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161.
<Emphasis Type="Italic">Not</Emphasis> driving alone? American commuting in the twenty-first century
This paper investigates recent commuting trends by American workers. Unlike most studies of commuting that rely on data from
the American Community Survey this study utilizes the American Time Use Survey to detail the complex commuting patterns of
modern-day workers. Changes in the price of gasoline in recent years suggest that the incidence of “driving alone” should
be on the decline. Indeed, results show that the sensitivity of modal commuting with respect to changes in gasoline prices
appears to be relatively large. We estimate the gasoline-price elasticity of driving alone to be 0.057 and the gasoline-price
elasticity of carpooling to be 0.502. Additional factors also affect commuting, including socio-economic characteristics and
social desires. However, it is changes in gasoline prices that appear to account for nearly all of the recent variation in
the mode chosen for commuting. 相似文献
162.
Institutes imparting training in marine engineering require replication of shipboard ambience for strengthening the competencies. For building an engineering centre for training, five options at different physical levels were considered based on a model of a new liquefied natural gas tanker ship build. A mock-up facility, simulator, full-scale engine room, scaled down version and a combination arrangement with live and dummy equipment were the options. Analytic hierarchy process was applied for selecting a suitable option based on criteria of cost, effectiveness in attaining competencies, practicability and environmental conduciveness. Analyses were carried out on the eigenvalues based on eight subselection criteria. The combination of live equipment (boilers and turbo alternator) and non-live shipboard equipment (auxiliaries) was chosen based on the global weightages obtained from the pairwise comparison matrix computations. The reliability was ascertained from the consistency index which was less than 0.1. For selection of the learning modes and the equipment, a constructivist approach of learners reflecting and choosing the learning mode was adopted. Industry practitioners were made into learner groups composed of trainers, shipboard personnel and company personnel. Established competencies were assigned as scores to the different learning modes. ANOVA application and statistical methods were used to analyse the scores to verify if there were too much variation in the choices. The calculated F ratio values were low (0.14 to 0.40) compared to the reference values indicating that the choices were even. The chi-squared test indicated that the group composition did have an influence on choosing the learning mode and equipment for training. The objective of identifying the learning mode and equipment for the training centre was achieved. 相似文献
163.
In order to compare the ventilation efficiency and air speed of the tunnel for different parameters of ventilation openings, the acrylic board is used to build a 1:15 tunnel model and carry out the proportional model test. Four working conditions are set up to compare the ventilation in the tunnel under different ventilation openings in terms of number, length and height. The experimental results show that the air velocity distribution and ventilation efficiency change significantly under different ventilation openings in terms of number, length and height. Based on the test results, the best setting pattern of the ventilation opening is proposed in this paper. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved. 相似文献
164.
The shield tunnel is an ultra-long linear space. It will cause a lot of dust during the tunnel maintenance and overhaul operation, which is extremely unfavorable to the physical and mental health of the construction personnel and the environment outside the tunnel. It is difficult to guarantee the ventilation effect of the linear space using the conventional dust removal technology, which directly affects the construction safety and overhaul period. Therefore, based on the overhaul of a cross-river tunnel in Shanghai, combined with Computational Fluid Dynamics (CFD) simulation, device optimization and process combination, a three-stage dust reduction standardization process for tunnel overhaul construction is proposed, namely taking a water sprayer at the working point to control the dust at the source (primary protection); installing electrostatic dust removal and water filtration dust removal equipment in the tunnel(secondary protection); and installing two sets of water curtain spray device at the two tunnel exits to prevent dusts from diffusing into the atmosphere. It explores the actual dust-reducing effects of different dust-removing measures and layout combinations, laying a technical foundation for green and efficient dust reduction. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved. 相似文献
165.
Brenda B. Lin Tim Capon Art Langston Bruce Taylor Russ Wise Rachel Williams 《Coastal management》2017,45(5):384-405
Climate change adaptation presents a difficult challenge for coastal towns around the world, forcing local governments to plan for sea level rise in a contentious decision-making space. The concept of “adaptation pathways,” a diagnostic and analytical tool to assist in adaptive planning and decision-making, is gaining traction as a way of framing and informing climate adaptation. It provides decisionmakers a way to acknowledge the inter-temporal complexities and uncertainties associated with the novel dynamics of climate change and a mechanism to manage these challenges in the local context. In 2012, the Australian Government funded an 18-month program to provide decisionmakers in the coastal zone an opportunity to test the utility of the adaptation pathways concept for coastal climate adaptation. Using a selection of completed projects as case studies, we performed a document analysis to better understand the learnings from the projects. The main themes surrounded: (1) the utility of the adaptation pathway framework in developing options, (2) decision-making rationale and criteria, and (3) stakeholder participation in pathway development. A project participant survey was developed to further understand these themes. Our analysis reveals that “adaptation pathways” was generally framed narrowly and conservatively to emphasize extant economic, administrative and legal considerations over community, participatory, or exploratory ones. Although some case study projects were able to reach a point in the pathway discussion to actively involve stakeholders in their decision-making process, many case studies continued to build technical data as a method for defending policies and actions. These results indicate that coastal adaptation can take-up adaptation pathways as a useful concept for decision-making and planning; however, many councils may still require assistance in stakeholder communication processes in order to develop sociallyacceptable plans that take into account the full range of values affecting local coastal environments. 相似文献
166.
Mass transit projects are often a top contender of many cities to meet their increasing demand for travel. Despite the global
trend of privatization, mass transit services, as public goods, remain largely being provided and operated by the public sector.
Hong Kong is one of the few exceptions that all mass transit services are commercially operated. Both rail and bus services
in Hong Kong are reputable for their quality and profitability, often serving as benchmarks for new projects. In this study,
we investigate the factors contributing to this success. In particular, we ascertain the quality of transit service provision
by the private sector over the past two decades. Then, we conduct an in-depth analysis of the account books of leading railway
and bus operators in Hong Kong so as to shed light on their financial viability. Through this study, we hope to present crucial
factors for providing financially viable private transit services. 相似文献
167.
The propagation of fatigue cracks under constant amplitude cyclic loading was studied in welded stiffened steel plates. The residual stresses in the stiffened plates were measured using the neutron diffraction strain-scanning technique. A finite element model of the stiffened plate was constructed to simulate the residual stresses by an uncoupled thermal and thermo-mechanical analysis. Both the finite element model and the neutron diffraction measurements indicated that in general the residual stresses were tensile near the welded stiffeners and compressive between the stiffeners and ahead of the starter notch tip. Fatigue testing indicated that the fatigue crack growth rates of the stiffened plates were in general lower than that of a corresponding unstiffened plate, especially near the notch tip where compressive residual stresses existed. Both the finite element method and Green's function predicted the fatigue crack growth rates with reasonable accuracy. 相似文献
168.
This paper examines the economic impact of the code-sharing agreement between ATA and Southwest Airlines, the first time Southwest has chosen to enter markets via a code-share alliance rather than direct entry. We examine the impact of complementary code-sharing on incumbent airline's fares and passenger volumes and also the overall impact on consumer welfare in Denver airline markets. Empirical results show that air fares decreased and passenger volumes increased for incumbent carriers operating on code-shared routes. Further, we find evidence that this code-sharing arrangement increased both consumer and producer surplus. Thus, the well-known “Southwest Effect” is observed not only when Southwest enters a route directly, but also when it enters a route via a code-share agreement with another airline. 相似文献
169.
B. Supriyo K. B. Tawi H. Jamaluddin 《International Journal of Automotive Technology》2013,14(2):313-323
This paper introduces an electro-mechanical, dual acting pulley, continuously variable transmission (EMDAPCVT) and presents its real time ratio controller using a proportional-derivative-plus-conditional-integral (PDPCI) controller. The ratio controller system is developed based on primary (input) and secondary (output) pulley position controllers. Each position controller has two PID parameters, releasing and clamping, which are determined experimentally using a relay feedback method. A PC-based ratio controller system is implemented using Matlab/Simulink® software and a Keithley DAS-1602 data acquisition system card. The experimental results show that the PDPCI controller system can control the CVT ratio adequately. 相似文献
170.