547 research outputs found

    Electrical and optical properties of fluid iron from compressed to expanded regime

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    Using quantum molecular dynamics simulations, we show that the electrical and optical properties of fluid iron change drastically from compressed to expanded regime. The simulation results reproduce the main trends of the electrical resistivity along isochores and are found to be in good agreement with experimental data. The transition of expanded fluid iron into a nonmetallic state takes place close to the density at which the constant volume derivative of the electrical resistivity on internal energy becomes negative. The study of the optical conductivity, absorption coefficient, and Rosseland mean opacity shows that, quantum molecular dynamics combined with the Kubo-Greenwood formulation provides a powerful tool to calculate and benchmark the electrical and optical properties of iron from expanded fluid to warm dense region

    A Natural Language Model of Computing with Words in Web Pages

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    PACLIC 20 / Wuhan, China / 1-3 November, 200

    A refined numerical investigation of a large equivalent shallow-depth underwater explosion

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    The large equivalent shallow-depth explosion problem is very significant in the field of naval architecture and ocean engineering, as such explosions can be used to attack and demolish ships and anti-ship missiles. In the current work, a refined numerical study of the flow-field characteristics of a large equivalent shallow-depth explosion is carried out using a self-developed Eulerian finite element solver. Firstly, the numerical model is validated against theoretical results and a small equivalent explosion test in a tank. The numerical results are found to agree well with the theoretical and experimental results. In the next step, the cavitation cut-off effect is added to the underwater explosion model, and the cavitation phenomenon is quantitatively analyzed through the flow-field pressure. In addition, the dynamic characteristics of the bubble and water hump under various initial conditions for different stand-off parameters are analyzed. The effect of gravity on these physical processes is also discussed. The bubble pulsation period, taking into account the free surface effect, is then quantitatively studied and compared with Cole's experimental formula for an underwater explosion. Overall, when the stand-off parameter > 2, the influence of the free surface on the empirical period of the bubble is not significant. Our investigation provides broad insights into shallow-depth underwater explosions from theoretical, experimental, and numerical perspectives

    Design and Distortion Analysis of Passive Sensor Probes for the Measurements in Electric Fields

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    The sensor probes deployed in the electric fields will cause the distortion in the vicinities, therefore it may significantly affect the accuracy of the measurements in the electric fields. In this paper, we propose a novel approach to separate the electric field distortion due to the spherical sensor probes in a uniform electric field. Moreover, we also investigate the impacts of the spherical sensor probes to the original electric field distortion in terms of the size of sensor probes, the electrode materials, the coupling between the polar electrodes in the design of sensor probes. Our simulation results show that a passive electric field sensor system with the bands from 5 Hz to 200 kHz, and a 20 nF capacitance, combining with our new electric field distortion correction scheme, can surprise meet the requirements of the practical engineering. Moreover, our simulation results also show that the electric field sensor probe system we suggested only has 0.16 % nonlinear errors compared with the corresponding original system measurements. We hope our work will stimulate the future research in the design of the sensor probe systems for monitoring of the electric field
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