快速轴流CO_2激光器

本文报道我们设计的快速轴流ＣＯ_２激光器和实验结果,激光器的光学谐振腔为三折Ｚ形折叠半共焦腔,输出耦合镜为ＧａＡｓ材料,透过率为７２％的,得到最大输出功率２５３０Ｗ,电光转换效率最高达到２４％。     

TD-CDM-OFDM: Evolution of TD-SCDMA toward 4G

TD-SCDMA, which is the "homemade" 3G standard in China, has received considerable attention and is believed to play a critical role in the development of China's mobile communication. Meanwhile, advanced MIMO and OFDM techniques shed light on the feasibility of high-performance 4G broadband systems. We discuss an evolutionary path of TD-SCDMA toward 4G systems in this article, which combines the existing advanced traits in TD-SCDMA with new features for broadband wireless communication systems.     

Ionic liquids in perovskite solar cells

Metal halide perovskites have gained a lot of attention par-ticularly in recent years due to their excellent optoelectronic properties and simple scalable processability[1-3].One major application of halide perovskites is solar cells,however,des-pite the power conversion efficiencies(PCEs)have already reached around 25％[4,5],the long-term stability issue of such devices still impedes their commercialization.Ionic liquids,which contain a large asymmetric organic cation and an organ-ic or inorganic anion,have recently been applied to per-ovskite solar cells(PSCs),not only increasing the efficiency but also remarkably improving the long-term stability[6,7].     

基于多平台实现的UCAV攻击编队自主协作系统设计

为了实现无人战斗机的编队攻击,在深入分析编队协作复杂性的基础上,采用模块化设计,根据高可靠性原则,在V isual C++6.0环境中,提出了一种可以在不同平台中实现功能的UCAV攻击编队自主协作系统的设计方法,并对各个子系统的组成和功能进行了探讨,给出了该系统在整个作战过程中的工作流程,最后对正常攻击、单个任务失败、基于不同平台的系统实现3种情况进行了仿真分析。结果表明,该系统能够在不同的平台中可靠地实现UCAV编队自主协作攻击过程。     

Boron-doped silicon film as a recombination layer in the tunnel junction of a tandem solar cell

Boron-doped hydrogenated silicon films with different gaseous doping ratios (B2H6/SiH4) were deposited in a plasma-enhanced chemical vapor deposition (PECVD) system. The microstructure of the films was investigated by atomic force microscopy (AFM) and Raman scattering spectroscopy. The electrical properties of the films were characterized by their room temperature electrical conductivity (σ) and the activation energy (Ea). The results show that with an increasing gaseous doping ratio, the silicon films transfer from a microcrystalline to an amorphous phase, and corresponding changes in the electrical properties were observed. The thin boron-doped silicon layers were fabricated as recombination layers in tunnel junctions. The measurements of the Ⅰ-Ⅴ characteristics and the transparency spectra of the junctions indicate that the best gaseous doping ratio of the recombination layer is 0.04, and the film deposited under that condition is amorphous silicon with a small amount of crystallites embedded in it. The junction with such a recombination layer has a small resistance, a nearly ohmic contact, and a negligible optical absorption.     

基于IaaS云计算平台的弹性计费模型

文章认为计费系统是云计算平台不可缺少的重要组成部分。在分析中国外著名企业的云计费模式的基础上,文章针对基础设施即服务(IaaS)云计算平台,提出了一种基于租赁实体的计费模型与基于事件触发机制的计费模型相结合的计费模型,利用租赁实体的计费模型对空闲的主机进行调度,通过事件触发机制对计费信息进行统计。该计费模型使云计费方式更加灵活。     

Design and Performance of Space–Time Precoder With Hybrid ARQ Transmission

Multiple-input-multiple-output (MIMO) technology can efficiently increase the system capacity in rich scattering environments without increasing the bandwidth or transmission power. The precoder for MIMO transmission is a processing technique that exploits the channel state information (CSI) by operating on the signal before transmission to effectively improve link performance. A hybrid automatic repeat request (HARQ) scheme can be incorporated with the linear precoder to ensure highly reliable communication. To fully utilize the type-I HARQ diversity gain, particularly in slow-fading channels, we propose the optimal design principle of linear precoders whose column vectors are correspondingly orthogonal to each other. In addition, the practical solution based on codebook is given in this paper. Finally, simulation results demonstrate the effectiveness of the proposed precoders in reducing the detection of bit error rate (BER) and in improving normalized throughput.     

TD-SCDMA演进与多载波技术

为了提高TD-SCDMA系统的传输速率和系统容量,更好地支持高速数据业务及大规模组网能力, TD-SCDMA开始向多载波方向进行增强和演进。本文首先介绍了TD-SCDMA未来演进和发展趋势,提出了TD-SCDMA演进的四阶段;然后重点讨论了多载波TD-SCDMA技术特征,分别对不引入HSDPA的多载波TD-SCDMA和引入HSDPA的多载波TD-SCDMA进行了介绍,并对多载波TD-SCDMA系统的容量和性能进行了评估;最后总结了多载波TD-SCDMA技术的未来挑战。     

Macro-Sized All-Graphene 3D Structures via Layer-by-Layer Covalent Growth for Micro-to-Macro Inheritable Electrical Performances

Creating 3D-engineered macroscopic architectures while inheriting the superior properties of individual building blocks remains one of the fundamental challenges in nanotechnology. Stable covalent interconnection between micro/nanoblocks is a desired but underexplored strategy to meet the challenges, rather than current dependently-used weak physical forces or organic cross-linking, which disrupts the continuity of chemical composition and electrical properties. Herein, a novel layer-by-layer covalent growth protocol is developed to construct all-graphene macrostructures (AGM) with micro-to-macro inheritable electrical properties by laser-assisted covalent linkage of polyethersulfone-derived 3D porous graphene microblocks without introducing any catalysts, templates, and additives. Creatively, along with graphene generation and inter-layer bonding, a quality optimization process is integrated into one-step laser irradiation, which is unique and efficient for synthesizing high-crystalline graphene. With the covalently nondestructive bridge and free of non-graphene foreign phase impurities, AGM shows unprecedented electrical conductivity, especially a more than 100-fold improvement in cross-layer conductivity compared with non-covalent assembly. Furthermore, the covalent growth mechanism of AGM is clarified by molecular dynamics simulations. Finally, the application efficacy of AGM with enhanced isotropic conductivity is verified by using it as a supercapacitor electrode. This methodology enables the as-obtained AGM to possess the potential for high-performance-pursuing, multi-disciplinary, or large-scale applications.     

基于故障树的接口模块Flash测试方法改进研究

故障树分析法是一种系统、可靠、逻辑性强的分析方法。分析接口模块硬件结构,建立UserFlash测试故障树模型、对故障分支进行分析,查明测试报故的原因,通过机理分析,改进Flash测试方法并进行验证。结果表明,改进后的测试方法能有效提高测试通过率和延长芯片使用寿命,具有很强的工程应用价值。