认知无线电系统的动态双门限协作能量检测算法

认知无线电系统中,认知用户间协作检测有利于提高频谱检测的准确性。基于OR(或)协作方式和多门限能量检测算法,提出了一种动态双门限协作能量检测算法,并根据认知用户接收到的主用户信噪比确定检测门限。理论分析和仿真结果表明,该算法可以有效提高频谱检测概率,降低系统漏检概率。     

生理参数遥测系统无线供能模块的设计

能量供应问题是动物生理参数遥测系统实现长期稳定工作的关键,基于电磁感应的无线供能技术是解决这一问题的有效途径.为向动物生理参数遥测系统提供稳定、安全的能量,从能量传输的稳定性与电磁生物安全性两方面出发,对能量传输模块进行优化设计,实现了由长方形截面发射线圈和三维接收线圈组成的无线供能模块,能够在Φ10.5 mm×11 mm接收空间内提供至少150 mW有效功率,传输效率不小于2.64%.遥测系统的活体实验证实了该供能方式的可行性.     

基于阿伦方差的微机电陀螺误差建模及其粒子滤波

基于Allan方差对微机电陀螺的随机漂移误差进行分析和建模,并通过粒子滤波提高了微机电陀螺的零偏稳定性.实验结果表明,这种方法比较简单而切实可行,可以明显提高微机电陀螺仪的零偏稳定性.     

基于磁耦合谐振的旋转机械嵌入式监控供能技术研究

磁耦合谐振式无线能量传输技术是一种新型的电能传输技术,具有传输效率高、传输距离远的优点.对这种传输技术的基本原理进行了研究,提出利用该技术向安装在旋转部件上的嵌入式监控系统无线输送能量.设计了一对一的能量传输系统,并在此基础上研究了一对多的能量传输模式,分析了一对多的传输机理,实验中将多个接收线圈上的LED点亮.在接收线圈为简单线圈的方向性实验中,当接收线圈与发射线圈平行时,接收线圈接收到的能量最大,而当两者垂直时,接收线圈将接收不到能量.将接收线圈设计成2组圆线圈正交和3组圆线圈正交的形式,保证始终有磁感线穿过接收线圈,提高接收效果,实验验证了这种方法的有效性.     

基于生物安全性的无线能量传输系统发射线圈优化设计

针对为胶囊内窥镜供能的无线能量传输技术在应用过程中对人体组织可能造成伤害的问题,进行了无线能量传输系统发射线圈优化设计研究.分析了人体组织安全性与无线能量传输系统发射线圈之间的关系,提出用磁场均匀度、频率稳定度等指标来评价发射线圈性能,并建立了以能量传输效率为目标函数、以人体安全性和能量需求为约束条件的最优化模型.该模...     

顺流串联逆电渗析电堆数对能量转换效率的影响研究

逆电渗析电堆(RED Stack)可以将自然界中广泛存在或通过人工方法制取的盐差能转换为电能。为了有效提高RED电堆的能量转换效率和输出电压,通过建立RED电堆能量转换模型,对采用溶液顺流流程的多个RED电堆(多电极)串联的RED发电系统进行理论研究,探讨RED流道总长,溶液流速以及RED电堆数对系统能量转换效率及输出特性的影响.计算结果表明:在设定参数下,降低溶液流速,增加流道总长和电堆数均能提升RED系统的发电效率.但随流道总长和电堆数继续增加,效率提升的趋势减缓.串联电堆在增加输出电压和功率密度的同时其总内阻随之增加,导致系统输出电流变化对输出电压和电堆功率密度的影响增大.     

基于蓝牙技术的倒F型天线的设计

<正>蓝牙是一种支持设备短距离通信(一般是1Om之内)的无线电技术,能在设备之间进行无线信息交换,其工作频段是2.4～2.483GHz的全球通信自由频段,目前已广泛应用在移动通信设备中。天线是蓝牙无线系统中用来传送与接收电磁波能量的重要必备组件。由于目前技术尚无法将天线整合至半导体芯片中,故在蓝牙模块里除了核心的系统     

利用微机提取俄歇电子信号

用四极栅能量分析器对样品进行表面分析,既可以得到表面的低能电子衍射图,又可以得到表面俄歇电子信息。但是由于四极栅能量分析器本身结构所限,其灵敏度和信噪比较之筒镜能量分析器为低。为弥补其不足,我们用微机及A/D、D/A技术对表面电     

基于线圈磁耦合模型的无线充电仿真研究

飞行器电气系统"无缆化"是目前研究的热点关键技术之一.本文基于无线传感器网络系统,建立了磁耦合无线能量传输模型和简化电路图,并结合实际工程需要,利用有限元法和控制变量法对磁耦合模型进行仿真分析,详细探讨了磁耦合无线电能传输中的各模型参数对传输功率的影响.最后,在需求传输功率的要求下,对耦合无线能量传输模型中的传输距离、谐振频率和不同激励幅值等参数进行了对比分析和参数优选.本工作针对磁耦合模型的应用研究展开了深入分析,能够为后续工程应用中设计满足需求的磁耦合无线电能传输系统提供一定的借鉴意义.     

无线传声器系统的技术概论（一）

无线传声器系统广泛用于扩声系统,包括发射机和接收机两种单机,涉及无线电发送系统和无线电接收系统。无线传声器占用的频段及其参数见表1。表1无线传声器占用的频段及其性能参数     

Coil geometry models for power loss analysis and hybrid inductive link for wireless power transfer applications

This paper presents a hybrid inductive link for Wireless Power Transfer (WPT) applications. Achieving better power transfer efficiency over a relatively wider distance across coils is the prime objective in most of the WPT systems, but often suffers from power loss in the near field area of inductively coupled coils. One of the reasons for this power loss is the pattern of the magnetic field produced by the source coil used in the WPT system. Mostly the nature of magnetic field produced by the source coil is distributed radially over the coil, in which the produced magnetic field is not fully utilized. Achieving better efficiency and load current by reducing power loss is the main driving force of this work. One of the viable methods to reduce the power loss is by increasing the field intensity thereby redirecting the flux lines flow to be directional. With this aim, three coils such as solenoid, spiral and conical are designed and simulated to determine the magnetic field strength using Finite Element Method. The conical coil produces the highest self-inductance of 8.63 µH and a field strength of 1.542 Wb with the coil thickness of 3.20 mm. Then, WPT system is demonstrated with the inclusion of Maximum Power Point Tracking algorithm for improving efficiency. The schematic of flux generation of both in the transmitter and receiver sections are demonstrated and analyzed graphically. The efficiency of both simulation and experimental measurements are matched well with similar progression. The effect of parameters (angle, distance, and load resistance) on the efficiency is explored. The outcomes conclude that the inductive coupling has achieved 73% (average case) power transfer wirelessly over a distance of 5 cm with an input voltage of 5 V and 5 MHz frequency.     

Operating characteristics and cooling cost evaluation for HTS receiver arrays of wireless power charging system in superconducting MAGLEV train

Since conventional power supply unit should be attached to HTS magnet in the MAGLEV, a large thermal loss is indispensably caused by power transfer wires and joints, those have been one of essential obstacles in the superconducting MAGLEV train. As the wireless power transfer (WPT) technology based on strongly resonance coupled method realizes large power charging without any wires through the air, there are advantages compared with the wired counterparts, such as convenient, safety and fearless transmission of power during movement. Above all, the WPT technology in the MAGLEV can reduce the cost of tunnel construction since the space of conventional power line doesn’t required. From these merits, the WPT systems have been started to be applied to the wireless charging for various power applications such as transportations (train, underwater ship, electric vehicle). In this study, as a practical approach, authors investigate transfer efficiency and cooling cost for multi-Tx and multi-sized single Tx coils under different size of Rx coils arrays, respectively. Additionally, authors investigated transfer ratio at HTS Rx with helix and spiral Tx coils under different interval. As well as, authors evaluate cooling cost of different sizes of HTS receiver under long single and multi-copper antenna arrays based on nitrogen evaporation method.     

A systematic study of DRIE process for high aspect ratio microstructuring

Various MEMS devices like Accelerometers, Resonators, RF- Filters, Micropumps, Microvalves, Microdispensers and Microthrusters are produced by removing the bulk of the substrate materials. Fabrications of such Microsystems requires the ability to engineer precise three-dimensional structures in the silicon substrate. Fabrication of MEMS faces multiple technological challenges before it can become a commercially viable technology. One key fabrication process required is the deep silicon etching for forming high aspect ratio structures. There is an increasing interest in the use of dry plasma etching for this application because of its anisotropic etching behavior, high etch speed, good uniformity and profile control, high aspect ratio capabilities without having any undesired secondary effects i.e. RIE lags, Loading, microloading, loosing of anisotropic nature of etching as aspect ratio increases, micro-grass and even etch stalling. Developing a DRIE micro-machining process requires a thorough understanding of all plasma parameters, which can affect a silicon etching process and their use to suppress the secondary effects. In this paper our intention is to investigate the influence of etching gas flow, etching gas pressure, passivation gas pressure, ICP coil power, Platen power and etch and passivation time sequence on etch rate and side wall profile. Parameter ramping is a powerful technique used to achieve the requirements of high aspect ratio microstructures (HARMS) for MEMS applications by having high etch rate with good profile/CD control. The results presented here can be used to rationally vary processing parameters in order to meet the microstructural requirements for a particular application.     

Study on the micro-heater geometry in In,2O3 micro electro mechanical systems gas sensor platforms and effects on NO2 gas detecting performances

Micro electro mechanical systems (MEMS) platforms for gas sensing devices with the co-planar type micro-heaters were designed, fabricated and its effects on the In2O3 gas sensors were investigated. Micro-heaters in MEMS gas sensor platforms were designed in the four-type heater patterns with different geometries. Electro-thermal characterizations showed that the designed platforms had highly thermal efficiency because the micro hot-plate structures were formed in the diaphragm and the thermal efficiencies were analyzed for all of 16 models and compared with each other, respectively. The designed micro-platforms were fabricated by MEMS process, and Indium oxide (In2O3) nanoparticles were synthesized by sol-gel process and dropped on the MEMS platforms for detecting the noxious oxide gas (NO2) Fabricated micro-platforms had a very low power consumption in the fabricated 16-type models, especially, the minimum power consumption was 41 mW at the operating temperature of 250 degrees C. After experiments on gas sensing characteristics to NO2 gases, fabricated In2O3 gas sensors had almost the same gas sensitivity (Rs) at the operation temperature of 250 degrees C. It is concluded that the micro-heater geometries, pattern shapes and sizes, can be influential on the power consumption of the devices and its gas sensing characteristics.     

基于小波包变换的内燃机气阀漏气诊断方法

探讨了利用缸盖振动信号诊断内燃机气阀漏气的一种新方法－－小波包方法。诊断机理分析和实验研究表明,缸盖 振动信号中关于气阀漏气的特征信息集中在高频段,故选用了小波包变换作为信号处理的基本方法,因为小波包变换较之小波变换在中高频段具有更高更均匀的频率分辨率;对实测信号的分析和处理结果表明了小波包在该领域的适用性;建立了基于马氏距离法的气阀漏气多指标诊断模型;进行了实机诊断,取得了预期的效果。     

基于干法刻蚀技术的氮化镓MEMS加工工艺(英文)

氮化镓(GaN)材料已成功应用于光电子器件、高频功率器件等领域.近年来,由于GaN优异的材料特性,例如机械、热、化学稳定性以及生物兼容性等,使基于GaN的微机电系统(MEMS)得到了学术界的广泛关注.针对氮化镓MEMS结构的有效的图形化及释放技术是工艺研究的重点.设计、采用了一种全干法刻蚀技术,实现了(111)晶向硅衬底上的氮化镓基MEMS微结构的加工制造.利用提出的工艺方案,实现了多种悬浮GaN微结构的加工与测试表征实验.通过电子扫描显微镜(SEM)和光学轮廓仪进行了基本形貌表征;利用微拉曼光谱实验进行了加工结构的残余应力表征.     

小波包变换和隐马尔可夫模型在轴承性能退化评估中的应用

轴承是旋转机械中的关键部件,有效地对其进行性能退化评估对指导设备维护、防止设备意外失效有非常重要的意义。本文提出了一种基于小波包变换和隐马尔可夫模型（HMM）的轴承性能退化评估方法。该方法使用小波包变换对轴承振动信号进行分析,并提取节点能量及其总能量作为特征,仅使用正常状态下的数据训练HMM,建立性能退化评估模型,然后使用该模型对轴承的退化程度进行定量评估。最后,通过对轴承加速疲劳寿命试验的研究,验证了所提出的方法的可行性和有效性。     

Inkjet-Printed Metal Oxide/PEDOT:PSS-Based Diodes and Rectifiers for Wireless Power Transfer

Printed electronic circuits are beginning to attract commercial success in different areas of applications that include low-cost wearables, biosensors, biomedical tags, packaging, e-textiles, etc. However, the major part of the research in this domain has always been focused on developing high-performance thin-film transistors (TFTs), while the other essential circuit elements, that are required, for example, for low-loss conversion of the input power, have rarely been reported. In this regard, inkjet-printed amorphous oxide-based diodes on glass, and flexible polyimide substrates with rectification ratio >10⁴ and operation frequency up to 25 and 15 MHz, respectively, are demonstrated. Next, using the printed diodes’ full-wave and double half-wave rectifiers are fabricated to convert input AC signals to DC supply. In addition, wireless power transfer (WPT) is demonstrated, where the input AC signal is wirelessly transmitted from a distance of 3 cm, at 125 kHz. The demonstrated WPT technology can be suitable for invasive implantable devices and standalone systems in multiple mediums. Finally, bending fatigue tests are carried out with the printed diodes on flexible substrates, down to a bending radius of 2.5 mm to demonstrate tensile strain tolerance up to 2.5%.     

高温环境下MEMS微构件动态特性测试技术研究

基于放电激励方法建立了高温环境下MEMS微构件动态特性测试系统,该系统主要由激励装置、激光多普勒测振仪、微构件温度控制系统组成.激励装置利用尖端放电产生的激波激励微构件,通过进给机构调节电极间距以改变激励能量.激励底座是用高温胶粘接而构成的多层结构,包括微构件安装板、十字载台、陶瓷绝缘片和板电极.微构件胶粘在底座上,其振动响应信号由多普勒测振仪测量,计算机对测量数据频谱分析后得到谐振频率.编写了基于LabVIEW的微构件温度控制软件,控制测试时温度.利用该测试系统,测试了微构件在室温~500℃环境下的谐振频率,得到了谐振频率随温度变化规律.     

利用频闪成像方法进行微机电系统的计量

为了实现MEMS器件的计量,一个基于频闪成像原理的MEMS动态测试平台被构建,用于在全频率、相位和电压输入范围内表征器件的全三维运动。系统利用高亮度LED和LD作为脉冲光源,有效冻结MEMS器件的面内和离面运动,能在从静止状态到1MHz很宽的频率范围内对MEMS器件进行表征,达到了纳米级分辨力。通过实验对一个微谐振器进行了三维运动测量,在扫频和扫幅两种工作模式下,配合强大的数据分析软件,给出器件运动的幅频和相频特性曲线,为分析器件的动态性能提供了可靠数据。