共查询到20条相似文献,搜索用时 31 毫秒
1.
N. I. Nikitenko 《Journal of Engineering Physics and Thermophysics》2002,75(3):684-692
The fundamentals of radiation theory and the mechanism of evaporation of condensed bodies are presented. The distribution functions of particles of a body by energies and by the intensity of their transition from one energy level to another in the process of evaporation have been obtained based on the law of spectralradiation intensity of the body particles. The temperature dependence of the resulting vapor flow on the outer surface of a massive condensed body and a thin layer in equilibrium and nonequilibrium states, which, in the limit, transforms to the known Hertz–Knudsen formula, has been found. 相似文献
2.
The compound γ-RbNbUO6·H2O was prepared for the first time as single crystals, which were studied by X-ray diffraction. Crystal data: rhombic system, space group Pcab, a = 7.614(2), b = 11.219(2), c = 16.510(3) Å, Z = 8. The crystal structure is built from uranium-containing layers of the composition [NbUO6] 2∝ δ? , infinite in two directions. The water molecules and rubidium atoms distributed over two randomly occupied positions are accommodated between the layers. 相似文献
3.
Reinhard L■ck 《材料科学技术学报》1997,13(4):260-264
For a few years it has been realized that nanocrystalline phases can be formed during crystallization of amorphous alloys annealed isothermally below the crystallization temperature of usual heating experiments. Data of this transformation monitored by the measurement of magnetic susceptibility are presented. A method using a magnetic balance with electronic stabilisation and combined computer facilities is applied. Constant heating and cooling rates as well as isothermal heat treatments are used. Magnetic measurements are able to detect the onset of the transformation of amorphous Ni-P alloys much earlier than was possible with differential scanning calorimetry. The transformation kinetics can be analyzed by means of the Avrami plot based on the Johnson-Mehl-Avrami equation.The kinetics of solid state reactions in the nanostructured material can be investigated similarly. Formation of a Ni-phase in a nanostructured Hf-Ni alloy could be detected in a very early stage, where calorimetric methods are not sensitive. Segregation phenomena could be detected from the experiments even after long time. The sensitivity of the applied method is not dependent on the heating rate as the sensitivity of scanning calorimetry is 相似文献
4.
刘纯鹏 《材料科学技术学报》1990,6(2):143-143
The metallurgy department of Kunm-ing Institute of Technology,with its empha-sis on nonferrous metallurgy,is one of themajor academic and technical centres underthe China National Nonferrous Metals In-dustry Corporation(CNNC).The province of Yunnan,of whichKunming is the capital city,is very rich withresources of nonferrous metals,such as 相似文献
5.
Escherichia coli β-galactosidase was incubated in the presence of the slow-release inhibitor D-galactal for 30 min at a concentration of 70 times its K(i). The sample was then diluted 20000-fold into buffer containing the fluorogenic substrate 9H-(1,3-dichloro-9,9-dimethylacridin-2-on-7-yl) β-D-galactoside, reducing the inhibitor concentration to K(i)/280. The sample was subjected to a capillary electrophoresis continuous flow single enzyme molecule assay. As the inhibitor dissociated while the enzyme traveled the length of the capillary, a fraction of molecules showed stepwise increases in activity. This was due to the activation of individual subunits within single molecules. The changes in activity can be largely explained in terms of each molecule containing subunits of indistinguishable activity. 相似文献
6.
Analysis of clusters and uniformity of distribution of states of polarization on the Poincaré sphere 总被引:1,自引:0,他引:1
Perlicki K 《Applied optics》2005,44(21):4533-4537
An analysis of the clusters and the uniformity of distribution of states of polarization on the surface of a Poincaré sphere generated by rotating wave plates is given. The analysis of clusters of the states of polarization is based on a spherical radial distribution function. For uniform analysis of the distribution, two methods are proposed. The first method is based on calculation of the correlation coefficient; the second method is based on calculation of the angles between pairs of the states of polarization on the Poincaré sphere. For polarization scramblers consisting of eight or more rotating wave plates, nonclustered and near-uniform distribution of states of polarization is obtained. 相似文献
7.
S. P. Zhvavyi G. D. Ivlev V. A. Pilipenko V. N. Ponomar' 《Journal of Engineering Physics and Thermophysics》2001,74(2):433-440
The authors consider the process of fusion of phosphorosilicate and borophosphorosilicate glasses in planarization of the surface of integrated microcircuits under the conditions of both isothermal and pulse heat treatment. An expression for calculating the angle of fusion of the relief step as a function of the concentration of doping impurities in a glass and the time and temperature of heat treatment is obtained. 相似文献
8.
K. E. Belyavin D. V. Min'ko O. O. Kuznechik 《Journal of Engineering Physics and Thermophysics》2004,77(3):628-637
Consideration has been given to the process of electricdischarge sintering (EDS) of a powder fill in passing an electric current through it. The dependences for calculation of the heat release, the efficiency of an EDS unit, the resistance of a powder fill, and the temperature in the contact zone have been obtained. An algorithm for calculation of the technological parameters of the process of EDS has been given. 相似文献
9.
《材料科学技术学报》2001,(3)
10.
The zinc oxide varistor with a low threshold voltage and large grain size was derived with ZnO crystalline seeds from a molten salt process The chemical composition and I-V characteristics of single grains and single grain boundaries were determined by means of energy dispersive spectrum (EDS) and microcontact measurement respectively. Temperatu re dependence of dielectric loss at various frequencies and voltage dependence of capacitance were carefully measured. Based on these experimental data. the barrier heights of giain boundaries are estimated to be 0.2. 0.5 and 0.6 eV respectively corresponding to thick, th in and direct contact grain boundaries. In addition. a computerized electrical circuit simufation is employed in simulating I-V characteristics of single grain boundary within ZnO varistor. By adjustjng parameters of resistor and diode, a general agreement between the measured data and simulated curves is achieved 相似文献
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13.
《中国标准化(英文版)》2004,(1)
National standardization technical committee of superconduction was established on Aug 26th, 2003. Tmittee contains 22 experts, of which the percentage of professors and researchers reaches up to 77.3%mention there are four academician consultants, Gan Zizhao, Zhao Zhongxian and Yang Guozhen fromAcademy of Sciences, and Zhou Lian from China Academy of Engineering. The four academicians had ed earlier in the 7th Academic Seminar of Superconduction in April that the high-tech superconduct… 相似文献
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15.
《Drug development and industrial pharmacy》2013,39(7):797-801
The rheology of non-Newtonian fluid systems is complex. Their experimental study is difficult because of the existence of many dependent variables. In the present work, a mathematical equation is proposed to calculate the spread surface from a simple viscosimetric study in a theoretical way. It was determined for multiple parameters. The spread surface has to be marked because of its direct relation to the shear stress; this fact enabled us to connect one variable dependent on the compression deformation with another dependent on the shear deformation. At the same time, the viscoelastic phenomenon can be evidenced by applying this mathematical equation. 相似文献
16.
We present the results of investigation of the axles of wheels of AN-124 Ruslan aircrafts after failures occurring either in service or in the process of resource testing. It is shown that, in service, the axles fail according to the intergranular mechanism. At the same time, in the course of stand tests, we observe fatigue fracture. On the basis of the analysis of the structure of landing gear and the results of investigation of external factors, we propose a model of formation and propagation of cracks in the axle of a wheel. We also propose several procedures aimed at the prevention of failures. 相似文献
17.
Bi2Sr2CaCu2Ox superconductor was studied by differential scanning calorimetry (DSC) and thermogravimetry (TG) in different atmospheres. It is discovered that there is a thermal anomaly in the DSC curve, associated with a weight loss in the TG curve before the melting of the sample. Careful thermal analysis and high temperature X-ray diffraction reveal that the thermal anomaly and the weight loss show an instability of the crystalline Iattice. By annealing the sample in oxygen and argon, respectively and then by TC measurement and thermal analysis, the coincidence of transition temperature with the instability is found. The coincidence is further confirmed by Y-doped 2212 phase. 相似文献
18.
The diameters of the coexistence curves of aqueous solutions of tetrahydrofuran and two quasibinary, isotopically related mixtures near their lower consolute points are analyzed in terms of different composition variables including mole, mass, and volume fractions, using various possible definitions of the reduced temperature. A (1–) anomaly is observed for all choices of the temperature and concentration variables. In terms of mole fraction the diameters are free from a regular contribution as well as from a spurious 2 contribution arising from the inappropriate choice of the order parameter. The mass and volume fractions lead to an apparent symmetrization of the coexistence curve, but cause significant 2 contributions to the diameter that could mask the 1– anomaly. A reduced temperature that accounts for the presence of both upper and lower critical consolute points is found to be preferable, although the second critical point is 80 K away. 相似文献
19.
Zahra Rajabi 《Materials Science & Technology》2018,34(10):1218-1227
This study was aimed at developing lead-free brass alloys with the goal of substituting lead element with tin. For this purpose, lead-free alloys with tin were developed and the microstructure, hardness and machining behaviour of the Cu–30%Zn alloy was compared with Cu–30%Zn–x%Sn (x?= 1.2, 3.2, 5.4, 8, 11.4, 13.9, 17.4). The results showed that the addition of Sn to single-α phase brass led to the formation of duplex (α?+?β′) brass and then the formation of (β′?+?? ) brass both with increased hardness. In addition, the addition of Sn to Cu–30%Zn alloy led to the decrement of equivalent machining forces (Fm), surface roughness and also the promotion of chip fragmentation due to the formation of the β′ phase, which is an improvement in machinability. 相似文献
20.
E. I. Suzdal'tsev 《Journal of Engineering Physics and Thermophysics》2001,74(6):1533-1538
This paper presents the results of investigations of the thermostability of the glassceramics obtained by ceramic technology with the use of the method of casting blanks from highdensity aqueous suspensions of lithium alumosilicate glass with their subsequent sintering and crystallization under combined conditions of treatment. It is shown that the basic factors influencing the thermostability of materials are the values of the elastic modulus, CTLE, and porosity. Experiments and calculations indicate that the glassceramics exceeds the known radiotechnicalpurpose pyroceramics in thermostability and can be used in articles designed to operate under hard conditions. 相似文献