拉曼光谱技术在宝石学研究中的应用

拉曼光谱技术已被成功地应用于宝石学研究和宝石鉴定领域。拉曼光谱技术可以准确地鉴定宝石内部的包裹体,提供宝石的成因及产地信息,并且可以有效、快速、无损和准确地鉴定宝石的类别——天然宝石、人工合成宝石和优化处理宝石。但是,该技术也存在着一定的局限性。     

铝合金稀土转化膜成膜工艺研究

应用正交实验设计 ,开发并研究了LY1 2铝合金 4价铈盐转化膜的成膜工艺及其膜层的耐蚀性能 .实验表明 :经稀土转化处理的铝合金其点蚀电位升高 ,自然腐蚀电位有所降低 ,从而降低了点蚀敏感性 ;试样极化阻力提高 70倍以上 ,耐蚀性能大大提高 ,与铬酸盐相当 ;另外 ,还结合电化学测试和表面分析 ,初步探讨了铝合金稀土转化膜的耐蚀机理     

On the nonlinear slewing dynamics and control of the Space Station based Mobile Servicing System

A relatively general Lagrangian formulation for studying the nonlinear dynamics and control of space-craft with interconnected flexible members in a tree-type topology is developed. Versatility of the formulation is illustrated through a dynamical study of the Space Station based two-link Mobile Servicing System (MSS). The performance of the MSS undergoing inplane and out-of-plane slewing maneuvers is compared. Results indicate that, in absence of control, the maneuvers induce undesirable librational motion of the Space Station as well as vibration of the links. Nonlinear control, based on the Feedback Linearization Technique (FLT), appears promising. Quasi-Closed Loop Control (QCLC), a variation of the FLT, is applied to control the libration of the Space Station. Once the attitude of the Space Station is controlled, the performance of the MSS improves significantly. For a 5-minute maneuver of the MSS, the maximum control torque required is only 34.5 Nm.Nomenclature f _i ¹ , f _i,j ¹ fundamental frequency of bodies B _i and B _i,j, respectively - l _c, l _i, l _i,j length of bodies B _c, B _i, and B _i,j, respectively - m _c, m _i, m _i,j mass of bodies B _c, B _i, and B _i,j, respectively - % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXafv3ySLgzGmvETj2BSbqefm0B1jxALjhiov2D% aebbfv3ySLgzGueE0jxyaibaiGc9yrFr0xXdbba91rFfpec8Eeeu0x% Xdbba9frFj0-OqFfea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs% 0dXdbPYxe9vr0-vr0-vqpWqaaeaabiGaciaacaqabeaadaqaaqGaaO% qaaerbhv2BYDwAHbacfiGab8xCayaaraqefavySfgDP52BGWuAU9gD% 5bxzaGGbciaa+zgacaWFSaGaa8hiaiqa-fhagaqeaiaa-jhaaaa!4B1F!\[\bar qf, \bar qr\] vector representing flexible and rigid generalized coordinates - % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXafv3ySLgzGmvETj2BSbqefm0B1jxALjhiov2D% aebbfv3ySLgzGueE0jxyaibaiGc9yrFr0xXdbba91rFfpec8Eeeu0x% Xdbba9frFj0-OqFfea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs% 0dXdbPYxe9vr0-vr0-vqpWqaaeaabiGaciaacaqabeaadaqaaqGaaO% qaaerbhv2BYDwAHbacfiGaa8hkaiqa-fhagaqeaiaa-jhacaWFPaqe% favySfgDP52BGWuAU9gD5bxzaGGbciaa+rgaaaa!4A18!\[(\bar qr)d\] vector representing the desired rigid generalized coordinates - (I _xx)k, (I _yy)k, (I _zz)k principal inertia of body B _k about X _k, Y _k, and Z _k axes, respectively; ksc, i or i, j - K _p, K _v displacement and velocity gain matrices - N _q total number of generalized coordinates - % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXafv3ySLgzGmvETj2BSbqefm0B1jxALjhiov2D% aebbfv3ySLgzGueE0jxyaibaiGc9yrFr0xXdbba91rFfpec8Eeeu0x% Xdbba9frFj0-OqFfea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs% 0dXdbPYxe9vr0-vr0-vqpWqaaeaabiGaciaacaqabeaadaqaaqGaaO% qaaerbwvMCKfMBHbacfiGab8xuayaaraqefavySfgDP52BGWuAU9gD% 5bxzaGGbciaa+zgaieaacaqFSaGaa0hiaiqa-ffagaqeaGqaciaa8j% haaaa!4AEF!\[\bar Qf, \bar Qr\] control effort vectors for flexible and rigid coordinates, respectively - Q , Q , Q control effort for pitch, roll and yaw degree of freedom, respectively - _k ^y , _k ^z tip deflection of a beam type appendage (B _k) in the Y _k and Z _k directions, respectively.     

《微波技术与天线》教学的研究与探讨

通过对《微波技术与天线》这门课的特点与主要内容的分析,针对传统教学中出现的一些问题提出了相应的改革措施。对该课程的教学方式、教学方法等方面进行了探讨与研究。实际教学效果证明,该系列改革措施增加了学生的学习兴趣和热情,教学效果良好。     

Narrow pulse formation using nonlinear LC ladder networks

Soliton propagation in a nonlinear lossy LC ladder network has been studied. We propose a quadratic polynomial expression to model the C-V characteristic of the nonlinear capacitor of the LC ladder network. This fits the experimental C-V data better over a wider range of the applied voltage, compared with the conventionally used formulae.

Using this C-V expression, the Korteweg-de Vries (KdV) equation with a loss term has been obtained. This nonlinear equation has been solved by employing a novel technique that is based on Fourier series analysis. We have investigated the effects of bias voltage on the soliton pulse width and peak voltage and found a good agreement between the theoretical and experimental results.     

SQP技术与广义投影相结合的次可行方向法

本文建立非线性不等式约束优化的一个新算法，分析和证明了算法的整体收敛性和超线性收敛性。其技巧在于将广义投影和ＳＱＰ技术结合使用。     

Razumikhin Type Theorems on Boundedness

ＲａｚｕｍｉｋｈｉｎＴｙｐｅＴｈｅｏｒｅｍｓｏｎＢｏｕｎｄｅｄｎｅｓｓＺｈａｎｇＳｈｕｎｉａｎ（张书年）（ＤｅｐａｒｔｍｅｎｔｏｆＡｐｐｌｉｅｄＭａｔｈｅｍａｔｉｃｓ，ＳｈａｎｇｈａｉＪｉａｏｔｏｎｇＵｎｉｖｅｒｓｉｔｙ，Ｓｈａｎｇｈａｉ，２００２４...     

Quintic spline technique for time fractional fourth‐order partial differential equation

Higher order non‐Fickian diffusion theories involve fourth‐order linear partial differential equations and their solutions. A quintic polynomial spline technique is used for the numerical solutions of fourth‐order partial differential equations with Caputo time fractional derivative on a finite domain. These equations occur in many applications in real life problems such as modeling of plates and thin beams, strain gradient elasticity, and phase separation in binary mixtures, which are basic elements in engineering structures and are of great practical significance to civil, mechanical, and aerospace engineering. The quintic polynomial spline technique is used for space discretization and the time‐stepping is done using a backward Euler method based on the L1 approximation to the Caputo derivative. The stability and convergence analysis are also discussed. The numerical results are given, which demonstrate the effectiveness and accuracy of the numerical method. The numerical results obtained in this article are also compared favorably well with the results of (S. S. Siddiqi and S. Arshed, Int. J. Comput. Math. 92 (2015), 1496–1518). © 2016 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 33: 445–466, 2017     

Validation of LES predictions for turbulent flow in a Confined Impinging Jets Reactor

This work focuses on the prediction of the turbulent flow in a three-dimensionial Confined Impinging Jets Reactor with a cylindrical reaction chamber by using Large Eddy Simulation. Three-dimensional unsteady simulations with different sub-grid scale models, numerical schemes and boundary conditions were performed for various flow rates, covering different flow regimes. First, a qualitative analysis of the flow field was carried out and then predictions of the mean and fluctuating velocities were compared with micro Particle Image Velocimetry data. Good agreement was found both for the mean velocity components and the fluctuations. For low to moderate Reynolds numbers the sub-grid scale model was found not to be very relevant, since small scales are of less importance, as long as scalar transport and chemical reaction are not in play. An important finding is the good prediction of the high velocity fluctuations detected in particular at higher Reynolds number due to the natural instability of the system, strongly enforced by the jets unsteadiness.     

Monotone Method for Second Order Periodic Boundary Value Problems and Periodic Solutions of Delay Difference Equations

In this article, we employ monotone iterative technique to study the existence of solutions for second order periodic boundary value problem and periodic solutions of delay difference equations.