共查询到20条相似文献,搜索用时 31 毫秒
1.
Mori I. Sumitomo K. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1988,16(6):623-630
An application of ambipolar potential in a magnetized plasma is proposed for direct energy conversion. Analyses of a model device for 20-MW-per-unit-length (without considering end loss) and 14-MW-per-unit-length (with the end loss) are shown. The plasma density profile, the potential distribution in the device, and the voltage-current characteristics are obtained on the basis of the Poisson continuity equation system. As an example, a theoretical energy loss by neutral particles, which should not affect the total efficiency much. Experiments with a small thermal ionization-type device were performed wherein the relations of output voltage versus current and power versus impedance were acquired. the experimental results are compared with the theoretical and a qualitative agreement is obtained 相似文献
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Jun‐ichi Aihara 《Journal of Physical Organic Chemistry》2008,21(1):79-85
Circuit resonance energy (CRE) is a key quantity that links energetic and magnetic criteria of aromaticity for a polycyclic π‐system. Topological resonance energy (TRE) correlates well with the sum of CREs for an entire π‐system. We found that bond resonance energy (BRE), so far defined to estimate the degree of kinetic stability for a polycyclic π‐system, also correlates very well with the corresponding quantity defined with CREs. These findings justify the view that graph‐theoretical quantities, such as TRE and BRE, can be used safely even though they rely on unrealistic reference structures. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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More than 10?7 of the positrons emitted by 11C (produced by proton bombardment of boron) emerge from the room-temperature boron target with a low energy (less than 1 eV) and a measured energy width of (0.100+0.010) eV. 相似文献
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Vasily L. Morgunov 《Pramana》2007,69(6):1097-1100
A new calorimeter energy calibration method was developed for the proposed ILC detectors. The method uses the center-of-mass
energy of the accelerator as the reference. It has been shown that using the energy conservation law it is possible to make
ECAL and HCAL cross calibration to reach a good energy resolution for the simple calorimeter energy sum.
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M. Venkataramanaiah S.V.J. Lakshman 《Journal of Quantitative Spectroscopy & Radiative Transfer》1981,26(1):11-13
The true potential energy curves have been constructed for the ground and excited electronic states of SiCl by the method of Lakshman and Rao. The dissociation energy of the ground state has been estimated by fitting the Hulburt-Hirschfelder function to the true potential energy curves. The dissociation energy thus obtained is 33,500 cm-1 (4.15 eV), which is in good agreement with the value of 4.5±0.5 eV reported by Gaydon. 相似文献
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We present a holographic dark-energy model in which the Newton constant GN scales in such a way as to render the vacuum energy density a true constant. Nevertheless, the model acts as a dynamical dark-energy model since the scaling of GN goes at the expense of deviation of concentration of dark-matter particles from its canonical form and/or of promotion of their mass to a time-dependent quantity, thereby making the effective equation of state (EOS) variable and different from −1 at the present epoch. Thus the model has a potential to naturally underpin Dirac's suggestion for explaining the large-number hypothesis, which demands a dynamical GN along with the creation of matter in the universe. We show that with the aid of observational bounds on the variation of the gravitational coupling, the effective-field theory IR cutoff can be strongly restricted, being always closer to the future event horizon than to the Hubble distance. As for the observational side, the effective EOS restricted by observation can be made arbitrary close to −1, and therefore the present model can be considered as a “minimal” dynamical dark-energy scenario. In addition, for nonzero but small curvature (|Ωk0|?0.003), the model easily accommodates a transition across the phantom line for redshifts z?0.2, as mildly favored by the data. A thermodynamic aspect of the scenario is also discussed. 相似文献
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给出了高能脉冲X射线能谱测量的基本原理及实验结果.采用Monte-Carlo程序计算了高能光子在能谱仪中每个灵敏单元内的能量沉积,利用能谱仪测量了"强光Ⅰ号"加速器产生的高能脉冲X射线不同衰减程度下的强度,求解得到了具有时间分辨的高能脉冲X射线能谱,时间跨度57ns,时间步长5ns,光子的最高能量3.0MeV,平均能量1.04MeV,能量在0.2—0.9MeV之间的光子数目最多,占46.5%.也利用二极管的电压电流波形理论计算了光子的能谱,并与利用能谱仪测得的能谱进行了比较,两种方法所得结果基本一致. 相似文献
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Maciej Krystian 《哲学杂志》2013,93(9):949-966
In fcc crystals, dislocations are dissociated on the {111} glide plane into pairs of partial dislocations. Since each partial interacts individually with the Peierls potential and is coupled to its neighbour by a stacking fault, periodic variations in the separation distance d of the partials occur when dislocations running along closed packed lattice directions are displaced. This can drastically reduce the effective Peierls stress. By using the Peierls model the structure of 0°, 30°, 60° and 90° dislocations in a typical fcc metal with the elastic properties of Cu and a stacking-fault energy γ0 in the interval 0.04?≤?γ0?≤?0.05?J/m2 was studied, and the magnitude of the Peierls energy ΔE P and the resulting kink energies E K were determined. Since the energies involved are of the order of 10?3?eV/b or less, their magnitude cannot be asserted with high confidence, considering the simplifying assumptions in the model. The difference in the changes of the core configuration during displacement of dislocations of different orientations should, however, be of physical significance. It is found that a dissociated 60° dislocation generally has a higher effective Peierls energy than a screw dislocation, but the reverse is true for the kink energy, at least in Cu. 相似文献
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Electric ignition energy evaluation and the energy distribution structure of energy released in electrostatic discharge process
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Ignition energy is one of the important parameters of flammable materials, and evaluating ignition energy precisely is essential to the safety of process industry and combustion science and technology. By using electric spark discharge test system, a series of electric spark discharge experiments were conducted with the capacitor-stored energy in the range of 10 J, 100 J, and 1000 J, respectively. The evaluation method for energy consumed by electric spark, wire, and switch during capacitor discharge process has been studied respectively. The resistance of wire, switch, and plasma between electrodes has been evaluated by different methods and an optimized evaluation method has been obtained. The electric energy consumed by wire, electric switch, and electric spark-induced plasma between electrodes were obtained and the energy structure of capacitor-released energy was analyzed. The dynamic process and the characteristic parameters(the maximum power, duration of discharge process) of electric spark discharge process have been analyzed. Experimental results showed that, electric spark-consumed energy only accounts for 8%–14% of the capacitor-released energy. With the increase of capacitor-released energy, the duration of discharge process becomes longer, and the energy of plasma accounts for more in the capacitor-released energy. The power of electric spark varies with time as a damped sinusoids function and the period and the maximum value increase with the capacitor-released energy. 相似文献
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核能与聚变裂变混合能源堆 总被引:3,自引:0,他引:3
未来20年将是核能发展的一个关键时期.2035年左右,快堆有望投入商用;磁约束聚变、激光聚变、Z箍缩聚变也都有演示堆计划.聚变演示堆存在纯聚变与聚变裂变混合能源堆两种可能,而后者可降低聚变功率,缓解高能中子对材料的辐照损伤.另外,氘氚聚变供能时间有限.文章介绍了混合能源堆的概念.能源堆可充分利用铀资源,且后处理不涉及铀钚分离,有很好的防扩散性能.裂变堆、聚变堆、能源堆共同发展,可望使核能在不太长的时间内获得大规模应用,并可为人类提供千年以上的能源供应. 相似文献
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A key issue for noise, vibration and harshness purposes, when modelling the vibroacoustic behaviour of a system, is that of determining how energy is transmitted from a given source, where external energy is being input, to a target where energy is to be reduced. In many situations of practical interest, a high percentage of the transmitted energy is driven by a limited set of dominant paths. For instance, this is at the core of the existence of transmission loss regulations between dwellings. In this work, it is shown that in the case of a system modelled with statistical energy analysis (SEA), the problem of ranking dominant paths can be posed as a variation of the so-called K shortest path problem in graph theory. An algorithm for the latter is then modified and adapted to obtain the sorted set of K dominant energy transmission paths in a SEA model. A numerical example to show its potential for practical applications is included. 相似文献
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F. A. Bumiller F. R. Buskirk J. N. Dyer R. D. Miller 《Zeitschrift für Physik A Hadrons and Nuclei》1969,223(5):415-424
The energy distributions of electrons of about 54, 75 and 97 Mev have been measured before and after passing through aluminum absorbers of thicknesses ranging from 0.730 to 5.574 gm/cm2. The electrons were accelerated by the LINAC of the Naval Postgraduate School. The most probable energy losses agree with the theory ofBlunck andWestphal for all thicknesses; the half widths of the distributions agree with theory except for large thicknesses, where they exceed the theoretical values. These results are in contrast to those ofBreuer, which indicate systematically large half widths and most probable energy losses which are greater than theory for thicknesses greater than about 2 gm/cm2. Since our data agree with those ofBreuer, the difference occurs in the treatment of the theory. 相似文献
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Previous models of surface segregation have generally been based on the assumption that a decrease in surface free energy constitutes the predominant driving force for the phenomenon. In contrast, grain boundary segregation models have been founded on the postulate that the major driving force for that phenomenon is the reduction in lattice strain energy which accompanies the transfer of misfitting solute atoms from the lattice to the boundary. These two concepts have been combined here into a single unified formalism of surface segregation. In addition, the temperature dependence of surface composition of both nickel-rich and gold-rich nickelgold alloys has been measured by Auger electron spectroscopy. Comparisons of the predictions of the combined formalism with the experimental results show excellent agreement between measured and calculated heats of adsorption (segregation). Furthermore, the present formalism provides estimates of the entropies of adsorption which can be used to explain apparent incompatibilities between the behavior of gold-rich and nickel-rich alloys. 相似文献
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关于静电体系总能和相互作用能的几点讨论 总被引:3,自引:1,他引:2
在阐明静电体系总能和相互作用能的基础上,利用电动力学中得到的静电体系总有量公式W总=1/2∫ρdV,在电荷体分布的情况下,当电荷分割为n个体电荷元时,可以严格证明:limW互=W总。 相似文献
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《Physics letters. [Part B]》1988,214(4):657-659
the distribution of energy density for nucleus-nucleus reactions at 200 GeV/nucleon is calculated using the gluon-gluon interaction model. Agreement with data which use the Bjorken approximation as input is good and the initial longitudinal extension of the central fireball turns out to be approximately 2 fm. 相似文献
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B. Mace 《Journal of sound and vibration》2003,264(2):391-409
Expressions for the energy influence coefficients of a built-up structure are found in terms of the modes of the whole structure. These coefficients relate the time and frequency average energies of the subsystems to the subsystem input powers. Rain-on-the-roof excitation over a frequency band Ω is assumed. It is then seen that the system can be described by an SEA model only if a particular condition involving the mode shapes of the system is satisfied. Broadly, the condition holds if the mode shapes of the modes in the frequency band of excitation are, on average, typical enough of all the modes of the system in terms of the distribution of energy throughout the system. If this condition is satisfied then the system can be modelled using an “quasi-SEA” approach, irrespective of the level of damping or of the strength of coupling. However, the resulting model need not be of a proper SEA form, and in particular the indirect coupling loss factors may not be negligible. 相似文献