共查询到20条相似文献,搜索用时 62 毫秒
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系统以FPGA为核心,通过对正弦信号进行滤波、放大整形后得到标准的方波,由FPGA对其频率、周期及相位差进行测量.频率、周期测量采用等精度测量法,其具有精度高的特点;.相位差测量采用鉴相器分辨出相位差后测量其高电平所占比例测量.摒弃传统的FPGA+单片机方案,利用SOPC Builder在FPGA上构建Nios Ⅱ处理器对测量的数据进行数据处理及显示,实现了频率、周期、相位差测量的片上系统(SOPC),提高了系统的稳定性、降低了布线难度. 相似文献
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针对旋转动力机械扭矩的测量方法进行了研究。利用虚拟仪器技术,采用非接触测量方式,通过相关法相位差测量算法获得扭转角大小,实现了扭矩的测量。这种扭矩测量方法减少了复杂的硬件电路,提高了系统的可靠性和测量精度。测量实例的应用验证了该测量方法的正确性和适用性。 相似文献
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为了提高扭矩的动态实时测量能力,采用光电多码道技术进行扭矩测量,提出了基于DSP和现场可编程门阵列(FPGA)的多通道实时采集系统.通过多路方波信号细分计数周期,分析比较多路信号的状态变化特征并将比较结果作为计数依据,以实现对数据快速精确的采集.该系统通过FPGA实现逻辑控制、计数和存储并将接收到的数字信号传输给DSP,DSP将信号处理后传送至上位机以实现数据的存储、分析及显示.该系统采集速度快、精度高、结构简单. 相似文献
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智能型在线力矩测量以微计算机为核心,配用相位差式转矩转速传感器,自动校零,自动测量离合器正,反制动力矩,结合测试系统的传递函数提出了离合器动态力矩测量中动态补偿的设计方法。 相似文献
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针对丘陵山区小型农业机械扭矩测量过程中存在的传感器安装空间受限、现场布线困难等问题,基于应变检测原理和无线传输技术设计了一种动态扭矩测量系统。重点研究了应变信号采集电路、信号放大电路、A/D模数转换电路和无线通信模式,并通过所建立的单变量线性回归模型对静态标定试验数据进行了处理。结果表明:该无线扭矩测量系统灵敏度为0.8 mV/(N·m),非线性误差为1.54%,重复性误差为0.19%,拟合度可决系数R~2=0.999 0,可实现动态扭矩的实时监测。 相似文献
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基于Altera公司FPGA芯片,提出了一种基于双频激光干涉仪系统中数字相位计的实现方法。该相位计用于测量系统中被测信号和参考信号之间的相位差角度,间接测量激光干涉仪的光程差信息。被测信号经过光电接收器以及A/D模数转换成数字信号送到FPGA芯片中,与FPGA内建的查找表参考信号做正交相关法解调运算,得到一组X-Y值,再利用CORDIC算法计算arctan函数获取相位差,最后计算出干涉仪的光程差,算法的全过程使用FPGA硬件实现。实验结果表明,该相位计使双频激光干涉仪的相位差测量精度在0.01°以内。 相似文献
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C. MAURER A. JESACHER S. FÜRHAPTER S. BERNET & M. RITSCH-MARTE 《Journal of microscopy》2008,230(1):134-142
We present the implementation of a spiral phase plate in a standard bright-field microscope to enhance the contrast of phase and amplitude samples. The method can be employed in all types of microscopy where standard phase contrast methods are applicable, for example, in bright-field transmission or reflection microscopy using an illumination source with partial spatial coherence. The spiral phase filter is placed into an accessible Fourier plane of the imaging path of the microscope. It is shown that this produces not only a strong contrast enhancement but in theory also improves the spatial resolution of the microscope for white light. A series of different set-ups for transmissive or reflective samples, including epi-illumination, are presented to demonstrate the practical range of applications of this contrasting method. A minute shift of the spiral phase plate out of the centre results in relief-like images that are similar to those obtained by differential interference contrast microscopy. A series of such relief-like images can be numerically processed to obtain quantitative phase and amplitude information of the sample. 相似文献
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Simultaneous phase and amplitude extraction from a single defocused image of a homogeneous object 总被引:3,自引:0,他引:3
D. Paganin† S. C. Mayo T. E. Gureyev P. R. Miller & S. W. Wilkins 《Journal of microscopy》2002,206(1):33-40
We demonstrate simultaneous phase and amplitude extraction from a single defocused image of a homogeneous object. Subject to the assumptions explicitly stated in the derivation, the algorithm solves the twin‐image problem of in‐line holography and is capable of analysing data obtained using X‐ray microscopy, electron microscopy, neutron microscopy or visible‐light microscopy, especially as they relate to defocus and point projection methods. Our simple, robust, non‐iterative and computationally efficient method is applied to data obtained using an X‐ray phase contrast ultramicroscope. 相似文献
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快速准确获得振动信号的相位、幅值二特征量具有重要工程意义。本文提出了一种无需整周期采样、无需锁相环和复杂电路硬件的相位检测算法。该算法基于互功率谱估计,具有算法复杂度低、精确度高、适用频率范围广等优点。在该算法基础上又提出了一种相位补偿滤波算法,使信号经滤波后相位保持不变。该方法的运算量低,适于在线实时滤波;相位补偿准确度高,误差在1°以内。综合上述两算法构成的信号特征量检测方法,可以准确、快速地提取振动信号的相位及幅值。最后本文将上述方法应用于旋转机械自动平衡,结果表明两算法可以在线、准确地实现,并且能够达到较好的平衡效果。 相似文献
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基于最小二乘圆圆度测量方法,采用差动变压器作为位移测量元件,结合单片机技术,设计了可自动检测工件圆度的单片机系统。该系统结构简单,价格低廉,使用方便,可满足高精度测量要求。 相似文献
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We report the visualization of the wavefronts of light in the focal region of an objective lens. The focused wavefronts are measured for the highest available numerical aperture, i.e, 1·4 oil immersion. The measurement is accomplished by scanning a scattering probe through the focal region of a lens illuminated by plane waves. The scattered light is coherently added to an external reference beam and focused into a point-like detector. The registered signal allows the determination of the three-dimensional shape of the wavefronts in the focal region and their evolution in time. 相似文献
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Interpenetrating phase composites (IPCs) – composites in which each phase forms a completely interconnected network – are becoming an important class of materials as the result of the development of a number of new techniques for producing composites with interpenetrating microstructures. In this paper, the mechanical properties of two-phase IPCs are modelled. Finite element analysis is used to investigate elastic, strength, and thermal expansion properties of IPCs. The numerical results are compared with the properties of composites with non-interpenetrating microstructures. For the specific microstructures investigated, it is found that a composite with an interpenetrating microstructure can possess enhanced thermo-mechanical properties. The enhanced properties may result more from the contiguity of the phase with more advantageous properties than from the interpenetrating microstructure. 相似文献
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We present a simple and versatile scheme for characterising amplitude and phase modulation by an active element, such as a deformable mirror, in the pupil plane of a high NA microscope. By placing a mirror in the vicinity of the focal plane of the objective and recording images of the reflected focal spot on a camera, we show that reliable measurements of the influence function of the mirror actuators in the pupil plane of the objective can be obtained using an iterative electric field retrieval algorithm. Compared to direct wavefront sensors, the proposed method allows characterisation for a variety of objectives with different NA and pupil sizes without modification of the setup, requires minimal space inside the microscope, and can be used with pulsed sources such as used for multiphoton microscopy. In order to validate our method, we compare our data to the results obtained with a Shack-Hartmann wavefront sensor, and show that comparable precision is achieved. 相似文献
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针对某型号火星熄灭器,采用非定常雷诺时均(RANS)和离散型模型(DPM)对其内部流场和颗粒分离行为进行了数值模拟.计算了初始模型设计流速下的捕集效率和阻力损失;分析了内部速度场、压力场和颗粒运动轨迹特性.针对计算结果,对原火星熄灭器的结构进行了改进.采用相同的计算方法,对改进后的设计方案进行了仿真计算,结果表明提高了火星熄灭器的综合性能.该仿真计算方法能较好地预测火星熄灭器内部两相流的流动特性,对火星熄灭器性能预测和结构改进提供可靠依据. 相似文献
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介绍一种新型测量气/固两相流固相浓度的螺旋极板电容传感器,并通过实验得出提高传感器检测场灵敏度空间分布均匀性及克服边缘效应对检测精度影响的方法。 相似文献
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Multi-plane phase retrieval is a well established technique for reconstructing both, amplitude and phase of an object wave. This standard technique works best, if the intensity of the object wave changes rapidly along the optical axis. For slowly varying intensities, the iterative procedure may not converge at all. To overcome this limitation we combined the standard technique with a periodic phase element. We demonstrate that a binary diffractive micro lens array with overlapping aperture significantly improves the convergence of phase retrieval and thus the quality of reconstruction. Thus multi-plane phase retrieval can be applied for both rough and smooth phase distributions. 相似文献