排序方式: 共有50条查询结果,搜索用时 15 毫秒
41.
Wave-induced vertical bending moment (VBM) and horizontal bending moment (HBM) on a large-scale segmented model with a box-type backbone beam in short-crested irregular seas are systematically analyzed using sea trial measurement data. New insights into the relationship between nonlinear VBM and HBM of the ship sailing in short-crested sea waves are explored and presented. The results indicate that the HBM significantly contributes to the total sectional loads when the ship is sailing in a seaway and the HBM has a strong correlation with VBM in both magnitude and tendency. Therefore, design loads of HBM and the corresponding lateral structural strength issues should also be concerned in addition to VBM at the ship design phase. 相似文献
42.
Congestion pricing is one of the widely contemplated methods to manage traffic congestion. The purpose of congestion pricing is to manage traffic demand generation and supply allocation by charging fees (i.e., tolling) for the use of certain roads in order to distribute traffic demand more evenly over time and space. This study presents a framework for large-scale variable congestion pricing policy determination and evaluation. The proposed framework integrates departure time choice and route choice models within a regional dynamic traffic assignment (DTA) simulation environment. The framework addresses the impact of tolling on: (1) road traffic congestion (supply side), and (2) travelers’ choice dimensions including departure time and route choices (demand side). The framework is applied to a simulation-based case study of tolling a major freeway in Toronto while capturing the regional effects across the Greater Toronto Area (GTA). The models are developed and calibrated using regional household travel survey data that reflect the heterogeneity of travelers’ attributes. The DTA model is calibrated using actual traffic counts from the Ontario Ministry of Transportation and the City of Toronto. The case study examined two tolling scenarios: flat and variable tolling. The results indicate that: (1) more benefits are attained from variable pricing, that mirrors temporal congestion patterns, due to departure time rescheduling as opposed to predominantly re-routing only in the case of flat tolling, (2) widespread spatial and temporal re-distributions of traffic demand are observed across the regional network in response to tolling a significant, yet relatively short, expressway serving Downtown Toronto, and (3) flat tolling causes major and counterproductive rerouting patterns during peak hours, which was observed to block access to the tolled facility itself. 相似文献
43.
44.
施工单位参加工程施工招投标是承揽施工任务的主要途径,投标报价是否合理不仅是能否中标的关键,也是能否盈利的重要因素,同时投标报价的调整更是招投标过程中的重要环节。此文以市政工程工程量清单计价模式为例,阐述工程投标报价的组成,并就如何对分部分项工程单价、措施项目费、其他项目费、规费等进行调整做进一步论述,以期中标和获得可观的经济效益。 相似文献
45.
采用长距离水平冻结暗挖法的浅埋大断面地铁隧道施工技术 总被引:2,自引:0,他引:2
通过人工冻土试验、有限元数值分析和大型物理模型试验,研究浅埋大断面地铁隧道采用长距离水平冻结暗挖法的施工技术。通过现场土的人工冻土试验,得到土体冻结的物理力学指标。有限元数值分析结果表明,随着冻结壁厚度的增加,冻结壁的强度和稳定性增加。大型物理模型试验结果表明,冻胀和融沉量都随着冻结壁厚度的增加而明显增大;当冻结壁厚度为4.5 m时,预测实际工程地表冻胀和融沉量均已超过允许值。根据上述研究结果,进行了冻结施工方案的设计和优化。在施工过程中,改进超长距离水平冻结管连接方式,采用跟管钻进新技术,确保了冻结孔的成孔质量;采取设置卸压孔、加大盐水流量和融沉跟踪注浆等技术措施,有效地控制了地面的冻胀和融沉,确保了工程顺利地完成。 相似文献
46.
A new algorithm based on rough core was proposed to extract all relative-attribute reducts in decision information systems of large-scale records. In the algorithm, the rough core of the decision-making information system is first calculated. Then, an approach based on a top-down strategy is adopted to select the non-core condition attributes and generate candidate relative-attribute reducts. Finally, the set of all relative-attribute reducts is obtained by pruning the candidate relative-attribute reducts. Experimental results show that the proposed algorithm is superior to the other methods such as the algorithm without computing core, the exhaustive method and the discernibility matrix method in extracting all relative-attribute reducts for large-scale data sets. 相似文献
47.
张云军 《南通航运职业技术学院学报》2013,12(2):59-64
文章利用MSC.Nastran软件对A级航区航标船两种不同工况下进行有限元分析。文中给出了边界条件施加方法和载荷计算方法。在甲板结构不满足强度要求的情况下,对甲板结构提出三种加强方案进行计算,结果显示船体主要构件强度满足规范要求,再对该船甲板结构的三种加强方案进行模糊综合评判,确定出最优方案,可为航标船的设计提供宝贵的经验。 相似文献
48.
49.
50.
This paper presents a framework for addressing uncertainty and risk for large-scale transportation investments involving public–private participation. Demand, fare/toll and demand responsive costs are considered in the uncertainty analysis. Uncertainty analysis provides information on economic feasibility of the project. A set of relaxation policies is proposed to form various Ownership, Tenure and Governance (OTG) strategies reflecting the nature and level of participation by the public and private entity. A Monte Carlo Simulation-based Value at Risk is used to quantify risk. Finally, a methodology is proposed to integrate uncertainty and risk. The framework is tested on the proposed multibillion dollar Detroit River International Crossing connecting the cities of Detroit in the USA with Windsor in Canada. The analysis provides insights to probable outcomes for this transportation infrastructure investment under different OTG scenarios. 相似文献