测量电子电量及荷质比的实验方法

电子电量及电子的荷质比是带电微观粒子的基本参量之一,它们的测定在近代物理学的发展中具有重大的意义,本文介绍了测定电子电量及电子荷质比的典型实验方法,详细介绍了电子束磁聚焦实验测量电子荷质比和密立根油滴实验测量电子电量的实验原理及方法和注意问题。     

利用电荷电量与速度关系推导几个电磁学基本定律

由电荷与速度关系,导出电流元相互作用的安培定律,导出电荷在磁场中运动所受洛仑兹力,并对J.J汤姆逊测电子荷质比过程的分析,说明其结果并未违反运动电荷与速度关系。     

水利工程用止水铜片抗拉强度不确定度评定

本文介绍了用CSS44100电子万能材料试验机测定水利工程用止水铜片抗拉强度的试验方法,并对试验结果的测量不确定度进行分析评定,从而找出了影响抗拉强度测量结果的主要因素。     

基于数值计算方法的深基坑施工诱发淤泥质黏土运移规律研究

淤泥质黏土除了具有一般土体的各种变形特征以外,还有其自身的特点,首先淤泥质黏土较大的孔隙比、含水量,导致了其变形量较大;颗粒组成是以粘粒为主,单个孔隙很小,渗透性很低。饱和土受荷后,水不能很快排出,变形也只能缓慢发展。鉴于上述特点,需要对淤泥质黏土的变形规律进行深入研究。为此,依托深圳地铁10号线停车场基坑开挖工程,针对淤泥质黏土的工程力学特性,采用数值计算分析,得到了深基坑施工动荷载诱发淤泥质黏土运移规律,为掌握本工程淤泥质黏土力学特性和工程灾害治理提供了重要理论依据。     

电子汽车衡称量结果的测量不确定度评定

电子汽车衡作为贸易结算用测量设备,称量结果的准确程度可能直接影响测量过程的最终结果,因此,应对电子汽车衡称量结果进行合理评定,计算测量结果的最佳估计值以及分散性大小。详细介绍了电子汽车衡测量不确定度评定方法、过程。     

示波测试中异常现象浅析

示波器是一种常见的电子图示测量仪器,掌握正确的使用方法是进行电子测量的前提。本文对示波测试过程中异常现象的原因进行了分析和讨论,并提出了具体处理方法。     

示波测试中异常现象浅析

示波器是一种常见的电子图示测量仪器。掌握正确的使用方法是进行电子测量的前提。本文对示波测试过程中异常现象的原因进行了分析和讨论,并提出了具体处理方法。     

气固两相流静电测速技术与系统

介绍气固两相流中颗粒荷电产生的机理,阐述了静电传感器测量原理,并介绍了多种接触式和非接触式静电传感器,重点叙述了静电传感器测速的基本原理和整套气固两相流速度测量系统的组成部分。     

浅析电子仪表测量技术和故障检测维护

随着我国经济的不断进步,科技的不断发展,在电子产业方面取得了比较大的进步。对于电子仪表的测量还有故障检测维护的技术也在不断的提升,并且通过相关的电子测量设备就能够达到检测电子仪表的相关元件的工作状态,因此,掌握对于电子仪器仪表的故障检测和维护技术,能够有效的保证仪器仪表的正常使用。基于此,文章对于电子测量技术进行了概述,并且对电子仪表测量故障和维护的方式方法进行了探究。     

电子剪切散斑干涉技术时间相移法在金属梁微小位移测量中的应用分析

电子剪切散斑的图像稳定,对测量环境的要求低,可用于现场的无损检测。本文介绍了散斑干涉测量的原理与电子剪切散斑干涉时间相移法,并应用此方法对金属梁的位移场进行测量。     

Resistive pulse sensing of magnetic beads and supraparticle structures using tunable pores

Tunable pores (TPs) have been used for resistive pulse sensing of 1 μm superparamagnetic beads, both dispersed and within a magnetic field. Upon application of this field, magnetic supraparticle structures (SPSs) were observed. Onset of aggregation was most effectively indicated by an increase in the mean event magnitude, with data collected using an automated thresholding method. Simulations enabled discrimination between resistive pulses caused by dimers and individual particles. Distinct but time-correlated peaks were often observed, suggesting that SPSs became separated in pressure-driven flow focused at the pore constriction. The distinct properties of magnetophoretic and pressure-driven transport mechanisms can explain variations in the event rate when particles move through an asymmetric pore in either direction, with or without a magnetic field applied. Use of TPs for resistive pulse sensing holds potential for efficient, versatile analysis and measurement of nano- and microparticles, while magnetic beads and particle aggregation play important roles in many prospective biosensing applications.     

冠层底部光合有效辐射三种测量方法的比较

精确测量冠层底部光合有效辐射量(TPAR)可以提高生物量预测和模型模拟精度.本文采用3种方法对行播作物冬小麦和夏玉米整个生育期冠层底部TPAR分别进行了测量,并分生育期对比分析3种方法测量值的差异.结果表明:冬小麦全生育期垂直于行测量值平均相对误差最小,斜穿于行最大;夏玉米全生育期斜穿于行测量值平均相对误差最小,平行于行最大;冬小麦和夏玉米全生育期3种方法测量值在0.001置信水平上均无显著性差异.建议冬小麦冠层底部TPAR测量采用垂直于行的测量方法,夏玉米冠层底部TPAR测量采用斜穿于行的测量方法.     

两种方法评价不同高度涡度相关系统的观测结果

主要通过常规气象参数、湍流特性和能量闭合度对2套涡度相关系统的观测结果进行了比较研究.对2层高度湍流特性的研究中,以相似理论为基础,分析了垂直风速的标准差和稳定度参数z/L(观测高度与莫宁霍夫长度比值)的关系,2层观测结果对垂直风速的标准差和稳定度参数z/L的模拟方程显示23m观测数据的模拟结果更符合通用方程的经验参数.最后对2层高度的半年时间内(2003-01-01)～(2003-06-30)总体能量闭合度和能量闭合度的时间变化趋势作了对比研究.结果表明,39m观测结果的总体能量闭合度要高于23m的总体能量闭合度;但从各自的能量闭合度的时间变化来看,23m在冬季的能量闭合度要高于39m,而在春季39m的能量闭合度要高于23m.     

长白山地区蒙古栎光合特性

基于单叶尺度上的光强－光合响应以及CO2－光合响应测定，对长白山地区蒙古栎成树和幼树的光合特性分别进行了研究．结果表明，蒙古栎成树的光补偿点（Lcp）为21μmol/m2/s，光饱和点（Lsp）为1564μmol/m2/s，表观量子效率（a）为0.045μmol/mol；幼树的Lcp、Lsp、a以及CO2补偿点、饱和点分别为29μmol/m2/s、1581μmol/m2/s、0.049μmol/mol、73μmol/mol、625μmol/mol．幼树和成树具有相似的光响应特征，但前者的光合同化能力要高于后者．蒙古栎具有典型的喜光性，但对高光的利用效率要低于弱光．     

Quantitative impedimetric monitoring of cell migration under the stimulation of cytokine or anti-cancer drug in a microfluidic chip

Cell migration is a cellular response and results in various biological processes such as cancer metastasis, that is, the primary cause of death for cancer patients. Quantitative investigation of the correlation between cell migration and extracellular stimulation is essential for developing effective therapeutic strategies for controlling invasive cancer cells. The conventional method to determine cell migration rate based on comparison of successive images may not be an objective approach. In this work, a microfluidic chip embedded with measurement electrodes has been developed to quantitatively monitor the cell migration activity based on the impedimetric measurement technique. A no-damage wound was constructed by microfluidic phenomenon and cell migration activity under the stimulation of cytokine and an anti-cancer drug, i.e., interleukin-6 and doxorubicin, were, respectively, investigated. Impedance measurement was concurrently performed during the cell migration process. The impedance change was directly correlated to the cell migration activity; therefore, the migration rate could be calculated. In addition, a good match was found between impedance measurement and conventional imaging analysis. But the impedimetric measurement technique provides an objective and quantitative measurement. Based on our technique, cell migration rates were calculated to be 8.5, 19.1, and 34.9 μm/h under the stimulation of cytokine at concentrations of 0 (control), 5, and 10 ng/ml. This technique has high potential to be developed into a powerful analytical platform for cancer research.     

电涡流传感器线圈充磁介质对抑制温漂及测量性能的影响

对充满磁介质的电涡流传感器进行了较为深入的理论研究，讨论了磁介质对抑制线圈阻抗温度漂移及测试性能产生的影响。研究结果对电涡流传感器线圈中是否加磁介质有较好的参考价值。     

Refinement of the theory for extracting cell dielectric properties from dielectrophoresis and electrorotation experiments

A modified theory is proposed for extracting cell dielectric properties from the peak frequency measurement of electrorotation (ER) and the crossover frequency measurement of dielectrophoresis (DEP). Current theory in the literature is based on the low frequency (DC) approximations for the equivalent cell permittivity and conductivity, which are valid when the measurements are performed in a medium with conductivity less than 1 mS/m. The present theory extracts the cell properties through optimizing an expression for the medium conductivity in terms of the peak ER, or DEP crossover, frequency according to its definition using full expressions of equivalent cell permittivity and conductivity. Various levels of approximation of the theory are proposed and discussed through a scaling analysis. The present theory can extract both membrane and interior properties from the low and the high peak ER, or DEP crossover, frequencies for any medium conductivity provided the peak ER, or DEP crossover, frequency exists. It can be reduced to the linear theory for the low peak ER and DEP crossover frequencies in the literature when the medium conductivity is less than 10 mS/m. However, we can determine the membrane capacitance and conductance via the slope and intercept, respectively, of the straight line fitting of the ER peak and DEP frequency against medium conductivity data according to the linear theory only when the intercept dominates the experimental uncertainty, which occurs when the medium conductivity is less than 1 mS/m in practice.     

Construction and operation of a microrobot based on magnetotactic bacteria in a microfluidic chip

Magnetotactic bacteria (MTB) are capable of swimming along magnetic field lines. This unique feature renders them suitable in the development of magnetic-guided, auto-propelled microrobots to serve in target molecule separation and detection, drug delivery, or target cell screening in a microfluidic chip. The biotechnology to couple these bacteria with functional loads to form microrobots is the critical point in its application. Although an immunoreaction approach to attach functional loads to intact MTB was suggested, details on its realization were hardly mentioned. In the current paper, MTB-microrobots were constructed by attaching 2 μm diameter microbeads to marine magnetotactic ovoid MO-1 cells through immunoreactions. These microrobots were controlled using a special control and tracking system. Experimental results prove that the attachment efficiency can be improved to ∼30% via an immunoreaction. The motility of the bacteria attached with different number of loads was also assessed. The results show that MTB can transport one load at a velocity of ∼21 μm/s and still move and survive for over 30 min. The control and tracking system is fully capable of directing and monitoring the movement of the MTB-microrobots. The rotating magnetic fields can stop the microrobots by trapping them as they swim within a circular field with a controllable size. The system has potential use in chemical analyses and medical diagnoses using biochips as well as in nano/microscale transport.     

冲击法测量磁特性的误差分析

磁性材料的磁特性参数的测量已成为信息化程度的重要标志,本文主要介绍了数字式冲击检流计测量静态磁性参数的原理,并且分析了在测量过程中存在的误差。     

色散条纹传感技术用于拼接镜面位移探测的仿真研究

根据色散条纹传感技术的基本原理,从物理光学的角度对色散条纹传感器(DFS)进行了模拟研究,仿真出理论干涉图形,并从中采集能量信号,拟合光强分布曲线,得出测量结果.通过比较在不同波段的采样,提出在CCD上开出窗口采集有效信号的2种方法,借以提高检测精度.色散条纹传感器的检测范围为±50μm,检测精度可以达到几十nm.