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在介绍Rogowski线圈光电式电流互感器基本原理的基础上,设计了一种基于电N/N率(V/F),频率/电压(F/V)转换原理的光纤隔离变换器,实现了互感器高压端与低压端的电气隔离。论述了电路的结构、工作原理、硬件设计等,并通过实验进一步阐明光纤隔离变换器的工作原理。现场实验表明,该光线隔离变换器具有良好的线性度,传输精度高,工作稳定。 相似文献
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Examination of factors affecting freeway incident clearance times: a comparison of the generalized F model and several alternative nested models
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Traffic incidents are a principal cause of congestion on urban freeways, reducing capacity and creating risks for both involved motorists and incident response personnel. As incident durations increase, the risk of secondary incidents or crashes also becomes problematic. In response to these issues, many road agencies in metropolitan areas have initiated incident management programs aimed at detecting, responding to, and clearing incidents to restore freeways to full capacity as quickly and safely as possible. This study examined those factors that impact the time required by the Michigan Department of Transportation Freeway Courtesy Patrol to clear incidents that occurred on the southeastern Michigan freeway network. These models were developed using traffic flow data, roadway geometry information, and an extensive incident inventory database. A series of parametric hazard duration models were developed, each assuming a different underlying probability distribution for the hazard function. Although each modeling framework provided results that were similar in terms of the direction of factor effects, there was significant variability in terms of the estimated magnitude of these impacts. The generalized F distribution was shown to provide the best fit to the incident clearance time data, and the use of poorer fitting distributions was shown to result in severe over‐estimation or under‐estimation of factor effects. Those factors that were found to impact incident clearance times included the time of day and month when the incident occurred, the geometric and traffic characteristics of the freeway segment, and the characteristics of each incident. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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华夏 《青岛远洋船员学院学报》2005,26(4):45-49
本文介绍了以VC++6.0为技术平台实现F77船站手柄话机模拟京统的构想、软件的设计思路、编程技术分析和程序流程图。 相似文献
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相似关系设计是模型试验的关键环节。以沪杭客专32 m跨度的简支箱梁为原型,探讨了适合于徐变试验的模型的设计方法,建立了模型和原型的相似关系,设计了简单相似模型梁结构,推导出模型梁与原型梁的弹性上拱和徐变上拱的相似关系。通过对比分析原型梁的弹性上拱推算值、徐变上拱推算值与实测值,验证了相似模型的合理性。 相似文献