Determination of Base Spreading Resistance and Junction Temperature of Uniform-base Junction Transistors†

The propagation of waves in incompressible beam-plasma systems is investigated on the basis of linear fluid equations. The pressure is assumed scalar and the incompressibility condition is chosen to illustrate a class of non-barotropic plasmas. The dispersion law For these linear waves is derived, and is generally discussed. The case of oblique propagation differs appreciably from results obtained for barotropic plasmas, mainly because compressional longitudinal waves are absent. Alfvén. waves in beam-plasma systems are then denned as low-frequency waves, with wave and drift frequencies small compared to gyrofrequencies. The Alfvén approximation of the dispersion law shows that the wave frequency at fixed wave-number is lower than if no streaming were applied.     

基于FPGA和ISA总线的图像数据采集系统

为便于进行图像处理课题的研究，我们用FPGA和ISA总线开发了基于MOTOROLA公司的SCM20014^[1]的图像数据集卡，其性价比较高，满足一般图像处理研究的要求，本文介绍了该图像采集卡的设计要求和实现方法，文中所涉及的内容具有一般性和典型性。     

纳米材料与微电极生物传感器

主要阐述了利用微电子机械加工技术制作一种新型的微电极集成生物传感器 ,并利用电化学方法在微电极表面固定超微粒的纳米材料 ,检验纳米材料对生物传感器稳定性、灵敏度、响应时间等影响。这种具有纳米尺度效应的生物传感器将在生物医学领域有着广阔的应用前景。     

在MATLAB环境中调用DLL对硬件资源访问的方法

MATLAB是一款高性能的科学与工程计算软件,具有强大的数值计算和分析能力,但其对硬件的访问能力较弱。在MATLAB环境中实现对硬件资源的直接访问可以极大的方便对数据的处理及算法的验证,基于这种目的提出一种扩展MATLAB访问硬件的方法,通过MATLAB外部函数接口调用第三方器件商提供的动态链接库导出函数,在MATLAB平台下实现对一般硬件的访问,并具体介绍了该方法在气压高度计原型系统设计中的应用。该方法简化了MATLAB与硬件的数据交互,对于原型系统设计和算法的验证提供了一种有效的手段。     

谈喷印机喷印工艺与油墨性能的关系

喷印机的喷印过程中,喷印质量直接受油墨性能和喷印工艺参数的影响。本文从喷印机的实用性出发,主要分析探讨了在保证喷印质量的情况下喷印工艺参数的设定与油墨性能的相互关系,并对喷印工艺参数的设定和油墨的使用提出了一些量化指标,为使用者在选择油墨及对油墨性能进行调整和改善提供一定的参考依据,对喷印机的实际应用也有着一定的指导意义。     

Blind Equalization Using Coordinate Mapping for 4-PAM and 16-QAM Signals

It is well known that the famous Constant modulus algorithm （CMA） presents a large steady-state Mean square error （MSE） for nonconstant modulus sig- nals. In this paper a coordinate mapping approach for a 4-PAM nonconstant modulus signal is described which can change the signal to an Offset QPSK （OQPSK） constant modulus signal. And a new algorithm based on this ap- proach is proposed which is also suitable for a 16-QAM signal. For the 4-PAM and 16-QAM nonconstant modulus signals the proposed algorithm can achieve a zero steady- state MSE in a noiseless environment but CMA cannot, Theoretical analysis and simulations results demonstrate the high performance of the proposed algorithm.     

CMOS四路可加权高频模拟开关的设计和研究

介绍了一种可对高频信号进行取样、加权、控制、叠加的模拟信号处理开关集成电路,通过两个高宽长比的高跨导NM O S晶体管可实现权值的粗调和微调。该电路采用标准0.6μm CM O S工艺制造。测试结果表明:该电路的工作频段为50~250 MH z时,导通时最小插入损耗约为-5.0~-10.5 dB,关断时隔离度可达-40.5~-23.4 dB左右;其连续可调的加权动态范围最大值为21.3 dB。     

基于OFDM的UWB系统研究

UWB无线通信是未来最富有竞争力的无线通信技术之一。介绍了一种基于正交频分复用的超宽带(OFDM-UWB)系统的结构,详细分析了电路的主要构成:模数转换器、低噪声放大器、脉冲发生以及他们和系统功耗的联系;介绍了OFDM-UWB信号的处理过程,并探究了消除接收到的UWB信号中窄带干扰(NBI)信号的方法,该方法有效地提高了OFDM-UWB系统的抗干扰性。     

FDD-LTE下行速率感知分析及优化机制

FDD-LTE作为全球主流的第四代通信标准,可以满足用户高数据业务需求。但在现实中,影响速率的问题仍然存在,主要体现在速率波动大和偏低两种。对影响下行速率的因素进行分析,提出定位影响下行速率问题的步骤和优化方法,进而提升用户的速率感知。     

Effect of Cultural Conditions and Media on the Antimicrobial Activity of Streptococcus Thermophilus

When Streptococcus thermophilus was grown in basal medium with or without fermentable carbohydrate (lactose, glucose or sucrose at 2% level), antimicrobial activity was detected only in the cell-free medium and cells were free of any antimicrobial activity. Peanut milk, soymilk and basal medium with a fermentable sugar supported the production of antimicrobial compound(s) by S. thermophilus. Milk-based medium did not appear to be a necessity for such activity. When tested independently, the optimum temperature for maximum production of antimocrobial activity by S. thermophilus in whole milk was 50°C while the optimum time of incubation was 48 hr. An initial pH of 6.0 resulted in maximum antimicrobial activity in basal medium with 2% lactose.