2015 volumne 36 Issue 01
SHI Li,XU Kun-feng,NIU Xiao-ke
Abstract: The research on correlation between neurons is the foundation to understand the mechanism of infor-mation transmission and coding of neuronal population. A novel method called state-space log-linear model wasused to estimate the dynamic correlation between paired neurons,and data sieving methods were proposed toimprove the accuracy of model results for the effects of input data characteristics on the confidence interval ofthe model estimated values. By extracting the characteristics of dynamic correlation curves,changing charac-teristics of paired neurons’correlation was analyzed and then the effect on information coding of visual stimu-lus from synchronization between paired neurons was studied. Experimental verification was carried out in theprimary visual cortex of anesthetized rats.The results show that: the accuracy of the estimated value of themodel can be improved by removing the data with small firing rates,and synchronization between paired neu-rons encodes the information of different grating stimuli.
JIANG Jian-dong1,WANG Yi1,ZHANG Ling-juan2,ZHAO Yu-hui3
Abstract: Parameters optimization of control system for back to back converter station is a effective way to im-prove system operating performance. This paper researches the work theory of control system,derivates mathe-matical model of control system mode,such as constant current mode,constant extinction angle mode,con-stant voltage mode and constant power mode. Choosing ITAE performance index as genetic algorithm ( GA) a-daptive function and the value of objective function for parameters optimization,also is the process of parame-ters optimization. Parameters determining method for GA is provided in this paper. Basing on this method ,u-sing Lingbao back to back converter station as an example,the results of final optimizating parameters ara giv-en. Accodding to performance in transient process when AC side is in fault,genetic algorithm provided in pa-rameters optimization for back tp back converter station is effective and feasible.
ZENGQing-shan,LIU Wei
Abstract: Based on the evolutionary character of user equilibrium of the urban traffic,a new method whichcan solve the user equilibrium problem is presented. This method ensures all paths which have the minimumresistance are used by adding the shortest path step by step,and realize the user equilibrium of the urban traf-fic by distributing the flow of paths based on improved invasive weed optimization algorithm(IW O). The effec-tiveness is verified by solving the user equilibrium problems of one complex urban traffic network. It provesthat the new algorithm can get better solution of the user equilibrium problem after comparing it with the meth-od of successive algorithm(MSA) in solving the user equilibrium problems of some complex urban traffic net-works.
WANG Ke,CHEN Xiao-qiang
Abstract: A snake DGS defect structure which uses snake-like gap instead of rectangular gap into the dumb-bell DGS is introduced. An equivalent circuit is built,meanwhile,the relevant circuit parameters are derived.Control variate method is used to analyze the influence of parameters variation to frequency characteristics andcircuit characteristics of the snake DGS defect structure. Furthermore,this kind of structure is put into the de-sign of low-pass filter,simulation of the designed filter and its equivalent circuit model is done separately byMATLAB and HFSS. The results of these two methods are coincident. So it can be drawn that the structurehas lower attenuation frequency and more resonant frequency in the case of maintaining the area of the defects.
JIAO Liu-cheng,SHAO Chuang-chuang,CHENG Zhi-ping
Abstract: With ideas of ant colony algorithm and penalty function,an ant colony algorithm,which can solvecontinuous space constrained optimization problems,was proposed. We adopted the penalty function method ofadjusting its value of adaptively to transform the constrained optimization problems into unconstrained optimiza-tion problems,and then combined with the continuous domain ant colony algorithm of adjusting its global selec-tion factor and the value of the pheromone evaporation factor adaptively to solve the continuous space constrainedoptimization problems. And through programming solution of one benchmarking function,we compared the re-sults with those of using fixed parameters ant colony algorithm,it was verified with correctness and effectiveness.
QI Ge,BAI Zuo-xia,LIU Xian-lin,SHI Li
Abstract: The electromagnetic performance of the electromagnetic field distribution,flux linkage,current,and output torque and so on are analyzed,when dual three-phase motor is in fault condition of short-circuit ofone phase winding. At the same time,it is compared with traditional three-phase motor. Results indicate thatcoupling between phases of dual three-phase motor is very weak. ln fault condition,the fault phase of dualthree-phase motor dose not affect normal operation of non-fault phase which makes it can still continue to workwithin the acceptable range. So dual three-phase motor does not have to stop on the way , and has a certain tol-erance,and is applicable to the occasion which has special requirements for motor.
QI Ge,BAI Zuo-xia,LIU Xian-lin,SHI Li
Abstract: The electromagnetic performance of the electromagnetic field distribution,flux linkage,current,and output torque and so on are analyzed,when dual three-phase motor is in fault condition of short-circuit ofone phase winding. At the same time,it is compared with traditional three-phase motor. Results indicate thatcoupling between phases of dual three-phase motor is very weak. In fault condition,the fault phase of dualthree-phase motor dose not affect normal operation of non-fault phase which makes it can still continue to workwithin the acceptable range. So dual three-phase motor does not have to stop on the way,and has a certain tol-erance,and is applicable to the occasion which has special requirements for motor.
ZHOU Cai-rong,XU Min-qiang,WANG Xiao-song,WANG Hai-feng
Abstract: In view of the actual problem and the characteristics of carboxymethyl cellulose ( CMC) synthesisprocess,the waste liquor of the viscose fiber industry as main raw materials with wood pulp was used for pro-ducing carboxymethyl cellulose (CMC). The effect of gradient heating in ethrification process,along with theaddition of urea,sodium silicate sodium in alkalization process and the addition of tetraborate in the etherifica-tion process on the properties of the modified CMC were studied and explored by single factor test.The resultsshow that the modified CMC with the best properties were obtained by third-order heating ( first-order tempera-ture of 55 ℃,temperature of the second order of 70 ℃,and third-order temperature of 80 C ) for etherifica-tion reaction. Meanwhile, 3% urea and 5% alkaline sodium silicate were also added in alkalization process,and 6% tetraborate was added in the etherification process.The viscosity of the product CMC was up to 2486.7 MPa· s,the substitution degree was 0.65,the acid-viscosity ratio was 0.416,salt-viscosity ratio was 0.547. Compared with previous modified CMc,the indexes were promoted by 97.17%,23.63%,57.53%and 45.55 % for aboved-mentioned performances,respectively.
ZHAO Jian-hong,ZHANG Mei-mei,CHENG Xiang-lin,WANG Jian-she,WANG Liu-cheng,SONG Cheng-ying,ZHANG Jia-li
Abstract: A method was presented for the simultaneous determination of benzothiazole and 2-mercaptobenzoth-iazole in the reaction liquid by high performance liquid chromatography (HPLC). The analysis was performedon a Hypersil C18 column ( 150 mm x4.6 mm i.d) with 50 ;50 methanol-water as the mobile phase ( mobilephase with ammonia ,pH =7.0 ~8.0 ) at a flow rate of 0.9 mL/min. The samples were detected at 254 nmwith an UV detector and the column temperature was 30 ℃. It was found that benzothiazole and 2-mercapto-benzothiazole could be well separated under the chromatographic conditions. The linear ranges of the massconcentration were 0.047 ~0.426 g/L and 0.059 q/L~0.273 g/L respectively. The recoveries for them were98.20% ~ 101.0 3% and 98.78 % ~99.76% . The maximum relative standard deviations were 0.45 % and0.63 % for benzothiazole and 2-mercaptobenzothiazole.
WANG Yao-ling,CHI Ji-an,CHEN Duo
Abstract: Coal spontaneous combustion is a serious problem for coal mining industry. The use of inhibitor toprevent coal spontaneous combustion is one important measure. To identify a high efficient inhibitor to sup-press the self-heating and spontaneous ignition of coal, the inhibiting effect of CaCl, inhibitor and MgCl, inhib-itor,NaCl inhibitor,combined inhibitor was investigated by H202 oxidation test and activation energy test.The results show that each of four inhibitors is efficient and the combined inhibitor is best for preventing coalspontaneous combustion. In addition,the combined inhibitor is nonpoisonous and convenient in use.
ZHOU Jun-jie,WANG Mei-ling,GUO Peng-fei,WANG Ding-biao
Abstract: The three-dimensional numerical simulation and optimization of the last stage of a 25 MW condensa-ble steam turbine are conducted by using ANSYS Workbench,a platform of analysis system specially for therotating machinery. The results show that the modified blade has a better pressure coefficient distribution,re-duces the differential pressure distribution of blade surface,effectively controls the radial secondary flow los-ses.Total pressure loss coefficient is reduced,and the average total pressure loss coefficient is reduced by 1% . Isentropic efficiency increases from 92. 099 % to 93.157 % . After optimization,the aerodynamic per-formance of the blade increases obviously,the energy loss in the blade is reduced and the efficiency of steamturbine increases.
ZHANG Min1,2,SHEN Jia-hua1,LIU Dong-yun1
Abstract: The medium filling can improve the flotation environment effectively. The traditional sieve trays andfillings could only partially inhibit the cyclone flow and usually generate pulp jam. So we put forward the guid-ing fluid packed media to solve the contradiction of strong cyclonic flow and static separation in the cyclone-static microbubble flotation column. guiding fluid packed media is filled between the cyclone separation andcolumn flotation. while stabling static flotation environment,the upward scroll ( negative effect ) is guided andbecome stable upwelling,and the easy floating mineral is rapidly rised ( positive effect ),and make productconcentrate layer more thicker,more stable./ Based on the test data,it was found that the sieve packing hasthe potential to yield a product of approximately 25.83% copper concentration with 91.78% recovery from afeed concentration of approximately 0.727% . If mixed packing was used,the product concentration could befurther increased to 27.60% from a feed of approximately 0.739% concentration with 93.38% recovery.
LI Fu-shan,Ll Xing-rui,Ll Yu-luo,JIAN Cheng-zhi
Abstract: Fe-based amorphous alloys with excellent soft magnetic properties and high amorphous forming abil-ity have been a hot research point due to its wide application prospect. In this paper,the amorphous formationability ( AFA ),thermal stability and magnetic properties have been studied for the deliberately designed Fe80Si3,C5-xP12+x .( x =0%,1 %,2%) alloy system with eutectic composition. The results show that the amorphous alloyof Fe80Si3,C3P14,has high formation ability and soft magnetic properties. The saturation magnetic magnetization( B,) reaches 1.35 T,the initial permeability ue reaches 6 960,the coercivity H . low to 2.82A/m and the su-percooled liquid region AT reaches to 42K.
TANG Xian-xi1,YIN Yue-you1,GUo Wei2
Abstract: For the study of the effect of chloride ion penetration on crack surface by crack width and depth ,the reinforced concrete specimens with cracks were made and the chloride ion penetration experiments werecarried out. The transverse sections of specimens without crack and cracking while soaked in Chlorine ion so-lution were used for experiments.For the cracking specimens,the analysis were carried through compared ofthe crack width,the crack depth and the chloride ion penetration of crack surface,and compared with thetransverse section of specimens without crack.The research results show that,the crack width has negligibleeffect on surface chloride ion penetration of concrete cracks,surface chloride ion penetration was mainly relat-ed with the crack depth.The new viewpoint of concrete durability research on the cracking parts were put for-ward,which has important reference value for the study of the durability of concrete structures.
LU Sen-lin,WANG Long
Abstract: Modal aliasing problem exists in nonlinear and non-stationary signal processing through EmpiricalMode Decomposition (EMD ) ;Ensemble Empirical Mode Decomposition EEMD can suppress modal aliasingproblems in some extent,but added white noise can not be completely neutralized.So,complementary Ensem-ble Empirical Mode Decomposition (CEEMD) is proposed,which can reduce the reconstruction error and ex-tract the best Intrinsic Mode Function ( IMF). Then,fast fourier transformation is applied to the lMF compo-nent to derive the characteristic frequency of the fault. Analyzing the vibration signal collected by roller bear-ing experiment proved the superiority of the method and it has some practical value.
XU Ou-ming1,HAN Sen2,NIU Dongyu1,LIU Yamin2
Abstract: Viscosity is an important property of asphalt,and has a close relationship with the construction tem-perature and workability of the asphalt mixtures. In order to evaluate the effect of testing conditions on the vis-cosity,the apparent viscosity of SBS modified asphalt under different times,different temperatures,and differ-ent shear rates is studied by using Brookfield viscometer. The results shows that the apparent viscosity of SBSmodified asphalt is tending towards stability with time increasing gradually. The higher the temperature and thegreater the shear rate,the shorter the time for viscosity stabilizing and the smaller the difference between theinitial viscosity and stable viscosity. When the testing temperature exceeds 150 ℃,the variation of shear ratehas little effect on the viscosity. The shear rate should be no less than 20RPM when the viscosity of SBS modi-fied asphalt is measured at different temperatures.
WANG Qiang,QI Ying-jie
Abstract: 26.5R25 steel engineering meridian retreaded tire was regarded as study object,basic structurecomposition and dimension requirements of retreaded tires were analyzed and designed in order to lay the theo-retical toundation tor further improving use pertormance of engineering retreaded tures,engIneering retreadedtire multiple composite layer type mainly composed of tread layer thick-wall cylinder model,medium cushionrubber layer thin-wall cylinder model,belt layer thin-wall cylinder model,carcass layer thin-wall shell modeland tire side layer rotating ring model was constructed through theoretical analysis. Polar coordinate mode wasadopted for analyzing and discussing construction of multiple composite layer mechanical model and meso-stat-ics equilibrium equation based on ground mechanics theory.Stress-strain relation matrix of engineering retrea-ded tire tread rubber layer,buffer rubber layer,tire side layer,belt layer and carcass layer was described.
LU Yan-hui,ZHANG Shuai,MU Xiao-min,YANG Shou-yi
Abstract: The unused TV bands are discretized by the behaviors of the random presence of the incumbents,considered as primary users in the cognitive radio network. The spectrum discreteness is ignored by most of theexisting strategies,resulting in a mass of spectrum fragments that cannot afford the user’s demand. In the pa-per,the primary users are modeled as a Markov process,and the spectrum occupancy degree,fragments de-gree and the statistical average outage probability are defined to analyze the impact of the primary users on sys-tem performance. And two strategies are proposed in this paper. The first strategy involves adjustment factorand selects the fewer continuous channels. The second strategy based on the k-agile receiver involves the con-straint of agility and guard bands,and selects the minimum non-contiguous fragments to solve the fragmentsproblem in the physical layer. The simulations show that both strategies are superior to the existing strategies.
ZHANG Duan-jin,WANG Ai-juan
Abstract: The problem of fault detection for a class of nonlinear systems based on kernel principal componentanalysis is studied. The improved wavelet kernel principal component analysis is proposed. Firstly,the pro-posed method is applied to denose the data. Then,the preprocessed data is transformed by wavelet kernelfunction to map the nonlinear input space into linear characterization space. In the feature space,principalcomponent analysis is applied to detect faults for nonlinear system,in combination with SPE statistic and T’statistic. Simulation results show that the method can improve the fault detection performance.
YANG Zhi-yong1,2,LIANG Shan1,ZHOU Tong1
Abstract: To overcome the problem that the vehicle suspension model of the single periodic excitation roaddoes not truly reflect the nonlinear dynamics characteristics of the actual vehicle,the paper establishes a quasi-periodic dynamic road excitation function,and builds a four-degree of freedom nonlinear half vehicle suspen-sion model. Using the Poincaré map,phase diagram,power spectral density to analyse the nonlinear dynamicscharacteristics of the four degrees of freedom semi-active vehicle suspension model on uneven road surface,weobtain the amplitude of chaotic vibration and its vibration characteristics which is quasi-periodic →transitionstate → chaotic state as the vehicle through uneven road surface. At the same time,the occurrence of chaoticvibration can be inhibited effectively by adjusting the spring stiffness coefficient. The results show that the sim-ulations of the four degrees of freedom nonlinear semi-active suspension model under dual-frequency quasi-pe-riodic excitation is more closer to the real situation,which helps the design of vehicle suspension and pave-ment.
LI Xiao-gen,WANG An-ming
Abstract: The CGIS technique is used to investigate the statistics of landslide geological disasters,and the gridlimit equilibrium method and finite element method (FEM) are used to analyze stability of the landslide,andthe gray system theory method is used to forecast deformation trend of the landslide,and the early waning sys-tem about landslide geological disasters is completed.System operation results show that:the stability of thelandslide is good,the influence of water on the stability of the landslide is bigger;the early warning system a-bout landslide geological disasters which is developed realizes unified management and forecast of the relateddata of geological disasters;the constructed 3D model of landslide geological disasters can accurately reflectthe geological and topographical feature situation of where the disaster happened; the system has laid a solidfoundation to realize sharing of the WebGIS of geological disasters resources.
PEl Dong-jie,QIN Ying-zhou,ZHANG Zheng
Abstract: In order to realize bound paper books turn pages automatically to facilitate reading and scanning,adevice which can realize continuous pages turning,scanning and outputting electronic document is designed.Through decomposing,simulating the action of pages turning,and using the mechanical structure and controlsystem,the device achieves the design goal. It is shown that the device can fulfill automatic turn pages andscanning by making prototype. It has stable performance,simple operation,and can reduce the labor intensityof books scanning greatly ,which has important practical value.
MA Yong-tao,CHEN Tian-yue,LI Wei,YUAN Tao
Abstract: This paper studies the structural design of the single-layer spherical shell. with the wind loads ofshell bearing for design load,using FLUENT software to get the shell surface wind pressure distribution.Thecalculated surface wind pressure is applied to the shell structural analysis model,with unidirectional fluid-solidcoupling ( FSl) technology. Through the nonlinear calculation of structural analysis,we the stress distributionand deformation of shell under the wind load conditions. With minimizing beam section size of shell as optimi-zation goal,we obtained the size of beam section which satisfies the design requirements. Through field tests ,we got the shell node displacement load curve,and compared the results of the experiment with simulationcurves under the same conditions to verify the correctness of the shell structures model.
WANG Wei-shu1,GUO Hui-jun1,LIANG Cheng-sheng1,2,XU Wei-hui1
Abstract: The steady-state thermal analysis model of reactor core was established for a 900MW pressurizedwater reactor. The steady - state thermal-hydraulic of reactor core was calculated and analyzed with COBRA-IV. The temperature of fuel element,coolant flow distribution and temperature and the departure from nucleateboiling ratio ( DNBR ) of the reactor core were obtained. The results show that the coolant in the core exits lat-eral flow from the center to the around. The maximum temperature of coolant in the core outlet is up to 338.2℃. The maximum temperature of fuel in the core is up to 1 350 ℃. The maximum temperature of claddingsurface and fuel pellet appears above the center. The DNBR near the inlet is much higher than near the outlet,and the minimum DNBR appears near the center.
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