Locating and sizing park-ride lots with interactive computer graphs

Two alternative methods for conducting a preliminary analysis of the problem of locating and sizing park-ride lots for an urban bus transit system are examined. These alternative methods are tested using a large and complex street network representing the northern half of the City of Seattle, Washington. Four design criteria are identified and an overall measure of system performance is devised. The problem is to determine the size and location of three park-ride lots that will maximize the performance of the system. The first method utilizes a computing system called LOCATOR II in an interactive graphic mode. In an experimental setting, five students use LOCATOR II to locate three park-ride lots and their solutions are found to exhibit a very high average level of performance. The second method does not involve a direct interaction with the computing system but does use LOCATOR II in a batch mode. Several students participate in three rounds of the batch mode experiment and the performance of their designs is somewhat poorer than the designs found in the interactive graphics experiment. Overall, the experimental results show that relatively inexperienced persons can find a high performance design for a reasonably complex problem quickly and inexpensively. These designs can provide a good starting point for the detailed consideration of many of the other aspects of the problem of providing a high performance bus transit service in an urban area.     

The U.S.S.R.: Ocean Use and Ocean Law

This paper is an attempt to illustrate the stance of the Soviet Union in the law of the sea debate in the light of Soviet ocean activities. The paper has two sections. First, it examines the range of Soviet ocean activities. The considerable extent of Soviet ocean use underscores the importance which the Soviet Union places on the law of the sea debate and its consequent active participation in the process of international negotiation. Second, the paper considers the published record of the Soviet Union in the United Nations seabed debate. In seven years of debate the United Nations General Assembly and the Ad Hoc and permanent Seabed Commities and sub-Commities have generated a considerable body of documantation reflecting the public policy of over one hundred States concerning the law of the sea. Soviet expressions of opinion alone cover more than five hundred pages of documentation. Specific Soviet positions can be considered within two ganeral preferences: the protection of traditional freedoms of the high seas and opposition to ocean control by either coastal States or by an independent international ocean authority. The paper shows how these preferences and the specific Soviet negotiating positions defend and promote the maritime interests of the Soviet Union.     

Adaptive Suspension Concepts for Road Vehicles

Most vehicle suspensions are composed of passive spring and damper devices, although improved suspension performance is possible if an active system is used to control forces or relative velocities. The complexity, power requirements, and cost of fully active suspensions have restricted their use. Various partially active suspensions have been proposed and suspensions with slow load levelers and variable dampers are in widespread use. Here we analyze a class of basically passive suspensions the parameters of which can be varied actively in response to various measured signals on the vehicle. These suspensions can come close to optimal performance with simpler means than many of the active or semi-active schemes previously proposed.     

Semi-Active Control of Wheel Hop in Ground Vehicles

A two degree-of-freedom vehicle model is developed which incorporates passive, active, and semi-active secondary suspensions. The model is used to demonstrate the trade-offs which are inherent in attempting to provide desirable sprung weight isolation while at the same time controlling unsprung weight motions.

A linear model is used first in order to compare passive and active suspensions in an analytically understandable configuration. The semi-active suspension is inherently nonlinear and is compared to the others through computer simulation. The passive suspension is, of course, the most restrictive in providing simultaneous isolation of sprung and unsprung weight; however, the active suspension is also compromised in providing both functions. The semi-active suspension does an excellent job of tracking its active counterpart.     

The Response of Active and Semi-active Suspensions to Realistic Feedback Signals

A simple vehicle model is presented incorporating passive, active, and semi-active suspensions. When the desired feedback variables are ideally available, the system response is well understood and excellent sprung mass isolation results. More often than not, the measured variables must be signal processed in some manner prior to their use in some control algorithm. This paper presents the expected response of a simple vehicle with an active and/or semi-active suspension, subject to non-ideal feedback information.     

拥挤收费的政治策略

通过收费缓解交通拥堵的政治可行性取决于谁获得通行费收入。指出如果收益被分配给城市,特别是高速公路经过的城市,拥挤收费取得政治成功的可能性最大。与已有的很多建议不同,指出城市是比个体驾驶人和区域政府更有力的收益申索人。基于行为经济学和政治科学理论并结合几个大都市区的数据,对提议进行解析和阐述。在洛杉矶,潜在的拥挤收费收入估计每年接近50亿美元,将这些收入分配至高速公路经过的城市对拥挤收费的实施是有政治影响力和促进作用的。     

Quantifying anthropogenic shoreline modification of the Hudson River and Estuary from European contact to modern time

Abstract

Anthropogenic modifications to the shoreline of the New York Harbor estuary and the tidal portion of the Hudson River have been mapped and quantitatively assessed. Modifications studied include the filling of tidal salt‐ and freshwater marshes and the creation of fast land as well as dredging, shoreline armoring, and dike installation. Because the Hudson Estuary and River comprise a historically and commercially important harbor and waterway, shoreline modification commenced shortly after European colonization. While in the harbor segment of the estuary only about 20% of the original wetland areas remain today, the tidal Hudson River has seen a net increase in tidal freshwater wetland area of about the same magnitude resulting principally from shoreline railroad construction. Several different methods were used in compilation of the historical shoreline. Because determination of historical shorelines is important to public trust lands and to estuarine rehabilitation, data bases are being constructed incorporating those shorelines. The experience of this project suggests the benefits and problems associated with the techniques used.     

Ocean energy—an update

The oceans of the world, which comprise 71% of the earth's surface, provide a vast resource of renewable energy which has only been used in limited quantities. The feasibility of the extraction of energy from the ocean has been discussed and deemed possible, but with very few successful applications. However, as the world energy and economic situation changes, many countries are initiating R&D programmes to use the ocean waves, tides, currents, and temperature differentials to produce electricity. The transmission and utilization of this oceanderived electricity requires the integration of an ocean facility into an existing land-based electric power transmission grid. Extensive use of this energy source is still years in the future; however, prototype systems have been and are being developed so that this limitless supply can be successfully tapped.     

Suburban service in North America today—Which way will we go?

The current situation of suburban rail services is reviewed. Differences between seemingly similar services—urban transit, commuter service, suburban rail service and regional rail -are discussed. The suburban rail commuter is described as the true intermodal traveler. Differences of the political backgrounds of the inner-city compared to the suburbs complicate implementation of programs to improve service and suggest deep problems over the long term. Because the transition of suburban rail service from the private to public sector has been so recent, it is difficult for many to recognize that the profit of the service is in the lower total transportation costs for the community as compared to a cash dividend. Existing railroad lines in many cities have the potential of being a cost-effective solution to traffic problems, although the specific solutions vary widely, ranging from the operation of new commuter trains over the lines of a heavy duty railroad (Toronto) to a completely new light rail system (San Diego).     

What Does Happen to Our Driving When We Get Older?

Abstract

The objective of this paper is to uncover the main antecedents associated with driving errors among older drivers in order to establish a framework for analyzing potential skill improvements using other approaches, for example, games. The article also aims at classifying age-related declines in seniors' abilities associated with their driving performance. The research undertakes an analysis of attempts made through the investigation of the literature. We have systematically searched papers and extracted (1) prevalent driving errors among seniors and (2) underlying age-related declines in seniors' abilities associated with their driving performance. We have also identified some characteristics of the research in this area (e.g. the research methods and geographical distribution of the research). Our expert panel mapped the functional declines in seniors' abilities to the driving errors to identify the relationship between these findings. A reliability test resulted in 81% reliability of findings. We have identified eight groups of driving errors, which could be affected by physical, visual, and cognitive declines among seniors. According to the experts' opinions, the underlying relationship of physical, visual, and cognitive declines among seniors and their driving errors were also presented. Our findings show that there is a potential for the use of innovative interventions such as playing video games to create an inexpensive, motivational, and enjoyable method that may provide a transfer effect to specific driving skills. This could help improve seniors' driving performance by improving specific functional abilities associated with driving.