Applied Mechanics and Materials Vols. 121-126

Abstract: In order to meet the high-precision measurement requirement of tested objects with tiny dimension and complex shape, a miniature five-coordinate image measuring machine, which contains three translational axes and two rotational axes , is designed and built. This machine can inspect the objects from multi-orientation and multi-posture in non-contact way. As an indispensable step of image measurement, the autofocus effect has a direct influence on the following image quality and measurement accuracy. In this paper, the composition and working principle of autofocus system are presented and discussed. Meanwhile, the path planning method for autofocus system is introduced and an autofocus method based on evaluation function of mean square deviation is proposed and discussed in detail. Finally, the experiments demonstrate the effectiveness of the method and the accuracy of autofocus system

Abstract: The transformer is the hard core of the switch phase-sensitive circuit of the equipment. According to the basic failure rate model and working failure rate model of the national standards, the transformer working reliabilities are analyzed under different working conditions and environments. Based on this, the reliability analyses of the redundancy structures of the switch phase-sensitive circuit are done, and the comparisons and analysis of the results are done, and the useful conclusions for design and engineering are presented.

Abstract: The shortest path between the start node and end node plays an important role in city’s road traffic network analysis system. The basic ant colony system algorithm which is a novel simulated evolutionary algorithm is studied to solve the shortest path problem. But the basic ant colony system algorithm is easy to run into the local optimum solution for shortest path. In order to solve the problem, the improved ant colony system algorithm is proposed. The improvement methods for selection strategy, local search, and information quantity modification of basic ant colony system are discussed in detail. The experiments are done in Beijing road network in China. The results of experiments show that comparing with the basic ant colony algorithm, the improved algorithm can easily converge at the global optimum for the shortest path.

Abstract: Flue gas entrains a large number of ash particles which are composed of alkali substances into the heat recovery steam generator (HRSG). The deposition of particles on the tube surface of heat transfer can reduce the heat transfer efficiency significantly. In the present work, an Eulerian- Lagrangian model based on Computational Fluid Dynamics (CFD) is implemented to simulation flue gas turbulent flow, heat transfer and the particle transport in the HRSG. Several User-Defined Functions (UDFs) are developed to predict the particle deposition/ rebounding as well as the influence of physical properties and microstructure of deposits on the heat transfer process. The results show that only after one day deposition, the total heat transfer rate reduces 27.68% compared with the case no deposition. Furthermore, the total heat transfer rate reduces to only 238.74kW after 30 days of continuous operation without any slag removal manipulation. Both numerical simulation and field measurement identify that the deposits play an important role in the heat transfer in the HRSG. Especially, when the deposits can’t be removed designedly according to the actual operating conditions, the HRSG experiences a noticeable decline in heat transfer efficiency due to continuous fouling and slagging on the tube surface.

Abstract: In order to solve the multi-objective product-mix optimal problems oriented cloud manufacturing, SPEA2+ is used to realize the outside processing problem of lifting cross sliding trimensional parking equipment (multi-section trimensional parking equipment), which oriented cloud manufacturing. The outside processing problem is formulated as a multi-objective optimization problem and identified an analytical solution. The case illustration of parts of PSH2 lifting cross sliding trimensional parking equipment is taken as an example, examining the multi-objective optimization model. The model enables managers to determine which products to manufacture and which to outside processing. The solution of the multi-objective optimization formulation enables managers to apply the model by computing an operational ratio. The final model is simpler to apply and requires the computation of fewer variables than other prevalent models.

Abstract: The Taguchi method is used to find the optimal cutting parameters when drilling metal matrix composites (MMCs) with a polycrystalline diamond (PCD) tool. The combined effects of cutting parameters (cutting velocity and feed rate) and cutting time on three performance measures (tool wear (VBmax), the specific cutting pressure (Ks) and hole surface roughness (Ra)) were investigated employing an orthogonal array, signal to noise (S/N) ratio and the analysis of variance (ANOVA). The optimal cutting parameters for each performance measure were obtained, and the main cutting parameters that affect the cutting performance in drilling operations can be found. The relationship between the drilling parameters and the performance measures were determined using multiple linear regressions. Confirmation tests of the optimal levels with the initial machining parameters are carried out in order to illustrate the effectiveness of this approach for drilling MMCs.

Abstract: Aiming at the problem of process data update and working procedure model, the three-dimension CAPP (Computer Aided Process Planning) based on three-dimension CAD (Computer Aided Design) is proposed. The core of the system is the process model that is used to transfer data between CAPP and CAD system. This system can solve the problem of two-dimension CAPP based on parameter feature modeling of three-dimension CAD and has been applied to some aviation enterprises in china.

Abstract: Based on the analysis of the structure characteristics of high-speed wheel engineering equipment, a design method for virtual support training systems was presented, founded on virtual reality (VR), software engineering, process simulation technology. According to the function requirements, the system software and hardware platform were established. Combined with practical teaching needs, virtual support system of high-speed wheel engineering equipment was developed. The practice demonstrates that the system has high practical value and guiding significance on the aspects of talents cultivation, the teaching application, science research, etc.

Abstract: As the oil pressure of tank engine’s common-rail system is as high as 180MPa, it could bring a grate challenge to the oil con-rail’s seal quality. Especially in the condition of high oil pressure system, pulse load, metal creep deformation as well as machining error could low the reliability of con-rail’s. In tradition, shrinking the part’s tolerance is the main measure to ensure seal reliability .The measure eventually cause low efficiency, unnecessary waste, and high product cost in mechanical process. In this analysis, ABAQUS is exploited to discuss the influence that caused by various machining error on seal quality .Finally , the least taper angle error (critical point) lead to leakage is found. Besides the efficiency would be improved, the process cost also could be cut down a lot by using this data to constitute optimal technical files.

Abstract: Simulation results illustrate that there is an optimum-energy supply voltage point (Vopt) for SoC. And these voltage points normally lie in weak sub-threshold or near-threshold region. Considering about the degraded robustness under this low supply voltage, structural change instead of the sizing change is considered in proposed design. Different from conventional 6T SRAM design, the trip point voltage of proposed design changes according to bit-line voltage values. In this way, its read margin is 45% greater than conventional 6T SRAM. The proposed bit-cell exhibits wide hysteresis effect, making the design less vulnerable to process variation. Its hold margin is 30.2% greater than conventional 6T SRAM. The optimum-energy supply voltage of proposed array (256×16) is 400 mV. At the same time, the power consumption at 400 mV decreases to 16% compared to that at 1200 mV.