The Method of Characteristics (MOC) which can calculate arbitrary geometry neutron transport equation becomes more and more popular and is adopted in many neutron transport codes. However, the MOC codes with Flat Sour...
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ISBN:
(纸本)9781615673490
The Method of Characteristics (MOC) which can calculate arbitrary geometry neutron transport equation becomes more and more popular and is adopted in many neutron transport codes. However, the MOC codes with Flat Source Approximation (FSA) needs large storage space and long computing time when calculating large-scale three dimensional neutron transport problems. This paper proposes a new source approximation called Linear Source Approximation (LSA). By calculating several three dimensional neutron transport problems using the codes with FSA and LSA respectively, it was shown that the LSA MOC code gets more accurate results than the FSA MOC code with the same spatial meshes, and that the LSA MOC code with large meshes can get the results with the same accuracy of the FSA MOC code with fine spatial meshes. By using large spatial meshes which means there are less meshes and ray trajectories to store in memory, the LSA MOC code can calculate the three dimensional neutron transport problems with less storage and shorter computing time than FSA MOC code with fine meshes. Therefore, it is concluded that LSA MOC with large spatial meshes is able to calculate large-scale three dimensional problems with reasonable storage space and computing time.
Ecological traffic tunnel means that the manner can deal with tunnel project environmental problem of surrounding area and it is most close to the green environment. In general, we always use artificial light sources,...
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This paper introduces the shortage of the traditional tolerance design method and the strongpoint of the computer aided tolerancing (CAT) method, compares the shortage and the strongpoint among the three tolerance ana...
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This paper introduces the shortage of the traditional tolerance design method and the strongpoint of the computer aided tolerancing (CAT) method, compares the shortage and the strongpoint among the three tolerance analysis methods, which are Worst Case Analysis, Statistical Analysis and Monte-Carlo Simulation Analysis, and offers the basic courses and correlative details for CAT. As the study objects, the reactor pressure vessel, the core barrel, the hold-down barrel and the support plate are used to upbuild the tolerance simulation model, based on their 3D design models. Then the tolerance simulation analysis has been conducted and the scheme of the tolerance distribution is optimized based on the analysis results.
A new method for evaluating roundness error using polar measurement data, which named as polar mesh searching algorithm (PMSA), has been presented in this paper. The principle of the algorithm was that series of polar...
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A new method for evaluating roundness error using polar measurement data, which named as polar mesh searching algorithm (PMSA), has been presented in this paper. The principle of the algorithm was that series of polar-coordinate mesh points were collocated around the periphery of the least square circle according to certain rule, the radius of all the measured points were calculated by regarding each mesh point as the ideal center, and the roundness error from minimum circumscribed circle method, maximum inscribed circle method and minimum zone circle method were achieved accurately through comparing these radius. In the paper, the process and steps using the PMSA to solve the roundness error were described in detail and the mathematical formula and program flowchart were given. The simulation and experiment results show that roundness error can be evaluated effectually and accurately by this algorithm.
This paper presents a case study of development of a 6-axis robotic arm controller. The robot is powered by a hydraulic pump. The position of each axis can be derived from its potentiometer voltage. At each and every ...
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This paper presents a case study of development of a 6-axis robotic arm controller. The robot is powered by a hydraulic pump. The position of each axis can be derived from its potentiometer voltage. At each and every axis, a servo-valve is employed to control a servo motor. Its relative velocity is related to the servo-valve input. With 2 nd order PID controller, a micro-controller commands movements of all axes. The PID inputs are the six voltages from potentiometers and its outputs are the six DC voltages, which command the six servo-valves. A trajectory file is generated by solving the inverse kinematics problem with some (angular to digital value) conversions. A special case; closed-form calculation is developed to solve kinematics problem. With some constraints it only yields one solution. Experiments show that robot follow the given trajectory with acceptable errors.
A discrete ordinates method for a threedimensional first-order neutron transport equation based on unstructured-meshes that avoids the singularity of the second-order neutron transport equation in void regions was ***...
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A discrete ordinates method for a threedimensional first-order neutron transport equation based on unstructured-meshes that avoids the singularity of the second-order neutron transport equation in void regions was *** finite element variation equation was obtained using the least-squares method.A three-dimensional transport calculation code was *** the triangular-z and the tetrahedron elements were *** numerical results of some benchmark problems demonstrated that this method can solve neutron transport problems in unstructuredmeshes very *** most problems,the error of the eigenvalue and the angular flux is less than 0.3% and 3.0% respectively.
Fuel assembly grids of pressurized water reactor strengthen the coolant mixing around fuel rod through mixing structure. The size and shape of mixing vane affects the mixing performance and flow resistance. This paper...
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Fuel assembly grids of pressurized water reactor strengthen the coolant mixing around fuel rod through mixing structure. The size and shape of mixing vane affects the mixing performance and flow resistance. This paper introduces the process and result of grid mixing performance optimizing design. Using CFD software, three dimensional flow field of three grid design schemes are analyzed and compared. The results show that the mixing performance of scheme 3 is better than that of scheme 1 and 2 in terms of the highest fluid temperature and the most difference in temperature. And mixing performance of scheme 1 and 2 is better than that of scheme 3 in terms of typical channel average temperature.
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