3D FDTD Implementation for Scattering of Electric Anisotropic Dispersive Medium Using Recursive Convolution Method

The finite-difference time-domain method based on recursive convoltion method (RC-FDTD) for the electric anisotropic dispersive medium is discussed in detail. To exemplify the availability of the three-dimensional RC-FDTD algorithm, the backscattering Radar-Cross-Section(RCS) of a non-magnetized plasma sphere is computed, and the numerical results are the same as the one of the Shift Operater-FDTD method, and show that the RC-FDTD method is correct and efficient. In addition, the co-polarized and cross-polarized backscattering time-domain of a magnetized plasma sphere are obtained by the RC-FDTD algorithm. The results show that when the external magnetic field is implemented, the cross-polarized component appear, evidently.     

Noncooperative Differential Game Based Efficiency-aware Traffic Assignment for Multipath Routing in CRAHN

Comparing to the traditional multihop ad hoc networks, dynamic spectrum environment is the special characteristic of CRAHN (cognitive radio ad hoc networks). Therefore, the cognitive users will show their selfishness on spectrum bandwidth cost in multihop communication. In CRAHN, multipath routing is a reasonable choice when considering efficiency and stability. In order to take further advantage of efficiency of multipath routing, this paper study the efficiency-awareness traffic assignment problem of multipath routing in CRAHN. There are several existing game based traffic assignment schemes for selfish wireless network, however, all of them can not be directly applicable to CRAHN. In addition, none of the existing works studied whether the scheme is efficient. In this paper, a noncooperative differential game is proposed, and the equilibrium of the game is computed and proved to be an efficient traffic assignment for multipath routing in CRAHN. Besides this, we also optimize the total cost of game from the game designer’s point of view, and give a simple example to illustrate the optimization procedure.     

结合地物分类的湿地蒸散量定量遥感集成模型

湿地蒸散发量是湿地水量支出的重要组成部分。利用遥感技术可以合理有效地计算出地形复杂的湿地的蒸散发量。将遥感图像分类技术与定量遥感蒸散发模型结合起来,考虑各类地物不同的蒸散发源和水热传输机制,建立了集成模型,分析和计算了湿地主要地物的蒸散发量。通过对各地物类的样区平均蒸散发量与实测数据进行比较,证明结合地物分类的湿地蒸散发量计算集成模型能够取得很好的结果。     

Self-Adhesive Polydimethylsiloxane Foam Materials Decorated with MXene/Cellulose Nanofiber Interconnected Network for Versatile Functionalities

Polydimethylsiloxanes (PDMS) foam as one of next-generation polymer foam materials shows poor surface adhesion and limited functionality, which greatly restricts its potential applications. Fabrication of advanced PDMS foam materials with multiple functionalities remains a critical challenge. In this study, unprecedented self-adhesive PDMS foam materials are reported with worm-like rough structure and reactive groups for fabricating multifunctional PDMS foam nanocomposites decorated with MXene/cellulose nanofiber (MXene/CNF) interconnected network by a facile silicone foaming and dip-coating strategy followed by silane surface modification. Interestingly, such self-adhesive PDMS foam produces strong interfacial adhesion with the hybrid MXene/CNF nano-coatings. Consequently, the optimized PDMS foam nanocomposites have excellent surface super-hydrophobicity (water contact angle of ≈159^o), tunable electrical conductivity (from 10⁻⁸ to 10 S m⁻¹), stable compressive cyclic reliability in both wide-temperature range (from −20 to 200 ^oC) and complex environments (acid, sodium, and alkali conditions), outstanding flame resistance (LOI value of >27% and low smoke production rate), good thermal insulating performance and reliable strain sensing in various stress modes and complex environmental conditions. It provides a new route for the rational design and development of advanced PDMS foam nanocomposites with versatile multifunctionalities for various promising applications such as intelligent healthcare monitoring and fire-safe thermal insulation.     

Highly Crystalline Soluble Acene Crystal Arrays for Organic Transistors: Mechanism of Crystal Growth During Dip‐Coating

The preparation of uniform large‐area highly crystalline organic semiconductor thin films that show outstanding carrier mobilities remains a challenge in the field of organic electronics, including organic field‐effect transistors. Quantitative control over the drying speed during dip‐coating permits optimization of the organic semiconductor film formation, although the kinetics of crystallization at the air–solution–substrate contact line are still not well understood. Here, we report the facile one‐step growth of self‐aligning, highly crystalline soluble acene crystal arrays that exhibit excellent field‐effect mobilities (up to 1.5 cm V^?1 s^?1) via an optimized dip‐coating process. We discover that optimized acene crystals grew at a particular substrate lifting‐rate in the presence of low boiling point solvents, such as dichloromethane (b.p. of 40.0 °C) or chloroform (b.p. of 60.4 °C). Variable‐temperature dip‐coating experiments using various solvents and lift rates are performed to elucidate the crystallization behavior. This bottom‐up study of soluble acene crystal growth during dip‐coating provides conditions under which one may obtain uniform organic semiconductor crystal arrays with high crystallinity and mobilities over large substrate areas, regardless of the substrate geometry (wafer substrates or cylinder‐shaped substrates).     

Analysis of issues in gate recess etching in the InAlAs/InGaAs HEMT manufacturing process

We have developed an InAlAs/InGaAs metamorphic high electron mobility transistor device fabrication process where the gate length can be tuned within the range of 0.13 μm–0.16 μm to suit the intended application. The core processes are a two-step electron-beam lithography process using a three-layer resist and gate recess etching process using citric acid. An electron-beam lithography process was developed to fabricate a T-shaped gate electrode with a fine gate foot and a relatively large gate head. This was realized through the use of three-layered resist and two-step electron beam exposure and development. Citric acid-based gate recess etching is a wet etching, so it is very important to secure etching uniformity and process reproducibility. The device layout was designed by considering the electrochemical reaction involved in recess etching, and a reproducible gate recess etching process was developed by finding optimized etching conditions. Using the developed gate electrode process technology, we were able to successfully manufacture various monolithic microwave integrated circuits, including low noise amplifiers that can be used in the 28 GHz to 94 GHz frequency range.     

基于微扰法研究涡旋光束在大气中传输的热晕效应

基于一阶微扰法,推导了涡旋光束在大气中传输的稳态热晕解析表达式,并得到了由热晕引起的涡旋光束的相位畸变表达式.通过数值模拟涡旋光束在大气中传输的光强等值线分布,详细分析了传输距离、初始功率、横向风速、大气吸收系数和初始半径对涡旋光束热晕的影响.研究结果表明,在其他参数不变的情况下,单一增大涡旋光束的初始功率、传输距离和...     

容积信息粒子多传感器融合算法

为提高多传感器融合的精确度,提出一种容积信息粒子多传感器融合算法。算法将容积信息滤波(CIF)和粒子滤波(PF)结合一起,采用CIF传递PF的粒子,通过引入信息贡献向量和信息贡献矩阵,将多个传感器的量测信息更新到PF的粒子中,提高粒子与真实状态后验概率分布的逼近程度,改进多传感器融合精确度。同时将CIF估计值作为粒子,消除随机扰动对融合的影响,提高粒子有效度,进一步提高融合精确度。仿真与实验表明,算法能够有效处理集中式多传感器融合问题,具有较高的滤波精确度。     

A blockchain-based online language learning system

To check students’ daily language learning tasks and give students corresponding reasonable scores based on their daily behavior is hard for teachers. The existing online language learning systems are vulnerable and easy to be modified by teachers or system managers. Blockchain can provide immutable and trusted storage service and automatic calculation service. Therefore, a blockchain-based online language learning system is proposed in this paper to monitor students’ daily study and automatically evaluate their behavior so as to save teachers from tedious and complex homework verification workload and provide trusted and reliable evaluation on students’ behavior. This paper first introduces the current situation of language learning in universities and the related works on blockchain-based online language learning system. Then the system is detailed in its structure and smart contracts. At last, we implement this system and do the analysis and summary.

     

基于大数据和AI的智能化PeOTN-CO价值分级建网创新与实践

对某省联通PeOTN-CO价值分级建网方法论及实践进行了论述,通过市场空间大数据分析、AI算法及存量政企专线路径和流量等分析,对全省综合业务接入区(CO)进行价值分级,提出聚类标杆配置模型,优先预覆盖高价值综合业务接入点,次优先覆盖中低价值区域,实现政企精品网的价值精准建网,进而全面实现以PeOTN技术为主的本地光网络边缘延伸,打造智能光网络,适配新基建时代的“大带宽”“低时延”等业务需求特征,有效降低网络成本并提高短期投资回报率。