Optimization of pedestrian phase patterns at signalized intersections: a multi‐objective approach

This paper presents a multi‐objective optimization model and its solution algorithm for optimization of pedestrian phase patterns, including the exclusive pedestrian phase (EPP) and the conventional two‐way crossing (TWC) at an intersection. The proposed model will determine the optimal pedestrian phase pattern and the corresponding signal timings at an intersection to best accommodate both vehicular traffic and pedestrian movements. The proposed model is unique with respect to the following three critical features: (1) proposing an unbiased performance index for comparison of EPP and TWC by explicitly modeling the pedestrian delay under the control of TWC and EPP; (2) developing a multi‐objective model to maximize the utilization of the available green time by vehicular traffic and pedestrian under both EPP or TWC; and (3) designing a genetic algorithm based heuristic algorithm to solve the model. Case study and sensitivity analysis results have shown the promising property of the proposed model to assist traffic practitioners, researchers, and authorities in properly selecting pedestrian phase patterns at signalized intersections. Copyright © 2013 John Wiley & Sons, Ltd.     

Towed-Diver Surveys,a Method for Mesoscale Spatial Assessment of Benthic Reef Habitat: A Case Study at Midway Atoll in the Hawaiian Archipelago

An integrated method for benthic habitat assessment is described, in which divers maneuver boards equipped with digital video, temperature, and depth recorders while being towed behind a small boat. The tow path is concurrently recorded by a GPS receiver, and a layback model is applied to more accurately map the data. Percent cover of salient benthic categories is quantified by whole-image analysis of still frames sampled at 30-s intervals. The results of 15 towed-diver surveys at Midway Atoll in the Hawaiian Archipelago during a mass coral bleaching event are presented to exemplify the method and are compared to results derived from conventional methods. Towed-diver surveys bridge a gap between large-scale mapping efforts using satellite data and small-scale, roving diver assessments, providing a mesoscale spatial assessment of reef habitats. The spatial coverage of towed-diver surveys provides comprehensive data to managers concerning the extent, intensity, differential taxonomic response, and bathymetric correlates of bleaching.     

The role of the Federal Government in US marine transportation

The United States meets the world shipping crisis of the 1970s with a high-cost merchant fleet and a national maritime policy which needs clearer articulation. This paper examines the objectives, rationale and methods of implementation of the Us maritime programme with attention, finally, to the question of governmental reorganization.     

Impact of offshore oil and gas development on the coastal zone: Reforming the impact assessment process

In an otherwise complex regulatory system, the federal Environmental Impact Statement process affords local decision makers and coastal zone residents a rare opportunity to analyze the comprehensive range of land‐use and environmental issues that may arise from Offshore Continental Shelf (OCS) hydrocarbon development, while there is still time to formulate effective management strategies. As exemplified by the lease sale 40 statements, present onshore impact assessment procedures are sufficiently flawed to seriously compromise this goal. Critical deficiencies include failure to emphasize onshore impacts; insensitivity to spatial variations of impact; neglect of available data; rigid, unsupported assumptions; and preoccupation with short‐trm effects to the exclusion of more significant and dependent long‐term consequences. Suggested reforms include preparation of separate exploration and development impact statements; establishment of special Council on Environmental Quality review procedures; modification of the judicial review process; and provision of additional support to local onshore OCS impact areas.     

A Systematic method of public use zoning of the Great Barrier Reef Marine Park,Australia

Abstract

This paper is an abridged version of a report on the application of a land‐use planning method developed by the Commonwealth Scientific and Industrial Research Organisation (CSIRO) to the task of providing a zoning scheme for a portion of the Great Barrier Reef Marine Park. The approach involves the development of guidelines for making zoning decisions, the development of methods for measuring whether a scheme satisfies these guidelines, and the use of a computer‐aided technique to create successive schemes for evaluation against these guidelines.     

新开发的轮对设计方法

轮对设计在车轮磨耗方面正面临着严格的新规范 ,以降低外形车削的要求 ,并减轻质量 ,以减少对轨道的侵蚀 ,且在可靠性、运行安全性和寿命周期成本都没有不利影响的情况下 ,实现所有要求。与此同时 ,由于车辆有既在小半径曲线 ,又在高速线路上运行的趋向 ,在普通线路上提高了运行速度 ,以及由于低级维护而使线路质量和车辆质量有所降低 ,所以轮对的运行作用正在变化。为此 ,开发了一整套程序 ,以便为高速列车设计振动小、噪声低、寿命周期成本最佳的轮对 ,也为城市轨道车辆设计新型的使用铝制轮毂、钢制车轴和轮辋的轻型混合车轮。该程序以采…     

新型快餐盒生物降解性能试验方法研究

通过固体培养微生物侵蚀试验、液体培养微生物侵蚀试验、降解过程中纤维素酶活性测定、纤维素酶侵蚀试验和降解过程中 Ｃ Ｏ２ 生成体积分数的测定等试验结果分析，认为固体培养微生物侵蚀试验、纤维素酶侵蚀试验及 Ｃ Ｏ２ 生成量测定试验可用于评价新型快餐盒生物降解性能。     

Effect of engine exhaust gas modulation on the cold start emissions

This paper presents a computational investigation of the effect of engine exhaust gas modulations on the performance of an automotive catalytic converter during cold starts. The objective is to assess if the modulations can result in faster catalyst light-off conditions and thus reduce cold-start emissions. The study employs a single-channel based, one-dimensional, non-adiabatic model. The modulations are generated by forcing the variations in exhaust gases air-fuel ratio and gas compositions. The results show that the imposed modulations cause a significant departure in the catalyst behavior from its steady behavior, and modulations have both favorable and harmful effects on pollutant conversion during the cold-starts. The operating conditions and the modulating parameters have substantial influence on catalyst behavior.     

A “horizontal Sverdrup mechanism” may control the spring bloom around small oceanic islands and over banks

One of the most basic paradigms in marine ecology is the “Sverdrup mechanism,” where the spring bloom is retarded if the surface mixed layer is too deep, due to the algae being mixed vertically out of the euphotic layer. A similar mechanism may operate in vertically homogeneous water over a small shallow area, surrounded by deep waters, if the horizontal exchange is sufficiently intense. In systems with inter-annual variations in the horizontal exchange rate, this may induce inter-annual variations in the timing and intensity of the spring bloom. A numerical primary production model with circular symmetry and prescribed horizontal exchange rate is developed. Using the Faroe Shelf as an example, the model and observations show that the timing and intensity of the spring bloom in the shallow parts of the system may be critically dependent upon the rate of the horizontal exchange. Numerical experiments confirm that the effect of horizontal exchange on the spring bloom is less pronounced for banks than for shelf systems around islands of similar scales, and that the effect increases in importance as the horizontal scale is reduced.     

高速铁路车辆车轴的疲劳设计方法

从19世纪早期铁路运营开始,车轴的疲劳设计就是工程设计人员在材料的疲劳研究方面的一个难点。为了保证高速铁路系统的安全,一些杰出的研究人员进行了大量的投资和试验,并且在材料、制造、热处理和设计方法等方面取得了很大进步。比较欧洲和日本在高速铁路车辆车轴疲劳设计上的原理,认为在新干线车辆和TGV,ICE之间存在一些区别。疲劳强度的危险部位主要是容易受到磨损和疲劳损伤的压装配合部位,如轮座、齿轮座和制动盘座等部位。在欧洲,车轴压装部位采用大直径使危险部位平滑;在日本采用高频硬化的方法提高压装部位的疲劳强度,同时在车轴的压装部位附近设置了应力释放槽。多年来,新干线的车轴经过磁粉探伤没有发现疲劳磨损裂纹,这表明高速铁路车轴的安全性多年的改进是成功的。