63,423 research outputs found
Development of the all-welded common bulkhead fifth monthly progress report, 1 - 30 nov. 1964
Comparison of tungsten and molybdenum inert gas welded joint
Why Newton's gravity is practically reliable in the large-scale cosmological simulations
Until now, it has been common to use Newton's gravity to study the non-linear
clustering properties of the large-scale structures. Without confirmation from
Einstein's theory, however, it has been unclear whether we can rely on the
analysis, for example, near the horizon scale. In this work we will provide a
confirmation of using Newton's gravity in cosmology based on relativistic
analysis of weakly non-linear situations to the third order in perturbations.
We will show that, except for the gravitational wave contribution, the
relativistic zero-pressure fluid equations perturbed to the second order in a
flat Friedmann background coincide exactly with the Newtonian results. We will
also present the pure relativistic correction terms appearing in the third
order. The third-order correction terms show that these are the linear-order
curvature perturbation strength higher than the second-order
relativistic/Newtonian terms. Thus, the pure general relativistic corrections
in the third order are independent of the horizon scale and are small in the
large-scale due to the low-level temperature anisotropy of the cosmic microwave
background radiation. Since we include the cosmological constant, our results
are relevant to currently favoured cosmology. As we prove that the Newtonian
hydrodynamic equations are valid in all cosmological scales to the second
order, and that the third-order correction terms are small, our result has a
practically important implication that one can now use the large-scale
Newtonian numerical simulation more reliably as the simulation scale approaches
and even goes beyond the horizon.Comment: 8 pages, no figur
Associations between health and different types of environmental incivility : a Scotland-wide study
Objectives: Concern about the impact of the environment on health and well being has tended to focuson the physical effects of exposure to toxic and infectious substances, and on the impact of large scale infrastructures. Less attention has been paid to the possible psychosocial consequences of people's subjective perceptions of their everyday, street level environment, such as the incidence of litter and graffiti. As little is known about the potential relative importance for health of perceptions of different types of environmental incivility, a module was developed for inclusion in the 2004 Scottish Social Attitudes survey in order to investigate this relationship. Study design: A random sample of 1637 adults living across a range of neighbourhoods throughout Scotland was interviewed. Methods: Respondents were asked to rate their local area on a range of possible environmental incivilities. These incivilities were subsequently grouped into three domains: (i) street level incivilities (e.g. litter, graffiti); (ii) large scale infrastructural incivilities (e.g. telephone masts); and (iii) the absence of environmental goods (e.g. safe play areas for children). For each of the three domains, the authors examined the degree to which they were thought to pose a problem locally, and how far these perceptions varied between those living in deprived areas and those living in less deprived areas. Subsequently, the relationships between these perceptions and self assessed health and health behaviours were explored, after controlling for gender, age and social class. Results: Respondents with the highest levels of perceived street level incivilities were almost twice aslikely as those who perceived the lowest levels of street level incivilities to report frequent feelings of anxiety and depression. Perceived absence of environmental goods was associated with increased anxiety (2.5 times more likely) and depression (90% more likely), and a 50% increased likelihood of being a smoker. Few associations with health were observed for perceptions of large scale infrastructural incivilities. Conclusions: Environmental policy needs to give more priority to reducing the incidence of street levelincivilities and the absence of environmental goods, both of which appear to be more important for health than perceptions of large scale infrastructural incivilities
Evaluation of the metabolic cost of locomotion in an Apollo space suit
Evaluation of metabolic cost of locomotion in Apollo space sui
Wake in faint television meteors
The two component dustball model was used in numerical lag computation. Detached grain lag is typically less than 2 km, with expected wakes of a few hundred meters. True wake in television meteors is masked by apparent wake due to the combined effects of image persistence and blooming. To partially circumvent this problem, we modified a dual MCP intensified CID video system by addition of a rotating shutter to reduce the effective exposure time to about 2.0 ms. Preliminary observations showed that only 2 of 27 analyzed meteors displayed statistically significant wake
Expert system verification concerns in an operations environment
The Space Shuttle community is currently developing a number of knowledge-based tools, primarily expert systems, to support Space Shuttle operations. It is proposed that anticipating and responding to the requirements of the operations environment will contribute to a rapid and smooth transition of expert systems from development to operations, and that the requirements for verification are critical to this transition. The paper identifies the requirements of expert systems to be used for flight planning and support and compares them to those of existing procedural software used for flight planning and support. It then explores software engineering concepts and methodology that can be used to satisfy these requirements, to aid the transition from development to operations and to support the operations environment during the lifetime of expert systems. Many of these are similar to those used for procedural hardware
Development of the all-welded common bulkhead monthly report, 1 - 31 jan. 1965
Manufacturing concepts for welding bulkheads from honeycomb sandwich segments for Saturn V upper stage
Show or tell? Opportunities, problems and methods of the exhibition as a form of research dissemination
There has a been a good deal of debate about the possible use of exhibitions in disseminating research, as an alternative to conventional text papers where artefacts have a significant role in the research The European Academy of Design has been a pioneer in this area but, so far, there has been little documentation of this practice or constructive reflection to support future development.
The authors were responsible for the organisation of an exhibition of research work at the 2002 "Common Ground" Conference of the Design Research Society. Their role included mentoring the exhibitors, making the practical arrangements for the exhibition and organising refereeing of exhibits by an international panel of referees. The exhibition demonstrated the potential for new forms of research dissemination but also highlighted a number of problems and issues which must be dealt with if future exhibitions are to provide a robust and appropriate way to present and record research outcomes.
The reflections of the organisers, and comments of referees and exhibitors are employed in this paper to develop guidelines for future practice in research exhibitions, paying particular attention to the importance of providing a full narrative within the exhibit and a permanent record, and ways that exhibitions might change the format of conferences to allow more constructive engagement between participants. </p
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