Sediment geochemistry and mineralogy in Milos bay, SW Kyklades, Aegean Sea, Greece

This work aims at studying the geochemistry and mineralogy of Milos bay surface sediments. The bay forms an enclosed marine area, supplied totally by volcanic formations. Totally 16 samples were subjected to sedimentological (grain size), mineralogical (microscope examination and X-ray diffraction of the bulk sample and the pelitic fraction), and geochemical analyses (X-ray fluorescence in the pelitic fraction). Also the carbonate content was determined. Sediments were sandy with a high carbonate content (14–58%). The dominant minerals recognized in the pelitic fraction were smectite, kaolinite and illite, followed by chlorite, quartz, calcite, Mg-calcite and feldspars. In general, element concentrations appeared to be within the normal range, except Pb and Zn, which exhibited relatively high values. The Index of Geoaccumulation I_geo was computed, in order to investigate a possible enrichment of the surface sediments in metals. The analysis revealed again high values of I_geo class for both Pb and Zn. A careful study of the area, in relation to the quality of the catchment basins petrology, lead to a non-anthropogenic origin of these high concentrations. The enrichment of the surface sediments in Pb and Zn is attributed to the weathering of several mineral deposits, pyroclastic rocks and lavas, covering almost all Milos vicinity. A study of the geochemical data correlation coefficient matrix revealed three major groups of elements: (i) the elements of detrital origin represented by Si, Al, K and a part of the metals; (ii) the carbonates group; and (iii) a Fe–Mn oxyhydroxides–oxides group, which attracts a part of Pb, Cr and Ni.     

重庆朝天门长江大桥施工控制压重方案设计

朝天门长江大桥全长932 m,主桥为(190+552+190)m三跨连续单拱钢桁梁。结合主跨合龙特点介绍主跨合龙的思路、计算及操作要点,应用大型有限元分析程序MIDAS建立了朝天门长江大桥的三维有限元简化计算模型,并对其进行了施工过程控制分析。压重方案设计可以为同类桥梁的施工控制分析提供有益的思路。     

连锁经营是汽车维修业的发展方向

在我国汽车维修行业发展连锁经营是整个行业生存的必由之路。在介绍了国外的汽车维修连锁企业的基础上,论述了发展连锁经营的必要性和紧迫性,并对我国汽车维修连锁企业的发展提出了一些合理化建议。     

Modeling Feedback Scheme of Empty Cars in Unloading End of Heavy Haul Railway

The transportation organization of heavy haul railway is complex in China, especially, the feedback of empty cars. On the basis of reference to the existing research results, and deep analysis of the characteristics of empty cars distribution of heavy haul railway, the authors construct the feedback schematic model of empty cars in unloading end of heavy haul railway. The minimum quantity of the combined trains and the time for combination is taken as the model goal and solution algorithm on the basis of minimum cost and maximum flow is formulated. Daqin railway is taken as an example and relevant conclusions of feedback scheme of empty cars of heavy haul railway, through an analysis of calculation results, are drawn.     

Travel Behavior Analysis of the Females in Beijing

In urban life, compared with the same age group of male contrast, the statistical indicators of female travel behavior show significant differences. According to the sample data of Beijing 2005 travel survey, the paper analyzes the female travel behavior in the travel rate, travel consumption, trip purpose, and travel mode. Furthermore, the paper introduces the concept of the trip chain, to construct a female morning commuter trip chain choice behavior model with noncollection theories and methods, to analyze 10 factors that influence a female individual's choice of a trip chain from the source. Subsequently, model parameters are estimated, to calculate the incidents that can help to quantitatively understand the impact of each factor on a female's choice of the trip chain. The results show that the travel rate of elderly women is far lower than that of elderly men. Female travel proportion in shopping and social activities is obviously higher than that of male travelers, and factors related to the structure of families create important constraints in their average travel time consumption. The main travel mode of the female is walking, which is far more than that of a male. Age, whether they hold licenses, monthly income, and transport ownership are dominant factors for the female's choice of the trip chain.     

面向供应链的虚拟企业利润分配机制研究

随着专业分工和信息技术的发展,产业组织结构对企业效益和成本有极大的影响。揭示了虚拟企业的组织结构模型及其企业行为特征,建立了虚拟企业的供给模型,提出了虚拟企业联盟的两种利益分配机制,分析了这两种分配机制的合理性,为虚拟企业的实现创造了条件。     

Bolster spring fault detection strategy for heavy haul wagons

An on-board health monitoring system is proposed for heavy haul wagons in this paper including a signal-based fault detection and isolation (FDI) method and an on-line fault diagnose strategy. Such a system, to be feasible on freight wagons, must be sufficiently cheap and robust, hence the design assumes the constraint of using only two accelerometers mounted on the front left and right rear part of each carbody in a heavy haul train. This paper focuses on the detection of bolster spring fault conditions. The problem is made more complex by the modes of failure which might be expected in bolster spring nests. Types of spring failure are firstly identified and discussed covering situations of broken (shortening springs) and softening (individual spring loss from a nest or cross-section loss through corrosion). The effects of these faults and their detectability were investigated using simulations on straight and curved track and using a fully detailed model of a typical 40?t axle-load heavy haul wagon. The simulation results were then examined and compared using cross-correlation analysis and an FDI system was proposed. The FDI system introduced five possible fault indicators. Initial results indicated that it was possible to detect changes in bolster stiffness of ±25%. An on-line fault diagnoses strategy is proposed for bolster spring faults which only requires data from wagon monitoring during travel around sharp curves to detect and the occurrence of confirm faults. The functionality envisaged needs only a ‘once per trip’ monitoring site, such as a sharper curve, and is aimed at condition monitoring rather than the provision of alarms or comprehensive monitoring of all events.     

基于Shapley值法的港口冷链物流投资分析方法

从客户的角度出发,旨在建立一套与投资额度、客户满意程度相关联的港口冷链物流投资分析方法,为决策者在财务分析之外提供另一个分析视角。将港口冷链物流划分为冷藏存储、冷藏加工、冷藏运输、客户服务4个环节。首先利用层次分析法确定各个环节在整条供应链的权重,然后引入效用理论确定各个环节投资产生的效用,通过Shapley值法实现了各个环节在整条供应链权重和各个环节投资效用的有机结合,使得发展瓶颈随投资的变动而改变,从而更加符合实际情况。通过实例分析,此方法能够充分考虑投资效用的影响,也能够减少专家打分等定性方法产生的主观偏差。     

基于博弈论的供应链金融监管合同奖惩研究

将银行和物流监管公司签订的监管合同中的奖惩条款为研究对象,基于博弈论探讨了监管方和借款方的博弈行为,找到了纯粹决策和混合决策的纳什均衡。通过算例,对比计算了有无奖励和惩罚时,混合决策的纳什均衡点的差异性:当在合同中增加奖励和惩罚措施时,纳什均衡的点将离原点更远,双方将以更大的概率选择合作。以此为基础,科学设立监管合同中监管项目的评价指标体系,明确监管奖惩措施,将有效降低供应链金融风险。     

重载轨道车辆非线性结构设计

为减轻重载轨道车辆质量, 提高车辆的承载能力, 对于采用具有强化效应高强度低合金钢的车辆结构, 按材料非线性理论, 允许结构局部塑性变形, 进行结构轻量化设计, 采取弱化端墙、强化底架的结构优化措施, 并采用几何非线性理论对其进行非线性稳定性分析。按此非线性分析方法, 对新研发的轴载40 _t、总载160 _t的重载敞车进行了车体结构优化设计。在纵向压缩工况下, 优化后车体结构最大应力为336 MPa, 小于材料Q450NQR1屈服强度450 MPa, 发生局部屈曲的最小临界载荷F_cr为6 252 kN。在纵向冲击工况下, 车体的大应力点分布在上侧梁和上端梁区域, 应力值达到530 MPa左右, 仍低于材料的极限强度550 MPa, 且底架上的应力分布较优化前更均匀。车体结构的强度、刚度及稳定性符合AAR标准规范要求, 车辆自重系数仅为0.16。分析结果表明非线性分析方法是重载车辆结构轻量化设计的有效手段。