真空高温退火对锻态Ti-6Al-4V合金显微组织与超塑性性能的影响

退火处理是改善钛合金显微组织,提高力学性能及超塑成形性能的一种重要工艺。使用真空退火炉在850℃-950℃温度区间内对锻态Ti-6Al-4V合金的进行了高温退火处理,研究了退火态Ti-6Al-4V合金微观组织演变及其在温度为900℃,应变速率为0.01 s^-1时的超塑拉伸性能。结果表明,锻态Ti-6Al-4V合金的初生α晶粒尺寸随真空退火温度的升高而减小,β相比例随真空退火温度升高而增大。当真空退火温度为910℃时,Ti-6Al-4V合金的晶粒尺寸和α相与β相分布较为均匀,其超塑拉伸试验结果表明,该合金表现出最佳的超塑拉伸性能,其拉伸延伸率达到785%,峰值应力仅为26.8 MPa。     

组合转子同步电机稳定性探讨

组合转子同步电机由轴向叠片各向异性(ALA)磁阻段和面贴式永磁(SPM)段组合而成,磁路各自独立.为研究组合转子电机在开环V/f控制方式下的稳定性,采用小信号分析方法,探讨无惯性阻尼器和附加机械惯性阻尼器的组合式转子电机SPM段占转子全长之比k与电机稳定性的关系.研究结果表明,无惯性阻尼器的组合式转子电机,k值增大,稳定频率范围扩宽不明显;附加惯性阻尼器,选择合适的惯量盘惯量,调节阻尼器的粘性阻尼系数能明显扩宽稳定频率范围,且k和惯量盘惯量越大,阻尼器的粘性阻尼系数调节范围越宽,电机的稳定性越好.     

A sub‐1V supply CMOS voltage reference generator

An integrated sub‐1V voltage reference generator, designed in standard 90‐nm CMOS technology, is presented in this paper. The proposed voltage reference circuit consists of a conventional bandgap core based on the use of p‐n‐p substrate vertical bipolar devices and a voltage‐to‐current converter. The former produces a current with a positive temperature coefficient (TC), whereas the latter translates the emitter‐base voltage of the core p‐n‐p bipolar device to a current with a negative TC. The circuit includes two operational amplifiers with a rail‐to‐rail output stage for enabling stable and robust operation overall process and supply voltage variations while it employs a total resistance of less than 600 K Ω. Detailed analysis is presented to demonstrate that the proposed circuit technique enables die area reduction. The presented voltage reference generator exhibits a PSRR of 52.78 dB and a TC of 23.66ppm/^°C in the range of ? 40 and 125^°C at the typical corner case at 1 V. The output reference voltage of 510 mV achieves a total absolute variation of ± 3.3% overall process and supply voltage variations and a total standard deviation, σ, of 4.5 mV, respectively, in the temperature range of ? 36 and 125^°C. Copyright © 2011 John Wiley & Sons, Ltd.     

基于Zigbee无线传感器网络的智能灯光跟随系统

设计一个基于Zigbee的智能灯光跟随系统。系统中连接有人体红外热释电传感器的Zigbee结点等距离分布在走廊或道路的旁边,检测特定区域人员是否存在的信息,并将信息传于协调器节点,协调器节点连接主控制器PX-A270,PXA270根据采集的信息控制舵机的转向和照明装置的亮与灭,实现有人走动存在时,灯光随着人的转移而转移,无人时照明系统自动熄灭,从而实现节约能源的效果。     

B/S模式下的在线评教系统

系统基于Visual Studio .NET 2003(C#),以SQL Server 2000为数据库,采用B/S模式,运行于校园网络平台,实现各类用户对教师教学水平的在线评估.用户被分成学生、专家和教师三类.学生和专家可以对教师进行评估;教师可以查看学生和专家对自己的评价.每个用户都可以通过系统的反馈机制实现与系统管理人员的及时交流.     

采用V.34建议的高速传真保密机的研究与实现

本文研究分析了采用V.34建议的高速传真通信规程,阐述了高速传真保密通信的基本原理,基于此设计实现了门卫式高速传真保密机.     

RFID在音圈振膜自动化生产线中的应用

本文针对音圈振膜自动化生产线所选用的RFID系统进行了软硬件设计,详细介绍了V680系列的RFID系统。并在Sysmac Studio编程软件中对其进行通信测试,最后对上游工位下来的载体进行数据采集并将采集到的数据嵌入到本工作站实现相应的动作。     

Concept and demonstration of an intermediate band tandem device for solar energy conversion

We have realized a tandem solar cell design that combines a pin‐junction with a photovoltaic intersubband absorber. This concept allows harvesting light in the visible range and the near‐ and mid‐infrared at the same time, and theoretically, energy conversion efficiencies beyond the Shockley–Queisser‐limit could be achieved. A test structure was grown, and the operation of this concept could be confirmed, in principal with an optical two‐beam experiment. The basic characteristics of the device can be explained with an equivalent circuit design that consists of three individual cells, and we find an obvious analogy to the concept of the intermediate band solar cell with noteworthy advantages at some points. Our results show, that for a working device it is crucial to adjust the properties of the photovoltaic intersubband absorber for optimal charge separating performance at the working point of the solar cell. Copyright © 2015 John Wiley & Sons, Ltd.     

Assessing material qualities and efficiency limits of III–V on silicon solar cells using external radiative efficiency

The paper presents a quantitative approach to the investigation and comparison of the material qualities of III–V on silicon (III–V/Si) solar cells by using external radiative efficiencies. We use this analysis to predict the limiting efficiencies and evaluate the criteria of material quality in order to achieve high‐efficiency III–V/Si solar cells. This result yields several implications for the design of high‐efficiency III–V/Si solar cells. Copyright © 2016 John Wiley & Sons, Ltd.     

Distance and clustering‐based energy‐efficient pseudonyms changing strategy over road network

To improve the fairness, the energy consumption changing pseudonyms needs to be taken into account. Existing works focus on changing velocity‐based pseudonyms changing strategy and short changes interval with limited coverage, but due to similar velocity and short changes, internal attacker guesses easily known communication and location information due to location information of vehicle on tracking, which may expose adversary private information, and frequently, pseudonyms changing occurs due to movement of vehicles' similar velocity and short coverage, which may cause serious attack of vehicle. To overcome this problem, distance and cluster can be performed. In this work, we proposed distance and cluster‐based energy pseudonyms changing method for road network. We proposed distance and energy‐based clustering routing service over road network, the cluster head elected to depend on random number of distance and energy to change pseudonyms of vehicles. An each interval to be establish cluster head vehicle deployed while selects the operation mode and informs the cluster members of the selected mode through beacon signal. The cluster head vehicle node performs the pseudonyms changing based on the predicted distance and energy of the cluster member to use clustering optimization. The data of whole network send to report server through these nodes while near the RSU, and the vehicles in this area will use less energy to change the pseudonyms. The simulation results show that the proposed method enhances pseudonyms changing strategy less consumption and delays sufficient privacy level each vehicle also our method has outperform compare with existing methods than we use Sumo simulation and Matlab tools to verify our proposed method. Our proposed method outperformed in terms of pseudonym changing energy efficiency to careful attention during the cluster formation process, stable and balanced clusters that prolong the network lifetime, increases distances to more CH vehicles connectivity to makes clustering group and changing their pseudonyms in terms of high level privacy and finally, CH nodes use Dijkstra's algorithm use MST among the vehicles nodes depend on existing road networks to follow shortest path selection roads in terms of high connectivity probability of CH and stable structure of the network decreases the topology changes and thus,the clustering overhead is reduced.