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[en] This thesis consists of three papers. Paper 1 deals with the semiclassical approximation for a Schroedinger operator in one dimension with an arbitrary continuous potential. The basic result is that function in the range of a spectral projection associated with an interval are exponentially small (with respect to Plancks parameter h) in places where the potential exceeds the interval. As an application of this result, it is shown that the eigenvalues of the operator localized to the wells appear as resonances of the global operator. This is true also when the potential is not bounded from below. Such results were proved before for analytic potentials by analytic dilatation. In Paper 2, the potential is assumed to have the form of χ + V(χ) (the Stark Hamiltonian) with a well-behaved V(χ), an explicit spectral and scattering theory for such an operator was presented using the time-independent approach. In particular, we derive an eigenfunction expansion theorem which, combined with a construction of an intertwining operator, gives a solution of the inverse scattering problem according to L. Daddeev and A. Melin. The direct part of the second paper has a generalization to higher dimensions, and this was done in the third paper. Also in that paper, the condition on the potentials for doing the inverse scattering theory was relaxed, and an explicit formula for the potentials involving the first approximation of the scattering data was given
[en] IrO2/SnO2 (10%:90%, molar ratio) electrodes (ITEs) were prepared by the sol-gel method as an alternative to the electrodeposition and thermal decomposition process. The electrodes were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM), cyclic voltammetry (CV) and electrochemical impedance spectra (EIS). From the results of XRD, oxide films prepared at low temperature were in amorphous state, while hydrous IrO2 crystal and cassiterite phase SnO2 were formed at 300 deg. C or even to 500 deg. C. The highly porous structure was confirmed by AFM. The electrochemical experiments demonstrated that the sol-gel method made the ITEs having a fast electron transfer process with good stability and the optimal preparation temperature was 400 deg. C for the highest electroactivity. Furthermore, the electrocatalysis of pyrocatechol on the electrodes was investigated. A quasi-reversible process occurred and a linear range over three orders magnitude (1 x 10-2-10 mM) was obtained by differential pulse voltammetry (DPV). Meanwhile the detection limit of pyrocatechol was 5 x 10-3 mM. This study indicated that the sol-gel method was an appropriate route to prepare the IrO2/SnO2 electrodes for the electrocatalytic of pyrocatechol
[en] Eu2+, Dy3+ co-doped strontium aluminate (SrAl2O4) phosphor nanometer powders with high brightness and long afterglow were prepared by heating the precursor gel (resulted from sol-gel method) at 900 deg. C and a reductive atmosphere of active carbon. The average particle size of the SrAl2O4:Eu, Dy phosphor powders was 59±7 nm and its optical properties have been studied systematically. The broad band UV excited luminescence of the SrAl2O4:Eu, Dy was observed at λmax=506 nm due to transitions from the 4f65d1 to the 4f7 configuration of the Eu2+ ion. The results indicated that the main peaks in the emission and excitation spectrum shifted to the short wavelength compared with phosphor obtained by the solid-state reaction synthesis method. The decay speed of the afterglow for nanometer phosphors was faster than that obtained by the solid-state reaction method
[en] Acid dissolution method is that with intensively oxidation acid to decompose ion exchanging resins and dissolving U and Fe ion in water, then menstruate the U content by titration. Comparing with our current method of filtering wash, acid dissolution menstruation U can get more accurate result and take less time, use more simple device. (authors)
[en] Describe in detail the design requirements, performance characteristics, normal and abnormal operation of overall plant control system of Qinshan Phase Ⅲ Nuclear Power Plant, as the function and configuration of the digital control computer system, which is in charge of overall plant control. (authors)
[en] We employ a ghost model of interacting dark energy to obtain the equation of state ω for ghost energy density in an FRW universe in complex quintessence theory. We reconstruct the potential and study the dynamics of the scalar field that describes complex quintessence cosmology. We perform ω−ω′ analysis and stability analysis for both non-interacting and interacting cases and find that the same basic conclusion as for the real model, where ω′=dω/dlna. Taking account of the effect of the complex part and assuming the real part of the quintessence field to be a slow-rolling field, we conclude that the non-interacting model cannot describe the real universe since this will lead to fractional energy density Ω > 1, where Ω can be defined as the ratio of ρ to ρ. However, for the interacting case, if we take present Ω = 0.73, then we can determine that b = 0.0849, where b is the interaction coupling parameter between matter and dark energy. In the real quintessence model, Ω and b are independent parameters, whereas in the complex quintessence model, we conclude that there is a relationship between these two parameters.
[en] As a result of dimensional limit in narrow gap, bubbles are deformed and coalesced by squeeze as they are growing and flowing along a heating narrow channel. And their surface tension effects are altered greatly. A flow boiling heat transfer correlation is putted forward by modifying the Chen correlation with dimensionless Bond number, which considers the geometrical effect of narrow channel and bubble surface tension effect. The calculation results with the modified Chen correlation and original Chen correlation are compared with experimental data and it shows that the modified Chen correlation agrees well with the experimental data. Herewith, the correlation can be used to predict two-phase flow boiling heat transfer coefficient in narrow channel with one side heating
[en] Highlights: • All gases in the improved diffusion layer model are considered to be real gases. • New modified equation of the relation between P_v and x_v is developed. • Obtain the analytical expression of heat transfer coefficient at high pressure. • Compression factor of vapor is a key factor at high pressure. • Gas/vapor mean concentration ratio is a ternary function of thermal parameters. - Abstract: Condensation heat transfer in the presence of non-condensable gas is a vital problem in the nuclear engineering applications, such as the gas-steam pressurizer design, and heat removing on containment in the case of postulated accident. An improved diffusion layer model of condensation heat transfer at high pressure is presented in the vapor domination region, and it shows the influence of the pressure in the film condensation in presence of non-condensable gas. All gases in this improved model are considered to be real gases as the compressibility factor of gas is utilized. New modified equations are developed to describe the relation between partial pressure and mole fraction, and an approximate analytical solution for heat transfer coefficient in the presence of non-condensable gas is obtained. The analysis result indicates that the compressibility factor of vapor has a great effect on the condensation heat transfer coefficient in the vapor domination region at high pressure, whereas the compressibility factor of the non-condensable gas does not. The gas/vapor mean concentration ratio is a ternary function of vapor compressibility factor, gas mean concentration and vapor mean concentration instead of a binary function of gas mean concentration and vapor mean concentration in the previous model based on ideal gas assumption. The deviation of these two gas/vapor mean concentration ratios is about 30% when the total pressure is about 16.0 MPa and the mole fraction of non-condensable gas is less than 2%. Compared with the experimental data, it has been proven that this improved model can get good applicability and accuracy
[en] The gamma-ray spectra of pentane (C_5H_1_2) and its two isomers, i.e., 2-Methylbutane (CH_3C(CH_3)HC_2H_5) and 2,2-Dimethylpropane (C(CH_3)_4) have been studied theoretically in the present work. The recent experimental gamma-ray spectra of these three molecules show that they have the same Doppler shifts, although their molecular structures are dramatically different. In order to reveal why the gamma-ray spectra of these molecules are less sensitive to the molecular structures, the one-dimensional gamma-ray spectra and spherically averaged momentum (SAM) distributions, the two-dimensional angular correlation of annihilation radiation (ACAR), and the three-dimensional momentum distributions of the positron–electron pair are studied. The one-centered momentum distributions of the electrons are found to play more important role than the multi-centered coordinate distributions. The present theoretical predictions have confirmed the experimental findings for the first time. The dominance of the inner valence electrons in the positron–electron annihilation process has also been suggested in the present work. - Highlights: • The structure effects only play a minor role in the one-dimension gamma-ray spectra. • The present study further confirms the dominance of the inner valence electrons in the positron–electron annihilation process. • The momentum distributions of the electrons play more important role than the coordinate distributions.
[en] China is experiencing rapid motorization and each city has a unique motorization pathway owing to its different characteristics and development progress. The temporal and spatial variation trend in on-road energy use and CO2 emissions need to be better understood in order to project the future growth and to support policy-making at both local and national levels. This study simulates the on-road energy use and CO2 emissions of all of China's prefectural-level cities (and above) from 1978 through 2008, on the basis of the collected vehicle data from hundreds of national and local statistical yearbooks. The results show that China's on-road energy use and CO2 emissions were 119 million metric tons (MMT) and 377 MMT in 2008, respectively—20 times the levels in 1978. The economically developed cities and heavy industrial cities had the highest on-road energy use and CO2 emissions before the year 2000, but recently the spatial distribution has varied significantly as the uptake of motorization increases successively in these cities. Now and in the near future, the most important driving force of the on-road energy and CO2 growth in China is the great number of average cities that have just started or will soon start the motorization. - Highlights: • China's cities have unique motorization pathways due to their unique characteristics. • We simulate on-road energy use and CO2 emissions of all cities in China in 1978–2008. • China's on-road energy use and CO2 emissions in 2008 were 20 times the levels in 1978. • Large cities had the highest on-road energy usage but the growth rate is declining. • Non-large cities are the main impetus of the growth in China's on-road energy use