Analytical solution for electromagnetic scattering from a sphere of uniaxial left-handed material

INTRODUCTION The concept of left-handed materials (LHM for short, also called negative index materials) was in- troduced by Veselago (1968). An LHM has both negative permittivity and negative permeability, which makes the wave vector, the electric-field vector, and the magnetic-field vector in the LHM obey the left-hand rule. Experimental verifications for the existence of an LHM were made and its use as a perfect lens was suggested (Pendry, 2000; Shelby et al., 2001a; 2001b; Smith …     

Blackboard与网络教学资源库系统整合研究

首先分别介绍了Blackboard平台和网络教学资源库的体系结构及功能。其次针对两个系统的使用现状及存在问题,提出系统整合的思路。以资源共享为原则,采用宏观微观相结合的整合模式,开发逻辑数据库,对两个系统的功能和数据进行整合,为用户提供统一的登录平台,并增添个性化资源定制、个性化资源查询及综合查询等新功能,从而达到两个系统互补优劣,提高使用效率,更好地为网络教学服务的目的。     

磁荷与磁介质球系统磁标势研究

尝试用数学模型去解决磁介质与磁荷系统的磁化、磁性质等问题，并用统一的、严谨的理论框架去解决静磁场问题。通过建立磁荷与磁介质球系统磁标势的数学模型，从理论上构建磁荷与磁介质球系统的一般框架，利用该模型可以引导分析均匀磁场中磁介质球的磁标势，磁屏蔽以及均匀磁化铁球等问题。借此还可以进一步分析磁荷与磁介质系统的磁性质、磁场、磁力等问题。解决了磁荷、磁矩与磁介质系统磁场及磁力计算方法等问题，为进一步研究磁单极与磁场、磁介质之间的性质和关系奠定理论基础。     

溴化锂吸收式制冷机组的特点及应用分析

通过工程中对溴化锂吸收式制冷机组的实际应用分析,总结了溴化锂吸收式制冷机组的特点,对今后实际工程中选用溴化锂机组具有参考作用.     

Investigation of the dynamic characteristics of a dual rotor system and its start-up simulation based on finite element method

Recently, the finite element method (FEM) has been commonly applied in the engineering analysis of rotor dynamics. Gyroscopic moments, rotary inertia, transverse shear deformation and gravity can be included in computational models of rotor-bearing systems. In this paper, a finite element model and its solution method are presented for the calculation of the dynamics of dual rotor systems. A typical structure with two rotor shafts is discussed and the procedure for obtaining the coupling motion equations of the subsystems is illustrated. A computer program is developed to solve critical speeds and to simulate the transient motion. The influence of gyroscopic moments on co-rotation and counter-rotation is analyzed, and the effect of the speed ratio on critical speed is studied. The dynamic characteristics under different conditions of increasing speed during start-up are demonstrated by comparison with transient nodal displacements. The presented model provides a complete foundation for further investigation of the dynamics of dual rotor systems.     

城市高架路-匝道-地面交通的交互作用及交通流特性研究

Therapiddevelopmentoftheautomobileindustry andtherelativelagoftheroadconstructionhavecon stitutedaprominentcontradictionallovertheworld, particularly,inmostoflargecities.Tocopewithit, elevatedroadshavebeenbuiltinmanycitiesbothat homeandabroad.However,tra…     

创建有特色的“三位一体”高职技能教学模式

教育方针是国家教育工作的根本指导思想,也是指导教育教学改革的行动指南。重庆教育学院旅游系借重庆直辖的契机,努力践行教育方针,不断改革创新,抓住“两个结合”,在岗位技能课程教学中,将高职教学要求、岗位实际需求、国家职业标准三者相衔结,形成“三位一体”的教学模式的教改实践与探索,以期揭示符合市场要求具有高职特色的高职技能教学模式。     

Parallel programming characteristics of a DSP-based parallel system

INTRODUCTION DSP-based parallel system is a kind of high- performance parallel computer which uses parallel accelerating boards based on SHARC DSP chip (Kuo and Gan, 2005) as plug-in boards and inserts them into the military reinforcing computer, military fault-tolerant computer, even the personal computer. The parallel accelerating board based on SHARC DSP is a high-performance parallel processing board-level product developed by the Wuhan Digital Engineering Institute and is su…     

An energy harvester combining a piezoelectric cantilever and a single degree of freedom elastic system

This paper presents a type of vibration energy harvester combining a piezoelectric cantilever and a single degree of freedom (SDOF) elastic system. The main function of the additional SDOF elastic system is to magnify vibration displacement of the piezoelectric cantilever to improve the power output. A mathematical model of the energy harvester is developed based on Hamilton??s principle and Rayleigh-Ritz method. Furthermore, the effects of the structural parameters of the SDOF elastic system on the electromechanical outputs of the energy harvester are analyzed numerically. The accuracy of the output performance in the numerical solution is identified from the finite element method (FEM). A good agreement is found between the numerical results and FEM results. The results show that the power output can be increased and the frequency bandwidth can be improved when the SDOF elastic system has a larger lumped mass and a smaller damping ratio. The numerical results also indicate that a matching load resistance under the short circuit resonance condition can obtain a higher current output, and so is more suitable for application to the piezoelectric energy harvester.     

基于单片机的温度测量系统的研制

作综合应用传感器、信号拾取、模数转换、数字滤波、测量数字显示、汉字滚动菜单显示、串行通讯等技术，采用模块化设计，研制出一种基于单片机的温度测量系统，它可以应用于不同测控系统的制冷空调专业实验室的温度测控显示。     

Void Formation and Growth for a Class of Compressible Hyper-Elastic Sphere

In this paper, the strain energy function proposed by Shang and Cheng was generalized by introducing a nonlinear term. Void formation and growth in the interior of a sphere composed of compressible hyper-elastic material, subjected to a prescribed uniform displacement, was examined. A parametric cavitated bifurcation solution for the radial deformed function was obtained. Stability of the solution of the cavitated bifurcation equation was discussed. With the appearance of a cavity, an interesting feature of the radial deformation near the deformed cavity wall is the transition from extension to compression.     

Becoming a teacher of primary science: integrating theory and practice

This paper reports a study of how a group of six students learnt to teach primary science as they went through a 4-year teacher education degree. The study shows that from early in the course students had a clear view of how they wanted to teach science and had a range of concerns about their teaching. Their views gradually became refined and actionable in the classroom as they went through the course. A variety of data types was used to interpret their learning. A significant number of their decisions were not recorded in their written work so were only available in discussion or action. All students were able to deal with the complexity of their classrooms in their oral discussions, but fewer could do this in writing. The students drew on a range of programme material to support their decisions, and these are used to show the interaction between their work in school and in college.     

Development of instructional design strategies for integrating an online support system for creative problem solving into a University course

Asia Pacific Education Review - This study examined three cases in which an online support system was utilized to enhance creative problem solving (CPS) in a higher education setting. This study...     

Quantitative influence of HCI characteristics in a blended learning system

Of late blended learning is a popular choice of training in India. To assess the effectiveness of Human Compute Interaction (HCI) in blended mode, evaluation by trainee group was undertaken. The trainees with a background in commerce evaluated the blended learning system using a Likert type evaluation form. Due to the non-parametrical nature of data, we adopt RIDIT method to analyze data. The novel approach in this paper is the use of RIDIT method to analyze qualitative HCI features quantitatively. The trainee feedback has provided an understanding of the extent to which blended learning is acceptable. The evaluation provides insight into level of preference given among human-human, human-computer and technology aspect by trainees. This evaluation looks promising and provides opportunity for further developments in blending HCI features into blended learning environment to provide worthwhile and relevant learning opportunities.     

太阳能-地源热泵系统的交替运行特性

为了探讨太阳能-地源热泵系统的交替运行特性,提出并定义了各交替运行模式,建立了交替运行时考虑冻融相变的U形埋管周围土壤传热模型.基于对该模型的数值求解,探讨了各交替运行模式下地下埋管周围土壤温度的变化趋势.结果表明：各交替运行模式均可有效改善埋管周围土壤温度的恢复效果,对于无太阳能补热的昼夜交替与短时间间隔交替运行模式,在以24h为交替运行周期时,其太阳能热源承担的时间比例可控制在50%～58%;同时,利用日间太阳能补热来强制土壤温度的恢复,可有效克服土壤温度的自然恢复缺陷,与其他交替模式综合使用可达最佳运行效果.此外,利用钻孔壁实测数据对所建模型的预测精度进行了验证.研究结论可为太阳能-地源热泵系统的优化运行提供参考.     

建设有中国特色的人文教育新体系

人文教育是全民的教育,不是精英教育。人文求善,科学求真,社会的进步需要科学,科学的发展又受人文的影响。建立有中国特色的人文教育新体系,首先必须走全民教育之路;其次科技、人文并重;再次健全和完善保障机制。它是一项重大、艰巨而长期的工程,必须经历几代人的努力。     

激光步镜显示系统的设计与实现

介绍了步镜法激光图形显示系统,设计了应用计算机控制步镜来显示光栅图形的工作平台,分析了输出图形的软硬件工作原理,并推导了显示图形的数学公式.最后展现了现场控制和输出的结果图,取得了较满意的效果.     

AT89C2051单片机在温度测试系统中的应用

给出了由AT89C2051单片机控制的智能热电偶温度测试系统,叙述了该系统的温度测试电路、模数转换电路以及温度显示的软硬件实现方法。论述了模拟信号的采集、转换、处理和显示技术。     

振动温度在线监测系统研制

采用ＲＳ－４８５计算机网络、集成一体化传感器和ＡＤＡＭ－４０００系列模块,实现炉顶风机的状态监测。简化检测系统的结构,提高系统可靠性。     

差动变压式传感器位移测量系统设计

围绕测控专业本科生的综合设计型实验,介绍了差动变压式传感器位移测量的原理、各部分电路的基本组成、电路设计与参数选择、电路的调试方法以及应注意的问题.本测量系统是一个开环系统,结构简单、响应速度快,但精度还有待进一步提高.