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 Six-Dimensional Magnetic Localization Algorithm for a Rectangular Magnet Objective Based on a Particle Swarm Optimizer

To build a wireless capsule endoscope with active external guidance for controllable and interactive diagnosis on the gastrointestinal tract, it is necessary to track the capsule's 3-D position and 3-D orientation. An approach to tracking is to enclose a small rectangular permanent magnet in the capsule. The magnetic field produced around the body by the rectangular magnet can be detected by magnetic sensors outside the patient's body. With these detected magnetic sensor data, the 3-D localization and 3-D orientation parameters can be computed by an appropriate algorithm based on the mathematical model of the rectangular magnet's magnetic field. We tried several nonlinear optimization algorithms, and simulation experiments show that the particle swarm optimization algorithm can work effectively with good accuracy when the magnet moves within a predetermined range.      

Design of Long-Period Fiber Grating Refractometric Sensors With Linear Response by a Genetic Algorithm

A new method for the design of optical fiber refractometric sensors based on nonuniform long-period fiber gratings (LPFGs) is presented. A specialized genetic algorithm (GA) with properly designed operators is a fundamental element of this method and performs the theoretical synthesis of a necessary nonuniform LPFG period profile. Such a profile yields a linear response of the sensor to the refractive index of the external medium. A distinctive feature of the designed LPFG is a linear gradient of the core and cladding refractive index along the grating length. Also, a new mathematical model of nonuniform LPFGs is presented, the model permits to take into account the effect of some LPFG sections of a lower and others of a higher cladding refractive index than that of the external medium. The application of both the design method and the mathematical model is illustrated with a numerical example.     

Novel Magnetic Photonic Crystal Structures for Magnetic Field Sensors and Visualizers

Optimized one-dimensional (1-D) magnetophotonic crystals greatly increase the sensitivity of magnetooptical sensors, which are widely used in magnetooptical imaging to observe the magnetic domain patterns in magnetic materials, to observe the vortex states in superconductors, to detect small bits in magnetooptical recording media, to visualize defects in ferromagnetic objects, and to measure the value and spatial distribution of stray magnetic fields. This paper examines the properties of such devices operating in the optimized reflection (doubled Faraday rotation) mode and discusses the use of 1-D magnetophotonic crystals as sensors.     

Initial Position Estimation for Closed-Loop Linear Hybrid Stepping Motor Drives Using DC Excitation

This paper presents a simple and economical way to accurately estimate an initial position for linear hybrid stepping motor (LHSM) drives by utilizing dc excitation. In order to detect an absolute position of the mover, two preliminary tests are carried out under two different dc conditions: single-phase and two-phase dc excitation. The proposed algorithm has been successfully applied to a practical system with a rated initial load and stiction without causing any mechanical damage. The proposed scheme is not affected by the harmonic force ripple of the LHSM and its benefits are much more significant for multi-axis systems. The paper presents experimental results to prove the effectiveness of the scheme.     

用多齿分度台检测小度盘的刻线位置误差

本文介绍了用多齿分度台检测小度盘的刻线位置误差及其数据处理方法。对检测结果的可靠性进行了分析与估算。     

线性乘性规划的全局优化算法

本文研究线性乘性规划问题(LMP)的全局最优化算法,线性乘性规划问题在生产运输、工厂布局设计、超大规模集成电路芯片设计等方面有重要的应用。首先将LMP问题转化为等价规划问题(P1),然后利用参数线性化方法在相应的超矩形上求得问题(P1)的目标函数和约束函数线性下界估计,并提出了一个求线性乘性规划全局解的确定性全局优化算法,并证明了算法的收敛性。数值实验表明提出的方法是可行和有效的。     

二维曲线自动跟踪测量的一种新算法

商品坐标测量机软件的二维曲线自动跟踪测量功能在应用中经常出现跟踪失败和采样信息不充分等问题。针对这些问题 ,提出了一种基于三次样条曲线基本性质的二维曲线自动跟踪测量算法 ,采用圆弧外插方法估算后续测量点并利用回溯方法提高跟踪测量的可靠性。这种方法还可以推广应用于曲面的扫描测量和一些特殊的三维曲线的自动跟踪测量中。文中还对测头补偿问题进行了分析 ,提出了相应的解决方法。     

一种运动目标位置合成的快速算法

研究用经纬仪测定运动目标位置过程中的有关问题。为保证算法的实时性,采用直线插值方法。根据非整数倍周期时的偏差量,给出偏差量在整数倍周期时的带有延时作为参数的表示式。利用这一表示式,在目标作匀加速运动的前提下提出了延时的辨识方法,从而解决了目标位置合成中的难题。     

Coil and Magnet Design for Nuclear Magnetic Resonance in Inhomogeneous Field

High-resolution nuclear magnetic resonance (NMR) spectrometry is possible in nonhomogeneous magnetic fields-such as those in portable equipment-if the static and the radio-frequency (RF) magnetic fields are perpendicular and correlated in the measurement volume. From the easy-axis rotation theorem and the Amperian currents model, it is possible to exactly match two magnetic fields in two-dimensional systems. We derive a basic probe element that fulfills these conditions. Then we present a portable NMR probe design. The static and RF magnetic fields of the probe are matched on a large volume     

传感器方法检定压力变送器能力的演算

压力变送器的检定一般是以活塞压力计为标准建标,但是现场检定／校准中使用数字压力计更为方便,如果使用此方法会带来不同量程、精度等级的数字压力计传感器的检定／校准能力的问题,本文就将此问题做一个粗略的演算,使现场检定／校准工作更为合理有效。     

A New Algorithm for Extreme Vertices Designs for Linear Mixture Models

A new algorithm for obtaining extreme vertices designs for linear mixture models is proposed. The algorithm generally produces designs that are as efficient as those produced by the XVERT algorithm of Snee and Marquardt (1974) but with less computational effort. Use of the algorithm in obtaining designs is also described.     

A Model for Magnetic Ordering in Quasi-Low-Dimensional Magnet CsDy(MoO4)2

For quasi-low-dimensional magnet CsDy(MoO4)2 a model for the equilibrium spin arrangement in the magnetically ordered state is proposed on the ground of the symmetry analysis of neutron diffraction data. Low crystal symmetry of monoclinic syngony results in several spatial orientations of strongly anisotropic magnetic centers in the crystal and leads to the form of an order parameter more complicated than simply ferromagnetic or antiferromagnetic one. Measurements of magnetization along crystal axes have been performed both above and below the Neel point.     

Saturation Magnetic Induction Prediction for Amorphous Magnetic Alloys by Using Support Vector Regression

This paper illustrates an application of support vector regression (SVR) approach in forecasting the saturation magnetic induction (B _s ) of amorphous magnetic alloys. SVR was trained and tested with an experimental data set comprised of five input variables, comprising the average number of valence electrons of amorphous magnetic alloys, mixed entropy, ratio of radii, difference of electron density, and difference of work function. The prediction performance of SVR was compared with that of artificial neural networks’ (ANN) model. The results demonstrate that the prediction ability of SVR is superior to that of ANN. This investigation indicates that SVR-based modeling is a practically useful tool in prediction of the saturation magnetic induction of amorphous alloys. This study provides a novel methodology to foresee the saturation magnetic induction in sintering/development of novel amorphous magnetic alloys possessing high saturation magnetic induction.     

New Noncontacting Inductive Analog Proximity and Inductive Linear Displacement Sensors for Industrial Automation

Noncontacting inductive sensors are applicable on a large scale for position detection or travel measurement in industrial applications. Reasons for such broad acceptance in many sectors of industry are noncontact and wear-free sensing of the target (any metal object), reliability and robustness, resistance to fouling, water tightness and compact size. The present work is intended to be a systematic, complete, and consistent presentation of the technological innovations, recent implementations and current trends regarding the analog distance and travel sensing offered by noncontacting inductive sensors for industrial applications. It starts with the fundamentals of inductive sensing and presents the physical basics gained by modern analytic and simulation methods, as well as high-level integrated circuits for inductive sensors. The following sections deal with present-day inductive analog proximity sensors and with the distinctive technological innovation offered by the new inductive linear displacement sensors and with miniaturization results achieved through consistent integration.     

外测弹道速度与加速度的解算方法研究

在飞行器外测弹道参数解算时,常利用由位置参数中心微分平滑的方法获取弹道速度与加速度参数,但微分得到的速度／力口速度数据跳动很大,不利于与内测参数进行精度比对．本文研究了样条函数和迭次下采样方法在弹道拟合和微分求速中的应用,实际数据处理结果表明,样条函数用于外测数据拟合和微分求速可以获得更高的精度．     

遗传算法支持下的孔组复合位置度误差评判

在孔组复合位置度误差评判过程中,用传统的数值优化方法一般难以找到符合最小条件判别准则的几何图框理想位置,尤其当位置度公差遵守最大实体要求且被测要素尚未达到最小实体尺寸时,被判为不合格的零件还有被修复的可能。针对上述问题,可利用自适应遗传算法全局搜索几何图框最佳位置,并在搜索过程中同时考虑遵守最大实体要求时的误差补偿因素的影响。此外,针对不合格零件进行的可修复性判别和修正量的计算,进一步降低了零件误废率。