12,679 research outputs found
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Evidence of convection as a major source of condensation nuclei in the northern midlatitude upper troposphere
In loco intellegentia: Human factors for the future European train driver
The European Rail Traffic Management System (ERTMS) represents a step change in technology for rail operations in Europe. It comprises track-to-train communications and intelligent on-board systems providing an unprecedented degree of support to the train driver. ERTMS is designed to improve safety, capacity and performance, as well as facilitating interoperability across the European rail network. In many ways, particularly from the human factors perspective, ERTMS has parallels with automation concepts in the aviation and automotive industries. Lessons learned from both these industries are that such a technology raises a number of human factors issues associated with train driving and operations. The interaction amongst intelligent agents throughout the system must be effectively coordinated to ensure that the strategic benefits of ERTMS are realised. This paper discusses the psychology behind some of these key issues, such as Mental Workload (MWL), interface design, user information requirements, transitions and migration and communications. Relevant experience in aviation and vehicle automation is drawn upon to give an overview of the human factors challenges facing the UK rail industry in implementing ERTMS technology. By anticipating and defining these challenges before the technology is implemented, it is hoped that a proactive and structured programme of research can be planned to meet them
Building theories from case study research: the progressive case study
Meredith (1998) argues for more case and field research studies in the field of operations\ud
management. Based on a literature review, we discuss several existing approaches to case\ud
studies and their characteristics. These approaches include; the Grounded Theory approach\ud
which proposes no prior literature review in the substantive area under study (Glaser, 1992:\ud
31) versus Eisenhardt (1989) and Yin (1994) who propose a more directed study with a priori\ud
constructs. We then propose an alternative approach which we call the progressive case\ud
study. This approach combines strengths of both approaches such as the informative aspect of\ud
Grounded Theory and a more plan able approach such as Yin and Eisenhardt propose. We\ud
also describe that case studies are not simply a set of interviews and provide examples on the\ud
amount of data that might be collected in a detailed case study. Furthermore, we provide\ud
direction for analyzing qualitative data in cases
Factors influencing impala distribution patterns in Nairobi National Park, Kenya
Monitoring the distribution of wild animals using appropriate methods and survey techniques is essential not only for sustainable management but also to avoid wastage of resources. This study applied remote sensing to investigate the factors influencing the distribution of herbivores in Nairobi National Park, Kenya. Impala was selected as indicator specie for the herbivores within the park, because the population of impala had drastically reduced over time. The influence of food availability, water and disturbance on herbivore presence was investigated. A positive significant statistical relationship between impala population density and feed availability was observed. However, the correlation between impala population density and water distance was negative, indicating less impalas as the distance from water sources increase. An interesting finding was the expectation of greater impala population presence next to roads. The study demonstrated a rapid method for gaining information useful for conservation and land use planning practices, such as in the determination of the carrying capacity or even for redistributing animals within the park
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Biomass burning emisison inventory with daily resolution: Application to aircraft observations of Asian outflow
We develop a daily-resolved global emission inventory for biomass burning using AVHRR satellite observations of fire activity corrected for data gaps and scan angle biases. We implemented this inventory in a global three-dimensional model (GEOSCHEM) to simulate aircraft CO observations during the TRACE-P mission over the NW Pacific in February-April 2001. Seasonal biomass burning in SE Asia was a major contributor to the outflow of Asian pollution observed in TRACE-P and shows large day-to-day fluctuations that vary depending on location. Three simulations were conducted with the same 3-month total (February-April) emissions but different temporal distributions: 2001 daily resolved, 2001 monthly resolved, and climatological monthly resolved. The effect of daily resolved versus monthly resolved 2001 emissions in the simulation of CO is less than 8 ppbv in Asian outflow over the NW Pacific but can exceed 100 ppbv over source regions. The relatively small effect in Asian outflow reflects spatial and temporal averaging of emissions during ageing in the continental boundary layer. Significant improvement in the simulation of TRACE-P observations (as diagnosed by the resolved variance) is found when using 2001 monthly versus climatological monthly emissions, but using 2001 daily emissions does not offer further improvement. Copyright 2003 by the American Geophysical Union
Nonmethane hydrocarbon measurements in the North Atlantic Flight Corridor during the Subsonic Assessment Ozone and Nitrogen Oxide Experiment
Mixing ratios of nonmethane hydrocarbons (NMHCs) were not enhanced in whole air samples collected within the North Atlantic Flight Corridor (NAFC) during the fall of 1997. The investigation was conducted aboard NASA's DC-8 research aircraft, as part of the Subsonic Assessment (SASS) Ozone and Nitrogen Oxide Experiment (SONEX). NMHC enhancements were not detected within the general organized tracking system of the NAFC, nor during two tail chases of the DC-8's own exhaust. Because positive evidence of aircraft emissions was demonstrated by enhancements in both nitrogen oxides and condensation nuclei during SONEX, the NMHC results suggest that the commercial air traffic fleet operating in the North Atlantic region does not contribute at all or contributes negligibly to NMHCs in the NAFC. Copyright 2000 by the American Geophysical Union
Acoustical barriers in classrooms: the impact of noise on performance in the classroom
There is general concern about the levels of noise that children are exposed to in classroom situations. We report the results of a study that explores the effects of typical classroom noise on the performance of primary school children on a series of literacy and speed tasks. One hundred and fifty eight children in six Year 3 classes participated in the study. Classes were randomly assigned to one of three noise conditions. Two noise conditions were chosen to reflect levels of exposure experienced in urban classrooms (Shield & Dockrell, 2004): noise by children alone, that is classroom–babble, and babble plus environmental noise, babble and environmental. Performance in these conditions was compared with performance under typical quiet classroom conditions or base. All analyses controlled for ability. A differential negative effect of noise source on type of task was observed. Children in the babble and environmental noise performed significantly worse than those in the base and babble conditions on speed of processing tasks. In contrast, performance on the verbal tasks was significantly worse only in the babble condition. Children with special educational needs were differentially negatively affected in the babble condition. The processes underlying these effects are considered and the implications of the results for children’s attainments and classroom noise levels are explored
SHOP2: An HTN Planning System
The SHOP2 planning system received one of the awards for distinguished
performance in the 2002 International Planning Competition. This paper
describes the features of SHOP2 which enabled it to excel in the competition,
especially those aspects of SHOP2 that deal with temporal and metric planning
domains
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