Qinhuangdao, China
Qinhuangdao, China

Yanshan University is a university in Qinhuangdao, Hebei, China under the provincial government. It has student population of 38,000 and a staff population of 3000 .The origin of Yanshan University can be traced back to the Harbin Institute of Technology founded in 1920. In 1958, the Department of Heavy Machinery of HIT and its related specialties moved to the strategic industrial town of Fulaerji, Qiqihar in Northeast China's Heilongjiang Province and was renamed the School of Heavy Machinery of HIT. In 1960, the school became independent as the Northeast Heavy Machinery Institute, and in 1978, it was accredited as one of the eighty-eight national key institutions of higher learning. Starting in 1985, it began to relocate southward to the historic seaside city of Qinhuangdao in Hebei Province and completed the migration in 1997 when it was accredited by the former State Education Commission to adopt the present name of Yanshan University .The YSU campus covers an area of 5,000 mu with a total construction area of nearly one million square meters. At present, the university has a faculty and staff of 3000, including 2,000 teachers, of which 326 are professors and 422 are associate professors. The university has a student population of 38,000.YSU has five postdoctoral research stations, six disciplines of 35 subdisciplines conferring doctoral degrees, 13 disciplines of 80 subdisciplines conferring master degrees, 16 masters of engineering programs, one Master of Public Administration program, one Master of Business Administration program, as well as 60 undergraduate programs. With such a wide range of programs, YSU has become a multiversity with emphasis laid on engineering studies and importance attached to liberal arts, science, economics, management, law and education.YSU consists of twenty-one colleges and schools. YSU runs five national key disciplines, four key disciplines of national defense, thirteen key provincial disciplines, one key national laboratory, thirteen key provincial laboratories and engineering centers.YSU is known for its world-renowned achievements in the development of whole-set heavy machinery and equipment, the theory and technology of parallel robots, the technology of fluid transmission and electro-hydraulic servo-systems, the technology and equipment of precision plasticity figuration, technology of thermal treatment of big forging, the technology of mega amorphous bodies, metastable materials and technology, the theory and technology of industrial automation, etc.YSU has won seventeen national scientific and technological awards in a row since 1996, including three first-class China State Science and Technology Progress Awards, ten second-class Awards, two third-class Awards, one State Technology Invention Award, and one second-class National Natural science Award. The university has undertaken more than 300 national research projects, including those funded by the 973 Programs, the 863 Programs, as well as the National Natural science Foundation and the National Social science Foundation. In 1999, YSU established its high-tech park in the Qinhuangdao Economic and Technological Development Zone. The park was officially established by the Chinese Ministry of Science and Technology and Ministry of Education as a national university science park in September 2003, thus becoming one of the 34 national university science parks of its kind.The university also attaches great importance to international academic exchange and collaboration, and has conducted joint study and research programs with institutions from the United Kingdom, the United States, Canada, Norway, Germany, France, Italy, Ireland, Japan, Korea, etc.Qinhuangdao City in which YSU is located is a coastal resort city just 260 km northeast of Beijing. As one of the Class A tourist destinations in China, Qinhuangdao attracts visitors from China and abroad with the beginning of the Great Wall , the First Pass Under Heaven on the Great Wall, the summer resort Beidaihe Beach, the sandy Golden Beach at the Nandaihe area, the safari zoo, and other scenic spots which are all within easy access. Wikipedia.

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Jia Z.,Yanshan University | Jia Z.,Chengde Petroleum College | Yang Y.,Yanshan University
Composites Part B: Engineering | Year: 2012

The influences of normal contact pressure and sliding velocity on self-lubricating property of PTFE-based composite filled with nano-serpentine particles were mainly studied in the range of 0.12-0.96 m/s and 1.43-8.55 MPa. For comparison, the friction and wear experiments of pure PTFE also were carried out under the same conditions. A scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) were employed to examine the worn surfaces of PTFE/serpentine nanocomposite and transfer films. The experimental results showed that normal contact pressure and sliding velocity had significant effects on the tribological performances of PTFE/serpentine composite. Under different loads, the nanocomposite suffered from abrasive wear, fatigue wear and adhesive wear successively. And at different sliding velocity, the main wear mechanisms were abrasive wear and adhesive wear. SEM and EDS analyses indicated that the continuous and uniform transfer film generated on counterfaces acted as a solid lubricant, which was important to improve the self-lubricating property of PTFE/serpentine nanocomposite. © 2012 Elsevier Ltd. All rights reserved.

Fu X.,Yanshan University | Fu X.,Key Laboratory for Special Fiber and Fiber Sensor of Hebei Province | Xie H.,Yanshan University | Zeng X.,Shanghai University | And 4 more authors.
Optics Express | Year: 2015

A refractive index (RI) insensitive temperature sensor based on specialty triple-clad fiber (STCF) is proposed. Based on coupling mode theory, the STCF can be equivalent to a rod waveguide and two tube waveguides. Then the cladding mode resonance characteristic of STCF is analyzed by calculating different mode dispersion curves, which indicates that it works only on the mode resonance from core to the fluorine-doped silica cladding, and finally a resonance wavelength can be obtained. Two straightforward experiments are performed to prove its sensing properties. Experimental results show that it has sensitivities of 72.17 pm/°C at temperature range from 35°C∼95°C with characteristics of insensitive to external RI in the range from 1.3450 to 1.4607. Thus, this proposed sensor can be used for solution temperature monitoring in real time. © 2015 Optical Society of America.

Guo X.,Yanshan University | Zhang X.,University of Aalborg | Wang B.,Yanshan University
IEEE Transactions on Power Electronics | Year: 2014

This letter presents a new control strategy of three-phase grid-connected inverter for the positive sequence voltage recovery and negative sequence voltage reduction under asymmetrical grid faults. Unlike the conventional control strategy based on an assumption that the network impedance is mainly inductive, the proposed control strategy is more flexible and effective by considering the network impedance impact, which is of great importance for the high penetration of grid-connected renewable energy systems into low-voltage grids. The experimental tests are carried out to validate the effectiveness of the proposed solution for the flexible voltage support in a low-voltage grid, where the network impedance is mainly resistive. © 1986-2012 IEEE.

Guo X.,Yanshan University | Wu W.,Yanshan University | Chen Z.,University of Aalborg
IEEE Transactions on Industrial Electronics | Year: 2011

Synchronization with the utility networks is crucial for operating three-phase grid-interfaced converters. A challenge of synchronization is how to fast and precisely extract the fundamental positive and negative sequences under the distorted and unbalanced conditions. Many phase-locked loop (PLL) and synchronization techniques have been presented in the past decades. Most of them make a tradeoff between the accuracy and dynamic response under severe distorted and unbalanced conditions. In this paper, a multiple-complex coefficient-filter-based PLL is presented, and its unique feature lies in the accurate and rapid extraction of the positive and negative sequence components from the polluted grid voltage, and the harmonic components can also be estimated precisely, which has the potential use for selective compensation in active filter applications. Another advantage of the proposed method is its flexibility for simplifying its structure in some specified conditions. Results of continuous-domain simulations in MATLAB and discrete-domain experiments based on a 32-b fixed-point TMS320F2812 DSP are in good agreement, which confirm the effectiveness of the proposed method. © 2011 IEEE.

Qi X.,Yanshan University | Jia Z.,Yanshan University | Jia Z.,Chengde Petroleum College | Yang Y.,Yanshan University | Fan B.,Yanshan University
Tribology International | Year: 2011

Friction and wear experiments were carried out with nanoscale serpentine (a magnesium silicate mineral) and heat-treated serpentine as lubricating oil additives at 400 °C. The tribological test results showed that the self-repairing protective layers could be well formed on the contact surfaces, whether nanoscale serpentine or heat-treated serpentine powder was added into lubricating oil. SEM and EDAX analysis demonstrate that the morphology and elements of self-repairing layers are in accordance with that of serpentine. A generation mechanism of the layer was proposed from the view of isomorphic replacement theory in mineralogy and petrology, and friction-induced chemical reaction. © 2011 Elsevier Ltd. All rights reserved.

Liu H.,Yanshan University | Li B.,Yanshan University | Zheng L.,Yanshan University | Xu C.,Yanshan University | And 3 more authors.
Optics Letters | Year: 2013

We theoretically investigate the optical properties of a hybrid nanostructure consisting of one triangle and one nano-rod. A plasmon-induced transparency (PIT) resonance appears in the transmission spectrum, which is ascribed to the induced multipole plasmon mode of the nanorod. Multispectral PIT resonances are observed, when two or more nanorods are put in proximity to the triangle. It is proved that the combined effects of the induced multipole plas-mon mode of nanorods and the cavity resonant mode contribute to these PIT peaks. The tunability of PIT on the geometrical parameters is also presented. © 2013 Optical Society of America.

Song J.-S.,Duke University | Song J.-S.,Shanghai JiaoTong University | Zhang H.,Academia Sinica, China | Zhang H.,National University of Singapore | And 2 more authors.
Operations Research | Year: 2010

We study a single-item (r, q) inventory system, where r is the reorder point and q is the order quantity. The demand is a compound-Poisson process. We investigate the behavior of the optimal policy parameters and the long-run average cost of the system in response to stochastically shorter or less-variable lead times. We show that although some of the properties of the base-stock system can be extended to this more general model, some cannot. The same findings also apply when the comparison is conducted on the lead-time demand distributions. © 2010 INFORMS.

Ouyang G.,City University of Hong Kong | Ouyang G.,Yanshan University | Dang C.,City University of Hong Kong | Li X.,Yanshan University
Clinical Neurophysiology | Year: 2010

Objective: Ordinal patterns analysis such as permutation entropy of the EEG series has been found to usefully track brain dynamics and has been applied to detect changes in the dynamics of EEG data. In order to further investigate hidden nonlinear dynamical characteristics in EEG data for differentiating brain states, this paper proposes a novel dissimilarity measure based on the ordinal pattern distributions of EEG series. Methods: Given a segment of EEG series, we first map this series into a phase space, then calculate the ordinal sequences and the distribution of these ordinal patterns. Finally, the dissimilarity between two EEG series can be qualified via a simple distance measure. A neural mass model was proposed to simulate EEG data and test the performance of the dissimilarity measure based on the ordinal patterns distribution. Furthermore, this measure was then applied to analyze EEG data from 24 Genetic Absence Epilepsy Rats from Strasbourg (GAERS), with the aim of distinguishing between interictal, preictal and ictal states. Results: The dissimilarity measure of a pair of EEG signals within the same group and across different groups was calculated, respectively. As expected, the dissimilarity measures during different brain states were higher than internal dissimilarity measures. When applied to the preictal detection of absence seizures, the proposed dissimilarity measure successfully detected the preictal state prior to their onset in 109 out of 168 seizures (64.9%). Conclusions: Our results showed that dissimilarity measures between EEG segments during the same brain state were significant smaller that those during different states. This suggested that the dissimilarity measure, based on the ordinal patterns in the time series, could be used to detect changes in the dynamics of EEG data. Moreover, our results suggested that ordinal patterns in the EEG might be a potential characteristic of brain dynamics. Significance: This dissimilarity measure is a promising method to reveal dynamic changes in EEG, for example as occur in the transition of epileptic seizures. This method is simple and fast, so might be applied in designing an automated closed-loop seizure prevention system for absence epilepsy. © 2009 International Federation of Clinical Neurophysiology.

Zhang W.,China Institute of Technology | Niu P.,Yanshan University
Proceedings of the 2nd International Conference on Intelligent Control and Information Processing, ICICIP 2011 | Year: 2011

In this paper, a novel Chaotic Particle Swarm Optimization (CPSO) with simulated annealing algorithm (SACPSO) based scheme is proposed to choose the parameters of LS-SVM automatically. CPSO adopts chaotic mapping with certainty, ergodicity, and the stochastic property, possessing high search efficiency. SA algorithm employs certain probability to improve the ability of PSO to escape from a local optimum and has fast convergence and high computational precision. The hybrid algorithm is applied to a turbine heat rate modeling. The simulation results have shown that the performance of the hybrid algorithm is better than of the Particle Swarm Optimization (PSO), and the hybrid algorithm is effective and feasible for solving the problem of predicting heat rate. © 2011 IEEE.

Guo X.,Yanshan University | Guerrero J.M.,University of Aalborg
IEEE Transactions on Smart Grid | Year: 2016

Current regulation is crucial for operating singlephase grid-connected inverters. The challenge of the current controller is how to fast and precisely track the current with zero steady-state error. This paper proposes a novel feedback mechanism for the conventional proportional integral controller. It allows the steady-state error suppression with no need of additional complex control algorithms such as the synchronous reference frame transformation. Five alternative implementation methods are comparatively evaluated from the viewpoint of the steady-state and dynamic responses. Further, the theoretical analysis done indicates that the widely used P+Resonant control is just a special case of the proposed control solution. The time-domain simulation in MATLAB/Simulink and experimental results from a TMS320F2812 DSP-based laboratory prototypes are in good agreement, which verify the effectiveness of the proposed generalized method. © 2015 IEEE.

Niu P.,Yanshan University | Zhang W.,Yanshan University | Zhang W.,China Institute of Technology
Neurocomputing | Year: 2012

Ascertaining real time optimal initial pressure has important significance to safeguard the economic, efficient and safe operation of turbine units. In this paper, a new calculation model of the optimal initial pressure under off-design conditions has been put forward. Support Vector Regression (SVR) is used to build the model of heat rate and the optimal selection approach of SVR parameters is discussed. Heat rate is chosen as the fitness function, and then Genetic Algorithm (GA) is applied to seek the optimal initial pressure within the feasible pressure range depend on its global optimal search capability. The obtained optimal initial pressure can effectually guide the economical operation of turbine unit. © 2011 Elsevier B.V.

Li D.,Yanshan University | Li X.,Beijing Normal University | Hagihira S.,Osaka University | Sleigh J.W.,Waikato Hospital
British Journal of Anaesthesia | Year: 2013

BackgroundFourier bicoherence has previously been applied to investigate phase coupling in the EEG in anaesthesia. However, there are significant theoretical limitations regarding its sensitivity in detecting transient episodes of inter-frequency coupling. Therefore, we used a recently developed wavelet bicoherence method to investigate the cross-frequency coupling in the EEG of patients under isoflurane anaesthesia; examining the relationship between the patterns of wavelet bicoherence and the isoflurane concentrations.MethodsWe analysed a set of previously published EEG data, obtained from 29 patients who underwent elective abdominal surgery under isoflurane anaesthesia. Artifact-free, 1 min EEG segments at different isoflurane concentrations were extracted from each subject and the wavelet bicoherence calculated for all pairs of frequencies from 0.5 to 20 Hz.ResultsIsoflurane caused two peaks in the α (6-13 Hz) and slow δ (<1 Hz) regions of the bicoherence matrix diagonal. Higher concentrations of isoflurane shifted the α peak to lower frequencies [11.3 (0.9) Hz at 0.3% to 7.1 (1.2) Hz at 1.5%], as has been previously observed in the power spectra. Outside the diagonal, we also found a significant α peak that was phase-coupled to the slow δ waves; higher concentrations of isoflurane shifted this peak to lower frequencies [10.8 (1.2) to 7.7 (0.7) Hz].ConclusionsIsoflurane caused cross-frequency coupling between α and slow δ waves. Increasing isoflurane concentration slowed the α frequencies where the coupling had occurred. This phenomenon of α-δ coupling suggests that slow cortical oscillations organize the higher α band activity, which is consistent with other studies in natural sleep. © The Author [2012].

Lin Y.,Yanshan University | Xu B.,Yanshan University | Feng Y.,Yanshan University | Lavernia E.J.,University of California at Davis
Journal of Alloys and Compounds | Year: 2014

In this study we analyze the phenomenon of stress-induced grain growth in nanostructured Al containing a high volume fraction of nanoscale oxide particles during high-temperature extrusion. Our results show that in the absence of an externally applied stress, grain growth was essentially inhibited during annealing at 600 C. In contrast, when the same material was extruded at 400 C, the grains increased in size by a factor of 2.2 relative to the initial microstructure. The experimental results were analyzed on the basis of the mechanisms that govern grain growth. We discuss the role of grain boundary (GB) migration, grain rotation, discontinuous dynamic recrystallization and geometric dynamic recrystallization on stress-induced grain growth. Finally, the influence of nanoscale oxide particles on GB migration and grain rotation was rationalized on the basis of a theoretical model.© 2014 Elsevier B.V. All rights reserved.

Nie G.,Shijiazhuang University | Liu J.,Shijiazhuang University | Fang X.,Shijiazhuang University | An Z.,Yanshan University
Acta Mechanica | Year: 2012

This work considers the propagation of shear horizontal (SH) waves in a bilayer system consisting of a piezoelectric (PE) layer and a piezomagnetic (PM) substrate. The interface between the PE layer and the PM substrate is imperfectly bonded. The surfaces of the bilayer system are free of traction, electrically shorted or open and magnetically open or shorted. The exact dispersion equations are derived. The numerical examples are given to illustrate the effects of the electromagnetic boundary conditions, the imperfect interface, the different PE layers and the thickness ratio on the dispersion behaviors. It is found that (a) the electrical boundary conditions dominate the propagation characteristics of SH waves; (b) the imperfect bonding lowers the phase velocities; (c) the thickness ratio and the properties of PE layers have a significant effect on the dispersion behaviors. The obtained results provide a predictable and theoretical basis for applications of PE-PM composites to acoustic wave devices. © Springer-Verlag 2012.

Qi X.,Yanshan University | Lu L.,Yanshan University | Jia Z.,Yanshan University | Jia Z.,Chengde Petroleum College | And 2 more authors.
Tribology International | Year: 2012

Friction and wear experiments were carried out with nanoscale serpentine (magnesium silicate mineral) and magnesium hexasilicate powder as lubricating oil additives at 400 °C. The tribological test results showed that the self-repairing protective layers could be well formed on the contact surfaces, whether nanoscale serpentine or magnesium hexasilicate powder was added into lubricating oil. The SEM and EDAX analysis demonstrate that the morphology and elements of both self-repairing layers are in accordance with each other. The research results indicate that the essence of self-repairing of serpentine power is isomorphic replacement and tribochemical reaction between magnesium silicate and metal matrix. © 2011 Elsevier Ltd. All rights reserved.

Qi X.,Yanshan University | Jia Z.,Yanshan University | Jia Z.,Chengde Petroleum College | Yang Q.,Yanshan University | Yang Y.,Yanshan University
Surface and Coatings Technology | Year: 2011

Hard and wear-resistance layer of high chromium cast iron (HCCI) with vanadium additive was prepared by surfacing technology. Using DSC the phase transition temperature curve of surfacing alloy layer was examined. The content of carbide in hardfacing layer was further determined through microstructure analysis. Meanwhile, iron-carbon equilibrium phase diagram of hardfacing layer was calculated. In addition, the wear-resistance of hardfacing layer was carried out. The results show that the carbide precipitated from hardfacing layer is the type of M7C3. Primary, eutectic and secondary carbides are approximately hexagonal structure, long rods and fine spherical, respectively. However, the secondary carbide VC is precipitated from the hardfacing layer when vanadium additive was added into flux cored wire. As the content of vanadium additive increases in the flux-cored wire, the size of primary carbide significantly reduces and the amount of eutectic and secondary carbides gradually increase. Therefore, the improvement of wear-resistance of surfacing layer was mainly due to the vanadium additive in flux-cored wire. © 2011 Elsevier B.V.

Cui D.,Yanshan University | Liu X.,Peking University | Wan Y.,Peking University | Li X.,Yanshan University
Neural Networks | Year: 2010

Synchronization is an important mechanism that helps in understanding information processing in a normal or abnormal brain. In this paper, we propose a new method to estimate the genuine and random synchronization indexes in multivariate neural series, denoted as GSI (genuine synchronization index) and RSI (random synchronization index), by means of a correlation matrix analysis and surrogate technique. The performance of the method is evaluated by using a multi-channel neural mass model (MNMM), including the effects of different coupling coefficients, signal to noise ratios (SNRs) and time-window widths on the estimation of the GSI and RSI. Results show that the GSI and the RSI are superior in description of the synchronization in multivariate neural series compared to the S-estimator. Furthermore, the proposed method is applied to analyze a 21-channel scalp electroencephalographic recording of a 35 year-old male who suffers from mesial temporal lobe epilepsy. The GSI and the RSI at different frequency bands during the epileptic seizure are estimated. The present results could be helpful for us to understand the synchronization mechanism of epileptic seizures. © 2010 Elsevier Ltd.

Li Z.,Yanshan University | Li X.,Beijing Normal University
PLoS ONE | Year: 2013

Estimating the causal interaction between neurons is very important for better understanding the functional connectivity in neuronal networks. We propose a method called normalized permutation transfer entropy (NPTE) to evaluate the temporal causal interaction between spike trains, which quantifies the fraction of ordinal information in a neuron that has presented in another one. The performance of this method is evaluated with the spike trains generated by an Izhikevich's neuronal model. Results show that the NPTE method can effectively estimate the causal interaction between two neurons without influence of data length. Considering both the precision of time delay estimated and the robustness of information flow estimated against neuronal firing rate, the NPTE method is superior to other information theoretic method including normalized transfer entropy, symbolic transfer entropy and permutation conditional mutual information. To test the performance of NPTE on analyzing simulated biophysically realistic synapses, an Izhikevich's cortical network that based on the neuronal model is employed. It is found that the NPTE method is able to characterize mutual interactions and identify spurious causality in a network of three neurons exactly. We conclude that the proposed method can obtain more reliable comparison of interactions between different pairs of neurons and is a promising tool to uncover more details on the neural coding. © 2013 Li, Li.

Yang Y.,Nanjing University of Posts and Telecommunications | Yue D.,Nanjing University of Posts and Telecommunications | Dou C.,Yanshan University
Information Sciences | Year: 2016

In this paper, we consider a leader-follower output consensus problem for a class of uncertain heterogeneous non-affine pure-feedback multi-agent systems (MASs) in the presence of time-delay items and input saturation restrictions under switching directed topologies. A distributed adaptive control scheme is constructed by combining Lyapunov-Krasovskii functionals, backstepping methods, neural networks (NNs), auxiliary systems, graph theory, the mean value theorem and the implicit function theory along with the dynamic surface control (DSC) technique. The key advantages of the designed control approach are that there is no requirement of precise knowledge about uncertain dynamics and time-delay items of individual agents and the computational burden can drastically be reduced by employing the DSC technique. Also, norms of unknown weight of neural networks are estimated online instead of weight vectors themselves. In theory, it can be proven that the output signals of follower agents can synchronize with the leader's and all signals in the closed-loop system are cooperatively semiglobally uniformly ultimately bounded (CSUUB) by suitable choice of design parameters. Two simulation examples are presented to demonstrate the effectiveness of the proposed strategy. © 2016 Elsevier Inc. All rights reserved.

Jia Z.-n.,Yanshan University | Jia Z.-n.,Chengde Petroleum College | Yang Y.-l.,Yanshan University | Chen J.-j.,Yanshan University | Yu X.-j.,Yanshan University
Wear | Year: 2010

This paper presents a PTFE/serpentine solid lubricant composite that exhibits low friction coefficient and low wear rate. It is postulated that synergistic effect alters the dominant wear mechanism of PTFE matrix. In order to examine the influence of serpentine content on tribological properties of PTFE/serpentine composite, six blends of PTFE with serpentine (in the range of 0-30 wt.%) were evaluated using a MMU-5G friction and wear tester. Tests were carried out in standard laboratory conditions with a nominal contact pressure of 2.85 MPa and a sliding speed of 0.48 m/s. The friction coefficient of the composite, which was weakly dependent on serpentine content, was stable roughly from μ = 0.10 to 0.12 during steady friction. Compared with the wear rate of unfilled PTFE, the wear resistance of PTFE/serpentine composite increased 24 times. However, the content of serpentine (5-30 wt.%) had little effect on wear rate of composite. The images of confocal laser scanning microscope (CLSM) revealed that the hybrid transfer film generated on the surface of mating pair is likely responsible for the lower wear rate obtained in these experiments. © 2009 Elsevier B.V. All rights reserved.

Wang Z.-J.,University Of Science And Technology Liaoning | Yang Q.-X.,Yanshan University | Qiao J.,University Of Science And Technology Liaoning
Transactions of Nonferrous Metals Society of China (English Edition) | Year: 2010

The phase structure of ZK60-1Er magnesium alloy thermally compressed at the temperature of 450 °C and the strain rate of 1×10-4 s -1 was determined by transmission electron microscopy (TEM) and high-resolution electron microscopy (HREM). The results show that this magnesium alloy contains many new W phases (Mg3Zn3Er2, FCC structure) in the matrix. Those new W phases have two morphologies, either irregularly rectangular or rod morphology. Lattice constants of the two new W phases are slightly higher than those of W Phase (Mg3Zn 3Y2) containing rare earth element of yttrium. © 2010 The Nonferrous Metals Society of China.

Qi X.,Yanshan University | Jia Z.,Chengde Petroleum College | Yang Y.,Yanshan University
Journal of Applied Polymer Science | Year: 2013

Nanoparticles with unique properties have been widely used in various fields. The tribological performance of the fabric self-lubricating liner, which is used as the main component of spherical plain bearings, directly affects the bearing service life. The purpose of this study was to prepare a self-lubricating liner enhanced with nano titanium dioxide (nano-TiO 2) by dispersion technology. The effects of several factors on the dispersion of nano-TiO2 were studied in detail. The effects of the dispersion of nano-TiO2 on the tribological properties of a self-lubricating liner were analyzed comparatively. The best dispersing conditions were determined through experiments and statistical characterization. From the results of the tribological tests, the fabric self-lubricating liner reinforced with nano-TiO2 showed better antifriction and wear-resistant properties than that without nanoparticles. © 2013 Wiley Periodicals, Inc.

Guo X.,Yanshan University | Cavalcanti M.C.,Federal University of Pernambuco | Farias A.M.,Federal University of Pernambuco | Guerrero J.M.,University of Aalborg
IEEE Transactions on Power Electronics | Year: 2013

Modulation strategy is one of the most important issues for three-level neutral-point-clamped inverters in three-phase transformerless photovoltaic systems. A challenge for modulation is how to keep the common-mode voltages constant to reduce the leakage currents. Asingle-carrier modulation strategy is proposed. It has a very simple structure, and the common-mode voltages can be kept constant with no need of complex space-vector modulation or multicarrier pulsewidth modulation. Experimental results verify the theoretical analysis and the effectiveness of the presented method. © 2013 IEEE.

Wang D.,Yanshan University | Wang D.,China Institute of Technology | Zhang W.,Yanshan University
Zhongguo Jixie Gongcheng/China Mechanical Engineering | Year: 2012

For the modulation and energy concentration feature of fault ball bearing vibration signals, a fault diagnosis study based on wavelet packet energy and Hilbert transform was put forward. The vibration signals of ball bearing were decomposed and reconstructed using wavelet packet transform. And energy of every frequency band was calculated, then the signals of the frequency band with maximal energy were analyzed by applying Hilbert transform. Finally, the characteristic frequency of fault signals was extracted. The computation of fault features was accomplished artificially. A new method which can select fault features automatically was presented herein. Through processing and analyzing the practical ball bearing experimental data, it is shown that the fault diagnosis study can diagnose different running states of ball bearings due to surface damage accurately and quickly.

Wang S.R.,Yanshan University | Jia H.H.,Chengde Petroleum College
Applied Mechanics and Materials | Year: 2012

Under low stress conditions, when the load exerting on the mined-out areas roof is less than the rock long-term strength, the rock roof will generate some creep deformation. In order to prevent the roof of the mined-out areas suddenly collapse, and to ensure the operator and construction equipment above the mined-out areas safety, it is an important security technical problem to reveal the creep characteristics of the shallow mined-out areas roof. Taking the mined-out areas of Antaibao Surface Mine as background, considering the rheological properties of rock roof, and assuming the roof was a rectangular thick plate, the creep characteristics of mined-out areas roof were analysed by applying the thick plate theory and Kelvin creep model. The regression equation of the roof deflection increment over time was given, and the creep characteristics of the shallow mined-out areas roof were revealed also. The above results can provide a theoretical basis to ensure the surface mine safety construction, which has some reference to similar engineering. © (2012) Trans Tech Publications.

Zhang W.,Yanshan University | Zhang W.,China Institute of Technology | Niu P.,Yanshan University | Niu P.,National Engineering Research Center for Equipment and Technology of Cold Strip Rolling | And 4 more authors.
Knowledge-Based Systems | Year: 2013

Accurate heat rate forecasting is very important in ensuring the economic, efficient, and safe operation of a steam turbine unit. The support vector machine (SVM) is a novel tool from the artificial intelligence field that has been successfully applied to heat rate forecasting. The least squares SVM (LS-SVM) is an improved algorithm based on the SVM. LS-SVM has minimal computational complexity and fast calculation. However, traditional LS-SVM, which was established by using offline data samples, can no longer accurately describe the actual system working condition, thereby resulting in problems when directly used in heat rate prediction. In this paper, a heat rate forecasting method based on online LS-SVM, which possesses dynamic prediction functions, is proposed. To avoid blindness and inaccuracy in parameter selection, the gravitational search algorithm (GSA) is used to optimize the regularization parameter γ and the kernel parameter σ2 of the online LS-SVM modeling. The results confirm the efficiency of the proposed method. © 2012 Elsevier B.V. All rights reserved.

Sun X.,Yanshan University | Zeng J.,Yanshan University | Chen Z.,University of Aalborg
IEEE Transactions on Power Electronics | Year: 2013

Series resonance between capacitance and line inductance may magnify background harmonic voltage and worsen the harmonic voltage distortion in power systems. To solve this problem, in this paper, the transmission line theory is used to set up the distributed parameter model of power system feeders, and analyze the harmonic voltage propagation caused by the background harmonic voltage in power systems. Then, a new strategy is proposed for the site selection of resistive active power filter to damp the background harmonic voltage in power systems. Experiments have been performed to verify the theoretical analysis and demonstrate the effectiveness of the proposed strategy. © 1986-2012 IEEE.

Bian Z.,Yanshan University | Li Q.,The Second Artillery General Hospital of PLA | Wang L.,The Second Artillery General Hospital of PLA | Lu C.,Yanshan University | And 2 more authors.
Frontiers in Aging Neuroscience | Year: 2014

Objective: Diabetes is a risk factor for dementia and mild cognitive impairment. The aim of this study was to investigate whether some features of resting-state EEG (rsEEG) could be applied as a biomarker to distinguish the subjects with amnestic mild cognitive impairment (aMCI) from normal cognitive function in type 2 diabetes. Materials and Methods: In this study, 28 patients with type 2 diabetes (16 aMCI patients and 12 controls) were investigated. Recording of the rsEEG series and neuropsychological assessments were performed. The rsEEG signal was first decomposed into delta, theta, alpha, beta, gamma frequency bands. The relative power of each given band/sum of power and the coherence of waves from different brain areas were calculated. The extracted features from rsEEG and neuropsychological assessments were analyzed as well. Results: The main findings of this study were that: (1) compared with the control group, the ratios of power in theta band [P(theta)] vs. power in alpha band [P(alpha)] [P(theta)/P(alpha)] in the frontal region and left temporal region were significantly higher for aMCI, and (2) for aMCI, the alpha coherences in posterior, fronto-right temporal, fronto-posterior, right temporo-posterior were decreased; the theta coherences in left central-right central (LC-RC) and left posterior-right posterior (LP-RP) regions were also decreased; but the delta coherences in left temporal-right temporal (LT-RT) region were increased. Conclusion: The proposed indexes from rsEEG recordings could be employed to track cognitive function of diabetic patients and also to help in the diagnosis of those who develop aMCI. © 2014 Bian, Li, Wang, Lu, Yin and Li.

Zhao Q.,Yanshan University | Zhang J.,Dezhou Power Supply Company
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2013

A passive lossless snubber based on magnetic coupling is proposed, which restrains the reverse recovery current and reduces the overlapping area of voltage and current during the turning-on period of switch. Therefore, the efficiency of PFC(Power Factor Correction) is enhanced and the EMI(ElectroMagnetic Interference) reduced. The energy is absorbed and transferred through the resonance of snubber inductor and capacitor. The coupled winding makes the energy of snubber inductor easy to be reset and no additional voltage stress is introduced by the snubber to the switch. The operating principle of snubber and the parameters design of key passive components are presented in detail. The experimental waveforms and efficiency comparison tests of 500 W prototype show the high efficiency of the proposed snubber.

Lin Y.,Yanshan University | Zhang Y.,General Research Institute for Nonferrous Metals, China | Xiong B.,General Research Institute for Nonferrous Metals, China | Lavernia E.J.,University of California at Davis
Materials Letters | Year: 2012

An ultra-fine grained (UFG) 5083 Al produced by conventional extrusion of a fine-grained (FG) precursor exhibits a high tensile elongation (15.7% of uniform elongation in engineering strain) and a reasonably high tensile strength. In light of our results, the high tensile elongation is primarily attributable to the low dislocation density (5 × 10 12 m - 2) in the UFG 5083 Al. The low dislocation density effectively improves the tensile elongation of an UFG material via two possible mechanisms: (i) enhancing the formation of dislocation tangling and (ii) minimizing the possibility of localized shear banding. Moreover, our results suggest that conventional plastic deformation of FG precursor materials provides a feasible approach for the synthesis of UFG materials that contain a low density of dislocations. © 2012 Elsevier B.V. All rights reserved.

Yang H.,Yanshan University | Shi P.,University of Adelaide | Shi P.,Victoria University of Melbourne | Li X.,Yanshan University | Li Z.,Yanshan University
Signal Processing | Year: 2014

This paper studies a fault-tolerant control scheme for T-S fuzzy models based on delta operator approach. A fuzzy fault detection observer is constructed by means of T-S fuzzy delta operator systems. Moreover, a new approach is established for the estimation of faults in a class of nonlinear systems. The proposed fault-detection observer can be obtained in terms of the solvability of linear matrix inequalities. Then, an active fault-tolerant controller is designed to compensate for the effect of the faults and makes the closed-loop fuzzy delta operator system stable. A numerical example is provided to illustrate the effectiveness of the proposed design techniques. © 2013 Elsevier B.V.

Wang L.,Yanshan University | Guo X.Q.,Yanshan University | Gu H.R.,Yanshan University | Wu W.Y.,Yanshan University | Guerrero J.M.,University of Aalborg
IEEE International Symposium on Industrial Electronics | Year: 2012

This paper deals with the precise modeling of droop controlled parallel inverters. This is very attractive since that is a common structure that can be found in a stand-alone droop-controlled MicroGrid. The conventional small-signal dynamic is not able to predict instabilities of the system, so that in this paper, the combination of both small signal model and dynamic phasor model (DPM) of parallel-connected inverters is presented. Simulation results show that the dynamic phasor model is able to predict accurately the stability margins of the system when the droop control gains exceed certain values. In addition, the virtual ω-E frame power control method, which deals with the power coupling caused by the line impedance X/R characteristic, has been chosen as an application example of this modeling technique. © 2012 IEEE.

Yang H.,Yanshan University | Xia Y.,Beijing Institute of Technology | Shi P.,University of Adelaide | Shi P.,Victoria University of Melbourne | Liu B.,Beijing Institute of Technology
International Journal of Adaptive Control and Signal Processing | Year: 2013

SUMMARY In this paper, the problem of guaranteed cost control for networked control systems is addressed by using delta operator Kalman filter approach. To cope with network-induced delays and packet dropout, we take into account the quality-of-service of networks. The networked control system is described as a kind of delayed Markovian jump delta operator systems. Sufficient conditions for the solvability of underlying problem are derived in terms of linear matrix inequalities. A numerical example is given to illustrate the effectiveness of the developed techniques. Copyright © 2012 John Wiley & Sons, Ltd. Copyright © 2012 John Wiley & Sons, Ltd.

Fang S.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | Fang S.,Chinese Academy of Sciences | Xu L.,CAS Institute of Computing Technology | Xu L.,Old Dominion University | And 6 more authors.
IEEE Transactions on Industrial Informatics | Year: 2014

Water scarcity and floods are the major challenges for human society both present and future. Effective and scientific management of water resources requires a good understanding of water cycles, and a systematic integration of observations can lead to better prediction results. This paper presents an integrated approach to water resource management based on geoinformatics including technologies such as Remote Sensing (RS), Geographical Information Systems (GIS), Global Positioning Systems (GPS), Enterprise Information Systems (EIS), and cloud services. The paper introduces a prototype IIS called Water Resource Management Enterprise Information System (WRMEIS) that integrates functions such as data acquisition, data management and sharing, modeling, and knowledge management. A system called SFFEIS (Snowmelt Flood Forecasting Enterprise Information System) based on the WRMEIS structure has been implemented. It includes operational database, Extraction-Transformation-Loading (ETL), information warehouse, temporal and spatial analysis, simulation/prediction models, knowledge management, and other functions. In this study, a prototype water resource management IIS is developed which integrates geoinformatics, EIS, and cloud service. It also proposes a novel approach to information management that allows any participant play the role as a sensor as well as a contributor to the information warehouse. Both users and public play the role for providing data and knowledge. This study highlights the crucial importance of a systematic approach toward IISs for effective resource and environment management. © 2005-2012 IEEE.

Li Y.,University of California at Davis | Lin Y.J.,University of California at Davis | Lin Y.J.,Yanshan University | Xiong Y.H.,University of California at Davis | And 2 more authors.
Scripta Materialia | Year: 2011

Extended twins, up to 100 nm in length and occupying the length of an entire grain, are observed in an Al-4%Mg alloys/B4C nanocomposite material processed via high-temperature, high-strain-rate forging. High-resolution electron microscopy, used to identify the extended twins and to formulate the mechanism for their formation, indicates that they are created by the emission of 1/6h1 1 2i twinning partial dislocations. The macroscopic origin is attributed to the local high stress field present during the forging process. © 2010 Acta Materialia Inc.

Dong M.,Yanshan University | Liu C.,Yanshan University
IEEE Transactions on Control Systems Technology | Year: 2010

A nonlinear model of a hydraulic automatic gauge control (AGC) system is established for fault detection and isolation (FDI). By analyzing the relationship between faults and load uncertainties, a decoupling subsystem has been derived using a differential geometric approach. An exponential gain observer has been designed based on the observable decoupling subsystem. Diagnosis residual signal is sensitive to designated faults and robust to load uncertainty. Two real data examples verify that the observer is stable and asymptotically convergent. The correctness and superiority are testified by actual data examples. © 2009 IEEE.

Li D.,Yanshan University | Voss L.J.,University of Auckland | Sleigh J.W.,University of Auckland | Li X.,Beijing Normal University
Anesthesiology | Year: 2013

Background: The exact neurophysiological mechanisms of anesthetic-induced unconsciousness are not yet fully elucidated. The cortical information integration theory hypothesizes that loss of consciousness during general anesthesia is associated with breakdown of long-distance cortical connectivity across multiple brain regions. However, what is the effect of anesthetics on neural activities at a smaller spatial scale? Methods: The authors analyzed a set of previously published eight-channel electrocorticogram data, obtained from a 14-mm-long linear array of electrodes in eight adult merino sheep during general anesthesia induced by sevoflurane, desflurane, isoflurane, and enflurane. The S-estimator was applied to the bi-channel coherence matrix to construct an overall index called the SI, which is the entropy of the eigenvalues of the cortical coherence for each pair of channels within the multichannel electrocorticographic dataset. Results: The SI values increased ~30-50% from the waking to the burst-suppression states, and returned to baseline during recovery. The anesthetic-induced increase in synchrony was most marked in the α (8-13 Hz) and β (13-30 Hz) frequency bands (P < 0.05). Using prediction probability (PK) analysis, we found a significant correlation between the increase in spatial synchrony (as estimated by the SI at various frequency bands) and anesthetic-induced cortical depression (as estimated by the approximate entropy). Conclusions: The results suggest that it is feasible to use the SI to measure cortical synchrony, and over a local spatial scale of 2-14 mm, synchrony increased during general anesthesia. Copyright © 2013, the American Society of Anesthesiologists, Inc. Lippincott Williams & Wilkins.

Pang L.,Yanshan University | Zhao M.,Yanshan University | Zhao X.,Shanghai JiaoTong University | Chai Y.,Shijiazhuang University
Journal of Power Sources | Year: 2012

In this paper, LiFe 1-xGd xPO 4/C composites (x = 0, 0.02, 0.04, 0.06, 0.07, 0.08) are synthesized via a high-temperature solid-phase reaction. The structure and electrochemical behavior of the materials are investigated using a wide range of techniques such as X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), particle size analysis, galvanostatic charge/discharge and electrochemical impedance spectroscopy (EIS). It is found that the maximum discharge capacity of the as-prepared LiFe 0.93Gd 0.07PO 4/C composite can reach up to 150.7 mAh g -1, 125.9 mAh g -1, 106.0 mAh g -1 and 81.3 mAh g -1 at rates of 0.2 C, 1 C, 5 C and 10 C, respectively. And at 0.1 C rate, the initial discharge capacity of the composite monotonically increases with temperature from 66.3 to 122.2 mAh g -1 in the range of -30 to 0 °C. It is also demonstrated that the presence of a small amount of Gd 3+ ion in the sample prepared in this work can reduce the charge-transfer resistance, resulting in the enhanced electrochemical catalytic activity. © 2011 Elsevier B.V.

Ouyang G.,Yanshan University | Li J.,University of Sheffield | Li J.,Nanchang University | Liu X.,Peking University | And 2 more authors.
Epilepsy Research | Year: 2013

Understanding the transition of brain activities towards an absence seizure, called pre-epileptic seizure, is a challenge. In this study, multiscale permutation entropy (MPE) is proposed to describe dynamical characteristics of electroencephalograph (EEG) recordings on different absence seizure states. The classification ability of the MPE measures using linear discriminant analysis is evaluated by a series of experiments. Compared to a traditional multiscale entropy method with 86.1% as its classification accuracy, the classification rate of MPE is 90.6%. Experimental results demonstrate there is a reduction of permutation entropy of EEG from the seizure-free state to the seizure state. Moreover, it is indicated that the dynamical characteristics of EEG data with MPE can identify the differences among seizure-free, pre-seizure and seizure states. This also supports the view that EEG has a detectable change prior to an absence seizure. © 2012 Elsevier B.V.

Ding H.,Yanshan University | Ding H.,Key Laboratory of Industrial Computer Control Engineering of Hebei Province | Hou F.,Key Laboratory of Industrial Computer Control Engineering of Hebei Province | Kecskemethy A.,University of Duisburg - Essen | Huang Z.,Yanshan University
Mechanism and Machine Theory | Year: 2012

Obtaining all the independent kinematic structures of mechanisms is very helpful for the selection of the most suitable candidate at the conceptual design stage of mechanisms. This paper proposes a fully-automatic method to synthesize the whole family of planar 1-DOF (degrees of freedom) kinematic chains with different links, and the corresponding atlas databases containing all the classified topological graphs are also established. The topological graph and the contracted graph are used to represent the topological structures of kinematic chains. The contracted graphs and valid contracted graphs of 1-DOF kinematic chains with different numbers of links are synthesized first. All the topological graphs are then synthesized from the corresponding valid contracted graphs. The atlas database of 1-DOF kinematic chains with 6, 8, 10, 12 and 14 links, which contains all the valid topological graphs classified by their structure characteristics, is also established and illustrated at the end of the paper, proving the effectiveness of the method. © 2011 Elsevier Ltd. All rights reserved.

Yu S.,Yanshan University | Li Y.,Yanshan University | Pan N.,University of California at Davis
RSC Advances | Year: 2014

The importance of developing high-performance electrode materials with low cost for supercapacitors is self-evident. In this paper, composites of KOH activated carbon/graphene nanosheets were prepared via a simple hydrothermal treatment of graphite oxide and KOH activated carbon. The electrochemical experiments that were conducted demonstrate that these composites exhibited synergistically improved electrochemical performance as electrodes in a supercapacitor. The specific capacitance of these composites can reach as high as 205 and 173 F g-1 in 6 M KOH aqueous solution and 1 M TEABF4 in acetonitrile solution, respectively. In addition, the as fabricated electrodes that were obtained using these composites show a reduced internal resistance and higher capacitance retention performance. Furthermore, the entire preparation process is simple, low cost and easily scalable to mass production, leading to great potential application in supercapacitors for as prepared composites. © the Partner Organisations 2014.

Zhou J.,Yanshan University | Bao Z.,National University of Singapore | Wang W.,University of New South Wales | Ling T.W.,National University of Singapore | And 3 more authors.
Proceedings - International Conference on Data Engineering | Year: 2012

In this paper, we focus on efficient keyword query processing for XML data based on the SLCA and ELCA semantics. We propose a novel form of inverted lists for keywords which include IDs of nodes that directly or indirectly contain a given keyword. We propose a family of efficient algorithms that are based on the set intersection operation for both semantics. We show that the problem of SLCA/ELCA computation becomes finding a set of nodes that appear in all involved inverted lists and satisfy certain conditions. We also propose several optimization techniques to further improve the query processing performance. We have conducted extensive experiments with many alternative methods. The results demonstrate that our proposed methods outperform previous methods by up to two orders of magnitude in many cases. © 2012 IEEE.

Tian N.-S.,Yanshan University
International Journal of Information and Management Sciences | Year: 2010

This paper studies a fluid model driven by an M/M/l/N queue with single exponential vacation. With the standard spectral method, the exact expression of the steady-state distribution of the buffer content is acquired. Then the performance measure- mean buffer content is obtained. Finally, using the numerical example, we present the parameter effect on the stationary distribution of the buffer content.

Zhang X.,Yanshan University | Hu S.,Yanshan University | Chen D.,Wuhan University | Chen D.,University of Birmingham | And 2 more authors.
IEEE Transactions on Industrial Informatics | Year: 2012

The exiting covariance matching method is not suited for real-time applications due to its demand for exhaustive search. Aiming at this problem, we developed a novel approach based on fuzzy genetic algorithm (GA) to boost the computing efficiency of covariance matching. The approach employs GA in searching for optimal solution in a large image region. To avoid premature convergence or local optimum which often occur in traditional GAs, we use a fuzzy inference system to adaptively estimate the crossover and mutation probabilities to gain convergence in a much higher speed than using a conventional GA. Experimental results show that the proposed approach can significantly improve the processing speed of covariance matching, while keeping the matching results almost unchanged. The runtime performance of the proposed approach is faster than its counterparts using exhaustive search with eight times and more. © 2006 IEEE.

Li Z.,Yanshan University | Ouyang G.,Yanshan University | Li D.,Yanshan University | Li X.,Yanshan University | Li X.,Beijing Normal University
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2011

Uncovering the causal relationship between spike train recordings from different neurons is a key issue for understanding the neural coding. This paper presents a method, called permutation conditional mutual information (PCMI), for characterizing the causality between a pair of neurons. The performance of this method is demonstrated with the spike trains generated by the Poisson point process model and the Izhikevich neuronal model, including estimation of the directionality index and detection of the temporal dynamics of the causal link. Simulations show that the PCMI method is superior to the transfer entropy and causal entropy methods at identifying the coupling direction between the spike trains. The advantages of PCMI are twofold: It is able to estimate the directionality index under the weak coupling and against the missing and extra spikes. © 2011 American Physical Society.

Hao Y.-J.,Yanshan University | Srivastava H.M.,University of Victoria | Jafari H.,University of Mazandaran | Yang X.-J.,China University of Mining and Technology
Advances in Mathematical Physics | Year: 2013

The main object of this paper is to investigate the Helmholtz and diffusion equations on the Cantor sets involving local fractional derivative operators. The Cantor-type cylindrical-coordinate method is applied to handle the corresponding local fractional differential equations. Two illustrative examples for the Helmholtz and diffusion equations on the Cantor sets are shown by making use of the Cantorian and Cantor-type cylindrical coordinates. © 2013 Ya-Juan Hao et al.

Chen D.,China University of Geosciences | Li X.,Beijing Normal University | Cui D.,Yanshan University | Wang L.,China University of Geosciences | Lu D.,Yanshan University
IEEE Transactions on Neural Systems and Rehabilitation Engineering | Year: 2014

The estimation of synchronization amongst multiple brain regions is a critical issue in understanding brain functions. There is a lack of an appropriate approach which is capable of 1) measuring the direction and strength of synchronization of activities of multiple brain regions, and 2) adapting to the quickly increasing sizes and scales of neural signals. Nonlinear Interdependence (NLI) analysis is an effective method for measuring synchronization direction and strength of bivariate neural signal. However, the method currently does not directly apply in handling multivariate signal. Its application in practice has also long been largely hampered by the ultra-high complexity of NLI algorithms. Aiming at these problems, this study 1) extends the conventional NLI to quantify the global synchronization of multivariate neural signals, and 2) develops a parallelized NLI method with general-purpose computing on the graphics processing unit (GPGPU), namely, G-NLI. The approach performs synchronization measurement in a massively parallel manner. The G-NLI has improved the runtime performance by more than 1000 times comparing to the original sequential NLI. Meanwhile, the G-NLI was employed to analyze 10-channel local field potential (LFP) recordings from a patient suffering from temporal lobe epilepsy. The results demonstrate that the proposed G-NLI method can support real-time global synchronization measurement and it could be successful in localization of epileptic focus. © 2001-2011 IEEE.

Hua C.-C.,Beijing University of Posts and Telecommunications | Hua C.-C.,Yanshan University | Ding S.X.,University of Duisburg - Essen | Guan X.-P.,Yanshan University | Guan X.-P.,Shanghai JiaoTong University
Automatica | Year: 2012

This paper considers the controller design problem for a class of uncertain systems with unknown actuator parameters. The considered systems are with multiple time delays and nonlinear uncertainties, and the uncertain nonlinearities are bounded by nonlinear functions with unknown coefficients. The actuator parameters are time-varying and their bounds are unknown, moreover the signs of them are not available. To deal with unknown actuator parameters problem, we decompose the system into two subsystems. For the resultant system, we develop the corresponding tolerant controller design method with the help of Nussbaum function. By constructing the Lyapunov Krasovskii functional, we prove the asymptotical stability of the closed-loop system. Finally, simulations are performed on a chemical reactor system to show the effectiveness of the proposed method. © 2011 Elsevier Ltd. All rights reserved.

Hua C.,Yanshan University | Liu X.P.,Carleton University
IEEE Transactions on Instrumentation and Measurement | Year: 2011

This paper addresses the controller design problem for teleoperation over networks such as the Internet. The forward and backward network transmission time delays are assumed to be asymmetric and time varying, which is the case for computer network communications. We propose a novel masterslave controller, which renders the entire system stable with relatively good steady- and transient-state performances. The relations among the parameters of the controller and the allowable maximum time delays are built in the form of linear matrix inequality. The designed controller is extended to the case that the velocity information is not available. A high-gain observer is designed to estimate the velocities of the master and slave joints online, and the controller is constructed on the basis of the estimated velocities. The stability of the closed-loop system is proved. Both simulations and experiments are performed to verify the correctness and effectiveness of the proposed method. © 2010 IEEE.

Liu X.,Beijing University of Posts and Telecommunications | Liu X.,Yanshan University | Qiao Y.,Beijing University of Posts and Telecommunications | Ji Y.,Beijing University of Posts and Telecommunications
Optics Communications | Year: 2010

In this paper, optical phase conjugation (OPC) located in the transmitter based on four wave mixing (FWM) in a semiconductor optical amplifier (SOA) is first simulated in 40 Gb/s CO-OFDM systems, and the fiber nonlinearity impairment of the transmission link is precompensated before OPC by transmission through a fiber with large nonlinearity coefficient. Simulation results show that the nonlinear threshold (NLT) can be increased by about >3 dB and maximum Q factor can be increased by about 2 dB for the single-channel system. For 50-GHz-Spacing WDM systems, the maximum Q and NLT are increased by about 1 dB, even in the presence of cross phase modulation (XPM) from neighbouring WDM channels. It is found that this OPC subsystem located in the transmitter, not necessary to be inserted into the middle of link, can mitigate the fiber nonlinearity impairment for both single-channel and WDM systems. Crown Copyright © 2010 Published by Elsevier B.V. All rights reserved.

Hua C.-C.,Yanshan University | Guan X.-P.,Yanshan University | Guan X.-P.,Shanghai JiaoTong University
Automatica | Year: 2016

The dynamic output feedback control problem is considered for a class of systems with multiple time delays and nonlinear uncertainties. Based on the control input matrix and output matrix, we decompose the system into two subsystems. The dynamic compensator is designed for the first subsystem, and then the output feedback controller is constructed based on the compensator and the second subsystem. By using the introduced new Lyapunov-Krasovskii functional, we show that the solution of the resultant closed-loop system converges exponentially to an adjustable bounded region. Compared with the previous works, the developed controller in this paper is memoryless and smooth, which only uses the system output. The control design conditions are relaxed because of the developed dynamic compensator. The result is further extended to the general nonlinear case. The corresponding dynamic nonlinear output feedback control method is proposed. Finally, simulations are performed to show the potential of the proposed methods. © 2016 Elsevier Ltd. All rights reserved.

Luo X.,Shanghai JiaoTong University | Han N.,Yanshan University | Guan X.,Yanshan University
Journal of Systems Engineering and Electronics | Year: 2011

Two protocols are presented, which can make agents reach consensus while achieving and preserving the desired formation in fixed topology with and without communication timedelay for multi-agent network. First, the protocol without considering the communication time-delay is presented, and by using Lyapunov stability theory, the sufficient condition of stability for this multi-agent system is presented. Further, considering the communication time-delay, the effectiveness of the protocol based on Lyapunov-Krasovskii function is demonstrated. The main contribution of the proposed protocols is that, as well as the velocity consensus is considered, the formation control is concerned for multi-agent systems described as the second-order equations. Finally, numerical examples are presented to illustrate the effectiveness of the proposed protocols.

Ma K.,Yanshan University | Liu Z.,Yanshan University | Guan X.,Shanghai JiaoTong University
Wireless Personal Communications | Year: 2012

The principal purpose of this paper is to develop a joint relay selection and power allocation algorithm in cooperative cellular networks with multiple users assisted by multiple relays. By solving a rate optimization problem, we can obtain the optimal solutions and the distributed implementation based on the primal-dual decomposition. An admission control algorithm is also presented when there exists the minimal rate requirement for each user. Simulation results indicate that the algorithm with joint design is superior to the existing ones with isolated design in large total transmission rates and small deviations. Moreover, with the admission control algorithm, the rate requirements for users participating in cooperation are also satisfied. © 2010 Springer Science+Business Media, LLC.

Zhao G.,Yanshan University | Wang J.,Shanghai JiaoTong University
IET Control Theory and Applications | Year: 2016

This study investigates discrete-time triggered reset law design for linear systems in order to adapt reset control to computer-based implementation. The reset actions are triggered at discrete sampling times if predefined reset conditions are satisfied, and reset law is used to determine reset values of the controller states. A discrete-time switched system model of the reset control systems is established, then, a model predictive strategy is proposed to design the reset law by solving a linear matrix inequality optimisation problem. Moreover, the proposed method is extended to observer-based reset law design. The obtained results are applied to numerical example and typical continuous stirred tank reactor system, simulations show that the proposed design is effective. © The Institution of Engineering and Technology 2016.

Hua C.-C.,Carleton University | Hua C.-C.,Yanshan University | Liu X.P.,Carleton University
IEEE Transactions on Robotics | Year: 2010

This paper addresses the stability-analysis problem for teleoperation systems with time delays. Compared with previous work, communication delays are assumed to be both time-varying and asymmetric, which is the case for network-based teleoperation systems. The stability analysis is performed for two classes of controllers: delayed position-error feedback and delayed torque feedback. By choosing LyapunovKrasovskii functional, we show that the masterslave teleoperation system is stable under specific linear-matrix- inequality (LMI) conditions. With the given controller-design parameters, the proposed stability criteria can be used to compute the allowable maximal transmission delay. Finally, both simulations and experiments are performed to show the effectiveness of the proposed method. © 2010 IEEE.

Hua C.-C.,Yanshan University | You X.,Yanshan University | Guan X.-P.,Shanghai JiaoTong University
Automatica | Year: 2016

The finite-time leader-following consensus problem is addressed for a class of high-order multi-agent systems with uncertain nonlinear dynamics. Each follower node is modeled by lower-triangular system. By using recursive method, we develop the finite-time consensus control design scheme. Based on finite-time Lyapunov stability theorem and matrix theory, we prove that the finite-time consensus of high-order uncertain nonlinear multi-agent systems is guaranteed by non-lipschitz continuous control laws. Simulation results are given to illustrate the effectiveness of the theoretical results. © 2016 Elsevier Ltd

Hua C.-C.,Yanshan University | Liu D.,Yanshan University | Guan X.-P.,Shanghai JiaoTong University
IEEE Transactions on Circuits and Systems II: Express Briefs | Year: 2014

A new method for the stability analysis of a large class of fractional-order delayed systems is proposed. The exact region of the delay that can stabilize the system is determined without any approximation. Two steps of system transformation are employed to switch the fractional characteristic function to its corresponding integral function and to achieve an algebraic equation that facilitates the computation. Finally, an example is given to prove the feasibility of the proposed method. © 2013 IEEE.

Tang Y.,Yanshan University | Tang Y.,Key Laboratory of System Control and Information Processing | Zhang X.,Yanshan University | Zhang D.,Yanshan University | And 2 more authors.
Neurocomputing | Year: 2013

Antilock braking system (ABS) is a highly nonlinear system including variation and uncertainties in the parameters due to changes in vehicle loadings, road condition, etc. It is a difficult task to design an ideal controller for ABS. In this paper, a novel robust controller named fractional order sliding mode controller (FOSMC) is proposed for ABS to regulate the slip to a desired value. The proposed FOSMC combines sliding mode controller (SMC) with fractional order dynamics, in which fractional order proportional-derivative (FOPD) sliding surface is adopted. FOSMC can not only deal with the uncertainties in ABS system but also track the desired slip faster than conventional integer order SMC with proportional or proportional-derivative sliding surface. Experimental results demonstrate the effectiveness of the proposed method. © 2013.

Luo X.,Yanshan University | Liu D.,Yanshan University | Guan X.,Shanghai JiaoTong University | Li S.,City University of Hong Kong
IET Control Theory and Applications | Year: 2012

In this study, the authors investigate the problem of flocking motion combined with topology optimisation for mobile multi-agent systems. In most of the recent literatures, all agents are assumed to be informed of target's information for all time to maintain connectivity. Actually, it is not essential to make all agents be informed. In this study, the authors present a distributed topology optimisation scheme to reduce the communication complexity of keeping connectivity while the multi-agent system pursuits a virtual target. This optimisation scheme is performed in the discrete space of graphs and relies on two key ideas. First, it generates optimally rigid graphs for each agent with its neighbouring flockmates. Second, partial agents are selected as the informed units to maintain the connectivity of the multi-agent system. Based on this scheme, the authors propose a distributed motion controller to make the mobile agents result in flocking behaviour. Applying the proposed algorithms, it is shown that the communication energy dissipation of the networked system is decreased. Stability analysis is further achieved by using differential conclusions and non-smooth analysis in switching topology. Numerical simulation examples demonstrate the effectiveness of the proposed algorithms. © 2012 The Institution of Engineering and Technology.

Zhu X.,Yanshan University | Pei L.,Yanshan University | Zhao Z.,Yanshan University | Liu B.,Yanshan University | And 2 more authors.
Journal of Alloys and Compounds | Year: 2013

A systematic investigation was performed on the hydrogen storage properties of composites which were prepared by ball milling MgH2 with different amounts of LaH3 and the catalysis mechanism of La hydride on MgH 2 was reported in this paper. Pressure-Composition-Temperature (P-C-T) curves showed that the reversible hydrogen storage capacity of MgH 2 + 20 wt.% LaH3 composite was 5.1 wt.% at 548 K, while the pure MgH2 hardly released any H2 under the same conditions. The addition of LaH3 also significantly improved the hydriding/dehydriding kinetics, and led to the rate-controlling steps of MgH2 becoming altered from a three-dimensional interfacial reaction to a one-dimensional diffusion process. The XRD pattern indicated that the LaH3 phase partially transformed to LaH2.3 phase during the dehydriding process. TEM micrograph images revealed that the LaH 2.3 phase was distributed homogeneously throughout the Mg phase and that the Mg crystals were coated with LaH2.3 crystals in the matrix. This microstructure exhibited an obvious volume contraction and resulted in a distinct strain of MgH2 when the LaH3 phase released H2. DSC curves proved that the addition of LaH3 could decrease the temperature at which the onset of the dehydrogenation of MgH 2 occurred by approximately 20.4 K. © 2013 Elsevier B.V. All rights reserved.

Capaccioli S.,CNR Institute for Chemical and Physical Processes | Paluch M.,University of Silesia | Prevosto D.,CNR Institute for Chemical and Physical Processes | Wang L.-M.,Yanshan University | Ngai K.L.,CNR Institute for Chemical and Physical Processes
Journal of Physical Chemistry Letters | Year: 2012

Most glass-forming systems are composed of basic units interacting with each other with a nontrivial anharmonic potential. Naturally, relaxation and diffusion in glass formers is a many-body problem. Results from recent experimental studies are presented to show the effects of many-body relaxation and diffusion manifested on the dynamic properties of glass formers. Considering that the effects are general and critical, the problem of glass transition will not be solved until the many-body nature of the relaxation process has been incorporated fundamentally into any theory. © 2012 American Chemical Society.

Li S.,City University of Hong Kong | Wang J.,Yanshan University | Luo X.,Yanshan University | Guan X.,Yanshan University | Guan X.,Shanghai JiaoTong University
Systems and Control Letters | Year: 2011

This paper aims to find a simple but efficient method for consensus protocol design. This paper presents two consensus protocols to solve the consensus problem of complex multi-agent systems that consist of inhomogeneous subsystems. The limitations of current studies are analyzed, and a novel model based on transfer functions is presented. This model can be used to describe both homogeneous and inhomogeneous multi-agent systems in a unified framework. Based on this model, two sufficient and necessary conditions for the consensus of complex multi-agent systems have been obtained. One is for the systems without any external input, and the other is for the systems with the same external input. Then, two corresponding distributed consensus protocols are presented. Considering that the complex multi-agent systems may require different outputs sometimes, the relationship between inputs and outputs is analyzed. Finally, some simulations are given to demonstrate the performance and effectiveness of the proposed approaches. © 2010 Elsevier B.V. All rights reserved.

Yang Y.,Yanshan University | Hua C.,Yanshan University | Guan X.,Yanshan University | Guan X.,Shanghai JiaoTong University
IEEE Transactions on Fuzzy Systems | Year: 2014

The master-slave control design problem is considered for the networked teleoperation system with friction and external disturbances. A new finite-time synchronization control method is proposed with the help of adaptive fuzzy approximation. We develop a new nonsingular fast terminal sliding mode (NFTSM) to provide faster convergence and higher precision than the linear hyperplane-sliding mode and the classic terminal-sliding mode (TSM). Then, the adaptive fuzzy-logic system is employed to approximate the system uncertainties, and the corresponding adaptive fuzzy NFTSM controller is designed. By constructing Lyapunov function, the stability and finite-time synchronization performance are proved with the new controller in the presence of system uncertainties and external disturbances. Compared with the traditional teleoperation design method, the new control scheme achieves better transient-state performance and steady-state performance. Finally, the simulations are performed and the comparisons are shown among the proposed method, the P+d method, the PD+d method, the DFF method, and the classic TSM FTSM. The simulation results further demonstrate the effectiveness of the proposed method. © 2014 IEEE.

Li J.,CAS Institute of Physics | Wang D.-S.,Beijing Information Science and Technology University | Wu Z.-Y.,CAS Institute of Physics | Wu Z.-Y.,Yanshan University | And 2 more authors.
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2012

A three-dimensional study of the ring vortex solitons is conducted for both attractive and repulsive Bose-Einstein condensates subject to harmonic potential confinement. A family of stationary ring vortex solitons, which is defined by the radial excitation number and the winding number of the intrinsic vorticity, are obtained numerically for a given atomic interaction strength. We find that stabilities of the ground and radially excited states of the ring vortex soliton are dependent on the winding number differently. The ground state of the ring vortex soliton with the large winding number is unstable dynamically against random perturbation. The radially excited state of the ring vortex soliton with large winding number corresponds to the increased collapse threshold and therefore can be made stable for sufficiently small atomic interaction strengths. The ground and radially excited states also demonstrate different dynamic evolutions under large atomic interaction strengths. The former exhibits simultaneous symmetric splitting in the transverse plane, while the latter displays periodic expand-merge cycles in the longitudinal direction. © 2012 American Physical Society.

Liu Z.,Yanshan University | Zheng Q.,Yanshan University | Xue L.,Yanshan University | Guan X.,Yanshan University | Guan X.,Shanghai JiaoTong University
Future Generation Computer Systems | Year: 2012

Coverage preservation, unique ID assignment and extension of network lifetime are important features for wireless sensor networks. Grouping sensor nodes into clusters is an effective way to improve the network performance. By analyzing communication energy consumption of the clusters and the impact of node failures on coverage with different densities, we propose a DEECIC (Distributed Energy-Efficient Clustering with Improved Coverage) algorithm. DEECIC aims at clustering with the least number of cluster heads to cover the whole network and assigning a unique ID to each node based on local information. In addition, DEECIC periodically updates cluster heads according to the joint information of nodes' residual energy and distribution. The algorithm requires neither time synchronization nor knowledge of a node's geographic location. Simulation results show that the proposed algorithm can prolong the network lifetime and improve network coverage effectively. © 2011 Elsevier B.V. All rights reserved.

Zhang L.,Yanshan University | Zhang L.,Shanghai JiaoTong University | Zhang L.,Hengshui University | Tang Y.,Yanshan University | And 3 more authors.
Applied Soft Computing Journal | Year: 2015

Particle swarm optimization is a stochastic population-based algorithm based on social interaction of bird flocking or fish schooling. In this paper, a new adaptive inertia weight adjusting approach is proposed based on Bayesian techniques in PSO, which is used to set up a sound tradeoff between the exploration and exploitation characteristics. It applies the Bayesian techniques to enhance the PSO's searching ability in the exploitation of past particle positions and uses the cauchy mutation for exploring the better solution. A suite of benchmark functions are employed to test the performance of the proposed method. The results demonstrate that the new method exhibits higher accuracy and faster convergence rate than other inertia weight adjusting methods in multimodal and unimodal functions. Furthermore, to show the generalization ability of BPSO method, it is compared with other types of improved PSO algorithms, which also performs well. © 2014 Elsevier B.V. All rights reserved.

Liu X.,Beijing University of Posts and Telecommunications | Liu X.,Yanshan University | Qiao Y.,Beijing University of Posts and Telecommunications | Ji Y.,Beijing University of Posts and Telecommunications
Chinese Optics Letters | Year: 2011

We study an electronic compensator (EC) as a receiver for a 100-Gb/s polarization division multiplexing coherent optical orthogonal frequency division multiplexing (PDM-CO-OFDM) system without optical dispersion compensation. EC, including electrical dispersion compensation (EDC), least squares channel estimation and compensation (LSCEC), and phase compensation (PC), is used to compensate for chromatic dispersion (CD), phase noise, polarization mode dispersion (PMD), and channel impairments, respectively. Simulations show that EC is highly effective in compensating for those impairments and that the performance is close to the theoretical limitation of optical signal-to-noise rate (OSNR), CD, and PMD. Its robustness against those transmission impairments and fiber nonlinearity are also systematically studied. © 2011 Chinese Optics Letters.

Zhao Y.,Yanshan University | Xiong D.-B.,Kyoto University | Qin H.,KTH Royal Institute of Technology | Gao F.,Yanshan University | And 2 more authors.
International Journal of Hydrogen Energy | Year: 2012

Low temperature solid oxide fuel cell (LTSOFC, 300-600 °C) is one of the hot areas in recent fuel cell developments. In order to develop high performance LTSOFCs, compatible electrodes are highly demanded. We used NANOCOFC (nanocomposites for advanced fuel cell technology) approach to develop nanocomposite electrodes based on metal oxides Ni-Cu-Zn-oxide and samarium doped ceria (SDC). It was found that the materials consist of individual metal oxide and SDC phase, indicating the material as a composite with a homogenous distribution for all constituent components. Highly homogenous distribution of the particles enhanced the catalyst function for electrode applications in LTSOFC devices. We constructed the devices using the SDC-carbonate nanocomposite (NSDC) as the electrolyte and above as prepared composite as electrodes in a symmetrical configuration. We found that the prepared composite electrodes had good catalytic function for both H2 and O2, to prove its anode and cathode functions. Based on the material properties, the LTSOFC devices have reached a power output more than 730 mW cm-2 at 550 °C. Copyright © 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Zhao X.,Shanghai JiaoTong University | Tang X.,Shanghai JiaoTong University | Zhang L.,Yanshan University | Zhao M.,Yanshan University | Zhai J.,Yanshan University
Electrochimica Acta | Year: 2010

LiFe1-xNdxPO4/C (x = 0-0.08) cathode material was synthesized using a solid-state reaction. The synthesis conditions were optimized by thermal analysis of the precursor and magnetic properties of LiFePO4/C. The structure and electrochemical performances of the material were studied using XRD, FE-SEM, EDS, electrochemical impedance spectroscopy and galvanostatic charge-discharge. The results show that a small amount of aliovalent Nd3+ ion-dopant substitution on Fe2+ ions can effectively reduce the particle size of LiFePO4/C. Cell parameters of LiFe1-xNdxPO4 (x = 0.04-0.08) were calculated, and the results showed that LiFe1-xNd xPO4/C had the same olivine structure as LiFePO 4. LiFe0.4Nd0.6PO4/C delivers the discharge capacity of 165.2mAhg-1 at rate of 0.2 C and the capacity retention rate is 92.8% after 100 cycles. Charge-transfer resistance decreases with the addition of glucose and Nd3+ ions. Poly(cyclotriphosphazene- co-4,4′-sulfonyldiphenol) (PZS) was synthesized and PZS nanorods were used as a carbon source to coat LiFePO4. All of the results show that aliovalent doping substitution of Fe in LiFePO4 is well tolerated. © 2010 Elsevier Ltd. All rights reserved.

Yu Y.-M.,CAS Institute of Physics | Voigt A.,CAS Institute of Physics | Guo X.,TU Dresden | Liu Y.,Yanshan University
Applied Physics Letters | Year: 2011

Through phase-field simulations, we investigate simultaneous step meandering and bunching instabilities with the presence of Ehrlich-Schwoebel barrier and elastic interaction. The meandering instability induced by the Ehrlich-Schwoebel barrier is found to be dependent on the elastic interaction at low adatom deposition rate. The ordered step meandering-bunching structure is designed by using the predefined magnitude distribution of the force monopoles on vicinal surfaces based on interplay between the Ehrlich-Schwoebel barrier and the elastic interaction. © 2011 American Institute of Physics.

Yang A.-M.,Yanshan University | Yang A.-M.,Hebei United University | Zhang Y.-Z.,Yanshan University | Zhang Y.-Z.,Hebei United University | Long L.,Hebei United University
Thermal Science | Year: 2013

1-D fractal heat-conduction problem in a fractal semi-infinite bar has been developed by local fractional calculus employing the analytical Yang-Fourier transforms method. The simplicity and the accuracy of the method are discussed.

Yang X.,Yanshan University | Hua C.,Yanshan University | Yan J.,Yanshan University | Guan X.,Yanshan University | Guan X.,Shanghai JiaoTong University
Information Sciences | Year: 2013

The stability problem is studied for teleoperation systems over general communication networks. Compared with previous work, both quantization and time delay issues are considered. The controller used in this paper is in the form of proportional-derivative, and the output signals of master and slave systems are quantized before being transmitted. The stability criteria are presented to show that the controller can stabilize the master-slave system under quantization and variable time delay. Additionally, we propose a new quantized measurement, which can decrease the quantization error. Finally, simulations and detailed analysis are given to show the effectiveness of the main results. © 2013 Elsevier Inc. All rights reserved.

Cui B.-Y.,Hebei United University | Jin Z.-L.,Yanshan University
Advanced Materials Research | Year: 2013

In order to increase wosrkspace and carrying capacity of leg mechanism and improve popularity and adaptability of leg mechanism, a novel mechanism is proposed which has three branches of 6-DOF, which used 3-UPS parallel mechanism as the prototype of the mechanism. The static performance of the leg mechanism is analyzed and the structure parameters are designed. First, the static transmission equation of the leg mechanism is established by using the principle of virtual works which simplifies the calculation process of the leg mechanism. Further, the static performance evaluation index and the global torque performance evaluation index are defined, and the performance atlas of the static performance evaluation index is plotted at the work spaces of the leg mechanism. Moreover, by using of the space model theory, the structural dimensions parameters are optimized of the leg mechanism. Finally, using a set of optimal structural dimensions parameters and the virtual prototype of leg mechanism is designed. The research provides a theoretical basis for further investigation on leg mechanism. © (2013) Trans Tech Publications, Switzerland.

Cui B.-Y.,Hebei United University | Jin Z.-L.,Yanshan University
Advanced Materials Research | Year: 2013

Kinematics research of mechanism is very important, the dynamic analysis and the design are based on kinematical analysis. In this paper, a novel robot shoulder joint based on 3-RRR orthogonal spherical parallel mechanism is proposed, and the kinematics transmission equation of shoulder joint is derived by using the kinematics inverse solution, and Jacobin matrix is established. Then Jacobin matrix is introduced into the global performance index, and the velocity of global performance evaluation index is defined. Furthermore, the shoulder joint dimensions are changed, and the global performance index is analyzed, then a performance atlas is given at the work spaces of shoulder joint with different dimension. It is found that the Jacobin matrix has more important influence on the kinematics performance of the shoulder joint. Having a good kinematics performance, structure dimensions ranges of shoulder joint are gained, thus the evaluation of kinematics of shoulder joint is more comprehensive. Finally, a novel robot shoulder joint is designed with the kinematics performance evaluation index. © (2013) Trans Tech Publications, Switzerland.

Xiao F.-R.,Yanshan University | Cao Y.-B.,Yanshan University | Qiao G.-Y.,Yanshan University | Zhang X.-B.,Jiangsu Shagang Group Co Ltd | Liao B.,Yanshan University
Journal of Iron and Steel Research International | Year: 2012

Nb is often considered to be a powerful alloying element for controlling the recrystallization process in microalloyed high strength steels. However, Nb can be presented either as solute in solution, where it is thought to exhibit a strong solute drag effect, or as NbC precipitates, which are thought to be effective at pinning grain boundaries. Therefore, it is very important to quantitatively measure Nb in solution or in NbC precipitates. A quantitative analysis method of Nb in solution and in precipitates was proposed. The test procedure involved chemical dissolution, filtration and inductively coupled plasma atomic emission spectroscopic (ICP-AES) analysis. The amount of Nb in solution in Nb-microallyed steels under different treatment conditions was evaluated. The results show that the niobium and carbon contents in steels have a great effect on niobium dissolution kinetics. The solute Nb is more effective to retard dynamic recrystallization, while the NbC precipitates are more effective to inhibit static recrystallization. The results may help to comprehend effect of Nb in steels, and provide some guides in the design of new high strength Nb-bearing steels. © 2012 Central Iron and Steel Research Institute.

Luo X.,Yanshan University | Yan Y.,Yanshan University | Li S.,City University of Hong Kong | Guan X.,Shanghai JiaoTong University
Computer Networks | Year: 2013

This paper presents an optimization scheme of sensor networks for node scheduling and topology control, aiming to reduce energy consumption for heterogeneous Wireless Sensor Networks (WSNs) with non-uniform transmission ranges. Motivated by geographical adaptive fidelity (GAF), we partition sensors into groups based on the location of sensors, such that a connected backbone network can be maintained by keeping only one arbitrary node from each group in active status while putting others to sleep. In addition, optimally rigid geographical adaptive fidelity (ORGAF) approach is proposed to decrease the communication complexity and reduce the energy dissipation. Furthermore, we prove the topology derived under ORGAF is 2-connected; and the average degree of nodes in the topology converges to four approximately. Simulation results show that ORGAF can improve the network performance as well as reducing the energy consumption. © 2012 Elsevier B.V. All rights reserved.

Zhang X.M.,CAS Institute of Physics | Zhang X.M.,Hebei University of Technology | Wang W.H.,CAS Institute of Physics | Liu E.K.,CAS Institute of Physics | And 3 more authors.
Applied Physics Letters | Year: 2011

The electronic structures of tetragonally distorted half-Heusler compound LaPtBi in the C1b structure are investigated in the framework of density functional theory using the full potential linearized augmented plane with local spin density approximation method. The calculation results show that both the band structures and the Fermi level can be tuned by using either compressive or tensile in-plane strain. A large bulk band gap of 0.3 eV can be induced through the application of a compressive in-pane strain in LaPtBi with the assumption of a relaxed volume of the unit cell. Our results could serve as a guidance to realize topological insulators in half-Heusler compounds by strain engineering. © 2011 American Institute of Physics.

Li A.,Kyushu University | Li A.,Yanshan University | Imasaka T.,Kyushu University | Uchimura T.,Kyushu University | Uchimura T.,University of Fukui
Analytica Chimica Acta | Year: 2011

Gas chromatography/multiphoton ionization/time-of-flight mass spectrometry (GC/MPI/TOFMS) was utilized for analysis of a standard mixture sample containing 49 pesticides and 4 real samples using the third-harmonic emission (267. nm) of a femtosecond Ti:sapphire laser (100. fs) as the ionization source. A sample of a standard mixture of n-alkane was also measured for calibration of the retention time indices of the pesticides. Two photons are required for the excitation of n-alkane due to an absorption band located in the far ultraviolet region (140. nm). The n-alkane molecule in the excited state was subsequently ionized either directly or by absorbing another photon because of a high ionization potential. Due to a large excess of energy, the molecular ion was decomposed and formed many fragment ions. Compared to n-alkanes, most of the pesticides were softly ionized by the femtosecond laser; one photon was used for excitation and another was used for the subsequent ionization. The pesticides with no conjugated double bond had a lower ionization efficiency. The present analytical instrument was applied to several samples prepared from a variety of vegetables and a single fruit after pretreatment with solid-phase extraction. Three pesticides were found in these samples, although some of them were not detected by conventional GC/EI/MS-MS due to insufficient sensitivity and selectivity. © 2011 Elsevier B.V.

Li Y.,Yanshan University | Chen X.,Beijing Technology and Business University | Fan C.,Chinese Academy of Inspection and Quarantine | Pang G.,Yanshan University | Pang G.,Chinese Academy of Inspection and Quarantine
Journal of Chromatography A | Year: 2012

A gas chromatography-mass spectrometry (GC-MS) analytical method was developed for simultaneously determining 186 pesticides in tea matrices using analyte protectants to counteract the matrix-induced effect. The matrix effects were evaluated for green, oolong and black tea, representing unfermented, partially fermented and completely fermented teas respectively and depending on the type of tea, 72%, 94% and 94% of the pesticides presented strong response enhancement effect. Several analyte protectants as well as certain combinations of these protectants were evaluated to check their compensation effects. A mixture of triglycerol and d-ribonic acid-γ-lactone (both at 2. mg/mL in the injected samples) was found to be the most effective in improving the chromatographic behavior of the 186 pesticides. More than 96% of the 186 pesticides achieved recoveries within the range of 70-120% when using the selected mixture of analyte protectants. The simple addition of analyte protectants offers a more convenient solution to overcome matrix effects, results in less active sites compared to matrix-matched standardization and can be an effective approach to compensate for matrix effects in the GC-MS analysis of pesticide residues. © 2012 Elsevier B.V.

Zhao G.,Yanshan University | Wang J.,Shanghai JiaoTong University
IET Control Theory and Applications | Year: 2015

This study considers the use of reset control to achieve non-overshoot step response for minimum-phase linear single-input single-output systems. Novel reset controllers with state-dependent reset conditions are proposed to asymptotically track a constant step reference with zero overshoot, and rise time can be arbitrarily tuned with mild assumption. Moreover, the existence of such non-overshoot reset controllers is also presented. The proposed design method can also be used for a class of input-output linearisable non-linear systems and set point regulation. Simulation examples support authors' results. © The Institution of Engineering and Technology 2015.

Wang Z.-Q.,Yanshan University | Zhao J.-C.,Shanghai JiaoTong University
Journal of Structural Engineering (United States) | Year: 2014

A first-order torsion formulation for closed thin-walled (CTW) beam subjected to restrained torsion is developed to consider the warping deformation and restrained shear stresses on cross section and their effect on the behavior of thin-walled (TW) beam. The total torque on closed cross section in the current formulation consists of four component torques. The expressions of various torques and corresponding shear stresses are given. To account for the distribution of true restrained shear stress due to restrained shear rotation in TW cross section, torsion shear coefficient is proposed for CTW beam. Like the transverse shear coefficient in Timoshenko beam theory, the torsion shear coefficient lies at the heart of the first-order torsion theory. The new governing equations of restrained torsion of CTW beam are obtained, which have obvious physical meaning and is easy to be used in engineering and can also be used to solve the torsion problem of open thin-walled beam. The initial parameter method is developed so as to obtain the analytical solution effectively. To demonstrate the accuracy and applicability of the present theory, numerical and closed-form results are compared with those of some other available method. The effects of restrained shear stress on the behavior of open and CTW beams are investigated and verified. © 2014 American Society of Civil Engineers.

Wang L.-M.,Yanshan University | Tian Y.,Yanshan University | Liu R.,Yanshan University | Wang W.,CAS Institute of Physics
Applied Physics Letters | Year: 2012

We have established a generally applicable criterion for the critical cooling rates R c needed for the formation of metallic glasses, based on thermodynamic and kinetic properties of ten categories of metal-based alloys ranging from binary to multicomponent systems. R c is found to depend on several fundamental properties of materials including the glass transition temperature (normalized with respect to the liquidus temperature), entropy of fusion, and kinetic fragility. Such a relation reproduces the experimental R c values of 43 metallic glasses remarkably well with a R 2 value of 0.94. The explanation of R c provides guidance in search of metallic glasses. © 2012 American Institute of Physics.

Ge C.,Yanshan University | Ge C.,Hebei United University | Hua C.,Yanshan University | Guan X.,Yanshan University | Guan X.,Shanghai JiaoTong University
IEEE Transactions on Neural Networks and Learning Systems | Year: 2014

This brief is concerned with the problem of asymptotic stability of neural networks with time-varying delays. The activation functions are monotone nondecreasing with known lower and upper bounds. Novel stability criteria are derived by employing new Lyapunov-Krasovskii functional and the integral inequality. The developed stability criteria have delay dependencies and the results are characterized by linear matrix inequalities. New and less conservative solutions to the global stability problem are provided in terms of feasibility testing. Numerical examples are finally given to demonstrate the effectiveness of the proposed method. © 2013 IEEE.

Sun M.,CAS Institute of Physics | Hou Y.,CAS Institute of Physics | Hou Y.,Yanshan University | Xu H.,CAS Institute of Physics | Xu H.,Lund University
Nanoscale | Year: 2011

We attempt to provide experimental and theoretical evidence that information of chemical reaction can propagate with plasmonic waveguide along the nanowire and be detected at the remote terminal of nanowire, where the chemical reaction is the surface catalyzed reaction of DMAB produced from PATP assisted by surface plasmon polaritons. © 2011 The Royal Society of Chemistry.

Hua C.,Beijing University of Posts and Telecommunications | Hua C.,Yanshan University | Ding S.X.,University of Duisburg - Essen
IEEE Transactions on Fuzzy Systems | Year: 2012

The robust control problem is studied for a class of large-scale networked control systems. The subsystems are in the nonlinear form, and they exchange information through the communication networks. The interconnections considered are nonlinear, and not the traditional linear form, which brings a challenging issue for the decentralized control design. We develop a new memoryless control scheme with the use of the decomposition for each subsystem that is based on the input matrix. By Takagi-Sugeno (T-S) fuzzyfication for each subsystem, the interconnected T-S fuzzy subsystems are obtained. When the upper bound functions of uncertain interconnections are known, we design a decentralized memoryless state feedback controller. When the parameters of bound functions are not available, the adaptive method is used, and the decentralized memoryless adaptive controller is developed. By the construction of a new Lyapunov-Krasovskii functional, we prove the stability of the resultant closed-loop system for the both cases. Finally, we apply the theoretic results to the decentralized controller design of networked interconnected chemical reactor systems. The simulations are performed, and the effectiveness of the proposed method is demonstrated. © 2012 IEEE.

Wang L.-M.,Yanshan University | Mauro J.C.,Corning Inc.
Journal of Chemical Physics | Year: 2011

The kinetic fragility of a liquid is correlated to the magnitude of enthalpy hysteresis in various glass-forming materials during thermal cycling across the glass transition. While the lower bound of liquid fragility is well known, there has been little research into the possibility of an inherent upper limit to fragility. In this paper, we present a theoretical argument for the existence of a maximum fragility and show that the correlation between fragility and enthalpy hysteresis allows for an empirical evaluation of the upper limit of fragility. This upper limit occurs as the enthalpy hysteresis involved in thermal cycling about the glass transition approaches zero, leading to m max≈175. This result agrees remarkably well with our previous estimate. The dynamics of maximum fragility liquids are discussed, and a critical temperature of ∼1.5 Tg (where Tg is the glass transition temperature) is revealed where a transition from nonexponential to exponential structural relaxation occurs. © 2011 American Institute of Physics.

Xiao J.H.,Yanshan University | Xu Y.L.,Yanshan University | Jiang C.P.,Beihang University
ZAMM Zeitschrift fur Angewandte Mathematik und Mechanik | Year: 2011

The problem of a doubly periodic array of conducting rigid line inclusions in piezoelectric materials under far-field antiplane mechanical load and inplane electric load is investigated, where the fundamental cell contains four rigid line inclusions of unequal size. An exact solution to the problem is presented by employing the conformal mapping technique and the elliptical function theory. The closed form formulae for the stress and electrical displacement intensity factors at the rigid line inclusion tip and the effective electroelastic moduli of such composites are derived. Many new and existing solutions can be regarded as the special or degenerated cases. Numerical examples are provided to show the interesting electroelastic interaction phenomenon induced by multiple rigid line inclusions. The present work is helpful in understanding the optimization mechanism of some naturally occurring composites and in designing novel materials by direct engineering of their microstructure. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Yang J.,Yanshan University | Shen T.,Sophia University | Jiao X.,Yanshan University
IEEE Transactions on Control Systems Technology | Year: 2014

In this paper, a stochastic optimal control scheme for the air-fuel ratio is proposed, which considers the cyclic variations of the residual gas fraction (RGF). Initially, a cylinder pressure-based measurement of the RGF is derived by following the physics of inlet-exhaust process. Then, a dynamical model is presented to describe the cyclic variation of the air charge, fuel charge, and combustion products under a cyclically varied RGF, where the RGF is modeled as a Markovian stochastic process. Using this model, a feedback control law is derived, which optimizes the quadratic cost function in the stochastic sense with respect to the stochastic property of the residual gas. The cost function reflects the tradeoff between the accuracy of the regulation of the air-fuel ratio with the fluctuation in the fuel injection. Finally, a sampling process-based statistical analysis for the RGF is presented based on the experiments conducted on a full-scaled gasoline engine test bench, and the proposed control law is validated based on a numerical simulation and experiments. © 2013 IEEE.

Li F.,Yanshan University | Li F.,Sophia University | Shen T.,Sophia University | Jiao X.,Yanshan University
Chinese Control Conference, CCC | Year: 2013

Control-oriented modeling and control problem for gasoline engines are studied in this paper. First, a mean-value model-based control scheme is proposed that consists of dual control loops, the fuel injection mass decision and the receding horizon optimization regarding the speed tracking performance with the throttle opening. Then, as Part I of this research, the paper focuses on the modeling problem, where the static function fitting technique and the parameter identification algorithm are made full use and the proposed approach is demonstrated with experimental data conducted on a gasoline engine with six cylinders. © 2013 TCCT, CAA.

Liu Y.,Brock University | Liu Y.,Yanshan University | Bose S.K.,Brock University | Kudrnovsky J.,ASCR Institute of Physics Prague
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

Using full-potential linear augmented plane-wave method (FP-LAPW) we have studied the stability and electronic properties of the chalcogenide CrTe in three competing structures: rocksalt (RS), zinc blende (ZB), and the NiAs-type (NA) hexagonal. Although the ground state is of NA structure, RS and ZB are interesting in that these fcc-based structures, which can perhaps be grown on various semiconductor substrates, exhibit half-metallic (HM) phases above some critical values of the lattice parameter. We find that the NA structure is not HM at its equilibrium volume while both ZB and RS structures are. The RS structure is more stable than the ZB with an energy that is lower by 0.25 eV/atom. While confirming previous results on the HM phase in ZB structure, we provide hitherto unreported results on the HM RS phase, with a gap in the minority channel and a magnetic moment of 4.0 μB /f.u. A comparison of total energies for the ferromagnetic (FM), nonmagnetic, and antiferromagnetic (AFM) configurations shows the lowest energy configuration to be FM for CrTe in all the three structures. The exchange interactions in the RS and ZB structures are studied for a wide range of the lattice parameter using the linear-response method and a mapping of the total energy to the classical Heisenberg model. These linear-response calculations are performed in the linear muffin-tin orbitals (LMTOs) basis, using the atomic sphere approximation (ASA). We have verified that the results of the electronic structure obtained via the LMTO-ASA method under local-density approximation (LDA) and LDA+U schemes are in close agreement with those obtained via the more accurate FP-LAPW method. The results show that the exchange interactions in the RS structure are much more short ranged than in the ZB structure. Hence, for the RS structure the exchange interactions are also studied by using a nearest- and next-nearest-neighbor (J1-J2) model and the energy differences between FM and two AFM states. These J1-J2 model results are obtained by using both the FP-LAPW and LMTO-ASA methods and compared with the linear-response results. The calculated Curie temperatures for the RS phase are consistently higher than those for the ZB phase. © 2010 The American Physical Society.

Jiao X.,Yanshan University | Zhang J.,Dalian Nationalities University | Shen T.,Sophia University
IEEE Transactions on Industrial Electronics | Year: 2014

In order to achieve higher precise positioning of the throttle plate, an adaptive servo control strategy is presented for the electronic throttle control system. Compared with the existing results on the electronic throttle control schemes, in this paper, the throttle valve reference tracking controller comprises a proportional-integral-derivative-type feedback controller with adaptive gain parameters, an adaptive feedforward compensator, and adaptive nonlinearity compensators for friction, limp-home (LH), and backlash. The closed-loop controller is realized by only utilizing the information of the throttle valve position measured by a cheap potentiometer of low resolution. The theoretical proof and analysis show that the designed throttle control system can ensure fast and accurate reference tracking of the valve plate angle in the case of the uncertain parameters related to production deviations, variations of external conditions and aging, and the effects of transmission friction, return-spring LH, and gear backlash nonlinearity with uncertain parameters. Moreover, the capability of the adaptive controller to preserve the transient performance and accuracy is evaluated in both simulation and experiment. © 1982-2012 IEEE.

Zhang T.,Yanshan University | Zhang T.,Nanjing Southeast University | Li Q.,Yanshan University | Xiao H.,Yanshan University | And 2 more authors.
Industrial and Engineering Chemistry Research | Year: 2012

A novel adsorbent of Li-Al layered double hydroxides (LDHs) was prepared through the precipitation of metal nitrates and further applied to remove excessive fluoride ions from water. The physical and chemical properties of synthesized materials were examined by powder transmission electron microscopy (TEM), X-ray diffraction (XRD) analysis, N 2 adsorption/desorption analysis, and thermogravimetric analysis (TGA). The TEM results indicated that the materials synthesized via coprecipitation present a preferential orientation of the nanoscale LDH platelets. The XRD analysis confirmed that the synthesized products have a highly crystalline nature and a well-ordered layer structure. The high specific surface areas (37.24-51.27 m 2/g) of calcined products were demonstrated to be beneficial for the adsorption of fluoride. For the adsorption experiment, the effects of the adsorption conditions including pH, coanions and adsorbent dose were investigated at initial fluoride concentration of 20 mg/L. The kinetics and isotherms of fluoride adsorption by calcined Li-Al LDHs were studied. The results indicated that the Li-Al LDHs can be effectively used to remove fluoride from water, where the maximum percentage removal (97.36%) could be reached and the adsorption equilibrium could be attained within 1 h. The kinetic data were well-fitted to the pseudo-second-order model, while the Freùndlich isotherm model provided the better correlation of the equilibrium data. Based on FT-IR and kinetic analysis, the memory effect may play an important role in the early adsorption stage, while the ion-exchange process may control the adsorption rate at the second adsorption stage. Since the Li-Al LDHs show excellent fluoride removal efficiency, they are expected to separate fluoride from water in pollution control. © 2012 American Chemical Society.

Chen X.,Shandong University of Science and Technology | Feng W.,Shandong University of Science and Technology | Zhao Y.,Yanshan University
Nongye Jixie Xuebao/Transactions of the Chinese Society for Agricultural Machinery | Year: 2013

A 4-UPS-UPU spatial 5-DOF parallel robot mechanism was introduced. A dynamics model of 4-UPS-UPU was presented. The kinematics of the UPS and UPU chain of leg was analyzed and the velocity mapping relationships between the parts and the driving axis were established. The exterior force load and the equivalent driving force were educed. The dynamics model of 4-UPS-UPU parallel robot mechanism was educed by the virtual work principle approach, which was the foundation of the dynamic analysis. Combined with engineering application examples, numerical verification and virtual simulation verification of the results of driving force and constraining torque was carried out.

Liu Y.,Yanshan University | Bose S.K.,Brock University | Kudrnovsk J.,ASCR Institute of Physics Prague
Journal of Applied Physics | Year: 2012

This work presents results for the magnetic properties of the compound GeTe doped with 3d transition metals V, Cr, and Mn from the viewpoint of potential application in spintronics. We report a systematic density-functional study of the electronic structure, magnetic and cohesive properties of these ternary compounds in both rock salt and zinc blende structures. In both cases, it is the Ge sublattice that is doped with the three transition metals. Some of these compounds are found to be half-metallic at their optimized cell volumes. For these particular cases, we calculate both exchange interactions and the Curie temperatures in order to provide some theoretical guidance to experimentalists trying to fabricate materials suitable for spintronic devices. Discussions relating our results to the existing experimental studies are provided whenever applicable and appropriate. Apparent discrepancy between experimental observations and our theoretical result for the case of Mn-doping is discussed in detail, pointing out various physical reasons and possible resolutions of the apparent discrepancy. © 2012 American Institute of Physics.

Zhang T.,Nanjing Southeast University | Mei Z.,Nanjing Southeast University | Zhou Y.,Nanjing Southeast University | Bu X.,Nanjing Southeast University | And 3 more authors.
CrystEngComm | Year: 2014

The properties of materials are largely determined by the microstructures and components of materials. The design of layered double hydroxide (LDH) based composites has garnered much interest as a way of fabricating novel multiscale architectures with tunable micro/nanostructures and chemical compositions. The present study aims at exploiting the Zn-Al composites for controlled synthesis of multi-scale structures and multi-component materials. Firstly, microscaled Al2O3 fibers are successfully fabricated via a simple, convenient, and cost-effective biotemplate method employing paper fibers as bio-templates. Then, the multi-scale architectures are designed by an in situ growth method, which involves direct growth of nanoscaled LDH platelets on the surfaces of Al2O3 fibers. Finally, the multi-component LDH based materials are prepared based on the controlled crystal growth of LDHs and ZnO. The microstructure, morphology, and textural properties of the as-prepared samples are characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption/ desorption. The experimental results show that the longer reaction times are favorable for the crystal growth of LDHs, and the higher hydrothermal temperatures are favorable for the formation of ZnO. This study shows that the design of multi-scale structures and multi-components Zn-Al composites can be extended for the preparation of other hierarchical LDH based materials with controlled morphological and tunable chemical compositions for separation, catalysis, adsorption, sensor, and optical applications. This journal is © The Royal Society of Chemistry.

Wang C.-F.,Tianjin Normal University | Yu Y.,Yanshan University
Communications in Computer and Information Science | Year: 2010

In this paper, the authors mainly deal with a predator-prey type fishery system with Beddington-De Angelis functional response. They first study the existence of steady states and local stability behaviour for the system. Then global stability of this model is discussed through constructing Lyapunov function. Finally a control instrument tax is imposed to protect the fish population from over exploitation. The problem of optimal taxation policy is solved by using Pontryagin's maximal principle. © 2010 Springer-Verlag.

Chen S.Y.,Zhejiang University of Technology | Luo G.J.,Karlsruhe Institute of Technology | Li X.,Yanshan University | Ji S.M.,Zhejiang University of Technology | Zhang B.W.,Nanjing University of Finance and Economics
IEEE Transactions on Industrial Electronics | Year: 2012

For pearls and other smooth alike lustrous jewels, the apparent shininess is one of the most important factors of beauty. This paper proposes an approach to automatic assessment of spherical surface quality in measure of shininess and smoothness using artificial vision. It traces a light ray emitted by a point source and images the resulting highlight patterns reflected from the surface. Once the reflected ray is observed as a white-clipping level in the camera image, the direction of the incident ray is determined and the specularity is estimated. As the specular exponent is the most important reason of surface shininess, the method proposed can efficiently determine the equivalent index of appearance for quality assessment. The observed highlight spot and specular exponent measurement described in this paper provide a way to measure the shininess and to relate the surface appearance with white-clipped image highlights. This is very useful to industrial applications for automatic classification of spherical objects. Both numerical simulations and practical experiments are carried out. Results of objective and subjective comparison show its satisfactory consistency with expert visual inspection. It also demonstrates the feasibility in practical industrial systems. © 2012 IEEE.

Peng Q.,Yanshan University | Fu H.,Yanshan University | Xiao W.,Beihang University
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2013

Serration flow is first observed in a fine-grained Mg-0.8 wt pct Ca alloy throughout the deformation history. Strain rate sensitivity (SRS) is sensitive with the deformation temperatures. A positive SRS in combination with a type of downward serration is found at low temperatures, which is mostly attributed to the strong dislocation-dislocation interaction. However, at high temperatures, another upward serration is observed and the SRS is changed to negative as a result of the solute pinning dislocation. © 2013 The Minerals, Metals & Materials Society and ASM International.

Chen C.,Yanshan University | Chen C.,Qinhuangdao Audio Visual Machinery Research Institute | Hu C.-H.,Yanshan University
Guangxue Jingmi Gongcheng/Optics and Precision Engineering | Year: 2013

To match the projecting images on dome screens from different types and specs of mainstream digital engineering projectors, a basic design method for a general projection fisheye zoom lens was presented. First, based on the characteristics and universality of the projection fisheye lens, the optical structure used in the final system was defined. By configuring the initial parameters of moving unit bestly, the moving path of compensating group was linearized to construct synchronously two cam curves to be standard helical lines. Then, image surface position was kept steady during a zooming process by controlling the spherical aberration of front fixed group and the focal length of back fixed group. The final design indicates that the optical system can always keep a full field angle of view of 160° and a F# of 2.0 as it uses two moving components that contain a positive zooming group and a negative compensating group. By controlling parameters reasonably, the system can match prisms of different effective optical thicknesses from 16.5 mm to 26 mm in several kinds of digital projector engines, and also can match digital engineering projectors by using 1LCD, 3LCD and 1DMD technologies with the chip sizes from 16-24 cm (0.63-0.95 in) and the length-width ratio of chip in 16:9 and 4:3 when the image shift is within ±0.03 mm. The design can fulfill the requirements of common and general projections with its simpler structure and good technology.

Gao D.,Yanshan University | Li Q.,Yanshan University | Gao Z.,Beijing Ditan Hospital | Wang L.,Yanshan University
Yonsei Medical Journal | Year: 2012

Purpose: Diabetes is the leading cause of end-stage renal failure. The present study was undertaken to characterize the effects of Corni Fructus on diabetic nephropathy in streptozotocin-induced diabetic rats and their mechanisms. Materials and Methods: Streptozotocin-diabetic rats were orally administrated with Corni Fructus at a dose of 100, 200 or 400 mg/kg body mass for 40 days. Results: Corni Fructus-treated diabetic rats showed significant decreases of blood glucose, urinary protein levels and water consumption. Corni Fructus also reduced serum total cholesterol, total triglyceride and low-density lipoprotein cholesterol levels, and showed a tendency of enhancing high-density lipoprotein cholesterol level. Levels of serum albumin and creatinine in diabetic rats were also significantly reduced by Corni Fructus administration at a dose of 200 and 400 mg/kg body mass compared with non-treated diabetic rats. Corni Fructus increased catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidose (GSH-px) activities in the kidneys of diabetic rats. Furthermore, Corni Fructus treatment enhanced renal peroxisome proliferator-activated receptor-γ (PPARγ) expression in diabetic rats. Conclusion: These results demonstrated that Corni Fructus may have the potential to protect the animals from diabetic nephropathy by amelioration of oxidative stress and stimulation of PPARγ expression. © Yonsei University College of Medicine 2012.

Zhang Z.,Dalian University of Technology | Zhang Z.,Tsinghua University | Zhang Z.,Yanshan University | Wang B.,Dalian University of Technology | Zhang X.,Dalian University of Technology
Scripta Materialia | Year: 2014

By varying the twin thickness from 4 to 23 nm, a maximum of hardness is achieved by molecular dynamics simulations at a twin thickness of 16 nm. When the twin thickness is >16 nm, the hardness is consistent with the Hall-Petch effect, whereas the hardness of a twin ≤16 nm thick is in a good agreement with the reverse Hall-Petch effect. This is attributed to a transformation of the synergistic effect between both twin boundaries from monotonically increasing to decreasing with increasing twin thickness. © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Du J.,Yanshan University | Wen B.,Yanshan University | Melnik R.,Wilfrid Laurier University | Kawazoe Y.,Tohoku University | Kawazoe Y.,RAS Institute of Thermophysics
Intermetallics | Year: 2014

The structural, mechanical, thermodynamic and electronic properties of binary Ni-Zr intermetallic compounds have been investigated by performing first-principles calculations. The results indicated that the structural parameters of these Ni-Zr intermetallic compounds agree well with the available experimental and other theoretical values. With increasing of Zr-content, the mass density and bulk modulus of these Ni-Zr intermetallic compounds decrease. Besides, Ni5Zr is the most stiffness phase and NiZr2 is the most ductile phase among these binary Ni-Zr intermetallic compounds. The structural stability of these Ni-Zr alloys ascends with Zr-content increasing. Furthermore, all the binary Ni-Zr intermetallic compounds considered in this work are conductive phases, and they are thermodynamically stable. © 2014 Elsevier Ltd. All rights reserved.

Xue J.,Yanshan University | Li S.,Yanshan University | Li S.,University of Rochester | Xiao Y.,University of Rochester | And 3 more authors.
Optics Express | Year: 2013

The polarization filter characters of a gold-coated and liquidfilled photonic crystal fiber are studied using the finite element method. Results show that the resonance strength and wavelengths are different in two polarized directions. Filling liquid of refractive index n = 1.33 (purified water) in holes in longitudinal direction can increase the loss of core mode polarized in the y-direction around the resonance peak. The resonance strength is much stronger in y-polarized direction than in xpolarized direction. The resonance strength can achieve 508dB/cm in ypolarized direction at the communication wavelength of 1311nm in one of our structures. Moreover, the full width half maximum is only 20nm. Such a small number makes such photonic crystal fibers promising candidate to filter devices. A liquid filled PCF of the small hole in the fiber core is designed and we find that filling liquid increases the resonance strength peak by thirty eight percent for the y-polarized resonance point. © 2013 Optical Society of America.

Li N.,Yanshan University | Gao Y.,Jilin University | Hou L.,Yanshan University | Gao F.,Yanshan University
Journal of Physical Chemistry C | Year: 2011

Growth and assembly of inorganic materials with the guidance of biomolecules is a promising route to control over the arrangement of nanoparticles. We present in this article an effective and efficient method for producing zinc oxide (ZnO) nanoparticle chains by directly using DNA as guide. Using extensive experiments over a wide range of synthesis parameters, such as the solvents and the concentrations of reactants, we have obtained high-quality ZnO nanoparticle chains in different sizes. This strategy makes it possible to tailor the optical and structural properties of ZnO nanoparticles aggregated on DNA. We have also studied theoretically the variation of the bandgap energy with the size of the ZnO nanocrystals using a chemical bond theory of quantum size effects. Furthermore, possible mechanisms are discussed in detail. © 2011 American Chemical Society.

Tang Y.,Yanshan University | Liu Y.,Yanshan University | Yu S.,Yanshan University | Zhao Y.,Yanshan University | And 2 more authors.
Electrochimica Acta | Year: 2014

To construct suitable nanostructures for electronic and ionic transport in the electrode of a supercapacitor, a flower-like nanostructured nickel hydroxide (Ni(OH)2) was synthesized by a facile hydrothermal process in this study. For comparison, an additional two Ni(OH)2 samples were synthesized to investigate the formation mechanism of the flower-like Ni(OH)2. Physicochemical characterizations indicate that the Ni(OH)2 nanoflower was formed by stacked hexagonal β-phase of the Ni(OH)2 nanoflakes. The dissolution-recrystallization of Ni(OH)2 and the stacking of nanoflakes play important roles in the formation of Ni(OH)2 nanoflowers. Due to the higher conductivity and the suitable macropores for ionic transport, the nanoflower-like Ni(OH) 2 exhibits a high specific capacitance of 2653.2 F g-1 at 2 A g-1 and 1998.5 F g-1 at 40 A g-1. An asymmetric supercapacitor, which was assembled with Ni(OH)2 as the positive material and HNO3-treated activated carbon as the negative material, exhibited a high cell voltage of 1.6 V. Due to the high specific capacitance and high cell voltage, the as-prepared asymmetric supercapacitor exhibited a high energy density of 32.7 Wh kg-1 at 71.5 W kg -1 and 25.5 Wh kg-1 at 1.28 kW kg-1. © 2014 Elsevier Ltd.

Du J.,Yanshan University | Wen B.,Yanshan University | Melnik R.,Wilfrid Laurier University | Kawazoe Y.,Tohoku University | Kawazoe Y.,RAS Institute of Thermophysics
Journal of Alloys and Compounds | Year: 2014

First-principle calculations have been performed to investigate the structural, mechanical, thermodynamic and electronic properties of eight binary Cu-Zr intermetallic compounds. The results indicated that with increasing Zr concentration, the mass density decreases monotonously. All Cu-Zr intermetallic compounds considered here are mechanically stable structures, and they are ductile materials. Among the eight binary Cu-Zr intermetallic compounds, CuZr is the most ductile phase. Furthermore, the heats of formation of the Cu-Zr intermetallic compounds are negative. Furthermore, CuZr2 is a semiconductor with indirect band gap of 0.227 eV, while the other seven Cu-Zr intermetallic compounds considered here are conductors. © 2013 Elsevier B.V. All rights reserved.

Lu Y.,Yanshan University | Lu Y.,Parallel Robot and Mechatronic System Laboratory of Hebei Province | Li X.P.,Yanshan University
Advanced Robotics | Year: 2014

A novel 6-DoF parallel manipulator I with three planar limbs is proposed and its dynamics is analyzed systematically. First, its characteristics and DoF are analyzed and calculated. Second, the formulae for solving kinematics of the moving platform and the planar limbs are derived. Third, the formulae for solving the inertial wrench applied on the planar limbs and the moving platform are derived, and dynamics formula is derived for solving dynamic active forces applied onto the planar limbs. Fourth, a singularity of the proposed parallel manipulator is determined and analyzed. Fifth, an analytic example is given for solving the kinetostatics and dynamics of the proposed parallel manipulator, and the solved results are analyzed and verified by the simulation mechanism. Finally, a workspace is constructed and analyzed by comparing with an existing 6-DoF parallel manipulator. © 2014 Taylor and Francis.

Li Y.,Tsinghua University | Li Y.,Yanshan University | Fu L.,Tsinghua University | Zhang S.,Tsinghua University | Zhao X.,Tsinghua University
Energy | Year: 2011

Large district heating (DH) system accounts for 70% of urban building heating in China. In North China, this proportion is even higher (The North China is the north of the Huai River and Qinling Mountains). Many cities in North China can exploit various kinds of low-grade renewable energy. This paper presents a new heating method to realize renewable energy recovery by absorption heat pumps associated with municipal network. In the DH substations, absorption heat pumps are driven by the exergy-difference originated from the larger temperature difference of heat exchange between primary and secondary heat network. There are two configurations-type I and type II substations based on the temperature of renewable energy. A reasonable parameter setting of system is suggested. The equipment operational performance was optimized based on a practical example. The low-grade renewable energy can be recovered effectively in this method. As a result, both heating capacity and energy efficiency of the DH system can be improved. Furthermore, operating costs may be reduced remarkably, due to the reduction in both the coal consumption of heat production unit and the power consumption of delivery pump. Therefore, the system is superior in energy conservation and has a promising application prospect. © 2011 Elsevier Ltd.

Li Y.,Tsinghua University | Li Y.,Yanshan University | Fu L.,Tsinghua University | Zhang S.,Tsinghua University | And 2 more authors.
Energy Conversion and Management | Year: 2011

A new type of district heating (DH) method based on Co-ah cycle was designed to improve both the capacity of heating system and the energy efficiency of Cogeneration plant. In the DH system substations, the temperature of return water of the primary heat network is reduced to about 25 °C through the absorption heat-exchange units. In the thermal station of the Cogeneration plant, the return water of the primary heat network is heated orderly by the exhaust steam in the condenser, the absorption heat pumps and the peak load heater. Compared with the traditional DH methods, this system runs with a greater circuit temperature drop so that the delivery capacity of the heat network increases dramatically. The heating capacity and the energy efficiency of the Cogeneration plant is significantly increased by the exhausted heat recovery from the condensers. A remarkable economic advantage can be achieved in this technology. At present, an application demonstration project had been built up in Chifeng city of Inner Mongolia Autonomous Region in north China. © 2010 Elsevier Ltd. All rights reserved.

Zhao Z.,Yanshan University | Tian F.,Nankai University | Dong X.,Nankai University | Li Q.,Jilin University | And 9 more authors.
Journal of the American Chemical Society | Year: 2012

Group 14 elements (C, Si, and Ge) exist as various stable and metastable allotropes, some of which have been widely applied in industry. The discovery of new allotropes of these elements has long attracted considerable attention; however, the search is far from complete. Here we computationally discovered a tetragonal allotrope (12 atoms/cell, named T12) commonly found in C, Si, and Ge through a particle swarm structural search. The T12 structure employs sp 3 bonding and contains extended helical six-membered rings interconnected by pairs of five- and seven-membered rings. This arrangement results in favorable thermodynamic conditions compared with most other experimentally or theoretically known sp 3 species of group 14 elements. The T12 polymorph naturally accounts for the experimental d spacings and Raman spectra of synthesized metastable Ge and Si-XIII phases with long-puzzling unknown structures, respectively. We rationalized an alternative experimental route for the synthesis of the T12 phase via decompression from the high-pressure Si- or Ge-II phase. © 2012 American Chemical Society.

Zhang K.-C.,Bohai University | Liu Y.,Yanshan University | Li Y.-F.,Inner Mongolia University of Science and Technology | Zhu Y.,Nanjing University of Aeronautics and Astronautics
Journal of Applied Physics | Year: 2013

We investigate the magnetic properties of Cu-doped SnO2, which was reported recently in experiments to possess ferromagnetism at room temperature, by first-principles calculations. Our results show that the doped system prefers the antiferromagnetic state for only Cu substitution. The oxygen vacancies are more inclined to form on the sites nearest to Cu defects. However, only those oxygen vacancies away from Cu defects contribute to the ferromagnetism significantly. Our results reveal that Sn vacancies are much easier to form than oxygen vacancies for their much lower formation energy. Moreover, the Cu-doped system always prefers the ferromagnetic state in the presence of Sn vacancies. Therefore, the origin of ferromagnetism in Cu-doped SnO2 can be attributed to the magnetic mediation of Sn vacancies. © 2013 American Institute of Physics.

Li G.,Yanshan University | Li G.,University of Tennessee at Knoxville | Wang Y.Y.,Yanshan University | Liaw P.K.,University of Tennessee at Knoxville | And 2 more authors.
Physical Review Letters | Year: 2012

We report that a series of lanthanide-based bulk metallic glasses show a pressure-induced polyamorphic phase transition observed by in situ angle-dispersive x-ray diffraction under high pressures. The transition started from a low-density state at lower pressures, and went through continuous densification ending with a high-density state at higher pressures. We demonstrate that, under high pressure, this new type of polyamorphism in densely packed metallic glasses is inherited from its lanthanide-solvent constituent and related to the electronic structure of 4f electrons. The found electronic structure inheritance could provide the guidance for designing new metallic glasses with unique functional physical properties. © 2012 American Physical Society.

Wang Y.,University of Science and Technology Beijing | Lin C.,Tsinghua University | Li Q.-L.,Yanshan University
Performance Evaluation | Year: 2010

Email is a crucial part of our daily life, but email systems are facing increasing security threats such as attacks and spam. Because of this, new mechanisms are being provided to defend against the attacks and to reduce the amount of spam in email systems. Up to now, few available works have been reported on the performance evaluation of email systems under attack, which has become necessary for enhancing email security. In this paper, we propose a novel method to study the impact of three types of attacks on email systems. We construct a multiple queueing model to characterize three types of attacks integrally, and study the performance metrics of system security such as system availability, average queue length and information leakage probability. Numerical examples indicate that the approach of this paper is effective and efficient for dealing with the security analysis of email systems under attack. We believe that this work will open a new avenue for the performance evaluation of computer networks under email attack and other forms of attacks. © 2010 Elsevier B.V. All rights reserved.

Zhang F.X.,Yanshan University | Zhang F.X.,University of Michigan | Lang M.,University of Tennessee at Knoxville | Ewing R.C.,Stanford University
Applied Physics Letters | Year: 2015

Gd2Zr2O7 pyrochlore with different degrees of cation disorder were synthesized by isothermal annealing at various temperatures (1100-1550°C), and the related changes in the structure were investigated by ambient and high pressure x-ray diffraction (XRD) measurements. Unit cell parameters increase almost linearly with increasing treatment temperature. The degree of cation order in pyrochlore also increases with the increase of temperature, but saturates at ∼60%. The compressibility of the pyrochlore structures decreases when the degree of cation order increases. High pressure XRD measurements also indicate that the phase stability of Gd2Zr2O7 is not very sensitive to the degree of atomic disorder in the pyrochlore structure. © 2015 AIP Publishing LLC.

Xu J.,Hunan University | Zhuang X.,Hunan University | Guo P.,Hunan University | Zhang Q.,Hunan University | And 10 more authors.
Nano Letters | Year: 2012

Compact wavelength-sensitive optical components are desirable for optical information processing and communication in photonic integrated system. In this work, optical waveguiding along single composition-graded CdS xSe 1-x nanowires were systematically investigated. Under a focused laser excitation, the excited light can be guided passively along the bandgap-increased direction of the nanowire, keeping the photonic energy of the guided light almost unchanged during the whole propagation. In comparison, the excited light is guided actively through incessantly repeated band-to-band reabsorption and re-emitting processes along the bandgap-decreased direction, resulting in a gradual wavelength conversion during propagation. On the basis of this wavelength-converted waveguiding, a concept of nanoscale wavelength splitter is demonstrated by assembling a graded nanowire with several composition-uniform nanowires into branched nanowire structure. Our study indicates that composition-graded semiconductor nanowires would open new exciting opportunities in developing new wavelength-sensitive optical components for integrated nanophotonic devices. © 2012 American Chemical Society.

Tang Y.,Yanshan University | Liu Y.,Yanshan University | Yu S.,Yanshan University | Mu S.,Wuhan University of Technology | And 3 more authors.
Journal of Power Sources | Year: 2014

A facile hydrothermal process with hexadecyltrimethyl ammonium bromide (CTAB) as the soft template is proposed to tune the morphology and size of cobalt hydroxide (Co(OH)2). Monodisperse β-phase Co(OH) 2 nanowires with uniform size are obtained by controlling the CTAB content and the reaction time. Due to the uniform well-defined morphology and stable structure, the Co(OH)2 nanowires material exhibits high capacitive performance and long cycle life. The specific capacitance of the Co(OH)2 nanowires electrode is 358 F g-1 at 0.5 A g -1, and even 325 F g-1 at 10 A g-1. The specific capacitance retention is 86.3% after 5000 charge-discharge cycles at 2 A g-1. Moreover, the asymmetric supercapacitor is assembled with Co(OH)2 nanowires and nitrite acid treated activated carbon (NTAC), which shows an energy density of 13.6 Wh kg-1 at the power density of 153 W kg-1 under a high voltage of 1.6 V, and 13.1 Wh kg -1 even at the power density of 1.88 kW kg-1. © 2014 Elsevier B.V. All rights reserved.

Du J.,Yanshan University | Wen B.,Yanshan University | Melnik R.,Wilfrid Laurier University | Kawazoe Y.,Tohoku University | Kawazoe Y.,RAS Institute of Thermophysics
Acta Materialia | Year: 2014

The "cluster-plus-glue-atom" model can easily describe the structure of complex metallic alloy phases. However, the biggest obstacle limiting the application of this model is that it is difficult to determine the characteristic principal cluster. In the case when interatomic force constants (IFCs) inside the cluster lead to stronger interaction than the interaction between the clusters, a new rule for determining the characteristic principal cluster in the "cluster-plus-glue-atom" model has been proposed on the basis of IFCs. To verify this new rule, the alloy phases in Cu-Zr and Al-Ni-Zr systems have been tested, and our results indicate that the present new rule for determining characteristic principal clusters is effective and reliable. © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Yang L.,Yanshan University | Wang Y.,Yanshan University | Lu X.,Tsinghua University
Zhongguo Jiguang/Chinese Journal of Lasers | Year: 2013

The identification and measuring method of petroleum pollutant is proposed by three-dimensional fluorescence spectroscopy combined with parallel factor analysis. Different concentration solutions of 97# gasoline, 0# diesel and kerosene in CCl4 are as measuring samples. Every petroleum product as one component is considered as a whole and the specific components are not taken into account. By mixing gasoline and diesel with different concentrations and taking kerosene as interfering substance, the three-dimensional fluorescence spectra of samples are measured with FLS920 fluorescence spectrometer. Instrumental error and effect of scattering are removed and the true spectra are obtained by using excitation and emission correction and blank subtraction. The experiments use the second-order calibration algorithms based on the parallel factor to analyze the spectral data and the second-order advantage is adequately exploited. It is proved that the identification and measurement of different components in mixed sample are achieved accurately in existence of interfering substance and good recovery is obtained.

Liu F.C.,CAS Shenyang Institute of Metal Research | Liu F.C.,Yanshan University | Ma Z.Y.,CAS Shenyang Institute of Metal Research | Zhang F.C.,Yanshan University
Journal of Materials Science and Technology | Year: 2012

Friction stir processing (FSP) was applied to extruded Al-Mg-Sc alloy to produce fine-grained microstructure with a grain size of 2.2 μm. Electron backscatter diffraction (EBSD) result showed that the grain boundary misorientation distribution was very close to a random grain assembly for randomly oriented cubes. Super-plastic investigations in the temperature range of 425-500 °C and strain rate range of 1×10-2-1×100 s-1 showed that a maximum elongation of 1500% was achieved at 475 °C and a high strain rate of 1×10-1 s-1. The FSP Al-Mg-Sc exhibited enhanced superplastic deformation kinetics compared to that predicted by the constitutive relationship for superplasticity in fine-grained aluminum alloys. The origin for enhanced superplastic deformation kinetics in the FSP alloy can be attributed to its high fraction of high angle grain boundaries (HAGBs). The analyses of the superplastic data and scanning electron microscopy (SEM) examinations on the surfaces of deformed specimens indicated that grain boundary sliding is the main superplastic deformation mechanism for the FSP Al-Mg-Sc alloy. © 2012 The Chinese Society for Metals.

Wang K.,CAS Shenyang Institute of Metal Research | Liu F.C.,Yanshan University | Ma Z.Y.,CAS Shenyang Institute of Metal Research | Zhang F.C.,Yanshan University
Scripta Materialia | Year: 2011

Friction stir processed Al-Zn-Mg-Cu alloy with grain size 6.2 μm was subjected to superplastic investigation at 500-535°C and a high strain rate of 1 × 10-2 s-1. A maximum elongation of 3250% was achieved at 535°C, which was just above the incipient melting temperature of the sample. Exceptionally high elongation was attributed to the presence of a liquid phase, which served both to relax the stress concentration and to suppress the appearance of cavities during deformation. © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Xue J.,Jilin University | Shen Y.,Jilin University | Zhou Q.,Jilin University | He T.,Jilin University | Han Y.,Yanshan University
International Journal of Hydrogen Energy | Year: 2010

The highly phase-pure perovskite electrolyte, La0.9Sr0.1Ga0.8Mg0.115Co0.085O2.85 (LSGMCO), was prepared by means of glycine-nitrate process (GNP) for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The perovskite phase evolution, sintering, electrical conductivity and electrochemical performance of LSGMCO were investigated. The results show that the highly phase-pure perovskite electrolyte LSGMCO can be obtained after calcining at 1150 °C. The sample sintered at 1450 °C for 20 h in air exhibited a better sinterability, and the relative density of LSGMCO was higher than 95%. The stoichiometric indexes of the elements in the sintered sample LSGMCO determined experimentally by EDS were in good agreement with the nominal composition. The electrical conductivities of the sample were 0.094 and 0.124 S· cm-1 at 800 °C and 850 °C in air, respectively. The ionic conduction of the sample was dominant at high temperature with the higher activation energies. While at lower temperature the electron hole conduction was predominated with the lower activation energies. The maximum power densities of the single cell fabricated with LSGMCO electrolyte with Ce0.8Sm0.2O1.9 (SDC) interlayer, SmBaCo2O5+x cathode and NiO/SDC anode achieved 643 and 802 mW cm-2 at 800 °C and 850 °C, respectively. © 2009 Professor T. Nejat Veziroglu.

Sun H.,Tsinghua University | Yu Y.,Yanshan University | Yu Y.,Northeast Petroleum University | Luo J.,Tsinghua University | And 2 more authors.
CrystEngComm | Year: 2012

ZnO 3D hierarchical structures assembled by different low-dimensional building blocks (nanosheet, nanoneedle) have been successfully synthesized at room temperature without the addition of organic agents. The morphology of the hierarchical structures can be well controlled by simply changing the concentration of the reactant. On the basis of the experimental results, a possible mechanism for the formation of the ZnO 3D hierarchical structures is proposed. The room temperature photoluminescence spectra of the ZnO 3D hierarchical structures show that the relative intensity of UV emission increases from nanosheets to the thin needle flowers and can be tuned by controlling the morphology. Importantly, the thin needle flowers sample exhibits an enhanced photocatalytic performance as compared with the other ZnO nanostructures due to structural features and good optical quality. This journal is © The Royal Society of Chemistry.

Yang H.,Beijing Institute of Technology | Yang H.,Yanshan University | Xia Y.,Beijing Institute of Technology | Shi P.,Beijing Institute of Technology | And 2 more authors.
IEEE Transactions on Automatic Control | Year: 2012

This note generalizes the stability analysis for a high frequency networked control system. The high-frequency networked control system is described by a delta operator system with a high frequency constraint. Stability conditions are given for the high frequency delta operator system. Furthermore, by developing the generalized Kalman-Yakubovic-Popov lemma, improved stability conditions are also presented in terms of linear matrix inequalities. Some experiment results are presented to illustrate the effectiveness of the developed techniques. © 2012 IEEE.

Li H.,Tsinghua University | Yang H.,Yanshan University | Sun F.,Tsinghua University | Xia Y.,Beijing Institute of Technology
Automatica | Year: 2013

This paper presents a new stabilization method for networked control systems (NCSs). An improved stability criterion dependent on both time delay bound and packet loss bound is derived and the corresponding stabilizing controller design technique is also provided. The merit of the proposed method lies in its much less conservatism, which is achieved by explicitly considering NCSs physical properties and by guaranteeing the deceasement of Lyapunov functional at each control signal updating step rather than at each sampling step, which is largely ignored in the existing literature. Illustrative examples are provided to show the advantage and effectiveness of the developed results. © 2013 Elsevier Ltd. All rights reserved.

Fu R.,Yanshan University | Wang H.,Northeastern University China | Zhao W.,Louisiana State University
Expert Systems with Applications | Year: 2016

Driver's states in successive time slices are not independent, especially, fatigue is one of a cognitive state that is developing over time. Meanwhile, driver fatigue is also influenced by some corresponding contextual information at a certain time. In such case, classifying driving state at each time slice separately from it in before and after time slices obviously has less meaning. Therefore, a dynamic fatigue detection model based on Hidden Markov Model (HMM) is proposed in this paper. Driver fatigue can be estimated by this model in a probabilistic way using various physiological and contextual information. Electroencephalogram (EEG), Electromyogram (EMG), and respiration signals were simultaneously recorded by wearable sensors and sent to computer by Bluetooth during the real driving. From these physiological information, fatigue likelihood can be achieved using kernel distribution estimate at different time sections. Contextual information offered by specific environmental factors were used as prior of fatigue. As time proceeds, the posterior of fatigue can be gotten dynamically by this HMM-based fatigue recognition method. Based on the results of the method in this paper, it shows that it provides an effective way in detecting driver fatigue. © 2016 Elsevier Ltd

Yang H.,Yanshan University | Shi P.,University of South Wales | Shi P.,Victoria University of Melbourne | Zhang J.,Beijing University of Chemical Technology | Qiu J.,Hebei University of Science and Technology
Information Sciences | Year: 2012

In this paper, we investigate a robust H∞ control problem for a class of T-S fuzzy systems with time delays by using delta operator approach. It is known that a better control effect can be obtained by using delta operator approach than using shift operator approach for small sampling periods. Furthermore, the delta operator can unify some previous related continuous and discrete fuzzy systems into fuzzy delta operator system framework. Based on Lyapunov-Krasovskii functionals in delta domain, a new fuzzy H∞ state feedback controller is presented in terms of linear matrix inequalities. Some experiment results of an ball and beam model on a laboratory-scale setup are presented to illustrate the effectiveness and potential for the developed techniques. © 2011 Elsevier Inc. All rights reserved.

Yu Y.,Northeast Petroleum University | Wang X.,Yanshan University | Sun H.,Tsinghua University | Ahmad M.,Pakistan Institute of Nuclear Science and Technology
RSC Advances | Year: 2012

3D anatase TiO 2 hollow microspheres assembled with high-energy {001} facets have been synthesized by a one-pot solution method and their lithium storage capacity are investigated. The structural and compositional analysis of the mesoporous TiO 2 product has been performed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) along with selected area electron diffraction (SAED). The Bruauer-Emmett-Teller (BET) specific surface area has been calculated by the nitrogen isotherm curve and pore size distribution of TiO 2 microspheres has been determined by the Barret-Joyner-Halenda (BJH) method. It has been found that the as-prepared TiO 2 electrodes delivered high capacity, good cycling stability and rate capability. The improved electrochemical performance is attributed to the hollow nature and exposed high-energy {001} facets of the 3D assembled structure. Therefore, such a structure can be considered to be an attractive candidate as an electrode material for LIBs. This journal is © 2012 The Royal Society of Chemistry.

Yu J.,CAS Institute of Automation | Dou C.,Yanshan University | Li X.,Yanshan University
IEEE Transactions on Industrial Electronics | Year: 2016

An advanced control scheme for managing a hybrid energy generation system (HEGS) is presented in this paper. A hierarchical management and control architecture based on multi-agent systems (MAS) is discussed. MAS will account for the complex behavior of a hybrid energy supply system. The management and control strategies are implemented through a system of agents based on three tiers. The upper level agents develop overall energy management strategies for a hybrid energy supply system. The middle-level agents integrate coordinated switching controllers. The lower level agents are responsible for dealing with local control strategies. Coordinated switching controllers within the middle-level agents are designed as event-triggered hybrid controllers based on differential hybrid Petri-net (DHPN) models. The operation modes of distributed energy resources (DERs) can smoothly transfer in a coordinated manner due to the coordinated action of the switching controllers according to variation in operating conditions. Finally, simulation results from different scenarios verifying the feasibility of the proposed scheme are offered. © 2016 IEEE.

Li X.,Harbin Institute of Technology | Yang M.,Harbin Institute of Technology | Guo S.,Yanshan University | Li Z.,Yanshan University
Zhongguo Jiguang/Chinese Journal of Lasers | Year: 2012

A special type of waveguides consisting of photonic crystal waveguide and random media is investigated. Based on the photonic crystal waveguide model, a new kind of photonic crystal waveguides with random media is put forward. In this paper, by employing the finite-difference time-domain (FDTD) method, the influences of the embedded ZnO random particles on the frequency, time-domain, gain characteristics of photonic crystal waveguide are studied. The simulation results demonstrate that in the present of random media in the defect layer of photonic crystal, the light in the defect area is obviously amplified, and the localization level is higher than the pure random media and photonic crystal waveguide, respectively. In addition, the interaction time between the random gain medium and the light is lengthened and the threshold is reduced. The waveguide can be used in the field of integrated optical system and microlaser with low threshold.

Xu W.,Harbin Institute of Technology | Zhao H.,Harbin Institute of Technology | Li Y.,Yanshan University | Zheng L.,Yanshan University | And 3 more authors.
Sensors and Actuators, B: Chemical | Year: 2013

Under 980 nm diode laser excitation, efficient upconversion emissions from the Ho3+/Yb3+ codoped CaWO4 phosphor were obtained. The upconversion quantum efficiency was evaluated to be about 3.3% when the power density of the excitation laser was 47 W/cm2. Additionally, temperature dependent blue emissions from the 5F 2,3/3K8 and 5G6/ 5F1 states of Ho3+ ions were studied in the range of 303-923 K. The result demonstrated that using the ratio between the blue luminescence intensities of Ho3+ ions, the sensitivity and the accuracy for optical thermometry achieved here are superior to the previously reported Er3+ green fluorescence based optical temperature sensors. © 2013 Elsevier B.V.

Chen Y.,Yanshan University | Li Y.-L.,Tangshan College | Liu J.-H.,Yanshan University | Zhang R.-J.,Yanshan University
Materials Transactions | Year: 2013

The ordereddisordered phase transformation temperature and time of CuZn alloy before and after 2 GPa pressure treatment were measured by differential scanning calorimeter (DSC). The phase transformation activation energy and Avrami exponent were calculated and the effect of 2 GPa pressure treatment on the microstructure evolution was also discussed based on the kinetic parameters. The results show that 2 GPa pressure treatment on CuZn alloy from ordered (β′) to disordered (β) phase transformation shift to the low temperature region and can shortened the phase transformation time in the subsequent heating process, which is helpful to the formation of the microstructure with a fine grain size in CuZn alloy, but no new phase is generated. © 2013 The Japan Institute of Metals.

Cheng S.,Harbin Institute of Technology | Wang C.,Harbin Institute of Technology | Ma M.,Yanshan University | Shan D.,Harbin Institute of Technology | Guo B.,Harbin Institute of Technology
Thermochimica Acta | Year: 2014

The thermodynamics and kinetics of Zr41.2Ti 13.8Cu12.5Ni10Be22.5 amorphous alloy under non-isothermal condition were evaluated using differential scanning calorimetry (DSC). The first and third exothermic events at the heating rates of 5 K/min and 10 K/min split into two peaks. The local Avrami exponents at various heating rates calculated by the Kolmogorov-Johnson-Mehl-Avrami equations showed different trends. The grain growth was controlled by atom diffusion at all heating rates. But their growth dimensionality reduced from 2 to 1 as heating rates increase at the beginning of crystallization process. The result exhibited that the heating rate had a great influence on growth mechanism, the crystallization peaks of Zr41.2Ti13.8Cu 12.5Ni10Be22.5 amorphous alloy separated into two single-step processes for the change of growth dimensionality. Two fragility indexes evaluated by Angell and DA equations were 44 and 42.5, respectively, implying that the as-cast Zr41.2Ti13.8Cu 12.5Ni10Be22.5 amorphous alloy should be considered as "intermediate glasses". © 2014 Elsevier B.V.

Lu Z.,Yanshan University | Lu C.,State Grid Corporation of China
Dianwang Jishu/Power System Technology | Year: 2013

Along with the demand on CO2 emission reduction becoming more and more explicit, various emission reduction technologies are matured and perfected more and more. It is an important subject to be worth researching to make power generation enterprises ensuring their benefits with the demand on emission reduction being considered through the selection and coordination of different emission reduction technologies. For this purpose, according to the theory of value engineering, a concept of low-carbon benefit, i.e., the quantity of carbon emission reduction under specific investment for a certain emission reduction project during its life cycle, is proposed to make different technologies or assessment methods comparable, and three indices, namely technical feasibility, economic rationality and social friendliness, are established to perform the assessment; then taking the maximization of low-carbon benefit as the objective, a model to coordinate the investment for carbon capture system and wind power system is built; and then an investment planning scheme that confirms to both economic development trend and demand on carbon emission reduction is given; finally, from the perspective of the three indices the assessment is performed to offer guiding opinion for the development of emission reduction projects in future.

Hua C.-C.,Yanshan University | Ding S.X.,University of Duisburg - Essen
IEEE Transactions on Automatic Control | Year: 2011

The model following control problem is addressed for a class of nonlinearly interconnected systems with time delays. The subsystems are with multiple dead-zone actuators and mismatched time-varying disturbances. To deal with the multiple unknown dead-zone inputs, we decompose the system properly based on the input matrix. By using the adaptive method to compensate the unknown parameters, we design a new and simple memoryless controller. The stability of the resultant closed-loop error system is proved by employing a new Lyapunov Krasovskii functional. The designed controller is tolerant to any dead-zone inputs and general time delays. Finally, the simulations are performed and the results show the potential of the proposed method. © 2006 IEEE.

Xu W.,Harbin Institute of Technology | Gao X.,Yanshan University | Zheng L.,Yanshan University | Zhang Z.,Harbin Institute of Technology | And 2 more authors.
Optics Express | Year: 2012

Ho3+/Yb3+ codoped glass ceramic was prepared by meltquenching and subsequent thermal treatment. Under a 980 nm diode laser excitation, upconversion emissions from Ho3+ ions centered at 540, 650, and 750 nm were greatly enhanced compared with those in the precursor glass. Especially, the short-wavelength upconversion emissions centered at 360, 385, 418, 445, and 485 nm were successfully obtained in the glass ceramic. An explanation for this phenomenon is given based on the fluorescence decay curve measurements. In addition, an optical temperature sensor based on the blue upconversion emissions from 5F2,3/3K 8→5I8 and 5F1/ 5G6→5I8 transitions in Ho 3+/Yb3+ codoped glass ceramic has been developed. It was found that by using fluorescence intensity ratio technique, appreciable sensitivity for temperature measurement can be achieved by using the Ho 3+/Yb3+ codoped glass ceramic. This result makes the Ho3+/Yb3+ codoped glass ceramic be a promising candidate for sensitive optical temperature sensor with high resolution and good accuracy. © 2012 Optical Society of America.

Zhang F.,Yanshan University | Zhang F.,Virtual Computer | Zhou Q.,Yanshan University | Zhou Q.,Virtual Computer
Knowledge-Based Systems | Year: 2014

Collaborative recommender systems are known to be particularly vulnerable to profile injection attacks, in which malicious users insert fake profiles into the rating database in order to bias the systems' output. To reduce this risk, a number of methods have been proposed to detect such attacks. However, almost all of them operate in batch mode, i.e., they require examining and processing the entire rating database to detect the attacks. With this problem in mind, we propose an online method (called HHT-SVM) to detect profile injection attacks by combining Hilbert-Huang transform (HHT) and support vector machine (SVM), which can operate incrementally. The underpinning idea of HHT-SVM is the feature extraction method based on an individual user profile. In this paper, we first construct rating series for each user profile based on the novelty and popularity of items. Then, by introducing HHT we use the empirical mode decomposition (EMD) approach to decompose each rating series and extract Hilbert spectrum based features to characterize the profile injection attacks. Finally, we exploit SVM to detect profile injection attacks based on the proposed features. We conduct experiments on the MovieLens 1M dataset and compare the performance of HHT-SVM with PCA-VarSelect and Batch-SVM to demonstrate the effectiveness of the proposed approach. © 2014 Elsevier B.V. All rights reserved.

Hu Z.-P.,Yanshan University | Hu Z.-P.,Virtual Computer | Song S.-F.,Yanshan University
Zidonghua Xuebao/Acta Automatica Sinica | Year: 2012

In order to construct a fast and robust image recognition algorithm, an image recognition algorithm of maximum likelihood estimation sparse representation based on class-related neighbors subspace is proposed in this paper. Considering the different distribution characteristics of each test sample and the class-representative principle of training Samples' selection, instead of constructing the dictionary of sparse representation by all training samples, suitable sub-space is selected and local neighbors of adaptive number that is selected from each class are used to construct the new dictionary based on distance proximity criterion. The training samples are reduced and the original subspace structure of sparse representation is kept at the same time. Then based on the recognition method of maximum likelihood sparse representation, the fidelity of sparse representation is represented by the maximum likelihood function of residuals and the recognition problem is converted to a weighted sparse optimization problem. Experiments results on public available face and handwritten digital databases verify the rationality, recognition speed, and recognition accuracy of the proposed algorithm. The algorithm is robust, especially it can work for in disturbed and occluded images. Copyright © 2012 Acta Automatica Sinica. All rights reserved.

Lu C.-B.,Yanshan University | Wang Z.-H.,Yanshan University | Zhou Y.-H.,Hebei Normal University of Science and Technology | Vreugdenhil M.,University of Birmingham
Acta Pharmacologica Sinica | Year: 2012

Aim:Fast neuronal network oscillation at the γ frequency band (γ oscillation: 30-80 Hz) has been studied extensively in hippocampal slices under interface recording condition. The aim of this study is to establish a method for recording γ oscillation in submerged hippocampal slices that allows simultaneously monitoring γ oscillation and the oscillation-related intracellular events, such as intracellular Ca 2+ concentration or mitochondrial membrane potentials.Methods:Horizontal hippocampal slices (thickness: 300m) of adult rats were prepared and placed in a submerged or an interface chamber. Extracellular field recordings were made in the CA3c pyramidal layer of the slices. Kainate, an AMPA/kainate receptor agonist, was applied via perfusion. Data analysis was performed off-line.Results:Addition of kainate (25-1000 nmol/L) induced γ oscillation in both the submerged and interface slices. Kainate increased the γ power in a concentration-dependent manner, but the duration of steady state oscillation was reduced at higher concentrations of kainate. Long-lasting γ oscillation was maintained at the concentrations of 100-300 nmol/L. Under submerged condition, γ oscillation was temperature-dependent, with the maximum power achieved at 29°C. The induction of γ oscillation under submerged condition also required a fast rate of perfusion (5-7 mL/min) and showed a fast dynamic during development and after the washout.Conclusion: The kainite-induced γ oscillation recorded in submerged rat hippocampal slices is useful for studying the intracellular events related to neuronal network activities and may represent a model to reveal the mechanisms underlying the normal neuronal synchronizations and diseased conditions. © 2012 CPS and SIMM All rights reserved.

Chen D.,China University of Geosciences | Wang L.,Indiana University | Ouyang G.,Yanshan University | Li X.,Yanshan University
Computing in Science and Engineering | Year: 2011

Although the ensemble empirical mode decomposition (EEMD) method and Hilbert-Huang transform (HHT) offer an unrivaled opportunity to understand neural signals, the EEMD algorithm's complexity and neural signals' massive size have hampered EEMD application. However, a new approach using a many-core platform has proven both efficient and effective for massively parallel neural signal processing. © 2011 IEEE.

Xu W.,Yanshan University | Qi H.,Yanshan University | Zheng L.,Yanshan University | Zhang Z.,Harbin Institute of Technology | And 2 more authors.
Optics Letters | Year: 2015

Broadband near-infrared luminescence (NIR) from 720 to 950 nm, which is located in the biological window, has been successfully achieved from Nd3+/Yb3+ codoped hexagonal NaYF4 nanoparticles when excited by 980 nm diode laser. Using the fluorescence intensity ratio technique, the temperature sensing behavior of Nd NIR emissions exhibits various advantages over other rare earth ion based nanothermometers. The light-induced thermal loading for the 980 nm excited NaYF4:Nd3+/Yb3+ was also investigated. The results illustrate the multifunctionality of such fluoride nanoparticles, which could simultaneously act as the luminescent nanothermometers and nanoheaters and find potential application in photothermal therapy. © 2015 Optical Society of America.

Zhou X.-F.,Nankai University | Zhou X.-F.,State University of New York at Stony Brook | Dong X.,Nankai University | Dong X.,State University of New York at Stony Brook | And 6 more authors.
Physical Review Letters | Year: 2014

It has been widely accepted that planar boron structures, composed of triangular and hexagonal motifs are the most stable two-dimensional (2D) phases and likely precursors for boron nanostructures. Here we predict, based on an ab initio evolutionary structure search, a novel 2D boron structure with nonzero thickness, which is considerably, by 50 meV/atom, lower in energy than the recently proposed α-sheet structure and its analogues. In particular, this phase is identified for the first time to have a distorted Dirac cone, after graphene and silicene the third elemental material with massless Dirac fermions. The buckling and coupling between the two sublattices not only enhance the energetic stability, but also are the key factors for the emergence of the distorted Dirac cone. © 2014 American Physical Society.

Xu W.,Harbin Institute of Technology | Gao X.,Yanshan University | Zheng L.,Yanshan University | Zhang Z.,Harbin Institute of Technology | And 2 more authors.
Sensors and Actuators, B: Chemical | Year: 2012

An optical temperature sensor based on the upconversion luminescence of Tm 3+ has been developed. Under a 980 nm diode laser excitation, the fluorescence intensity ratio (FIR) between 700 (Tm 3+: 3F 2, 3 → 3H 6) and 800 nm (Tm 3+: 3H 4 → 3H 6) upconversion emissions from Tm 3+/Yb 3+ codoped oxyfluoride glass ceramic was studied as a function of temperature in the range of 293-703 K. The 3F 2, 3 and 3H 4 states of Tm 3+ are verified to be thermally coupled levels. By using FIR technique, the sensitivity for detecting temperature variations achieved here is better than previous reported rare earth ions fluorescence based temperature sensors. With the advantages of intense upconversion luminescence and absolutely separated 700 and 800 nm emission bands, the Tm 3+/Yb 3+ codoped oxyfluoride glass ceramic is a very promising candidate for accurate optical temperature sensors with much higher sensitivity and resolution. © 2012 Elsevier B.V.

Wang L.,Yanshan University | Tian H.,Yanshan University | Wang D.,Harbin Institute of Technology | Qin X.,Yanshan University | Shao G.,Yanshan University
Electrochimica Acta | Year: 2015

NiO/sulfonated graphene(NiO/SGN) composites were fabricated under the assistance of urea as supercapacitor materials. The composites as prepared possess the leaf vein-like morphology, forming the porous structure that benefits the enhancement of pseudocapacitive performance. Moreover, the introduction of sulfonated graphene contributes to the surface hydroxylation of NiO, which may increase electrochemically active sites on the surface of NiO. The electrochemical measurements demonstrate that specific capacitances of NiO, NiO/thermally reduced graphene(NiO/TRG) and NiO/SGN are 200, 261 and 307 F g-1 at a current density of 5.0 A g-1 respectively, suggesting that the significant improvement of pseudocapacitive performance for NiO/SGN could be expected. The results from electrochemical impedance spectroscopy(EIS) demonstrate that sulfonated graphene can not only provide electron transport channels for its composites similar to thermally reduced graphene, but also benefit the electrolyte penetration in the composites compared with thermally reduced graphene. © 2014 Elsevier Ltd. All rights reserved.

Liu Y.,CAS Shanghai Advanced Research Institute | Li Y.,Yanshan University | Li X.-M.,CAS Shanghai Advanced Research Institute | He T.,CAS Shanghai Advanced Research Institute
Langmuir | Year: 2013

Silanization of magnetic ironoxide nanoparticles with (3-aminopropyl) triethoxylsilane (APTES) is reported. The kinetics of silanization toward saturation was investigated using different solvents including water, water/ethanol (1/1), and toluene/methanol (1/1) at different reaction temperature with different APTES loading. The nanoparticles were characterized by Fourier transform infrared spectroscopy, vibrating sample magnetometry, transmission electron microscopy, and thermal gravimetric analysis (TGA). Grafting density data based on TGA were used for the kinetic modeling. It is shown that initial silanization takes place very fast but the progress toward saturation is very slow, and the mechanism may involve adsorption, chemical sorption, and chemical diffusion processes. The highest equilibrium grafting density of 301 mg/g was yielded when using toluene/methanol mixture as the solvent at a reaction temperature of 70 C. © 2013 American Chemical Society.

Wang H.,Harbin Institute of Technology | Wang H.,Yanshan University | Zhu D.,Harbin Institute of Technology | Zou C.,Harbin Institute of Technology | Wei Z.,Harbin Institute of Technology
Materials and Design | Year: 2012

In this work the microstructure and nanohardness of Ti-48at.%Al alloy solidified under different pressures (normal pressure, 2GPa, 4GPa) were experimental investigated by using a tungsten-carbide six-anvil apparatus. The results indicate that high pressure does not change the phase constitution of Ti-48at.%Al alloy. However, the microstructure changes under high pressure. With increasing pressure, the volume fraction of interdendritic γ (γs) phase decreases and Al concentration in lamellae increases. When the pressure is 4GPa, there is only a little γs embedded in lamellar structure. The volume fraction of γs phase is approximately 17.0% for normal pressure, 8.73% for 2GPa, 0.69% for 4GPa. The lamellar spacings also decrease with pressure, which are 495nm, 345nm, 227nm under normal pressure, 2GPa, 4GPa, respectively. The change in nanohardness was discussed based on the microstructural observations. It shows a certain increase of the nanohardness as the pressure increases from normal pressure to 4GPa. When the pressure is 4GPa, the nanohardness increases by 50.2% compared with that of normal pressure. © 2011 Elsevier Ltd.

Zhang L.,Yanshan University | Han S.,Yanshan University | Han D.,University of Florida | Li Y.,Yanshan University | And 2 more authors.
Journal of Power Sources | Year: 2014

The Ce2Ni7-type (hexagonal, 2H) single phase La 1.6Mg0.4Ni7 alloy has been obtained by annealing the induction melting as-cast sample at 1223 K for 12 h. The relationship between phase structural stability and volume change rate of the three kinds of slabs in Ce2Ni7-type structure is studied. It is found that the volume change rate of Mg-containing [La 1.22Mg0.78Ni4] slab after hydrogenation/ dehydrogenation is larger than that of [LaNi5] I (outer) and [LaNi5] II (inner) slabs, and the consecutive cell volume change of [La1.22Mg0.78Ni4] slab ultimately results in the decomposition of Ce2Ni7-type phase La 1.6Mg0.4Ni7 to amorphous La and Mg phases, nanocrystalline Ni, and CaCu5-type LaNi5 phases, as well as the reduction of electrochemical discharge capacity. Electrochemical studies show that the single phase alloy electrode possesses good discharge capacity (400 mAh g-1) and cycling stability (84.2% after 100 cycles). The improvement in phase structure stability and the cycling stability of the superlattice structure alloys can be achieved by inhibiting the significant volume change of Mg-containing slabs during hydrogenation/dehydrogenation. © 2014 Elsevier B.V. All rights reserved.

Ding H.,Yanshan University | Yang W.,Yanshan University | Huang P.,Yanshan University | Kecskemethy A.,University of Duisburg - Essen
Journal of Mechanical Design, Transactions of the ASME | Year: 2013

It is of great importance in the conceptual creative design of mechanical systems to synthesize as many feasible kinematic structures of mechanisms as possible. However, the methods for the structural synthesis of multiple joint kinematic chains are seldom addressed in literature even though they are widely used in various mechanical products. This paper proposes an automatic method to synthesize planar multiple joint kinematic chains. First, the bicolor topological graph and the bicolor contracted graph are introduced to represent the topological structures of multiple joint kinematic chains. Then, the characteristic number string of bicolor topological graphs is proposed and used to efficiently detect isomorphism in the synthesis progress. Finally, a systematic method for the synthesis of kinematic chains with one multiple joint is proposed, and the whole families of multiple joint kinematic chains with up to 16 links and all possible degrees of freedom are synthesized for the first time. Copyright © 2013 by ASME.

Li X.,Yanshan University | Bowers C.P.,University of Birmingham | Schnier T.,University of Birmingham
IEEE Transactions on Industrial Electronics | Year: 2010

In this paper, we propose an intelligent data-analysis method for modeling and prediction of daily electricity consumption in buildings. The objective is to enable a building-management system to be used for forecasting and detection of abnormal energy use. First, an outlier-detection method is proposed to identify abnormally high or low energy use in a building. Then a canonical variate analysis is employed to describe latent variables of daily electricity-consumption profiles, which can be used to group the data sets into different clusters. Finally, a simple classifier is used to predict the daily electricity-consumption profiles. A case study, based on a mixed-use environment, was studied. The results demonstrate that the method proposed in this paper can be used in conjunction with a building-management system to identify abnormal utility consumption and notify building operators in real time. © 2010 IEEE.

Sun J.,Yanshan University | Xiao Q.,Yanshan University | Wen J.,Yanshan University | Wang F.,China Petroleum Pipeline Engineering Corporation
Measurement: Journal of the International Measurement Confederation | Year: 2014

As it is difficult to identify the scale and aperture of small leaks occurring in a natural gas pipeline, this paper proposes a small leak feature extraction and recognition method based on local mean decomposition (LMD) envelope spectrum entropy and support vector machine (SVM). First, LMD is used to decompose the leakage signals into several FM-AM signals, i.e. into product function (PF) components. Then, based on their kurtosis features, the principal PF components that contain most of the leakage information are selected. Wavelet packet decomposition and energy methods are used to analyze and then reconstruct the principal PF components. The Hilbert transform is applied to these reconstructed principal PF components in order to acquire the envelope spectrum, from which the envelope spectrum entropy is obtained. Finally the normalized envelope spectrum entropy features are input into the SVM as leakage feature vectors in order to enable leak aperture category identification. By analyzing the acquired pipeline leakage signals in field experiments, it shows that this method can effectively identify different leak categories. © 2014 Elsevier Ltd. All rights reserved.

Zhang S.,Yanshan University | Zhang S.,Harbin Institute of Technology | Yan S.,Yanshan University
Optical Engineering | Year: 2012

A novel depth estimation and occlusion boundary recovery approach for a single outdoor image is described. This work is distinguished by three contributions. The first contribution is the introduction of a new depth estimation model, which takes the camera rotation and pitch into account, thus improving the depth estimation accuracy. The second contribution is a depth estimation algorithm, in which we classify the standing object region with visible ground-contact points into three cases according to the information of vanishing point for the first time, meanwhile, we propose the depth reference line concept for estimating the depth of the region with depth change. Two advantages can thereby be obtained: improving the depth estimation accuracy further and avoiding the occlusion mismarked phenomenon. The third contribution is the depth estimation method for the standing object region without visible ground-contact points, which takes the mean of minimum and maximum depth estimation result as region depth and prevents the missing phenomenon of occlusion boundaries. Extensive experiments show that our works are better than previously published results. © 2012 Society of Photo-Optical Instrumentation Engineers (SPIE).

Xu W.,Harbin Institute of Technology | Gao X.,Yanshan University | Zheng L.,Yanshan University | Wang P.,Harbin Institute of Technology | And 2 more authors.
Applied Physics Express | Year: 2012

Under 980nm excitation, the temperature-dependent green upconversion emissions from Er 3+/Yb 3+-codoped CaWO 4 phosphor were studied at temperatures from 294 to 923 K. By using the fluorescence intensity ratio technique, the maximum sensitivity for temperature measurement achieved here is approximately 0.0092 K -1, which is much higher than previously reported temperature sensors based on the fluorescence of Er 3+ions in other host materials. With the efficient upconversion fluorescence, the Er 3+/Yb 3+-codoped CaWO 4 is a very promising candidate for optical high-temperature sensors with high sensitivity and good accuracy. © 2012 The Japan Society of Applied Physics.

Chen J.,Yanshan University | Zhao Q.,Harbin Institute of Technology
Measurement: Journal of the International Measurement Confederation | Year: 2015

The relative tool-work vibration is not generalized enough to represent the actual displacement between tool and workpiece in previous prediction models. This is due to the fact that the vibration was assumed as a steady simple harmonic motion and was only measured before turning process. In this study, an improved method is presented to evaluate the actual relative tool-work vibration. By using this method the vibration information obtained is more credible, as it contains the components caused by machine tool error, cutting force, material property and changing of cutting parameters. Moreover, the swelling effect is analyzed using a new evaluating method and taken into account for predicting surface roughness. On the basis of analyzing both the relative vibration and the swelling effect, a model is proposed for predicting surface roughness Ra in single point diamond turning. Prediction results prove that this model is a closer approximation of the actual turning process as compared to the previous models and shows a higher predicting accuracy of surface roughness. © 2015 Elsevier Ltd. All rights reserved.

Xu W.,Yanshan University | Xu W.,Harbin Institute of Technology | Song Q.,Yanshan University | Zheng L.,Yanshan University | And 2 more authors.
Optics Letters | Year: 2014

Under a 980 nm diode laser excitation, the near-infrared (NIR) emissions from Nd3+:4F7/2, 4F5/2, and 4F3/2 states in Nd3+/Yb3+ codoped CaWO4 powder were studied at temperatures ranging from 303 to 873 K. As the temperature increased, the NIR luminescence intensity was significantly enhanced and nearly 190-fold enhancement was achieved at 873 K compared with that at 303 K. By using the fluorescence intensity ratio technique, the thermometry behaviors through the NIR emissions were investigated. The results illustrate that the sensitivity and the accuracy achieved here are much higher than temperature sensors based on other rare earth ion doped materials. © 2014 Optical Society of America.

Hummer's method is one of most frequently used methods to prepare graphite oxide (GO), an intermediate of graphene nanosheets. The treatment of wastewater containing a large amount of Mn ion and acid produced in this method is very important to protect the environment and use resources efficiently. In this report, facile treatment of wastewater produced in Hummer's method was proposed to remove strong acid and transform Mn ion into Mn3O4 nanoparticles. The as-prepared Mn3O4 nanoparticles have been characterized with X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectrum (FTIR). Their electrochemical performance as cathode material in an asymmetric supercapacitor was also investigated. The primary electrochemical experiment has shown that as-prepared Mn3O4 exhibited good electrochemical performance. © 2013 The Royal Society of Chemistry.

Li Y.,Xinjiang University | Li Y.,Yanshan University | Guan X.,Yanshan University | Luo X.,Yanshan University
International Journal of Systems Science | Year: 2011

This article investigates the problem of delay-dependent exponential stability in mean square for continuous-time linear stochastic systems with structured uncertainties and time-varying delays. By applying descriptor model transformation of the systems, a new type of Lyapunov-Krasovskii functional is constructed, and by introducing some free weighting matrices, some new delay-dependent and delay-independent stability criteria are derived respectively in terms of an LMI algorithm. The new stability criteria are less conservative than existing results. Numerical examples demonstrate that the new criteria are effective and are an improvement over existing results. © 2011 Taylor & Francis.

Hu B.,Yanshan University | Lu Y.,Yanshan University | Tan Q.,Yanshan University | Yu J.,Yanshan University | Han J.,CAS Institute of Automation
Robotics and Computer-Integrated Manufacturing | Year: 2011

A 2(SPSPRSPU) manipulator is a serial-parallel manipulator, which includes an upper manipulator and a lower manipulator. Its stiffness and elastic deformation are studied systematically in this paper. Firstly, a 2(SPSPRSPU) manipulator is constructed and its characteristics are analyzed. Secondly, the formulae for solving the elastic deformation and the compliance matrix of the active legs are derived and the elastic deformation and the total stiffness matrix of this manipulator are solved and analyzed. Finally, a finite element model of this manipulator is constructed and its elastic deformations are solved. The analytic solutions of elastic deformations of this manipulator are coincident with that of its finite element model. © 2010 Elsevier Ltd. All rights reserved.

Dou C.-X.,Yanshan University | Liu B.,University of Sydney | Liu B.,Hunan University of Technology
International Journal of Electrical Power and Energy Systems | Year: 2014

Due to an increased penetration of distributed energy resources, as well as more uncertain operating environment, etc., present distribution power system is facing many challenges. For improving the performance regarding dynamic stability, self-healing, security, as well as economical and environmental benefit, this paper proposes a hierarchical management and control strategy for the high-penetrated distribution grid based on multi-agent systems structure via intelligent switching of operating mode. Corresponding to the complex hybrid behaviors, the hierarchical control scheme is designed as a three-level decentralized coordinated hybrid control. The simulation studies certify that the hierarchical hybrid control is effective and feasible to deal with comprehensive problems of high-penetrated distribution grids. © 2013 Elsevier Ltd. All rights reserved.

Dou C.-X.,Yanshan University | Liu B.,Hunan University of Technology | Liu B.,Australian National University
IEEE Transactions on Smart Grid | Year: 2013

This paper studies the smart control issue for an autonomous microgrid in order to maintain the secure voltages as well as maximize economic and environmental benefits. A control scheme called as multi-agent based hierarchical hybrid control is proposed versus the hierarchical control requirements and hybrid dynamic behaviors of the microgrid. The control scheme is composed of an upper level energy management agent, several middle level coordinated control agents and many lower level unit control agents. The goals of smart control are achieved by designed control strategies. The simulations are given to demonstrate the effectiveness of proposed smart control for an autonomous microgrid. © 2010-2012 IEEE.

Dou C.X.,Yanshan University | Liu B.,Australian National University | Liu B.,Hunan University of Technology
International Journal of Electrical Power and Energy Systems | Year: 2012

With the rapid increase in the rate of distributed generation (DG) penetration depth, the issues of improving micro-grid transient become more significant. This paper investigates a two-level hierarchical hybrid control consists of continuous local controller for each DG unit at the first level coordinated by discrete supervisory control strategies at the secondary level for transients performance enhancement of micro-grid with various DG units following pre-planned or accidental events. The discrete supervisory control strategies are established based on information fusion technique by using wide-area measurements (WAMs) in order to switch each DG subsystem into apposite operational mode following large disturbances. The continuous local controller for each DG unit is designed based on multiple Lyapunov stability theory integrating linear matrix inequality (LMI) techniques in order to regulate the set point of each DG subsystem to reach the best performance and acceptable operation indexes. The effectiveness of the proposed hybrid control is demonstrated through simulation examples. © 2012 Elsevier Ltd. All rights reserved.

Dou C.-X.,Yanshan University | Liu B.,Australian National University | Liu B.,Hunan University of Technology
International Journal of Electrical Power and Energy Systems | Year: 2012

For the purpose of improving comprehensive performance including stability, security and economic benefit of power system, in this study a two-level hierarchical hybrid control is proposed in a real-time manner. First, a novel hybrid model is founded to clearly explain the hybrid dynamical behaviors of the power systems. On the basis of the model, a hybrid control scheme is designed in an interaction manner between the discrete control strategies at the upper level and the continuous dynamical controls at the lower level. The upper level discrete control strategies are responsible for converting operating modes to guarantee the security during significant disturbances and the economic benefit of overall system. After locating operating modes, the lower level local continuous controllers are responsible for regulating dynamic behavior of each controlled unit to obtain the satisfactory stability performance. The effectiveness of the proposed hybrid control is demonstrated through simulation examples. © 2012 Elsevier Ltd. All rights reserved.

Wen S.,Yanshan University | Zheng W.,Yanshan University | Zhu J.,Yanshan University | Li X.,Yanshan University | Chen S.,Zhejiang University of Technology
IEEE Transactions on Systems, Man and Cybernetics Part C: Applications and Reviews | Year: 2012

This paper addresses a virtual force field between mobile robots and obstacles to keep them away with a desired distance. An online learning method of hybrid force/position control is proposed for obstacle avoidance in a robot environment. An Elman neural network is proposed to compensate the effect of uncertainties between the dynamic robot model and the obstacles. Moreover, this paper uses an Elman fuzzy adaptive controller to adjust the exact distance between the robot and the obstacles. The effectiveness of the proposed method is demonstrated by simulation examples. © 2012 IEEE.

Chen Y.,Yanshan University | Yi M.,Yanshan University | Chen C.,China Radio International | Yu C.,Yanshan University
CMES - Computer Modeling in Engineering and Sciences | Year: 2012

Abstract: In this paper, Bernstein polynomials method is proposed for the numerical solution of a class of space-time fractional convection-diffusion equation with variable coefficients. This method combines the definition of fractional derivatives with some properties of Bernstein polynomials and are dispersed the coefficients efficaciously. The main characteristic behind this method is that the original problem is translated into a Sylvester equation. Only a small number of Bernstein polynomials are needed to obtain a satisfactory result. Numerical examples show that the method is effective. Copyright © 2012 Tech Science Press.

Liu B.,Hunan University of Technology | Dou C.,Yanshan University | Hill D.J.,University of Sydney
Systems and Control Letters | Year: 2014

This paper studies the robust exponential input-to-state stability (robust e-ISS) for impulsive systems. New notions of input-to-state exponent (IS-e) and e-property are proposed. Based on the established relation between IS-e and e-property, and the method of variation of constants formula, the equivalent conditions for robust e-ISS have been derived. Then the notion of robust event-e-ISS is defined. The sufficient conditions and the robust regions for robust e-ISS and robust event-e-ISS are also derived by using the IS-e of every subsystem. It shows the whole system may have robust event-e-ISS while every subsystem may have no ISS. It also shows the external disturbances may lead to relatively small robust regions. The results are then specialized to derive the equivalent conditions of interval e-ISS for interval impulsive systems. As an application, the result is used to test the ISS for a controlled micro-grid. © 2014 Elsevier B.V. All rights reserved.

Zhao Y.-H.,Sichuan Normal University | Li Y.-F.,Inner Mongolia University of Science and Technology | Liu Y.,Yanshan University
Applied Physics Letters | Year: 2012

We investigated the p-electron ferromagnetism in alkaline earth doped AlAs by using first-principles calculations. The modified Becke and Johnson potential is used to give a much more reasonable semiconductor gap. Our results demonstrate that ferromagnetic phase is always energetically favorable than the antiferromagnetic and nonmagnetic ones for all considered compounds. Magnetic moments are mainly attributed to the partly filled anionic p states. Especially, half-metallic ferromagnetism has been obtained for Ca- and Sr-doped AlAs, which may be promising for spintronic applications. The calculated results are also useful for understanding of the origin of ferromagnetism in diluted magnetic semiconductors. © 2012 American Institute of Physics.

Zhao S.,Yanshan University | Peng Q.,Yanshan University | Li H.,Yanshan University | Liu B.,Henan Polytechnic University
Journal of Alloys and Compounds | Year: 2014

The aim of this study was to investigate the effects of super-high pressure solidification (2 and 4 GPa) on microstructures, nano-mechanical behaviors and corrosion properties of Mg-30 wt.% Al alloy. The lattice parameter (a) of Mg matrix is decreased and the c/a value is increased owing to the increased Al concentration in Mg matrix. In contrast to the as-cast sample or other super-high pressure samples, the Mg matrix is more homogeneous and the net-like eutectic phase becomes finer after super-high pressure solidification at 800 C under 2 GPa. In addition, the area fraction of eutectic phase is reduced with increasing the exterior pressure and temperature during the solidification, whilst the Al concentration in both the Mg matrix and the eutectic phase are enhanced. The nanoindentation results indicate that both the hardness and Young's modulus are sensitive to the solidification pressure and temperature. The Tafel curves and electrochemical impedance spectroscopes results reveal the corrosion properties of the sample at 800 C under 2 GPa are remarkably improved due to the formation of a compact and continuous oxide layer. © 2013 Elsevier B.V. All rights reserved.

Peng Q.,Yanshan University | Guo J.,Yanshan University | Zhang Q.,Yanshan University | Xiang J.,Yanshan University | And 4 more authors.
Journal of the American Chemical Society | Year: 2014

The functional groups and site interactions on the surfaces of two-dimensional (2D) layered titanium carbide can be tailored to attain some extraordinary physical properties. Herein a 2D alk-MXene (Ti3C 2(OH/ONa)xF2-x) material, prepared by chemical exfoliation followed by alkalization intercalation, exhibits preferential Pb(II) sorption behavior when competing cations (Ca(II)/Mg(II)) coexisted at high levels. Kinetic tests show that the sorption equilibrium is achieved in as short a time as 120 s. Attractively, the alk-MXene presents efficient Pb(II) uptake performance with the applied sorption capacities of 4500 kg water per alk-MXene, and the effluent Pb(II) contents are below the drinking water standard recommended by the World Health Organization (10 μg/L). Experimental and computational studies suggest that the sorption behavior is related to the hydroxyl groups in activated Ti sites, where Pb(II) ion exchange is facilitated by the formation of a hexagonal potential trap. © 2014 American Chemical Society.

Zhou J.,Yanshan University | Bao Z.,Interactive Digital Media Institute | Wang W.,University of New South Wales | Zhao J.,Yanshan University | Meng X.,Renmin University of China
VLDB Journal | Year: 2014

Keyword search over XML data has attracted a lot of research efforts in the last decade, where one of the fundamental research problems is how to efficiently answer a given keyword query w.r.t. a certain query semantics. We found that the key factor resulting in the inefficiency for existing methods is that they all heavily suffer from the common-ancestor-repetition problem. In this paper, we propose a novel form of inverted list, namely the IDList; the IDList for keyword k consists of ordered nodes that directly or indirectly contain k. We then show that finding keyword query results based on the smallest lowest common ancestor and exclusive lowest common ancestor semantics can be reduced to ordered set intersection problem, which has been heavily optimized due to its application in areas such as information retrieval and database systems. We propose several algorithms that exploit set intersection in different directions and with or without using additional indexes. We further propose several algorithms that are based on hash search to simplify the operation of finding common nodes from all involved IDLists. We have conducted an extensive set of experiments using many state-of-the-art algorithms and several large-scale datasets. The results demonstrate that our proposed methods outperform existing methods by up to two orders of magnitude in many cases. © 2013 Springer-Verlag Berlin Heidelberg.

Capaccioli S.,CNR Institute for Chemical and Physical Processes | Capaccioli S.,University of Pisa | Ngai K.L.,CNR Institute for Chemical and Physical Processes | Ngai K.L.,Yanshan University
Journal of Chemical Physics | Year: 2011

We consider experimental data on the dynamics of water (1) in glass-forming aqueous mixtures with glass transition temperature Tg approaching the putative Tg 136 K of water from above and below, (2) in confined spaces of nanometer in size, and (3) in the bulk at temperatures above the homogeneous nucleation temperature. Altogether, the considered relaxation times from the data range nearly over 15 decades from 10-12 to 10 3 s. Assisted by the various features in the isothermal spectra and theoretical interpretation, these considerations enable us to conclude that relaxation of un-crystallized water is highly non-cooperative. The exponent K of its Kohlrausch stretched exponential correlation function is not far from having the value of one, and hence the deviation from exponential time decay is slight. Albeit the temperature dependence of its -relaxation time being non-Arrhenius, the corresponding Tg-scaled temperature dependence has small steepness index m, likely less than 44 at Tg, and hence water is not fragile as a glassformer. The separation in time scale of the - and the -relaxations is small at Tg, becomes smaller at higher temperatures, and they merge together shortly above Tg. From all these properties and by inference, water is highly non-cooperative as a glass-former, it has short cooperative length-scale, and possibly smaller configurational entropy and change of heat capacity at Tg compared with other organic glass-formers. This conclusion is perhaps unsurprising because water is the smallest molecule. Our deductions from the data rule out that the Tg of water is higher than 160 K, and suggest that it is close to the traditional value of 136K. © 2011 American Institute of Physics.

Zhao W.,Henan Polytechnic University | Huang D.,Henan Polytechnic University | Hu Z.Q.,Yanshan University
Key Engineering Materials | Year: 2011

Analysis of BTA deep hole drilling bar on Liquid-Solid Coupled Vibration model, there are vortex and unstability on bending deformation of the rotating boring drilling bar induced by cutting fluid force. At first, the rotating fluid force inside the boring bar was expressed linear physical form, and it's stiffness and damping coefficients were derived by the unsteady reynolds dynamic equation of the fluid. Then establish conditions including eddy and mechanical mechanism of the boring bar by cutting fluid force. The results of analysis show that the solution on coupled vibration model are more accurate than the other vibration model. Coriolis effect is the main reason for eddy or unstability of the deep hole boring bar induced by cutting fluid internal the drilling bar's wall. Some rules are also derived with which cutting parameters can be selected reasonably, which is coincide with the parameters used in heavy machine building industry.

Piao Z.,Yanshan University | Piao Z.,Academy of Armored force Engineering | Xu B.,Academy of Armored force Engineering | Wang H.,Academy of Armored force Engineering | Pu C.,Academy of Armored force Engineering
Tribology International | Year: 2010

The aim of this paper was to address the influence of undercoating on the rolling contact fatigue (RCF) performance of coatings. The Fe-based alloy and Ni/Al alloy were deposited on substrates as surface coating and undercoating by plasma spraying. The failure modes were investigated for two kinds of coatings. RCF performances were compared using Weibull distribution plot. The results showed undercoating played an important role on increasing RCF life of coating for the higher bond strength, and decreasing the scatter of RCF life data. The deposited undercoating could influence the failure mode of coating and prevent the occurrence of catastrophic delamination. © 2009 Elsevier Ltd. All rights reserved.

Kim Y.J.,Inha University | Liu Y.D.,Inha University | Liu Y.D.,Yanshan University | Seo Y.,Seoul National University | Choi H.J.,Inha University
Langmuir | Year: 2013

Core-shell-structured magnetic polystyrene (PS)/inorganic particles were fabricated by Pickering emulsion polymerization using nanosized Fe 2O3 particles as a solid stabilizer. Scanning electron microscopy and transmission electron microscopy confirmed the synthesized PS/Fe2O3 particles to be comprised of a PS surface coated with Fe2O3 nanoparticles. The chemical structure of the composite nanospheres was characterized by Fourier transform infrared spectroscopy and X-ray diffraction. The thermal properties of composite nanospheres and corresponding pure polymer were examined by thermogravimetric analysis. The rheological properties of the core-shell-structured magnetic PS/inorganic particles dispersed in silicone oil were investigated under an external magnetic field strength using a rotational rheometer. The particles with extremely lower density than common magnetic particles exhibited solid-like magnetorheological phase characteristics, and the flow curves were fitted to the Cho-Choi-Jhon model of the rheological equation of state. © 2013 American Chemical Society.

Liu X.,Tianjin Polytechnic University | Xu L.Z.,Yanshan University
Applied Mechanics and Materials | Year: 2013

Dual-stator toroidal motor is a new type of motor. The basic structure and principle of the motor were introduced. The state equations of toroidal motor were presented, the response considering speed fluctuations of the motor was given as well. The objection function was given, and the optimal servo of the motor was designed. The control strategy was used to remove the speed fluctuations and realize desired speed tracking. The state feedback control scheme was obtained and the control signals were also presented. Small speed track errors were achieved and the speed fluctuations of the motor system were eliminated. The results justify the validity of the servo, and offer meaningful instruction for further research and practical application of the novel motor. © (2013) Trans Tech Publications, Switzerland.

Bian L.Y.,Yanshan University | Bian L.Y.,Henan Polytechnic University | Wang Y.H.,Yanshan University | Zang J.B.,Yanshan University | And 2 more authors.
International Journal of Hydrogen Energy | Year: 2012

Platinum nanoparticles supported on undoped nanodiamond (ND) with an average particle size of 50 nm were prepared using a microwave-heating polyol method. This method involves the addition of different amounts of chloroplatinic acid in the synthesis solution to obtain different Pt mass percentages. The Pt/ND catalysts were characterized by energy-dispersive spectroscopy, transmission electron microscopy, and X-ray diffraction. The small and uniform Pt nanoparticles were highly dispersed on ND supports. The mean size of the Pt particles was 4-5 nm. The effect of Pt loading on catalytic performance was investigated. Electrochemical measurements demonstrate that the Pt/ND catalysts prepared with proper Pt mass percentage exhibited a significantly high electrocatalytic activity for methanol electrooxidation. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Ren R.,Academy of Armored force Engineering | Zhang Y.-Y.,Yanshan University | Luo X.-Y.,Yanshan University | Li S.-B.,Yanshan University
International Journal of Automation and Computing | Year: 2010

In this paper, decentralized methods of optimally rigid graphs generation for formation control are researched. The notion of optimally rigid graph is first defined in this paper to describe a special kind of rigid graphs. The optimally rigid graphs can be used to decrease the topology complexity of graphs while maintaining their shapes. To minimize the communication complexity of formations, we study the theory of optimally rigid formation generation. First, four important propositions are presented to demonstrate the feasibility of using a decentralized method to generate optimally rigid graphs. Then, a formation algorithm for multi-agent systems based on these propositions is proposed. At last, some simulation examples are given to show the efficiency of the proposed algorithm. © 2010 Institute of Automation, Chinese Academy of Sciences and Springer-Verlag Berlin Heidelberg.

Li F.,Jilin Agricultural Science and Technology College | Li F.,Yanshan University | Zhang Y.,Xinqiao Hospital | Zhong Z.,University of Troms
International Journal of Molecular Sciences | Year: 2011

The current study evaluated the glucoselowering effect of ganoderma lucidum polysaccharides (GlPS) in streptozotocin (STZ)induced diabetic mice. The diabetic mice were randomly divided into four groups (8 mice per group): diabetic control group, lowdose GlPS treated group (50 mg/kg, GlPS), highdose GlPS treated group (150 mg/kg, GlPS) and positive drug control treated group (glibenclamide, 4 mg/kg), with normal mice used as the control group. Body weights, fasting blood glucose (FBG), serum insulin and blood lipid levels of mice were measured. After 28 days of treatment with GlPS, body weights and serum insulin levels of the GlPS treated groups was significantly higher than that of the diabetic control group, whereas FBG levels was significantly lower. Moreover, total cholesterol (TC), triglyceride (TG) and low density lipoprotein cholesterol (LDLC) levels of the GlPS treated groups had dropped, whereas the high density lipoprotein cholesterol (HDLC) levels had increased. In addition, according to acute toxicity studies, GlPS did not cause behavioral changes and any death of mice. These data suggest that GlPS has an antihyperglycemic effect. Furthermore, considering the GlPS effects on lipid profile, it may be a potential hypolipidaemic agent, which will be a great advantage in treating diabetic conditions associated with atherosclerosis or hyperlipidemia. © 2011 by the authors; licensee MDPI, Basel, Switzerland.

Piao Z.-Y.,Academy of Armored force Engineering | Piao Z.-Y.,Yanshan University | Xu B.-S.,Academy of Armored force Engineering | Wang H.-D.,Academy of Armored force Engineering | Pu C.-H.,Academy of Armored force Engineering
Applied Surface Science | Year: 2011

The rolling contact fatigue (RCF) failure prediction of the coating Fe-Cr alloy coatings was investigated. The acoustic emission (AE) technique was used to monitor RCF tests of the coatings. The failure mechanism was investigated. Results showed AE signals sensitively detected the initiations and propagations of the fatigue cracks within the coatings before the obvious surface material losses. AE signals also reflected the cumulate damage procedure. So the coming RCF failures can be predicted by AE signal responses. Moreover, the micro-defects within the coatings were considered to be the fatigue crack origins. © 2010 Elsevier B.V. All rights reserved.

Li H.,Yanshan University | Sun L.,Southwest Jiaotong University | Zhang Y.,Yanshan University
Applied Thermal Engineering | Year: 2014

In this study, a combined solar thermal heat pump system with seasonal energy storage was proposed for both space heating and domestic hot water (DHW) in cold climate area. Using the TRNSYS software, the proposed system was modeled and compared with a conventional space heating system. Moreover, the influence of major parameters on system performance was analyzed. The investigation results show that the average COP of the total system reaches 3.7 during heating months. On average, the monthly COP for space heating is about 3.2. Compared with the traditional space heating system, the system performance is improved obviously and the monthly energy saving ratio for space heating is about 52%. It is also found that the most appropriate dead-band temperature of the air-to-water heat pump unit is -7 °C, the optimum storage factor should be within the range of 0.5 m3/m2 to 0.8 m3/m 2 and the solar collector area is proposed to be in the range of 130 m2-160 m2. With the specifically proposed parameters, the system performance for space heating is improved by 12.8% compared with the original design. It is concluded that the properly designed solar thermal heat pump heating system can operate effectively and reduce tremendous energy consumption compared with the traditional heating system used in cold climate buildings. © 2014 Elsevier Ltd. All rights reserved.

Wang W.,Xi'an Jiaotong University | Lin Q.,Yanshan University | Lin R.,Xi'an Jiaotong University | Zhang J.,Xi'an Jiaotong University | And 3 more authors.
Experimental Cell Research | Year: 2013

The ligand-activated transcription factor peroxisome proliferator-activated receptor-α (PPARα) participates in the regulation of cellular inflammation. More recent studies indicated that sirtuin1 (SIRT1), a NAD+-dependent deacetylase, regulates the inflammatory response in adipocytes. However, whether the role of PPARα in inflammation is mediated by SIRT1 remains unclear. In this study, we aimed to determine the effect of PPARα agonist fenofibrate on the expressions of SIRT1 and pro-inflammatory cytokine CD40 and underlying mechanisms in 3T3-L1 adipocytes. We found that fenofibrate inhibited CD40 expression and up-regulated SIRT1 expression in tumor necrosis factor-α (TNF-α)-stimulated adipocytes, and these effects of fenofibrate were reversed by PPARα antagonist GW6471. Moreover, SIRT1 inhibitors sirtinol/nicotinamide (NAM) or knockdown of SIRT1 could attenuate the effect of fenofibrate on TNF-α-induced CD40 expression in adipocytes. Importantly, NF-κB inhibitor pyrrolidine dithiocarbamate (PDTC) augmented the effect of fenofibrate on CD40 expression in adipocytes. Further study found that fenofibrate decreased the expression of acetylated-NF-κB p65 (Ac-NF-κB p65) in TNF-α-stimulated adipocytes, and the effect of fenofibrate was abolished by SIRT1 inhibition. In addition, fenofibrate up-regulated SIRT1 expression through AMPK in TNF-α-stimulated adipocytes. Taken together, these findings indicate that PPARα agonist fenofibrate inhibits TNF-α-induced CD40 expression in 3T3-L1 adipocytes via the SIRT1-dependent signaling pathway. © 2013 Elsevier Inc.

Dou Y.-K.,Beijing Institute of Technology | Li J.-B.,Beijing Institute of Technology | Fang X.-Y.,Yanshan University | Jin H.-B.,Beijing Institute of Technology | Cao M.-S.,Beijing Institute of Technology
Applied Physics Letters | Year: 2014

The dielectric properties and microwave attenuation performance of N-doped SiC have been evaluated in 8.2-12.4GHz in the temperature range of 293-673K. The N doping dramatically improves the microwave absorption capability of SiC. The minimum reflection loss of N-doped SiC is enhanced to nearly -30dB with the effective absorption bandwidth [RL(dB) ≤ -10 dB] up to 3GHz at 673K. The excellent high-temperature dielectric properties are attributed to multi-relaxations, originated from the polarization relaxations of dipoles induced by the N doping and vacancy defects. © 2014 AIP Publishing LLC.

Kang Y.-Q.,Beijing Institute of Technology | Cao M.-S.,Beijing Institute of Technology | Yuan J.,Center University for Nationality | Zhang L.,Beijing Institute of Technology | And 2 more authors.
Journal of Alloys and Compounds | Year: 2010

Basalt fiber/nickel core-shell heterostructures with different thicknesses of nickel shells are fabricated successfully. The electromagnetic parameters of basalt fiber/nickel-paraffin composites ranging from 8.2 to 12.4 GHz (X band) are measured for investigating the microwave absorption properties. The electromagnetic parameters of basalt fiber/nickel are several times higher than those of naked basalt fibers due to the formation of the core-shell interface. The measured results indicate that effective electromagnetic match is realized in the whole X band. The values of complex permittivity and permeability of basalt fiber/nickel increase monotonically with the increasing thicknesses of the nickel shells. It is interesting that the reflection loss of basalt fiber/nickel do not show the monotonic character with the increasing thicknesses of the nickel shells. The basalt fiber/nickel with the nickel shell thickness about 300 nm shows the strongest reflection loss. The value of reflection loss is more than 15 dB in the whole X band and reaches 40 dB at 8.9 GHz, while the naked basalt fibers hardly exhibit any microwave absorption. The excellent microwave absorption properties of the basalt fiber/nickel core-shell heterostructures are attributed to the good electromagnetic match between the dielectric loss and magnetic loss. © 2010 Elsevier B.V. All rights reserved.

Zhou Q.,Inner Mongolia University of Technology | Xing J.,Beijing Institute of Technology | Gao Y.,Inner Mongolia University of Technology | Lv X.,Chinese Academy of Sciences | And 3 more authors.
ACS Applied Materials and Interfaces | Year: 2014

The design and development of nanomaterials has become central to the advancement of pseudocapacitive performance. Many one-dimensional nanostructures (1D NSs), two-dimensional nanostructures (2D NSs), and three-dimensional hierarchical structures (3D HSs) composed of these building blocks have been synthesized as pseudocapacitive materials via different methods. However, due to the unclear assembly mechanism of these NSs, reports of HSs simultaneously assembled from two or more types of NSs are rare. In this article, NiCo 2O4 multiple hierarchical structures (MHSs) composed of 1D nanowires and 2D nanosheets are simply grown on Ni foam using an ordered two-step hydrothermal synthesis followed by annealing processing. The low-dimensional nanowire is found to hold priority in the growth order, rather than the high-dimensional nanosheet, thus effectively promoting the integration of these different NSs in the assembly of the NiCo2O4 MHSs. With vast electroactive surface area and favorable mesoporous architecture, the NiCo2O4 MHSs exhibit a high specific capacitance of up to 2623.3 F g-1, scaled to the active mass of the NiCo2O4 sample at a current density of 1 A g-1. A nearly constant rate performance of 68% is achieved at a current density ranging from 1 to 40 A g-1, and the sample retains approximately 94% of its maximum capacitance even after 3000 continuous charge-discharge cycles at a consistently high current density of 10 A g-1. © 2014 American Chemical Society.

Yang H.,Beijing Institute of Technology | Yang H.,Yanshan University | Xia Y.,Beijing Institute of Technology
Automatica | Year: 2012

A strictly positive real control problem for delta operator systems in a low frequency range is presented by using the generalized Kalman- Yakubovič-Popov lemma. The objective of the strictly positive real control problem is to design a controller such that the transfer function is strictly positive real and the resulting closed-loop system is stable. Sufficient conditions for the low frequency strictly positive real controller of the closed-loop delta operator systems are presented in terms of solutions to a set of linear matrix inequalities. A numerical example is given to illustrate the effectiveness and potential for the developed techniques. © 2012 Elsevier Ltd. All rights reserved.

Xu Z.,Yanshan University | Wen W.,University of Kentucky | Zhai T.,University of Kentucky
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2012

The stress field around a pore was analyzed as a function of the pore position in depth in the surface of a linear elastic solid using finite element modeling. It was found that the pore depth dominated the stress field around the pore on the surface and that the maximum stress was increased sharply when the pore intercepted with the surface at its top. Given the applied nominal stress, the magnitude of the maximum main stress only depended on the relative depth of the pore, while the pore size affected the stress distribution in the surface. An elastic-plastic model was also used to account for the yielding effect in the region where stress was over the yield strength. The results still indicated a significant maximum stress concentration when the pore was just buried underneath the surface, but with a lowered value than that of the linear elastic model. These results were consistent with the experimental observations that fatigue cracks were preferably initiated from pores and particles, which were just intercepted at their top with the sample surface or just buried beneath the surface. © The Minerals, Metals & Materials Society and ASM International 2011.

Jiao T.,Yanshan University | Jiao T.,CAS Lanzhou Institute of Chemical Physics | Wang Y.,Yanshan University | Zhang Q.,Yanshan University | And 2 more authors.
Nanoscale Research Letters | Year: 2013

In this paper, new azobenzene imide derivatives with different substituent groups were designed and synthesized. Their gelation behaviors in 21 solvents were tested as novel low-molecular-mass organic gelators. It was shown that the alkyl substituent chains and headgroups of azobenzene residues in gelators played a crucial role in the gelation behavior of all compounds in various organic solvents. More alkyl chains in molecular skeletons in present gelators are favorable for the gelation of organic solvents. Scanning electron microscopy and atomic force microscopy observations revealed that the gelator molecules self-assemble into different aggregates, from wrinkle, lamella, and belt to fiber with the change of solvents. Spectral studies indicated that there existed different H-bond formations between amide groups and conformations of methyl chains. The present work may give some insight to the design and character of new organogelators and soft materials with special molecular structures. © 2013 Jiao et al.

Xu Y.,Yanshan University | Hao X.,Yanshan University | Hao X.,University of Vienna | Franchini C.,University of Vienna | Gao F.,Yanshan University
Inorganic Chemistry | Year: 2013

By means of first-principles calculations based on density functional theory (DFT) and hybrid functional, we studied the structural, electronic, and ferroelectric properties of the two recently synthesized high-pressure perovskite-type (orthorhombic, space group Pnma) and LiNbO3-type (rhombohedral, space group R3c) polymorphs of CdPbO3. Besides providing structural and electronic results in good agreement with available experiments, our results are able to correctly describe the pressure-induced Pnma → R3c structural phase transition and most importantly predict the realization of proper ferroelectric behavior in LiNbO3-type CdPbO3 with an electric polarization of 52.3 μC/cm2. The proper covalent interaction mechanism driving the ferroelectric transition is discussed and explained in terms of the analysis of Born effective charges, potential-energy surfaces, charge density isosurfaces, and electric localization function. © 2013 American Chemical Society.

Li H.,Intelligent Systems Technology, Inc. | Yang H.,Yanshan University | Sun F.,Intelligent Systems Technology, Inc. | Xia Y.,Beijing Institute of Technology
IEEE Transactions on Industrial Electronics | Year: 2014

This paper addresses the output feedback stabilization problem for a class of networked control systems (NCSs) under a multiple-packet transmission policy. To compensate the time delays and packet losses, a sliding-mode predictive controller is constructed by taking full advantage of network transmission capacity. A Kalman predictor is used to estimate the current and predict the future plant states, while sliding-mode control (SMC) is employed to compute the control sequences. The estimated state errors are transformed into a system disturbance, and the stability of the closed-loop NCSs is guaranteed by constructing the robust stabilizing SMC controller. Simulation and experimental results are given to demonstrate the effectiveness of the proposed approach. © 1982-2012 IEEE.

Hua C.-C.,Yanshan University | Liu X.P.,CarletonUniversity
IEEE/ASME Transactions on Mechatronics | Year: 2013

The control design problem is investigated for network-based teleoperation systems under the condition of asymmetric and time-varying delays. The classic teleoperation model is considered forwhich the position of the master is transmitted to the slave site as the control command and the slave torque is directly transmitted to the master in order for the user to have a feeling of the remote interaction. The slave controller is constructed based on the master-slave position error plus a new nonlinear damping function, while the master controller is composed of the transmitted slave torque and the introduced nonlinear damping function. By employing a new Lyapunov Krasovskii functional, we prove the exponential input-to-state stability of the closed-loop system. The relationship is built among the control design parameters and the maximum allowable time delays, which is in the form of linear matrix inequality. Both the simulations and experiments are performed to show the effectiveness of the proposed method. Comparedwith existing approaches, transmission delays considered are both time varying and asymmetric, and the passivity conditions on the remote environment and the human operator are removed. In addition, the method is very simple. © 2012 IEEE.

Ren J.,Yanshan University | Cai B.,Yanshan University | Hu C.,Beijing Institute of Technology
Journal of Convergence Information Technology | Year: 2011

Most existing grid-based stream clustering algorithms are low efficient for high-dimensional data streams due to a large number of cells, and can not handle noise points effectively. In this paper, we propose a novel approach PKS-Stream for clustering data streams, which is based on grid density and index tree Pks-tree. The new index structure Pks-tree is introduced to store the non-empty grid cells, which aims to improve the efficiency of storage and indexing. Simultaneously, we define a novel time based density threshold function to remove the noise points in real time. Based on Pks-tree, the data stream is clustered by grid density in the initial stage. With new data records arriving, the novel pruning strategy is adopted to periodically detect and remove noise points. Also, the generated clusters are dynamically adjusted. The experimental results show that PKS-Stream has better clustering quality and scalability.

Wang G.W.,Beijing Institute of Technology | Xu T.Z.,Beijing Institute of Technology | Feng T.,Yanshan University
PLoS ONE | Year: 2014

In this paper, using the Lie group analysis method, we study the invariance properties of the time fractional fifth-order KdV equation. A systematic research to derive Lie point symmetries to time fractional fifth-order KdV equation is performed. In the sense of point symmetry, all of the vector fields and the symmetry reductions of the fractional fifth-order KdV equation are obtained. At last, by virtue of the sub-equation method, some exact solutions to the fractional fifth-order KdV equation are provided. © 2014 Wang et al.

Zhao L.,Yanshan University | Yang Y.,Yanshan University | Xia Y.,Beijing Institute of Technology | Liu Z.,Yanshan University
IEEE Transactions on Industrial Electronics | Year: 2015

This paper presents an active disturbance rejection position control scheme for a magnetic rodless cylinder in servo systems without pressure states. It is very hard to achieve precise position control of magnetic rodless cylinders due to nonlinearity from large friction force and hysteresis. In this paper, the overshoot, which has a negative influence on position control, is effectively reduced by using a tracking differentiator. Furthermore, the nonlinearity is estimated by a designed extended-state observer. In addition, the self-stable region theory is used to prove the convergence of the extended-state observer. Finally, both control precision and response speed are guaranteed via a nonlinear error feedback controller in the pneumatic system. Experimental results show that the steady-state error within 0.05 mm is achieved for a step signal. © 1982-2012 IEEE.

Zhang P.,Dalian University of Technology | Zhao J.,Dalian University of Technology | Qin Y.,Dalian University of Technology | Wen B.,Dalian University of Technology | Wen B.,Yanshan University
Journal of Nuclear Materials | Year: 2011

The stability and migration behavior of helium and self defects in vanadium and V-4Cr-4Ti alloy are studied by first-principles calculations. The tetrahedral site is found as the most stable configuration for interstitial He, followed by the octahedral and substitutional sites. Among the self defects, the monovacancy has lower formation energy (1.71 eV for V and 2.14 eV for V-4Cr-4Ti alloy) than the self interstitial ones. The migration energies for He hopping between the tetrahedral sites are 0.06 and 0.09 eV for vanadium and V-4Cr-4Ti alloy, respectively. Our calculations reveal strong repulsion between two interstitial He atoms and strong attraction between He and vacancy, suggesting that vacancy acts as a trapping site for He impurity and a seed for further bubble formation. © 2011 Elsevier B.V. All rights reserved.

Zhang Z.,Dalian University of Technology | Zhang Z.,Yanshan University | Zhang N.,Dalian University of Technology | Ma G.,Dalian University of Technology | And 2 more authors.
Scripta Materialia | Year: 2013

Nanotwinned (nt) mercury cadmium telluride (HgCdTe or MCT) was prepared using nanoindentations. The hardness of nt-MCT is 100 times higher than that of monocrystalline counterparts. Transmission electron microscopy shows that the twin lamellae of nt-MCT prior to cyclic nanoindentations are distributed along two directions, intersecting at an angle of 76. The nanotwinned microstructure of nt-MCT is stable after 100 cyclic nanoindentations. The loading-unloading curves of nt-MCT are basically invariable after 50 cycles, and have elastic characteristics. © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Fu X.,Dalian University of Technology | Chen G.,Dalian University of Technology | Zu Y.,Dalian University of Technology | Luo J.,Yanshan University | Zhou W.,Dalian University of Technology
Scripta Materialia | Year: 2013

Directional solidification techniques are not suitable for preparing eutectic ceramics that possess a combination of large dimensions and fine microstructures. Herein, a traditional processing method of melt superheating was adopted to refine the microstructure, and successfully performed on Al 2O3/YAG/ZrO2 bulk eutectic with an interphase spacing of 350 nm. The microstructures can be tailored by controlling the melt superheating treatment conditions. The solidification structure transitions are discussed in terms of the classical nucleation mechanism. © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Zhang P.,Dalian University of Technology | Zhao J.,Dalian University of Technology | Wen B.,Dalian University of Technology | Wen B.,Yanshan University
Journal of Nuclear Materials | Year: 2012

We report the energetics and diffusion behavior of H, He, O, and C impurities in beryllium as fusion materials from first-principles calculations. Among the six interstitial sites in Be, the basal tetrahedral one is most stable for H, He, O, while C prefers to occupy an octahedral site. Solution of O impurity in Be is an exothermic process with solution energy of -2.37 eV, whereas solution of H, C and He is an endothermic process (solution energy: 1.55 eV, 2.46 eV, and 5.70 eV, respectively). Overall speaking, these impurities prefer to diffuse along longer paths. The H and O impurities share the same out-of-plane diffusion path via basal tetrahedral sites, while the He and C impurities in Be mainly diffuse via basal tetrahedral and octahedral sites along the (0 0 1) plane. Diffusion of He in Be is easiest with a lowest barrier of 0.14 eV; whereas H diffusion in Be is also rather fast with migration energies of 0.4 eV. On the contrary, diffusion of C and O impurities is more difficult because of strong bonding with lattice atoms and high energy barriers of 0.42 and 1.63 eV, respectively. Our theoretical results provide the fundamental parameters for understanding the impurity aggregation and bubble formation in early stage of irradiation damage. © 2012 Elsevier B.V. All rights reserved.

Zhang P.,Dalian University of Technology | Zhao J.,Dalian University of Technology | Wen B.,Yanshan University
Journal of Nuclear Materials | Year: 2012

First-principles calculations were performed to illustrate the trapping mechanism of multiple hydrogen atoms in a monovacancy of vanadium solid in terms of the stability of hydrogen-vacancy (mH-VA) complexes and H-H interactions. The preferential site for single H is not vacancy center but close to octahedral interstitial site with solution energy of -0.67 eV. Lower electron density in the presence of vacancy explains why H impurities can be easily trapped at vacancy. Among the possible mH-VA complexes, the 2H-VA conjuration is the most stable complex energetically. According to computed trapping energies, up to six H atoms can be trapped in one monovacancy inside vanadium solid. We also found that H 2 molecule is extremely difficult to survive in a small vacancy complex. The present results provide an elementary picture of the H trapping mechanism as well as H bubble formation in vanadium solid. © 2012 Elsevier B.V. All rights reserved.

Zhao G.,Yanshan University | Mi J.,Taiyuan University of Technology
Chinese Control Conference, CCC | Year: 2016

In reset control systems, the reset law determines reset values at reset time instants. This paper considers the observer-based reset law design for uncertain systems. Model predictive strategy based approach is proposed to design the reset law by minimizing a quadratic cost function, the optimization problem is transformed into linear matrix inequality (LMI) form which can be easily solved by LMI technique. Several examples are given to show the effectiveness of the obtained results. © 2016 TCCT.

Wen B.,Yanshan University | Zhao J.,Dalian University of Technology | Melnik R.,Wilfrid Laurier University | Tian Y.,Yanshan University
Physical Chemistry Chemical Physics | Year: 2011

A novel polymorph of boron nitride (BN) with a body-centered tetragonal structure (bct-BN) has been predicted using first-principles calculations. The structural, vibrational, and mechanical calculations indicated that bct-BN is mechanically stable at zero pressure. When pressure is above 6 GPa, bct-BN becomes energetically more stable than h-BN. The bct-BN appears to be an intermediate phase between h-BN and w-BN due to a low energy barrier from h-BN to w-BN via bct-BN. Our results also indicated that the structure of unknown E-BN phase might be bct-BN. © the Owner Societies 2011.

Wang X.,Yanshan University | Li Q.,Yanshan University | Di Y.,Taiyuan University of Technology | Xing G.,Yanshan University
Fibers and Polymers | Year: 2012

The object of this work is to develop a flame-retardant viscose fiber containing phosphazene derivative. Hexaphenoxycyclotriphosphazene (HPTP) was synthesized and applied to viscose fiber through wet spinning method, with alkyl polysaccharide glycoside as dispersant. Properties of the fiber were tested and discussed. All flame-retardant samples survived 3 ignitions, according to 45 degree slope burning method. Limiting oxygen index value of the flame-retardant fiber containing 16% flame retardant was 28.6 %. The number decreased to 27.5 % after 30 washing cycles. After burning, inflated carbonized coat was found on the fiber surface in scanning electron microscopy image. Thermal gravimetric analysis and differential scanning calorimetry results indicated that the primary decomposition of fiber was moved up by about 20°C, while secondary decomposition was delayed by around 46°C. Damage on mechanical properties of fibers was insignificant. The introduction of HPTP was compatible and the flame retardancy of viscose fiber was greatly improved with limited negative impact. © 2012 The Korean Fiber Society and Springer Netherlands.

Dong J.,Yanshan University | Shao L.,Dalian University of Technology
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2010

In the unsaturated compacted soil triaxial tests under controlled suction conditions, the digital image measurement technique is used, with which the strength and deformation behaviours of unsaturated compacted soil can be studied by considering the influence of end effect. The comparison of test results of the overall specimen and 1/3 zone in the middle of specimen under controlled suction reflects that end effect has a little influence on 1/3 zone in the middle of specimen; the test result of this part can better stand for the actual deformation properties of unsaturated soil; and it provides credible test data for the study of unsaturated soil stress-strain relationship. The end effect has great influence on parameters of shear strength formula, when using the double-stress state variable method to analyze the shear strength. The elastoplastic model of Alonso for unsaturated soil is adopted to further analyze the influence of end effect on numerical calculation.

Wang N.,Tianjin University | Li L.,Tianjin University | Jia Q.,Yanshan University | Dong H.,Yanshan University
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2011

In this paper, using the atomic decomposition method, four coherent dictionaries were designed based on analyzing characteristics of power quality disturbance signals. The matching pursuits (MP) algorithm was optimized by changing searching parameters. The fundamental frequency component, similar fundamental frequency disturbance, oscillatory disturbance and pulse disturbance were extracted from the original signal in sequence using the MP algorithm. During this process, the fundamental frequency component and similar fundamental frequency disturbance were revised before extracting oscillatory disturbance and pulse disturbance. The parameters of the fundamental frequency component and disturbances were gained. According to the relationship of signal energy between the disturbance components and the residual of wiped off fundamental component, the disturbance types of power quality could be classified. Simulation and real data results show that the classification method has high accuracy and signal-to-noise ratios. © Chin. Soc. for Elec. Eng.

Zhang P.,Dalian University of Technology | Zhao J.,Dalian University of Technology | Qin Y.,Dalian University of Technology | Wen B.,Dalian University of Technology | Wen B.,Yanshan University
Journal of Nuclear Materials | Year: 2011

We report the energetics, stability, and diffusion behavior of helium (He), vacancies (V), and helium-vacancy complex clusters HenVm (n, m = 0-4) in vanadium solid from first-principles calculations. For He, vacancy site is more energetically favorable than tetrahedral interstitial by ∼0.74 eV, while hydrogen always prefers to stay in tetrahedral sites in vanadium. He exhibits a low migration energy (0.06 eV) and can be easily trapped in vacancy. A nearly linear relationship between formation energy and the number of He or vacancy is obtained for He or vacancy clusters, and the weak binding energies of He clusters indicate that He clusters themselves are unstable. The binding energies and dissociation energies of He and vacancy to helium-vacancy complex clusters are computed and compared well with the experimental observation from helium desorption spectra. The cluster stability depends on He content. Finally, He diffusion coefficients are predicted to be (1.07-1.27) × 10-8 m2 s-1 at typical temperatures of 600-800 K. We thus propose that He aggregation via vacancy trapping should be the main mechanism for He bubble formation. © 2011 Elsevier B.V. All rights reserved.

Li J.-H.,Shanxi University | Liu W.-Q.,Shanxi University | Tian N.-S.,Yanshan University
Performance Evaluation | Year: 2010

This paper analyzes a discrete-time batch arrival queue with working vacations. In a GeoXG1 system, the server works at a lower speed during the vacation period which becomes a lower speed operation period. This model is more appropriate for the communication systems with the transmit units arrived in batches. We formulate the system as an embedded Markov chain at the departure epoch and by the M/G/1-type matrix analytic approach, we derive the probability generating function (PGF) of the stationary queue length. Then, we obtain the distribution for the number of the customers at the busy period initiation epoch, and use the stochastic decomposition technique to present another equivalent PGF of the queue length. We also develop a variety of stationary performance measures for this system. Some special models and numerical results are presented. Finally, a real-world example in an Ethernet Passive Optical Network (EPON) is provided. © 2010 Elsevier B.V.

Zhang P.,Dalian University of Technology | Zhao J.,Dalian University of Technology | Wen B.,Dalian University of Technology | Wen B.,Yanshan University
Journal of Physics Condensed Matter | Year: 2012

The microscopic mechanism for H and He trapping by vacancy defects and bubble formation in a Be host lattice is investigated using first-principles calculations. A single He atom prefers to occupy a vacancy centre while H does not. He can segregate towards the vacancy from the interstitial site much more easily than H. Both H and He exhibit lower diffusion barriers from a remote interstitial to a vacancy with regard to their diffusion barriers inside a perfect Be solid. Up to five H or 12 He atoms can be accommodated into the monovacancy space, and the BeHe interaction is much weaker than BeH. The physical origin for aggregation of multiple H or He atoms in a vacancy is further discussed. The strong tendency of H and He trapping at vacancies provides an explanation for why H and He bubbles were experimentally observed at vacancy defects in materials. We therefore argue that vacancies provide a primary nucleation site for bubbles of H and He gases inside Be materials. © 2012 IOP Publishing Ltd.

Zhao D.,Yanshan University | Zhao D.,Dalian University of Technology | Li H.,Dalian University of Technology
Smart Materials and Structures | Year: 2010

The seismic response reduction of the semi-active fuzzy control system including a new type of piezoelectric variable-friction damper and fuzzy controller was investigated on the shaking table under various earthquake records for a building model. The performance of the piezoelectric actuator under different preloads was tested in advance to identify its force generation. The feature test of the damper under either constant or linear increased voltage was carried out to study its motion characteristics. Based on the experimental tests of the damper, a semi-active fuzzy control algorithm was presented for the real-time manipulation of the damper according to the structural response. The seismic performance of the building structural model was tested for the uncontrolled, passive-controlled and semi-active controlled cases. The semi-active control effectiveness of the damper was compared with other cases. Experimental results have indicated that the proposed semi-active control system based on the fuzzy controller and piezoelectric variable-friction damper can be more efficient in reducing the inter-storey drifts and accelerations of the building under various earthquake excitations. © 2010 IOP Publishing Ltd.

Xin G.,Dalian University of Technology | Pan H.,Dalian University of Technology | Chen D.,Dalian University of Technology | Zhang Z.,Dalian Jiaotong University | Wen B.,Yanshan University
Journal of Physics and Chemistry of Solids | Year: 2013

N-doped TiO2 was synthesized by calcining a mixture of titanic acid and graphitic carbon nitride (g-C3N4) at temperatures above 500 °C. The final samples were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS), and UV-vis diffuse reflectance spectra. The photocatalytic activity of N-doped TiO2 was studied by assessing the degradation of methylene blue in an aqueous solution, under visible light and UV light irradiation. It was found that the N-doped TiO2 displayed higher photocatalytic activity than pure TiO2, under both visible and UV light. © 2012 Elsevier Ltd. All rights reserved.

Li D.,Yanshan University | Li X.,Yanshan University | Liang Z.,Yanshan University | Voss L.J.,Waikato Hospital | Sleigh J.W.,Waikato Hospital
Journal of Neural Engineering | Year: 2010

Electroencephalogram (EEG) monitoring of the effect of anesthetic drugs on the central nervous system has long been used in anesthesia research. Several methods based on nonlinear dynamics, such as permutation entropy (PE), have been proposed to analyze EEG series during anesthesia. However, these measures are still single-scale based and may not completely describe the dynamical characteristics of complex EEG series. In this paper, a novel measure combining multiscale PE information, called CMSPE (composite multi-scale permutation entropy), was proposed for quantifying the anesthetic drug effect on EEG recordings during sevoflurane anesthesia. Three sets of simulated EEG series during awake, light and deep anesthesia were used to select the parameters for the multiscale PE analysis: embedding dimension m, lag τ and scales to be integrated into the CMSPE index. Then, the CMSPE index and raw single-scale PE index were applied to EEG recordings from 18 patients who received sevoflurane anesthesia. Pharmacokinetic/pharmacodynamic (PKPD) modeling was used to relate the measured EEG indices and the anesthetic drug concentration. Prediction probability (Pk) statistics and correlation analysis with the response entropy (RE) index, derived from the spectral entropy (M-entropy module; GE Healthcare, Helsinki, Finland), were investigated to evaluate the effectiveness of the new proposed measure. It was found that raw single-scale PE was blind to subtle transitions between light and deep anesthesia, while the CMSPE index tracked these changes accurately. Around the time of loss of consciousness, CMSPE responded significantly more rapidly than the raw PE, with the absolute slopes of linearly fitted response versus time plots of 0.12 (0.09-0.15) and 0.10 (0.06-0.13), respectively. The prediction probability Pk of 0.86 (0.85-0.88) and 0.85 (0.80-0.86) for CMSPE and raw PE indicated that the CMSPE index correlated well with the underlying anesthetic effect. The correlation coefficient for the comparison between the CMSPE index and RE index of 0.84 (0.80-0.88) was significantly higher than the raw PE index of 0.75 (0.66-0.84). The results show that the CMSPE outperforms the raw single-scale PE in reflecting the sevoflurane drug effect on the central nervous system. © 2010 IOP Publishing Ltd.

Yang J.,Tianjin University | Zhang G.,Tianjin University | Ma K.,Yanshan University
International Journal of Electrical Power and Energy Systems | Year: 2014

This paper proposes a novel power control and real time pricing approach to match supply with demand for smart grid. We formulate a utility optimization problem to maximize the comfort level of the consumer under a reasonable payment. Then, we develop a power control and pricing algorithm to search for the optimal power consumption and price and give a distributed implementation method. Simulation results show that the algorithm has rapid convergence speed and keeps the balance between electricity supply and demand with real time pricing. © 2014 Elsevier Ltd. All rights reserved.

Li Q.-L.,Yanshan University | Lui J.C.S.,Chinese University of Hong Kong | Wang Y.,University of Science and Technology of China
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2011

In this paper, we provide a matrix-analytic solution for randomized load balancing models (also known as supermarket models) with phase-type (PH) service times. Generalizing the service times to the phase-type distribution makes analysis of the supermarket models more difficult and challenging than that of the exponential service time case which has been extensively discussed in the literature. We describe the supermarket model as a system of differential vector equations, provide a doubly exponential solution to the fixed point of the system of differential vector equations, and analyze the exponential convergence of the current location of the supermarket model to its fixed point. © 2011 IFIP International Federation for Information Processing.

Wu X.,CAS Hefei Institutes of Physical Science | Liu C.,CAS Hefei Institutes of Physical Science | Zhu Z.,CAS Hefei Institutes of Physical Science | Ngai K.L.,Yanshan University | And 2 more authors.
Macromolecules | Year: 2011

The shear mechanical compliance of the glass-rubber transition or softening zone of high molecular weight amorphous polymers typically increases from the glassy compliance of ∼10-10 cm2/dyn up to the rubbery plateau of ∼10-6 cm2/dyn. The contributions from the local segmental relaxation and the Rouse modes cannot account for the entire range of compliance, leaving three decades of compliance in between their contributions unaccounted for. Although new viscoelastic mechanism called sub-Rouse modes with length scales intermediate between the local segmental relaxation and the Rouse modes have been found to fill the void, so far they have not been found in archetypal polymers including polystyrene (PS) and poly(methyl methacrylate) (PMMA). This calls the generality of the existence of sub-Rouse modes into question. Using high precision shear mechanical spectroscopic tool, we report the observation of the sub-Rouse modes in PS and PMMA. From the various properties of the sub-Rouse modes determined, we find that the sub-Rouse modes are intermolecularly coupled like the local segmental relaxation, albeit to a less degree. The results are isomorphic to those found in poly(vinyl acetate) (PVAc) and PVAc-poly(ethylene oxide) (PVAc-PEO) blends. Thus, the sub-Rouse modes and its properties seem general in amorphous polymers. © 2011 American Chemical Society.

Mu Y.,Yanshan University | Mu Y.,Zhongyuan University of Technology | Wang M.,Yanshan University | Yu D.,Yanshan University
International Journal of Refractory Metals and Hard Materials | Year: 2011

Titanium carbonitride, Ti(C, N) has been prepared by combustion synthesis from Ti powder and a carbon-nitrogen precursor. The phase composition of the sample was investigated by X-ray diffraction. The scanning electron microscopy image indicates that the average size of the obtained Ti(C, N) particles was 3 μm. © 2010 Elsevier Ltd. All rights reserved.

Liang S.X.,Yanshan University | Liang S.X.,Hebei University of Engineering | Yin L.X.,Hebei University of Engineering | Jing R.,Yanshan University | And 3 more authors.
Materials and Design | Year: 2014

The Ti-30Zr-5Al-3V (wt.%, TZAV-30) alloy having good mechanical properties is a potential structural material to apply in the aerospace industry. The microstructure and mechanical properties of ZTAV-30 alloy underwent various annealing heat treatments were investigated. The specimens annealed from 500 to 800. °C are composed of α and β two phases. No compound is detected in specimens annealed in that temperature range. The microstructure of annealed specimens is characterized as a typical basketweave microstructure. Three microstructural parameters, thickness of plate α phase, relative fraction of β phase and aspect ratio of α grains, were measured in those annealed specimens. As the alloy annealed in the range from 500 to 800. °C, the average thickness of plate α grains increases with the increasing annealing temperature from 500 to 700. °C but decreases while annealed at 800. °C. The fraction of retained β phase increases with annealing temperature. And the aspect ratio of plate α grains decreases firstly but increases while the annealing temperature is higher than 700. °C. As the variation of those three microstructural parameters, the strength of examined alloy varies from 1269 to 1355. MPa for tensile strength and from 1101 to 1190. MPa for yield strength, inversely, the elongation changes in the range from 12.7% to 8.4%. The strengthening and toughening mechanism of the TZAV-30 alloy with basketweave microstructure is also discussed in this paper. © 2014.

Meng F.,Yanshan University | Liang B.,Zhongyuan University of Technology | Wang M.,Yanshan University
International Journal of Refractory Metals and Hard Materials | Year: 2013

In this study, 3Ti/Si/2C powders were used as raw materials to synthesize Ti3SiC2 by self-propagating high-temperature synthesis (SHS). The phase compositions and morphological characteristics of Ti 3SiC2, as well as the effects of grain granularity on Ti3SiC2 synthesis, were investigated. The reaction paths and dynamic behaviors of the synthesized Ti3SiC2 were studied using combustion front quenching. The results showed that the liquid phase of Ti-Si was formed during SHS. The mechanism for TiC formation exhibited a great effect on Ti3SiC2 synthesis. The proposed reaction mechanism for the synthesis of Ti3SiC2 by SHS suggested that Ti3SiC2 might be formed from the liquid phase of Ti-Si and the solid phase of TiC. © 2013 Elsevier Ltd. All rights reserved.

Liang S.X.,Yanshan University | Liang S.X.,Hebei University of Engineering | Yin L.X.,Hebei University of Engineering | Che H.W.,Hebei University of Engineering | And 4 more authors.
Materials and Design | Year: 2013

Zirconium alloys show attractive properties for astronautic applications where the most important factors are anti-irradiation, corrosion resistance, anti-oxidant, very good strength-to-weight ratio. The effects of Al content (2.2-6.9wt%) on structure and mechanical properties of the hot-rolled ZrTiAlV alloy samples were investigated in this study. Each sample of the hot-rolled ZrTiAlV alloys with Al contents from 2.2wt% to 5.6wt% is composed of the α phase and β phase, meanwhile, the relative content of the α phase increased with the Al content. However, the (ZrTi)3Al intermetallic compound was observed as the Al content increased to 6.9wt%. Changes of phase compositions and structure with Al content distinctly affected mechanical properties of ZrTiAlV alloys. Yield strength of the alloy with 2.2wt% Al is below 200MPa. As Al content increased to 5.6wt%, the yield strength, tensile strength and elongation of the examined alloy are 1088MPa, 1256MPa and 8%, respectively. As Al content further increased to 6.9wt%, a rapid decrease in ductility was observed as soon as the (ZrTi)3Al intermetallic compound precipitated. Results show that the ZrTiAlV alloys with Al contents between 3.3wt% and 5.6wt% have excellent mechanical properties. © 2013.

Li Q.-L.,Yanshan University | Lui J.C.S.,Chinese University of Hong Kong
Discrete Event Dynamic Systems | Year: 2014

Supermarket models are a class of parallel queueing networks with an adaptive control scheme that play a key role in the study of resource management of, such as, computer networks, manufacturing systems and transportation networks. When the arrival processes are non-Poisson and the service times are non-exponential, analysis of such a supermarket model is always limited, interesting, and challenging.This paper describes a supermarket model with non-Poisson inputs: Markovian Arrival Processes (MAPs) and with non-exponential service times: Phase-type (PH) distributions, and provides a generalized matrix-analytic method which is first combined with the operator semigroup and the mean-field limit. When discussing such a more general supermarket model, this paper makes some new results and advances as follows: (1) Providing a detailed probability analysis for setting up an infinite-dimensional system of differential vector equations satisfied by the expected fraction vector, where the invariance of environment factors is given as an important result. (2) Introducing the phase-type structure to the operator semigroup and to the mean-field limit, and a Lipschitz condition can be established by means of a unified matrix-differential algorithm. (3) The matrix-analytic method is used to compute the fixed point which leads to performance computation of this system. Finally, we use some numerical examples to illustrate how the performance measures of this supermarket model depend on the non-Poisson inputs and on the non-exponential service times. Thus the results of this paper give new highlight on understanding influence of non-Poisson inputs and of non-exponential service times on performance measures of more general supermarket models. © 2014 Springer Science+Business Media New York.

Jin M.,Yanshan University | Zhao J.,Yanshan University | Jin J.,Hebei University of Technology | Yu G.,Audio Visual Machinery Research Institute | Li W.,Yanshan University
Measurement: Journal of the International Measurement Confederation | Year: 2014

In the inertial motion capture system, the model complexity and the large amount of computation make the completion of the orientation estimation algorithm rely solely on PC. Because the data processing speed is slow, it is difficult to realize high-speed motion tracking in the embedded system. In order to further expand the application of the motion tracking technology, this paper introduces a two-step Kalman filter, which is suitable for the embedded system. The filter is composed of two sub filters, and is adaptively adjusted based on the variance matching of fuzzy logic. IMU orientation is calculated based on the filtered acceleration vector and the estimated yaw. This approach simplifies the mathematical model, reduces the matrix operations and improves the speed of computation. © 2013 Elsevier B.V. All rights reserved.

Jing R.,Yanshan University | Liang S.X.,Yanshan University | Liang S.X.,Hebei University of Engineering | Liu C.Y.,Yanshan University | And 2 more authors.
Materials and Design | Year: 2013

This study aimed to evaluate the effects of the annealing temperature on the structural evolution and mechanical properties of TiZrAlV alloy. The microstructural evolution and mechanical properties of the alloy were investigated by X-ray diffraction, metallographic analysis, tensile testing, and microhardness testing. The results showed that the thickness of the α phase that precipitated from the parent phase was sensitive to the annealing temperature. With increased annealing temperature, the α-phase tended to exhibit equiaxed grains, except for the specimen annealed at 1050°C. The tensile strength of the equiaxed α grains were also demonstrated to have higher tensile strength than those of the lamellar α phase. The optimal mechanical properties of the alloy was obtained after annealing at 850°C, i.e., σb=1245MPa, σ0.2=1006MPa, and ε=16.89%. © 2013 Elsevier Ltd.

Han P.,Yanshan University | Xiao F.-R.,Yanshan University | Zou W.-J.,Henan University of Technology | Liao B.,Yanshan University
Materials and Design | Year: 2014

The alloy of 75% Cu-25% Sn was utilised and hot-pressed for 4 min at 421, 520 and 600 °C to obtain a self-sharpening bond for diamond honing stones at low sintering temperature. Densification and mechanical tests were performed, and structures were investigated by X-ray diffraction, energy dispersive spectroscopy and scanning electron microscopy. Results showed that the porous structures changed into microporous structures when the hot pressing temperature was increased from 421 °C to 600 °C. The mechanical properties improved from HRB 79.1 to HRB 105.1 in hardness and from 104.2 MPa to 201.4 MPa in transverse rupture strength. After hot pressing at 600 °C, the microstructure consisted of α(Cu) + δ eutectoid and micropores, which meets the requirements of bonds for honing stones. © 2013 Elsevier Ltd.

Dan Liu Y.,Yanshan University | Dan Liu Y.,Inha University | Jin Choi H.,Inha University
Journal of Applied Physics | Year: 2014

Snowman-like anisotropic microparticles with a shell of Fe 3O4 nanoparticles were synthesized using a two-step process, in which snowman-like poly(methyl methacrylate) particles were first synthesized by seeded polymerization, and then coated with Fe3O 4 nanoparticles via an electrostatic interaction between the adsorbed ionic surfactant and Fe3+/Fe2+. The magnetic properties of the particles were examined by vibrating sample magnetometry. Their rheological characteristics when dispersed in silicone oil were observed using a rotational rheometer at a controlled shear rate mode under a range of magnetic field strengths, exhibiting typical magnetorheological characteristics. © 2014 AIP Publishing LLC.

Liu Y.D.,Inha University | Liu Y.D.,Yanshan University | Lee J.,Inha University | Choi S.B.,Inha University | Choi H.J.,Inha University
Smart Materials and Structures | Year: 2013

Silica-coated soft magnetic carbonyl iron (CI) particles with a reduced density and enhanced anti-corrosion properties compared to pristine CI were synthesized and applied as magneto-responsive particles in a magnetorheological (MR) fluid in this study. The MR fluids containing both pristine CI and silica-coated CI particles were injected into a custom-designed MR damper, and their damping characteristics, such as damping force as a function of time, displacement and velocity, were investigated, since vibration attenuation using mechanical damper systems is one of the main applications of MR fluids. Under the same magnetic field strength applied, the damping characteristics of the two MR fluids were observed to be directly related to their yield stresses. © 2013 IOP Publishing Ltd.

Hong C.H.,Inha University | Liu Y.D.,Inha University | Liu Y.D.,Yanshan University | Choi H.J.,Inha University
Applied Clay Science | Year: 2013

The magnetorheological (MR) characteristics of a micron-sized soft magnetic carbonyl iron-based MR fluid were examined using halloysite nanoclay mineral, as an additive. The flow curves measured from a rotational rheometer revealed non-Newtonian Bingham fluid behavior under an applied magnetic field. The sedimentation of the MR fluid with and without the halloysite additive was also measured using a Turbiscan. It was found that the added rod-like hollow nanotubular-structured halloysite improved the sedimentation problem despite the decrease in MR behavior, as determined from the significant decrease in sedimentation rate. © 2013 Elsevier B.V.

Liu Y.D.,Yanshan University | Liu Y.D.,Inha University | Quan X.,Inha University | Hwang B.,Inha University | And 2 more authors.
Langmuir | Year: 2014

Monodisperse core-shell-structured poly(styrene-co-butyl acrylate-co-[2-(methacryloxy)ethyl] trimethylammonium chloride)/silica (PSBM/SiO2) nanoparticles were applied as new electrorheological (ER) materials in which the particles were dispersed in an insulating oil. These nanoparticles were prepared by the consecutive precipitation of cetyltrimethylammonium bromide and negatively charged tetraethylorthosilicate onto the cationic surfaces of PSBM colloidal particles. The successful deposition of the shell phase of the particles and their morphology was examined by transmission and scanning electron microscopy. Their ER properties were studied with a rotational rheometer under different shear modes: controlled shear rate, steady shear under constant shear rate, and creep test. The silica shell allowed the PSBM/SiO2 particles to exhibit typical ER performance under an applied electric field. The dielectric spectra of the PSBM/SiO2-based ER fluid were also recorded using an LCR meter, which was correlated to the ER performance of the ER fluid. © 2014 American Chemical Society.

Xing G.,Yanshan University | Teixeira F.L.,Ohio State University
IEEE Transactions on Antennas and Propagation | Year: 2015

A robust formulation is presented to eliminate overflow, underflow, and convergence problems that arise the computation of tensor Green's functions in cylindrical multilayered media under finite-precision arithmetic. This is done by first introducing a set of rescaled functions associated to the (canonical) cylindrical Bessel and Hankel functions representing standing waves and outgoing waves along the radial direction. The rescaled cylindrical functions are designed to avoid the poor scaling inherent to the canonical cylindrical functions for very small or very large arguments. In addition, a parabolic Sommerfeld integration path is constructed in the spectral complex plane to yield a numerical integration with good convergence properties for a wide range of parameter values. © 2015 IEEE.

Zhang X.,Yanshan University | Dong X.,Chengdu Electric Power Bureau
Dianwang Jishu/Power System Technology | Year: 2013

There are two objective functions in the proposed multi-objective economic dispatching model for low-carbon power system containing wind farms: generation cost and carbon emission. Considering economy of power system the carbon emission should be reduced; considering the risk brought by wind farms, the risk cost should be added in the generation cost; to achieve the energy-saving and carbon emission reduction, the output of wind farms should be increased while the economy of power system is ensured. The proposed multi-objective economic dispatching model for low-carbon power system containing wind farms is solved by improved multi-objective particle swarm optimization algorithm. Simulation results of IEEE 13-machine system show that the proposed multi-objective economic dispatching model is correct and effective.

Wang Q.,Yanshan University | Xu B.,Yanshan University | Sun J.,Nanjing University | Liu H.,University of Saskatchewan | And 4 more authors.
Journal of the American Chemical Society | Year: 2014

Elemental silicon has a large impact on the economy of the modern world and is of fundamental importance in the technological field, particularly in solar cell industry. The great demand of society for new clean energy and the shortcomings of the current silicon solar cells are calling for new materials that can make full use of the solar power. In this paper, six metastable allotropes of silicon with direct or quasidirect band gaps of 0.39-1.25 eV are predicted by ab initio calculations at ambient pressure. Five of them possess band gaps within the optimal range for high converting efficiency from solar energy to electric power and also have better optical properties than the Si-I phase. These Si structures with different band gaps could be applied to multiple p-n junction photovoltaic modules. © 2014 American Chemical Society.

Xiao D.,Yanshan University | Li Y.,Yanshan University | Liu L.,Yanshan University | Wen B.,Yanshan University | And 3 more authors.
Chemical Communications | Year: 2012

A microporous bithiophene polymer (MBP) stable up to 460 °C was synthesized using bithiophene and biphenyl as building blocks through Suzuki cross-coupling. The as-obtained MBP product exhibits green fluorescence peaked at 530 nm, and most interestingly, a two-photon fluorescence was observable from MBP upon excitation by an 800 nm femtosecond laser. © 2012 The Royal Society of Chemistry.

Han Y.,Yanshan University | Yu E.,Yanshan University | Zhang H.,Qinhuangdao Shougang Plate Co. | Huang D.,Yanshan University
Applied Thermal Engineering | Year: 2013

The medium-frequency heat treatment of the high-frequency induction welded pipe was simulated using the finite element method. Results show that an hourglass-shaped temperature field is formed over the weld seam across the wall thickness. The influences of the current frequency, the current density and the distance between the coil and weld seam on the heating efficiency and the temperature difference across the thickness of weld seam are analyzed. The comparative metallographic experiments are conducted to verify the temperature field. The experimental results show that the medium-frequency heat-treatment process parameters have significant effect on the metallographic structure and mechanical properties. By a careful selection of the heat-treatment parameters it is possible to obtain a temperature field that would optimize the welding quality and the energy consumption. A theoretical method is proposed for the quantitative analysis of medium-frequency induction heat-treatment production. © 2012 Elsevier Ltd. All rights reserved.

Zhao Y.,Yanshan University | Ran W.,Yanshan University | He J.,Yanshan University | Huang Y.,Nanyang Technological University | And 6 more authors.
Small | Year: 2015

In this work, MnO2/GO (graphene oxide) composites with novel multilayer nanoflake structure, and a carbon material derived from Artemia cyst shell with genetic 3D hierarchical porous structure (HPC), are prepared. An asymmetric supercapacitor has been fabricated using MnO2/GO as positive electrode and HPC as negative electrode material. Because of their unique structures, both MnO2/GO composites and HPC exhibit excellent electrochemical performances. The optimized asymmetric supercapacitor could be cycled reversibly in the high voltage range of 0-2 V in aqueous electrolyte, which exhibits maximum energy density of 46.7 Wh kg-1 at a power density of 100 W kg-1 and remains 18.9 Wh kg-1 at 2000 W kg-1. Additionally, such device also shows superior long cycle life along with ∼100% capacitance retention after 1000 cycles and ∼93% after 4000 cycles. © 2014 Wiley-VCH Verlag GmbH & Co. KGaA.

Zhou X.-F.,Nankai University | Qian G.-R.,Nanjing University | Dong X.,Nankai University | Zhang L.,Nankai University | And 3 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

A body-centered tetragonal carbon (bct-carbon) allotrope has been predicted to be a transparent carbon polymorph obtained under pressure. The structural transition pathways from graphite to diamond, M-carbon, and bct-carbon are simulated and the lowest activation barrier is found for the graphite-bct transition. Furthermore, bct-carbon has a higher shear strength than diamond due to its perpendicular graphenelike structure. Our results provide a possible explanation for the formation of a transparent carbon allotrope via the cold compression of graphite. We also verify that this allotrope is hard enough to crack diamond. © 2010 The American Physical Society.

Tian F.,Nankai University | Dong X.,Nankai University | Zhao Z.,Yanshan University | He J.,Yanshan University | And 2 more authors.
Journal of Physics Condensed Matter | Year: 2012

A simple (5+6+7)sp 3 carbon (denoted as F-carbon) with eight atoms per unit cell predicted by a newly developed ab initio particle-swarm optimization methodology on crystal structure prediction is proposed. F-carbon can be seen as the reconstruction of AA-stacked or 3R-graphite, and is energetically more stable than 2H-graphite beyond 13.9GPa. Band structure and hardness calculations indicate that F-carbon is a transparent superhard carbon with a gap of 4.55eV at 15GPa and a hardness of 93.9GPa at zero pressure. Compared with the previously proposed Bct-, M- and W-carbons, the simulative x-ray diffraction pattern of F-carbon also well matches the superhard intermediate phase of the experimentally cold-compressed graphite. The possible transition route and energy barrier were observed using the variable cell nudged elastic band method. Our simulations show that the cold compression of graphite can produce some reversible metastable carbons (e.g. M-and F-carbons) with energy barriers close to diamond or lonsdaleite. © 2012 IOP Publishing Ltd.

Cui B.,Yanshan University | Cui B.,Agricultural University of Hebei | Jin Z.,Yanshan University
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2011

For raising automation level of farm operation, improving popularity and adaptability of agricultural robot and advancing its service efficiency, a novel elbow joint of agricultural robot was proposed based on 2-D orthogonal spherical parallel mechanism. The architecture of the mechanism was comprised of a moving platform attached to a frame through two linkages, and the moving platform relative to the frame had two-rotation-freedom. Compared with the others robot elbow joint, the elbow joint had the advantage of structure symmetry, easy assembly, good kinematics character and large workspace. In this paper, the statics performance of the novel elbow joint of agricultural robot was analyzed. Firstly, the static transmission equation of the elbow joint was established by using the principle of virtual works. Further, the force Jacobian matrix was introduced into the statics performance evaluation index by using the norm in Matrix theory, and the torque input stability evaluation index as well as the torque transitivity evaluation index were defined, and the performance atlas of the statics performance evaluation indexes were plotted at the work spaces of the elbow joint. Results showed that the statics transitivity evaluation index and the torque input stability evaluation index of the novel elbow joint presented a symmetric distribution, and the statics transitivity decreased as the angle increasing, and had good static performance and motion stability at initial position nearby 50% range. Important information for optimization design in the novel elbow joint of agricultural robot was provided in this paper.

Cui B.-Y.,Yanshan University | Cui B.-Y.,Agricultural University of Hebei | Jin Z.-L.,Yanshan University
Guangxue Jingmi Gongcheng/Optics and Precision Engineering | Year: 2011

In order to increase the workspace and carrying capacity of a robot shoulder joint and to improve its popularity and adaptability, a novel robot shoulder joint was proposed based on 3-RRR orthogonal spherical parallel mechanism. The statics performance of the robot shoulder joint was analyzed and the structure parameters were designed. Firstly, the static transmission equation of the robot shoulder joint was established based on the principle of virtual works. Then, by use of the norm in matrix theory, the force Jacobian matrix was introduced into the statics performance evaluation index to define the statics performance evaluation index and the global torque performance evaluation index and to plot the performance atlas of the statics performance evaluation index at the work spaces of the robot shoulder joint. Furthermore, the objective optimal function based on the global torque performance evaluation index of the robot shoulder joint was established, and the relation of the objective optimal function and the global torque performance evaluation index was analyzed. By use of fully automatic searching method, the optimal structural parameter ranges of the robot shoulder joint are 49.8-60 mm for the middle follower length of WB and 90-112 mm for the frame connecting rod length of AU. Analysis results show that the robot shoulder joint has good static transmission performance at the initial position, and the static transmission performance decreases with increasing turning angle. Finally, using a set of optimal structural size parameters, a novel robot shoulder joint was designed.

Yang Z.,Jiangsu Xuzhou Construction Machinery Research Institute | Du J.,Yanshan University | Wen B.,Yanshan University | Hu C.,Jiangsu Xuzhou Construction Machinery Research Institute | And 2 more authors.
Intermetallics | Year: 2013

First principles calculations have been performed to study the structural, heats of formation, elastic properties, and densities of states of eight Mg-AE (AE = Ca, Sr, Ba) intermetallic compounds. The obtained results indicate that with increasing atom weight and concentration of AE, the bulk moduli decrease monotonously, and the larger the electronegativity difference is, the smaller the elastic modulus would be. Based on the ratios of shear moduli to bulk moduli, it has been found that Mg 2Ca, Mg 38Sr 9, Mg 2Sr, Mg 17Ba 2 and Mg 23Ba 6 behave in a brittle manner, and Mg 17Sr 2, Mg 23Sr 6 and Mg 2Ba behave in a ductile manner. Our calculations of the densities of states, heats of formation, and elastic constants of all the eight Mg compounds indicate that they are all conductors, thermodynamically and mechanically stable. © 2012 Elsevier Ltd. All rights reserved.

Yang Z.,Jiangsu Xuzhou Construction Machinery Research Institute | Shi D.,East China University of Technology | Wen B.,Yanshan University | Melnik R.,Wilfrid Laurier University
Journal of Alloys and Compounds | Year: 2012

Structural, elastic and electronic properties, as well as heats of formation, of seven Ca-Zn intermetallic compounds have been studied by using first principles methods. It was found that with increasing Zn concentration, the bulk moduli and shear moduli of Ca-Zn intermetallic compounds increase monotonically. Our results also indicate that Ca 3Zn, Ca 5Zn 3, and CaZn are ductile, while CaZn 2, CaZn 5, CaZn 11, and CaZn 13 are brittle. Furthermore, calculations of the electronic properties and heats of formation indicate that seven Ca-Zn intermetallic compounds, considered in this work, are all conductors and thermodynamically stable. © 2012 Elsevier B.V.

Kang Y.,Yan'an University | Shao X.,Yanshan University | Wang C.,Yanshan University
Shiyou Kantan Yu Kaifa/Petroleum Exploration and Development | Year: 2012

Production characteristics of coalbed methane wells in Fanzhuang and Hancheng mining areas, which are typical high and mid rank coal fields, are analyzed, compared, and summarized. And the effects of perforating thickness, number of perforated layers, unloading technology and stimulation treatment on gas production are analyzed. Coalbed methane wells in Fanzhuang and Hancheng mining areas are divided into four categories: high gas-production wells, middle gas-production wells, low gas-production wells and little gas-production wells. High gas-production wells have gas production of more than 3000 m3/d, long stable production period, slow and smooth declining rate, high peak production and short unloading period. Middle gas-production wells have gas production between 1000 m3/d and 3000 m3/d, shorter stable production period, longer unloading period and quick declining rate at the early stage. Low gas-production wells have gas production of less than 1000 m3/d, short stable production period, high water output, long unloading period and discontinuous production. Little gas-production wells have large water output, slow reducing rate of liquid level and a low or zero surface casing pressure. Based on the production characteristics, three types of production modes of coalbed methane wells are summed up. In view of specific examples, it is discussed quantitatively and qualitatively how different factors affect the gas production of coalbed methane wells. It turns out that, generally, the perforating thickness of coalbed methane wells should be larger than 5 m and the layers of perforation should not exceed 3 layers. A proper unloading system is needed to maintain stable and persistent high gas production, and secondary stimulation treatments can bring about significant production increase.

Li X.,Yanshan University | Zhong F.,Agricultural University of Hebei
Inflammation | Year: 2014

Exposure to nickel (Ni2+) can trigger allergic reactions in susceptible individuals, which is widely accepted as the major cause of allergic contact hypersensitivity (CHS) worldwide. Although Ni2+-induced proinflammatory responses clearly play a pivotal role in CHS, the underlying molecular mechanism has not been fully defined. Here we report that Ni 2+ activates the NLRP3-ASC-caspase-1 immune signaling pathway in antigen-presenting cells, leading to the proteolytic processing and secretion of a proinflammatory cytokine, interleukin-1β (IL-1β). The activation of this signaling axis is independent of phagolysosome-cathepsin B pathway. Instead, Ni2+ induces mitochondrial reactive oxygen species accumulation and cation fluxes, both of which are required for activating the NLRP3-ASC-caspase-1 pathway. Together, these results identified a novel innate immune signaling pathway (NLRP3-ASC-caspase-1-IL-1β) activated by Ni 2+ and provided a mechanistic basis for optimizing the therapeutic intervention against Ni2+-induced allergy in patients. © 2013 Springer Science+Business Media New York.

Li C.H.,Beijing University of Technology | Cao L.B.,Beijing University of Technology | Su J.G.,Beijing University of Technology | Su J.G.,Yanshan University | And 2 more authors.
Proteins: Structure, Function and Bioinformatics | Year: 2012

Understanding the key factors that influence the preferences of residue-nucleotide interactions in specific protein-RNA interactions has remained a research focus. We propose an effective approach to derive residue-nucleotide propensity potentials through considering both the types of residues and nucleotides, and secondary structure information of proteins and RNAs from the currently largest nonredundant and nonribosomal protein-RNA interaction database. To test the validity of the potentials, we used them to select near-native structures from protein-RNA docking poses. The results show that considering secondary structure information, especially for RNAs, greatly improves the predictive power of pair potentials. The success rate is raised from 50.7 to 65.5% for the top 2000 structures, and the number of cases in which a near-native structure is ranked in top 50 is increased from 7 to 13 out of 17 cases. Furthermore, the exclusion of ribosomes from the database contributes 8.3% to the success rate. In addition, some very interesting findings follow: (i) the protein secondary structure element π-helix is strongly associated with RNA-binding sites; (ii) the nucleotide uracil occurs frequently in the most preferred pairs in which the unpaired and non-Watson-Crick paired uracils are predominant, which is probably significant in evolution. The new residue-nucleotide potentials can be helpful for the progress of protein-RNA docking methods, and for understanding the mechanisms of protein-RNA interactions. © 2011 Wiley Periodicals, Inc.

Han N.,Longdong University | Luo X.,Yanshan University
Chinese Control Conference, CCC | Year: 2016

The problems of tracking and distributed formation for leader-following heterogeneous multi-agent systems are investigated in this paper. Firstly, without considering the variable time delay, the formation control protocols are proposed for heterogeneous multi-agent systems under switching topologies. By using Lyapunov theory, the sufficient condition that the protocol can make the followers form the desired formation and keep consensus with the virtual leader is given. Secondly, considering the variable time delay, the protocols for the multi-agent systems under fixed topology are designed, and the sufficient condition that the protocol satisfies to achieve the control goal is given in the form of LMIs. Finally, the simulation results are exhibited to illustrate the effectiveness of the designed protocols. © 2016 TCCT.

Xu X.,Beijing University of Technology | Su J.,Beijing University of Technology | Su J.,Yanshan University | Chen W.,Beijing University of Technology | Wang C.,Beijing University of Technology
Journal of Biomolecular Structure and Dynamics | Year: 2011

The thermo-stability and unfolding behaviors of a small hyperthermophilic protein Sso7d as well as its single-point mutation F31A are studied by molecular dynamics simulation at temperatures of 300 K, 371 K and 500 K. Simulations at 300 K show that the F31A mutant displays a much larger flexibility than the wild type, which implies that the mutation obviously decreases the protein's stability. In the simulations at 371 K, although larger fluctuations were observed, both of these two maintain their stable conformations. High temperature simulations at 500 K suggest that the unfolding of these two proteins evolves along different pathways. For the wild-type protein, the C-terminal alpha-helix is melted at the early unfolding stage, whereas it is destroyed much later in the unfolding process of the F31A mutant. The results also show that the mutant unfolds much faster than its parent protein. The deeply buried aromatic cluster in the F31A mutant dissociates quickly relative to the wild-type protein at high temperature. Besides, it is found that the triple-stranded antiparallel β-sheet in the wild-type protein plays an important role in maintaining the stability of the entire structure. ©Adenine Press (2011).

The title compounds were assembled through charge-assisted hydrogen bonds, multiple C-H⋯O bonds and π-π stacking, and structurally characterized. The compounds, with dramatic differences in the cations of their tectons, are isostructural and featured 1D ribbons of alternating anions and cations. The 1D ribbons are aligned edge-to-edge to generate 2D sheets through arrays of C-H⋯O bonds. The 2D sheets then stack directly upon each other, resulting in alternating homogeneous columns of bipyridinium cations and oxalate anions in the structure. This journal is © The Royal Society of Chemistry 2012.

Sun W.,Yanshan University | Wang Y.,Hong Kong Polytechnic University | Tian N.,Yanshan University
4OR | Year: 2012

In this paper we study unobservable Markovian queueing systems with three types of setup/closedown policies: interruptible, skippable and insusceptible setup/closedown policies, respectively. For a system with the interruptible setup/closedown policy, service starts as soon as a customer arrives during a closedown time; However, for a system with the skippable setup/closedown policy, customers arriving in a closedown time (if any) can be served only after the closedown time finishes and the following setup time can be skipped; Then for a system with the insusceptible setup/closedown policy, customers arriving in a closedown time can't be served until the following setup time finishes. We assume that customers need a price for service, and derive the equilibrium and socially optimal balking strategies for customers as well as the maximal social welfare. Then we make pricing control to motivate customers to adopt the optimal strategies and obtain an appropriate price that also maximizes server's profit. Moreover, we numerically make some comparisons between the various performance measures. © 2012 Springer-Verlag.

Liu J.,Yanshan University | Han S.,Yanshan University | Li Y.,Yanshan University | Yang S.,Yanshan University | And 3 more authors.
Journal of Alloys and Compounds | Year: 2013

In this paper, the phase transformation and electrochemical characteristics of the as-cast and annealed La0.75Mg0.25Nix (x = 3.0, 3.3, 3.5, 3.8) alloys were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), pressure composition isotherm (PCI) and electrochemical measurements. The as-cast alloys were composed of LaNi 5, (La,Mg)2Ni7 and (La,Mg)Ni3 phases. Phase transformation of LaNi5 and (La,Mg)Ni3 phases into (La,Mg)2Ni7 phase occurred during annealing treatment, leading to the increase of the (La,Mg)2Ni7 phase and decrease or even depletion of the LaNi5 and (La,Mg)Ni3 phases. The two plateaus observed in P-C isotherms of the as-cast alloys tended to become single and the plateau pressure dropped after the phase transformation by annealing. Electrochemical study showed that for the alloy electrodes with and without annealing treatment, the maximum discharge capacity and HRD initially increased then decreased with × increasing from 3.0 to 3.8. The transformation of the LaNi5 and (La,Mg)Ni3 phases into (La,Mg)2Ni7 phase favored the maximum discharge capacity and cycling stability but suppressed the activation as well as HRD of the La0.75Mg0.25Nix (x = 3.0, 3.3, 3.5, 3.8) alloy electrodes. The annealing treatment significantly improved the cycling stability of the alloy electrodes by alleviating the pulverization and oxidation degree of the electrode alloys. © 2012 Elsevier Ltd. All rights reserved.

Huang Z.,Yanshan University | Chen Z.,Yanshan University | Liu J.,Beijing University of Technology | Liu S.,Yanshan University
Journal of Mechanisms and Robotics | Year: 2011

It is difficult to manufacture parallel manipulators (PMs) with multiple revolute joint axes intersecting at one point. These types include the 3DOF spherical parallel manipulators (SPMs), the 4DOF 3R1T and 2R2T PMs, the 5DOF 3R2T PMs, etc. PMs with this problem are hard to achieve the expected mobility. In this paper, a 3-RPS cubic PM is studied, which has three rotational freedoms and is without those intersecting axes. The motion property of this PM will not change when the manufacturing errors exist. In order to show its orientation capability, the orientation workspace of this PM is analyzed. More discussions about the differences between the traditional SPMs and this PM are proposed. The results show that compared with the traditional SPMs, this 3-RPS cubic PM can also achieve three rotational motions with an enough orientation capability for applications and it has the advantage of easy fabrication. © 2011 American Society of Mechanical Engineers.

Li Y.,Yanshan University | Wang Z.,Yanshan University | Lv X.-J.,CAS Technical Institute of Physics and Chemistry
Journal of Materials Chemistry A | Year: 2014

To improve the electrochemical performance of TiO2 nanotube as anode materials in Li-ion batteries, N-doped TiO2 nanotube/N-doped graphene composites were prepared via hydrothermal synthesis followed by heat treatment in the presence of urea. The N-doped TiO2 nanotubes/N-doped graphene composites were characterized by X-ray powder diffraction, transition electron microscopy, scanning electron microscopy and X-ray photoelectron spectroscopy. The electrochemical experiments demonstrated that the as-prepared sample exhibit superior discharge capacity (up to 369 mA h g-1 at 0.1 A g-1) as well as excellent rate ability (90 mA h g-1 even at 5 A g-1 at 180th cycle) as anode materials in lithium-ion batteries. © the Partner Organisations 2014.

Zhou Y.,Yanshan University | Yin L.-Q.,Hebei Normal University of Science and Technology
Chinese Physics Letters | Year: 2012

We report a new self-detection control system for leaking pipes by making use of the surface defects of 1D photonic crystals, where the key concept is analog to the Bragg fiber structure. The current low costs and coating techniques of SiO 2 are beneficial to the applications, and its error is below the standard requirement. The problem of leaking pipes can be resolved by devising a remote pipeline control system which combines a long-distance pipeline and a signal transmission system. © 2012 Chinese Physical Society and IOP Publishing Ltd.

Du G.-J.,Yanshan University | Wang J.,Dalian Jiaotong University
Cailiao Kexue yu Gongyi/Material Science and Technology | Year: 2011

Forming mechanism of the residual stress field in the case of carburize quencher is detail expounded. Based on the parameters thermal conductivity coefficient, specific heat, convection coefficient, facies change temperature, specific enthalpy and thermal expansion coefficient etal. which are obtain by experiment, the numerical simulation about the course of carburize with multi time-varying parameters by the finite element software ANSYS, obtain the correspond to data of forming the stress field in the course of carburize and the residual stress field after carburize. The effects of carburize depth on residual stress field are discussed, so providing reliable theory gist for effective controlling the formation of residual stress field.

Wang Z.,Yanshan University | Li Y.,Yanshan University | Lv X.-J.,CAS Technical Institute of Physics and Chemistry
RSC Advances | Year: 2014

Here we report the electrochemical performance of N-doped ordered mesoporous carbon as an anode in sodium ion batteries for the first time. The experiments show that high reversible capacities as well as good rate performance can be achieved at room temperature; indicating a promising future for ordered mesoporous carbon in Na-ion batteries. © The Royal Society of Chemistry 2014.

Wang Y.,Yanshan University | Li B.,North China Institute of Aerospace Engineering
Journal of Optical Communications and Networking | Year: 2010

An optical code-labeled router that performs packet forwarding through optical code label swapping (OCLS) based on code division multiplexing technology is proposed. It can enhance the processing speed of packets that can adapt to the growth of data and the aggregation of data service. The throughput of the router increases obviously since the optical code division multiplexing (OCDM) paths on the same wavelength can be processed in parallel. Moreover, it is attractive for its traffic control, bandwidth efficiency, protocol transparency, channel granularity, and so on. © 2010 Optical Society of America.

Xin G.,Yanshan University | Wang Y.,Yanshan University | Liu X.,Yanshan University | Liu X.,Hebei Normal University of Science and Technology | And 3 more authors.
Electrochimica Acta | Year: 2015

A graphene-based composite was prepared by the in-situ growth of a self-supporting graphene (SSG) on a flexible graphite sheet (FGS) via electrochemical intercalation of FGS and then the electrodeposition of a thin, homogeneous, and conformal polyaniline (PANI) film. The maximum areal capacitance of 1.36 F cm-2 and specific capacitance based on PANI of 491.3 F g-1 were achieved for the prepared FGS-SSG/PANI composite. The good cycling stability of FGS-SSG/PANI was proved by cyclic voltammetry at a scan rate of 50 mV s-1 for 3000 cycles. The symmetric supercapacitor device assembled using FGS-SSG/PANI composite electrodes exhibited a high energy density of 46 W h kg-1 at a power density of 275 W kg-1 on the basis of the total mass of PANI (∼ 10% of the total mass of the flexible electrodes). The good electrochemical properties indicate that the FGS-SSG/PANI is a promising flexible electrode for supercapacitors. ©2015 Elsevier Ltd. All rights reserved.

Liu H.,University of Chinese Academy of Sciences | Yang H.,University of Chinese Academy of Sciences | Hao X.,CAS Changchun Institute of Applied Chemistry | Xu H.,CAS Changchun Institute of Applied Chemistry | And 4 more authors.
Small | Year: 2013

A class of core-shell nanoparticles possessing a layer of biocompatible shell and hydrophobic core with embedded oxygen-sensitive platinum-porphyrin (PtTFPP) dyes is developed via a radical-initiated microemulsion co-polymerization strategy. The influences of host matrices and the PtTFPP incorporation manner on the photophysical properties and the oxygen-sensing performance of the nanoparticles are investigated. Self-loading capability with cells and intracellular-oxygen-sensing ability of the as-prepared nanoparticle probes in the range 0%-20% oxygen concentration are confirmed. Polymeric nanoparticles with optimized formats are characterized by their relatively small diameter (<50 nm), core-shell structures with biocompatible shells, covalent-attachment-imparted leak-free construction, improved lifetime dynamic range (up to 44 μs), excellent storage stability and photostability, and facile cell uptake. The nanoparticles' small sensor diameter and core-shell structure with biocompatible shell make them suitable for intracellular detection applications. For intracellular detection applications, the leak-free feature of the as-prepared nanoparticle sensor effectively minimizes potential chemical interferences and cytotoxicity. As a salient feature, improved lifetime dynamic range of the sensor is expected to enable precise oxygen detection and control in specific practical applications in stem-cell biology and medical research. Such a feature-packed nanoparticle oxygen sensor may find applications in precise oxygen-level mapping of living cells and tissue. Core-shell-type oxygen nanosensors with optimized formats are developed. They are characterized by their relatively small diameter (<50 nm), biocompatible and protective shells, covalent-attachment-imparted leak-free construction, improved lifetime dynamic range (up to 44 μs), and excellent storage stability and photostability. Their facile cell uptake and ability to sense intracellular oxygen are confirmed. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Xie Y.,University of Tokyo | Xie Y.,Yanshan University | Bell C.,University of Tokyo | Bell C.,Japan Science and Technology Agency | And 4 more authors.
Nano Letters | Year: 2010

Biased conducting-tip atomic force microscopy (AFM) has been shown to write and erase nanoscale metallic lines at the LaAlO3/SrTiO3 interface. Using various AFM modes, we show the mechanism of conductivity switching is the writing of surface charge. These charges are stably deposited on a wide range of LaAlO3 thicknesses, including bulk crystals. A strong asymmetry with writing polarity was found for 1 and 2 unit cells of LaAlO3, providing experimental evidence for a theoretically predicted built-in potential. © 2010 American Chemical Society.

Lv X.-J.,CAS Technical Institute of Physics and Chemistry | She G.-W.,CAS Technical Institute of Physics and Chemistry | Zhou S.-X.,CAS Technical Institute of Physics and Chemistry | Li Y.-M.,Yanshan University
RSC Advances | Year: 2013

Ni-promoted MoS2 microspheres consisting of nanosheets have been prepared via a facile one-pot hydrothermal synthesis for the first time. The electrochemical hydrogen evolution reaction (HER) results demonstrated that the Ni-promoted MoS2 catalysts showed superior catalytic activity in the HER compared to pure MoS2 catalysts. This journal is © The Royal Society of Chemistry 2013.

Huang R.,CAS Technical Institute of Physics and Chemistry | Liu Y.,Yanshan University | Fan W.,CAS Technical Institute of Physics and Chemistry | Tan J.,CAS Technical Institute of Physics and Chemistry | And 3 more authors.
Journal of the American Chemical Society | Year: 2013

La(Fe, Si)13-based compounds are well-known magnetocaloric materials, which show a pronounced negative thermal expansion (NTE) around the Curie temperature but have not been considered as NTE materials for industrial applications. The NaZn13-type LaFe13-xSix and LaFe11.5-xCoxSi1.5 compounds were synthesized, and their linear NTE properties were investigated. By optimizing the chemical composition, the sharp volume change in La(Fe, Si)13-based compounds was successfully modified into continuous expansion. By increasing the amount of Co dopant in LaFe11.5-xCoxSi1.5, the NTE shifts toward a higher temperature region, and also the NTE operation- temperature window becomes broader. Typically, the linear NTE coefficient identified in the LaFe10.5Co1.0Si1.5 compound reaches as much as -26.1 × 10-6 K-1, with an operation-temperature window of 110 K from 240 to 350 K, which includes room temperature. Such control of the specific composition and the NTE properties of La(Fe, Si)13-based compounds suggests their potential application as NTE materials. © 2013 American Chemical Society.

Zhang W.,Hebei Normal University of Science and Technology | Ma Y.,Yanshan University | Yang G.,Yanshan University
Advances in Information Sciences and Service Sciences | Year: 2012

Based on the principle that the selection of delay time and embedding dimension has no correlation in the process of phase space reconstruction, this paper puts forward a new method of identifying the embedding dimension by Cao Liangyue Theory (CAO Theory) after the delay time is identified by Mutual Information Function. By means of the numerical verification of a few typical examples of chaotic dynamic system, the result shows that the method can identify the valid delay time of phase space reconstruction and the best embedding dimension. In addition, a new way of identifying the chaotic signal is provided and this method can effectively reconstruct the phase space of the original system from the time series.

Jia Q.,Yanshan University | Yang X.,Yanshan University | Song Z.,Jilong Electro mechanics
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2014

To exactly obtain the harmonic parameter in case of asynchronous sampling, and avoid the big error of phase estimation in the nonlinear interpolation, this paper proposed a novel window frequency shift algorithm to precisely estimate the harmonic parameters of power system. Using the derived frequency shift formula, the window signal could move the amount of frequency shift in the frequency domain. Then the measured frequency point was overlapped with its practical position. The harmonic parameters could be obtained through the shift signal spectrum correspondingly. The advantage of the novel algorithm is to realize the application of frequency shift in harmonic analysis, based on window signal shift in frequency domain. The asynchronous sampling problem was synchronized through moving the window signal to eliminate the asynchronous sampling error. At the same time, the algorithm avoided the correction process which exists in the interpolation algorithm. Moreover, estimations of amplitude, phase and frequency have more simple calculation formulas in the algorithm. The example results verify the correctness of the presented algorithm, and exhibit higher estimating precision, especially phase precision, compared with the window interpolation algorithm in case of noise jamming. © 2014 Chin. Soc. for Elec. Eng.

Tang Y.,Yanshan University | Tang Y.,National Engineering Research Center for Equipment | Zhang X.,Yanshan University | Hua C.,Yanshan University | And 2 more authors.
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2012

Chaos can be observed in fractional-order nonlinear systems with appropriate orders. The knowledge about the parameters and orders are the basis of the control and synchronization of fractional-order chaotic systems. In this Letter, the problem of parameter identification of commensurate fractional-order chaotic systems is investigated. By treating the orders as additional parameters, the parameters and orders are identified together through minimizing an objective function. Differential evolution algorithm, a powerful and robust evolutionary algorithm, is applied to search the optimal solution of the objective function. Numerical simulations and comparisons with genetic algorithm (GA) demonstrate the effectiveness of the proposed method. Crown Copyright © 2011 Published by Elsevier B.V. All rights reserved.

Zhang Z.W.,Yanshan University | Zhang Z.W.,Hebei Normal University of Science and Technology | Ma D.Q.,Yanshan University | Yue Y.,Yanshan University | And 2 more authors.
Journal of Alloys and Compounds | Year: 2015

A novel high-efficiency near-UV light-emitting diode (LED)-based color-conversion phosphor, red-emitting LaBMoO6:Eu3+, was synthesized by solid-state reaction for the first time, and its photoluminescence (PL) properties were investigated for application in white-light-emitting diodes (W-LEDs). The as-synthesized phosphors were characterized by X-ray powder diffraction, photoluminescence excitation (PLE), and PL emission spectra. The PLE and PL emission spectra revealed that when x ≤ 0.05, all the charge-transfer states centered at 350 nm, and LaBMoO6:Eu3+ phosphor emitted bright red light under 350 nm excitation. The CIE (Commission Internationale de l'Eclairage) chromaticity coordinates for LaBMoO6:Eu3+ red phosphor were simulated and located in the red region. All the results indicate that the developed LaBMoO6:Eu3+ phosphor could be potentially used as W-LEDs. © 2015 Elsevier B.V. All rights reserved.

Zhang X.,Yanshan University | Liu H.,University of Portsmouth | Li X.,Yanshan University
Robotics and Autonomous Systems | Year: 2010

This study proposes a novel method for target tracking based on the combination of object matching and background anti-matching which take account of both the global property of covariance matching and local property of mean shift tracking synthetically. In the background anti-matching phrase, a certain number of background regions are extracted based on the feature of color orientation codes via an entropy filter, and the covariance matrix is adapted to match these regions to get the global motion of the background; further, the object matching is carried out by a mean-shift tracking algorithm. The proposed method is evaluated in various datasets in comparison with their counterpart algorithms; experimental results sufficiently demonstrate the effectiveness of the method proposed in this study. © 2010 Elsevier B.V. All rights reserved.

Rong Y.,Yanshan University | Rong Y.,Hebei Normal University of Science and Technology | Jin Z.-L.,Yanshan University
Guangxue Jingmi Gongcheng/Optics and Precision Engineering | Year: 2012

A 3-DOF mechanical leg with compact structure, strong carrying capacity and the rotational motion in decoupled was proposed. To analyze the drive parameters of the 3-DOF parallel mechanical leg, a dynamic model was established and the peak of a servo motor was predicted based on the dynamic model. Firstly, by analyzing the motion parameters of the leg mechanism, the dynamic model was established based on the Lagrange equation, and the drive force acted on the mechanism was given. Then, based on the dynamic model, a peak prediction model of the servo motor for the drive speed and torque was defined. Finally, for a given motion equation and a set of structural parameters, the time curves of drive speed and torque were obtained, the dynamics of the mechanism was given and the peak prediction model was proved to be correct. Calculations show that the peaks of the drive speeds from three driving motors are 19, 17, 27 r/s for N x, N y and N w, and the peaks of the drive torque are 5.8, 3.1, 4.4 N·m for ε x, ε y and ε w respectively.

Rong Y.,Yanshan University | Rong Y.,Hebei Normal University of Science and Technology | Jin Z.-L.,Yanshan University | Qu M.-K.,Hebei Normal University of Science and Technology
Guangxue Jingmi Gongcheng/Optics and Precision Engineering | Year: 2012

A parallel mechanism was applied to the mechanical leg of a six-legged robot to expand the application areas of the six-legged robot. A new mechanical leg based on the (U+UPR)P+UPS parallel mechanism was proposed, and the structure parameters of the mechanical leg were designed. Firstly, the kinematics of leg mechanism was discussed, and the inverse position and velocity mapping equations were presented. Then, the workspace of the leg mechanism was discussed and a 3D map of the workspace was drawn. The performance evaluation index of workspace was defined and the relationship curve of the structure parameters and the evaluation index of workspace was given. Furthermore, the kinematics dexterity of the leg mechanism was analyzed, and the 3D map for condition numbers of Jacobian matrix was drawn. The performance evaluation index of kinematics dexterity was defined, and the relationship curve of the structure parameters and the index of kinematics dexterity were given. Finally, based on the indexes of workspace and kinematic dexterity, the structure parameters were analyzed by Monte Carlo method. A set of excellent structural parameters were proposed, and a 3-DOF mechanical leg was designed. These results lay the theoretical foundation for the further study of six-legged robots.

Guo X.,Yanshan University | Zhang H.,Yanshan University | Chang Z.,Aalto University
ICIC Express Letters | Year: 2010

Thresholding methods are widely used, in image segmentation because oftheir simplicity and efficiency. Most of the common thresholding methods have alot of dificulties when processing images which have unimodal histograms or lowgray level edge points. In this paper, we give a new membership function, a newfuzzy set distance definition, based on these definitions we propose a newthresholding algorithm. Experiment results in this paper show that the newalgorithm, is useful to threshold, unimodal images and, images with low graylevel edges. ICIC International © 2010.

Han H.-L.,CAS Changchun Institute of Applied Chemistry | Liu Y.,CAS Changchun Institute of Applied Chemistry | Liu Y.,Yanshan University | Liu J.-Y.,CAS Changchun Institute of Applied Chemistry | And 2 more authors.
Dalton Transactions | Year: 2013

A series of novel binuclear phenoxyimino organoaluminum complexes of the type [(RNCH)C6H3OAlMe2]2 [R = C 6H5 (2a), 2,6-iPr2C 6H3 (2b), 2,6-Ph2C6H3 (2c), adamantyl (2d), tBu (2e)] have been prepared in high yields, and these complexes were identified by 1H, 13C NMR and elemental analysis. Structural analysis for 2a-e revealed that these complexes have a distorted tetrahedral geometry around Al and both the Al-O and the Al-N bond distances were considerably influenced by substituents in the imino groups. The complexes were tested as catalyst precursors for ring-opening polymerisation (ROP) of ε-caprolactone (CL) in the presence of BnOH, and their catalytic activities were strongly affected by the catalyst structures and polymerisation conditions. An efficient living ROP has been achieved using the 2b/BnOH system. © 2013 The Royal Society of Chemistry.

Zhu J.-Z.,Yanshan University | Li W.-L.,CAS Changchun Institute of Optics and Fine Mechanics and Physics
Faguang Xuebao/Chinese Journal of Luminescence | Year: 2012

High efficiency white organic light-emitting diodes (WOLEDs) with high color rendering index (CRI) was fabricated. The white light was composed by the blue emission of 9, 10-di(2-naphthyl) anthracene and the enhanced green and red emissions of tris-(8-hydroxyquinolinato) aluminum and 4-(dicyanomethylene)-2-t-butyl-6- (1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran, respectively. The WOLED shows the Commission Internationale de l'Eclairage-1931 coordinates vary from (0.3432, 0.3397) to (0.3243, 0.3218), the correlated color temperature varies from 5035 K to 5915 K and all the CRIs exceed 90 when the driving voltage changes from 8 V to 12 V. A maximum brightness of 27853 cd/m 2 at 14 V and a peak current efficiency of 9.58 cd/A at 7.5 V are attained, respectively. The electroluminescent (EL) spectrum is tuned by changing the thickness of the green and red emission layers. The efficiency enhancement is realised by sensitising the green and red light emissions. The maximum efficiency is increased by 73.6% compared to the control device.

Wang Y.,Yanshan University | Yao T.,Yanshan University | Yao J.-L.,McMaster University | Zhang J.,Yanshan University | Gou H.,Yanshan University
Physical Chemistry Chemical Physics | Year: 2013

Rhenium nitride (ReN2) with the hexagonal MoS2 structure was recently synthesized by metathesis reaction under high pressure. Here the calculated elastic and thermodynamic stabilities and chemical bonding show that the MoS2 phase is unstable based on first-principles calculations. Meanwhile, the MoS2-type ReN2 compound may be stabilized by nitrogen-vacancies from X-ray diffraction and supercell calculations. Structure searches identify a monoclinic C2/m phase for ReN 2, which is energetically more stable than previous predictions and MoS2 structure over a wide range of pressures. Above 130 GPa, a tetragonal P4/mbm phase becomes favorable from enthalpy calculations. Both phases have superior mechanical properties, and their syntheses would have important applications fundamentally and technologically. © the Owner Societies 2013.

Li A.,Kyushu University | Li A.,Yanshan University | Uchimura T.,Kyushu University | Watanabe-Ezoe Y.,Kyushu University | Imasaka T.,Kyushu University
Analytical Chemistry | Year: 2011

Dioxins in a soil sample were measured using gas chromatography/resonance- enhanced multiphoton ionization/time-of-flight mass spectrometry coupled with different types of laser sources. The fourth-harmonic emission (266 nm) of a nanosecond Nd:YAG laser (1 ns) provided low ionization efficiency, especially for highly chlorinated dioxins/dibenzofurans (CDDs/CDFs). The ionization efficiency was improved using the fourth-harmonic emission (266 nm) of a picosecond Nd:YAG laser (4 ps), due to shorter singlet excited-state lifetimes. It was, however, difficult to efficiently ionize hepta-CDD and octa-CDD/CDF, because of their shorter lifetimes, which were induced by stronger spin-orbit coupling that led to efficient relaxation of the excited molecule to triplet levels. The ionization efficiency was substantially improved using the fifth-harmonic emission (213 nm) of the picosecond Nd:YAG laser (4 ps), in which the analyte molecule that was relaxed to triplet levels was efficiently ionized using a photon with sufficient energy for ionization, although the pulse energy obtained at 213 nm was only one-third of the pulse energy obtained at 266 nm. The limits of detection achieved for 17 toxic polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDDs/PCDFs) were 0.41-45 pg. The analytical instrument developed in the present study performed sufficiently well for the practical trace analysis of dioxins in soil samples. © 2010 American Chemical Society.

Chen Z.X.,Kyushu University | Qian L.H.,Yanshan University | Zhu S.J.,Fukuoka Institute of Technology
Engineering Fracture Mechanics | Year: 2010

Ceramic thermal barrier coatings (TBCs) are increasingly applied to enhance the performance of advanced gas turbine engines. However, the delamination cracks initiated in these coatings limit their applications. In this research, a sandwiched four-point bend specimen is used to evaluate the crack growth resistance in plasma-sprayed TBCs. Well controlled, stable and measurable crack extension is obtained. A rising crack growth resistance curve is found. The steady state strain energy release rate is obtained to be about 170J/m2. The delamination crack evolution behavior is in situ observed and simulated by the finite element analysis based on a crack bridging model. © 2010 Elsevier Ltd.

Yuan X.,Yanshan University | Ashayeri J.,University of Tilburg
International Journal of Modelling, Identification and Control | Year: 2013

During the last 45 years, system dynamics as a continuous type of simulation has been used for simulating various problems, ranging from economic to engineering and managerial when limited (historical) information is available. Control theory is another alternative for continuous simulation that also includes the modelling of differential equations, but mostly employed in engineering. Based on the system dynamics simulation model of Sterman's high-tech growth firms, this paper studies the application of control theory simulation in design of a high-tech supply chain system and compares the results with those of system dynamics-based simulation. It is shown how easily supply chain processes can be translated into a control theory model using the differential equation approach in the place of Laplace transform. In addition, some improvements are also made on Sterman's model. Copyright © 2013 Inderscience Enterprises Ltd.

Jiang W.,Yanshan University | Wu S.,Yanshan University | Wu S.,Xingtai Vocational and Technical College
Yi Qi Yi Biao Xue Bao/Chinese Journal of Scientific Instrument | Year: 2010

Aiming at the difficulty that evidence theory can hardly determine basic probability assignment (BPA) and SVM can hardly obtain probability output, a new multi-data fusion fault diagnosis method is proposed, which is based on SVM and D-S evidence theory. In the method, BPA is assigned based on one-versus-one multi-class SVM; a fusion arithmetic based on matrix analysis is presented to solve the calculation bottleneck problem of evidence theory. The method is tested on a hydraulic pump; at first, the fault signals of slipper looseness and wearing between cylinder body and valve plate are collected; the measured signals are preprocessed using wavelet cluster; 12 fault features are picked up in time domain and frequency domain; at last, the fault is diagnosed using the proposed new method. Experiment results show that the new method features high correct diagnosis rate and is effective in fault diagnosis.

Gou H.,Rensselaer Polytechnic Institute | Gou H.,Yanshan University | Li Z.,Yanshan University | Niu H.,Rensselaer Polytechnic Institute | And 4 more authors.
Applied Physics Letters | Year: 2012

By means of first-principles calculations, we report superior rigidity, ideal tensile, and shear strength for orthorhombic CrB 4 and MnB 4. The analysis of microscopic deformation mechanism reveals that the unique rectangular boron units in CrB 4 and MnB 4 are responsible for the consolidation of the directionality of boron-boron covalent bonds and the exceptional rigidity and ideal strength. The unusual mechanical properties of the orthorhombic tetraborides highlight their potential applications as intrinsically superhard materials. The unique rectangular boron unit also implies a criterion for designing and synthesizing transition metal boride based-materials with ultimate hardness and strength. © 2012 American Institute of Physics.

Wu X.,Yanshan University | Li Y.,Yanshan University | Zhang J.,Hebei University of Science and Technology | Zhu Q.,University of the West of England
International Journal of Modelling, Identification and Control | Year: 2014

This study presents a generalised procedure for designing sliding mode control of neutral systems with uncertain parameters. Based on the new sliding surface, a sliding mode controller is designed, by means of linear matrix inequality technique to deal with the unknown parameters in the neutral systems. The bounds of the unknown parameters should be known in advance. The Lyapunov stability theory is referred to prove that the neutral system is converged to zero equilibrium. An example is simulated to demonstrate the effectiveness and efficiency of the procedure. Copyright © 2014 Inderscience Enterprises Ltd.

Yang X.,Taiyuan University of Science and Technology | Xiao H.,Yanshan University | Chen Z.,Chongqing University
Yingyong Lixue Xuebao/Chinese Journal of Applied Mechanics | Year: 2014

Due to the strong non-linearity of roll bearing contact problem, the Boundary Element Method (BEM) is used to study the roll bearing contact problem. Bearing boundary elements are used to simulated the bearing contact elements, and the Hertz contact theory is used to revise the contact widths of rollers with inner race and outer race in the bearing BEM. According to the assemble and fit characteristics of mill conical roller bearings, both loose fits are adopted to the inner race with the roll and the outer race with the block, the program of bearing BEM for the four-bodies elastic contact with friction is compiled, with which a mill four-row conical roller bearing is simulated. According to the results, the small ends of the conical rollers bear the larger pressure and the pressure on the ends is lager by far than the pressure on the middle. The direction of axial pressure on the rollers is consistent with the conicity of the rollers and the maximum pressure occurs in the mill roll side on the first-row rollers. The distribution law of the contact widths of the rollers is consistent with the radial load on the rollers and the radial pressure distribution on non-bearing contact area corresponds to the location of the rollers bearing load. The numerical example illustrates the viability and accuracy of the algorithm .

Lu Z.,Yanshan University | Cheng H.,Yanshan University | Feng L.,Xingtai Polytechnic College
Diangong Jishu Xuebao/Transactions of China Electrotechnical Society | Year: 2013

The traditional load flow calculation, which has a strict requirement for power type, needs the injection active power of all nodes except the balance node, and the injection reactive power of all PQ nodes. The strict requirement often leads to the load flow calculation failure due to the lack of injection power. This paper presents extended-power load flow which makes use of branch power as substitutes for the missing injection power. The modified equation of the new method are deduced. The coefficient matrix method is also proposed to select the alternative branch power and the criterion to judge whether the power flow calculation has solutions is built. The algorithm process is given and simulation is done on IEEE 14 and IEEE-118 system. The results show that the existed problem can be solved based on the extended-power load flow and the coefficient matrix.

Chen Z.,Chongqing University | Xiao H.,Yanshan University
Computational Mechanics | Year: 2012

Fast multipole boundary element methods (FMBEMs) are developed based on the couple of fast multipole algorithm and generalized minimal residual algorithm. The FMBEMs improve the efficiency of conventional BEMs, accelerate the computing, enlarge the solving scale, and it is applied in various engineering fields. The paper tried to do a brief reviewfor the FMBEMs, and focus on the description of basic principles and applications in rolling engineering. The basic principles and main frameworks of two typical methods of FMBEMs (sphere harmonic function multipole BEM and Taylor series multipole BEM) are briefly described, and then the key numerical iterative and preconditioning techniques suitable for the FMBEMs are introduced. The typical numerical examples are presented, including the elasticity problems, the elastic contact problems and the elastoplasticity problems, etc. The validity and effectiveness of FMBEMs are effectively illustrated by engineering analysis examples. The numerical results suggest that the FMBEMs are suitable for the analysis and solution of large scale rolling engineering problems. The implementation process of numerical analysis can provide useful reference for the applications in other engineering fields.

Bian L.,Yanshan University | Bian L.,Dalhousie University | Taheri F.,Dalhousie University
Materials and Design | Year: 2011

In the present paper, the crack initiation and propagation in rectangular magnesium alloy plates containing an inclined through crack are investigated experimentally and theoretically. Based on the complex stress state at the crack tip, a maximum ratio criterion is developed to determine the crack propagation for a given inclination angle by means of an opening mode theory. It is assumed that the crack begins to propagate when the maximum value of ratio approaches its critical value, and the direction of crack propagation coincides with the direction of maximum ratio defined. The experiments for checking the theoretical predictions from the proposed criterion have been conducted. The material properties and fracture characteristics are evaluated during the tests. The results obtained are compared with those obtained using the commonly employed fracture criteria and the experimental data. © 2010 Elsevier Ltd.

Cheng Y.,Yanshan University | Bian L.,Yanshan University | Wang Y.,Yanshan University | Taheri F.,Dalhousie University
International Journal of Solids and Structures | Year: 2014

In the present study, an effective model is proposed to predict the effective elastic behavior of the three-phase composite containing spherical inclusions, each of which is surrounded by an interphase layer. The constitutive equations are derived for the stress and strain of each phase of the composite subjected to a far-field tension. Based on these constitutive laws, the effective bulk, shear and Young's modulus are obtained. A statistical debonding criterion is adopted to characterize the varying probability of the evolution of interphase debonding. Influences of debonding damage, particle volume fraction, interphase properties and bonding strength on overall mechanical behavior of composites are also discussed. Numerical analyses are carried out on particle-reinforced composites and the predictions have a good agreement with the experimental results. © 2014 Elsevier Ltd. All rights reserved.

Wei J.,Yanshan University | Chen Y.,Yanshan University | Li B.,Hebei Normal University | Yi M.,Yanshan University
CMES - Computer Modeling in Engineering and Sciences | Year: 2012

In this paper, we present a computational method for solving a class of space-time fractional convection-diffusion equations with variable coefficients which is based on the Haar wavelets operational matrix of fractional order differentiation. Haar wavelets method is used because its computation is sample as it converts the original problem into Sylvester equation. Error analysis is given that shows efficiency of the method. Finally, a numerical example shows the implementation and accuracy of the approach. Copyright © 2012 Tech Science Press.

Zhang J.,Hebei University of Science and Technology | Zhu Q.,University of the West of England | Wu X.,Hebei University of Science and Technology | Wu X.,Yanshan University | Li Y.,Yanshan University
Neurocomputing | Year: 2013

This study presents a generalized procedure for designing recurrent neural network enhanced control of time-varying-delayed nonlinear dynamic systems with non-affine triangle structure and pure-feedback prototype. Under the framework, recurrent neural network is developed to accommodate the on-line approximation, which the weights of the neural network are iteratively and adaptively updated through system state vector. Based on the neural network online approximation model, an indirect adaptive neural network controller is designed, by means of dynamic compensation, to deal with some of the challenging issues encountered in such complex nonlinear control systems. Taking consideration of the correctness, rigorousness, and generality of the new development, the Lyapunov stability theory is referred to prove that the closed-loop control system is uniformly ultimately bounded stable and the output of the system is converged to a small neighborhood of the desired trajectory. Two bench mark tests are simulated to demonstrate the effectiveness and efficiency of the procedure. In addition these could be the show cases for potential readers/users to digest and/or apply the procedure to their ad hoc problems. © 2013 Elsevier B.V.

Bian L.,Yanshan University | Bian L.,Dalhousie University
Journal of Constructional Steel Research | Year: 2014

In this study, the fatigue fracture of steel pipes, each consisting of an inclined semi-elliptical crack, subjected to axial loading is investigated both experimentally and theoretically. The inclined angle of the crack with respect to the axis of loading varies between 0° and 90°. On a microscopic scale, in fact, the fracture surface is not smooth indeed, as asperities, which are related to microstructure details, are developed. The mutual sliding interactions of these asperities result in a pressure and a frictional stress field between the fracture surfaces. In the present investigation, a new crack growth model, which accounts for the fracture surface interaction effects on the crack growth, is proposed. The fracture surface is considered in a form of a factory roof, with asperity height of h and wavelength of λ. Subsequently, this proposed model is applied to predict fatigue crack growth in steel pipes under complex stress states. © 2014 Elsevier Ltd.

Wan S.,Huangshan University | Ma Z.,Huangshan University | Xue Y.,Huangshan University | Ma M.,Huangshan University | And 3 more authors.
Industrial and Engineering Chemistry Research | Year: 2014

In the present study, the sorption ability of three metal ions, lead, cadmium, copper, from aqueous solution by tea waste was investigated. Sorption of the evaluated toxic metals by tea waste was pH-dependent, and kinetic data for three metal ions not only indicated a quick sorption process but also were excellently represented by the pseudo-second-order model with all correlation coefficients R2 > 0.97. In addition, the sorption processes of three metal ions by tea waste in different temperatures could be described satisfactorily by both Langmuir and Freundlich isotherms. According to calculated results by the Langmuir equation, the maximum removal capacities of Pb(II), Cd(II), and Cu(II) were 33.49, 16.87, and 21.02 mg/g, respectively. Fourier transform infrared (FT-IR) analysis of the tea waste samples laden with different metals indicated that multiple functional groups were involved in the sorption of metal ions, and the carboxyl group (Cî - O) and bonded-OH group were primary binding sites in lead and cadmium removal, while the -CN stretching and the carboxyl group were primary binding sites in copper removal. All the results reported strongly implied the potential of tea waste as an economic and excellent bioadsorbent for removal of metal ions from contaminated waters. © 2014 American Chemical Society.

Wu X.,Yanshan University | Wu X.,Hebei University of Science and Technology | Luo X.,Yanshan University | Zhu Q.,University of the West of England | Guan X.,Yanshan University
Neurocomputing | Year: 2012

This paper presents tracking control problem of the unmatched uncertain nonlinearly parameterized systems (NLP-systems) with unknown input nonlinearities. Two kinds of nonlinearities existing in the control input are discussed, which are non-symmetric dead-zone input and continuous nonlinearly input. The smooth controller is proposed in either of these two cases by effectively integrating adaptive backstepping technique and neural networks. Some assumptions, in which the parameters with respect to the input nonlinearities are available in advance in previous works, are removed by adaptive strategy. The researches also take the arbitrary unmatched uncertainties and nonlinear parameterization into account without imposing any condition on the system. It is shown that the closed-loop tracking error converges to a small neighborhood of zero. Finally, numerical examples are initially bench tested to show the effectiveness of the proposed results. © 2011 Elsevier B.V..

Si G.,Northeastern University China | Zhao Y.,Pennsylvania State University | Lv J.,Northeastern University China | Wang F.,Northeastern University China | And 3 more authors.
Nanoscale | Year: 2013

We report an improved method to directly and accurately fabricate plasmonic nanostructures with ultrasmall gaps. The fabrication is based on high-resolution focused ion beam milling with closely packed nanoring patterns. With fine and precise adjustment of the ion beam, elegant plasmonic nanostructures with ultrasmall dimensions down to 10 nm are achieved. We also show that the gap dimensions have a strong effect on the optical reflectance and transmittance of the plasmonic nanostructures. Measured results show reasonable agreement with finite-difference time-domain calculations. Our approach could find promising applications in plasmon-assisted sensing and surface-enhanced spectroscopy. This journal is © 2013 The Royal Society of Chemistry.

Liu Y.,CAS Changchun Institute of Applied Chemistry | Liu Y.,Yanshan University | Dong W.-S.,CAS Changchun Institute of Applied Chemistry | Liu J.-Y.,CAS Changchun Institute of Applied Chemistry | Li Y.-S.,CAS Changchun Institute of Applied Chemistry
Dalton Transactions | Year: 2014

A series of novel aluminium complexes containing cyclic β-ketiminato ligands of type Me2Al{O-[(ArNCHC4H4(C 6H4))]} (3a, Ar = 2,6-iPr2C 6H3; 3b, Ar = C6H5; 3c, Ar = C 6F5) have been prepared in high yields. These complexes were identified by 1H, 13C NMR spectroscopy and elemental analysis. X-ray structural analyses for 3a-c revealed that these complexes have a distorted tetrahedral geometry around Al, and both bond distances and bond angles were considerably influenced by the ligand structure. These complexes were tested as catalyst precursors for ring-opening polymerisation of ε-caprolactone (ε-CL) and l-lactide (l-LA) in the presence of 2-propanol as an initiator. Complex 3a could polymerize ε-CL in a controlled manner with high efficiency. Based on the living characteristics, the preparation of well-defined block copolymers PCL-b-PLLA via sequential addition of monomers was performed by 3a. Note that complex 3c exhibited rather high catalytic activity for the ROP of l-LA with narrow molecular weight distribution. The monomer conversion reached completion only in 4 h when the l-LA/Al molar ratio was 100 at 80 °C. PLLA-b-PCL copolymers were thus easily produced by 3c. © 2014 The Royal Society of Chemistry.

Xu J.,Yanshan University | Zhang R.,Yanshan University | Wu C.,Yanshan University | Zhao Y.,Yanshan University | And 2 more authors.
Carbon | Year: 2014

Graphitized carbide-derived-carbon (CDC) with hierarchical micro- and meso-pores is synthesized by chlorination of titanium carbide powder at 1000 °C. The produced CDC has many bilayer graphenes and some narrow graphite ribbons, which contributes a large amount of micropores (∼1.35 nm) and some mesopores. Although hierarchical pore is an attractive structure for supercapacitor, the low hydrophilicity of the graphitized CDC leads to poor electrochemical performance in alkaline electrolyte. The specific capacitance of the CDC in KOH aqueous electrolyte is only 5 F g-1. A strategy that adding ethanol to alkaline electrolyte is presented to improve its surface wettability. The specific capacitance of the graphitized CDC in KOH aqueous electrolyte with addition of ethanol increases to 60 F g-1 at a scan rate of 20 mV s-1. The optimal content of ethanol in KOH electrolyte is 10 wt.%. In addition, cyclic voltammogram curve can maintain a quasi-rectangular shape well even at a scan rate of 500 mV s-1 and the retention rate of the specific capacitance is about 70%. The specific capacitance is stable at high current density (e.g. 1 A g-1), and almost no performance degradation is observed after 8000 consecutive cycles. © 2014 Elsevier Ltd. All rights reserved.

Wang Z.-B.,Yanshan University | Wang Z.-G.,North China Electrical Power University
International Journal of Theoretical Physics | Year: 2016

In this article, we calculate the contributions of the condensates up to dimension-6, including the one-loop corrections to the quark condensates, in the operator product expansion in a consistent way, and study the masses and decay constants of the heavy pseudoscalar mesons with the thermal QCD sum rules. We reproduce the experimental values of the masses of the D, Ds, B and Bs and obtain the decay constants at zero temperature. Then we study the thermal behaviors of the masses and decay constants, which are useful in explaining the heavy-ion collision experiments. © 2016, Springer Science+Business Media New York.

Peng Q.,Yanshan University | Li X.,Yanshan University | Ma N.,Yanshan University | Liu R.,Yanshan University | Zhang H.,CAS Changchun Institute of Applied Chemistry
Journal of the Mechanical Behavior of Biomedical Materials | Year: 2012

Backward extrusion was used to improve the properties of Mg-based biomaterials. The microstructures, mechanical performance and corrosion properties of as-cast and backward extruded Mg- xZn (x= 0.5, 1, 1.5, 2, wt.%) alloys were investigated. The secondary dendrite arm spacing of as-cast Mg- xZn alloys and the grain size of backward extruded Mg- xZn alloys were decreased with the increment of Zn content. Meanwhile, both strength and elongation were improved by backward extruded treatment. With increasing Zn addition, the corrosion properties of both as-cast and backward extruded Mg- xZn alloys were decreased. However, the corrosion performance of backward extruded sample was improved obviously compared to the corresponding as-cast one. More importantly, the degradation rate of the backward extruded alloy was stable, which was mainly associated with the fine second precipitates and the homogeneous microstructure. It was demonstrated that backward extrusion was an effective approach to manufacture high performance Mg-based biomaterials. © 2012 Elsevier Ltd.

Wang Y.,Virginia Polytechnic Institute and State University | Gong J.,Virginia Polytechnic Institute and State University | Wang D.Y.,Virginia Polytechnic Institute and State University | Dong B.,Virginia Polytechnic Institute and State University | And 2 more authors.
IEEE Photonics Technology Letters | Year: 2011

We propose a serial time-division-multiplexing sensor network based on ultraweak fiber Bragg gratings (FBGs). Twelve ultraweak FBGs are distinguished with a spatial resolution of about 0.2 m, and their spectra are resolved with an accuracy of about 10 pm. The low crosstalk of the gratings makes it possible to multiplex over 1000 gratings along a single optical fiber. © 2006 IEEE.

Yan C.,Hebei University of Science and Technology | Li Y.,Yanshan University | Zhang J.,Hebei University of Science and Technology
International Journal of Modelling, Identification and Control | Year: 2014

This study develops a generalised procedure in adaptive neural network enhanced controller design for strict feedback non-linear time delay systems. Under the framework, recurrent neural network is tailored to accommodate the on-line identification, by which the weights of the neural network are iteratively and adaptively updated through the system state. Based on the neural network online approximation model, the state feedback adaptive controller is obtained by constructing a Lyapunov-Krasovskii function, which the integral type efficiently overcomes the controller singularity problem. To guarantee the correctness, rigorousness, and generality of the developed results, Lyapunov stability theory is used to prove the closed-loop control systems semiglobally, uniformly, and ultimately bounded stable. Two bench mark tests are simulated to demonstrate the effectiveness and efficiency of the procedure and furthermore these could be the showcases for potential users to apply to their demanded tasks. Copyright © 2014 Inderscience Enterprises Ltd.

Qin S.,Yanshan University | Liao B.,Yanshan University | Mao L.,Hebei University of Science and Technology | Xiao F.,Yanshan University
Materials Letters | Year: 2014

A novel method of mechanical alloying and heat treatment for preparing the nano-NbC particles mixed with Fe powder was proposed, and the nano-NbC particle reinforced steels were prepared. The results show that the mechanical alloying and heat treatment are an effective method for preparing the nano-NbC particles. The nano-NbC particles can uniformly distribute in steels. Furthermore, the as-casted microstructure is refined remarkably, and hardness of the steels increases. © 2014 Elsevier B.V.

Peng X.,Yanshan University | Xu C.,Yanshan University | Arasu K.T.,Wright State University
IEEE Transactions on Information Theory | Year: 2012

A pair of binary sequences is generalized from the concept of a two-level autocorrelation function of a single binary sequence. In this paper, new families of binary sequence pairs with period N=np, where gcd(n,p)=1, and optimal correlation values -1 are constructed, as well as new families of binary sequence pairs with three-level correlation and period N≡ 0(mod 4). For the new binary sequence pairs with optimal correlation values, their corresponding new difference set pairs and almost difference set pairs are also derived. © 2012 IEEE.

Hu J.,Yanshan University | Sun X.,Yanshan University | Xu J.,North China Electrical Power University | Li Z.,Yanshan University
Energy and Buildings | Year: 2013

This paper aims to investigate a simple-structure mechanical ventilation solar air collector (MV-SAC) with internal baffles. A numerical model is developed to predict its internal flow and heat transfer characteristics. And a sample experimental system is built and tested for validation of the numerical model. The investigation results indicate that the introduction of baffles can strengthen the convective heat transfer process and lessen the radiation heat loss, which contributes to efficiency improvement. But the presence of baffles causes strong flow separation which results in flow loss to some extent. The convective heat loss of the top cover plate is dominative in the total heat loss. The influence of baffle number, the thickness of air gap, the number of top glass cover and the operating conditions on the collector performance is also analyzed, and the results show that as for a specific scale collector, there exists an optimal baffle number, for this case the number is three. The operating parameters such as the surrounding temperature, solar radiation intensity have significant influence on the temperature rise but have little influence on collector efficiency, which indicates that this kind of solar air collector could be applied in a wide range of geographical latitude. © 2013 Elsevier Ltd. All rights reserved.

Xu J.,Yanshan University | Zhang R.,Yanshan University | Chen P.,Yanshan University | Ge S.,Pennsylvania State University
Journal of Power Sources | Year: 2014

Porous carbide-derived carbons (CDCs) are synthesized from TiC at different chlorination temperatures as electrode materials for electrochemical capacitors. It is found that the microstructure of the produced CDCs has significant influence on both the hydrophilicity in aqueous KOH electrolyte and the resultant electrochemical performance. Because the TiC-CDC synthesized at higher temperature (e.g. 1000 C) contains well-ordered graphite ribbons, it shows lower hydrophilicity and specific capacitance. It is also found that addition of a small amount of ethanol to KOH electrolyte effectively improves the wettability of the CDCs synthesized at higher temperature and the corresponding specific capacitance. Compared with the CDC synthesized at 600 C, the CDC synthesized at 1000 C shows fast ion transport and excellent capacitive behavior in KOH electrolyte with addition of ethanol because of the existences of mesopores and high specific surface area. © 2013 Elsevier B.V. All rights reserved.

Chen G.,Academy of Military Medical science | You G.,Academy of Military Medical science | Wang Y.,Academy of Military Medical science | Lu M.,Academy of Military Medical science | And 4 more authors.
Critical Care | Year: 2013

Introduction: This study compared the effects of hydroxyethyl starch 130/0.4, hydroxyethyl starch 200/0.5, and succinylated gelatin on oxidative stress and the inflammatory response in a rodent hemorrhagic shock model.Methods: Sodium pentobarbital-anesthetized adult male Wistar rats (200 g to 220 g) were subjected to a severe volume-controlled hemorrhage using arterial blood withdrawal (30 mL/kg to 33 mL/kg) and resuscitated with a colloid solution at the same volume as blood withdrawal (hydroxyethyl starch 130/0.4, hydroxyethyl starch 200/0.5, or succinylated gelatin). Arterial blood gas parameters were monitored. Malondialdehyde (MDA) content and myeloperoxidase (MPO) activity in the liver, lungs, intestine, and brain were measured two hours after resuscitation. The levels of tumor necrosis factor-alpha (TNF-α) and interleukin-6 in the intestine were also measured.Results: Infusions of hydroxyethyl starch 130/0.4, but not hydroxyethyl starch 200/0.5 or succinylated gelatin, significantly reduced MDA levels and MPO activity in the liver, intestine, lungs and brain, and it also inhibited the production of TNF-α in the intestine two hours after resuscitation. However, no significant difference between hydroxyethyl starch 200/0.5 and succinylated gelatin was observed.Conclusions: Hydroxyethyl starch 130/0.4, but not hydroxyethyl starch 200/0.5 or succinylated gelatin, treatment after hemorrhagic shock ameliorated oxidative stress and the inflammatory response in this rat model. No significant differences were observed after hydroxyethyl starch 200/0.5 or succinylated gelatin administration at doses of approximately 33 mL/kg. © 2013 Chen et al.; licensee BioMed Central Ltd.

Zhou Y.F.,Yanshan University | Yang Y.L.,Yanshan University | Jiang Y.W.,Yanshan University | Yang J.,Yanshan University | And 2 more authors.
Materials Characterization | Year: 2012

The microstructure and carbide refinement mechanisms of Fe-24 wt.%Cr-4.1 wt.%C hardfacing alloys with 0 wt.%, 0.5 wt.%, 1.0 wt.%, 2 wt.%, and 4 wt.% ceria additives have been systematically investigated in this work. Optical microscopy, field emission scanning electron microscopy with energy dispersive spectrometer, and X-ray diffraction were collectively used to study the microstructure, the phase components, and the chemical formation of inclusion formed in the welding process. Wear-resistance of the alloys was comparatively studied using an abrasive wear testing machine. The structure analysis results show that the Fe-Cr-C hardfacing alloy mainly consists of martensite, retained austenite, MC carbide and M 7C 3 carbide. With increasing ceria additive contents, the average size of the primary M 7C 3 carbide decreases and reaches a most refined state in the alloy with 2 wt.% ceria additives. Comparative wear tests data shows that the wear resistance of the hardfacing alloys with ceria additives is better than that without ceria additive. In a good agreement with the carbide refinement results, the wear resistance of the alloy reaches an optimum level in the sample with 2 wt.% ceria additive. The main RE inclusion type identified with in-situ XRD analysis is RE inclusion Ce 2O 2S. Thermodynamics calculation confirms that this type of RE inclusion could precipitate prior to M 7C 3 carbides, and act as a heterogeneous nucleus for M 7C 3 in the welding process, which effectively provides a mechanism for significant refinement of the M 7C 3 carbide and improves its wear resistance. © 2012 Elsevier Inc.

Chen M.,Qingdao Agricultural University | Zhao D.,Yanshan University
Mechanical Systems and Signal Processing | Year: 2016

Considering the disadvantage of higher throttling loss for the open-circuit hydrostatic transmission at present, a novel gravitational potential energy regeneration system (GPERS) of the boom of hydraulic excavator, namely the closed-circuit GPERS, is proposed in this paper. The closed-circuit GPERS is based on a closed-circuit hydrostatic transmission and adopts a hydraulic accumulator as main energy storage element fabricated in novel configuration to recover the entire gravitational potential energy of the boom of hydraulic excavator. The matching parameter and control system design are carried out for the proposed system, and the system is modeled based on its physical attributes. Simulation and experiments are performed to validate the employed mathematical models, and then, the velocity and the pressure performance of system are analyzed. It is observed that the closed-circuit GPERS shows better velocity control of the boom and response characteristics. After that, the average working efficiency of the closed-circuit GPERS of boom is estimated under different load conditions. The results indicate that the proposed system is highly effective and that the average working efficiency in different load conditions varied from 60% to 68.2% for the experiment platform. © 2016 Elsevier Ltd.

Chang J.,CAS Changchun Institute of Applied Chemistry | Chang J.,Yanshan University | Sun X.,CAS Changchun Institute of Applied Chemistry | Feng L.,CAS Changchun Institute of Applied Chemistry | And 3 more authors.
Journal of Power Sources | Year: 2013

Nitrogen-doped acetylene carbon black (N-C) is prepared by annealing acetylene carbon black and melamine under the protection of N2 at different temperatures. The resultant N-C materials are used as the support of Pd catalyst (Pd/N-C) for formic acid electrooxidation (FAEO). The catalytic activity of the Pd/N-C catalyst towards FAEO is evaluated by cyclic voltammetry, COad stripping voltammetry and chronoamperometry. The results show that when the heat-treatment temperature of support is 900 C, the corresponding catalyst, Pd/N-C-900, generate 2.84-fold and 0.96-fold higher activity than homemade and commercial Pd/C catalysts in 0.5 M H2SO4 and 0.5 M HCOOH solution. The COad stripping voltammetry results demonstrate that Pd/N-C-900 has much better resistance to CO poisoning. Moreover, the effect of formic acid concentration and the temperature on the Pd/N-C catalysts are also explored, which confirms the really enhanced performances for FAEO. It is founded that the doping of nitrogen results an increase in the performance for FAEO due to the improved Pd nanoparticles (Pd NPs) dispersion and the modified electronic effect. The results indicate that the Pd/N-C catalyst has great application prospect as a high-performance anode catalyst for direct formic acid fuel cells (DFAFCs). © 2013 Elsevier B.V. All rights reserved.

Wu X.-J.,Yanshan University | Wu X.-L.,Hebei University of Science and Technology | Luo X.-Y.,Yanshan University | Guan X.-P.,Yanshan University
IET Control Theory and Applications | Year: 2012

The problem of tracking control for a class of uncertain time-delay non-linear system with state constraint is addressed. To prevent constraint violation, the tangent barrier Lyapunov function (TBLF) is firstly used for time-delay non-linear system. By ensuring boundedness of the TBLF in the closed loop, besides those limits are not transgressed, the authors also tackle scenarios wherein parametric uncertainties and time delays are presented. Asymptotically tracking stable in the sense of uniformly ultimate boundedness is achieved without violation of the constraint. Finally, the performance of the proposed control has been illustrated through a chaotic system. © 2012 The Institution of Engineering and Technology.

Xu J.,Yanshan University | Zhang R.,Yanshan University | Chen P.,Yanshan University | Shen D.,Yanshan University | And 2 more authors.
Carbon | Year: 2013

Porous carbide-derived carbons (CDCs) are synthesized from different carbide (VC, TiC, NbC) as electrode materials for electrochemical capacitors. The process of carbide-carbon transformation is investigated by observations at different carbide/CDC interfaces. It is found that the restructuring process has much influence on formation of microstructure as well as the resultant electrochemical performance. The carbon structure in the produced CDC is well in accordance with that formed at the carbide/CDC interface, indicating that the microstructure in the produced CDC is decided by re-bonding of the residual carbon atoms. It is further found that the internal stress during carbide-carbon transformation has much influence on the CDC microstructure. In addition, the microstructure in CDCs is dependent on the volumetric concentration of carbon atoms in carbide precursor. Lower volumetric concentration of carbon atoms facilitates the formation of CDC with short and curved graphene structure, which owns easily accessible pores and large specific surface area, and thus high electrochemical performance for ultracapacitor. A novel strategy that controlling microstructure of CDC through controlling the volumetric concentration of carbon atoms in carbide precursor is presented. This strategy is very effective to form designed microstructure of CDC for electrochemical applications. © 2013 Elsevier Ltd. All rights reserved.

Xu J.,Yanshan University | Zhang R.,Yanshan University | Wang J.,Yanshan University | Ge S.,Pennsylvania State University | And 3 more authors.
Carbon | Year: 2013

A microstructure control strategy for carbide-derived carbon (CDC) by ball-milling the metal carbide precursor prior to CDC synthesis is investigated. This work explores the effect of chlorination temperature and ball-milling time on the microstructure, specific surface area (SSA) and the pore size distribution. It is found that the degree of order of CDC obtained from the milled titanium carbide (TiC) is obviously high and can be well tuned by controlling the ball-milling time at a lower chlorination temperature (400-800 °C). As the chlorination temperature rises to 1000 °C, an obvious decrease in the degree of order is observed and many cubic diamond-like carbon nanoparticles with larger d-spacing are formed. In addition, the produced CDC has a high SSA with both micro- and meso-pores. The effect of ball-milling TiC precursor on the microstructure of CDC can be attributed to the iron (Fe) in the TiC from the milling balls and jar to a great extent. The Fe promotes the formation of the better-organised carbon at lower chlorination temperature and the formation of the nano-diamond at higher temperature. © 2012 Elsevier Ltd. All rights reserved.

Chen Z.-Y.,Yanshan University | Wang B.-P.,Northwestern University
Jisuanji Xuebao/Chinese Journal of Computers | Year: 2011

A method of image segmentation based on 3-D histogram and restrain fuzzy kohonen clustering network (RFKCN) is proposed. The method includes two steps. The first step is the fuzzy pixels process in which two redundant images are built by fuzzy mean value and fuzzy median value. The second step is the processing of image segmentation by RFKCN clustering network with original image and their redundant images. The new method not only uses gray distribution information of pixels, but also uses relevant information and fuzzy information of neighboring pixels, to construct 3-dimension observation space. Based on the competition, redundancy, complementation and fuzzy character of all information, this algorithm improves the accuracy of clustering through efficient fusion. The theoretical analysis and experimental results show that the new algorithm obtains better performance in image segmentation.

Zhang J.,Yanshan University | Wang Y.,Yanshan University | Zang J.,Yanshan University | Zang J.,University of Science and Technology Beijing | And 3 more authors.
Carbon | Year: 2012