共轴载流矩形线圈间的相互作用力

本文计算了共轴载流矩形线圈问的相互作用力，并对计算结果作了相关讨论，得出了一些有意义的结论．     

四个平行共轴等大载流方线圈磁场的均匀性分析

匀强磁场广泛应用于科学研究和工程技术.以毕奥-萨伐尔定律和磁场叠加原理为基础,建立了4个平行共轴等大载流方线圈磁场磁感应强度的表达式;用泰勒级数展开方法,发现了线圈系统磁场均匀性最好的条件;借助于数值计算,讨论了3种具体情况下线圈系统磁场的均匀性.结果表明:在最佳状态下,线圈系统能够在较大空间区域产生相对偏差小于0.01%、方向偏差小于0.01度的均匀性极高的磁场,并且磁场的均匀性和空间范围都明显优于方形亥姆霍兹线圈的磁场.     

亥姆霍兹线圈磁场的探究

定量计算了亥姆霍兹线圈空间磁场的分布,并用Mathmatic进行空间模拟,形象地描述了亥姆霍兹线圈的空间磁场分布,同时就其均匀性与三线圈和载荷旋转圆盘的磁场进行了对比讨论.     

无线输电装置发射线圈的磁场分布研究

根据毕奥 萨伐尔定律推导出发射线圈在空间磁场分布的积分表达式, 利用 MAT LA B对发射线圈产 生的磁场分布进行仿真, 得到磁场在径向和轴向的三维分布图, 对定性、 定量分析无线输电装置的能量传输介质 — — — 磁场有十分重要的作用     

载流线圈和有限长直螺线管磁场的理论分析与讨论

利用毕奥-萨伐尔定律,首先分析了单个载流圆线圈在空间任意一点的磁感强度分布的积分表达式,获得了其解析计算结果,并利用Mathematic描绘了其磁感线分布,同时分析了载流圆线圈所在圆面上磁感分布的特点.进而,基于单个载流圆线圈的结果,讨论了长直螺线管在空间任意一点的磁感分布,通过数值计算分析讨论了其磁场在空间分布的均匀区,并利用Mathematic描绘了其磁感线分布.最后,结合工科大学物理和大学物理实验中所涉及到的有关问题作了相应的讨论.     

多个矩形载流线圈组合磁场的模拟仿真及应用

根据毕奥-萨伐尔定律推导出矩形载流线圈在空间产生磁场的计算公式.利用公式计算出两个\\四个矩形载流线圈同名磁极相对时磁场分布规律.根据计算结果,设计出磁场能量转化演示仪,分析了弹体在磁场中运动特点及动能的来源.     

利用智能手机磁传感器测量亥姆霍兹线圈磁场

通过预实验确定智能手机磁传感器的位置后,用其测量亥姆霍兹线圈轴线的磁场分布,验证毕奥-萨伐尔定律及磁场的叠加原理,提供一种较为精确而简便的测量磁场的新方法.     

毕奥-萨伐尔定律建立过程中的数学分析

对于毕奥-萨伐尔定律建立过程中的数学分析进行了进一步研究,发现毕奥-萨伐尔定律的导出可以有严格的数学推导.而从数学的角度看,毕奥的弯折直导线实验是非常精巧的实验,在物理教学中具有重要意义.     

共轴载流正三角形线圈间的相互作用

从计算回路的磁通量出发,应用虚位移原理,通过Mathematica数学软件,数值计算得到了共轴正三角形载流线圈间的相互作用力和力矩与线圈距离以及交错角度的关系曲线.     

"电流间通过磁场发生相互作用"实验的改进

利用自制装置对教材中“电流间通过磁场发生相互作用”实验进行了改进,改进后实验现象明显,重复性好.     

Accurate AC/DC voltage measurements using electrostatic comparator

The electrostatic AC-DC voltage comparator for precise voltage measurement in voltage range of 100–1000 V and frequency range of 20–100,000 Hz was designed. The equality of AC and DC voltages transforms into horizontal positioning of the beam, which is registered by two photoelectric transducers. DC voltage was measured by voltage divider, standard cell and low-voltage comparator. The construction, main characteristics, and sources of errors are described. The comparison error has been determined as having the value of 0.003% at the voltage of 100 V and the value of 0.0009% at the voltage of 1000 V.     

粉末厚膜(交)直流电致发光(DCEL)平板显示器

我国是继英国之后世界上第二个独立自主研究并全面掌握DCEL技术的国家，其基本技术已赶上英国，达到世界先进水平，近年来，我国在DCEL核心关键技术－－包铜和形成工艺方面又开发出独特的新工艺，使生产效率和DCEL显示器最大单元发不面积均提高十至几十倍，彻底克服了对产业化的严重制约，处于世界领先水平。我国首先发现并深入研究了DCEL器件的ACEL特性，其ACEL发光亮度在市电工作条件下比传统ACEL器件提高十倍以上。深入地研究了DCEL形成过程的物理图像和机制。亮度衰减特性；发光区的成因及其随机性；DCEL器件在交流（AC）电压下的光电特性等。1985年完成世界上首台计算机控制大面积（1m^2）镶嵌式DCEL终端显示器，并成功用于全国人大常委会会务信息显示；同年还完成我国首台高分辨率便携式固体平板化DCEL微机终端显示器，利用DCEL器件的ACEL特性还成功开发出多种非矩阵DCEL显示器。     

Variations on the slotted-tube resonator: rectangular and elliptical coils.

Two designs (one rectangular, one elliptical) are proposed as efficient alternatives to noncylindrical birdcage RF coils. These designs are based on the slotted-tube resonator and their performance relies on the natural current distribution in the conductors due to the eddy current effects at high frequencies. A Finite element method program, solving the full set of Maxwell's equations, has been employed to accurately characterize and optimize the field homogeneity of the proposed noncylindrical coils. The optimum configuration of each design is presented, taking into account the effect of the RF shield. The proposed designs are compared to several configurations presented in the literature. Two coils (one rectangular, one elliptical) have been constructed and tested in a 0.6 T imaging system. A rectangular coil has been built to operate at 300 MHz. MR images substantiate the usefulness of these coils.     

Analytically modelling the effects of interaction between two or more rectangular nanomagnets

In a recent paper (Goode and Rowlands J. Magn. Magn. Mater. 295 (2005) 197–218), the micromagnetic equations which govern the magnetization distribution have been studied for rectangular nano-sized magnets where the magnetization is nearly uniform. Analytical solutions to these equations have been obtained in the form of Fourier series in which only the first few terms in the series are necessary to give results accurate to a few percent. In this paper, the above method is extended to include the effects of interaction between two or more rectangular nanomagnets. The near-uniform nature of the magnetization distributions is shown to change depending on the distance the nanomagnets are apart from each other. To estimate at what distance between the nanomagnets this interaction becomes important and therefore must be included in the analysis, the demagnetizing and interaction energies are compared for an array of uniformly magnetized rectangular nanomagnets.     

Decomposition of benzene using wire-tube AC/DC discharge reactors

Decomposition of benzene was investigated using single and two-stage stainless steel reactors with application of high-voltage AC and DC currents. Benzene removal, CO, and CO₂ were measured as a function of reactor diameter, applied voltage, and stage of reactor configuration. The results showed that, benzene removal and CO₂ selectivity improved in two-stage configuration and reached up to 59% and 97.8% respectively, where the gap size was 8.5 mm. Formation of OH, N-H and N=O function groups were seen in the exhaust gas. Subsequently, organic acids, phenols, and alcohols were identified as the main byproduct of benzene decomposition considering GC-MS analysis.     

缺陷条件下高温超导直流线圈稳定性研究

在高温超导带材生产及线圈制作的过程中,会不可避免的存在缺陷。缺陷区域的带材性能退化,表现为临界电流Ic与n值下降;极端情况下超导结构被完全破坏,呈现出非超导的阻性区。线圈工作时在阻性区会出现焦耳热,若热量不能有效地传出,温度会持续上升直到带材烧毁出现失超事故。在假设线圈退化情况的条件下,利用有限元仿真的方法,对不同热环境下带材退化对线圈温度的影响进行了研究,得出了不同热环境与区域退化下线圈的最大稳定工作电流。     

Nonlinear AC and DC Conductivities in a Two-Subband n-GaAs/AlAs Heterostructure

JETP Letters - The DC and AC conductivities of the n-GaAs/AlAs heterostructure with two filled size quantization levels are studied within a wide magnetic field range. The electron spectrum of such...     

Effects of DC and AC stress on the VT shift of AlGaN/GaN MIS-HEMTs

AlGaN/GaN MIS-HEMTs with adjusted V_T were fabricated using a recess gate to investigate the effect on actual operation when the polarity of the gate voltage is opposite in the on- and off-state. The direction and time exponents of V_T shift depend on the polarity of the gate bias stress. Electrons detrapping from the Al₂O₃/AlGaN interface trap site to AlGaN under negative gate bias stress has to overcome the energy barrier, resulting in a higher temperature dependence. In addition, the unaffected g_m and SS show that the degradation occurred primarily at the Al₂O₃/AlGaN interface rather than channel or mobility degradation. For unipolar and bipolar AC stresses, the time exponent of the V_T shift during stress time has two values, and a relatively low value during relaxation after bipolar AC stress. These results may be due to the further degradation by V_min at the broader energy levels of the Al₂O₃/AlGaN interface.     

介质加载的矩形截面Cerenkov脉塞中带状电子注与慢波结构互作用的研究

本文建立了介质加载的矩形截面Cerenkov脉塞中带状电子注与慢波结构互作用的三维物理模型. 采用Borgnis函数法和场匹配法求解了多层介质中场的匹配问题, 获得了注波互作用结构的混合模热色散方程(含电子注)及其近似解. 通过数值计算, 分析了热态下介质层厚度、电子注电压、电流密度、电子注厚度及电子注与 介质层间隙距离等主要结构和电参数对注波互作用增长率的影响.