Applied Mechanics and Materials Vols. 58-60

Abstract: Double precision floating point matrix operations are wildly used in a variety of engineering and scientific computing applications. However, it’s inefficient to achieve these operations using software approaches on general purpose processors. In order to reduce the processing time and satisfy the real-time demand, a reconfigurable coprocessor for double precision floating point matrix algorithms is proposed in this paper. The coprocessor is embedded in a Multi-Processor System on Chip (MPSoC), cooperates with an ARM core and a DSP core for high-performance control and calculation. One algorithm in GPS applications is taken for example to illustrate the efficiency of the coprocessor proposed in this paper. The experiment result shows that the coprocessor can achieve speedup a factor of 50 for the quaternion algorithm of attitude solution in inertial navigation application compare with software execution time of a TI C6713 DSP. The coprocessor is implemented in SMIC 0.13μm CMOS technology, the synthesis time delay is 9.75ns, and the power consumption is 63.69 mW when it works at 100MHz.

Abstract: In order to reduce the field of the acoustic radiation and improve the efficiency of energy using, a new-style ultrasonic linear array is present, which base on the special structural of the acoustic field produced by the cylindrical acoustic lens. The new-style linear array is composed of numbers of cylindrical acoustic lens, each lens act as an element distributed in a line along the width direction. Define x-direction is the direction of wave propagate. We have studied the acoustic field theoretically and have analyzed it numerically. Found that acoustic field have a better directivity in y-direction and the radiation field is much smaller than the traditional linear array, at the same time the focus ability is appear in the Z-direction if we control the number of element and the distance of center-to-center spacing of each element. This paper is helpful to the change and development of traditional liner array.

Abstract: Recently, research on new mufflers lined with sound-absorbing material has been addressed in the industrial field. On the basis of the transfer matrix method and the stiffness matrix method, most researchers have explored noise reduction effects. Yet, the maximum noise reduction of a compact silencer equipped with sound-absorbing splitters within a constrained space, which often occurs in modern industries, has been ignored. Therefore, the optimum design of mufflers becomes essential. In this paper, a one-chamber muffler equipped with multiple sound-absorbing panels within a fixed length is assessed. In order to facilitate the assessment of optimal mufflers having multiple sound-absorbing splitters, an approximated simplified objective function (OBJ) is established in advance by linking the boundary element model (BEM) with a polynomial neural network fitted with a series of real data, input design data (muffler dimensions) and output data obtained by BEM simulation. To assess the optimal mufflers, a genetic algorithm (GA) is applied. Before the GA operation can be carried out, the accuracy of the mathematical models must be checked using the experimental data. On the basis of the fixed total thickness of the splitters, the open area of the flowing channel can be assured. Therefore, not only the influence of the backpressure can be minimized, but also the cost of the sound absorbing splitters can be economically saved. Optimal results reveal that the maximum value of the sound transmission loss (STL) can be improved at the targeted frequencies. Consequently, the optimum algorithm proposed in this study provides an efficient way to find a better silencer for industry.

Abstract: Image segmentation is the basis of image analysis, and because of its simplicity, rapidity and stability, the threshold method is the important one, applying in the image processing and recognition widely. In this paper, a new method is proposed, which based on relative entropy coefficients between random variables. It maximizes the target and background, which is the relative entropy coefficient in probability distribution, and gets the optimal threshold of image segmentation, and then optimizes it using particle swarm algorithm which is an evolutionary computation algorithm. The result of relative entropy coefficients for image segmentation proves its feasibility and better effect.

Abstract: Based on the well-defined UML2.0 activity diagram, a meta-model based on Control Flow Diagram is presented. And our strategy in this article is to define an OCL-based mapping in a formal and verifiable form as consistency rules between an AISD and a CFG, so as to ensure the completeness of our meta-models and allow their verification. At last, we adopt a static analyze method to transform procedure blueprint to Control Flow diagram.

Abstract: Aiming at the Multi-layer leather cutting machine,for the more thicker material paved on the table,the cutting resistance are increased and the cutter are to be need much more longer,this caused the cutter chattered easily.In order to solve the problem, the structure analysis are to be done for the main transmission system, the dynamics model of the high-frequency cutting knife shaft system is established according to transfer matrix method of the multibody system.Then combining with boundary conditions, the shaft system of natural frequency are calculated,it helped to do the dynamic equilibrium analysis for the flexible rotor and the slider-crank mechanism, simulation results show that it is good to reduce its inertia force and improve cutting stability through structure improvement for the main transmission system.

Abstract: In order to get a feasible better machining path for holes machining, which could be used to the NC (Numerical Control) programming, the algorithm for Holes Machining Path Planning (HMPP) based on Ant colony optimization (ACO) were designed. The value of the algorithm parameters were determined by computer simulation experiment. The Roulette Wheel Approach (RWA) was used by each ant to select the next milling point, and only global pheromone updating was adopted. Finally, an example was given, and the approach was proved to be efficient and practical.

Abstract: Taken the computer case as an example, dynamics modeling and analysis of a thin shell structure is presented in this paper. Optimization is implemented with the goal to reduce the vibration. Four proposals of optimal design are simulated employing the FEM software. Those proposals differ in material, shape, pattern and connectivity. Some especial techniques are used to build the three-dimensional model and to finish the FEM analysis. The dynamics characteristics of the computer case are then investigated in modal analysis based on the dynamics theory. The result is acquired by comparing the modal parameters of those in different proposals. A preferable model takes also the manufacturing and cost into account. The skeleton is universal to dynamics analysis and design of other thin shell structure.

Abstract: For the flexible three-dimensional microstructure, the GMC single-cell method was applied to establish the mechanical model of the bending interface, and then the interface micro-element method based on composite materials was performed to work on the interfacial properties of weak interfaces and micro-mechanical behavior. As a result, a flexible interface model for the interface stress was constructed and it would be helpful to improve the bending properties of the flexible three-dimensional microstructure.

Abstract: To enforce consistency and reliability of web services composite at run-time, solving exception is to ensure the transaction atomicity anomalies，it is an effective method. This paper proposes a novel mechanism based on directed graph to addressing the problem of exception handling in web services composite. According to execution dependencies and compensation dependencies among tasks in business processes, adopt the approach of directed graph to set up functional model, when exceptions are handled with forward or backward-recovery methods during execution of business processes, the approach can guarantee compensation achieving, and also gives consideration to the problem that there are no compensation services or the cost to achieve compensation,it is too expensive. Simulations prove that when the approach can efficiently guarantee the consistency and reliability of composite services at run-time.