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361.
In recent years, the work in engine control rooms (ECRs) onboard ships is becoming increasingly demanding and complex due to growing presence of modern information technology (IT) applications introduced in a problem-patching fashion. Previous studies about ECRs discussed the design issues associated with physical and cognitive ergonomics and lack of regulatory support. This paper has re-examined a design case in an ECR on a merchant ship and discussed the potential of a service-oriented architectural approach to manage emerging unruly technologies and integrate distributed resources in the maritime human-technology system. An EU project was introduced to illustrate the value of this design approach. Confronted with the complexity issues residing in a sociotechnical system like the ECR, this conceptual paper suggests a shift of focus from patching individual problems locally to a holistic systems perspective on the maritime eco-system development, which would likely require more collaborative efforts of various maritime stakeholders in practice. Certain extent of mandatory standardization for deploying and managing information systems is considered to be critical in these collaborative endeavors.  相似文献   
362.
For educational and/or training purposes, games are often described as multimodal texts, where signs, gestures, images, habits, behaviors, sounds, etc. have different meanings according to the way and the context they are represented. During their execution, a large variety of strategies can be employed; images, words, sounds, music, movement, and even bodily sensations can provide the necessary factors. More importantly, when games are integrated in an educational (or training) activity, it is essential to record solid evidence that the targeted learning outcome is achieved. Game-based learning (GBL) for seafarers is a multifactor domain combining educational psychology, learning theories, instructional design, computer game technology, and last but not least, research in the maritime field. In order to create the appropriate framework, there is a need to combine three different scientific areas (education design, computer science, and maritime education and training (MET)) towards the proper game design. In these types of games, the design process includes an extremely important task: embedding suitable educational approaches and instructional techniques for specific learning outcomes and student profiles into the scenario, so that the game will be played without losing the fun and attractive part of it. In the current analysis, a framework for GBL that is applicable for 200 maritime professionals is presented; the specific application is related to navigational safety training, and the respective framework is a 3D real-time strategy game called “Trader of the World” (TotW-alpha version). The game is designed for already competent adult seafarers as well as undergraduate students of maritime academies/institutions and it is applied in nonformal educational settings. A demonstration of this game has already taken place at the undergraduate level; results, evaluations, and opinions provided by the participants were used as the basis for discussion.  相似文献   
363.
Most analyses of marine microbial systems in the seasonally ice covered areas of the Southern Ocean have been based on data from the major embayment areas of the Ross and Weddell Seas. In this study data were collected at stations covering a range of regimes from full ice cover through to open water in the Bellingshausen Sea. A major feature of the production system was a rapid retreat of the ice-edge, which uncoupled the marginal ice zone from a phytoplankton bloom which remained associated with a frontal system. This bloom was maintained, and probably initiated, in an unusual environment generated by the interaction between the marginal ice zone and the front. Size-based analyses of the microbial system were derived for ice-covered, recently ice-covered and open water sites. Estimates of standing stocks and key rate processes were combined to produce a single food web network for each station. The under-ice system was one of low production and low recycling but apparently high retention. As the ice retreated the microbial systems to the north began to develop, but these were constrained by grazing pressure. The bloom in the area appeared to be sustained even though estimated losses were far higher than production, although the high sedimentation losses expected were not observed. The carbon flow networks are discussed in relation to the environmental changes and the interaction of the marginal ice zone and the frontal system appears crucial to the phytoplankton. Microzooplankton grazing is implicated as a major controlling factor. The local microbial dynamics are strongly influenced by material which was produced at an earlier time and somewhere else in the Southern Ocean.  相似文献   
364.
In the present work, computational simulations was made using ANSYS CFX to predict the improvements in film cooling performance with dual trench. Dual-trench configuration consists of two trenches together, one wider trench and the other is narrow trench that extruded from the wider one. Several blowing ratios in the range (0.5:5) were investigated. The pitch-to-diameter ratio of 2.775 is used. By using the dual trench configuration, the coolant jet impacted the trench wall two times allowing increasing the spreading of coolant laterally in the trench, reducing jet velocity and jet completely covered on the surface. The results indicate that this configuration increased adiabatic effectiveness as blowing ratio increased. The spatially averaged adiabatic effectiveness reached 57.6% for at M= 2. No observed film blow-off at all blowing ratios. The adiabatic film effectiveness of dual trench case outperformed the narrow trench case, laidback fan-shaped hole, fan-shaped hole and cylinder hole at different blowing ratios.  相似文献   
365.
366.
Researchers and practitioners highlight the unreliability of travel as a potential weak link in the transportation system which may inhibit individuals’ accessibility and urban economic activity. With the trend towards increasing traffic congestion, the outlook suggests that travel conditions will become structurally less reliable over time, but that not all places will be equally affected. But is travel time unreliability a problem? This study uses global positioning systems travel survey data for Chicago to build a regional model of travel time unreliability. The results suggest that unreliability varies spatially during different time periods, but that the average overall network unreliability varies little across times in the day. Using the Chicago Metropolitan Agency for Planning (CMAP)’s 2007 Travel Tracker Survey, a household travel diary survey including both GPS and non-GPS components, we estimate a mode choice model for work trips to explore the influence of unreliability on travel behavior. The results suggest that unreliable auto travel conditions induce mode switching to transit and that the influence is strongest when service by train is already faster than by car. This further suggests that auto travel unreliability may have the strongest influence in metropolitan regions with highly-competitive transit systems. Nevertheless, the influence of travel unreliability is limited and is not the underlying driver of travel decision-making.  相似文献   
367.

One perspective on the allocation of transport investments by public authorities is offered by the so‐called ‘pork barrel’ model, whereby politicians and political parties allocate public investment spatially in such a way as to gain electoral support from localities so benefited. The paper introduces this model and discusses its attractions and problems in the case of the transport sector. A review of the modest number of published examples of this approach is offered before a detailed case study considers the case of railway investment in Nelson, New Zealand.  相似文献   
368.
Air quality modelling plays an important role in formulating air pollution control and management strategies by providing guidelines for better and more efficient air quality planning. Several line source models, mostly Gaussian‐based, have been suggested to predict pollutant concentrations near highways/roads. These models, despite several assumptions and limitations, are used throughout the world, including in India, to carry out air pollution prediction analysis due to vehicular traffic near roads/highways. These models are being continuously upgraded and modified based on field experiments, and numerical and physical modelling results. An effort has been made in the present paper to review briefly the philosophy and basic features of most of the commonly used highway dispersion models. The paper also discusses various theories and techniques that led to the development and modification of these models along with the statistical analysis tools to evaluate the performance of these models. An attempt has also been made to summarize briefly the various line source models currently used in India and to highlight the difficulties being faced while using them in an Indian context.  相似文献   
369.

This paper underlines the important role played by the interaction between transport and land use in the way cities develop and the need to use a fully integrated land‐use/transport model to assess the longer‐term impacts of urban policies. Since most of the models of this type had never been properly tested, the Transport and Road Research Laboratory in the early 1980s set up a collaborative study to examine critically their performance and to assess the impacts of a range of commonly applied policies.

The paper briefly describes the first phase of the study in which nine models from seven countries were subjected to a rigorous set of tests covering a variety of policies. For practical reasons each model was applied to the city on which it was originally calibrated. To overcome some of the problems of comparison, a second phase of the study was conducted in which some models were applied to several cities each so that the differences due to the particular characteristics of the cities could be identified. In carrying out this phase, some cities were examined by several models and discrepancies in the results analysed. The setting up of the second phase of the study is outlined in this paper, but not the results, which are given in later papers in this and subsequent issues of Transport Reviews.  相似文献   
370.
Methane release and coastal environment in the East Siberian Arctic shelf   总被引:1,自引:0,他引:1  
In this paper we present 2 years of data obtained during the late summer period (September 2003 and September 2004) for the East Siberian Arctic shelf (ESAS). According to our data, the surface layer of shelf water was supersaturated up to 2500% relative to the present average atmospheric methane content of 1.85 ppm, pointing to the rivers as a strong source of dissolved methane which comes from watersheds which are underlain with permafrost. Anomalously high concentrations (up to 154 nM or 4400% supersaturation) of dissolved methane in the bottom layer of shelf water at a few sites suggest that the bottom layer is somehow affected by near-bottom sources. The net flux of methane from this area of the East Siberian Arctic shelf can reach up to 13.7 × 104 g CH4 km− 2 from plume areas during the period of ice free water, and thus is in the upper range of the estimated global marine methane release. Ongoing environmental change might affect the methane marine cycle since significant changes in the thermal regime of bottom sediments within a few sites were registered. Correlation between calculated methane storage within the water column and both integrated salinity values (r = 0.61) and integrated values of dissolved inorganic carbon (DIC) (r = 0.62) suggest that higher concentrations of dissolved methane were mostly derived from the marine environment, likely due to in-situ production or release from decaying submarine gas hydrates deposits. The calculated late summer potential methane emissions tend to vary from year to year, reflecting most likely the effect of changing hydrological and meteorological conditions (temperature, wind) on the ESAS rather than riverine export of dissolved methane. We point out additional sources of methane in this region such as submarine taliks, ice complex retreat, submarine permafrost itself and decaying gas hydrates deposits.  相似文献   
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