双光梳绝对距离测量实验研究

长度测量作为几何量测量关键共性基础技术之一,在科学研究、高端装备制造及空间探测等领域有着重要的应用。双光梳绝对测距技术充分发挥了光学频率梳的时域超短脉冲和频域高分辨特性,实现了高测量速率的绝对距离测量。目前双光梳测距存在测量范围小、测量精度低的问题,为解决此问题,提出了一种基于双光梳测距技术与相位测距技术相结合的方案,采用双光梳测距技术实现非模糊距离范围内长度的高精度测量,利用相位测距技术实现非模糊距离整数倍测量及指示功能,作为双光梳测距高精度测量的有效补充。搭建实验系统对该方案的可行性进行验证,结果表明在0~70 m的测量范围内,测量误差小于±5 μm。     

测量距离影响辐射温度计检定结果的实验研究

针对测量距离对辐射温度计检定结果的影响进行了实验研究，给出了几种所选择的常用的辐射温度计的实验数据和分析图表。确定了辐射温度计的最佳测量距离是在离开黑体辐射源靶面0.3~0.5 m范围内。     

基于米氏散射及夫朗和费衍射的FAM激光测粒仪

提出了综合运用夫朗和费衍射和米氏散射，即在大粒径范围内采用夫朗和费衍射理论，而在小粒径范围内采用米氏散射理论，来改善小粒径范围内的测量精度，保证激光测粒仪在整个粒径范围内的测量精度。     

基于全站仪和激光跟踪仪的长距离标定方法研究

针对超长距离位置参数的高精度标定需求,设计了一种采用激光跟踪仪与全站仪的联合测量方法,该方法可集成两个系统各自优势满足测量需求。通过建立不同等级的测量控制网,采用分级测量技术,为全程测量提供基准,控制测量误差。采用统一空间测量网络的分析方法,将测量设备联合起来,建立统一的测量坐标系。结果表明,该方法可高精度、高效率的对超长距离位置信息进行标定。     

影响红外测温的主要因素分析研究

红外测温在钢铁企业应用越来越广泛，成为钢企温度在线测量的关键设备。但在实际工作中，红外测温受到诸多因素影响，导致测温不准，影响产品质量控制。文章通过自主实验研究影响红外测温准确度最重要的发射率参数以及使用中安装距离等问题，综合确定几种钢材最佳发射率约为0.96(测温仪型号C316),使实验的几种钢种测量精度均能达到测量值的0.25%+1 K,并通过距离实验表明，即使在测试距离符合距离系数(D:S)的前提下，不同距离测量误差可能不同。本实验装置和方法可以为三钢不同的钢种或其它材料提供发射率测试，对测温仪发射率进行标定。     

基于米氏散射及夫朗和费衍射的FAM激光测粒仪

提出了综合动用夫朗和费衍射和米氏散射，即在大粒径范围内采用夫朗和费衍射理论，而在小粒径范围内采用米氏散射理论，来改善小粒径范围内的测量精度，保证激光测粒仪在整个粒径范围的测量精度。     

调频激光干涉绝对距离测量技术及其信号处理

最最的绝对距离测量方法是非相干飞行时间测量法。随后，在小数重合法的基础上，产生了多波长干波绝对距离测量技术。随着半导体激光器的发展，８０年代又出现了调频干涉绝对距离测量方法，并很快成为一种新的测长技术。本文在综述绝对距离技术及方法的基础上，着重介绍了调频激光干涉绝对距离测量技术的一些新发展及其几种不同的信号处理。     

CPU散热器换热特性的数值研究

对一种散热器结构，在风扇与散热器间距离不同和不同风速下的散热特性进行了数值模拟。采用ICEPAK软件进行计算，结果显示：风扇与散热器之间存在一个最优的距离，而在CPU工作温度范围内，风速对散热器的影响不是很大。采取数值模拟的方法对CPU散热器进行研究是实验方法的可靠补充，计算所得的结果有助于分析CPU散热器的换热过程，并可为电子设备的设计和改进提供参考。     

用于绝对距离测量的0．6328μm氦－氖激光外差干涉仪

提出了一种用于绝对距离测量的新型外差干涉仪，它采用０．６３２８μｍ双模氦－氖激光器，光外差干涉和电信号混频、比相技术，直接测量合成波小数级次。此法避免了该领域常用的外差干涉仪的不足和拍波干涉仪结构复杂的问题，而且测量精度高、抗干扰能力强、测量时间短，使绝对距离测量技术更具有实用性。     

数字水准仪测量编解码技术研究

针对传统的数字水准仪测量精度受到测量距离和视场的制约,固定的码元难以兼容远近测量的精度等问题,为进一步提高数字水准仪的测量精度,该文提出一种编解码方案,利用圆的各向同性性质,以圆形码代替传统条形码进行编制,并且采用面阵CCD获取二维编码图像,同时在远近不同距离采用不同进制编码,在解码粗测时应用最大相似匹配算法,精测时应用比例求解。对比实验证明,该编解码方法分辨率较高,测量更加准确,实现高精度、快速水准测量。测量范围为2~100 m,单点测量绝对误差小于±0.2 mm。     

Instrumentation for time-resolved measurement of ultrasoundvelocity deviation

An inexpensive digital data acquisition unit is described which has the capability to record ultrasound velocity variations up to 20 m/s in ultrasound velocity at rates up to 1000 readings per second. No calibration procedures are required. The intrinsic velocity resolution of the unit is less than 1 part in 10⁶; however, the short-term frequency instability of the phase-locked loop instrument used as a velocity sensor limits the overall resolution to 1 part in 10 ⁵     

Use of a droplet nucleation analyzer in the study of water freezing kinetics under the influence of ultrasound waves

In this report we present a new instrument (a droplet nucleation analyzer) to be used in the study of the influence of ultrasonic waves on the freezing of pure water. This influence can be of great interest in the cryopreservation of biological material. Two different types of experiments have been carried out. In the first set of experiments, ultrasound waves were used during the cooling process. In the second set, ultrasound was applied prior to the cooling process, trying to quantitatively reproduce some experiments in which the ice nucleation temperature of water was successfully decreased. A theoretical discussion of the results is also presented.     

A lens acoustic microscope with a two-dimensional ultrasound array

A lens acoustic microscope is proposed in which a two-dimensional high-frequency ultrasound array is used instead of a single converter. In this microscope, electronic scanning of the region of naturally occurring focus of the acoustic lens can be performed and the focus can be held electronically at different distances, including inside solid objects. It was demonstrated that the multielement microscope has potentially higher performance compared with a single-element scanning microscope and is not inferior in resolution power.     

超声波油位测量计的设计

介绍了超声波油位测量的原理、电路及测控程序。油位测量计以集成锁相环解码器LM567作为超声波检测元件,以89C2051单片机作为主控元件,可用干电池供电。用超声波测量油位具有非接触、可测低温介质、无机械运动部件、寿命长等优点;以LM567作为超声波检测元件降低了系统的价格,提高超声波捕捉能力;采用单片机控制超声发射与接收,并经温度补偿后计算出油位,使检测具有高智能性。对由于超声声速变化及LM567输出延时引起测量误差的原因作了详细的分析,并提出了提高调整波速精度及调整输出延时的措施。     

探讨高频超声检测乳腺肿块内不同钙化类型在诊断乳腺癌中的价值

目的:探讨高频超声检测乳腺肿块内不同钙化类型在诊断乳腺癌中的价值和重要性.方法:采用高频超声探头显像特征和内部回声等声像图对乳腺癌患者进行肿块病理结果分析.结果:手术后经过病理检查可知,高频超声诊断的符合率达到98％.其中肿块内不同钙化点类型对于鉴别良恶性诊断极为重要.结论:对于乳腺癌高频超声具有较好的诊断价值,利用高频超声检测乳腺肿块内不同钙化类型可以明显提高乳腺癌的诊断率,具有重要的临床应用价值.     

An Instrument for Measuring Deformations in Large Structures

An instrument that has been developed for measuring the deformations in shape that result from the movement of a radio telescope reflector is described. A radar technique is used to measure distances from near the focal point of the reflector to selected points on the reflector surface. The short term accuracy of the instrument is ±0.003 in) and when used on the 140-ft telescope in Green Bank, W.Va., good agreement was found between calculated and measured deformations.     

大尺寸蜗轮齿距累积误差的检测及数据处理

介绍了１种作为工厂机床检修中大尺寸蜗轮距累积误差的检测装置和检测方法，以及用计算机快速准确地进行数据处理。     

Exposimetry of low-frequency ultrasonic dental devices

In low-frequency (20-40-kHz) ultrasonic devices used in dentistry the ultrasound is conducted to the tooth either via a metal waveguide oscillating predominantly in its longitudinal mode or via metal files or reamers driven to vibrate transversely or longitudinally at the same frequency as the transducer. All of these arrangements have unique coupling problems, so that it is difficult to estimate how much ultrasonic energy enters the tooth and therefore what its biological effects might be. As a first step, it is proposed that the maximum displacement amplitudes of that part of the instrument that contacts the tooth be measured to obtain some estimate of the ;acoustic output' of each instrument. These measurements are necessary because of the wide variations in the efficiency of the transduction process between different probe designs (i.e., the interchangeable inserts) powered by the same handpiece, or by the same insert powered by different but compatible generators from the same manufacturer. It is suggested that this information will also improve the ability of clinical users of these devices to reproduce each other's techniques and procedures, and thus make it possible to reduce the number of contradictory claims regarding their clinical efficiency.     

Singular spectrum analysis applied to backscattered ultrasound signals from in vitro human cancellous bone specimens

Mean scatterer spacing (MSS) holds particular promise for the detection of changes in quasiperiodic tissue microstructures such as may occur during development of disease in the liver, spleen, or bones. Many techniques that may be applied for MSS estimation (temporal and spectral autocorrelation, power spectrum and cepstrum, higher order statistics, and quadratic transformation) characterize signals that contain a mixture of periodic and nonperiodic contributions. In contrast, singular spectrum analysis (SSA), a method usually applied in nonlinear dynamics, first identifies components of signals corresponding to periodic structures and, second, identifies dominant periodicity. Thus, SSA may better separate periodic structures from nonperiodic structures and noise. Using an ultrasound echo simulation model, we previously demonstrated SSA's potential to identify MSS of structures in quasiperiodic scattering media. The current work aims to observe the behavior of MSS estimation by SSA using ultrasound measurements in phantom materials (two parallel, nylon-line phantoms and four foam phantoms of different densities). The SSA was able to estimate not only the nylon-line distances but also nylon-line thickness. The method also was sensitive to the average pore-size differences of the four sponges. The algorithms then were applied to characterize human cancellous bone microarchitectures. Using 1-MHz center-frequency, radio-frequency ultrasound signals, MSS was measured in 24 in vitro bone samples and ranged from 1.0 to 1.7 mm. The SSA MSS estimates correlate significantly to MSS measured independently from synchrotron microtomography, r2 = 0.68. Thus, application of SSA to backscattered ultrasound signals seems to be useful for providing information linked to tissue microarchitecture that is not evident from clinical images.