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Beijing, China

Beijing University of Technology , also called Beijing Polytechnic University or Bei Gong Da , is recognized as one of the Project 211 universities. The University has established a multidisplinary academic structure, offering a variety of programs and is involved in diversified research in the fields of Science, Engineering, Economics, Management, Liberal Arts, and Law. Wikipedia.

Kan M.,Peking University | Kan M.,Sungkyunkwan University | Adhikari S.,Sungkyunkwan University | Sun Q.,Peking University | Sun Q.,Beijing University of Technology
Physical Chemistry Chemical Physics | Year: 2014

Using density functional theory combined with Monte Carlo (MC) simulations, we show that the two dimensional (2D) MnS2 and MnSe2 sheets are ideal magnetic semiconductors with long-range magnetic ordering and high magnetic moments (3 μB per unit cell), where all the Mn atoms are ferromagnetically coupled, and the Curie temperatures (TC) estimated for MnS2 and MnSe2 by the MC simulations are 225 and 250 K, respectively, which can be further increased to 330 K and 375 K by applying 5% biaxial tensile strains. © 2014 the Owner Societies.

Ren X.-L.,Beihang University | Geng L.-S.,Beihang University | Meng J.,Beihang University | Meng J.,Beijing University of Technology | Meng J.,Stellenbosch University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

The scalar strangeness content of the nucleon, characterized by the so-called strangeness-nucleon sigma term, is of fundamental importance in understanding its sea-quark flavor structure. We report a determination of the octet baryon sigma terms via the Feynman-Hellmann theorem by analyzing the latest high-statistics nf=2+1 lattice QCD simulations with covariant baryon chiral perturbation theory up to next-to-next-to-next-to-leading order. In particular, we predict σπN=55(1)(4)MeV and σsN=27(27)(4)MeV, while the first error is statistical and the second systematic due to different lattice scales. The predicted σsN is consistent with the latest LQCD results and the results based on the next-to-next-to-leading order chiral perturbation theory. Several key factors in determining the sigma terms are systematically taken into account and clarified for the first time, including the effects of lattice scale setting, systematic uncertainties originating from chiral expansion truncations, and constraint of strong-interaction isospin breaking effects. © 2015 American Physical Society.

Shao D.,Rensselaer Polytechnic Institute | Yu M.,Rensselaer Polytechnic Institute | Yu M.,Beijing University of Technology | Lian J.,Rensselaer Polytechnic Institute | Sawyer S.,Rensselaer Polytechnic Institute
Nanotechnology | Year: 2013

A high sensitivity, fast ultraviolet (UV) photodetector was fabricated from WO3 nanodiscs (NDs)/reduced graphene oxide (RGO) composite material. The WO3 NDs/reduced GO composite material was synthesized using a facile three-step synthesis procedure. First, the Na2WO 4/GO precursor was synthesized by homogeneous precipitation. Second, the Na2WO4/GO precursor was transformed into H 2WO4/GO composites by acidification. Finally, the H 2WO4/GO composites were reduced to WO3 NDs/RGO via a hydrothermal reduction process. The UV photodetector showed a fast transient response and high responsivity, which are attributed to the improved carrier transport and collection efficiency through graphene. The excellent material properties of the WO3 NDs/RGO composite demonstrated in this work may open up new possibilities for using WO3 NDs/RGO for future optoelectronic applications. © 2013 IOP Publishing Ltd.

Yang W.-C.,Chinese Academy of Geological Sciences | Sun Y.-Y.,Beijing University of Technology | Yu C.-Q.,Chinese Academy of Geological Sciences
Chinese Journal of Geophysics (Acta Geophysica Sinica) | Year: 2015

The Crust of Qinghai-Tibet Plateau is the product of collision between the Eurasia and India plates. Though some geophysical profiles have been performed to reveal the lithospheric structures, but very few work on deep plane mapping of whole plateau have been done. We study 3D crustal density disturbance of the plateau and present corresponding deformation belt maps for the upper, middle and lower crust respectively. We apply a method called the multi-scale scratch analysis to Qinghai-Tibet Plateau for delineation of deformation belts and division of continental tectonic units. The method of regional gravity data processing have been developed by our group, combining theories based on multi-scale wavelet analysis, spectral analysis of potential fields, geophysical inversion, and surface scratch analysis. The multi-scale wavelet analysis, spectral analysis of potential fields and inversion produce density disturbance maps on planes of different depth, which are used as input for scratch analysis to compute the ridge coefficient images. The ridge coefficient images for each equivalent layer indicate the crustal deformation belts at certain depth in the crust. The sharp edges in the ridge-coefficient images reflect the boundaries between different secondary structural units. The ridge coefficient images show the variation of the deformation belts in Qinghai-Tibet Plateau from the upper crust to the lower, as well as the geometry of main crustal terrans exist in the plateau. The deformation belts are very dense and thin in the upper crust, but become coarse and thick in the lower crust, demonstrating the vertical variation modes of the deformation belt similar to a tree that has a coarse and thick trunk in its lower part and dense and thin branches in its top. The dense and thin deformation areas in the upper correspond to crustal shortening areas in the plateau. The thick and continuous deformation belts in the lower crust indicate structural framework of the plateau. The ridge-edge coefficient images show terrane boundaries at different depth in the crust and coincide with sharp varying zones of the density disturbance, therefore presenting the tectonic division of lower-crust units. The divided high-density terrans in the plateau include Himalaya, Kashmir, Chayuhe, Qiangtang, Qaidam and Baryanhar. Among them the Qiangtang, Qaidam and Baryanhar terrans have the crust roots of high density in the lower crust. As Kashmir and Chayuhe terrans are solid and of very high density, they were not easy to be crashed during the collision between the India and Eurasia Plates, playing the special effect in formation of the western and eastern structural knots, respectively. The method of multi-scale scratch analysis has been successfully applied to Qinghai-Tibet Plateau for delineation of crustal deformation belts and division of secondary tectonic units, providing some new evidences for understanding the deep structures in the plateau. © 2015, Science Press. All right reserved.

Zhang Z.,Beijing University of Technology | Sun H.,Beijing Institute of Technology | Peng L.,University of Surrey
Differential Geometry and its Application | Year: 2013

In this paper, we use natural gradient algorithm to control the shape of the conditional output probability density function for the stochastic distribution systems from the viewpoint of information geometry. The considered system here is of multi-input and single output with an output feedback and a stochastic noise. Based on the assumption that the probability density function of the stochastic noise is known, we obtain the conditional output probability density function whose shape is only determined by the control input vector under the condition that the output feedback is known at any sample time. The set of all the conditional output probability density functions forms a statistical manifold (M), and the control input vector and the output feedback are considered as the coordinate system. The Kullback divergence acts as the distance between the conditional output probability density function and the target probability density function. Thus, an iterative formula for the control input vector is proposed in the sense of information geometry. Meanwhile, we consider the convergence of the presented algorithm. At last, an illustrative example is utilized to demonstrate the effectiveness of the algorithm. © 2013 Elsevier B.V.

Atyabi A.,Flinders University | Luerssen M.H.,Flinders University | Powers D.M.W.,Flinders University | Powers D.M.W.,Beijing University of Technology
Neurocomputing | Year: 2013

Subject transfer is a growing area of research in EEG aiming to address the lack of having enough EEG samples required for BCI by using samples originating from individuals or groups of subjects that previously performed similar tasks. This paper investigates the feasibility of two frameworks for enhancing subject transfer through a 90%+ reduction of EEG features and electrodes using Particle Swarm Optimization (PSO). In the first framework, electrodes and features selected by PSO from individual subjects are combined into a single ". meta-mask" to be applied to the new subject. In the second framework, the preprocessed EEG of multiple subjects is concatenated into a single ". super subject", from which PSO selects electrodes and features for use on the new subject. The study is focused on finding the optimal mixture of subjects in either of the proposed frameworks in addition to investigating the impact of various electrode and features selections. The results indicate the important role of having an optimal mixture of expertise in the subjects' data. © 2013 Elsevier B.V.

Makal T.A.,Texas A&M University | Li J.-R.,Beijing University of Technology | Lu W.,Texas A&M University | Zhou H.-C.,Texas A&M University
Chemical Society Reviews | Year: 2012

The need for alternative fuels is greater now than ever before. With considerable sources available and low pollution factor, methane is a natural choice as petroleum replacement in cars and other mobile applications. However, efficient storage methods are still lacking to implement the application of methane in the automotive industry. Advanced porous materials, metal-organic frameworks and porous organic polymers, have received considerable attention in sorptive storage applications owing to their exceptionally high surface areas and chemically-tunable structures. In this critical review we provide an overview of the current status of the application of these two types of advanced porous materials in the storage of methane. Examples of materials exhibiting high methane storage capacities are analyzed and methods for increasing the applicability of these advanced porous materials in methane storage technologies described. This journal is © The Royal Society of Chemistry 2012.

Chen H.-X.,Beihang University | Chen W.,University of Saskatchewan | Liu X.,Lanzhou University | Steele T.G.,University of Saskatchewan | And 2 more authors.
Physical Review Letters | Year: 2015

Inspired by Pc(4380) and Pc(4450) recently observed by LHCb, a QCD sum rule investigation is performed, by which they can be identified as exotic hidden-charm pentaquarks composed of an anticharmed meson and a charmed baryon. Our results suggest that Pc(4380) and Pc(4450) have quantum numbers JP=3/2- and 5/2+, respectively. Furthermore, two extra hidden-charm pentaqurks with configurations D¯Σc∗ and D¯∗Σc∗ are predicted, which have spin-parity quantum numbers JP=3/2- and JP=5/2+, respectively. As an important extension, the mass predictions of hidden-bottom pentaquarks are also given. Searches for these partners of Pc(4380) and Pc(4450) are especially accessible at future experiments like LHCb and BelleII. © 2015 American Physical Society.

Chen R.,Lanzhou University | Liu X.,Nankai University | Li X.-Q.,Beijing University of Technology | Li X.-Q.,Peking University | Zhu S.-L.,Lanzhou University
Physical Review Letters | Year: 2015

The LHCb Collaboration at the Large Hadron Collider at CERN discovered two pentaquark states Pc(4380) and Pc(4450). These two hidden-charm states are interpreted as the loosely bound Σc(2455)D∗ and Σc∗(2520)D∗ molecular states in the boson exchange interaction model, which provides an explanation for why the experimental width of Pc(4450) is much narrower than that of Pc(4380). The discovery of the new resonances Pc(4380) and Pc(4450), indeed, opens a new page for hadron physics. The partners of Pc(4380) and Pc(4450) should be pursued in future experiments. © 2015 American Physical Society.

Liu Y.,Beijing University of Technology | Qin F.,Beijing University of Technology | Liu Y.,Tsinghua University | Cen Z.,Tsinghua University
Computational Mechanics | Year: 2010

In this paper, Daubechies (DB) wavelet is used for solution of 2D large deformation problems. Because the DB wavelet scaling functions are directly used as basis function, no meshes are needed in function approximation. Using the DB wavelet, the solution formulations based on total Lagrangian approach for two-dimensional large deformation problems are established. Due to the lack of Kroneker delta properties in wavelet scaling functions, Lagrange multipliers are used for imposition of boundary condition. Numerical examples of 2D large deformation problems illustrate that this method is effective and stable. © 2009 Springer-Verlag.

Kan M.,Peking University | Zhou J.,Peking University | Sun Q.,Peking University | Sun Q.,Beijing University of Technology | And 3 more authors.
Journal of Physical Chemistry Letters | Year: 2013

The Mn atom, because of its special electronic configuration of 3d 54s2, has been widely used as a dopant in various two-dimensional (2D) monolayers such as graphene, BN, silicene and transition metal dichalcogenides (TMDs). The distributions of doped Mn atoms in these systems are highly sensitive to the synthesis process and conditions, thus suffering from problems of low solubility and surface clustering. Here we show for the first time that the MnO2 monolayer, synthetized 10 years ago, where Mn ions are individually held at specific sites, exhibits intrinsic ferromagnetism with a Curie temperature of 140 K, comparable to the highest TC value achieved experimentally for Mn-doped GaAs. The well-defined atomic configuration and the intrinsic ferromagnetism of the MnO2 monolayer suggest that it is superior to other magnetic monolayer materials. © 2013 American Chemical Society.

Jin S.,Beijing University of Civil Engineering and Architecture | Jin S.,University of Tennessee at Knoxville | Zhang J.,Beijing University of Technology | Huang B.,University of Tennessee at Knoxville
Construction and Building Materials | Year: 2013

Pore structure is one of the major characteristics influencing the freeze-thaw resistance of concrete. Although the air-void spacing factor associated to the porosity features of concrete is known as a widely used parameter to assess the freeze-thaw resistance, controversies on the determination of critical values of air-void spacing factor still exist in many related studies. Moreover, it is reported that the pore-size distribution in concrete also significantly affects its freeze-thaw resistance. In this study, a fractal model was established to characterize the air voids size-distribution in concrete, and the corresponding fractal dimension obtained from the fractal model was validated for its effectiveness in describing the air voids size-distribution quantitatively. By comparison to a fractal model presented in a previous study, the fractal model proposed in this study was found more reasonable and reliable. Based on the theoretical principle, correlations between air voids size-distributions and the measured freeze-thaw resistances of concrete were established through laboratory experiments. The results revealed that air voids size-distribution exhibited more significant influence on the freeze-thaw resistance of concrete than the air-void spacing. Furthermore, a regression equation with fairly high correlation coefficient between the fractal dimension of air voids size-distribution and the durability factors of concrete was obtained from the results. © 2013 Elsevier Ltd. All rights reserved.

Tong H.,Chinese Academy of Sciences | Xu R.X.,Beijing University of Technology
Astrophysical Journal Letters | Year: 2012

The spin-down behaviors of SGR 0418+5729 are investigated. The pulsar spin-down model of Contopoulos and Spitkovsky is applied to SGR 0418+5729. It is shown that SGR 0418+5729 lies below the pulsar death line and its rotation-powered magnetospheric activities may therefore have stopped. The compact star is now spun down by the magnetic dipole moment perpendicular to its rotation axis. Our calculations show that under these assumptions there is the possibility of SGR 0418+5729 having a strong dipole magnetic field, if there is a small magnetic inclination angle. Its dipole magnetic field may be much higher than the characteristic magnetic field. Therefore, SGR 0418+5729 may be a normal magnetar instead of a low magnetic field magnetar. © 2012 The American Astronomical Society. All rights reserved.

Yue Y.,Beihang University | Zheng K.,Beijing University of Technology
Applied Physics Letters | Year: 2014

With electron-beam (e-beam) off, in-situ tensile experiments on amorphous silica nanowires (NWs) were performed inside a transmission electron microscope (TEM). By controlling the loading rates, the strain rate can be adjusted accurately in a wide range. The result shows a strong strain rate effect on the plasticity of amorphous silica NWs. At lower strain rate, the intrinsic brittle materials exhibit a pronounced elongation higher than 100% to failure with obvious necking near ambient temperature. At the strain rate higher than 5.23 × 10- 3/s, the elongation of the NW decreased dramatically, and a brittle fracture feature behavior was revealed. This ductile feature of the amorphous silica NWs has been further confirmed with the in-situ experiments under optical microscopy while the effect of e-beam irradiation could be eliminated. © 2014 AIP Publishing LLC.

Wang W.,Beijing University of Technology
Advances in High Energy Physics | Year: 2012

In this note we briefly review the recent studies of dark matter in the MSSM and its singlet extensions: the NMSSM, the nMSSM, and the general singlet extension. Under the new detection results of CDMS II, XENON, CoGeNT, and PAMELA, we find that (i) the latest detection results can exclude a large part of the parameter space which is allowed by current collider constraints in these models. The future SuperCDMS and XENON can cover most of the allowed parameter space; (ii) the singlet sector will decouple from the MSSM-like sector in the NMSSM; however, singlet sector makes the nMSSM quite different from the MSSM; (iii) the NMSSM can allow light dark matter at several GeV to exist. Light CP-even or CP-odd Higgs boson must be present so as to satisfy the measured dark matter relic density. In case of the presence of a light CP-even Higgs boson, the light neutralino dark matter can explain the CoGeNT and DAMA/LIBRA results; (iv) the general singlet extension of the MSSM gives a perfect explanation for both the relic density and the PAMELA result through the Sommerfeld-enhanced annihilation. Higgs decays in different scenario are also studied. © 2012 Wenyu Wang.

Kou J.-K.,Beijing University of Technology
Beijing Gongye Daxue Xuebao/Journal of Beijing University of Technology | Year: 2015

Smoothness of the regression function is unknown in practical applications, so it isn't reasonable to assume the smoothness. This paper investigates a regression model based on size-biased random samples, and proves the mean consistency of two wavelet estimators without assuming any smooth conditions of the regression function. Numerical experiments indicate that regression functions given by the two wavelet estimators are closer to the true regression function as the size of sample increasing. Especially, they are almost same as the true regression function when the size of sample is 1000. Numerical experiments support the main theorem. The results can be considered as a supplement of Chesneau and Shirazi's work. ©, 2015, Beijing University of Technology. All right reserved.

Jie S.,Beijing University of Technology
Journal of Microelectromechanical Systems | Year: 2012

A resist (ma-N 2403 and ZEP 520A7)-based convenient technology to fabricate air bridges on arbitrary substrate is proposed. It involves only two steps of electron-beam lithography. By changing the exposure dose during lithography, the resist can be cross-linked to different extent, and the permanently cross-linked polymer is used for piers. An evaporated 205-nm-thick Ti/Au thin film is used to construct the bridges. Typically, the air bridge is more than 18 μm long, 2 μm high, and 5 μm wide. Due to the accumulated strain in the metal, it naturally forms an arch bridge, rendering no need for critical point drying. The adhesion between the metal and the polymer is considerably strong, even surviving mild sonication. This letter should contribute to a facile technology for manufacturing air bridges for various applications in microelectromechanical systems. © 2012 IEEE.

Liu J.,Beijing University of Technology
Journal of Engineering Mathematics | Year: 2011

The dynamic fracture of a thin-walled structure that is mainly due to impact and explosive loading is studied. Use is made of a meshless SPH shell formulation based on Mindlin-Reissner's theory. The formulation is an extension of the continuum-corrected and stabilized SPH method allowing a thin structure to be modelled using only one particle characterizing the mean position of the shell surface. Fracture is based on an effective criterion similar to that of the visibility method. Four numerical examples are studied among which tearing of pre-notched plates, fracture due to impact loading and dynamic fracture of cylindrical shells. © 2010 Springer Science+Business Media B.V.

Lei J.,Beijing University of Technology | Zhang C.,University of Siegen | Bui T.Q.,Tokyo Institute of Technology
European Journal of Mechanics, A/Solids | Year: 2015

This paper aims to gain a deeper insight into the effects of the poling directions, the volume fractions and the combined loading parameters on the dynamic field intensity factors at the interfacial crack-tips in two dimensional, piecewise homogeneous and magnetoelectroelastic composite bi-materials under the combined magnetoelectromechanical impact loadings. For this purpose, a time-domain boundary element method (BEM) together with the sub-domain technique is applied. The present time-domain BEM uses a quadrature formula for the temporal discretization to approximate the convolution integrals and a collocation method for the spatial discretization. Quadratic quarter-point elements are implemented at the interfacial crack-tips. An explicit displacement extrapolating formula is proposed to determine the dynamic field intensity factors of stresses, electrical displacements and magnetic inductions at the interfacial crack-tips. Numerical examples for different poling directions, different volume fractions and different combined loading parameters are presented and discussed. Based on these numerical results, some useful conclusions are drawn on the effects of various material and loading combinations on the dynamic field intensity factors. © 2014 Elsevier Masson SAS. All rights reserved.

Yu C.,University of North Texas | Yan W.,Beijing University of Technology
Thin-Walled Structures | Year: 2011

This paper proposes a design method, based on the Effective Width Method, for determining the nominal distortional buckling strength of typical cold-formed steel C and Z sections subjected to bending. The method can be integrated into the classic effective width design provisions specified in AISI S100, and it allows the conventional design approach to cover more comprehensive limit states. The proposed method is calibrated by the flexural distortional buckling strength predicted by the Direct Strength Method. Comparison with experimental results indicates that the proposed method yields reasonable predictions for the flexural distortional buckling strength of industrial standard C and Z sections. The method offers the same level of accuracy and reliability as the Direct Strength Method. © 2010 Elsevier Ltd. All rights reserved.

Huang L.,University of Science and Technology Beijing | Huang L.,Beijing Institute of Technology | Cong D.Y.,University of Science and Technology Beijing | Suo H.L.,Beijing University of Technology | Wang Y.D.,University of Science and Technology Beijing
Applied Physics Letters | Year: 2014

We report a giant effective magnetic refrigeration capacity in a Ni 40Co10Mn40Sn10 multifunctional alloy. With a large magnetization difference between austenite and martensite, this alloy shows a strong magnetic field dependence of transformation temperatures. Complete magnetic-field-induced structural transformation and a considerable magnetic entropy change are observed in a broad operating temperature window of 33K near room temperature. Consequently, an effective magnetic refrigeration capacity of 251J/kg for 5T is achieved, which is the largest value for Ni-Mn-based Heusler alloys and comparable to that of the high-performance Gd-Si-Ge and La-Fe-Si magnetocaloric materials. Incorporating the advantages of low cost and non-toxicity, this alloy shows very promising prospects for room-temperature magnetic refrigeration. © 2014 AIP Publishing LLC.

Li Y.,Beijing University of Technology | Chen B.,Shanghai JiaoTong University
Construction and Building Materials | Year: 2013

Magnesium phosphate cement (MPC) was prepared with dead burned magnesia oxide (MgO), potassium di-hydrogen phosphate (KH2PO4) and some retarders in a given proportion used in the same manner as Portland cement. Factors such as the w/c ratio, casting temperature and fly ash contents that affect the properties of MPC were studied in this paper. The experimental results demonstrate that the setting time was significantly affected by the w/c ratio and casting temperature. Adding fly ash can increase the setting time and flowability of fresh MPC paste. The compressive strengths of MPC paste prepared using various w/c ratios were measured at ages of 3 h, 1 d, 7 d and 28 d. The 3-, 7- and 28-day compressive strengths of MPC mortar prepared using various fly ash contents were also measured. The compressive strength of MPC paste decreased with an increasing w/c ratio, and the aged compressive strengths of MPC mortar increased with increasing fly ash content. The results also indicate that adding fly ash can improve the water resistance and dry shrinkage of MPC mortar. Finally, the hydrate products were analyzed using XRD and SEM. © 2013 Elsevier B.V. All rights reserved.

Wei Y.,China University of Petroleum - Beijing | Liu J.,China University of Petroleum - Beijing | Zhao Z.,China University of Petroleum - Beijing | Chen Y.,Pennsylvania State University | And 4 more authors.
Angewandte Chemie - International Edition | Year: 2011

(Figure Presented) The catalyst support 3DOM LaFeO3 contains highly ordered macropores that are connected with each other by small windows. 3DOM LaFeO3 supported gold catalysts, which combine the advantages of good contact by the macroporous support and highly active sites for activation of O2 by gold clusters, exhibit super catalytic performance for soot oxidation. © 2011 Wiley-VCH Verlag GmbH & Co. KGaA.

Li Y.P.,North China Electrical Power University | Huang G.H.,North China Electrical Power University | Nie S.L.,Beijing University of Technology | Chen X.,Xinjiang Institute of Ecology and Geography
Agricultural Water Management | Year: 2011

In regional water management systems, various uncertainties may be derived from random feature of resource conditions and natural processes, errors in estimated modeling parameters, as well as imprecision or fuzziness human-induced. This leads to difficulties in formulating and solving the resulting regional water management problems. In this study, a robust multistage interval-stochastic programming (RISP) method is developed for dealing with vague and random information in regional water management systems. The decision variables are useful for justifying and/or adjusting the decision schemes for agricultural activities through the incorporation of their implicit knowledge on regional water management. Different policies for agricultural water supply have been analyzed. The results can help to identify desired water-allocation schemes for agricultural sustainable development that the prerequisite water demand for supporting crops' survival can be guaranteed when the water resource is scarce. © 2011 Elsevier B.V.

Guihe W.,Beijing University of Technology
Electronic Journal of Geotechnical Engineering | Year: 2015

Unstable slopes have been a potential threat to human lives and properties, especially in the densely-populated places. Therefore, dangerous slopes must be treated with proper and flexible measurements according to diverse forms of slope disasters and complicated geological conditions, which prove to be a demanding and heavy-loaded job. This paper analyzes the characteristics and a variety of treating measurements with the particular case of dangerous slopes of the fire-prevention road of Fragrant Hill North Ditch, and proposes a comprehensive treating plan combining anchoring, anti-slide piles, concrete surface layers and biological control measures. Key control points are monitored after the construction of treating project, with the result showing that the slopes remain stable and the supporting structure prove to be a guarantee to the safety of slopes. © 2015 ejge.

Yu H.-B.,Beijing University of Technology
Kongzhi yu Juece/Control and Decision | Year: 2013

The effect of risk aversion and demand uncertainty in inventory system is studied. The monotonicities of the optimal order quantity and optimal profit on penalty cost and risk level are obtained. By using stochastic comparison, larger demand leads to high optimal order quantity, and larger demand leads to higher optimal profit when the penalty cost is set to zero. It is proved that the profit will decrease when the demand variability increases, and the corresponding sufficient conditions and/or necessary and sufficient conditions are given. Furthermore, a class of distributions exist such that larger demand variability leads to higher optimal profit. Several examples are provided to illustrate the obtained results.

Chang L.,Beijing University of Technology
Proceedings - IEEE 2011 10th International Conference on Electronic Measurement and Instruments, ICEMI 2011 | Year: 2011

With the development of communication technology, modern wireless communication systems gradually operate in increasingly high frequency bands. In order to meet the needs of research on wireless channel characteristics in high frequency bands, this paper proposes an efficient and convenient channel measurement scheme which accomplished the measurement of typical indoor office environment at 6.25 GHz using high-performance vector network analyzer R&S ZVT-8 and automatic control software Labview. Besides, the article presents the method of data processing following the frequency-domain channel measurement campaign. On the basis of measurement results analysis, the indoor wireless channel large scale propagation characteristics at 6.25GHz are extracted and briefly reported here, too. © 2011 IEEE.

Wang Y.,Beijing University of Technology
Zidonghua Xuebao/ Acta Automatica Sinica | Year: 2010

Due to the limitation of the present techniques and facilities for data collection and various interferences, the data obtained are often distorted and noised, directly influencing the result of subsequent data analysis. The conventional approaches to outlier removal either assume that the data follow a certain known distribution or deal with the data that are from a single distribution, resulting in a reduced credibility of the data processed. This paper proposes a novel method to remove outliers based on density estimation and it has been applied to real-world traffic data. By comparison with the conventional approach, the experimental results indicate that the proposed algorithm is capable of detecting and removing outliers effectively for the data that may follow different unknown distributions, and the processed data retain the original and significant characteristics possessed by the system. Copyright © 2010 Acta Automatica Sinica. All rights reserved.

Li A.,Xiamen University | Xu R.-X.,Beijing University of Technology | Lu J.-F.,Xiamen University
Monthly Notices of the Royal Astronomical Society | Year: 2010

We investigate the stability of strange quark matter and the properties of the corresponding strange stars for a wide range of quark mass scalings. The calculations show that the resulting maximum mass always lies between 1.5 M⊙ and 1.8 M⊙ for all the scalings chosen here. Strange star sequences with a linear scaling support the lowest gravitational masses, and a change (increase or decrease) of the scaling around the linear scaling leads to a higher maximum mass. Radii always decrease with the mass scaling. Thus, the larger the scaling, the faster the star might spin. In addition, the variation of the scaling causes an order of magnitude change of the strong electric field on the quark surface. This field is essential to the support of possible crusts of strange stars against gravity and thus may have some astrophysical implications. © 2010 The Authors. Journal compilation © 2010 RAS.

Yan P.F.,CAS Shenyang Institute of Metal Research | Du K.,CAS Shenyang Institute of Metal Research | Sui M.L.,Beijing University of Technology
Acta Materialia | Year: 2010

A martensitic transformation from the α to the γ phase of aluminum oxide was observed by transmission electron microscopy (TEM) upon rapid heating induced by pulsed laser irradiation. Two variants possessing a twin relationship were found in the product. Highresolution TEM reveals that the transformation is achieved via the glide of quarter partial dislocations on every other basal plane of α-Al 2O 3. The high thermal stress caused by pulsed laser irradiation is believed to be the main driving force of the phase transformation. This martensitic transformation is associated with a positive volume change and substantial shear strain. The overall shear strain could be minimized by the self-accommodating variants. These characteristics suggest potential application of the martensitic transformation for transformation toughening in ceramic materials. © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Su W.-J.,Kings College | W Zu J.,Beijing University of Technology
Smart Materials and Structures | Year: 2014

In this paper, a novel bi-directional piezoelectric energy harvester which can harvest vibration energy bi-directionally is introduced and investigated theoretically and experimentally. The proposed harvester is composed of two sub-systems: a main beam to generate electricity and a spring-mass oscillator to trigger the vibration of the main beam from an additional direction by using magnets to couple the two sub-systems. The theoretical model is built on the basis of the Euler-Bernoulli beam theory and the magnetic charge model. A prototype is fabricated to test the performance of the harvester experimentally. Linear upward and downward frequency sweeps are used to obtain the frequency responses. The experimental results show good agreement with the theoretical model under frequency sweeps. A comparison with a beam-beam bi-directional piezoelectric energy harvester is also performed experimentally. Although both bi-directional piezoelectric energy harvesters exhibit the capability of harvesting vibration energy in two orthogonal directions, the beam-spring energy harvester shows a more consistent performance in both directions as regards the bandwidth and amplitude of the frequency responses. © 2014 IOP Publishing Ltd.

Studies of functional modules in a Protein-Protein Interaction (PPI) network contribute greatly to the understanding of biological mechanisms. With the development of computing science, computational approaches have played an important role in detecting functional modules. We present a new approach using multi-agent evolution for detection of functional modules in PPI networks. The proposed approach consists of two stages: the solution construction for agents in a population and the evolutionary process of computational agents in a lattice environment, where each agent corresponds to a candidate solution to the detection problem of functional modules in a PPI network. First, the approach utilizes a connection-based encoding scheme to model an agent, and employs a random-walk behavior merged topological characteristics with functional information to construct a solution. Next, it applies several evolutionary operators, i.e., competition, crossover, and mutation, to realize information exchange among agents as well as solution evolution. Systematic experiments have been conducted on three benchmark testing sets of yeast networks. Experimental results show that the approach is more effective compared to several other existing algorithms. The algorithm has the characteristics of outstanding recall, F-measure, sensitivity and accuracy while keeping other competitive performances, so it can be applied to the biological study which requires high accuracy.

Lansberg J.-P.,University Paris - Sud | Shao H.-S.,Beijing University of Technology | Shao H.-S.,CERN
Physical Review Letters | Year: 2013

We proceed for the first time to the evaluation of the Born cross section for J/ψ+ηc production, namely, via g+g→J/ ψ+ηc+g, and show that it has a harder PT spectrum than the J/ψ-pair yield at the Born level. If one stuck to a comparison at the Born level, one would conclude that J/ψ+ηc production would surpass that of J/ψ+J/ψ at large PT. This is nonetheless not the case since J/ψ-pair production, as for single J/ψ, receives leading-PT contributions at higher orders in αs. We also present the first evaluation of these leading-PT next-to-leading order contributions. These are indeed significant for increasing PT and are of essential relevance for comparison with forthcoming data. We also compute kinematic correlations relevant for double-parton-scattering studies. Finally, we evaluate the polarization of a J/ψ accompanied by either an ηc or a J/ψ and another light parton. These results may be of great help to understand the polarization of quarkonia produced at high energies. © 2013 American Physical Society.

Liu H.L.,Xian Jiaotong University | Xu F.R.,Beijing University of Technology
Physical Review C - Nuclear Physics | Year: 2013

Configuration-constrained potential-energy-surface calculations with reflection asymmetry show enhanced octupole correlations in the Kπ=6 - states with configuration ν5/2+[633]⊠- ν7/2-[743] in N=142,144 isotones, where a 33.5-μs isomer has been observed in 234U. High-K isomeric states in other nuclei around 240Pu are calculated to have reflection-symmetric deformations with excitation energies, in agreement with available data. © 2013 American Physical Society.

Gao J.,Southern Methodist University | Li C.S.,Beijing University of Technology | Li C.S.,Peking University | Zhu H.X.,SLAC
Physical Review Letters | Year: 2013

We present the complete calculation of the top-quark decay width at next-to-next-to-leading order in QCD, including next-to-leading electroweak corrections as well as finite bottom quark mass and W boson width effects. In particular, we also show the first results of the fully differential decay rates for the top-quark semileptonic decay t→W+(l+ν)b at next-to-next-to-leading order in QCD. Our method is based on the understanding of the invariant mass distribution of the final-state jet in the singular limit from effective field theory. Our result can be used to study arbitrary infrared-safe observables of top-quark decay with the highest perturbative accuracy. © 2013 American Physical Society.

Ye Y.L.,Beijing University of Technology
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms | Year: 2013

This report gives a brief overview of the RIB (Rare Isotope Beam) facilities in Asia, including its historical development, current situation and future plans. The RIB facilities are presently concentrated in Japan, China and Australia, but new projects or upgrade programs are proposed also from Korea and India. Experimental instrumentations are outlined together with related major physics topics.© 2013 Elsevier B.V. All rights reserved.

Zhang Y.,China Railway No.5 Engineering Group Co. | Xing B.,Beijing University of Technology | Song C.,Chinese Institute of Crustal Dynamics
Modern Tunnelling Technology | Year: 2014

Affected by staged excavation, stress-strain nonlinear variation may occur inside the surrounding rock of a tunnel. In high-ground-stress areas, this mechanical effect tends to be even more obvious and can cause serious geological disasters like rockbursts and wall caving, etc. Taking the construction of the Meihuashan tunnel in Fujian as an example, this paper analyzes the interaction of the excavation steps and the change rule of the 3D stress field and strain field in the tunnel by establishing a 3D excavation numerical model with 3D -Sigma software, using the measured stress data as a boundary condition and determining the inputs of the rock mass with the Hoek -Brown strength criterion. The results show that: because of high ground stress, compressive stress concentration occurs at the tunnel crown and shear stress concentration occurs at the spandrel, which may cause brittle failure at the tunnel wall; previously excavated tunnel sections may be affected by subsequent excavation, making the stress concentration effect more obvious and the failure of the surrounding rock more serious; the actual rockburst locations correspond with the locations of maximum compressive stress concentration and maximum shear stress concentration in simulation analysis. The numerical simulation can clearly reveal the mechanism and the possible law of the rock burst, providing strong technical support for engineering applications.

Wang Y.-S.,Beijing University of Technology
Tien Tzu Hsueh Pao/Acta Electronica Sinica | Year: 2014

It has a great significance to analyze the elastic deformation of the vessel wall for cardiovascular diseases' clinical treatment and the selection of the surgical plan. On the premise of making reasonable assumptions, firstly, establish the deformation model of infinitesimal's displacement. Secondly, use the finite element analysis method to divide the area of the vessel wall into a number of triangular surface infinitesimal, export the triangular surface deformation model by the displacement functions of triangle's three vertices and three sides. Finally, this deformation model is verified by simulation, compared with the literature methods, this method shows that it is able to not only calculate the size but also show the direction of the strain and give the results of the strain in three directions. ©, 2014, Tien Tzu Hsueh Pao/Acta Electronica Sinica. All right reserved.

Zheng H.,Beijing University of Technology | Xu D.,CAS Wuhan Institute of Rock and Soil Mechanics
International Journal for Numerical Methods in Engineering | Year: 2014

Aiming to solve, in a unified way, continuous and discontinuous problems in geotechnical engineering, the numerical manifold method introduces two covers, namely, the mathematical cover and the physical cover. In order to reach the goal, some issues in the simulation of crack propagation have to be solved, among which are the four issues to be treated in this study: (1) to reduce the rank deficiency induced by high degree polynomials as local approximation, a new variational principle is formulated, which suppresses the gradient-dependent DOFs; (2) to evaluate the integrals with singularity of 1/r, a new numerical quadrature scheme is developed, which is simpler but more efficient than the existing Duffy transformation; (3) to analyze kinked cracks, a sign convention for argument in the polar system at the crack tip is specified, which leads to more accurate results in a simpler way than the existing mapping technique; and (4) to demonstrate the mesh independency of numerical manifold method in handling strong singularity, a mesh deployment scheme is advised, which can reproduce all singular locations of the crack with regard to the mesh. Corresponding to the four issues, typical examples are given to demonstrate the effectiveness of the proposed schemes. © 2014 John Wiley & Sons, Ltd.

Li B.,Johns Hopkins University | Yan P.F.,CAS Shenyang Institute of Metal Research | Sui M.L.,Beijing University of Technology | Ma E.,Johns Hopkins University
Acta Materialia | Year: 2010

We present transmission electron microscopy (TEM) observations of stacking faults (SFs) and their interactions with pyramidal dislocations, in plastically deformed polycrystalline pure magnesium. We have observed well-defined fringes as well as streaking in diffraction patterns, typical of SFs. The basal SFs are decorated by a large number of dark speckles, which are created by the interaction with pyramidal dislocations that have both 〈c〉 and 〈a〉 components as revealed by our contrast analysis. The SFs do not appear to result from the splitting of unit dislocations, as the SFs are relatively wide and no dislocation nodes were observed. By tilting the specimen systematically inside TEM, the SFs and the associated dislocations in Mg are found to exhibit a rich variety of features in terms of their morphology and diffraction contrast. © 2009 Acta Materialia Inc.

Ji Q.,CAS Beijing National Laboratory for Molecular | Zhang Y.,CAS Beijing National Laboratory for Molecular | Zhang Y.,Peking University | Gao T.,CAS Beijing National Laboratory for Molecular | And 10 more authors.
Nano Letters | Year: 2013

Molybdenum disulfide (MoS2) is back in the spotlight because of the indirect-to-direct bandgap tunability and valley related physics emerging in the monolayer regime. However, rigorous control of the monolayer thickness is still a huge challenge for commonly utilized physical exfoliation and chemical synthesis methods. Herein, we have successfully grown predominantly monolayer MoS2 on an inert and nearly lattice-matching mica substrate by using a low-pressure chemical vapor deposition method. The growth is proposed to be mediated by an epitaxial mechanism, and the epitaxial monolayer MoS2 is intrinsically strained on mica due to a small adlayer-substrate lattice mismatch (∼2.7%). Photoluminescence (PL) measurements indicate strong single-exciton emission in as-grown MoS2 and room-temperature PL helicity (circular polarization ∼0.35) on transferred samples, providing straightforward proof of the high quality of the prepared monolayer crystals. The homogeneously strained high-quality monolayer MoS2 prepared in this study could competitively be exploited for a variety of future applications. © 2013 American Chemical Society.

Mao B.,Case Western Reserve University | Chuang C.-H.,Case Western Reserve University | Lu F.,Case Western Reserve University | Lu F.,Nanjing University | And 4 more authors.
Journal of Physical Chemistry C | Year: 2013

AgInS2-ZnS (AIZS) nanocrystals (NCs) were synthesized using a simple one-step approach by heating a Ag/In/Zn/S solution to 210 C providing highly tunable photoluminescence (PL). The incorporation of Zn even at low temperatures (∼150 C) and the increased cation exchange of silver by zinc at higher temperatures strongly influence the optical properties of the resulting NCs. The correlation between synthesis parameters and resulting optical properties provided insights on the growth and stability of ternary and quaternary semiconductors. Systematic investigation with time-resolved spectroscopy showed distinguishable PL behaviors between developing and fully grown AIZS NCs. Attempts to coat as-prepared AgInS2 NCs resulted in the same PL behavior as the one-step reaction product indicating that Zn readily exchanges with Ag ions even when not directly incorporated in the initial reaction mixture. Even with a low amount of zinc, the fully grown AIZS NCs showed improved PL QYs and single exponential decay behavior with long PL lifetimes. Control of the optical properties of these NCs makes them potentially useful for applications in photovoltaics and bioimaging particularly in light of their nontoxicity. © 2012 American Chemical Society.

Chow W.K.,Hong Kong Polytechnic University | Li J.,Beijing University of Technology
Building and Environment | Year: 2011

Sizing of horizontal ceiling vent in a tall atrium is usually based on vent flow models with unidirectional flow. This is only good for natural vents with large pressure differences between inside and outside. For low pressure differential across the horizontal ceiling vent as experienced in some atrium fires, bidirectional smoke flow rates were observed. The extraction rate through the vent would be reduced, giving poor performance of the smoke exhaust system. Bidirectional flow across a ceiling vent will be discussed in this paper. Models available in the literature will be briefly reviewed first. A new model was developed on studying effects of bidirectional flow across a horizontal vent on the smoke layer interface height. A critical pressure difference between inside and outside across the vent can be estimated on inducing bidirectional flows. The approach is illustrated with an example sizing calculation for a cubic atrium commonly found in Hong Kong. © 2011 Elsevier Ltd.

Wang Y.-Z.,Harbin Institute of Technology | Li F.-M.,Beijing University of Technology
International Journal of Non-Linear Mechanics | Year: 2014

Based on the nonlocal continuum theory, the nonlinear primary resonance of nano beam with the axial initial load is investigated. The amplitude-frequency response for the primary resonance is derived with the multiple scale method and the stability is analyzed. The nonlinear primary resonance of nano beam is discussed with the influences of small scale effect, axial initial load, mode number, Winkler foundation modulus and the ratio of the length to the diameter. From the results, the typical hardening nonlinearity can be observed. Moreover, some significant and interesting nonlinear phenomena can be found for the primary resonance of nano beam. This work is expected to be useful for the design and analysis for the nonlinear dynamic behaviors of structures at nano scales. © 2014 Published by Elsevier Ltd. All rights reserved.

Feng D.,Texas A&M University | Gu Z.-Y.,Texas A&M University | Li J.-R.,Texas A&M University | Li J.-R.,Beijing University of Technology | And 3 more authors.
Angewandte Chemie - International Edition | Year: 2012

Biomimetic MOF: Extremely stable MOFs with different open metal sites and ultra-large 1D channels, PCN-222 (Fe, Mn, Co, Ni, Cu, and Zn), have been assembled with eight-connected Zr6 clusters and redox-active metalloporphyrin motifs. PCN-222(Fe) shows peroxidase-like activity in aqueous solution, exhibiting highly effective biomimetic oxidation on a number of substrates. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Zheng H.,Beijing University of Technology | Liu F.,CAS Wuhan Institute of Rock and Soil Mechanics | Li C.,CAS Wuhan Institute of Rock and Soil Mechanics
International Journal of Fracture | Year: 2014

In order to solve problems, from a continuum point of view and in a unified way, involving continuum and discontinuum deformation, and small deformation and large movement, the numerical manifold method (NMM) introduces two covers, namely the mathematical cover (MC) and the physical cover (PC). This study generates the MC with the influence domains of nodes in the moving least squares (MLS) interpolation instead of commonly-used finite element meshes, significantly simplifying the generation of PCs and the simulation of crack growth. Advantageous over the conventional meshfree method, the MLS-based NMM can naturally treat complex geometry without recourse to those complicated but contrived criteria or operations. Moreover, the treatment of large movement caused by cracking is much easier with the MLS-based NMM than with the FE-based NMM. © 2014, Springer Science+Business Media Dordrecht.

Zheng H.,Beijing University of Technology | Liu Z.,CAS Wuhan Institute of Rock and Soil Mechanics | Ge X.,CAS Wuhan Institute of Rock and Soil Mechanics
International Journal for Numerical Methods in Engineering | Year: 2013

For second-order problems, where the behavior is described by second-order partial differential equations, the numerical manifold method (NMM) has gained great success. Because of difficulties in the construction of the H 2-regular Lagrangian partition of unity subordinate to the finite element cover; however, few applications of the NMM have been found to fourth-order problems such as Kirchhoff's thin plate problems. Parallel to the finite element methods, this study constructs the numerical manifold space of the Hermitian form to solve fourth-order problems. From the minimum potential principle, meanwhile, the mixed primal formulation and the penalized formulation fitted to the NMM for Kirchhoff's thin plate problems are derived. The typical examples indicate that by the proposed procedures, even those earliest developed elements in the finite element history, such as Zienkiewicz's plate element, regain their vigor. © 2013 John Wiley & Sons, Ltd.

Hou Z.,Yantai University | Gong Q.,Beijing University of Technology | Sun Z.,Yantai University
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2011

Based on field investigation for tunnels at Jinping II Hydropower Station, four primary failure types of deep buried marble are classified and their failure mechanisms are analyzed: (1) The first one is tensile slabbing rockburst. The rock mass near tunnel wall is slabbed due to unloading of excavation; at the same time, the elastic strain energy is stored in the slabs. Then, when the strain energy is stored sufficiently, the energy is released suddenly and the rockburst occurs. (2) The second one is tensile slabbing spalling. The rock mass near tunnel wall is slabbed due to unloading of excavation. Then, the slabs bend to inner of the tunnel and break. At last, the instabilities of slabs appear and they collapse down from the tunnel wall. (3) The third one is shear rock burst. A potential wedge of rock is formed in the rock mass near the tunnel wall because of the shearing action; and at the same time, the elastic strain energy is stored in the wedge. Then, the wedge is pushed out from the tunnel wall and the rockburst occurs when the shear stress on the potential shear surface exceeds the shear strength of the rock mass. (4) The last one is shear spalling. A wedge of rock is formed in the rock mass near the tunnel wall. Then, the wedge is detaching gradually from the tunnel wall, and at last, the wedge collapse down from the bottom of the tunnel. The four failure types may occur separately or combinatorially. The occurrence frequency of tensile failure is higher than that of shear failure. The failure classification of deep buried marble is useful for understanding the failure mechanisms of depth buried and intact hard rock mass and tunnel support design.

Yang T.-Z.,Shenyang Aerospace University | Ji S.,Shenyang Aerospace University | Yang X.-D.,Beijing University of Technology | Fang B.,Shenyang Aerospace University
International Journal of Engineering Science | Year: 2014

The microfluid-induced nonlinear free vibration of microtubes is studied in this paper. A derivation of the nonlinear equation of motion is presented based on Hamilton's principle and a modified couple stress theory. The geometric nonlinearity, arising from the mid-plane stretching, is taken into account. The modified couple stress theory is used to capture the micro-structure dependent size effects when the microtubes are at micron- and submicron scales. The static postbuckling problem is then studied and the size-dependent postbuckling configurations are analyzed. The approximate solution to the nonlinear free vibration is obtained using the homotopy analysis method. The influences of internal material length scale parameter, outer diameter, flow velocity, and Poisson's ratio on the dynamic behavior are discussed in detail. © 2013 Elsevier Ltd. All rights reserved.

Tong H.,CAS Institute of High Energy Physics | Song L.M.,CAS Institute of High Energy Physics | Xu R.X.,Beijing University of Technology
Astrophysical Journal Letters | Year: 2010

Significant research in compact stars is currently focused on two kinds of enigmatic sources: anomalous X-ray pulsars (AXPs) and soft gamma-ray repeaters (SGRs). Although AXPs and SGRs are popularly thought to be magnetars, other models (e.g., the accretion model) for understanding the observations can still not be ruled out. It is worth noting that a non-detection in a Fermi/LAT observation of AXP 4U 0142+61 has been reported recently by Sasmaz Mus & Gogus. We propose here that Fermi/LAT observations may distinguish between the magnetar model and the accretion model for AXPs and SGRs. We explain how this null observation of AXP 4U 0142+61 favors the accretion model. Future Fermi/LAT observations of AXP 1E 1547.0-5408 and AXP 1E 1048.1-5937 are highly recommended. © 2010. The American Astronomical Society. All rights reserved.

Li X.,Beijing University of Technology | Wu C.,Shandong University | Li W.,Tianjin University
Jixie Gongcheng Xuebao/Journal of Mechanical Engineering | Year: 2012

Welding is one of the most important technologies of materials forming and processing in modern manufacturing industry, the development of welding technology is of very important significance in promoting China to be a manufacturing giant in the world. Based on the summary and analysis of the recent advances on welding?science and technology?in China, the future?development strategies on the relative fields are proposed. Due to steels still hold the dominant role in the basic structural materials, the study of welding metallurgy for the new generation steels and the development of high grade welding consumables are the key topics in welding manufacturing. China is now the largest electronic production site in the world, however, the study and development in lead-free soldering materials and lead-free packing technologies are the sole way to ensure China to be the largest green electronic producer. High energy density welding, such as laser beam welding and electron beam welding, is proven an advanced welding process which could increase the welding productivity remarkably, the study and application of such welding process in equipment manufacturing should be encouraged. The numerical simulation on welding process is beneficial in the understanding of the complex physical phenomena involved in welding, which also provides important and practical basic data. Significant progress in the simulation of thermal process, residual stress, deformation and welding metallurgy is made in China in the past years, nevertheless, the practical application of the above achievements should be further investigated. Achievements in research on automatic welding and intelligent welding have shown that the high productivity and welding quality could be reached by using welding automation, however, the integrated application of welding automation should be studied. The research and application on evaluation of integrity of welded structures should be emphasized in order to ensure fitness for purpose of such structures. © 2012 Journal of Mechanical Engineering.

Li Y.P.,North China Electrical Power University | Huang G.H.,North China Electrical Power University | Nie S.L.,Beijing University of Technology
Advances in Water Resources | Year: 2010

In this study, a fuzzy-boundary interval-stochastic programming (FBISP) method is developed for planning water resources management systems under uncertainty. The developed FBISP method can deal with uncertainties expressed as probability distributions and fuzzy-boundary intervals. With the aid of an interactive algorithm woven with a vertex analysis, solutions for FBISP model under associated α-cut levels can be generated by solving a set of deterministic submodels. The related probability and possibility information can also be reflected in the solutions for the objective function value and decision variables. The developed FBISP is also applied to water resources management and planning within a multi-reservoir system. Various policy scenarios that are associated with different levels of economic consequences when the pre-regulated water-allocation targets are violated are analyzed. The results obtained are useful for generating a range of decision alternatives under various system conditions, and thus helping decision makers to identify desired water resources management policies under uncertainty. © 2010 Elsevier Ltd.

Li A.X.,Beijing University of Technology
2015 11th Conference on Lasers and Electro-Optics Pacific Rim, CLEO-PR 2015 | Year: 2016

We demonstrate a miniature crystalline Raman laser operating at three discretely-tunable wavelengths in the green-yellow. Over 200 mW output powers were obtained for each wavelength with 3.8 W pumping. The threshold is below 0.4 W. © 2015 IEEE.

Yang Y.,Rice University | Fan X.,Rice University | Fan X.,Beijing University of Technology | Casillas G.,University of Texas at San Antonio | And 5 more authors.
ACS Nano | Year: 2014

Three-dimensional self-organized nanoporous thin films integrated into a heterogeneous Fe2O3/Fe3C-graphene structure were fabricated using chemical vapor deposition. Few-layer graphene coated on the nanoporous thin film was used as a conductive passivation layer, and Fe 3C was introduced to improve capacity retention and stability of the nanoporous layer. A possible interfacial lithium storage effect was anticipated to provide additional charge storage in the electrode. These nanoporous layers, when used as an anode in lithium-ion batteries, deliver greatly enhanced cyclability and rate capacity compared with pristine Fe2O 3: a specific capacity of 356 μAh cm-2 μm -1 (3560 mAh cm-3 or ∼1118 mAh g-1) obtained at a discharge current density of 50 μA cm-2 (∼0.17 C) with 88% retention after 100 cycles and 165 μAh cm-2 μm -1 (1650 mAh cm-3 or ∼518 mAh g-1) obtained at a discharge current density of 1000 μA cm-2 (∼6.6 C) for 1000 cycles were achieved. Meanwhile an energy density of 294 μWh cm -2 μm-1 (2.94 Wh cm-3 or ∼924 Wh kg -1) and power density of 584 μW cm-2 μm-1 (5.84 W cm-3 or ∼1834 W kg-1) were also obtained, which may make these thin film anodes promising as a power supply for micro- or even nanosized portable electronic devices. © 2014 American Chemical Society.

Ding W.,CAS Institute of Physics | Wang Y.,Beijing University of Technology
Optics Express | Year: 2014

We report an analytic model for quantitatively calculating the transmission attenuation of single-wall hollow-core anti-resonant fibers. Our calculations unveil the light leakage dependences on azimuthal angle, polarization, and geometrical shape and have been examined in a variety of fiber geometries. Based on our model, a simple and clear picture about light guidance in hollow-core lattice fibers is presented. Formation of equiphase surface at fiber's outermost boundary and light emission ruled by Helmholtz equation in transverse plane constitute the basis of this picture. Using this picture, we explain how the geometrical shape of a single-wall hollow-core fiber influences its transmission properties. © 2014 Optical Society of America

Seyring M.,Friedrich - Schiller University of Jena | Song X.,Beijing University of Technology | Rettenmayr M.,Friedrich - Schiller University of Jena
ACS Nano | Year: 2011

The special properties of nanocrystalline materials are generally accepted to be a consequence of the high density of planar defects (grain and twin boundaries) and their characteristics. However, until now, nanograin structures have not been characterized with similar detail and statistical relevance as coarse-grained materials, due to the lack of an appropriate method. In the present paper, a novel method based on quantitative nanobeam diffraction in transmission electron microscopy (TEM) is presented to determine the misorientation of adjacent nanograins and subgrains. Spatial resolution of <5 nm can be achieved. This method is applicable to characterize orientation relationships in wire, film, and bulk materials with nanocrystalline structures. As a model material, nanocrystalline Cu is used. Several important features of the nanograin structure are discovered utilizing quantitative analysis: the fraction of twin boundaries is substantially higher than that observed in bright-field images in the TEM; small angle grain boundaries are prominent; there is an obvious dependence of the grain boundary characteristics on grain size distribution and mean grain size. © 2011 American Chemical Society.

Liu K.,George Washington University | Liu K.,Beijing University of Technology | Ye C.R.,George Washington University | Khan S.,George Washington University | Sorger V.J.,George Washington University
Laser and Photonics Reviews | Year: 2015

As electronic device feature sizes scale-down, the power consumed due to onchip communications as compared to computations will increase dramatically; likewise, the available bandwidth per computational operation will continue to decrease. Integrated photonics can offer savings in power and potential increase in bandwidth for onchip networks. Classical diffraction-limited photonics currently utilized in photonic integrated circuits (PIC) is characterized by bulky and inefficient devices compared to their electronic counterparts due to weak light-matter interactions (LMI). Performance critical for the PIC is electro-optic modulators (EOM), whose performances depend inherently on enhancing LMIs. Current EOMs based on diffraction-limited optical modes often deploy ring resonators and are consequently bulky, photon-lifetime modulation limited, and power inefficient due to large electrical capacitances and thermal tuning requirements. In contrast, wavelength-scale EOMs are potentially able to surpass fundamental restrictions set by classical (i.e. diffraction-limited) devices via (a) high-index modulating materials, (b) nonresonant field and density-of-states enhancements such as found in metal optics, and (c) synergistic onchip integration schemes. This manuscript discusses challenges, opportunities, and early demonstrations of nanophotonic EOMs attempting to address this LMI challenge, and early benchmarks suggest that nanophotonic building blocks allow for densely integrated high-performance photonic integrated circuits. The performances of electro-optic modulators (EOM) is determined by the interaction strength between light and matter. Here, EOMs based on sub-diffraction-limited optical modes are summarized and discussed. These devices show performance metrics that are able to surpass classical device limits through (a) optical field enhancements, (b) low-Q resonators and (c) synergistic integration schemes including emerging materials for strong index modulation. © 2015 by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tong H.,CAS Institute of High Energy Physics | Song L.M.,CAS Institute of High Energy Physics | Xu R.X.,Beijing University of Technology
Astrophysical Journal | Year: 2011

Anomalous X-ray pulsars (AXPs) and soft gamma-ray repeaters (SGRs) are magnetar candidates, i.e., neutron stars powered by a strong magnetic field. If they are indeed magnetars, they will emit high-energy gamma rays that are detectable by the Fermi Large Area Telescope (LAT), according to the outer gap model. However, no significant detection is reported in recent Fermi-LAT observations of all known AXPs and SGRs. Considering the discrepancy between theory and observations, we calculate the theoretical spectra for all AXPs and SGRs with sufficient observational parameters. Our results show that most AXPs and SGRs are high-energy gamma-ray emitters if they are really magnetars. The four AXPs 1E 1547.0-5408, XTE J1810-197, 1E 1048.1-5937, and 4U 0142+61 should have been detected by Fermi-LAT. There is therefore a conflict between the outer gap model in the case of magnetars and Fermi observations. Possible explanations in the magnetar model are discussed. On the other hand, if AXPs and SGRs are fallback disk systems, i.e., accretion-powered for the persistent emissions, most of them are not high-energy gamma-ray emitters. Future deep Fermi-LAT observations of AXPs and SGRs will help us make clear whether they are magnetars or fallback disk systems. © 2011. The American Astronomical Society. All rights reserved.

Liu Y.,Beijing University of Chemical Technology | Dai H.,Beijing University of Chemical Technology | Du Y.,Beijing University of Technology | Deng J.,Beijing University of Chemical Technology | And 3 more authors.
Journal of Catalysis | Year: 2012

Three-dimensionally ordered macroporous (3DOM) single-phase rhombohedral perovskite-type oxide LaMnO 3 materials with nanovoid skeletons were prepared using the poly(methyl methacrylate)-templating methods with the assistance of surfactant (poly(ethylene glycol) (PEG) or triblock copolymer (Pluronic P123)). The nature of surfactant influenced the pore structure of the LaMnO 3 sample. The use of PEG400 alone led to a 3DOM-structured LaMnO 3 without nanovoid skeletons; with the addition of PEG400 and P123, however, one could prepare LaMnO 3 samples with high-quality 3DOM structures, nanovoid skeletons, and high surface areas (37-39 m 2/g). Under the conditions of toluene concentration = 1000 ppm, toluene/O 2 molar ratio = 1:400, and space velocity = 20,000 mL/(g h), the porous LaMnO 3 samples were superior to the bulk counterpart in catalytic performance, with the nanovoid-containing 3DOM-structured LaMnO 3 catalyst performing the best (the temperatures for toluene conversions of 50% and 90% were 222-232 and 243-253 °C, respectively). The apparent activation energies (57-62 kJ/mol) over the 3DOM-structured LaMnO 3 catalysts were much lower than that (97 kJ/mol) over the bulk LaMnO 3 catalyst. We believe that the excellent performance of the 3D macroporous LaMnO 3 materials in catalyzing the combustion of toluene might be due to factors such as large surface area, high oxygen adspecies concentration, good low-temperature reducibility, and unique nanovoid-containing 3DOM structure of the materials. © 2011 Elsevier Inc. All rights reserved.

Miao L.,Tulane University | Xu H.,Tulane University | Xu H.,Beijing University of Technology | Mao Z.Q.,Tulane University
Physical Review B - Condensed Matter and Materials Physics | Year: 2014

We have grown Sr2IrO4 (SIO) epitaxial thin films on SrTiO3 (STO) and NdGaO3 (NGO) substrates by a pulsed laser deposition method and characterized their structures and magnetic properties. We find that SIO films grown on STO substrates display tetragonal structure with a tensile strain of 0.13%, while SIO films grown on NGO substrates exhibit slightly orthorhombic structure with anisotropic biaxial tensile strains of 0.39% and 0.51% along the in-plane crystallographic axes. Although both films display insulating properties as bulk SIO does, their magnetic properties are distinct from that of bulk SIO. The ferromagnetic (FM) component of the Jeff = 1/2 canted antiferromagnetic order, which emerges below ∼240 K in bulk SIO, is significantly weakened in both films, with a greater weakening appearing in the SIO/NGO film. From structural and magnetoresistance anisotropy analyses for both films, we reveal that the weak FM component in SIO films is dependent on the epitaxial strain. The greater tensile strain leads to a smaller octahedral rotation: The rotation angle is ∼9.7(1) for the SIO/NGO film and ∼10.7(2) for the SIO/STO film. These findings indicate that the Jeff = 1/2 moment orientation in SIO follows the IrO6 octahedral rotation due to strong spin-orbit interaction. © 2014 American Physical Society.

Shao H.-S.,Beijing University of Technology | Shao H.-S.,CERN
Computer Physics Communications | Year: 2013

By the virtues of the Dyson-Schwinger equations, we upgrade the published code HELAC to be capable to calculate the heavy quarkonium helicity amplitudes in the framework of NRQCD factorization, which we dub HELAC-Onia. We rewrote the original HELAC to make the new program be able to calculate helicity amplitudes of multi P-wave quarkonium states production at hadron colliders and electron-positron colliders by including new P-wave off-shell currents. Therefore, besides the high efficiencies in computation of multi-leg processes within the Standard Model, HELAC-Onia is also sufficiently numerical stable in dealing with P-wave quarkonia (e.g. hc,b,χc,b) and P-wave color-octet intermediate states. To the best of our knowledge, it is a first general-purpose automatic quarkonium matrix elements generator based on recursion relations on the market. © 2013 Elsevier B.V. All rights reserved.

Ma B.-Q.,Beijing University of Technology | Ma B.-Q.,Peking University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

We propose simple forms of the neutrino mixing matrix in analogy with the Wolfenstein parametrization of the quark mixing matrix by adopting the smallest mixing angle θ13 as a measure of expansion parameters with the tribimaximal pattern as the base matrix. The triminimal parametrization technique is utilized to expand the mixing matrix under two schemes, i.e., the standard Chau-Keung scheme and the original Kobayashi-Maskawa scheme. The new parametrizations have their corresponding Wolfenstein-like parametrizations of the quark mixing matrix, and therefore they share the same intriguing features of the Wolfenstein parametrization. The newly introduced expansion parameters for neutrinos are connected to the Wolfenstein parameters for quarks via the quark-lepton complementarity. © 2013 American Physical Society.

Lei J.,Beijing University of Technology | Zhang C.,University of Siegen
International Journal of Fracture | Year: 2012

A time-domain boundary element method (BEM) together with the sub-domain technique is applied to study transient response of interfacial cracks in piecewise homogeneous, anisotropic and linear piezoelectric bi-materials under electrical and mechanical impacts. The present time-domain BEM uses a quadrature formula for the temporal discretization to approximate the convolution integrals and a collocation method for the spatial discretization. Quadratic quarter-point elements are implemented at the tips of the interface cracks. To determine the real or complex dynamic stress intensity factors and the dynamic electrical displacement intensity factor of the interfacial cracks, an explicit extrapolating formula in a typical state of the crack plane perpendicular to the poling direction is presented in this paper. Numerical examples are presented; and the effects of the load combination and material combination on dynamic intensity factors and dynamic energy release rate are discussed. © 2012 Springer Science+Business Media B.V.

Ding W.,CAS Institute of Physics | Wang Y.-Y.,Beijing University of Technology
Optics Express | Year: 2015

We identify, for the first time to our best knowledge, a new type of transmission band having hybrid resonance nature in hollow-core anti-resonant fibers (ARF). We elucidate its unique phase-locking feature of the electric field at the outermost boundary. Exploiting this hybrid band, large birefringence in the order of 10-4 is obtained. Our analyses based on Kramer-Kronig relation and transverse field confinement interpret the link between the hybrid transmission band and the large birefringence. Guided by these analyses, an experimentally realizable polarization-maintaining ARF design is proposed by introducing multi-layered dielectric structure into a negative curvature core-surround. This multi-layered ARF possesses characteristics of low loss, broad transmission band and large birefringence simultaneously. © 2015 Optical Society of America.

Huang C.,Beijing University of Technology | Wong C.K.,City University of Hong Kong
Automation in Construction | Year: 2015

This paper develops a mathematical formulation to model and optimise site facility locations inside a construction site for a construction project's different stages. The existence and dimensions of a construction project's available locations and site facilities can be varied across the construction stages. Without proper planning, unnecessary facility relocations may be required in each construction stage, resulting in a higher construction cost and longer construction time due to the need to dismantle and set up site facilities. Site layout plans should be optimised using a multiple-stage model to avoid unnecessary changes to facility settings across construction stages, improving efficiency. The proposed site layout problem with multiple construction stages is formulated as a binary-mixed-integer-linear programme, which can be solved by a standard branch-and-bound algorithm using the commercial software package LINGO. The mathematical objective function established in the solution process aims to minimise the total cost, which consists of the material transportation cost between the relevant site facilities and the dismantling, setup and relocation costs for all of the involved site facilities in each construction stage. Numerical examples using the proposed mathematical model to optimise different site layout settings for a construction site are given, including (1) a reference site layout plan using the conventional static single-stage approach, (2) a multiple-stage construction site layout plan and (3) a multiple-stage site layout plan with additional safety design considerations. © 2015 Elsevier B.V. All rights reserved.

Luo B.,Tsinghua University | Wang X.,Tsinghua University | Wang Y.,Beijing University of Technology | Li L.,Tsinghua University
Journal of Materials Chemistry A | Year: 2014

Calcium barium zirconate titanate (Ba0.95Ca 0.05Zr0.15Ti0.85O3, BCZT) ceramic particles were prepared by a conventional solid-state method. BCZT powders were modified by dopamine through a chemical coating method. The composite flexible films based on dopamine@BCZT and polyvinylidene fluoride were fabricated via a solution casting method. The microstructure and morphology were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, high-resolution transmission electron microscopy, and field emission scanning electron microscopy. A precision impedance analyzer and a dielectric withstand voltage test were used to test the dielectric constant, loss tangent, and breakdown strength. TEM results showed that dopamine was uniformly coated on the surface of BCZT particles with an average thickness of 20 nm. SEM results showed that the ceramic particles were dispersed homogeneously in the matrix. The dielectric constant increased with the increase of BCZT contents, while the loss tangent remained constant in the frequency range of 103 to 105 Hz. Different theoretical models were employed to predict the effective dielectric constants of the composite films, and the estimated results were compared with the experimental data. Weibull distribution was used to analyze the dielectric breakdown strength, and the results showed that the breakdown strength decreased then stayed over 60 kV mm-1. © 2013 The Royal Society of Chemistry.

Lu Z.,Nanjing Southeast University | Ma B.-Q.,Beijing University of Technology | Ma B.-Q.,Peking University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

The transverse momentum dependent helicity distributions of valence quarks are calculated in the light-cone diquark model by adopting two different approaches. We use the model results to analyze the P h⊥-dependent double spin asymmetries for π+, π-, and π0 productions in semi-inclusive deep inelastic scattering, and find that the asymmetries agree with the CLAS data in one of the approaches. By taking the Fourier transform of the transverse momentum dependent helicity distributions, we obtain the helicity distributions of valence quarks in the transverse coordinate space, and then apply them further to predict the Bessel-weighted double spin asymmetries of π+, π-, and π0 productions in semi-inclusive deep inelastic scattering at CLAS, COMPASS, and HERMES for the first time. The shape of the Bessel-weighted double spin asymmetry thereby provides a direct probe on the transverse structure of longitudinally polarized quarks. © 2013 American Physical Society.

An L.,Peking University | Huang W.,Anhui University of Science and Technology | Zhang N.,Peking University | Chen X.,Beijing University of Technology | Xia D.,Peking University
Journal of Materials Chemistry A | Year: 2014

Carbon-supported CoN (CoN/C) nanoparticles have been synthesized by heating at reflux in the solution of o-xylene and subsequent thermal annealing under a NH3 reducing atmosphere. The as-prepared CoN/C composite exhibited high oxygen reduction reaction (ORR) activity and excellent stability as a new efficient non-precious metal electrocatalyst. © The Royal Society of Chemistry.

Yu J.,Tsinghua University | Li D.-P.,Beijing University of Technology | Liao Q.-M.,Tsinghua University
Zidonghua Xuebao/Acta Automatica Sinica | Year: 2011

Imaging in the atmosphere is often degraded by scattering due to atmospheric particles such as haze, fog, and mist. In this paper, we propose a novel fast defogging method based on the atmospheric scattering model. The white balance is performed and the atmospheric scattering model is simplified prior to visibility restoration. In the inference process of the atmospheric veil, the coarser estimate is refined using a fast bilateral filtering approach that preserves edges. Finally, the scene albedo is recovered by inverting this simplified model. The complexity of the proposed method is only a linear function of the number of input image pixels and this allows a very fast implementation. Results on a variety of outdoor foggy images demonstrate that the proposed method achieves good restoration for contrast and color fidelity, resulting in a great improvement in image visibility. Copyright © 2011 Acta Automatica Sinica.

Huang J.-J.,Beijing University of Technology
Lecture Notes in Electrical Engineering | Year: 2012

The marketing typically involves two components, customers and products. By focusing on a customer, recommender systems attempts to find targeted groups of products with respect to the customer. Recommender systems are considered one of important application fields in Web Intelligence and Data Mining. © 2012 Springer-Verlag London Limited.

Ye Q.,University of Michigan | Ye Q.,Beijing University of Technology | Wang L.,University of Michigan | Yang R.T.,University of Michigan
Applied Catalysis A: General | Year: 2012

Copper, iron, and mixed copper/iron exchanged zeolites containing ZSM-5 and chabazite-like zeolites (SSZ-13, SAPO-18 and SAPO-34) were studied for selective catalytic reduction (SCR) of NO with NH 3 with or without propene. Cu/ZSM-5, Cu/SSZ-13, Cu/SAPO-18 and Cu/SAPO-34 exhibited high NO conversions without propene. However, as compared to Cu/ZSM-5, NO conversions over Cu/SSZ-13, Cu/SAPO-18 and Cu/SAPO-34 were more stable with propene, due to coke formation over Cu/ZSM-5. The results of N 2-adsorption/desorption and XPS showed that the surface area, Cu +/Cu 2+ ratio and the surface amount of Cu content of Cu/ZSM-5 catalysts changed from 324 m 2/g, 0.03 and 11.5 wt% for the fresh Cu/ZSM-5 catalyst to 68 m 2/g, 0.34 and 5.3 wt% for the used sample. However, there were little changes between fresh and used Cu/SSZ-13, Cu/SAPO-18 and Cu/SAPO-34 catalysts. Moreover, Cu/ZSM-5 catalyst showed a larger decline in NO conversion with time on stream and a higher adsorption amount of propene compared to Cu/SSZ-13, Cu/SAPO-18 and Cu/SAPO-34 catalysts. The resistance to hydrocarbon poisoning depended on the pore geometry of the zeolites. During NH 3-SCR, the presence of medium-pore sizes in Cu/ZSM-5 led to hydrocarbon deposition, which blocked the active sites and also decreased the active intermediates needed for NO conversion. Cu/SSZ-13, Cu/SAPO-18 and Cu/SAPO-34 catalysts, on the other hand, with small pores and cage diameters and with one-dimensional channel structures, showed higher hydrocarbon poison resistance. Moreover, these copper exchanged small-pore zeolites showed much higher hydrothermal stability than the medium-pore Cu/ZSM-5. © 2012 Elsevier B.V.

Sun L.-B.,Texas A&M University | Li J.-R.,Texas A&M University | Li J.-R.,Beijing University of Technology | Lu W.,Texas A&M University | And 3 more authors.
Journal of the American Chemical Society | Year: 2012

Metal-organic polyhedra (MOPs) have been incorporated into silica nanopores for the first time. Three MOPs with identical geometries but different ligand functionality (namely tert-butyl, hydroxyl, and sulfonic groups) were employed. A typical mesoporous silica, SBA-15, with a two-dimensional hexagonal pore regularity was used as the host. In comparison with bulk MOPs, which prefer to aggregate, MOPs confined in silica nanopores can be well dispersed, making the active sites and pores in the MOPs accessible. These dispersed MOPs showed apparently superior H 2 adsorption capacity in comparison with aggregated bulk MOPs. Moreover, the thermal stability of the MOPs was enhanced upon their confinement in silica nanopores. © 2012 American Chemical Society.

Li Z.P.,Southwest University | Song B.Y.,Southwest University | Yao J.M.,Southwest University | Vretenar D.,University of Zagreb | And 4 more authors.
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2013

The evolution of quadrupole and octupole shapes in Th isotopes is studied in the framework of nuclear Density Functional Theory. Constrained energy maps and observables calculated with microscopic collective Hamiltonians indicate the occurrence of a simultaneous quantum shape phase transition between spherical and quadrupole-deformed prolate shapes, and between non-octupole and octupole-deformed shapes, as functions of the neutron number. The nucleus 224Th is closest to the critical point of a double phase transition. A microscopic mechanism of this phenomenon is discussed in terms of the evolution of single-nucleon orbitals with deformation. © 2013 Elsevier B.V.

Wang X.-G.,Beijing University of Technology | Luan Q.-B.,Dalian University of Technology
Frontiers of Physics | Year: 2013

Whistler waves generated in fast magnetic reconnection processes of collisionless high beta plasmas are reviewed in experiments and satellite observations, as well as in theory and simulation, and further studied in the two-fluid theory. It is found that low frequency whistler waves can be excited in the ion inertial range of the reconnection region. The wave is found right-handed polarized with a quadrupolar out-of-plane magnetic perturbation, in accord with satellite observations in the geomagnetosphere. © 2013 Higher Education Press and Springer-Verlag Berlin Heidelberg.

Zhu Y.,Fujian University of Traditional Chinese Medicine | Zeng Y.,Beijing University of Technology
CNS Neuroscience and Therapeutics | Year: 2011

Aim: Clinically electroacupuncture (EA) is proved an effective therapy for vascular dementia (VD), but their mechanisms remain uncertain. The aim of this study was to determine whether EA protects pyramidal cells from apoptosis in hippocampus of a VD rat model by inhibiting the expression of p53 and Noxa. Methods: One month after a VD animal model was established by bilateral occlusion of common carotid arteries, EA treatment was given at "Baihui" (DU20), "Dazhui" (DU14), and "Shenshu" (BL23). The learning and memory ability was assessed by Morris water maze. Neuronal apoptosis in hippocampus was evaluated with hematoxylin-eosin (HE) staining, and the expression of p53 and Noxa was analyzed by confocal laser scanning microscope with immunofluorescence staining. Results: Expressions of p53 and Noxa in the EA group and sham-operated group were less than in the VD model group (P < 0.01), and the expression of p53 was positively correlated to expression of Noxa in hippocampus of VD rats (r = 0.918, P < 0.01). EA treatment could reduce the amount of apoptotic neurons in hippocampal CA1 area of rats with VD. The average latency in the Morris water maze test was significantly shorter, and escape strategies improved from edge and random searches to more linear swim pathway in the EA group compared with the VD model group (P < 0.01). Conclusions: The increasing expressions of p53 and Noxa play important roles in the pathogenesis of VD. EA improves learning and memory ability and protects pyramidal cells from apoptosis by blocking expression of p53 and Noxa in the hippocampal CA1 region of VD rats. These results suggest a novel mechanism of EA treatment to VD. © 2010 Blackwell Publishing Ltd.

Li N.,Beijing University of Technology | Zhu S.-L.,Peking University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012

We reinvestigate the possibility of X(3872) as a DD ̄* molecule with JPC=1 ++ within the framework of both the one-pion-exchange model and the one-boson-exchange model. After careful treatment of the S-D wave mixing, the mass difference between the neutral and charged D(D*) mesons and the coupling of the DD ̄* pair to D*D ̄*, a loosely bound molecular state X(3872) emerges quite naturally with large isospin violation in its flavor wave function. For example, the isovector component is 26.24% if the binding energy is 0.30 MeV, where the isospin breaking effect is amplified by the tiny binding energy. After taking into account the phase space difference and assuming the 3π and 2π come from a virtual omega and rho meson respectively, we obtain the ratio of these two hidden-charm decay modes: B(X(3872) →π +π -π0J/ψ)/B(X(3872) →π +π -J/ψ)=0.42 for the binding energy being 0.3 MeV, which is consistent with the experimental value. © 2012 American Physical Society.

Xu N.,Beijing University of Technology | Tian H.,RWTH Aachen | Kulatilake P.H.S.W.,University of Arizona | Duan Q.,China Institute of Water Resources and Hydropower Research
Computers and Geotechnics | Year: 2011

The dam area of the SUOXI hydropower project shows high terrain undulation and complex geological conditions, containing 6 faults and 7weak inter-beds. A geometric model developed to represent the geology and engineering structures should incorporate the geological realities and should allow suitable mesh generation to perform numerical stress analysis. This is an important precondition to perform rock mass stability analysis of a dam foundation based on a numerical stress analysis software such as FLAC3D. Using the modeling tools available in FLAC3D, it is difficult to construct a complex geological model even after performing a large amount of plotting and data analyses. The 3-D geological modeling technique suggested in this paper, named as Sealed Geological Modeling (SGM), is a powerful tool for constructing complex geological models for rock engineering projects that require numerical stress analysis. Applying this technique, first, the geological interfaces are constructed for the dam area of SUOXI hydropower project using various interpolation procedures including geostatistical techniques. Then a unitary wire frame is constructed and the interfaces are connected seamlessly. As the next step, a block tracing technique is used to build a geological model that consists of 130 seamlessly connected blocks. Finally, based on the Advancing Front Technique (AFT), each block is discretized into tetrahedrons and a mesh is generated including 57,661 nodes and 215,471 tetrahedrons which is suitable to perform numerical stress analysis using FLAC3D. © 2011 Elsevier Ltd.

Kelley R.,Harvard University | Schwartz M.D.,Harvard University | Schabinger R.M.,Autonomous University of Madrid | Zhu H.X.,Beijing University of Technology
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012

We investigate the exclusive jet mass distribution in e +e - events, defined with a veto on the out-of-jet radiation, at two-loop order. In particular, we calculate the two-loop soft function, which is required to describe this distribution in the region of small jet mass. When combined with other ingredients using the soft-collinear effective theory, this generates the complete singular distribution for jet thrust, the sum of the jet masses, at two-loop order. The result is in excellent agreement with full quantum chromodynamics. The integrated jet thrust distribution is found to depend in an intricate way on both the finite jet cone size, R, and the jet veto scale. The result clarifies the structure of the potentially large logarithms (both global and nonglobal) which arise in jet observables for the first time at this order. Somewhat surprisingly, we find that, in the small R limit, there is a precise and simple correspondence between the nonglobal contribution to the integrated jet thrust distribution and the previously calculated nonglobal contribution to the integrated hemisphere soft function, including subleading terms. This suggests that the small R limit may provide a useful expansion for studying other exclusive jet substructure observables. © 2012 American Physical Society.

Si P.,Beijing University of Technology | Ji H.,Beijing University of Posts and Telecommunications | Yu F.R.,Carleton University | Leung V.C.M.,University of British Columbia
IEEE Transactions on Vehicular Technology | Year: 2010

Spectrum pooling in cognitive radio systems is an approach to manage the available spectrum bands from different licensed networks. Most previous work on spectrum pooling concentrates on the system architecture and the design of flexible-access algorithms and schemes. In this paper, we present a cooperative scheme for internetwork spectrum sharing among multiple secondary systems, which takes into account the price and spectrum efficiency as the design criteria. Specifically, the spectrum-sharing problem is formulated as a stochastic bandit system; thus, the optimal spectrum-sharing scheme is simply allocating the new available band to the secondary network with the lowest index. Extensive simulation examples illustrate that the proposed scheme significantly improves the performance compared with the existing scheme that ignores optimal spectrum sharing. © 2006 IEEE.

Chen F.-M.,Beijing University of Technology
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012

We construct some examples of D=3, N=4 GW theory and N=5 superconformal Chern-Simons matter theory by using the covariantly constant curvature of a quaternionic-Kahler manifold to construct the symplectic 3-algebra in the theories. Comparing with the previous theories, the N=4, 5 theories constructed in this way possess a local Sp(2n) symmetry and a diffeomorphism symmetry associated with the quaternionic-Kahler manifold. We also construct a generalized N=8 BLG theory by utilizing the dual curvature operator of a maximally symmetric space of dimension 4 to construct the Nambu 3-algebra. Comparing with the previous N=8 BLG theory, the theory has a diffeomorphism invariance and a local SO(4) invariance associated with the symmetric space. © 2012 American Physical Society.

Li N.,Beijing University of Technology | Zhu S.-L.,Peking University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012

We investigate the possible molecules composed of two heavy flavor baryons such as "A QB Q" (Q=b, c) within the one-pion-exchange model (OPE). Our results indicate that the long-range π exchange force is strong enough to form molecules such as [Σ QΞQ′]S=1I=1/2 (Q=b, c), [Σ QΛ Q]S=1I=1 (Q=b, c), [Σ bΞb′]S=1I=3/2, and [Ξ bΞb′]S=1I=0 where the S-D mixing plays an important role. In contrast, the π exchange does not form the spin-singlet A QB Q bound states. If we consider the heavier scalar and vector meson exchanges as well as the pion exchange, some loosely bound spin-singlet S-wave states appear while results of the spin-triplet A QB Q system do not change significantly, which implies the pion exchange plays an dominant role in forming the spin-triplet molecules. Moreover, we perform an extensive coupled channel analysis of the Λ QΛ Q system within the OPE and one-boson-exchange framework and find that there exist loosely bound states of Λ QΛ Q (Q=b, c) with quantum numbers I(JP)=0(0 +), 0(0 -), and 0(1 -). The binding solutions of Λ QΛ Q system mainly come from the coupled-channel effect in the flavor space. Besides the OPE force, the medium- and short-range attractive force also plays a significant role in the formation of the loosely bound Λ cΛ c and Λ bΛ b states. Once produced, they will be very stable because such a system decays via weak interaction with a very long lifetime around 10 -13-10 -12s. © 2012 American Physical Society.

Tang Z.,Beijing University of Technology | Tang Z.,State Key Laboratory of Millimeter Waves
IEEE Transactions on Components, Packaging and Manufacturing Technology | Year: 2012

Thermal control of printed circuit board and integrated circuit package is challenging in microelectronics because the power density increases when smaller and more complicated packages are designed. Temperature rising due to power dissipation and hotspots worsens harmful clock skew and jeopardizes reliability of products. To overcome these risks, designers have to perform electromagnetic-thermal co-simulations at the early design stage. However, it is difficult to detect the hotspots in the package because very high-resolution simulations are needed. In this paper, an improved adaptive finite element method (FEM) is applied to detect hotspots, which only needs one-step adaptive refinement for a given error threshold, which is very fast and uses much smaller computation resources. Furthermore, instead of electromagnetic-thermal co-simulation, this method directly finds potential hotspots based on the volumetric heat generation. Test results show that the adaptive FEM only takes about 60 times the memory and CPU time to detect all hotspots when compared to the initial FEM solution. © 2011-2012 IEEE.

Cao J.,Henan Normal University | Hikasa K.-I.,Tohoku University | Wang W.,Beijing University of Technology | Yang J.M.,CAS Institute of Theoretical Physics
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2011

For the experimental search of neutralino dark matter, it is important to know its allowed mass and scattering cross section with the nucleon. In order to figure out how light a neutralino dark matter can be predicted in low energy supersymmetry, we scan over the parameter space of the NMSSM (next-to-minimal supersymmetric model), assuming all the relevant soft mass parameters to be below TeV scale. We find that in the parameter space allowed by current experiments the neutralino dark matter can be as light as a few GeV and its scattering rate off the nucleon can reach the sensitivity of XENON100 and CoGeNT. As a result, a sizable parameter space is excluded by the current XENON100 and CoGeNT data (the plausible CoGeNT dark matter signal can also be explained). The future 6000 kg-days exposure of XENON100 will further explore (but cannot completely cover) the remained parameter space. Moreover, we find that in such a light dark matter scenario a light CP-even or CP-odd Higgs boson must be present to satisfy the measured dark matter relic density. Consequently, the SM-like Higgs boson hSM may decay predominantly into a pair of light Higgs bosons or a pair of neutralinos so that the conventional decays like hSM→γγ is much suppressed. © 2011 Elsevier B.V.

Wang N.,Guangxi Normal University | Liu M.,Guangxi Normal University | Wu X.,China Institute of Atomic Energy | Meng J.,Beijing University of Technology | Meng J.,Beihang University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2014

By taking into account the surface diffuseness correction for unstable nuclei, the accuracy of the macroscopic-microscopic mass formula is further improved. The rms deviation with respect to essentially all the available mass data falls to 298 keV, crossing the 0.3 MeV accuracy threshold for the first time within the mean-field framework. Considering the surface effect of the symmetry potential which plays an important role in the evolution of the "neutron skin" toward the "neutron halo" of nuclei approaching the neutron drip line, we obtain an optimal value of the symmetry energy coefficient J = 30.16 MeV. With an accuracy of 258 keV for all the available neutron separation energies and of 237 keV for the α-decay Q-values of super-heavy nuclei, the proposed mass formula is particularly important not only for the reliable description of the r process of nucleosynthesis but also for the study of the synthesis of super-heavy nuclei. © 2014 The Authors.

Wang Y.,Beijing University of Technology
IEEE Transactions on Network and Service Management | Year: 2016

QoS-aware applications can satisfy not only the functional requirements of the customers, but also the QoS requirements. QoS-aware Web service orchestration translates the QoS requirements of the customers into those of its component Web services. In a system viewpoint, we discuss issues on QoS-aware Web service orchestration and design a typical QoS-aware Web service orchestration engine called QoS-WSOE. More importantly, we establish a formal model of QoS-WSOE based on actor systems theory. Within the formal model, we use a three-layered pyramidal structure to capture the requirements of the customers with a concept named QoS-aware WSO service, characteristics of QoS-WSOE with a concept named QoS-aware WSO system, and structures and behaviors of QoS-WSOE with a concept named QoS-aware WSO behavior. Conclusions showing that a system with QoS-aware WSO behavior is a QoS-aware WSO system and further can provide QoS-aware WSO Service are drawn. © 2015 IEEE.

Chai W.,Beijing University of Technology
International Journal of Innovative Computing, Information and Control | Year: 2014

This paper proposes a novel set membership identification method for models nonlinear in their parameters. A mapping which can approximate the homeomorphism between the feasible parameter set (FPS) boundary and the n—1 -sphere (n is the number of parameters) is constructed. First, a data set consisting of vectors uniformly sampled from the FPS boundary is mapped into a data set contained by the n—1 -sphere. This is achieved by locally linear embedding followed by data normalization. Then, a non-parametric method based on the two data sets is used to build a mapping which approximates the homeomorphism between the FPS boundary and the n—1 -sphere. Once this mapping is established, it can be used to map the n—1-sphere into an approximation of the FPS boundary. Moreover, a strategy is proposed to improve the boundary approximation. Examples show that the proposed method exhibits superior performance compared with other nonlinear set membership identification methods. © 2014, IJICIC Editorial Office. All rights reserved.

Li J.-Z.,Beijing University of Technology | Ma Y.-Q.,Brookhaven National Laboratory | Chao K.-T.,Peking University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

We calculate the annihilation decay widths of spin-singlet heavy quarkonia hc, hb and ηb into light hadrons with both QCD and relativistic corrections at order O(αsv2) in nonrelativistic QCD. With appropriate estimates for the long-distance matrix elements by using the potential model and operator evolution method, we find that our predictions of these decay widths are consistent with recent experimental measurements. We also find that the O(αsv2) corrections are small for bb̄ states but substantial for cc̄ states. In particular, the negative contribution of O(αsv2) correction to the hc decay can lower the decay width, as compared with previous predictions without the O(αsv2) correction, and thus result in a good agreement with the recent BESIII measurement. © 2013 American Physical Society.

Liu H.,Xian Jiaotong University | Xu F.,Beijing University of Technology
Science China: Physics, Mechanics and Astronomy | Year: 2013

Configuration-constrained potential-energy-surface calculations are performed to investigate high-K isomers in 97Y, 130Ba, 176Yb, 177Lu, and 178Hf that were observed to have increased electric quadrupole moments but decreased charge radii relative to the states on which they are built. Taking into account the effects of deformation change and unpaired protons, our calculations can reproduce the enhancement of electric quadrupole moments for the isomers in 97Y, 130Ba, 176Yb, 177Lu and the K π = 8- isomer in 178Hf, and can reproduce the reduction of charge radii for the K π = 27/2- isomer in 97Y and the K π = 16+ isomer in 178Hf. © 2013 Science China Press and Springer-Verlag Berlin Heidelberg.

Liu X.-H.,Beijing University of Technology | Li G.,Qufu Normal University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

By assuming that Y(4260) either is a D1D̄ molecular state or has sizeable couplings with D0D̄* and D1′D̄, we investigate several decay modes of Y(4260). Under the special kinematic configurations, triangle singularity may occur in the rescattering amplitude, which will significantly change the threshold behavior. Obvious threshold enhancements or narrow cusp structures appear quite naturally without introducing a genuine resonance. We emphasize that the radiative decay modes may be useful for studying D(*)D̄ S-wave scattering. © 2013 American Physical Society.

Li G.,Qufu Normal University | Liu X.-H.,Beijing University of Technology
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

By assuming that Y(4260) is a D1D̄ molecular state, we investigate some hidden-charm and charmed pair decay channels of Y(4260) via intermediate D1D̄ meson loops with an effective Lagrangian approach. Through investigating the α dependence of branching ratios and ratios between different decay channels, we show that the intermediate D 1D̄ meson loops are crucial for driving these transitions of Y(4260) studied here. The coupled channel effects turn out to be more important in Y(4260)→D*D̄*, which can be tested in future experiments. © 2013 American Physical Society.

Wang W.,Beijing University of Technology | Wang W.,Wright State University | Shan G.,University of Nevada, Las Vegas
Biometrics | Year: 2015

For comparison of proportions, there are three commonly used measurements: the difference, the relative risk, and the odds ratio. Significant effort has been spent on exact confidence intervals for the difference. In this article, we focus on the relative risk and the odds ratio when data are collected from a matched-pairs design or a two-arm independent binomial experiment. Exact one-sided and two-sided confidence intervals are proposed for each configuration of two measurements and two types of data. The one-sided intervals are constructed using an inductive order, they are the smallest under the order, and are admissible under the set inclusion criterion. The two-sided intervals are the intersection of two one-sided intervals. R codes are developed to implement the intervals. Supplementary materials for this article are available online. © 2015, The International Biometric Society.

Chien Y.-T.,Harvard University | Kelley R.,Harvard University | Schwartz M.D.,Harvard University | Zhu H.X.,Beijing University of Technology
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

A method is developed for calculating the jet mass distribution at hadron colliders using an expansion about the kinematic threshold. In particular, we consider the mass distribution of jets of size R produced in association with a hard photon at the Large Hadron Collider. Expanding around the kinematic threshold, where all the energy goes into the jet and the photon, provides a clean factorization formula and allows for the resummation of logarithms associated with soft and collinear divergences. All of the large logarithms of jet mass are resummed at next-to-leading logarithmic level, and all the global logarithms at next-to-next-to-leading logarithmic level. A key step in the derivation is the factorization of the soft function into pieces associated with single scales and a remainder which contains nonglobal structure. This step, which is standard in traditional resummation, is implemented in effective field theory which is then used to resum the large logarithms using the renormalization group in a systematically improvable manner. © 2013 American Physical Society.

Papaefstathiou A.,University of Zurich | Yang L.L.,Beijing University of Technology | Yang L.L.,University of Zurich | Zurita J.,University of Zurich
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

We consider Higgs boson pair production at the LHC in the bb̄W +W- channel, with subsequent decay of the W +W- pair into ℓνjj. Employing jet substructure and event reconstruction techniques, we show that strong evidence for this channel can be found at the 14 TeV LHC with 600 fb-1 of integrated luminosity, thus improving the current reach for the production of Higgs boson pairs. This measurement will allow us to probe the trilinear Higgs boson coupling λ. © 2013 American Physical Society.

Berger E.L.,Argonne National Laboratory | Cao Q.-H.,Beijing University of Technology | Yu J.-H.,Michigan State University | Zhang H.,Argonne National Laboratory | Zhang H.,Illinois Institute of Technology
Physical Review Letters | Year: 2012

The polarization of a top quark can be sensitive to new physics beyond the standard model. Since the charged lepton from top-quark decay is maximally correlated with the top-quark spin, it is common to measure the polarization from the distribution in the angle between the charged lepton and the top-quark directions. We propose a novel method based on the charged lepton energy fraction and illustrate the method with a detailed simulation of top-quark pairs produced in supersymmetric top squark pair production. We show that the lepton energy ratio distribution that we define is very sensitive to the top-quark polarization but insensitive to the precise measurement of the top-quark energy. © 2012 American Physical Society.

Wang Y.,Beijing University of Technology
Beijing Gongye Daxue Xuebao/Journal of Beijing University of Technology | Year: 2012

To automatically construct a Mamdani fuzzy model, a novel approach is proposed based on local density of data. The fuzzy rule base and membership function parameters for a candidate fuzzy system can be determined through the data mining using the clustering algorithm of fuzzy clustering of local approximation of membership (FLAME), and consequently the fuzzy system is generated automatically. In the clustering process, there is no requirement to specify the number of clusters and the outliers can be automatically identified without any extra pre-processing. The proposed approach is evaluated through a set of simulated experiments on the traffic prediction and the results indicate that the proposed approach for fuzzy system identification is feasible and efficient.

Xu R.-X.,Beijing University of Technology
Research in Astronomy and Astrophysics | Year: 2014

A circumstellar corona is proposed to explain a strange quark-cluster star during an accretion phase, which could be essential for understanding the observations of the puzzling symbiotic X-ray system 4U 1700+24. The state of cold matter at supranuclear density is still an important matter of debate, and one of the consequences of a strange star acting as a pulsar is the self-bound phenomenon on the surface, which makes extremely low-mass compact objects unavoidable. In principle, both the redshifted O VIII Ly-α emission line and the change in the blackbody radiation area could naturally be understood if 4U 1700+24 is a low-mass quark-cluster star which exhibits wind accretion. © 2014 National Astronomical Observatories of Chinese Academy of Sciences and IOP Publishing Ltd.

Zhou J.,Peking University | Sun Q.,Peking University | Sun Q.,Beijing University of Technology
Nanoscale | Year: 2014

A two-dimensional sheet with long range ferromagnetic (FM) order has been hotly pursued currently. The recent success in synthesizing polymerized Fe-phthalocyanine (poly-FePc) porous sheets paves a possible way to achieve this goal. However, the poly-FePc and its analog poly-CrPc structure are intrinsically antiferromagnetic (AFM). Using first principles combined with Monte-Carlo simulations, we study systematically the carrier-induced magnetic coupling transitions in poly-CrPc and poly-FePc sheets. We show that electron doping can induce stable FM states with Curie temperatures of 130-140 K, while hole doping will enhance the stability of the AFM states. Such changes in magnetic couplings depend on the balance of AFM superexchange and FM p-d exchange. © 2014 The Royal Society of Chemistry.

Wang Z.-L.,Jilin University | Yan J.-M.,Jilin University | Zhang Y.-F.,Beijing University of Technology | Ping Y.,Jilin University | And 2 more authors.
Nanoscale | Year: 2014

AuPd-CeO2 nanocomposites directly nucleated and grown on nitrogen-doped reduced graphene oxide, exhibit excellent catalytic activity and 100% hydrogen selectivity toward formic acid decomposition for hydrogen generation without any additives at room temperature. This journal is © The Royal Society of Chemistry.

Song C.-Y.,Beijing University of Technology | Yao J.-M.,Southwest University
Chinese Physics C | Year: 2010

The polarization effect on the spin symmetry for anti-Lambda spectrum in 16O+Λ̄ system has been studied in relativistic mean-field theory. The PK1 effective interaction is used for nucleon-meson couplings and G-parity symmetry with a reduction factor ξ= 0.3 is adopted for anti-Lambda-meson couplings. The energy differences between spin doublets in the anti-Lambda spectrum are around 0.10-0.73 MeV for pΛ̄ state. The dominant components of the Dirac spinor for the anti-Lambda spin doublets are found to be near identical. It indicates that the spin symmetry is still well-conserved against the polarization effect from the valence antiLambda hyperon, which leads to a highly compressed cold nucleus with the central density up to 2 -3 times of saturated density. © 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.

Chen W.,Beijing University of Technology | Zhu S.-L.,Peking University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2010

We study the possible charmoniumlike states with JPC=0-, 0 -+ using the tetraquark interpolating currents with the QCD sum rules approach. The extracted masses are around 4.5 GeV for the 0 - charmoniumlike states and 4.6 GeV for the 0-+ charmoniumlike states, while their bottomoniumlike analogues lie around 10.6 GeV. We also discuss the possible decay, production, and experimental search of the 0- charmoniumlike state. © 2010 The American Physical Society.

Ferroglia A.,New York City College of Technology | Pecjak B.D.,Durham University | Yang L.L.,Beijing University of Technology | Yang L.L.,Peking University
Journal of High Energy Physics | Year: 2013

We obtain a soft plus virtual approximation to the NNLO QCD contributions to the top-pair invariant mass distribution at hadron colliders. It is valid up to corrections of order mt 2/M2, with M the pair invariant mass. This is currently the most complete QCD calculation for a differential cross section in top-quark pair production, and is useful for describing the high invariant mass region characteristic of boosted top quarks. We use our results to construct an improved NNLO approximation for the pair invariant mass distribution and compare it with previous, less complete approximations based on logarithmic terms from NNLL soft-gluon resummation alone. We find that the new NNLO approximation produces moderate enhancements of the differential cross section compared to previous ones, the effect being slightly more important at low values of invariant mass than at high ones. On the other hand, at high values of invariant mass the new NNLO corrections are dominated by even higher-order effects included in NNLL soft-gluon resummation, reaffirming the need for resummation in describing the highly boosted regime. © 2013 SISSA, Trieste, Italy.

Chao W.,Peking University | Zheng Y.-J.,Shandong University | Zheng Y.-J.,Beijing University of Technology
Journal of High Energy Physics | Year: 2013

Inspired by the indication of a relatively large θ 13 from accelerator and reactor neutrino oscillation experiments, we provide a systematic study of general modifications to the three well-studied neutrino mixing patterns, i.e., tri-bimaximal, bimaximal and democratic lepton mixing matrices. The correlation between θ 13 and the other two neutrino mixing angles are derived for each types of additional rotations. Predictions on θ 12 and θ 23 are also studied. Our study shows that, although some types of additional rotations are already excluded by the current global fit data of neutrino mixing angles, several types of additional rotations still survive. Our results may provide a guideline for the model building in neutrino physics. © 2013 SISSA, Trieste, Italy.

Wang L.,CAS Institute of Computing Technology | Zhan J.,CAS Institute of Computing Technology | Shi W.,Wayne State University | Liang Y.,Beijing University of Technology
IEEE Transactions on Parallel and Distributed Systems | Year: 2012

The basic idea behind cloud computing is that resource providers offer elastic resources to end users. In this paper, we intend to answer one key question to the success of cloud computing: in cloud, can small-to-medium scale scientific communities benefit from the economies of scale? Our research contributions are threefold: first, we propose an innovative public cloud usage model for small-to-medium scale scientific communities to utilize elastic resources on a public cloud site while maintaining their flexible system controls, i.e., create, activate, suspend, resume, deactivate, and destroy their high-level management entitiesservice management layers without knowing the details of management. Second, we design and implement an innovative systemDawningCloud, at the core of which are lightweight service management layers running on top of a common management service framework. The common management service framework of DawningCloud not only facilitates building lightweight service management layers for heterogeneous workloads, but also makes their management tasks simple. Third, we evaluate the systems comprehensively using both emulation and real experiments. We found that for four traces of two typical scientific workloads: High-Throughput Computing (HTC) and Many-Task Computing (MTC), DawningCloud saves the resource consumption maximally by 59.5 and 72.6 percent for HTC and MTC service providers, respectively, and saves the total resource consumption maximally by 54 percent for the resource provider with respect to the previous two public cloud solutions. To this end, we conclude that small-to-medium scale scientific communities indeed can benefit from the economies of scale of public clouds with the support of the enabling system. © 2006 IEEE.

Li B.Q.,CAS Shenyang Institute of Metal Research | Sui M.L.,Beijing University of Technology | Mao S.X.,University of Pittsburgh
Applied Physics Letters | Year: 2010

It is usually believed that the partial dislocation and deformation twin are the results of permanent plasticity in materials. Here, we present in situ atomic-scale observation of reversible stacking fault and deformation twin during loading and unloading in nanocrystalline Ni under high-resolution transmission electron microscopy. The high propensity for the reversibility of the stacking fault and deformation twin is due to the high stacking fault force and small grain size, and will provide an understanding at atomistic scale on the nature of the deformation in nanocrystalline materials. © 2010 American Institute of Physics.

Zuo X.-N.,CAS Institute of Psychology | Xing X.-X.,Beijing University of Technology
PLoS ONE | Year: 2011

Neuroimaging community usually employs spatial smoothing to denoise magnetic resonance imaging (MRI) data, e.g., Gaussian smoothing kernels. Such an isotropic diffusion (ISD) based smoothing is widely adopted for denoising purpose due to its easy implementation and efficient computation. Beyond these advantages, Gaussian smoothing kernels tend to blur the edges, curvature and texture of images. Researchers have proposed anisotropic diffusion (ASD) and non-local diffusion (NLD) kernels. We recently demonstrated the effect of these new filtering paradigms on preprocessing real degraded MRI images from three individual subjects. Here, to further systematically investigate the effects at a group level, we collected both structural and functional MRI data from 23 participants. We first evaluated the three smoothing strategies' impact on brain extraction, segmentation and registration. Finally, we investigated how they affect subsequent mapping of default network based on resting-state functional MRI (R-fMRI) data. Our findings suggest that NLD-based spatial smoothing maybe more effective and reliable at improving the quality of both MRI data preprocessing and default network mapping. We thus recommend NLD may become a promising method of smoothing structural MRI images of R-fMRI pipeline. © 2011 Zuo, Xing.

Deng Z.,Beijing University of Technology
Fuhe Cailiao Xuebao/Acta Materiae Compositae Sinica | Year: 2016

In order to research the toughness characteristics of hybrid fiber on ultra-high performance concrete(UHPC), 161 specimens of three-point bending beam fracture testing of UHPC reinforced with four type fibers and various contents have been conducted. The load-crack mouth open displacement (CMOD) curves and load-deflection curves were measured. We took the peak-load CMOD of plain UHPC as the reference initial CMOD value of hybrid fibers reinforced UHPC. Based on the load-CMOD curves, a characterization method of equivalent fracture toughness was proposed. This new method has clear physical meaning, and unveils the influence rule of hybrid fibers type and contents to fracture toughness of UHPC. The research shows that the toughness of UHPC depends on the content of steel fiber in small deformation stage (less than the 50 times CMOD value of plain UHPC at peak load) and macro-synthetic fiber plays toughening effect in middle deformation and large deformation stage (larger than the 50 times CMOD value of plain UHPC at peak load). © 2016, BUAA Culture Media Group Ltd. All right reserved.

Hao Y.X.,Beijing Information Science and Technology University | Zhang W.,Beijing University of Technology | Yang J.,RMIT University
Composites Part B: Engineering | Year: 2011

Nonlinear dynamic analysis of a cantilever functionally graded materials (FGM) rectangular plate subjected to the transversal excitation in thermal environment is presented for the first time in this paper. Material properties are assumed to be temperature dependent. The nonlinear governing equations of motion for the FGM plate are derived based on Reddys third-order plate theory and Hamiltons principle. The first two vibration mode functions satisfying the boundary conditions of the cantilever FGM rectangular plates are chosen to be the admissible displacement functions. Galerkins method is utilized to convert the governing partial differential equations to a two-degree-of-freedom nonlinear system including quadratic and cubic nonlinear terms under combined external excitations. The present study focuses on resonance case with 1:1 internal resonance and subharmonic resonance of order 1/2. The asymptotic perturbation method is employed to obtain four nonlinear averaged equations which are then solved by using Runge-Kutta method to find the nonlinear dynamic responses of the plate. It is found that chaotic, periodic and quasi-periodic motions of the plate exist under certain conditions and the forcing excitations can change the form of motions for the FGM rectangular plate. © 2010 Elsevier Ltd. All rights reserved.

Li F.X.,Peking University | Li F.X.,Beijing University of Technology | Zhou X.L.,Peking University | Soh A.K.,University of Hong Kong
Applied Physics Letters | Year: 2010

An optimization-based computational model is proposed to study domain evolution in polycrystalline ferroelectrics composed of numerous grains, each of which consists of multiple domains. Domain switching is realized by an optimization process to minimize the free energy of each grain. Similar to phase field modeling, no priori domain-switching criterion is imposed in the proposed model. Moreover, by focusing on the volume fractions of domains only, the computational complexity of this model becomes much smaller and the domain textures evolution can be captured. Simulation results on both tetragonal and rhombohedral lead titanate zirconate ceramics illustrate the efficiency of this model. © 2010 American Institute of Physics.

Song X.,Beijing University of Technology
Computational Materials Science | Year: 2012

Findings on the stability of nanocrystalline grain structures reported by S.A. Sabeti et al. in Computational Materials Science [1] are commented. In particular, the validity of Molecular Dynamics simulations and their comparability with results of thermodynamic modeling [2] are discussed. The conclusion in [1] that "by the increase of the temperature, the possibility for the stoppage of grain growth in nanocrystalline Pd is facilitated" is discussed critically. © 2012 Elsevier B.V. All rights reserved.

Yang Q.-S.,Beijing University of Technology
Computers, Materials and Continua | Year: 2013

In nanoindentation testing of materials, the analytical/numerical models to connect the indentation load, indentation depth and material properties are crucial for the extraction of mechanical properties. This paper studied the methods of extracting the mechanical properties of nonlinear elastic materials and built general relationships of the indentation load and depth of hyperelastic materials combined with the dimensional analysis and finite element method (FEM). Compared with the elastic contact models and other nonlinear elastic contact models, the proposed models can extract the mechanical properties of nonlinear elastic materials under large deformation simply and effectively. Copyright © 2013 Tech Science Press.

Wang L.,Harbin Institute of Technology | Wang L.,Beijing University of Technology | Wang Y.,National School in Computer Science | Gao W.,National School in Computer Science
International Journal of Computer Vision | Year: 2011

We propose a layered-grammar model to represent actions. Using this model, an action is represented by a set of grammar rules. The bottom layer of an action instance's parse tree contains action primitives such as spatiotemporal (ST) interest points. At each layer above, we iteratively mine grammar rules and "super rules" that account for the high-order compositional feature structures. The grammar rules are categorized into three classes according to three different ST-relations of their action components, namely the strong relation, weak relation and stochastic relation. These ST-relations characterize different action styles (degree of stiffness), and they are pursued in terms of grammar rules for the purpose of action recognition. By adopting the Emerging Pattern (EP) mining algorithm for relation pursuit, the learned production rules are statistically significant and discriminative. Using the learned rules, the parse tree of an action video is constructed by combining a bottom-up rule detection step and a top-down ambiguous rule pruning step. An action instance is recognized based on the discriminative configurations generated by the production rules of its parse tree. Experiments confirm that by incorporating the high-order feature statistics, the proposed method largely improves the recognition performance over the bag-of-words models. © 2010 Springer Science+Business Media, LLC.

Liu C.-F.,Hebei United University | Kong S.-S.,Beijing University of Technology | Yuan S.-J.,Hebei United University
Thermal Science | Year: 2013

A reconstructive scheme for variational iteration method using the Yang-Laplace transform is proposed and developed with the Yang-Laplace transform. The identification of fractal Lagrange multiplier is investigated by the Yang-Laplace transform. The method is exemplified by a fractal heat conduction equation with local fractional derivative. The results developed are valid for a compact solution domain with high accuracy.

Qu Z.,Tsinghua University | Qu Z.,Beijing University of Technology | Wan C.,Tsinghua University | Pan W.,Tsinghua University
Acta Materialia | Year: 2012

Compounds with an A 2B 2O 7-type pyrochlore structure have been identified as a class of materials with low thermal conductivity. To ascertain the effect of the pyrochlore structure, the thermophysical properties of rare-earth stannates which constitute the longest isostructural series with this unique crystal structure were measured and the thermal conduction behavior was investigated by analyzing the variation in the inverse phonon mean free path with temperature in terms of the phonon-scattering theory. The results show that the contraction of rare-earth ions and the accompanying deviation from the ideal pyrochlore structure result in a simultaneous increase in the Young's modulus and the thermal expansion coefficient. Scattering due to the strain field fluctuation caused by the systemic displacement of 48f oxygen ions rather than scattering from the so-called 8a site "oxygen vacancies" and thermal defects predominates in reducing the phonon mean free path and consequently the thermal conductivity at relative low temperature. At a certain critical temperature, the thermal conduction behavior of the stannates undergoes a transition to a minimum phonon mean free path mechanism, which is responsible for the remarkable variation in temperature dependence of thermal conductivity across the compositions. © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Li Y.-W.,Nankai University | Li J.-R.,Beijing University of Technology | Wang L.-F.,Nankai University | Zhou B.-Y.,Nankai University | And 2 more authors.
Journal of Materials Chemistry A | Year: 2013

Two cluster-based microporous MOFs containing coordination unsaturated metal(ii) sites (or open metal(ii) sites) have been constructed from boxlike or cagelike {M3}x SBUs. They both exhibit highly selective uptake for CO2 over CH4 and N2 under ambient conditions. More importantly, MOF-1 also provides an ideal luminescence sensor for selective probing Ba2+ and Cu2+ ions based on significant luminescence enhancement or quenching. This journal is © 2013 The Royal Society of Chemistry.

Zhao Z.,Beijing University of Chemical Technology | Dai H.,Beijing University of Chemical Technology | Deng J.,Beijing University of Chemical Technology | Du Y.,Beijing University of Technology | And 2 more authors.
Microporous and Mesoporous Materials | Year: 2012

Three-dimensionally (3D) ordered macroporous (3DOM) La 0.6Sr 0.4FeO 3-δ (LSF-F127, LSF-PEG, LSF-PEG-EtOH, and LSF-Lysine) with mesoporous or nanovoid-like skeletons were prepared using the surfactant (Pluronic F127, poly(ethylene glycol) (PEG) or l-lysine)-assisted polymethyl methacrylate (PMMA)-templating method in aqueous or 40% ethanol aqueous solution. It is shown that the LSF samples displayed a 3DOM architecture and were of a single-phase orthorhombic crystal structure. The nature of surfactant and solvent could influence the pore structure and surface area of the final product. Treating the LSF precursor first in N 2 at 500 °C and then in air at 750 °C favored the formation of 3DOM-structured La 0.6Sr 0.4FeO 3-δ. The porous LSF catalysts performed well in toluene combustion, with LSF-PEG showing the best catalytic performance (T 10% = 54 °C, T 50% = 225 °C and T 90% = 280 °C at 20,000 mL/(g h)). It is concluded that the excellent catalytic performance of 3DOM-structured LSF is associated with their larger surface areas, higher oxygen adspecies concentrations, better low-temperature reducibility, and high-quality 3DOM structures. © 2012 Elsevier Inc. All rights reserved.

Zhao X.,Beijing University of Technology | Xia Z.,Beijing Institute of Technology | Xia D.,Peking University
Electrochimica Acta | Year: 2010

Sn/Cu nanowire composite film was electrodeposited on copper foil substrates and used as an anode material for lithium-ion batteries. The structure of the obtained composite film anode was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical performance was evaluated by cyclic voltammetry, galvanostatic cycling and impedance spectroscopy. It was found that the Sn/Cu nanowire composite film anode showed a better cycle stability than Sn film anode, whereas the Sn/CNT composite film anode indicated poor capacity retention. It could be deduced that copper nanowire reinforced the Sn film anode due to the better wetting property of Sn on the surface of copper and reduced the loss of electric contact among tin particles in the Sn/Cu nanowire composite film anode. © 2010 Elsevier Ltd. All rights reserved.

Gu X.,Peking University | Sun Q.,Peking University | Sun Q.,Beijing University of Technology
Physical Chemistry Chemical Physics | Year: 2013

Using density functional theory (DFT) and time-dependent DFT in different levels, we have systematically studied new porphyrin-based dyes with A-π-D structures focusing on optical absorption, light harvest efficiency, ground state oxidation potential, excited state oxidation potential, and natural transition orbitals. Compared with existing dyes, we find that these new dyes have wide absorption regions (400-1000 nm) with high molar extinction coefficients, and display good energy level alignment for efficient injection of electrons and fast regeneration of the oxidized dyes. This journal is © 2013 the Owner Societies.

Yang Y.,CAS Wuhan Institute of Rock and Soil Mechanics | Zheng H.,Beijing University of Technology
Engineering Fracture Mechanics | Year: 2016

A three-node triangular element fitted to the numerical manifold method with continuous nodal stress called Trig3-CNS (NMM) element for accurately modeling two-dimensional linear elastic fracture problems is presented. By adopting two cover systems, namely, the mathematical cover and physical cover, the numerical manifold method (NMM) could easily solve continuous and discontinuous problems in a unified way. In contrast to the three-node triangular element (Trig3), the Trig3-CNS element has higher order of approximations, much better accuracy and continuous nodal stress. Moreover, it is free from the "linear dependence" which otherwise cripples many of the partition of unity based methods with high order approximations. The purpose of the present work is to synergize the advantages of both the recently developed Trig3-CNS element and the NMM to precisely model two-dimensional linear elastic fracture problems. A number of numerical examples indicate the accuracy and robustness of the present Trig3-CNS (NMM) element. © 2016 Elsevier Ltd.

Yang Y.,Beijing University of Technology
Acta Mechanica Sinica/Lixue Xuebao | Year: 2016

The recent progress on non-local Lagrangian and quasi-Lagrangian structures in turbulence is reviewed. The quasi-Lagrangian structures, e.g., vortex surfaces in viscous flow, gas-liquid interfaces in multi-phase flow, and flame fronts in premixed combustion, can show essential Lagrangian following properties, but they are able to have topological changes in the temporal evolution. In addition, they can represent or influence the turbulent flow field. The challenges for the investigation of the non-local structures include their identification, characterization, and evolution. The improving understanding of the quasi-Lagrangian structures is expected to be helpful to elucidate crucial dynamics and develop structure-based predictive models in turbulence. © 2016 The Chinese Society of Theoretical and Applied Mechanics; Institute of Mechanics, Chinese Academy of Sciences and Springer-Verlag Berlin Heidelberg

Wu B.,Frankfurt Institute for Advanced Studies | Wu B.,Beijing University of Technology | Wu B.,Bielefeld University
Journal of High Energy Physics | Year: 2011

We study the contributions from radiation to p⊥-broadening of a high energy parton traversing a QCD medium with a finite length L. The interaction between the parton and the medium is described by decorrelated static multiple scattering. Amplitudes of medium-induced gluon emission and parton self-energy diagrams are evaluated in the soft gluon limit in the BDMPS formalism. We find both the double-logarithmic correction from incoherent scattering, which is parametrically the same as that in single scattering, and the logarithmic correction from the LPM effect. Therefore, we expect a parametrically large correction from radiation to the medium-induced p⊥-broadening in perturbative QCD. © 2011 SISSA.

Lei J.,Beijing University of Technology | Zhang C.,University of Siegen
European Journal of Mechanics, A/Solids | Year: 2014

The three generalized Barnett-Lothe tensors L, S and H are frequently encountered in the extended Stroh formalism of two-dimensional deformation of anisotropic magneto-electro-elastic materials. Meantime, they are directly related to the admittance matrix Y, which is required to characterize the crack-tip field. In this paper, the elements of L, S and H together with Y are constructed using a modified Lekhinitskii formalism for general anisotropic magneto-electro-elastic materials. As a typical case, the three generalized Barnett-Lothe tensors are explicitly expressed in terms of the reduced generalized elastic compliances for transversely isotropic magneto-electro- elastic materials. A simple example is presented to validate these expressions. © 2014 Elsevier Masson SAS. All rights reserved.

Yang G.-H.,Northeastern University China | Wang H.,Beijing University of Technology
IET Control Theory and Applications | Year: 2010

The study paper deals with sensor fault detection problem for a class of linear uncertain systems with bounded disturbances and non-zero constant reference inputs. The sensor faults are modelled as multi-mode, named as fault-free mode and faulty modes. A steady-state-based approach is proposed to detect the sensor faults. The steady-state-based approach can be used to detect lock-in-place sensor faults with arbitrary small magnitudes, which has not been well investigated in the literature. A convergent iterative algorithm based on linear matrix inequalities is given to obtain the solutions. A numerical example is given to illustrate the effectiveness of the proposed methods. © 2010 The Institution of Engineering and Technology.

Xiu C.,Beijing University of Technology
Journal of Computational Information Systems | Year: 2013

Chinese Word Segmentation is an important task in natural language processing for languages without word delimiters. In this paper we analyze the key issues in Chinese word segmentation from three degrees: the limitation of supervised segmentation, the shortcoming in unsupervised segmentation, and the relationship of OOV, ambiguity and word segmentation result. The analysis shows that supervised and unsupervised segmentation are not suitable for domain word segmentation. And the problem of ambiguity will be more serious than OOV in practical application. Copyright © 2013 Binary Information Press.

Toth T.,Ecole Polytechnique Federale de Lausanne | Gong Q.,Beijing University of Technology | Zhao J.,Ecole Polytechnique Federale de Lausanne
Tunnelling and Underground Space Technology | Year: 2013

This paper investigates the performance of tunnel boring machines (TBMs) in rock-soil mixed-face ground based on TBM tunneling projects in Singapore. Currently several methods are available to estimate TBM tunneling performance in homogenous rock or soil. However, the existing models cannot be effectively applied to predict TBM penetration rate in mixed ground. The tunnels in this study were excavated in adverse mixed-face ground conditions. The geological profiles and the TBM operational parameters are compiled and analyzed. The influence of different geological face compositions on the performance of the TBMs is studied. The statistical analysis shows that there is a possible correlation between the mixed-face ground characteristics and the TBM advancement. Different approaches are used to find a reliable model. Finally, a method is proposed to predict the TBM performance in mixed-face ground for project planning and optimization. © 2013 Elsevier Ltd.

Zhang P.,Beijing University of Technology
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2010

We show that the nucleon spectrum in a hard-wall anti-de Sitter/QCD model can be improved by use of a relatively large IR cutoff. All of the spin-1/2 nucleon masses listed in the Particle Data Group can be fit quite well within 11%. The average error is remarkably only 4.66%. © 2010 The American Physical Society.

Fu W.-J.,CAS Institute of Theoretical Physics | Liu Y.-X.,Beijing University of Technology | Liu Y.-X.,Accelerator Centre | Wu Y.-L.,CAS Institute of Theoretical Physics
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2010

We study fluctuations of conserved charges including baryon number, electric charge, and strangeness as well as the correlations among these conserved charges in the 2+1 flavor Polyakov-Nambu-Jona-Lasinio model at finite temperature. The calculated results are compared with those obtained from recent lattice calculations performed with an improved staggered fermion action at two values of the lattice cutoff with almost physical up and down quark masses and a physical value for the strange quark mass. We find that our calculated results are well consistent with those obtained in lattice calculations except for some quantitative differences for fluctuations related with strange quarks. Our calculations indicate that there is a pronounced cusp in the ratio of the quartic to quadratic fluctuations of baryon number, i.e. χ4B/χ2B, at the critical temperature during the phase transition, which confirms that χ4B/χ2B is a useful probe of the deconfinement and chiral phase transition. © 2010 The American Physical Society.

Shao L.,Beijing University of Technology | Ma B.-Q.,Peking University
Modern Physics Letters A | Year: 2010

Lorentz violation (LV) is predicted by some quantum gravity (QG) candidates, wherein the canonical energymomentum dispersion relation, E 2 = p2+m2, is modified. Consequently, new phenomena beyond the standard model are predicted. In particular, the presence of LV highly affects the propagation of astrophysical photons with very high energies from distant galaxies. In this paper, we review the updating theoretical and experimental results on this topic. We classify the effects into three categories: (i) time lags between photons with different energies; (ii) a cutoff of photon flux above the threshold energy of photon decay, γ→e++e-; (iii) new patterns in the spectra of multi-TeV photons and EeV photons, due to the absorption of background lights. As we can see, the details of LV effects on astrophysical photons depend heavily on the "phase space" of LV parameters. From observational aspects, available and upcoming instruments can study these phenomena hopefully, and shed light onto LV issues and QG theories. The most recent progresses and constraints on the ultra-high energy cosmic rays (UHECRs) are also discussed. © 2010 World Scientific Publishing Company.

Wang Z.-X.,Dalian University of Technology | Wei L.,Dalian University of Technology | Wang X.,Beijing University of Technology
Physics of Plasmas | Year: 2012

The effect of q-profiles on the excitation of high-order harmonic q 1 tearing modes during sawtooth crashes is investigated by a collisionless fluid model with the electron inertia term in Ohm's law. It is found that for a flat q-profile in the core region, the high-order harmonics, such as m / n 2 / 2 and/or m / n 3 / 3 modes, comparable to or stronger than the m / n 1 / 1 component, can be excited during tokamak sawteeth. The stronger the magnetic shear on the q 1 surface is, the more unstable the higher- m modes are. For smoothly monotonously increased q-profiles, a lower q value on the plasma edge tends to easily excite higher-m harmonics at the same level as the m 1 mode simultaneously. The spatial characteristics of the eigenmodes in the cases with the typical q-profiles are also discussed. In addition, the basic feature of the magnetic island structures in the nonlinear evolution is numerically obtained, which is consistent qualitatively with the experimentally reconstructed phenomenon. © 2012 American Institute of Physics.

Yang Q.,Beijing University of Chemical Technology | Liu D.,Beijing University of Chemical Technology | Zhong C.,Beijing University of Chemical Technology | Li J.-R.,Beijing University of Technology
Chemical Reviews | Year: 2013

The article highlights both the successes and the limitations of various computational methodologies for metal-organic frameworks (MOF). As an illustration, we provide a state-of-the-art review on modeling studies of gas separations in MOFs using these new methods and concepts. Development of computational methods often requires evaluation of intermolecular interactions in which electrostatic forces may be the dominant long-range contributions. In most cases, to represent the electrostatic potentials of MOFs, assignment of partial charges for their framework atoms is a good compromise between computational effectiveness and accuracy. In addition, atomic partial charges can be regarded as a convenient representation of the asymmetric distribution of electrons in chemical bonds. Due to very good descriptions of intermolecular interactions using Coulomb potential, electrostatic potential (ESP) derived charges are perhaps the most widely adopted charge type in molecular modeling.

Liu J.,Beijing University of Technology | Qin H.,Princeton Plasma Physics Laboratory | Qin H.,Anhui University of Science and Technology
Physics of Plasmas | Year: 2011

We study the dynamics of the gyrophase of a charged particle in a magnetic field which is uniform in space but changes slowly with time. As the magnetic field evolves slowly with time, the changing of the gyrophase is composed of two parts. The first part is the dynamical phase, which is the time integral of the instantaneous gyrofrequency. The second part, called geometric gyrophase, is more interesting, and it is an example of the geometric phase which has found many important applications in different branches of physics. If the magnetic field returns to the initial value after a loop in the parameter space, then the geometric gyrophase equals the solid angle spanned by the loop in the parameter space. This classical geometric gyrophase is compared with the geometric phase (the Berry phase) of the spin wave function of an electron placed in the same adiabatically changing magnetic field. Even though gyromotion is not the classical counterpart of the quantum spin, the similarities between the geometric phases of the two cases nevertheless reveal the similar geometric nature of the different physics laws governing these two physics phenomena. © 2011 American Institute of Physics.

Chen W.,Beijing University of Technology | Zhu S.-L.,Peking University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2011

After constructing all the tetraquark interpolating currents with JPC=1-+, 1-, 1++ and 1 +- in a systematic way, we investigate the two-point correlation functions to extract the masses of the charmoniumlike states with QCD sum rule. For the 1- qcq̄c̄ charmoniumlike state, mX=4.6∼4.7GeV, which implies a possible tetraquark interpretation for the state Y(4660). The masses for both the 1++ qcq̄c̄ and scs̄c̄ charmoniumlike states are around 4.0∼4.2GeV, which are slightly above the mass of X(3872). For the 1-+ and 1 +- qcq̄c̄ charmoniumlike states, the extracted masses are around 4.5∼4.7GeV and 4.0∼4.2GeV, respectively. As a by-product, the bottomoniumlike states are also studied. We also discuss the possible decay modes and experimental search of the charmoniumlike states. © 2011 American Physical Society.

Feng R.,Peking University | Liu K.,Peking University | Liu K.,Beijing University of Technology
Physica B: Condensed Matter | Year: 2012

The mechanism for the shift of the band-gap in two kinds of finite phononic crystals (PCs) (steel/epoxy and aluminum/epoxy) with different initial stresses is studied experimentally and theoretically. The experimental results and theoretical analysis simultaneously indicate that the initial stress will efficiently tune the location and width of the band-gap. The current work provides a basis for tuning the band-gap of phononic crystals in engineering applications. © 2012 Elsevier B.V. All rights reserved.

Ye L.,University of Queensland | Ye L.,Beijing University of Technology | Pijuan M.,University of Queensland | Yuan Z.,University of Queensland
Water Research | Year: 2010

Nitrite/Free Nitrous Acid (FNA) has previously been shown to inhibit aerobic and anoxic phosphate uptake by polyphosphate accumulating organisms (PAOs). The inhibitory effect of FNA on the aerobic metabolism of Glycogen Accumulating Organisms (GAOs) is investigated. A culture highly enriched (92 ± 3%) in Candidatus Competibacter phosphatis (hereafter called Competibacter) was used. The experimental data strongly suggest that FNA likely directly inhibits the growth of Competibacter, with 50% inhibition occurring at 1.5 × 10-3 mgN-HNO2/L (equivalent to approximately 6.3 mgN-NO2 -/L at pH 7.0). The inhibition is well described by an exponential function. The organisms ceased to grow at an FNA concentration of 7.1 × 10-3 mgN-HNO2/L. At this FNA level, glycogen production, another anabolic process performed by GAOs in parallel to growth, decreased by 40%, while the consumption of polyhydroxyalkanoates (PHAs), the intracellular carbon and energy sources for GAOs, decreased by approximately 50%. FNA likely inhibited either or both of the PHA oxidation and glycogen production processes, but to a much less extent in comparison to the inhibition on growth. The comparison of these results with those previously reported on PAOs suggest that FNA has much stronger inhibitory effects on the aerobic metabolism of PAOs than on GAOs, and may thus provide a competitive advantage to GAOs over PAOs in enhanced biological phosphorus removal (EBPR) systems. © 2010 Elsevier Ltd. All rights reserved.

Draper P.,University of Chicago | Liu T.,University of Chicago | Liu T.,University of California at Santa Barbara | Wagner C.E.M.,University of Chicago | And 4 more authors.
Physical Review Letters | Year: 2011

We study a limit of the nearly Peccei-Quinn-symmetric next-to-minimal supersymmetric standard model possessing novel Higgs and dark matter (DM) properties. In this scenario, there naturally coexist three light singletlike particles: a scalar, a pseudoscalar, and a singlinolike DM candidate, all with masses of order 0.1-10 GeV. The decay of a standard model-like Higgs boson to pairs of the light scalars or pseudoscalars is generically suppressed, avoiding constraints from collider searches for these channels. For a certain parameter window annihilation into the light pseudoscalar and exchange of the light scalar with nucleons allow the singlino to achieve the correct relic density and a large direct-detection cross section consistent with the DM direct-detection experiments, CoGeNT and DAMA/LIBRA, preferred region simultaneously. This parameter space is consistent with experimental constraints from LEP, the Tevatron, Υ, and flavor physics. © 2011 American Physical Society.

Wang Z.-X.,Dalian University of Technology | Wei L.,Dalian University of Technology | Wang X.,Beijing University of Technology | Liu Y.,Dalian University of Technology
Physics of Plasmas | Year: 2011

Reversed magnetic shear configuration, a key method for improving plasma confinement in advanced tokamaks, is prone to exciting double tearing modes (DTMs) that can severely degrade the plasma confinement. In this letter, we reveal a new mechanism of suppressing the DTM instability due to the self-induced Alfvén resonance in rotating tokamak plasmas. The linear growth rate is reduced from ∼ S Hp - 1 / 3 of the fast DTM regime to ∼ S Hp - 3 / 5 of the slow single tearing mode regime, where S Hp is magnetic Reynolds number. Instead of generating magnetic islands at the inner rational surface that can greatly enhance plasma transport in the core region, the formation of current sheets at resonance layers not only prevents the fast nonlinear DTM reconnection phase but also contributes to plasma heating. © 2011 American Institute of Physics.

Zhang P.,Beijing University of Technology
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2010

We study further the soft-wall AdS/QCD model with a cubic potential for the bulk scalar. We analyze the spectra of pseudoscalar, scalar, vector, and axial-vector mesons. We also study the spin-1/2 nucleon spectrum and the pion-nucleon coupling. All of them have a good agreement with the experimental data. © 2010 The American Physical Society.

Chen D.-Y.,Lanzhou University | Chen D.-Y.,CAS Institute of Physics | Liu X.,Lanzhou University | Zhu S.-L.,Beijing University of Technology
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2011

Inspired by the newly observed two charged bottomoniumlike states, we consider the possible contribution from the intermediate Zb(10610) and Zb(10650) states to the Υ(5S)→Υ(2S) π+π- decay process, which naturally explains Belle's previous observation of the anomalous Υ(2S)π+π - production near the peak of Υ(5S) at √s=10.87GeV. The resulting dΓ(Υ(5S)→Υ(2S)π+π-)/ dmπ+π- and dΓ(Υ(5S) →Υ(2S)π+π-)/dcosθ distributions agree with Belle's measurement after inclusion of these Zb states. This formalism also reproduces the Belle observation of the double-peak structure and its reflection in the Υ(2S)π+ invariant mass spectrum of the Υ(5S)→Υ(2S)π+π- decay. © 2011 American Physical Society.

Liu Y.,Tsinghua University | Peng Y.,Beijing University of Technology
Science China: Physics, Mechanics and Astronomy | Year: 2011

Using the concept of base forces as state variables, a new finite element method - the base force element method (BFEM) on complementary energy principle for linear elasticity problems is presented. Firstly, an explicit expression of compliance matrix for an element is derived through base forces by dyadic vectors. Then, the explicit control equations of finite element method of complementary energy principle are derived using Lagrange multiplier method. Thereafter, the base forces element procedure for linear elasticity is developed. Finally, several examples are analyzed to illustrate the reliability and accuracy of the formulation and the procedure. © 2011 Science China Press and Springer-Verlag Berlin Heidelberg.

Peng J.,Beijing Normal University | Zhao P.W.,Kyoto University | Zhao P.W.,Beijing University of Technology
Physical Review C - Nuclear Physics | Year: 2015

The self-consistent tilted axis cranking relativistic mean-field (TAC-RMF) theory based on a point-coupling interaction is applied to investigate the observed magnetic and antimagnetic rotations in the nucleus Cd110. The energy spectra, the relation between the spin and the rotational frequency, the deformation parameters, and the reduced M1 and E2 transition probabilities are studied with the various configurations. It is found that the configuration has to be changed to reproduce the energy spectra and the relations between the spin and the rotational frequency for both the magnetic and antimagnetic rotational bands. The shears mechanism for the magnetic rotation and the two-shears-like mechanism for the antimagnetic rotation are examined by investigating the orientation of the neutron and proton angular momenta. The calculated electromagnetic transitions B(M1) and B(E2) are in reasonable agreement with the data, and their tendencies are coincident with the typical characteristics of the magnetic and antimagnetic rotations. © 2015 American Physical Society.

Pijuan M.,University of Queensland | Pijuan M.,Catalan Institute for Water Research | Ye L.,University of Queensland | Ye L.,Beijing University of Technology | Yuan Z.,University of Queensland
Water Research | Year: 2010

In full-scale wastewater treatment systems, phosphorus removal typically occurs together with nitrogen removal. Nitrite, an intermediate of both the nitrification and denitrification processes, can accumulate in the reactor. The inhibitory effect of nitrite/free nitrous acid (FNA) on the aerobic metabolism of poly-phosphate accumulating organisms (PAOs) is investigated. A culture highly enriched (90 ± 5%) in Candidatus "Accummulibacter phosphatis", a well-known PAO, was used to perform a series of batch experiments at various nitrite and pH levels. FNA was found to inhibit all key aerobic metabolic processes performed by PAOs, namely PHA oxidation, phosphate uptake, glycogen replenishment and growth. The inhibitory effect on the anabolic processes (growth, phosphate uptake and glycogen production) was much stronger than that on the catabolic processes (PHA oxidation). 50% inhibition on all anabolic processes occurred at FNA concentrations of approximately 0.5 × 10-3 mg HNO2-N/L (equivalent to 2.0 mg NO2 --N/L at pH 7.0), while full inhibition occurred at FNA concentrations of approximately 6.0 × 10-3 mg HNO2-N. These concentrations could be found in full-scale wastewater treatment systems that achieve nitrogen removal via the nitrite pathway. In comparison, PHA oxidation remained at 40-50% of the highest rate at FNA concentrations in the range 2.0 × 10-3-10.0 × 10-3 mg HNO2-N/L. Interestingly, PAOs were able to reduce nitrite under aerobic conditions (DO ≈ 3 mg/L), with the rate increasing substantially with the FNA concentration. The inhibition on phosphate uptake was found to be reversible. © 2010 Elsevier Ltd.

Kelley R.,Harvard University | Schwartz M.D.,Harvard University | Schabinger R.M.,Autonomous University of Madrid | Zhu H.X.,Beijing University of Technology
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2011

The hemisphere soft function is calculated to order αs2. This is the first multiscale soft function calculated to two loops. The renormalization scale dependence of the result agrees exactly with the prediction from effective field theory. This fixes the unknown coefficients of the singular parts of the two-loop thrust and heavy-jet mass distributions. There are four such coefficients, for 2 event shapes and 2 color structures, which are shown to be in excellent agreement with previous numerical extraction. The asymptotic behavior of the soft function has double logs in the CFCA color structure, which agree with nonglobal log calculations, but also has subleading single logs for both the CFCA and C FTFnf color structures. The general form of the soft function is complicated, does not factorize in a simple way, and disagrees with the Hoang-Kluth ansatz. The exact hemisphere soft function will remove one source of uncertainty on the αs fits from e+e - event shapes. © 2011 American Physical Society.

Wang Z.,CAS Institute of Mechanics | Wang Z.,Beijing University of Technology | Zhao Y.,CAS Institute of Mechanics
Science China: Physics, Mechanics and Astronomy | Year: 2011

In the framework of continuum thermodynamics, the present paper presents the thermo-hyperelastic models for both the surface and the bulk of nanostructured materials, in which the residual stresses are taken into account. Due to the existence of residual stresses, different configuration descriptions of the surface (or the bulk) thermo-hyperelastic constitutive equations are not the same even in the cases of infinitesimal deformation. As an example, the effective thermal expansion coefficient of spherical nanoparticles is analyzed. © Science China Press and Springer-Verlag Berlin Heidelberg 2011.

Yu P.-Z.,Beijing University of Technology
Petroleum Science | Year: 2015

Cationic polymer fluid loss additive (CPFL) was prepared by using the reaction of 2,3-epoxypropyltrimethyl ammonium chloride (EPTMAC) (as cationic reagent) with the amide group in the molecular structure of the sodium salt of partially hydrolyzed polyacrylonitrile fibers (HPAN-Na). The chemical reaction was determined by studying the infrared absorption peaks of the materials and the products. The results proved that the cationic groups of EPTMAC were successfully grafted onto the HPAN molecular chain. The composition of the molecular chain of the product CPFL was determined by investigation and calculation of the elemental analysis results of the grafted HPAN and the final reaction product CPFL. The drilling fluid performance was evaluated, and the result showed that when the cation content was more than 0.27 mmol/g, the drilling fluid would have good resistance to fluid loss and to pollution from calcium chloride. © 2015, The Author(s).

Yang G.-H.,Northeastern University China | Wang H.,Beijing University of Technology
IEEE Transactions on Control Systems Technology | Year: 2010

This brief studies the problem of fault detection for a class of uncertain state-feedback tracking control systems with constant reference inputs and bounded disturbances. The considered systems are modeled via multiple modes, namely, fault-free case and faulty cases. Actuator stuck faults, including outage cases, are considered. With the aid of the finite-frequency positive-realness approach, a new linear-matrix-inequality-based fault detection method for control systems is obtained and applied to fault detection for flight control systems. An F-18 aircraft model is included in the simulation to illustrate the effectiveness of the proposed method. © 2009 IEEE.

Wei Z.,Beijing University of Technology | Zhang W.,Wuhan University
International Journal of Bifurcation and Chaos | Year: 2014

This paper reports the finding of a four-dimensional (4D) non-Sil'nikov autonomous system with three quadratic nonlinearities, which exhibits some behavior previously unobserved: hidden hyperchaotic attractors with only one stable equilibrium. The algebraical form of the non-Sil'nikov chaotic attractor is very similar to the hyperchaotic Lorenz-Stenflo system but they are different and, in fact, nonequivalent in topological structures. Of particular interest is the fact this system has only one stable equilibrium, but can exhibit hidden hyperchaos, chaos, periodic orbit. Moreover, the coexistence of attracting sets can be obtained in the system for some parameter values and different initial conditions, such as hyperchaotic attractor and point, hyper-chaotic attractor and period orbit. To further analyze the new system, the ultimate bound and positively invariant set for the modified hyperchaotic Lorenz-Stenflo system are also obtained. Moreover, the complete mathematical characterizations for 4D Hopf bifurcation are rigorously derived and studied. © World Scientific Publishing Company.

Wu J.-B.,CAS Institute of High Energy Physics | Zhu M.-Q.,Beijing University of Technology
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

In this paper, we first compute the Killing spinors of AdS4×Q1,1,1 and its certain orbifolds. Based on this, two classes of M2-brane solutions are found. The first class of solutions includes M2-branes dual to Wilson loops in the fundamental representation as a special case. The second class includes the candidates of the holographic description of vortex loops in the dual field theories. © 2014 American Physical Society.

Zhao X.,Beijing University of Technology | Soh A.K.,University of Selangor
Functional Materials Letters | Year: 2015

The temporal evolution of domain structure and its piezoelectric behavior of ferroelectric material BaTiO3 during the transition process from rhombohedral to tetragonal phase under an applied electric field have been studied by employing Landau-Ginzburg theory and the phase-field method. The results obtained show that, during the transformation process, the intermediate phase was monoclinic MA phase, and several peak values of piezoelectric coefficient appeared at the stage where obvious change of domain pattern occurred. In addition, by comparing the cases of applied electric field with different frequencies, it was found that the maximum piezoelectric coefficient obtained decreased with increasing frequency value. These results are of great significance in tuning the properties of engineering domains in ferroelectrics, and could provide more fundamentals to the design of ferroelectric devices. © 2015 World Scientific Publishing Company.

Liu F.,Beijing University of Technology
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011

Image segmentation remains one of the major challenges in image analysis and computer vision. Fuzzy clustering, as a soft segmentation method, has been widely studied and successfully applied in mage clustering and segmentation. The fuzzy c-means (FCM) algorithm is the most popular method used in mage segmentation. However, most clustering algorithms such as the k-means and the FCM clustering algorithms search for the final clusters values based on the predetermined initial centers. The FCM clustering algorithms does not consider the space information of pixels and is sensitive to noise. In the paper, presents a new fuzzy c-means (FCM) algorithm with adaptive evolutionary programming that provides image clustering. The features of this algorithm are: 1) firstly, it need not predetermined initial centers. Evolutionary programming will help FCM search for better center and escape bad centers at local minima. Secondly, the spatial distance and the Euclidean distance is also considered in the FCM clustering. So this algorithm is more robust to the noises. Thirdly, the adaptive evolutionary programming is proposed. The mutation rule is adaptively changed with learning the useful knowledge in the evolving process. Experiment results shows that the new image segmentation algorithm is effective. It is providing robustness to noisy images. © 2011 SPIE.

Shao H.-S.,Beijing University of Technology
Journal of High Energy Physics | Year: 2014

Based on Monte Carlo techniques, we analyze the initial state radiation (ISR) effects in prompt J/ inclusive production at B factories. ISR enhances cross section (e-e+ → J/ψ +gg+X) by about 15-25%, which is almost the same size as the QCD and relativistic correction. Moreover, ISR slightly changes (e-e+ → J/ψ +cc+X). The J/ momentum spectrum in e-e+ → J/ψ +gg+X and in e-e+ → J/ψ+cc+X is softer after the photon showering from the initial e± beam radiation. After combining the QCD,relativistic, and ISR corrections,a more precise theoretical result is obtained. The new result provides a more stringent constraint of the color-octet contribution to (e-e+ → J/ψ + X non-cc). © The Authors.

Liu H.L.,Xian Jiaotong University | Walker P.M.,University of Surrey | Xu F.R.,Beijing University of Technology
Physical Review C - Nuclear Physics | Year: 2014

Configuration-constrained potential-energy-surface calculations are performed including β6 deformation to investigate high-K isomeric states in nuclei around 254No and 270Ds, the heaviest nuclei where there have been some observations of two-quasiparticle isomers, while data for four-quasiparticle isomers are scarce. We predict the prevalent occurrence of four-quasiparticle isomeric states in these nuclei, together with their favored configurations. The most notable examples, among others, are Kπ=20+ states in 266,268Ds and 268,270Cn having very high K value, relatively low excitation energy, and well-deformed axially symmetric shape. The predicted isomeric states, with hindered spontaneous fission and α decay, could play a significant role in the future study of superheavy nuclei. © 2014 American Physical Society.

Xi P.W.,Beijing University of Technology | Xi P.W.,Lawrence Livermore National Laboratory | Xu X.Q.,Lawrence Livermore National Laboratory | Diamond P.H.,National Fusion Research Institute | Diamond P.H.,University of California at San Diego
Physical Review Letters | Year: 2014

We derive a new nonlinear criterion for the occurrence of fast relaxation (crash) events at the edge of high-confinement-mode plasmas. These fast relaxation events called ELMs (edge-localized modes) evolve from ideal magnetohydrodynamics (MHD) instabilities, but the crash is not due only to linear physics. We show that for an ELM crash to occur, the coherence time of the relative phase between potential and pressure perturbations must be long enough to allow growth to large amplitude. This phase coherence time is determined by both linear and nonlinear dynamics. An ELM crash requires that the instability growth rate exceed a critical value, i.e., γ>γc, where γc is set by 1/τc and τc is the phase coherence time. For 0<γ<γc, MHD turbulence develops and drives enhanced turbulent transport. The results indicate that the shape of the growth rate spectrum γ(n) is important to whether the result is a crash or turbulence. We demonstrate that ELMs can be mitigated by reducing the phase coherence time without changing linear instability. These findings also offer an explanation of the occurrence of ELM-free H-mode regimes. © 2014 American Physical Society.

Song H.,Beijing University of Technology | Bass S.A.,Duke University | Heinz U.,Ohio State University
Physical Review C - Nuclear Physics | Year: 2014

Using the vishnu hybrid model that couples (2+1)-dimensional viscous hydrodynamics to a microscopic hadronic transport model, we calculate the multiplicity, pT spectra, and elliptic flow for pions, kaons, and protons in 2.76A TeV Pb+Pb collisions, using mc-kln initializations with smoothed initial conditions, obtained by averaging over a large number of events. The results from our calculations are compared to data from the ALICE Collaboration, showing nice agreement over several centrality bins. Using the same inputs, we predict the pT spectra and elliptic flow for Ï• mesons and explore their flow development in the strong and weak coupling limits through hydrodynamic calculations with different decoupling temperatures. In addition we study the influence of baryon and antibaryon annihilation processes on common observables and demonstrate that, by including annihilation processes below a switching temperature of 165 MeV, vishnu provides a good description of the multiplicity and pT spectra for pions, kaons, and protons measured by PHENIX and ALICE at both the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). © 2014 American Physical Society.

Liu C.,Hong Kong Polytechnic University | Jing X.,Hong Kong Polytechnic University | Daley S.,University of Southampton | Li F.,Beijing University of Technology
Mechanical Systems and Signal Processing | Year: 2015

Micro-vibration caused by disturbance sources onboard spacecraft can severely degrade the working environment of sensitive payloads. Some notable vibration control methods have been developed particularly for the suppression or isolation of micro-vibration over recent decades. Usually, passive isolation techniques are deployed in aerospace engineering. Active isolators, however, are often proposed to deal with the low frequency vibration that is common in spacecraft. Active/passive hybrid isolation has also been effectively used in some spacecraft structures for a number of years. In semi-active isolation systems, the inherent structural performance can be adjusted to deal with variation in the aerospace environment. This latter approach is potentially one of the most practical isolation techniques for micro-vibration isolation tasks. Some emerging advanced vibration isolation methods that exploit the benefits of nonlinearity have also been reported in the literature. This represents an interesting and highly promising approach for solving some challenging problems in the area. This paper serves as a state-of-the-art review of the vibration isolation theory and/or methods which were developed, mainly over the last decade, specifically for or potentially could be used for, micro-vibration control. © 2014 Elsevier Ltd. All rights reserved.

Li Q.,Beijing University of Technology | Yan Q.-S.,University of Chinese Academy of Sciences | Yan Q.-S.,Peking University | Zhao X.,University of Chinese Academy of Sciences
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

Higgs pair production is crucial for measuring the Higgs boson self-coupling. The dominant channel at hadron colliders is gluon fusion via heavy-quark loops. We present the results of a fully exclusive simulation of gluon fusion Higgs pair production based on the matrix elements for hh+0, 1 partons including full heavy-quark loop dependence, matched to a parton shower. We examine and validate this new description by comparing it with (a) Higgs effective theory predictions, (b) exact hh+0-parton sample showered by Pythia, and (c) exact hh+1-parton distributions, by looking at the most relevant kinematic distributions, such as pTh, pThh, Mhh spectra, and the jet rate as well. We find that matched samples provide a state-of-the-art accurate exclusive description of the final state. © 2014 American Physical Society.

Liu H.,Beijing University of Technology | Yuan X.,Ecole Normale Superieure de Paris
Canadian Geotechnical Journal | Year: 2015

Microcracks and joints, two types of flaws that appear in a rock mass, affect both the rock mass strength and deformability. A model that can simultaneously reflect the effect of these two types of flaws on the mechanical behavior of a rock mass with persistent joints is not yet available. This study focusses on a microcracked rock mass with persistent joints and establishes a mechanical model, accounting for the anisotropy in the rock mass strength and deformability induced by the existence of the joints. Firstly, the compound damage variable from the coupling macroscopic and mesoscopic flaws is deduced based on the Lemaitre strain equivalence hypothesis. Secondly, the corresponding damage constitutive model for a jointed rock mass is set up. Thirdly, the joint shear failure criterion is incorporated into the constitutive model to extend the model. Finally, the results of the calculation examples show that the existence of the joint will reduce the strength, enlarge the deformability, and lead to anisotropy of the rock mass. A series of calculation examples and comparisons validate that the proposed model is capable of presenting the joint-induced anisotropy in rock mass strength and deformability, determining its possible failure modes, and reasonably simulating its complete stress-strain relationship. © 2014, National Research Council of Canada. All Rights Reserved.

Peng J.,Beijing Institute of Technology | He H.,Beijing Institute of Technology | Feng N.,Beijing University of Technology
Energies | Year: 2013

This paper presents a collaborative control system for an electric vehicle chassis based on a centralized and hierarchical control architecture. The centralized controller was designed for the suspension and steering system, which is used for improving ride comfort and handling stability; the hierarchical controller was designed for the braking system, which is used for distributing the proportion of hydraulic braking and regenerative braking to improve braking performance. These two sub-controllers function at the same level of the vehicle chassis control system. In order to reduce the potential conflict between the two sub-controllers and realize a coordination optimization of electric vehicle performance, a collaborative controller was built, which serves as the upper controller to carry out an overall coordination analysis according to vehicle signals and revises the decisions of sub-controllers. A simulation experiment was carried out with the MATLAB/Simulink software. The simulation results show that the proposed collaborative control system can achieve an optimized vehicle handling stability and braking safety. © 2013 by the authors; licensee MDPI, Basel, Switzerland.

Tian J.-y.,Harbin Institute of Technology | Chen Z.-l.,Harbin Institute of Technology | Yang Y.-l.,Beijing University of Technology | Liang H.,Harbin Institute of Technology | And 2 more authors.
Water Research | Year: 2010

Chemical cleaning of fouled hollow-fiber polyvinyl chloride (PVC) membrane with the consecutive use of NaOH and ethanol during ultrafiltration of river water was investigated in the study. Results showed that through the chemical cleaning with 1% NaOH for 30 min, a negative cleaning efficiency of -14.6% was observed for the PVC membrane. This might be due to the increase of membrane hydrophobicity, which was reflected by the increase of contact angle from 69.7° to 87.6°. On the other hand, the cleaning efficiency of 85.1% was obtained by the consecutive cleaning with 30 min of 1% NaOH and 30 min of ethanol. Individual ethanol cleaning could remove 48.5% of the irreversible resistance, indicating that NaOH cleaning also made its contribution (36.6%) to the removal of membrane foulants. Scanning electronic microscopy (SEM) and atomic force microscopy (AFM) analyses demonstrated that both NaOH and ethanol were not only able to eliminate the foulants on membrane surface, but also able to remove the in-pore fouling of the PVC membrane. The synergetic effects for removing membrane foulants were observed between the NaOH and ethanol. Furthermore, ethanol could also restore the hydrophilicity of the membrane by decreasing the contact angle from 87.6° to 71.4°. Considering that ethanol is easy to be used and reclaimed, the consecutive chemical cleaning by alkali and ethanol is recommended for PVC membrane in filtration of surface water. © 2009 Elsevier Ltd. All rights reserved.

Xue X.,CAS National Center for Nanoscience and Technology | Zhao Y.,CAS National Center for Nanoscience and Technology | Dai L.,CAS National Center for Nanoscience and Technology | Zhang X.,CAS National Center for Nanoscience and Technology | And 9 more authors.
Advanced Materials | Year: 2014

Tetraphenylethene and doxorubicin are assembled into a self-indicating drug delivery system (TD NPs). TD NPs are decomposed into DOX and TPE NPs in lysosome. Since TD NPs, TPE NPs and DOX are all fluorescent, the detachment of DOX from TPE NPs is accompanied by fluorescence changing. By observing the fluorescence changes, the spatiotemporal drug release is visualized. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Yuan X.,Beijing University of Technology
Ceramics International | Year: 2014

The grain boundary character distributions of sigma2 grain boundaries were investigated in WC-Co samples with different cobalt volume fractions. Specimens were prepared with cobalt fractions of 6 wt%, 8 wt% and 10 wt% respectively. The electron backscattered diffraction measurements show that with the increase of the cobalt fraction, the population of sigma2 boundaries decreases and sigma2 twist boundary keeps as the most common boundary type. The result suggests that the cobalt volume fraction could be determinant in controlling the population of sigma2 grain boundaries in cemented carbides. © 2013 Elsevier Ltd and Techna Group S.r.l.

Cao J.,Henan Normal University | Wang W.,Beijing University of Technology | Yang J.M.,CAS Institute of Theoretical Physics
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2011

We examine the present and future XENON limits on the neutralino dark matter in split supersymmetry (split-SUSY). Through a scan over the parameter space under the current constraints from collider experiments and the WMAP measurement of the dark matter relic density, we find that in the allowed parameter space a large part has been excluded by the present XENON100 limits and a further largish part can be covered by the future exposure (6000 kgday). In case of unobservation of dark matter with such an exposure in the future, the lightest neutralino will remain bino-like and its annihilation is mainly through exchanging the SM-like Higgs boson in order to get the required relic density. © 2011 Elsevier B.V.

Long J.,Beijing University of Technology
Journal of High Energy Physics | Year: 2014

Abstract: In this paper, we develop a perturbation formulation to calculate the single interval higher spin Rényi and entanglement entropy for two dimensional conformal field theory with (Formula Presented.) symmetry. The system is at finite temperature and is deformed by higher spin chemical potential. We manage to compute higher spin Rényi entropy with various spin deformations up to order (Formula Presented.). For spin 3 deformation, we calculate exact higher spin Rényi and entanglement entropy up to (Formula Presented.). When λ = 3, in the large c limit, we find perfect match with tree level holographic higher spin entanglement entropy up to order μ4 obtained by the Wilson line prescription. We also find quantum corrections to higher spin entanglement entropy which is beyond tree level holographic results. The quantum correction is universal at order μ4 in the sense that it is independent of λ. Our computation relies on a multi-valued conformal map from n-sheeted Riemann surface (formula presented)(formula presented) to complex plane and correlation functions of primary fields on complex plane. The method can be applied to general conformal field theories with (formula presented)(formula presented) symmetry. © 2014, The Author(s).

Alwall J.,National Taiwan University | Frederix R.,CERN | Frixione S.,CERN | Hirschi V.,SLAC | And 7 more authors.
Journal of High Energy Physics | Year: 2014

We discuss the theoretical bases that underpin the automation of the computations of tree-level and next-to-leading order cross sections, of their matching to parton shower simulations, and of the merging of matched samples that differ by light-parton multiplicities. We present a computer program, MadGraph5 aMC@NLO, capable of handling all these computations - parton-level fixed order, shower-matched, merged - in a unified framework whose defining features are flexibility, high level of parallelisation, and human intervention limited to input physics quantities. We demonstrate the potential of the program by presenting selected phenomenological applications relevant to the LHC and to a 1-TeV e + e - collider. While next-to-leading order results are restricted to QCD corrections to SM processes in the first public version, we show that from the user viewpoint no changes have to be expected in the case of corrections due to any given renormalisable Lagrangian, and that the implementation of these are well under way. © 2014 The Author(s).

Nie Z.R.,Beijing University of Technology
Journal of Alloys and Compounds | Year: 2013

The temporal evolution of the Al3(ErZr) precipitates is investigated in Al-0.04Er-0.04Zr and Al-0.04 Er-0.08Zr alloys during aging at elevated temperature of 450 and 500 °C. The results show that the coarsening behavior of the precipitates in both alloys is similar, due to the core-shell structure with Zr segregated in the shell of the Al3(ErZr) precipitates. With the increase of the amount of Zr addition, the misfit between the precipitate and the Al matrix decreases, consequently the coherency transition size of the precipitates in Al-0.04Er-0.08Zr is larger than that of Al-0.04Er-0.04Zr. After aging at 500 °C for 100 h, some of the precipitates in Al-0.04Er-0.08Zr transform to D023 structure due to the high Zr/Er ratio, while the precipitates in Al-0.04Er-0.04Zr keep the L12 structure. © 2013 Published by Elsevier B.V.

Han C.,CAS Institute of Theoretical Physics | Ji X.,CAS Institute of Theoretical Physics | Ji X.,Beijing University of Technology | Wu L.,University of Sydney | And 2 more authors.
Journal of High Energy Physics | Year: 2014

We consider the current experimental constraints on the parameter space of the MSSM and NMSSM. Then in the allowed parameter space we examine the Higgs pair production at the 14 TeV LHC via b̄b → hh (h is the 125 GeV SM-like Higg boson) with one-loop SUSY QCD correction and compare it with the production via gg → hh. We obtain the following observations: (i) For the MSSM the production rate of b̄b → hh can reach 50 fb and thus can be competitive with gg → hh, while for the NMSSM b̄b → hh has a much smaller rate than gg → hh due to the suppression of the hb̄b coupling; (ii) The SUSY-QCD correction to b̄b → hh is sizable, which can reach 45% for the MSSM and 15% for the NMSSM within the 1σ region of the Higgs data; (iii) In the heavy SUSY limit (all soft mass parameters become heavy), the SUSY effects decouple rather slowly from the Higgs pair production (especially the gg → hh process), which, for M SUSY = 5 TeV and m A < 1 TeV, can enhance the production rate by a factor of 1.5 and 1.3 for the MSSM and NMSSM, respectively. So, the Higgs pair production may be helpful for unraveling the effects of heavy SUSY. © 2014 The Author(s).

Li F.-M.,Harbin Institute of Technology | Li F.-M.,Beijing University of Technology | Song Z.-G.,Harbin Institute of Technology
Journal of Sound and Vibration | Year: 2013

Aerothermoelastic analysis for composite laminated panels in supersonic flow is carried out. The flutter and thermal buckling control for the panels are also investigated. In the modeling for the equation of motion, the influences of in-plane thermal load on the transverse bending deflection are taken into account, and the unsteady aerodynamic pressure in supersonic flow is evaluated by the linear piston theory. The governing equation of the structural system is developed applying the Hamilton's principle. In order to study the influences of aerodynamic pressure on the vibration mode shape of the panel, both the assumed mode method (AMM) and the finite element method (FEM) are used to derive the equation of motion. The proportional feedback control method and the linear quadratic regulator (LQR) are used to design the controller. The aeroelastic stability of the structural system is analyzed using the frequency-domain method. The effects of ply angle of the laminated panel on the critical flutter aerodynamic pressure and the critical buckling temperature change are researched. The flutter and thermal buckling control effects using the proportional feedback control and the LQR are compared. An effective method which can suppress the flutter and thermal buckling simultaneously is proposed. © 2013 Elsevier Ltd. All rights reserved.

Li J.-R.,Beijing University of Technology | Li J.-R.,Texas A&M University | Yu J.,Texas A&M University | Lu W.,Texas A&M University | And 4 more authors.
Nature Communications | Year: 2013

Despite tremendous efforts, precise control in the synthesis of porous materials with pre-designed pore properties for desired applications remains challenging. Newly emerged porous metal-organic materials, such as metal-organic polyhedra and metal-organic frameworks, are amenable to design and property tuning, enabling precise control of functionality by accurate design of structures at the molecular level. Here we propose and validate, both experimentally and computationally, a precisely designed cavity, termed a 'single-molecule trap', with the desired size and properties suitable for trapping target CO 2 molecules. Such a single-molecule trap can strengthen CO 2 -host interactions without evoking chemical bonding, thus showing potential for CO 2 capture. Molecular single-molecule traps in the form of metal-organic polyhedra are designed, synthesised and tested for selective adsorption of CO 2 over N 2 and CH 4, demonstrating the trapping effect. Building these pre-designed single-molecule traps into extended frameworks yields metal-organic frameworks with efficient mass transfer, whereas the CO 2 selective adsorption nature of single-molecule traps is preserved. © 2013 Macmillan Publishers Limited.

Liu Z.,Hefei University of Technology | Liu Z.,China Earthquake Administration | Huang J.,Beijing University of Technology | Peng Z.,Georgia Institute of Technology | Su J.,China Earthquake Administration
Geophysical Research Letters | Year: 2014

We investigate temporal changes of seismic velocity in the epicentral region of the 12 May 2008 Mw 7.9 Wenchuan earthquake using three-component continuous waveforms recorded by a seven-station small-aperture array. We use an ambient noise cross-correlation technique to compute the empirical Green's function between station pairs from August 2004 to September 2011. Our results show no obvious precursory change immediately before the main shock, clear coseismic reduction of seismic velocity of up to 0.2%, and initial postseismic recovery followed by a long-lived velocity reduction. The coseismic and postseismic velocity changes are most prominent in the period band of 2-4 s (approximate depth of 1-4 km), and the velocity changes are smaller in other period bands. The seismic velocity in the period band of 1-2 s (i.e., top 2 km) correlates well with the water level change of the Zipingpu Reservoir. The observed temporal changes likely reflect damage and healing processes with possible permanent deformation in the upper crust associated with the Wenchuan main shock. Key Points Clear coseismic velocity reduction during the Wenchuan main shock Initial postseismic recovery followed by a long-lived velocity reduction Negative correlation between velocity change and the Zipingpu water level ©2013. American Geophysical Union. All Rights Reserved.

Gehrlein J.,Karlsruhe Institute of Technology | Petcov S.T.,International School for Advanced Studies | Petcov S.T.,University of Tokyo | Petcov S.T.,Bulgarian Academy of Science | And 2 more authors.
Nuclear Physics B | Year: 2015

In this paper we discuss a minor modification of a previous SU(5)×A5 flavour model which exhibits at leading order golden ratio mixing and sum rules for the heavy and the light neutrino masses. Although this model could predict all mixing angles well it fails in generating a sufficient large baryon asymmetry via the leptogenesis mechanism. We repair this deficit here, discuss model building aspects and give analytical estimates for the generated baryon asymmetry before we perform a numerical parameter scan. Our setup has only a few parameters in the lepton sector. This leads to specific constraints and correlations between the neutrino observables. For instance, we find that in the model considered only the neutrino mass spectrum with normal mass ordering and values of the lightest neutrino mass in the interval 10-18 meV are compatible with the current data on the neutrino oscillation parameters. With the introduction of only one NLO operator, the model can accommodate successfully simultaneously even at 1σ level the current data on neutrino masses, on neutrino mixing and the observed value of the baryon asymmetry. © 2015 The Authors.

Xu W.-S.,Ningbo University | Zeng D.-F.,Beijing University of Technology
Nuclear Physics B | Year: 2015

We study a quark-monopole bound system moving in N=4 SYM plasma with a constant velocity by the AdS/CFT correspondence. The screening length of this system is calculated, and it is smaller than that of the quark-antiquark bound state. © 2014.

Zhou L.,CAS Research Center for Eco Environmental Sciences | Wang Y.,CAS Research Center for Eco Environmental Sciences | Long X.-E.,Chinese Institute of Urban Environment | Guo J.,Beijing University of Technology | Zhu G.,CAS Research Center for Eco Environmental Sciences
FEMS Microbiology Letters | Year: 2014

The discovery of nitrite-dependent anaerobic methane oxidation (n-damo) mediated by 'Candidatus Methylomirabilis oxyfera' with nitrite and methane as substrates has connected biogeochemical carbon and nitrogen cycles in a new way. The paddy fields often carry substantial methane and nitrate, thus may be a favorable habitat for n-damo bacteria. In this paper, the vertical-temporal molecular fingerprints of M. oxyfera-like bacteria, including abundance and community composition, were investigated in a paddy soil core in Jiangyin, near the Yangtze River. Through qPCR investigation, high abundance of M. oxyfera-like bacteria up to 1.0 × 108 copies (g d.w.s.)-1 in summer and 8.5 × 107 copies (g d.w.s.)-1 in winter was observed in the ecotone of soil and groundwater in the paddy soil core, which was the highest in natural environments to our knowledge. In the ecotone, the ratio of M. oxyfera-like bacteria to total bacteria reached peak values of 2.80% in summer and 4.41% in winter. Phylogenetic analysis showed n-damo bacteria in the paddy soil were closely related to M. oxyfera and had high diversity in the soil/groundwater ecotone. All of the results indicated the soil/groundwater ecotone of the Jiangyin paddy field was a favorable environment for the growth of n-damo bacteria. © 2014 Federation of European Microbiological Societies.

Yu H.-B.,Beijing University of Technology
Xitong Gongcheng Lilun yu Shijian/System Engineering Theory and Practice | Year: 2014

We study the effect of demand uncertainty on two classes of newsvendor problems by using stochastic dominance and variability orderings in applied probability, one is the classical newsvendor problem with minimization cost, the other is the newsvendor problem with maximization profit with two ordering policy. We get the monotonicities of the optimal cost (optimal profit) corresponding to the two classes of newsvendor problems with respect to the shortage penalty cost (two ordering cost), and equivalence of the two classes of newsvendor problems from the optimization and stochastic comparison's point of view. For the newsvendor problem with maximization profit, we provide the sufficient conditions to compare newsvendor's optimal profit under the dispersive ordering, and show that stochastic larger demand leads to larger newsvendor's optimal profit when two ordering cost is smaller than or equal to sales price, however, this result may not be true when two ordering cost is larger than sales price. We show that the optimal profit will decrease when demand variability increasing under the second degree stochastic dominance for any two ordering cost, and there exists a certain demand distribution, the optimal profit will increase when demand variability increases for those two ordering cost that is larger than a fixed value. We obtain similar results for the newsvendor problem with minimization cost. Several numerical examples are provided to show those obtained results.

Tiejun D.,Beijing University of Technology
Resources, Conservation and Recycling | Year: 2015

The application of material flow analysis (MFA) as a tool produces an objective assessment on scale, structure, operation efficiency and other aspects of the development of iron and steel industry in Hebei Province. This study is based on the framework of "Economy-wide material flow accounts and derived indicators: A methodological guide;" however, some necessary corrections have been made for the analysis of material metabolism according to the characteristics of industrial MFA and the reality in the Hebei iron and steel industry (HISI). Two panoramic MFA analyses of HISI in 2005 and 2010 were conducted respectively, which form a continuous analysis of scale, structure, and efficiency in material metabolism for HISI. The results show that between 2005 and 2010, there was a rapid development of HISI as a result of huge consumption of resource and energy. Between these years, the material inputs and material consumption increased by 3.30 times and 4.98 times, respectively, leading to serious environmental degradation and significant waste of resource and energy. Although the scale of material metabolism kept increasing, the rate of increase slowed. Hence, the total amount of waste emission increased year after year; specifically, gas waste witnessed an increase of 9.7% each year. Clearly, there is an excessive and growing dependence on primary energy resources. The amount of iron ore imports increased 2.61 times in 2010 compared to 2005. In order to achieve sustainable development in HISI, we recommend the following: improving technologies, strengthening material recycling, and promoting circular economy. © 2015 Elsevier B.V. All rights reserved.

Wang L.,Beijing University of Technology
Applied Mechanics and Materials | Year: 2014

Based on analysis of domestic and national literature, the related theory of enterprise knowledge management performance evaluation and methods of knowledge management performance evaluation has been summarized and compared. Combining with the characteristics of enterprises, the model and method of software enterprise knowledge management performance evaluation has been confirmed. Through surveying to related experts, index system of software enterprise knowledge management performance evaluation has been structured which applies in fuzzy evaluation method, it’s able to apply in software enterprise knowledge management performance evaluation. © (2014) Trans Tech Publications, Switzerland.

Lansberg J.-P.,University Paris - Sud | Shao H.-S.,Beijing University of Technology | Shao H.-S.,CERN
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2015

We demonstrate that the recent studies of J/ψ-pair production by CMS at the LHC and by D0 at the Tevatron reveal the presence of different production mechanisms in different kinematical regions. We find out that next-to-leading-order single parton scattering contributions at αs 5 dominate the yield at large transverse momenta of the pair. Our analysis further emphasises the importance of double parton scatterings - which are expected to dominate the yield at large J/ψ-rapidity differences - at large invariant masses of the pair in the CMS acceptance, and thereby solve a large discrepancy between the theory and the CMS data. In addition, we provide the first exact - gauge-invariant and infrared-safe - evaluation of a class of leading-PT (PT-4) next-to-next-to-leading-order contributions at αs 6, which can be relevant in the region of large values of PTmin=min(PT1, PT2). Finally, we derive simple relations for the feed-down fractions from the production of an excited charmonium state with a J/ψ in the case of the dominance of the double parton scatterings, which significantly deviate from those for single parton scatterings. Such relations can be used to discriminate these extreme scenarios, either DPS or SPS dominance. © 2015 The Authors.

Deng Z.,Beijing University of Technology
Harbin Gongcheng Daxue Xuebao/Journal of Harbin Engineering University | Year: 2016

In order to study the uniaxial compressive behavior of different types of fiber reinforced polymer (FRP) confined ultrahigh-performance concrete (UHPC), 27 FRP-confined UHPC specimens and 3 un-confined specimens were used for performing the uniaxial compressive tests. The stress-strain curves were obtained from the testes. The effects of FRP types and fiber sheets number on confinement effectiveness were analyzed. The test results show that the compressive strength of FRP-confined specimens mainly depends on the confinement ratios, but the ultimate strain not only depend on the confinement ratio, but also depend on the types of FRP. The compressive strength and ultimate strains increase with the confinement ratio. The Lam-Teng model represented the best fit for the stress-strain curves. Based on the test results, the new models for predicting the compressive strength and ultimate strain were proposed, and those models can more accurately predict the confinement responses of FRP-confined UHPC. © 2016, Editorial Board of Journal of Harbin Engineering. All right reserved.

Roberts C.D.,Argonne National Laboratory | Roberts C.D.,Beijing University of Technology | Roberts C.D.,Illinois Institute of Technology
Few-Body Systems | Year: 2012

In tackling QCD, a constructive feedback between theory and extant and forthcoming experiments is necessary in order to place constraints on the infrared behaviour of QCD's β-function, a key nonperturbative quantity in hadron physics. The Dyson-Schwinger equations provide a tool with which to work toward this goal. They connect confinement with dynamical chiral symmetry breaking, both with the observable properties of hadrons, and hence can plausibly provide a means of elucidating the material content of real-world QCD. This contribution illustrates these points via comments on: in-hadron condensates; dressed-quark anomalous chromo- and electro-magnetic moments; the spectra of mesons and baryons, and the critical role played by hadron-hadron interactions in producing these spectra. © 2011 Springer-Verlag (outside the USA).

Li A.,Xiamen University | Huang F.,Xiamen University | Xu R.-X.,Beijing University of Technology
Astroparticle Physics | Year: 2012

The maximum mass of a neutron star is generally determined by the equation of state of the star material. In this study, we take into account dark matter particles, assumed to behave like fermions with a free parameter to account for the interaction strength among the particles, as a possible constituent of neutron stars. We find dark matter inside the star would soften the equation of state more strongly than that of hyperons, and reduce largely the maximum mass of the star. However, the neutron star maximum mass is sensitive to the particle mass of dark matter, and a very high neutron star mass larger than 2 Mȯ could be achieved when the particle mass is small enough, being Mȯ the mass of the sun. Such kind of dark-matter-admixed neutron stars could explain the recent measurement of the Shapiro delay in the radio pulsar PSR J1614-2230, which yielded a neutron star mass of 1.97 ± 0.04 Mȯ that may be hardly reached when hyperons are considered only, as in the case of the microscopic Brueckner theory. Furthermore, in this particular case, we point out that the dark matter around a neutron star should also contribute to the mass measurement due to its pure gravitational effect. However, our numerically calculation illustrates that such contribution could be safely ignored because of the usual diluted dark matter environment assumed. We conclude that a very high mass measurement of about 2 Mȯ requires a really stiff equation of state in neutron stars, and find a strong upper limit (≤0.64 GeV) for the particle mass of non-self-annihilating dark matter based on the present model. © 2012 Elsevier B.V. All rights reserved.

Chen Q.B.,Beijing University of Technology
Acta Physica Polonica B, Proceedings Supplement | Year: 2015

The recent progresses of the collective Hamiltonian and its applications for chiral and wobbling modes are reviewed. In particular, the phenomenon of the multiple chiral doublet bands that are given by the collective Hamiltonian is introduced. In the investigation of the wobbling mode, the wobbling frequency as a function of the rotational frequency by the collective Hamiltonian in comparison with the harmonic frozen alignment approximation results for the longitudinal and transverse wobbling is discussed.

Li S.,Beijing University of Technology | Wang S.,China Security Co.
Knowledge-Based Systems | Year: 2014

Financial early warning (FEW) models aim to help companies recognize possible financial crises and reduce financial risks through generating FEW messages. The current FEW models are mainly constructed by a set of financial indicators and the predictive accuracy has only been verified by these financial indicators rather than non-financial indicators. The issue in such a situation is that these financial indicators can be controlled or manipulated by related senior managerial personnel of companies, and therefore, using only financial indicators to verify FEW models cannot ensure the reliability of predictive accuracy of the models. To handle this issue, this paper develops a new FEW logit model which has better predictive accuracy than existing ones. More importantly, we propose a new approach which verifies the predictive accuracy of the logit model by using non-financial efficiency indicators of data envelopment analysis. An empirical study on Chinese company datasets revealed that the accuracy rates of predictions of the proposed model, for in-sample and out-of-sample companies, are 97.1% and 94.1% respectively, higher than existing results. Using non-financial efficiency indicators, the verification rates for the prediction results of the logit model for in-sample and out-of-sample companies are 95.8% and 96.2%, respectively. The findings show that the proposed FEW logit model has improved the accuracy of prediction and stability; the approach which uses non-financial efficiency indicators to verify the results of FEW logit model has significantly ensured the reliability of the FEW models. © 2014 Elsevier B.V. All rights reserved.

Shao H.-S.,Beijing University of Technology | Zhang Y.-J.,Beihang University | Chao K.-T.,Peking University
Journal of High Energy Physics | Year: 2012

We present a new systematic method to evaluate one-loop tensor integrals in conventional ultraviolet cutoff regularization. By deriving a new recursive relation that describes the momentum translation variance of ultraviolet integrals, we implement this relation in the Passarino-Veltman reduction method. With this method, we recalculate the Higgs boson decay into two photons at one-loop level in the Standard Model. We reanalyze this process carefully and clarify some issues arisen recently in cutoff regularization. © SISSA 2012.

Shi Z.,Beihang University | Zhang S.,Beijing University of Technology
Acta Physica Polonica B, Proceedings Supplement | Year: 2015

The low-lying structures of the even-even Gd isotopes, including the partial dynamical symmetry candidates 156-162Gd, are investigated in the framework of five-dimensional collective Hamiltonian based on the covariant density functional theory with the density functional PC-PK1. The available experimental data are reproduced by the microscopic calculations. A shape evolution from the γ-soft 150Gd to the well-deformed prolate 162Gd is presented. The ground states of the partial dynamical symmetry candidates 156-162Gd are all well-deformed prolate at β 0:35.

Shao H.-S.,Beijing University of Technology | Zhang Y.-J.,Beihang University
Journal of High Energy Physics | Year: 2012

The complete set of Feynman rules for the rational part R of QCD corrections in the MSSM are calculated at the one-loop level, which can be very useful in the next-to-leading order calculations in supersymmetric models. Our results are expressed in the 't Hooft-Veltman regularization scheme and in the Four Dimensional Helicity scheme with non-anticommutating and anticommutating γ 5 strategies. © 2012 SISSA.

Wang K.,Beijing University of Technology | Levinson D.M.,CNRS Civil and geo-Environmental Engineering Laboratory
PLoS ONE | Year: 2016

Using travel diary data from 2000-2001 and 2010-2012 this research examines fundamental traffic relationships at the metropolitan level. The results of this paper can help to explain the causes of some traffic phenomena. Network average speed by time of day can be explained by trip length and cumulative number of vehicles on the road. A clockwise hysteresis loop is found in the Metropolitan Fundamental Diagram in the morning period and a reverse process happens in the afternoon. © 2016 Wang, Levinson. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Sun L.,Beijing University of Technology | Sun L.,Henan Normal University | Xu J.,Henan Normal University
Bio-Medical Materials and Engineering | Year: 2014

Feature selection is a key problem in tumor classification and related tasks. This paper presents a tumor classification approach with neighborhood rough set-based feature selection. First, some uncertainty measures such as neighborhood entropy, conditional neighborhood entropy, neighborhood mutual information and neighborhood conditional mutual information, are introduced to evaluate the relevance between genes and related decision in neighborhood rough set. Then some important properties and propositions of these measures are investigated, and the relationships among these measures are established as well. By using improved minimal-Redundancy-Maximal-Relevancy, combined with sequential forward greedy search strategy, a novel feature selection algorithm with low time complexity is proposed. Finally, several cancer classification tasks are demonstrated using the proposed approach. Experimental results show that the proposed algorithm is efficient and effective. © 2014 - IOS Press and the authors. All rights reserved.

Ling S.K.,Curtin University Australia | Wang S.,Curtin University Australia | Peng Y.,Beijing University of Technology
Journal of Hazardous Materials | Year: 2010

Dye degradation using advanced oxidation processes with Co2+/H2O2 and Co2+/peroxymonosulfate (PMS) systems has been investigated. Two types of dyes, basic blue 9 and acid red 183, were employed. Several parameters affecting dye degradation such as Co2+, PMS, H2O2, and dye concentrations were investigated. The optimal ratio of oxidant (PMS, H2O2)/Co2+ for the degradation of two dyes was determined. It is found that dye decomposition is much faster in Co2+/PMS system than in Co2+/H2O2. For Co2+/H2O2, an optimal ratio of H2O2 to Co2+ at 6 is required for the maximum decomposition of the dyes. For Co2+/PMS, higher concentrations of Co2+ and PMS will increase dye degradation rate with an optimal ratio of 3, achieving 95% decolourisation. For basic blue 9, a complete decolourisation can be achieved in 5min at 0.13mM Co2+, 0.40mM PMS and 7mg/l basic blue 9 while the complete degradation of acid red 183 will be achieved at 30min at 0.13mM Co2+, 0.40mM PMS and 160mg/l of acid red 183. The degradation of acid red 183 follows the second-order kinetics. © 2010 Elsevier B.V.

Jiang Q.,Beijing University of Chemical Technology | Xue R.,Beijing University of Technology | Jia M.,Beijing University of Chemical Technology
Applied Surface Science | Year: 2012

A novel layer-by-layer electrodeposition and heat-treatment approach was attempted to obtain Sn-Sb-Cu film anode for lithium ion batteries. The preparation of Sn-Sb-Cu anodes started with galvanostatic electrochemically depositing antimony and tin sequentially on the substrate of copper foil collector. Sn-Sb and Cu-Sb alloys were formed when heated. The SEM analysis showed that the crystalline grains become bigger and the surface of the Sn-Sb-Cu anode becomes more denser after annealing. The energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) analysis showed the antimony, tin and copper were alloyed to form SnSb and Cu 2Sb after heat treatment. The X-ray photoelectron spectroscopy (XPS) analysis showed the surface of the Sn-Sb-Cu electrode was covered by a thin oxide layer. Electrochemical measurements showed that the annealed Sn-Sb-Cu anode has high reversible capacity and good capacity retention. It exhibited a reversible capacity of about 962 mAh/g in the initial cycle, which still remained 715 mAh/g after 30 cycles. © 2011 Elsevier B.V. All rights reserved.

Meshgin P.,University of Colorado at Boulder | Xi Y.,University of Colorado at Boulder | Li Y.,Beijing University of Technology
Construction and Building Materials | Year: 2012

Phase change materials (PCMs) and rubber particles from recycled tires were used in portland cement mortar with a potential application as insulation mortar. Series of tests were designed and conducted including compressive strength, flexural strength, thermal conductivity, drying shrinkage, and bond strength tests at 7 days and 28 days of age. Different types of additives were also used in the mix designs. The experimental results showed that mechanical properties of rubberized-mortar can be improved by adjusting the size of rubber particles and the amount of additives. With the same volume fraction of PCM and rubbers, the mechanical properties of PCM-modified mortar are either the same or better than that of rubberized-mortar. In terms of thermal properties, the rubber particles can reduce thermal conductivity of the mortar significantly, while the PCM can improve heat capacity of the mortar. © 2011 Elsevier Ltd. All rights reserved.

Liu X.-H.,Beijing University of Technology
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

We investigate the processes e+e- annihilating to J/ψππ, ψ′ππ and hcππ. The coupled-channel effects induced by the couplings between the widely accepted D-wave charmonium ψ(4160) and D1D, D1D∗ and D2D∗ charmed meson pairs in the S-wave state with couplings given by heavy quark spin symmetry are analyzed. The line shapes show the presence of cusps that result from the singularities of the rescattering loops, which could be helpful in understanding the nature of Y(4260), Y(4360), Zc(3900)/Zc(3885) and Zc(4020)/Zc(4025). © 2014 American Physical Society.

Teng H.,Beijing University of Technology
Journal of Instrumentation | Year: 2014

The Resistive Plate Chamber (RPC) detector system in LHC-CMS experiment is designed for the trigger purpose. The endcap RPC system has been successfully operated since the commissioning period (2008) to the end of RUN1 (2013). We have developed an analysis tool for endcap RPC performance and validated the efficiency calculation algorithm, focusing on the first endcap station which was assembled and tested by the Peking University group. We cross checked the results obtained with those extracted with alternative methods and we found good agreement in terms of performance parameters [1]. The results showed that the CMS-RPC endcap system fulfilled the performance expected in the Technical Design Report [2]. © CERN 2014.

Ma S.,Xian Jiaotong University | Xing J.,Xian Jiaotong University | Fu H.,Beijing University of Technology | Gao Y.,Xian Jiaotong University | Zhang J.,Xian Jiaotong University
Acta Materialia | Year: 2012

The microstructure and crystallography of eutectic borides and secondary precipitations in 18 wt.% Cr-4 wt.% Ni-1 wt.% Mo-3.5 wt.% B-0.27 wt.% C steel have been investigated extensively. The results show that the as-cast microstructure of Cr-Ni-Mo-containing Fe-B steel is composed of a dendritic martensite with large interdendritic eutectic borides. Transmission electron microscopy (TEM) results confirm that the borides are indexed to Cr- and Mo-rich M 2B-type borides with the chemical formulas of Fe (1.35-1.36)Cr (0.92-1.05)B 0.96 and Fe 0.73Cr 0.45Mo 0.78B, respectively. The cluster-like boride possesses a possible orientation relationship between body-centred orthorhombic Cr-rich M 2B and martensite with 〈11̄0〉 M2B//〈1 1 0〉 α growth direction. After destabilization, M 23(C, B) 6 secondary borocarbide with a specific orientation relationship precipitates first and thereafter coarsens following the appearance of M 7(C, B) 3 precipitation with the increasing destabilization temperature at the same soaking time, thus leading to a large decrease of Cr content in the martensite. However, no M 6(C, B) secondary borocarbide is found in as-destabilized Fe-B steel. Destabilization treatment has no effect on the morphology of eutectic borides. The secondary borocarbides have the stoichiometry of (Fe 18.26Cr 4.74)(B, C) 6 and (Fe 3.86Cr 3.14)(B, C) 3 respectively. The high-resolution TEM results indicate that the nucleation and precipitation of M 23(C, B) 6 occur at the grain/subgrain boundaries as well as partial within martensite, and a subsequent transformation from M 23(C, B) 6 to M 7(C, B) 3 takes place in situ, which is probably owing to the crystalline defects of dislocations and stacking faults in the structures caused by lattice distortion. © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Tang X.,Beijing University of Technology | Ren N.,Harbin Institute of Technology | Xu J.,Inner Mongolia University
International Journal of Hydrogen Energy | Year: 2013

Corn cob is a promising hydrogen fermentation substrate, not only because of its abundant and low cost, but also because of its high cellulose and hemicellulose content. However, little information is available on the use of corn cob as a feedstock for hydrogen production. In this study, corn cob was hydrolyzed by cellulase after acid steam-explosion, alkali soaking, or steam-explosion pretreatment. The liquid products of pretreatment and the enzymatic hydrolysates were then used as carbon sources for hydrogen production by Clostridium hydrogeniproducens HR-1. Pretreatment followed by enzymatic hydrolysis yielded 720, 670, and 530 mg reducing sugars/g corn cob, and the hydrogen yield from corn cob reached 119, 100, and 83 ml H2/g corn cob, which is 55.9%, 46.7%, and 38.8% of the theoretical hydrogen yield from corn cob using C. hydrogeniproducens HR-1, respectively. Copyright © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Sun J.,CAS Institute of Process Engineering | Wang J.,CAS Institute of Process Engineering | Cheng W.,CAS Institute of Process Engineering | Zhang J.,CAS Institute of Process Engineering | And 3 more authors.
Green Chemistry | Year: 2012

Development of efficient, cheap and recyclable catalysts for a reaction under green reaction conditions is still a very attractive topic. In this work, the cycloaddition reactions of CO 2 with various epoxides to form five-membered cyclic carbonates catalyzed by chitosan functionalized 1-ethyl-3-methyl imidazolium halides (CS-EMImX, X = Cl, Br) without additional solvent and metal co-catalyst were achieved in high yield and selectivity. The catalyst could be easily recovered and reused five times with high catalytic activity and selectivity. Besides, a possible catalytic cycle for the hydrogen bond assisted ring-opening of epoxide and activation of CO 2 induced by the nucleophilic tertiary nitrogen of the chitosan was also proposed. The process represents a simple, ecologically safe and cost-effective route to synthesize cyclic carbonates with high product yield, as well as easy catalyst recycling. © The Royal Society of Chemistry 2012.

Zhong N.,Maebashi Institute of Technology | Zhong N.,Beijing University of Technology | Li Y.,Queensland University of Technology | Wu S.-T.,Asia University, Taiwan
IEEE Transactions on Knowledge and Data Engineering | Year: 2012

Many data mining techniques have been proposed for mining useful patterns in text documents. However, how to effectively use and update discovered patterns is still an open research issue, especially in the domain of text mining. Since most existing text mining methods adopted term-based approaches, they all suffer from the problems of polysemy and synonymy. Over the years, people have often held the hypothesis that pattern (or phrase)-based approaches should perform better than the term-based ones, but many experiments do not support this hypothesis. This paper presents an innovative and effective pattern discovery technique which includes the processes of pattern deploying and pattern evolving, to improve the effectiveness of using and updating discovered patterns for finding relevant and interesting information. Substantial experiments on RCV1 data collection and TREC topics demonstrate that the proposed solution achieves encouraging performance. © 2011 IEEE.

Wang Y.,Tongji University | Geng J.,Tongji University | Peng Y.,Beijing University of Technology | Wang C.,Tongji University | And 2 more authors.
Bioresource Technology | Year: 2012

The endogenous processes in anaerobic end and aerobic end sludge responsible for biological denitrifying phosphorus removal were compared during a 7-d starvation under anaerobic conditions. The results showed that polyphosphate and glycogen were utilized simultaneously to generate maintenance energy for both the anaerobic and aerobic end sludge. During the 7-d starvation, the decay rate of denitrifying-phosphorus-accumulating-organisms (DPAOs) was higher for the aerobic end sludge than for the anaerobic end sludge. More energy was required for maintenance in the aerobic end sludge than for the anaerobic end sludge, with the greater amount of phosphorus release and glycogen degradation occurring in the aerobic end sludge. Moreover, different metabolic pathways for the endogenous processes were observed for the anaerobic and aerobic end sludge. After the 7-d starvation, the activity of DPAOs decreased more for the aerobic end sludge than that for the anaerobic end sludge. © 2011 Elsevier Ltd.

Sun T.,Peking University | Wang J.,Peking University | Kang W.,Beijing University of Technology
Nanoscale | Year: 2013

Interfaces usually impede heat transfer in heterogeneous structures. Recent experiments show that van der Waals (vdW) interactions can significantly enhance thermal conductivity parallel to the interface of a bundle of nanoribbons compared to a single layer of freestanding nanoribbon. In this paper, by simulating heat transfer in nanostructures based on a model of nonlinear one-dimensional lattices interacting via van der Waals interactions, we show that the vdW interface interaction can adjust the thermal conductivity parallel to the interface. The efficiency of the adjustment depends on the intensity of interactions and temperature. The nonlinear dependence of the conductivity on the intensity of interactions agrees well with experimental results for carbon nanotube bundles, multi-walled carbon nanotubes, multi-layer graphene, and nanoribbons. © 2013 The Royal Society of Chemistry.

Cao J.,Henan Normal University | Hikasa K.-I.,Tohoku University | Wang W.,Beijing University of Technology | Yang J.M.,CAS Institute of Theoretical Physics | Yu L.-X.,CAS Institute of Theoretical Physics
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2010

Assuming the lightest neutralino solely composes the cosmic dark matter, we examine the constraints of the CDMS-II and XENON100 dark matter direct searches on the parameter space of the minimal supersymmetric standard model (MSSM) Higgs sector. We find that the current CDMS-II/XENON100 limits can exclude some of the parameter space which survive the constraints from the dark matter relic density and various collider experiments. We also find that in the currently allowed parameter space, the charged Higgs boson is hardly accessible at the LHC for an integrated luminosity of 30fb-1, while the neutral non-SM (standard model) Higgs bosons (H,A) may be accessible in some allowed region characterized by a large μ. The future XENON100 (6000 kg-days exposure) will significantly tighten the parameter space in case of nonobservation of dark matter. © 2010 The American Physical Society.

Berger E.L.,Argonne National Laboratory | Cao Q.-H.,Argonne National Laboratory | Cao Q.-H.,University of Chicago | Chen C.-R.,University of Tokyo | And 4 more authors.
Physical Review Letters | Year: 2010

We explore the potential for discovery of an exotic color sextet scalar in same-sign top quark pair production in early running at the LHC. We present the first phenomenological analysis at colliders of color sextet scalars with full top quark spin correlations included. We demonstrate that one can measure the scalar mass, the top quark polarization, and confirm the scalar resonance with 1fb-1 of integrated luminosity. The top quark polarization can distinguish gauge triplet and singlet scalars. © 2010 The American Physical Society.

Yang G.-H.,Northeastern University China | Wang H.,Beijing University of Technology | Xie L.,Nanyang Technological University
International Journal of Robust and Nonlinear Control | Year: 2010

The paper studies the fault detection problem for output feedback control systems with bounded disturbances and nonzero constant reference inputs. A steady-state-based approach is proposed which can be used to detect small actuator stuck faults including actuator outage (the stuck value is zero). These small stuck faults, especially the outage faults, cannot be detected effectively using the existing techniques. A dynamic output feedback controller and a weighting matrix are designed simultaneously. The dynamic output feedback controller stabilizes the closed-loop system for both fault-free and faulty cases and attenuates the effects of disturbances. By manipulating the steady-state values of system states with the detection weighting matrix, a residual is then generated, through which actuator stuck faults including actuator outages can be detected effectively. Simulation results are included to demonstrate our design procedure. Copyright © 2009 John Wiley & Sons, Ltd.

Chen H.-X.,Beijing University of Technology | Dmitrasinovic V.,University of Belgrade | Hosaka A.,Osaka University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2011

Three-quark nucleon interpolating fields in QCD have well-defined SU L(3)×SUR(3) and UA(1) chiral transformation properties, viz. [(6,3)×(3,6)], [(3,3̄) ×(3̄,3)], [(8,1)×(1,8)], and their mirror images; see. It has been shown (phenomenologically) in that mixing of the [(6,3)×(3,6)] chiral multiplet with one ordinary (naive) and one mirror field belonging to the [(3,3̄)×(3̄,3)], [(8,1)×(1,8)] multiplets can be used to fit the values of the isovector (gA(3)) and the flavor-singlet (isoscalar) axial coupling (gA(0)) of the nucleon and then predict the axial F and D coefficients, or vice versa, in reasonable agreement with experiment. In an attempt to derive such mixing from an effective Lagrangian, we construct all SUL(3)×SUR(3) chirally invariant nonderivative one-meson-baryon interactions and then calculate the mixing angles in terms of baryons' masses. It turns out that there are (strong) selection rules: for example, there is only one nonderivative chirally symmetric interaction between J=12 fields belonging to the [(6,3)×(3,6)] and the [(3,3̄) ×(3̄,3)] chiral multiplets, that is also UA(1) symmetric. We also study the chiral interactions of the [(3,3̄)×(3̄,3)] and [(8,1)×(1,8)] nucleon fields. Again, there are selection rules that allow only one off-diagonal nonderivative chiral SUL(3)×SU R(3) interaction of this type, that also explicitly breaks the U A(1) symmetry. We use this interaction to calculate the corresponding mixing angles in terms of baryon masses and fit two lowest-lying observed nucleon (resonance) masses, thus predicting the third (J=12, I=32) Δ resonance, as well as one or two flavor-singlet Λ hyperon(s), depending on the type of mixing. The effective chiral Lagrangians derived here may be applied to high density matter calculations. © 2011 The American Physical Society.

Berger E.L.,Argonne National Laboratory | Cao Q.-H.,Argonne National Laboratory | Cao Q.-H.,University of Chicago | Chen C.-R.,University of Tokyo | Zhang H.,Beijing University of Technology
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2011

New heavy gauge bosons exist in many models of new physics beyond the standard model of particle physics. Discovery of these W′ and Z′ resonances and the establishment of their spins, couplings, and other quantum numbers would shed light on the gauge structure of the new physics. The measurement of the polarization of the SM fermions from the gauge boson decays would decipher the handedness of the coupling of the new states, an important relic of the primordial new physics symmetry. Since the top quark decays promptly, its decay preserves spin information. We show how decays of new gauge bosons into third generation fermions (W′→tb, Z′→tt̄) can be used to determine the handedness of the couplings of the new states and to discriminate among various new physics models. © 2011 American Physical Society.

Chen H.-X.,Beijing University of Technology | Dmitrasinovic V.,Vinca Institute of Nuclear Sciences | Hosaka A.,Osaka University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2010

We use the conventional F and D octet and decimet generator matrices to reformulate chiral properties of local (nonderivative) and one-derivative nonlocal fields of baryons consisting of three quarks with flavor SU(3) symmetry that were expressed in SU(3) tensor form by Chen et al.. We show explicitly the chiral transformations of the [(6,3)(3,6)] chiral multiplet in the "SU(3) particle basis," for the first time to our knowledge, as well as those of the (3,3̄)(3̄,3), (8,1)(1,8) multiplets, which have been recorded before by Bardeen and Lee and Lee. We derive the vector and axial-vector Noether currents, and show explicitly that their zeroth (chargelike) components close the SUL(3)×SUR(3) chiral algebra. We use these results to study the effects of mixing of (three-quark) chiral multiplets on the axial current matrix elements of hyperons and nucleons. We show, in particular, that there is a strong correlation, indeed a definite relation between the flavor-singlet (i.e. the zeroth), the isovector (the third), and the eighth flavor component of the axial current, which is in decent agreement with the measured ones. © 2010 The American Physical Society.

Wang Q.,Beijing University of Technology | Wang Q.,Virginia Commonwealth University | Jena P.,Virginia Commonwealth University
Journal of Physical Chemistry Letters | Year: 2012

Hydrogen storage properties of Li-coated C 60 fullerene have been studied using density functional theory within the local density as well as generalized gradient approximation. Hydrogen atoms are found to bind to Li 6C 60 in two distinct forms, with the first set attaching to C atoms, not linked to Li, in atomic form. Once all such C atoms are saturated with hydrogen, the second set of hydrogen atoms bind quasi-molecularly to the Li atoms, five of which remain in the exohedral and the sixth in the endohedral position. The corresponding hydrogen gravimetric density in Li 6C 60H 40 is 5 wt %. Desorption of hydrogen takes place in succession, the ones bound quasi-molecularly desorbing at a temperature lower than the ones bound atomically. The results are compared with the recent experiment on hydrogen adsorption in Li 6C 60. © 2012 American Chemical Society.

Chen H.,Nanchang University | Zhao Y.,Beijing University of Technology
International Journal of Systems Science | Year: 2014

This paper is mainly concerned with the problem for the robustly exponential stability in mean square moment of uncertain neutral stochastic neural networks with interval time-varying delay. With an appropriate augmented Lyapunov-Krasovskii functional (LKF) formulated, the convex combination method is utilised to estimate the derivative of the LKF. Some new delay-dependent exponential stability criteria for such systems are obtained in terms of linear matrix inequalities, which involve fewer matrix variables and have less conservatism. Finally, two illustrative numerical examples are given to show the effectiveness of our obtained results. © 2014 © 2014 Taylor & Francis.

Yu C.,Peking University | Xiao Z.,Peking University | Xiao Z.,Beijing University of Technology
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2013

A refined two-term helical subgrid-scale (SGS) stress model with respect to that suggested by Li is designed for large-eddy simulation (LES) of helical turbulence. The model coefficients in the new model are verified a priori to be scale invariant in inertial range, which proves that our model is local in scale. A dynamic method based on minimizing the residual resolved energy and helicity dissipations is suggested to simultaneously evaluate the coefficients of the mixed SGS model as the simulation progresses. In addition, an SGS helicity dissipation (or helicity flux) constraint condition is proposed to optimize the mixed two-term model. Both techniques are first tested and validated in the LES of forced isotropic helical turbulence. The statistical results are analyzed and compared with those obtained from the dynamic Smagorinsky model, the traditional dynamic mixed model, and the direct numerical simulation. It is found that the introduction of this dynamic procedure can help overcome the drawback of the traditional dynamic method which can not capture the negative helicity fluxes and SGS dissipations. The probability density functions of the energy flux and the conditioned helicity flux and SGS stress demonstrate that the helicity flux constrained dynamic SGS model can effectively predict the real SGS helical effects on the resolved scales, such as backscatters of energy and helicity, accurate helicity dissipation rate, and so on. The present models are also applied to the simulation of freely decaying isotropic turbulence with no apparent improvement observed in comparison with the traditional SGS models. The underlying reasons for these issues are addressed in detail. © 2013 American Physical Society.

Tiejun D.,Beijing University of Technology
Resources, Conservation and Recycling | Year: 2011

An iron resource efficiency is proposed to define a measure of the natural iron resources saved in the steel manufacturing process. A simplified iron flow diagram is presented for the steel manufacturing process. The influences of various deviations in iron flow from the simplified iron flow diagram on iron resource efficiency are analyzed. The relationships between iron resource efficiency of unit processes and the final product are also discussed. As an example, data from a steel plant are used to analyze the influence of iron flow on its iron resource efficiency of finial product in the steel manufacturing process, the influence of iron resource efficiency of unit process on iron resource efficiency of the final product, and give some measures to improve the iron resource efficiency of the steel manufacturing process. © 2011 Elsevier B.V. All rights reserved.

Chow C.L.,University of Cambridg | Li J.,Beijing University of Technology
Journal of Civil Engineering and Management | Year: 2010

Static smoke exhaust systems with natural vents are starting to be installed in big shopping complexes, warehouses and cargo terminals in the Far East. These systems are used for natural ventilation as well as for letting out smoke. This paper responds to concerns over the performance of static smoke exhaust systems, which remain less popular than dynamic smoke exhaust systems with mechanical fans. We propose a modification of a simple flow model found in the literature, adapting this to study smoke layer interface height with natural vents opened. We compare and justify our results, as generated by both Computational Fluid Dynamics and zone models, alongside reports of historical field tests. The model of smoke exhaust is applied in an illustrative example of a large hall, leading to the suggestion that a flow model could be used for designing natural vents. As the key driving force in removing smoke through natural vents is smoke's own buoyancy, the system might only be effective for bigger fires.

Chuang Z.,North China University of Water Conservancy and Electric Power | Liu Y.,Beijing University of Technology
International Journal of Wavelets, Multiresolution and Information Processing | Year: 2011

This paper deals with the construction of spline wavelets on the interval [0, 1], which have zero boundary values and vanishing moments. One begins with some primal scaling functions and their biorthogonal duals. Then desired biorthogonal wavelets are given by the method of Dahmen, Kunoth and Urban. Since the structure of those wavelets looks complicated, one tries to construct those types of wavelets only in primal side finally, without using any dual informations. Some numerical experiments show good effects, although the uniform stability remains to be proved theoretically. © 2011 World Scientific Publishing Company.

Xue L.,Beijing University of Technology
Computational Statistics and Data Analysis | Year: 2013

The estimation and empirical likelihood for single-index models with missing covariates are studied. A generalized estimating equations estimator for index coefficients with missing covariates is constructed, and its asymptotic distribution is obtained. The local linear estimator for link function achieves optimal convergence rate. By using the bias-correction and inverse selection probability weighted methods, a class of empirical likelihood ratios is proposed such that each of our class of ratios is asymptotically chi-squared. A simulation study indicates that the proposed methods are comparable in terms of coverage probabilities and average lengths (areas) of confidence intervals (regions). An example of a real data set is illustrated. © 2013 Elsevier B.V.