矩形压电片对Lamb波传感的方向性研究

矩形压电片被广泛用作超声Lamb波的传感器与驱动器。理论推导了矩形压电片对Lamb波（A₀模式）的传感灵敏度系数的函数表达式,同时对推导结果进行了实验验证。研究结果表明矩形压电片对Lamb波的传感具有很强的方向性。当Lamb波传播方向沿着矩形压电片长度方向时,矩形压电片传感响应电压最大。随着Lamb波入射角度的增大,响应电压幅值越来越小,当入射方向与矩形压电片长度方向垂直时,响应幅值达到最小。     

基于动态图像差分的多维脉搏信号获取

传统的脉搏传感器无法实现真正的多点脉搏信号检测。该文应用新型脉搏图像化检测装置采集脉搏动态图像，提出利用图像差分的方法获取多点脉搏信号。对不同差分方法实验结果的进一步比较分析表明，利用选择参考帧的差分法能够获得稳定的脉搏信号。讨论了参考帧的选择，实现了多维脉搏信号的获取。为脉搏信号检测与脉诊客观化研究提供了新的思路和方法。     

Smart ultrasonic sensors systems: potential of aluminum nitride thin films for the excitation of the ultrasound at high frequencies

We investigated the potential of the aluminum nitride films to excite ultrasonic waves at frequencies >50?MHz. The deposition process of the aluminum nitride thin film layers on silicon substrates was investigated and optimized regarding their piezoelectric behavior. Large single element transducers were deposited on silicon substrates with aluminum electrodes, under different parameters for the magnetron sputter process, like pressure and bias voltage. Special test setup and a measuring station were created to characterize the sensors. Acoustical measurements were carried out in pulse echo mode up to 500?MHz and the values of piezoelectric charge constant (d₃₃) were determined. As a result, two parameter sets were found for the sputtering process to obtain an excellent piezoelectric charge constant of about 7.2?pC/N maximum. Then the sputtering process with these parameters was used to deposit sensors on various substrate materials and with different electrode sizes.     

一种简易通用的敲击触发式惯性导航系统时间同步装置设计方案

科学研究与工程实践中常需要利用多种传感器协同工作获取被测目标的动态信息,此时对不同传感器采集的数据进行时间同步是必要前提。提出了一种以“敲击-脉冲”信号为媒介的时间同步方案,通过能够在敲击瞬间产生脉冲信号的时间同步装置实现惯性导航系统等运动传感器与其他脉冲同步传感器的时间同步,并通过实验验证了其可行性和时间同步精度。与传统的硬件方案或软件方案时间同步技术相比,本方案通用性极强,开发工作量小,操作简单方便,适用于对时间同步精度要求不高的传感器或系统的快速试验评估。     

Investigations on excitation and detection methods for Lamb wave sensors

Due to a high potential sensitivity, Lamb wave acoustic sensors have been studied for biochemical applications. Usually, Lamb waves are generated and detected using piezoelectric transducers. This technology involves bilayers structures and causes some problem of induced strain and temperature compensation. In this paper, we have investigated optical and electrostatic excitation methods. The optical excitation of Lamb waves is studied, and the main limitations of such an excitation method are pointed out. Theoretical as well as experimental studies are reported on electrostatic excitation of Lamb waves, and it is shown that this technique can be suitable for biosensors.     

基于ATmega16单片机的智能伞控制系统的设计

智能伞控制系统选用ATmega16单片机为核心控制芯片,集风速、光强、雨水传感器和其他辅助模块为一体;雨水传感器把采集到的雨量信号经过光电转换模块转化为脉冲宽度信号;风速传感器将风杯转速转化为电信号;光强传感器同时对流过两个光敏二极管的电流进行积分,并转换为数字量;所有的信号都传给单片机,经过微机分析,根据已经设定好的模糊算法,执行相应的驱动电机程序或保持系统状态不变,并在LCD上显示实时雨水、风速、光强和时钟等相关信息,从而实现了户外伞的自动化运行和管理。     

Selectivity of SPR fiber sensors in absorptive media: An experimental evaluation

Conventional surface plasmon resonance (SPR) fiber sensors show selective behavior when resonance wavelengths are tuned to absorption peaks of the surrounding medium, as it is experimentally shown and evaluated in this paper by using a doubly-deposited uniform-waist tapered optical fiber (DLUWT) and a dye as a test material. This behavior is clearly distinguishable from the usual response to nonabsorbing media and can be used to develop a new concept of SPR transducers. At the same time, the obtained results, which are in accordance with the theoretical predictions permit to increase the basic knowledge on surface plasma waves excitation in optical fibers.     

Effective Maximum Likelihood Grid Map With Conflict Evaluation Filter Using Sonar Sensors

In this paper, we address the problem of building a grid map using cheap sonar sensors, i.e., the problem of using erroneous sensors when seeking to model an environment as accurately as possible. We rely on the inconsistency of information among sonar measurements and the sound pressure of the waves from the sonar sensors to develop a new method of detecting incorrect sonar readings, which is called the conflict evaluation with sound pressure (CEsp). To fuse the correct measurements into a map, we start with the maximum likelihood (ML) approach due to its ability to manage the angular uncertainty of sonar sensors. However, since this approach suffers from heavy computational complexity, we convert it to a light logic problem called the maximum approximated likelihood (MAL) approach. Integrating the MAL approach with the CEsp method results in the conflict evaluated maximum approximated likelihood (CEMAL) approach. The CEMAL approach generates a very accurate map that is close to the map that would be built by accurate laser sensors and does not require adjustment of parameters for various environments.      

基于卡尔曼滤波的动态脉搏波处理和脉率提取

在脉搏的动态检测中,由于被测体运动等因素的干扰,由压阻式脉搏传感器得到的脉搏波会发生形变甚至波峰丢失,最终影响到脉率的提取。本文采用动态阈值结合波峰位置估计的方法识别脉搏波峰,并计算瞬时脉率;利用加速度计实时检测被测体的运动情况并动态调整瞬时脉率的置信度,进而引入Kalman滤波器,实现基于运动测量的自适应滤波。实验结果表明,该方法有效地消除了运动噪声,最终实现准确实时监测脉率。     

基于MC9S12DG128单片机智能车设计与实现

本智能车控制系统采用飞思卡尔16位单片机作为唯一的核心控制单元,加以直流电机、舵机、光电传感器和电源电路以及其他电路构成。由安装在车前部的反射式红外传感器负责采集信号,并将采集到的电平信号传入核心控制单元,核心控制单元对信号进行判别处理后,由PWM4发生模块发出PWM波,分别对转向舵机和直流电机进行控制,完成智能车的转向与前进。智能车后轮上装有霍尔传感器,用来采集车轮转速反馈的脉冲信号,并经由核心控制单元进行PID控制算法处理后会自动调节输入到电机驱动模块的PWM波占空比,从而控制小车的速度。寻迹由RPR220型光电管完成。     

Imaging of layered media in inverse scattering problems for an acoustic wave equation

Two-dimensional (2D) inverse scattering problems for the acoustic wave equation consisting of obtaining the density and acoustic impedance of the medium are considered. A necessary and sufficient condition for the unique solvability of these problems in the form of the law of energy conservation has been established. It is proved that this condition is that for each pulse oscillation source located on the boundary of a half-plane, the energy flow of the scattered waves is less than the energy flux of waves propagating from the boundary of this half-plane. This shows that for inverse dynamic scattering problems in acoustics and geophysics when the law of energy conservation holds it is possible to determine the elastic density parameters of the medium. The obtained results significantly increase the class of mathematical models currently used in solving multidimensional inverse scattering problems. Some specific aspects of interpreting inverse problems solutions are considered.     

基于双原理的热流量传感器的研究

介绍了一种基于测热原理的新型流量传感器 ,它采用加热器对流体加热 ,利用薄膜温度传感器 ,通过测量流体的温度差和热脉冲上升时间 ,实现流量的测量。两种测量方法相结合使得测量范围有了较大的提高 (0 .1～ 15 0mm/s) ,响应时间缩短到了 2ms,并且 ,这种传感器对杂物不敏感。     

汽车组合仪表有意电磁干扰空时域联合分离系统设计

有意电磁波与汽车仪器电磁传输波产生的混合干扰,降低了汽车组合仪表的稳定运行能力,造成仪表设备失灵。为避免上述情况的发生,设计汽车组合仪表有意电磁干扰空时域联合分离系统。在步进电机驱动电路中,设置汽车组合仪表控制器、分离电源与 PCB 电路板、有意电磁干扰数字传感器。分配有意电磁波空时域源地址,通过计算干扰信号平坦度的方式,确定脉冲参数的取值范围,实现汽车组合仪表有意电磁的空时域干扰效应分析。估算有意电磁波干扰信号的数目,按照信号分解的处理原则,求解联合分离修正函数,实现电磁干扰的联合分离。实验结果表明,设计系统应用后可以在混合信号中,按照空域、时域标准的不同分离有意电磁波,不会因混合干扰降低汽车组合仪表的稳定运行能力。     

随机系统事件驱动控制策略的研究与设计

随着传感器和网络技术的发展，无线传感器网络广泛应用于各种场景，然而在多数应用中，传感器节点的能量无法得到补充。另外由于电子开关元件的使用寿命多以触发次数为量度，这使得如何有效利用能源、延长网络的工作寿命成为需要考虑的关键因素之一。讨论随机系统的一种事件驱动控制机制，设计控制策略决定控制器何时发送控制数据，平衡系统性能和驱动频率。通过一类二次性能指标函数推导出这种控制策略，分别就状态反馈和输出反馈设计出性能指标计算公式，推理出性能指标上界，并将定理中的条件转化为可以使用线性矩阵不等式工具箱求解的LMI。通过理论分析和实验，验证了控制策略的可行性和有效性。     

基于工控机和环形线圈传感器的车速测量系统

介绍了一种基于工控机和环形线圈传感器的车速测量系统，该系统主要依据车辆通过两个环形线圈感应探头时，经过检测器的整形，得到两个不同时刻的宽脉冲，再经过高分频，计数，然后把所采集的数据通过专用的PCI卡送入到工控机中进行处理，得到车辆通过环形线圈时的频率变化波形，最后利用波形的相关性，得到同一车辆经过两个线圈时的时间差，利用速度公式，计算出车辆的速度。     

Human-centered computing: thinking in and out of the box

The motion picture "AI" lets the AI profession squirm in the glory of misrepresentation. It's not fun, especially when one's field suffers from waves of innovation/hype/backlash. The problem is that the film "AI" reinforces the dream of the android just when many who work toward "truly" intelligent technologies are cutting loose from the dream's more surrealistic aspects. People are asking new questions: Is the Turing test really the right kind of standard? If not, what is better? Must we define intelligence in reference to humans? Must intelligent technology be boxes chock-full of this thing we call intelligence, or should it operate as a "cognitive prosthesis" to amplify or extend human perceptual, cognitive and collaborative capabilities? Must intelligence always be in some individual thing - either a headbone or a box - or is intelligence a system property that is definable only in terms of the triple of humans-machines-contexts?.     

Secure Location Verification Using Radio Broadcast

Secure location verification is a recently stated problem that has a number of practical applications. The problem requires a wireless sensor network to confirm that a potentially malicious prover is located in a designated area. The original solution to the problem, as well as solutions to related problems, exploits the difference between propagation speeds of radio and sound waves to estimate the position of the prover. In this paper, we propose a solution that leverages the broadcast nature of the radio signal emitted by the prover and the distributed topology of the network. The idea is to separate the functions of the sensors. Some sensors are placed such that they receive the signal from the prover if it is inside the protected area. The others are positioned so that they can only receive the signal from the prover outside the area. Hence, the latter sensors reject the prover if they hear its signal. Our solution is versatile and it deals with provers using either omni-directional or directional propagation of radio signals without requiring any special hardware besides a radio transceiver. We estimate the bounds on the number of sensors required to protect the areas of various shapes and extend our solution to handle complex radio signal propagation, optimize sensor placement, and operate without precise topology information     

Lateral field excited Y-cut langasite bulk acoustic wave sensor

Previous studies have shown that lateral field excited (LFE) devices on AT-cut quartz are sensitive to liquid electrical property changes. AT-cut quartz LFE devices have low piezoelectric coupling factors. To further improve electrical sensitivities of LFE sensors, it is necessary to study LFE sensors based on other piezoelectric materials with higher coupling factors. In this paper, LFE sensors on Y-cut langasite, which has twice the higher piezoelectric coupling factor of AT-cut quartz, are investigated. Several Y-cut langasite LFE sensors are designed, fabricated, and tested. The experimental results show that the devices are over 6 times more sensitive to liquid conductivity changes and about 2.5 times more sensitive to liquid permittivity changes compared to AT-cut quartz LFE devices. It was also found that the Y-cut langasite LFE devices are about 1.3 times more sensitive to changes in liquid acoustic viscosity compared to the AT-cut quartz LFE devices.     

基于弹性腔模型的下肢脉动信号仿真

脉搏波包含人体的重要生理信息,对下肢脉动信号进行仿真研究,有助于辅助临床诊断和疾病预测。根据电网络模型理论,将下肢各段动脉等效为串并联弹性腔,建立了下肢动脉仿真模型。通过matlab/simulink对该模型的脉搏波在不同动脉顺应性和外周阻力的条件下进行仿真分析,得到正常与病理状态下足背动脉脉搏波的仿真波形。结果显示,当血管顺应性减小时,收缩压升高,主波波峰前移,脉压差增大;外周阻力增大时,脉搏波上升支的幅度与斜率均增大,脉压差增大,仿真结果与实测基本吻合。该模型能较有效模拟血管不同生理参数下的脉搏波,对血管疾病的诊治和相关医疗仪器的开发具有一定应用价值。