基于Matlab示波器原理的演示

利用Matlab简洁的语句表达方式和强大的绘图能力,实现示波器扫描方式、同步问题和李萨如图形的演示.该研究不但可以帮助学生加深对示波器工作原理理解,同时也可以提高示波器实验教学效果.     

Information for Authors

正Chinese Optics Letters is a short-article journal for the rapid dissemination of new,i mportant results in all branches of optical science and technology and related fields,published monthly by Chinese Laser Press and distributed abroad by the Optical Society(OSA).Submission of Papers     

石英晶体碱(KOH)腐蚀像及其与酸(HF)腐蚀像对比研究

本文用KOH溶液对石英晶体进行腐蚀实验.对石英晶体不同结晶学方向的5个品面(切面)的腐蚀像进行观察,建立了石英碱腐蚀形貌的立体模型,并与酸(HF)溶液所腐蚀的同样5个面的腐蚀像进行对比.研究发现碱腐蚀与酸腐蚀在柱面{1010}和菱面{1011}、{0111}上有很人不同,在柱切面{1120}、{2110}上有相同之处.但它们都反映各品面及晶体的对称特点.该研究对揭示矿物晶体在不同酸碱地质环境下腐蚀的特点具有指导意义.     

The mixed volume optimization problem

The mixed volume optimization problem is to determine the point of duality Q for a given convex set K that minimizes the “mixed volume” of the associated polar set (K^*;Q). In the plane, the mixed volumes translate as the area and length; in space, the mixed volumes include the volume, surface area, and mean width. In this paper, the geometric optimization problems associated with minimizing mixed volumes are examined from two perspectives: enumerative search and symbolic computation. The problem of minimizing the polar area through an enumerative search is first considered. The dual polygon (P_m^*;Q) is constructed for an arbitrary point of duality QP_m° by using an algebraic correspondence between the edges of P_m and the vertices of (P_m^*;Q), and the area of (P_m^*;Q), A(P^*_m;Q), is calculated and minimized using naive search techniques. A result due to Santaló is applied to verify the minimizing solution, and computational tests are described for various classes of randomly generated polygons. Statistical evidence indicates that a “good” approximation to the minimum area polar polygon occurs when the duality point is located at the center-of-gravity of P_m. The polar area problem is then investigated using symbolic procedures. Explicit symbolic expressions for the polar area and length functionals are computed and solved directly using the differential optimality conditions and Newton's iterative method of solution. The mixed volume and surface area functionals are formulated and solved using numerical products, and the mean width functional is described. Examples are used throughout to illustratethe methodology.     

李萨如图在捷联惯导系统圆锥误差估计中的应用

分析了激光陀螺捷联惯导系统产生圆锥运动的原因，给出了估计圆锥误差的一般方法，并在此基础上给出了一种简单、实用的方法-李萨如图法，后比前更加接近工程应用。最后给出了验证试验结果。     

Experimental Considerations for Temperature Modulated DSC at Low Temperature

Temperature modulated DSC (TMDSC) at low temperatures requires attention to the selection of experimental parameters that are within the capability of the instrumentation as well as special care in calibration of heat capacity measurement when high precision is required. Data are presented to facilitate selection of appropriate modulation periods and amplitudes at low temperature when using a mechanical cooling accessory. The standard error of the mean heat capacity measurement for a sapphire standard increased with decreasing temperature, decreasing period, and increasing pan mass. For ice in hermetically sealed pans, the standard error of the mean heat capacity measurement was larger than for sapphire and did not follow a predictable trend with changes in temperature and period of modulation. This was attributed to changes in sample geometry between successive measurements due to melting and resolidification. A simple one-point temperature calibration by TMDSC may be unsuitable for precise measurement of heat capacity because of the random error caused by sample placement and the systematic error caused by cell asymmetry, temperature dependence of the calibration constant, and different sample thermal conductivities. An alternative calibration procedure using standard DSC and either a linear or second order fit of the calibration constant over the temperature range of interest is proposed. This revised version was published online in August 2006 with corrections to the Cover Date.     

General Phase-stepping Algorithm Using Lissajous Figures Technique

A new phase-stepping algorithm is proposed, the algorithm can be implemented without knowing or calculating the phase steps. New phase extraction expressions based on using Lissajous figures and ellipse fitting are derived by introducing a simple difference transform for the intensity of the interferograms. The simulating results indicate that the new algorithm is insensitive to phase-stepping errors and the accuracy of the new algorithm is only limited by the computation truncation errors.