Concerning the trade-off between convergence and diversity in solving the multi-trip pickup and delivery Vehicle Routing Problem （VRP）， a hybrid Non-dominated Sorting Genetic Algorithm Ⅱ （NSGA-Ⅱ） combining Adaptive Large Neighborhood Search （ALNS） algorithm and Adaptive Neighborhood Selection （ANS）， called NSGA-Ⅱ-ALNS-ANS， was proposed. Firstly， considering the influence of the initial population on the convergence speed of the algorithm， an improved regret insertion method was employed to obtain high-quality initial population. Secondly， to improve global and local search capabilities of the algorithm， various destroy-repair operators and neighborhood structures were designed， according to the characteristics of the pickup and delivery problem. Finally， a Best Fit Decreasing （BFD） algorithm based on random sampling and an efficient feasible solution evaluation criterion were proposed to generate vehicle routing schemes. The simulation experiments were conducted on public benchmark instances of different scales， in the comparison experiments with the MA （Memetic Algorithm）， the optimal solution quality of the proposed algorithm increased by 27%. The experimental results show that the proposed algorithm can rapidly generate high-quality vehicle routing schemes that satisfy multiple constraints， and outperform the existing algorithms in terms of both convergence and diversity.

To solve the problems of three-dimensional clipping and Multi-Planar Reformation (MPR) that only the geometrical information of the tissues or organs can be obtained and the structure of a curving organ cannot be displayed in a single image, a Curved Planar Reformation (CPR) algorithm based on MPR to extract the outline was proposed to reform the coronary artery. Firstly, the discrete points expressing the outline of the coronary artery were extracted by using MPR. Afterwards, the Cardinal interpolation was used to get smooth outline fitting curve. Secondly, the outline was projected along the interested direction to get the scanning curved planar. Finally, the scanning curved planar corresponding to the volume data of the cardiac was displayed, so the CPR image of artery was got. The experimental results show that, compared with three-dimensional clipping method and three-dimensional data field method, the increment for the extracting speed of the coronary artery outline is about 4 to 6 frames per second, and the rendering time is shorter. On the aspect of rendering quality, compared with three-dimensional segmentation method, the image of coronary artery curved plane is clear and complete, which is helpful for doctors to analyze the lesion clearly and satisfies the demands of actual clinical diagnosis.

In order to overcome the rendering drawbacks of traditional algorithms that cannot be interacted fluently with the user and have a big time consumption and single rendering result, a ray casting algorithm based on Graphics Process Unit (GPU) was proposed to be used for the real-time volume rendering of medical tomographic images. Different rendering effects can be switched quickly by the proposed algorithm. Firstly, medical tomographic images were read into the computer memory to construct voxels. Afterwards, properties (interpolating, shading and light) of the corresponding voxels were set. The transfer functions of color and opacity were designed to display different organs and tissues. Finally, the volume data were loaded and the ray casting algorithm was executed by GPU. The experiments show that the rendering speed of the proposed algorithm can reach 40 frames per second, which satisfies the clinical application. On the aspect of rendering quality, jags produced in the process of interaction because of resampling on GPU are apparently lower than the ray casting algorithm on CPU. The time consumption of CPU-based ray casting algorithm is about 9 times that of the proposed algorithm.

The precision of the common network time protocol is low when being realized in the application layer, while high in physical layer yet a definite hardware is in need. With reference to the WinPcap time stamps management method of the famous network packet pawing software, a new high precision relative time synchronization algorithm was implemented with pure software in data link layer. Besides, the software was tested under Windows XP circumstance in an abbreviated LAN. The result indicates that the proposed algorithm can attain synchronization precision within 100μs.

Currently, many computers are required to cooperate frequently in the network application. Therefore, a uniform clock is in need. A new mechanism to realize clock synchronization in LAN by using CPU internal high-precision time stamp was presented; besides, the server and client software was also developed in VC++, and tested under Windows XP and Windows 2000 circumstance in an abbreviated LAN. The result indicates that the algorithm can attain much high synchronization precision, and the system runs steadily.