High current pulse forming network switched by static induction thyristor

A high-current pulse forming network (PFN) has been developed for applications to artificial solar-wind generation. It is switched by staticinduction thyristor (SIThy) and is capable of generating pulsed current of ~9.7 kA for a time duration of ~1 ms. The SIThy switch module ismade that it can be controlled by an optical signal and it can be operated at elevated electrical potential. The experiments reported in this paperused two switch modules connected in series for maximum operating voltage of 3.5 kV. The experimental results have demonstrated a pulsedhigh-current generator switched by semiconductor devices, as well as the control and operation of SIThy for pulsed power application.

ADAPTIVE PINNING SYNCHRONIZATION OF COUPLED NEURAL NETWORKS WITH MIXED DELAYS AND VECTOR-FORM STOCHASTIC PERTURBATIONS

In this article, we consider the global chaotic synchronization of general cou- pled neural networks, in which subsystems have both discrete and distributed delays. Stochastic perturbations between subsystems are also considered. On the basis of two sim- ple adaptive pinning feedback control schemes, Lyapunov functional method, and stochas- tic analysis approach, several sufficient conditions are developed to guarantee global syn- chronization of the coupled neural networks with two kinds of delay couplings, even if only partial states of the nodes are coupled. The outer-coupling matrices may be symmetric or asymmetric. Unlike existing results that an isolate node is introduced as the pinning target, we pin to help the network realizing synchronization without introducing any iso- late node when the network is not synchronized. As a by product, sufficient conditions under which the network realizes synchronization without control are derived. Numerical simulations confirm the effectiveness of the obtained results.

Selection of Optimal Beam Forming Algorithm for Mobile Ad Hoc Networks

Ad hoc networks have drawn considerable attentions of researchers for the last few years. Various applications of ad hoc networks have been reported in the literatures including disaster management, battle field, environmental management, healthcare, and smart grid. Ad hoc networks have some limitations namely short operating life, unreliability, scalability, delay, high interference, and scarce resources. In order to overcome these limitations, numerous researches have been carried out. Smart antenna integration is one of them. It has been shown in the literatures that smart antenna can improve network’s capacity, increase network lifetime, reduce delay, and improve scalability by directing antenna radiation pattern in a desired direction. But, producing a desired antenna radiation pattern is not a simple task for resource constraint ad hoc networks. A careful selection of beam forming algorithm is required. In this paper we show that smart antenna system, consisting of circular microstrip antennas and arranged in a linear arrangement, is the most suitable choice for ad hoc network. We compare a number of smart antenna algorithms in this paper under different noisy conditions. We show that the Least Square Constant Modulus (LSCM) and Least Constant Modulus (LCM) algorithms outperform other algorithms in terms of directivity and minimized side lobes.

二次B—样条三角面片的Polarform算法

近年来三角B样条曲面（B-patch）作为非张量积曲面在几何造型的拟会和设计中得到了广泛的应用。它以类deCasteljau算法和拓朴三角形形式而使该曲面既有样条函数的整体光滑性，又适于描述非拓扑四边形的情形，特别是适用于有限元网格划分。本文讨论了多元B样条和多元对称仿射变换及其与B—patch的关系和性质，给出在三角划分域上的二次三角B样条曲面的Polarform算法和定义。可方便地应用于曲面设计与拟合的诸多场合。

Optimization of press bend forming path of aircraft integral panel

In order to design the press bend forming path of aircraft integral panels,a novel optimization method was proposed, which integrates FEM equivalent model based on previous study,the artificial neural network response surface,and the genetic algorithm.First,a multi-step press bend forming FEM equivalent model was established,with which the FEM experiments designed with Taguchi method were performed.Then,the BP neural network response surface was developed with the sample data from the FEM experiments.Furthermore,genetic algorithm was applied with the neural network response surface as the objective function. Finally,verification was carried out on a simple curvature grid-type stiffened panel.The forming error of the panel formed with the optimal path is only 0.098 39 and the calculating efficiency has been improved by 77%.Therefore,this novel optimization method is quite efficient and indispensable for the press bend forming path designing.

PHYSICAL SIMULATION AND PROPERTY PREDICTION IN HEAT FORMING PROCESS OF 1Cr18Ni9Ti

Regarding heat forming process of 1Cr18Ni9Ti as typical forming process, this paper presents the study of the effect of various parameters on flow stress, grain size and hardness of formed specimen by means of Gleeble-1500 Thermo-simulation machine and metalloscope. On the basis of technical experi- ment this paper, data are proceeded by applying multilayer feedforward back-propagation neural network, a prediction model of technological parameters together with microstructure and property in the heat forming process is established, thus forging property prediction in the heat forming process is realized.

基于SQL*Forms的图书馆管理系统建设

论述了构建图书馆局域网和利用SQL Forms开发图书馆管理系统的关键技术 。

基于Polar Form算法的三角B样条曲面和三角Bezer曲面间的转化

本文探讨了近来流行的PolarForm方法，该方法在几何造型、CAD、计算机图形学等方面有重要的应用，首先给出了一般三角域的二次B样条曲面片的PolarForm算法，然后讨论了三角域上的B─面片和Bezier面片间的相互转换算法。

Reconfigure ZigBee Network Based on System Design

This article analyses key technology used by network layer based on ZigBee technology. Then a reconfigure network as well as its strategy of forming network and distributing node is given. The simulation proved that the stability of reconfigure network and the ability of transmitting pass through obstacle are better than tradi-tional network;it has an active significance for shorter delay because of the flexible of the improved forming network strategy.

Seismic reliability analysis of urban water distribution network

An approach to analyze the seismic reliability of water distribution networks by combining a hydraulic analysis with a first-order reliability method （FORM）, is proposed in this paper. The hydraulic analysis method for normal conditions is modified to accommodate the special conditions necessary to perform a seismic hydraulic analysis. In order to calculate the leakage area and leaking flow of the pipelines in the hydraulic analysis method, a new leakage model established from the seismic response analysis of buried pipelines is presented. To validate the proposed approach, a network with 17 nodes and 24 pipelines is investigated in detail. The approach is also applied to an actual project consisting of 463 nodes and 767 pipelines. The results show that the proposed approach achieves satisfactory results in analyzing the seismic reliability of large-scale water distribution networks.

Using Neural Network to Predict the Interfacial Friction and Flow Stress of Materials via Ring Compression

In this study a neural network approach is proposed to realize an automatic numerical prediction of the interfacial friction factor and the flow stress of materials. Decrease in the inner diameter and reduction in the height of the ring are taken as input

The Social Network:A Study from the Narrative Perspective

As the most successful social website,Facebook is well received by people all over the world.The Social Network is a film about the establishment of the website and the story between the co-founders.The construction of a film is based on the narrative content,presented by the narrative forms.Therefore,under the framework of narratology,this thesis attempts to analyze the success of the movie by illustrating how the director combines the hearings and the flashback memories skillfully and presents the characters' paradox and complicated inner world through anti-traditional,non-linear and intertextual narrative style.

Design and Analysis of a Compact Band Notch UWB Antenna for Body Area Network

This paper presents the design of a small printed ultra wideband antenna with Band Notched characteristics. Both the free space and on-body performances of this antenna were investigated through simulation. The newly designed UWB antenna is more revised small form factor sized, with the ability to avoid interference caused by WLAN (5.15 - 5.825 GHz) and WiMAX (5.25 - 5.85 GHz) systems with a band notch. The return loss response, gain, radiation pattern on free space of the antenna were investigated. After that, the on-body performances were tested on 3-layer human body model with radiation pattern, gain, return loss, and efficiency at 3.5, 5.7, 8, 10 GHz and all the results were compared with free space results. As the on-body performance was very good, the proposed antenna will be suitable to be used for multi-purpose medical applications and sports performance monitoring.

基于CNN-LSTM混合神经网络的卷烟滤棒质量预测

为了在卷烟生产数据中挖掘出滤棒生产过程的有效信息,解决各批次产品质量检测困难的问题,结合卷积神经网络的特征提取能力与长短期记忆网络处理时序数据的有效性,提出了基于CNN-LSTM混合神经网络的卷烟滤棒质量预测模型。该模型通过卷积层提取输入数据的局部特征,然后在LSTM层中捕捉特征之间的时序关系,分层结构使其具有同时处理不同时间维度信息的能力,从而提升了预测精度。将滤棒的质量定义为圆周值与吸阻值两个物理量,利用卷烟厂6万余条实时生产数据进行模型训练和预测,结果表明:以平均绝对百分误差(MAPE)作为评价标准,圆周指标预测误差为0.078%,吸阻指标预测误差为1.42%,对比各类传统机器学习方法,CNN-LSTM混合神经网络表现出了更高的精确性。该方法可为快速准确地预测卷烟滤棒质量提供技术支持,提升烟草工业的自动化水平。

基于网络平台的翻转课堂在超声影像学教学中的应用

目的探讨基于网络平台的翻转课堂对超声影像学教学效果的影响。方法选取2022年6月—2023年4月华中科技大学同济医学院附属同济医院超声影像科76名接受超声影像学教学的超声科室医师,依据所用教学方法不同分为对照组(n=38)与观察组(n=38)。对照组采用常规教学模式,观察组采取基于网络平台的翻转课堂,回顾性分析2组医师的教学理论与实践考核、教学满意度和对教学过程的认可度。结果观察组的教学理论考核[(96.54±1.18)分]、实践考核[(93.52±1.30)分]高于对照组[(91.80±2.30)分、(85.65±5.25)分],差异有统计学意义(P<0.001);观察组的教学满意度(100%)高于对照组(84.21%),差异有统计学意义(P<0.05);通过调查问卷,观察组对思维能力培养、沟通能力、学习兴趣、知识理解、提升实际应用能力的认可度高于对照组,差异有统计学意义(P<0.05)。结论超声影像学教学中采取基于网络平台的翻转课堂,能够提升整体教学质量,帮助医师提升超声影像学阅片与分析能力,更好地适应临床超声科日常工作,保证工作质量。

基于TCN的跟网/构网混合型新能源场站并网系统小干扰稳定性快速评估

为支撑跟网/构网混合型新能源场站中机组控制方式快速切换,实现可适应电网强度变化的新能源场站安全稳定运行,提出基于时间卷积神经网络(temporal convolutional network,TCN)的跟网/构网混合型新能源场站并网系统小干扰稳定性快速评估方法。首先,构建跟网/构网混合型新能源场站聚合阻抗模型,通过特征值计算得到并网系统小干扰稳定裕度。然后,以并网系统短路比和新能源场站跟网/构网控制方式信息作为输入特征,以并网系统小干扰稳定裕度和阻尼比作为输出特征,训练TCN得到混合型新能源场站并网系统小干扰稳定性快速评估模型。经过训练的模型可根据短路比和跟网/构网混合型新能源场站中各机组的控制方式快速输出对应的小干扰稳定裕度和阻尼比。最后,以一个含10台风电机组的新能源场站为对象进行算例分析。结果表明:所提TCN方法相比于长短期记忆神经网络方法,在小干扰稳定裕度和阻尼比预测上的平均绝对百分比误差分别降低16.76%、14.75%;所提方法的计算耗时相对于特征值计算方法降低98.54%,从而验证所提小干扰稳定性快速评估方法的准确性与时效性。

双碳目标下我国配电网形态快速演进的思考

许多国家大力推动能源转型,新能源快速发展,终端用能电气化水平不断提升,促进配电网形态逐渐演进。我国碳达峰到碳中和时间跨度仅为发达国家的1/2,配电网面临补短板、保增长、促转型的多重使命,形态演进的程度更加剧烈。该文提出按照城市、园区、农村3类场景和网络架构、技术管控、商业运营3种形态分析配电网变革演进的分类方法,研判配电网形态演进的驱动力、关键环节和宏观目标,认为:城市配电网将向着“大电网主导、负荷柔性化调控、新型储能灵活配置的配用电系统”演进,园区配电网将向着“大电网支撑、多能互补型的综合能源系统”演进,农村配电网将向着“分布式新能源和储能主导,与大电网互联的新型局域电力系统”演进。政产研用各相关利益主体宜建立系统思维,运用系统方法,协同源网荷储各要素有序友好地推进配电网规划、建设和运营。

L波段全国产化2.5 kW级脉冲模块设计

随着国防和民用技术的迅速发展,高性能的L波段脉冲模块成为雷达和通信领域的关键组件。文章介绍了一个全国产化的2.5 kW级L波段脉冲模块的设计流程。该模块采用先进的射频放大技术和脉冲形成网络设计,结合本土材料和工艺技术的优势,实现模块的高性能和低成本生产。仿真和实验验证表明,设计的模块满足了所有预期的技术参数,包括功率水平、脉冲宽度和效率,通过了严格的质量控制和可靠性评估。

电力电子组网系统中构网型换流器间的协同限流研究

新能源快速发展下带来的100%电力电子设备组网独立运行的场景逐渐增多,由于缺乏传统同步发电机的惯性和阻尼,当基于不同控制类型的构网型换流器为系统提供电压和频率支撑时,其对外部干扰较敏感,负荷大扰动情况下,系统存在明显的过流问题。针对该问题,首先对单端构网型换流器设计了一种基于电流饱和算法的过电流抑制方法,以限制端口换流器的暂态过电流。其次,在多端口换流器协同限流方面,提出了一种基于不同控制类型的构网型换流器间协同限流控制方法,解决了不同构网型换流器组网时由于扰动造成的输出过电流问题,并实现限流控制与正常工作模式间的平滑切换。同时,建立系统的小信号模型,利用根轨迹分析主要控制参数对系统稳定性的影响。最后,搭建了控制器级硬件在环测试平台,对理论分析和所提方法进行了硬件在环测试,验证了所提方法的有效性和优越性。