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1.
We discuss recent results of radius to frequency mapping of pulsars. This method shows that for 43 pulsars the radio emission originates near the polar cap for millisecond pulsars and a few hundred km away for longer period pulsars. If the magnetospheres of these object contain dipolar magnetic fields, the corresponding magnetic field strength in the emission region is about 107 gauss, for all pulsars in the sample. We investigate possible physical reasons for the location of the radio emission.  相似文献   

2.
Energy supply rates to magnetospheres of Earth and Jupiter are estimated on the basis of most recent information on controlling parameters, and these are compared with energy consumption rates inside respective magnetospheres. Dominant role played by the reconnection process is suggested, but the high ejection rate of energetic electrons from the Jovian magnetosphere reported by Conlon (1978) might suggest the importance of the planetary rotation as the energy source.Proceedings of the Symposium on Solar Terrestrial Physics held in Innsbruck, May–June 1978.  相似文献   

3.
A review is presented of current theories of nucleosynthesis. The predicted contributions from (1) cosmological nucleosynthesis, (2) super-massive stars, (3) non-violent (quasi-static) stellar evolution, (4) supernova explosions, (5) cosmic ray interactions with the interstellar medium and (6) nova explosions to the observed solar system abundances are summarized. Recent studies of explosive nucleosynthesis in supernovae and of the production of lithium, beryllium and boron by the interaction of cosmic rays with interstellar gas are emphasized. Observations of stellar spectra which either impose limitations upon or provide confirmation of various aspects of these theories are noted, as are several critical nuclear experiments. The general picture which emerges is incouraging in that most of the major abundance features appear to be at least qualitatively understood, but significant further research is required.  相似文献   

4.
New material technologies such as Silicon Carbide (SiC) are promising in the development of compact high-power converters for next-generation power electronics applications. This paper presents an optimized converter design approach that takes into consideration non-linear interactions among various converter components, source and load. It is shown that with the development of high-temperature, high-power SiC power module technology, magnetic components and capacitors become important technology challenges, and cannot be ignored. A 50% improvement in power density is calculated for a 100 V-2 kV, 7 kW SiC DC-DC power converter operating at 150°C compared to a silicon power converter. The SiC power converter can be operated at junction temperatures in excess of 300°C (as compared to 150°C for a silicon power converter) with reasonable efficiency that potentially leads to a significant reduction in thermal management  相似文献   

5.
设备驱动程序是操作系统的信任组件,是I/O子系统与相关硬件的软件接口.WDM定义的以Windows NT内核模式驱动程序为基础的结构和对象,是Windows环境下WDM驱动程序的主体内容.  相似文献   

6.
Nine fields containing BL Lacertae objects have been observed with the Imaging Proportional Counter of the Einstein Observatory. We have detected seven BL Lacertae objects and eight serendipitous sources. In this paper we give a full account of the time variability of 3C 66A, by comparing its behaviour at X-ray energies and at the other frequencies, and we try to identify the features of its overall frequency spectrum.  相似文献   

7.
The feasibility of observation of EUV sources is assessed. Many stars have been detected in the EUV range ( 100–1000); line fluxes from others can be predicted. Selected astrophysical problems are reviewed that can benefit from EUV spectroscopy. Included among them are the physics and dynamics of stellar coronae, confirmation of nuclear surface burning on cataclysmic variables, evolutionary properties of white dwarfs, the helium abundance in the interstellar medium, and spectroscopic signatures of neutrino oscillations.Proceedings of the Conference Solar Physics from Space, held at the Swiss Federal Institute of Technology Zurich (ETHZ), 11–14 November 1980.  相似文献   

8.
The physical sense of the main ideas, presently used in plasma physics, is discussed. An attempt is made to clarify the concepts, used in plasma physical calculations. The concept of `Coulomb collisions' with the implicitly introduced rapid stochastization plays the main negative role in the physics of fully ionized plasma. Statistical methods, which are adequate for the neutral gas and for the partially ionized plasma, are not applicable for the completely ionized case. It is the cause of large errors in evaluating real plasma parameters. A new concept is considered: a fully ionized space plasma should be treated as a dynamical system with a low level of chaos. Further progress in space physics requires a serious renewal of plasma theory.  相似文献   

9.
对交易进行了经济学解释,突破传统的把“交易”理解为市场交换的认识,支持康芒斯的“交易”指人与人之间关系的思想。从内涵和外延分析交易成本,认为交易成本无非就是在交易前、交易中和交易后各种与交易有关的成本,并在微观和宏观角度对交易成本的量化进行综述,最后针对现有交易成本的量化研究提出新的思路和视角。  相似文献   

10.
从理论、体系结构和语言三个方面,对Agent的主要技术和研究现状进行综合分析介绍,并通过一个应用实例对Agent的设计实现作分析说明。  相似文献   

11.
为探究超紧凑燃烧室内流场结构和数值模拟结果的准确性,根据相似原理,搭建了超紧凑燃烧室内冷态流场水流模拟实验装置。用红墨水作示踪剂,显示超紧凑燃烧室周向环腔内不同位置的流场轨迹。在满足与水流模拟实验雷诺数相等的情况下,以空气为介质用Fluent软件对超紧凑燃烧室内冷态流场进行数值模拟。数值模拟与水流模拟实验结果对比表明,所得流动轨迹形状相似,运动趋势一致。利用水流代替空气流研究超紧凑燃烧室内冷态流场特性,能更直观地验证流场结构数值模拟结果的可靠性。  相似文献   

12.
基于优化控制理论,以圆柱绕流的电磁控制为例,以减阻为目的,推导了流场优化控制的性能指标表达式和伴随方程,并对圆柱绕流的优化控制问题进行了数值研究,讨论了该优化控制下,流场和圆柱表面阻力和升力的变化过程.  相似文献   

13.
The ISO mission is expected to allow significant progress in the study of Solar-System objects, especially concerning planetary and cometary atmospheres. Beyond ISO, future Solar-System studies using infrared space missions will require an extension of the spectral coverage toward longer wavelengths and increased spatial capabilities for imaging spectroscopy.  相似文献   

14.
EXOSAT observations reveal that daily X-ray variability appears to be a common property of high luminosity BL Lac objects. Results are reported for PKS0735+178, OM280(=1147+245), OQ530(=1418+546), OV-236 (=1921-293) and OJ287(=0851+202). In OJ287, for which we have the most extensive coverage, the amplitude of variability at X-ray frequencies appears to be a factor of a few larger than at longer wavelengths.  相似文献   

15.
A balloon program in hard X-ray astronomy (20–200 keV) is jointly pursued by the Astronomisches Institut der Universität Tübingen (AIT) and the Max Planck-Institute für Extraterrestrische Physik in Garching (MPE). Since 1973 nine successful balloon flights have been performed from Texas and Australia. Here results on Centaurus A and on several galactic binary X-ray sources are summarized. In particular the high energy photon spectrum of Hercules X-1 and the evidence for the cyclotron line feature which was discovered by us in 1976 is reviewed.  相似文献   

16.
本文根据现代经济增长理论的演化过程,探寻现代经济增长理论的发展趋势。首先分析了经济增长理论三个发展时期中具有代表性的人物、主要观点及这些观点的不中之处;然后,结合复杂性科学所取得的重要成果及其对经济学的冲击,分析了现代经济增长理论所面临的挑战与机遇,进而对现代经济增长理论的未来发展作了展望。  相似文献   

17.
为了解绕水翼附着空化的流体动力特性,用实验方法研究了绕水翼的空化流动现象。实验在空化水洞中完成,采用高速摄像技术观测了不同空化阶段的空穴形态,并测量了水翼所受的升阻力。利用时频分析中的Choi-Williams变换和小波变换对水翼升力信号进行了分析处理,得到了水翼升力信号在不同空化阶段的时频特征。结果表明:在不同的空化阶段,对应于各种不同的空化形态,其流体动力的频谱特性也表现了不同的特点。在没有空化产生时,水翼升力的时频无规则,升力随时间的变化不存在周期性;在片状空化阶段,升力信号变化的频率随着空化数的减小而减小;在云状空化阶段,空穴波动增强,升力信号的周期性更加显著,而此时频率基本不随时间和空化数变化。  相似文献   

18.
激励理论的整合及其对管理实践的启示   总被引:4,自引:0,他引:4  
文章概述了几种有影响的激励理论,并对它们进行了整合和分析,试图从激励理论的整合中找出适合不同激励对象的管理模式,提高管理的实践效果.  相似文献   

19.
The purpose of this article is to summarize a computational approach, which developed and matured over an extended period of time, and has been shown to be useful for performing large-eddy simulation (LES) of flows with active control. Because of the nature of active flow control, simulation of this class of problems typically cannot be carried out accurately by methods less sophisticated than LES. Active control flowfields are highly unsteady, and can be characterized by small-scale fluid structures which are produced by the control process, but may also be inherent in the original uncontrolled situation. The numerical scheme is predicated upon an implicit time-marching algorithm, and utilizes a high-order compact finite-difference approximation to represent spatial derivatives. Robustness of the scheme is maintained by employing a low-pass Pade-type nondispersive spatial filter, which also accounts for the fine-scale turbulent dissipation that otherwise is traditionally provided by an explicitly added subgrid-scale (SGS) stress model. Geometrically complex applications are accommodated by an overset grid technique, where spatial accuracy is preserved through use of high-order interpolation. Utility of the method is illustrated by specific computational examples, including suppression of acoustic resonance in supersonic cavity flow, leading-edge vortex control of a delta wing, efficiency enhancement of a transitional highly loaded low-pressure turbine blade, and separation control of a wall-mounted hump model. Control techniques represented in these examples are comprised of both steady and pulsed mass injection or removal, as well as plasma-based actuation. For each case, features of the flowfield are elucidated and the solutions are compared to the baseline situation where no control was enforced. Where available, comparisons are also made with experimental data.  相似文献   

20.
关于探测器定点在共线平动点附近的控制问题   总被引:6,自引:0,他引:6  
对探测器定点在共线平动点附近的轨道控制提出了一种小推力方案,针对日-地(月)系的具体背景给出了数值模拟结果,并对其进行了相应的分析.  相似文献   

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