驱动性能试验园地--MAP测试

OBD Ⅱ系统一直依赖于各种基本传感器所提供的信号输入,但是现在氧传感器在燃油控制与供给方面起到了更为突出的作用。     

利用OBDⅡ系统进行排放检测

OBD Ⅱ系统很快将取代标准排气管检测排放污染。在美国己制订了相应的法规,马克·沃伦先生在本文中解释这项法规涉及的内容以及与排气管检测的区别。通过本文,读者可了解排放检测的最新技术。     

我依然是局外人——宝马车手库比卡专访

踏入F1的第3年，23岁的Robert Kubica就拿下个人的首胜，而且他并非是待在传统强队之中，一度成为积分的暂时领先者，跃升为祖国波兰的超级明星人物，然而他依然保持低调的风格，凡事都有着超龄的成熟度，赛季迈入一半，让他来谈谈挤进Ferrari及Mclaren的争冠集团的感想。     

Condition monitoring of wooden railway sleepers

Wooden railway sleeper inspections in Sweden are currently performed manually by a human operator; such inspections are to large extent based on visual analysis. In this paper a machine vision based approach has been considered to emulate the visual abilities of the human operator to enable automation of the process. Digital images from either ends (left and right) of the sleepers have been acquired. A pattern recognition approach has been adopted to classify the condition of the sleeper into classes (good or bad) and thereby achieve automation. Appropriate image analysis techniques were applied and relevant features such as the number of cracks on a sleeper, average length and width of the crack and the condition of the metal plate were determined. Feature fusion has been proposed in order to integrate the features obtained from each end for the classification task which follows. The effect of using classifiers like multi-layer perceptron and support vector machines has been tested and compared. Results obtained from the experiments show that multi-layer perceptron and support vector machines have achieved encouraging results, with a classification accuracy of 90%; thereby exhibiting a competitive performance when compared to a human operator.     

Adapting the light · biomass (BZI) models of phytoplankton primary production to shallow marine ecosystems

Several authors have reported a strong linear relationship between daily phytoplankton production and the product of chlorophyll biomass, photic depth, and incident irradiance for a variety of estuaries. This “light · biomass” (BZ_pI_o) formulation has been proposed as an alternative to traditional mechanistic approaches for computing phytoplankton production in numerical estuarine models. One limitation to their application in shallow systems is that the BZ_pI_o models have been developed in relatively deep estuaries where light does not reach the bottom. We propose a nonlinear correction factor to adapt the BZ_pI_o relationship to shallow systems where light does reach the bottom. Our function takes into account variations in incident irradiance, attenuation coefficient for light, photosynthetic efficiency, and maximum rate of photosynthesis. A series of correction polynomials are proposed for various ranges of incident irradiance, and are integrated into a single multiple polynomial which applies across all irradiance levels. Our new correction factor was tested against a ¹⁴C-based productivity dataset from shallow stations in Narragansett Bay, RI and an O₂-based dataset from shallow (1.1 m) lagoon mesocosms at the University of Rhode Island. Results showed that our polynomials accurately correct BZ_pI_o-predicted rates of production in shallow water columns. Application of our correction factor to a series of shallow water productivity datasets from the literature together with theoretical calculations show how significant the shallow water correction can be, especially in very shallow water columns with low turbidity.     

Valuation of improved railway rolling stock: A review of the literature and new evidence

The paper provides a comprehensive review of a large amount of previously unpublished British evidence about the valuation of new railway rolling stock and its effects on demand. An important conclusion is that incentives to bias Stated Preference responses and unfamiliarity with the rolling stock being considered have led to inflated values. This has broader implications for the use of Stated Preference techniques. Also provided is fresh empirical evidence for a range of different types of rolling stock and specific rolling stock attributes. A novel aspect of the research was the use of disaggregate Revealed Preference choice data. The estimated rolling stock values are much lower than those obtained from previous studies.     

Is it the labor unions’ fault? Dissecting the causes of the impaired technical efficiencies of the legacy carriers in the United States

Data envelopment analysis is used to evaluate the technical efficiencies of a number of major passenger airlines in the United States at transforming their inputs (labor, fuel and fleet-wide seating capacity) into available seat-miles. A tobit regression model is then used to identify the underlying drivers of airline efficiency, as measured by the data envelopment analysis efficiency score. The impact of unionization on airline efficiency is found to be statistically insignificant, controlling for the influences of other hypothesized determinants of airline efficiency: the average age of an airline’s fleet, the average size of its aircraft, its average stage length, the extent to which the airline relies of hubbing within its route structure, the percent of its passenger enplanements that are international, and whether the airline is a legacy carrier. The statistically significant drivers of airline efficiency, at a ten percent level of significance, are average aircraft size, average stage length and the extent to which the airline relies on hubbing and connecting flights within its route structure. The stage length variable is not significant at a five percent level of significance, however. An increase in average aircraft size or in average stage length enhances an airline’s efficiency whereas an increase in hubbing reduces it.     

Suburban attitudes toward policies aimed at reducing solo driving

Policies that are aimed at discouraging commuters from solo driving have become a part of overall efforts to improve air quality and reduce traffic congestion. Since driving alone is the overwhelming choice of employed residents in US metropolitan areas, the political acceptability of proposed policy changes plays a role in their success. The 1992 Orange County (CA) Annual Survey asked employed solo drivers to rate their likelihood of changing from solo driving in response to various fees and incentives. Fewer say they would be very likely to stop solo driving if they were charged a parking fee at work (20%), a smog fee (17%) or a congestion fee (16%), than if their employers paid them a cash bonus for stopping solo driving (28%), or if more public transit (33%) or more carpools at work (35%) were available. Young and lower-status solo drivers are more likely than others to say they would stop driving alone if there were fees or cash bonuses. Current non-solo drivers tend to be young and low income, providing a validity check on the demographic predictors of stated preferences. The findings are discussed in light of recent policy changes in Southern California.