629 research outputs found

    Investigation in optimisation of accuracy with non-contact systems by influencing variable processes

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    The use of 3D scanning systems is becoming increasingly popular and an essential tool for manufacturers for inspection and measurement. With such systems being utilised on the manufacturing shop floor due to their portability and ease of use, it is no doubt that such systems are designed to address a variety of users whom, with minimal training can operate the equipment. Due to continuing demands of high-quality products there is the need for manufacturers of 3D scanning systems to develop technologies that deliver fast and accurate information. However, one of the key challenges lies not in the training of people to use the equipment, but to develop engineers who can produce traceable, accurate and precise results with a declared statement of confidence quantifying the quality of the measurement. This statement of the quality of the output results relies on employing a set of workflow actions that involve planning, capture, processing and analysis, and finally output. This paper sets out to show how the results from a set of workflow actions from different categories of 3D scanning devices affects the quality of output

    Gravitational Waves from the Dynamical Bar Instability in a Rapidly Rotating Star

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    A rapidly rotating, axisymmetric star can be dynamically unstable to an m=2 "bar" mode that transforms the star from a disk shape to an elongated bar. The fate of such a bar-shaped star is uncertain. Some previous numerical studies indicate that the bar is short lived, lasting for only a few bar-rotation periods, while other studies suggest that the bar is relatively long lived. This paper contains the results of a numerical simulation of a rapidly rotating gamma=5/3 fluid star. The simulation shows that the bar shape is long lived: once the bar is established, the star retains this shape for more than 10 bar-rotation periods, through the end of the simulation. The results are consistent with the conjecture that a star will retain its bar shape indefinitely on a dynamical time scale, as long as its rotation rate exceeds the threshold for secular bar instability. The results are described in terms of a low density neutron star, but can be scaled to represent, for example, a burned-out stellar core that is prevented from complete collapse by centrifugal forces. Estimates for the gravitational-wave signal indicate that a dynamically unstable neutron star in our galaxy can be detected easily by the first generation of ground based gravitational-wave detectors. The signal for an unstable neutron star in the Virgo cluster might be seen by the planned advanced detectors. The Newtonian/quadrupole approximation is used throughout this work.Comment: Expanded version to be published in Phys. Rev. D: 13 pages, REVTeX, 13 figures, 9 TeX input file

    Effect of Nickel Administration in vivo on the Testicular Structure in Male Mice

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    The aim of this study was to describe the effects of nickel (NiCl2) on murine testicular structure. Experimental animals were injected intraperitoneally with a single dose of 20 mg NiCl2 per kg of body mass (group A, n = 5) and 40 mg NiCl2 per kg b. m. (group B, n = 5). The group without injection (n = 5) was the control (C). Animals were killed 48 hours after administration of nickel. The body mass of animals, the mass of testes and the testes : body mass ratio were not significantly affected. In both experimental groups a significant (p p p < 0.05 - 0.001) after nickel administration. Evaluation of the lumen diameter in the seminiferous tubule showed a significant increase in both experimental groups. The data of the perimeter of seminiferous tubules corresponded with those of the seminiferous tubule diameter. TUNEL assay detected a higher frequency of localized apoptosis in the interstitium of nickel-administered animals compared to control group. Our findings clearly suggest a negative effect of nickel on the structure as well as on the function of the seminferous epithelium at the site of spermatozoa production

    The cost of cooking a meal. The case of Nyeri County, Kenya

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    Energy for cooking is considered essential in achieving modern energy access. Despite this, almost three billion people worldwide still use solid fuels to meet their cooking needs. To better support practitioners and policy-makers, this paper presents a new model for comparing cooking solutions and its key output metric: the 'levelized cost of cooking a meal' (LCCM). The model is applied to compare several cooking solutions in the case study area of Nyeri County in Kenya. The cooking access targets are connected to the International Workshop Agreement and Global Tracking Framework's tiers of cooking energy access. Results show how an increased energy access with improved firewood and charcoal cookstoves could reduce both household's LCCMs and the total costs compared to traditional firewood cooking over the modelling period. On the other hand, switching to cleaner cooking solutions, such as LPG- and electricity, would result in higher costs for the end-user highlighting that this transition is not straightforward. The paper also contextualizes the results into the wider socio-economic context. It finds that a tradeoff is present between minimizing costs for households and meeting household priorities, thus maximizing the potential benefits of clean cooking without dismissing the use of biomass altogether
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