Agent-based Collaborative Design Framework Supporting Synchronization and Asynchronization on Internet

On the basis of analysis of the research issues and requirement of collaborative design, we propose the overall framework of agent based collaborative design on Internet. Then, we describe the implementation of synchronous and asynchronous collaborative design process based on standardized design activities under the overall framework. In order to realize design message passing, the DMP Protocol is proposed as well in this paper and described in detail.

Asynchronism-synchronism of regional precipitation in South-to-North Water Transfer planned areas

This paper proposes a method on analyzing the asynchronism-synchronism of precipitation of different hydrological regions regarding the S-to-N water transfer areas of eastern China. The general process of the analysis includes three steps. Firstly, we created the rainfall series of the region concerned by calculating the regional average rainfall of the stations in the area with the help of the classical Thiessen Polygon method. Secondly, the standards of assessment indices for wetness or dryness are set according to Gamma distribution function with a certain probability P 37.5% or 62.5% given respectively. Finally, the frequency of nine combinations are counted as the quantitative feature of asynchronism and synchronism in three time scales, that is the yearly, seasonal and monthly scales. The asynchronism-synchronism of two region pairs has been estimated. The results show that the frequency of precipitation asynchronism in 1957–1998 is larger than the synchronism frequency for both the North China-middle and lower Yangtze River pair and for the North China-upper Hanjiang River pair. As for the synchronism phenomena, the frequency of Nd?Sd is rather low. As the combinations that are suitable for water transfers are Nd?Sw, Nn?Sw, Nd?Sn and Nn?Sn, the total frequency of these combinations for North China-middle and lower Yangtze River is 40% on an annual basis, but only 28% in spring when water shortages are most likely to occur. The total frequency of these combinations for North China-upper Hanjiang River is about 24% on an annual basis, but 35% in spring and winter. It should be noted that if future precipitation patterns are similar to that of the period 1957–1998, it is very important to change the natural character of asynchronism-synchronism by enhancing the capability of hydro-projects regulation and improving management of the water transfer project.

The Paralleling of High Power High Frequency Amplifier Based on Synchronous and Asynchronous Control

The vertical position of plasma in the HT-7U Tokamak is inherently unstable. In order to realize active stabilization, the response rate of the high-power high-frequency amplifier feeding the active control coils must be fast enough. This paper analyzes the paralleling scheme of the power amplifier through two kinds of control mode. One is the synchronous control; the other is the asynchronous control. Via the comparison of the two kinds of control mode, both of their characteristics are given in the text. At last, the analyzed result is verified by a small power experiment.

Examinees’Affective Preference for Online Speaking Assessment:Synchronous VS Asynchronous

With technological advancement and the COVID pandemic,online speaking assessment is increasingly used in language teaching.Two modes are developed:online synchronous testing(direct human-to-human interview)and online asynchronous testing(semi-direct human-to-machine interview).Ample literature has explored how each of the two online modes differs from traditional face-to-face speaking assessments.However,few studies have investigated the differences between the two modes,especially in terms of examinees’affective preferences.This study,therefore,compares the extent to which each mode is accepted and favored by test takers and explores why such an affective preference emerges.The participants are 46 college students enrolled in an Elementary Chinese course.They completed a survey that investigates their level of motivation,self-confidence,and anxiety in the two types of online speaking tests.An open-ended question item solicited further explanations from test-takers.Results showed a strong affective preference for synchronous assessment,as manifested by a higher level of motivation and self-confidence and a lower level of anxiety.Possible reasons are discussed based on students’written responses.The study is theoretically significant as it identifies factors on student experience and performance in online speaking assessments.It also provides practical guidance for language teachers in optimizing online oral tests.

Comprehensive Energy-Saving Optimization Model of Asynchronous Motor for Voltage Regulation Based on Static Synchronous Compensator

There are several problems existing in the direct starting of asynchronous motor such as large starting current,reactive power absorption from network side and weak interference-resistance,etc.Aiming at this,a comprehensive energy-saving optimization model of asynchronous motor for voltage regulation based on static synchronous compensator(STATCOM)is put forward.By analyzing the working principle and operation performance of static synchronous compensator regulating voltage,a new energy-efficient optimization method for asynchronous motor is proposed based on the voltage regulator model to achieve soft start,continuous dynamic reactive power compensation and the terminal voltage stability control.The multi-objective optimal operation of asynchronous motor is realized by controlling the inverter to adjust the reactive current dynamically.The strategy reduces the influence of starting current and grid voltage by soft starting,and realizes the function of reactive power compensation and terminal voltage stabilization.The effectiveness and superiority of the proposed model is verified by the simulation analysis and the results of comparison with the motor started directly.

An Investigation of English Language Learning in Synchronous （SL） and Asynchronous （ASL） E-Learning

This study investigated the factors affecting the English language learning of students in SL （synchronous） and ASL （asynchronous） e-learning. The subjects were 102 undergraduate students at Bang Khen and Kamphaengsaen Campus, Kasetsart University. Before the experiment, the subjects answered an online questionnaire adopted from Reid （1998） to measure their perceptual learning style preferences. Then, they were grouped according to their English grades and were randomly assigned to two experimental groups. Each group was given learning tasks requiring different cognitive strategies. The two groups received two treatments with SL and ASL simultaneously. After each treatment, both groups were tested. They were given a questionnaire at the end of the treatments to retrieve their opinions, Data from both tests were analyzed using 2 ~ 2 factorial ANOVA repeated measures. The results showed no significant difference between the two tasks and no interaction effect among types of tasks and SL and ASL. However, a significant difference was found between SL and ASL. The results of the survey showed that the subjects preferred ASL which was in contrast to the results from statistical analyses. The learning style preferences of the two experiment groups were not different; therefore, they were not the factors in the analysis

Asynchronous and Synchronous Communication in College English Writing in Web-based Learning Environment

In web-based learning environment,College English writing has always been a thorny issue.Here both asynchronous and synchronous communications in college English writing mean the new interactive teaching belief. This paper attempts to do the blending of two in the traditional writing learning and teaching in college English in order to promote a more flexible,efficient and interactive learning environment in accordance with students' interests and needs.

基于柔直控制的南方电网异步联网频率同步运行控制器设计与应用

电网分区异步运行将成为未来南方电网发展趋势,针对分区异步电网间频率失去了同步性和一致性问题,开展分区异步电网频率同步运行控制策略研究,提出了分区异步电网频率同步运行控制器结构,优化确定运行关键控制参数并通过仿真验证其有效性。鲁西柔直工程作为试点实施分区异步电网频率同步运行,现场实施效果表明该控制能够有效保证分区异步运行电网间实际运行中频率的一致性和同步性,且与电网AGC策略具有良好的适配性,实施中未出现两侧电网功率振荡和频率振荡发散情况,有效改善分区电网频率稳定性和提升分区电网间功率的灵活性支援性能,同时也实现全网调频资源的实时、自动共享,推动构建全网统一的调频辅助服务市场。

考虑用电和馈电模式的变流器电驱系统建模与稳定性分析

由大量异步电机驱动设备构成的电力电子化交流配用电系统存在严重的次/超同步振荡问题。电驱系统正常工作时具有用电和馈电2种运行模式,现场振荡现象表明不同的运行模式对系统的稳定性影响也不同。建立了含机侧系统的电驱系统详细阻抗模型,利用阻抗分析法揭示了电驱系统接入电网的次/超同步振荡机理,分析了运行模式、电网强度、控制参数、交流电压幅值等因素对系统次/超同步稳定性的影响,并基于相位裕度灵敏度明确了主导影响因素。基于实际系统数据,搭建了时域仿真模型,仿真复现了振荡现象,并验证了理论分析的正确性。

交⁃直⁃交异步系统准同步控制下直流动态功频响应特性分析

经直流输电互联的异步系统通过对直流输电实施附加控制,可实现异步系统的准同步运行,达到实时共享异步系统调频资源的目的。但在准同步控制的工程实践中,不合理的控制结构或参数配置将导致系统出现非预期的功率波动。首先,根据直流准同步附加控制,构建准同步系统的动态功频响应分析模型;然后,基于该模型分析了直流控制参数对功率振荡的影响;进而,分析准同步控制导致的功率波动与传统功角振荡的异同;最后,以准同步实验过程中出现的功率波动为例进行分析验证,提出抑制直流功率波动的建议,并对准同步控制进行了讨论。

中老铁路互联网售票系统设计与应用

为提升中老(中国—老挝)铁路客运服务水平,方便旅客购票出行,设计中老铁路互联网售票系统。结合服务化分层设计理念,详细阐述了该系统的总体架构和逻辑架构,并重点研究了分布式缓存处理、数据同步机制、异步排队交易、支付本地化适配及消息通知自动化监控等关键技术,解决了大量用户高并发下的实时余票查询、异步排队交易、以及分布式系统数据一致性等技术难题,不仅提升了老挝旅客出行购票体验,也提高了中老铁路客运服务质量和运营组织效率,助推中老铁路向数字化、网络化、服务化方向发展。

Multi-Objective Loosely Synchronized Search for Multi-Objective Multi-Agent Path Finding with Asynchronous Actions

In recent years,the path planning for multi-agent technology has gradually matured,and has made breakthrough progress.The main difficulties in path planning for multi-agent are large state space,long algorithm running time,multiple optimization objectives,and asynchronous action of multiple agents.To solve the above problems,this paper first introduces the main problem of the research:multi-objective multi-agent path finding with asynchronous action,and proposes the algorithm framework of multi-objective loose synchronous(MO-LS)search.By combining A*and M*,MO-LS-A*and MO-LS-M*algorithms are respectively proposed.The completeness and optimality of the algorithm are proved,and a series of comparative experiments are designed to analyze the factors affecting the performance of the algorithm,verifying that the proposed MO-LS-M*algorithm has certain advantages.

Harmonics in the Squirrel Cage Induction Motor Analytic Calculation Part III: Influence on the Torque-speed Characteristic

The harmonics that appear in the squirrel cage asynchronous machine have been discussed in great detail in the literature for a long time. However, the systematization of the phenomenon is still pending, so we made an attempt to fill this gap in the previous parts of our study by elaborating formulas for calculation of parasitic torques. It was a general demand among those who work in this field towards the author to verify his formulas with measurements. In the literature, it seems,only one detailed, purposeful series of measurements has been published so far, the purpose of which was to investigate the effect of the number of rotor slots on the torque-speed characteristic curve of the machine. The main goal of this study is to verify the correctness of the formulas by comparing them with the referred series of measurements. Relying on this, the expected synchronous parasitic torques were developed for the frequently used rotor slot numbers-as a design guide for the engineer.Thus, together with our complete table for radial magnetic pull published in our previous work, the designer has all the principles, data and formulas available for the right number of rotor slots for his given machine and for the drive system. This brings this series of papers to an end.

大功率带式输送机变频驱动方式比较研究

以某输煤项目为研究对象,分析了该项目大功率带式输送机的驱动配置特点,对比了2种主流变频驱动方式在项目应用中的技术优缺点,全面系统归纳了2种主流变频驱动方式的初期投资成本差异,计算得出了75%负载下2种变频驱动方式的项目耗电量差值,给出了永磁同步变频电机的选型建议。

基于Matlab的锁相环频率合成器教学实践

通信系统性能好坏很大程度上取决于有没有一个良好的同步系统。在“通信原理”课程中提到了基于锁相环的同步系统,但是对这部分内容介绍简单,没有系统的推导以及结论。基于Matlab的锁相环系统,能够得到不同参数下的锁相环的环路滤波器幅频响应和闭环响应,在Simulink工具箱中,设计一个基于锁相环的频率合成器,让学生可以较好地掌握锁相环相位锁定的原理以及同步系统,为“通信原理”课程学习提供了支持。

燃气轮发电机同期回路加装闭锁继电器的研究与应用

某些燃气轮发电机同期回路未配置闭锁继电器,存在非同期并网的安全隐患。为解决此问题,对某电厂燃气轮发电机同期回路进行研究,提出了在其同期回路中加装闭锁继电器的方案,进行闭锁继电器和中间继电器选型。现场试验证明,该方案能够提高燃气轮发电机同期并列的可靠性,达到了消除非同期并列安全隐患的目的,可为同类型燃气轮发电机同期回路加装闭锁继电器提供借鉴。

基于异步电机改造的永磁同步电机控制系统设计与实现

本研究基于异步电机改造为永磁同步电机的控制系统设计与实现,通过在异步电机转子上添加永磁体,提高了电机的效率和功率因数。采用矢量控制原理,建立了电机的数学模型,并设计了相应的硬件和软件系统。实验结果表明,这一控制系统能够快速、准确地跟踪速度指令,具有良好的速度调节性能和稳定性,为电动汽车驱动系统提供了可行的解决方案。

异步时滞布尔网络的内同步

提出异步时滞布尔网络的内同步模型,通过利用矩阵半张量积理论,研究异步时滞影响下的布尔网络内同步问题,分析时滞对布尔网络内同步的影响,给出了异步时滞布尔网络内同步实现的充分必要条件.通过数值仿真实例进一步验证了该模型的可行性以及所得结果的正确性.

基于自学习的组合式门吊高铁道岔智能铺换多机协同微动控制研究

针对高铁线路道岔铺换过程中存在的施工难度大、效率低、工人劳动程度高以及危险系数大等问题,文章提出了一种多门吊组合式高铁线路道岔智能铺换装备控制方法。其采用组合式门吊异步横移与同步倾斜控制方案分别实现大部件的旋转及纵移功能,并对组合式门吊铺换装备的旋转及纵移作业工况进行了理论数学建模分析;同时,结合组合式多门吊实际施工过程链条的柔性特征,采用自学习算法进行多机协同柔性高精度微动控制。现场作业试验结果表明,采用本文所提控制方法,组合式多门吊的旋转、纵移动作功能运行稳定可靠,运行误差在10 mm以内,满足工程使用要求。

Non-PLL high-precision synchronous sampling method among lots of acoustics acquisition channels for underwater multilinear array seismic exploration system

Synchronous sampling is very essential in underwater multilinear array seismic exploration system in which every acquisition node(AN)samples analog signals by its own analog-digital converter(ADC).Aiming at the problems of complex synchronous sampling method and long locking time after varying sampling rate in traditional underwater seismic exploration system,an improved synchronous sampling model based on the master-slave synchronous model and local clock asynchronous drive with non phase locked loop(PLL)is built,and a high-precision synchronous sampling method is proposed,which combines the short-term stability of local asynchronous driving clock with the master-slave synchronous calibration of local sampling clock.Based on the improved synchronous sampling model,the influence of clock stability,transmission delay and phase jitter on synchronous sampling error is analyzed,and a high-precision calibration method of synchronous sampling error based on step-by-step compensation of transmission delay is proposed.The model and method effectively realize the immunity of phase jitter on synchronous sampling error in principle,and compensate the influence of signal transmission delay on synchronous sampling error.At the same time,it greatly reduces the complexity of software and hardware implementation of synchronous sampling,and solves the problem of long locking time after changing the sampling rate in traditional methods.The experimental system of synchronous sampling for dual linear array is built,and the synchronous sampling accuracy is better than 5 ns.