生物洁净室的污染控制

生物洁净室的目的是控制细菌污染。通过对细菌特性、来源及污染途径的分析,确定了全方位、全过程控制的基本思想,即污染源控制,污染传播过程控制和交叉污染控制,通过分析微粒的运动特性,提出了空气途径污染的主要手段是气流流动控制和表面污染控制,最后分析了交叉污染的形成原因及其防治措施。     

半导体激光器辐照损伤效应实验研究进展

半导体激光器(LD)工作在空间辐射或核辐射环境中时,会受到辐照损伤的影响而导致器件性能退化。文章回顾了不同时期研制的LD(从早期的GaAs LD到量子阱LD和量子点LD)在辐照效应实验方面的研究进展,梳理了国际上开展不同辐射粒子或射线(质子、中子、电子、伽马射线)诱发LD辐射敏感参数退化的实验规律,分析总结了当前LD辐照效应实验方法研究中亟待解决的关键技术问题,为今后深入开展LD的辐照效应实验方法、退化规律、损伤机理及抗辐射加固技术研究提供理论指导和实验技术支持。     

Electrical performance study of 25 nm Ω-FinFET under the influence of gamma radiation: A 3D simulation

In this research paper, a 3D process simulation of 25 nm n-channel Ω-FinFET and the effect of Gamma radiation on device characteristics have been studied. Device simulations are carried out under the influence of Gamma radiation under varying does conditions from 100 Krad (SiO₂) to 10 Mrad (SiO₂). Effects of Gamma radiation on the threshold voltage, transfer characteristics, drive current, off-state leakage current and subthreshold characteristics have been studied. Extracted parameters for virgin and irradiated devices have been compared in order to understand the degradation in the electrical characteristics of the Ω-FinFET under study. Simulation results under the low drain and high drain bias has been reported and discussed. It is found that Ω-FinFET delivers better performance under irradiation as compared with conventional single gate MOS structures. Ω-FinFET is shown to be significantly tolerant to gamma radiation upto dose of 5 Mrad (SiO₂). In addition, the influence of quantum effects on this nanoscale device is investigated in detail. Sentaurus simulation results obtained has been compared with the reported experimental data.     

等效集中参数模型在空载长线路教学中的应用

在＂电气工程基础＂课程的过电压教学过程中,空载架空线路的长线电容效应是一个十分重要的概念。本文从均匀架空长线的分布参数等效模型及其端点的等效集中参数模型出发,对电容效应不同的补偿方式进行等效参数分析和讨论,同时对复杂的补偿方法进行了等效分析.本文的讨论对电气工程课程的教学和工程实践具有一定的参考价值。     

3-D electrothermal simulation of active cycling on smart power MOSFETs during short-circuit and UIS conditions

Active cycling of power devices operated in harsh conditions causes high power dissipation, resulting in critical electrothermal and thermo-mechanical effects that may lead to catastrophic failures. This paper analyzes the ageing-induced degradation of the chip metallization of a power MOSFET and its impact on the device robustness during short-circuit and unclamped inductive switching tests. A 3-D electrothermal simulator relying on a full circuit representation of the whole device is used to predict the influence of various ageing levels. It is found that ageing can jeopardize the robustness of the transistor when subject to short-circuit conditions due to the exacerbated de-biasing effect on the gate-source voltage distribution; conversely, this mechanism does not arise under unclamped inductive switching conditions. This allows explaining the difference in time-to-failure experimentally observed for the transistors subject to these tests and dissipating the same energy.     

Structural tuning of wide‐gap chalcopyrite CuGaSe2 thin films and highly efficient solar cells: differences from narrow‐gap Cu(In,Ga)Se2

Simultaneous realization of high values of open circuit voltage (V_oc), fill factor (FF), and energy conversion efficiency (η) in wide‐gap CuGaSe₂ (CGS) solar cells has long been one of the most challenging issues in the realm of chalcopyrite photovoltaics. In this communication, structural tuning of CGS thin films by means of controlling the amount of Se flux used during CGS film growth and improvements in solar cell performance (V_oc > 0.9 V, FF > 0.7, and η > 10%) are demonstrated. Systematic variations in CGS film properties with the Se flux and correlation with device properties are shown. The unique CGS thin‐film growth kinetics, which are different from narrow‐gap Cu(In,Ga)Se₂, are also presented and discussed. This development of double digit efficiency for CGS solar cells opens a new frontier for the broad application of a new class of chalcopyrite‐based devices. Copyright © 2014 John Wiley & Sons, Ltd.     

Social media and political partisanship – A subaltern public sphere’s role in democracy

Social media, as a subaltern public sphere (Fraser, 1990), have a democratic function in providing an alternative platform for minorities and marginalized to defy mainstream discourses in the public sphere. However, social media have been found to have an echo chamber effect, which may be detrimental to democracy. They may help to accelerate the ascendancy of a “post-truth” era in which objective facts are less influential in shaping public opinion than appeals to emotion and personal belief. A study on political polarization, however, showed that selective exposure and avoidance in social media are weak indicators of polarization (Johnson et al., 2017). This study examines the role of social media in democracy and partisan politics. The authors considered that despite the echo chamber effect, social media have a limited part to play in the formation of polarized stances compared with other factors, such as demographics, political orientation, and mass media use. The study tested two main hypotheses: H1: Social media use is associated with political stance that is marginalized in the mainstream media; H2: Political orientation has a stronger relationship than social media use with the stance toward political values and social issues.The results supported both hypotheses. Social media are associated with political stance that is marginalized in the mainstream media. However, when compared with other factors, the relationship between social media and stance becomes less obvious. Although the echo chamber effect may reinforce the original stance, social media do not exhibit a strong relationship with the stance toward political values and social issues. Partisan orientation and use of partisan mass media are found to have stronger links with variations in stance. Social media, however, provide a subaltern public sphere for those excluded from the dominant public sphere, thus extending the public sphere to accommodate multiple opinions and perspectives.     

光折变Bi12TiO20晶体中的波耦合性质

研究了光折变Bi12TiO20(TBO)晶体中的二波耦合矢量特性.对扩散记录全息求得信号光能量增益和偏振态改变的分析解,研究它们在3种制备可得的晶体切割面上随入射抽运光和信号光(不同)偏振方向、光栅取向以及晶体厚度的变化关系,并给出在任意光栅取向的取值范围.分析了信号光能量增益和偏振态改变量分别达到最大值时各向同性和各向异性耦合的作用,并研究旋光、压电及弹光效应在3种晶体切割面上对矢量波耦合的影响.     

铬鞣粉剂中添加剂对其铬含量和碱度的影响

本文研究了铬鞣粉剂中添加剂ＤＰＳ、石粉以及无水硫酸钠对铬鞣粉剂中Ｃｒ２Ｏ３含量和碱度的影响，从而为皮化厂的铬鞣粉剂的质量控制提供了理论基础。     

Fast complex memory polynomial-based adaptive digital predistorter

Today's 3G wireless systems require both high linearity and high power amplifier (PA) efficiency. The high peak-to-average ratios of the digital modulation schemes used in 3G wireless systems require that the RF PA maintain high linearity over a large range while maintaining this high efficiency; these two requirements are often at odds with each other with many of the traditional amplifier architectures. In this article, a fast and easy-to-implement adaptive digital predistorter has been presented for Wideband Code Division Multiplexed signals using complex memory polynomial work function. The proposed algorithm has been implemented to test a Motorola LDMOSFET PA. The proposed technique also takes care of the memory effects of the PA, which have been ignored in many proposed techniques in the literature. The results show that the new complex memory polynomial-based adaptive digital predistorter has better linearisation performance than conventional predistortion techniques.