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International Journal of Mining Science and Technology 2017年第5期27卷 819-823页

作者： zha Wenhua Shi Hao Liu San Kang Changhao Key Laboratory of Safe and Effective Coal Mining School of Mining and Safety EngineeringAnhui University of Science&TechnologyMinistry of EducationHuainan 232001China

gob-side entry driving can increase coal recovery ratio, and it is implied in many coal mines. Based on geological condition of 10416 working face tailentry in Yangliu Coal Mine, the surrounding rock deformation characteristics of gob-side entry driving with narrow coal pillar is analysed, reasonable size of coal pillar and reasonable roadway excavation time after mining are achieved. Surrounding rock control technology and effective roadway side sealing technology are proposed and are taken into field practice. The results showed that a safer and more efficient mining of working face can be achieved. In addition, results of this paper also have important theoretical significance and valuable reference for surrounding rock control technology of gob-side entry driving with narrow coal pillar under special geological condition.

关键词： Narrow coal pillar gob-side entry driving Surrounding rock control Roadway side sealing technology

Structural Stability and Half Metallic Features of Zn_(0.5)Cr_(0.5)S under Pressure

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Journal of Materials Science & Technology 2014年第3期30卷 234-238页

作者： Yuhong Huang Wanqi Jie Yan Zhou gangqiang zha State Key Laboratory of Solidification Processing School of Materials Science and Engineering Northwestern Polytechnical University

Spin-polarized first-principle was performed to study the structural stability and the electronic states of Cr doped ZnS with the Cr component of 50% in zincblende （ZB）, wurtzite （W） and rocksalt （RS） structures under pressure. The results show that the zincblende and wurtzite structures become unstable under low pressures of about 4.68 and 9.61 gPa, respectively, but the rocksalt structure can be maintained up to an extremely high pressure of about 32.92 gPa. Both zincblende and wurtzite ***.5S display half metallic features under pressure, while rocksalt *** exhibits metallic feature. The half metallic features can be ascribed to the stronger interactions between S-3p and Cr-3d states and the metallic feature is due to the higher crystal symmetry of rocksalt Zn0.5Cr0.5S. These results can provide helpful guidance for Cr doped ZnS to be used in spintronic devices.

关键词： Structural stability Half metallic features Electronic properties Zn0.5Cr0.5S Pressure

Particle breakage evolution of coral sand using triaxial compression tests

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Journal of Rock Mechanics and geotechnical Engineering 2021年第2期13卷 321-334页

作者： gang Wang zhaonan Wang Qinguo Ye Jingjing zha Key Laboratory of New Technology for Construction of Cities in Mountain Area Chongqing UniversityChongqing400045China School of Civil Engineering Chongqing UniversityChongqing400045China National Joint Engineering Research Center for geohazards Prevention in the Reservoir Areas Chongqing400045China

Particle breakage continuously changes the grading of granular materials and has a significant effect on their mechanical *** the evolution pattern of particle breakage is valuable for development and validation of constitutive models for crushable materials.A series of parallel triaxial compression tests along the same loading paths but stopped at different axial strains were conducted on two coral sands with different particle sizes under drained and undrained *** tested specimens were carefully sieved to investigate the intermediate accumulation of particle breakage during the loading *** test results showed that under both drained and undrained conditions,particle breakage increases continuously with increasing axial strain but exhibits different accumulating patterns,and higher confining pressures lead to greater particle *** on the test results,the correlations between particle breakage and the stress state as well as the input energy were *** results demonstrated that either the stress state or input energy alone is inadequate for describing the intermediate process of particle breakage ***,based on experimental observation,a path-dependent model was proposed for particle breakage evolution,which was formulated in an incremental form and reasonably considers the effects of the past breakage history and current stress state on the breakage *** path-dependent model successfully reproduced the development of particle breakage during undrained triaxial compression using the parameters calibrated from the drained tests,preliminarily demonstrating its effectiveness for different stress paths.

关键词： Particle breakage Coral sand Triaxial compression Relative breakage Breakage model

Simulation of dual transponder carrier ranging measurements

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第10期10卷 1395-1403页

作者： Xiang-yu zha Xiao-jun JIN Zhong-he JIN department of lnformation Science and Electronic Engineering Zhejiang University Hangzhou 310027 China

The most dominant error source for microwave ranging is the frequency instability of the oscillator that generates the carrier phase signal. The oscillator noise is very difficult to filter due to its extremely low frequency. A dual transponder carrier ranging method can effectively minimize the oscillator noise by combing the reference phase and the to-and-fro measurement phase from the same single oscillator. This method does not require an accurate time tagging system, since it extracts phases on the same satellite. This paper analyzes the dual transponder carrier ranging system by simulation of the phase measurements with comprehensive error models. Both frequency domain and time domain noise transfer characteristics were simulated to compare them with dual one-way ranging. The simulation results in the two domains conformed to each other and demonstrated that a high level of accuracy can also be achieved by use of the dual transponder carder ranging system, with relatively simple instruments.

关键词： dual transponder carrier ranging dual one-way ranging Oscillator noise Transfer characteristic

Ranking approach of cross-efficiency based on improved TOPSIS technique

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Journal of Systems Engineering and Electronics 2011年第4期22卷 604-608页

作者： Jie Wu Jiasen Sun Yong zha Liang Liang School of Management University of Science and Technology of China Hefei 230026 R R. China

The cross-efficiency evaluation method is reviewed which is developed as a data envelopment analysis （dEA） extensive tool. The cross-efficiency evaluation method is utilized to identify the decision making unit （dMU） with the best practice and to rank the dMUs by their respective cross-efficiency scores. The main drawbacks of the cross-efficiency evaluation method when the ultimate average cross-efficiency scores are used to evalu- ate and rank the dMUs are also pointed out. With the research gap, an improved technique for order preference by similarity to ideal solution （TOPSIS） is introduced to rank the crossfficiency by eliminating the average assumption. Finally, an empirical example is illustrated to examine the validity of the proposed method.

关键词： data envelopment analysis (dEA) cross-efficiency,improved technique for order preference by similarity to ideal solu-tion (TOPSIS) decision making unit (dMU).

Preparing cyclic polymers at high concentrations via self-folding cyclization technique by adjusting the contents of hydrophilic units in linear precursors

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Chinese Chemical Letters 2024年第2期35卷 283-288页

作者： Hao zha Zuowei Wang Chao Liu Chunyan Hong department of Polymer Science and Engineering University of Science and Technology of ChinaHefei 230026China Hefei National Laboratory for Physical Sciences at the Microscale University of Science and Technology of ChinaHefei 230026China

Cyclic polymers are a class of polymers that feature endless topology,and the synthesis of cyclic polymers has attracted the attention of many ***,cyclic polymers were efficiently constructed by self-folding cyclization technique at high *** poly((oligo(ethylene glycol)acrylate)-co-(dodecyl acrylate))(P(OEgA-co-ddA))precursors with different ratios of hydrophilic and hydrophobic moieties were synthesized by reversible addition-fragmentation chain transfer(RAFT)polymerization using a bifunctional chain transfer agent with two anthryl end *** amphiphilic linear precursors underwent the self-folding process to generate polymeric nanoparticles in *** irradiating the aqueous solution of the nanoparticles with 365 nm UV light,cyclic polymers were synthesized successfully via coupling of anthryl *** effects of the ratios of hydrophilic and hydrophobic moieties in linear P(OEgA-co-ddA)copolymers and polymer concentration on the purity of the obtained cyclic polymers were explored in detail via ^(1)H nuclear magnetic resonance(^(1)H NMR),dynamic light scattering(dLS),UV‒visible(vis)analysis,three-detection size exclusion chromatography(Td-SEC)and transmission electron microscopy(TEM).It was found that by adjusting the content of the hydrophilic segments in linear precursors,single chain polymeric nanoparticles(SCPNs)can be generated at high polymer ***,cyclic polymers with high purity can be constructed *** method overcomes the limitation of traditional ring-closure method,which is typically conducted in highly dilute conditions,providing an efficient method for the scalable preparation of cyclic polymers.

关键词： Cyclic polymers Self-folding cyclization technique Single chain polymeric nanoparticles RAFT polymerization direct visualization

A comprehensive investigation on nonlinear vibration and bending characteristics of bio-inspired helicoidal laminated composite structures

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Applied Mathematics and Mechanics(English Edition) 2025年第1期46卷 81-100页

作者： S.SAURABH R.KIRAN d.SINgH R.VAISH V.S.CHAUHAN School of Mechanical and Materials Engineering Indian Institute of Technology Mandi

Bio-inspired helicoidal composite laminates, inspired by the intricate helical structures found in nature, present a promising frontier for enhancing the mechanical properties of structural designs. Hence, this study provides a comprehensive investigation into the nonlinear free vibration and nonlinear bending behavior of bio-inspired composite plates. The inverse hyperbolic shear deformation theory(IHSdT) of plates is employed to characterize the displacement field, with the incorporation of green-Lagrange nonlinearity. The problem is modeled using the C0finite element method(FEM), and an in-house code is developed in the MATLAB environment to solve it numerically. Various helicoidal layup configurations including helicoidal recursive(HR), helicoidal exponential(HE), helicoidal semi-circular(HS), linear helicoidal(LH), and Fibonacci helicoidal(FH)with different layup sequences and quasi-isotropic configurations are studied. The model is validated, and parametric studies are conducted. These studies investigate the effects of layup configurations, side-to-thickness ratio, modulus ratios, boundary conditions, and loading conditions at different load amplitudes on the nonlinear vibration and nonlinear bending behaviors of bio-inspired composite plates. The results show that the laminate sequence exerts a substantial impact on both nonlinear natural frequencies and nonlinear bending behaviors. Moreover, this influence varies across different side-to-thickness ratios and boundary conditions of the bio-inspired composite plate.

关键词： Inverse problems

Terrestrial Near-Surface Wind Speed Variations in China:Research Progress and Prospects

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Journal of Meteorological Research 2021年第3期35卷 537-556页

作者： Jinlin zha deming zhaO Jian WU Cheng SHEN CAS Key Laboratory of Regional Climate and Environment for Temperate East Asia Institute of Atmospheric PhysicsChinese Academy of Sciences(CAS)Beijing 100029 Key Laboratory of Atmospheric Environment and Processes in the Boundary Layer over the Low-Latitude Plateau Region Department of Atmospheric ScienceYunnan UniversityKunming 650091 gaochun district Meteorological Office Nanjing 211300

Changes in terrestrial near-surface wind speed(NSWS)are indicative of the concentrated net effect of climate change and anthropogenic *** change mechanisms of NSWS not only furthers the understanding of how the atmosphere changes and improves the climate analysis and projection,but also aids the evaluation and application of wind energy *** advances in studies of the changes and associated mechanisms of the NSWS over China are reviewed in this *** new results have been achieved in understanding the behaviors of the NSWS *** NSWS over China has experienced a decrease in the past 40 years and a recovery in the recent decade,exhibiting large regional and seasonal *** of the mechanisms of the NSWS changes has been improved in several aspects;for example,it is found that the reduced NSWS over China is due to the weakening of the pressure-gradient force(PgF)attributed to variations in large-scale ocean–atmosphere circulations(LOACs)as well as the increase of surface roughness due to the land use and cover change(LUCC).The main methods used to analyze the NSWS changes and corresponding mechanisms are also elucidated and ***,studies are still lacking on the mechanisms for multi-timescale(seasonal,interannual,decadal,multidecadal)variations in the NSWS over China,and it remains unknown about the contributions of different forcing factors to the NSWS ***,key scientific issues regarding our understanding of the NSWS changes are proposed for future investigation.

关键词： near-surface wind speed(NSWS) land use and cover change(LUCC) large-scale ocean-atmosphere circulations(LOACs) detection and attribution future projection

The good,Bad,and Ugly Stories of Chinese Education,Yet They Are Not the Whole Story

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Frontiers of Education in China 2016年第1期11卷 102-106页

作者： Qiang zha York University

Who’s afraid of the big bad dragon?Why China has the best(and worst)education system in the *** *** Francisco,CA:Jossey-Bass,2014.272pp.,(hardcover),$26.95,ISBN:*** entertaining and provocative book was published in 2014 by *** I offer my critique on its content and thesis,I would like to share a piece of information that I recently learnt:The author,*** zhao(who holds a presidential chair and a professorship at the University of Oregon’s College of Education),is ranked 9th in the 2015 RHSU Edu-Scholar Public Influence *** rankings recognize university-based scholars in the US who contributed most substantially to public debates about education in the previous *** this book,with its vivid stories and compelling data,*** offers a fascinating tour of Chinese education,and a nuanced analysis that reveals the secrets that make it both“the best and worst”in the world.

关键词： education Whole holds

RATIO-dEPENdENT PREdATOR-PREY MOdEL WITH STAgE STRUCTURE ANd TIME dELAY

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International Journal of Biomathematics 2012年第4期5卷 15-37页

作者： LIJUAN zha JINg-AN CUI XUEYONg ZHOU School of Mathematical Sciences Nanjing Normal University Nanjing 210046 Jiangsu P. R. China School of Science Beijing University of Civil Engineering and Architecture Beijing 100044 P. R. China

Ratio-dependent predator prey models are favored by many animal ecologists recently as more suitable ones for predator-prey interactions where predation involves searching process. In this paper, a ratio-dependent predator prey model with stage structure and time delay for prey is proposed and analyzed. In this model, we only consider the stage structure of immature and mature prey species and not consider the stage structure of predator species. We assume that the predator only feed on the mature prey and the time for prey from birth to maturity represented by a constant time delay. At first, we investigate the permanence and existence of the proposed model and sufficient conditions are derived. Then the global stability of the nonnegative equilibria are derived. We also get the sufficient criteria for stability switch of the positive equilibrium. Finally, some numerical simulations are carried out for supporting the analytic results.

关键词： Ratio-dependent stage structure time delay characteristic equation globally asymptotical stability.