对二分法求函数零点近似值的教学思考

“函数的零点”是上海教育出版社高中一年级第一学期3．4节“函数的基本性质”中的内容,教学要求为：使学生理解用“二分法”求函数零点的算法思想,会借助计算器求函数零点的数值解．笔者在研究教材相关内容的过程中,发现一些值得思考的问题．     

气轨上单摆的混沌实验

设计并自制了一个气轨上单摆的混沌演示装置,建立了系统的动力学方程,直观地显示了混沌的一些基本特征。     

抵押贷款信用违约互换的定价

在结构化方法框架下,用偏微分方程方法,对抵押贷款的信用违约互换进行定价.给出了形式解,并进行数值计算和参数分析.     

基于显微光杠杆技术的微结构偏转角测量系统

针对微结构的偏转角度测试需求,设计并搭建了一套基于显微光杠杆技术的角度测量系统。该系统将光杠杆光路与无限共轭显微光路相结合,所得聚焦光斑直径小于10μm;采用电流模式电路处理四象限探测器输出信号,系统理论带宽超过5MHz;系统对微结构的转角测量分辨力和理论量程分别可达1.2″和±4°。利用该系统测量了原子力显微镜微悬臂梁探针在步进载荷下的偏转情况,测量结果与铁摩辛柯梁理论计算一致,验证了系统的可靠性。     

例说在高中数学教学中的审题训练

在高中数学学习中,审题不清是学生有效解题的第一障碍．特别在解析几何的解题过程中,因为由文字、数式、图形等数学语言堆砌的问题抽象而繁复,且层层设套,使学生眼花缭乱,无从下手,或一不小心走了弯路．笔者就抛物线教学中的一个实例,对课堂教学中学生审题能力的培养进行了思考．     

ZnTe晶体中光学整流产生的THz辐射及其电光探测研究

借助抽运-探测技术研究了ZnTe晶体中光学整流产生的太赫兹(THz)辐射，利用ZnTe晶体的线性电光效应探测THz辐射场分布，观察到了较窄(约为0.2 ps)的THz场分布及相应较宽(响应超过4 THz，半峰宽约为2.4 THz)的THz频谱，并运用琼斯矩阵对实验结果进行了理论拟合. 研究了飞秒激光脉冲波长(750—850 nm)、脉冲宽度(56—225 fs)和晶体旋转与THz辐射产生的关系. 同时改变探测光偏振方向进行偏振调制，并从理论上分析了偏振调制对THz辐射探测的影响. 关键词： THz辐射 光学整流 电光探测 ZnTe     

中美高中数学教材之函数与不等式部分的对比与融合

在教育全球化的背景下,随着课程改革的进行,各国都希望从其他国家借鉴到有益的经验,教材的国际比较成为教育研究的热点.当前普遍认为,我国数学教育注重培养基础知识和基本技能,美国教育擅长对学生创新意识和应用能力的培养.对两国高中数学教材进行比较分析的目的在于发现不同教材之间的具体差异,揭示各自的优势和不足,取长补短,提高我国的数学教育.     

Production of ZnO Nanobelts and Meso-Scale Study of Mechanical Properties

We investigate a peculiar phenomenon by processing ZnO nanobelts with an atomic force microscope （AFM）. In the contact mode of AFM, peculiar bending occurs in meso-scale when the nanobelt is applied with force in lateral direction. We study the mechanical properties of ZnO nanobelts under the influence of small size effect, with finite element analysis and mathematical analysis by means of Matlab. Based on this abnormal effect, a novel measuring method is proposed, which allows the surface morphology and surface properties to be characterized at the same time.     

Effect of electrical contact on performance of WSe2 field effect transistors

Two-dimensional (2D) transition metal dichalcogenides (TMDCs) such as tungsten diselenide (WSe₂) have spead many interesting physical properties, which may become ideal candidates to develop new generation electronic and optoelectronic devices. In order to reveal essential features of 2D TMDCs, it is necessary to fabricate high-quality devices with reliable electrical contact. We systematically analyze the effect of graphene and metal contacts on performance of multi-layered WSe₂ field effect transistors (FETs). The temperature-dependent transport characteristics of both devices are tested. Only graphene-contacted WSe₂ FETs are observed with the metal-insulator transition phenomenon which mainly attributes to the ultra-clean contact interface and lowered contact barrier. Further characterization on contact barrier demonstrates that graphene contact enables lower contact barrier with WSe₂ than metal contact, since the Fermi level of graphene can be modulated by the gate bias to match the Fermi level of the channel material. We also analyze the carrier mobility of both devices under different temperatures, revealing that graphene contact can reduce the charge scattering of the device caused by ionized impurities and phonon vibrations in low and room temperature regions, respectively. This work is expected to provide reference for fabricating 2D material devices with decent performances.