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31.
Transportation - Urban utility cycling is being promoted widely due to various health, social, economic and environmental benefits. This study seeks to identify and rank which municipal-level... 相似文献
32.
The quenching of a metal component with a channel section in a water tank is numerically simulated. Computational fluid dynamics
(CFD) is used to model the multiphase flow and the heat transfer in film boiling, nucleate boiling and convective cooling
processes to calculate the difference in heat transfer rate around the component and then combining with the thermal simulation
and structure analysis of the component to study the effect of heat transfer rate on the distortion of the U-channel component.
A model is also established to calculate the residual stress produced by quenching. The coupling fluid-thermal-structural
simulation provides an insight into the deformation of the component and can be used to perform parameter analysis to reduce
the distortion of the component. 相似文献
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34.
The effect of location,mobility and socio-demographic factors on task and time allocation of households 总被引:1,自引:0,他引:1
This paper investigates the role of location factors in task and time allocation at the household level. It is hypothesized
that, if time constraints are less binding as a result of living in an urban area or owning more cars, spouses engage more
often and longer in out-of-home activities and schedule their activities more independently. The hypotheses are tested with
logistic and Cox regression models of activity participation and time allocation on a data set collected in the Amsterdam–Utrecht
region in the Netherlands. Results suggest that the hypotheses are supported with respect to specific household activity scheduling
decisions. 相似文献
35.
This paper introduces a new method for the prediction of ship maneuvering capabilities. The new method is added to a nonlinear
six-degrees-of-freedom ship motion model named the digital, self-consistent ship experimental laboratory (DiSSEL). Based on
the first principles of physics, when the ship is steered, the additional surge and sway forces and the yaw moment from the
deflected rudder are computed. The rudder forces and moments are computed using rudder parameters such as the rudder area
and the local flow velocity at the rudder, which includes contributions from the ship velocity and the propeller slipstream.
The rudder forces and moments are added to the forces and moments on the hull, which are used to predict the motion of the
ship in DiSSEL. The resulting motions of the ship influence the inflow into the rudder and thereby influence the force and
moment on the rudder at each time step. The roll moment and resulting heel angle on the ship as it maneuvers are also predicted.
Calm water turning circle predictions are presented and correlated with model test data for NSWCCD model 5514, a pre-contract
DDG-51 hull form. Good correlations are shown for both the turning circle track and the heel angle of the model during the
turn. The prediction for a ship maneuvering in incident waves will be presented in Part 2. DiSSEL can be applied for any arbitrary
hull geometry. No empirical parameterization is used, except for the influence of the propeller slipstream on the rudder,
which is included using a flow acceleration factor. 相似文献
36.
Katie Hogg María Semitiel-García Pedro Noguera-Méndez Tim Gray Sarah Young 《Coastal management》2018,46(1):58-74
Many marine protected areas (MPAs) face a multitude of threats to the ecosystems that they have been established to conserve. This study is based on 111 interviews conducted in 2013–2014 designed to discover the perceptions of stakeholders about the threats, the causes of the threats, and their responses to the threats, to a well-established MPA – Cabo de Palos - Islas Hormigas (CPH-MPA). This MPA was created to safeguard fisheries and the associated artisanal fishers, but over time it has become a tourism “hotspot.” Resilience theory, which incorporates ecological resilience, social resilience, and individual resilience, helps us to analyze stakeholders' responses to threats by categorizing them into passive, adaptive, and transformative responses. We found respondents identified four main threats – over-fishing, excessive scuba diving, pollution, and invasive species; attributed the threats to three main causes – ineffective management, poor environmental stewardship, and climate change; and expressed three kinds of responses – do nothing, adapt, or transform – with a preference for adaptation and (especially) transformation. The lesson of this study is that it shows how, unless drastic action is taken to curb recreational diving activities, the CPH-MPA is in danger of changing from a fishing reserve to a largely unregulated leisure diving venue, which is unlikely to fulfill the requirements of resilience; ecological, social, or individual. 相似文献
37.
40多年前,Triumph TR5,Porsche 911和Alfa Romeo GTV纷纷使出自己的浑身解数,想在动力、天生的竞技综合能力以及人们所接受的1960年代车型风格等方面拔得头筹。如今,哪一台车值得装进你的车库中呢? 相似文献
38.
The mobile nature of soft coasts means that coastal communities face uncertainty in their property values and peace of mind when the existing coastal defense is lowered or removed. The acceptance by the U.K. government that coastal realignment in areas of low population density and limited ecological value is unavoidable means that the current state of affairs, where coastal residents have broadly come to assume that they will be defended if they make enough fuss, cannot continue. The government is currently unwilling to confront this consternation and continues to refuse to pay compensation for lost property value. This is creating an outcry over loss of fairness of treatment. This dispute raises important questions of governance for coastal change. This participatory research project worked closely with English Nature, North Norfolk District Council, local residents associations, the Environment Agency, and the Department for Environment, Food and Rural Affairs. What emerged in the analysis were unresolved tensions between national strategic frameworks, emerging planning arrangements, changing economic assessments, and the desirability of delivering, through a number of public and voluntary agencies, local flexibility in participation and in coastal design. This article reports on the research process, the challenges for coastal governance, and the scope for creative partnerships between science, planning, policy delivery, and public acceptance. 相似文献
39.
Safety in density (SID) potentially explains the safety in numbers (SIN) phenomenon by positing that ‘the SIN effect can be reproduced simply through encouraging behaviour that leads to the formation of higher-density cyclist groups’. The study further explores this hypothesis using event-based exposure, queues and groups of road users. Using three different definitions of encounters between road users, these were manually counted at signalized intersections, and their relationship to traffic volume was assessed. Based only on the frontmost motor vehicle in a queue and one cyclist among the several passing in front of that vehicle, the results show a less than linear relationship between meetings and traffic volume. An increase in the number of cyclists entails a general increase in cyclists passing in front of each motor vehicle, and an increase in motor vehicles increases queue lengths. However, crash data from the Swedish accident database (STRADA) show that it is exceedingly rare for multiple cyclists to be injured in the same crash. Together with results from a crash-encounter model, this suggests that the SID hypothesis may help to explain SIN 相似文献
40.
In many cities of the world, road space is increasingly contested. Growing vehicle numbers, traffic calming and the development of new infrastructure for more sustainable transport modes such as bicycles have all contributed to pressure on available space and conflicts over the allocation of space. This paper provides the first assessment of urban transport infrastructure space distribution, distinguishing motorized individual transport, public transport, cycling and walking. To calculate area allocation, an assessment methodology was developed using high-resolution digital satellite images in combination with a geographical information system to derive area measurements. This methodology was applied to four distinctly different city quarters in Freiburg, Germany. Results indicate that space is unevenly distributed, with motorized individual transport being the favoured transport mode. Findings also show that if trip number to space allocation ratios are calculated, one of the most sustainable transport modes, the bicycle, is the most disadvantaged. This suggests that area allocation deserves greater attention in the planning and implementation of more sustainable urban transport designs. 相似文献