General series expression of eddy-current impedance for coil placed above multi-layer plate conductor

This paper presents a closed expression of the layered-plate factor used to calculate the coil eddy-current impedance over the multi-layer plate conductor. By using this expression, the general series of eddy-current impedance can be written directly without solving the undetermined constant equations. The series expression is easy to use for theoretical analysis and programming. Experimental results show that calculated values and measured values are in agreement. As an application, when the bottom layer of the layered plate is a non-ferromagnetic thin layer conductor and the product of the thickness and conductivity of the layer remains unchanged, using the layered-plate factor expression proposed in this paper, it can be theoretically predicted that the eddy-current impedance curves corresponding to different thin layer thickness values will coincide.

Microstructure and impact mechanical properties of multi-layer and multi-pass TIG welded joints of Al-Zn-Mg alloy plates

The microstructure and mechanical properties of multi-layer multi-pass TIG welded joints of Al-Zn-Mg alloy plates were studied.The phase constituent and microstructure of different regions of the welded joints were characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD),transmission electron microscopy(TEM)and energy disperse spectrum(EDS),while the mechanical properties were evaluated according to the impact test.A dispersively distributed spherical and needle-likeη(MgZn2)phase was obtained in the welding seam.The phase composition of the heat-affected zone(HAZ)wasα(Al)+η(MgZn2)+Al6Mn,and there were a large number of dispersively precipitated nanoscale particles.The welded joint zone had the highest impact toughness as compared with the other parts of the joint.The MgZn2 phase in the weld zone contributed to the improved toughness of the joint.Al2 MgCu phase in HAZ was proven to act as a crack source during fracture.

Damage of multi-layer spaced metallic target plates impacted by radial layered PELE

Three different kinds of PELE(the penetrator with lateral efficiency) were launched by ballistic artillery to impact the multi-layer spaced metal target plates.The lmpact velocities of the projectiles were measured by the velocity measuring system.The damage degree and process of each laye r of target plate impacted by the three kinds of projectiles were analyzed.The experimental results show that all the three kinds of projectiles have the effect of expanding holes on the multi-layer spaced metal target plates.For the normal structure PELE(without layered) with tungsten alloy jacket and the radial layered PELE with tungsten alloy jacket,the diameters of holes on the seco nd layer of plates are 3.36 times and 3.76 times of the diameter of the projectile,re spectively.For radial layered PELE with W/Zr-based amorphous composite jacket,due to the large number of tungsten wires dispersed after the impact,the diameter of the holes on the four-layer spaced plates can reach 2.4 times,3.04 times,5.36 times and 2.68 times of the diameter of the projectile.Besides,the normal structure PELE with tungsten alloy jacket and the radial layered PELE whit tungsten alloy jacket formed a large number of fragments impact marks on the third target plate.Although the number of fragments penetrating the third target plate is not as large as that of the normal structure PELE,the area of dispersion of fragments impact craters on the third target plate is larger by the radial layered PELE.The radial layered PELE with W/Zr-based amorphous composite jacket released a lot of heat energy due to the impact of the matrix material,and formed a large area of ablation marks on the last three target plates.

Limit analysis of ultimate uplift capacity and failure mechanism ofshallow plate anchors in multi-layered soils

Considering the fact that in some complex cases,plate anchors are buried in multi-layered geotechnical materials,the ultimate dynamic analysis was performed to investigate the uplift capacity and failure mechanism of shallow strips and circular plate anchors in multi-layered soils.The nonlinear strength criterion and non-associated flow rule of geotechnical materials were introduced to investigate the influence of nonuniformity on the pullout performance and failure mechanism of shallow plate anchors.The expressions of the detaching curves or surfaces were obtained to reflect the failure mechanism,which can be used to figure out the ultimate uplift capacity and failure range.The results are generally in agreement with the numerical simulations and previous research.The effects of various parameters on the ultimate uplift capacity and failure mechanism of plate anchors in multi-layered soils were investigated,and it is found that the ultimate uplift capacity and failure range of shallow anchors increase with the increase of initial cohesion and dilatancy coefficient,but decrease with the unit weight,axial tensile stress and nonlinear coefficient.

The wave absorption efficiency of multi-layer vertical perforated thin plates

This paper analyzes the wave absorption efficiency of multi-layer perforated plates in an ideal fluid, based on the linear potential flow theory. The influence of the thickness, the porosity and the layout form of the plates on the wave absorptivity is studied on the assumption that all perforated plates are composed of the same materials and have the same thickness and porosity. The calculation results indicate that the larger the number of layers of the perforated plate set, the better the wave absorption efficiency, however, when the layer number exceeds a certain value, the efficiency of the plates is not significantly increased. For the case of porosity ？= 0.2, thickness b= 0.07 m and 4 layers of perforated plates with a distance l= 1.0 m between the layers, 90% of the energy of the wave within the incident wave period between 1.6 s and 4.4 s can be absorbed.

瞬变电磁法三分量测量方法研究

在不考虑本征电流之间互感的情况下,研究用本征电流代替涡流计算地表瞬变电磁场的模拟计算方法,计算均匀半空间中定源装置下薄板导体在不同倾角时的X,Y和Z3个分量的响应特征,并与1条已知地质剖面的实测结果进行对比分析。研究结果表明:除板状体直立外,薄板导体X分量的过零点基本上是板状体的中心在地面的投影位置;当板状体水平或直立时,Y分量曲线是对称的,Z分量曲线是反对称的;当板状体倾斜时,Z分量和Y分量曲线都不对称,在倾斜方向曲线平缓,响应范围大,在反方向曲线陡立,响应范围小,因此,用X分量可以确定异常的中心,用Z和Y分量可以定性判断板状体的倾向;实测结果与计算结果一致,说明综合分析X,Y和Z方向3个分量的方法比单分量分析的方法更有助于对异常体的解释。

无限大均匀平板导体中的涡流场并矢格林函数

推导了有限厚度无限大均匀平板导体中的涡流场并矢格林函数 ,它是求解涡流检测问题构造积分方程法的核心 .由于考虑了导体厚度 ,所得结果较以前无限厚导体的模型更接近于实际情况 .

铁磁性导体材料平板远场涡流探伤技术分析

介绍了平板远场涡流检测系统的基本结构和基本检测原理.根据检测时系统中磁力线和能量的分布特点,提出了能量凹陷区的概念.利用电磁数值仿真技术,给出了远场涡流检测中导体板无缺陷和有缺陷时,感应线圈处对检测信号起主要作用的方向的磁通密度分布变化特点.对比分析了板中不同深度和不同半径平底孔缺陷对感应线圈处磁通密度分布的不同影响.分析结果表明,因缺陷引起的空间磁通密度分布曲面形状与缺陷形状间有较直观的对应关系.最后,给出了实际平板远场涡流检测实验中,铁板上下表面存在不同尺寸平底孔缺陷时的远场检测信号曲线,显示出缺陷的半径、深度及位置对检测信号的不同影响.

平板导体中裂纹缺陷探伤涡流场的求解

裂纹缺陷是涡流检测中最常遇到的缺陷类型。根据裂纹的特点 ,可以把它近似为一个没有厚度的面缺陷 ,其作用由分布在裂纹面上的等效电流偶极子层代替。使用积分方程法计算其涡流场问题 ,只需要很小的计算量。以前的工作都以无限厚导体为求解对象 ,文中研究了有限厚平板导体 ,结果表明它更加接近涡流检测的真实情况。线圈阻抗的计算值与实验结果进行了比较 ,吻合很好。

Sn-Ni化学镀硅酸钙镁矿物晶须的制备与表征

以硅酸钙镁晶须为原料,采用化学镀方法制备一种镀Sn-Ni硅酸钙镁晶须,并用SEM,XRD,EDS和FT-IR对镀Sn-Ni硅酸钙镁晶须进行表征。结果表明:镀Sn-Ni硅酸钙镁晶须是一种针状结构的硅酸盐晶须材料,除有部分聚集增粗外,其形貌几乎没有变化;镀Sn-Ni硅酸钙镁晶须的主要化学组成为:w(O)48.24%,w(Si)10.78%,w(Mg)5.44%,w(Ca)2.26%,w(Sn)22.45%,w(Ni)2.19%,w(Na)4.38%,w(P)2.46%和w(S)1.80%;镀Sn-Ni硅酸钙镁晶须在1100cm-1～850cm-1强吸收区的振动频率的增加值与在750cm-1～600cm-1弱吸收区的振动频率的降低值均为4.98cm-1;镀Sn-Ni硅酸钙镁晶须的主体结构和化学键没有发生根本上改变,Sn-Ni化学镀在本质上是一种物理包覆过程。该研究为提高矿产资源的综合开发和利用水平提供了一种新的思路和方法。

有限宽金属平板对工频磁场的屏蔽

为了定量评估金属平板对工频磁场的屏蔽效果,在阐述了理想导磁材料和理想导电材料的磁场屏蔽原理基础上,基于无限宽金属平板屏蔽区域磁场解析式,通过计算域映射,推导了有限宽金属平板屏蔽区域磁场解析式。通过仿真分析了对称三相传输线屏蔽系统,讨论了导线组排列位置、屏蔽材料类型对屏蔽效果的影响。结果表明,采用解析式,可对有限宽金属平板的屏蔽效果进行快速计算,其准确性和计算效率优于现有电磁场分析软件所采用的数值求解方法,可对实际屏蔽系统的设计提供参考。

钢板地电流新型测量仪器校准系统设计及分析

舰船钢板地电流的检测是地电流研究的一大难题,因此急需设计一种适用于舰船钢板地电流检测的新型磁场测量仪器。本文设计了长直导线和亥姆霍兹线圈两套校准系统,推导出磁场测量仪器的输出电压和磁场的函数关系式,得到了每套校准系统的校准公式及不同频率所对应的校准系数,并通过实验进行了验证。利用所得到的校准系数对钢板地电流的测量结果进行校准,可避免测量放大器增益随频率的变化对测量结果的影响,保证了地电流干扰研究的实验检测手段和验证方法的有效性。本文提出的方法思路新颖,电路结构简单,具有较强的工程应用价值。

用于涂层导体的Ag/立方织构Cu复合基带的制备

通过二次冷轧铜棒并850℃恒温热处理,制备出具有较强立方织构的Cu基带。以硝酸银、亚硫酸钠和硫代硫酸钠为主要原料配制镀银液,在立方织构Cu基带上制备出具有较强Ag(200)择优取向的银镀层。在600℃恒温热处理30min后Ag膜仍具有(200)择优取向,而830℃热处理后,Ag会扩散到Cu基底中,重复镀银、热处理5次后,Ag膜具有(200)的择优取向并少量面内织构,所得Ag/立方织构Cu复合带材可作为第二代高温超导带材YBCO涂层导体的金属基底。

涡流检测中的等效源方法

提出一种涡流等效源方法 ,用于识别缺陷的位置、形状和大小。该方法用位于分界面上的多个等效线圈产生的场等效逼近因缺陷引起的扰动场 ,使逆问题的求解中每次需用数值方法求解正问题的过程转变为每次用解析法求解正问题。缺陷的重构速度比用体积分方程法提高十倍以上。直线裂缝和 T型裂缝的重构计算证明 。

全球地壳、上地幔电导率经向分布特征

计算了对应于各个ＵＴ小时的２４个经度带的Ｓｑ地下感应场对外部施感场的响应函数，应用Ｓｃｈｍｕｃｋｅｒ＇ｓＡｐｐｒｏｘｉｍａｔｅＥｕｒｉｓｔｉｃ反演方法，计算了这些经度带的地下等效层及其电导率分布，得到了地壳－上地幔电导率经向分布的大致图案。对该结果的分析研究得出，全球电导率经向分布存在着极大的不均匀性，在０－４００ｋｍ深度范围内，太平洋和大西洋为低导区；欧亚大陆与美洲大陆为高导区。电导率分布特征与岩石层结构有明显的相关性：在俯冲带，低导区由海洋向大陆下插入；在大洋中脊表现为高导电性。反演结果与地震层析成像结果的比较表明，地下高电导区和低电导区的位置分别对应于地震波低速区和高速区。

求解时域电场积分方程的偏置网格有限差分法

细线、薄板状良导体的时域散射特性可由“全切向”时域电场积分方程 (TDEFIE)描述。本文采用偏置网格的有限差分方法数值求解“全切向”TDEFIE。这种网格充分利用物体的几何、物理特性 ,数值实现简便。利用这种方法 ,本文研究了电磁辐射、散射的三个经典问题 ,同时分析了方法本身的数值稳定性。数值结果表明 。

HDX-1500型板式电选机的研制

概述了国内、国外电达机的发展概况，提出了板式电速机的设计原则、结构及工作原理，设计了适合导体矿物精选用的电极结构装置．该新型电造机经工业试验及生产应用，结果表明，当给矿品位TiO2为94．16％时，经一次电选，金红石精矿可达特级品，其品位TiO2＞95．00％，回收率为95．91％．

接地条形导体板对均匀电场的影响及其数值模拟

利用保角变换法和复位函数法,研究接地条形导体板对均匀电场的影响,给出其电势和场强分布,并利用软件MATLAB对场分布进行数值模拟.

两平行接地大导体板间线电荷的电场

利用复数坐标系z上的保角变换,计算长直线电荷在两平行接地大导体板之间的电势和场强分布.

平板导体上方倾斜圆形线圈的瞬态涡流场

研究了有限厚导电平板上方的倾斜圆形线圈在脉冲电流激励下产生的电磁场。推导了倾斜圆形通电线圈的电流密度表达式,解析求解了导体内部的涡流密度,并提出了一种计算时域响应的有效方法。结合算例,分析了瞬态涡流的时空特点,讨论了线圈倾角、板厚与响应的关系。计算结果显示,提出的方法可用于分析倾斜圆形线圈的线性瞬态涡流场问题。与软件仿真结果的对比验证了所提模型和方法。所得结果有助于了解在倾斜条件下所获得的脉冲涡流检测信号。