A new method for a generalized Hirota-Satsuma coupled KdV equation

In this paper, differential transform method (DTM), which is one of the approximate methods is implemented for solving the nonlinear Hirota-Satsuma coupled KdV partial differential equation. A variety of initial value system is considered, and the convergence of the method as applied to the Hirota-Satsuma coupled KdV equation is illustrated numerically. The obtained results are presented and only few terms of the expansion are required to obtain the approximate solution which is found to be accurate and efficient. Numerical examples are illustrated the pertinent features of the proposed algorithm.     

基于一元线性回归的近红外光谱模型传递研究

为解决近红外光谱分析中的模型传递问题,本研究提出了一元线性回归直接标准化算法(Simple linear regression direct standardization,SLRDS)。为验证算法的有效性,采用玉米样品的近红外光谱集进行实验,并与传统的直接标准化算法(Direct standardization,DS)、分段直接标准化算法(Piecewise direct standardization,PDS)进行比较。实验结果表明,SLRDS算法不仅能够有效消除近红外光谱仪之间的差异,很好地实现玉米样品的PLS校正模型在3台仪器之间的共享,而且与DS和PDS算法相比,具有传递性能高、模型简单及所求参数少等优点。     

Impact of gate offset in gate recess on DC and RF performance of InAlAs/InGaAs InP-based HEMTs

A set of 100-nm gate-length InP-based high electron mobility transistors (HEMTs) were designed and fabricated with different gate offsets in gate recess. A novel technology was proposed for independent definition of gate recess and T-shaped gate by electron beam lithography. DC and RF measurement was conducted. With the gate offset varying from drain side to source side, the maximum drain current (I_ds,max) and transconductance (g_m,max) increased. In the meantime, f_T decreased while f_max increased, and the highest f_max of 1096 GHz was obtained. It can be explained by the increase of gate-source capacitance and the decrease of gate-drain capacitance and source resistance. Output conductance was also suppressed by gate offset toward source side. This provides simple and flexible device parameter selection for HEMTs of different usages.     

Research on terahertz photonic crystal fiber characteristics with high birefringence

A new high birefringence photonic crystal fiber is proposed within the terahertz frequency region. It has two types of claddings, the inner is composed of six ellipse air holes arranged in a honeycomb array and the outer surrounded by circle holes. By using the full vector finite element method with anisotropic perfectly matched layers absorption boundary condition, the birefringence, chromatic dispersion and confinement loss of the fundamental mode are evaluated. The results show that the birefringence can achieve 10⁻³ when the wavelength increases from 600 μm to 900 μm. This structure will provide some reference value for the designing of high birefringence terahertz photonic crystal fiber.     

Robust image hashing with dominant DCT coefficients

Image hashing is an emerging technology of multimedia processing. This paper proposes a robust image hashing with dominant discrete cosine transform (DCT) coefficients. The proposed hashing converts the input image to a normalized image, divides it into non-overlapping blocks, extracts dominant DCT coefficients in the first row/column of each block to construct feature matrices, and finally conducts matrix compression by calculating and quantifying column distances. Many experiments are conducted and the results show that the proposed hashing is robust against normal digital operations and has desirable discrimination. Receiver operating characteristics (ROC) curve comparisons indicate that the proposed hashing is better than some notable image hashing.     

领导-跟随多智能体系统的滞后一致性

近年来,随着应用的需要和技术的发展,多智能体系统的一致性逐渐成为研究热点.在通信网络和工程应用中,由于信号传播的延迟效应,系统中智能体的状态可能表现为滞后一致.本文提出多智能体系统的滞后一致性概念,研究了有向网络环境下一阶领导-跟随多智能体系统的滞后一致性问题.通过设计合适的控制协议,利用矩阵理论和稳定性理论,获得该系统达到滞后一致的充分条件.数值模拟验证了理论结果的正确性.     

用晶格玻尔兹曼方法研究血液在分岔管中的栓塞

血液栓塞形成机理一直是学术界研究的热点.本文将以圆形刚性颗粒在分岔管中的运动模拟血液在微血管中的运动,对血液在分岔管中的栓塞现象作了初步研究.重点研究了当血管发生分岔时,血管中血液流速的变化以及血栓形成的概率.得出结论,压积越大越容易发生栓塞,压差越大越不易发生栓塞.分岔管的入口和分岔处最容易发生栓塞.血液经分岔管后,大管中的压积比小管的高.     

同伴教学法对课堂期望的影响——基于广西师范大学《电磁学》的教学实践研究

同伴教学法（Peer Instruction,简称PI）是一种基于问题的自主学习和学生之间的合作探究的教学方法．同伴教学法作为一种新的教学方式,富有成效地改变了传统的课堂教学模式,提高了学生的学习主动性和学习效果,为大学物理教学改革提供了一种新模式与借鉴．为在大学物理课程中更有效地实施同伴教学法,笔者进行了教学实践研究．研究中主要采用实验法与调查问卷法,分别以广西师大物理教育和科学教育专业作为实验班与对照班,分别采用同伴教学法与传统教学法．一是旨在对比两种教学方法对学习效果的影响,二是通过调查问卷分析同伴教学法对课堂期望的影响．结果表明同伴教学法课堂的整体学习效果明显得到了提高;实验班在课堂学习模式、课堂满意程度、师范生培养、课程改革的期望比对照班有明显提高,在课堂内容的期望上两班没有区别．     

锡基钙钛矿太阳能电池载流子传输层的探讨

锡基钙钛矿太阳能电池可避免铅元素对环境带来的污染,近年来已成为光伏领域的研究热点.本文以SCAPS-1D太阳能电池数值模拟软件为平台,对不同电子传输层和不同空穴传输层的锡基钙钛矿太阳能电池器件的性能进行数值仿真对比,从理论上分析不同载流子传输层的锡基钙钛矿太阳能电池的性能差异.结果显示,载流子传输层与钙钛矿层的能带对齐对电池性能至关重要.电子传输层具有更高的导带或电子准费米能级以及空穴传输层具有更低的价带或空穴准费米能级时,对电池输出更大的开路电压有促进作用.另外,当电子传输层的导带高于钙钛矿层导带或钙钛矿层的价带高于空穴传输层的价带时,钙钛矿层与载流子传输层界面形成spike势垒,界面复合机制相对较弱,促使电池获得更佳的性能.当Cd0.5Zn0.5S和MASnBr3分别作为电子传输层和空穴传输层时,与其他材料相比,获得了更优的输出特性:开路电压Voc=0.94 V,短路电流密度Jsc=30.35 mA/cm^2,填充因子FF=76.65%,功率转换效率PCE=21.55%,可认为Cd0.5Zn0.5S和MASnBr3是设计锡基钙钛矿太阳能电池结构合适的载流子传输层材料.这些模拟结果有助于实验上设计并制备高性能的锡基钙钦矿太阳能电池.     

光源角度对金属表面图像边缘的影响分析

在机器视觉的图像处理中影响图像优劣的因素有很多,其中光源照射角度是主要因素之一。为了得到更好的图像数据,对视觉系统中光源照射最佳角度进行了仿真分析与实验研究,实验中采用单一变量法,只改变光源照射角度,通过理论计算、模拟仿真和实验验证相结合,得到了最佳的光源照射角度。结合Sobel算法检验在最佳角度下和其他角度下的图像边缘质量,结果表明在光照角度为57.17°的倾角下图像光照数据和边缘图像表现最好。该实验结果对更深层次的图像处理和图像采集具有指导意义。