共查询到20条相似文献,搜索用时 62 毫秒
1.
P. Bloembergen M. Battuello F. Girard G. Machin L. Wright 《International Journal of Thermophysics》2016,37(4):44
This paper considers the influence of the thermal inertia of the furnace on the shape of the melting curve of the eutectic Co–C. To this end, melting experiments have been performed in a uniform three-zone furnace, with an inherent substantial thermal inertia. The thermal inertia has been quantified by measuring the step-response of the furnace with the sample in its solid state, just below its melting temperature. From the analysis of the effect of the thermal inertia of the furnace, it turned out that during melting the temperature distribution within the furnace, surrounding the crucible, is bound to be in a non-stationary state. This provided the key to properly finalizing the correction to be applied. The shape of the corrected curve differs considerably from that of the curve, as measured, in that the former shows a flatter melting plateau, and a larger curvature on the way down to the solidus point. As regards the liquidus temperature \(T_{\mathrm{liq}}\)—of major interest in the characterization of the transition temperature of high-temperature fixed points—it is demonstrated that the thermal inertia of the furnace shows a kind of self-compensating mechanism. But the effects of the thermal inertia of the furnace on the parameters defining the Scheil fit, involved in the correction procedure, were considerable. 相似文献
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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
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A. I. Igolkin 《Materials Science》1995,30(1):72-74
Some common features of the transgranular embrittlement of -titanium alloys in chloride solutions, hot salts, liquid metals, and air are established. These types of brittle fracture are typical symptoms of trans-granular embrittlement along the basal (near-basal) cleavage planes of metals (alloys) with hcp crystal lattices with various values of the ratioc/a. In this connection, the role of alloying elements and the mechanism of corrosion cracking of -titanium alloys in chloride solutions are reconsidered.Central Scientific Research Institute of Structural Materials Prometheus, St. Petersburg. Translated from Fiziko-Khimicheskaya Mekhanika Materialov, Vol. 30, No. 1, pp. 75–77, January–February, 1994. 相似文献
4.
Glasses in the system xGd2O3·(100 − x)[TeO2·GeO2] with 0 ≤ x ≤ 50 mol% have been prepared from melt quenching method. In this paper, we investigated changes of the coordination numbers
of germanium, tellurium, and gadolinium ions by investigations of FTIR, EPR, and UV–VIS spectroscopy. By analyzing the structural
changes resulted from the IR spectra we found that the bending modes of [GeO4] structural units and the deformed modes of the Te–O–Te linkages produce intercalation of the [GdO
n
] entities in the germanate–tellurate chain network and densification of the glasses by increasing the number of [GeO6] structural units. EPR spectra of the studied samples reveal that the gadolinium ions play a role of network former. The
UV–VIS spectra show broad UV absorption bands located in the 250–350 nm region. Their intensity increase with the increasing
of Gd2O3 content showing that these stronger transitions can be due to the presence of the O=Ge bonds (n–π* excitations) of [GeO5] structural units. The [GeO5] structural units are more stable thermodynamically than their analogues and the [GeO6] structural units produce the improvement of the amorphous character of these glasses. 相似文献
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On the basis of a survey of works, we demonstrate the priority of the Lviv school of mechanics in the field of creation and development of the deformation theory of limiting equilibrium of bodies with cracks known as the
k
-model. The theory is based on the criterion of crack opening displacement proposed by Leonov and Panasyuk and on the procedure of evaluation of this quantity by modeling the inelastic zones in front of the crack by cuts the edges of which are loaded by certain stresses 0 whose physical meaning is determined by the properties of the material. This method (known as the model of plastic strips) is also used for the determination of the development of plastic zones at the crack tip for various configurations of plates and loads and also in twisted bodies. The results of numerical calculations agree with the experimental data. 相似文献
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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
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V. V. Pasichnyi V. Ya. Berezhetskaya A. A. Goryachev M. Ya. Gofin G. A. Frolov 《Journal of Engineering Physics and Thermophysics》2001,74(6):1396-1398
We have investigated the serviceability of the heatinsulating tiles of the orbital aircraft Buran under radiant heating on an SGU7 solar plant with a mirror concentrator 5 m in diameter. Cycles of aerodynamic heating with a duration of 20 min were simulated. For the total number of cycles for different materials from 20 to 85, the efficiency and serviceability of TZMKtype materials with different coats have been corroborated. The results obtained agree with the test data obtained on gasdynamic (power consumption 1 MW) and radiation (250 kW) test beds, which enables such tests to be recommended for use at preliminary stages in powersaving and ecologically harmless solar furnaces. 相似文献
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《Composites Part A》2003,34(8):689-694
An experimental investigation of the effect of nanotube length and aggregate size on the mechanical and electrical properties of the composites was reported. Three treatments, that affect mainly the length and aggregate size, were applied on the CVD MWNTs before they were added into a resin matrix. They had a very clear impact on the dielectric properties of the composites and on the improvement efficiency. There was an insulator-to-conductor transition with the as-prepared MWNTs at 0.5 wt%. Regarding the mechanical properties, the addition of MWNTs increased the Young's modulus and reduced the fracture strain. In that case, the pre-treatment on MWNTs, however, had a much more moderate effect on the improvement efficiency. 相似文献
11.
《Materials Chemistry and Physics》1988,20(1):87-97
The effect of the parameters of globular structure (diameter of globules and number of their contact points) on the course of a texture modification process has been examined. Modification of silica gels was carried out in an autoclave at elevated pressure in the temperature range 110–300°C and in a water vapour atmosphere. Silica gels having specific surface area of 64–830 m2/g and predominant pore radii of 40–1000 Å were modified. The mechanism of hydrothermal treatment is relatively complex. It depends, among other things on different parameters of globular texture, the temperature of a process and on the presence of different admixtures in the adsorbent being modified. Above 200°C the course of hydrothermal modification depends only slightly on the nature of the silica gel (narrow or wide porous). 相似文献
12.
B. Klaić 《Scientometrics》1995,32(2):133-152
The scientific production of researchers from the Republic of Croatia, consisting of the published papers with addresses of the institutions from Croatia only, was analyzed for the period 1990–1992, covering 2047SCI, SSCI, andA&HCI registered papers. The source index ofSCI has registered 1912 (92.50% of total number of published articles) papers,SSCI 118 (5,71%), andA&HCI 37 (1.79%) papers, respectively. The papers were published in more than 700 different journals, covering 122 scientific subfields. The most frequently used journals are the nationalPeriodicum Biologorum, Croatica Chemica Acta andCollegium Antropologicum with 236 published papers or 11.5%. The largest number of papers have been published in scientific subfields:Biology (146 papers),Chemistry (107), andPhysics of Condensed Matter (102). The average paper was published by 3.57 researchers, but subfields ofNuclear Physics (7.40 authors per paper),Immunology (5.67), andHematology (5.60) were with the highest authorship. The partial contributions of institutions were also determined, and the most productive were Ruder Bokovi Institute with 645.0, the Faculty of Medicine with 396.7, and the Faculty of Science and Mathematics with 201.7 published papers, respectively. The average quality of the used journals were estimated; Institute of Physics, Ruder Bokovi Institute, and the Faculty of Science and Mathematics published their papers in journals with bigger impact factor (higher quality) than average institutions. Publications were divided by the type of papers, most frequent being articles (1778 publications, 86.85%), notes (117, 5.71%) and letters (56, 2.74%), respectively. Scientific subfield distribution of papers published by the most productive institutions were also analyzed. 相似文献
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Edith Penrose’s Theory of the Growth of the Firm and the strategic management of multinational enterprises 总被引:1,自引:1,他引:0
– | This paper provides a formal model of Edith Penrose’s Theory of the Growth of the Firm which has important implications for the strategy of multinational enterprises. |
– | The model provides an analysis of the trade-off between product diversification and foreign market penetration. It also can account for the speed of entry into foreign markets. |
– | Formalizing Penrose’s Theory of the Growth of the Firm provides an account of internationalization incorporating geographical expansion patterns, sequential decision making and learning. |
15.
《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》1988,270(1):146-148
A Monte Carlo simulation for the study of the influence of the thickness of the radioactive source in β-ray spectroscopy is presented in this paper. We make use of the Bethe-Bloch formula for ionization loss and Rutherford scattering cross section to trace the tracks of the β particles from a randomly sampled point source of given energy, which has been implanted in an aluminum coating with copper backing. We have studied seven groups of β rays with momenta from 119.14262 to 139.12328 keV/c. There are the peak shift, the broadening of the line width and the low energy tail. Their momentum dependences have been found. The program can be applied to similar cases with minor modification. 相似文献
16.
Marta Weiss 《History of Photography》2013,37(4):431-444
From 1859 to 1878 the British sculptor Richard Cockle Lucas assembled at least sixteen albums containing photographs of himself in numerous guises, ranging from Shakespearean roles to embodiments of specific emotions. Lucas utilised the practice of dressing up in front of the camera in conjunction with the album format as an ongoing means of experimenting with photography’s capacity to convey human expression, and as an extension of his concerns as a sculptor. Lucas’s albums, which also include photographs of his work in sculpture, represent the first sustained pursuit of photographic self-depiction in such a wide range of roles. Read in conjunction with Lucas’s own writings on expression in photography and sculpture, the albums reveal how Lucas viewed photographic self-portraiture as a form of ‘living sculpture’ to be enacted before the camera. 相似文献
17.
O. E. Gerasimova S. F. Borisov C. Boragno U. Valbusa 《Journal of Engineering Physics and Thermophysics》2003,76(2):413-416
The morphology of the surface of singlecrystalline silicon as a function of the degree of oxidation has been investigated by the method of atomicforce microscopy. The roughness of the surface at different stages of treatment has been evaluated with the use of topographic images. It has been found that the standard deviation characterizing the distribution of microroughnesses by height, or the roughness, increases with oxidation of the sample. A histogram of the distribution of structural surface elements has been presented. The data obtained can be employed in specifying boundary conditions to gasdynamic problems. 相似文献
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A. K. Alekseev 《Journal of Engineering Physics and Thermophysics》2002,75(2):446-452
Consideration has been given to the employment of the conjugate problems of first and second orders, which are applied to solution of the inverse problems of heat exchange, to calculate the error of solution of the primal problem from the data on the error of the initial information. It has been shown that the algorithms of solution of the inverse problems of heat exchange in a variational formulation make it possible to directly determine the error of the corresponding primal problems by calculation of the Hessian range. 相似文献