TCM5电子罗盘在三维流速计中的应用

随着电子技术的进步,基于磁通门测量原理的小型三维电子罗盘广泛的应用于海洋仪器、水下机器人、小型飞行器等仪器和设备的导航和定向系统中,和陀螺仪相比,具有体积小、功耗低、零漂小的特点。通过在三维海流计中应用PNI公司的TCM5型电子罗盘实现流速的三维矢量测量。通过实验验证和分析,证明该电子罗盘的具有较高测量精度,抗硬磁场干扰能力强的特性。     

便携式电子计价秤的电路设计

本文提出了一种便携式电子计价秤的电路设计方法，通过普通计算器的接口电路，可使计价秤的主体功能单元直接利用计算器实现，从而可降低成本．该设计亦适用于其它仪器电路中．     

油井高压直管泄漏原因

某油井的高压直管在试压作业后进行酸洗作业时发生泄漏。通过化学成分分析、壁厚测量、硬度测试、力学性能测试、金相检验、扫描电镜及能谱分析等方法,对该高压直管泄漏的原因进行了分析。结果表明:该高压直管内表面存在折叠缺陷是造成泄漏的主要原因;多次酸洗作业使高压直管的壁厚因腐蚀而明显减薄,承压能力降低,是造成泄漏的次要原因,两者共同作用导致高压直管最终泄漏。     

ICS-17A型电子皮带秤在电厂入炉煤计量系统中的应用

本文介绍了ICS-17A型电子皮带秤的组成。该系统经过科学的计算,较精确地计算出各原煤仓的进煤量,可以对瞬时流量和累计重量进行实时监控,实现了以一台电子秤来计量多个原煤仓的进煤量。     

一种通道可扩展的堆叠式数据采集系统设计

针对武器装备测试过程中对振动、冲击、压力等多路信号的采集需求,设计一种通道可任意扩展的堆叠式微型数据采集系统。采用FPGA作为核心控制器,将系统功能划分为基础控制模块和数据采集模块,通过在基础模块上叠加数据采集模块的方法实现对采集通道数量的扩展。数据采集模块内置程控信号调理电路和采集电路,采集数据编帧后通过M-LVDS多点互联总线传输到控制模块中。系统由控制模块管理采集模块,并通过USB电缆将数据上传到计算机进行波形分析。经测试,该仪器能按需求灵活扩展通道数量,单通道采样率最高可达500kS/s,具有微型化、抗冲击等突出特点。     

电子全息高分辨率三维数值重现

对电子全息图进行计算机三维数值重现时,由于样品各层电子衍射的干扰,影响了纵向分辨率的提高。本文提出一种基于多能量电子全息图数值重现像叠加原理的新方法,可以提高电子全息数值重现纵向分辨率,从而实现真正的三维数值重现的含义。还通过计算机模拟研究的手段对该原理和方法的有效性进行了验证,得出了有价值的结果。     

基于VXI总线仪器的电路板综合测试系统

本文论述的是一个基于ＶＸＩ总线仪器的先进的电路印制板（ＰＣＢ）自动测试与故障诊断系统，与其它夹具式电路板在线测试仪所不同之处在于它既可对被测电路板进行整体功能测试，又可对单个器件进行在线测试，在对单个器件进行在线测试时无需对被测器件施加任何激励或设保护点，实践证明该系统的测试方法先进，故障定位准确。     

在S3C2440AL扩展CAN总线接口电路的设计

现场总线技术和嵌入式技术的发展对现代制造业产生了深远的影响。本文介绍在微处理器S3C2440AL上通过SPI总线扩展CAN总线接口电路的方法,并介绍了硬件和软件设计方法,通过实验验证设计的可行性。该研究成果对实现现代制造业的网络化有积极地推动作用。     

医学超声内镜中同步编码激励技术的设计与实现

为了提高医学超声内镜系统中的探测深度、分辨率及成像质量,在超声内镜成像系统中采用编码激励技术,首次将普遍用于开关电源电路设计中的"半桥"电路引入超声内镜编码激励电路.在只有正电压电源供电的情况下产生正负高压激励脉冲,利用电机转动的编码信号,设计了基于CPLD的同步编码激励电路,在保证与超声内镜主机FPGA同步的基础上,简化了超声内镜系统内信号的传递.实验中,同步编码激励电路发射的编码激励信号与理论码型一致,通过人体体模实验,获得的回波波形幅度达1.0Vpp,噪声20×10-3VPP~30×10-3Vpp,信噪比高达34 dB,波形与仿真结果一致.     

基于VXI总线数字多用表模块硬件设计

VXI总线数字多用表（DMM）模块是组建实用的VXI总线自动测试系统的最常用的通用模块仪器之一。本文讲述了基于VXI总线高精度数字多用表的硬件电路设计。电路设计包含模拟信号调理电路，MD转换电路，数据传输电路和VXI总线接IEI电路。充分结合了VXI消息器基接IEI的优点，实现了高速数据采集、数据的快速和模块灵活控制三者的结合。并就设计过程存在的问题进行讨论。     

声波测井压电换能器多频点阻抗匹配技术研究

针对声波测井压电换能器的多频点阻抗匹配技术展开研究,首先采用多模态等效电路精确描述了换能器的导纳特性;然后通过分析多模态阻抗匹配理论,设计电感-电容复合阻抗匹配网络,并结合换能器等效电路进行参数优化和电路仿真。实验表明,相比于换能器没有阻抗匹配的测试结果,该阻抗匹配技术可大幅提高换能器在谐振频率附近多个频率处的有功功率,频带内的有功功率平均提高了30倍,从而改善换能器的激励带宽和激励效率,提高测井仪器的适应性、探测深度和分辨率。     

多极声源在裸眼井外的纵横波辐射特性

声波远探测方法已逐渐成为石油测井的一门重要应用技术,声源向井外地层中的辐射特性是远探测声场的主控因数。推导了单极、偶极和四极子声源的远场位移渐近解与辐射指向性公式,模拟分析了低频和常规测井频率下多极子声源在井外地层中的辐射图样,优选出不同声源辐射到地层中的优势波类型,并对比了不同频率下优势波指向性的变化规律。结果表明:单极辐射P波和偶极辐射SH横波在各自的辐射声场中占据了主导地位,它们对应的最佳激发频段分别在10 k Hz和4 k Hz左右,而在四极子声源的辐射声场中,P波和SH横波的指向性相近,均优于SV横波,且两者在7 k Hz左右达到最佳,为多极子声波远探测技术的应用提供了理论支持。     

An electroacoustic method for measuring the intensity of high-powermicrowave pulses

A microwave electric field intensity meter for single high-power radiowave pulses is described. A surface acoustic wave (SAW) dielectric acoustic line is used which has nonlinear electroacoustic properties and is comprised of two transducers. The first (nonlinear) transducer is affected by a microwave electric field and provides the SAW excitation due to nonlinear effects. A delayed SAW signal, carrying information about the electric field strength, is received by a linear interdigital transducer     

随钻声波测井仪控制采集电路的优化设计与实现

从随钻声波测井的实际需要出发,针对作业环境、设计空间、传输速率以及信号特点等方面进行了需求分析,提出了一种适用于随钻声波测井仪采集控制系统的优化设计。该系统以数字信号处理器(Digital Signal Processor,DSP)为控制核心,以现场可编程门阵列(Field-Programmable Gate Array,FPGA)作为信号传输以及接口转换的桥梁,与外围功能芯片包括模拟与数字转换器、与非门闪存芯片(NAND FLASH)等进行通讯,完成相应的信号采集、控制、存储等功能。所设计的采集控制电路不但充分发挥了DSP数据处理功能强的优势,而且将FPGA控制时序精准、接口丰富的特点表现出来。最后经过上位机软件测试,得到了较好的效果,为实际随钻声波测井控制采集电路设计及实现提供了技术参考。     

声波测井仪井下数字滤波器设计与实现

交叉偶极阵列声波测井仪是目前主流的先进声波测井设备之一,但在测井过程中难免存在噪声干扰,对测井质量造成不利影响。在利用Matlab对大量实测信号进行时频分析的基础上,针对噪声的规律和特点,提出时域滤波和频域滤波相结合的方案。时域上采取限幅平均滤波法,频域上选择具有线性相位的FIR滤波器。利用Matlab滤波器设计与分析工具箱获取滤波器系数,借助DSP软件开发环境CCS,用汇编语言设计了基于DSP的井下实时FIR数字滤波器。现场测井试验表明,该滤波器对测井信号中存在的噪声具有良好的抑制作用,同时满足测井系统的实时性要求。     

Two-dimensional manipulation of micro particles by acoustic radiation pressure in a heptagon cell

An acoustic particle manipulation system is presented, using a flexible printed circuit board formed into a regular heptagon. It is operated at 4 MHz and has a side dimension of 10 mm. The heptagonal geometry was selected for its asymmetry, which tends to reduce standing wave behavior. This leads to the possibility of having fine control over the acoustic field by varying the output phases of the transducer elements. Configurations with two and three active transducers are demonstrated experimentally. It is shown that with two transducers, the particles align along straight lines, the position of which can be moved by varying the relative excitation phases of the two transducers. With three active transducers, hexagonal-shaped patterns are obtained that can also be moved, again according to the phase of the excitation signals. Huygens' principle-based simulations were used to investigate the resultant pressure distributions. Good agreement was achieved between these simulations and both Schlieren imaging and particle manipulation observations.     

A magnetic sense amplifier

A new mode of operation of a balanced magnetic circuit is described. With this new mode of operation, which utilizes pulsed current excitation, the detection sensitivity of the magnetic modulator circuit is combined with the high-speed amplification of parametric buildup. This combination permits detection of low-level current pulses applied during a specified time interval of the excitation sequence and provides subsequent amplification of the detected signal. Matched square-loop toroids are used. Signal currents which are a small fraction of the coercive MMF have been successfully detected. The limit of detection sensitivity depends upon the matching of the two cores. The parametric buildup has been made to occur for pump cycle times of 30 μs to 120 μs, depending upon the magnetic material used. The signal information is retained when the pulse excitation sequence is interrupted during buildup because the signal information is stored as a flux unbalance in the two cores during the time interval between excitation pulses. The use of this circuit mode as a sense amplifier for the detection and amplification of sense winding currents in magnetic memories is suggested.     

Three-dimensional multiexcitation magnetoacoustic tomography with magnetic induction

Magnetoacoustic tomography with magnetic induction (MAT-MI) is a hybrid imaging modality proposed to image electrical conductivity contrast of biological tissue with high spatial resolution. This modality combines magnetic excitations with ultrasound detection through the Lorentz force based coupling mechanism. However, previous studies have shown that MAT-MI method with single type of magnetic excitation can only reconstruct the conductivity boundaries of a sample. In order to achieve more complete conductivity contrast reconstruction, we proposed a multiexcitation MAT-MI approach. In this approach, multiple magnetic excitations using different coil configurations are applied to the object sequentially and ultrasonic signals corresponding to each excitation are collected for conductivity image reconstruction. In this study, we validate the new multiexcitation MAT-MI method for three-dimensional (3D) conductivity imaging through both computer simulations and phantom experiments. 3D volume data are obtained by utilizing acoustic focusing and cylindrical scanning under each magnetic excitation. It is shown in our simulation and experiment results that with a common ultrasound probe that has limited bandwidth we are able to correctly reconstruct the 3D relative conductivity contrast of the imaging object. As compared to those conductivity boundary images generated by previous single-excitation MAT-MI, the new multiexcitation MAT-MI method provides more complete conductivity contrast reconstruction, and therefore, more valuable information in possible clinical and research applications.     

Metal nanoparticle ensembles: tunable laser pulses distinguish monomer from dimer vibrations

Resonant interaction of laser pulses with plasmons is used to identify vibrations associated with isolated spheres and pairs of contacting spheres in a system of gold nanoparticles. The optical pulses generate coherent mechanical oscillations of both monomers and dimers in the 5-150 GHz range, the amplitudes of which exhibit a strong enhancement when the laser central wavelength is tuned to resonate with the corresponding plasmon. Because of the resonant selection in the excitation process, the widths of the acoustic modes are significantly smaller than broadening caused by the spread in radii in the ensemble.     

随钻声波测井仪高效电源设计

为了保障随钻声波测井仪在锂电池供电条件下能够长时间工作,需要采用高效电源设计。根据随钻声波电子系统的供电特点、电池性能和工程应用要求,设计了随钻声波测井仪电源控制电路。随钻声波测井仪采用间歇工作方式,低功耗微处理器根据随钻测量系统的指令控制电源开关,对仪器主电子系统的电源进行控制。仿真和实验结果表明,电源控制电路功耗低、抗干扰能力强、可靠性高,能够满足随钻声波测井仪的工作要求。