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随着汽车电子化程度越来越高,车速信号应用的范围也越来越广泛。通过特定的传感器产生与汽车车轮的转数成正比的脉冲信号,在汽车内部ECU中,通过一定的公式计算采集到的脉冲数,来反算出车速。车速信号被广泛的应用于导航系统、车道偏离系统、自适应巡航系统中,汽车车速的准确与否直接关系到汽车安全及可靠性。 相似文献
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Traffic is the largest contributor (37%) to urban air pollution in India. During commuting, passengers are significantly exposed to pollutants. We carried out a study on a National Highway (NH) in India to measure personal exposure to Particulate Matter (PM) in five travel modes. PM2.5 concentrations showed the following trend: Bus > Car FA (fresh air mode of air condition) > Bus AC > Car > Car RC (re-circulation mode of air condition). Highest and lowest concentrations of PM10 were observed in Bus (134 ± 47 µg m−3) and Car RC (20 ± 5 µg m−3), respectively. The exposures were highest at the rear seats during the Bus AC journeys. In Car FA, the contribution of PM1 to total concentrations was dominant (61%). Travel modes explained highest variabilities in PM10, PM2.5 and PM1 concentrations. In all travel modes, the highest particle counts were observed for PM0.3–0.5. PM>0.5–5.0 counts during Bus journeys were comparatively higher than remaining modes. Deposition doses of passengers were as high as 3.22 µg of PM10 (in Bus), 0.66 µg of PM2.5 (in Bus) and 0.06 µg of PM1 (in Bus AC) during the ~1 h journey. Our study revealed that Car RC is the safest mode of travel, both in terms of personal exposures and PM depositions in respiratory system. The results from this study can be used to target efforts to reduce personal exposure of highway commuters. 相似文献
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罗依梦;许庆阳;段贺辉;徐永波;王泽宇 《铁道通信信号》2024,60(2):32-39
在铁路信号系统动态检测数据中,地面轨道电路的补偿电容脉冲检测信号和轨道电路感应电压数据均可反映补偿电容的工作状态。针对单一来源数据进行补偿电容故障判别误报率高的问题,提出一种基于D-S证据融合理论的补偿电容故障判决方法。首先,针对补偿电容脉冲检测信号和轨道电路感应电压数据,提取出有效代表补偿电容状态的特征值,并基于该特征值进行正常/故障概率分配;其次,利用D-S证据融合理论,对单一判定结果进行融合,得到每个补偿电容的故障概率,从而实现补偿电容故障识别;最后,基于实际检测数据对所提方法进行验证。试验结果表明：相较于基于补偿电容脉冲或感应电压的单一来源数据故障识别方法,基于D-S证据融合理论的补偿电容识别准确率分别提升13%和5%,有效地提高了补偿电容故障识别准确率。 相似文献
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分析了空间电压矢量脉宽调制（SVPWM）逆变器死区效应产生的原因及影响,根据死区效应及SVPWM的特点提出了电压补偿法。该方法无需增加硬件,实用性较强。仿真和实验结果验证了该方法的有效性。 相似文献
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Abstract Estimation of the origin–destination (O–D) trip demand matrix plays a key role in travel analysis and transportation planning and operations. Many researchers have developed different O–D matrix estimation methods using traffic counts, which allow simple data collection as opposed to the costly traditional direct estimation methods based on home and roadside interviews. In this paper, we present a new fuzzy model to estimate the O–D matrix from traffic counts. Since link data only represent a snapshot situation, resulting in inconsistency of data and poor quality of the estimated O–Ds, the proposed method considers the link data as a fuzzy number that varies within a certain bandwidth. Shafahi and Ramezani's fuzzy assignment method is improved upon and used to assign the estimated O–D matrix, which causes the assigned volumes to be fuzzy numbers similar to what is proposed for observed link counts. The shortest path algorithm of the proposed method is similar to the Floyd–Warshall algorithm, and we call it the Fuzzy Floyd–Warshall Algorithm. A new fuzzy comparing index is proposed by improving the fuzzy comparison method developed by Dubois and Prade to estimate and compare the distance between the assigned and observed link volumes. The O–D estimation model is formulated as a convex minimization problem based on the proposed fuzzy index to minimize the fuzzy distance between the observed and assigned link volumes. A gradient-based method is used to solve the problem. To ensure the original O–D matrix does not change more than necessary during the iterations, a fuzzy rule-based approach is proposed to control the matrix changes. 相似文献
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The purpose of this paper is to investigate the net incidence of government subsidies to a transit system (i.e., the net impact of who pays and who benefits from transit subsidies). Rather than considering the U.S. transit subsidy program in the aggregate, the net incidence of subsidies to a particular transit system — Tidewater Regional Transit (TRT) — is analyzed. The paper concludes that the net incidence of the TRT subsidy program is progressive. Furthermore, the paper provides a methodology that can be used for investigating the net incidence of government subsidies to other transit systems. 相似文献
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Hurricanes harm people and damage property through extreme wind speeds and flooding associated with heavy rains and storm surge. One of the most effective and widely used tactics to protect people from hurricanes is evacuation. Improved knowledge of the behavior of communities before, during and after an evacuation can better support emergency planning and operations, and thus help make evacuations safer and more efficient. The objective of this work is to identify ways to use traffic data to better understand evacuation behavior and to explore ways to integrate traffic data into evacuation planning and response. Traffic data collected in Delaware before, during and after Hurricane Irene in August 2011 using automated traffic recorders are assembled and analyzed. The analysis shows that a significant number of residents and visitors evacuated from the beach communities and the evacuation patterns are very similar to the traffic patterns experienced on summer weekends. These insights suggest that this type of analysis may also be of value for other events in other communities. 相似文献
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地基土标准贯入锤击数与物理力学参数关系探讨 总被引：1，自引：0，他引：1
根据徐州地区大量的粘性土标准贯入试验及土工试验资料,基于数理统计理论,采用回归分析方法研究了标贯击数与物理力学指标间的相关关系,拟合了相应的回归方程。结果表明,粘性土物理力学参数与标贯击数具有高度线性关系,利用标贯击数确定粘性土物理力学参数具有较高的可靠性。研究成果可为建立地区经验公式提供基础性资料。 相似文献
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水运工程地基海相沉积的软黏土地层较多,软黏土十字板强度指标是进行地基和边坡稳定验算的重要指标,但在海上进行十字板试验受风浪、潮汐影响,实施较为困难,试验数据的相关性研究较少。结合多个港口软黏土十字板测试成果数据,分析了十字板强度与有效自重应力及标贯击数的相关性,并建立了相关公式,对软黏土十字板强度指标的获取和应用具有实用和借鉴意义。 相似文献