工业以太网技术在李庄闸自动化控制系统中的应用

本文介绍了工业以太网技术在沂沭泗河洪水东调南下续建工程刘家道口枢纽李庄闸防倒漾闸计算机监控系统中的应用,叙述了工业以太网技术的优点,并指出工业以太网技术是整个水闸自动化项目发展的必然选择.     

以太网技术在宽带接入网中的应用

以太网技术在中国石油化工集团公司安庆石油化工总厂、中国石油化工股份有限公司安庆分公司(以下合称安庆石化)计算机网络系统中的应用已有较长的时间。早在上个世纪90年代初期，安庆石化就开始建设基于以太网技术的企业计算机网络系统，对以太网技术的应用已有广泛的网络基础和长期的运行经验。在建设安庆石化宽带接入网时，以太网技术又作为宽带接入网的骨干接入技术。     

风力发电机组多通道振动数据采集系统

针对大型风力发电机组运行状态监测对传动主轴、轴承以及齿轮箱等的多路振动信号采集要求,设计基于以太网的多通道振动数据采集系统。系统采用AT91SAM9G20嵌入式主板实现以太网接口,并通过PC104总线接口连接多个同步振动数据采集模块,实现采集通道的柔性扩展。振动数据采集模块实现了ICP振动传感器的信号调理以及抗混叠滤波器,并由FPGA控制AD7656实现了6通道16位振动数据同步采集。通过实验验证,系统实现了高速的多通道数据采集。     

基于以太网的水电站闸门自动控制系统

本文首先分析了以太网的应用技术,然后结合PLC的运用,给出了某水电站监控与自动控制综合系统的构成。重点分析了系统的架构,以及PLC程序的设计,然后给出了系统的测试。该开发可以对同类开发起到良好的借鉴作用。     

基于Vx Works系统的多网口驱动程序设计

介绍了基于Vx Works系统的多个快速以太网PCI控制器驱动的编程方法,给出了硬件框图和程序流程图,并说明了该驱动与上层程序的接口。     

基于无线以太网的原料和堆取料设备联锁系统

针对莱钢新二区原料设备和堆取料设备联锁系统信号不稳定的问题,采用基于无线以太网传输方式改造设备联锁系统,确保信号稳定传输。     

S7-300以太网PLC时钟同步设置和校正

阐述SCADA系统中PLC时钟控制的误差及S7-300以太网与PLC间时钟同步的设置和校正。     

网络常青树

不经意间,以太网已经30岁了。到目前为止,在局域网上最主要的数据传输方式依然是以太网。 1973年5月,当施乐公司的帕洛阿尔托研究中心(PARC)的研究员Bob Metcalfe把以太网设计出来时,其设计意图只是要完成每秒3M字节的数据传输。而今天,每秒1G字节的以太网已十分常见,每秒100G字节的以太网也正在开发之中。由于以太网无处不在,互联网上绝大多数的数据流量始于之,亦终于之。     

城市轨道交通车辆无线传输装置设计研究

城市轨道交通车辆无线传输装置是列车控制及监控系统的重要组成部分,通过研究无线传输装置系统架构、数据传输内容和功能模块,分析TCMS系统MVB总线数据及各子系统以太网数据,给出单台设备数据传输整体带宽需求建议。     

基于以太网接口的电源变换器的设计

以太网是现有局域网中最通用的通信协议标准,而以太网电源是以太网的基础设备。本文设计了一种基于以太网接口的15W DC/DC电源变换器模块电路。该电源由以太网接口电路和高效率DC/DC电源变换器2部分组成,模块中包含PoE识别信号阻抗、“0”类类型电路,采用MOSFET开关时,电源变换器的效率高达88％,PoE接口的效率可达97%以上。     

基于神经网络的无刷直流电机故障诊断和容错控制方法的研究

提出并设计了一种针对无刷直流电机控制器的故障诊断和容错控制方法。该神经网络状态观测器由实际非线性控制系统进行训练,根据实际系统和神经网络观测器输出残差,容错控制系统能够被确定下来。针对系统控制器、电流和速度传感器的故障条件进行了仿真分析,容错控制通过使用补偿控制器实现,保证系统故障条件下的稳定性和性能。结果表明,所提出的方法能有效地定位错误故障和时间,消除干扰并提高系统的鲁棒性。     

棒材生产线冷床下卸钢系统的应用

针对棒材生产线上冷床下卸钢系统机械效率低、运行周期长,不能适应快节奏生产的现状,采用以工业以太网为主、DP网为辅的网络通讯,应用西门子FM350-2高速计数器,通过有效的数学计算模型,结合变频器和液压传动控制技术,实现网络自动化控制。     

负荷控制系统总体设计

电力负控系统主要采用辐射的分散用户集中管理方式,由前置机、操作机和用电信息分析处理三个分系统组成。网络结构采用标准以太网形式,内部以星形方式连接,使整个网络结构稳定,便于扩充,并且功能划分清楚,便于使用和操作。     

ICT for sustainable development: Global comparative evidence of globalisation thresholds

The objectives of this paper are to investigate the effect of ICT on sustainable development and the mechanisms through which the effect is modulated. The focus is on a sample of 140 countries around the globe for the period 2000–2019. The methodology involves the: (i) Fixed Effects estimator to control for individual heterogeneity, (ii) Driscoll and Kraay estimator to control for cross-section dependence between panels, (iii) the Mean Group estimator to take into account the averages between panel groups, (iv) the system GMM to correct for unobserved heterogeneity and simultaneity bias and (v) the instrumental variable Fixed Effects Tobit to take in to account the limited range in our dependent variable. The results show that ICT has a positive and significant effect on sustainable development. Whereas overall net effects are positive, the findings are contingent on the choice of the ICT measurement, the geographical location of the economy and the income group category. The study recommends policy makers to take into account ICT and the advantages it offers in the elaboration of measures for the sustainable development agenda.     

Generalizing the OLS and Grid Estimators

The vast majority of market valuations employ either some formal estimator such as ordinary least squares (OLS) or rely upon an informal set of rules defining the grid adjustment estimator. The success of the grid adjustment estimator suggests the data do not obey the ideal assumptions underlying OLS. However, the grid adjustment estimator's lack of a formal statistical foundation makes it difficult to use for inference and other purposes. This article demonstrates how to generalize the grid estimator and OLS to potentially obtain the best features of both. Interestingly, the generalization defines a spatial autoregression. On an empirical example the spatial autoregression outperforms the grid estimator which in turn outperforms OLS.     

Repeat Sales as a Matching Estimator

The most common approaches for constructing house price indices—hedonic price functions and the repeat sales estimator—focus on changes over time in mean prices. Though the hedonic approach is less wasteful of data than the repeat sales estimator, it relies on an accurate specification of the underlying econometric model. I suggest using a matching estimator as an alternative to the hedonic and repeat sales approaches. Like the repeat sales approach, a matching estimator uses pairs of sales from different dates to estimate the mean difference in sales prices over time. The matching approach preserves much larger sample sizes than the repeat sales estimator while requiring less preimposed structure than the hedonic approach. The matching approach makes it easy to characterize changes in the full distribution of house prices.     

Comparing the Accuracy of the Minimum-Variance Grid Method to Multiple Regression in Appraised Value Estimates

The adjustment-grid method and the multiple-regression method are the two most frequently used techniques in the sales comparison approach. This paper demonstrates that although both techniques provide unbiased estimators, the minimum-variance grid estimator should result in a smaller standard deviation than the multiple-regression estimator. A technique is also derived to estimate the confidence interval or to perform hypothesis tests for the minimum-variance grid estimator.     

Orchestrating resources for FMA in coopetitive NPD

The rapid introduction of new products in high‐tech industries is a key competence for firms wanting to benefit from the first‐mover advantage (FMA). Prior studies call for forging links between FMA and the resource‐based view, as the resources at the disposal of a firm tend to influence the likelihood and timing of market entry. Analysing the way firms orchestrate internal and external resources enables a better understanding of this link. More precisely, synchronising the combination of internal and external resources is important in determining the development time of new products. This issue becomes vital when the NPD process regroups competitors due to the short age of the acquired knowledge. An in‐depth case study of the product development strategies of four competitors that collaborated to develop Ethernet solutions identifies three different product introduction strategies based on different resource orchestrations and timing: pioneer, wise and slow. The firms that structured their resources early to make them available for bundling during coopetition were able to introduce products faster than firms that structured their resources during coopetition. Furthermore, our results show that only prepared firms are able to reap benefits from knowledge gained through coopetitive NPD.     

梯度法对输出颜色渐变平滑度的量化

为了使用客观测量值对颜色渐变中平滑程度的感知进行量化,本文建立了一个计算硬拷贝中颜色渐变平滑度的模型。这种基于梯度的方法可以由95%阶调跳跃评价值二阶导数和5%阶调失真评价值一阶导数共同决定。从心理物理学角度分析了模型的性能和早期提出的方法,而且对其预测精准性进行了相互比较。模型对于相应的视觉数据表现出了较强的皮尔森相关性,皮尔森相关系数值达到了0.87。通过方差分析验证模型的显著性。将记忆色的变化（蓝天、绿草和白种人肤色）制作成渐变梯级当做测试样品。