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1.
分析了电加热器对流动氦气的加热过程,从能量平衡和热传导的角度建立了系统数学模型,用解析的方法表达了热量的传递过程,得到了传递函数。用Matlab 的Simulink 模块搭建了PID 的控制框架,用积分分离的策略改进了温度控制的效果。仿真结果显示流体在进口温度不断变化的情况下,通过加热器的功率调节获得了比较稳定的气体出口温度,表现出了良好的控制结果。 相似文献
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武振有 《工程物理研究院科技年报》2008,(1)
1 工程设计技术
利用有限元软件和采用CAD设计方法,对复杂结构进行了优化设计,达到了提高产品可靠性的目的。开展了五层阻尼圆板的优化设计,达到了阻尼板具有更佳的减振效果;整机三维立体布线设计,实现了整机布线可视化装配;控制系统的集成化设计,提高了产品的可靠性和降低了电源能耗;Kα波段短脉冲检波器设计,为毫米波短脉冲的检测技术提供了重要的设计经验。 相似文献
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本文在8根水力直径均为186ìm的硅微平行通道的入口端加工了限制装置,抑制了通道间的相互作用,得到了稳定的气液两相流动,并借助于可视化技术,揭示了通道内部不同区段典型的流型特点.分析了经过通道的压降和局部换热系数的变化规律,并用经验关系式和试验结果进行了比较. 相似文献
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王义芳 《中国物理C(英文版)》2008,32(Z1)
描述了兰州重离子加速器中两台等时性回旋加速器的匹配现状,提出了几种可达到100%匹配效率的方法并进行了比较,得到了最佳方案.并叙述了该方案其他的优越性. 相似文献
7.
众所周知,伊萨克•牛顿(IsaacNewton,1642~1727)是英国伟大的科学家,其研究领域包括了物理学、数学、天文学、自然哲学、炼金术和神学。牛顿发明了微积分,发现了万有引力定律,创建了经典力学,设计并制造了第一架反射式望远镜等,被誉为人类历史上最有影响力的科学家。正如恩格斯所说:"牛顿由于发明了万有引力定律而创立了科学的天文学;由于进行了光的分解,而创立了科学的光学;由于创立了二项式定理和无限理论而创立了科学的数学;由于认识了力的本质,而创立了科学的力学"。假如牛顿生活的时代就有诺贝尔奖的话,他无疑会多次获得诺贝尔奖。为了纪念牛顿的杰出成就,以牛顿的姓氏命名力的单位,国际天文学联合会还把662号小行星命名为牛顿小行星。 相似文献
8.
介绍了Blackfin系列DSP的并行外围接口,提出了一种红外视频处理通用模块的构架,省略了数据缓冲硬件环节,缩短了数据等待时间,提高了DSP的运算效率。 相似文献
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E. M. Baitinger E. A. Belenkov M. M. Brzhezinskaya V. A. Greshnyakov 《Physics of the Solid State》2012,54(8):1715-1722
The experimental results of a comprehensive investigation of the structure of detonation synthesis nanodiamonds by electron microscopy methods have been presented. The morphology of diamond nanoparticles has been investigated and the microdiffraction patterns have been analyzed. The method of characteristic fast electron energy loss spectroscopy in transmission electron microscopy has been used. The local density of structural components of a nanodiamond (diamond core and fullerene-like shell) has been obtained. The shape of the shell surrounding the nanocrystal has been determined using model calculations. A hypothesis explaining the charging of the nanodiamond surface has been proposed. 相似文献
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A. V. Rogachev A. I. Kuklin A. Yu. Cherny A. N. Ozerin A. M. Muzafarov E. A. Tatarinova V. I. Gordeliy 《Physics of the Solid State》2010,52(5):1045-1049
The structure of organosilicon dendrimers of the ninth generation with the four-functional core and butyl terminal groups
has been studied by small-angle neutron scattering. It has been demonstrated that the dendrimers are monodisperse objects
with an anisometric shape. The partial volume and the average scattering density have been determined using the contrast variation
technique. It has been shown that the dendrimers under study are identical in overall sizes and scattering density distribution.
It has been revealed that 20% of the overall volume of the dendrimer is accessible for the penetration of the solvent. The
distribution of the scattering length density in the dendrimers has been simulated and reconstructed using the Monte Carlo
method, and a change in the excluded volume for different contrasts has been revealed. The specific features of the spatial
structure of organosilicon dendrimers of higher generations have been discussed. 相似文献
13.
The second and third virial coefficients of polar gases have been calculated for a set of force parameters which has been found suitable to explain the dilute gas viscosity data. The influence of a large number of orientation dependent pair- and three-body nonadditive interactions have been taken into account. The relative contribution of each branch of pair and triplet interactions has been evaluated as a function of temperature. The theoretical results have been compared with the experimental data of NH3 and CH3F. 相似文献
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V. L. Hilarov M. S. Varkentin V. E. Korsukov M. M. Korsukova V. S. Kuksenko 《Physics of the Solid State》2010,52(7):1404-1408
The experimental data on the surface relief of loaded ribbons of an amorphous alloy have been obtained. The distributions
of surface defects formed under loading have been analyzed using the wavelet transform and box counting method. Moreover,
the data on the time accumulation of microcracks in the volume of a loaded granite specimen have been examined. It has been
shown that power-law size distributions of defects (scaling) appear on the surface and in the bulk before fracture. It has
been revealed that the appearance of the power-law distributions is one of the indications of the formation of the self-organized
critical state. The formation of the self-organized critical state in the bulk and on the surface of the material has been
considered. It has been established that the formation of the self-organized critical state precedes the fracture of a solid. 相似文献
15.
M G Ramchandani 《Pramana》1988,31(6):513-517
The complete electronic energy band structure of bcc potassium metal has been calculated using the non-relativistic augmented
plane wave method. The density of states has been calculated and results compared with available thermal, optical and X-ray
data. The lattice constant has been varied to get the band structures for pressures varying from 1 to 5 kb. The Fermi surface
has been studied with varying lattice constants and the results discussed in the light of results of pressure-induced changes
of de-Hass van-Alphen frequency obtained by Altounian and Datars. 相似文献
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S. V. Sazonov 《JETP Letters》2012,96(4):263-274
Various methods to increase the efficiency of the generation of broadband terahertz radiation based on optical rectification have been analyzed. The solutions of self-consistent optical terahertz equations have been studied using the inclined front technique. The effect of symmetric and asymmetric resonant impurity centers incorporated into a crystal has been examined. Transient and asymptotic stages of generation have been considered. Attention has been focused on the evolution of the spectra of both generated terahertz and input optic signals. One- and two-frequency generation modes have been discussed. Acoustic analogs that would provide the possibility of the generation of the gigahertz acoustic supercontinuum using subterahertz elastic signals in a solid have been analyzed. The main similarities and differences between terahertz optics and subterahertz acoustics have been revealed. 相似文献
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V. Antoni M. Bagatin A. Buffa G. Della Mea F. Freyre Jr. P. Mazzoldi F. Romanato 《Il Nuovo Cimento D》1991,13(4):435-453
To investigate the ion flux escaping from the plasma and the impurity flux released by the wall, collector probes made of
graphite, silicon and titanium have been exposed to the deuterium plasma confined in the toroidal device ETA BETA II. The
damages on the collector surfaces have been surveyed by a scanning electron microscopy (SEM) apparatus. The deuterium and
impurity retention have been measured by elastic recoil detection (ERD) and Rutherford backscattering spectroscopy (RBS) techniques
respectively. The implantation build-up has been investigated as a function of the exposure time. The deuterium dose in graphite
saturates after a few discharges, whereas the metal impurities exhibit a linear increase in time. The deuterium flux and its
radial dependence, inferred from the implanted concentrations, have been compared with those measured by Langmuir probes.
Metal impurities have been identified and their relative abundances have been compared with the material wall composition.
The impurity flux is found consistent with the global content in the plasma derived by spectroscopic measurements. The deuterium
dose measured in different samples has been related to the backscattering coefficient of the materials. Finally, to investigate
the damage on sample probes facing the plasma particle flow, erosion probes made of vitreous graphite with silver implanted
at a fixed depth have been exposed to the plasma and the thickness change after exposure recovered. 相似文献
19.
A physical model of interactions of protein molecules has been developed. The regularities of their reactivity have been studied using electrostatics methods for two histone dimers H2A–H2B and H3–H4 assembled from monomers. The formation of histone dimers from different monomers has been simulated and their ability to the formation of stable compounds has been investigated by analyzing the potential energy matrix using the condition number. The results of a simulation of the electrostatic interaction in the formation of dimers from complete amino acid sequences of selected proteins and their truncated analogs have been considered. The calculations have been performed taking into account the screening of the electrostatic charge of charged amino acids for different concentrations of the monovalent salt using the Gouy–Chapman theory. 相似文献
20.
The effect of doping of metallic tin in cadmium iodide crystals has been systematically studied. The method of zone melting has been employed both for purification and for the growth of single crystals of cadmium iodide. The doping has been carried out by zone levelling technique. The as-grown crystals have been characterized by X-ray diffraction and physical methods. All the crystals have been found to consist of the most common polytype 4H. Unlike the case of pure undoped crystals of cadmium iodide grown from melt, all the X-ray photographs showed the presence of arcing. None of the photographs showed the presence of streaking. Besides, the doped crystal were found to be harder than the crystals of undoped cadmium iodide. Unlike the undoped crystals, cleavage in the doped crystals was found to be difficult and highly localized. The results have been discussed. 相似文献