Fabrication of a MEMS inertia switch on quartz substrate and evaluation of its threshold acceleration

Based on surface micromachining technology, a micro-electro-mechanical system (MEMS) inertia switch with single sensitive direction and reverse impact protection has been designed and fabricated on quartz substrate. The switch is laterally driven (i.e. its sensitive direction is parallel to the substrate plane), in which the conjoined snake springs are used to fix and suspend the movable electrode (i.e. proof mass), and blocks are used to protect the device against reverse impact. The relationship between the threshold acceleration a_th and the intrinsic frequency has been investigated by theoretical analysis and finite element simulation, respectively, based on which the geometrical parameters of the switch can be decided to meet design objective. The proof mass thickness H was chosen as a variable, as the micro-fabrication of the device was carried out by low-cost and convenient multi-layer electroplating technology, where H can be easily adjusted while the plane geometry remains the same. The stress distribution of the switch in the contact process was also simulated. Packaged micro-switches were tested by dropping hammer experiments, which generated half-sine wave acceleration as in reality. The measured threshold acceleration generally met the design objective of 60g and the response time was in the order of 10⁻⁴ s, both agreed with the simulated results.     

功率器件封装工艺中的铝条带键合技术

文章回顾了功率器件封装工艺中几种常见的互连方式,主要介绍了铝条带键合技术在功率器件封装工艺中的主要优点,特别是它应用在小封装尺寸的功率器件中。铝条带的几何形状在一定程度上降低了它在水平方向的灵活性,但却增加了它在垂直方向上的灵活性。铝条带垂直方向的灵活性可以让我们使用最少的铝条带条数来达到功率器件键合的要求。也由于几何形状的不同,铝条带键合具有一些不同于铝线键合的特点,但它对粘片工艺、引线框架和包封工艺的要求与粗铝线键合极其相似,可以与现有的粗铝线键合工艺相兼容,不需要工艺和封装形式的重新设计。     

基于分块Contourlet变换的图像盲分离

文章研究了多尺度Contourlet变换并将它与独立分量分析ICA结合起来,在传统的小波ICA基础上提出了FRITICA方法。利用Contourlet变换比小波变换具有更好的稀疏性以及图像进行分块处理后某些图像块的星座图比其他图像块的星座图方向性更好的特点,提出一种基于分块Contourlet变换的独立分量分析方法,进而提高叠加混合图像的盲分离的效果与速度。     

数字化校园中统一身份认证与数据同步研究及实现

高校现有信息系统的问题主要表现在：高校原有信息系统基本上是各个部门相对独立开发出来的,每个应用都有自己的一套身份验证和访问控制机制。而为了建设信息集成与加工为核心的高校教育管理综合信息系统就必须首先建设一套完善和安全的数字化校园统一身份认证系统。本文结合数字化校园建设的实际发展情况,讨论了如何在最新的网络计算环境——Web Services下实现统一身份认证系统和相关应用系统的数据同步问题。     

氢脉泽中四极磁态选择器的设计及其应用

氢脉泽是一种中、长期稳定度最高的原子频率标准.其中原子磁态选择器的改进设计可以改善氢脉泽的工作参数及其体积与重量,从而改进氢脉泽的品质与工作寿命等,同时也可以改进氢脉泽的长期性能,并给出了磁态选择器的设计与实验结果.     

集成波导型表面等离子体共振传感芯片及其理论分析

集成波导型表面等离子体共振传感芯片是表面等离子体共振传感技术和微电子制造技术相结合的产物.介绍了集成表面等离子体共振传感芯片的工作机理和基本结构,并通过基于传统波导模式的分析法结合表面等离子体波的色散方程,发展出简单实用的波导表面等离子体共振分析方法.利用该方法对波导型表面等离子体共振传感芯片的工作状态进行了理论建模,给出了各特性参数之间的关系.这证明该方法是分析等离子体共振传感芯片优化的有力工具.     

A new ARMAX model based on evolutionary algorithm and particle swarm optimization for short-term load forecasting

In this paper, a new ARMAX model based on evolutionary algorithm and particle swarm optimization for short-term load forecasting is proposed. Auto-regressive (AR) and moving average (MA) with exogenous variables (ARMAX) has been widely applied in the load forecasting area. Because of the nonlinear characteristics of the power system loads, the forecasting function has many local optimal points. The traditional method based on gradient searching may be trapped in local optimal points and lead to high error. While, the hybrid method based on evolutionary algorithm and particle swarm optimization can solve this problem more efficiently than the traditional ways. It takes advantage of evolutionary strategy to speed up the convergence of particle swarm optimization (PSO), and applies the crossover operation of genetic algorithm to enhance the global search ability. The new ARMAX model for short-term load forecasting has been tested based on the load data of Eastern China location market, and the results indicate that the proposed approach has achieved good accuracy.     

无线通信式低零值绝缘子手持检测仪

为及时检测出挂网运行绝缘子串中的低零值绝缘子,在总结输电线路瓷质低零值绝缘子检测方法后提出一种以分布电压为主,辅助考虑泄漏电流和脉冲电流的低零值绝缘子检测新方法,并据此研制了一套可在线定量测量≤220kV电压等级的输电线路瓷质绝缘子分布电压、泄漏电流和脉冲电流的低零值绝缘子检测仪。该检测仪采用高精度小型高压分压器和傅氏滤波算法保证所测电压精度;使用低功耗微控制器并结合触发测量机制保证检测仪省电;使用无线通信技术、屏蔽桶屏蔽等抗干扰措施优化检零过程和仪器结构以保证检测仪具有高可靠性和智能性,整个检测仪轻巧、实用。     

基于量子退火Metropolis-Hastings算法的叠前随机反演

传统的Metropolis-Hastings （MH）算法是一种常见的随机反演方法,可以得到大量来自于后验分布的样本,从而得到更可靠的参数估计和反演结果的不确定性信息,但对于较为复杂的参数空间,MH算法往往不能对其充分搜索。为此,针对该问题提出了基于量子退火MH算法的叠前随机反演方法,主要通过调节算法的接受概率提高算法的计算效率和稳定性。模型试算与实际数据反演结果表明,相较于传统的MH算法,该方法具有更高的收敛效率。     

鲟鱼传统发酵过程中挥发性风味物质的分析评价

以鲟鱼为原料,采用固相微萃取-气相色谱-质谱联用法,研究其发酵过程中挥发性风味物质种类和相对含量的变化情况,结合感觉阈值,采用相对气味活度值评价挥发性风味物质对总体风味的影响,探讨发酵过程中的关键性风味物质。分别检测新鲜鲟鱼,腌制鲟鱼,发酵5、10、20、25、35 d 7 个阶段的挥发性风味物质,结果表明：新鲜、腌制、发酵5、10、20、25、35 d 7 个阶段的挥发性风味物质种类分别为38、48、66、72、75、76 种和84 种。新鲜鲟鱼肉的主体风味物质为2,4-癸二烯醛、1-辛烯-3-醇、壬醛、癸醛、己醛等;腌制后的鲟鱼肉主体风味物质为壬醛、1-辛烯-3-醇、己醛、癸醛、柠檬烯等;发酵5 d鲟鱼肉的主体风味物质为1-辛烯-3-醇、柠檬烯、壬醛、乙酸乙酯、庚醇等;发酵10 d鲟鱼肉的主体风味物质为壬醛、1-辛烯-3-醇、乙酸乙酯、柠檬烯、癸醛等;发酵20 d鲟鱼肉的主体风味物质为壬醛、柠檬烯、1-辛烯-3-醇、癸醛、乙酸乙酯等;发酵25 d鲟鱼肉的主体风味物质为壬醛、柠檬烯、1-辛烯-3-醇、乙酸乙酯、癸醛等;发酵35 d鲟鱼肉的主体风味物质为乙酸乙酯、柠檬烯、壬醛、1-辛烯-3-醇、庚醇等。