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1.
Characterizations of PSD Fractal of Porous Medium 总被引：1，自引：0，他引：1
Fractalisatermusedtodescribegeometricalobjectsthatareinvariantuponthechangeoflengthscale .Manyfrac talcharactersofscaleinvarianceonporousmediumshavebeeninvestigatedduringthepastdecades[1] .Particle sizedistribution (PSD)isafundamentalpropertyofporousmedi ums.PSDofporousmediumsiscommonlyreportedintermsofthepercentagesofvariousparticle sizeintervalsandhasusuallybeenfoundtoobeypowerscalingofthetype[2 ] N(≥d)∝d-Dp (1)whereN(≥d)isthenumberofparticlediameterlargerthanorequaltod ,andthepow… 相似文献
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A laser shaft alignment system with dual PSDs 总被引：3，自引：0，他引：3
INTRODUCTION Precise alignment occurs when the centerlines of rotation of two shafts are essentially collinear with each other. The degree to which two machines are misaligned can be determined by examining the amount of offset and angularity that exists between them. Offset is the distance between the two rota- tional centerlines, and angularity is the angle between the centerlines created by the misalignment of the two centerlines. The traditional precise shaft alignment method is dial … 相似文献
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汪洁 《实验室研究与探索》2005,24(10):79-80
双频激光干涉仪是现代精密测量中最精密的测量仪器之一。文章介绍了双频激光干涉仪的实验内容和方法，以及在实验教学中激发学生兴趣和求知欲，提高学生综合能力的实践经验。 相似文献
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本文提出一种改进的幅度比较式无线电测向体制及测向算法,给出了在某手持测向设备中的应用结果．该测向体制及算法可抵消掉由硬件电路、人体干扰及环境等因素对天线方向图造成的影响,具有测向速度快、抗干扰能力强等优点,可广泛应用于各种手持式测向设备． 相似文献
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A new type of real-time holographic three-slit interferometer is presented.It uses a calcite polarized optical element to obtain objective light and reference light to record a hologram.Its remarkable feature is to use a beam of fixed slit diffracted light as the reference light to record the lateral slit diffracted wave front,and to use also the same diffracted light as the illuminating light to reconstruct the wave front.This insures the phase distribution of the reconstructed wave front against the influence by the small natural direction drift of the laser beam and also by the tiny external vibration.The stabillity,reliability and measuring accuracy of this apparatus are improved notably. 相似文献
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通过对VMCL600型立式加工中心三轴误差元素的误差分析,建立其几何误差的数学模型,并在建模过程中消除了不确定的假设条件,使其求解简便、通用性好。同时,利用激光干涉仪对VMCL600立式加工中心沿三个坐标方向测量9个运动方向的精度误差值和相应9项直线度误差值,并保证直线度误差测量与位移误差测量在同一直线上进行,提高了数控机床误差的辨识精度和测量效率。 相似文献
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提出了一种基于坐标测量机、测头回转体和激光三角法测头的非接触三维测量系统 ,并介绍了测量系统的工作原理 .同时给出了采用标准球对测量系统进行标定的方法 ,建立了测量系统的数学模型 ,还对白纸样板曲面进行了实际测量 相似文献
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Cong-jing REN Jing-dai WANG Di SONG Bin-bo JIANG Zu-wei LIAO Yong-rong YANG 《浙江大学学报(A卷英文版)》2011,12(4):260-267
Particle size distribution (PSD) is an important parameter in the process of fluidization, and it always plays a crucial role
in a gas-solid fluidized system. A PSD model for on-line PSD determination based on acoustic emission (AE) measurement was
developed according to the mechanism of particle collision with the inner wall of the cylinder and multi-scale wavelet decomposition
analysis. This PSD model illuminates the quantitative relationship between the energy percentage of AE signals for different
scales and the PSD, which indicates the feasibility of the application of the PSD model. Experiments were undertaken both
in lab and plant gas-solid fluidized setup with polyethylene particles, and the parameters of the PSD model were calibrated
and revised. The experimental conditions and results proved that the PSD model was suitable for on-line measurement and was
sufficiently sensible and accurate. Concerning agglomeration, the PSD model also showed exact serviceability on detecting
the onset of agglomeration by abnormal PSD, and the result agreed with that from the radiation method. Ultimately, AE measurement
was found to be a reliable and credible means for understanding the PSD information that affects the behavior of a system,
which can provide valuable guidance for practical applications. 相似文献
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针对工科院校车刀几何角度测量实验中存在的问题,从教学目标出发分析了车刀几何角度测量仪应具有的目标功能,在此基础上研制了多功能车刀几何角度测量仪,并进行了实验验证。该测量仪具有参考坐标系的建立、车刀几何角度测量和车刀纵横方向进给等多种功能,便于学生对金属切削刀具知识的学习、理解和掌握。 相似文献
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A precise aperture measuring system of small deep holes with capacitance sensors is presented. Based on the working principle of non-contact capacitance sensors, influence of the edge effect of gauge head is studied, and one capacitance sensor for measuring the aperture of the small blind holes or through holes is introduced. The system is composed of one positioning device, one aperture measuring capacitance sensor, one measuring circuit, and software. This system employs visual CCD and two-dimensional micro-adjusting mechanism to realize the precise positioning. By LabView software this system is controlled to run automatically, to carry out calibration and automatic data collection, and to make data import into the database directly. Experiments proved that the diameter measurement range of the system can be 1.8 mm—7 mm, the resolution can be up to 5 nm—10 nm, the repeatability measurement standard deviation can be 0.05 μm—0.1 μm, and the measurement uncertainty can achieve 0.15 μm—0.3 μm. So the measuring system can realize the nanometer-level measurement. 相似文献
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位置传感器(Position Sensitive Detector,PSD)广泛应用于精度较高的非接触测量中,特别是在激光三角法微位移测量中,常采用PSD作为位置敏感元件感测光线的微小偏移。本文分析了PSD的原理和性质,并设计了PSD的信号处理电路,同时设计了微小信号电流的流压转换电路,将微弱的电流信号转换为电压信号,满足了后续信号处理模块的要求,电路存在的噪声控制在±0.8mV内,使整体测量系统的分辨力达到80nm。 相似文献
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提出了一种基于矢量伏安法测量原理的便携式阻抗测量装置,并分析了磁耦合谐振式无线电能传输中耦合线圈结构阻抗测量电路的设计原理,通过单片机系统控制AD5933阻抗转换器测量待测谐振耦合结构的阻抗,利用串口通讯协议实现LabVIEW软件和单片机系统的相互通讯。实验结果表明,耦合线圈工作在谐振态下,阻抗测量值与理论阻抗值相对误差为2%,成本较低,便于携带,能够满足大部分耦合线圈设计需求。 相似文献
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A system for measuring the quality parameters of elevator guide rails is developed. The quality parameters the system can measure include straightness, flatness, squareness, width and height of the rail. The system consists of six parts:main guideway, auxiliary guideway, reference rail, saddle, control casing and measured rail. The guide rail to be measured is mounted on a bed. The straightness errors of surfaces are checked by five linear displacement sensors mounted on the saddle. The deviation of readings from the sensor, which is in contact with top guiding surface, gives the straightness error of the surface and height of the rail. The other four sensors are used to measure side guiding surfaces respectively and give other parameters including flatness on the surfaces, squareness, width and height of the rail. A novel calibration method is also developed to calibrate the straightness motion error of the system in horizontal and vertical directions. The deflection deformation of the measured rail is fitted by using a fourth-order polynomial. Experimental results show that the uncertainty of the system on the side surfaces after compensating the straightness motion error is less than 0. 01 mm, and the uncertainty of the system on the top surface after compensating the straightness motion error and the deflection deformation of the rail is less than 0.03 mm. 相似文献
15.
介绍了一种基于LabVlEW的Mach-Zehnder光纤干涉仪闭环工作点控制系统。详细阐述了用LabVlEW实现的基本思路,并对两种不同情况下的检测结果进行了比较。 相似文献
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The resonant tunneling diode (RTD) is an ultra-highspeed and ultra-high frequency quantum-transport deviceaccompanied with negative differential resistance (NDR)I-Vcharacteristic originating fromresonant tunneling effect .The core structure of RTDis doubl… 相似文献
17.
盛爱兰 《洛阳师范学院学报》2013,32(2):61-62
大学物理实验中,金属杨氏弹性模量的测定方法主要为光杠杆法,但该法存在调节比较困难、读数过程存在视差、成本高等不足.本文设计了一种利用激光管测定金属杨氏模量的简易装置,成本低廉且操作简单,准确度较高. 相似文献
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迈克尔孙干涉仪定域干涉光程差和波长的讨论 总被引：1，自引：0，他引：1
该文推导出迈克尔孙干涉仪定域干涉各种情况下光程差的通用公式,通过实验对光波波长的测定进行讨论,并在此基础上提出了进一步提高光波波长测定精度的有效途径。 相似文献
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以双CCD技术构成的交汇测量系统因其结构简单、使用方便、测量精度高、测量速度快等诸多优点，而广泛应用于现代靶场中各种动态飞行目标的跟踪测量。在介绍线阵CCD交汇测量原理的基础上，重点分析了坐标测量精度与交汇系统各结构参数之间的关系，并利用计算机仿真技术对系统的布站方式进行优化设计。仿真结果表明：在给定靶面尺寸及各结构参数测量误差的前提下，通过仿真计算可以得到使系统坐标测量误差最小的最佳布站方式。 相似文献