Table of Content

28 April 2012, Volume 46 Issue 04 Previous Issue    Next Issue

Aeronautics & Astronautics

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Experiment on Bi-functional Catalyst of Dimethyl Ether Steam Reforming for Hydrogen Production WU Jiao, HUANG Peng, CHEN Xiao-Ling, ZHOU Xiang-Man, ZHANG Wu-Gao 2012, 46 (04):  509-514.  Abstract ( 3460 )   Save Abstract： The performance of catalysts prepared by mechanically mixing dimethyl ether (DME) hydrolysis active components and methanol reforming active components were compared in the DME steam reforming reaction. The effects of different active components and different calcination temperatures of CuMnspinel were studied. The results show that HZSM5 (nSiO2/nAl2O3=38) has the highest H2 production rate among different DME hydrolysis active components. CuMnspinel has high H2 production among different methanol reforming active components. CuMnspinel that was calcined by 700 °C exhibits the highest activity for DME steam reforming. The result shows that DME conversion is 99.65% and H2 production is 73.15% at 350 °C when used the bifunctional catalyst composed of CuMnspinel(700 °C) and HZSM5(38). The study is very important for fuel design of DME engine. Key words： References | Related Articles | Metrics

Energy and Power Engineering

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The Influence of Oil on Pressure Drop of R410A Flow Condensation in Small Diameter Microfin Tube HU Hai-Tao-1, HUANG Xiang-Chao-1, DING Guo-Liang-1, DENG Bin-2, ZHENG Yong-Xin-3, GAO Yi-Feng-3, SONG Ji-3 2012, 46 (04):  515-519.  Abstract ( 3522 )   Save The pressure drop characteristics of R410Aoil mixture flow condensation inside a small diameter microfin tube were investigated experimentally, and the effect of oil on frictional pressure drop was analyzed. The results show that, when the vapor quality is lower than 0.6, the presence of oil decreases the condensation frictional pressure drop of R410A, and the decrement can reach up to 12% at the present test conditions; when the vapor quality is higher than 0.6, the presence of oil increases the condensation frictional pressure drop of R410A, and the increment can reach up to 13% at the present test conditions. A new correlation of frictional pressure drop for R410Aoil mixture flow condensation inside small diameter microfin tubes was developed based on the mixture properties, and it can agree with 94% of the experimental data within a deviation of ±30%. References | Related Articles | Metrics

Engergy and Power Engineering

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The Flow Stability Analysis of Supercritical Fluid in Heated Pipes：Frequency Domain Analysis HOU Dong, LIU Peng-Fei, LIN Meng, YANG Yan-Hua 2012, 46 (04):  520-523.  Abstract ( 2820 )   Save The frequency domain model for stability analysis of flow dynamics with supercritical fluid was described. With the model the density wave oscillation of supercritical water flowing in heated pipes was studied, and the stability maps were constructed. The sensitivity studies of system inlet and outlet orifice coefficients, system pressure drop, etc., were carried out. The results show that larger inlet orifice coefficients can improve the system stability, but larger outlet orifice coefficients can degrade the system stability. Increasing the system pressure drop can also be beneficial to the system stability. Key words： frequency domain model; flow stability; supercritical References | Related Articles | Metrics

Energy and Power Engineering

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The Flow Stability Analysis of Supercritical Fluid in Heated Pipes：Time Domain Analysis HOU Dong, LIU Peng-Fei, LIN Meng, YANG Yan-Hua 2012, 46 (04):  524-529.  Abstract ( 3238 )   Save The time domain model for stability analysis of flow dynamics with supercritical fluid was described. With the model the dynamic behaviors of supercritical water flowing in heated pipes were studied. The mass flow fluxes versus time were given out, and the portraits of system inlet and outlet mass fluxes were plotted in the phase plane. The stability characteristics of system when the logarithmic decay ratios (LDRs) are very close to zero were checked out, and the results show that the system has stable limit cycles with nearzero LDRs. Through transient simulations with jumping heating powers the stability oscillations of system of high outlet enthalpies were observed. The frequency domain analysis and time domain analysis are consistent with each other. However, the latter method can provide better analysis of the nonlinear characteristics of fluid flow. References | Related Articles | Metrics

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Performance Analysis of Heat and Mass Transfer on a Metal Hydride Reactor HU Xiao-Chen, QI Zhao-Gang, YIN Li-Ming, CHEN Jiang-Ping 2012, 46 (04):  530-535.  Abstract ( 3164 )   Save In the metal hydride compression cycle, the heat and mass transfer performance of the reactor has great impact on the system efficiency. A computational fluid dynamics (CFD) method was used to simulate the performance of heat and mass transfer on a new reactor bed with segmental baffle plate. The simulation on the reactor bed with different numbers of baffles and research on the unsteady state of the bed under a particular baffle number were carried on. As a result, the flow performance of reactor increases and heat transfer properties of reactor change less with the baffle number. Hence, the baffle of spiralplate type is indicated to optimize the above reactor. The simulation process proves that the new type reactor shows better heat and mass transfer performances than the reactor with segmental baffles. References | Related Articles | Metrics

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Unsteady Simulation of a Centrifugal Compressor with Holed Casing XU Wei, WANG Tong, DING Liang, GU Chuan-Gang 2012, 46 (04):  536-539.  Abstract ( 3287 )   Save Holed casing treatment was proposed for unshrouded centrifugal compressor and unsteady simulation was done in small flowrate condition near rotating stall. It was found that the pressure near the bleed port fluctuates in the tip region. The inlet flowrate of the compressor can be raised by the reinjected flow in the holes. A periodical excitation to the inlet flow of the compressor is also induced because of the space periodicity and time periodicity of the reinjected flow, and the flow in the tip region near the blade leading edge is periodic. The shear flow in the tip region of the compressor is improved and the flow in the tip clearance is interfered by holed casing treatment, and the stable working range of the compressor is expanded as a result. References | Related Articles | Metrics

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Closed-Loop Control of Low Temperature Combustion and Transition Process of Diesel Engine QU Shuan, SHI Lei, DENG Kang-Yao 2012, 46 (04):  540-544.  Abstract ( 3278 )   Save Transition from conventional combustion to low temperature combustion was studied by using closed loop combustion control system. The test results reveal that the cyclebased closed loop control system can follow c （crank angle corresponding to 50% of total heat release） step input and restrain system disturbances such as speed, load, rail pressure and exhaust gas recirculation (EGR). During the transition process, fuel injection timing can be adjusted in time to keep the combustion phase at the set point, in other words, combustion stability is ensured. Related Articles | Metrics

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Modeling and Simulation for Thermodynamic Process of Steam Accumulator System HU Ji-Min, JIN Jia-Shan, YAN Zhi-Teng 2012, 46 (04):  545-549.  Abstract ( 3679 )   Save Based on the analysis on steam accumulator charge system with theories of variable mass system thermodynamics and viscous fluid mechanics, mathematic models of each system component were built up. Then the steam charging process was simulated by system simulation model based on Simulink of Matlab, and the obtained results of dynamic characteristics provide the optional method and parameters for design of system. Key words： steam accumulator; variablemass; control valve; modeling; simulation References | Related Articles | Metrics

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Effects of Slot Geometry on the Film Cooling Performance WAN Chao-Yi-1, RAO Kun-2, RAO Yu-1, XU Ya-Min-3 2012, 46 (04):  550-555.  Abstract ( 3283 )   Save  A numerical study was conducted to investigate the film cooling performance of a straight slot, a converging slot and a diffuser slot. Firstly, a shear stress transport (SST) k-ω model and a Reynolds stress turbulence model (RSTM) were respectively used to calculate the slot film cooling, and the calculation results were compared with the existing literature data. The comparison indicates that for the same mesh gird, the SST model shows a better performance in simulating the flow and heat transfer characteristics in the slot film cooling. Based on the validated model, the film cooling effectiveness of the different kinds of slot with the same jet angle (45°) as well as the same exit geometry at different blowing ratios was obtained. The results show the slot geometry plays an important role in the film cooling performance, and the straight slot has the best film cooling performance than the other two slots. The temperature field, streamline traces and the turbulent kinetic energy field around the film cooling slots at M = 4 are also obtained to analyze the underlying mechanisms of the slot geometry influencing the film cooling performance. References | Related Articles | Metrics

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Design and Construction of a Double-sides Guarded Hot Plate Apparatus at Liquid Nitrogen Temperature LI Man-Feng-1, 2 , ZHANG Hua-1, JU Yong-Lin-1 2012, 46 (04):  556-560.  Abstract ( 2993 )   Save The principle and structure of a doublesides guarded hot plate apparatus (GHP) at liquid nitrogen temperature (-196 °C) were described . It is different with the traditional GHP in terms of the structure, heating method and temperature measurement. The method of the line heat source was applied for the meter and guard plates, and the liquid nitrogen containers were employed as the cold plate. The clamping assemblies and the sliding assemblies were also presented. The measurement methods of the temperatures, the input power, the meter area and the thickness of the specimens were given. The uncertainties for the measurement were also discussed.   References | Related Articles | Metrics

Chemical Engineering

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Study on the Catalytic Oxidation of Ethane in a Million Seconds Contact Time Reactor LI Tuo-Nian, LIN He, LUO Tao, HUANG Zhen 2012, 46 (04):  561-566.  Abstract ( 3033 )   Save The Pt catalyst samples were prepared by impregnation of αAl2O3 foam monolith. By changing the radio of C2H6/O2, the percentage of N2 and total flow rate, the property of shortcontacttime reforming (SCTR) in a millionseconds was investigated. In addition, direct and indirect oxidation models were discussed by checking the temperature layout in the catalyst monolith. The results show that when enhancing C2H6/O2 ratio and N2 dilution ratio, the selectivity of C2H4 increases (up to 70%) and selectivity of CO and H2 decreases. The contact time affects the selectivity of the products from ethane oxidation, the selectivity of synthesis gas reaches maximum (S（H2）=40%，S（CO）=75%) at the flow rate of 4 L/min. The experimental results prove that SCTR is a combination of homogeneous and heterogeneous reaction. Key words： References | Related Articles | Metrics

Automation Technique, Computer Technology

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Shuffled Frog Leaping Algorithm for Multisupplier Selection Problem with Multiple Products and Discounts HAN Yi-1a, 1b , 2 , CAI Jian-Hu-1a, 1b , LI Yan-Lai-3, YE Xu-Hong-1a, LIN Hua-Zhen-1a, WANG Wei-1a 2012, 46 (04):  567-572.  Abstract ( 4278 )   Save  For solving multisupplier selection problem with multiple products and discounts, a problemspecific shuffled frog leaping algorithm (SFLA) was designed. The basic concepts and principles of SFLA were briefly introduced. The coding style, operators and executive procedures were described. Through an instance, the high performance and the reason of SFLA over genetic algorithm (GA) in computational time and quality of solution were highlighted and analyzed. References | Related Articles | Metrics

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Hydrodynamic Characteristics Analysis of UUV Parking on the Seabed ZHU Xin-Yao-1, SONG Bao-Wei-1, DAN Zhi-Xiong-2, WANG Peng-1 2012, 46 (04):  573-578.  Abstract ( 3843 )   Save  Based on the introduction of the conception and working process of unmanned under water vehicle(UUV) parking on the seabed, in order to study the hydrodynamic forces of UUV changing with attack angle and the impact of assistantthrusters and supporting structures on hydrodynamic forces, this paper meshed structured grid using Ansys ICEM and simulated the flow field using CFX of three different kinds of UUV, the UUV without supporting structure and assistantthruster, the UUV with only supporting structures and the UUV with assistantthrusters and supporting structures. The paper also simulated the situations of attack angle changing from -90 to 90 degrees and obtained the results of drags, lifts and pitching moments at each situation. Then the results were summarized and the curves of drag coefficient, lift coefficient and pitching moment coefficient were drawn. Finally, the hydrodynamic characteristic of the UUV and the impact of assistantthrusters and supporting structures on hydrodynamic forces were analyzed. Key words： References | Related Articles | Metrics

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Adaptive Fuzzy CMAC Position Tracking Control Based on Pneumatic Artificial Muscle SHEN Wei-1, SHI Guang-Lin-2 2012, 46 (04):  579-583.  Abstract ( 3212 )   Save A single degree freedom pneumatic artificial muscle spring mass system was built. An adaptive fuzzy CMAC (AFCMAC) was setup to track and control the pneumatic artificial muscle system. With the parallel supervision of discrete anti saturation PID (DASPID) there is few too big tracking error and pressure fluctuation in the beginning of control process, which makes the online real time self adjustment of AFCMAC possible. The online real time self adjustment ability improves the control performance of the adaptive fuzzy CMAC, and finally the spring mass system is entirely controlled by AFCMAC. In the end, the comparative study of control performance between DASPID and CMAC was carried out. The experimental results suggest that in nonlinear condition, AFCMAC could get better tracking performance than DASPID. References | Related Articles | Metrics

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Point-Based Surface Filtering Based on Meshless Local Petrov-Galerkin Method QIN Hong-Xing-1, YANG Jie-2 2012, 46 (04):  584-590.  Abstract ( 3464 )   Save This paper presented a meshless approach for pointbased surface filtering based on meshless local PetrovGalerkin method. For the approach, there is neither need to construct local or global triangular meshes, nor need of global parameterization. By computing local tangent space, local symmetric weak form for every point is constructed in terms of anisotropic diffusion equation. Then PDEspecific mass and stiffness matrices are constructed. The corresponding sparse linear system is solved with an iterative solver. The obtained results show that the approach can smooth noises on pointbased surfaces while preserving geometric feature. Its efficiency is comparable with that of the traditional finite element method. References | Related Articles | Metrics

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Parallel Computation for the Dynamic Response of Connectional Passage in Twin-Tunnel due to Train Load WANG Jian-Wei, JIN Xian-Long, CAO Lu-Fen, ZHANG Wei-Wei 2012, 46 (04):  591-595.  Abstract ( 3267 )   Save Taking a largescale twintunnel as an example, a 3D model of traintunnelconnectional passagessoil system was established. Based on Dawning 5000A in Shanghai Supercomputer Center, a traintunnel interaction balanced domain decomposition algorithm was designed to overcome the computing difficulty induced by large scale model. The dynamic response of connectional passage under train load was analyzed, the computing efficiency of different partition schemes were also compared. The results show that although the additional dynamic stress in connecting passage due to train load is small, two train intersect should be avoided in this location because of the high stress level. The traintunnel interaction balanced domain decomposition algorithm has higher parallel efficiency than the common recursive coordinate bisection method. References | Related Articles | Metrics

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State Performance Evaluation for the Main Pump Bearing of Pump Truck Based on Ant Colony Optimization of Neural Network SUN Wang, LI Yan-Ming, DU Wen-Liao, YUAN Jin, LIU Cheng-Liang 2012, 46 (04):  596-600.  Abstract ( 2857 )   Save  During the process of the state performance evaluation for the key components of mechanical equipment, the convergence speed of BP neural network, genetic neural networks and other hybrid intelligence algorithm is slow and may inevitably meet local minimal problems. According to these problems, a kind of hybrid intelligence algorithm was proposed which combines the global optimization characteristics of ant colony optimization (ACO) and the innings optimization ability of BP neural network. And it is applied in the state performance evaluation for the main pump bearing of pump truck. According to the application results, the ant colony neural network can solve the slowly convergence speed, local minimal problems very well and the accuracy of classification is improved which also reflects the good application prospect. References | Related Articles | Metrics

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Geometric Design and Adjustment of Shape for Developable Quartic λBézier Surfaces with Shape Parameters HU Gang-a, b , JI Xiao-Min-b, c , QIN Xin-Qiang-a, SHEN Xiao-Qin-a 2012, 46 (04):  601-606.  Abstract ( 3498 )   Save To solve the problems in adjusting and controlling shapes of developable surfaces, two direct explicit and efficient methods of computeraided design for developable surfaces with local shape parameters were proposed. Firstly, following the important idea of duality between points and planes in 3D projective space, the developable quartic λBézier surfaces with shape parameters were represented using control planes with quartic λBézier basis functions. The developable quartic λBézier surfaces inherit the outstanding properties of the Bézier surfaces, with a good performance on adjusting their local shapes by changing the shape parameters. In the particular case where λ is equal to 0, the developable quartic λBézier surface is a developable Bézie surface. And then, the conditions of G2 continuity and C2 continuity between two adjacent developable quartic λBézier surfaces were presented. Finally, some properties of the developable quartic λBézier surfaces and applications in developable surfaces design were discussed. The modeling examples illustrate that the developable quartic λBézier surfaces provide two valuable ways for the design of developable surfaces. References | Related Articles | Metrics

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A Fault Detection Model Based on Dynamic Limit under Non-periodic Non-steady Conditions WANG Tian-Zhen-1, 2 , GAO Di-Ju-1, LIU Ping-1, TANG Tian-Hao-1 2012, 46 (04):  607-612.  Abstract ( 3752 )   Save When the system is working under nonperiodic nonsteady conditions, the traditional straight line limit is hard to detect the faults. For these problems above, this paper presented a fault detection model based on the dynamic limit. According to the need for realtime fault detection, the process data is used to segment handling. And the paper proposes the dynamic limit to substitute the straight limit line. Then slid on the test data transformation, result in subsliding line. And then achieve fault detection by determining the subtraverse line and the dynamic limit. At last, the feasibility analysis is given to the model. The experiment results verify that the model is applicable to the fault detection under the nonperiodic nonsteady conditions even if the system’s multivariate outputs are mutated and the amplitude of Hotelling T2 changes greatly. Compared with traditional methods, the model greatly reduces the system’s leakage alarm and false alarm. References | Related Articles | Metrics

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A Framework of Collaborative Simulation for Autonomous Underwater Vehicles WANG Zhuo-a, FENG Xiao-Ning-b, WAN Lei-a, PANG Yong-Jie-a 2012, 46 (04):  613-619.  Abstract ( 3640 )   Save According to the practical application of AUV simulation, collaborative simulation was used to solve these problems. An AUV collaborative simulation architecture and development method was provided. The architecture structure and the information transfer process of the platform were described. And the hydrodynamics collaborative simulation model was also described. Finally, the obstacle avoidance and long voyage simulation test, objects detection and recognition simulation test, and pipes track simulation test were conducted. The tests prove that the collaborative simulation framework can complete the collaborative work between isomerous simulation models in different software environment. And at the same time, it solves the problem that single model can not accurately describe the nonlinear computing. It improves the simulation reliability at a certain extent. References | Related Articles | Metrics

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Bisimulation Research on C Model Embedded with Computable Function JIANG Meng-Zhi-1, 2 , ZHAO Feng-Jing-2 2012, 46 (04):  620-623.  Abstract ( 2641 )   Save  In C model embedded with computable functions, there is no Summation operator. So this paper defined new concept of prime process and gave out the normalization process and finite axioms system. Then it provided a model with localization and polydic operators. With the help of these extra features, the Prefix, Replication and Choice operators can be defined conveniently. References | Related Articles | Metrics

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Connectivity on One-and Two-Way Flight Routes in Aeronautical Ad hoc Networks ZHENG Bo-1, 2 , ZHANG Heng-Yang-1, SUN Peng-1, HUANG Guo-Ce-1 2012, 46 (04):  624-629.  Abstract ( 4241 )   Save A scheme of storecarryforward in delay/disruption tolerant network (DTN) was introduced to eliminate some problems in the oceanic aeronautical Ad hoc networks (AANET), such as low node density and low connectivity. The connectivity probability of AANET on one and twoway of the flight routes were analyzed theoretically and verified through simulations. Furthermore, the connectivity probability of AANET over North Pacific Ocean Route was calculated using the information of scheduled flights between East Asia and North America, validating the effectiveness of the storecarryforward scheme. The result shows that the scheme can improve the connectivity of AANET, especially in the condition of low aircraft density. References | Related Articles | Metrics

Energy and Power Engineering

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Distortion Drift Compensation Algorithm with Video Watermarking in Compressed Domain ZHOU Yue-1, SUN Tan-Feng-1, 2 , JIANG Xing-Hao-1, 2 2012, 46 (04):  630-635.  Abstract ( 3781 )   Save A drift compensation algorithm for robust H.264/AVC video watermarking in compressed domain was proposed. The drift compensation algorithm is adopted to reduce the visible decoding error, and the possible instances that reference blocks could be changed in the embedded process of watermarks are taken into consideration to avoid the further spread of distortion drift. The macroblocks with the least partition size are selected to embed watermarks and the algorithm utilizes the “energy compact” property of Discrete Cosine Transform to ensure stability under the attacks. The experiments show that this algorithm can obtain excellent imperceptibility. Drift compensation algorithm can significantly eliminate the visual influence caused by watermarking. Under the high lossy compression attack, an average detection correction rate of 80% can still be obtained with the proposed algorithm. References | Related Articles | Metrics

Automation Technique, Computer Technology

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Improved Combination Rule of Evidence Based on Pignistic Probability Distance XIAO Jian-Yu-1, 2 , TONG Min-Ming-1, ZHU Chang-Jie-2, FAN Qi-2 2012, 46 (04):  636-641.  Abstract ( 3962 )   Save To remedy the shortcomings in the recognition of evidence conflict by using conventional conflict coefficient, this paper discussed the application conditions of Dempster’s combination rule by traditional conflict quantification standard and the distance among probability assignment functions transformed by pignistic. Furthermore, the paper presented an improved method of evidence combination. In this method, the conflict level is represented by the pignistic probability distance of evidence, after that the conflict level is transformed into similarity level and the support degree of evidence is obtained. In addition, the weight coefficients are determined. Finally, the basic probability assignments adjusted by weight coefficient are fused by Dempster’s combination rule. The numerical examples prove that the modified method can resolve the evidence conflict efficiently and has fast convergence speed. References | Related Articles | Metrics

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Dynamic RBF Network Training Method Based on Immune Mechanism LING Xiao-Feng, GONG Xin-Bao, JIN Rong-Hong 2012, 46 (04):  642-645.  Abstract ( 2671 )   Save A two stage RBF network training method for dynamic systems was proposed. Taking its inspiration from dynamic nature and adaptability of natural immune system, in the method, the RBF hidden units are differentiated into two types, and undergo different training stages according to the stable and mutation part of dynamic systems. Through adaptive immune mechanism, the method greatly reduces the computational complexity and improves the dynamic tracing ability. The computer simulations demonstrate that the proposed method strikes a good balance between precision and convergence speed, and achieves very high performance. References | Related Articles | Metrics

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Influence of Crimping on the Performances of Balloon Expandable Stents WANG Ming, MA Quan-Chao, ZHANG Wen-Guang, LUO Yun 2012, 46 (04):  646-650.  Abstract ( 3659 )   Save Plastic deformation and work hardening may occur in crimping, which can result in changes of material properties and affect the performance of stents. A complete deformation procedure of a typical stent was simulated using finite element method. Its mechanical performances were evaluated and compared with that using a simplified procedure (omitting the process of stent crimping). It was found that the crimping has a significant influence on the stent shape, stress distribution, recoil rate and the maximum expandable diameter of stent. References | Related Articles | Metrics

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Two-Dimensional Irregular Spatial Scheduling Method for Hull Block Construction in Shipbuilding ZHANG Zhi-Ying-1, YANG Ke-Kai-1, YU Jin-Wei-2 2012, 46 (04):  651-656.  Abstract ( 3738 )   Save  Considering spatiotemporal feature of spatial scheduling in block construction and irregular projection shape of blocks, an optimization model which takes time and space as the optimization objectives was proposed. In order to approach actual situation, blocks are thought as irregular polygons. Interference checking and suspension test are used to avoid the phenomenon of suspension and overlap in spatial scheduling. An improved particle swarm optimization method was designed and average adaptive approach was used to determine weights for different optimal goal in the spatial scheduling algorithm. The simulation results validate the effectiveness of the proposed approach, showing that this algorithm can improve the spatial utilization and reduce the complete processing time effectively. References | Related Articles | Metrics

General Industrial Technology

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Sensitivity of Physiological Parameters in Different Indoor Environment PAN Li-1, LIAN Zhi-Wei-1, SUN Bi-Ying-2, DONG Li-2, YE Jian-Jun-3 2012, 46 (04):  657-660.  Abstract ( 2591 )   Save Physiological parameters including heart rate (HR), heart rate variability (HRV), blood oxygen saturation (SaO2), finger blood flow (FBF), skin conductance (SC) and respiratory rate (RR) were measured when indoor environmental factors varied in temperature, relative humidity, ventilation, lighting and noise. Sensitivity of these physiological parameters changing towards different environmental factors was statistically analyzed. The results show that HRV, FBF and RR can be combined to evaluate acoustical environment; HRV and SaO2 are suitable for thermal environment; RR can be chosen for fresh air volume changing environment; and FBF and SC can be selected altogether to judge lighting environment. Key words： References | Related Articles | Metrics