Subjects: Geosciences >> Space Physics submitted time 2017-03-10
Abstract：为了实现对不同频率超声波信号的高速采集，提出了一种基于可编程滤波器、USB2.0和C#的接收频率可调的超声波信号接收与采集系统设计方案，并完成了系统的软硬件设计。该系统的硬件部分主要用来数字量化模拟信号并将其上传至上位机，软件部分采用C语言和C#编程，以实现数据的正常采集与上传保存。实际应用表明，该系统具有操作简便、测试准确、使用灵活的特点，达到了设计要求。
Peer Review Status:
Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2017-03-10
Abstract：传统接触测量的方法无法对高温范围的金属材料的热膨胀系数进行测量，结合静电悬浮无容器技术和图像测量方法， 通过半导体激光器加热悬浮的样品，在加热的过程中利用CCD采集悬浮样品的图像，采用方向梯度算法提取图像中样品的边缘， 并利用球谐函数拟合样品的体积，计算得到材料在不同温度下的热膨胀系数。采用纯锆的金属材料样品进行实验，在 750-1800℃的温度范围内，测量得到固态样品锆的热膨胀系数随温度变化的表达式，验证了该测量方法的有效性和精度。
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2017-03-10
Abstract：随着材料研究逐渐深入，材料制备和材料分析的方法越来越重要，然而，一些重要的物理性质是开展相关研究的基础。 由于一些材料熔点高、难熔化，同时，传统手段无法避免容器壁的污染，或者无法在真空条件下进行试验避免气体的污染， 或者由于实验性质原因只能测量特定的材料；这些方法很难测量材料在高温下过热过冷阶段的热物理性质。本文系统介绍了 静电悬浮技术这种新型的实现深过冷的方式，达到对材料热物理性质进行测量的目的。静电悬浮技术使样品在两极板间悬浮， 在悬浮的状态下采用激光对样品进行加热，使材料达到高温熔化，同时进行热物性的测量。本文对比了几种实现测量典型热 物理性质的方法，了解静电悬浮的优势，以及详细地介绍了静电悬浮技术对材料的熔体密度、热膨胀系数、表面张力和粘度 系数以及比热的测量。
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-05-13
Abstract： A measurement and control system of three-dimensional(3D) position information of electrostatic levitation based on position sensitive detector(PSD) is setup and structure of PSD and position measurement and control principle of electrostatic levitation are analyzed.Output signal of PSD is processed by STC12C5A60S2 MCU,corresponding relationship between suspension sample position information and output voltage of PSD is obtained,and communication between MCU and upper PC,data analysis and processing,and position control on levitation sample are realized.Use zirconium materials to carry out suspension experiment and test results indicate that the system can realize non-contact measurement of sample position information and stable suspension of sample,and it has advantages of stable operation and reliable detecting data,and so on,and this measurement system laid foundation for material suspended heating and undercooling research.
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-05-13
Abstract： The production and measurement system of uniform axial hypomagnetic field based on Silicon Labs C8051F005 micro-processor is designed for the research on biological effects of the hypomagnetic field. A new structure for producing uniform axial hypomagnetic field is suggested according to the principle of magnetic field generated by Helmholtz coil. MAX038 is used for hardware circuit to generate the alternating magnetic field. The magnetic field can be accurately measured by magnetoresistive sensor, the data of which are transferred to the host computer via serial port, and then displayed graphically in real time. The uniformity of the magnetic field generated with the new structure is experimentally demonstrated to be better than that generated with Helmholtz coil. Experiments show that the magnetic field intensity is proportional to the current, and has the well controllability. The frequency of alternating magnetic field can be controlled by simple parameter setting.
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-04-22
Abstract： In this paper,in order to realize the high-resolution spectral measurement of low light,we propose a new spectral measurement method which is based on a digital micro-mirror device (DMD) and a photoelectric multiplier tube (PMT). Firstly, the spectrum of the measured light is imaged on a DMD by the dispersive optics system based on a small-size slit. Secondly, by the rotation of the micro-mirrors of the DMD per column,the spectrum is reflected to a PMT according to the different wavelengths. Lastly, the measurement of the spectrum is achieved through the scanning mode. The contrast experiments of our method and a charge-coupled device (CCD) spectrometer are performed,and the experiments for different low light conditions are also performed. At last,the signal-to-noise ratio (SNR) experiment of the system is conducted. The results show that the spectral resolution is 0.23 nm,the sensitivity of the spectral system is less than 4.6 pW,and the SNR performance is also perfect. Compared with the conventional spectroscopy technique, this spectral measurement method has the merits of low price, easy implementation and stable performance.
Peer Review Status:Awaiting Review
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