单相电压源变换器减少开关次数调制算法的研究

作为基本的电力电子变换器,单相全桥结构两电平电压源变换器包括单相电压源逆变器、单相并网逆变器、单相电压源整流器和单相有源电力滤波器,具有广泛的应用场合。鉴于单相电压源变换器具有多解性,可以寻找一种减少开关次数的调制算法,以便降低开关损耗。本文根据三相电压源全桥结构两电平电压源变换器的最小开关次数调制算法,设计了一种适合单相全桥结构两电平电压源变换器的最少开关次数的调制算法,在理论分析的基础上,采用MATLAB/SIMULINK进行了仿真验证。     

OTN技术发展与组网应用

从分析OTN的发展驱动力入手,介绍了OTN的技术与标准化进展,讨论了OTN组网的基本要求、应用模式和发展趋势。     

深亚微米nMOSFET器件的总剂量电离辐射效应

选取了采用0.25μm工艺的两组器件进行研究.通过对这两种器件关态泄漏电流、跨导和栅电流等电学参数进行分析,得出当器件发展到深亚微米阶段时,影响其辐射效应的主要原因是场氧化层中的陷阱电荷.并对相关机理进行了分析和仿真验证.     

EC9706细胞经不同剂量X射线辐照后的拉曼光谱

为了研究不同剂量X射线对食管癌(EC9706)细胞的辐射损伤,经不同剂量X射线照射后继续培养24 h,利用拉曼光谱分析其内部蛋白质、核酸、脂类等构象和含量变化.实验结果表明,各剂量组拉曼光谱的峰强和频移与空白对照组之间存在较大的差异.对照组光谱中某些谱带在个别剂量组消失,如蛋白质主链中C-N振动1114 cm-1谱带在各剂量组中消失,脱氧核糖Dr振动谱带895 cm-1仅存在于8Gy组,937 cm-1谱带仅存在于12Gy组,膜脂中膜结合β-胡萝卜素的C=C振动谱带1523 cm-1仅存在于6Gy组.这些特征谱带在不同剂量组光谱中的变化,为进一步研究X射线辐照EC9706细胞的最佳剂量提供了一定参考.     

A lightweight authentication scheme based on self‐updating strategy for space information network

The security of space information network (SIN) is getting more and more important now. Because of the special features of SIN (e.g., the dynamic and unstable topology, the highly exposed links, the restricted computation power, the flexible networking methods, and so on), the security protocol for SIN should have a balance between security properties and computation/storage overhead. Although a lot of security protocols have been proposed recently, few can provide overall attacks resistance power with low computation and storage cost. To solve this problem, in this paper we propose a lightweight authentication scheme for space information network. It is mainly based on the self‐updating strategy for user's temporary identity. The scheme consists of two phases, namely, the registration phase and the authentication phase. All the computing operations involved are just hash function (h), the bit‐wise exclusive‐or operation (⊕), and the string concatenation operation (||), which are of low computation cost. The security properties discussion and the attacks–resistance power analysis show that the proposed authentication scheme can defend against various typical attacks, especially denial of service attacks. It is sufficiently secure with the lowest computation and storage costs. Furthermore, the formal security proof in SVO logic also demonstrates that the scheme can satisfy the security goals very well. Copyright © 2016 John Wiley & Sons, Ltd.     

Cr2+:ZnSe的激光输出和调谐性能

Cr2 :ZnSe具有很宽的吸收带和发射带,是中红外波段优秀的可调谐激光材料.从吸收光谱、发射光谱以及角度调谐输出对Cr2 :ZnSe晶体的激光输出性能进行了研究.采用真空高温扩散法制备Cr2 :ZnSe晶体,获得了高浓度的Cr2 离子掺杂的厚1.7 mm,直径10 mm的薄片ZnSe晶体.使用中心波长2.05 μm,最大输出功率8 W的Tm离子掺杂的光纤激光器抽运,使用平凹腔结构搭建谐振腔,获得了最大平均功率1.034 W,中心波长2.367 μm,线宽10 nm的连续激光输出.利用角度调谐的方法,对Cr:ZnSe晶体的调谐性能进行了研究,在100 nm范围内获得了调谐输出.     

悬停直升机检测问题研究

主要研究悬停直升机目标的检测问题。首先描述直升机旋翼的理想后向散射模型,分析了直升机理想旋翼回波时域上的调制特点和频域上的分布特征。并据此讨论了检测中需要考虑的问题的问题和要求。最后,提出了一种以小波变换为工具进行信号处理、利用直升机目标旋翼的回波闪烁幅度的数目进行检测的新方法,计算机仿真验证此方法是有效的。     

Unexpected Sole Enol‐Form Emission of 2‐(2′‐Hydroxyphenyl)oxazoles for Highly Efficient Deep‐Blue‐Emitting Organic Electroluminescent Devices

Considerable efforts have been devoted to the development of highly efficient blue light‐emitting materials. However, deep‐blue fluorescence materials that can satisfy the Commission Internationale de l'Eclairage (CIE) coordinates of (0.14, 0.08) of the National Television System Committee (NTSC) standard blue and, moreover, possess a high external quantum efficiency (EQE) over 5%, remain scarce. Here, the unusual luminescence properties of triphenylamine‐bearing 2‐(2′‐hydroxyphenyl)oxazoles ( 3a–3c ) and their applications in organic light‐emitting diodes (OLEDs) are reported as highly efficient deep‐blue emitters. The 3a ‐based device exhibits a high spectral stability and an excellent color purity with a narrow full‐width at half‐maximum of 53 nm and the CIE coordinates of (0.15, 0.08), which is very close to the NTSC standard blue. The exciton utilization of the device closes to 100%, exceeding the theoretical limit of 25% in conventional fluorescent OLEDs. Experimental data and theoretical calculations demonstrate that 3a possesses a highly hybridized local and charge‐transfer excited state character. In OLEDs, 3a exhibits a maximum luminance of 9054 cd m^?2 and an EQE up to 7.1%, which is the first example of highly efficient blue OLEDs based on the sole enol‐form emission of 2‐(2′‐hydroxyphenyl)azoles.     

一种用于MEMS电容式加速度计的116dB动态范围CMOS读出电路

A high stability in-circuit reprogrammable technique control system for a capacitive MEMS accelerometer is presented. Modulation and demodulation are used to separate the signal from the low frequency noise. A low-noise low-offset charge integrator is employed in this circuit to implement a capacitance-to-voltage converter and minimize the noise and offset. The application-specific integrated circuit （ASIC） is fabricated in a 0.5 /μm one-ploy three-metal CMOS process. The measured results of the proposed circuit show that the noise floor of the ASIC is -116 dBV, the sensitivity of the accelerometer is 66 mV/g with a nonlinearity of 0.5%. The chip occupies 3.5×2.5 mm2 and the current is 3.5 mA.     

Optical properties in 1D photonic crystal structure using Si/C60 multilayers

The feasibility of using Si/C60 mulfilayer films as one-dimensional(1D)photonie band gap crystals was investigated by theoretical calculations using a transfer matrix method(TMM).The response has been studied both within and out of the periodic plane of Si/C60 multilayers.It is found that Si/C60 multilayer films show incomplete photonic band gap(PBG)behavior in the visible frequency range.The fabricated Si/C60 multilayers with two pairs of 70 am C60 and 30 nm Si layers exhibit a PBG at central wavelength of about 600 nm.and the highest reflectivity call reach 99%.As a consequence,this photonic crystal may be important for fabricating a photonic crystal with an incomplete band gap in the visible frequency range.