Results 1 - 10 of 15076
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[en] Conditions corresponding to more uniform motion of the linear and angular coordinates of a precision jig-boring machine with digital positional servo drives are outlined. Uniform coordinate motion, especially at low supply speeds, is extremely important for high-precision measuring operations and also in finishing. The effectiveness of the proposals is demonstrated in simulation.
[en] We used microparticles under hypergravity conditions, induced by a centrifuge, in order to measure nonintrusively and spatially resolved the electric field strength as well as the particle charge in the collisional rf plasma sheath. The measured electric field strengths demonstrate good agreement with the literature, while the particle charge shows decreasing values towards the electrode. We demonstrate that it is indeed possible to measure these important quantities without changing or disturbing the plasma.
[en] Model for ringing-out rotors with arbitrary profile of wall with or without covers is proposed to determine rotor flexure frequencies. The method for increasing the first flexure frequency of rotor and its optimization by means of centrifuge rotor wall profiling is demonstrated
[ru]Для быстрого определения изгибных частот роторов предложена модель для прозвонки роторов с произвольным профилем стенки с крышками или без них. Продемонстрирован способ повышения первой изгибной частоты ротора и ее оптимизации за счет профилирования стенки ротора центрифуги
[en] Distributed Hybrid Testing (DHT) is an experimental technique designed to capitalise on advances in modern networking infrastructure to overcome traditional laboratory capacity limitations. By coupling the heterogeneous test apparatus and computational resources of geographically distributed laboratories, DHT provides the means to take on complex, multi-disciplinary challenges with new forms of communication and collaboration. To introduce the opportunity and practicability afforded by DHT, here an exemplar multi-site test is addressed in which a dedicated fibre network and suite of custom software is used to connect the geotechnical centrifuge at the University of Cambridge with a variety of structural dynamics loading apparatus at the University of Oxford and the University of Bristol. While centrifuge time-scaling prevents real-time rates of loading in this test, such experiments may be used to gain valuable insights into physical phenomena, test procedure and accuracy. These and other related experiments have led to the development of the real-time DHT technique and the creation of a flexible framework that aims to facilitate future distributed tests within the UK and beyond. As a further example, a real-time DHT experiment between structural labs using this framework for testing across the Internet is also presented.
[en] The design characteristic of the autocontrol technique of the combined centrifuge is introduced. Digital technique, vary structure control and interface technique, graphical display techniques, digital communication technique as well as electronic technique are applied in the course of research. Automation in the operation of large scale combined centrifuges and the course of combined test has been realized and it can coordinate with other systems of status monitoring, data collecting and centrifugal force-aerodynamic force matched load automatically
[en] Transfer coefficients have become virtually indispensible in the study of the fate of radioisotopes released from nuclear installations. These coefficients are used in equilibrium assessment models where they specify the degree of transfer in food chains of individual radioisotopes from soil to plant products and from feed or forage and drinking water to animal products and ultimately to man. Information on transfer coefficients for terrestrial food chain models is very piecemeal and occurs in a wide variety of journals and reports. To enable us to choose or determine suitable values for assessments, we have addressed the following aspects of transfer coefficients on a very broad scale: (1) definitions, (2) equilibrium assumption, which stipulates that transfer coefficients be restricted to equilibrium or steady rate conditions, (3) assumption of linearity, that is the idea that radioisotope concentrations in food products increase linearly with contamination levels in the soil or animal feed, (4) methods of determination, (5) variability, (6) generic versus site-specific values, (7) statistical aspects, (8) use, (9) sources of currently used values, (10) criteria for revising values, (11) establishment and maintenance of files on transfer coefficients, and (12) future developments. (auth)
[en] The NKS project FOREST was established to prepare a guide for sampling in forest ecosystems for radionuclide analysis. The aim of this guide is to improve the reliability of datasets generated in future studies by promoting the use of consistent, recommended practices, thorough documentation of field sampling regimes and robust preparation of samples from the forest ecosystem. The guide covers general aims of sampling, the description of major compartments of the forest ecosystem and outlines key factors to consider when planning sampling campaigns for radioecological field studies in forests. Recommended and known sampling methods for various sample types are also compiled and presented. The guide focuses on sampling practices that are applicable in various types of boreal forests, robust descriptions of sampling sites, and documentation of the origin and details of individual samples. The guide is intended for scientists, students, forestry experts and technicians who appreciate the need to use sound sampling procedures in forest radioecological projects. The guide will hopefully encourage readers to participate in field studies and sampling campaigns, using robust techniques, thereby fostering competence in sampling. (au)
[en] An interactive code, FOOD, has been written in BASIC for the UNIVAC 1108 to facilitate calculation of internal radiation doses to man from radionuclides in food products. In the dose model, vegetation may be contaminated by either air or irrigation water containing radionuclides. The model considers two mechanisms for radionuclide contamination of vegetation: direct deposition on leaves and uptake from soil through the root system. The user may select up to 14 food categories with corresponding consumption rates, growing periods and either irrigation rates or atmospheric deposition rates. These foods include various kinds of produce, grains and animal products. At present, doses may be calculated for the skin, total body and five internal organs from 190 radionuclides. Dose summaries can be displayed at the local terminal. Further details on percent contribution to dose by nuclide and by food type are available from an auxiliary high-speed printer. This output also includes estimated radionuclide concentrations in soil, plants and animal products
[en] In the analysis of the consequences of radioactive fallout, one of the main sources of concern is the contamination of the food chain. The results obtained in investigations on the transport of radioactive contaminants from soil to plants are often used as input parameters in long term evaluations and dose assessments. However, the data obtained under experimental conditions may be of little relevance in actual fallout situations. The paper discusses the differences between the transfer factors that can be used with arable and pasture lands. An example shows how experimental data can be used to evaluate the nuclide fraction transferred to human consumption through wheat grain. The accumulated nuclide fraction, as calculated from experimental transfer data for five different nuclides, indicates which nuclides give the main dose contributions. (author). 18 refs, 1 fig., 1 tab
[en] These studies were made in 1976 and 1977 by the Aix Geographical Institute (Aix-Marseille II University), then in 1978 by the B.E.G.E.A. under the scientific control of the Institute. Their subject concerns the food consumption of local populations for the subsequent determination of radioactive contamination levels. They make an inventory of the various local agricultural, animal rearing and fishing productions and determine the part they represent in the diet of the populations living near the sites
[fr]Ces etudes ont ete realisees en 1976 et 1977 par l'institut de geographie d'Aix (Universite d'Aix-Marseille II), puis en 1978 par le B.E.G.E.A., sous le controle scientifique de l'Institut. Leur theme concerne la consommation alimentaire des populations locales en vue de la determination ulterieure des niveaux de contamination radioactive. Elles recensent les differentes productions de l'agriculture, de l'elevage, ou de la peche locale et determinent la part qu'elles representent dans le regime alimentaire des populations residant aux abords des sites