Dynamic electrothermal simulation of integrated resistors at device level

This paper presents the dynamic electrothermal simulation of a rectangular resistor integrated on a semi-conductor substrate. Due to the temperature dependence of the electrical conductivity of the resistive sheet, self-heating provokes a coupling between the electrical and thermal problem and gives rise to nonlinear phenomena. We introduce a time stepping iterative method to perform the calculations. The electrical and thermal solvers are based on FEM and Green's functions techniques, respectively. An extensive dynamic analysis of the device will be presented. The results include heating and cooling curves, Nyquist plot (complex locus) of the thermal impedance, time constant spectrum and structure function. Comparisons with the linear case, i.e. a temperature independent resistor, are made and accompanied by analytical approximations if possible. One key observation is that the nonlinearity may easily be overlooked: its detection is only possible in particular characteristics.     

平面左手结构色散与传播特性分析

采用时域有限差分方法研究了一种新型平面结构阵列在左手频带内的后向波传播特性与负折射特性,提出分析二维平面左手结构的新方法:基于单元结构的四端口网络参数进行Bloch分析,得出色散关系和Bloch阻抗;根据色散关系和Bloch阻抗分析相位与能量传播方向的关系,以确定出左右手特性频带.相比于以往单元结构分析方法,本文方法利于单元结构的灵活设计,能较好地考虑分布参数元件色散特性,能简便准确地判断出左右手特性频带,且能用于分析各向异性和有损耗结构.仿真分析结果验证了方法的有效性.     

电压波动与闪烁试验的豁免方法

当电气电子产品不符合EN61000—3—3的限值时，可以作为有条件连接产品进行评估以表明符合EN61000—3—11。介绍了如何通过声明最大允许连接阻抗的方法，使不符合EN61000—3—3的产品实现有条件连接。     

Eddy current analysis of thin metal container in induction heating by line integral equations

In recent years, induction‐heating cookers have spread rapidly. It is desirable to commercialize flexible and disposable food containers that are suitable for induction heating. In order to develop a good‐quality food container for moderate heating, the eddy currents induced in a thin metal plate must be accurately analyzed. The integral equation method is widely used for solving induction‐heating problems. If the plate thickness approaches zero, the surface integral equations on the upper and lower plate surfaces tend to become the same and the equations become ill‐conditioned. In this paper, we first derive line integral equations from the boundary integral equations under the assumption that the electromagnetic fields in the metal are attenuated more rapidly than those along the metal surface. Next, to test the validity of the line integral equations, we solve for the eddy current induced in a thin metal container in induction heating and obtain the power density imparted to the container and the impedance characteristics of the heating coil. We then compare the computed results with those obtained by the FEM. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 168(2): 20–27, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20813     

Ionic conductivity improvement in primary pores of fuel cell catalyst layers: Electropolymerization of m-aminobenzenesulfonic acid and its effect on the performance

Catalyst layers of direct methanol fuel cells (DMFCs) are modified by in situ electropolymerization of m-aminobenzenesulfonic acid. By using electrochemical impedance spectroscopy and porosimetry, this modification is found to add polymer electrolyte into primary pores (<10 nm), where ionic resistance is high for lack of polymer electrolyte (i.e., Nafion), and the additional electrolyte successfully decreases the ionic resistance by 10-15% compared to the plain carbon surface with a slight ion-conductivity (>40 kΩ cm). In view of methanol oxidation characteristics, this modification decreases the resistance by ca. 25% (from 5.1 Ω cm² to 3.7 Ω cm²) at 0.6 V vs. DHE, resulting in the increase in the cell voltage of DMFC test by ca. 20 mV. The clear relation between the performance and the microstructures is concluded to be helpful to understand the performance of fuel cell electrodes in detail.     

含有纯滞后特性的PI(D)—VGAC系统的稳定性和鲁棒性

应用Fenandez等人对含有纯滞后特性的自适应系统的理论分析方法,针对由一阶惯性环节加纯滞后特性所构成的PI(D)—VGAC系统的稳定性及鲁棒性进行了分析,得出了一些结论,并将其推广到高阶系统。数字仿真结果验证了这些结论是正确的。     

有向图的满装

本文应用 Edmonds 定理得到了某些有向图中以固定顶点为根的弧互不交的支撑树形图的极大个数.     

弱光下不同黄瓜品种生理适应性的研究

在弱光条件下测定了5个黄瓜品种的生理性状。结果表明,津优30号叶面积增加最多,津优2号较多,寒月居中,绿宁3号和北极星最少;津优30号和寒月叶绿素含量增加较多,绿宁3号和津优2号居中,北极星最少;寒月光抑制程度较轻;津优30号和津优2号光合产物转化受抑最轻,叶片淀粉累积量最高;津优30号干物重累积量最多,寒月较多,津优2号居中,绿宁3号和北极星最少。综合比较得出,津优30号的适应性最强,寒月、绿宁3号和津优2号居中,北极星适应性最差。     

简易单参数自适应PID控制研究

提出一种基于工程整定法的简易PID控制算法。该算法是根据扩充临界比例法等工程整定方法将PID公式简化，然后根据一般的控制系统阶跃响应曲线特性分析，得出该控制器增益的变化规律，并用于该简易PID控制算法增益的自适应变化。该算法已经用于实际的印染行业的有关设备的温度控制中，通过对打样机（印染行业的一种设备）温度的控制可以看出，该算法的控制效果良好，适应能力较强，具有算法简单、参数整定容易等特点，非常适合于工程上的应用。     

Positive and negative recency effects in retirement savings decisions.

Retirement savings decisions can be influenced by the fund composition of the retirement savings plan. In 2 experiments, strong composition effects were observed, with a larger percentage of resources being invested in stock funds when more stock than bond funds were offered. Although participants changed their allocations repeatedly, the opportunity to learn did not alter the composition effects. Learning processes led to positive and negative recency effects as well, providing evidence that allocations were strongly influenced by the recent performance of the different allocation options. Two learning models were tested to explain these learning processes. The first, a local adaptation learning model, assumes that people change their behavior on the basis of recent experience, whereas the second, a reinforcement learning model, assumes that decisions are made on the basis of the totality of accumulated experience. The local adaptation model was more accurate in predicting allocation decisions, in explaining positive and negative recency effects, and in showing why composition effects are not overcome by learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)