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根据天津港货物吞吐量的历史数据,分别建立有关该港吞吐量的回归预测模型、Logistic生长曲线模型以及组合模型。通过比较3种模型的平均相对误差,可以证明组合模型的平均相对误差最小。运用组合模型预测港口吞吐量可以降低误差,提高预测精度。 相似文献
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基于信息化联合作战需求,阐述了传统的指挥控制与火力控制信息交互方式面临的挑战,分析了信息化联合作战对指挥控制与火力控制一体化的军事需求,对指挥控制与火力控制一体化的特点、功能和系统设计方法及原则进行了阐述,并以具体示例加以说明。 相似文献
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Accurate and timely traffic forecasting is crucial to effective management of intelligent transportation systems (ITS). To predict travel time index (TTI) data, we select six baseline individual predictors as basic combination components. Applying the one‐step‐ahead out‐of‐sample forecasts, the paper proposes several linear combined forecasting techniques. States of traffic situations are classified into peak and non‐peak periods. Based on detailed data analyses, some practical guidance and comments are given in what situation a combined model is better than an individual model or other types of combined models. Indicating which model is more appropriate in each state, persuasive comparisons demonstrate that the combined procedures can significantly reduce forecast error rates. It reveals that the approaches are practically promising in the field. To the best of our knowledge, it is the first time to systematically investigate these approaches in peak and non‐peak traffic forecasts. The studies can provide a reference for optimal forecasting model selection in each period. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
977.
The maximum approximate composite marginal likelihood (MACML) estimation of multinomial probit-based unordered response choice models 总被引:1,自引:0,他引:1
Chandra R. Bhat 《Transportation Research Part B: Methodological》2011,45(7):923-939
The likelihood functions of multinomial probit (MNP)-based choice models entail the evaluation of analytically-intractable integrals. As a result, such models are usually estimated using maximum simulated likelihood (MSL) techniques. Unfortunately, for many practical situations, the computational cost to ensure good asymptotic MSL estimator properties can be prohibitive and practically infeasible as the number of dimensions of integration rises. In this paper, we introduce a maximum approximate composite marginal likelihood (MACML) estimation approach for MNP models that can be applied using simple optimization software for likelihood estimation. It also represents a conceptually and pedagogically simpler procedure relative to simulation techniques, and has the advantage of substantial computational time efficiency relative to the MSL approach. The paper provides a “blueprint” for the MACML estimation for a wide variety of MNP models. 相似文献
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Ángel IbeasRuben Cordera Luigi dell’Olio Jose Luis Moura 《Transportation Research Part A: Policy and Practice》2011,45(6):485-498
Multiple linear regression (MLR) and geographically weighted regression (GWR) models are used for estimating parking demand in areas with paid short stay parking systems. These models have been applied to the city of Santander (Cantabria, Spain) to check their goodness of fit and their predictive ability. The results show the main advantages and disadvantages of using GWR models. The technique proved to be useful in this case study because it offered a better fit and made better predictions in a scenario showing a certain degree of spatial heterogeneity unexplained by any of the variables introduced into the global model. However, the GWR model also presented situations of local correlation although this was considered moderate given the results provided by the variance inflation factors and the local condition indexes. 相似文献
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María Castro Luis Iglesias José A. Sánchez Luis Ambrosio 《Transportation Research Part C: Emerging Technologies》2011,19(6):997-1005
Analyzing the distance visible to a driver on the highway is important for traffic safety, especially in maneuvers such as emergency stops, when passing another vehicle or when vehicles cross at intersections. This analysis is necessary not only in the design phase of highways, but also when they are in service. For its use in this last phase, a procedure supported by a Geographic Information System (GIS) has been implemented that determines the highway distances visible to the driver. The use of a GIS allows the sight distance analysis to be integrated with other analyses related to traffic safety, such as crash and design consistency analyses. In this way, more complete analyses could be made and costs shared. Additionally, with the procedure proposed it is possible to use data regarding the trajectory of a vehicle obtained on a highway with a Global Positioning System (GPS) device. This application is very useful when highway design data are not available. The procedure developed and its application in a case study are presented in this article. 相似文献
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