宽量程空-燃比传感器的检测

使用宽量程空/燃比传感器已经有几年了,但人们对此并不十分了解,沃伦先生告诉我们如何利用故障扫描仪处理这些数据。     

Do motor-vehicle users in the US pay their way?

Governments in the US spend over a hundred billion dollars per year to build and maintain roads and provide a variety of services for motor-vehicle users. To pay for these infrastructure and services governments collect revenue from a variety of taxes and fees. The basic objective of this paper is to compare these government expenditures with the corresponding user tax and fee payments in the US. At the outset I argue that the such comparisons tell us something about the equity but not necessarily the economic efficiency of highway financing. I then present four different ways one might tally up government expenditures and user payments, depending on the extent to which one wishes to count “indirect” expenditures (e.g., on prosecuting car thieves) and non-targeted general-tax payments (e.g., severance taxes on oil). I make a comprehensive analysis of all possible expenditures and payments, and then compare them according to three of the four ways of counting expenditures and payments. The analysis indicates that in the US current tax and fee payments to the government by motor-vehicle users fall short of government expenditures related to motor-vehicle use by approximately 20–70 cents per gallon of all motor fuel. (Note that in this accounting we include only government expenditures; we do not include any “external” costs of motor-vehicle use.) The extent to which one counts indirect government expenditures related to motor-vehicle use is a key factor in the comparison.     

Household type and structure, time-use pattern, and trip-chaining behavior

In order to examine time allocation patterns within household-level trip-chaining, simultaneous doubly-censored Tobit models are applied to model time-use behavior within the context of household activity participation. Using the entire sample and a sub-sample of worker households from Tucson’s Household Travel Survey, two sets of models are developed to better understand the phenomena of trip-chaining behavior among five types of households: single non-worker households, single worker households, couple non-worker households, couple one-worker households, and couple two-worker households. Durations of out-of-home subsistence, maintenance, and discretionary activities within trip chains are examined. Factors found to be associated with trip-chaining behavior include intra-household interactions with the household types and their structure and household head attributes.     

An approximate analytic model of supertanker lightering operations

The most economical means of transporting crude oil over long distances is through the use of very large and ultra large crude containers (VLCCs and ULCCs respectively). These ships require sea lane depths of more than 55 feet to navigate. Since no major U.S. port is deeper than 45 feet, special offloading procedures must be employed. One such procedure is lightering, the process of offloading crude oil from VLCCs to smaller vessels for final delivery to the port.A linked set of queuing models is developed in an effort to understand lightering operations better and to enhance tradeoff analyses. The model assumes that port service times, lightering vessel loading times and VLCC interarrival times are exponentially distributed, allowing us to model lightering vessel operations using a cyclic queuing model. VLCC delays are modeled using an approximate M/E_k/S queue. The two models are linked through a VLCC service time model. The sensitivity of the model to changes in key inputs as well as the likely impacts of the model's assumptions and approximations are discussed. The paper concludes with recommendations for future studies.     

Ridership estimation for short-range transit planning

The objective of this research was to develop a simple transit ridership estimation model system for short-range planning. The main feature of the model system is that it exploits knowledge of transit link volumes which are obtained readily from on-off counts. Extensive use is made of default values for model parameters, taken directly from the transportation literature. The remaining parameters can be derived easily from generally available land-use and socioeconomic data. Expensive household surveys and time-consuming model calibrations are not required. A sequence of simple trip generation, trip distribution and modal split models generate trip-purpose specific transit trip tables, denoted as “trial” trip tables. These trip tables and observed transit link volumes are used in a linear programming model which serves as a correction mechanism. The gain in accuracy is achieved by using the ridership information contained in the transit link volumes. The corrected trip tables may be used in a pivot-point analysis to estimate changes in ridership and revenue. The results of a test application of the model system indicate that it can generate accurate ridership estimates when reliable transit link volumes are available from on-off counts, and when the trial transit trip tables as derived from the first three component models are reasonably accurate.     

Investigating the link between cyclist volumes and air pollution along bicycle facilities in a dense urban core

In this paper we explore the air pollution levels along types of bicycle facilities using a NO₂ land use model previously developed for Montreal. We explore potential associations between bicycle volumes through signalized intersections and pollution levels at those intersections. We further investigate this relationship through the comparison of over thirty cycling corridors as well as an evaluation of the potential exposure of cyclists to air pollution along five routes. We observe NO₂ concentrations to be positively correlated with bicycle flows at the intersection level. We also observe that corridors with either a bicycle path or cycle track generally rank higher in terms of bicycle volume and also have higher NO₂ concentrations than corridors without bicycle facilities. This indicates that intersections and bicycle facilities with a large number of cyclists are also those characterized with the highest air pollution levels.     

A simulation‐based reliability assessment approach for congested transit network

This paper is an attempt to develop a generic simulation‐based approach to assess transit service reliability, taking into account interaction between network performance and passengers' route choice behaviour. Three types of reliability, say, system wide travel time reliability, schedule reliability and direct boarding waiting‐time reliability are defined from perspectives of the community or transit administration, the operator and passengers. A Monte Carlo simulation approach with a stochastic user equilibrium transit assignment model embedded is proposed to quantify these three reliability measures of transit service. A simple transit network with a bus rapid transit (BRT) corridor is analysed as a case study where the impacts of BRT components on transit service reliability are evaluated preliminarily.     

Kuwaiti tanker reflagging_a confluence of foreign and maritme politime policies

In 1987, the government of Kuwait requested permission of the US government to reflag 11 of its tankers to the American flag for the purpose of gaining protection from Iranian attacks. The US government agreed, citing overall strategic and political considerations. As part of the reflagging, waivers were granted to permit the vessels to operate without proper inspections and without licensed radio operators. Furthermore, the vesels employed only one US mariner each, th eecaptain, and though subsequent legislation closed the 'loophole' through which that occurred, anotherr waiver allowed the Kuwaitis to continue without hiring Americans. The maritime policy implications-and the juxtaposition of maritime and foreign policies-were of concern to members of Congress, who held hearings and introduced and passed legislation on the issue.     

Stated willingness to participate in travel surveys: a cross-country and cross-methods comparison

Transportation - Travel surveys are the primary source of data that feed into the analysis and modeling of travel behaviour. Numerous studies have found that the survey method, be it pen and paper,...