A Linear Position Transducer Using a Magnet and Hall Effect Devices

Magnets and magnetic field sensing devices are often attractive in instrumentation because they are noncontacting, small, and independent of the media's dielectric constant. The nonlinearity of the magnetic field with distance is a problem, however. A circuit to remove this nonlinearity and also to reduce the effective temperature coefficient is described. The circuit is used in a clinical dental research laboratory to measure movements of the jaw.     

A Method of Measuring the Angular Coordinates for Objects Moving in a Group

A method is proposed for measuring the angular coordinates of objects moving in a group. It is based on the statistical characteristics of the complex reflection coefficients of a group and the errors of measuring the velocities of the members. Inverse antenna aperture synthesis is used to increase the angular resolution.Translated from Izmeritel’naya Tekhnika, No. 3, pp. 12–18, March, 2005.     

光电摆角测量系统中CCD信号检测与处理电路设计

本文介绍了在光电摆角测量系统中,采用多片CCD同步采样实现物体空间摆角实时测量的方法。给出了CCD工作参数和输出信号处理电路的设计,讨论了工程中的有关问题。     

一种利用激光及热电器件的实时测温系统的测温精度

基于Kirchhoff定律，利用半导体激光器及钽酸锂热释电探测器设计了一种实用化的实时测温系统。从反射辐射对该测温系统测温精度的影响出发，讨论了水冷遮蔽板的相对尺寸(即H/R之值)与测温不确定度的关系，并确定了H/R之值；从波长对该测温系统测温精度的影响出发，并结合系统的测温灵敏度、探测器的温度分辨率及大气的透射窗口和温度的标准差等的研究结果，确定了系统的工作波长；总结了影响该实时测温系统测温不确定度的5种原因，结合光路中的外界干扰对该测温系统测温精度的影响，对该测温系统的测温精度及系统的测温不确定度进行了简要的分析。实验表明，在400-1200℃测温范围内，系统的测温不确定度优于0．3％。     

Measuring Technology and Pricing Differences in the Digital Still Camera Industry Using Improved Hedonic Price Estimation

In this paper we present an improved hedonic price regression for cases in which many implemented technological characteristics are to be included into a set of explanatory variables. This approach modifies Massy’s (1965) principal components regression in which original dummy explanatory variables corresponding to the characteristics are transformed into principal components. The selected subset which we obtained from the principal components regression was further orthogonally rotated by Kaiser’s (1957) varirnax criterion in order to reconstruct explanatory variables with a simple structure for the final hedonic regression, resulting in a more straightforward understanding of hedonic regression in the case of many explanatory variables. This approach is applied in order to compare different pricing strategies in the digital still camera industry, where the products contain 35 different technical attributes. The pricing strategies were measured using relative errors: differences between log actual prices and log quality-adjusted prices were identified using hedonic regression. The result shows that those companies, which have priced their products cheaper than the value of contained technologies, or than the prices of competitors, seem to have gained a larger market share.

     

Output Feedback Sliding Mode Control for a Linear Focusing Actuator in Digital Video Cameras

The output feedback sliding mode control offers an effective positioning method by robustness to parameter variation and disturbance rejection. This paper presents the output feedback sliding mode control based on a position estimation algorithm written in the microprocessor for use in the focusing control system of a digital video camera to achieve fast focusing response and accurate positioning despite vibration and friction of the movable part of the linear focusing actuator. The focusing performance by utilizing the output feedback sliding mode control includes a 60-ms setting time and 7-m steady-state error, respectively, which are only half and one-third of those in proportional-integral-derivative control when the movable part of the linear focusing actuator moves at a 5-mm stroke.     

Perturbation Bounds and Condition Numbers for a Complex Indefinite Linear Algebraic System

We consider perturbation bounds and condition numbers for a complex indefinite linear algebraic system, which is of interest in science and engineering. Some existing results are improved, and illustrative numerical examples are provided.     

Automatic System for Measuring and Controlling the Length of a Moving Product in Industries

This paper describes the design and development of a very simple low-cost online system for measuring the length of moving billets in the steel industry. Few photosensors, digital logic gates, and light-emitting diodes are used to track and display the wide variation in billet length. Not a single amplifier or comparator is used in photosensor circuit. The comparative study shows its superiority over other costly dimension-measuring systems, viz., shaft encoder, laser Doppler meter, and charge-coupled-device camera. Before, an operator had a risk of an accident while crossing the hot-cobble-prone area for measuring the billet length. However, today, the length of each billet is displayed in a pulpit, thereby increasing the safety. The measuring error in the billet length, ranging from +100 to -100 mm, is reduced to +50 mm. The fluctuation in linear velocity of an incoming billet to a flying shear causes wide variation in its cut lengths. To overcome this severe problem, the speed of the flying shear is adjusted during the tail end of each billet. The benefit of the system is in the tune of Rs 49.5 times 10⁶ (approximately U.S. $1.26 times 10⁶) per annum, whereas the payback period is less than 15 days. Apart from the different steel products like the slab, bloom, and rail, the developed system is also useful in the dimensional measurement of the products in nonferrous industries.     

Correction of the Spurious Strains and Displacements Caused by Out of Plane Movements in Digital Image Correlation (DIC) with a Single Camera

Digital image correlation (DIC) is a powerful experimental technique capable to measure the displacement field of a wide region through images. Also it’s scalable and can be applied to large structures, calculating the full strain field of a certain region. This potentiality is restricted by the spurious movements that insert noise in the measurements, reducing considerably the accuracy of the method and its applicability. This paper presents an algorithm capable to remove the effect of those spurious movements from a dataset, enhancing the accuracy of the technique. This is essential for the applicability of DIC to large structures where the spurious movement can’t be prevented and the deformations are very small due to the stiffness of the structures.     

Procedure for Estimating Errors of Measuring the Parameters of Camshafts and Crankshafts Using a Plane Tappet

An analysis has been made of the monitoring parameters of camshafts (master cams) and of the permissible errors in measuring them. A list of errors is determined, mathematical models are developed for them and their permissible values are designated. Calculations carried out together with experimental checks of these measurement errors have revealed satisfactory agreement between the combined calculated and experimental error values.     

超导磁储能系统在舰船电力系统中的应用前景及其关键课题

现代舰船电力系统容量急剧增大，全电力舰船的实现、敏感负荷和新概念武器的引入使舰船电力系统面临着一系列挑战。介绍了超导磁储能系统（SMES）作为一种新型储能设备的应用研究进展，分析了SMES在舰船电力系统中的潜在应用，最后提出了舰船电力系统中应用SMES的关键课题。     

Devices with Whispering Gallery Mode Optical Resonators: Current State of Research and Prospects for their Application in Time and Frequency Metrology

Measurement Techniques - The development of highly stable, narrow-band laser sources and oscillators producing sets of equidistant narrow optical spectral lines (so-called optical frequency combs)...     

数字光电跟踪系统定位时的自激振荡及其抑制

由于某些非线性的影响,数字光电跟踪系统定位精度大大降低,因此相应的非线性补偿方法研究势在,必行.本文以数字化光电跟踪系统为研究对象,首先进行了电视跟踪定位时影响定位精度的等效间隙非线性分析,给出了两种主要非线性的理论表达式,即量化非线性和光电探测器滞后非线性,然后采用描述函数法对实测定位自激振荡进行了定量分析,最后确定了双极工作模式的PWM功率驱动器.在实际的数字化光电跟踪系统定位实验研究中,定位误差的最大峰-峰值小于22.23",表明双极PWM驱动器的零位振颤特性,对数字控制系统的自激振荡起到了很好的抑制作用.