压电悬臂梁发电机能量转换效率研究

为提高车轮轮毂振动下的压电悬臂梁发电机能量转换效率,根据哈密顿原理建立了发电机能量转换效率模型,利用数值模拟和试验分析的方法研究了发电机结构尺寸和材料特性对其能量转换效率的影响规律。研究表明,金属基板过厚或太薄、杨氏模量太小都不利于提高发电机的能量转换效率。在金属基板材料不同时,存在一个最佳厚度比(金属基板与总厚度之比)使发电机能量转换效率最高,铜、铝、钼3种金属基板材料的发电机最佳厚度比分别为0.67、0.72、0.45;在相同厚度比(0.5)条件下,钼基板的发电机能量转换效率较高,随着杨氏模量比(金属基板的杨氏模量与陶瓷的杨氏模量之比)的增大,发电机能量转换效率增高,但当杨氏模量比大于4时,发电机的能量转换效率变化不明显。     

蝴蝶式多层悬臂梁压电发电装置研究

为了提高压电发电装置的发电能力,设计了一种新型的蝴蝶式多层压电悬臂梁。为了研究该装置中每个压电双晶梁的发电性能,建立了在自由端外力作用下压电悬臂梁的输出电压理论模型,以此用来分析压电双晶梁的开路输出电压。制作了多层压电发电装置,并搭建实验平台对装置的发电电压进行实验测试,将实验测试数据与理论计算结果进行比较,两者误差小于10%。将发电装置中的6层压电片串联后研究发现,装置的发电电压基本不变,而发电功率可达单层的6倍,说明该新型蝴蝶式多层压电悬臂梁结构可提高发电能力。     

变负载压电悬臂梁共振频移量研究

基于Euler-Bernoulli梁原理研究了铝基双晶串联压电悬臂梁电压频响和短路-开路共振频移量问题。以悬臂梁总厚度和压电陶瓷厚度为影响参数,首先推导了输出电压的单/多模态解,再以单模态解为基础,分析了不同厚度压电悬臂梁短路-开路共振频移量。研究结果表明,与多模态解相比,单模态解的估计性良好,且计算简便。在任意变负载区间内,存在最劣压电陶瓷厚度,使短路-开路共振频移量最大。因此,在进行压电悬臂梁结构设计时,应尽量避开最劣点,使外部负载具有最佳适应性,提高能量回收效率。     

GMM,PZT和弹性基板复合磁电耦合效应研究

将超磁致伸缩材料(GMM)、压电材料(PZT-5H)复合于弹性基板上,利用共振原理构造了一种新型的磁电换能器。当激励磁场的频率等于或者接近于弹性基板的固有频率时,GMM将驱动弹性基板振动并发生共振,粘结于基板上的压电材料的输出电压将达到极大。实验研究表明,该器件的磁电耦合电压曲线呈现多个峰值,在800Oe偏置磁场和1Oe交变磁场激励下,谐振点处的磁电耦合电压系数达到1.552V/Oe。     

GMM,PZT和弹性基板复合磁电耦合效应研究

将超磁致伸缩材料(GMM)、压电材料(PZT-5H)复合于弹性基板上,利用共振原理构造了一种新型的磁电换能器.当激励磁场的频率等于或者接近于弹性基板的固有频率时,GMM将驱动弹性基板振动并发生共振,粘结于基板上的压电材料的输出电压将达到极大.实验研究表明,该器件的磁电耦合电压曲线呈现多个峰值,在800 Oe偏置磁场和1 Oe交变磁场激励下,谐振点处的磁电耦合电压系数达到1.552 V/Oe.     

圆盘式压电双晶片发电性能和耦合电路的仿真分析与研究

以有限元分析法为理论基础并搭配ANSYS软件,建立圆盘式压电双晶片振子的模型,研究压电振子半径、压电层厚度和支撑层厚度对其发电能力的影响。并在此基础上探讨压电-电路的导纳阻抗及输出功率特性。着重研究压电双晶片在串联和并联两种连接方式之间的差异。研究结果表明,在保证可靠度和固有频率的前提下,应尽量增加压电振子半径,减小振子的基板厚度,以获得最大的输出电压。串联方式的输出电压大,内部阻抗高,适用于后续负载阻抗较高的能量采集系统;并联方式的内部阻抗较串联式低,适用于后续负载阻抗适中的能量采集系统。而当在两种电路连接方式下的外部电阻达到最佳电阻值时,两者最佳输出功率相同。     

面向负载功率的压电悬臂梁研究

基于电路负载阻抗匹配原理,为最大程度利用压电悬臂梁发电装置收集环境振动能量,保证压电悬臂梁外接负载能够正常工作,需要研究压电悬臂梁结构参数对其最佳输出功率以及相对应外接负载匹配阻值的影响。该文通过压电电路分析,研究了基板和压电陶瓷片的长度、厚度、宽度和质量块质量对压电悬臂梁最佳输出功率以及相对应负载匹配阻值的影响。结果表明,一定范围内,增加基板长度、压电陶瓷片厚度、质量块质量可以增加压电悬臂梁外接负载匹配阻值,增加基板厚度、压电陶瓷片长和宽可降低压电悬臂梁外接负载匹配阻值;随着基板长度、压电陶瓷片宽和长、质量块质量的增加,压电悬臂梁最佳输出功率得到显著提高,基板宽度对压电悬臂梁最佳输出功率基本无影响,增加压电陶瓷片的厚度,压电悬臂梁最佳输出功率先增加后降低,存在一个最佳输出功率。     

收集人体动能的压电俘能器研究

提出了一种基于压电效应的人体动能转换装置(压电俘能器),并对其发电能力进行了理论和试验分析。结果表明,在一定变形范围内,压电俘能器的输出电能随着激励力的增加而增大;当激励频率和压电俘能器结构尺寸确定时,压电俘能器的输出功率随着负载电阻的变化而变化,且存在最佳的负载使其输出功率达到最大值,最大输出功率是压电俘能器开路时电压和电容的函数,最大输出功率与外接滤波电容无关。在2Hz(行走频率)激振频率下,压电俘能器最大输出功率为0.31mW。     

基于行车风压的谐振腔式压电俘能器研究

针对汽车行驶过程中车载传感器需要持续稳定的供能需求,设计一种以谐振腔结构为主体,扰流圆柱与亥姆霍兹谐振腔为辅助的压电俘能器。为研究俘能器的发电性能,设计其最佳结构,建立流固电耦合仿真模型。仿真时,根据实际风压分布,将风压载荷分区加载到压电发电模块。仿真分析结果表明,基板与压电陶瓷的厚度比对压电悬臂梁的输出电压和固有频率有影响,最佳厚度比为1.25;基板与主腔体间间隙、扰流圆柱直径、亥姆霍兹谐振腔皆存在最佳尺寸参数使压电俘能器发电性能达到最佳;负载电阻在400～600 kΩ内时,可获得最佳的输出功率;风速为15 m/s时,最大输出功率为37.3 mW。     

谐振法确定热激励微梁谐振器厚度及残余应变

精确测量热激励微梁(悬臂梁和桥)谐振器的厚度和残余应变对研究其谐振特性具有重要意义。由于组成谐振器的薄膜厚度远小于占优层厚度，本文首先利用单层梁谐振频率推算得梁的厚度的近似值，从而得到热激励梁的等效杨氏模量和等效密度。在此基础上利用双层梁谐振频率精确推算梁的厚度和残余应变，结果与测量值符合较好。该方法具有非破坏性的优点。     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers

A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.     

Diode-end-pumped Nd:YVO4/LBO lasers with 4.2W continuous-wave output at 457 nm

A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.     

Call for Papers

正Wireless Body-area Networks The last decade has witnessed the convergence of three giant worlds:electronics,computer science and telecommunications.The next decade should follow this convergence in most of our activities with the generalization of sensor networks.In particular with the progress in medicine,people live longer and the aging of population will push the development of wireless personal networks