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Dynamical Algebraic Approach to the Modified Jaynes-Cummings Model

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Chinese Physics Letters 2001年第1期18卷 51-53页

作者： xu Jing-bo ZOU xu-bo Zhejiang Institute of Modern Physics and Department of Physics Zhejiang UniversityHangzhou 310027

The modified Jaynes-Cummings model of a single two-level atom placed in the common domain of two cavities or interacting with two quantized modes is studied by a dynamical algebraic *** the help of an SU(2)algebraic structure,we then obtain the eigenvalues,eigenstates,time evolution operator and atomic inversion operator for the *** proceed to investigate the modified Jaynes-Cummings model governed by the Milburn equation and present the exact solution of the Milburn equation.

关键词： equation. method. algebraic

Mechanically Strong Heterogeneous Catalysts via Immobilization of Powderous Catalysts to Porous Plastic Tablets

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Chinese Journal of Chemistry 2021年第10期39卷 2673-2678页

作者： Tingting Li bo xu Key Laboratory of Science and Technology of Eco-Textiles Ministry of EducationCollege of ChemistryChemical Engineering and BiotechnologyDonghua UniversityShanghai201620 China

Main observation and conclusion We describe a practical and general protocol for immobilization of heterogeneous catalysts to mechanically robust porous ultra-high molecular weight polyethylene tablets using inter-facial Lifshitz-van der Waals *** types of powderous catalysts,including Cu,Pd/C,Pd/Al2O3,Pt/C,and Rh/C have been immobilized *** immobilized catalysts are mechanistically robust towards stirring in solutions,and they worked well in diverse synthetic *** immobilized catalyst tablets are easy to handle and ***,the metal leaching of immobilized catalysts was reduced significantly.

关键词： Heterogeneous catalysts Solution-phase chemistry Immobilization Porous plastic tablets Metal leaching Main observation

Variable structure guidance law for attacking surface maneuver targets

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Journal of Systems Engineering and Electronics 2008年第2期19卷 337-341页

作者： Han Yanhua xu bo Coll. of Astronautics Nanjing Univ. of Aeronautics and Astronautics Nanjing 210016 P. R. China

The characteristics of surface maneuver targets are analyzed and a 3-D relative motion model for missiles and targets is established. A variable structure guidance law is designed considering the characteristics of targets. In the guidance law, the distance between missiles and targets as well as the missile-target relative velocity are all substituted by estimation values. The estimation errors, the target＇s velocity, and the maneuver acceleration are all treated as bounded disturbance. The guidance law proposed can be implemented conveniently in engineering with little target information. The performance of the guidance system is analyzed theoretically and the numerical simulation result shows the effectiveness of the guidance law.

关键词： air-to-surface missile guidance law variable structure control surface maneuver target.

Novel pseudo-divergence of Gaussian mixture models based speaker clustering method

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仪器仪表学报 2006年第z1期27卷 712-714,732页

作者： Wang bo xu Yiqiong Information Engineering University Zhengzhou 450002 China

Serial structure is applied to speaker recognition to reduce the algorithm delay and computational *** speech is first classified into speaker class,and then searches the most likely one inside the *** between Gaussian Mixture Models(GMMs) is widely applied in speaker *** paper proposes a novel mean of pseudo-divergence,the ratio of Inter-Model dispersion to Intra-Model dispersion,to present the difference between GMMs,to perform speaker ***,mean and variance,GMM’s components,are involved in the *** indicate that the measurement can well present the difference of GMMs and has improved performance of speaker clustering.

关键词： Serial structure Speaker recognition Pseudo-divergence GMMs

Numerical Study on Flow Heat Transfer Characteristics of Horizontal Tube Falling-Film Evaporator

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Journal of Thermal Science 2021年第4期30卷 1302-1317页

作者： xu bo JIANG Chun CHEN Zhenqian School of Energy and Environment Southeast UniversityNanjing 210096China Jiangsu Provincial Key Laboratory of Solar Energy Science and Technology School of Energy and EnvironmentSoutheast UniversityNanjing 210096China Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education School of Energy and EnvironmentSoutheast UniversityNanjing 210096China

As an efficient and energy-saving heat exchange technology, horizontal tube falling film evaporation has a great application prospect in refrigeration and air conditioning. The three-dimensional models of falling film flow evaporation outside horizontal single tube and inside evaporator were established, and the accuracy of flow and heat transfer simulation process was verified by comparison. For horizontal single tube, the results showed that total heat transfer coefficient was low and increased with larger spray density and evaporation temperature. The thickness of liquid film outside tube decreased gradually with the increase of tube diameter, and the total heat transfer coefficient of small tube diameter was significantly greater than that of the large tube diameter. The total heat transfer coefficient presented an increasing trend with larger liquid distribution height and density. In addition, the fluctuation of tube axial liquid film thickness distribution decreased with larger liquid distribution density. For evaporator, the results indicated that part of liquid refrigerant was carried into the vapor outlet. The temperature of tube wall and fluid presented a gradually rising trend in vertical downward direction, while tube wall temperature within the same horizontal and transverse row had little difference. The high-temperature zone on the outer wall of heat exchange tube moved towards the inlet and gradually decreased, and the outlet temperature of water in the tube also gradually decreased with the increase of refrigerant spray density. The local heat transfer coefficient of heat exchanger tube in the vertical direction presented a downward trend which was more obvious with the smaller spray density and it was obviously higher located in the middle of upper tube row and both sides of lower tube row for horizontal tube rows.

关键词： horizontal single tube evaporator falling film numerical simulation heat transfer

Effect of Graphite Layers on the Conformation and Thermal Conductivity of n-octadecane:A Molecular Dynamics Study

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Journal of Thermal Science 2021年第5期30卷 1789-1802页

作者： ZHANG Tiantian xu bo CHEN Zhenqian School of Energy and Environment Southeast UniversityNanjing 210096China Jiangsu Provincial Key Laboratory of Solar Energy Science and Technology School of Energy and EnvironmentSoutheast UniversityNanjing 210096China Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education School of Energy and EnvironmentSoutheast UniversityNanjing 210096China

To understand the thermal conductivity improvement of the paraffin and graphite composite PCMs in micro-scale,the conformation characteristics of molecules with rising temperature was studied by molecular dynamics(MD)*** then the structure and dynamics characteristics of the paraffin PCM,including the structural evolution,the self-diffusion coefficient,phase change properties and thermal conductivity,were *** results indicate that the distribution of the n-octadecane molecules is more regular in the region near the graphite layers,although the temperature is higher than the phase transition point,which means that the graphite layer has a significant absorption influence on the conformation of alkane ***,the self-diffusion coefficient of n-octadecane molecules increases with the increasing of temperature,which shows great agreement with the ***,the self-diffusion coefficient of n-octadecane molecules staying far away from the graphite layers is larger than that of the molecules in the region near the graphite *** addition,the radial distribution function(RDF)was used to analyze the molecular interaction of the system at different *** sudden increase of R(ratio of the first peak value to the first valley value of the RDF)within the temperature range from 293 K to 313 K corresponds to the phase transition point,indicating that the solid-liquid phase transition occurs at the temperature ***,the results indicate that the thermal conductivity of amorphous n-octadecane is about 2.5 times lower than that of the crystal n-octadecane with perfect *** investigation provides theoretical guidance for the study of the micro-mechanism of n-octadecane doped with graphite composite phase change materials.

关键词： phase change materials self-diffusion coefficient graphite layers thermal conductivity molecular dynamics conformation

Toward tunable shape memory effect of NiTi alloy by grain size engineering:A phase field study

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Journal of Materials Science & Technology 2024年第1期168卷 276-289页

作者： bo xu Chong Wang Qingyuan Wang Failure Mechanics and Engineering Disaster Prevention Key Laboratory of Sichuan ProvinceSichuan UniversityChengdu 610065China Department of Mechanical Science and Engineering College of Architecture and EnvironmentSichuan UniversityChengdu 610065China Key Laboratory of Deep Underground Science and Engineering (Sichuan University)Ministry of EducationChengdu 610065China

The inelastic deformations of shape memory alloys(SMAs)always show poor controllability due to the avalanche-like martensite transformation,and the effective control for the deformation of precision de-vices has been not yet *** this work,the phase field method was used to investigate the shape memory effects(SMEs)of NiTi SMAs undergoing grain size(GS)engineering,to obtain tunable one-way and stress-assisted two-way SMEs(OWSME and SATWSME).The OWSME and SATWSME of the systems with various gradient-nanograin structures and bimodal grain structure,as well as that with geometric gradients were *** simulated results indicate that due to the GS dependences of martensite transformation and reorientation,the occurrence and expansion of martensite reorientation,martensite transformation and its reverse can be efficaciously controlled via the GS *** combining the GS engineering and geometric gradient design,since the effects of GS and stress gradient can be su-perimposed or competing,and the responses of martensite reorientation,martensite transformation and its reverse to this are different,the OWSME and SATWSME of the geometrically graded systems with various nanograin structures can exhibit different improvements in *** short,the reorienta-tion hardening modulus during OWSME is increased and the transformation temperature window during SATWSME is widened by GS engineering,indicating the improved controllability of *** optimal GS engineering schemes revealed in this work provide the basic reference and guidance for designing tun-able SMEs and producing NiTi-based driving devices catering to desired functional performance in various engineering fields.

关键词： Phase field NiTi Shape memory effect Grain size engineering Geometric gradient

Improving multi-layer spiking neural networks by incorporating brain-inspired rules

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Science China(Information Sciences) 2017年第5期60卷 226-236页

作者： Yi ZENG Tielin ZHANG bo xu Institute of Automation Chinese Academy of Sciences Center for Excellence in Brain Science and Intelligence Technology Chinese Academy of Sciences

This paper introduces seven brain-inspired rules that are deeply rooted in the understanding of the brain to improve multi-layer spiking neural networks(SNNs). The dynamics of neurons, synapses, and plasticity models are considered to be major characteristics of information processing in brain neural ***, incorporating these models and rules to traditional SNNs is expected to improve their efficiency. The proposed SNN model can mainly be divided into three parts: the spike generation layer, the hidden layers, and the output layer. In the spike generation layer, non-temporary signals such as static images are converted into spikes by both local and global feature-converting methods. In the hidden layers, the rules of dynamic neurons,synapses, the proportion of different kinds of neurons, and various spike timing dependent plasticity(STDP)models are incorporated. In the output layer, the function of classification for excitatory neurons and winner take all(WTA) for inhibitory neurons are realized. MNIST dataset is used to validate the classification accuracy of the proposed neural network model. Experimental results show that higher accuracy will be achieved when more brain-inspired rules(with careful selection) are integrated into the learning procedure.

关键词： brain-inspired rules spiking neural network plasticity classification task

Dry modification of electrode materials by roller vibration milling at room temperature

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Particuology 2008年第5期6卷 383-388页

作者： Shengjuan Li Shulin Wang bo xu Department of Power Engineering University of Shanghai for Science and Technology 516 Jungong Road Shanghai 200093 China

For the first time dry roller vibration milling at room temperature was used to prepare active carbon （AC） nano-particles and to modify MnO2 powder as electrode materials. In 30 min AC was milled to a mean particle size of 30-50 nm with increased crystallinity and higher specific surface area, predominantly mesoporous and with improved pore diameter distribution. Then, AC nano-particles were incorporated with MnO2 or bismuth-doped MnO2 nano-particles synthesized by sol-gel methods to prepare nano-composite electrode materials for studying their electrochemical performance. The AC nano-particles combined with 10 wt.% bismuth-doped MnO2 nano-particles were found to possess excellent electrochemical property with specific capacitance up to 308 F/g and without obvious attenuation with increasing current. Our method seems to ooen a new way to imorove AC based electrode materials used for clean energy such as suner capacitors.

关键词： Active carbon Roller vibration milling Electrode materials Nano-materials Super-capacitors