关键词： 光机械   动力学冷却:声子  

摘要： 基于光机械耦合系统,详细研究了该系统的动力学冷却问题,比较了强耦合系统中不同的光学腔模型耗散率对平均声子数的影响.在一定的范围内,腔耗散率越大,平均声子数越小,并且有更大的腔耗散率,平均声子数才能快速地达到瞬态冷却极限,即通过增大腔耗散率,能加速系统的冷却过程.对于强耦合系统,随着耦合强度的增加,平均声子数出现周期性的振荡,且随着腔耗散率的增大而快速的减小,最后达到一个冷却极限.相反,对于弱耦合体系,平均声子数随着腔耗散率的增大而快速的增大,而后达到一个稳定的平衡态,且随着耦合强度的增大,不会出现周期性的振荡.因此,在弱耦合系统中,增大腔耗散率有可能会加速系统的热过程.

关键词： 农业机械化   农业劳动力   劳动力转移  

摘要： 农业是国家经济发展的基础。农业发展与人们的生活息息相关。随着时代的发展进步,现代化技术日新月异,农业现代化也已经成为现代农业的发展趋势。农业机械化的产生和发展,必将造成更多的农业劳动力剩余。本文论述了农业机械化发展条件及其发展影响,并对农业劳动力转移制约因素进行了简单分析。

关键词： 排放约束   液力传动   动力传动系统   匹配   加权因子  

摘要： 基于加权因子法,提出了一种集动力性、经济性与排放性于一体的煤矿液力车辆动力传动系统合理匹配的综合评价指标,同时引入了衡量该类车辆排放特性好坏的颗粒物和排放质量指数,并给出了各加权参数因子确定方法和加权系数确定原则。利用Advisor软件建立了煤矿液力车辆动力传动系统仿真模型,结合Matlab优化工具箱编制了煤矿液力车辆动力传动系统优化程序,并以WCJ10E煤矿井下防爆无轨胶轮车为例进行了分析计算,通过台架试验验证了仿真模型的准确性,在此基础上考虑排放特性约束对某型号煤矿液力传动车辆的动力传动系统进行了优化匹配。

关键词： MASS TRANSFER   Mass flux   Net solute removal rate   slag refining   mechanical agitation   slag constitution   Bulk phases   STIRRING RATE  

摘要： Mechanical stirring was demonstrated to be a potent means to increase the mass transfer rates of B and Ca in slag refining of silicon, and optimal stirring conditions were attained with only a modest kinetic energy input into the melt. Experiments were undertaken to measure mass transfer rates between liquid silicon and CaO-SiO2 slags at 1823 K (1550 degrees C) with varying stirring speed and slag composition. A remarkable feature of this system is the extreme fluctuation in interfacial area-these changes occur very rapidly and are difficult to capture. As little as 50 rpm stirring speed promotes, significant transient increases in interfacial area. At stirring speeds above 100 rpm, the rates of mass transfer do not increase significantly, so it is evident that above this threshold mass transfer in the bulk phases and interfacial area generation are already maximized. With a sufficiently high content of CaO in the slag, interfacial phenomena induced by the mass flux of calcium facilitate emulsification, and this is explained from a thermodynamic standpoint. It is likely that the calcium transfer enhances boron transfer by increasing the available interfacial area.

关键词： Mechanical ventilation   Pneumatic system   Dimensionless dynamics   Modeling simulation   Experimental study  

摘要： Dynamics of mechanical ventilation system can be referred in pulmonary diagnostics and treatments. In this paper, to conveniently grasp the essential characteristics of mechanical ventilation system, a dimensionless model of mechanical ventilation system is presented. For the validation of the mathematical model, a prototype mechanical ventilation system of a lung simulator is proposed. Through the simulation and experimental studies on the dimensionless dynamics of the mechanical ventilation system, firstly, the mathematical model is proved to be authentic and reliable. Secondly, the dimensionless dynamics of the mechanical ventilation system are obtained. Last, the influences of key parameters on the dimensionless dynamics of the mechanical ventilation system are illustrated. The study provides a novel method to study the dynamic of mechanical ventilation system, which can be referred in the respiratory diagnostics and treatment.

关键词： Systems biology   Mechanistic explanation   Understanding   Systems-level understanding   Abstraction   Complexity  

摘要： In this paper we draw upon rich ethnographic data of two systems biology labs to explore the roles of explanation and understanding in large-scale systems modeling. We illustrate practices that depart from the goal of dynamic mechanistic explanation for the sake of more limited modeling goals. These processes use abstract mathematical formulations of bio-molecular interactions and data fitting techniques which we call top-down abstraction to trade away accurate mechanistic accounts of large-scale systems for specific information about aspects of those systems. We characterize these practices as pragmatic responses to the constraints many modelers of large-scale systems face, which in turn generate more limited pragmatic non-mechanistic forms of understanding of systems. These forms aim at knowledge of how to predict system responses in order to manipulate and control some aspects of them. We propose that this analysis of understanding provides a way to interpret what many systems biologists are aiming for in practice when they talk about the objective of a "systems-level understanding." (C) 2014 Elsevier Ltd. All rights reserved.

关键词： CARBON dioxide fixation   ZINC catalysts   HETEROCYCLIC compounds   CHEMICAL kinetics   ORGANIC solvents   CHEMICAL reactions  

摘要： In this contribution, a series of N-heterocyclic compounds cooperated with ZnBr2 catalyst for chemical fixation of CO2 to cyclic carbonates was developed without utilization of additional organic solvents. It was found that the catalytic activity of N-heterocyclic compounds could be obviously enhanced in the presence of ZnBr2, and the N-methylimidazole (Mim)/ZnBr2 catalytic system was the most efficient among the catalysts employed. Under the optimum reaction conditions, 99% yield of propylene carbonate was achieved with TOF of 474 h(-1), and the catalysts were also versatile for CO2 cycloaddition with less active epoxides such as styrene oxide and cyclohexene oxide. Furthermore, a possible synergistic catalytic mechanism was proposed. Moreover, the rate constants were determined as a function of reaction temperature in the range of 130-160 degrees C, the activation energy was determined to be 41.1 ***(-1), and the kinetic equation on the synthesis of propylene carbonate catalyzed by Mim/ZnBr2 was also obtained.

关键词： Mechanical properties   defects   nanomaterial modeling  

摘要： A molecular dynamics (MD) based computational intelligence (CI) approach is proposed to investigate the Young modulus of two graphene sheets: Armchair and Zigzag. In this approach, the effect of aspect ratio, the temperature, the number of atomic planes and the vacancy defects on the Young modulus of two graphene sheets are first analyzed using the MD simulation. The data obtained using the MD simulation is then fed into the paradigm of a CI cluster comprising of genetic programming, which was specifically designed to formulate the explicit relationship of Young modulus of two graphene structures. We find that the MD-based-CI model is able to model the Young modulus of two graphene structures very well, which compiles in good agreement with that of experimental results obtained from the literature. Additionally, we also conducted sensitivity and parametric analysis and found that the number of defects has the most dominating influence on the Young modulus of two graphene structures.