50-nm Self-Aligned and “Standard” T-gate InP pHEMT Comparison: The Influence of Parasitics on Performance at the 50-nm Node

Continued research into the development of III-V high-electron mobility transistors (HEMTs), specifically the minimization of the device gate length, has yielded the fastest performance reported for any three terminal devices to date. In addition, more recent research has begun to focus on reducing the parasitic device elements such as access resistance and gate fringing capacitance, which become crucial for short gate length device performance maximization. Adopting a self-aligned T-gate architecture is one method used to reduce parasitic device access resistance, but at the cost of increasing parasitic gate fringing capacitances. As the device gate length is then reduced, the benefits of the self-aligned gate process come into question, as at these ultrashort-gate dimensions, the magnitude of the static fringing capacitances will have a greater impact on performance. To better understand the influence of these issues on the dc and RF performance of short gate length InP pHEMTs, the authors present a comparison between In_0.7Ga_0.3As channel 50-nm self-aligned and "standard" T-gate devices. Figures of merit for these devices include transconductance greater than 1.9 S/mm, drive current in the range 1.4 A/mm, and fT up to 490 GHz. Simulation of the parasitic capacitances associated with the self-aligned gate structure then leads a discussion concerning the realistic benefits of incorporating the self-aligned gate process into a sub-50-nm HEMT system     

双层红外微测辐射热计的微桥结构仿真

非制冷红外探测器具有广阔的军事和民用前景。近年来,出现了一类性能优越的新型双层微测辐射热计型红外探测器。利用有限元分析方法和光学导纳矩阵法详细研究了两种类型的双层微测辐射热计的主要性能。结果表明,双层微测辐射热计的综合性能优于单层微测辐射热计。其中,双层S型结构的温升最优,但其力学稳定性较差,难以满足实践需要;双层U型结构的温升虽低于双层S型结构的温升,但明显优于单层微桥;重要的是,双层U型结构在光吸收性能、力学稳定性、器件制造等方面均优于双层S型结构。所以,双层U型结构的综合性能更优。还设计了一种综合性能更优的改进型双层U型结构。     

Highly Efficient Deep‐Blue Electrophosphorescent Pt(II) Compounds with Non‐Distorted Flat Geometry: Tetradentate versus Macrocyclic Chelate Ligands

A new class of deep blue electrophosphorescent Pt(II) emitters have been designed and synthesized. This new class of deep blue Pt(II) emitters employ tetradentate and macrocyclic chelate chromophores to constrain the Pt(II) molecules in a non‐distorted flat geometry in both the ground state and the excited state. The new deep blue emitters do not produce excimer emission, with emission quantum efficiency as high as 95% in 10% doped PMMA (poly(methyl methacrylate) films, and excellent UV stability, compared to the corresponding bidentate Pt(II) emitters. The macrocyclic tetradentate chelate Pt(II) compounds are the first examples of fully sterically constrained deep blue Pt(II) emitters that do not display structural distortion and have a higher thermal stability and a higher emission quantum efficiency than the corresponding non‐macrocyclic tetradentate Pt(II) analogues. A computational study supports that the macrocylic Pt(II) compounds are structurally more stable than the tetradentate Pt(II) molecules. Bright and efficient deep blue electrophosphorescent devices using a macrocyclic Pt(II) emitter have been successfully fabricated with a maximum brightness of 10 680 cd m^?2, maximum external quantum efficiency of 15.4% (at 490 cd m^?2), and Commission Internationale de L'Eclairage (1931) coordinates (x + y ) of less than or near 0.30, respectively.     

基于媒体用户访问行为偏好模型的代理缓存算法

目前,代理缓存技术广泛应用于改善流媒体传输的服务质量.文章从实际用户日志文件的分析出发,利用发现的用户浏览流媒体对象时的行为分布模型,提出了一种新的视频流媒体缓存算法.仿真结果证明,该算法可以通过记录很少的用户访问信息获取较高的性能表现.     

基于多智能体深度强化学习的D2D通信资源联合分配方法

设备对设备(D2D)通信作为一种短距离通信技术,能够极大地减轻蜂窝基站的负载压力和提高频谱利用率。然而将D2D直接部署在授权频段或者免授权频段必然导致与现有用户的严重干扰。当前联合部署在授权和免授权频段的D2D通信的资源分配通常被建模为混合整数非线性约束的组合优化问题,传统优化方法难以解决。针对这个挑战性问题,该文提出一种基于多智能体深度强化学习的D2D通信资源联合分配方法。在该算法中,将蜂窝网络中的每个D2D发射端作为智能体,智能体能够通过深度强化学习方法智能地选择接入免授权信道或者最优的授权信道并发射功率。通过选择使用免授权信道的D2D对(基于“先听后说”机制)向蜂窝基站的信息反馈,蜂窝基站能够在非协作的情况下获得WiFi网络吞吐量信息,使得算法能够在异构环境中执行并能够确保WiFi用户的QoS。与多智能体深度Q网络(MADQN)、多智能体Q学习(MAQL)和随机算法相比,所提算法在保证WiFi用户和蜂窝用户的QoS的情况下能够获得最大的吞吐量。     

Computation Controllable Mode Decision and Motion Estimation for Scalable Video Coding

This paper proposes an efficient computation‐aware mode decision and search point (SP) allocation algorithm for spatial and quality scalabilities in Scalable Video Coding. In our proposal, a linear model is derived to allocate the computation for macroblocks in enhancement layers by using the rate distortion costs of the base layer. In addition, an adaptive SP decision algorithm is proposed to decide the number of SPs for motion estimation under the constraint of the allocated computation. Experiment results demonstrate that the proposed algorithm allocates the computation resource efficiently and outperforms other works in rate distortion performance under the same computational availability constraint.     

Formaldehyde OTFT Sensors Based on Airbrushed Different Ratios of P3HT/ZnO Films

The formaldehyde (HCHO) detecting at room temperature is of great significance. Different ratios of P3HT/ZnO composite films (3:1, 1:1, and 1:3) were deposited on the organic thin film transistor (OTFT) by spray-deposition technology, and the electrical properties and HCHO-sensing properties of all the prepared OTFT devices were measured by Keithley 4200-SCS source measurement unit. The results show that the OTFT sensor based on the P3HT/ZnO films with the ratio of 1:1 exhibited the best output and transfer curves. Different changing tendency were observed with the increase of ZnO proportion when exposed to HCHO at room temperature, and the device with the ratio of 1:1 behaved a good response and recovery characteristics.     

三种可视化技术在驱油剂评价中的适应性

针对可视化技术在驱油剂评价中适用范围不明确的问题,对比了可视化微观物理驱替模型、计算机X线断层扫描(CT)和核磁共振成像(MRI)三种可视化技术的原理与功能,分析了它们在驱油剂评价中的应用范围与存在的问题。可视化微观物理驱替模型和CT适用于驱油剂驱油机理的研究,前者侧重于微观,后者侧重于宏观;CT和MRI适用于驱油剂驱油性能的评价,前者侧重于轻质油体系下剩余油饱和度的沿程分布,后者侧重于稀油体系下剩余油在不同孔径孔隙内的分布。     

电力线载波通讯在热网温度监测系统中的应用

采用智能温度传感器DS18B20、热电偶及电力线载波应用于热网温度监测系统。建立了系统总体方案和拓扑结构图、选择了温度传感器,及相应的软硬件系统。实际运行表明,该系统抗干扰能力强,信号传输距离远,能够满足监测系统的要求。     

Optical neurochip with learning capability

A dynamic optical neurochip with variable synaptic interconnection capability has been reported. A novel type of photodetector called a variable sensitivity photodetector has been developed for the synaptic interconnection of neural networks. It utilizes a metal-semiconductor-metal structure whose quantum efficiency can be modulated by an applied bias voltage. The fabricated dynamic optical neurochip consists of an 8×8 variable sensitivity photodetector (VSPD) array and an 8 line-shaped LED array. It is shown that this device is suitable for learning in neural networks. The application to pattern classification is demonstrated