8,923 research outputs found

    Design knowledge capture for the space station

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    The benefits of design knowledge availability are identifiable and pervasive. The implementation of design knowledge capture and storage using current technology increases the probability for success, while providing for a degree of access compatibility with future applications. The space station design definition should be expanded to include design knowledge. Design knowledge should be captured. A critical timing relationship exists between the space station development program, and the implementation of this project

    An approach to design knowledge capture for the space station

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    The design of NASA's space station has begun. During the design cycle, and after activation of the space station, the reoccurring need will exist to access not only designs, but also deeper knowledge about the designs, which is only hinted in the design definition. Areas benefiting from this knowledge include training, fault management, and onboard automation. NASA's Artificial Intelligence Office at Johnson Space Center and The MITRE Corporation have conceptualized an approach for capture and storage of design knowledge

    Peer-group and price influence students drinking along with planned behaviour

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    This article is available open access through the publisher’s website at the link below. Copyright @ 2008 The Authors.Aims: To examine the theory of planned behaviour (TPB), as a framework for explaining binge drinking among young adults. Methods: One hundred and seventy-eight students in a cross-sectional design study completed self-report questionnaires examining attitudes to drinking, intention to drink and drinking behaviour in university. Binge drinking was defined for females (and males) as consuming ‘four (males—five) or more pints of beer/glasses of wine/measures of spirits’ in a single session. Results: Drinking alcohol was common; 39.6% of males and 35.9% of females reported binge drinking. The TPB explained 7% of the variance in intention to drink. Overall, 43% of the variance in intention, 83% of the variance in total weekly consumption and 44% of the variance in binge drinking was explained. The frequency of drinking and the drinking behaviour of friends significantly predicted intention to drink and binge drinking, respectively. Binge drinkers were influenced by peers and social-situational factors. Pressure to drink was greater for males; undergraduates were influenced by the size of the drinking group, ‘special offer’ prices, and the availability of alcohol. Conclusions: The TPB appeared to be a weak predictor of student drinking but this may be a result of how constructs were measured. With friends’ drinking behaviour emerging as a significant predictor of alcohol consumption, interventions seeking to reduce excessive drinking should target the role of peers and the university environment in which drinking occurs

    Considerations for a design and operations knowledge support system for Space Station Freedom

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    Engineering and operations of modern engineered systems depend critically upon detailed design and operations knowledge that is accurate and authoritative. A design and operations knowledge support system (DOKSS) is a modern computer-based information system providing knowledge about the creation, evolution, and growth of an engineered system. The purpose of a DOKSS is to provide convenient and effective access to this multifaceted information. The complexity of Space Station Freedom's (SSF's) systems, elements, interfaces, and organizations makes convenient access to design knowledge especially important, when compared to simpler systems. The life cycle length, being 30 or more years, adds a new dimension to space operations, maintenance, and evolution. Provided here is a review and discussion of design knowledge support systems to be delivered and operated as a critical part of the engineered system. A concept of a DOKSS for Space Station Freedom (SSF) is presented. This is followed by a detailed discussion of a DOKSS for the Lyndon B. Johnson Space Center and Work Package-2 portions of SSF

    Conservation Tillage, Pesticide Use, and Biotech Crops in the U.S.A.

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    This paper presents the first part of an ongoing project whose objective is to present a long term relationship between conservation tillage, adoption of GE crops and pesticide use for major crops in the United States. In addition, the project aims to provide some innovative tests on causality using a panel data set. This paper presents preliminary results for soybeans.conservation tillage, biotechnology, genetically engineered crops, soybeans, herbicides, Environmental Economics and Policy, Farm Management, Production Economics,

    Performance, lean meat proportion and behaviour of fattening pigs given a liquid diet at different animal/feeding-place ratios

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    Sensor feeding is a liquid feeding system for fattening pigs that is operated with a restricted animal/feeding-place ratio (AFR). The aim of the present study was to quantify the effect of three different AFRs (4:1, 7:1 and 13:1, calculated with a feeding space of 33 cm per animal) on the performance and behaviour of fattening pigs (mean initial weight 26·3 (s.d. 3·3) kg, live weight at slaughter 102 (s.d. 5) kg). The pigs were housed in groups of 40 and each AFR was tested with seven groups (21 groups in total). The daily weight gain of the individual pigs was calculated from the beginning of the experiments until slaughter. Additionally, the lean meat percentage was recorded (AutoFOM). Feeding behaviour was observed by means of 24-h video recording at the ages of 14 and 17 weeks with scan sampling every 5 min. The daily weight gain decreased with increasing AFR ( P<0·01) and females had lower weight gains than barrows ( P<0·001). The lean meat proportion was influenced by the AFR ( P<0·01) and sex of the pigs ( P<0·001). Proportions were highest with the AFR 13:1 and in females. The average number of pigs feeding simultaneously was highest for the AFR of 4:1 ( P<0·01). Moreover, the ingestion rate per day (kg/min) increased with increasing AFR ( P<0·05). The average number of pigs waiting behind other pigs feeding at the trough was highest with the AFR 13:1 ( P<0·001).In conclusion, growth performance and pig behaviour were negatively affected by an AFR of 13:1, which cannot be recommended for use with this feeding system. With an AFR of 4:1 lean meat values were lo

    The L_X--M relation of Clusters of Galaxies

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    We present a new measurement of the scaling relation between X-ray luminosity and total mass for 17,000 galaxy clusters in the maxBCG cluster sample. Stacking sub-samples within fixed ranges of optical richness, N_200, we measure the mean 0.1-2.4 keV X-ray luminosity, , from the ROSAT All-Sky Survey. The mean mass, , is measured from weak gravitational lensing of SDSS background galaxies (Johnston et al. 2007). For 9 <= N_200 < 200, the data are well fit by a power-law, /10^42 h^-2 erg/s = (12.6+1.4-1.3 (stat) +/- 1.6 (sys)) (/10^14 h^-1 M_sun)^1.65+/-0.13. The slope agrees to within 10% with previous estimates based on X-ray selected catalogs, implying that the covariance in L_X and N_200 at fixed halo mass is not large. The luminosity intercent is 30%, or 2\sigma, lower than determined from the X-ray flux-limited sample of Reiprich & Bohringer (2002), assuming hydrostatic equilibrium. This difference could arise from a combination of Malmquist bias and/or systematic error in hydrostatic mass estimates, both of which are expected. The intercept agrees with that derived by Stanek et al. (2006) using a model for the statistical correspondence between clusters and halos in a WMAP3 cosmology with power spectrum normalization sigma_8 = 0.85. Similar exercises applied to future data sets will allow constraints on the covariance among optical and hot gas properties of clusters at fixed mass.Comment: 5 pages, 1 figure, MNRAS accepte

    The Mean and Scatter of the Velocity Dispersion-Optical Richness Relation for maxBCG Galaxy Clusters

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    The distribution of galaxies in position and velocity around the centers of galaxy clusters encodes important information about cluster mass and structure. Using the maxBCG galaxy cluster catalog identified from imaging data obtained in the Sloan Digital Sky Survey, we study the BCG-galaxy velocity correlation function. By modeling its non-Gaussianity, we measure the mean and scatter in velocity dispersion at fixed richness. The mean velocity dispersion increases from 202+/-10 km/s for small groups to more than 854+/-102 km/s for large clusters. We show the scatter to be at most 40.5+/-3.5%, declining to 14.9+/-9.4% in the richest bins. We test our methods in the C4 cluster catalog, a spectroscopic cluster catalog produced from the Sloan Digital Sky Survey DR2 spectroscopic sample, and in mock galaxy catalogs constructed from N-body simulations. Our methods are robust, measuring the scatter to well within one-sigma of the true value, and the mean to within 10%, in the mock catalogs. By convolving the scatter in velocity dispersion at fixed richness with the observed richness space density function, we measure the velocity dispersion function of the maxBCG galaxy clusters. Although velocity dispersion and richness do not form a true mass-observable relation, the relationship between velocity dispersion and mass is theoretically well characterized and has low scatter. Thus our results provide a key link between theory and observations up to the velocity bias between dark matter and galaxies.Comment: 25 pages, 15 figures, 2 tables, published in Ap

    Assessing cubicle dimensions for finishing bulls based on animal behaviour and cleanliness

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    Finishing bulls need increasingly large cubicles throughout their growth, and optimal cubicle dimensions may differ from those used for dairy cows. The space requirements of finishing bulls was investigated by observing standing-up and lying-down behaviour, lying duration and number of lying bouts, as well as the cleanliness of cubicles and animals before and after increasing cubicle size at four different points in time. Lying area in the cubicles measured 120 × 70 cm at the start and 185 × 110 cm at the end of the finishing period (approx. at 160 and 550 kg, respectively). Twenty animals kept in four groups were observed at weights of approximately 220, 330, 380 and 500 kg before and after cubicle dimensions were increased. The proportion of standing-up events with more than one head lunge decreased with enlargement of the cubicles (P = 0·01). As cubicle size increased, bulls hit the partition rails less on standing up, except at 220 kg weight where the pattern was inverted (interaction: P = 0·001). Partitions were also hit less on lying down as cubicle size increased, except at 220 kg weight with an inverse pattern (interaction: P = 0·01). The number of exploratory head sweeps before lying down did not change with cubicle enlargement (P > 0·5). Bulls slipped more often with cubicle enlargement, except at 380 kg where the difference was inverted (interaction: P = 0·03). They never fell and never turned around in the cubicles. In general, both animals and cubicles were very clean. On average, lying duration decreased (P < 0·01) while the number of lying bouts tended to increase (P = 0·052) with enlargement of the cubicles but the absolute differences were small. Consequently at each point in time, the smaller cubicles still seemed to provide sufficient lying space for the bulls. If the impacts with the partitions were minor and did not represent a serious welfare concern, as suggested by qualitative observations, the cubicle dimensions used could be considered suitable for housing the type of finishing bulls used in this stud
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