PARASITIC TOLERANT DIFFERENTIAL SC TRANSCONDUCTANCE USING UNITY GAIN BUFFERS

The unity gain buffer will be good to design high frequency SCF if its resistiveeffects can be eliminated,and therefore the whole parasitic sensitivities will greatly be reduced.On the basis of this concept,a novel parasitic tolerant SC DTE(differential transconductanceelement)is proposed.SC floating inductor and integrator fit for high frequency applications areformed by the DTE.The computer simulation and experiment on a third order elliptic LP filterverify its validity.     

Unity direct chain with feedback series impedance based innovative negative group delay circuit

An innovative negative group delay (NGD) circuit theory on unity direct chain (UDC) topology is developed in this paper. The NGD UDC cells are based on the operational amplifier adder with feedback series impedance. Innovative topologies of high-pass NGD UDC cell composed of RL-series network, all-pass RC-parallel network and low-pass RC-series network are identified. It is a first time that all-pass NGD original topologies are defined. NGD analyses and synthesis methods of each NGD UDC cells are provided. The UDC cell based NGD functions are validated with SPICE simulations. The proofs-of-concept (POC) of UDCs behave as all-pass and low-pass NGD functions with group delay equal to −1 ms at very low frequencies. The low-pass NGD cut-off frequency is 424 Hz. The high pass NGD circuit generates −1 µs at the optimal NGD frequency of about 5.15 kHz. Further analysis of the operational amplifier gain and bandwidth effects is performed. The operational amplifier gain affects significantly the NGD level and bandwidth for the all considered UDC cells. Nevertheless, only the RC-parallel feedback based UDC cell is particularly sensitive to the operational bandwidth.     

QUADRATURE METHODS FOR HIGHLY OSCILLATORY SINGULAR INTEGRALS

We address the evaluation of highly oscillatory integrals,with power-law and logarithmic singularities.Such problems arise in numerical methods in engineering.Notably,the evaluation of oscillatory integrals dominates the run-time for wave-enriched boundary integral formulations for wave scattering,and many of these exhibit singularities.We show that the asymptotic behaviour of the integral depends on the integrand and its derivatives at the singular point of the integrand,the stationary points and the endpoints of the integral.A truncated asymptotic expansion achieves an error that decays faster for increasing frequency.Based on the asymptotic analysis,a Filon-type method is constructed to approximate the integral.Unlike an asymptotic expansion,the Filon method achieves high accuracy for both small and large frequency.Complex-valued quadrature involves interpolation at the zeros of polynomials orthogonal to a complex weight function.Numerical results indicate that the complex-valued Gaussian quadrature achieves the highest accuracy when the three methods are compared.However,while it achieves higher accuracy for the same number of function evaluations,it requires signi cant additional cost of computation of orthogonal polynomials and their zeros.     

Unity3d产品虚拟展示技术的研究与应用

本文是在介绍虚拟现实技术的基础上,阐述应用专业引擎Unity3D为工具,实现虚拟产品模型展示的设计流程以及各个环节,最终开发出基于网络的,数据精准．表现力强,交互性强的工业产品虚拟展示应用系统。通过搭建一个跨越时空局限性的交流互动平台,实现企业与消费者之间更加方便快捷的产品信息交流,满足信息化时代人们对高速高效电子商务的需求。     

基于Unity3D的电路原理虚拟实验室设计

电路原理实验是电信类学生大学的第一门专业实验课程,在实验过程中学生第一次使用电子类专业的常用仪器,因此通过开发3D的虚拟实验系统作为辅助教学工具,使学生直观的掌握实验仪器的使用方法,通过有沉浸感的虚拟操作掌握实验方法,取得更好的实践效果,为学生自主实验提供必要条件。     

基于Leap Motion手语语音转换的设计与实现

文章介绍了基于Leap Motion手语语音转换的原理以及在实际中如何实现应用,其能够将手语手势翻译成所需语言,并且以语音的形式传递消息,实现为聋哑人"发声"的目的。Leap Motion手语语音转换的硬件部分采用Leap Motion体感控制器,能够实时采集人手指的坐标、加速度、方向等动态手势的运动信息。软件采用Unity 3D三维引擎,提供了开发手势识别的SDK,并给出了一些基本手的模型,在Unity 3D中完成由手势到文字,再到语音的转换。     

基于国产自主CPU的SEP0611平台中Dalvik虚拟机的移植和优化

Dalvik是Google公司自己设计用于Android平台的Java虚拟机,Andriod系统不支持所有构架的特性使将andriod系统移植到基于国产内核Unity的Soc的SoC SEP0611上有着大量的工作.对Dalvik虚拟机平台相关性和无关性进行分析,使对虚拟机的移植有了基本认识和实现基础,同时介绍了我们自主研发的基于国产自主内核的SoC,将与基于国产内核Unity架构平台相关的JNI(Java Native Interface)机制进行分析,找到了移植的关键环节本地调用桥(Callbridge),同时对Dalvik虚拟机优化的进行了分析与研究,找到了解释器优化的最好途径,即用汇编重写解释器,并初步探讨了JIT( Just In Time)编译器的实现方法.通过实现本地调用桥,实现了Dalvik虚拟机在SEP0611国产自主SoC上的移植.     

沿海高层建筑内覆盖质量的优化方案和案例

高层建筑内手机用户的使用感知质量情况,一直是无线网络优化工作研究的课题。随着城市的建设的快速发展,一些沿海城市海景楼、海景酒店林立而起,沿海高层建筑周边的CDMA质量覆盖技术也形成了新的研究课题。主要介绍几种高层导频污染和弱覆盖问题解决的优化方案和案例,从中提炼CDMA无线优化提供参考经验。     

多重短程有序准化学模型:有序原子对的对立与统一

在准化学模型框架下, 假设有序原子对同时具有可区分与不可区分的双重属性, 首先构造了双重短程有序准化学模型, 然后讨论了该模型所能满足的各类理论极限. 经总结提炼, 提出了有序原子对的对立统一理论. 基于该理论, 进一步将双重短程有序准化学模型做了一般化推广, 开发了多重短程有序准化学模型. 该模型能够有效描述二元熔体中存在多重短程有序构型时的热力学行为. 选取了至少存在两重短程有序构型的Bi-K熔体来检验模型的合理性和可靠性. 结果表明, 除配位数外, 只需4个模型参数就能合理再现该二元熔体所有的热化学数据.     

使用单位增益缓冲器构成的抗寄生SC跨导

用单位增益缓冲器构成的开关电容滤波器(SCF),若能消除寄生电容引起的阻性寄生,则可用于高频设计,总寄生灵敏度会因此大大降低。本文在此基础上提出一种新的抗寄生开关电容(SC)跨导元件电路差分跨导元件,并用它构成了适用于高频的SC浮地电感和积分器。最后用它实现了一个三阶椭圆函数低通滤波器,并经计算机模拟和实验验证,证明了该方案的正确性。