LiNbO3光波导DBR结构透射特性分析

本文采用等效波导光栅Ｆ－ｐ腔方法分析了有耗情况下ＬｉＮｂＯ３光波导ＤＢＲ结构的透射特性，给出了利用这一结构设计电光强度调制器以及电调频分器的方法。     

无线数据通信网发展趋势

无线数据通信具有两大发展趋势，即低速的广域移动数据网及高速的局域无线数据网。本文介绍了其技术特点、应用情况和市场前景，分析了无线数据通信传输技术、网络结构和媒质接入控制等问题。     

无线传感网络中的动态集群密钥管理方案

Wireless sensor networks are open architectures, so any potential threat can easily intercept, wiretap and counterfeit the information. Therefore, the safety of WSN is very important. Since any single key system cannot guarantee the security of the wireless sensor network for communications, this paper introduces a hierarchical key management scheme based on the different abilities of different sensor nodes in the clustered wireless sensor network. In this scheme, the nodes are distributed into several clusters, and a cluster head must be elected for each cluster. Private communication between cluster heads is realized through the encryption system based on the identity of each head while private communication between cluster nodes in a same cluster head is achieved through the random key preliminary distribution system. Considering the characteristics of WSN, we adopt dynamic means called dynamic cluster key management scheme to deal with master key, so master key will be updated according to the changed dynamic network topology. For cluster head node plays a pivotal role in this scheme, a trust manage-ment system should be introduced into the election of the cluster head which will exclude the malicious node from outside the cluster, thus improve the whole network security.     

Flux-based two-degrees-of-freedom algorithm for three-phase electronic converter control

This letter integrates the tracking robustness of two-degrees-of-freedom control and fast dynamic response of flux-based, pulse-width modulation to develop a new current controller for high performance, three-phase electronic converter control. Theoretical analysis shows that the controller can simultaneously achieve good steady-state, transient and harmonic performance, which are challenges not previously met by existing current controllers reported in the literature. Experimental results are presented to verify the performance and practicality of the proposed controller.     

舰基空基导弹的综合环境适应性研究

以美军标为基础,从导弹经历的环境历程、双平台环境的相同点和不同点以及每种发射平台各自的环境特点几方面,对舰基空基双平台发射导弹的综合环境适应性进行了研究,并提出了双平台发射导弹所应满足的综合环境适应性要求.     

Vertical Nonvolatile Schottky-Barrier-Field-Effect Transistor with Self-Gating Semimetal Contact

Emerging 2D nonvolatile Schottky-barrier-field-effect transistors (NSBFETs) are envisaged to build a promising reconfigurable in-memory architecture to mimic the brain. Herein, a vertically stacked multilayered graphene (MGr)-molybdenum disufide (MoS₂)-tungsten ditelluride (WTe₂) NSBFET is reported. The semimetal WTe₂ with the charge-trapping effect enables the simultaneous integration of the electrode and the self-gating function. The effective Schottky barrier height offset ΔΦ_B is programed from ΔΦ_B-p = 132.6 meV to ΔΦ_B-n = 109.4 meV, inducing the reversed built-in electric field to make the NSBFET, so as to provide one with a multifunctional platform to integrate the nonvolatility and the reconfigurable self-powered photo response. The reversible open-circuit voltages of NSBFET synapse are programmed from −0.1 to 0.25 V and the self-powered responsivity with reversed signs is tuned from 290 to −50 mA W⁻¹, which enables the representation of a signed weight in a single device to enrich multiple optical sensing and computing capabilities.     

一种弹载陀螺信号采集系统

为了利用陀螺仪更为准确地测定弹体姿态信息,基于模拟/数字转换理论设计一种基于STM32的高速度、高精度、大量程的信号采集系统。分析弹载信号采集系统的设计要求及现有采集系统的优缺点,介绍系统信号采集的原理和硬件设计,并对可能存在的误差进行分析,利用滤波算法消除误差。验证结果表明:该设计方法为弹载计算机提供实时稳定的陀螺数据信息,能够满足弹载环境信号采集的要求。     

Generalised nearest feature line for subspace learning

Nearest feature line (NFL) is a powerful tool in pattern recognition, which generalises the representational capacity of available prototypes by using linear interpolation and extrapolation between the feature points. NFL is generalised to subspace learning so that the obtained subspace has desirable discriminating ability. Experiments on face recognition demonstrate its effectiveness.     

The influence of solder volume and pad area on Sn–3.8Ag–0.7Cu and Ni UBM reaction in reflow soldering and isothermal aging

This paper examines various aspects of SAC (Sn–3.8Ag–0.7Cu wt.%) solder and UBM interactions which may impact interconnection reliability as it scales down. With different solder joint sizes, the dissolution rate of UBM and IMC growth kinetics will be different. Solder bumps on 250, 80 and 40 μm diameter UBM pads were investigated. The effect of solder volume/pad metallization area (V/A) ratio on IMC growth and Ni dissolution was investigated during reflow soldering and solid state isothermal aging. Higher V/A ratio produced thinner and more fragmented IMC morphology in SAC solder/Ni UBM reflow soldering interfacial reaction. Lower V/A ratio produced better defined IMC layer at the Ni UBM interface. When the ratio of V/A is constant, the IMC morphology and growth trend was found to be similar. After 250 h of isothermal aging, the IMC growth rate of the different bump sizes leveled off. No degradation in shear strength was observed in these solder bump after 500 h of isothermal aging.     

LiFePO4 Particles Embedded in Fast Bifunctional Conductor rGO&C@Li3V2(PO4)3 Nanosheets as Cathodes for High‐Performance Li‐Ion Hybrid Capacitors

The sluggish kinetics of Faradaic reactions in bulk electrodes is a significant obstacle to achieve high energy and power density in energy storage devices. Herein, a composite of LiFePO₄ particles trapped in fast bifunctional conductor rGO&C@Li₃V₂(PO₄)₃ nanosheets is prepared through an in situ competitive redox reaction. The composite exhibits extraordinary rate capability (71 mAh g^?1 at 15 A g^?1) and remarkable cycling stability (0.03% decay per cycle over 1000 cycles at 10 A g^?1). Improved extrinsic pseudocapacitive contribution is the origin of fast kinetics, which endows this composite with high energy and power density, since the unique 2D nanosheets and embedded ultrafine LiFePO₄ nanoparticles can shorten the ion and electron diffusion length. Even applied to Li‐ion hybrid capacitors, the obtained devices still achieve high power density of 3.36 kW kg^?1 along with high energy density up to 77.8 Wh kg^?1. Density functional theory computations also validate that the remarkable rate performance is facilitated by the desirable ionic and electronic conductivity of the composite.