垂直管内油水分散流的数值研究

建立封闭的双流体模型并对垂直管内油水分散流进行了数值模拟,采用κ-ε模型处理连续相的湍流结构。模型预测结果与实验数据的比较结果表明,该模型能较好地模拟垂直管湍流分散流的局部相含率分布和速度分布。     

考虑循环水–能源桩换热的单U型埋管能源桩变热流传热模型

基于有限长度线热源模型和叠加原理,提出了一种变热流条件下有限长度线热源模型的近似解答;在此基础上,将单U型换热器划分为多个节段,采用热响应的分段叠加思路,最终建立了考虑循环水与能源桩换热的单桩变热源传热模型。通过与Comsol三维数值模型和无限长线热源模型出水口温度的比较以及与试验中出水口温度和土体温度的比较,验证了该模型的准确性。同时通过该传热模型进行了U形管能源桩不同桩长、不同质量流率、不同桩土导热系数的换热分析。此模型可以帮助我们获得随时间变化的热流密度和更为精确的出水口温度,便于能源桩换热量的快速评估。     

近红外光谱技术检测植物木质素纤维素研究进展

近红外光谱技术可用来检测植物木质素、纤维素及半纤维素含量,与传统的湿化学方法相比具有快速、操作简单、准确、无损等优点,是一种新型的测定方法,近年来在检测木本植物及草本植物木质纤维素组成成分中被广泛应用。综述了国内外利用近红外光谱技术快速检测木本植物(用作造纸原料的木材、竹材以及潜在的可用作生物质能源的木材)及草本植物(饲草及草类能源植物)木质素、纤维素、半纤维素含量的研究进展,并从样品前处理、光谱预处理及波长选取方法、化学计量学方法三个方面对利用近红外光谱技术快速检测植物木质素、纤维素方法研究上的进展进行了总结,并结合国内木材、牧草及能源草行业发展现状提出了四点展望: 建立适用性更强的模型;建立全面的草产品品质指标近红外光谱数据库;建立能源植物能用品质指标相关模型并对建模方法进行进一步的探索和完善;推动应用近红外光谱技术检测植物木质纤维素的方法从实验阶段走向实际应用。随着对近红外光谱检测植物木质纤维素方法的不断成熟和完善,它必将对造纸、饲草及能源草行业的发展产生巨大的推动作用。     

回旋速调管放大器时域非线性理论与模拟

研究了一种回旋速调管放大器时域非线性理论模型.该模型由广义电报方程来表示回旋速调管内的电磁场,采用引导中心近似的电子运动方程来推动粒子,由粒子更新得到的电流密度为源激励电磁场.基于上述理论模型,从回旋速调管电子注横向速度满足高斯分布出发,建立了速度分散的分布模型,编写了相应的时域非线性注波互作用模拟程序,对回旋速调管放大器的注波互作用进行了深入的分析和研究,并应用粒子模拟软件与自洽非线性模拟程序进行对比验证,两者结果基本一致.     

附加碳税的综合能源系统优化调度分析

针对节能减排的能源转型发展要求,构建了结合可再生能源以及储能装置的综合能源系统模型。引入碳税将CO₂排放的环境问题转换为经济成本问题并建立以经济成本最低为目标函数的优化模型。利用改进的猫群算法对碳税为50 CNY/t的综合能源系统冬夏两季典型日优化调度,对比传统的冷热电三联产(CCHP)系统,综合能源系统的CO₂排放在夏季是CCHP系统的48.93%,冬季为50.86%;节能率在夏季可达到36.33%,冬季能达到23.65%;与没有引入碳税的综合能源系统相比,冬夏两季典型日共减少了40.28%的CO₂排放。对不同碳税下减排效果与经济性的分析,现阶段采用中等的碳税水平(50 CNY/t)更为合理。     

太阳能和风能的短期分散储存

运用太阳能和风能是解决能源问题的根本和长期的途径,但是,传统的能源可以根据需要调节供应,而太阳能和风能是间歇性的而且不能随需要来控制,要有效地运用太阳能和风能,能量储存是必须的,大规模长期储存能量是非常昂贵的,解决这个问题的一种方案是太阳能和风能的短期分散储存,所谓短期,是指十几小时至几天,相当于太阳能和风能的变化周期.所谓分散,是指以单个建筑为单位,并且以多种不同的方式储存能量,从产业发展的角度看,太阳能和风能的短期分散储存的没备会形成一个新的大规模的工业部门.     

多分散高浓度介质偏振光后向扩散散射的Monte Carlo仿真

建立了针对多分散高浓度介质偏振光后向扩散散射的Monte Carlo仿真模型，导出了多分散 系统的有效自由程分布函数. 给出了半径为50nm与550nm及其三种不同体积浓度比混合的聚 苯乙烯微球作为散射粒子的高浓度介质的仿真结果. 定性地分析了多分散介质偏振光后向扩 散散射的光强空间分布特征与粒子的体积浓度比的关系. 关键词： 后向扩散散射 偏振光 多分散高浓度介质 Monte Carlo仿真     

分散液相微萃取-高效液相色谱法测定蜂蜜中的磺胺类抗生素

应用分散液相微萃取(DLLME)技术,建立了蜂蜜中磺胺类抗生素的高效液相色谱分析方法。考察了萃取剂、分散剂、萃取剂体积、分散剂体积、时间、盐度和pH等因素对分散液相微萃取的影响,并确定了最佳萃取条件为:40μL 1,1,2,2-四氯乙烷(萃取剂)和1mL乙腈(分散剂),混匀后,加入水样,离心2min,吸取5μL沉积相,进行HPLC分析。应用本方法对3批蜂蜜样品进行了测定,取得了良好的效果。     

ORC换热设备结构与操作参数多目标同步优化

随着全球性的能源紧缺和环境问题日益严重,通过充分利用可再生能源和工业余热资源,从而提高能源利用效率是缓解能源和环境问题的重要方式。有机朗肯循环(ORC)是最有应用前景的低品位热能发电技术之一。本文针对ORC系统建立了结构参数和系统操作参数同步优化的换热设备多目标优化模型,采用R245fa为工质和板式换热器,以效率最大和比投资成本最小为目标函数。首先分析了单个变量(蒸发压力、冷凝压力、过热度、蒸发器板间距、冷凝器板间距)对系统性能的影响,然后选取了系统的运行参数(蒸发压蒸发压力、冷凝压力、过热度)和换热器的结构参数(蒸发器和冷凝器的板长、板宽、板间距)九个参数为决策变量,利用遗传算法进行ORC换热设备结构与操作参数多目标同步优化,获得多目标优化的Pareto最优前沿及对应的最优系统运行参数和最佳换热器结构参数组合。     

应变液晶的负压光效应和反式压光效应

介绍聚合物分散液晶和应变液晶概念,给出聚合物分散液晶调光玻璃的"正压光效应"、"负压光效应"和"反式压光效应"三种效应定义.实验制备出负压光效应和反式压光效应新型应变调光玻璃样品,测试样品散射态雾度90%以上,半透明态透光率接近30%.用偏光显微术研究压光效应原理,表明对样品施加垂面按压或拉伸的应力诱导作用会引起液晶微滴中液晶分子具有某些特殊排列方式,导致样品光学性质发生显著变化.建立垂面拉伸液晶微滴模型,计算模拟所绘出的图形与偏光显微镜照片独特花样十分相似,进而合理解释了实验现象.应变液晶压光效应研究具有聚合物分散液晶基础研究意义和开发非电控调光玻璃的实际应用价值.     

Model of self-oscillations in a neuron generator under the action of an active medium

Mechanisms of generation of self-oscillations in a mathematical model of a neuron embedded in an active medium have been analyzed. The processes of generation of pulsed electric activity are mediated by ionic currents through the cell membrane of the neuron, which can in turn be controlled by neuroactive substances distributed in the extracellular space. Bifurcation mechanisms of the generation and destruction of self-oscillations, as well as their characteristics, have been studied within a neuron generator model developed on the basis of neurobiological experiments.     

ELECTRIC CIRCUIT DESIGN AND TESTING OF INTEGRATED DISTRIBUTED STRUCTRONIC SYSTEMS

Modelling distributed parameter systems (DPS) by electric circuits and fabricating the complicated equivalent circuits to evaluate system responses poses many challenging research issues for many years. Electrical modelling and analysis of distributed sensing/control of smart structures and distributed structronic systems are even scarce. This paper is to present a technique to model distributed structronic control systems with electric circuits and to evaluate control behaviors with the fabricated equivalent circuits. Electrical analogies and analysis of distributed structronic systems is proposed and dynamics and control of beam/sensor/actuator systems are investigated. To determine the equivalent circuits and system parameters, higher order partial derivatives are simplified using the finite difference method; partial differential equations (PDE) are transformed to finite difference equations and further represented by electronic components and circuits. To provide better signal management and stability, active electrical circuit systems are designed and fabricated. Electrical signals from the distributed system circuits (i.e., soft and hard) are compared with results obtained by the classical theoretical, finite element, and experimental techniques.     

A Linear programming formulation for routing asynchronous power systems of the Digital Grid

In recent years, practical research related to distributed power generation and networked distribution grids has been increasing. This research uses a relatively abstract model for the cost reduction in the Digital Grid Power Network. In the Digital Grid, the traditional wide-area synchronous grid is divided into smaller segmented grids which are connected asynchronously. In this paper, we demonstrate how to formulate the minimized cost of power generation by using linear programming methods, while considering the cost of electric transmission and distribution and using asynchronous power interchange among separate grids.     

DYNAMICS AND DISTRIBUTED CONTROL OF CONICAL SHELLS LAMINATED WITH FULL AND DIAGONAL ACTUATORS

Nozzles, rocket fairings and many engineering structures/components are often made of conical shells. This paper focuses on the finite element modelling, analysis, and control of conical shells laminated with distributed actuators. Electromechanical constitutive equations and governing equations of a generic piezo(electric)elastic continuum are defined first, followed by the strain-displacement relations and electric field-potential relations of laminated shell composites. Finite element formulation of a piezoelastic shell element with non-constant Lamé parameters is briefly reviewed; element and system matrix equations of the piezoelastic shell sensor/actuator/structure laminate are derived. The system equation reveals the coupling of mechanical and electric fields, in which the electric force vector is often used in distributed control of shells. Finite element eigenvalue solutions of conical shells are compared with published numerical results first. Distributed control of the conical shell laminated with piezoelectric shell actuators is investigated and control effects of three actuator configurations are evaluated.     

Self-organized criticality and 1/f fluctuation under conditions of nonequilibrium phase transitions

The results are given of an experimental investigation of fluctuation phenomena under conditions of electric arc discharge. Fluctuations are observed whose spectral density is inversely proportional to frequency (1/f noise). Power dependences are revealed of the fluctuation distribution functions. The behavior of spectral density and of distribution functions is associated with the simultaneous occurrence of various nonequilibrium phase transitions. Within the framework of the mean field theory, a mathematical model is suggested of interacting nonequilibrium phase transitions in a distributed system, which predicts the self-organization of the critical state and the generation of fluctuations with diverging spectral characteristics. An adequate agreement is observed between the suggested model and experimental data.     

Piezoelectric effect in liquid crystals

A piezoelectric effect has been observed in a cholesteric liquid crystal layer (an electric field effect type, a mixture of cholesteryl oleyl carbonate, cholesteryl chloride and cholesteryl nonanoate) [1]. The layer, subjected to shear vibration, generates an alternating electric potential of the same frequency as the exciting vibration. In the present paper an extension of these investigations is reported to cases with various mixing ratios and also to one of smectic liquid crystals (lecithin with water). For a cholesteric liquid crystal of a particular mixing ratio, the strength of the electric generation is found to reach as high as 450 mV(p-p) for a vibratory shear displacement of 1 μm(p-p) under a certain molecular orientation preparation. Small electric generation is also observed for the above smectic liquid crystal but not for the nematic liquid crystals (MBBA and EBBA). A simple continuum elasticity model can qualitatively explain the behaviour of this electric potential generation.     

电场对协流式微流控装置中乳液液滴生成行为的调控机理

建立了直流电场作用下协流式微流控装置中单乳液液滴乳化生成过程的非稳态理论模型,并开展了数值模拟研究,揭示了电场对液滴乳化生成动力学行为的调控机理,阐明了流场/电场参数对液滴乳化生成特性的影响规律.研究结果表明:沿流体流动方向施加静电场可在电物性参数不同的两相流体界面法线方向上产生指向内相流体的电场力,进而强化了内相流体界面的颈缩和断裂,提升了液滴生成速率和形变程度,减小了液滴生成尺寸;在同一毛细数下,随着电毛细数的增大,乳液乳化流型由每周期仅有单一液滴生成的滴式流型转变为每周期有一个主液滴并伴随有卫星液滴生成的滴式流型;随着毛细数和电毛细数的增大,黏性拖曳力以及电场力作用增强,使内相流体颈缩过程后期更容易形成细长型液线,从而有助于诱发液线上产生Rayleigh-Plateau不稳定现象,继而促进卫星液滴的形成.     

Study on power generation using electro-conductive polymer and its mixture with magnetic fluid

A new power generation system using electro-conductive polymer and its mixture with magnetic fluid is introduced. The system using non-poison electro-conductive polymer and its mixture with magnetic fluid and operating at room temperature is proposed in the present paper. The system could be used as a micro-distributed energy supply system for domestic use in the future. An experimental set-up is designed and established to investigate the performance of the power generation with an aid of a theoretical analysis of the power generation. It is found that the theoretical results are in good agreement with the measured data. Based on the obtained results, the electric output increases with Reynolds number, size of the test channel, magnetic strength and electric conductivity. It is understood that in order to obtain a practical power generation, priority should be put on increasing fluid flow velocity and magnetic field strength.     

空调轿车降温特性的数值模拟与实验研究

本文通过建立与车箱体传热相耦合的轿车空调车室内三维空气流动与传热的数学模型,研究了汽车空调制冷系统和车室内空气流动的耦合特性,对空调轿车降温特性进行了动态模拟,建立了环境模拟试验台,验证了理论模型的可靠性．     

分布式能量系统的综合评价

分布式能量系统由于具有良好的经济与环保性能,得到了世界各国的普遍重视。本文选取人们所关注的经济性、可靠性、环保性及CO2减排的几个因素作为指标,建立了分布式能量系统综合评价的指标体系和模糊识别模型。通过分布式能量系统与传统大电网集中供电方式的比较,结合实际案例,对几种常用的供能方式进行了综合评价。本文的研究成果为在电力市场竞争机制下分布式能量系统的发展与规制提供了决策支持,有利于实现分布式能量系统与大电网集中统一供电的相互补充,以满足不同用户的需求。