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[en] A conclusion can be summarized that there is regularity in nuclides' binding energies and specific binding energies by fitting a quadratic polynomial for each element after calculating these energy values. These values match some certain quadratic polynomials with mass numbers as independent variables. Some doubtful or unknown relative atomic masses are predictable by statistics method. (authors)
[en] A flexible, personal computer based, screen-graphics oriented pulse sequence editor called PULSE has been developed for nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI). PULSE is used to set such NMR spectroscopic parameters as the delay and duration of rf transmit and receive gates, rf phase, sampling times, and such imaging parameters as rf pulse shape and gradient waveforms. The output of PULSE is a set of programs that can be loaded into a hardware pulse programmer. With PULSE, any desired NMR or MRI pulse sequence can be programmed quickly and easily. 7 refs., 2 figs
[en] Highlights: • Oxygen distribution in unreduced and reduced powder section were systematically analyzed and compared, and the oxygen depth distribution curves fit well with exponential decay function shown as Y = f(x) = A1exp(− x/t1) + A2exp(− x/t2) + y0. • A model of particle oxygen distribution was set up for quantitative analysis of oxygen, which will be useful for further research of reduction kinetics. • The micro process of the reduction of oxides and the thickness decrease of the oxygen-rich layer were systematically analyzed. - Abstract: The characterization of surface oxides composition and the depth distribution of oxides in water-atomized steel powder is vital to adjust the reduction condition for sufficient removal of the oxides. To systematically analyze the composition, depth distribution and morphology of surface oxides in water-atomized low alloy steel powder containing manganese (0.3 wt.%), X-ray photoelectron spectroscopy (XPS) combined with Ar-cluster-ion sputtering, X-ray diffraction (XRD), scanning electron microscope (SEM) and energy disperse spectroscopy (EDS) were utilized. The results show that surface oxygen exists in the form of “Oxides Island”, and the surface oxygen content is much higher than the bulk. In the unreduced powder, the oxygen-rich surface layer contains 67% of total oxygen within a depth of 1800 nm (0.072R, R denotes the radius of the powder); while for the reduced powder, the oxygen-rich surface layer contains 28% of the total oxygen in the powder within a depth of 80 nm (0.0032R). The oxygen depth distribution curves fit well with exponential decay function as Y = f(x) = A1exp(− x/t1) + A2exp(− x/t2) + y0. The oxides mainly exist in the forms of γ-Fe2O3, FeO, Mn2O3 and MnO in the unreduced powder and γ-Fe2O3, FeO, Mn2O3 in the reduced powder
[en] In magnetic resonance imaging (MRI), the original data are sampled in the spatial frequency domain. The sampled data thus constitute a set of discrete Fourier transform (DFT) coefficients. The image is usually reconstructed by taking inverse DFT. The image data may then be efficiently compressed using the discrete cosine transform (DCT). A method of using DCT to treat the sampled data is presented which combines two procedures, image reconstruction and data compression. This method may be particularly useful in medical picture archiving and communication systems where both image reconstruction and compression are important issues. 11 refs., 3 figs
[en] Due to the complex and potentially dangerous of the nuclear power plant system. The safety of nuclear power plants (NPPs) has been of concern to the public. Therefore, it is of great significance to develop a fault detection and diagnosis system to reduce the decision-making pressure of operators and the potential danger after failure. Combined with the idea of distributed, the method of fault detection for NPPs based on thermal hydraulic simulation model is studied, and a distributed detection model based on mechanism simulation is established according to the actual measurement points in NPPs. In the process of synchronous operation of the model and the actual system, the residual vector is produced. Then, the method of principal component analysis is used to analysis the residual vector, which realizes the fault detection and initial location of the actual system. So as to realize the on-line monitoring of nuclear power plants. (author)
[en] The role of vaporisation in the evolution of surface micro-structural instability has been investigated in Ni-base superalloys during heat treatment below the solvus temperature. Initial nucleation of beta (β) grains at the surface with random orientations arose from vaporisation of Ni, Co and Cr with subsequent de-stabilisation of gamma (γ) phase. Further vaporisation and inter-diffusion resulted in a discontinuous reaction (secondary reaction zone - gamma prime (γ') matrix + topologically close packed phases with needle-like morphology). On the other hand, advancement of the secondary reaction zone grain boundary was shown to be dependent only on the solute supersaturation ahead of the boundary. The driving force for growth of the secondary reaction zone was calculated from the Gibbs energy change and nearly all of this force was available to pull the grain boundary.
[en] Iron-chalcogenide compounds with FeSe(Te, S) layers did not attract much attention until the discovery of high-Tc superconductivity (SC) in the iron-pnictide compounds at the begining of 2008. Compared with FeAs-based superconductors, iron-chalcogenide superconductors have aroused enormous enthusiasm to study the relationship between SC and magnetisms with several distinct features, such as different antiferromagnetic ground states with relatively large moments in the parents, indicating possibly different superconducting mechanisms, the existence of the excess Fe atoms or Fe vacancies in the crystal lattice. Another reason is that the large single crystals are easily grown for the iron-chalcogenide compounds. This review will focus on our exploration for the iron-chalcogenide superconductors and discussion on several issues, including the crystal structure, magnetic properties, superconductivity, and phase separation. Some of them reach a consensus but some important questions still remain to be answered. (topical review - iron-based high temperature superconductors)
[en] Along with the development of various new energy, concerns about the economy of nuclear power plants are growing. Performance monitoring and analysis system monitors the performance of the nuclear power plant (NPP), locates the cause of performance degradation, guides maintenance and operation. Finally, realize the purpose of improving the economy by reducing the effort of maintenance, improving the operation time and efficiency. In this paper, a distributed performance monitoring and analysis system for nuclear power plant is developed based on C Sharp. The method of distribution is used to model the thermal system of PWR. In the distributed model, the actual data detected from NPP is used as the boundary condition for partial exergy analysis. Meantime another exergy analysis is done under the ideal condition. By compare the two result, the condition of the NPP can be analyzed and the area which causes the performance degradation can be located. Furthermore, a human-machine interface, based on WinForm, is developed to display the parameters, condition of the NPP and the results of the analysis. (author)
[en] A new phosphor, Cd2Ge7O16:Mn2+, which emits orange-coloured long-lasting phosphorescence upon UV light excitation, was prepared by the conventional high-temperature solid-state method and its luminescent properties were systematically investigated. X-ray diffraction, photoluminescence and thermoluminescence spectra and lifetime decay curves were used to characterize the synthesized phosphor. This phosphor is well-crystallized by calcination at 950 C for 6 h and shows excellent performance. After irradiation under 258 nm UV light, this phosphor emits a broad band centred at 585 nm and shows obvious long-lasting phosphorescence. The colour coordinate values of this phosphor are x=0.56, y=0.46. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
[en] Based on the quasi-boson approach, a model of a Λ-type three-level atom coupled to a X-shaped coupled cavity arrays (CCAs) is used to study the transport properties of a single-photon in the dissipative case, and a classical field is introduced to motivate the one transition of the Λ-type three-level atom (ΛTLA). The analytical expressions of transmission and transfer rate are obtained. Our results show that the cavity dissipation will obviously weaken the single-photon transfer rate where the incident energy of the single photon is resonant with the excited energy of the atom. Whether the cavity dissipation exists or not, the single photon can be almost confined in the incident channel at large detuning, and we can regulate the intensity of the classical field to control the total transmission of the single-photon. Graphical abstract: .