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21.
舰船批量建造费用的组合预测应用研究 总被引:1,自引:0,他引:1
研究了舰船批量建造费用的组合预测问题.首先依据舰船批量建造费用的变化特点,采用生长曲线法、数据平滑法、灰色分析法对费用进行预测,然后运用支持向量机的回归算法对3种预测方法的预测值进行有机组合,建立了舰船批量建造费用的组合预测模型,最后利用样本数据分析了一个参数变化对预测性能的影响,给出了支持向量机参数选择的依据.仿真结果表明,该模型能明显提高系统预测的精度和稳定性,可用于舰船批量建造费用的预测和估算,具有较大的实用价值. 相似文献
22.
以北京地铁奥运支线起点(熊猫环岛站)区间隧道下穿健安桥的设计与施工为背景,分析浅埋暗挖隧道穿越地面结构物施工如何有效地控制沉降,探讨施工时应注意的关键环节和采取的措施,以此作为今后类似工程施工的依据和借鉴. 相似文献
23.
路基沉降预测及其工程应用 总被引:2,自引:0,他引:2
根据某公路软土路段的实测沉降资料,采用双曲线法预测各施工阶段测点的沉降和工后沉降量,为路面结构层的铺设及间歇期的确定提供了依据。 相似文献
24.
This paper systematically reviews studies that forecast short-term traffic conditions using spatial dependence between links. We extract and synthesise 130 research papers, considering two perspectives: (1) methodological framework and (2) methods for capturing spatial information. Spatial information boosts the accuracy of prediction, particularly in congested traffic regimes and for longer horizons. Machine learning methods, which have attracted more attention in recent years, outperform the naïve statistical methods such as historical average and exponential smoothing. However, there is no guarantee of superiority when machine learning methods are compared with advanced statistical methods such as spatiotemporal autoregressive integrated moving average. As for the spatial dependency detection, a large gulf exists between the realistic spatial dependence of traffic links on a real network and the studied networks as follows: (1) studies capture spatial dependency of either adjacent or distant upstream and downstream links with the study link, (2) the spatially relevant links are selected either by prejudgment or by correlation-coefficient analysis, and (3) studies develop forecasting methods in a corridor test sample, where all links are connected sequentially together, assume a similarity between the behaviour of both parallel and adjacent links, and overlook the competitive nature of traffic links. 相似文献
25.
ABSTRACTThis paper describes the development of railway station choice models suitable for defining probabilistic station catchments. These catchments can then be incorporated into the aggregate demand models typically used to forecast demand for new rail stations. Revealed preference passenger survey data obtained from the Welsh and Scottish Governments was used for model calibration. Techniques were developed to identify trip origins and destinations from incomplete address information and to automatically validate reported trips. A bespoke trip planner was used to derive mode-specific station access variables and train leg measures. The results from a number of multinomial logit and random parameter (mixed) logit models are presented and their predictive performance assessed. The models were found to have substantially superior predictive accuracy compared to the base model (which assumes the nearest station has a probability of one), indicating that their incorporation into passenger demand forecasting methods has the potential to significantly improve model predictive performance. 相似文献
26.
For existing advanced geological forecasting, the forecast distance is short and the test frequency is high, increasing test and construction risks. Since various methods have different requirements for the test environ-ment, preparation work can be tedious and result in a long construction time thereby affecting normal construction.A new advanced geological forecast technique based on multi-source seismic interferometry for tunnels is proposed.This technique uses the blast at one end of tunnel as a centrum and receives the signal at the other end of the tun-nel, therefore allowing advanced geological forecasting of the unexcavated tunnel part by relative processing and im-aging. A numerical simulation of this kind of geological forecasting using the finite difference method to simulate two kinds of unfavorable geological bodies (karst and a fault) predicted them accurately and verified the effective-ness and accuracy of this geological forecasting method. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved. 相似文献
27.
Within the literature concerned with aspects of competitiveness, innovation and strategic management of industrial clusters, the body regarding forecasting of strategic management is still nascent. This work aspires to render a contribution within the domain of strategic management forecasting, through the indicative case of European maritime clusters. For this end, a two-tier model is formulated. A quantitative strengths, weaknesses, opportunities, and threats (SWOT) methodology that derives from the fusion of a quondam situation analysis and crosstabs’ theory is generated. This leads to the utilization of the crosstab’s conditional probabilities as transition probabilities; the latter are called to compile the transition matrix of a Markov chain. Through this methodology, and the successive Markov chain’s transition matrices, strategic forecasts are extracted for a devised European maritime cluster case. This work relinquishes a novel application with respect to strategic management forecasting, that provides a dichotomy of practical interpretations and scenarios for quantitative situation analysis. Thus, it may enable effective real-time decision-making for strategic management and/or policy drafting. The situation analysis forecasting model may find applicability in a plethora of practical and theoretical cases, wherein forecasting may be desirable. It may as well pertain to an intrinsic methodology for situation analysis forecasting of maritime clusters. 相似文献
28.
Dongjoo Park Laurence R. Rilett Byron J. Gajewski Clifford H. Spiegelman Changho Choi 《Transportation》2009,36(1):77-95
With the recent increase in the deployment of ITS technologies in urban areas throughout the world, traffic management centers
have the ability to obtain and archive large amounts of data on the traffic system. These data can be used to estimate current
conditions and predict future conditions on the roadway network. A general solution methodology for identifying the optimal
aggregation interval sizes for four scenarios is proposed in this article: (1) link travel time estimation, (2) corridor/route
travel time estimation, (3) link travel time forecasting, and (4) corridor/route travel time forecasting. The methodology
explicitly considers traffic dynamics and frequency of observations. A formulation based on mean square error (MSE) is developed
for each of the scenarios and interpreted from a traffic flow perspective. The methodology for estimating the optimal aggregation
size is based on (1) the tradeoff between the estimated mean square error of prediction and the variance of the predictor,
(2) the differences between estimation and forecasting, and (3) the direct consideration of the correlation between link travel
time for corridor/route estimation and forecasting. The proposed methods are demonstrated using travel time data from Houston,
Texas, that were collected as part of the automatic vehicle identification (AVI) system of the Houston Transtar system. It
was found that the optimal aggregation size is a function of the application and traffic condition.
相似文献
Changho ChoiEmail: |
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