基于WSN的轨道客车空调数据采集分析系统

为快速准确地验证高速动车组空调系统的数值模拟计算结果,提出了一种数据采集分析系统方案。通过对比分析试验测量与模拟计算的结果,帮助设计人员评价车厢内的热舒适性,建立新的客车空调效果检验模式。系统由无线数据采集子系统、空调性能分析软件及空调设计数据库组成。无线测量网络基于ZigBee协议,节点硬件应用JN5139模块设计,采用Cskip算法的树型网络地址分配策略,对温湿度传感器进行非线性补偿;CFD（Computational Fluid Dynamics）计算使用FLUENT软件;用ADPI（Air Diffusion Performance Index）指标评价热舒适性。小规模模拟试验表明,系统工作稳定可靠,准确地实现了温湿度等参数的实时测量。     

Morphological analyses of minute crystals by using stereo-photogrammetric scanning electron microscopy and electron back-scattered diffraction

We present a new method for the morphological analyses of minute faceted crystals by combining stereo-photogrammetric analysis of scanning electron microscope images and electron back-scattered diffraction. Two scanning electron microscope images of the same crystal, recorded at different tilt angles of the specimen stage, are used to determine the orientations of crystal edges in a specimen-fixed coordinate system. The edge orientations are converted to the indices [ uvw ] in the crystal system using the crystal orientation determined by electron back-scattered diffraction analysis. The Miller indices of crystal facets are derived from the indices of the edges surrounding the facets. The method is applicable to very small crystal facets. The angular error, as derived from tests using a calcite crystal of known morphology, is a few degrees.
To demonstrate the applicability of the method, the morphology of boehmite (γ-AlOOH) precipitated from solution during the dissolution of anorthite was analyzed. The micrometre-sized boehmite crystals are surrounded by two {010} basal facets and eight equivalent side facets that can be indexed equally well as {323}, {434} or {545}. We suggest that these side facets are in fact {111}, the morphology having been modified slightly (by a few degrees) by a small extension associated with opening along (010) microcleavage planes. Tiny {140} facets are also commonly observed.     

高温橡胶废气在电滤装备中的流场特性研究

为研究板式电滤装备对橡胶行业燃烧所产生高温烟气的净化效果,建立了板式电滤装备的物理模型,分析板式电滤装备内部复杂的流场特性以及不同温度橡胶烟气对装备内部电场分布和净化效率的影响,利用FLUENT对烟气温度为323~673 K时板式电滤装备的收尘过程进行了数值模拟。结果表明:在相同放电电压下,烟气的温度越高,电荷密度越低,电场强度越小,烟气中细颗粒物所受静电力越小;温度升高会增强细颗粒物与流体间的相互作用,表现在气体粘度和颗粒曳力增大,从而降低了净化效率,尤其是对粒径在1μm以下的细微颗粒物,其净化效率减小得更为明显。     

Microstrip Band Pass Filter of GHz Region Employing Aerosol-Deposited Alumina Thick Films

The miniaturized 10 GHz microstrip band-pass filter was successfully fabricated on the alumina thick films grown on Cu substrates at room temperature by aerosol deposition method and using the newly developed pattern electroplating procedure and electromagnetic analysis. The relative dielectric permittivity and loss tangent of the aerosol-deposited alumina thick films on Cu were 9.9 and 0.089, respectively. The resistivity of the electroplated Cu line was determined to be 2 × 10^{? 8} Ω m. The very good agreement was shown between results simulated using a 3-dimensional electromagnetic analysis and the actual measured data.     

ESCAPING THE LOCAL TRAP? THE ROLE OF COMMUNITY‐REPRESENTING ORGANIZATIONS IN URBAN GOVERNANCE

ABSTRACT: This article explores the potential dangers of parochialism in using community‐based associations to represent community interests and the role of these organizations in advising on citywide policies in urban governance. Based on recent theoretical debates on citizen participation at the local level, we analyze whether community‐based participation potentially leads to parochial pursuit of community interests at the expense of broader regional goals by investigating the effect of organizational and community characteristics. Using Los Angeles neighborhood councils as an empirical case, this exploratory analysis finds that the nature of neighborhood council members’ civic activities is related to the degree to which they may potentially pursue parochial interests. A similar relationship is found between the geographic location of communities and such pursuits. Lastly, neighborhood council members’ civic activities and other community characteristics also influence their activities concerning advice on citywide policies. These findings suggest ways that neighborhood councils might play a greater role in advising on citywide policies in urban governance.     

Time optimal control of linear systems with a terminal region

In this paper we formulate a time optimal control problem for a continuous time linear system with a terminal region by the method based on functional analysis and present its solution. The solution is obtained from the results of a minimization of a convex function that is solved by a digital computer. Numerical results of an example system are shown for the two cases of amplitude constraint and energy constraint on control inputs.     

混合集成电路的电磁兼容设计

本文主要介绍了在混合电路设计时需考虑的电磁兼容问题,并分析了产生问题的原因.从电子系统电磁兼容性角度出发,详细地叙述了混合集成电路的布局和布线规则,并进行了讨论.     

MODELING AND OPTIMIZATION OF OHMIC HEATING OF FOODS INSIDE A FLEXIBLE PACKAGE

A pulsed ohmic heating system and flexible package for food reheating and sterilization were developed to minimize Equivalent System Mass during long‐duration space missions. A package made of flexible pouch materials was powered through a pair of metal foil electrodes extending out. Preliminary tests of the package within an ohmic heating enclosure show that International Space Shuttle menu items such as chicken noodle soup and black beans could be heated using pulsed ohmic heating technology. The electrical conductivities of selected samples ranged between 0.01 and 0.03 S/cm. A 2‐D thermal‐electric model was developed using commercial CFD software Fluent to optimize the design and layout of electrodes to ensure uniform heating of the material. A static system under the assumption of there being no fluid motion in a microgravity environment was implemented. A package configuration with V‐shaped electrodes with dimensionless width of 0.147 was validated to be most appropriate for uniform heating while minimizing the cold zone to 2% of total area. The effect of field overshoot near the electrode edge is expected to be crucial to determine the uniformity of heating.     

基于相电流特征的配电网单相断线区段定位新方法

由于雷击等原因,配电网单相断线故障时有发生。为了避免断线故障导致电机损坏等事故,文章基于相电流特征提出了一种断线故障区段定位新方法。首先利用序网络分析了配电网发生断线故障后的相电压、电流特征,然后根据相电压特征构造了启动判据和故障选相判据,根据相电流相关系数构造了区段定位识别判据。所提出的方法具有灵敏度高、通信量小的优点,PSCAD仿真验证了该方法的有效性。     

外源水杨酸对低温胁迫下烤烟抗氧化代谢的影响

为有效解决烤烟生产中的低温危害问题,用不同浓度的水杨酸(SA)喷施烤烟后置于5℃低温下胁迫,研究外源SA处理对低温胁迫下烤烟抗氧化代谢的影响.结果表明:外源SA预处理的烤烟叶片中超氧化物歧化酶( SOD)和过氧化氢酶(CAT)活性增加,相对电导率降低,脯氨酸(Pro)、叶绿素(chl)和抗坏血酸( AsA)含量均提高,且以浓度1.0 mmol·L-1的效果最好,说明适宜浓度的SA能够增强低温胁迫下烤烟抗膜脂过氧化能力,从而抵御低温危害.