Determining the Charge-to-Mass Ratio of the Electron

The aim of this lab was to determine an experimental value for the charge-to-mass ratio e/me of the electron. In order to do this, an assembly consisting of Helmholtz coils and a helium-filled fine beam tube containing an electron gun was used. Electrons were accelerated from rest by the electron gun at a voltage of 201.3 V kept constant across trials. When the accelerated electrons collided with the helium atoms in the fine beam tube, the helium atoms entered an excited state and released energy as light. Since the Helmholtz coils put the electrons into centripetal motion, this resulted in a circular beam of light, the radius of which was measured by taking a picture and using photo analysis. This procedure was used to test currents through the Helmholtz coils ranging from 1.3 A to 1.7 A in increments of 0.1 A. Using a linearization of these data, the experimental value for the charge-to-mass ratio of the electron was found to be 1.850 × 1011 C/kg, bounded between 1.440 × 1011 C/kg and 2.465 × 1011 C/kg. This range of values includes the accepted value of 1.759 × 1011 C/kg, and yields a percent error of 5.17%. The rather low percent error is a testament to the accuracy of this procedure. During this experiment, the orientation of the ambient magnetic field due to the Earth at the center of the apparatus was not considered. In the future, it would be worthwhile to repeat this procedure, taking care to position the Helmholtz coils in such a way to negate the effects of the Earth’s magnetic field on the centripetal motion of electrons.

Contribution of patchy reconnection to the ion-to-electron temperature ratio in the Earth’s magnetotail

The ion-to-electron temperature ratio is a good indicator of the processes involved in the plasma sheet.Observations have suggested that patchy reconnection and the resulting earthward bursty bulk flows(BBFs)transport may be involved in causing the lower temperature ratios at smaller radial distances during southward IMF periods.In this paper,we estimate theoretically how a patchy magnetic reconnection electric field can accelerate ions and electrons differently.If both ions and electrons are non-adiabatically accelerated only once within each reconnection,the temperature ratio would be preserved.However,when reconnection occurs closer to the Earth where magnetic field lines are shorter,particles mirrored back from the ionosphere can cross the reconnection region more than once within one reconnection;and electrons,moving faster than ions,can have more crossings than do ions,leading to electrons being accelerated more than ions.Thus as particles are transported from tail to the near-Earth by BBFs through multiple reconnection,electrons should be accelerated by the reconnection electric field more times than are ions,which can explain the lower temperature ratios observed closer to the Earth.

Inter-stage line ratio of He- and Li-like Ti emissions for the electron temperature measurement

Under coronal conditions, the steady state rate-equations are used to calculate the inter-stage line ratios between Li-like ls22p(2P3/2)→ls22s(2S1/2) and He-like ls2p(1P1)→1s2(1S0) transitions for Ti in the electronic temperature ranges from 0.1keV to 20 keV. The results show that the temperature sensitivities are higher at the electronic temperature less than 5000 eV and the temperature sensitivities will decrease with the increase of electronic temperature.

Effects of Finite Aspect Ratio and Noncircular Plasma Flux Surface on Electron Temperature Gradient Driven Modes

A gyrokinetic model with integral eigenmode equations is developed based on the local equilibrium of shaped tokamak plasmas. Effects of main geometric parameters （finite aspect ratio, elongation, triangularity, and Shafranov shift gradient） on the electrostatic electron temper- ature gradient （ETG） driven modes are investigated numerically. It is found that the finite aspect ratio has a general stabilizing effect, while the elongation can be either stabilizing or destabilizing, depending on the poloidal wavelength of the mode and other parameters. It is shown that a low aspect ratio enhances the stabilizing effect of elongation, and weakens its destabilizing effect as well.

Energy response correction for an electronic personal dosimeter using the channel ratio method

An electronic personal dosimeter mainly uses a Si-PIN photodiode as X-and gamma-ray detectors.The photon energy response of this instrument is inconsistent in the case of no correction,which seriously affects the accurate monitoring of personal dose equivalent H_p(10)parameters for radiation workers.For this reason,in this paper we propose a method of combining composite screen detection technology,multichannel measurement technology,and the channel ratio method to achieve accurate measurement of the personal dose equivalent parameters.According to China National Standard GB/T 13161-2003 and National Verification Regulation JJG 1009-2006,the instrument was tested in the energy range between 48 keV and 1.25 MeV.The experimental results showed that the difference of energy response to ^(137)C_S corrected by the new method was almost constant within ±6.0%,which fulfilled the ±30% requirement of GB/T 13161-2003 and JJG1009-2006.Meanwhile,the method proposed obtained energy information regarding the radiation field.

轮毂式电动汽车电子差速复合控制方法

为实现轮毂式电动汽车在弯道的稳定转向,解决传统控制方法对汽车行驶速度的局限性,提出一种高-低速复合电子差速控制方法。当汽车处于低速行驶状态时,根据Ackermann转向模型获取驱动轮期望转速,提出一种模糊PID控制方法,实现轮速的稳定跟踪;当汽车处于高速行驶状态时,以驱动轮的相对滑移率作为反馈控制量,提出一种基于模糊逼近的滑移率优化控制方法,无需建立精确的系统状态空间模型,同时根据LQR理论保证了汽车驱动轮相对滑移率最小。Matlab/Carsim联合仿真证明,所提出的高-低速复合控制方法能够使汽车在不同行驶速度下实现稳定转向。

分布驱动式纯电动汽车电子差速控制策略研究

以轮毂电机直接驱动的分布驱动式电动车为研究对象,为解决汽车转向行驶稳定性和主动安全性的问题,对其电子差速控制策略进行研究。将汽车转向时的横摆稳定性和车轮滑动率相结合,基于动力学计算转矩输出,使用模糊控制算法确定变量范围并设计出模糊控制器,采用双移线和方向盘角阶跃两种输入工况,通过CarSim搭建整车仿真联合模型,对两种电子差速控制策略的对比分析及仿真验证。结果表明,采用DYC+S控制策略比采用DYC+T控制策略的性能更加优越,提高了整车的驾驶性能。

不同肉酱比鹿肉酱中关键挥发性有机化合物的判别分析

目的探究不同肉酱比对鹿肉酱中挥发性有机化合物(volatile organic compounds,VOCs)影响的差异性,并筛选不同肉酱比的关键性VOCs。方法利用电子鼻结合气相色谱-离子迁移谱法(gas chromatography-ion mobility spectrometry,GC-IMS)检测不同肉酱比加工的鹿肉酱样品中的香气类别及VOCs成分,通过计算偏最小二乘法判别(partial least squares discriminant analysis,PLS-DA)和正交-偏最小二乘法判别(orthogonal partial least squares discriminant analysis,OPLS-DA)分析变量重要性因子(variable important for the projection,VIP),筛选可区分不同肉酱比的鹿肉酱样品中差异性影响最关键的变量敏感物质及VOCs(VIP>1)。结果电子鼻传感器S3、S7、S9和S10对应的氨类、芳香族、硫化物和萜烯类、芳香族、硫化氢类、烷烃类等敏感物质是不同肉酱比的鹿肉酱样品中最关键的挥发类特征性气味;利用GC-IMS共检测出82种主要VOCs,筛选出33种关键差异性特征VOCs(VIP>1),与电子鼻的关键特征性香气检测结果一致。结论基于电子鼻和GC-IMS的主要特征香气标志物的聚类分析能够有效、全面、客观地对不同肉酱比的鹿肉酱中关键挥发性性气味和VOCs进行区分和评价。

自由电子激光制备高强度亚稳态氦原子和类氦离子

在少电子原子精密光谱测量中,产生高强度、单一量子态的氦原子和类氦离子是实验研究的关键,也是改善实验测量信噪比的决定性因素.本文提出利用自由电子激光获得高强度亚稳态氦原子和类氦离子的实验方案.激光的制备效率可以通过求解光和原子相互作用的主方程获得,根据拟建设的深圳自由电子激光装置的设计参数和实验条件,计算得到亚稳态He,Li^(+)和Be^(2+)的制备效率分别可达3%,6%和2%以上.与常见的气体放电和电子轰击等制备方法相比,激光激发产生亚稳态原子/离子不仅可以提高制备产率,也可以降低放电时产生的电子、离子以及光子等高能杂散粒子的影响.利用自由电子激光激发制备亚稳态氦原子和类氦离子有望应用于多个研究领域.

Microscopic Analysis of Cementitious Sand and Gravel Damming Materia

The mechanical properties of cementitious sand and gravel damming material have been experimentally determined by means of microscopic SEM(Scanning Electron Microscopy)image analysis.The results show that the combination of fly ash and water can fill the voids in cemented sand and gravel test blocks because of the presence of hydrated calcium silicate and other substances;thereby,the compactness and mechanical properties of these materials can be greatly improved.For every 10 kg/m^(3) increase in the amount of cementitious material,the density increases by about 2%,and the water content decreases by 0.2%.The amount of cementitious material used in the sand and gravel in these tests was 80-110 kg/m^(3),the water-binder ratio was 1-1.50.Moreover,the splitting tensile strength was 1/10 of the compressive strength,and the maximum strength was 7.42 MPa at 90 d.The optimal mix ratio has been found to be 50 kg of cement,60 kg of fly ash and 120 kg of water(C50F60W120).The related dry density was 2.6 g/cm^(3),the water content was 6%,and the water-binder ratio was 1.09.

Unified Description of the Three Stable Particles in Self-Action Allows Determination of Their Relative Masses

The Dirac equation γμ(δμ-eAμ)Ψ=mc2Ψ describes the bound states of the electron under the action of external potentials, Aμ. We assumed that the fundamental form of the Dirac equation γμ(δμ-Sμ)Ψ=0 should describe the stable particles (the electron, the proton and the dark-matter-particle (dmp)) bound to themselves under the action of their own potentials Sμ. The new equation reveals that self energy is consequence of self action, it also reveals that the spin angular momentum is consequence of the dynamic structure of the stable particles. The quantitative results are the determination of their relative masses as well as the determination of the electromagnetic coupling constant.

一种MTW结构分子筛的合成及其二甲苯异构化反应性能

采用类似五元环中间体结构的烷基吡咯烷为模板剂,通过动态水热法在不同碱度比和硅铝比条件下合成了一种具有MTW拓扑结构的分子筛(LMTW),通过XRD、N_(2)吸附-脱附、SEM、Py-FTIR和电子晶体学等方法对分子筛的结构进行表征。以该分子筛为酸性组分,负载铂制备了转化型二甲苯异构化双功能催化剂(Pt/LMTW),使用微型活塞流反应器对催化剂的反应性能进行评价,并与Pt/REI-430催化剂的性能进行比较。实验结果表明,合成的LMTW分子筛具有和MTW分子筛一致的特征峰及相似的晶胞参数,合成过程中的碱度比和硅铝比会影响分子筛的孔道结构、比表面积及酸性等。与Pt/REI-430催化剂相比,制备的Pt/LMTW催化剂用于二甲苯异构化反应具有优异的性能。

鉴别电子烟中天然烟碱和合成烟碱的分析方法研究进展

烟碱是电子烟等新型烟草制品中的核心成分之一,烟碱有天然提取和化学合成两种来源方式,如何鉴别成为近年来的研究热点。综述了8种分析方法,主要包括烟碱异构体比例法和同位素法等,对各方法的优缺点进行了讨论,并探讨了其它可能的方法。烟碱异构体比例法包括旋光仪法、HPLC法、GC法、SFC法和NMR法等,具有简单、快速、定性定量等特点,可作为间接鉴别的方法;同位素法包括δ^(2)H、δ^(14)C、同位素模式法等,具有准确、高效、无需定量的特点,可作为直接鉴别的方法。采用上述多种方法同时确证电子烟中的烟碱来源,将大大提高结果的准确可靠性,为产品质量控制和市场监管提供技术参考。

中性粒细胞/淋巴细胞比值与白塞病疾病活动性的相关性

目的探讨中性粒细胞/淋巴细胞比值(NLR)与白塞病(BD)疾病活动性的相关性。方法103例BD患者依据电子病历疾病活动性指数(EMRAI)评分分为低活动性组(0~4分,61例)和高活动性组(5~11分,42例)。检测患者白细胞计数(WBC)、中性粒细胞计数(NEU)、淋巴细胞计数(LY)、血小板计数(PLT)、红细胞计数(RBC)、血红蛋白(Hb)、红细胞沉降率(ESR)、C反应蛋白(CRP)、IgG、IgA、IgM及补体C3、C4,计算NLR和血小板/淋巴细胞比值(PLR);分析NLR、PLR与全体患者ESR、CRP、EMRAI的相关性;采用Logistic回归分析BD疾病活动性的影响因素;绘制受试者工作特征(ROC)曲线,评估NLR对BD疾病活动性的判断效能。结果高活动性组患者WBC、NEU、PLT、ESR、CRP、NLR、PLR及补体C3、C4均高于低活动性组(P<0.05),余指标差异均无统计学意义(P>0.05)。NLR与全体患者ESR、CRP、EMRAI呈正相关,PLR与全体患者ESR、CRP、EMRAI呈正相关(P<0.05)。Logistic回归分析显示,高NLR是BD疾病活动性的危险因素(OR=1.511,95%CI:1.080~2.113,P<0.05)。ROC曲线分析结果显示,NLR评估BD疾病活动性的曲线下面积(AUC)为0.706(95%CI:0.603~0.809)。结论NLR对BD患者疾病活动性有一定的判断效能,可作为BD疾病活动性评估的生物学指标。

基于磁透镜结构参数的电子枪磁聚焦特性分析

磁透镜是电子枪的重要组成部分,其结构会影响磁聚焦性能,从而影响束斑直径与电子束焊接质量。文章以国产ZD-VEBW系列高压电子束焊接设备电子枪为研究对象,构建电子枪束源与电磁聚焦结构的物理模型,并借助CST平台,仿真分析了球差影响下的束斑形貌和不同聚焦电流下磁透镜铁壳内径、铁壳开口对束斑直径的影响。设计环形挡板实现了磁透镜铁壳内径、铁壳开口参数的调整,并进行聚焦电流变化下的焊接实验研究。实验结果表明:磁透镜结构参数的合理设计可以达到更优的磁聚焦特性、更小束斑直径与更大的焊缝深宽比,实验验证了仿真结果的正确性,文章的研究对国产ZD-VEBW系列高压电子枪磁透镜结构的设计和该系列电子枪焊接质量的提升提供了理论和实验指导。

基于OpenCV提升电子荷质比的测量精度

利用计算机视觉库OpenCV提供的Hough圆检测方法对塞曼效应实验中光的干涉圆环进行拟合,采用拟合的直径数据计算电子荷质比,并与CCD自带的三点画圆测量干涉圆环直径的方法进行对比.实验结果表明:利用三点画圆方法得到的数据计算电子荷质比的相对偏差为9.09%,利用Hough圆检测方法得到的数据计算电子荷质比的相对偏差为1.13%,有效提升了测量精度.为了提升测量的便捷性,基于Vue数据双向绑定技术,实现了基于HTML5的跨平台交互应用界面,打破了编程语言需要特定运行环境的限制,在该界面中,通过对拟合参量的调节,实现干涉圆环和圆心的同步拟合显示,并将拟合得到的圆心坐标和直径大小直观显示在界面中,方便电子荷质比的计算.

低透气性煤层点式酸化压裂增透技术研究与应用

为解决富含矿物质煤层透气性问题,基于点式压裂和酸液增透煤体机制,提出了点式酸化压裂增透技术,且通过扫描电镜试验确定了适合三元煤矿的酸液配比。现场试验结果表明,点式酸化压裂钻孔组的平均瓦斯抽采流量和浓度是普通钻孔组的3.65倍和1.72倍,是点式水力压裂钻孔组的1.32倍和1.06倍,点式酸化压裂增透效果明显优于点式水力压裂,且其增透煤体的起裂压力和同等条件下的注液量均低于点式水力压裂。点式酸化压裂实现了煤体定点、低流量、大范围、快速增透,其对物理增透与化学增透方式的融合大大提高了煤体孔隙-裂隙结构的发育程度和其整体连通性,有助于煤体中瓦斯的运移及高效抽采。

基于FPGA的间歇采样干扰技术及实现

在现代电子战环境中,雷达系统面临着各种复杂的干扰威胁,其中,间歇采样干扰是一种有效的干扰措施,它通过在时间上非连续地发射干扰信号片段来影响雷达的检测和跟踪能力。本文对间歇采样切片干扰的实现进行了详细的理论分析和工程实现验证,通过对切片干扰参数以及干扰时序的控制提出了三种间歇采样切片干扰的实现方式。通过理论分析以及工程实现验证,结果表明,间歇采样切片干扰能够对脉冲压缩体制雷达系统产生有效的干扰效果。该研究为电子战领域提供了一种创新的干扰手段,同时也为雷达系统的抗干扰设计提出了新的挑战。

新型高纵横比通孔镀铜整平剂研究

印制电路板是电子工业的重要部件之一,广泛地应用在社会生活的方方面面。随着电子信息技术的发展,电子产品与设备不断轻薄化、小型化、集成化。作为电子元器件的载体,电路板设计和制造也朝着高密度互连、小孔化技术的方向快速发展。通孔作为连接层与层之间的导通孔,逐渐成为实现层间互连的核心技术。但是高厚径比通孔的电镀工艺往往存在电流密度分布不均、孔内镀液传质不佳等现象,导致镀层均匀性及铜层结晶质量变差现象产生,无法满足客户端的需求。如何解决高厚径比的微通孔镀铜是电镀领域的一个技术难题,具有重要研究意义及实际应用价值。整平剂是镀铜整平剂体系中很重要的物质,其含量较低,对孔内的低电流密度区域影响不大。目前针对高厚径比通孔电镀整平剂研究较少,且市面上使用较为广泛的镀铜整平剂被国外大公司垄断。因此,急需研发一种高厚径比通孔电镀方法,有效改善线路板表面与孔内镀层均匀性,提升通孔深镀能力,从而打破技术垄断,突破“卡脖子”难题,促进我国印制电路板产业的发展。

掺黏粒改良粉土的土水特征试验研究

以河南开封金明大道北延道路路基工程低液限粉土为研究对象,通过滤纸法测定不同黏粒含量、压实度的粉土土水特征曲线,研究其基质吸力变化规律;采用扫描电镜试验从微观结构演化角度分析其影响机制。结果表明:加州承载比CBR值随黏粒含量与压实度的增加均单调增大;不同压实度下掺黏粒改良粉土的饱和含水率均随黏粒含量的增加呈先增大后减小趋势;任一黏粒含量下,土水特征曲线具有明显的阶段性特征,黏粒含量为15.5%、20.5%、26.5%的土水特征曲线存在基质吸力保持相对恒定的平台期;黏粒含量的增加使得重塑土样的微观结构逐渐紧密,粉黏粒间的接触方式由线或面的接触逐渐转变为胶结及包裹镶嵌作用。根据规范要求,掺黏粒改良粉土可应用于公路路基填筑。