Table of Content

30 September 2014, Volume 48 Issue 09 Previous Issue    Next Issue

Electrotechnology

Select

Influences of Characteristics of Metamaterials on Wireless Power Transmission HUANG Ying,MA Dianguang,TANG Houjun,CHEN Ence 2014, 48 (09):  1213-1217.  Abstract ( 1023 )   Save  In order to improve the efficiency and increase the distance of the wireless power transmission system, metamaterials were applied. The formula derivation and simulation analysis verified the ability of metamaterials to improve the transmission efficiency respectively from the point of view of negative refraction and the evanescent wave. It is concluded that negative permeability can enhance the magnetic field and exponentially increase the coupling coefficient, while negative permittivity can only make little contribution to the coupling coefficient; and that the focusing effect caused by negative refraction cannot improve transmission efficiency under the radio band within a couple of centimeters. The matematerials with single negative permeability is good enough to improve the efficiency. References | Related Articles | Metrics

Select

Characteristics of Conductor Dynamic Tension During Galloping for 500 kV Power Transmission Line with 6-Bundle YANG Xiaohui1,2,ZHANG Bo2,YANG Wei2,FU Zhengcai1 2014, 48 (09):  1218-1224.  Abstract ( 858 )   Save Taking the advantage and basic condition of comprehensive test centre built on real overhead transmission line (which belongs to State Grid Company of China), the conductor tension during galloping for 500 kV 6-bundle transmission line was measured and analyzed by using artificial airfoils with D shape on conductor, which had been proved to be quite essential for galloping excitation. Through the frequency spectrum comparison and the correlation analysis with wind load, the characteristics of conductor dynamic tension during galloping were obtained. It was shown that the conductor dynamic tension could be used as one of the critical parameters for galloping, which would not only be used for reliable analysis of tower-line system, but also be applied for the monitoring and identification of transmission line galloping. In a word, the characteristics of conductor dynamic tension during galloping are the basic data for the pre-warning of galloping and the performance evaluation of anti-galloping measuring. References | Related Articles | Metrics

Select

Harmonic Detection of Electrified Railway Based on Improved HilbertHuang Transform Method GENG Chao1,WANG Fenghua1,HUANG Ronghui2,ZHANG Jun1,ZHANG Xin2,FENG Lin1 2014, 48 (09):  1225-1230.  Abstract ( 959 )   Save Electrified railway is one of the major harmonic sources in the power system, which is greatly affected by the route and weather. So, precise detection of electrified railway power load harmonic is of great important for the safety of power grid. A math mode of electric locomotive was built in this paper, from which the load current of the railway under different conditions was acquired. An improved HilbertHuang transform was applied to extract the harmonic of the current waveform in which bandwidth restricted empirical mode decomposition (EMD) method was used. By adding masking signal, the mode mixing could be restrained effectively. The simulation results show that the proposed method can extract the time-frequency distribution of the harmonics in electrified railway, which provides a new method for harmonic detection of electrified railway. References | Related Articles | Metrics

Select

Multi-Objective Distributed Generation Planning Considering Active Management ZHANG Xiang1，CHENG Haozhong1，FANG Chen2，ZHANG Shenxi1 2014, 48 (09):  1231-1238.  Abstract ( 886 )   Save  Considering the active management, a multi-objective distributed generation planning model was proposed, the upper level planning objective of which was to minimize both the investment and operating cost of distributed generation and the power loss, while the lower level planning objective of which was to minimize the curtailment value of distributed generation. It took into account the randomness of intermittent generation, such as wind turbine generation and photovoltaic power generation, as well as the uncertainty of loads. The Latin hypercube sampling-based Monte Carlo simulation was used to sample the wind speed, the illumination intensity and the load. The upper planning model was solved by the non-dominated sorting genetic algorithm while the lower planning model was solved by the prime-dual interior point method. Finally, the Pareto-optimal solutions were obtained, which could avoid the subjective impact of the traditional weighted methods on determining the weights. The feasibility of the model and the effectiveness of the algorithm were proved by the simulation and analysis of a 33-bus distribution system. References | Related Articles | Metrics

Select

Performance Analysis of Fuel Cell for Pressured MCFC/MGT Hybrid System LIU Aiguo1,WENG Yiwu2,CHEN Lei1,MA Hongan1 2014, 48 (09):  1239-1245.  Abstract ( 910 )   Save The molten carbonate fuel cell (MCFC) performances of a pressured MCFC/MGT hybrid system using a fixed micro-gas turbine (MGT) design were analyzed for off-design operation with different control methods. The effects of current density and MCFC temperature were considered for the MCFC modeling, and the modeling and experimental result were comparied. The off-design operation of the MGT was modeled by the performance characteristics of the compressor and turbine. Four control methods were mentioned for the part-load operation of the hybrid system, and the performances of MCFC were analyzed for the different methods using the system model. The results show that the efficiency of MCFC at partload operation can be higher than the design value by using the control method. The performance of MCFC has great effects on the system, the system performance can be improved by maintaining the MCFC operation temperature. References | Related Articles | Metrics

Select

Cooling Simulation Analysis Based on Multi-Field Coupling Technology of  Permanent Magnet Synchronous Motor ZENG Jinling1,XU Yu2,HAN Yepeng2,LI Guanhua2,ZHANG Qun2 2014, 48 (09):  1246-1251.  Abstract ( 839 )   Save A complete coupling analysis interface software named INTESIM-ETFMotor was developed by INTESIM (Dalian) Co. Ltd. to realize the electromagneticthermal-fluid coupling analysis of automotive permanent magnet synchronous motor. The comparison of the results between the electromagnetic-thermalfluid coupling method and the traditional simplified decoupling method shows that  a simplified decoupling model cannot guarantee the temperature continuity and energy conservation, which does not reach the true thermal equilibrium. Thus, it is necessary to conduct the bidirectional coupling analysis. References | Related Articles | Metrics

Others

Select

Extraction of Colon Peristalsis Pressure Signal Based on Wavelet Analysis ZHAO Kai,YAN Guozheng,WANG Zhiwu,LU Li,XU Fei 2014, 48 (09):  1252-1256.  Abstract ( 708 )   Save In order to obtain the pure peristalsis pressure signal of the colon, a method for extracting the peristalsis pressure signal of the colon based on wavelet analysis was proposed in this paper. The colonic pressure signal was decomposed into five levels and the peristalsis pressure signal of the colon was reconstructed after detaching the interference signal. Besides, an experiment for eliminating abnormal data was conducted. The results showed that not only the abnormal colonic pressure signal was inhibited effectively, but also the detail characteristics of the colonic peristalsis pressure signals were maintained by using the proposed method. Compared with the peristaltic pressure signal containing interference signal, the extracted signal had higher signal noise ratio and lower mean square error. References | Related Articles | Metrics

Select

Study of Signal Pathways in 3D Cell-Scaffold SystemsBased on Image Informatics Framework GUO Jin 1,TZERANIS Dimitrios S2，SO Peter T C2,WEI Xunbin3 2014, 48 (09):  1257-1262.  Abstract ( 248 )   Save Stable protein expression interference of key components of transforming growth factor (TGF)-β pathway in fibroblasts was achieved by transfection with a shRNA lentivirus. Two-photon microscopy, combined with an image informatics framework that suitable for 3D cellmatrix system, was used to study the TGF-β signaling in fibroblasts inside porous collagen scaffolds. It is concluded that, compared with TGF-β3, TGF-β1 plays a more important role in mediating myofibroblast differentiation, and that SMAD1 and SMAD3 play key roles in TGF-β1 mediated myofibroblast differentiation but in different ways. These conclusions were consistent with the results obtained by using biochemical or genetic methods. References | Related Articles | Metrics

Atomic Energy Technology

Select

Numerical Simulation of Mechanical Behaviors of Periodontal Ligament Based on Hyperelastic Model HUANG Huixiang1,TANG Wencheng1,WU Bin2,YAN Bin3 2014, 48 (09):  1263-1267.  Abstract ( 108 )   Save To accurately predict the mechanical behavior of the periodontal ligament, an exponential hyperelastic model was used to simulate and analyze the shear experiments and orthodontic treatment. The constitutive equation and elasticity tensor for the hyperelastic model were obtained based on the large deformation of continuum mechanics, and the ABAQUS UMAT subroutine for the model was developed. The parameters of the model were obtained by means of the fittings between the model and four shear experimental data. The results demonstrate that the exponential hyperelastic model can well describe the nonlinear mechanical behavior of the periodontal ligament. Meanwhile, comparisons of numerical results and four periodontal ligament shear experimental data prove the validity of the UMAT subroutine developed for the model. The simulation result of the  orthodontic treatment show that the stresses within the periodontal ligament under orthodontic load are concentrated in the areas near the cervical positions and the root apex. References | Related Articles | Metrics

Select

Experimental Study of Optimal Load Characteristics of Low Temperature Heat Organic Ranine Cycle Power Generation TANG Lei，WANG Yuping，YANG Ping，WENG Yiwu 2014, 48 (09):  1268-1273.  Abstract ( 142 )   Save The experimental study of the small organic Ranine cycle (ORC) power system performance under different heat resource temperature and different load resistance was conducted. The organic Rankine cycle power generation experimental system was built using scroll expander with the working fluid R600a utilizing low temperature heat. The results show that when the heat source temperature does not exceed 120 ℃, the experimental system has a maximum generating power of 1.05 kW and power generation efficiency of up to 4.51%, the scroll expander rotation speed and expansion ratio can reach 2 922 r/min and 3.03, respectively; There exists an optimum load resistance value which makes the power generation, unit power output and power generation efficiency ratio maximum under different heat temperatures and different working fluid mass flow rates. The scroll expander should match permanent magnet generator and the load when designing power systems so that the system can get the best performance. References | Related Articles | Metrics

Select

Experimental Investigation of Heat Transfer Characteristics of Flow Boiling of Liquid Nitrogen in MicroChannels Heat Sink JIA Hongwei1,ZHANG Peng1,GUO Tao2,FU Xin3,JIANG Shichen3 2014, 48 (09):  1274-1278.  Abstract ( 142 )   Save The flow boiling of liquid nitrogen in a micro-channel heat sink was experimentally studied for mass fluxes ranging from 62.6 to 598 kg/(m2·s). The heat sink was made of stainless steel. The experimental results showed that the heat transfer coefficient significantly increased with heat flux at low vapor quality where heat transfer was dominated by nucleate boiling. The heat transfer coefficient first increased with heat flux and then decreased with the increase in vapor quality after the heat transfer coefficient reached the peak value, which was due to flow pattern transition and the local dry-out. The experimental data was compared with the empirical correlations. Both results showed similar trend, but the calculated results were larger than the experimental ones. References | Related Articles | Metrics

Select

Effects of Turbine Casing Boundary Layer on the Flow Field and Heat Transfer at Tip Region of Turbine Blade ZHAO Gang1,ZHU Xiaocheng1,HE Lei2,WANG Jiao2,HUANG Qihe2,DU Zhaohui1 2014, 48 (09):  1279-1285.  Abstract ( 128 )   Save At the tip of the turbine blade, there are leakage flow and secondary flow, the interaction between which has significant influences on the flow and heat transfer of tip region. While casing boundary layer is the main source of secondary flow,  the length of import segment, the wall conditions of casing and tip clearance height are changed to adjust the strength of leakage flow and secondary flow in order to analyze the effects of casing boundary layer on blade tip region flows, particularly tip wall heat transfer. Calculations have been performed on the GE-E3 first stage high pressure turbine rotor and the result shows that the interaction between leakage flow and secondary flow has noticeable effects on the tip heat transfer of the suction surface side, and both reducing secondary flow and increasing leakage flow can decrease the tip heat transfer on the suction surface side but enhance the tip heat transfer on the pressure surface side. In addition, the influence of the radiused edge blade on the tip leakage flow and heat transfer has been discussed in order to provide a reference for the analysis of the tip flow and heat transfer in the multilevel and complex casing conditions. References | Related Articles | Metrics

Select

An In-Cylinder Transient Heat Transfer Model for Temperature Field Simulation of Diesel Engine Structure LIU Xiaori1,2，LI Guoxiang1，HU Yuping1，BAI Shuzhan1，DENG Kangyao2 2014, 48 (09):  1286-1290.  Abstract ( 122 )   Save  Abstract： Based on the dimensional formula h(,i)=C()d－0.2p0.8w0.8T－0.8μ－0.47eλ0.67ec0.33p, a local heat transfer model was developed and characteristic parameters were proposed as transient flow and heat transfer parameters. The total quantity of heat transfer was calculated using Woschni correlation. By ensuring that the total quantity of heat transfer from local heat transfer model is always equal to Woschni correlation at every crankangle, the undetermined coefficient C() was obtained. The improved model was applied to a singlecylinder watercooled natural aspirated fourstroke direct injection diesel engine. The simulation results are satisfactorily in agreement with the experiment. Key words： References | Related Articles | Metrics

Select

Characteristics of Variable Conditions of Screw Expander System Based on Organic Rankine Cycle LIANG Ren1,YU Yuefeng1,CHEN Liangle2,DENG Zhiqiang2,HUANG Yun2 2014, 48 (09):  1291-1296.  Abstract ( 187 )   Save Simplified models for thermodynamic calculation and indicator diagrams were established based on the operating feature of screw expander．A screw expander system based on organic Rankine cycle (ORC) using R123 as working medium was applied to power generation with associated hot fluid during oil recovery in Huabei Oil Field. After screening main factors, systematic characteristics under variable conditions were attained, by solving new steady state using iteration, analyzing net power, thermal efficiency and energy destructions. The result shows that superheated vapor leads to the decline of output network, although it benefits the output power per unit working medium. The temperature of inlet cooling water affects system performance most and the higher temperature in hot summer results in great deviation of systematic output from design condition. Ensuring the cooling capacity is an effective way to improve the performance. The influence of the change of heat source temperature is larger than that of mass flow． References | Related Articles | Metrics

Select

Measurement Method for Piston Assembly-Cylinder Friction Force Based on Wireless Transmission in an Internal Combustion Engine NING Lipu,MENG Xianghui,XIE Youbai 2014, 48 (09):  1297-1302.  Abstract ( 100 )   Save The principle of the indicated mean effective pressure (IMEP) method to measure the piston assemblycylinder friction was derived, and the method for calculation of the inertia force of piston assembly and connecting rod was obtained. Then, a reliable transmission of connecting rod stress signal was achieved using wireless transmission method, and piston assemblycylinder friction forces were measured at a range of engine operating speed under motored conditions. References | Related Articles | Metrics

Select

Numerical Simulation of Forced Convective Heat Transfer and Flow Characteristics of Nanofluids in Small Tubes Using Multiphase Models CHEN Yanjun,LI Yuanyang,LIU Zhenhua 2014, 48 (09):  1303-1308.  Abstract ( 122 )   Save The forced laminar and turbulent heat transfer characteristics of nanofluids in small smooth tubes were simulated using two kinds of multiphase-flow models. The simulated results were compared with the experimental results and the traditional predicting equations. The multiphase-flow models include the Euler-Euler model, of which one is the mixture model and the other is Eulerian model, respectively. The effects of various parameters such as Reynolds number and mass concentration of nanoparticles on the heat transfer characteristics were investigated and discussed in each model. The results show that little deviation exists between the simulated results and traditional predicting  equations for low concentration nanofluid. While non-traditional fluid characteristics occur and increase with the increase of the nanoparticles concentration of nanofluid, the effect of multiphase flow comes out when concentration reaches a certain value. Besides, the simulated results using special multiphase-flow models are closer to the experimental data than that of the traditional equations. References | Related Articles | Metrics

General Industrial Technology

Select

Experimental Study on Cooling Performance of a Thermal Environment Simulation Chamber with Helium Atmosphere Based on a Stirling Cryogenerator HUANG Yonghua1,CHENG Lei1,WU Jingyi1,XU Yuxiong1,LU Zisheng1,ZHANG Liangjun1,2,XU Shichao2 2014, 48 (09):  1309-1314.  Abstract ( 168 )   Save A 2 m×2.2 m highlow temperature environment simulation chamber charged with helium gas was developed for testing aerospace products and their tolerance to high heating/cooling rate at extreme temperatures. The high cooling rate in the chamber was realized through a combination of forced convection and radiation heat transfer, which was significantly different from conventional thermal vacuum chambers. Using liquid nitrogen and a fourcylinder, as well as the twostage Stirling cryogenerator as the cold sources, this paper conducted experimental study to test the results such as the achievable lower limit temperature and the cooling rates for approaching certain target temperatures. The Stirling cryogenerator enables the temperature of the heat sink to decrease to -210 ℃ when the chamber is precooled by liquid nitrogen, after which the helium gas inside is evacuated. References | Related Articles | Metrics

Select

Effects of Refrigerant-Side Structure on Heat Transfer and Flow Performance of Multiple Micro-Channel Parallel Flow Condenser FANG Jihua1，GU Bo1，TIAN Zhen1，ZHAO Pengcheng2 2014, 48 (09):  1315-1322.  Abstract ( 120 )   Save The theoretical model of the multiple micro-channel parallel flow condenser was established based on the method of distribution parameters, and the validity of the model was verified by comparison with the experimental data. Based on this model, the effects of flat tube inner hole numbers, proportion of height and width of the inner hole, flow paths arrangement, flat tubes distribution of different flow path on the heat transfer and flow performance of multiple micro-channel parallel flow condenser were investigated. The results show that, as the flat tube inner hole numbers increase, the heat transfer rate and air-side pressure drop increase, while the refrigerant-side pressure drop decreases;  when the proportion of the height and width of the inner hole increases, the heat transfer rate and refrigerant-side pressure drop decrease, and the air-side pressure drop remains constant; as the flow paths number increases, the heat transfer rate and refrigerant-side pressure drop increase; when the flow paths number remains constant, the principle of flat tubes distribution is that the tube number in every flow path should be decreased in turn, the decreasing speed should be gradually slowed down, and the tube numbers in the subcooling section should not be too few. References | Related Articles | Metrics

Mathematical sciences and chemical

Select

Propagation of SH Waves in PMNPT Single Crystal/Piezoelectric Double Layer Structure KONG Yanping,LIU Jinxi 2014, 48 (09):  1323-1328.  Abstract ( 128 )   Save The upper and lower surfaces of the double layer structure are mechanically free. The electrical boundary conditions are electrically open, electrically short and connected with the air medium. The general solution of the SH waves are obtained by the constitutive equations of the PMN-PT piezoelectric materials. The dispersion curves are affected by the boundary conditions and the thickness ratio of the structure. The obtained results show that the propagation properties can be achieved in the processing of the boundary and the design of the structure. References | Related Articles | Metrics

Select

Graphic Processing Unit Computing of Lattice Boltzmann Method on a Desktop Computer LIU Qiang,XIE Wei,QIU Liaoyuan,XIE Xueshen 2014, 48 (09):  1329-1333.  Abstract ( 135 )   Save Development background of the combination of lattice Boltzmann method (LBM) and graphic processing unit (GPU) computing on a desktop computer was discussed. A detailed analysis was conducted of the standard LBM form and the reason of its natural parallelism. The CUDA programming model and the Kepler computing architecture used in the computing were expounded. In order to verify the application capacity of GPU computing of LBM on a desktop computer, numerical simulations of two-dimensional flow around a square cylinder were conducted, and simulation results with the finite volume method calculation results were compared. The results show that as for the problem of twodimensional flow around a square cylinder, computational efficiency of GPU computing is approximately 3.4 times of central processing unit (CPU) computing, which proved the computing capacity of GPU computing of LBM on desktop computers to universal scientific computing. References | Related Articles | Metrics

Select

Characteristics of Drag Reduction and Control Behavior of  Boundary Layer on Multi-Factor Coupling of Jet Surface GU Yunqing1,MU Jiegang1,ZHENG Shuihua1,ZHAO Gang2, SUN Zhuangzhi2,RU Jing2 2014, 48 (09):  1334-1340.  Abstract ( 141 )   Save In order to study the influence of jet surface under the circumstance of multifactor coupling, an extension module of coupling elements and coupling mode between main flow field velocity and jet velocity, as well as high configuration of jet hole and coupling arrangement of the bottom of the jet hole was built by using the basic principle of extension. The drag reduction characteristics of jet surface under conditions of multifactor coupling were numerically simulated with standard k-ε turbulence model. The reasons for reducing the viscous resistance and drag reduction rate of the jet surface were analyzed, and the controlling behavior of jet surface towards the flow field of the boundary layer of the wall near the jet holes was revealed. The results show that under the condition of multi-factor coupling, the jet surface has a better drag reduction effect, and the best drag reduction rate is 27.69%. The jet surface under conditions of multi-factor coupling changes the shear stress distribution of walls, and affects the structure of boundary layer. Meanwhile, vortexes formed in the downstream of jet holes alter the thickness of boundary layer, which leads to the reduction of viscous resistance near the wall, and makes the jet surface to have the characteristics of drag reduction. References | Related Articles | Metrics

Others

Select

Effect of Hollow Glass Microsphere Thin Film on Heat-Insulation Performance of Building Envelope WANG Hong1,FANG Hongjie1,LAN Qingdong1,XU Lili2，HE Shun2,JIANG Chun2,3 2014, 48 (09):  1341-1345.  Abstract ( 136 )   Save The heat-insulation performance of the building envelope with sing-layer plate glass, double-layer plate glass and hollow glass microsphere (HGM) thin film as well as the heat conductivity coefficient and heat-insulation performance of HGM thin film were analyzed, and a simulation software DOE-2 was used to calculate heatinsulation performance of buildings in this paper. The results show that the buildings and window glasses coated with HGM can efficiently decrease the room temperature, and the outer wall with HGM can decrease the room temperature, too. References | Related Articles | Metrics

Select

Analysis of Temperature Uniformity in a Spacecraft Thermal-Cycling Test System Based on Wavelet Transform and Multiple Regression YANG Guang,WU Jingyi 2014, 48 (09):  1346-1350.  Abstract ( 156 )   Save A model for predicting the temperature uniformity in a thermal cycling test system for space application was proposed in this paper based on experimental data, wavelet transform and multivariate statistical analysis. The turbulent pressure signals were decomposed and reconstructed by wavelet analysis, and the correlation of the temperature nonuniformity factor with other variables were obtained by multiple regressions. An experiment was conducted to validate the proposed model. In addition, the wavelet transform was proved to have the potential to improve the accuracy of the prediction. spacecraft; thermal cycling test; temperature uniformity; wavelet transform; multiple regression References | Related Articles | Metrics

Select

Analysis of Price Bubble Formation Mechanism and Management Strategy Based on Limited Rational Real Estate Market PAN Yun1,LAN Hai1,LIU Tiejun2,TU Meizeng1 2014, 48 (09):  1351-1356.  Abstract ( 195 )   Save Research on the real estate market price formation mechanism is the basis for exploring the real estate bubble governance strategy. In this paper, from the study of nature of real estate properties, the utility composition of the supply and demand of real estate was discussed,  the formation of the price of real estate and the development of the price bubble was analyzed from the condition of gradual relaxation of complete information(rational) to the condition of incomplete information(irrational), and suggestions for the control of the bubbles were proposed. References | Related Articles | Metrics