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North China Electric Power University is a university based in Beijing, People's Republic of China under the national Ministry of Education that specializes in polytechnic disciplines. Wikipedia.


Chen Z.,North China Electrical Power University
International Review on Computers and Software | Year: 2012

LDPC code-aided frame synchronization algorithms based on Maximum-Likelihood rule are studied. For soft information vectors with different frame offsets, the likelihood ratio value presenting the probability ratio of satisfaction of all check restrictions and dissatisfaction of all check restrictions are computed respectively, and then the point corresponding to the maximum value or larger than a threshold is chosen as the final frame synchronization bounder. Both frame synchronization error ratios of new algorithms are derived. New frame synchronization algorithms can be implemented by parts of LDPC decoder resource. Compared to other code-aided frame synchronization algorithms, simulation results show favorable performance of new code-aided frame synchronization algorithms based on soft information. © 2012 Praise Worthy Prize S.r.l. Source


Qiu Y.,North China Electrical Power University
International Review on Computers and Software | Year: 2012

The ever increasing demand of multimedia applications such as video conferencing, distributed data processing and HDTV have raised tremendous challenges on the network design, both in bandwidth and service. Wavelength-division-multiplexing (WDM) networks are the best choice as a backbone for the next generation optical networks. Supporting efficient multicast routing in WDM optical networks becomes an important challenge. This paper focus on the problem of multicast routing in WDM networks, and an algorithm employing the concept of light forest to construct multicast trees is proposed and is compared with existing optimal algorithms through simulations. The simulation results show that the proposed multicast routing scheme can achieve near optimal performance in terms of request blocking probability and average request delays between source and destination nodes. © 2012 Praise Worthy Prize S.r.l. - All rights reserved. Source


Li Y.,North China Electrical Power University
Hedongli Gongcheng/Nuclear Power Engineering | Year: 2010

For the nuclear power industry, due to characteristics of its own, its economy is quite different from that of the traditional fossil-fuel power. This paper studied the basic characteristics of the nuclear power economy and the status of economy of domestic nuclear power, and analyzed the main ways to improve the nuclear power economy. Source


Wang Z.-G.,North China Electrical Power University | Huang T.,CAS Institute of High Energy Physics
Nuclear Physics A | Year: 2014

In this article, we study the axial-vector mesons Zb(10610) and Zb(10650) with the Cγμ-Cγ5 type and Cγμ-Cγν type interpolating currents, respectively, by carrying out the operator product expansion to the vacuum condensates up to dimension 10. In calculations, we explore the energy scale dependence of the QCD spectral densities of the hidden bottom tetraquark states in detail for the first time, and suggest a formula μ=MX/Y/Z2-(2Mb)2 with the effective mass Mb=5.13 GeV to determine the energy scales. The numerical results favor assigning the Zb(10610) and Zb(10650) as the Cγμ-Cγ5 type and Cγμ-Cγν type hidden bottom tetraquark states, respectively. We obtain the mass of the JPC=1++ hidden bottom tetraquark state as a byproduct, which can be compared to the experimental data in the futures. Furthermore, we study the strong decays Zb±(10610)→ϒ{hooked}π±,ηbρ± with the three-point QCD sum rules, the decay widths also support assigning the Zb(10610) as the Cγμ-Cγ5 type hidden bottom tetraquark state. © 2014 Elsevier B.V. Source


Zhai M.-Y.,North China Electrical Power University
International Journal of Electrical Power and Energy Systems | Year: 2015

Load forecasting based on fractal interpolation is a very important method. However, traditional methods exists several disadvantages such as vertical scale factor difficult to calculate, low-precision, difficult to use. Therefore, a method is proposed combined with self-similarity theory and fractal interpolation theory to solve the above problems. In this paper, the self-similarity of electrical load historical data is analyzed using multi-resolution wavelet firstly, then use the Hurst parameter values to calculate vertical scaling factors in Iterative Function Systems (IFS) based on the values of Hurst parameter. The vertical scaling factors can be used to get the other parameters of IFS affine transformation. Then the electrical load forecasting curve was generated by the iterations system. According to the actual needs of electricity production, this algorithm was used to forecast electrical load from two aspects: fractal interpolation and fractal extrapolation, and the average relative errors are only 2.303% and 2.296%, in the case of only six interpolation points for the entire set of forecast data. The result shows this algorithm has advantages of high-precision, less-sample demands, less-interpolation points and easy to use. © 2015 Elsevier Ltd. All rights reserved. Source


Wang Z.-G.,North China Electrical Power University
European Physical Journal C | Year: 2016

In this article, we take the X(5568) to be the scalar diquark–antidiquark type tetraquark state, study the hadronic coupling constant gXBsπ with the three-point QCD sum rules by carrying out the operator product expansion up to the vacuum condensates of dimension-6 and including both the connected and the disconnected Feynman diagrams; then we calculate the partial decay width of the strong decay X(5568) → Bs 0π+ and obtain the value ΓX= (20.5 ± 8.1) MeV , which is consistent with the experimental data Γ X= (21.9 ± 6.4 -2.5 +5.0) MeV from the D0 collaboration. © 2016, The Author(s). Source


Qiu Y.,North China Electrical Power University
International Review on Computers and Software | Year: 2012

With the explosive growing of Internet traffic and emerging applications, such as video conferencing, multimedia delivery and Grid computing, long-haul transport networks must provide more bandwidth capacity and reliable delivery. Optical burst switching (OBS) is such a promising bufferless WDM switching technology. In order to offer better services for diverse Internet applications, the development of quality of service (QoS) mechanisms becomes an important issue in OBS networks. In this paper, a novel scheme for improving QoS in OBS networks is proposed and is compared with conventional scheduling algorithm in OBS through simulation. Simulation results show that the proposed scheme can guarantee QoS requirements in the OBS networks and can get a low burst blocking probability. © 2012 Praise Worthy Prize S.r.l. Source


Xu R.,North China Electrical Power University | Wang Y.,China Electric Power Research Institute
Dianwang Jishu/Power System Technology | Year: 2013

In allusion to precise judgment of security situation of electric power information network, a machine learning-based method for security situation awareness (SSA) is proposed and applied to actual environment. The proposed method abstracts the SSA as classification problem, and the records of actual field monitoring devices are taken as data source and input into classifier to attain awareness results. Based on ball vector machine a classifier is designed, and using quantum genetic algorithm the optimal training parameters of ball vector machine are searched to improve classification accuracy. Results of experiments based on KDD Cup 99 data set and actual operation of SSA system show that the proposed SSA system is better than traditional methods in the accuracy of situation awareness. Source


Mu G.,Northeast Dianli University | Cui Y.,North China Electrical Power University | Yan G.,Northeast Dianli University
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2011

As some wind energy enriched regions are away from load centers, especially in the North China, it is necessary to connect clustering wind farms into the main grid with high-voltage transmission lines. So the primary issue is to rationally determine transmission capacity of the transmission line. This paper presented a static optimization method for transmission capacity determination considering the low energy density characteristics of wind generation. In order to maximize the comprehensive benefits of the transmission project, the following factors have been taken into account such as the transmission benefit, transmission constructing costs as well as the congestion loss probably caused by a low transmission capacity. Example shows that the proposed method can achieve optimal transmission project benefit than the traditional one based on the total installed capacity. Meanwhile, the proposed method is an effective tool to determine transmission capacity for incorporating some 10 GW-class wind farms into main grid. © 2011 Chin. Soc. for Elec. Eng. Source


Guo P.,North China Electrical Power University
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2010

Large-scale variable pitch wind turbine generator usually uses the PID controller to maintain the output power unchanged above the rated wind speed. One set of PID parameters can hardly achieve satisfactory control performance because the range between rated wind speed and cut out wind speed is very large. This paper firstly analyzed the shortcomings of PID controller, then a new pitch control method combined with fuzzy feed forward and fuzzy PID controller was proposed. The fuzzy PID controller can produce a better control result than PID controller. With the analysis of the aerodynamic characteristics of the blade, the fuzzy feed forward controller can give different feed forward pitch angles according to wind speed at different wind speed range. The feed forward controller has achieved the dynamic feed forward compensation and improved the rapidness of control system. With the simulation of a 300 kW wind turbine generator at different wind speed, the new pitch control strategy can effectively reduce system's overshoot and regulation time, and has a satisfactory control performance. © 2010 Chin. Soc. for Elec. Eng. Source


Guo P.,North China Electrical Power University
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2010

Large-scale variable pitch wind turbine usually uses PID controller to maintain the output power unchanged above the rated wind speed. But with rotor's serious nonlinear aerodynamic characteristic, conventional single PID controller can hardly achieve idea control performance. With a deep analysis of rotor's aerodynamic characteristic, the numerical calculation and least square polynomial fit method were used to construct the nonlinear model between the pitch angle and wind speed. Then optimal selection method was used to linearize the model to several partitions according to wind speed. In each partition, one PID controller was designed. When wind speed changed, the outputs of multiple PID controllers switched according to the management strategy. The new control strategy takes rotor's dynamic characteristic into consideration and has the merits of simplicity and easy implement. Simulation of 300 kW wind turbine generator (WTG) proves that the new control strategy has good control performance. © 2010 Chinese Society for Electrical Engineering. Source


Ming-Yue Z.,North China Electrical Power University
International Journal of Communication Systems | Year: 2015

SUMMARY: Under some special environments in China, there exist moving radio radiations with high transmission powers that can degrade the performance of the power line communications systems significantly. Such radiations overlap with the OFDM-based signals in time and frequency domains, and hence, it is very difficult to mitigate directly if not possible. The paper introduced the fractional Fourier transform trying to deal with such moving radio interferences. When using the fractional Fourier transform to separate signals and noises/interferences, the fractional order plays a key role, but there is no method to obtain its optimal value in the published papers. In the paper, like for the time-frequency representations, we defined the second moments of the fractional Fourier transform of the signal. The fractional order, corresponding the maximum of the second moments, is the one used to separate the OFDM signals and the moving radio interferences, which is modelled as the Doppler signals in our scheme. The proposed method can mitigate the moving radio interferences significantly by applying the proposed method to the simulated OFDM signals and the measurements data. The results also show that the system's BERs can be improved from 10-2 to 10-5 for lower signal-noise-rate (SNR), and from 10-4 to 10-9 for high SNRs. © 2014 John Wiley & Sons, Ltd. Source


Wang Z.-L.,North China Electrical Power University
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2014

In view of the shortage of the fisher fishing algorithm easily falling into local optimum, a niche fisher fishing algorithm is proposed to improve the global optimization capability of basic fisher fishing algorithm, and applied to solve distribution network substation planning problem. This paper composes niche groups according to the distance between the various entities on the basis of the basic fisher fishing algorithm, and conducts the optimization by using fisher fishing algorithm in niche groups. For the updated groups, according to the distance between the individuals, the shared mechanism is used to change their fitness, and to improve the global search ability of the entire group. Through the calculation and analysis of the given test case, the results show a high convergence success rate and better solution of this algorithm for the substation locating and sizing issues. Source


Wang L.L.,North China Electrical Power University
Proceedings of the 5th IEEE International Conference on Electric Utility Deregulation, Restructuring and Power Technologies, DRPT 2015 | Year: 2015

The output characteristics of the photovoltaic cell are a nonlinear and easily affected by external environment. The maximum power point tracking (MPPT) control is an effective method to improve the conversion efficiency of the photovoltaic system. In order to solve the problems of conventional fuzzy control algorithm, a new control strategy based on T-S fuzzy reasoning is proposed. This algorithm can avoid the oscillation near the maximum power point and reduce the energy loss with good dynamic and static performance. The model of the photovoltaic system is established and simulated by Matlab/Simulink. The simulation results show the effectiveness of the proposed control algorithm. © 2015 IEEE. Source


Zhou Z.,North China Electrical Power University | Dong M.,Japan National Institute of Information and Communications Technology | Ota K.,Muroran Institute of Technology | Wu J.,Shanghai JiaoTong University | Sato T.,Waseda University
IEEE Wireless Communications Letters | Year: 2014

In this letter, we investigate the tradeoff between energy efficiency (EE) and spectral efficiency (SE) in device-to-device communications underlaying cellular networks with uplink channel reuse. The resource allocation problem is modeled as a noncooperative game, in which each user equipment is self-interested and wants to maximize its own EE. Given the SE requirement and maximum transmission power constraints, a distributed energy-efficient resource allocation algorithm is proposed by exploiting the properties of the nonlinear fractional programming. The relationships between the EE and SE tradeoff of the proposed algorithm and system parameters are analyzed and verified through computer simulations. © 2014 IEEE. Source


Wang Z.-G.,North China Electrical Power University
European Physical Journal C | Year: 2015

In this article, we calculate the contributions of the vacuum condensates up to dimension-6 including the (Formula presented.) corrections to the quark condensates in the operator product expansion, then we study the masses and decay constants of the pseudoscalar, scalar, vector, and axial-vector heavy-light mesons with the QCD sum rules in a systematic way. The masses of the observed mesons (Formula presented.) can be well reproduced, while the predictions for the masses of (Formula presented.) and (Formula presented.) can be confronted with the experimental data in the future. We obtain the decay constants of the pseudoscalar, scalar, vector, and axial-vector heavy-light mesons, which have many phenomenological applications in studying the semi-leptonic and leptonic decays of the heavy-light mesons. © 2015, The Author(s). Source


Yan-Kun L.,North China Electrical Power University
Analytical Methods | Year: 2012

Consensus modeling based on improved Boosting algorithm (Boosting-PLS, BPLS) combined with wavelength (variable) selection by MC-UVE (Monte Carlo-Uninformative Variable Elimination) method is applied to determination of cetane number (CN) of diesel. MC-UVE is firstly used to select characteristic variables from Near-infrared (NIR) spectra of diesel based on principles of MC simulation and UVE, and then the selected variables instead of the full spectra are used for BPLS modeling to predict results. From predicted results, the proposed MC-UVE-BPLS algorithm improves the performance of conventional linear PLS modeling in terms of accuracy and robustness, so it is more efficient and parsimonious with few numbers of useful variables when applied to the relationship between CN and diesel NIR spectra. Simultaneously, the prediction results of MC-UVE-BPLS compared with those of MC-UVE-PLS, BPLS and CPLS (Consensus modeling based on Bagging) show that MC-UVE-BPLS is superior to other models, and also verifies the efficiency of MC-UVE and improved BPLS. So the proposed MC-UVE-BPLS method provides a new approach for determination of diesel CN by NIR spectra. © 2012 The Royal Society of Chemistry. Source


Yang L.,North China Electrical Power University
Material Science and Environmental Engineering - Proceedings of the 3rd annual 2015 International Conference on Material Science and Environmental Engineering, ICMSEE 2015 | Year: 2016

This paper first analyzes the difficult position of Chinese PV enterprises and the existing problems in the process of development. It then puts forward the main ways for the business model innovation of photovoltaic enterprise by combining with the related theory of business model innovation that includes value innovation, value network innovation and profit model innovation. Finally, it brings forward the main countermeasures of photovoltaic enterprise business model innovation. © 2016 Taylor and Francis Group, London. Source


Zhang S.,North China Electrical Power University
Renewable and Sustainable Energy Reviews | Year: 2012

During 2010 and 2011, China had been the largest producer of wind turbines in the world for two consecutive years. How China can transform from being the largest producer to being the strongest producer of wind turbines is currently a great concern in the industry. The purpose of this paper is to discuss this issue from the perspective of the international competitiveness of China's wind turbine manufacturing industry. Firstly, the paper establishes a model for evaluating the international competitiveness of wind turbine manufacturing industry, which consists of five first-level indexes and 10 second-level indexes. Then, the paper uses these indexes to evaluate the international competitiveness of six leading wind turbine companies in the world - Vestas (Denmark), Gamesa (Germany), GE Wind (the USA), Nordex (Spain), Suzlon (India) and Sinovel (China). The result shows that the international competitiveness of the Chinese wind turbine company, Sinovel, ranked the fifth, lagging behind Vestas, Gamesa, GE Wind and Suzlon. Finally, the paper makes in-depth analysis on the major factors that hamper the international competitiveness of China's wind turbine manufacturing industry and provides implications for future development of the industry. © 2012 Elsevier Ltd. All right reserved. Source


Luo G.-L.,North China Electrical Power University | Zhang X.,Chinese Academy of Sciences
Renewable and Sustainable Energy Reviews | Year: 2012

There are still more than 30% of the Tibetan administrative villages without power, and about 40% farmers there are suffering from a serious shortage of firewood. Tibet is abundant in the deposits of hydropower, geothermal, and solar energy. The practical ways to solve the universal service of Tibetan rural energy are researched in the paper. We find that there are two main objectives of the universal access to energy in Tibetan rural areas. One is to meet the demand of electricity consumption and daily energy consumption of the farmers and herdsmen without power, initially solve energy poverty, realize the equitable access to energy, and ensure the early access to modern civilization. The other is to guarantee the provision of energy required in Tibet's rural economic development and urbanization. Their accomplishment depends on the responsibilities' definition and implementation in the universal service of energy by the central and local governments, and on the establishment of a universal service mechanism of energy. The conflict between the need of energy development in the agricultural and pastoral areas of Tibet and its insufficient financial resources cannot be solved without the support and assistance from the central government and other developed provinces in China. © 2012 Elsevier Ltd. All rights reserved. Source


Liu G.,Hunan University | Shi H.,Hunan University | Yang Y.,North China Electrical Power University
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2013

As power system is a non-analytical complex variable system, node voltages are not analytical complex-variable function of load current. In the plural domain, node voltages are not directly derivative of the load current, so there are still no papers using dynamic analytic method to study power system voltage stability. In this paper, the dynamic analytic method of non-analytical complex was derived; the comprehensive dynamic equivalent impedance of power system was defined; and the necessary condition when power system achieves limit transmission is that the comprehensive dynamic equivalence impedance mode is equal to load static equivalent impedance mode. By simulation and calculations, it proved that the necessary condition was right; load impedance modulus margin can accurately describe the system load node voltage stability level. Dynamic analytic method set a theoretical foundation to establish power system nonlinear equivalent model, and to apply nonlinear equivalent model to calculate limit power quickly and accurately. The maximum transmission power judgment criterion can be used to judge whether it is feasible to the solution of power flow equation for large-scale power system. © 2013 Chin. Soc. for Elec. Eng. Source


Liu G.,Hunan University | Yang Y.,North China Electrical Power University
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2013

Voltage stability and angle stability are only two extreme conditions of power system stability analysis. When Jacobian matrix is singular, it's not only critical point of voltage stability, but static critical point of angle stability. According to the general principle of extreme value analysis of nonlinear equations, the equivalence relation of static angle stability and voltage stability was proved. The decentralized dynamic equivalent method was proposed, by introducing current auxiliary variable and flow equations. The unified analysis method of dynamic voltage stability and angle stability was established by using the dynamic parameters in Jacobian matrix and the nonlinear dynamic analysis principle. Through the application of direction differential of complex current (voltage), the relationship between integrated dynamic equivalent impedance and load static equivalent impedance were studied and the comprehensive evaluation of voltage stability and static angle stability margin index were proposed. Impedance margin means the unitization of limit load power and the transformation of angle curve into power-impedance curve. The impedance margin is not only a sensitivity index, but has good nonlinear properties. Take the dynamic characteristics of injection power into account further; we will promote the online application value of resistance margin in the static stability, transient stability and dynamic stability analysis. © 2013 Chin. Soc. for Elec. Eng. Source


Liao C.C.,North China Electrical Power University
Material Science and Environmental Engineering - Proceedings of the 3rd annual 2015 International Conference on Material Science and Environmental Engineering, ICMSEE 2015 | Year: 2016

Since many real networks generally have characteristics of small-world networks, this paper proposes a revised SIR model on a dynamical small-world network model on the basis of the mean-field theory. The comparison of the result of simulation and reality shows that this method can be the basis of forecasting and preventing the spread of infectious virus. It truly reflects the situation and transmission of Ebola. © 2016 Taylor and Francis Group, London. Source


Li Y.,North China Electrical Power University
Journal of Information and Computational Science | Year: 2015

For overcoming many drawbacks existing in the current pricing mode, this study seeks to explore the pricing elements and process of medical services, and establish the dynamic pricing model of government and hospitals co-decision. The process showed the logical relationships between medical prices and pricing elements. And the Causal Relationship model revealed how to accomplish the dynamic equilibrium between elements. The simulation model was built based on System Dynamics theory. Through the simulation and the sensitivity tests, results showed different grades of hospitals applying the pricing model may give full play to the respective roles and continuously improve core strengths. ©, 2015, Journal of Information and Computational Science. All right reserved. Source


Wang W.,North China Electrical Power University | Han Z.-L.,Nankai University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

In this paper we propose a radiated linear seesaw model where the naturally small term μL is generated at the one-loop level and its soft breaking of lepton number symmetry contributes to the spontaneous breaking (SSB) of B-L gauge symmetry. The value of B-L charges for new particles are assigned to satisfy the cancellation of anomalies. It is found that some new particles may have exotic values of B-L charge such that there exists residual Z2×Z2′ symmetry even after SSB of B-L gauge symmetry. The Z2×Z2′ discrete symmetry stabilizes these particles as dark matter candidates. In the model, two classes of inert fermions and scalars with different B-L charges are introduced, leading to two-component dark matter candidates. The lepton-flavor-violation processes, the relic density of dark matter, the direct detection of dark matter and the phenomenology at the LHC are investigated. © 2015 American Physical Society. Source


Peng M.,Beijing Jiaotong University | Yang X.,North China Electrical Power University
Chaos | Year: 2010

A detailed analysis of zero distributions in a special polynomial of the form λτ(λ-a1)(λ-a2)⋯(λ-an)-(c+id) is proposed, where all ai(i=1,2,...,) have the same sign. As its applications, new criteria for asymptotic behavior of nonlinear delayed coupled systems with different topological structures are established. All possible bifurcations, including codimension-two bifurcations with 1:4/1:3 strong resonance in such a delayed difference system, are discussed. Numerical simulation gives a solid verification of the theoretical analysis. © 2010 American Institute of Physics. Source


Yong W.,North China Electrical Power University
Soft Computing | Year: 2014

The objective of traveling salesman problem (TSP) is to find the optimal Hamiltonian circuit (OHC). It has been proven to be NP complete in most cases. The hybrid Max–Min ant system (MMA) integrated with a four vertices and three lines inequality is introduced to search the OHC. The four vertices and three lines inequality is taken as the constraints of the local optimal Hamiltonian paths (LOHP), including four vertices and three lines and all the LOHPs in the OHC conform to the inequality. At first, the MMA is used to search the approximate OHCs. Then, the local paths of adjacent four vertices in the approximate OHCs are converted into the LOHPs with the four vertices and three lines inequality to get the better approximation. The hybrid Max–Min ant system (HMMA) is tested with tens of TSP instances. The results show that the better approximations are computed with the HMMA than those with the MMA under the same preconditions. © 2014, Springer-Verlag Berlin Heidelberg. Source


Ding P.,Shandong University | Sun D.L.,North China Electrical Power University
Numerical Heat Transfer, Part B: Fundamentals | Year: 2013

In this article, a novel finite-volume solver for the two-dimensional incompressible flow on unstructured grids is presented. The solver is formulated to operate on any type of control volumes. The performance of the new algorithm as compared to the SIMPLE algorithm is tested by solving three benchmark problems using both methodologies and comparing their computational costs. Results indicate that the new algorithm can reach convergence in a more wide parameter range and it is at least two times faster than the SIMPLE algorithm. The advantage of the new algorithm is especially evident for the case of high Reynolds number. © 2013 Copyright Taylor and Francis Group, LLC. Source


Lei J.,North China Electrical Power University
Computers and Electrical Engineering | Year: 2011

Compressed sensing (CS) is considered as a promising signal processing technique, and successful applications of the CS theory depend mainly on the accuracy and speed of the reconstruction algorithms. In this paper, a generalized objective functional, which has been developed using the combinational estimation and an extended stabilizing functional, is proposed. An efficient iterative scheme, which integrates the beneficial advantages of the homotopy method, the shuffled frog-leaping (SFL) algorithm and the harmony search (HS) algorithm, is designed for searching a possible global optimal solution. Numerical simulations are implemented to evaluate the numerical performances and effectiveness of the proposed algorithm. Excellent numerical performances and encouraging results are observed. For the cases considered in this paper, a dramatic improvement in the reconstruction accuracy is achieved, which indicates that the proposed algorithm is a promising candidate for solving CS inverse problem. © 2011 Elsevier Ltd. All rights reserved. Source


Li H.,Hunan University | Lei J.,North China Electrical Power University | Liu Q.,CAS Institute of Engineering Thermophysics
International Journal of Heat and Mass Transfer | Year: 2012

The inverse heat conduction problems (IHCP) analysis method provides an efficient approach for estimating the thermophysical properties of materials, the boundary conditions, or the initial conditions. Successful applications of the IHCP method depend mainly on the efficiency of the inversion algorithms. In this paper, a generalized objective functional, which has been developed using a generalized stabilizing functional and a combinational estimation that integrates the advantages of the least trimmed squares (LTS) estimation and the M-estimation, is proposed. The objective functional unifies the regularized M-estimation, the regularized least squares (LS) estimation, the regularized LTS estimation, the regularized combinational estimation of the LTS estimation and the M-estimation, and the regularized combinational estimation of the LS estimation and the M-estimation into a concise formula. The filled function method, which is coupled with the Broyden-Fletcher-Goldfarb-Shanno (BFGS) algorithm, is developed for searching a possible global optimal solution. Numerical simulations are implemented to evaluate the feasibility and effectiveness of the proposed algorithm. Favorable numerical performances and satisfactory results are observed, which indicates that the proposed algorithm is successful in solving the IHCP. © 2012 Elsevier Ltd. All rights reserved. Source


Wang Z.-G.,North China Electrical Power University
European Physical Journal C | Year: 2013

In this article, we calculate the Bc *} → Bc electromagnetic form-factor with the three-point QCD sum rules and then study the radiative decays Bc *± → Bc ± γ. Experimentally, we can study the radiative transitions using the decay cascades Bc *± → Bc ± γ → J/ψℓ±ν̄ℓ γ → μ+ μ- ℓ±ν̄ ℓ γ in the future at the LHCb. © 2013 Springer-Verlag Berlin Heidelberg and Società Italiana di Fisica. Source


Lei Y.,Sun Yat Sen University | Wang Y.,Sun Yat Sen University | Huang J.,Sun Yat Sen University | Huang J.,North China Electrical Power University
Signal Processing: Image Communication | Year: 2011

Image authentication has become an emergency issue in the digital world as it can be easily tampered with the image editing techniques. In this paper, a novel robust hashing method for image authentication is proposed. The reported scheme first performs Radon transform (RT) on the image, and calculates the moment features which are invariant to translation and scaling in the projection space. Then discrete Fourier transform (DFT) is applied on the moment features to resist rotation. Finally, the magnitude of the significant DFT coefficients is normalized and quantized as the image hash bits. Experimental results show that the proposed algorithm can tolerate almost all the typical image processing manipulations, including JPEG compression, geometric distortion, blur, addition of noise, and enhancement. Compared with other approaches in the literature, the reported method is more effective for image authentication in terms of detection performance and the hash size. © 2011 Elsevier B.V. All rights reserved. Source


Wang X.,North China Electrical Power University
World Transactions on Engineering and Technology Education | Year: 2015

Radiative image detection has led to great advances in clinical science, with ultrasound (US) imaging playing an important part in information engineering. To attract students toward the study of US imaging, an interactive and autonomic learning mode is proposed. The teaching has four steps, viz. pre-discussion stage to determine the next topic to be studied, literature survey and programming homework, presentation of the homework and a formal lecture. In the homework, two experimental subgroups applied the SUSAN (smallest univalue segment assimilating nucleus) transform and the watershed method to segment a US image of an embryo. In class, there was an open, competitive, but friendly discussion between subgroups to present their homework programs. This demonstrated the understanding by autonomic learning of the concepts and main properties of US medical imaging. The lecture expatiates US imaging principles, and sums up merits and drawbacks of US imaging. A questionnaire and test results show a positive outcome for the proposed learning method, with good intuitive understanding of techniques by experimental subgroup members. © 2015 WIETE. Source


Wang X.,North China Electrical Power University
World Transactions on Engineering and Technology Education | Year: 2015

The techniques and technology for denoising printed text characters from scanned historical documents forms a defined part of the content in information technology education. In this article, a class teaching case is reported based on designing three visual experiments involving image enhancement. It is pointed out to undergraduate students that the traditional anisotropic diffusion equation method is not suitable for the image enhancement of blurred printed text. New convolution masks are subsequently put forward as part of a novel anisotropic diffusion equation, in order to improve the enhancement. Course experiments verify that the novel method can more efficiently recover the text strokes from background grey noise, with less computational time. Such algorithm design is important for image enhancement education, and the visualised class teaching can effectively attract the students' attention. © 2015 WIETE. Source


Wang Z.-G.,North China Electrical Power University
International Journal of Modern Physics A | Year: 2013

In this paper, we calculate the mass modifications of the vector and axial vector mesons D*, B*, D1 and B1 in the nuclear matter with the QCD sum rules, and obtain the mass-shifts δM D* =-71 MeV, δMB* =-380 MeV, δMD1 = 72 MeV, δMB1 = 264 MeV, and the scattering lengths aD* =-1.07 fm, a B* =-7.17 fm, aD1 = 1.15 fm and a B1 = 5.03 fm for the D*N, B*N, D1N and B1N interactions, respectively. © 2013 World Scientific Publishing Company. Source


Wang Z.-G.,North China Electrical Power University
European Physical Journal A | Year: 2013

In this article, we study the vector and axialvector Bc mesons with QCD sum rules, and make reasonable predictions for the masses and decay constants, then calculate the leptonic decay widths. The present predictions for the masses and decay constants can be confronted with the experimental data in the future. We can also take the masses and decay constants as basic input parameters and study other phenomenological quantities with the three-point vacuum correlation functions via QCD sum rules. © Societá Italiana di Fisica / Springer-Verlag 2013. Source


Luo Z.D.,North China Electrical Power University
Journal of Scientific Computing | Year: 2015

At first, a semi-discrete Crank–Nicolson (CN) formulation with respect to time for the non-stationary incompressible Boussinesq equations is presented. Then, a fully discrete stabilized CN mixed finite volume element (SCNMFVE) formulation based on two local Gauss integrals and parameter-free is established directly from the semi-discrete CN formulation with respect to time. Next, the error estimates for the fully discrete SCNMFVE solutions are derived by means of the standard CN mixed finite element method. Finally, some numerical experiments are presented illustrating that the numerical errors are consistent with theoretical results, the computing load for the fully discrete SCNMFVE formulation are far fewer than that for the stabilized mixed finite volume element (SMFVE) formulation with the first time accuracy, and its accumulation of truncation errors in the computational process is far lesser than that of the SMFVE formulation with the first time accuracy. Thus, the advantage of the fully discrete SCNMFVE formulation for the non-stationary incompressible Boussinesq equations is shown sufficiently. © 2015 Springer Science+Business Media New York Source


Su X.,North China Electrical Power University | Zheng L.,University of Science and Technology Beijing
Central European Journal of Physics | Year: 2013

This paper deals with the boundary layer flow and heat transfer of nanofluids over a stretching wedge with velocity-slip boundary conditions. In this analysis, Hall effect and Joule heating are taken into consideration. Four different types of water-base nanofluids containing copper (Cu), silver (Ag), alumina (Al2O3), and titania (TiO2) nanoparticles are analyzed. The partial differential equations governing the flow and temperature fields are converted into a system of nonlinear ordinary differential equations using a similarity transformation. The resulting similarity equations are then solved by using the shooting technique along with the fourth order Runge-Kutta method. The effects of types of nanoparticles, the volume fraction of nanoparticles, the magnetic parameter, the Hall parameter, the wedge angle parameter, and the velocityslip parameter on the velocity and temperature fields are discussed and presented graphically, respectively. © 2013 Versita Warsaw and Springer-Verlag Wien. Source


Cai B.,North China Electrical Power University
Applied Mechanics and Materials | Year: 2014

currently, more and more following-setting compensation arc suppression coils are applied. When the power distribution network is operated in a loop closing mode, the problems about the parallel operation of the following-setting compensation arc suppression coils are caused. On the basis that the operational characteristics of the following-setting compensation arc suppression coils are analyzed, the improved master-slaved type automatic control technology of the parallel operation of the multiple following-setting compensation suppression coils is proposed. When the capacitive current is calculated, all slave arc suppression coils should go into service with the respective compensating capacity of each when operated on the respective shunt, then the master arc suppression coil is adjusted, and therefore the calculation accuracy is guaranteed. After the calculation of the capacitive current is completed, the compensating current should be proportionally distributed according to the capacity of the arc suppression coils so that the loads of all the arc suppression coils are balanced. The technology is mature and reliable and the practicability of the technology is fully proved by the actual field operation. © (2014) Trans Tech Publications, Switzerland. Source


Chung C.Y.,Hong Kong Polytechnic University | Yu H.,Hong Kong Polytechnic University | Yu H.,North China Electrical Power University | Wong K.P.,University of Western Australia
IEEE Transactions on Power Systems | Year: 2011

Based on a quantum-inspired evolutionary algorithm for unit commitment, this paper proposed ways to advance the efficiency and robustness of the algorithm so that its capacity for application in large-scale unit commitment problems can be significantly enhanced. The paper develops an advanced quantum-inspired evolutionary unit commitment algorithm by developing a new initialization method based on unit priority list and a special Q-bit expression for ensuring diversity in the initial search area for improving the efficiency of solution searching. Different techniques such as multi-observation, single-search, and group-search are also proposed for incorporation in the advanced algorithm. The advanced algorithm is tested and compared with the earlier quantum-inspired evolutionary algorithm and a number of known methods through its applications to test systems with up to 100 generator units for a 24-h scheduling horizon. © 2010 IEEE. Source


Guo Q.-l.,North China Electrical Power University | Guo Q.-l.,University of Science and Technology Beijing | Zhang M.,University of Science and Technology Beijing
Robotics and Computer-Integrated Manufacturing | Year: 2010

Agent technology is considered as a promising approach for developing optimizing process plans in intelligent manufacturing. As a bridge between computer aided design (CAD) and computer aided manufacturing (CAM), the computer aided scheduling optimization (CASO) plays an important role in the computer integrated manufacturing (CIM) environment. In order to develop a multi-agent-based scheduling system for intelligent manufacturing, it is necessary to build various functional agents for all the resources and an agent manager to improve the scheduling agility. Identifying the shortcomings of traditional scheduling algorithm in intelligent manufacturing, the architecture of intelligent manufacturing system based on multi-agent is put forward, among which agent represents the basic processing entity. Multi-agent-based scheduling is a new intelligent scheduling method based on the theories of multi-agent system (MAS) and distributed artificial intelligence (DAI). It views intelligent manufacturing as composed of a set of intelligent agents, who are responsible for one or more activities and interacting with other related agents in planning and executing their responsibilities. In this paper, the proposed architecture consists of various autonomous agents that are capable of communicating with each other and making decisions based on their knowledge. The architecture of intelligent manufacturing, the scheduling optimization algorithm, the negotiation processes and protocols among the agents are described in detail. A prototype system is built and validated in an illustrative example, which demonstrates the feasibility of the proposed approach. The experiments prove that the implementation of multi-agent technology in intelligent manufacturing system makes the operations much more flexible, economical and energy efficient. © 2009 Elsevier Ltd. All rights reserved. Source


Wang W.,Zhejiang University | Wang W.,North China Electrical Power University | Huang J.-H.,Zhejiang University | Sheng Z.-M.,Zhejiang University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

The Z→e+e- decay is studied based on the noncommutative standard model with the hybrid gauge transformation. It is shown that if the latter is not included, the noncommutative correction to the amplitude of the Z→e+e- appears only as a phase factor, so that there is no new physical effect on the decay width. However, when the hybrid gauge transformation is included, the noncommutative effect appears in the two-body decay process. The discrepancy between the experimental branch ratio and the standard model prediction allows us to set the bound on the noncommutative parameters. © 2013 American Physical Society. Source


After large scale blackout, there may be more than one black-start unit in power system. A rational subsystem partitioning restoration scheme could speed up the entire system restoration procedure and promote restoration reliability. In the paper, a subsystem partitioning strategy considering the restoration reliability is proposed. The calculation of nodes restoration reliability based on the disjoint of Binary Decision Diagram (BDD) algorithm. Then according to different restoration reliability of nodes to be restored by different black-start units or charged areas, as well as its restoration time of the paths, the belonging subsystems are identified. The proposed subsystem partitioning restoration pays extra attention to the uncertainty of transmission lines and transformers which fits the practical operation conditions better. A partitioning criterion function which is solved by genetic algorithm is established to evaluate the partitioning result. Finally, the effectiveness of the proposed method is validated by IEEE 118 bus system. © 2015, Strojarski Facultet. All rights reserved. Source


Wei M.Y.,North China Electrical Power University
Applied Mechanics and Materials | Year: 2014

For the study of distributed generation and its impact on power system, this paper briefly introduces the basic concept, the advantages of distributed generation, and the concept and basic structure of micro-grid. From the power system planning, system voltage, power quality, island effect, relay protection and other aspects, this paper analysis and discusses the influence of distributed power on power system. To properly resolve the grid-connected distributed generation power influence, it will be helpful for the development of future of distributed power generation. Distributed power generation can be used not only as an important supplement of the traditional centralized power supply mode, but also as a very important role in energy utilization, it will become an important area of research and development in future energy. © (2014) Trans Tech Publications, Switzerland. Source


Zhang S.,North China Electrical Power University
Energy | Year: 2016

DSPV (Distributed solar PV) power, either located on rooftops or ground-mounted, is by far one of the most important and fast-growing renewable energy technologies. Since the second half of 2012, China has shifted from LSPV (large-scale solar PV) to DSPV and a series of policy to promote DSPV power deployment have been put in place. Unfortunately these policies were not well performed due to myriad constraints on DSPV power deployment across the country. Building mainly on non-academic sources including government documents and presentations, industry reports and presentations, media reports, and interviews, this paper firstly provides a comprehensive review of China's policy on DSPV passed between the second half of 2012 and the first half of 2014, then barriers associated with DSPV deployment are identified. This is followed by an account and discussions of recent policy changes since Sep 2014, and major local incentives. In addition, policy performance is briefly reviewed. At the end of the paper, conclusions and policy implications are provided. This paper provides an understanding of the recent DSPV policy progress in China and insights for policy makers in other economies which are experimenting DSPV power policies. © 2016 Published by Elsevier Ltd. Source


Zhao X.,North China Electrical Power University | Zhao X.,University of Michigan | Yin H.,Shanghai JiaoTong University | Yin H.,University of Michigan
Energy Policy | Year: 2011

With economic development and the change of industrial structure, industrial relocation is an inevitable trend. In the process of industrial relocation, environmental externality and social cost could occur due to market failure and government failure. Little attention has been paid to this issue. In this paper, we address it with a theoretical analysis and an empirical investigation on the relationship between China's industrial relocation in the early 1990s and energy consumption which is the primary source of CO 2 emission, an environmental externality that causes increasing concerns. The macro-policy analysis suggests that there would be a positive link between China's industrial relocation in the early 1990s and energy saving (and environmental externalities reduction). Using fixed-effect regression model and simulation method, we provide an empirical support to this argument. In order to further reduce environmental externalities and social cost in the process of industrial relocation, we provide policy suggestions as follows: First, strengthen the evaluation of environmental benefits/costs; Second, pay more attention to the coordinated social-economic development; Third, avoid long-lived investment in high-carbon infrastructure in areas with industries moved in; Fourth, address employment issue in the areas with industries moved out. © 2011 Elsevier Ltd. Source


Zhang Z.,North China Electrical Power University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012

The recent lattice calculation at finite axial chemical potential suggests that the induced current density of the chiral magnetic effect (CME) is somehow suppressed compared with the standard analytical formula. We show in a Nambu-Jona-Lasino-type model of QCD that such a suppression is a natural result when considering the influence of the attractive axial-vector interaction. We point out that the lattice result does not need to be quantitatively consistent with the analytical formula due to the chirality density-density correlation. We also investigate the nonperturbative effect of instanton molecules on the CME. Since an unconventional repulsive axial-vector interaction is induced, the CME will be enhanced significantly by the instanton-anti-instanton pairings. Such a prediction needs to be tested by more improved lattice simulations. We further demonstrate that the axial-vector interaction plays an important role on the T-μ A phase diagram. © 2012 American Physical Society. Source


Wang Z.-G.,North China Electrical Power University
Communications in Theoretical Physics | Year: 2012

In this article, we study the (1/2) ± and (3/2) ± triply heavy baryon states in a systematic way by subtracting the contributions from the corresponding (1/2) ∓ and (3/2) ∓ triply heavy baryon states with the QCD sum rules, and make reasonable predictions for their masses. © 2012 Chinese Physical Society and IOP Publishing Ltd. Source


Wang Z.-G.,North China Electrical Power University
European Physical Journal C | Year: 2013

In this article, we take the tensor currents Q̄(x)σμνQ(x) to interpolate the P-wave spin-singlet heavy quarkonium states hQ, and study the masses and decay constants with the Borel sum rules and moments sum rules. The masses and decay constants from the Borel sum rules and moments sum rules are consistent with each other, the masses are also consistent with the experimental data. We can take the decay constants as basic input parameters and study other phenomenological quantities with the three-point correlation functions via the QCD sum rules. The heavy quarkonium states h Q couple potentially to the tensor currents Q̄(x)σμνQ(x), and have the quark structure ε{lunate}ijkξ†σkζ besides the quark structure. In calculations, we take into account the leading-order, next-to-leading-order perturbative contributions, and the gluon condensate, four-quark condensate contributions in the operator product expansion. The analytical expressions of the perturbative QCD spectral densities have applications in studying the two-body decays of a boson to two fermions with the vertexes σμνγ5 and σμν. © 2013 Springer-Verlag Berlin Heidelberg and Società Italiana di Fisica. Source


Wang W.,North China Electrical Power University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2014

In this paper we investigate the parallel texture structures with cofactor zeros in the charged lepton and neutrino sectors. The textures cannot be obtained from arbitrary leptonic matrices by making weak basis transformations, which therefore have physical meaning. The 15 parallel textures are grouped as 4 classes where each class has the same physical implications. It is founded that one of them is not phenomenologically viable and another is equivalent to the texture zero structures extensively explored in previous literature. Thus we focus on the other two classes of parallel texture structures and study the their phenomenological implications. The constraints on the physical variables are obtained for each class, which is essential for the model selection and can be measured by future experiments. The model realization is illustrated in a radiated lepton mass model. © 2014. Source


Sun Z.,University of Science and Technology Beijing | Sun Z.,North China Electrical Power University
European Physical Journal D | Year: 2014

Based on Thomas-Fermi density functional theory, itinerant ferromagnetism of repulsive two-component Fermi gas trapped in a triple-well is studied. The density profiles of the two components are calculated in three types of triple-well trapping potential. The conclusion is drawn that phase separation relates closely not only to the interaction strength, but also to the shape of the trapping potential, which plays a critical role in determining the density profile of the gas. The separation in each type of trapping potential is a result of the competition between repulsive interaction energy and the kinetic energy. Numerical results show that phase separation occurs once the coupling constant reaches a critical value. With further increase in the coupling constant, the interplay between wells is enhanced, which may cause complex separation. Despite our crude treatment in the Thomas-Fermi approximation, the results may help to explore and understand the nature of itinerant ferromagnetism of trapped Fermi mixtures in both theoretical and experimental research in the future. © 2014 EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg. Source


Feng X.,North China Electrical Power University
Mocaxue Xuebao/Tribology | Year: 2012

The friction and wear properties of two kinds of fluorosilicone oils and PN (amine salt of alkoxyl phosphate) as lubricant additives in poly-alpha-olefin are evaluated using an Optimol SRV reciprocating friction and wear tester by bronze disc against AISI 52100 steel ball. The morphologies of worn surfaces of the bronze discs are examined using a scanning electron microscopy. In addition, the elemental compositions and chemical states of several typical elements on the worn surfaces of the bronze discs are examined by means of X-ray photoelectron spectroscopy. Results indicate that oils containing PN and fluorosilicone as additives exhibit excellent wear-resistance and low and stable friction coefficient. This is partly attributed to tribophysical and tribochemical reaction of phosphorus, nitrogen and fluorine with the sliding surfaces. Source


Wang Z.-G.,North China Electrical Power University
European Physical Journal C | Year: 2014

In this article, we calculate the contributions of the vacuum condensates up to dimension 10 in the operator product expansion, and study the (Formula presented.) molecular states with the QCD sum rules. In the calculations, we use the formula (Formula presented.) to determine the energy scales of the QCD spectral densities. The numerical results favor assigning the Zc(4020) and Zc(4025) to the (Formula presented.) molecular states, the Y (4140) to the J PC = 0++ D∗ s D∗ s molecular state, the Zb(10650) to the J PC = 1+− B∗ B ∗ molecular state, and they disfavor assigning the Y (3940) to the (J PC = 0++) molecular state. The present predictions can be confronted with the experimental data in the future. © The Author(s) 2014. Source


An N.,Hefei University of Technology | Zhao W.,Lanzhou University | Wang J.,Lanzhou University | Shang D.,University College of Applied Sciences | Zhao E.,North China Electrical Power University
Energy | Year: 2013

For accurate electricity demand forecasting, this paper proposes a novel approach, MFES, that combines a multi-output FFNN (feedforward neural network) with EMD (empirical mode decomposition)-based signal filtering and seasonal adjustment. In electricity demand forecasting, noise signals, caused by various unstable factors, often corrupt demand series. To reduce these noise signals, MFES first uses an EMD-based signal filtering method which is fully data-driven. Secondly, MFES removes the seasonal component from the denoised demand series and models the resultant series using FFNN model with a multi-output strategy. This multi-output strategy can overcome the limitations of common multi-step-ahead forecasting approaches, including error amplification and the neglect of dependency between inputs and outputs. At last, MFES obtains the final prediction by restoring the season indexes back to the FFNN forecasts. Using the half-hour electricity demand series of New South Wales in Australia, this paper demonstrates that the proposed MFES model improves the forecasting accuracy noticeably comparing with existing models. © 2012 Elsevier Ltd. Source


Wang Z.-G.,North China Electrical Power University
European Physical Journal C | Year: 2014

In the article, we calculate the hadronic coupling constants (Formula presented.)with the three-point QCD sum rules, then study the two-body strong decays (Formula presented.), and make predictions to be confronted with the experimental data in the future. © 2014, The Author(s). Source


Zhang X.,KTH Royal Institute of Technology | Yang W.,KTH Royal Institute of Technology | Dong C.,North China Electrical Power University
Journal of Analytical and Applied Pyrolysis | Year: 2013

Levoglucosan is one important primary product during cellulose pyrolysis either as an intermediate or as a product. Three available mechanisms for levoglucosan formation have been studied theoretically in this paper, which are free-radical mechanism; glucose intermediate mechanism; and levoglucosan chain-end mechanism. All the elementary reactions included in the pathway of every mechanism were investigated; thermal properties including activation energy, Gibbs free energy, and enthalpy for every pathway were also calculated. It was concluded that free-radical mechanism has the highest energy barrier during the three levoglucosan formation mechanisms, glucose intermediate mechanism has lower energy barrier than free-radical mechanism, and levoglucosan chain-end mechanism is the most reasonable pathway because of the lowest energy barrier. By comparing with the activation energy obtained from the experimental results, it was also concluded that levoglucosan chain-end mechanism fits better with the experimental data for the formation of levoglucosan. © 2013 Elsevier B.V. All rights reserved. Source


Wang C.,Bohai University | Chen D.,North China Electrical Power University | Hu Q.,Tianjin University
Fuzzy Sets and Systems | Year: 2014

With the arrival of the information age, information acquisition and communication have become more and more important in the field of information technology. This paper uses the concept of homomorphism as a basic tool to study the communication between fuzzy information systems. The concepts of consistent and compatible mappings with respect to fuzzy sets are firstly defined and their basic properties are studied. Then, a pair of lower and upper rough fuzzy approximation operators is constructed by means of the concept of fuzzy mappings. Basic invariant properties of the approximation operators are investigated. Finally, the concepts of fuzzy information system and its homomorphism are introduced, and some invariant properties of fuzzy information systems under homomorphisms are examined. It is proved that the attribute reductions of an original information system and its image system are equivalent to each other in the context of fuzzy attributes. These results may have potential applications in attribute reduction and classification issues. © 2014 Elsevier B.V. All rights reserved. Source


Yu S.,North China Electrical Power University
RISTI - Revista Iberica de Sistemas e Tecnologias de Informacao | Year: 2016

Sports industry has become the most promising emerging industries in the 21st century. The industrialization of sports competition is an important part of sports industry, it is the product of the combination of sports and market, and has great developing potency. The traditional manual schedule arrangement of track and field meeting is a very complicated work, which is very easy to make mistakes by manual processing. Therefore, in order to solve the existing problems in the traditional manual schedule management, the schedule arrangement system of track and field sports competition based on artificial intelligence is designed in this paper. The design scheme, the realization method of the system, the development tools and related technologies are expounded, and how to use artificial intelligence technology to develop the schedule management system of track and field sports meeting is described, then based on the genetic algorithm in artificial intelligence, the schedule arrangement algorithm is researched, thus a schedule arrangement system of track and field sports competition is designed on the basis of the artificial intelligence. The experiment proved its effectiveness. This system can solve the existing problems in the traditional manual schedule management, improve management level, management quality and work efficiency of the sports meeting, and save a lot of manpower, material resources and time for event managers. Source


Han Y.,CAS Institute of Physics | Li W.Y.,CAS Institute of Physics | Cao L.X.,CAS Institute of Physics | Wang X.Y.,CAS Institute of Semiconductors | And 4 more authors.
Physical Review Letters | Year: 2010

By realizing in thin films a tensile stress state, superconductivity of 13 K was introduced into FeTe, a nonsuperconducting parent compound of the iron pnictides and chalcogenides, with a transition temperature higher than that of its superconducting isostructural counterpart FeSe. For these tensile stressed films, superconductivity is accompanied by a softening of the first-order magnetic and structural phase transition, and also, the in-plane extension and out-of-plane contraction are universal in all FeTe films independent of the sign of the lattice mismatch, either positive or negative. Moreover, the correlations were found to exist between the transition temperatures and the tetrahedra bond angles in these thin films. © 2010 The American Physical Society. Source


Zhang S.,North China Electrical Power University | Pan B.,Changjiang River Scientific Research Institute
Journal of Hydrology | Year: 2014

With the increase of urbanization, conditions of the underlying surface and climate have been changed by human activities. This results in more frequent flooding and inundation problems in urban areas. Storm-inundation models based on hydrology and hydrodynamics require a large amount of input data (detailed terrain, sewer system and land use data). Simulation models are complex and difficult to build and run. To determine inundation conditions quickly with only a few commonly available input data, an urban storm-inundation simulation method (USISM) based on geographic information systems (GIS) is proposed in this paper. The method is a kind of simplified distributed hydrologic model based on DEM, in this method, depressions in the terrain are regarded as the basic inundated area. The amount of water that can be stored in a depression indicates the final inundation distribution. The runoff catchment area and maximum storage volume of a depression, and the flow direction between these depressions are all considered in the final inundation simulation. GIS technology is used to find the depressions in an area, divide the subcatchment for each depression, and obtain the flow order of the depressions based on a digital elevation model (DEM). The SCS method is used to calculate storm runoff, and a water balance equation is used to calculate water storage in each depression. Nangang District in Harbin City, China, is selected as the study area to verify the USISM. The result reveals that the USISM could find inundation locations in the urban area and quickly calculate inundation depth and area. The USISM is valuable for simulating storms of short duration in an urban area with a few commonly available input data. © 2014 Elsevier B.V. Source


Huang Y.,Xinjiang Institute of Ecology and Geography | Li Y.P.,North China Electrical Power University | Chen X.,Xinjiang Institute of Ecology and Geography | Ma Y.G.,Xinjiang Remote Sensing Center
Agricultural Water Management | Year: 2012

An integrated optimization method is developed for supporting agriculture water management and planning in Tarim River Basin, Northwest China. The developed method couples two-stage stochastic programming (TSP) with inexact quadratic program (IQP). The hydrological model is provided for forecasting the available irrigation water. The simulation system is then embedded into an optimization framework, where the objective is to maximize the system benefit for water resources management. The developed method can not only deal with nonlinearities in the cost/benefit objective and uncertainties expressed as probabilities and intervals, but also support the analysis of policy scenarios that are associated with economic penalties when the promised water-allocation targets are violated. A case study is conducted for Kaidu-kongque watershed in Tarim River Basin. The results obtained can help generate desired policies for water resources management with maximized economic benefit and minimized system-failure risk. © 2012 Elsevier B.V.. Source


Xu E.,CAS Institute of Electrical Engineering | Yu Q.,CAS Institute of Electrical Engineering | Wang Z.,CAS Institute of Electrical Engineering | Yang C.,North China Electrical Power University
Renewable Energy | Year: 2011

1 MW Dahan solar thermal power tower plant is modeled from mathematical models for all of the working conditions using the modular modeling method. The dynamic and static characteristics of the power plant are analyzed based on these models. Response curves of the system state parameters are given for different solar irradiance disturbances. Conclusions in this paper are good references for the design of solar thermal power tower plant. © 2010 Elsevier Ltd. Source


Tian L.,China Electric Power Research Institute | Shi S.,China Electric Power Research Institute | Jia Z.,North China Electrical Power University
Dianwang Jishu/Power System Technology | Year: 2010

After the utilization of electric vehicles on a large scale, the demand on their charging power will impact power grid to some extent. The factors related to the demand on charging power of electric vehicles are analyzed. Under a certain assumed conditions, according to statistical data of internal combustion cars and taking the probability distribution of some enchancement factors, a statistical model of electric vehicles' power demand is built. The mathematical expectation of single electric vehicle's power demand and its standard deviation are solved by Monte Carlo simulation, after that a method to compute total power demand of many electric vehicles is given. Taking the daily load curves of Bejing and Shanghai in a certain day in summer for example, the impacts of power demand of electric vehicles in different scales on original load curves are calculated. Calculation results show that the natural charging characteristic of electric vehicles makes maximum load of power grid increased in a certain extent. Not only the proposed statistical model is available for the research on the impact of electric vehicle on power grid, but also it is availabe for refernece to the design of the strategy to manage the charging of electric vehicles. Source


Liu J.-C.,North China Electrical Power University
Journal of Electron Spectroscopy and Related Phenomena | Year: 2014

The electron dynamics of a tightly bound system exposed to an ultraintense extreme-ultraviolet laser field is investigated by solving numerically the relativistically corrected two-dimensional time-dependent Schrödinger equation. The Coulomb interaction between the single-active electron and the parent ion is included throughout the harmonic generation process. The nondipole effects are found to be more pronounced with the increase of the ionization potential. The structure of the below-threshold harmonics changes drastically for different field intensities. The time-frequency analysis of the electron acceleration gives clearly the time-resolved harmonic spectrum and its dependence on the intensity of the pump field. With proper driving field intensities and ramp durations, hyper-Raman lines appear in the harmonic spectra for the soft-core potential. But due to multiple excitations of the atomic bound states, the hyper-Raman lines are spiked and broadened. When nearly full ionization occurs at the tail of the driving field, the HR lines disappear, while the emission of the odd harmonic lines is found to be most efficient then. © 2014 Elsevier B.V. Source


Hung T.-C.,Roc Military Academy | Yan W.-M.,National University of Tainan | Wang X.-D.,North China Electrical Power University | Chang C.-Y.,National University of Tainan
International Journal of Heat and Mass Transfer | Year: 2012

Heat transfer enhancement in a 3-D microchannel heat sink (MCHS) using nanofluids is investigated by a numerical study. The addition of nanoparticles to the coolant fluid changes its thermophysical properties in ways that are closely related to the type of nanoparticle, base fluid, particle volume fraction, particle size, and pumping power. The calculations in this work suggest that the best heat transfer enhancement can be obtained by using a system with an Al 2O 3-water nanofluid-cooled MCHS. Moreover, using base fluids with lower dynamic viscosity (such as water) and substrate materials with high thermal conductivity enhance the thermal performance of the MCHS. The results also show that as the particle volume fraction of the nanofluid increases, the thermal resistance first decreases and then increases. The lowest thermal resistance can be obtained by properly adjusting the volume fraction and pumping power under given geometric conditions. For a moderate range of particle sizes, the MCHS yields better performance when nanofluids with smaller nanoparticles are used. Furthermore, the overall thermal resistance of the MCHS is reduced significantly by increasing the pumping power. The heat transfer performance of Al 2O 3-water and diamond-water nanofluids was 21.6% better than that of pure water. The results reported here may facilitate improvements in the thermal performance of MCHSs. © 2012 Elsevier Ltd. All rights reserved. Source


Hung T.-C.,Military Academy | Yan W.-M.,National University of Tainan | Yan W.-M.,Research Center for Energy Technology and Strategy | Wang X.-D.,North China Electrical Power University | Huang Y.-X.,National Cheng Kung University
International Journal of Heat and Mass Transfer | Year: 2012

This work uses an optimization procedure consisting of a simplified conjugate-gradient method and a three-dimensional fluid flow and heat transfer model to investigate the optimal geometric parameters of a double-layered microchannel heat sink (DL-MCHS). The overall thermal resistance R T is the objective function to be minimized, and the number of channels N, channel width ratio β, lower channel aspect ratio α l, and upper channel aspect ratio α u are the search variables. For a given bottom area (10 × 10 mm) and heat flux (100 W/cm 2), the optimal (minimum) thermal resistance of the double-layered microchannel heat sink is about R T = 0.12°C/m 2W. The corresponding optimal geometric parameters are N = 73, β = 0.50, α l = 3.52, and, α u = 7.21 under a total pumping power of 0.1 W. These parameters reduce the overall thermal resistance by 52.8% compared to that yielded by an initial guess (N = 112, β = 0.37, α l = 10.32, and α u = 10.93). Furthermore, the optimal thermal resistance decreases rapidly with the pumping power and then tends to approach an constant value. As the pumping power increases, the optimal values of N, α l, and α u increase, whereas the optimal β value decreases. However, increasing the pumping power further is not always cost-effective for practical heat sink designs. © 2012 Elsevier Ltd. All rights reserved. Source


Liu G.,CAS Guangzhou Institute of Energy Conversion | Xu J.,CAS Guangzhou Institute of Energy Conversion | Yang Y.,North China Electrical Power University
Microfluidics and Nanofluidics | Year: 2010

The smooth channel surface of microsystems delays boiling incipience in heated microchannels. In this paper, we use seed bubbles to trigger boiling heat transfer and control thermal non-equilibrium of liquid and vapor phases in parallel microchannels. The test section consisted of a top glass cover and a silicon substrate. Microheater array was integrated at the top glass cover surface and driven by a pulse voltage signal to generate seed bubbles in time sequence. Each microheater corresponds to a specific microchannel and is located in the microchannel upstream. Five triangular microchannels with a hydraulic diameter of 100 μm and a length of 12.0 mm were etched in the silicon substrate. A thin platinum film was deposited at the back surface of silicon chip with an effective heating area of 4,500 × 1,366 μm, acting as the main heater for the heat transfer system. Acetone liquid was used. With the data range reported here, boiling incipience was not initiated if wall superheats are smaller than 15°C without seed bubbles assisted. Injection seed bubbles triggers boiling incipience and controls thermal non-equilibrium between liquid and vapor phases successfully. Four modes of flow and heat transfer are identified. Modes 1, 2, and 4 are the stable ones without apparent oscillations of pressure drops and heating surface temperatures, and mode 3 displays flow instabilities with apparent amplitudes and long periods of these parameters. The four modes are divided based on the four types of flow patterns observed in microchannels. Seed bubble frequency is a key factor to influence the heat transfer. The higher the seed bubble frequency, the more decreased non-equilibrium between two phases and heating surface temperatures are. The seed bubble frequency can reach a saturation value, at which heat transfer enhancement attains the maximum degree, inferring that a complete thermal equilibrium of two phases is approached. The saturation frequency is about a couple of thousand Hertz in this study. © 2009 Springer-Verlag. Source


Zhai M.-Y.,North China Electrical Power University
IEEE Transactions on Power Delivery | Year: 2011

By employing the self-similarity properties of the power-line communications (PLC) orthogonal frequency-division multiplexing (OFDM) signals, this paper presents a novel PLC OFDM signal reconstruction solution based on the fractals. This new signal reconstruction solution consists of two methods that try to solve two main difficulties faced by the fractals interpolation. The first method is based on the affine transform, trying to determine the vertical scaling factors by a set of the middle points in each affine mapping, and solving the difficulty of determining the vertical scaling factors, which is one of the most difficult challenges faced by the fractal interpolation. The second method tries to solve the problem where the ordinary fractals interpolation cannot obtain the value of any arbitrary point directly, a very novel algorithm called the pointed point algorithm, based on iterated function systems, is proposed to reconstruct the PLC OFDM signals with the expected interpolation error. Numerical experiments have shown that great accuracy in the reconstruction of the OFDM signals has been found, leading to a significant improvement over other signal reconstruction methods. © 2011 IEEE. Source


Wu Y.,CANMET Energy | Wang C.,North China Electrical Power University | Tan Y.,CANMET Energy | Jia L.,CANMET Energy | Anthony E.J.,CANMET Energy
Applied Energy | Year: 2011

Oxy-fuel combustion experiments have been carried out on an oxygen-fired 100kWth mini-circulating fluidized bed combustion (CFBC) facility. Coal and petroleum coke were used as fuel together with different limestones (and fixed Ca:S molar ratios) premixed with the fuel, for in situ SO2 capture. The bed ash (BA) and fly ash (FA) samples produced from this unit were collected and characterized to obtain physical and chemical properties of the ash samples. The characterization methods used included X-ray fluorescence (XRF), X-ray diffraction (XRD), char carbon and free lime analysis, thermogravimetric analysis (TGA), and surface analysis. The main purpose of this work is to characterize the CFBC ashes from oxy-fuel firing to obtain a better understanding of the combustion process, and to identify any significant differences from the ash generated by a conventional air-fired CFBC. The primary difference in the sulfur capture mechanism between atmospheric air-fired and oxy-fuel FBC, at typical FBC temperatures (∼850°C), is that, in the air-fired case the limestone sorbents calcine, whereas the partial pressure of CO2 in oxy-fuel FBC is high enough to prevent calcination, and hence the sulfation process should mimic that seen in pressurized FBC (PFBC). Here, the char carbon content in the fly ash was much higher than that in the bed ash, and was also high by comparison with ash obtained from conventional commercial air-firing CFBC units. In addition, measurements of the free lime content in the bed and fly ash showed that the unreacted Ca sorbent was present primarily as CaCO3, indicating that sulfur capture in the oxy-fuel combustor occurred via direct sulfation. Limestone utilization for oxy-fuel combustion in this unit was generally lower than that in industrial-scale air-firing CFBCs, with better limestone performance found during combustion of petcoke running at relatively higher temperatures. The Brunauer-Emmett-Teller (BET) surface area and also the pore volume in the fly ash were much higher than in the bed ash and smaller size pores predominated in the fly ash samples. © 2011. Source


Cheng Y.,North China Electrical Power University | Zhai N.,Taian Power Supply Company
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2012

In the areas that have executed peak-valley price, reasonable adjustment of time period partition is a new problem when considering current customer responses. The fuzzy membership based method reported in the literature to divide time periods is no longer suitable for adjustment of time period partition. A new time period partition model for time-of-use electrical price based on customer response is proposed. This model compares the intensity variation of customers load profile proportion structure to estimate customer response degree and property index for each time point. Then, based on the response degree of each point, the model adjusts time period partition of fuzzy membership cluster analysis results. The model is applied on real data set of some regions. The results demonstrate that the model can effectively stimulate demand response through adjustment of time period partition scheme. © 2012 State Grid Electric Power Research Institute Press. Source


Zhao Z.,China Electric Power Research Institute | Hu H.,North China Electrical Power University
Dianwang Jishu/Power System Technology | Year: 2011

The constitution and features of communication service for smart power distribution and utilization system are analyzed. According to the application features of distribution network and electricity utilization system, the information acquisition in communication network for smart power distribution and utilization system is divided into three sevice sections, i.e., the point to collect distribution information, the point to collect electricity utilization information and the point to collect information of business office, and the service compositions in the three sevice sections are analyzed. A service data flow model of the communication service for power distribution and utilization that is converged towards the substation and three service flow models for the service sections are built, and the calcualtion mothods for the sercive sections as well as the calculation method for the data flow converged to the substation from the sections are proposed. The reasonableness and effectiveness of the proposed method are verified by the calculation example utilized in the 12th five-year program of China. Source


Zhao Z.-B.,North China Electrical Power University | Suo Z.-G.,Hebei Electric Power Research Institute
Gaodianya Jishu/High Voltage Engineering | Year: 2011

In accordance with the arbitrarily disposed grounding electrodes, taking the effect of grounding grid into account, we put forward a new method to inverse the parameters of horizontally stratified soil model on the basis of the Green function of horizontal multiple-layer soil and the calculation model of grounding grid with unequal spacing. The proposed method can be used in later expansion of station to select measurement electrode and the minimum distance of grounding grid in soil parameter measurement. In the validation of the method, the effectiveness of the equal-spacing four-electrode method, straight four-electrode method, and arbitrary four-electrode method is evaluated. By taking a simple grounding grid as example, the inversed soil model and grounding resistivity are compared for the cases with and without consideration of grounding grid. The effective range of the grounding grid is defined. It is required that, on the premise of measurement standard, the space between the connection line of measurement electrodes and the grounding gird edge is not less than 0.618 times that of the diagonal the grounding gird. Source


Zhai M.-Y.,North China Electrical Power University | Zhai M.-Y.,University of California at Berkeley
IEEE Transactions on Power Delivery | Year: 2011

With the decision to construct the smart grids around China, the power line communications (PLC) on the low-voltage (LV) distribution networks have become one of the potential technologies to commute the information between the end users and the power provider. In order to provide communications services with different priorities under the smart grids environment, it is a must to design a completely new PLC system with variable information rate, which means understanding of the LV PLC channel characteristics become vital. This paper presents the measurement results of channel properties of LV PLC systems after giving a general overview of the topologies for the typical LV distribution networks in China. The testing results show that the main reason influencing the reliable communication of high-speed data of power line is the attenuation of the high-frequency signal, which exhibits more obviously in the branch of power line. It is almost impossible to use the frequency range from 10 to 20 MHz for the reliable communications from distribution transformer to end user, so it must be solved with the aid of such means as the repeater and the modulation schemes. Considering the signal's attenuation, the lower frequency range from 2 to 10 MHz is more suitable for the high-speed data access system. Based on the general topologies of the LV distribution networks, a new method with the help of the reflection matrix based on the multiconductor transmission line theory is proposed to model the channel transfer functions, taking into account of the source inner impedance matrix. The simulation results fit the measured data quite well and verify the feasibility of the proposed modeling scheme. © 2010 IEEE. Source


Zhou G.,North China Electrical Power University | Zhou G.,Carnegie Mellon University | Yao S.-C.,Carnegie Mellon University
Applied Thermal Engineering | Year: 2011

There are three prominent theories with regard to the effects of surface roughness on the pressure drop of laminar liquid flow in micro-channels, the original constricted flow model, the constricted model containing roughness distribution and the roughness-viscosity model. However, they have only been validated with very limited data by the authors. To provide a more reliable guide for various micro-channel applications, a review of these theories was conducted based upon the broad experimental data in literature. It is found that all the normalized data of fRe can be predicted by the original constricted flow model within an error of about ±15%. It is possible that the constricted model containing roughness distribution and the roughness-viscosity model can be further improved for easier use. However, the data, which support these two theories, can also be predicted well by the original constricted flow model with similar accuracy. Furthermore, the dependence of the critical Reynolds number (transition to turbulent flow) on the relative roughness of micro-channels was examined based upon the broad and much scattered experimental data. It is interesting to find that the effects of large discrete roughness on the side walls of shallow micro-channels follow the roughness correlation of macro-channels. The critical Reynolds numbers for different kinds of rough micro-channels were correlated respectively. © 2010 Elsevier Ltd. All rights reserved. Source


Zhao W.,North China Electrical Power University
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2011

As the test data of electric power transformer fault diagnosis are incomplete and biased, a transformer fault diagnostic method is proposed based on selective Bayes classifier, which, with the ability to process uncertain information, combines DGA(Dissolved Gas Analysis) with other electrical test results. The transformer fault diagnosis model is built based on selective Bayes classifier. Its superiority in uncertain information processing is elaborated in detail. With the accumulated and improved training samples, it automatically modifies the parameters of network structure and probability distribution. Experimental results show that Bayes classifier is suitable for the transformer fault diagnosis. Source


Lin F.,North China Electrical Power University | Zeng H.,Fujian Electrical Power Co.
Dianwang Jishu/Power System Technology | Year: 2011

Due to the existence of distributed capacitance and transition resistance in HV transmission lines, existing fault location methods based on one-terminal impedance are not suitable for the one-terminal fault location of HV transmission lines. To solve this problem, a transmission line model based on distributed parameters is built and the calculation formula for operation voltage at reference position is defined. A location function based on phase characteristics and a location function based on amplitude characteristics, which utilize one-terminal data, are given. It is known from theoretical analysis that the voltage loaction function possesses different phase characteristics while the selected reference position is located at the left side or the right side of the faulty point, i. e., an only step abrupt change of the phase characteristic occurs while the reference position moves through the fault point, and when the selected reference position coincides with faulty point, the amplitude of votlage location function reaches its minimum. On this basis a one-terminal phase-based fault location method and a one-terminal amplitude-based fault location method for the fault location of single-phase earth fault of HV transmission line are proposed. Simulation results show that the two proposed fault location method are slightly affected by fault position, transition resistance and load current, their fault location results are accurate for high-resistance earth-fault, thus they can meet the requirement of on-site application. Source


Dong Z.,CAS Guangzhou Institute of Energy Conversation | Xu J.,North China Electrical Power University | Jiang F.,CAS Guangzhou Institute of Energy Conversation | Liu P.,CAS Guangzhou Institute of Energy Conversation
International Journal of Thermal Sciences | Year: 2012

Flow boiling in a microchannel is characterized by nucleation and dynamic behavior of vapor bubbles in the channel. In the present study, the effect of vapor bubble on fluid flow and heat transfer in a microchannel is investigated via lattice Boltzmann (LB) modeling. With respect to boiling flow in a single microchannel, the bubble nucleation, growth, and departure are simulated by using an improved hybrid LB model. Relating bubble behavior with fluid flow and boiling heat transfer provides some insight into the relevant fundamental physics on flow boiling in the microchannel. It is found that the bubble growth before its departure from the wall induces an obvious resistance to the fluid flow. The processes of nucleation and motion of different bubbles interact, leading to an alternate, either enhanced or weakened, effect of bubble behavior on the flow boiling. © 2011 Elsevier Masson SAS. All rights reserved. Source


Li J.,North China Electrical Power University
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2015

The interturn short circuit of the exciting winding is a common fault in turbine generators; however, its location is difficult to be determined with now available methods. Based on principal theories in electrical machines, we deduced the expression of harmonic component variation about exciting magnetomotive force (MMF), magnetic flux density in the air-gap, no-load electromotive force (e. m. f.) and circular currents between stator parallel branches in order to determine the location of the dynamic rotor winding interturn fault of turbine generators. Then, the characteristic quantity and diagnosis method about the dynamic rotor winding interturn fault were confirmed. The presented method was validated by simulative and experimental results. The two ratios were obtained, which one was the ratio of stator odd harmonic e. m. f variations and the other was the ratio of even harmonics of stator parallel branch circulation. They are one-to-one correspondence with the location of the excitation coils interturn short fault. So the location of the short circuit fault can be obtained. The proposed method can be used to detect the location of dynamic and static interturn faults of the exciting winding. © 2015 Chin. Soc. for Elec. Eng.. Source


Huang H.,North China Electrical Power University
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2016

The scientific evaluation of effective investment scale for wind power in certain system conditions is important for its sustainable development. An analytical model of effective wind power investment capacity is built based on the long-term market equilibrium model, which considers the volatility and randomness of wind power, a simulative calculation of effective wind power investment scale is carried out for IEEE 30-bus system based on the data of American PJM market, and the sensitiveness of main influencing factors is analyzed. Results show that, the wind power capacity cost, market demand level, fast peak regulation capability and grid transmission capacity are the key factors of wind power development. Suggestions are put forward for the optimal planning of China's wind power. © 2016, Electric Power Automation Equipment Press. All right reserved. Source


Sun J.,North China Electrical Power University
Proceedings 2011 International Conference on Mechatronic Science, Electric Engineering and Computer, MEC 2011 | Year: 2011

The layout scheme of photovoltaic cell arrays has the most significant impact on the total power generation in a large photovoltaic power plant. Here, a simple optimum layout scheme for single-axis tracking photovoltaic systems using PVSYST is proposed. First, the photovoltaic array reference spaces in north-south and east-west orientation are determined following the actual engineering experience. Then, using the power generation capacity of unit cost as the optimization function, the photovoltaic array spaces are meshed twice to obtain the optimization parameters. A real example was given to show the specifics of the method © 2011 IEEE. Source


Dengwen Z.,North China Electrical Power University
Proceedings - 2010 3rd International Congress on Image and Signal Processing, CISP 2010 | Year: 2010

Image interpolation is a technique of producing a high-resolution image from its low-resolution counterpart, which is often required in many image processing tasks. In this paper, we propose an edge-directed bicubic convolution (BC) interpolation. The proposed method can well adapt to the varying edge structures of images. The experimental results show that it reduces common artifacts such as blurring, blocking and ringing etc. and significantly outperforms some existing interpolation methods (including BC interpolation) in terms of both subjective and objective measures. ©2010 IEEE. Source


Wang Z.-G.,North China Electrical Power University
Communications in Theoretical Physics | Year: 2013

In this article, we study the light-flavor scalar and axial-vector diquark states in the vacuum and in the nuclear matter using the QCD sum rules in a systematic way, and make reasonable predictions for their masses in the vacuum and in the nuclear matter. © 2013 Chinese Physical Society and IOP Publishing Ltd. Source


Luo Z.,North China Electrical Power University
Advances in Applied Mathematics and Mechanics | Year: 2014

A semi-discrete scheme about time for the non-stationary Navier-Stokes equations is presented firstly, then a newfully discrete finite volume element (FVE) formulation based on macroelement is directly established fromthe semi-discrete scheme about time. And the error estimates for the fully discrete FVE solutions are derived by means of the technique of the standard finite element method. It is shown by numerical experiments that the numerical results are consistent with theoretical conclusions. Moreover, it is shown that the FVE method is feasible and efficient for finding the numerical solutions of the non-stationary Navier-Stokes equations and it is one of the most effective numerical methods among the FVE formulation, the finite element formulation, and the finite difference scheme. © 2014 Global Science Press. Source


Network skeleton reconfiguration is an important task during power system restoration after blackout. The uncertainty of the restoration time and the restoration successful rate during the network skeleton reconfiguration are considered in the paper. The restoration time of transmission lines and transformers, units’ startup time limit and the restoration successful rate are selected as trapezoidal fuzzy variables. The optimal network skeleton reconfiguration model after power system blackout is constructed based on a fuzzy chance-constrained programming. An optimization algorithm combining fuzzy simulation with PSO is implemented to solve the optimal model. The optimal network skeleton with higher reliability and the restoration sequence which meet a certain confidence level are optimized by the proposed method. The restoration sequence can ensure the restoration as quickly as possible. The effectiveness of the proposed method is validated by Matlab with IEEE 30 bus system test. © 2015, Strojarski Facultet. All rights reserved. Source


Yao X.,Beihang University | Yao X.,North China Electrical Power University | Guo L.,Beihang University
Automatica | Year: 2013

This paper is concerned with the problems of composite disturbance- observer-based control (DOBC) and H∞ control for Markovian jump systems with nonlinearity and multiple disturbances. Our aim is to design a disturbance observer to estimate the disturbance generated by an exogenous system, then construct the control scheme by integrating the output of the disturbance observer with state-feedback control law, such that, the closed-loop system can be guaranteed to be stochastically stable, and different types of disturbances can be attenuated and rejected. By constructing a proper stochastic Lyapunov-Krasovskii functional, sufficient conditions for the existence of the desired observer and the state-feedback controller are established in terms of linear matrix inequalities (LMIs), which can be readily solved by standard numerical software. Finally, a numerical example is provided to show the effectiveness of the proposed approaches. © 2013 Elsevier Ltd. All rights reserved. Source


Li H.,North China Electrical Power University
Communications in Computer and Information Science | Year: 2011

The focus of the study is on the assessment of readability for prevailing America and Chinese English textbooks with the measurement software and systems. The result indicated college reading textbooks produced by Chinese publishers seemed to vary in level, with some texts above the reading ability of most college students. Then simplification strategies used to make Chinese EFL reading texts more accessible are compared to those used in American reading texts. The substantial findings for the study are of great value to English textbook compilation and English language teaching. © 2011 Springer-Verlag Berlin Heidelberg. Source


Lin Q.G.,Environment Canada | Huang G.H.,University of Regina | Huang G.H.,North China Electrical Power University
Energy | Year: 2010

Energy management systems are highly complicated with greenhouse-gas emission reduction issues and a variety of social, economic, political, environmental and technical factors. To address such complexities, municipal energy systems planning models are desired as they can take account of these factors and their interactions within municipal energy management systems. This research is to develop an interval-parameter two-stage stochastic municipal energy systems planning model (ITS-MEM) for supporting decisions of energy systems planning and GHG (greenhouse gases) emission management at a municipal level. ITS-MEM is then applied to a case study. The results indicated that the developed model was capable of supporting municipal energy systems planning and environmental management under uncertainty. Solutions of ITS-MEM would provide an effective linkage between the pre-regulated environmental policies (GHG-emission reduction targets) and the associated economic implications (GHG-emission credit trading). © 2010 Elsevier Ltd. All rights reserved. Source


Teng J.,North China Electrical Power University | Snoussi H.,University of Technology of Troyes | Richard C.,University of Nice Sophia Antipolis
IEEE Transactions on Mobile Computing | Year: 2010

The prime motivation of our work is to balance the inherent trade-off between the resource consumption and the accuracy of the target tracking in wireless sensor networks. Toward this objective, the study goes through three phases. First, a cluster-based scheme is exploited. At every sampling instant, only one cluster of sensors that located in the proximity of the target is activated, whereas the other sensors are inactive. To activate the most appropriate cluster, we propose a nonmyopic rule, which is based on not only the target state prediction but also its future tendency. Second, the variational filtering algorithm is capable of precise tracking even in the highly nonlinear case. Furthermore, since the measurement incorporation and the approximation of the filtering distribution are jointly performed by variational calculus, an effective and lossless compression is achieved. The intercluster information exchange is thus reduced to one single Gaussian statistic, dramatically cutting down the resource consumption. Third, a binary proximity observation model is employed by the activated slave sensors to reduce the energy consumption and to minimize the intracluster communication. Finally, the effectiveness of the proposed approach is evaluated and compared with the state-of-the-art algorithms in terms of tracking accuracy, internode communication, and computation complexity. © 2006 IEEE. Source


Wang X.,Jilin University | Li Y.,North China Electrical Power University
Journal of Hazardous Materials | Year: 2011

Clay minerals in surficial sediment samples, collected from the Songhua River in China, were separated via sedimentation after removal of Fe/Mn oxides and organic materials; Cu and Zn adsorption onto the sediment components was then evaluated. Clay minerals were examined via X-ray diffraction and scanning electron microscopy. Clay minerals were found to consist mainly of illite, kaolinite, chlorite and an illite/smectite mixed layer. Non-clay minerals were dominated by quartz and orthoclase. The retention of Cu and Zn by clay minerals was 1.6 and 2.5 times, respectively, greater than that of the whole, untreated surficial sediment. Compared to the other critical components in sediments related to metal sorption (Mn oxides, Fe oxides and organic materials), the adsorption capacity of clay minerals was found to be relatively lower on a unit mass basis. These data suggest that, although clay minerals may be important in the adsorption of heavy metals to aquatic sediments, their role is less significant than Fe/Mn oxides and organic materials. © 2011 Elsevier B.V. Source


Chen J.,North China Electrical Power University
3rd International Symposium on Intelligent Information Technology and Security Informatics, IITSI 2010 | Year: 2010

The comprehensive evaluations of complex systems are worthy of study deeply, and the subjectivity and fuzziness of evaluation objects further increase complexity of the evaluation systems. To attain the final comprehensive evaluation result in increasing evaluation reliability, a flexible fuzzy comprehensive evaluation method is proposed, which is a top-down method for the multi-layer evaluation index system and uses the tunable fuzzy compound operators to attain the final evaluation result. At first, a rough evaluation plan is generated to reach the final goal. Then, the plan is decomposed to many sub-goals which are submitted to the next lower layer of the index hierarchy and the more refined evaluation plans to reach these sub-goals are determined. As the evaluation process moves from high layer to low layer, the information granularity to the comprehensive evaluation becomes finer. This process of successive refinement continues until the final evaluation result is obtained. If only possible, the evaluation work will be finished depending on the part of index hierarchy, and it is not necessary to do the calculations for all the indexes. Finally, the practical applications indicate the effectiveness of the proposed method. © 2010 IEEE. Source


Liu Z.,North China Electrical Power University
Journal of Computational Information Systems | Year: 2010

The wind energy resources reserves occupies the world leader in China, the wind power generation technology is relatively mature, has the large-scale commercial development condition, the cost to be lower relatively in each kind of the electric power new energy. The wind power industry has the huge superiority and development potential extremely. Compared with the rich wind energy resources, the wind power industry was also at the weak position currently. To evaluate the wind power industry comprehensive competitiveness (WPICC) scientifically and accurately, this paper overcomes the shortcoming of tradition linear WPICC evaluation method, proposes a evaluation method which integrates the improved artificial neural network (ANN) algorithm and the data envelopment analysis (DEA) model, which not only can display the DEA's advantage of not involving the parameter estimation and weight determination, cause the evaluation results not influenced by the different index dimension, but exert the ANN's unique advantages and overcome the difficulty of seeking the high grade training sample data. The simulation results show that the hybrid model is simple and feasible, and further improve the evaluating efficiency and accuracy. © 2010 Binary Information Press. Source


Guo D.Z.,Xian Jiaotong University | Sun D.L.,North China Electrical Power University | Li Z.Y.,Xian Jiaotong University | Tao W.Q.,Xian Jiaotong University
Numerical Heat Transfer; Part A: Applications | Year: 2011

This article presents a numerical method directed towards the simulation of flows with changes of phase. The volume-of-fluid level set (VOSET) method, which is a new interface capturing method and combines the advantages of both volume-of-fluid (VOF) and level set methods, is used for interface tracking. A difficulty occurs for the problems studied here: the discontinuous velocity field due to the difference between mass-weighted velocity and volume weighted velocity caused by the phase change at the interface. In this article, some special treatment is made to overcome this difficulty. The VOSET method and the developed treatment for the difference between mass-weighted and volume-weighted velocities are adopted to simulate a one-dimensional Stefan problem, two-dimensional horizontal film boiling, and horizontal film boiling of water at near critical pressure. The predicted results in both Nusselt number and flow patterns are agreeable with experimental results available in the literature. Copyright © Taylor & Francis Group, LLC. Source


Xue Y.,University of New Brunswick | Xue Y.,Southwest Petroleum University | Xiao H.,University of New Brunswick | Zhang Y.,North China Electrical Power University
International Journal of Molecular Sciences | Year: 2015

Polymeric materials containing quaternary ammonium and/or phosphonium salts have been extensively studied and applied to a variety of antimicrobial-relevant areas. With various architectures, polymeric quaternary ammonium/phosphonium salts were prepared using different approaches, exhibiting different antimicrobial activities and potential applications. This review focuses on the state of the art of antimicrobial polymers with quaternary ammonium/phosphonium salts. In particular, it discusses the structure and synthesis method, mechanisms of antimicrobial action, and the comparison of antimicrobial performance between these two kinds of polymers. © 2015 by the authors; licensee MDPI, Basel, Switzerland. Source


Tan W.,North China Electrical Power University
Energy Conversion and Management | Year: 2011

Decentralized load frequency control (LFC) for multi-area power systems is studied in this paper. A method to analyze the stability of a multi-area power system under a decentralized LFC is derived by accounting the inherent structure of the multi-area power system. The method separates the local transfer matrix from the tie-line power flow network, and the impacts of the tie-line power flow network and the local load frequency controllers on the power system can be easily checked. This result makes it possible to tune the local LFC controller for each area by first ignoring the tie-line power flow network. Decentralized LFC tuning on a three-area and a four-area power system shows that the proposed method is easy to apply for multi-area power systems and good damping performance can be achieved. © 2010 Elsevier Ltd. All rights reserved. Source


Chen J.,North China Electrical Power University
3rd International Symposium on Intelligent Information Technology and Security Informatics, IITSI 2010 | Year: 2010

As Grid technologies evolve quickly on Internet, research related to resource scheduling faces new opportunities and challenges. These new technologies, ideas and approaches provide a new environment for researching and developing the economy-based resource scheduling system. Aiming at the hierarchical Grid model, following utility optimization thinking, while an universal flexible utility function is provided for addressing the Grid users' QoS requirements of deadline and budget, this paper proposes a new Grid resource scheduling algorithm, which can not only increase the utilization of resources and system throughput, but also realize cost-time optimization between resource providers and users within Grid systems. On the basis of having described the different functional parts of the proposed algorithm, two kinds of simulative experiments about completion time and cost of tasks are conducted. Finally, the experiment results show that the proposed algorithm is effective. © 2010 IEEE. Source


Wang Z.-G.,North China Electrical Power University
Journal of High Energy Physics | Year: 2013

In this article, we recalculate the contributions of all vacuum condensates up to dimension-6, in particular the one-loop corrections to the quark condensates αs(q̄q) and partial one-loop corrections to the four-quark condensates α2s(q̄q)2, in the operator product expansion. Then we study the masses and decay constants of the heavy pseudoscalar mesons D, Ds, B and Bs using the QCD sum rules with two choices: I we choose the MS masses by setting m = m(μ) and take perturbative corrections up to the order 0(αs); II we choose the pole masses m, take perturbative corrections up to the order 0(α2 s) and set the energy-scale to be the heavy quark pole mass μ = mQ. In the case of I, the predictions fD = (208 ± 11)MeV and fB = (189 ± 15) MeV are consistent with the experimental data within uncertainties, while the prediction f Ds = (241 ± 12) MeV is below the lower bound of the experimental data fDs = (260.0 ± 5.4) MeV. In the case of II, the predictions fD = (211±14) MeV, fB = (190±17) MeV, fDs = (258±13) MeV and f Ds/fD = 1.22±0.08 are all in excellent agreements with the experimental data within uncertainties. © SISSA 2013. Source


Wang Z.-G.,North China Electrical Power University
European Physical Journal C | Year: 2016

In this article, we construct the axialvector-diquark–axialvector-antidiquark type tensor current to interpolate both the vector- and the axialvector-tetraquark states, then calculate the contributions of the vacuum condensates up to dimension 10 in the operator product expansion, and we obtain the QCD sum rules for both the vector- and the axialvector-tetraquark states. The numerical results support assigning the Zc(4020 / 4025) to be the JP C= 1 + -diquark–antidiquark type tetraquark state, and assigning the Y(4660) to be the JP C= 1 - -diquark–antidiquark type tetraquark state. Furthermore, we take the Y(4260) and Y(4360) as the mixed charmonium–tetraquark states, and we construct the two-quark–tetraquark type tensor currents to study the masses and pole residues. The numerical results support assigning the Y(4260) and Y(4360) to be the mixed charmonium–tetraquark states. © 2016, The Author(s). Source


Yao X.,North China Electrical Power University | Yao X.,University of Western Sydney | Wu L.,Harbin Institute of Technology | Zheng W.X.,University of Western Sydney
International Journal of Robust and Nonlinear Control | Year: 2013

This paper investigates the problem of quantized ℋ∞ filtering for a class of discrete-time linear parameter-varying systems with Markovian switching under data missing. The measured output of the plant is quantized by a logarithmic mode-independent quantizer. The data missing phenomenon is modeled by a stochastic variable. The purpose of the problem addressed is to design a full-order ℋ∞ filter such that the filtering error dynamics is stochastically stable and the prescribed noise attenuation level in the ℋ∞ sense can be achieved. Sufficient conditions are derived for the existence of such filters in terms of parameterized linear matrix inequalities. Then the corresponding filter synthesis problem is transformed into a convex optimization problem that can be efficiently solved by using standard software packages. A simulation example is utilized to demonstrate the usefulness of the developed theoretical results. Copyright © 2011 John Wiley & Sons, Ltd. Source


Wang Y.,North China Electrical Power University
Journal of Intelligent and Fuzzy Systems | Year: 2015

Traveling salesman problem (TSP) is a typical of combinatorial optimization problem. Its objective is to find an optimal Hamiltonian circuit (OHC). It has been proven to be NP-complete. The frequency graph for TSP has been introduced in a previous paper. This article is the progressive research of the frequency graph for TSP. The probability of the edges is computed based on a frequency graph which is computed with a set of local optimal Hamiltonian paths. The bigger the probability of an edge, the more possible the edge belongs to the OHC. The value span of the probability of an edge in the OHC is derived and used to select the candidate edges to form the OHC. A variable m is noted as the number of the local optimal Hamiltonian paths with each edge. These optimal Hamiltonian paths are used to compute a frequency graph. The probability function of the edges in the OHC is derived and it is a geometric progression according to variable m. The general term formula of the probability of the edges in the OHC is simulated based on the experiments with the Euclidean TSP instances. It is used to evaluate the rightness of the generated OHC composed of the candidate edges. © 2015 - IOS Press and the authors. All rights reserved. Source


Gu C.,University of Bath | Li F.,University of Bath | He Y.,North China Electrical Power University
IEEE Transactions on Power Systems | Year: 2012

This paper improves the existing long-run incremental cost (LRIC) pricing which forms the basis for one of the two common charging methodologies that are to be adopted by the U.K.'s seven distribution network operators for charging customers connected at extra-high voltage (EHV) distribution networks from April 2012. The original model is expected to respect network security while evaluating charges based on the extent of the use of the network, which it achieves by reshaping components' capacity with their contingency factors into maximum available capacity. It then identifies the impact of a nodal injection on each component under normal conditions within the threshold of the maximum available capacity. The problem with the LRIC is that it assumes that the impact from a nodal injection is the same under both normal and contingent states, thus underestimating its impact under contingencies. In this paper, the original LRIC model is improved by considering the respective impacts from users under both normal and contingent conditions. The improved model runs incremental contingency flow analysis to determine how they affect components' flows under contingencies. In order to illustrate the differences in the reinforcement horizons, a comparison of the original and enhanced approaches is carried out on three basic distribution networks: single-branch, parallel-branch, and meshed. The new approach chooses the smaller horizons between those from normal and contingent situations to derive charges. Sensitivity analysis is introduced to reduce the calculation burden in determining components' flowincrements due to injections. The improved approach is finally testified and compared with the original model on a threebusbar system and a practical system. © 2006 IEEE. Source


Wang X.,Malardalen University | Wang X.,North China Electrical Power University | Nordlander E.,Malardalen University | Thorin E.,Malardalen University | And 2 more authors.
Applied Energy | Year: 2013

Microalgae are considered as potential sources for biodiesel production due to the higher growth rate than terrestrial plants. However, the large-scale application of algal biodiesel would be limited by the downstream cost of lipid extraction and the availability of water, CO2 and nutrients. A possible solution is to integrate algae cultivation with existing biogas plant, where algae can be cultivated using the discharges of CO2 and digestate as nutrient input, and then the attained biomass can be converted directly to biomethane by existing infrastructures. This integrated system is investigated and evaluated in this study. Algae are cultivated in a photobioreactor in a greenhouse, and two cultivation options (greenhouse with and without heating) are included. Life cycle assessment of the system was conducted, showing that algal biomethane production without greenhouse heating would have a net energy ratio of 1.54, which is slightly lower than that (1.78) of biomethane from ley crop. However, land requirement of the latter is approximately 68 times that of the former, because the area productivity of algae could reach at about 400t/ha (dry basis) in half a year, while the annual productivity of ley crop is only about 5.8t/ha. For the case of Växtkraft biogas plant in Västerås, Sweden, the integrated system has the potential to increase the annual biomethane output by 9.4%. This new process is very simple, which might have potential for scale-up and commercial application of algal bioenergy. © 2013 Elsevier Ltd. Source


Wang Z.-G.,North China Electrical Power University
European Physical Journal C | Year: 2016

In this article, we construct the diquark–diquark–antiquark type interpolating currents, and we study the masses and pole residues of the (Formula presented.) and (Formula presented.) hidden charm pentaquark states in detail with the QCD sum rules by calculating the contributions of the vacuum condensates up to dimension-10 in the operator product expansion. In the calculations, we use the formula (Formula presented.) to determine the energy scales of the QCD spectral densities. The present predictions favor assigning (Formula presented.) and (Formula presented.) to be the (Formula presented.) and (Formula presented.) pentaquark states, respectively. © 2016, The Author(s). Source


Wang Z.-G.,North China Electrical Power University | Huang T.,CAS Institute of High Energy Physics
European Physical Journal C | Year: 2016

In this article, we present the scalar-diquark–scalar-diquark–antiquark type and scalar-diquark–axialvector-diquark–antiquark type pentaquark configurations in the diquark model, and study the masses and pole residues of the (Formula Presented) hidden-charm pentaquark states in detail with the QCD sum rules by extending our previous work on the (Formula Presented) and (Formula Presented) hidden-charm pentaquark states. We calculate the contributions of the vacuum condensates up to dimension-10 in the operator product expansion by constructing both the scalar-diquark–scalar-diquark–antiquark type and the scalar-diquark–axialvector-diquark–antiquark type interpolating currents. The present predictions of the masses can be confronted to the LHCb experimental data in the future. © 2016, The Author(s). Source


Zhu Y.,Communication University of China | Shi Y.,North China Electrical Power University
IEEE Signal Processing Letters | Year: 2013

We use a small positive parameter to change the total-variation function for unconstrained MR image reconstruction to a strictly convex perturbed function. Bregman iteration is applied to solve the modified total-variation MR image (TVMRI) reconstruction problem. A lagged diffusivity fixed-point algorithm is applied to solve the minimization problem in the Bregman iteration. We use the periodic boundary condition and a Fourier transform to accelerate TVMRI reconstruction. Real MR images are used to test the approach in numerical experiments. The experimental results demonstrate that the proposed method is very efficient for TVMRI reconstruction. © 1994-2012 IEEE. Source


Jiao R.,North China Electrical Power University
ICCMS 2010 - 2010 International Conference on Computer Modeling and Simulation | Year: 2010

JPEG2000 is the international image coding standard. AVC/H.264 is the latest video coding standard and its I-Frame coding can also be used for image coding. In this paper we compare the coding performance of JPEG2000 and AVC I-Frame coding. First, we discuss the basic techniques of their coding schemes and encoder parameter settings. Second, compressions are performed on images with different resolution and texture complexity. Finally we discuss the experimental results. In this study, we have not considered computation complexity and scalability, as well as other JPEG2000 features. © 2010 IEEE. Source


Luo Z.,North China Electrical Power University
Acta Mathematica Scientia | Year: 2016

In this study, we employ mixed finite element (MFE) method, two local Gauss integrals, and parameter-free to establish a stabilized MFE formulation for the non-stationary incompressible Boussinesq equations. We also provide the theoretical analysis of the existence, uniqueness, stability, and convergence of the stabilized MFE solutions for the stabilized MFE formulation. © 2016 Wuhan Institute of Physics and Mathematics. Source


Huang X.-C.,North China Electrical Power University
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2011

The large scale penetration of Distributed Generation (DG) within distribution networks will significantly impact on the operation of future distribution systems. It will also be possible to take advantage of DG with regard to the service restoration in distribution networks. For example, when there is not enough capacity to restore the entire out-of-service area, the network operator can implement intentional island operation with the support of black-start DG to keep the electricity supply of important users. Furthermore, from the viewpoint of making full use of renewable energy sources, the network operator is required to ensure the interconnection of the renewable units that are installed in the out-of-service area. Based on these assumptions, this paper establishes a new optimization model for the solution of the service restoration problem of power grid with DG and applies NSGA-II to solve the model. Numerical analysis verifies the feasibility and correctness of the model. Source


Zhang Y.,University of Regina | Huang G.,North China Electrical Power University | Huang G.,University of Regina
Journal of the Air and Waste Management Association | Year: 2010

In this study, a fuzzy robust credibility-constrained programming (FRCCP) is developed and applied to the planning for waste management systems. It incorporates the concepts of credibility-based chance-constrained programming and robust programming within an optimization framework. The developed method can reflect uncertainties presented as possibility-density by fuzzy-membership functions. Fuzzy credibility constraints are transformed to the crisp equivalents with different credibility levels, and ordinary fuzzy inclusion constraints are determined by their robust deterministic constraints by setting α-cut levels. The FRCCP method can provide different system costs under different credibility levels (λ). From the results of sensitivity analyses, the operation cost of the landfill is a critical parameter. For the management, any factors that would induce cost fluctuation during landfilling operation would deserve serious observation and analysis. By FRCCP, useful solutions can be obtained to provide decision-making support for long-term planning of solid waste management systems. It could be further enhanced through incorporating methods of inexact analysis into its framework. It can also be applied to other environmental management problems. Copyright 2010 Air & Waste Management Association. Source


He Q.,Harbin Institute of Technology | Wu C.,Harbin Institute of Technology | Chen D.,North China Electrical Power University | Zhao S.,Hebei University
Knowledge-Based Systems | Year: 2011

Fuzzy rough set is a generalization of crisp rough set to deal with data sets with real value attributes. A primary use of fuzzy rough set theory is to perform attribute reduction for decision systems with numerical conditional attribute values and crisp (symbolic) decision attributes. In this paper we define inconsistent fuzzy decision system and their reductions, and develop discernibility matrix-based algorithms to find reducts. Finally, two heuristic algorithms are developed and comparison study is provided with the existing algorithms of attribute reduction with fuzzy rough sets. The proposed method in this paper can deal with decision systems with numerical conditional attribute values and fuzzy decision attributes rather than crisp ones. Experimental results imply that our algorithm of attribute reduction with general fuzzy rough sets is feasible and valid. © 2010 Elsevier B.V. All rights reserved. Source


Zhang X.,Xian Jiaotong University | Mei C.,Xian Jiaotong University | Chen D.,North China Electrical Power University | Li J.,Kunming University of Science and Technology
Knowledge-Based Systems | Year: 2013

Rule acquisition is one of the most concerned issues in the study of decision systems including covering decision systems. Usually, a covering decision system is inconsistent, which can lead to the result that some of the rules derived from the system are not certain but possible rules. Considering the fact that, in addition to the certain rules, the possible rules with high confidence are also commonly used in practice for making decision, and the compact rules without redundant conditional attributes can conveniently be used by a decision maker, we propose in this study a rule confidence preserving attribute reduction approach in order to extract from a covering decision system both the compact certain rules and the compact possible rules with their confidence degree being not less than a pre-specified threshold value. Furthermore, a combinatorial optimization algorithm is formulated to compute all the reducts. Some numerical experiments are further conducted to evaluate the performance of the proposed reduction method. © 2013 Elsevier B.V. All rights reserved. Source


Fu D.,North China Electrical Power University
Science China Chemistry | Year: 2011

An equation of state (EOS) applicable for the interfacial properties of CO 2-methanol and CO 2-ethanol mixtures was established by combining the cross-association EOS and the density gradient theory (DGT). The correlated surface tensions of CO 2-ethanol mixtures agreed well with the experimental data. The results illustrated the temperature and pressure dependence of the cross-association between CO 2 and alcohol hydroxyls in the whole vapor-liquid surface, and the influence of the cross-association on the calculation of the surface tensions of binary mixtures. © Science China Press and Springer-Verlag Berlin Heidelberg 2011. Source


In this paper, improving control performance of a networked control system by reducing DTD in a different perspective was investigated. Two different network architectures for system implementation were presented. Analysis and improvement dealing with DTD for the experimental control system were expounded. Effects of control scheme configuration on DTD in the form of FB were investigated and corresponding improvements by reallocation of FB and re-arrangement of schedule table are proposed. Issues of DTD in hybrid network were investigated and corresponding approaches to improve performance including (1) reducing DTD in PLC or PAC by way of IEC61499 and (2) cascade Smith predictive control with BPNN-based identification were proposed and investigated. Control effects under the proposed methodologies were also given. Experimental and field practices validated these methodologies. © 2014 ISA. Source


Jing L.,Memorial University of Newfoundland | Chen B.,North China Electrical Power University | Chen B.,Memorial University of Newfoundland
Journal of Environmental Informatics | Year: 2011

Recently, investigation and conservation of subarctic wetlands has been recognized as an attractive route. To gain insight of the interactions between hydrology and atmosphere of the second largest wetland in Canada - the Hudson Bay Lowlands (HBL), the semi-distributed land use-based runoff process (SLURP) hydrological model was applied to a typical subarctic wetland - the Deer River watershed over a 20-year period (1978-1997). Sensitivity analysis, calibration and validation of the model identified a number of distinguishable hydrological features of subarctic wetlands as well as model deficiencies. Snowmelt was the major source of water recharge in subarctic wetlands and constituted approximately half of the average annual runoff in the Deer River watershed. The peaks of the simulated spring runoff were 34% lower than the observed ones in average which could be attributed to the effects of shallow permafrost that impeded the infiltration of melt water. Runoff of rainfall water during the summer season occurred only during storms due to canopy interception, depression storage, soil porosity, impermeable permafrost, and intensive evapotranspiration. A lag of 2-8 days between the peaks of streamflow and rainfall was observed through both field investigation and modeling results. The numerous seasonally connected ponds/lakes stretching over the middle and lower reach of the watershed behaved as buffers and significantly prolonged the concentration time in summer and fall. The findings will help build a scientific basis for advancing the knowledge of the hydrologic cycle and impacts of climatic changes on sub-arctic wetlands. © 2011 ISEIS All rights reserved. Source


Degang C.,North China Electrical Power University | Suyun Z.,Hebei University
Fuzzy Sets and Systems | Year: 2010

One important and valuable topic in fuzzy rough sets is attribute reduction of decision system. The existing attribute reductions with fuzzy rough sets consider all decision classes together and cannot identify key conditional attributes explicitly for special decision class. In this paper we introduce the concept of local reduction with fuzzy rough sets for decision system. The local reduction can identify key conditional attribute and offer a minimal description for every single decision class. Approach of discernibility matrix is employed to investigate the structure of local reduction. At last, several experiments are performed to show that the idea of local reduction is feasible and valid. © 2009 Elsevier B.V. All rights reserved. Source


Wang C.,Bohai University | Chen D.,North China Electrical Power University | Sun B.,Harbin Institute of Technology | Hu Q.,Harbin Institute of Technology
Information Sciences | Year: 2012

Communication between information systems is considered as an important issue in granular computing. The concept of homomorphism is an effective mathematical tool to study information exchange between information systems. This paper provides a study on some basic properties of covering information systems and decision systems under homomorphisms. First, we define consistent functions related to coverings and covering mappings between two universes, and study their properties. Then, we introduce the notions of homomorphisms of covering information systems and point out that a homomorphism is a special covering mapping between information systems. Furthermore, we investigate some important properties of homomorphisms in covering information systems and decision systems. It is proved that some basic properties of original systems, such as set approximations, attribute reductions, can be reserved under the condition of homomorphisms in both covering information systems and covering decision systems. © 2012 Elsevier Inc. All rights reserved. Source


Zhang Q.,North China Electrical Power University
2010 International Conference on Machine Vision and Human-Machine Interface, MVHI 2010 | Year: 2010

This paper put forward a new method of the SVM and wavelet neural network model for mid-long term load forecasting. The neural call function is basis of nonlinear wavelets. We overcome the shortcoming of single train set of SVM. It can be seen from the example this method can improve effectively the forecast accuracy and speed. The forecast model was tested and the result showed that it was an effective way to forecast mid-long term electric load. © 2010 IEEE. Source


Yabin L.,North China Electrical Power University
Journal of Convergence Information Technology | Year: 2010

With China's rapid economic development, electricity supply is relatively shortage, and the contradiction of power coal supply and demand is prominent. In this context, using WITNESS logistics software platforms, this paper establishes a simulation model about a power coal ocean shipping logistics system of a transshipment port as the center, focusing on how to make full use of the existing resources of a transshipment port for studying transshipment port operating mechanism through the running simulation model and optimal design of power coal logistics cost in order to guarantee security and stability of power coal-fired supply and maximize logistics system economic benefits. Source


Wang Y.,North China Electrical Power University | Liu J.,Beihang University
International Journal of Advanced Manufacturing Technology | Year: 2013

Assembly sequence planning is a typical of NP-complete problem which will spend a large amount of computation time or disk memory once the assembly becomes complex. The complex product or assembly is composed of many parts and the number of assembly relationships between them is numerous. To decrease the difficulty of assembly sequence planning of complex products, the subassembly identification methods are focused on. It aims to decompose a complex assembly into a limitative number of subassemblies. Each subassembly contains a relatively smaller number of parts and the assembly sequence planning tasks of them can be handled efficiently. The subassembly identification methods for assembly sequence planning are summarized with respect to assembly constraints. The assembly constraints including the topological, geometrical, and process constraints are considered and merged into the assembly models for subassembly identification. The assembly models are generally represented as directed or undirected assembly diagrams including these considered constraints. It is generally taken as the input information to generate appropriate subassemblies complying with the requirements. The graph theories and graph search algorithms, integer programming methods and the emerging techniques, such as the knowledge-based methods, the intelligent algorithms and the virtual technology, etc. are advocated to resolve the subassembly identification problem with respect to the assembly models. The hierarchical assembly tree is widely used to represent the results of subassembly identification. These useful methods are not only used to subassembly identification for assembly sequence planning, but also successfully referred to by product disassembly. © 2013 Springer-Verlag London. Source


Wang Z.-G.,North China Electrical Power University
European Physical Journal C | Year: 2015

In this article, we study the charmed baryon states Λc(2625) and Ξc(2815) with the spin-parity 3/2- by subtracting the contributions from the corresponding charmed baryon states with the spin-parity 3/2+ using the QCD sum rules, and suggest a formula (Formula presented.) with the effective mass Mc = 1.8GeV to determine the energy scales of the QCD spectral densities, and make reasonable predictions for the masses and pole residues. The numerical results indicate that the Λc(2625) and Ξc(2815) have at least two remarkable under-structures. © 2015, The Author(s). Source


Bao H.,North China Electrical Power University
Journal of Communications | Year: 2016

For positioning with Global Navigation Satellite System (GNSS) in urban canyon area, besides the weak signal power, the satellite signal may also be frequently sheltered and no power can be received. It is a great challenge for the GNSS receiver to keep positioning continuously. If the tracking loop in GNSS receivers can recover locking the signal soon after the signal appears again, it will help a lot for the improvement of the positioning continuity since the acquisition stage is omitted. However, when signal is shortly interrupted, the local frequency estimation error increases during the period without signal. The tradition Phase Lock Loop (PLL) cannot directly lock the signal again. Hence, we propose the Delay Lock Loop (DLL) assisted PLL. In the method, when the signal is detected to be recovered, the DLL is firstly started up. Once the DLL is locked, the code phase measurements are extracted from the DLL to estimate the carrier frequency. Afterwards, it is utilized to correct the initial frequency of the PLL. By making use of the DLL’s insensitivity to the frequency variation, it will help the PLL quickly and accurately lock the signal when the signal is shortly sheltered. The theoretical analysis results inform that the accuracy of the carrier frequency estimated from the DLL is sufficient for the PLL to recover locking. The simulation results show that the proposed DLL assisted PLL can recover tracking immediately after the signal is shortly interrupted. And it will help a lot for the positioning availability of GNSS receiver. © 2016 Journal of Communications. Source


Duan W.,North China Electrical Power University | Joshi S.,Concordia University at Montreal
Engineering Failure Analysis | Year: 2011

Steel tie rods are very important load-carrying components in applications where high levels of pre-stresses are required. The bearing capacity of a steel tie rod is determined not only by the strength of the rod body, but also by the strength of the threaded connection that resists force. Analysis of the strength of the threaded connection and determining the optimal number of turns of thread engagement is critical to ensure structural safety. This paper reports the results of full-scale tensile rupture experiments on two categories of large-scale steel tie rods provided by China JULI Corporation: (i) LG75-00 steel tie rods with triangle threaded connection, and (ii) LG100-00 steel tie rods with trapezoidal threaded connection. The full-scale tensile rupture experiments were carried out to test the maximum allowable axial working load under different numbers of turns of engaged threads. The results of these experiments suggest strong guidelines on the minimum number of turns of thread engagement for preventing the failure of thread teeth of steel tie rods in practical shear and bending applications. © 2011 Elsevier Ltd. Source


Wang Z.-G.,North China Electrical Power University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2010

In this article, we study the vertices ΩQ*ΩQ with the light-cone QCD sum rules, then assume the vector meson dominance of the intermediate (1020), and calculate the radiative decays Ω Q*→ΩQγ. © 2010 The American Physical Society. Source


Miao Q.,KTH Royal Institute of Technology | Miao Q.,Shandong Normal University | Liu J.-C.,North China Electrical Power University | Agren H.,KTH Royal Institute of Technology | And 2 more authors.
Physical Review Letters | Year: 2012

X-ray lasing is predicted to ensue when molecules are pumped into dissociative core-excited states by a free-electron-laser pulse. The lasing is due to the population inversion created in the neutral dissociation product, and the process features self-trapping of the x-ray pulse at the gain ridge. Simulations performed for the HCl molecule pumped at the 2p1/2→ 6σ resonance demonstrate that the scheme can be used to create ultrashort coherent x-ray pulses. © 2012 American Physical Society. Source


Hu E.,University of Adelaide | Yang Y.,North China Electrical Power University | Nishimura A.,Mie University | Yilmaz F.,Deakin University | Kouzani A.,Deakin University
Applied Energy | Year: 2010

Fossil fuel based power generation is and will still be the back bone of our world economy, albeit such form of power generation significantly contributes to global CO2 emissions. Solar energy is a clean, environmental friendly energy source for power generation, however solar photovoltaic electricity generation is not practical for large commercial scales due to its cost and high-tech nature. Solar thermal is another way to use solar energy to generate power. Many attempts to establish solar (solo) thermal power stations have been practiced all over the world. Although there are some advantages in solo solar thermal power systems, the efficiencies and costs of these systems are not so attractive. Alternately by modifying, if possible, the existing coal-fired power stations to generate green sustainable power, a much more efficient means of power generation can be reached. This paper presents the concept of solar aided power generation in conventional coal-fired power stations, i.e., integrating solar (thermal) energy into conventional fossil fuelled power generation cycles (termed as solar aided thermal power). The solar aided power generation (SAPG) concept has technically been derived to use the strong points of the two technologies (traditional regenerative Rankine cycle with relatively higher efficiency and solar heating at relatively low temperature range). The SAPG does not only contribute to increase the efficiencies of the conventional power station and reduce its emission of the greenhouse gases, but also provides a better way to use solar heat to generate the power. This paper presents the advantages of the SAPG at conceptual level. © 2009 Published by Elsevier Ltd. All rights reserved. Source


Xu Z.,North China Electrical Power University
IEEE Transactions on Dielectrics and Electrical Insulation | Year: 2013

The dynamic contact angle is an important method to evaluate the hydrophobicity of material. To improve the accuracy of the dynamic contact angle measurement, the validity of the ellipse fitting algorithm in application of the dynamic contact angle measurement is analyzed. Water drop profiles with different volumes, contact angles and inclination angles are numerically generated based on the Laplace equation and finite difference method and at the same time, the ellipse fitting algorithm is used to calculate the dynamic contact angle. The results reveal that the significant error (/sp Gt/7°) in contact angle may be difficult to find. The dynamic contact angle error increases with the water drop volume. The ellipse fitting algorithm is not suitable for the case of too small or large contact angle. The critical water drop volumes corresponding to an error of 3° are given and the accuracy of the dynamic contact angle measurement is improved by using the volume. The results are verified by the experiments. © 1994-2012 IEEE. Source


Wang Z.-G.,North China Electrical Power University
Chinese Physics C | Year: 2010

In this article, we take the point of view that the light scalar meson a0(980) is a conventional q state, and calculate the coupling constants ga0ηπ0 and ga0η′π 0 with the light-cone QCD sum rules. The central value of the coupling constant ga0ηπ0 is consistent with that extracted from the radiative decay φ(1020) a0(980)γ ηπ0γ. The central value and lower bound of the decay width Γa0ηπ0 127-48 +84 MeV are compatible with the experimental data of the total decay width Γa0(980) (50-100) MeV from the Particle Data Group with a very model dependent estimation (the decay width can be much larger), while the upper bound is too large. We give a possible explanation for the discrepancy between the theoretical calculation and experimental data. © 2010 Chinese Physical Society and the Institute of High Energy Physics of the Chinese Academy of Sciences and the Institute of Modern Physics of the Chinese Academy of Sciences and IOP Publishing Ltd. Source


Wang K.C.,North China Electrical Power University
Advanced Materials Research | Year: 2014

An innovative new automatic approach for image retrieval is proposed to make duplex printing paper fragments retrieval, a simple mathematical model is built and the corresponding algorithm is designed. By extracting image information and utilizing the property that the front and the back sides can affect each other, if the matching process cannot continue, change to the other side to match continually. The results show that the arrangement that alternates between both sides can greatly improve the coherence and reduce the number of manual intervention. © (2014) Trans Tech Publications, Switzerland. Source


Zhang M.-H.,North China Electrical Power University
Chinese Physics B | Year: 2016

By performing the electronic structure computation of a Si atom, we compare two iteration algorithms of Broyden electron density mixing in the literature. One was proposed by Johnson and implemented in the well-known VASP code. The other was given by Eyert. We solve the Kohn-Sham equation by using a conventional outward/inward integration of the differential equation and then connect two parts of solutions at the classical turning points, which is different from the method of the matrix eigenvalue solution as used in the VASP code. Compared to Johnson's algorithm, the one proposed by Eyert needs fewer total iteration numbers. © 2016 Chinese Physical Society and IOP Publishing Ltd. Source


Fang F.,North China Electrical Power University
International Journal of Digital Content Technology and its Applications | Year: 2011

Wind power generation power system has been increased rapidly in recent years because of its environmental benefits, but the volatility of wind power brought some problems to power system operation, which affects Transmission Company's willingness to accept the wind power. Although the most serious conflicts influenced the development of wind power, but wind power is still widely applied. The grid prices don't need this fluctuation that influenced system operation. At present, quotas and accesses are widely applied in the provisions of the wind power. Now all wind power output should be accepted by grid, and a guide rate should be obtained. But with the increase of wind power penetration gridded, a more effective price adjustment should be set up for wind power on the consideration of the wind output uncertainties. Using the wind farms in different areas of China as the research object and taking the accounting cost analysis method to calculate the cost of wind power, wind power plants in different areas achieve the same return on investments with coal-fired power plants. These tariffs will receive a basic price of reference by power. The basic factor of wind power prices as the final price paid to the wind power plants is multiplied by a penalty which is a kind of innovation. The accuracy of punishment factor is related with the wind power output. In order to really pay wind power above the basic value demands the wind farm increasing their income, otherwise revenue will be reduced. To illustrate the problem, an example is given. Using this penalty factor will ultimately help stimulate wind farms improving the accuracy of wind power output, the system of stable operation and large wind power penetration ability, and finally promoting the sustainable development of commercial wind farms. Source


Ha Y.,Hebei University | Wang H.,North China Electrical Power University | Wang X.,Hebei University
Physics of Plasmas | Year: 2012

Asymmetric current pulses in dielectric-barrier atmospheric-pressure glow discharges are investigated by a self-consistent, one-dimensional fluid model. It is found that the glow mode and Townsend mode can coexist in the asymmetric discharge even though the gas gap is rather large. The reason for this phenomenon is that the residual space charge plays the role of anode and reduces the gap width, resulting in the formation of a Townsend discharge. © 2012 American Institute of Physics. Source


Wang Z.-G.,North China Electrical Power University
Physical Review C - Nuclear Physics | Year: 2012

In this article, we extend our previous work to study the Σ-type heavy baryons Σ c and Σ b in nuclear matter using QCD sum rules and obtain three coupled QCD sum rules for the masses MΣ Q*, vector self-energies Σ v, and pole residues λΣ Q* in nuclear matter. Then we take into account the effects of the unequal pole residues from different spinor structures, normalize the masses from QCD sum rules in vacuum to the experimental data, and obtain the mass shifts δMΣ c=- 123MeV and δMΣ b=-375MeV in the nuclear matter. © 2012 American Physical Society. Source


Wang C.,North China Electrical Power University | Jia L.,CANMET Energy | Tan Y.,CANMET Energy | Anthony E.J.,CANMET Energy
Energy and Fuels | Year: 2011

Oxy-fuel combustion of fossil fuel is one of the most promising methods for producing electricity, together with a stream of concentrated CO2 ready for sequestration. Oxy-fuel fluidized-bed combustion (FBC) can also use limestone as a sorbent for in situ capture of sulfur dioxide. However, although a limited number of studies have been performed on sulfation of limestone under oxy-fuel combustion conditions, there are still a number of important but unanswered questions. Here, the effect of water vapor on the sulfation of limestone was studied, because it has not been examined in detail in previous sulfation studies and past studies on direct sulfation of limestone in FBC either did not explore the influence of H2O or did so under unrealistic conditions for oxy-fuel FBC. The purpose of this study is to identify the effect of water vapor on direct sulfation of limestone under simulated oxy-fuel circulating FBC (CFBC) conditions. Direct sulfation of three limestones was conducted in a thermogravimetric analyzer (TGA) apparatus at 800 and 850 °C. The limestone particle sizes used were 75-125, 125-150, 150-250, and 250-425 μm, and tests were carried out in a synthetic flue gas atmosphere, consisting of 80% CO2, 15%, 10% or 0% H2O, 4% O2, 5000 ppm SO2, and balance N2. Water always improved limestone sulfation, especially at 850°C. In addition, for some limestones, such as Kelly Rock (Nova Scotia, Canada), when the reaction gas contained no H2O, the calcium conversion ratio was higher at 800°C than at 850°C. However, when the reaction gas contained 10% H 2O, the conversion ratio and the sulfation reaction rate were always higher at 850°C than at 800°C. Because coal-fired boiler flue gases always contain water vapor, the role played by H2O in the limestone sulfation reaction should always be considered in future studies. © 2011 American Chemical Society. Source


Wang Z.-G.,North China Electrical Power University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2011

In this article, we study the strong decays of the newly observed charmed mesons D(2550), D(2600), D(2750), and D(2760) with the heavy quark effective theory in the leading order approximation, and tentatively identify the (D(2550),D(2600)) as the 2S doublet (0-,1-) and the (D(2750),D(2760)) as the 1D doublet (2-,3-), respectively. The identification of the D(2750) and D(2760) as the same particle with JP=3- is disfavored. © 2011 American Physical Society. Source


Li Y.P.,North China Electrical Power University | Huang G.H.,University of Regina
International Journal of Energy Research | Year: 2013

Increased atmospheric CO2 concentration is widely being considered as the main driving factor that causes the phenomenon of global warming, due to the ever-boosting use of fossil fuels. In this study, a fuzzy-stochastic programming model with soft constraints (FSP-SC) is developed for electricity generation planning and greenhouse gas (GHG) abatement in an environment with imprecise and probabilistic information. The developed FSP-SC is applied to a case study of long-term planning of a regional electricity generation system, where integer programming technique is employed to facilitate dynamic analysis for capacity expansion within a multi-period context to satisfy increasing electricity demand. The results indicate different relaxation levels can lead to changed electricity generation options, capacity expansion schemes, system costs, and GHG emissions. Several sensitivity analyses are also conducted to demonstrate that relaxation of different constraints have different effects on system cost and GHG emission. Tradeoffs among system costs, resource availabilities, GHG emissions, and electricity-shortage risks can also be tackled with the relaxation levels for the objective and constraints. © 2012 John Wiley & Sons, Ltd. Source


Zhu H.,University of Regina | Huang G.H.,North China Electrical Power University | Huang G.H.,University of Regina
International Journal of Electrical Power and Energy Systems | Year: 2013

A dynamic stochastic fractional programming (DSFP) approach is developed for capacity-expansion planning of electric power systems under uncertainty. The traditional generation expansion planning focused on providing a sufficient energy supply at minimum cost. Different from using least-cost models, a more sustainable management approach is to maximize the ratio between renewable energy generation and system cost. The proposed DSFP method can solve such ratio optimization problems involving issues of capacity expansion and random information. It has advantages in balancing conflicting objectives, handling uncertainty expressed as probability distributions, and generating flexible capacity-expansion strategies under different risk levels. The method is applied to an expansion case study of municipal electric power generation system. The obtained solutions are useful in generating sustainable power generation schemes and capacity-expansion plans. The results indicate that DSFP can support in-depth analysis of the interactions among system efficiency, economic cost and constraint-violation risk. © 2013 Elsevier Ltd. All rights reserved. Source


Zhu Y.,North China Electrical Power University | Fan X.,State Grid Electric Power Research Institute of China
International Journal of Electrical Power and Energy Systems | Year: 2013

As very little research on the fault location for multi-terminal transmission lines based on current traveling waves only has been done, a new fault location scheme on this is proposed. The proposed scheme is different from the traditional ones based on fundamental impedance. Fast Intrinsic Mode Decomposition (FIMD) and Teager Energy Operator (TEO) are combined (FIMD&TEO) to detect the arrival time of the traveling wave at each terminal. Fault Distance Ratio Matrix (FDRM) and rules for identifying faulted sections of a multi-terminal transmission line are proposed and the method for building FDRM is presented in this paper. After several couples of local and remote terminals connecting through the faulted section are got, their fault distances are calculated by means of a two-ended traveling wave method, and then the fault point can be located by averaging the fault distances. Many simulations under various fault conditions have been done, and the results show that the proposed scheme can locate faults more accurately than existing impedance-based methods. © 2013 Elsevier Ltd. All rights reserved. Source


Xu Z.-N.,North China Electrical Power University
IEEE Transactions on Power Delivery | Year: 2013

To improve the accuracy of the static contact angle measurement in the silicone rubber aging experiments, a high accurate contact angle algorithm in combination with the circle fitting algorithm and ellipse fitting algorithm is proposed. The influence of the water drop volume and noise on the calculation accuracies of the two algorithms are analyzed. The results reveal that the circle fitting algorithm is more suitable for the images with small water drop volume and contact angle. However, the ellipse fitting algorithm is more suitable for the images with relatively large water drop volume and contact angle. The critical water drop volumes of the two algorithms in different hydrophobicities are obtained by the calculation of contact angle by the two algorithms. And it is used to select which algorithm to calculate contact angles in the proposed algorithm. The tangent line method, $\theta/2$ method, circle fitting algorithm, ellipse fitting algorithm, and proposed algorithm are implemented. The numerically generated water drop profiles and real water drop images of aged silicone rubber are used to validate the new algorithm. The results indicate that the proposed algorithm is more accurate than the other algorithms in different water drop volumes, contact angles, and noise levels. © 1986-2012 IEEE. Source


Liu M.,University of Victoria | Liu M.,Hubei Engineering University | Shi Y.,University of Victoria | Fang F.,University of Victoria | Fang F.,North China Electrical Power University
Applied Energy | Year: 2013

Performance of the combined cooling, heating and power (CCHP) systems depends on the system structure, power flow strategy and the choice of facility capacity. This paper presents a matrix modeling approach to optimize the CCHP system. Modeled in a matrix form, the CCHP system can be viewed as an input-output model. Energy conversion and flow from the system input to the output is modeled by a conversion matrix including the dispatch factors and components efficiencies. By designing the objective function and determining the constraints, the optimization problem of minimizing the evaluation criteria function is solved. Furthermore, the size of the power generation unit (PGU) is also optimized to achieve the optimal performance of the CCHP system. An illustrative case study is conducted to present the effectiveness and economic efficiency of the proposed optimal power flow and operation strategy. © 2012 Elsevier Ltd. Source


Tan W.,North China Electrical Power University
Nuclear Engineering and Design | Year: 2011

A water level control system for a nuclear steam generator (SG) is proposed. The control system consists of a feedback controller and a feedforward controller. The feedback controller is of first order, the feedforward controller is of second order, and parameters of the two controllers are directly related to the parameters of plant model thus scheduling is easy to implement in practice. Robustness and performance of the feedback and the feedforward controllers are analyzed in details and tuning of the two parameters of the controllers are discussed. Comparisons among a single robust controller, a multi-model controller and a gain-scheduled controller are studied. It is shown that the proposed gain-scheduled controller can achieve good performance at both low and high power levels. © 2011 Elsevier B.V. All rights reserved. Source


Dai W.,North China Electrical Power University
12th International Conference on Environment and Electrical Engineering, EEEIC 2013 | Year: 2013

This paper proposes a method to realize better locating and sizing optimization of distributed generation. It combines the advantages of improved particle swarm optimization algorithm and principal component analysis technology. Based on artificial bee colony algorithm, it proposes the improvement about traditional particle swarm optimization algorithm to improve the convergence. Meanwhile, by means of using principal component analysis, it builds comprehensive model including several economy index, voltage stability index and constrained condition for comprehensive evaluation of multi-objective optimization to enhance credibility of the method proposed. © 2013 IEEE. Source


Wang Z.-G.,North China Electrical Power University
Modern Physics Letters A | Year: 2012

In this paper, we perform an systematic study of the radiative transitions among the bottomonium states using the heavy quarkonium effective Lagrangians, and make predictions for the ratios among the radiative decay widths of a special multiplet to another multiplet. The predictions can be confronted with the experimental data in the future. © 2012 World Scientific Publishing Company. Source


Liu Y.,North China Electrical Power University
International Journal of Theoretical Physics | Year: 2014

In standard Grover's algorithm for quantum searching, the probability of finding a marked state is not exactly 1, and some modified versions of Grover's algorithm that search a marked state from an evenly distributed database with full successful rate have been presented. In this article, we present a generalized quantum search algorithm that searches M marked states from an arbitrary distributed N-item quantum database with a zero theoretical failure rate, where N is not necessary to be the power of 2. We analyze the general properties of our search algorithm, we find that our algorithm has periodicity with a period of 2J + 1, and it is effective with certainty for J + (2J + 1)m times of iteration, where m is an arbitrary nonnegative number. © 2014 Springer Science+Business Media New York. Source


Gao X.,North China Electrical Power University
12th International Conference on Environment and Electrical Engineering, EEEIC 2013 | Year: 2013

In order to further improve the accuracy and efficiency of PMU optimizing methods, a new method considering both bus weight and voltage stability is presented in this paper. The method calculates every bus's weight value at first, related to the importance of the bus in the network, and then places PMU at the bus with maximum weight value until the system is completely observable. Proposed method is further extended for assuring complete observability considering voltage stability obtained by voltage stability analysis. Simulation results for IEEE14-bus system with proposed method are prepared with those with existing techniques. Results show that the proposed method is not only more efficient and accurate, but also beneficial to improving stability of power monitoring system. © 2013 IEEE. Source


An C.-J.,University of Regina | Huang G.-H.,University of Regina | Yao Y.,University of Regina | Sun W.,University of Regina | An K.,North China Electrical Power University
Journal of Hazardous Materials | Year: 2012

Massive quantities of food waste often coexist with other agroindustrial and industrial waste, which might contain coal ash (CA) and uric acid (UA). This study investigated the influence of CA and UA on the composting of food waste in the in-vessel system. The patterns of food waste composting were compared among various combinations. The results showed that the temperature level was enhanced in the presence of CA and UA during the first 8 days. The significant drop in pH was observed in the treatment without any amendment. But the presence of CA could alleviate the drop of pH. More intensive organic mass reduction took place in the treatments with amended CA and UA in the first half of process. The O 2 uptake rate in the reactor with CA and UA was higher than that with only CA in the early stage. Both thermophilic and mesophilic microorganisms were present throughout the composting period. The populations of both thermophilic and mesophilic microorganisms were influenced when amended with CA and UA. The decreasing trend in C/N ratio was shown in all the reactors, while a relatively lower C/N ratio was obtained in the series with both CA and UA. © 2011 Elsevier B.V. Source


Zhou G.,North China Electrical Power University | Zhang Y.,Tianjin University
Applied Thermal Engineering | Year: 2012

Inlet pressure fluctuations were found during the experiments for coiled adiabatic capillary tubes in a one-pass-through type test facility. The fluctuation takes place when the inlet temperature rapidly changes from one point to another. Measured temperature distribution along the tube length showed that this phenomenon may be caused by the variation of flash point location in the capillary tube which leads to the pressure variation wave propagating upstream. Further experiments showed that the pressure fluctuation for coiled capillary tubes is much more prominent than for straight ones; the inlet pressure fluctuation is weak for small coil-diameter capillary tubes; with the increasing of the preset inlet pressure and decreasing of target inlet temperature, the fluctuation amplitude decreases; the pressure fluctuation amplitude at the inlet of parallel coiled capillary tubes is much lower than that of the single one and it needs less time to be stabilized which indicates the advantages of using parallel capillary tubes. The inlet pressure fluctuation in an actual air-conditioner system is found weaker than in the one-pass-through test facility. © 2011 Elsevier Ltd. All rights reserved. Source


Xu E.,CAS Institute of Electrical Engineering | Wang Z.,CAS Institute of Electrical Engineering | Wei G.,North China Electrical Power University | Zhuang J.,CAS Institute of Electrical Engineering
Renewable Energy | Year: 2012

In this paper, the thermal energy storage system of Badaling 1 MW solar power tower plant is modelled from mathematical models for whole of the working conditions using the modular modelling method. This model can accurately simulate the recharge and discharge processes of thermal energy storage system. The dynamic and static characteristics of the thermal energy storage system are analyzed based on the model response curves of the system state parameters that are obtained from different steam flow disturbances. Conclusions of this paper are good references for the design, operating, and control strategy of solar thermal power plant. © 2011 Elsevier Ltd. Source


Fiori F.,Polytechnic University of Turin | Merlin M.,North China Electrical Power University
IEEE Transactions on Power Electronics | Year: 2012

This paper focuses on the electromagnetic emissions of smart-power integrated systems that include analog, digital, and power sections. With reference to common high-voltage CMOS technology processes, it is shown that the switching noise of digital core blocks can propagate to the power sections through the silicon substrate they share. Such disturbances feed the printed circuit board traces and cables connected to the IC power section, which behave like parasitic antennas, and unwanted electromagnetic emissions are experienced. A generic integrated system fabricated with a planar CMOS technology process is considered and the propagation of digital switching noise is analyzed referring to a system level equivalent circuit, which comprises a substrate model and an IC package model. Based on this, the circuit parameters that affect the propagation of the switching noise are highlighted and a new grounding scheme, which reduces the substrate parasitic coupling in smart-power system-on-chip, is proposed. Its effectiveness is proved through computer simulations and experimental tests. © 2011 IEEE. Source


Xu Z.,North China Electrical Power University
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2013

To evaluate the influence of noise type and content on the accuracy of dielectric loss factor calculation, the white noise is simulated by a random variable with normal distribution and the impulsive noise by a random variable with Cauchy distribution and limited amplitude, while the quantization noise of analog-digital conversion is programmed. The influence of SNR(Signal-Noise Ratio) and signal length on the error of dielectric loss factor is investigated and the calculation formulas of errors caused by mentioned noises are fitted. Results show that: the error caused by white noise or impulsive noise decreases along with the increase of SNR or signal length while the error caused by quantization noise decreases only along with the increase of digitalizing bits, immune to signal length. The formulas of errors caused by different noises are given. Source


Ma M.-M.,Jilin University | Ma M.-M.,North China Electrical Power University | Chen H.,Jilin University
IET Control Theory and Applications | Year: 2011

This study suggests an approach to design an active suspension controller with non-linear actuator dynamics, which can achieve good ride comfort while respecting safety constraints such as road holding and limited suspension strokes. The procedure includes two steps: design a state feedback ∞ controller for the linear subsystem with time-domain constraints, and then apply the backstepping technique to deal with non-linear actuator dynamics and to derive the control law. The closed-loop system achieves a bounded disturbance attenuation level (the l2 gain), which gives a measure of ride comfort in the case of general road disturbances. Simulation results are provided to show the effectiveness of the designed controller. © 2011 The Institution of Engineering and Technology. Source


Wang Z.-G.,North China Electrical Power University
Physical Review C - Nuclear Physics | Year: 2015

In this article, I calculate the contributions of nuclear-matter-induced condensates up to dimension 5, take into account the next-to-leading order contributions of the nuclear-matter-induced quark condensate, study the properties of the scalar, pseudoscalar, vector, and axial-vector heavy mesons in nuclear matter with the QCD sum rules in a systematic way, and obtain the shifts of the masses and decay constants. Furthermore, I study the heavy-meson-nucleon scattering lengths as a byproduct, and conclude qualitatively about the possible existence of heavy-meson-nucleon bound states. © 2015 American Physical Society. Source


Cong R.-G.,North China Electrical Power University | Cong R.-G.,Lund University | Wei Y.-M.,Beijing Institute of Technology
Renewable and Sustainable Energy Reviews | Year: 2012

Carbon allowances auctions are a good way to achieve the carbon allowance allocations under international agreements to address global climate change. Based on an economic experiment, this paper compares three possible carbon allowance auction formats (uniform price auction, discriminatory price auction and English clock auction) with heterogeneous bidders (coal power plants and gas power plants) from four perspectives (carbon price, auction efficiency, demand withholding and fluctuations in power supplies). Possibilities of collusion among bidders and impacts of allowance banking and penalty price on bidders' behaviors under different auction formats are also examined. The results show that (1) when there are relatively more bidders and there are no obvious communications between them, despite there being some tacit collusion, efficiency of English clock auction is greater than the other two formats; (2) when there are relatively fewer bidders and there are obvious communications between them, explicit collusions are observed under English clock auction. In this case, discriminatory price auction helps prevent collusion to some extents; (3) in the banking scenario, more speculations are observed, while penalty price exacerbates price volatility. © 2012 Elsevier Ltd. All right reserved. Source


Wang Z.-G.,North China Electrical Power University
Communications in Theoretical Physics | Year: 2015

In this article, we take the Zc(3900) and Z(4430) as the ground state and the first radial excited state of the axial-vector tetraquark states with JPC = 1+-, respectively, and study their masses and pole residues with the QCD sum rules by calculating the contributions of the vacuum condensates up to dimension-10 in a consistent way in the operator product expansion. The numerical result favors assigning the Zc(3900) and Z(4430) as the ground state and first radial excited state of the axial-vector tetraquark states, respectively. © 2015 Chinese Physical Society and IOP Publishing Ltd. Source


Wang Z.-G.,North China Electrical Power University
Communications in Theoretical Physics | Year: 2015

In this article, we calculate the contributions of the vacuum condensates up to dimension-10 in the operator product expansion, and study the Cγμ - Cγν type scalar, axial-vector and tensor tetraquark states in details with the QCD sum rules. In calculations, we use the formula to determine the energy scales of the QCD spectral densities. The predictions favor assigning the Zc(4020) and Zc(4025) as the JPC = 1+- or 2++ diquark-antidiquark type tetraquark states, while the prediction disfavors assigning the Z(4050) and Z(4250) as the JPC = 0++ diquark-antidiquark type tetraquark states. Furthermore, we discuss the strong decays of the 0++, 1+-, 2++ diquark-antidiquark type tetraquark states in details. © 2015 Chinese Physical Society and IOP Publishing Ltd. Source


Zhou W.N.,University of Nottingham | Yan Y.Y.,University of Nottingham | Xu J.L.,North China Electrical Power University
International Communications in Heat and Mass Transfer | Year: 2014

Due to its distinctive characteristics nanofluid has drawn much attention from academic communities since the last decade. Compared with conventional fluids, nanofluid has higher thermal conductivity and surface to volume ratio, which enables it to be an effective working fluid in terms of heat transfer enhancement. Recent experimental works have shown that with low nanoparticle concentrations (1-5. vol.%), the effective thermal conductivity of the suspensions can increase by more than 20% for various mixtures. Although many outstanding experimental works have been carried out, the fundamental understanding of nanofluid characteristics and performance is still not sufficient. Much more theoretical and numerical studies are required. Over the past two decades, the lattice Boltzmann method (LBM) has experienced a rapid development and well accepted as a useful method to simulate various fluid behaviours. In the present study, the LBM is employed to investigate the characteristics of nanofluid flow and heat transfer. By coupling the density and temperature distribution functions, the hydrodynamics and thermal features of nanofluids are properly simulated. The effects of the parameters including Rayleigh number and volume fraction of nanoparticles on hydrodynamic and thermal performances are investigated. The results show that both Rayleigh number and solid volume fraction of nanoparticles have influences on heat transfer enhancement of nanofluids; and there is a critical value of Rayleigh number on the performance of heat transfer enhancement. © 2014 Elsevier Ltd. Source


Larson E.D.,Princeton Environmental Institute | Fiorese G.,Polytechnic of Milan | Liu G.,Princeton Environmental Institute | Liu G.,North China Electrical Power University | And 3 more authors.
Energy and Environmental Science | Year: 2010

Energy, carbon, and economic performances are estimated for facilities co-producing Fischer-Tropsch Liquid (FTL) fuels and electricity from a co-feed of biomass and coal in Illinois, with capture and storage of by-product CO 2. The estimates include detailed modeling of supply systems for corn stover or mixed prairie grasses (MPG) and of feedstock conversion facilities. Biomass feedstock costs in Illinois (delivered at a rate of one million tonnes per year, dry basis) are $ 3.8/GJHHV for corn stover and $ 7.2/GJHHV for MPG. Under a strong carbon mitigation policy, the economics of co-producing low-carbon fuels and electricity from a co-feed of biomass and coal in Illinois are promising. An extrapolation to the United States of the results for Illinois suggests that nationally significant amounts of low-carbon fuels and electricity could be produced this way. © 2010 The Royal Society of Chemistry. Source


Wenmiao S.,North China Electrical Power University
Proceedings - 2011 4th IEEE International Symposium on Microwave, Antenna, Propagation and EMC Technologies for Wireless Communications, MAPE 2011 | Year: 2011

A digital IF receiver is researched based on the idea of Software defined radio in this paper. The receiver includes numerical controlled oscillator(NCO), Digital Down Conversion(DDC) and the modem in a Wireless Spread Spectrum Communication system. Firstly the DDC module which include CIC (cascaded-integrator-com) and HBF(half band filter) is implemented through DSP builder, ASIC (application specific integrated circuit) design flow and verified using a FPGA (field programmable gate array) board. Then the coherent demodulation of QPSK based on COSTAS loop is researched and designed in FPGA using modern DSP technology. © 2011 IEEE. Source


Xiang L.,North China Electrical Power University | Yang S.,Zhejiang University | Gan C.,Zhejiang University
Optics and Lasers in Engineering | Year: 2012

In this work, a laser torsional vibrameter was used to measure the torsion vibration of a rotating shaft system under electrical network impact. Based on the principles of laser Doppler velocimetry, the laser torsional vibrometer (LTV) are non-contact measurement of torsional oscillation of rotating shafts, offering significant advantages over conventional techniques. Furthermore, a highly complex shafting system is analyzed by a modified Riccati torsional transfer matrix. The system is modeled as a chain consisting of an elastic spring with concentrated mass points, and the multi-segments lumped mass model is established for this shafting system. By the modified Riccati torsional transfer matrix method, an accumulated calculation is effectively eliminated to obtain the natural frequencies. The electrical network impacts can activize the torsional vibration of shaft system, and the activized torsion vibration frequencies contained the natural frequencies of shaft system. The torsional vibrations of the shaft system were measured under electrical network impacts in laser Doppler torsional vibrometer. By comparisons, the natural frequencies by measurement were consistent with the values by calculation. The results verify the instrument is robust, user friendly and can be calibrated in situ. The laser torsional vibrometer represents a significant step forward in rotating machinery diagnostics. © 2012 Elsevier Ltd. Source


Xu Y.-H.,North China Electrical Power University
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2011

Subsynchronous oscillation resulting from the interaction between complex multi-machine system and HVDC is analyzed and damped. Firstly, the turbine generator units that have SSO problem are screened out using unit interaction factor method. Then, the complex multi-machine system is simplified into single-machine AC-DC hybrid system according to the principle of UIF invariability and the damping characteristic of AC-DC hybrid system is analyzed by complex torque coefficient method. Finally, the HVDC supplemented subsynchronous damping controller designed for single-machine system is used to damp the subsynchronous oscillation of the complex multi-machine system and the simulation results indicate that the SSDC designed in this paper is effective. Source


Zhang Z.,North China Electrical Power University | Kunihiro T.,Kyoto University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2011

We investigate the effects of the axial-anomaly term with a chiral-diquark coupling on the phase diagram within a two-plus-one-flavor Nambu-Jona-Lasinio model under the charge-neutrality and β-equilibrium constraints. We find that when such constraints are imposed, the new anomaly term plays a quite similar role as the vector interaction does on the phase diagram, which the present authors clarified in a previous work. Thus, there appear several types of phase structures with multiple critical points at low temperature T, although the phase diagrams with intermediate-T critical point(s) are never realized without these constraints even within the same model Lagrangian. This drastic change is attributed to an enhanced interplay between the chiral and diquark condensates due to the anomaly term at finite temperature; the u-d diquark coupling is strengthened by the relatively large chiral condensate of the strange quark through the anomaly term, which in turn definitely leads to the abnormal behavior of the diquark condensate at finite T, inherent to the asymmetric quark matter. We note that the critical point from which the crossover region extends to zero temperature appears only when the strength of the vector interaction is larger than a critical value. We also show that the chromomagnetic instability of the neutral asymmetric homogenous two-flavor color-superconducting phase is suppressed and can be even completely cured by the enhanced diquark coupling due to the anomaly term and/or by the vector interaction. © 2011 American Physical Society. Source


Wang Z.-G.,North China Electrical Power University | Tian Y.-F.,Hefei University of Technology
International Journal of Modern Physics A | Year: 2015

In this paper, we tentatively assign the Y(4140), Y(4274) and X(4350) to be the scalar and tensor csc¯s¯ tetraquark states, respectively, and study them with the QCD sum rules. In the operator product expansion, we take into account the vacuum condensates up to dimension-10. In calculations, we use the formula μ = √M2 X/Y/Z- (2M{double-struck}c)2to determine the energy scales of the QCD spectral densities. The numerical results favor assigning the Y(4140) to be the JPC= 2++diquark-antidiquark type tetraquark state, and disfavor assigning the Y(4274) and X(4350) to be the 0++or 2++tetraquark states. © 2015 World Scientific Publishing Company. Source


Xu Z.,North China Electrical Power University
Gaodianya Jishu/High Voltage Engineering | Year: 2013

To improve the accuracy of static contact angle measurements of silicone rubber material, a modified circle fitting algorithm is proposed. Based on water drop profiles numerically generated by the Young-Laplace equation, the influence of the water drop volumes and contact angles on the accuracy of the circle fitting algorithm is studied, while having the volume of these water drops less than 1000 μL, contact line less than 2 cm, and the static contact angle within a range of 5°~179°. The results indicate that the calculation error of the circle fitting algorithm increases with the water drop volume, and the maximum error could be larger than 100°. The calculation result is corrected by a linear two-dimensional interpolation, and it is concluded that the result could be properly corrected, with the same water drop volume and contact line length as mentioned above. Using the proposed algorithm to calculate the contact angles of numerically generated water drop images and real water drop images of silicone rubber with different hydrophobicities and water drop volumes, the results verifies the effectiveness of the proposed algorithm, with the maximum error of simulated results less than 1°. Moreover, the proposed algorithm could be relatively easily implemented while having less computational burden. The proposed algorithm can also be applied to calculate the static contact angle of other materials. Source


Wang Y.,North China Electrical Power University | Yu X.,RMIT University
IEEE Transactions on Industrial Electronics | Year: 2010

A nonlinear model combining boilerturbinegenerator dynamic characteristics for a thermal-power-generation unit is first introduced. Based on the nonlinear model, a new coordinated control design is proposed using the backstepping method incorporating the coordinated passivation approach that considers the entire boiler-turbine-generator system as a whole. The control design consists of three subcontrollers, namely, a main steam valve controller, an excitation controller, and a fuel flow controller. It is shown that the proposed coordinated control design can ensure asymptotical stability of the closed-loop system and improve the electric power regulation performance. Simulation results based on a practical thermal-power-plant model are presented to show the effectiveness of the proposed control design. © 2010 IEEE. Source


Xu Z.,North China Electrical Power University
Measurement: Journal of the International Measurement Confederation | Year: 2014

The static contact angle for blurry drop images is more intricate to obtain. To improve the accuracy of the Hough transformation for the static contact angle calculation, the water drop images with different volumes are generated by the Laplace equation, and the influence of the volume on the accuracy of the Hough transformation is analyzed. The results reveal that the circle Hough transformation is particularly well suited to the cases with small drop volume. At the same time, the critical water drop volume value corresponding to a contact angle error of 3° is given, a modified Hough transformation algorithm in conjunction with the critical water drop volume is proposed, and at the same time, the accuracy of the static contact angle calculation for blurry water drop images is significantly improved. The proposed algorithm is a powerful approach to estimate the static contact angle for blurry water drop images. © 2014 Elsevier Ltd. All rights reserved. Source


Wang Z.-G.,North China Electrical Power University
International Journal of Theoretical Physics | Year: 2014

In this article, we study the radiative transitions among the vector and scalar heavy quarkonium states with the covariant light-front quark model. In calculations, we observe that the radiative decay widths are sensitive to the constituent quark masses and the shape parameters of the wave-functions, and reproduce the experimental data with suitable parameters. © 2013 Springer Science+Business Media New York. Source


Yuan J.,North China Electrical Power University | Hou Y.,China Electricity Council | Xu M.,University of Michigan
Renewable and Sustainable Energy Reviews | Year: 2012

China has pledged to reduce its CO 2 emissions per unit of GDP by 40-45% by 2020 as of 2005 level. This research examines China's 2020 carbon intensity target and its interdependence with the overarching national economic and social development goals. The results show that, with annual GDP growth rate at 7% during the 12th Five-Year-Plan (FYP) period and 6% during the 13th FYP period, the 45% CO 2 intensity reduction target implies annual CO 2 emissions of 8600 million tonnes by 2020, close to 8400 million tonnes, the UNFCCC 450 ppm scenario for China. However, achieving only the 40% reduction target will lead to 9380 million tonnes CO 2 emissions in 2020 which largely surpass the UNFCCC 450 ppm scenario. We conclude that Chinas 45% CO 2 intensity reduction target is not only within international expectations but also self-consistent with its overall economic and social development strategy. Then primary energy and power planning for implementing the 45% carbon intensity reduction target is proposed. Related investment requirements are also estimated. To achieve the target, China needs to restructure the economic structure for significant improvements in energy conservation. © 2012 Elsevier Ltd. All rights reserved. Source


Cong R.-G.,North China Electrical Power University | Cong R.-G.,Lund University | Shen S.,Zhejiang University of Technology
The Scientific World Journal | Year: 2014

To address the problems of climate change and energy security, Chinese government strived to develop renewable power as an important alternative of conventional electricity. In this paper, the learning curve model is employed to describe the decreasing unit investment cost due to accumulated installed capacity; the technology diffusion model is used to analyze the potential of renewable power. Combined with the investment cost, the technology potential, and scenario analysis of China social development in the future, we develop the Renewable Power Optimization Model (RPOM) to analyze the optimal development paths of three sources of renewable power from 2009 to 2020 in a cost-effective way. Results show that (1) the optimal accumulated installed capacities of wind power, solar power, and biomass power will reach 169000, 20000, and 30000 MW in 2020; (2) the developments of renewable power show the intermittent feature; (3) the unit investment costs of wind power, solar power, and biomass power will be 4500, 11500, and 5700 Yuan/KW in 2020; (4) the discounting effect dominates the learning curve effect for solar and biomass powers; (5) the rise of on-grid ratio of renewable power will first promote the development of wind power and then solar power and biomass power. © 2014 Rong-Gang Cong and Shaochuan Shen. Source


Yuan H.,North China Electrical Power University
Journal of Information Hiding and Multimedia Signal Processing | Year: 2015

A semi-supervised human action recognition algorithm using skeleton feature is put forward in this paper. In the method, the cumulative skeleton image and skeleton history image are firstly calculated as the feature representation of the human actions. Then, the label of unannotated actions is predicted through the constrained semisupervised K-means clustering algorithm. Meanwhile the average cumulative and history skeleton images are generated as the model of each category actions. Finally, the nearest neighbour method is utilized to classify the observed action according to the correlation coefficients between its feature image and the pre-established templates. The experiments on Weizmann dataset demonstrate that our method is effective. © 2015. Source


Chen D.,North China Electrical Power University | He Q.,Hebei University | Wang X.,Hebei University
Fuzzy Sets and Systems | Year: 2010

This paper aims to improve hard margin support vector machines (SVMs) by considering the membership of every training sample in constraints. The membership is computed by employing the technique of fuzzy rough sets so that hard margin SVMs can be combined with fuzzy rough sets and the inconsistence between conditional features and decision labels can be taken into account at the same time. In this paper, we first propose fuzzy transitive kernel based fuzzy rough sets. For binary classification, we use a lower approximation operator in fuzzy transitive kernel based fuzzy rough sets to compute the membership for every training input. And then we reformulate hard margin support vector machines into fuzzy rough set based SVMs (FRSVMs) with new constraints in which the membership is taken into account. Finally, comparisons with soft margin SVMs and fuzzy SVMs are made. The experimental results show that the proposed approach is feasible and valid. It significantly improved the performance of the hard margin SVMs. © 2009 Elsevier B.V. All rights reserved. Source


Yao X.,North China Electrical Power University | Wu L.,Harbin Institute of Technology | Zheng W.X.,University of Western Sydney
IEEE Transactions on Signal Processing | Year: 2011

This paper addresses the problem of fault detection filter design for discrete-time Markovian jump singular systems with intermittent measurements. The measurement transmission from the plant to the fault detection filter is assumed to be imperfect and a stochastic variable is utilized to model the phenomenon of data missing. Our attention is focused on the design of a fault detection filter such that the residual system is stochastically Markovian jump admissible and satisfies some expected performances. A new necessary and sufficient condition for a class of discrete-time Markovian jump singular systems to be stochastically Markovian jump admissible is proposed in the form of strict linear matrix inequalities. Sufficient conditions are established for the existence of the fault detection filter. Finally, a numerical example is provided to demonstrate the usefulness and applicability of the developed theoretical results. © 2011 IEEE. Source


Chen Y.,North China Electrical Power University
Advances in Intelligent Systems and Computing | Year: 2013

Modern electrical automation system network highlights the advantages of strengthening the application of electrical information, can improve the efficiency of thermal power generation in the complex case, to improve the management level and economic efficiency of thermal power plants, promoting the stability of the electrical control,significant social and economic benefits. © 2013 Springer-Verlag. Source


Zhang S.,North China Electrical Power University
Energy Policy | Year: 2016

The Chinese government has in recent years put in place a large number of incentive policies for distributed solar PV (DSPV). However, some of these policies have not been well performed due to many constraints, particularly the lack of innovative business models and financing mechanisms. This paper looks into this issue through the approach of combining literature review and interactive research, including interactions with managers from China's policy and commercial banks and PV projects. A comprehensive literature review on DSPV business models and financing mechanisms are firstly reviewed. Then the rapid evolving business models and financing mechanisms in the United States are examined, which provides some insights for China. Subsequent to this, the existing innovative business models and financing mechanisms for DSPV deployment in China and challenges facing them are discussed. Built on this discussion, policy recommendations are provided at the end of the paper. This study provides some insights for renewable energy policy makers in China as well as in other countries. © 2016 Source


Shi P.,University of Adelaide | Shi P.,Victoria University of Melbourne | Yin Y.,Jiangnan University | Liu F.,Jiangnan University | Zhang J.,North China Electrical Power University
Information Sciences | Year: 2014

In this paper, a robust H∞ controller is designed for saturated Markov jump systems with uncertainties and time varying transition probabilities. The time-varying transition probability uncertainty is described as a polytope set. Stochastic stability is analyzed for the underlying systems by Lyapunov function approach and a sufficient condition is derived to design controllers such that the resulting closed-loop system is stochastically stable and a prescribed H∞ performance is also achieved. Furthermore, the attraction domain of this Markov jump system is estimated and evaluated. A simulation example is given to show the effectiveness of the developed techniques. © 2013 Elsevier Inc. All rights reserved. Source


Wang S.,University of Regina | Huang G.H.,University of Regina | He L.,North China Electrical Power University
Science of the Total Environment | Year: 2012

Groundwater contamination by dense non-aqueous phase liquids (DNAPLs) has become an issue of great concern in many industrialized countries due to their serious threat to human health. Dissolution and transport of DNAPLs in porous media are complicated, multidimensional and multiphase processes, which pose formidable challenges for investigation of their behaviors and implementation of effective remediation technologies. Numerical simulation models could help gain in-depth insight into complex mechanisms of DNAPLs dissolution and transport processes in the subsurface; however, they were computationally expensive, especially when a large number of runs were required, which was considered as a major obstacle for conducting further analysis. Therefore, proxy models that mimic key characteristics of a full simulation model were desired to save many orders of magnitude of computational cost. In this study, a clusterwise-linear-regression (CLR)-based forecasting system was developed for establishing a statistical relationship between DNAPL dissolution behaviors and system conditions under discrete and nonlinear complexities. The results indicated that the developed CLR-based forecasting system was capable not only of predicting DNAPL concentrations with acceptable error levels, but also of providing a significance level in each cutting/merging step such that the accuracies of the developed forecasting trees could be controlled. This study was a first attempt to apply the CLR model to characterize DNAPL dissolution and transport processes. © 2012 Elsevier B.V. Source


Wang L.,North China Electrical Power University | Gao Y.-T.,Beihang University | Qi F.-H.,Beijing University of Posts and Telecommunications
Annals of Physics | Year: 2012

Under investigation in this paper is a variable-coefficient modified Kortweg-de Vries (vc-mKdV) model describing certain situations from the fluid mechanics, ocean dynamics and plasma physics. N-fold Darboux transformation (DT) of a variable-coefficient Ablowitz-Kaup-Newell-Segur spectral problem is constructed via a gauge transformation. Multi-solitonic solutions in terms of the double Wronskian for the vc-mKdV model are derived by the reduction of the N-fold DT. Three types of the solitonic interactions are discussed through figures: (1) Overtaking collision; (2) Head-on collision; (3) Parallel solitons. Nonlinear, dispersive and dissipative terms have the effects on the velocities of the solitonic waves while the amplitudes of the waves depend on the perturbation term. © 2012 Elsevier Inc. Source


A method for mercury high throughput rapid speciation analysis was developed by short column capillary electrophoresis (SC-CE) coupled with inductively coupled plasma mass spectrometry (ICP-MS). A MicroMist nebulizer was employed to increase the nebulization efficiency and a laboratory-made removable SC-CE-ICP-MS interface on the basis of cross design was applied to alleviate buffer contamination of ICP-MS. In less than 60 s, methylmercury (MeHg(i)) and inorganic mercury (Hg(ii)) were separated in a 16 × 75 μm i.d. short fused-silica capillary at 21 kV, while a mixture of 30 mmol L -1 boric acid + 5% (v/v) CH 3OH (pH = 8.60) acted as running electrolyte. The precisions (RSD, n = 5) of migration time and peak area for MeHg(i) and Hg(ii) were in the range of 1.4-2.6% and 3.3-3.4%, respectively. The limits of detection (3σ) mercury species were 9.7 μg L -1 and 12.0 μg L -1, respectively. The recoveries for Hg(ii) and MeHg(i) were in the range of 96-107% and 99-105%. © 2011 The Royal Society of Chemistry. Source


Wang C.,Bohai University | He Q.,Hebei University | Chen D.,North China Electrical Power University | Hu Q.,Tianjin University
Information Sciences | Year: 2014

Attribute reduction has become an important step in pattern recognition and machine learning tasks. Covering rough sets, as a generalization of classical rough sets, have attracted wide attention in both theory and application. This paper provides a novel method for attribute reduction based on covering rough sets. We review the concepts of consistent and inconsistent covering decision systems and their reducts and we develop a judgment theorem and a discernibility matrix for each type of covering decision system. Furthermore, we present some basic structural properties of attribute reduction with covering rough sets. Based on a discernibility matrix, we develop a heuristic algorithm to find a subset of attributes that approximate a minimal reduct. Finally, the experimental results for UCI data sets show that the proposed reduction approach is an effective technique for addressing numerical and categorical data and is more efficient than the method presented in the paper [D.G. Chen, C.Z. Wang, Q.H. Hu, A new approach to attribute reduction of consistent and inconsistent covering decision systems with covering rough sets, Information Sciences 177(17) (2007) 3500-3518]. © 2013 Elsevier Inc. All rights reserved. Source


Cai Y.P.,University of Regina | Huang G.H.,University of Regina | Huang G.H.,North China Electrical Power University | Tan Q.,University of Regina | Chen B.,Beijing Normal University
Ecological Modelling | Year: 2011

In this study, a mixed integer fuzzy interval-stochastic programming model was developed for supporting the improvement of eco-resilience to floods in wetlands. This method allows uncertainties that are associated with eco-resilience improvement and can be presented as both probability distributions and interval values to be incorporated within a general modeling framework. Also, capacity-expansion plans of eco-resilience can be addressed through introducing binary variables. Moreover, penalties due to ecological damages which are associated with the violation of predefined targets can be effectively incorporated within the modeling and decision process. Thus, complexities associated with flood resistance and eco-resilience planning in wetlands can be systematically reflected, highly enhancing robustness of the modeling process. The developed method was then applied to a case of eco-resilience enhancement planning in three ecologically vulnerable regions of a wetland. Interval solutions under different river flow levels and different ecological damages were generated. They could be used for generating decision alternatives and thus help decision makers identify desired eco-resilience schemes to resist floods without causing too much damages. The application indicates that the model is helpful for supporting: (a) adjustment or justification of allocation patterns of ecological flood-resisting capacities, (b) formulation of local policies regarding eco-resilience enhancement options and policy interventions, and (c) analysis of interactions among multiple administrative targets within a wetland. © 2009 Elsevier B.V. Source


Qin X.S.,Nanyang Technological University | Xu Y.,North China Electrical Power University
Advances in Water Resources | Year: 2011

Incorporation of uncertainties within an urban water supply management system has been a challenging topic for many years. In this study, an acceptability-index-based two-step interval programming (AITIP) model was developed for supporting urban water supply analysis under uncertainty. AITIP improved upon the traditional two-step interval programming (TIP) through incorporating the acceptability level of constraints violation into the optimization framework. A four-layer urban water supply system, including water sources, treatment facilities, reservoirs, and consuming zones, was used to demonstrate the applicability of proposed method. The results indicated that an AITIP model was valuable to help understand the effects of uncertainties related to cost, constraints and decision maker's judgment in the water supply network, and capable of assisting urban water managers gain an in-depth insight into the tradeoffs between system cost and constraints-violation risk. Compared with TIP, the solutions from AITIP were of lower degree of uncertainty, making it more reliable to identify effective water supply patterns by adjusting decision variable values within their solution intervals. The study is useful in helping urban water managers to identify cost-effective management schemes in light of uncertainties in hydrology, environment, and decisions. The proposed optimization approach is expected to be applicable for a wide variety of water resources management problems. © 2011 Elsevier Ltd. Source


Yao X.,Beihang University | Yao X.,North China Electrical Power University | Guo L.,Beihang University
Information Sciences | Year: 2014

This study addresses the disturbance attenuation and rejection problem for discrete-time Markovian jump systems with lossy measurements and multiple disturbances. The measurements transmitted from the plant to the observer and the controller are assumed to be imperfect, and two stochastic variables are utilized to model the missing data separately. A composite disturbance observer-based control and H∞ control scheme is proposed for attenuating and rejecting the disturbances. This method is focused on the design of a new structure for the disturbance observer, dynamic output feedback controller, and composite controller, such that the composite system is stochastically stable and it satisfies scheduled performance requirements. The computation-oriented conditions of the disturbance observer gains and controller matrices for the controlled plant are provided based on the piecewise quadratic Lyapunov functional approach. Finally, a numerical example is provided to demonstrate the utility and applicability of the proposed theoretical method. © 2014 Elsevier Inc. All rights reserved. Source


Wang Z.-G.,North China Electrical Power University
European Physical Journal C | Year: 2011

In this article, we study the Λc and Λb baryons in the nuclear matter using the QCD sum rules, and obtain the in-medium masses, the in-medium vector self-energies, and the in-medium pole residues. The mass-shifts are and, respectively. © 2011 Springer-Verlag / Società Italiana di Fisica. Source


Zuo J.,University of South Australia | Zhao Z.-Y.,North China Electrical Power University
Renewable and Sustainable Energy Reviews | Year: 2014

Green building is one of measures been put forward to mitigate significant impacts of the building stock on the environment, society and economy. However, there is lack of a systematic review of this large number of studies that is critical for the future endeavor. The last decades have witnessed rapid growing number of studies on green building. This paper reports a critical review of the existing body of knowledge of researches related to green building. The common research themes and methodology were identified. These common themes are the definition and scope of green building; quantification of benefits of green buildings compared to conventional buildings; and various approaches to achieve green buildings. It is found that the existing studies played predominately focus on the environmental aspect of green building. Other dimensions of sustainability of green building, especially the social sustainability is largely overlooked. Future research opportunities were identified such as effects of climatic conditions on the effectiveness of green building assessment tools, validation of real performance of green buildings, unique demands of specific population, and future proofing. © 2013 Published by Elsevier Ltd. Source


Huang X.,North China Electrical Power University | Taytor G.,Brunel University
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2011

When solving the service restoring (SR) problem using the intelligent optimization algorithm, considerable time has to be consumed and the optimizing performance of the algorithm is reduced as it is necessary to not only repeatedly do network topology analysis during changes of the network structure but also very often to do additional checking on radiation during optimization to ensure that the constraints on network radiation operation are not violated. To avoid these disadvantages, the node-depth encoding (NDE) technique is introduced into the non-dominating sorting genetic algorithm-II (NSGA-II) to solve the SR problem to replace traditional crossover and mutation operations with preserve ancestor opexator (PAO) and change ancestor operaton (CAO) operations in NDE technique. The topological structure of the system can be quickly obtained with the NDE technique. Simulation results show that the algorithm proposed has a better performance in convergence and diversity than NSGA-II. © 2011 State Grid Electric Power Research Institute Press. Source


Wang C.,North China Electrical Power University | Jia L.,CANMET Energy | Tan Y.,CANMET Energy | Anthony E.J.,CANMET Energy
Fuel | Year: 2010

A series of tests was conducted in a thermogravimetric analyzer (TGA) to study the sulphation behaviour of limestone in the presence of water over the temperature range of 800-850 °C. Four different Canadian limestones, all with a particle size range of 75-425 μm, were sulphated using a synthetic flue gas with a composition of 15% CO2, 3% O2, 0% or 10% H2O, 1750 ppm SO2 and the balance N2. Water was shown to have a significant promotional effect on sulphation, especially in the diffusion-controlled stage. However, the effect of water during the kinetic-controlled stage appeared to be much less pronounced. Based on these results, it is proposed that the presence of water leads to the transient formation of Ca(OH)2 as an intermediate, which in turn reacts with SO2 at a faster rate than CaO does. Alternatively stated, it appears that H2O acts as catalyst for the sulphation reaction of CaO. Crown Copyright © 2010 Published by Elsevier Ltd. All rights reserved. Source


Zhao M.,North China Electrical Power University | Zhao M.,Beihang University
Advances in Applied Mathematics and Mechanics | Year: 2013

The scattering of the open cavity filled with the inhomogeneous media is studied. The problem is discretized with a fourth order finite difference scheme and the immersed interfacemethod, resulting in a linear system of equations with the high order accurate solutions in the whole computational domain. To solve the system of equations, we design an efficient iterative solver, which is based on the fast Fourier transformation, and provides an ideal preconditioner for Krylov subspace method. Numerical experiments demonstrate the capability of the proposed fast high order iterative solver. © 2013 Global Science Press. Source


Zhang Z.H.,North China Electrical Power University
Science China: Physics, Mechanics and Astronomy | Year: 2016

The high-spin rotational properties of two-quasiparticle bands in the doubly-odd 166Ta are analyzed using the cranked shell model with pairing correlations treated by a particle-number conserving method, in which the blocking effects are taken into account exactly. The experimental moments of inertia and alignments and their variations with the rotational frequency hω are reproduced very well by the particle-number conserving calculations, which provides a reliable support to the configuration assignments in previous works for these bands. The backbendings in these two-quasiparticle bands are analyzed by the calculated occupation probabilities and the contributions of each orbital to the total angular momentum alignments. The moments of inertia and alignments for the Gallagher-Moszkowski partners of these observed two-quasiparticle rotational bands are also predicted. © 2016, Science China Press and Springer-Verlag Berlin Heidelberg. Source


Lv F.,North China Electrical Power University
Yi Qi Yi Biao Xue Bao/Chinese Journal of Scientific Instrument | Year: 2013

Light spot area is an important parameter of ultraviolet discharge. The light spot areas of many images need to be extracted in external insulation ultraviolet discharge study. In order to extract the light spot area in external insulation ultraviolet discharge image automatically and accurately, a light spot area extraction method based on active contour model is proposed in the paper. With the active contour model, the ultraviolet discharge region contour is obtained through calculating partial differential equation. The algorithm has global optimization capacity, and is different from the conventional method that obtains the edge based on local image information. This method has strong capacity of resisting disturbance and low requirement for image definition; in the meantime, it does not require preprocessing, and can obtain the light spot area of ultraviolet discharge accurately. Conventional edge detection operator, mathematical morphology method and the proposed method were implemented to obtain the light spot areas of ultraviolet discharge images. The result indicates that the edge obtained with conventional edge detection operator contains much interference, the obtained contour points are discrete, and it is difficult to obtain the light spot area through subsequent calculation. The proposed method can obtain the areas of single or multiple light spots accurately. The method does not have the problems that the mathematical morphology method requires factitiously determining the optimal threshold for image binarization and adjusting the dimensions of the structure elements according to the area of interference light spot, and has good automation performance. Source


Wang W.,North China Electrical Power University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

In this paper we investigate the parallel texture structures containing texture zeros in the charged lepton mass matrix Ml and cofactor zeros in the neutrino mass matrix Mν. These textures are interesting since they are related to the Zn flavor symmetries. Using the weak basis permutation transformation, the 15 parallel textures are grouped as 4 classes (class I, II, III, and IV), with the matrices in each class sharing the same physical implications. Under the current experimental data, the classes I and III with inverted mass hierarchy and class II with normal mass hierarchy are phenomenologically acceptable. The correlations between some important physical variables are presented, which are essential for the model selection and can be tested by future experiments. The model realization is illustrated by means of Z4×Z2 flavor symmetry. © 2014 American Physical Society. Source


Liu X.,North China Electrical Power University | Guan P.,Beijing Institute of Machinery | Chan C.W.,University of Hong Kong
IEEE Transactions on Control Systems Technology | Year: 2010

A coordinated control strategy is often used to ensure a thermal power plant to have a higher rate of load change, but without violating the thermal constraints. Although model predictive control has been widely used for controlling power plant, handling input constraints is a major problem especially as these plants are nonlinear. Two alternative methods of exploiting the nonlinear predictive control are presented in this paper. One is the input-output feedback linearization technique based on a suitably chosen approximated linear model. The other is based on neuro-fuzzy networks to represent a nonlinear dynamic process using a set of local models. From the criteria based on the integral absolute errors and the relative optimization time for completing the simulation, it is shown that the performance of the coordinated control of a steam-boiler generation plant using these two nonlinear predictive methods are better than the conventional predictive method. © 2010 IEEE. Source


Liang C.,North China Electrical Power University
Proceedings - 2011 8th International Conference on Fuzzy Systems and Knowledge Discovery, FSKD 2011 | Year: 2011

Different users usually have different special information needs when they use search engines to find web information. The technologies of personalized web search can be used to solve the problem. An effective way to personalized search engines' results is to construct user profile to present an individual user's preference. Utilizing the relative machine learning techniques, three approaches are proposed to build the user profile in this paper. These approaches are called as Rocchio method, k-Nearest Neighbors method and Support Vector Machines method. Experimental results based on a constructed dataset show that k-Nearest Neighbors method is better than others for its efficiency and robustness. © 2011 IEEE. Source


Wang Z.-G.,North China Electrical Power University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

In this article, we study the momentum dependence of the hadronic coupling constants GBc*BcÏ, GBc*BcJ/ψ, GBcBcÏ, and GBcBcJ/ψ with the off-shell Υ and J/ψ using the three-point QCD sum rules. Then we fit the hadronic coupling constants into analytical functions and extrapolate them into deep time-like regions to obtain the on-shell values GBc*BcÏ (q2=MÏ 2), GBc*BcJ/ψ(q2=MJ/ψ2), GBcBcÏ (q2=MÏ 2), and GBcBcJ/ψ(q2=MJ/ψ2) for the first time. These hadronic coupling constants can be taken as basic input parameters in phenomenological analyses. © 2014 American Physical Society. Source


Kirca M.,University of Pittsburgh | Yang X.,North China Electrical Power University | To A.C.,University of Pittsburgh
Computer Methods in Applied Mechanics and Engineering | Year: 2013

Carbon nanotubes (CNTs) are one of the presents of nanotechnology being investigated due to their extraordinary mechanical, thermal and electrical properties. Carbon nanotube networks feed the idea that CNTs can be used as the building blocks of new advanced materials utilizing the superior characteristics of CNTs. In this way, nanoscale features of CNTs can be scaled up to even continuum proportions. In this study, 2-D and 3-D CNT network generation methods are introduced by which the geometrical parameters, such as CNT length, chirality, intersection angle and junctional density, can be controlled and a random CNT network is obtained. Then, molecular dynamics (MD) simulations are used to create covalent bonds between intersecting CNTs, which allow the investigation of the mechanical, thermal and electrical properties of random CNT networks. © 2013 Elsevier B.V. Source


Bai Z.-W.,North China Electrical Power University
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2014

The work fluctuations of a quantum Brownian particle driven by an external force in a general nonergodic heat bath are studied under a general initial state. The exact analytical expression of the work probability distribution function is derived. Results show the existence of a quantum asymptotic fluctuation theorem, which is in general not a direct generalization of its classical counterpart. The form of this theorem is dependent on the structure of the heat bath and the specified initial condition. © 2014 Elsevier B.V. Source


Qiu Y.,North China Electrical Power University
Journal of Theoretical and Applied Information Technology | Year: 2012

With the rapid development of Internet technology, there have been many new services which require high bandwidth. EPON (Ethernet Passive Optical Network) has become one of the best technologies in the next generation broadband access network because of their high-bandwidth and low-cost. Dynamic bandwidth allocation (DBA) is one of the most critical issues in EPON network. In this paper, a new DBA algorithm is proposed to support QoS and to get higher performance. The proposed algorithm could avoid bandwidth wastes result from dynamically allocation from differentiated services and unused bandwidth. Detailed simulations are performed to verify the effectiveness of the proposed DBA algorithm. © 2005 - 2012 JATIT & LLS. All rights reserved. Source


Zhang Z.-H.,North China Electrical Power University
Nuclear Physics A | Year: 2016

The high-spin rotational bands in odd-Z nuclei 159Ho (Z=67) are investigated using the cranked shell model with the pairing correlations treated by a particle-number conserving method, in which the blocking effects are taken into account exactly. The experimental moments of inertia and alignments and their variations with the rotational frequency hω are reproduced very well by the calculations. The splitting between the signature partners of the yrast band 7/2-[523] is discussed and the splitting of the excited band 7/2+[404] above hω~0.30 MeV is predicted due to the level crossing with 1/2+[411]. The calculated B(E2) transition probabilities are also suggested for future experiments. © 2016 Elsevier B.V. Source


Wang Z.-G.,North China Electrical Power University | Huang T.,CAS Institute of High Energy Physics
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

In this article, we distinguish the charge conjunctions of the interpolating currents, calculate the contributions of the vacuum condensates up to dimension 10 in a consistent way in the operator product expansion, study the masses and pole residues of the JPC=1+± hidden charmed tetraquark states with the QCD sum rules, and explore the energy-scale dependence in detail for the first time. The predictions MX=3.87-0.09+0.09GeV and MZ=3.91-0.09+0.11GeV support assigning the X(3872) and Zc(3900) [or Zc(3885)] as the 1++ and 1+- diquark-antidiquark type tetraquark states, respectively. © 2014 American Physical Society. Source


Xu Z.,North China Electrical Power University
IET Science, Measurement and Technology | Year: 2014

To improve the accuracy of the static contact angle evaluation for the blurry drop images, a large number of water drop images are numerically generated or acquired by the contact angle instrument/digital camera. Based on these images, the applicability of the circle Hough transformation and circle fitting algorithms is systematically investigated and compared. The results reveal that the least-squares circle fitting algorithm is particularly suitable for the clear drop images, such as the images acquired by the contact angle instrument. The circle Hough transformation is particularly suitable for the blurry drop images, such as the images acquired by the digital camera. The influence of the contact angle on the contact angle error by the circle Hough transformation is investigated. The critical contact angle values corresponding to various water drop volumes are given, which can be used to improve the accuracy of the static contact angle measurement for the blurry drop images. A modified Hough transformation based on the critical contact angle is proposed. The modified Hough transformation is verified by the static contact angle measurements of different insulating materials. The study proposes a comparatively effective algorithm for automatic and accurate static contact angle measurement of the blurry drop images. © The Institution of Engineering and Technology. Source


Tan X.,Shandong University | Li Q.,North China Electrical Power University | Wang H.,Shandong University
International Journal of Electrical Power and Energy Systems | Year: 2013

Microgrid (MG) is the indispensable infrastructure of nowadays smart grid, however, fluctuation and intermittence resulted from unstable micro-sources and nonlinear loads will execute considerable impacts on normal operation of the MG. Energy storage technology presents a preferable solution to the above issue. The paper gives a full scope review of the principal energy storage technologies being developed so far, and the features and benefits of energy storage systems (ESSs) within the MG are analyzed in details including ESS configuration and topologies, power electronics interfaces, ESS control schemes for charging/discharging, control strategy of hybrid ESS as well as optimization of the renewable sources and ESS. The future trends and challenges of ESS are also fully accounted, with a view to proposing smart ESS as the promising technology in the future for MG and smart grid. © 2012 Elsevier Ltd. All rights reserved. Source


Zhao Z.-Y.,North China Electrical Power University | Zhang S.-Y.,China Electric Power Research Institute | Hubbard B.,Purdue University | Yao X.,Beijing Association for Electrical Power Industry
Renewable and Sustainable Energy Reviews | Year: 2013

Solar photovoltaic (PV) power is a new and green energy source. China has significant opportunities for solar energy utilization with its huge solar resource. The solar PV power in China has developed for 50 years, and experienced a rapid progress in the last 10 years. To address the needs of the fast growth of the PV power industry in China, it is critical to identify, analyze and understand the growth path and the characteristics of the industry. This paper summarizes the status of the solar energy resources and the development of the solar PV power industry in China, and puts forward the main factors that impacted the development of the industry. A study refers to the selected five main factors the factors are: technology research and development, industrial plans, laws and regulations, electricity price policies, and projects incentive policies. A multifaceted approach including literature survey, statistical data investigation, law review, and regulation and policy study are adopted to investigate these factors. Analysis of the typical events, the growth process and the characteristics of the five factors, allows the establishment of growth route models. The results can be a useful reference for the development of solar PV power industry in China and other countries. © 2013 Published by Elsevier Ltd. Source


Yi Y.-J.,Beijing Normal University | Zhang S.-H.,North China Electrical Power University
Environmental Science and Pollution Research | Year: 2012

Purpose: The objective of this paper is to assess the regulation of the accumulation of heavy metals in the aquatic environment and different fish species. Methods: Water and fish samples were collected from upper to lower reaches of the Yangtze River. The heavy metal (Cd, Cr, Cu, Hg, Pb, Zn) concentrations in the muscle tissue of seven fishes were measured. Additionally, the relationships between heavy metal concentrations in fish tissue and fish size (length and weight), condition factor, water layer distribution, and trophic level were investigated. Results: Metal concentrations (milligrams per kilogram wet weight) were found to be distributed differently among different fish species. The highest concentrations of Cu (1. 22 mg/kg) and Zn (7. 55 mg/kg) were measured in Pelteobagrus fulvidraco, the highest concentrations of Cd (0. 115 mg/kg) and Hg (0. 0304 mg/kg) were measured in Silurus asotus, and the highest concentrations of Pb (0. 811 mg/kg) and Cr (0. 239 mg/kg) were measured in Carassius auratus and Cyprinus carpio. A positive relationship was found between fish size and metal level in most cases. The variance of the relationships may be the result of differences in habitat, swimming behavior, and metabolic activity. In this study, fishes living in the lower water layer and river bottom had higher metals concentrations than in upper and middle layers. Benthic carnivorous and euryphagous fish had higher metals concentrations than phytoplankton and herbivorous fish. Generally, fish caught from the lower reach had higher metals concentrations than those from the upper reach. Conclusions: Cadmium and lead concentrations in several fishes exceeded the permissible food consumption limits, this should be considered to be an important warning signal. © 2012 Springer-Verlag. Source


Cong R.-G.,North China Electrical Power University | Cong R.-G.,Lund University
Renewable and Sustainable Energy Reviews | Year: 2013

In response to climate change, China's power industry is undertaking the task of reducing carbon emissions. Renewable energy generation has become an important option. For the government and state grid companies, it is important to know the maximum possible capacities of renewable energy generation from its different sources in order to plan the construction of the power grid in the future. In this paper, several important factors affecting the development of renewable energy generation are identified through a review of the existing literature (such as cost, technical maturity and so on) and analyzed. Combined with the learning curve model, the technology diffusion model and expectations about future economic development in China, a new model, the Renewable Energy Optimization Model (REOM), is developed to analyze the development of three renewable energy sources (wind power, solar power and biomass power) from 2009 to 2020. Results show that (1) the maximum installed capacities of wind power, solar power and biomass power will reach 233321, 26680 and 35506 MW in 2020; (2) from 2009 to 2020, biomass power will develop rapidly at the early stage while wind power is developed massively at the final stage and solar power has relatively stable growth; (3) due to the added capacity in the early periods, the unit investment cost of solar power shows a large decline, which is good for its following scale development; (4) the investment ratio constraint has a large effect on the development of wind power while the constraint of on-grid proportion of renewable energy generation has a significant effect on the development of wind power and solar power. The results have important policy implications for long-term energy planning in developing countries, such as China and India. © 2012 Elsevier Ltd. Source


Sun C.-P.,North China Electrical Power University | Yang X.,A Cheng Relay Co.
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2013

A classification and recognition method for power quality disturbances based on module time-frequency matrixes by S transform is proposed. The corn of it is that, at first, module time-frequency matrix by S transform is used to indicate the characteristics of power quality distrubance, the standard mode of various distrubances is established on the base of probability density of magnitude of module time-frequency matrix, and then considering euclidean distance between distrubances and standard mode, the degree of similarity can be calculated, and disturbances are classified. And detection precision is also acceptable. The simulation results show that the approach has better anti-interference performance, and classification results in the condition of low SNR and detection precision are also acceptable. Source


Xu Y.-H.,North China Electrical Power University
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2013

In subsynchronous frequency range, usually there are multiple modes of torsional vibration for turbine generator shaft. At present, the effective damping strategy is deficient for multi-mode subsynchronous oscillation induced by high voltage direct current. In power system, the phenomena have happened several times that obvious shaft oscillations still exist after subsynchronous damping controller has been applied. In this paper, state space method is used to analyze shaft mechanical system, and the concept of mode observability and controllability degree of subsynchronous oscillation is established. In the design of subsynchronous damping controller, the parameters are optimized based on observability and controllability degree of subsynchronous oscillation modes. Simulation results of PSCAD/EMTDC indicate that traditional subsynchronous damping controller is not very effective for the oscillation mode with relative low observability and controllability degree and the subsynchronous damping controller based on observability and controllability degree proposed is very effective for all subsynchronous oscillations in different modes. The product of this paper has important reference value for damping multi-modes subsynchronous oscillation induced by high voltage direct current. Source


Tian G.,Anhui University of Science and Technology | Tian G.,KTH Royal Institute of Technology | Liu J.-C.,KTH Royal Institute of Technology | Liu J.-C.,North China Electrical Power University | And 2 more authors.
Physical Review Letters | Year: 2011

The electroluminescence (EL) of molecules confined inside a nanocavity in the scanning tunneling microscope possesses many intriguing but unexplained features. We present here a general theoretical approach based on the density-matrix formalism to describe the EL from molecules near a metal surface induced by both electron tunneling and localized surface plasmon excitations simultaneously. It reveals the underlying physical mechanism for the external bias dependent EL. The important role played by the localized surface plasmon on the EL is highlighted. Calculations for porphyrin derivatives have reproduced corresponding experimental spectra and nicely explained the observed unusual large variation of emission spectral profiles. This general theoretical approach can find many applications in the design of molecular electronic and photonic devices. © 2011 American Physical Society. Source


Wang Z.-G.,North China Electrical Power University | Huang T.,CAS Institute of High Energy Physics
Physical Review C - Nuclear Physics | Year: 2011

In this Brief Report we calculate the in-medium mass modifications of the scalar mesons D0 and B0 using the QCD sum rules. In calculations we observe that the D0N and B0N scattering lengths are about 1.1 and 4.1fm, respectively, the mass shifts δM D0=69MeV and δMB0=217MeV, and the D 0N and B0N interactions are repulsive. The positive mass shifts indicate that the decays of the higher charmonium states into the D 0D̄0 pair are suppressed. © 2011 American Physical Society. Source


Yin J.,North China Electrical Power University
Nature Environment and Pollution Technology | Year: 2014

Air pollution has no national boundaries, which has caused widespread concern around the world. In order to analyse the diffusion and distribution characteristics of the particulate matter smaller than 2.5 micrometers (PM2.5), the PM2.5 diffusion model was established. By comparatively analysing the solutions of instantaneous point source equation with and without wind, the solution of continuous point source equation with wind, and the correction solution of an elevated point source model; the conclusion was drawn that the Gauss smoke cloud model adopted can solve the problem of diffusivity of PM2.5. The results show that the Gauss smoke model with wind can reliably analyse the actual problem by numerical simulation and the monitoring data in Xi'an of China. Through the analysis of the causes and general rules of PM2.5, it was found that the human activities play the leading role for PM2.5. Source


Li Y.-R.,Chongqing University | Du M.-T.,Chongqing University | Wu C.-M.,Chongqing University | Wu S.-Y.,Chongqing University | And 2 more authors.
Energy | Year: 2014

This paper presents an economical evaluation and parametric optimization on subcritical ORC (organic Rankine cycle) system for recovering the low-temperature waste heat of flue gas which is released from industrial boilers. First, the effects of the PPTD (pinch point temperature difference) in evaporator and condenser, and evaporating temperature on the system performance are examined with the EPC (electricity production cost) as the evaluation criterion. The optimal evaporating temperature, PPTDs in evaporator and condenser, as well as condensing temperature corresponding to the minimum EPC are provided simultaneously for the subcritical ORC system under different heat source temperatures. Then, the optimal parameter values are compared for nine potential organic working fluids with the critical point temperature from 124°C to 235°C. Results show that there exists a possible relationship between the critical temperature of working fluids and the economical performance of the system. Furthermore, it is suggested that the working fluids including R123, n-pentane, R11 and R141b, whose critical temperature range from 180°C to 210°C, are preferable for recovering the low-temperature waste heat of flue gas. © 2014 Elsevier Ltd. Source


Yang S.,CNRS Research on Catalysis and Environment in Lyon | Yang S.,North China Electrical Power University | Besson M.,CNRS Research on Catalysis and Environment in Lyon | Descorme C.,CNRS Research on Catalysis and Environment in Lyon
Applied Catalysis B: Environmental | Year: 2010

CexZr1-xO2-based Pt catalysts were investigated in the catalytic wet air oxidation (CWAO) of formic acid at low temperature (294-326K) under atmospheric pressure in order to evaluate the impact of the high oxygen mobility over the ceria-zirconia supports on the catalytic performances. The effect of the support composition, the Pt loading and the reaction conditions (reaction temperature, formic acid concentration, oxygen partial pressure) was studied. The bare supports, in the absence of any active metal, appeared to be only slightly active. The 0.080wt.%Pt/Ce0.9Zr0.1O2 catalyst (0.5gL-1) exhibited the best performances: 100% formic acid (5gL-1) conversion was achieved after 360min at 326K under atmospheric pressure. The reaction apparent activation energy was ca. 36±4kJmol-1. In the lowest temperature range (T≤313K), the initial reaction rate was proportional to the dissolved oxygen concentration and, accordingly, the reaction order with respect to oxygen was ca. 1±0.1. The oxygen transfer to the active site was rate limiting and formic acid saturated the catalyst surface. More interestingly, from ca. 326K, the reaction order with respect to formic acid increased to ca. 0.5±0.1 and the reaction order with respect to oxygen decreased to 0.8±0.1, indicating that oxygen might already be efficiently activated on the CexZr1-xO2 mixed oxide supports even under moderate temperature conditions. © 2010 Elsevier B.V. Source


Yao X.,Beihang University | Yao X.,North China Electrical Power University | Guo L.,Beihang University
IET Control Theory and Applications | Year: 2014

This study addresses the problems of the composite disturbance-observer- based (DOB) output feedback control and passive control for Markovian jump systems with non-linearity and multiple disturbances. The multiple disturbances include two kinds: one is supposed to be a norm-bounded vector; the other is described by an exogenous system with perturbations. The purpose of the problem addressed is to design a DOB output feedback controller such that (i) the resulting composite system is passive; and (ii) different types of the above disturbances can be attenuated and rejected, respectively. The characterisation of the gains of the desired disturbance observer and the matrices of the expected output feedback controller are derived based on the solution to a convex optimisation problem that can be easily solved by standard numerical software. Finally, a simulation example is employed to show the effectiveness of the composite control scheme proposed in this study. © The Institution of Engineering and Technology 2014. Source


Tan W.,North China Electrical Power University
ISA Transactions | Year: 2010

Robust analysis and design for a double two-degree-of-freedom (TDF) scheme are discussed in the paper. It is shown that the double TDF scheme is a TDF version of the internal model control (IMC) structure for integrating and unstable processes and retains the property of the IMC structure for stable processes. A robustness measure is proposed assuming that the controlled process has a general uncertainty description. The measure is convenient for comparing the robustness of different control systems and can be used as a guideline for robust tuning. Finally, a TDF-IMC method is proposed to design and tune the parameters of the double TDF scheme to achieve improved robust performance. © 2010 ISA. Published by Elsevier Ltd. All rights reserved. Source


Lu X.,North China Electrical Power University
International Journal of Minerals, Metallurgy and Materials | Year: 2014

Ceramic materials were investigated as thermal barrier coatings and electrolytes. Electrophoretic deposition (EPD) and physical vapor deposition (PVD) were employed to fabricate samples, and the mechanical properties and microstructure were examined by nanoindentation and microscopy, respectively. Yttria-stabilized zirconia/alumina (YSZ/Al2O3) composite coatings, a candidate for thermal barrier coatings, yield a kinky, rather than smooth, load-displacement curve. Scanning electron microscope (SEM) examination reveals that the kinky curve is because of the porous microstructure and cracks are caused by the compression of the indenter. Li0.34La0.51TiO2.94 (LLTO) on Si/SrRuO3 (Si/SRO) substrates, an ionic conductor in nature, demonstrates electronic performance. Although SEM images show a continuous and smooth microstructure, a close examination of the microstructure by transmission electron microscopy (TEM) reveals that the observed spikes indicate electronic performance. Therefore, we can conclude that ceramic coatings could serve multiple purposes but their properties are microstructure-dependent. © 2014, University of Science and Technology Beijing and Springer-Verlag Berlin Heidelberg. Source


Wang Z.-G.,North China Electrical Power University
Communications in Theoretical Physics | Year: 2014

In this article, we calculate the B* c → ηc form-factors with the three-point QCD sum rules, then study the semileptonic decays B* c → ηcℓvℓ. The tiny decay widths may be observed experimentally in the future at the LHCb, while the B* c → ηc form-factors can be taken as basic input parameters in other phenomenological analysis. © 2013 Chinese Physical Society and IOP Publishing Ltd. Source


Wang R.,City University of Hong Kong | Kwong S.,City University of Hong Kong | Chen D.,North China Electrical Power University
Pattern Recognition | Year: 2012

In classification tasks, active learning is often used to select out a set of informative examples from a big unlabeled dataset. The objective is to learn a classification pattern that can accurately predict labels of new examples by using the selection result which is expected to contain as few examples as possible. The selection of informative examples also reduces the manual effort for labeling, data complexity, and data redundancy, thus improves learning efficiency. In this paper, a new active learning strategy with pool-based settings, called inconsistency-based active learning, is proposed. This strategy is built up under the guidance of two classical works: (1) the learning philosophy of query-by-committee (QBC) algorithm; and (2) the structure of the traditional concept learning model: from-general-to-specific (GS) ordering. By constructing two extreme hypotheses of the current version space, the strategy evaluates unlabeled examples by a new sample selection criterion as inconsistency value, and the whole learning process could be implemented without any additional knowledge. Besides, since active learning is favorably applied to support vector machine (SVM) and its related applications, the strategy is further restricted to a specific algorithm called inconsistency-based active learning for SVM (I-ALSVM). By building up a GS structure, the sample selection process in our strategy is formed by searching through the initial version space. We compare the proposed I-ALSVM with several other pool-based methods for SVM on selected datasets. The experimental result shows that, in terms of generalization capability, our model exhibits good feasibility and competitiveness. © 2012 Elsevier Ltd. Source


Liu L.-G.,North China Electrical Power University
Dianwang Jishu/Power System Technology | Year: 2010

The sun is the origin of space weather that is driven by violent activities of the sun. The disastrous space weather greatly influences technology systems on the ground. Among the influenced technology systems, the influence on power grids is the most severe, and the larger the power grid scale is, the more vulnerable it is. In this paper, the basic concept of space weather and its main impact are discussed and the present situation of the research in this field home and abroad is reviewed. On the basis of analyzing the accidents impacted by space weather home and abroad, the scientific issues, which must be researched and solved to cope with disastrous space weather for very large-scale power grids in China, are proposed. Studying these issues will be favorable to improve the international academic standing of China in the field of space weather and its impact, and can provide theoretical and technical foundation to ensure secure and reliable operation of large-scale power grid in China. Source


Wang Z.-G.,North China Electrical Power University
Nuclear Physics B | Year: 2015

In this article, we assume the two nonets of scalar mesons below and above 1 GeV are all q-q states, and study the semi-leptonic decays B→Sℓ-ν-ℓ, B→Sℓ+ℓ- and B→Sν-ν both in the standard model and in the universal extra dimension model using the B-S form-factors calculated by the light-cone QCD sum rules in our previous work. We obtain the partial decay widths and decay widths, which can be confronted with the experimental data in the future to examine the natures of the scalar mesons and constrain the basic parameter in the universal extra dimension model, the compactification scale 1/R. © 2015 The Author. Source


Wang Z.-G.,North China Electrical Power University
International Journal of Modern Physics A | Year: 2015

In this paper, we assume the Zc(4200) as the color octet-octet type axial-vector molecule-like state, and construct the color octet-octet type axial-vector current to study its mass and width with the QCD sum rules. The numerical values MZ c(4200) = 4.19 ± 0.08 GeV and ΓZ c(4200) ≈ 334 MeV are consistent with the experimental data MZ c(4200) = 4196+31 -29 +17 -13 MeV and ΓZ c(4200) = 370+70 -70 +70 -132 MeV, and support assigning the Zc(4200) to be the color octet-octet type molecule-like state with JPC = 1+- Furthermore, we discuss the possible assignments of the Zc(3900), Zc(4200) and Z(4430) as the diquark-antidiquark type tetraquark states with JPC = 1+-. © 2015 World Scientific Publishing Company. Source


Tan W.,North China Electrical Power University
IEEE Transactions on Power Systems | Year: 2010

A unified PID tuning method for load frequency control (LFC) of power systems is discussed in this paper. The tuning method is based on the two-degree-of-freedom (TDF) internal model control (IMC) design method and a PID approximation procedure. The time-domain performance and robustness of the resulting PID controller is related to two tuning parameters, and robust tuning of the two parameters is discussed. The method is applicable to power systems with non-reheated, reheated, and hydro turbines. Simulation results show that it can indeed improve the damping of the power systems. It is shown that the method can also be used in decentralized PID tuning for multi-area power systems. © 2009 IEEE. Source


Zhou G.,North China Electrical Power University | Zhang Y.,Tianjin University
Applied Energy | Year: 2010

This paper experimentally investigated the system performance of a split-type air conditioner matching with different coiled adiabatic capillary tubes for HCFC22 and HC290. Experiments were carried out in a room-type calorimeter. The results have shown that (1) similar cooling effects can be achieved by matching various capillary tubes of different inner diameters; (2) parallel capillary tubes presented better system performance and flow stability with weaker inlet pressure fluctuations than the single capillary tube; (3) with the coil diameter of the capillary tube increasing from 40 mm to 120 mm, the mass flow rate tended to increase slightly. But the cooling capacity, input power and energy efficiency ratio (EER) did not show evident tendency of change; (4) the refrigerant charge and mass flow rate for HC290 were only 44% and 47% of that for HCFC22, respectively, due to the much lower density. And HC290 had 4.7-6.7% lower cooling capacity and 12.1-12.3% lower input power with respect to HCFC22. However, the EER of HC290 can be 8.5% higher than that of HCFC22, which exhibits the advantage of using HC290. In addition, the experimental uncertainties were analyzed and some application concerns of HC290 were discussed. © 2009 Elsevier Ltd. All rights reserved. Source


Su X.,North China Electrical Power University
Indian Journal of Pure and Applied Physics | Year: 2015

The analysis of the unsteady MHD mixed convective flow and heat transfer over an impulsively stretched permeable vertical surface in a moving fluid with partial velocity slip and thermal slip conditions in the presence of thermal radiation, internal heat absorption or generation, and injection or suction, has been studied in the present paper. The governing boundary layer equations are converted into a system of nonlinear coupled ordinary differential equations by suitable similarity transformations. The appropriate analytical solutions for the velocity and temperature fields are gotten by the DTM-BF which is an analytical method based on the differential transformation method (DTM) and basis functions. The results obtained by the DTM-BF are in good agreement with those presented by the numerical method. The effects of the various parameters which determine the velocity and temperature fields are shown by plotting graphs and discussed in detail. Source


Liu Y.,North China Electrical Power University | Zhou J.,Wuhan Institute of Technology | Shen T.,Nanjing University of Technology
Materials and Design | Year: 2013

A theoretical model is proposed to study the influence of nano-metal particles (NMPs) on the fracture toughness of metal-ceramic composites (MCC). In the framework of the model, the crack tip intersects the grain boundary of the NMPs. Stress concentration at crack tip initiates edge dislocations which makes a shielding effect on the crack and leads to fracture toughness of the MCC. The dependence of critical crack intensity factors on grain size of the NMPs was calculated. The calculation suggested that the existence of the NMPs lead to an increase of critical crack intensity factors by 14%. © 2012 Elsevier Ltd. Source


Tian J.,North China Electrical Power University
Fuzzy Optimization and Decision Making | Year: 2011

Uncertain variables are measurable functions from uncertainty spaces to the set of real numbers. In this paper, some important inequalities of uncertain variables, for example, extension of Jensen's inequality, Liapounov's inequality, and refined Markov inequalities are presented. In addition, some mathematical properties of uncertain variables are also given and proven. © 2011 Springer Science+Business Media, LLC. Source


Cho Y.J.,Gyeongsang National University | Saadati R.,Islamic Azad University at Tehran | Wang S.,North China Electrical Power University | Wang S.,Gyeongsang National University
Computers and Mathematics with Applications | Year: 2011

In this paper, we introduce a concept of the c-distance in a cone metric space and, by using the concept of the c-distance, prove some fixed point theorems in ordered cone metric spaces. © 2010 Elsevier Ltd. All rights reserved. Source


Varhegyi G.,Hungarian Academy of Sciences | Bobaly B.,Hungarian Academy of Sciences | Jakab E.,Hungarian Academy of Sciences | Chen H.,North China Electrical Power University
Energy and Fuels | Year: 2011

The pyrolysis of four biomasses (corn stalk, rice husk, sorghum straw, and wheat straw) was studied at different temperature-time functions in an inert gas flow by thermogravimetric analysis (TGA). Linear and stepwise heating programs were employed. A distributed activation energy model (DAEM) with three pools of reactants (three pseudocomponents) was used because of the complexity of the biomass samples of agricultural origin. Compensation effects were observed between the kinetic parameters as in the works of other investigators. The compensation effects result in ambiguous parameter values; hence, they were eliminated with a decrease in the number of unknown parameters. For this purpose, some of the kinetic parameters were assumed to be the same for the four biomasses. This approach also helps to express the similarities of the samples in the model. The 16 experiments were evaluated simultaneously by the method of least squares, yielding dependable kinetic parameters. The resulting models describe well the experimental data and are suitable for predicting experiments at higher heating rates. The checks on the prediction capabilities were considered to be an essential part of the model verification. © 2010 American Chemical Society. Source


Wang Z.,Anhui University of Science and Technology | Lu Q.,North China Electrical Power University | Zhu X.-F.,Anhui University of Science and Technology | Zhang Y.,Anhui University of Science and Technology
ChemSusChem | Year: 2011

Sulfated zirconia was employed as catalyst for fast pyrolysis of cellulose to prepare levoglucosenone (LGO), a very important anhydrosugar for organic synthesis. The yield and the selectivity of LGO were studied in a fixed-bed reactor at different temperatures and cellulose/catalyst mass ratios. The experiments of catalyst recycling were also carried out. The results displayed that from 290 to 400 °C, the liquid and solid accounted for more than 95 wt % of products, and the higher temperature led to more liquid and less solid products. The introduction of SO4 2-/ZrO2 could promote cellulose conversion and LGO production. The temperature had a similar effect on the yield and selectivity of LGO at different cellulose/catalyst mass ratios. The maximum yield was obtained at 335 °C. Although the structure of the parent ZrO2 was retained after recycles, which was confirmed by X-ray diffraction and N2 adsorption-desorption measurements, the activity of SO4 2-/ZrO2 could only be partially recovered by simply calcination. The catalytic activity decrease could be mainly attributed to SO4 2- leaching, and the activity could be restored by further impregnation of H2SO4. It′s not diamond, it′s zirconia: SO4 2-/ZrO2 is an efficient catalyst for the production of levoglucosenone by fast pyrolysis of cellulose admixing catalysts. The optimal temperature for preparation of levoglucosenone is in the range of 320-350 °C. In the presence of the SO4 2-/ZrO2, the levoglucosenone content of pyrolysis liquid is greatly increased at 335 °C compared to pure cellulose. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source