A Scheduling Algorithm for Flexible Manufacturing Cell

In this paper, a new scheduling algorithm for the flexible manufacturing cell is presented, which is a discrete time control method with fixed length control period combining with event interruption. At the flow control level we determine simultaneously the production mix and the proportion of parts to be processed through each route. The simulation results for a hypothetical manufacturing cell are presented.

地震层析成像与天山地区的壳幔深部结构研究

The Tien Shan is the most prominent intracontinental mountain belt on the earth. The active crustal deformation and earthquake activities provide an excellent place to study the continental geodynamics of intracontinental mountain belt. The studies of deep structures in crust and upper mantle are significantly meaningful for understanding the geological evolution and geodynamics of global intracontinental mountain belts. This dissertation focuses on the deep structures and geodynamics in the crust and upper mantle in the Tien Shan mountain belt. With the arrival time data from permanent and temporal seismic stations located in the western and central Tien Shan, using seismic travel time tomographic method, we inversed the P-wave velocity and Vp/Vs structures in the crust and uppermost mantle, the Pn and Sn velocities and Pn anisotropic structures in the uppermost mantle, and the P-wave velocity structures in the crust and mantle deep to 690km depth beneath the Tien Shan. The tomographic results suggest that the deep structures and geodynamics have significant impacts not only on the deformations and earthquake activities in the crust, but also on the mountain building, collision, and dynamics of the whole Tien Shan mountain belt. With the strongly collision and deformations in the crust, the 3-D P-wave velocity and Vp/Vs ratio structures are highly complex. The Pn and Sn velocities in the uppermost mantle beneath the Tien Shan, specially beneath the central Tien Shan, are significantly lower than the seismic wavespeed beneath geological stable regions. We infer that the hot upper mantle from the small-scale convection could elevate the temperature in the lower crust and uppermost mantle, and partially melt the materials in the lower crust. The observations of low P-wave and S-wave velocities, high Vp/Vs ratios near the Moho and the absences of earthquake activities in the lower crust are consistent with this inference. Based on teleseismic tomography images of the upper mantle beneath the Tien Shan, we infer that the lithosphere beneath the Tarim basin has subducted under the Tien Shan to depths as great as 500 km. The lithosphere beneath the Kazakh shield may have subducted to similar depths in the opposite direction, but the limited resolution of this data set makes this inference less certain. These images support the plate boundary model of converge for the Tien Shan, as the lithospheres to the north and south of the range both appear to behave as plates.

反射地震转换波成像方法研究

Multi-waves and multi-component get more and more attentions from oil industry. On the basis of existent research results, My research focuses on some key steps of OBC 4C datum processing. OBC datum must be preprocessed quite well for getting a good image. We show a flow chart of preprocess including attenuation of noise on multi-component datum、elimination ghost by summing P and Z and rotation of horizontal components. This is a good foundation for the coming steps about OBC processing. How to get exact converted point location and to analyze velocity are key points in processing reflection seismic converted wave data. This paper includes computing converted point location, analyzing velocity and nonhyperbolic moveout about converted waves. Anisotropic affects deeply the location of converted wave and the nonhyperbolic moveout. Supposed VTI, we research anisotropic effect on converted wave location and the moveout. Since Vp/Vs is important, we research the compute method of Vp/Vs from post-stack data and pre-stack data. It is a part of the paper that inversing anisotropic parameter by traveltime. Pre-stack time migration of converted wave is an focus, using common-offset Kirchhoff migration, we research the velocity model updating in anisotropic media. I have achieved the following results: 1) using continued Fractions, we proposed a new converted point approximate equation, when the offset is long enough ,the thomsen’s 2 order equation can’t approximate to the exact location of converted point, our equation is a good approximate for the exact location. 2) our new methods about scanning nonhyperbolic velocity and Vp/Vs can get a high quality energy spectrum. And the new moveout can fit the middle and long offset events. Processing the field data get a good result. 3) a new moveout equation, which have the same form as Alkhalifah’s long offset P wave moveout equation, have the same degree preciseness as thomsen’s moveout equation by testing model data. 4) using c as a function of the ratio offset to depth, we can uniform the Li’s and thomsen’s moveout equation in a same equation, the model test tell us choice the reasonable function C can improve the exact degree of Li’s and thomsen’s equation. 5) using traveltime inversion ,we can get anisotropic parameter, which can help to flat the large offset event and propose a model of anisotropic parameter which will useful for converted wave pre-stack time migration in anisotropic media. 6）using our pre-stack time migration method and flow, we can update the velocity model and anisotropic parameter model then get good image. Key words: OBC, Common converted Point (CCP), Nonhyperbolic moveout equation, Normal moveout correction, Velocity analysis, Anisotropic parameters inversion, Kirchhoff anisotropic pre-stack time migration, migration velocity model updating

On the evaluation of diffusivities in gels using the diffusion cell technique

Modeling of the gel-immobilized cell system requires accurate measurement of diffusion coefficients. Three methods of the quasi-steady-state (QSS) method, the time-lag (TL) method and a variant quasi-steady-state (VQSS) method were critically assessed and compared for the evaluation of diffusivities using the diffusion cell technique. Experimental data from our laboratory were used for the analysis of the influence of crucial theoretical assumptions not being fulfilled in each method. The results highlighted a risk in obtaining highly variable diffusion coefficients by not validating the QSS and the accuracy of the measurements. In the TL method, the estimation of diffusivities based on the plot intercept that was mostly used in the literature, results in a many fold lower value when compared to that based on the plot slope. The comparison with the QSS and VQSS methods confirmed similar diffusivity obtained by the TL method based on the plot slope. It thus suggested that the correct estimation of diffusivities by the TL method could be based on the plot slope only. Furthermore, the errors associated with the solute mass in the gel, the sample withdrawal and the non-negligible concentration changes in the chambers were also discussed. It is concluded that diffusion cell technique has to be employed cautiously for a correct evaluation of diffusivities. (C) 2001 Elsevier Science B.V. All rights reserved.