A Compton camera consisting of a CZT pixel detector and a NaI scintillator array was proposed. Factors that affect angular resolution of the camera, including geometry of detectors, energy resolution and Doppler effect of CZT detector, were analyzed. Overall angular resolution was between 5.1° and 5.6° and geometry of detectors was confirmed as main factor that limits angular resolution of the camera. A filtered-back projection algorithm was analytically deduced. The angular resolution was 1.7° as broadening was omitted, and 4.2° as broadening was considered. Geant4 simulations were performed and the data were reconstructed with a practical method of filtered-back projection algorithm. Angular resolution was 1.7° as broadening was omitted and 5.1° as practical broadening factors of Compton camera was considered. Parallel acceleration with GPU in the framework of OpenCL was applied in the reconstruction and the acceleration ratio was 79.

Based on Tricomi formula for Hilbert transform and Taylor expansion of cosh-function, a numerical inversion algorithm for cosh-Hilbert transform (CHT) is proposed and applied to single photon emission computed tomography imaging. CHT of a function is represented as its Hilbert transform and a correction term including all of its moments by using Taylor expansion of cosh-function. A linear system about all moments of the function is obtained via Tricomi formula. Finite numbers of moments can be solved by truncating the infinite linear system, and the function can be reconstructed approximately. Numerical simulations are performed to verify the algorithm by comparing with analytical inversion formula.

With computational fluid dynamics method, effect of embankment inclining angle on aerodynamic characteristics of high speed train under crosswinds is explored. It shows that as inclining angle of embankment is increased, side force coefficient on head train is increased a little and then decreased. Side force coefficient on middle train is gradually decreased. Side force coefficient on rear train is decreased a little and then increased as the angle reaches 47.5°. Negative lifting force coefficient on middle train is increased and lifting force coefficient on rear train is sensitive to inclining angle of embankment. The flow field around train is transformed as the inclining angle of embankment is changed and aerodynamic force or moment is changed consequently.

To understand performance of molten salt heat transfer and thermal storage in solar thermal power system, thermodynamic properties of cubic KNO₂ under atmospheric pressure and temperatures between 300 and 725 K are studied with density functional theory combined with a quasi-harmonic Debye model. Temperature dependence of isobaric heat capacity, isochoric heat capacity, entropy, Debye temperature, volume thermal expansion coefficient, equilibrium volumes and bulk modulus under ambient pressure are calculated. It shows that calculated isobaric heat capacities are in good agreement with experiments under ambient pressures. Both entropy vary greatly. The average volume thermal expansion coefficient-is 1.837 8×10^-5K^-1 and Debye temperature is 667.13K at ambient temperatures, respectively.

Three dimensional unsteady natural convective heat transfer in an inclined cubic enclosure with porous medium is studied numerically. The right side wall (X=1) of the enclosure is kept at a constant temperature of T_o, Temperature of the opposite vertical wall (X=0) varies by sine law with a mean value of T_o. Other walls are kept adiabatic. A Brinkman-extended Darcy model is used to describe flow through porous medium in the enclosure and the equations are solved with SIMPLE algorithm. Inclination angle α1 rotating around Y coordinate varies between 0å and 90°. Inclination angle α2 rotating around X coordinate varies between 0° and 45°. Dimensionless temperature oscillation frequency f ranges from 5° to 90π. Effects of inclination angles and temperature oscillation frequency on heat transfer are studied in detail. It shows that the maximal heat transfer is achieved at an inclined angles α1=46°, α2=45° and a temperature oscillating frequency f=45π.

A finite difference beam propagation method (FD-BPM) is analyzed and assessed for the application to two-dimensional structures.The general formulations for the FD-BPM are derived form Maxwell equations for TE mode and TM mode respectively,with the transparent boundary condition (TBC).The FD-BPM is assessed by computing the loss caused by the numerical error and the percentage error of the propagation constants of the TE and TM modes of a step-index slab waveguide.Based on this assessment,FD-BPM appears to be a good tool for the analysis and simulation of the optical waveguide devices and a exellent method for the computer-aided-design in Integrated Optoelectronics.