理解磁通量和磁通量变化率的方法

在高中物理中磁通量和磁通量变化率好似一对孪生姐妹,学生在理解时往往混淆两个物理量的异同,特别是在交流电一章的学习过程中,线圈在磁场中转动,为什么磁通量最大时,磁通量的变化率最小;在磁通量最小时,磁通量的变化率反而最大.针对这个问题,笔者采用了两种方法进行分析,收到了很好的效果.     

Hydrodynamic Properties of Fe3O4 Kerosene-Based Ferrofluids with Narrow Particle Size Distribution

We investigate the hydrodynamic properties of Fe3O4 kerosene-based ferrofluids with narrow particle size distribution. The ferrofluids are synthesized by improving chemical coprecipitation technique. A narrow distribution of 8.6-10.8nm particle sizes is obtained from the magnetization curve with the free-form model based on the Bayesian inference theory. The fitting result is consistent with average particle size obtained from x-ray diffraction. With the increase of applied magnetic field and magnetic particle concentration, apparent viscosity of ferrofluids increases. At concentration 4.04%, the type of flow for the ferrofluid transforms from Newtonian to Bingham plastic fluid as the applied magnetic field increases.     

用高温超导模拟研制磁场高均匀度回旋管

磁场高均匀度的低温超导磁体系统已经取得了广泛的应用，在许多领域发挥着重要的作用。随着低温技术和超导技术的发展，用高温超导材料制作高均匀度的超导磁体成为可能。因此，我们用高温超导材料模拟制作了磁场高均匀度回旋管。     

Singlet-Triplet Transition in Quantum Dots Confined by Triangular and Bowl-Like Potentials： the Effect of Electric Fields

We theoretically investigate the energy spectra of two-electron two-dimensional （2e 2D） quantum dots （QDs） confined by triangular potentials and bowl-like potentials in a magnetic field by exact diagonalization in the framework of effective mass theory. An in-plane electric field is found to contribute to the singlet-triplet transition of the ground state of the 2e 2D QDs confined by triangular or bowl-like potentials in a perpendicular magnetic field. The stronger the in-plane electric field, the smaller the magnetic field for the total spin of the ground states in the dot systems to change from S = 0 to S = 1. However, the influence of an in-plane electric field on the singlettriplet transition of the ground state of two electrons in a triangular QD modulated by a perpendicular magnetic field is quite small because the triangular potential just deviates from the harmonic potential well slightly. We find that the strength of the perpendicular magnetic field needed for the spin singlet-triplet transition of the ground state of the QD confined by a bowl-like potential is reduced drastically by applying an in-plane electric field.     

三足鼎立 谁是巅——7款非磁带式数码摄像机横向评测

“天下大势，分久必合，合久必分……” 迷你磁带已经统治数码摄像机存储领域十数载，其终于在2005年迎来了最强有力的挑战。采用DVD刻录光盘，1.8英寸笔记本电脑硬盘及闪存卡的数码摄像机开始流行起来，改朝换代的时刻已经为期不远了。     

色彩绽放照片级彩色喷墨打钱横向比较

时尚数码生活需要什么呢?自由、简单、随心所欲。无论是家庭聚会还是出外旅游，让每一时刻的精彩生活完美呈现已经越来越成为数码发烧友的追求。随着以数码相机为代表的数码影像领域的不断发展，数码照片打印逐渐成为普通家庭用户乐于尝试的事情了，品味自己亲手打印照片的那份喜悦，正成为人们享受时尚的一种方式。早春三月，万物复苏，郊外山花烂漫，又到了一年一度的旅游踏青时节。在观赏秀丽的风景时，也拍摄了大量的数码照片，将它们打印出来与家人朋友共同分享也成为了大多数人的愿望。因此，选择一款照片级彩色喷墨打印机进行数码照片输出成为迫切的需要。因此，《数码》组织了这次照片级彩色喷墨打印机的横向评测，征集了四大打印机厂商的13款产品，通过严格的测试，向你全面展示它们的性能，以帮助你选择最优的产品……     

浅谈家用吊扇的调速方法

家用吊扇的核心部分是单相异步电动机,此绕组如图1,有一主绕组(工作绕组)与一串联电容器C的副绕组(启动绕组)相并联.这样做可使二绕组的电流在相位上相差90°,从而形成旋转磁场.转子的转动过程与三相异步电动机相似.     

用激光吹气注入高Z杂质使HL-1M装置放电有效地安全终止的研究

现在国际上大装置纷纷发现破裂放电而导致电流突然中止造成装置遭受重大的危害，因为能量熄灭阶段存在强烈的热通量，而且在电流熄灭阶段中产生强烈的逃逸电子，使得第一壁材料可运行的时间大大缩减；同时在真空器壁上产生很强的电磁力。所以，必须在大装置上建立一种避免和软化能量衰竭与电流衰竭，并且控制预计的放电破裂或突然终止放电的措施。