EGR率对柴油机富氢EGR燃烧过程的影响

在一台柴油机可视化实验台上,用高速摄像机拍摄下柴油机富氢EGR燃烧过程的火焰照片,应用三基色法计算了燃烧温度场,结合示功图和放热率曲线分析了EGR率对富氢EGR燃烧过程的影响.结果表明:当掺氢比为2％时,随着EGR率的增加,着火时刻呈现推迟的趋势,燃烧持续时间先延长后缩短;缸内最大爆发压力减小,达到峰值压力的时间推迟;放热率峰值下降,放热率曲线整体推后;缸内最高温度和平均温度随之降低.     

Indicators for Evaluating the Impact of Artificial Islands on the Barcelona Coast

Artificial islands have been constructed next to large cities due to the need for extra space in highly populated areas. These emerged structures have been used by many countries as platforms for developing infrastructure (airports, harbors, highways, etc.), rebuilding ecological areas, and creating new spaces for tourism or residential areas. In this study, two state-of-the-art numerical models for wave propagation and nearshore circulation are used to simulate the effects of an emerged artificial island on the Barcelona coast. Several sea indicators (wave height, intensity and direction of currents, and mean water level) are analyzed to assess the changes likely to be induced by an artificial island. Three different situations are studied and the indicators are compared across the different tests to obtain information that can be used in the planning process of these structures. In two-meter wave conditions, the tests show that wave height is generally reduced in the sheltered area, which leads to improved safety for beach users (bathing is prohibited when wave height exceeds the two-meter threshold). However, the numerical models also reveal that velocities in the sheltered area usually decrease, which must be controlled to prevent stagnation in the bathing area.     

Optimization of shipyard space allocation and scheduling using a heuristic algorithm

In this article we describe the development of a tool that allows planners to efficiently and effectively plan space within valuable areas of a shipyard. Traditionally, space is considered as resource; however, it is difficult to accurately account for and plan its consumption with the currently available planning software’s. The spatial scheduling tool described in this article can be used by planners to manually or automatically reserve space within the shipyard for construction of large blocks over the entire erection period of the ship. The software is coupled with a heuristic optimization solver inspired by an algorithm used for "3D bin-packing problems." The result is the ability to efficiently generate and compare multiple space allocation alternatives in a reduced time with the ultimate goal of maintaining the critical ship erection schedule. A better solution than manual or semi-automatic allocation of blocks can be obtained through the optimization module.     

高科技企业基于核心战略的人力资源规划研究

高科技企业作为我国国民经济的重要组成部分,拥有其自身特点和优势.人力资源作为企业的第一资源,是企业发展最具影响力的战略因素之一,而人力资源规划作为人力资源管理的一项重要职能,在高科技企业内部需要得到高度重视.从高科技企业人力资源规划面临的挑战人手,设计了基于核心战略的人力资源规划,为企业的人力资源管理提供了有力支持.     

Hub dependence in constrained economies: the case of North Korea

While the geographical and economic factors concerning the development of hub ports are widely described by a variety of scholars and professionals, there is no recognized methodology measuring the hub dependence of a given port, region, or country. Based on a 20-year database of vessel movements, this paper proposes a methodology measuring hub dependence. North Korea offers a good case of a constrained economy facing dramatic internal and external pressures. Notably, the weight and geographical extent of its maritime connections are worth analysing because of its contrasted evolution from Soviet influence, geopolitical isolation, and growing trade due to economic reforms and increased foreign investments. The main results of this study show the spatial shift from long-distance calls to feeder calls: global foreland contraction, regionalization within Northeast Asia, and traffic concentration upon closest hubs of which South Korean ports. We conclude that hub dependence is a combination of local constraints and trade growth. The political implications of this phenomenon are explored, and a spatial model of hub dependence is proposed.     

Mature hub ports in the free trade environment,the way forward from a global supply chain perspective: an Asian case

Asia-Pacific countries with divergent economic and political backgrounds developed a regime of bilateral free trade agreements in response to globalization. Challenged by the 1997 and 2008 financial crises, this Asian trade regime has remained intact, although the most powerful stakeholders have changed positions, as indicated by the strong emergence of China in the past decade. Efforts of key trading partners to tackle non-tariff barriers (e.g., rule of origin and customs formalities) in the region have yielded little progress thus far. Instead of aiming at a regional consensus on non-tariff barriers by all member states, a global supply chain (GSC) approach is recommended. Mature hub ports at strategic locations with advanced institutional measures could set up international trade facilitation centers co-locating multinational customs formalities. This GSC approach may also be adopted to construct a GSC hub development model that explains the transformation of hub ports.     

Ultimate strength assessment of a tanker hull based on experimentally developed master curves

A geometrically similar scaling was made from small-scale specimen to full-scale stiffened panels and then their collapse behaviour is investigated. It is considered that the stiffened panel compressive ultimate strength test was designed according to geometrical scaling laws so that the output of the test could be used as representative of the stiffened panels of the compressive zone of a tanker hull subjected to vertical bending moment. The ultimate strength of a tanker hull is analysed by a FE analysis using the experimentally developed master stress-strain curves which are obtained by the beam tension test and the compressive test of the stiffened panel, and are then compared with the result achieved by the progressive collapse method.     

Road Safety Strategies: A Comparative Framework and Case Studies

Abstract

This paper proposes a nine‐component analytical framework for developing, comparing, and evaluating road safety strategies. The nine components are: (1) vision; (2) objectives; (3) targets; (4) action plan; (5) evaluation and monitoring; (6) research and development; (7) quantitative modelling; (8) institutional framework; and (9) funding. While the first four components are essential for the formulation of a road safety strategy, the remaining components are key to its successful implementation. To demonstrate the usefulness of this comparative framework, we examine the road safety strategies of six selected administrations: Australia, California, Great Britain, Japan, New Zealand, and Sweden. In these case studies, we extract and highlight good practices in the formulation and implementation of their road safety strategies. The proposed framework also provides a systematic approach for assessing road safety strategies in other administrations. The evaluation of the six case studies forms a benchmarking platform for the planning, formulation, and implementation of good practices for road safety strategies.