基于深度神经网络和门控循环单元的动态图表示学习方法

学习图中节点的潜在向量表示是一项重要且普遍存在的任务,旨在捕捉图中节点的各种属性。大量工作证明静态图表示已经能够学习到节点的部分信息,然而,真实世界的图是随着时间的推移而演变的。为了解决多数动态网络算法不能有效保留节点邻域结构和时态信息的问题,提出了基于深度神经网络（DNN）和门控循环单元（GRU）的动态网络表示学习方法DynAEGRU。该方法以自编码器作为框架,其中的编码器首先用DNN聚集邻域信息以得到低维特征向量,然后使用GRU网络提取节点时态信息,最后用解码器重构邻接矩阵并将其与真实图对比来构建损失。通过与几种静态图和动态图表示学习算法在3个数据集上进行实验分析,结果表明DynAEGRU具有较好的性能增益。     

0.67 THz ISAR成像雷达收发链路设计

介绍了一种工作频率为0.67 THz的逆合成孔径雷达(ISAR)成像系统,该系统作用距离为2 m~8 m,成像分辨力1 cm×1 cm,采用收发分开的天线,发射信号形式为宽带线性调频连续波信号,可应用于安检和无损检测等多个领域。给出了其收发链路的设计方案,对作用距离、发射功率、信号相噪、分辨率、接收灵敏度、接收增益等指标进行了具体论证,并对收发链路各功能模块的组成结构进行了详细描述,为后续开展成像雷达系统的整机研制工作提供理论基础和技术支持。     

废胎面胶的De—link再生工艺研究

剖析De link再生剂的组成及特点 ,并详细叙述De link再生工艺过程 .用自制的De link再生剂对废旧胎面胶的再生工艺进行实验研究 ,分析再生剂和配合剂的用量及再生时间和再生温度对再生胶性能的影响 .     

细络联的发展方向与研发探讨

针对纺织厂"招工难,用工贵,熟练慢,流失快"的现状,阐明了纺织设备不断革新的趋势与要求。指出:多电机传动是智能化细纱机研发的技术基础。高节能电机是实现自动化、智能化、高效率细络联的关键。细络联合机研发的难点是集中控制技术,同时,细纱工序技术和效益提升的潜力也最大。未来智能化细络联合机的设计、研制与商机,就是要同步实现智能化细络联合机的远程控制,将纺纱工程成功地转型为集高科技、节能、高效率、高品质于一身的自动化、智能化设备优化组合。     

工科专业实践环节与课外科技活动结合模式的探索

在国内外竞争日趋激烈的今天,高校加强大学生创新实践能力的培养,对提高大学生素质极其重要。本文根据高校专业实践环节的特点,分析了学生实践能力培养的现状及形成原因,积极探索大学生课外科技活动与专业实践环节结合的途径和方法。     

A new ZVT–ZCT quasi-resonant DC link for soft switching inverters

In this article, the new ZVT–ZCT Quasi-Resonant DC Link, which ensures zero crossings at any time required for soft switching (SS) and provides zero voltage transition (ZVT) turn-on and zero current transition (ZCT) turn-off together for the main switch of active snubber cell in pulse width modulated or space vector modulated operation of inverter is presented. The new circuit combines the most desirable features of the circuits presented previously and overcomes most drawbacks of these circuits by using only one auxiliary switch with fewer other components. Consequently, new ZVT–ZCT Quasi-Resonant DC Link, which is verified by a prototype of a 1.2 kW and 50 kHz circuit, is analysed in detail. All semiconductor devices operate under SS, the main switch is subjected to no additional voltage and current stresses, and the stress on the auxiliary switch is very low in the proposed new inverter.     

Improved-throughput opportunistic transmission protocol for cooperative communication systems with a preferable-link switching combining

In this article, we propose an opportunistic transmission protocol for cooperative communication systems with L relay nodes under the influence of fading channels. Unlike the protocols previously known in the literature, and given the fact that direct single-link communication outperforms multilink cooperative communication in terms of throughput for same channel conditions, we adopt the channel conditions of the direct link as a main criterion to use whether the direct link in the transmission or the indirect cooperative link. Different performance metrics are derived to demonstrate the performance of the proposed protocol along with a switching combining with a preferable link scheme. These metrics include the bit error rate (BER), outage probability, signal to interference noise ratio (SNR) gain, average throughput and the sum SNR–throughput product (SSTP). The latter performance metric is introduced to compare the maximum achievable throughput as well as the SNR range at a given quality of service (QoS). Our results show that the proposed opportunistic protocol improves the throughput as compared to the conventional cooperative communication systems for the whole range of average SNR. On the other hand, it improves the coverage range as compared to the direct link communication.     

Resonant DC link soft-switching inverter with low-loss auxiliary circuit

An auxiliary switching device is usually set on the DC bus of the resonant DC link inverter, which restricts the efficiency of the inverter and is also one of the reasons for its not extensive application and promotion in the high-power field. To solve the problem, auxiliary circuits and DC bus of the resonant DC link soft-switching inverter designed in this paper are connected in parallel, and auxiliary switching devices and resonant elements are not connected in series on the DC bus, which help to improve the efficiency and reduce the power losses of the auxiliary resonant circuits. Based on the equivalent circuits in different operating modes, the paper analyzes the working process of the soft-switching inverter, soft-switching realization conditions and design rules. A 10 kW laboratory prototype is built, and through the comparison of the experimental results from it and the hard-switching inverter, it is shown that the efficiency improvement value of the designed inverter at full load is higher than that at light load. Therefore, the soft-switching inverter designed in this paper is conductive to reducing the power losses of the auxiliary resonant circuits and ensuring the efficient use of the electric energy.     

基于LACP的链路聚合测试方法研究和实践

基于LACP的链路聚合技术在电信运营商现网部署中被广泛应用,其不仅是一种廉价且有效增加链路带宽的方法,同时也是提高网络稳定性的一种方案.首先简要介绍了LACP的原理,分析了常见应用场景,提出了LACP实验室的验证解决方案,列举了关键参数和测试要点,最后运用网络测试仪进行协议和流量的模拟验证.     

双极性移相控制矩阵式高频链逆变器的研究

针对双向高频逆变器固有的电压冲击和开关损耗问题,采用一种双极性移相控制策略：前级H桥逆变器将直流电压调制成高频矩形波,然后由矩阵变换器解调成双极性SPWM波,经输出滤波后得到正弦波电压。在稳态下,用分析Buck变换器外特性的方法来分析单相矩阵式高频链逆变器的外部特性。通过软件仿真验证了此控制策略的正确性。