32,235 research outputs found

    Expulsion bladder-equipped storage tank structure Patent

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    Expulsion bladder equipped storage tank structur

    The linear boom actuator designed for the Galileo spacecraft

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    Because the linear boom actuator is to be used on a flight spacecraft, as opposed to a ground based application, there is a comprehensive set of requirements. First, of course, the actuator must be capable of positioning and holding the load. Initially the load as predicted to be 4448 N (1000 lb) but with subsequent spacecraft configuration changes the load has been greatly reduced to a constant tensile pull of 1477 N (332 lb) due to centrifugal force. Lesser compressive loads of 1317 N (296 centrifugal lb) may be experienced during launch and deployment. This actuator must have the maximum redundancy possible. Life requirements were defined by the 10.16 to 15.24 cm (4 to 6 in.) total liner travel expected during the five-year flight duration. Liner range required of the actuator was set at plus and minus 5.08 cm to accommodate configuration changes

    Remotely operated gas-pressure regulator and shuttle valve

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    Valve features precise gas-pressure regulation and shuts off flow by remote control. Valve is made up of regulator valve cavity and spring-compression adjusts cavity. Elements in regulator cavity are conventional and include high-pressure inlet, ball which mates with seat, push rod, and pressure-sensing diaphragm

    Combined pressure regulator and shutoff valve

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    A remotely operable pressure regulator and shutoff valve particularly suited for achieving high resolution and flow control, and positive shutoff is described. The valve is characterized by a spring-loaded ball coaxially aligned with a fluid port to be sealed, a spring-loaded pintle extended through the port into engagement with the ball, for controlling the position, a spring-loaded diaphragm for controlling the position of the pintle, and an axially displaceable spring supported by a movable stop which, in turn, is repositioned by a selectively operable stepper motor. Thus, the pressure-response characteristics for the valve can be varied through a selective repositioning of the stop

    Love and Addiction: The Importance of Commitment

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    The bilaterally monopolistic nature of relationships between part- ners, combined with the addictive nature of love, which represents the emotion people feel during the course of a relationship, results in love growth when re- lationships are based on commitment. However, in relationships with less than perfect commitment, love will wither, and potentially die. In this paper, the path of love through a relationship is examined under the assumption that love is addictive and that partners may or may not be able to commit to a relationship. The differences in the results suggest that cohabiting partners may, by their very lack of commitment at the outset, be unsuited to successful marriages.Addiction, Commitment

    The Aid and Maid System: South African Household Data Pitfalls

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    This paper presents research on South African household expenditure share behaviour. The research examines whether or not a theoretical and empirical model, which has been successful in explaining expenditure shares in Australia, is valid when applied to South African data. The primary conclusion of the research is that expenditure shares in South Africa do not conform to the assumptions set out in the model. Although there are many potential reasons for non-conformity, this paper provides evidence that the estimates produced within the AID System and the MAID System suffer from heteroskedasticity and non-normality. Therefore, in order to improve the understanding of spending behaviour by South African households, models will have to be specifically developed to deal with the idiosyncrasies of South African data.

    Can Effects of Dark Matter be Explained by the Turbulent Flow of Spacetime?

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    For the past forty years the search for dark matter has been one of the primary foci of astrophysics, although there has yet to be any direct evidence for its existence (Porter et al. 2011). Indirect evidence for the existence of dark matter is largely rooted in the rotational speeds of stars within their host galaxies, where, instead of having a ~ r^1/2 radial dependence, stars appear to have orbital speeds independent of their distance from the galactic center, which led to proposed existence of dark matter (Porter et al. 2011; Peebles 1993). We propose an alternate explanation for the observed stellar motions within galaxies, combining the standard treatment of a fluid-like spacetime with the possibility of a "bulk flow" of mass through the Universe. The differential "flow" of spacetime could generate vorticies capable of providing the "perceived" rotational speeds in excess of those predicted by Newtonian mechanics. Although a more detailed analysis of our theory is forthcoming, we find a crude "order of magnitude" calculation can explain this phenomena. We also find that this can be used to explain the graviational lensing observed around globular clusters like "Bullet Cluster".Comment: 5 pages, Accepted for publication in Journal of Modern Physics: Gravitation and Cosmology (Sept. 2012

    Subcritical Lp bounds on spectral clusters for Lipschitz metrics

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    We establish asymptotic bounds on the L^p norms of spectrally localized functions in the case of two-dimensional Dirichlet forms with coefficients of Lipschitz regularity. These bounds are new for the range p>6. A key step in the proof is bounding the rate at which energy spreads for solutions to hyperbolic equations with Lipschitz coefficients.Comment: 10 page

    Contingent Valuation of Community Forestry Programs in Ethiopia: Observing Preference Anomalies in Double-Bounded CVM

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    This study examines the potential for anomalous response behaviour effects within the context of double-bounded contingent valuation methods applied to community forestry programs in rural Ethiopia. Anomalous responses considered include shift effects, framing effects and anchoring effects, and these effects are considered within a double-bounded contingent valuation study. The results confirmed the presence of incentive incompatibility and framing effects. However, anchoring effects are not uncovered. After controlling for these biases, the community forestry program considered is shown to offer a welfare gain ranging from Ethiopian Birr (ETB) 20.14 to 22.80. In addition to these welfare benefits, the results raise questions with respect to the validity of previous welfare estimates associated with double-bounded CVM studies in developing countries, suggesting that future studies should control for incentive incompatibility and framing effects bias.Double-bounded CVM, incentive incompatibility bias, anchoring bias

    Does One Size Fit All? Heterogeneity in the Valuation of Community Forestry Programs?

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    Through the implementation of a choice experiment valuation exercise, this study set out to identify the set of community plantation attributes that impact the welfare of potential community forestry program participants. We employed a combination of choice models to evaluate the preferences, welfare impacts and choice elasticities associated with alternative community forestry programs, allowing for different assumptions regarding heterogeneity. In line with economic theory, increased participation costs reduced the demand for community forestry, while increases in expected productivity raised the demand. With respect to preferences for the other alternatives considered - type of forest, area enclosure and type of land upon which the forest was to be situated - the results point to significant differences in preferences across the study population, suggesting that programs should be tailored to the communities in which the program is to be implemented.community forestry, choice experiment, conditional logit, random parameters logit and latent class model
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