Applied Mechanics and Materials Vols. 121-126

Abstract: Role-based access control (RBAC) has been adopted widely by reducing the complexity of the management of access control. The least privilege principle is a very important constraint policy of RBAC. A key problem related to this is the notion of goodness/interestingness – when is a role good Devising a complete and correct set of roles for supporting the least privilege principle has been recognized as one of the most important tasks in implementing RBAC. In this paper, to address this problem, we map this problem to a formal definition in mathematics – δ-approx least privilege mining (δ-approx LPM). We introduce a method named GABM to enforce LPM based on the generic algorithm. By GABM, the least privilege roles can be found out correctly. Our experiments display the effect of GABM. Finally, we conclude our work.

Abstract: Aimed at the inadequacy of the standard BP algorithm, a near optimal learning rate BP algorithm (NOLRBP) is presented. Selecting the learning rate of the algorithm based on one-dimensional search algorithm of optimization theory avoids the blindness in determining the learning rate. Simulations show that the algorithm is superior to the standard BP algorithm (SDBP), momentum BP algorithm (MOBP) and variable learning rate BP algorithm (VLBP).

Abstract: Aimed at the disadvantage of over-segmentation that traditional watershed algorithm segmented MRI images, a new method of MRI image segmentation was presented. First, through traditional watershed segmentation algorithm, the image was segmented into different areas, and then based on the improved kernel-clustering algorithm, we used Mercer-kernel to map average gray value of each area to high-dimensional feature space, making originally not displayed features manifested. In this way, we can achieve a more accurate clustering, and solve over-segmentation problem of watershed algorithm segmenting MRI images efficiently, thereby get better segmentation result. Experimental results show that the method of this paper can segment brain MRI images satisfactorily, and obtain clearer segmentation images.

Abstract: The paper established U75V 100-meter rail 3-D transient non-liner finite element analysis model about U75V 100-meter rail by using the large-scale non-liner finite element analysis software ABAQUS. By analyzing the different positions in the section of the temperature variation, the changes of bending degree and the residual stress variation after the bending deformation have changed. Based on the 100-meter straight rail in natural cooling under the cooling process, simulation results showed that in the cooling process, deflection change with time mainly divided into four stages; In consideration of the friction effect, the flat rail cold curve for its deformation among roughly flat, the curve about either ends, the scope for bending is 18 meters, the maximal displacement is 1.88 meters while the flat rail occured end colding.

Abstract: Traditional genetic algorithm trapped into the local minimum easily. Therefore, based on a simple genetic algorithm and combine the base ideology of orthogonal test then applied it to the population initialization, crossover operator, as well as the introduction of adaptive orthogonal local search to prevent local convergence to form a new orthogonal evolutionary algorithm. Through the series of numerical experiments, proved the efficiency of the new algorithm.

Abstract: A new way, which is used to analysis the path contribution, is presented for the vibration transfer path systems considering the interact of vibration source, transfer path and receiver. It is that the path contribution is evaluated using the path transfer probability. According to the dynamic characteristics of vibration systems, the new concept of path transfer probability is given. Based on the generalized probabilistic perturbation method and the reliability theory, the computational approach for path transfer probability with uncertain physics and geometry factors in time range are presented. The transfer probability of vibration transfer path systems with translational and rotational motions is analyzed and calculated via a numerical example, which shows that the proposed method is feasible.

Abstract: The appearance of pectoral muscle in medio-lateral oblique (MLO) views of mammograms can increase the false positive in computer aided detection (CAD) of breast cancer detection. Pectoral muscle has to be identified and segmented from the breast region in a mammogram before further analysis. The main goal of this paper is to propose an accurate and efficient algorithm of pectoral muscle extraction on MLO mammograms. The proposed algorithm bases on the positional characteristic of pectoral muscle in a breast region to combine the iterative Otsu thresholding scheme and the mathematic morphological processing to find the rough border of the pectoral muscle. The multiple regression analysis is then employed on the rough border to obtain the accurate segmentation of the pectoral muscle. The presented algorithm is tested on the digital mammograms from the Mammogram Image Analysis Society (MIAS) database. The experimental results show that the pectoral muscle extracted by the presented algorithm approximately follows that extracted by an expert radiologist.

Abstract: The flexure hinge is an important part of micro-displacement table in the precision instruments. To improve the performance of micro-displacement table, the key parameters of its flexure hinges: radius and thickness of hinge and length of connecting rods etc. are studied. Aiming at a commonly used parallel four-bar flexure hinges structure, the parameters of flexure hinge are optimized by using the genetic algorithm under the condition that the frequency of objective function approaches a maximum value.

Abstract: A new dual-objective scheduling method based on the controlled Petri net and GA is proposed to the job-shop scheduling problem (JSP) constrained by machines, workers. Firstly, a detailed analysis of supervisory control for Petri net with uncontrollable transitions, especially important, for OR-logics linear constraint, a new method for constructing a Petri net feedback controller based on monitor and inhibitor arcs is presented. The Petri net model is constructed based on above method in flexible JSP. Then, the genetic algorithm (GA) is applied based on the controlled Petri net model and Pareto. Function objectives of the proposed method are to minimize the completion time and the total expense of machines and workers. Finally, Scheduling example is employed to illustrate the effectiveness of the method.

Abstract: The thesis introduces traffic patterns definition and identification. Combined with actual project it has established the regional traffic signal coordination and control system based on particle swarm K-means clustering algorithm pattern identification. It puts forward system structure and working principles with discussions focused on several key problems existing in traffic pattern identification process.