Optimizing Electromagnetic Flowmeter Coils

Design principles are considered for optimal coils for electromagnetic flowmeters for general industrial use.     

Noncoaxial Inductance Calculations Without the Vector Potential for Axisymmetric Coils and Planar Coils

This paper presents an exact method for calculating the mutual inductance between a general axisymmetric coil and a second planar coil consisting of either a disk coil or a planar loop of essentially arbitrary shape. The approach is based directly on the magnetic field rather than the vector potential . The paper gives detailed results for two circular loops, a circular loop and an elliptic loop, and a circular loop and an annular disk coil. The method can be extended to cover the cases where all these loops and coils are extruded in the axial direction to give the corresponding solenoids. The method is also applicable to calculations for nuclear radiation detectors.     

Mutual Inductance and Force Calculations Between Coaxial Bitter Coils and Superconducting Coils with Rectangular Cross Section

Mutual inductance and force calculations between coaxial Bitter coils and superconducting coils with rectangular cross section in a hybrid magnet system using derived semi-analytical expressions based on two integrations were performed. The mutual inductance and force calculations are based on the assumption of the uniform current density distribution in superconducting coils. The current density distribution of a Bitter coil in radial direction, however, is inversely proportional to the radius of the Bitter coil. The influence of the current density redistribution caused by a cooling hole and an inhomogeneous temperature distribution of Bitter coil of a water-cooled magnet was not considered. The obtained expressions can be implemented by Simpson’s integration with FORTRAN programming. We confirm the validity of mutual inductance calculation by comparing it with a filament method, and give the accuracy of two methods. The mutual inductance values computed by two methods are in excellent agreement. The derived semi-analytical expressions of mutual inductance allow a low computational time compared with filament method to a specific accuracy. The force is derived by multiplying the currents of the two coils by their mutual inductance gradient.     

Chloride Pitting of Steam Generator Boiler Coils

In this case study, pitting observed on boiler coil samples were analyzed. Chloride pitting was confirmed by chlorides identified in energy-dispersive X-ray (EDX) spectra and maps. The pitting failure was caused by initial chloride fluxing of the oxide/scale layering, followed by a chloride concentrating mechanism. The observed pitting can be prevented by water treatment to eliminate the halide ions followed by boiler scale and deposition control treatment.     

Test Coils Made of Tl-1223 Tapes

Silver sheathed Tl-1223 tapes were prepared by a powder-in-tube process. The critical current density of short samples was 18 kA/cm² at 77 K. Longer tapes up to 1.2 m, prepared by sequential pressing, had a critical current density of 12 kA/cm². From these tapes we have wound two coils. A solenoid coil with 5 windings was made of 8 tapes with a total length of 4.5 m. At 77 K the critical current of the coil was 23 A in the self generated magnetic field (18 Gauss at the centre of the coil). Using an iron yoke the critical current remained at 22 A while the generated magnetic field increased to 120 Gauss. A pancake coil with 15 windings, made of 5 tapes with a total length of 5 m, generated a magnetic field of 149 Gauss at the critical current of 12 A. From measurements of the critical current density of our tapes in applied magnetic fields, we conclude that coils made of Tl-1223 tapes can be used to generate higher magnetic fields at 77 K.     

HT-7U纵场磁体的真空压力浸渍

主要通过模拟匝间流动试验、短样试验和长样试验等 ,探求低温超导托卡马克HT 7U中纵场磁体线圈的绝缘层真空压力浸渍的工艺参数 ,确定工艺流程 ,并以模型线圈试验的电性能和液氦温度下的力学性能来验证工艺参数及工艺流程的可靠性。     

Versatile Aerogels for Sensors

Aerogels are unique solid‐state materials composed of interconnected 3D solid networks and a large number of air‐filled pores. They extend the structural characteristics as well as physicochemical properties of nanoscale building blocks to macroscale, and integrate typical characteristics of aerogels, such as high porosity, large surface area, and low density, with specific properties of the various constituents. These features endow aerogels with high sensitivity, high selectivity, and fast response and recovery for sensing materials in sensors such as gas sensors, biosensors and strain and pressure sensors, among others. Considerable research efforts in recent years have been devoted to the development of aerogel‐based sensors and encouraging accomplishments have been achieved. Herein, groundbreaking advances in the preparation, classification, and physicochemical properties of aerogels and their sensing applications are presented. Moreover, the current challenges and some perspectives for the development of high‐performance aerogel‐based sensors are summarized.     

Inductance Calculations for Noncoaxial Coils Using Bessel Functions

A relatively simple and general method for calculating the mutual inductance and self-inductance of both coaxial and noncoaxial cylindrical coils is given. For combinations of cylindrical coils, thin solenoids, pancake coils, and simple circular loops, the mutual inductance can be reduced to a one-dimensional integral of closed form expressions involving Bessel and related functions. Coaxial and noncoaxial cases differ only by the presence of an extra Bessel factor J ₀(sp) in the noncoaxial integral, where p is the perpendicular distance separating the coil axes and s is the variable of integration. The method is related to a recently given noncoaxial generalization of Ruby's formula for a nuclear radiation source and detector system, the analogy being close but not exact. In many cases, the Bessel function integral for the inductance can be easily evaluated directly using Maple or Mathematica. In other cases, it is better to transform the integral to a more numerically friendly form. A general analytical solution is presented for the inductance of two circular loops which lie in the same plane     

武钢硅钢卷的电解脱脂实践

武钢硅钢总厂CA12连续退火机组的硅钢卷生产线电解脱脂工序未使用专用电解脱脂液,致使钢板质量达不到预期效果.为此,开发并引入了WDF-1型电解脱脂液,现场进行了脂脱应用试验.结果显示,在控制的条件下,硅钢卷表面质量达到A～A~+级,满足了生产要求.     

碳螺旋纤维的阻抗特性研究

利用化学气相沉积（CVD）法制备微米尺度的碳螺旋纤维, 通过设计的拉伸装置引导试样中的碳螺旋纤维沿拉伸方向有序排列, 使用光学显微镜观察其形貌及排列情况. 具体研究了定向排列碳螺旋纤维的交流阻抗特性, 结果表明：低频时碳螺旋纤维的阻抗和辐角保持不变, 表现为纯电阻行为, 但是高频时（f>10kHz）阻抗和辐角随交流频率升高而迅速减小; 并且碳螺旋纤维对其被拉伸状态很敏感, 阻抗值随拉伸长度增大而增大. 该研究对开发碳螺旋纤维在微电路和微纳米感应器技术中的应用有重要意义.     

一种包装卷材快速在线检测算法

目的提高包装卷材图像的检测速度与精度,以实现快速在线检测。方法预先对几副标准样本图像进行拼接,将得到拓展的样板图像作为动态模板的母版。检测过程中,首先计算待测图样中心区域经简化的图像几何矩,并在前述样板中的一段区间内搜寻最佳匹配位置。再以该位置为中心,在样板图像上划分出与待测图样相同大小的区域作为动态模板,最后利用图像差影法实现缺陷检测与识别。结果二阶简化几何矩能有效减少运算量,动态模板可显著提高卷材图像检测速度,以电子元器件包装卷材载料带为检测对象对所提出的方法进行了测试,在较高分辨率条件下检测速度不低于2 m/s。结论该算法可满足包装卷材快速在线检测需求,对提高相位不确定性图像检测速度有一定参考意义。     

Stability analysis of ITER Poloidal Field Coils conductors

The stability analysis [1] of the Poloidal Field Coils of the ITER Project, specially the PF5, PF3 and PF2 coils for scenario #2, normal mode has been performed using the Gandalf [2] code. The conductor stability is assessed in the most severe operating conditions, at the minimal temperature margin time of the 4th pulse. It consists in determining the maximal deposited energy (perturbation in mJ/cm³ of superconducting strands) which can be absorbed without runaway. This study is performed for three initial different designs: Cu–nonCu ratio of 2.3, 1.6 and 4.4 for PF5, and Cu–nonCu ratio of 2.3, 1.6 and 6.9 for PF3 and PF2. The results are presented as well as a discussion about the phenomena, important parameters and uncertainties. For each type of perturbation, the calculated stability limits are quite similar from one design to another. The low Cu–nonCu ratios do not show significant stability degradation compared to the original ITER design with high ratios.     

Investigation of Failed Coils from a Steam Boiler

This case study presents results of analysis of failed coil samples from a steam-generating boiler. Scanning electron microscope images suggest that the main cause of failure was overheating. Calcium carbonate and calcium phosphate scaling salts probably derived from the water hardness were identified from the energy-dispersive x-ray (EDX) map. The combination of iron oxide and scales was likely to have created an insulating effect resulting in overheating and eventual tube failure. Calcium carbonate and phosphate scales are easily removed by chemical and mechanical methods. However, approximately 9% of the debris consisted of calcium silicate, as identified from the EDX map. Silicate scales adhere strongly to the surface and are not easily removed by chemical and mechanical methods. From the result of this analysis, it was possible to provide the prior information required for satisfactory repair and maintenance of the failed boiler coils.     

多阶段活塞式磁流变阻尼器的电磁线圈研究

分析磁流变阻尼器采用多阶段活塞式结构的优点,系统地研究磁流变阻尼器的电磁线圈特性。基于有限元软件构建磁流变阻尼器的仿真模型,分析得出在并联的电磁线圈中通入方向相反的电流,可以最大程度地提高磁路利用率。调整磁路中有效长度的分布和改变活塞齿槽断面为梯形结构,可以改善磁通的分布,确保整个阻尼通道内部的磁感应强度分布的均匀性。     

近程光电视觉传感器感知物体空间信息的研究

本文论述了二种新型光电近程视觉传感器的工作原理、计算方法和系统构成。一种是由多个点光源和位置敏感器(PSD)构成的传感器,文中从误差分析、统计运算的角度出发推导出确定被测对象空间信息的算法;另一种是由多个点光源和单个探测元件构成的传感器,这种传感器通过对位相信息的测定来感知物体的三维信息。两种传感器都能得到被测点到传感器之间的距离信息及被测表面空间取向的信息。所论及的传感器可用于机器人对三维物表面轮廓的追踪运动以及提供物体形状的三维描述信息等方面。     

Vacuum technology applied to solid state chemical sensors, processing, characterization and applications

This chapter will review several solid state chemical sensors with focus on the importance of ultra high vacuum, UHV, for the development of this area. Examples of sensors will be given where processing of sensors and sensing layers as well as characterization of chemical sensors takes place in UHV as well as examples of sensors for operation in UHV. Applications of chemical sensors both already commercialized and still on the research level will be given. Sensor technologies will span from metal oxide sensors, field effect transistor sensors to surface plasmon resonance, SPR, sensors and microcalorimeters. Examples of new challenging novel sensor approaches like sensors based on indirect SPR sensing and ultra sensitive graphene-based sensors for NO₂ detection will also be given.     

Measurement of Parameters of Superconducting Coils with Bare Windings

Measurement Techniques - The article discusses the problem of determining electrical parameters of superconducting coils with bare windings. Procedures for measuring these parameters are described;...     

A Distributed Optical Fiber Chemical Sensor System

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