Results 1 - 10 of 720
Results 1 - 10 of 720. Search took: 0.025 seconds
|Sort by: date | relevance|
[en] Remote-Field Eddy Current (RFEC) technology is a kind of new eddy current method of nondestructive testing for tubes. It performs testing by low frequency eddy current that can penetrate the tube wall. It can be used for testing of not only nonferromagnetic conducting material tube but also ferromagnetic tube. RFEC has almost the same sensitivity on both inside and outside of the tube wall to detect the defects such as indentation, crack and thickness lose, ignore the skin effect. These advantages make it important to research and develop RFEC method. Before, the research of RFEC technique is merely theoretical analysis and compute-aided simulation in the country. For a long time research, the authors developed the single- and multi-channel RFEC testing instruments which can be used in the inspection of small-bore tube. From 1994 to 1995, the authors successfully examined the carbon steel tube of high-pressure feedwater heaters in the Qinshan Nuclear Power Plant two times with RFEC method, that is very helpful to safe operation of the Nuclear Power Plant. The good public beneficial and economic results have been gained
[en] Cathodic plasma electrolysis was conducted in 1-propanol solutions and submicron diamond carbon was synthesized by the plasma electrochemical reactions under atmospheric pressure. The structure of the carbon particles was characterized by X-ray photoelectron spectroscopy, Raman spectroscopy and transmission electron microscopy. The effects of applied potential difference and treatment time on the structure of the prepared carbon products of PE processes were studied
[en] Based on characteristics of nuclear island layout design, the large number files and complicated interface, for realizing collaborative design and fine management goal, Establish collaborative design platform, which includes the design task module, 3D design module, project management module. These three modules can package design input files, realize synchronous design and real-time track design drawings state, timely feedback between design, procurement, construction site. There is no design task delay due to tracking and has realized fine management of design. (authors)
[en] Highlights: • Layered Li[Li0.2Ni0.2−xMn0.6−xMg2x]O2 (2x = 0, 0.01, 0.02, 0.05) were synthetized. • Li[Li0.2Ni0.2−xMn0.6−xMg2x]O2 exhibit enhanced electrochemical properties. • The improved performance is attributed to enhanced structure stability. -- Abstract: Mg-doped Li[Li0.2Ni0.2Mn0.6]O2 as a Li-rich cathode material of lithium-ion batteries were prepared by co-precipitation method and ball-milling treatment using Mg(OH)2 as a dopant. Scanning electron microscopy (SEM), ex situ X-ray powder diffraction (XRD), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvantatic charge/discharge were used to investigate the effect of Mg doping on structure and electrochemical performance. Compared with the bare material, Mg-doped materials exhibit better cycle stabilities and superior rate capabilities. Li[Li0.2Ni0.195Mn0.595Mg0.01]O2 displays a high reversible capacity of 226.5 mAh g−1 after 60 cycles at 0.1 C. The excellent cycle performance can be attributed to the improvement in structure stability, which is verified by XRD tests before and after 60 cycles. EIS results show that Mg doping decreases the charge-transfer resistance and enhances the reaction kinetics, which is considered to be the major factor for higher rate performance
[en] The second-harmonic generation (SHG) circular dichroism in the light of reflection from chiral films of tripod-like chiral molecules is investigated. The expressions of the second-harmonic generation circular dichroism are derived from our presented three-coupled-oscillator model for the tripod-like chiral molecules. Spectral dependence of the circular dichroism of SHG from film surface composed of tripod-like chiral molecules is simulated numerically and analysed. Influence of chiral parameters on the second-harmonic generation circular dichroism spectrum in chiral films is studied. The result shows that the second-harmonic generation circular dichroism is a sensitive method of detecting chirality compared with the ordinary circular dichroism in linear optics. All of our work indicates that the classical molecular models are very effective to explain the second-harmonic generation circular dichroism of chiral molecular system. The classical molecular model theory can give us a clear physical picture and brings us very instructive information about the link between the molecular configuration and the nonlinear processes
[en] We use Monte Carlo method to study three-state Potts model on maple leaf lattice with pure three-site interaction. The critical behavior of both ferromagnetic and antiferromagnetic cases is studied. Our results confirm that the critical behavior of the ferromagnetic model is independent of the lattice details and lies in the universality class of the three-state ferromagnetic Potts model. For the antiferromagnetic case the transition is of the first order. We have calculated the energy jump and critical temperature in this area. We find there is a tricritical point separating the first order and second order phases for this system.
[en] A periodic density functional theory (DFT) was utilized to calculate the dissociation process of methane (CH4) on Pt(1 1 1), Ir(1 1 1) and PtIr(1 1 1) surfaces. As compared to the adsorption energy, the most stable configurations of methane, methane dissociation species and co-adsorption of CHx (x = 0–3) with H were obtained. The kinetic results of the CH4 dissociation indicated that the dissociating of CH4 into CH3 and H is the rate-limiting step on the PtIr(1 1 1) and Ir(1 1 1) surfaces. CH was the most abundant species that was difficult to dehydrogenate into C and H. Particularly, the activation barrier for CH3 → CH2 + H and CH2 → CH + H on the Pt(1 1 1) surface is 3.5 and 1.4 times, respectively, higher than that on the PtIr(1 1 1) surface. According to the thermodynamics principles, the successive dehydrogenation of CH4 preferred to take place on the PtIr surface.
[en] A series of Ce"3"+ or Tb"3"+ doped and Ce"3"+/Tb"3"+ co-doped Ba_2ZnSi_2O_7 phosphors were prepared via the conventional high temperature solid state reaction method. The photoluminescence and energy transfer properties of samples were studied in detail. The optimal proportion of Ce"3"+ single doping is 2 mol% with maximal fluorescence intensity. Ba_1_._9_8_−_xZnSi_2O_7:0.02Ce"3"+, xTb"3"+ shows both a blue emission (428 nm) from Ce"3"+ and a yellowish-green emission (542 nm) from Tb"3"+ with considerable intensity under ultraviolet (UV) excitation (352 nm). The emission chromaticity coordinates can be adjusted from blue to green region by tuning the concentration of Tb"3"+ ions from 0.00 to 0.06 through an energy transfer process. The energy transfer mechanism from Ce"3"+ to Tb"3"+ ions was proved to be dipole–dipole interaction. The Ce"3"+ and Tb"3"+ co-doped Ba_2ZnSi_2O_7 phosphors are potential UV-convertible candidates with green light emitting in UV-LEDs for the high efficient energy transfer from Ce"3"+ to Tb"3"+ ions. - Highlights: • The emission color can be adjusted from blue to green region by tuning the concentration of Tb"3"+ ions. • There is very high transfer efficiency with the maximal value 84.4% from Ce"3"+ to Tb"3"+. • The energy transfer mechanism from Ce"3"+ to Tb"3"+ ions was proved to be dipole–dipole interaction
[en] Through analysing and researching on opening sealing situation and characters of nuclear buildings in CPR1000 nuclear power plant, a method of sealing criteria identifying standards is provide, while considering equipments attributes, safety function, radiation protection requirement, ALARA principle, the neighboring rooms affection, and so on. This article can provide some references to plugging of other-type nuclear power plants. (authors)