26,040 research outputs found

    Normalisation of shear test data for rate-independent compressible fabrics

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    This article describes a method of using both picture frame (PF) and bias extension (BE) tests together to characterize accurately the trellis shearing resistance of engineering fabrics under low in-plane tension conditions. Automated image analysis software has been developed to reduce the amount of laborious manual analysis required to interpret BE data accurately. Normalization methods for both PF and BE tests on rate-independent compressible fabrics are presented. Normalization of PF test results is relatively straightforward while normalization of BE test results for direct comparison with PF data is more complicated. The normalization method uses a number of simple assumptions to account for the nonuniform shear strain field induced across BE samples during testing. Normalized results from BE tests on samples of different aspect ratios are compared and provide validation of the theory

    Static and dynamic aspects of an air gap capacitor

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    This paper deals with the theory of an air-gap capacitor used as a micromechanical resonator. Both static and dynamic aspects are discussed. A single-element approach for the electrostatic excitation and capacitive detection of the vibrational motion of the resonators is described. The non-linear character of the electrostatic force is accounted for in the static analysis. The behaviour of the air-gap capacitor is modelled as a lumped spring-mass system and its limitations are discussed. Also an equivalent electrical one-port network is derived, which can be used in a circuit simulation to account for the mechanical behaviour of the resonator. The results obtained from the spring-mass system are compared with the results obtained from a more elaborate numerical analysis of the air-gap capacitor. The lumped spring-mass system is adequate for modelling the air-gap capacitor

    Effects of alcohol on subjective ratings of prospective and everyday memory deficits

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    Background: Research has shown that heavy alcohol use has a detrimental effect on retrospective memory. Less is known about the effect of alcohol on everyday memory. Methods: This study examined self-ratings of two aspects of memory performance: prospective memory (for example, forgetting to pass on a message) and everyday memory (measured by cognitive failures, such as telling someone a joke that you have told them before). To ensure anonymity and expand on the numbers of participants used in previous studies, data were collected by using the Internet. Data from 763 participants remained after data screening. Results: After controlling for other drug and strategy use, there was clear evidence that differential use of alcohol was associated with impairments in the long-term aspect of prospective memory and with an increased number of cognitive failures. Conclusions: These results support and extend the findings of previous research: our findings are consistent with the idea that heavy use of alcohol does have a significant and negative effect on everyday cognitive performance. Possible causes of these impairments are discussed

    Self-rated everyday prospective memory abilities of cigarette smokers and non-smokers: a web based study

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    The present study examined self-ratings of two aspects of everyday memory performance: long-term prospective memory—measured by the prospective memory questionnaire (PMQ), and everyday memory—measured by the everyday memory questionnaire (EMQ). Use of other substances was also measured and used as covariates in the study. To ensure confidentiality and to expand the numbers used in previous studies, an Internet study was carried out and data from 763 participants was gathered. After controlling for other drug use and strategy use, the data from the PMQ revealed that smokers reported a greater number of long-term prospective memory errors than non-smokers. There were also differences between light and heavier smokers in long-term prospective memory, suggesting that nicotine may have a dose-dependent impact upon long-term prospective memory performance. There was also a significant ANOVA group effect on the EMQ, although the trend for more memory errors amongst the heavier smokers was statistically only borderline (p = .057). These findings suggest there are selective memory deficits associated with smoking and that long-term prospective memory deficits should be added to the growing list of problems associated with cigarette use

    Relaxation phenomena in CsCoCl3·2 H2O

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    Dynamic susceptibility measurements have been performed on a single crystal of CsCoCl3·2H2O at liquid temperatures by means of a Hartshorn mutual inductance bridge. At the magnetic phase transition a maximum in τabs(H) has been observed. A jump in τabs(T) has been found at the λ-point of liquid helium

    Efficient superfluorescent light sources with broad bandwidth

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    We demonstrate various efficient broad-band light sources at ~1µm wavelength with a 3dB bandwidth of up to 65nm at 108mW output power, based on rare-earth doped silica fibers and a simple adjustable spectral filter

    HIV/AIDS Contamination Risk, Savings and the Welfare Effects of Diagnostic Testing

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    This paper models the effect of a HIV/AIDS epidemic on saving behavior and studies the welfare effects of testing for HIV. The model specifies a utility function that includes both regular consumption, and medical expenditures. Medical expenditures generate more utility if individuals are HIV infected, but they are only able to purchase the optimal medical consumption after being tested HIV positive. The paper describes different effects on aggregate savings according to different stages of the epidemic. We show that the HIV epidemic decreases savings if especially young individuals are (perceived to be) affected by the virus, but may increase savings if individuals perceive a sizable probability of getting infected later in life. By the same token, the welfare effects of testing young individuals differs greatly from the welfare effects of testing older individuals, the reason being that the savings responses to testing differ according to whether old or young individuals are tested.saving behavior;perceived risk;HIV/AIDS;HIV testing;mortality;life-cycle model

    Retirement Flexibility and Portfolio Choice

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    This paper explores the interaction between retirement flexibility and portfolio choice in an overlapping-generations model. We analyse this interaction both in a partial-equilibrium and general-equilibrium setting. Retirement flexibility is often seen as a hedge against capital-market risks which justifies more risky asset portfolios. We show, however, that this positive relationship between risk taking and retirement fl exibility is weakened - and under some conditions even turned around - if not only capital-market risks but also productivity risks are considered. Productivity risk in combination with a high elasticity of substitution between consumption and leisure creates a positive correlation between asset returns and labour income, reducing the willingness of consumers to bear risk. Moreover, it turns out that general-equilibrium effects can either increase or decrease the equity exposure, depending on the degree of substitutability between consumption and leisure.retirement (in)fl exibility;portfolio allocation;risk;intratemporal substitution elasticity
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