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881.
J. Gregor I. Jakubova J. Senk 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,54(2):329-334
Using real experimentally obtained integral values, the paper deals with modelling of electric arc stabilised by flowing gas.
Attention is focused namely on approximate estimation of radiation coefficient of argon. A designed model of electric arc
burning in argon of atmospheric pressure inside arc heater’s anode channel is described. The model makes it possible to compute
axial and/or radial dependencies of some quantities of interest (temperature, velocity, electric field intensity, arc radius,
etc.), and subsequently to judge energy exchange between the arc and its surroundings. Sets of model’s input data, including
arc voltage, arc current, argon flow-rate, and flow-rates and temperatures of water cooling individual parts of the arc heater,
have been measured during numerous experiments. In a studied case with relatively high argon flow-rate, radiation has been
found to be prevailing mechanism of energy transfer from arc to anode channel walls. Based on this finding, techniques have
been designed for simple approximate estimation of radiation coefficient of argon in a limited extent of temperatures. As
an example, they have been tested on a particular set of measured and computed data. Argon radiation coefficient estimated
in this way has been compared with the results of theoretical computations carried out by other authors. Considering simplifications
used and differences between a real situation and an ideal theoretical model, agreement of the results is within satisfactory
limits. 相似文献
882.
Liao-fu Luo 《Frontiers of Physics in China》2009,4(1):122-136
The entropy production rate of cancer cells is always higher than healthy cells in the case where no external field is applied.
Different entropy production between two kinds of cells determines the direction of entropy flow among cells. The entropy
flow is the carrier of information flow. The entropy flow from cancerous cells to healthy cells takes along the harmful information
of cancerous cells, propagating its toxic action to healthy tissues. We demonstrate that a low-frequency and lowintensity
electromagnetic field or ultrasound irradiation may increase the entropy production rate of a cell in normal tissue than that
in cancer and consequently reverse the direction of entropy current between two kinds of cells. The modification of the PH
value of cells may also cause the reversal of the direction of entropy flow between healthy and cancerous cells. Therefore,
the biological tissue under the irradiation of an electromagnetic field or ultrasound or under the appropriate change of cell
acidity can avoid the propagation of harmful information from cancer cells. We suggest that this entropy mechanism possibly
provides a basis for a novel approach to anticancer therapy.
相似文献
883.
Yi Lu Pingan Yang Yanhong Li Dandan Wen Jiasai Luo Shuhui Wang Fang Wu Liang Fang Yu Pang 《Molecules (Basel, Switzerland)》2021,26(16)
Microwave-absorbing materials have attracted increased research interest in recent years because of their core roles in the fields of electromagnetic (EM) pollution precaution and information security. In this paper, microwave-absorbing material NiFe-layered double hydroxide (NiFe-LDH) was synthesized by a simple co-precipitation method and calcined for the fabrication of NiFe-mixed metal oxide (NiFe-MMO). The phase structure and micromorphology of the NiFe-LDH and NiFe-MMO were analyzed, and their microwave-absorbing properties were investigated with a vector network analyzer in 2–18 GHz. Both NiFe-LDH and NiFe-MMO possessed abundant interfaces and a low dielectric constant, which were beneficial to electromagnetic wave absorption, owing to the synergistic effect of multi-relaxation and impedance matching. The optimum reflection loss (RL) of NiFe-LDH and NiFe-MMO was −58.8 dB and −64.4 dB, respectively, with the thickness of 4.0 mm in the C band. This work demonstrates that LDH-based materials have a potential application in electromagnetic wave absorption. 相似文献
884.
Thermal radiation emitted from flat facet edges of an aluminum bar has been experimentally investigated. It is established that the radiation is predominantly p-polarized and has the pattern with a pronounced maximum oriented at an angle of a few degrees to the plane of the facet. In addition, the magnitude of this maximum increases with the facet length size and tends to saturation as the length increases. The facts suggest that this phenomenon occurs due to diffraction of infrared surface plasmon-polaritons (SPPs) generated by phonons of the sample. This assumption is supported by a cubic dependence of the radiation intensity on temperature, which is typical for thermally generated SPPs (TSPPs). The analytical model for computing the spectrum and the integral intensity of the entire set of TSPPs arriving to the edge of their sources line has been developed as well. 相似文献
885.
An extended flamelet/progress variable (EFPV) model for simulating pulverised coal combustion (PCC) in the context of large eddy simulation (LES) is proposed, in which devolatilisation, char surface reaction and radiation are all taken into account. The pulverised coal particles are tracked in the Lagrangian framework with various sub-models and the sub-grid scale (SGS) effects of turbulent velocity and scalar fluctuations on the coal particles are modelled by the velocity-scalar joint filtered density function (VSJFDF) model. The presented model is then evaluated by LES of an experimental piloted coal jet flame and comparing the numerical results with the experimental data and the results from the eddy break up (EBU) model. Detailed quantitative comparisons are carried out. It is found that the proposed model performs much better than the EBU model on radial velocity and species concentrations predictions. Comparing against the adiabatic counterpart, we find that the predicted temperature is evidently lowered and agrees well with the experimental data if the conditional sampling method is adopted. 相似文献
886.
Application of multi-pulse optical imaging to measure evolution of laser-produced counter-streaming flows
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袁大伟 李玉同 朱保君 李彦霏 仲佳勇 魏会冈 刘畅 原晓霞 张喆 梁贵云 王菲鹿 李芳 赵家瑞 华能 朱宝强 朱健强 江少恩 杜凯 丁永坤 赵刚 张杰 《中国物理 B》2017,26(5):54206-054206
A counter-streaming flow system is a test-bed to investigate the astrophysical collisionless shock(CS) formation in the laboratory. Electrostatic/electromagnetic instabilities, competitively growing in the system and exciting the CS formation, are sensitive to the flows parameters. One of the most important parameters is the velocity, determining what kind of instability contributes to the shock formation. Here we successfully measure the evolution of the counter-streaming flows within one shot using a multi-pulses imaging diagnostic technique. With the technique, the average velocity of the high-density-part(ne ≥ 8–9 × 10~(19)cm~(-3)) of the flow is directly measured to be of ~ 10~6cm/s between 7 ns and 17 ns.Meanwhile, the average velocity of the low-density-part(ne ≤ 2 × 10~(19)cm~(-3)) can be estimated as ~ 10~7cm/s. The experimental results show that a collisionless shock is formed during the low-density-part of the flow interacting with each other. 相似文献
887.
888.
889.
An investigation is undertaken of an integrated mechanical-electromagnetic coupling system consisting of a rigid vehicle with heave, roll, and pitch motions, four electro-magnetic energy harvesters and four tires subject to uneven road excitations in order to improve the passengers' riding comfort and harvest the lost engine energy due to uneven roads. Following the derived mathematical formulations and the proposed solution approaches, the numerical simulations of this interaction system subject to a continuous sinusoidal road excitation and a single ramp impact are completed. The simulation results are presented as the dynamic response curves in the forms of the frequency spectrum and the time history, which reveals the complex interaction characteristics of the system for vibration reductions and energy harvesting performance. It has addressed the coupling effects on the dynamic characteristics of the integrated system caused by:(1) the natural modes and frequencies of the vehicle;(2) the vehicle rolling and pitching motions;(3) different road exci-tations on four wheels;(4) the time delay of a road ramp to impact both the front and rear wheels, etc., which cannot be tackled by an often used quarter vehicle model. The guide-lines for engineering applications are given. The developed coupling model and the revealed concept provide a means with analysis idea to investigate the details of four energy harvester motions for electromagnetic suspension designs in order to replace the current passive vehicle isolators and to harvest the lost engine energy. Potential further research directions are suggested for readers to consider in the future. 相似文献
890.
D. N. Makarov 《Annalen der Physik》2017,529(10)
At present, the sources of entangled photons have a low rate of photon generation. This limitation is a key component of quantum informatics for the realization of such functions as linear quantum computation and quantum teleportation. In this paper, we propose a method for high intensity generation of entangled photons in a two‐mode electromagnetic field. On the basis of exact solutions of the Schrödinger equation, when electrons interact in an atom with a strong two‐mode electromagnetic field, it is shown that there may be large quantum entanglement between photons. The quantum entanglement is analyzed on the basis of the Schmidt parameter. It is shown that the Schmidt parameter can reach very high values depending on the choice of characteristics of the two‐mode fields. We find the Wigner function for the considered case. Violation of Bell's inequalities for continuous variables is demonstrated. 相似文献