Showing papers by "University of Science and Technology Beijing published in 1989"
TL;DR: In this paper, the specific heat of a single phase (Bi, Pb) 2 Sr 2 Ca 2 Cu 3 O 10+ y sample with orthorhombic structure was measured over the temperature range 90 to 135 K.
Abstract: The specific heat of a single-phase (Bi, Pb) 2 Sr 2 Ca 2 Cu 3 O 10+ y sample with orthorhombic structure has been measured over the temperature range 90 to 135 K, revealing a jump of ΔC = 5.3 J / mol · K at T c =107 K and corresponding to the value of ΔC T c = 49.5 mJ/mol·K 2 . The Sommerfeld constant γ =34.6 mJ / mol · K 2 was estimated from the weak-coupling BCS limit. The Debye temperature can be obtained by fitting to a Debye specific heat function with θ = 418 K .
21 citations
TL;DR: In this article, a new solution model named integration model has been developed for predicting the ternary thermodynamic properties from its binary ones, which is more reasonable for its full utilization of binary information.
Abstract: A new solution model named integration Model has been developed for predicting the ternary thermodynamic properties from its binary ones. This model is more reasonable for its full utilization of binary information. Binary thermodynamic properties are fitted by means of rational function method and ternary partial thermodynamic properties are calculated using R-function method. Integration model was applied to the Na-Hg-Pb system and a good accordance was obtained between the calculated and experimental values.
19 citations
TL;DR: In this paper, the occupied position of Fe in the superconducting phase of Fe-doped YBa2Cu2 was estimated by point charge model by measuring the Mossbauer spectra in the temperature range from 78 K to 273 K.
16 citations
TL;DR: Preparation des alliages de composition Al6Cr 0,5Ni0,5 et Al4Mn 0, 5Ni0.5 et etude de microscopie electronique en transmission as mentioned in this paper.
15 citations
TL;DR: In this paper, a stainless steel was irradiated with 70-170 keV He+ to a dose of 1015−1×1018 ions cm−2 at 77-673 K. Post-irradiation annealing was carried out up to 1323 K. 2.5 MeV enhanced proton backscattering, transmission electron microscopy (TEM), scanning electron microscope (SEM) and conversion electron Mossbauer spectrometry (CEMS) are used to investigate the He trapping, bubble structures and the He release.
14 citations
TL;DR: In this paper, the magnetization and upper critical field of PbBiSrCaCuO with zero resistance temperature 107K were measured in an applied magnetic field up to 7T.
13 citations
TL;DR: In this paper, the authors present a formulae for calculating activities and activity coefficients from the phase diagram involving a two liquid or solid coexisting phases, in which no extra thermodynamic properties are required except for the composition of components along a miscibility gap.
Abstract: The formulae for calculating activities and activity coefficients from the phase diagram involving a two liquid or solid coexisting phases have been presented, in which no extra thermodynamic properties are required except for the composition of components along a miscibility gap. The application of these equations to the Zn-Pb and Zn-Bi systems shows that the calculation results are close to the experimental measurements.
10 citations
TL;DR: In this paper, the reduction electrochimique du praseodyme (Pr 3+ ) en Pr 3+ metallique en une seule etape, sur une electrode de tungstene ou de fer dans un sel fondu de LiCl−KCl a 450 o C est etudiee par voltammetrie cyclique et chronoamperometrie.
Abstract: La reduction electrochimique du praseodyme (Pr 3+ ) en praseodyme metallique en une seule etape, sur une electrode de tungstene ou de fer dans un sel fondu de LiCl−KCl a 450 o C est etudiee par voltammetrie cyclique et chronoamperometrie
9 citations
TL;DR: In this article, the effects of the presence of a stacking fault in austenitic stainless steel on higher-order Laue zone (HOLZ) reflections of convergent-beam electron diffraction patterns were investigated.
Abstract: The effects of the presence of a stacking fault in austenitic stainless steel on higher-order Laue zone (HOLZ) reflections of convergent-beam electron diffraction patterns were investigated. The splitting of certain HOLZ lines was examined. The parameters affecting the separation of two minima of a split HOLZ line, the related intensity distribution and the position of the two minima with respect to the single dark line in a perfect area of the crystal were determined on the basis of experiments and computations. A many-beam dynamical simulation technique was developed. It provides a convenient and reliable method for stacking-fault identification. Redistribution of excitation of Bloch waves was calculated and used to explain the origin of the HOLZ line splitting. A simple kinematical explanation is also given.
8 citations
TL;DR: In this paper, a vitesse de deformation lente d'echantillons de fer charge or non et hydrogene et soumis ou non a champ magnetique parallele a l'axe de traction.
8 citations
20 Dec 1989-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, a relationship between fracture ductility and stress triaxiality is derived from a modified damage criterion and is experimentally verified by using circumferentially notched tension specimens, from which an approximate equation for the fracture toughness is obtained.
Abstract: In this paper, the effect of stress states on the fracture ductility and fracture toughness of ductile metals is investigated. A relationship between the fracture ductility and stress triaxiality is derived from a modified damage criterion and is experimentally verified by using circumferentially notched tension specimens, from which an approximate equation for the fracture toughness is obtained. The results show that the calculated values of fracture ductility and fracture toughness are in good agreement with the experimental values when the influence of the stress triaxiality is taken into consideration.
01 Oct 1989
TL;DR: In this article, a gate turnoff (GTO)-type AC motor speed control device is presented with the advantages of simple construction, convenient control, high power factor, and low cost.
Abstract: A Scherbius device is presented with a gate turnoff (GTO)-type AC motor speed control device and the advantages of simple construction, convenient control, high power factor, and low cost. The invertor capacity of this device is reduced to about 40% of that of a common Scherbius system with the same load. There is only one gate turn-off element connected in parallel with the direct current side of the inverter in this device. A symmetric pulse-width modulation (PWM) control is adopted for the device under a certain fixed inverting firing angle of the inverter, instead of adjusting the inverting firing angle. In such a manner the inverted voltage and the motor speed can be controlled with a higher power factor and a lower influence of the harmonic current on the power supply compared with the common Scherbius system. This device is suitable for saving energy in ventilators and pumps. >
Journal Article•
TL;DR: In this article, the evolution of both the metric and topological properties of the microstructure for Ni pow- der compacts at the late stages of sintering has been investigated by means of stereological method.
Abstract: The evolution of both the metric and topological properties of the microstructure for Ni pow- der compacts at the late stages of sintering(V_v~s0.90)has been investigated by means of stereological method.The effects of precompaction pressure and loose sintering have been stu- died and discussed.
TL;DR: In this article, a transmission of the maclage mecanique de the phase α de Burgers lors de la deformation par traction a −75 o C dans l'alliage Ti-5Zr-3Nb.
TL;DR: In this paper, the boron-rich phase in the Nd-Fe-B magnet was investigated by means of electron diffraction and the results indicated that the fine structure of Nd 1+ϵFe4B4 compound exhibits variety with respect to those of X-ray diffraction.
TL;DR: In this article, a theoretical approach to the optimization of mine life and design capacity is developed. The objective is to maximize the future value of mineral reserve, and the concept introduced here may be used to evaluate the life and the design capacity of a mine for planning purpose or to analyze the effect of various parameters on the optimal mine life.
Abstract: The paper develops a theoretical approach to the optimization of mine life and design capacity. The objective is to maximize the future value of mineral reserve. The concept introduced here may be used to evaluate the life and design capacity of a mine for planning purpose or to analyze the effect of various parameters on the optimal mine life and design capacity.
TL;DR: The authors interpretation des donnees par l'approximation de difference finie, and presentation des resultats experimentaux, a.k.a. The authors.
TL;DR: In this article, the authors presented some results from numerical simulation using Boundary Element Method of failure process in Brittle Rock slopes and provided an analysis of progressive slope failure in brittle rocks.
Abstract: Current methods for analysis of slope stability, such as Bishop method, Janbu method and Samar method, are based on limiting equilibrium theory. The limiting equilibrium theory does not adequately explain failures in brittle rock slopes. This paper presents some results from numerical simulation using Boundary Element Method of failure process in Brittle Rock slopes. The simulation is based on the energy release concept as well as Mohr criterion of failure and provides an analysis of progressive slope failure in brittle rocks.
TL;DR: In this paper, the EDPs of Nd 1+ ϵ Fe 4 B 4 reveal the variety of the crystal structure and indicate that there exists a quasi-continuous series of compounds near the composition Nd1.1.
TL;DR: In this article, the minority phase Nd1+ϵFe4B4, also called the boron-rich phase, was investigated by means of X-ray and electron diffraction, electron microscopy and Mossbauer spectroscopy.
Abstract: The minority phase Nd1+ϵFe4B4, also called the boron-rich phase, in NdFeB magnets, has been investigated by means of X-ray and electron diffraction, electron microscopy and Mossbauer spectroscopy. The results indicate that the structure of this boron-rich phase is an incommensurate composite structure in the c direction in which two mutually incommensurate subsystems are involved. In addition, the fine structures revealed by electron diffraction studies are at variance with the results obtained from X-ray diffraction. High density planar faults always exist in the boron-rich phase in samples subjected to different heat treatments. In the cobalt-added system Nd1.1 (Fe1 − xCox)4B4(x = 0–1), a similar structural feature relating to dual periodicities also occurs. However, the two periods in the c direction vary with the composition. The low magnetic ordering temperature in the boron-rich phase implies an absence of momentum of the transition metals.
TL;DR: In this paper, a study of the geochemistry of inclusions from the Linglong Au deposit in Shandong Province shows that ore-forming temperature and pressure, frequency of appearance for critical inclusion, and saline halo of the main Au-bearing veins 108 and 51 increase in the direction of Linglong Fault.
TL;DR: In this paper, the contribution of Sm3+ ion to the magnetocrystalline anisotropy of SmTiFe11 has been calculated using the single ion theory, and the effect of the first excited state of Sm 3+ has been taken into consideration in the calculations.
Abstract: The magnetocrystalline anisotropy of SmTiFe11 has been studied. In addition to experimental investigations, the contribution of Sm3+ ion to the magnetocrystalline anisotropy of SmTiFe11 has been calculated using the single ion theory. The effect of the first excited state of Sm3+ has been taken into consideration in the calculations, and the calculated results are consistent with the experimental data.
TL;DR: In this paper, the simultaneous oxidation and sulfidation of Fe-25Cr and aluminum-rich alloys with 0.10 wt.% Al were studied at 1023, 1123, and 1223 K in H2H2O-H2S gas mixtures.
Abstract: The simultaneous oxidation and sulfidation of Fe-25Cr, Fe-25Cr-5Al and Fe-25Cr-10Al alloys were studied at 1023, 1123, and 1223 K in H2-H2O-H2S gas mixtures. Fe-25Cr and aluminum-rich alloys with 0–10 wt.% Al show, in H2H2O-H2S gas mixtures at high temperatures, a transition from protective oxide-scale formation to the formation of a sulfide-rich corrosion product. The kinetics boundary, which indicates the transition from oxide formation with slow weight gains to sulfide formation with rapid weight gains, has been found in these three alloys. The critical oxygen partial pressures to stabilize oxide formation at the constant-sulfur partial pressures of aluminum-rich Fe-25Cr alloys were systematically below those of Fe-25Cr alloy. When the oxygen partial pressure is much higher than the critical one, the oxide scale formed on the Fe-25Cr alloy was mainly Cr2O3 with a small amount of FeCr2O4; on the other hand, the oxide scale formed on the aluminum-rich Fe-25Cr alloys was mainly Fe(Cr,Al)2O4 with a small amount of Al2O3 and Cr2O3. The thermodynamic stability diagrams for (Fe, Cr, Al) -S-O systems were constructed, and the experimental results which show the existence of Fe(Cr, Al)2O4 in the simultaneous sulfidation and oxidation of aluminum-rich Fe-25Cr alloys are explained by these diagrams. The reaction kinetics were measured by a stainless-steel spring balance, and the reaction products were characterized by x-ray diffraction, Auger spectroscopy, and scanning electron microscopy. The reaction rate usually decreased with an increase of the oxygen partial pressure at a constant sulfur partial pressure. The existence of aluminum plays an important role to suppress the sulfidation of Fe-25Cr alloys.
TL;DR: In this paper, the effect of high order diffraction of crystal monochromator on the amplitude of EXAFS has been investigated and a method to correct the harmonic effect on EXAFs amplitude has been proposed.
Abstract: The effect on amplitude of EXAFS from harmonic caused by high order diffraction of crystal monochromator is discussed. The general expression and calculated results are presented. It is shown that the harmornic decreases the amplitude of EXAFS and the amount of decrease is related to such factors as intensity ratio of harmonic to fundamental, thickness and absorption coefficient of specimen. K edge EXAFS spectra with and without harmonic for different thickness copper foils have been measured respectively, and the distortion of single shell EXAFS amplitudes have been extracted. The measured results are consistent with calculated ones. Consequently, a method to correct the harmonic effect on EXAFS amplitude is proposed.
TL;DR: Etude par microscopie electronique a balayage et par spectrometrie Auger de la segregation du phosphore a l'interface fer/graphite as mentioned in this paper.
TL;DR: In this paper, in situ and dynamic observation of using a high voltage electron microscope as well as magnetic measurements of the SmCo 5 magnet has been made by using high voltage microscopes.
TL;DR: In this article, the analytical expressions of the anti-plane line force and its stress field have been obtained by means of direct integration, and the non-local line force has a Gaussian distribution.
01 May 1989