蓝宝石衬底上原子级光滑AlN外延层的MOCVD生长

在蓝宝石衬底表面无氮化、低Ⅴ/Ⅲ比的情况下,采用1200℃的衬底温度、5kPa反应室气压,用MOCVD方法在蓝宝石衬底上生长出了表面原子级光滑的AlN外延层.原子力显微镜测试表明其平均粗糙度为0.44nm,X射线衍射(0002)回摆曲线FWHM为166".实验结果和分析表明,极性和气相反应是影响AlN表面形貌的主要原因.以原子级光滑的AlN为模板生长出了高质量的高Al组分的n型AlGaN,证实了AlN模板具有较好的质量.     

一种用于提取超大规模集成电路电容的新型库查找法

提出了八种节点电容典型结构用以建立电容模型库,并阐明了这八种结构可以提取大多数VLSI互连线的电容参数,给出了这些结构的拟合公式.采用该库查找法计算的互连线电容结果与FastCap所得结果非常吻合.由于电容是直接代入拟合公式计算得到的,所以计算速度非常快.     

Adaptive fuzzy sliding mode active queue management algorithms

Active queue management (AQM) is aimed at achieving the tradeoff between link utilization and queuing delay to enhance TCP congestion control and is expected to perform well for a wider-range of network conditions. Static AQM schemes despite their simplicity, often suffer from long response time due to conservative parameter setting to ensure stability. Adaptive parameter settings, which might solve this problem, remain difficult from implementation point of view. In this paper, we propose an adaptive fuzzy sliding mode (AFSM) AQM algorithm to achieve fast response and yet good robustness. The AFSM algorithm uses the queue length and its differential as the input of AQM and adjusts fuzzy rules by the measurement of packet loss ratio dynamically. The stability analysis under heterogeneous round trip times provides guidelines for parameter settings in AFSM and guarantees that the stability of AFSM is independent of the active TCP flows. This merit as well as other performances is examined under various network environments. Compared to some typical AQMs, the AFSM algorithm trades off the throughput with queuing delay better and achieves a higher per-flow throughput. Finally, AFSM can be executed at a scale of seconds with the least fuzzy rules.     

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).     

基于语音控制的舞蹈机器人的设计与制作

本文主要介绍了基于语音控制的舞蹈机器人的设计与制作过程。通过对舞蹈机器人机械、电气和程序的设计与实现,使机器人完成优美的舞蹈动作。行走电机采用继电器控制,以AT89S51单片机为中央处理器,实现各种舞蹈动作,采用语音识别技术实现语音控制。     

Research on topology control based on Voronoi diagram algorithm in FSO networks

Telecommunication Systems - In a wireless sensor network (WSN) where positioning information is not assumed or is partially available, efficient data access is a very challenging issue especially...     

Distributed User Association with Resource Partitioning in Heterogeneous Cellular Networks

To fully utilize the resources of heterogeneous cellular networks (HCNs), an effective approach that offloads users to the underloaded small cells from overloaded macrocells is widely advocated. However, this operation often leads to a bad result that the offloaded users achieve lower signal-to-interference-plus-noise-ratio (SINR) than these users in macrocells. Thus, some appropriate interference avoidance techniques should be adopted to partially alleviate the SINR degradation. For this, we consider the resource (frequency) partitioning that turns off some fraction of such resources in a macrocell. Naturally, an optimal offloading strategy should be closely coupled with resource partitioning, and in turn the optimal partition decides the offloading performance. In this paper, we propose a distributed association strategy with joint offloading and resource partitioning for HCNs. We reveal that load balancing, by itself, is insufficient, and additional resource partitioning is required to improve system performance. Meanwhile, we also show that, compared with the best power association and range extension association, the proposed scheme provides better association performance.

     

工业互联网标准化工作现状与策略研究

工业互联网是典型的交叉融合领域,原有信息通信领域和工业领域的标准无法完全适用于工业互联网,为有效推进工业互联网有序发展,避免标准缺失、交叉、重复等问题,急需形成统筹协作、目标明确、高效高质的标准化工作平台环境,加快相关标准研制,推进工业互联网有序发展。     

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。