实施物流目标成本事前管理的方法探讨

物流目标成本事前管理是物流企业施行物流目标成本管理的最重要环节,然而在实施过程中却存在着各种问题。本文将站在另外一个角度,对物流企业如何有效实施目标成本事前管理进行尝试性的探索。     

影响人寿保险发展的因素与对策分析

分析了影响和制约我国寿险发展的经济因素、契约保全因素和理赔风险管理因素,提出了促进寿险健康发展的对策与措施.     

神经网络集成在工程造价估算中的应用研究

工程造价和主要工程量是评价一建筑工程的重要经济指标,特别是工程量清单于2003年7月1日在全国范围内展开以来,快速估算工程造价和主要工程量更具有其重要意义.文中采用神经网络集成方法建立了工程造价和主要工程量估算数学模型,并采用matlab6 1计算软件,以深圳市已完典型工程资料为例,验证了该模型的正确性及实用性,得出了神经网络集成方法泛化能力更高的结论.     

海洋平台KK型管节点的疲劳性能试验研究

以某自升式海洋平台为研究对象,进行了空间KK型管节点在轴力作用下的疲劳性能的试验研究.通过对管节点模型的试验测试,得到了KK节点在轴力作用下沿着焊缝周围的热应力区内的热点应力分布及节点的应力集中系数,并采用S-N曲线法对KK型管节点的疲劳寿命进行估算.通过对比分析,指出了试验方法与规范计算方法在管节点疲劳性能分析上的差异性.     

冻融作用下的沥青混合料力学特性

冻融损坏是冰冻地区沥青混合料的主要破坏形式。通过冻融循环作用下的沥青混合料单轴压缩和劈裂强度试验,分析了冻融循环次数、油石比等因素对沥青混合料力学特性的影响。试验得出,冻融循环次数和油石比对混合料的抗压和劈裂抗拉特性均有影响,油石比越小,影响越明显;在最佳油石比5.5%时,混合料的抗冻性能最好;冻融循环次数对沥青混合料力学特性的影响逐渐减弱,在10~12次冻融循环后,沥青混合料冻融后的强度和模量损失率均逐渐趋于稳定。     

ITS Ͷ����Ŀ�����з���Ч��Ͳ�ȷ���Է���

通过对ITS 投资项目的费用效益分析的系统研究，提出了建立ITS 投资项目费用效益分析的框架和技术流程的具体步骤，阐述了评价指标的计算方法、方案的可行性评价和方案选优等内容，研究了费用和效益的划分和估计方法. 另外，本文提出了不确定性分析的概念和方法，并对敏感性分析和概率分析进行了重点研究. 结合IDAS 软件，通过示例论述了上述方法的技术实现.     

钛合金疲劳小裂纹扩展行为预报方法研究

针对小裂纹扩展阶段裂纹尖端塑性区域尺寸相对于小裂纹长度是不可忽略的问题,在考虑小裂纹效应裂纹扩展速率修正模型基础上,对该模型中裂纹尺寸进行修正,即裂纹长度等于真实裂纹长度加上平面应变状态下裂纹尖端塑性区域一半;并利用修正后的模型对钛合金材料不同情况下疲劳小裂纹扩展速率和寿命进行预报,同时将预报结果与试验值比较.结果表明:修正后的预报模型对小裂纹扩展速率和寿命均有很好的预报效果.     

海上风机支撑结构的时域和频域疲劳对比研究

对海上风机支撑结构进行动力响应分析,求出结构危险节点的载荷谱和功率谱密度函数,结合疲劳损伤模型和Dirlik概率模型,分别在时域和频域内对支撑结构进行疲劳寿命分析.由于时域法计算疲劳寿命需进行应力循环计数,这一过程需处理的数据庞大,耗时长.频域法省去应力循环计数,代之以概率密度函数,可相对准确、快速地计算结构的疲劳寿命.分析结果表明,采用Dirlik概率模型的频域分析法能较准确地反映海上风机支撑结构在随机载荷作用下的疲劳损伤情况,计算结果误差在可接受范围内.     

Environmental impacts of public transport systems using real-time control method

Public Transport (PT) systems rely more and more on online information extracted from both operator’s intelligent equipment and user’s smartphone applications. This allows for a better fit between supply and demand of the multimodal PT system, especially through the use of PT real-time control actions/tactics. In doing so there is also an opportunity to consider environmental-related issues to approach energy saving and reduced pollution. This study investigates and analyses the benefits of using real-time PT operational tactics in reducing the undesirable environmental impacts. A tactic-based control (TBC) optimization model is used to minimize total passenger travel time and maximize direct transfers (without waiting). The model consists of a control policy built upon a combination of three tactics: holding, skip-stops, and boarding limit. The environmental-related measure is the global warming potential (GWP) using the life cycle assessment technique. The methodology developed is applied to a real life case study in Auckland, New Zealand. Results show that TBC could reduce the GWP by means of reduction of total passenger travel times and vehicle travel cycle time. That is, the TBC model results in a 5.6% reduction in total GWP per day compared with an existing no-tactic scenario. This study supports the use of real-time control actions to maintain a reliable PT service, reducing greenhouse gas emissions and subsequently moving towards greener PT systems.     

Electric vehicles for greenhouse gas reduction in China: A cost-effectiveness analysis

There have been ongoing debates over whether battery electric vehicles contribute to reducing greenhouse gas emissions in China’s context, and if yes, whether the greenhouse gas emissions reduction compensates the cost increment. This study informs such debate by examining the life-cycle cost and greenhouse gas emissions of conventional vehicles, hybrid electric vehicles and battery electric vehicles, and comparing their cost-effectiveness for reducing greenhouse gas emissions. The results indicate that under a wide range of vehicle and driving configurations (range capacity, vehicle use intensity, etc.), battery electric vehicles contribute to reducing greenhouse gas emissions compared with conventional vehicles, although their current cost-effectiveness is not comparable with hybrid electric vehicles. Driven by grid mix optimization, power generation efficiency improvement, and battery cost reduction, the cost-effectiveness of battery electric vehicles is expected to improve significantly over the coming decade and surpass hybrid electric vehicles. However, considerable uncertainty exists due to the potential impacts from factors such as gasoline price. Based on the analysis, it is recommended that the deployment of battery electric vehicles should be prioritized in intensively-used fleets such as taxis to realize high cost-effectiveness. Technology improvements both in terms of power generation and vehicle electrification are essential in improving the cost-effectiveness of battery electric vehicles.