Experimental Study of Liquid Metal Flow for the Development of a Contact-Less Control Technique

The article presents an experimental study on the flow of an eutectic gallium alloy in a cylindrical cell,which is placed in an alternating magnetic field.The magnetic field is generated by a coil connected to an alternating current source.The coil is located at a fixed height in such a way that its plane is perpendicular to the gravity vector,which in turn is parallel to the axis of the cylinder.The position of the cylinder can vary in height with respect to the coil.The forced flow of the considered electrically conductive liquid is generated due to the action of the localized electromagnetic force.It is assumed that under the action of the alternating magnetic field,the liquid is heated uniformly,and the resulting heat is quickly absorbed by the forced flow,so that liquid free convection can be neglected.The experiment is carried out using an ultrasonic Doppler anemometer.One transducer is installed in the axially located cylinder sluice and the other transducer is placed in the near-wall region.According to the results,a velocity profile,corresponding to a two-tori flow pattern can be hardly obtained in the low frequency range of the power supply.However,this is possible in the high frequency range.The average velocity profiles depend essentially on the location of the coil relative to the cell.The spectral analysis of velocity signals shows that the amplitude of the velocity pulsations is comparable to the average value of the flow velocity.Such experimental results and their verification through comparison with numerical calculations are intended to support the development of new methods for reducing the intensity of vortex flows during the electromagnetic separation of impurities through an electromagnetic induction mechanism(able to produce an electromotive force that displaces particles).

Experimental research of traction motor system for electric vehicle base on sound tensity

The traction motor of electric vehicle is differing from the general industry traction motor completely. Not only frequently start, parking, accelerate, decelerate and low speed, but also high torque in climbing slope, low torque in high speed and wide range speed are requested. Base on the theory of sound intensi- ty, the experiment of noise are study through the measurement at discrete points. The sizing grid is 10mm × 10mm, The sound intensity map of traction motor are protracted at 1000r/min and the result show that the main noise sources are fan, gear-box and the traction motor in turn.

The Quantum Handshake: An Electric Charge/Transactional Interpretation of the Single Electron Double-Slit Experiment

A new and falsifiable realist interpretation of quantum mechanics is examined in relation to the sum over histories concept, pilot wave theory and the many-worlds interpretation. This electric charge/transactional model explains how the single electron double-slit experiment produces extremely localized endpoints from diffracted wavicles, why these endpoints are scattered around the entire surface of the absorber screen, and why these points of contact result in the characteristic fringe pattern as they accumulate. Advanced waves and substantive electric charge effects in the double-slit experiment are postulated, then this hypothesis is supported by a quantitative analysis of electron emission in comparison to lightning. The wider implications if advanced waves and electric charge distribution prove to be significant factors in the double-slit experiment are discussed, including possible parallels with meteorological and neurological phenomena.

基于SolidWorks Electrical的机电一体化教学研究

现阶段高校在进行机电一体化课程建设时,往往理论知识较多,而实践机会较少,因此在学习机电一体化课程时,往往出现学生难以理解,导致学生的设计作品往往都因为经验不足而不理想,通过引入solid electrical系列软件,在虚拟三维空间中对机电一体化设备进行设计并加以改进,可以大大的缩短设计周期以及降低设计成本,而且还能够有效的提高产品设计的成功率。

EFFECT OF DENTIN TUBULES TO THE MECHANICAL PROPERTIES OF DENTIN.PART Ⅱ:EXPERIMENTAL STUDY

To verify the theoretical models of varying transversely isotropic stress-strain relations of dentin established in the preceding work(Part Ⅰ),we per- form a set of experiments.Because of the very fine tooth size,it usually seems to be difficult to directly measure the inhomogeneous and anisotropic parameters of dentin.In this paper,by the digital speckle correlation method,tensile experiments are made on the small dentin samples either parallel or perpendicular to the dentin tubules.With the theoretically predicted elastic stress-strain relations,an optimiza- tion method is proposed to fit the strain curve adapted to the experimental data. The results show that the theoretical elastic stress-strain relations coincides very well with the experimental observations.The determined Young's modulus and Poisson's ratio of dentin matrix are 29.5GPa and 0.44,respectively,in the optimization sense.

Comparison of smoothness-constrained and geostatistically based cross-borehole electrical resistivity tomography for characterization of solute tracer plumes

Experiments using electrical resistivity tomography(ERT) have shown promising results in reducing the uncertainty of solute plume characteristics related to estimates based on the analysis of local point measurements only.To explore the similarities and differences between two cross-borehole ERT inversion approaches for characterizing salt tracer plumes,namely the classical smoothness-constrained inversion and a geostatistically based approach,we performed two-dimensional synthetic experiments.Simplifying assumptions about the solute transport model and the electrical forward and inverse model allowed us to study the sensitivity of the ERT inversion approaches towards a variety of basic conditions,including the number of boreholes,measurement schemes,contrast between the plume and background electrical conductivity,use of a priori knowledge,and point conditioning.The results show that geostatistically based and smoothness-constrained inversions of electrical resistance data yield plume characteristics of similar quality,which can be further improved when point measurements are incorporated and advantageous measurement schemes are chosen.As expected,an increased number of boreholes included in the ERT measurement layout can highly improve the quality of inferred plume characteristics,while in this case the benefits of point conditioning and advantageous measurement schemes diminish.Both ERT inversion approaches are similarly sensitive to the noise level of the data and the contrast between the solute plume and background electrical conductivity,and robust with regard to biased input parameters,such as mean concentration,variance,and correlation length of the plume.Although sophisticated inversion schemes have recently become available,in which flow and transport as well as electrical forward models are coupled,these schemes effectively rely on a relatively simple geometrical parameterization of the hydrogeological model.Therefore,we believe that standard uncoupled ERT inverse approaches,like the ones discussed and assessed in this paper,will continue to be important to the imaging and characterization of solute plumes in many real-world applications.

Real-time localization for underwater equipment using an extremely low frequency electric field

A new real-time underwater equipment location method adopting an electric field induced by a standard current source is proposed.Our goals were real-time tracking and location of stationary or moving underwater equipment both in shallow and deep seas,under noisy conditions.The main features of this method are as follows:(1)a standard current source on the water surface,which can be towed by a vehicle,consisting of two electrodes,a signal generator,and a GPS unit;(2)measurement of the extremely low frequency(ELF)electric field emitted by the current source,made possible by electric field sensors on the underwater equipment;(3)position of the underwater equipment is estimated in real time based on a progressive update extended Kalman filter(PUEKF),which is carried out using the propagation model of an ELF electric field because the electric field at the position of the underwater equipment and the current source position are known.We verified the accuracy of our method and confirmed real-time location feasibility through numerical,physical scale,and real-time sea experiments.Through numerical experiments,we verified that our method works for underwater equipment location in real-world conditions,and the location error can be less than 0.2 m.Next,real-time location experiments for stationary underwater measuring equipment in water tank were conducted.The result shows that the location error can be less than 0.1 m.We also confirmed real-time location feasibility through the use of offshore experiment.We expect that our method will complement conventional underwater acoustic location methods for underwater equipment in acoustically noisy environments.

基于脑电信息的图感认知响应规律及其量化分析方法

“图”是人类感知世界的重要媒介,图感认知是大脑认知思维中平面图元与三维形体间形成有效转换的关键通道,但人脑在接受图形输入、完成认知处理并实现知识输出的过程是认知心理学和脑科学交叉学科。目前缺乏充分的研究方法和理论基础,因此针对图感认知过程不清晰及认知分析方法缺乏等问题,根据认知事件的脑电位相关性理论,以二维投影图和三维模型为图感认知对象,设计脑电认知测试实验并分析P300电位变化情况。结果表明:图感认知相关部位主要为大脑的前半部分左额叶位置;P300电位值可以用于反映大脑的图感认知程度,大脑对图像内容的接受能力越强,P300电位峰值越低。对比不同样本P300电位变化,可对图感认知过程进行分析,形成对图感认知能力的量化分析方法,提高图感认知内容对大脑的输入效率,对揭示图感输入和认知机理具有启示意义,并为图像交互深度应用反馈优化提供有效依据。

电基础课程群随课实践体系构建与探索

针对电基础课程理论与实验纵向脱节、横向脱离、统一与创新脱断3个痛点问题,借助口袋实验平台,将“随课”实践(跟随理论课进度的实践作业)纳入平时的教学环节;通过提炼元件—单元电路—子系统—综合系统4个模块,明晰应用主线;针对学生个性化需求,设置不同类别的经典工程案例;通过精心设置随课口袋实验内容,借助其“架梯子”作用,实现“重探究、深思考、闭环式”的纵向贯通;通过元器件和分立元件应用实例的恰当引入,借助口袋平台“搭桥梁”的角色,完成“强融合、优过渡”的横向破壁。经过多年的教学探索和实施,学生在实践能力、工程思维、创新意识的综合能力均得到提升。

导电溶液浓度对高压电脉冲煤体致裂增透效果影响实验研究

为检验溶液浓度对高压电脉冲煤体致裂增透效果的影响,采用水溶液和浓度分别为0.5 mol/L、1.0 mol/L、1.5 mol/L、2.0 mol/L的NaCl溶液作为导电介质,运用高压脉冲放电系统对相似煤样进行水中放电致裂实验,并采用超声波检测技术分析致裂效果。实验结果表明:采用水作为导电溶液时放电压力峰值为1.26 MPa,而采用NaCl溶液作为导电介质时放电压力峰值明显提升,采用NaCl溶液实验后煤样的首波声时差也高于水溶液实验后煤样的首波声时差,煤样的内部裂隙改造效果更为显著,表明导电溶液的加入可以优化煤样的导电性能;随着导电溶液的浓度增大,放电压力峰值越大,高压电脉冲在一定浓度的NaCl溶液中放电,能够提高电能转化为等离子通道能量的利用率,导电溶液浓度增加可以加强煤样的导电性,优化高压电脉冲放电致裂增透效果;但随着浓度继续升高,相较于1.5 mol/L NaCl溶液,2.0mol/L NaCl溶液放电压力峰值仅由2.20 MPa提升到2.25 MPa,两者首波声时差的变化也不大,煤样的致裂情况相仿,此时煤样对各导电离子的吸附量达到饱和状态,煤样吸附离子的数量基本维持不变,因此,煤样的导电性基本不变。

“新工科”背景下电气工程专业课程实验教学改革研究

新工科建设背景下,为满足电气工程专业课程实验教学体系改革优化的需求,该文首先对电气工程专业实验教学现状进行分析,总结当前实验教学中存在的问题和不足,并分析实验教学的发展趋势;然后针对实验教学内容、实验平台、教学模式、实验室管理、评价体系探究改革方向和措施;最后以电力电子探究性实验教学为例,介绍各改革方向在浙江大学电气学院专业实验教学中的应用案例,从而为电气工程类专业课程探究性实验教学改革提供理论和实践参考。

基于BOPPPS的混合式电子实验教学实践

为推进“教育+互联网”,国内高校广泛开展了在线课堂教学的新模式。将BOPPPS教学理念引入实验课程的在线教学中,以交流信号幅度判别电路的Multisim设计为例,对传统的电工电子实验课程进行重新设计和调整,以钉钉直播及雨课堂为教学工具,成功实现了该课程的线上混合式教学。实践表明,这种线上实验教学模式具有很好的教学效果,有助于提高学生的自主学习能力和实验操作的顺利进行。

电工电子仿真实验线上线下混合教学模式探索

为满足电工电子实验教学改革和公共突发事件教学预案的需求,基于线上会议平台和翻转课堂设计了电工电子的仿真实验,解决了时空不一致时实验教学难以实施的问题。以“串联电路中电感电容的共振现象”实验为例介绍了新的教学模式,实现了课前推送实验理论资料、实时测验预习情况、数字化实验报告和教学资料及线上线下混合教学的功能,在督促学生预习、灵活投屏答疑、个性化培养等方面存在优势,在本科生电工电子实践教学中取得了良好的效果。

个性化髋关节假体设计及其生物力学性能研究

通用型髋关节假体和个人股骨匹配度不足,易导致应力遮挡率过大。为制备与个人股骨相匹配的髋关节假体,基于人体下肢电子计算机断层扫描(computed tomography,CT)数据,通过逆向工程技术建立股骨实体模型,利用提取的关键特征参数逆向建模,建立个性化髋关节假体模型,采用步态试验确定股骨受力情况,进行有限元分析和电测实验研究其生物力学性能。结果显示,在站立中期的步态载荷下个性化髋关节假体的应力遮挡率在7.64%~38.71%之间,通用型髋关节假体应力遮挡率在16.66%~49.32%之间。个性化髋关节假体可以减小应力遮挡率,可为髋关节假体研究人员提供参考。

偏心拉伸实验的理论分析与实验研究

偏心拉伸实验是一种综合性、研究性的材料力学实验项目。为了增加材料力学实验课程的难度和深度,通过理论分析推导偏心拉伸应力公式,并指出偏心拉伸试样的实际中性层并不再是几何中性层;利用ABAQUS软件模拟了偏心拉伸试样的应力分布;通过自制的一种可以在电子万能试验机上进行偏心拉伸实验的装置并利用电测法测试了试样横截面上各点的应变。结果表明:偏心拉伸实验的理论计算结果、实验结果和模拟结果基本吻合,3种数据之间的偏差较小;而且,应力在试样横截面上几乎呈线性分布,左边受压缩,右边受拉伸,左边的应力最小,右边的应力最大。

基于电测法测量弹性模量和泊松比的实验研究

测量材料的弹性模量和泊松比是材料力学实验的一项重要实验项目。为了丰富材料力学实验教学手段和教学内容,把理论计算、有限元仿真技术和电测法测试技术有机地融合在一起。分别通过电测法、ABAQUS软件模拟和理论计算方法得到低碳钢的弹性模量和泊松比。结果表明:模拟结果和理论计算结果几乎相等,但是电测法实验测试结果与理论计算结果之间的误差相对较大,主要是由于电阻应变片在试样表面的粘贴质量不高和试样的几何尺寸测量不精确造成的。

采用量化任务驱动的混合式教学研究——以“电路原理实验”课程为例

线上线下混合式教学是目前高校常见的教学模式,但在其应用中学生的学习效果特别是线上部分难以保证。任务驱动式教学是一种通过任务来引导学生主动应用学习资源进行探究的教学方法。探索了在混合式教学中应用量化任务驱动的教学方法,教师预先对每一环节进行任务设定,且任务采用可量化评价的问卷或题目形式,形成清晰的评价目标,引导学生主动有效地学习。此方法在“电路原理实验”课程教改实践中取得了较好的效果。

BOPPPS模式在电工学实验教学中的应用

为解决电工学课内实验教学中存在学生学习动能不足、小组合作质量不高、学生被动学习等突出问题,提出运用BOPPPS教学模式规划完善课前、课堂和课后教学设计,重点“向课堂要成效”的教学改革思路。将传统实验教学方法与信息技术工具相结合,明确6个教学环节的目标任务和活动模式,强化人际互动,加强监督和及时反馈,在实验中培养学生工程实践能力。实践教学证明,所采取的改革措施可有效激发学生学习热情,促进小组成员合作,提高分析问题和解决问题的能力。在“预期学习目标达成”和“总体教学质量评价”方面学生认可度良好。方法与案例可为实验课程改革提供参考和借鉴。

面向电气工程实际的多物理场数值仿真开放实验教学

在电气工程专业本科生电磁场实验教学中,开展面向电气工程实际的多物理场数值仿真开放实验教学,对培养学生的工程观念、综合应用多学科专业知识解决实际电气工程问题的能力具有重要的意义。以电力系统中广泛应用的电力设备——干式空心电抗器为研究对象,阐述了开设干式空心电抗器电、磁、热以及力场等多物理场数值仿真开放实验的目的、内容及实施过程。这些开放实验取得了良好的教学效果。

填料性质对催化裂化油浆静电分离效率影响冷模试验研究

为分析静电分离法脱除催化裂化油浆中固含量影响因素,采用自制静电分离器试验装置,研究填料直径和材质对催化油浆中催化剂固体颗粒脱除效率影响规律。结合数值模拟,分析填料直径和材质对其接触点处电场强度变化的影响。结果表明,油浆中固体颗粒分离效率随填料直径增大而降低,氧化锆填料的分离效率最高,玻璃填料的分离效果最差。随填料直径和填料相对介电常数增大,填料接触点处的电场强度增大。在不同材质填料物化参数中,填料相对介电常数对油浆中固体颗粒静电分离影响过程起主要作用。