2017 volumne 38卷 Issue  04
Zhou Junjie, Wang Pu, Zhou Jinfang
Abstract: The analysis was held with the 125MW axial flow steam turbine impulse stage blade.The three-dimensional numerical simulation and optimization were conducted by using the commercial software ANSYS CFX.The results showed that the pressure distribution of blade surface reduced,and the radial secondary flow loses was controlled effectively,with optimizing the structure geometric parameters such as ellipticity of the leading edge and trailing edge,relative pitch,inter-stage ratio,and so on.Isentropic efficiency increased by 0.43%,the total pressure loss coefficiency decreased about 0.005.After the optimization,the aerodynamic performance of the blade increased,and the energy loss in the blade decreased and the efficiency of steam turbine increased.
Ding Chang, Fu Yantang, Wu Xuehong, Gong Yi
Abstract: FLUENT software was adopted to simulate the sloshing process of liquid in container under the sudden braking condition based on VOF (volume of fluid) model.The pressure variation of front and back head was compared,which showed that the sloshing liquid mainly had a greater impact on the front head.Baffles could effectively weaken the sloshing in the container,reduce the impact on the head and improve the container safety.The liquid impact on front head was studied in the condition of different filling ratio for different baffle arrangement(all down,all up,up and downinterlaced,left and right interlaced) of five same arc baffles.Results show that the arrangement style of left and fight interlaced 、all down could reduce impact load on front head for low filling ratio,however the arrangement style of up and downinterlaced all up had poor anti-wave effect.The anti-wave effect of the arrangement style of left and right interlaced became poorer and poorer with the increment of filling ratio.Compared with other arrangement style,the arrangement style of all down had better anti-wave effect.
ZHU Yazhong,LI Shunyi,LUO Yimeng ,MA Hongye,WANG Yan
Abstract: Self-made biological fillers embedded with Pseudomonas putida were used as biofilter packing materials for treating toluene.The effects of inlet loading rate (ILR) and empty bed residence time (EBRT) were evaluated.Changes in micro-organisms before and after the shut down period and its effect on biofilter performance were investigated.Results indicated that,no need for hanging film,activities of micro-organisms were high,capacity to eliminate toluene was strong.Optimal EBRT was 74.2 s,and removal efficiency ranged from 49.3 to 97.3 %;maximum elimination capacity,16.97 g · (m3 · h)-1 was occurred at ILR of 22.11 g · (m3 · h)-1.The recovery time needed for achieving constant state,after biofilter shut down for 3 d,7 d and 30 d,were 5,21 and 45 h,respectively.Microbial counts after recovery were significantly higher than the 30d shut-down period,and lower layer had the highest microbial population.
Sheng Zunrong1,Xue Bing1,Liu Zhouming1,Wei Xinli2
Abstract: A direct-contact method of zeolite adsorption liquid water was adopted to enhance heat and mass transfer rate within adsorption heat transformer.Hot water was recycled to generate superheated steam directly,and then saturated zeolite would be regenerated by drying gas.The reactor with was filled spherical zeolite with same mass and different diameters.The mass of steam generated by small particle packed bed was 64.89% higher than that generated by big particle packed bed.The maximum steam temperature and gross temperature life had increased by about 37C.Experiments of two kinds of packed types in double layer reactor (finecoarse bed and coarse-fine bed) have shown that small particle played a more effective role for the heating of steam and packed bed;the mean maximum temperature of the steam at the top of fine-coarse bed is 37.23% higher than that of coarse-fine bed and the lasting time of the maximum temperature is decreased by 14.25%.The steam generation rate of fine-coarse bed was 16.18% higher than that of coarse-fine bed,which is more efficient in steam generation.In regeneration process,drying time of upper reactor was 25.03% shorter than coarse-fine bed.It concluded that fine-coarse bed was more effective for zeolite regeneration.
Shi Chunyan1,Fan Bingbing1,Li Yaya1,Hu Yongbao1,Zhang Rui2
Abstract: In this work,graphene oxide (GO) was prepared by an improved Hummers method.Zirconia/graphene composites (ZrO2/rGO) were rapidly synthesized by hydrothermal method with Zr(OH)4/rGO as precursor prepared by ultrasound-stirred-coprecipitation.The adsorption capacity of Zr (OH) 4/rGO and ZrO2/rGO composites decreased with the increase of pH value and increased with the increase of phosphate concentration and the solution temperature.The maximum adsorption capacities of Zr (OH)4/rGO and ZrO2/rGO composites were 81.84 mg/g and 63.58 mg/g respectively at pH 2.0.The adsorption kinetics of these two adsorbents accorded with the pseudo-second-order model and isothermal adsorption complied with the Langmuir isotherm equation.The results of its recycling properties showed the adsorption capacity decreased for the Zr (OH) 4/rGO samples,while ZrO2/rGO samples were almost the same as the initial adsorption performance.
Li Jingli, He Pengwei, Qiu Zaisen, Li Yuanbo, Guo Liying
Abstract: Impulse charactersitic of grounding devices was the important factor of lightning withstand level and lightning trip-out rate of transmission line.Based on HIFREQ program and FFTSES program in grounding power system analysis software CDEGS,this paper presented a grounding system impulse characteristic modeling considered soil frequency-dependence,especially,the Visacro-Alipio soil frequency-dependence formula has been introduced.The impact of the soil frequency-dependence on the effective length of the grounding device in different initial soil resistivity and different impulse current waveform was analyzed.The calculating results showed that when considering soil frequency-dependence,the impulse effective length would be shorter,especially for the grounding devices buried in high resistivity soil.
Deng Jicai, Geng Yanan
Abstract: In order to improve the detection rate of the acoustic magnetic EAS system,and enhance the antiinterference performance,the paper studied a new label detection algorithm that was the combination of the improved artificial fish swarm algorithm (IAFSA) and the support vector machine (SVM).An improved scheme was proposed after analyzing the strengths and weaknesses of the traditional AFSA and SVM.The experimentalresults showed that the IASFA had the faster rate of convergence and the higher accuracy than AFSA,the genetic algorithm and the particle swarm algorithm;The IASFA-SVM had the higher detection rate,the longer detective distance and the lower rate of false than the traditional magnetic label detection algorithm,and the IASFA-SVM also could meet the requirements of real-time detection.
Ding Guoqiang1Zhang Duo1Xiong Ming1Zhou Weidong2
Abstract: In order to improve the precision requirement about the attitude control of the strap-down inertial navigation system,the high order moment matching UKF (Higher-order Moment Matching UKF,HoMMUKF) algorithm was proposed,that is to estimate the SINS’ attitude parameters of based on its quaternion error model.In the recursive calculation process,for accurately approximating computational purposes,it uses high order moment matching method to calculate the average skewness value and peak value of the predicted sampling points set and their weights of the system state parameters in the view of the probability distribution.Making use of attitude quaternion method,then onlinear quaternion error model was constructed,in which model the systemnoise vector depends on system state vector,meanwhile construct its measure equation whose measurement noise vector depends on quaternion measurement vector by pseudo observation vector method was constructed,the weighted average of estimated quaternion with Lagrangian operator was calculated,the system noise variance calculation with the system noise separation algorithm was carried out,and finallyconstruct the SINS’ attitude estimation HoMM-UKF algorithms simulation on SINS attitude experiment platform was designed.It can be seen that HoMM-UKF algorithm’s calculation accuracy is higher than others and has better numerical stability,comparison of the UKF,and CDKF algorithms,and so the HoMM-UKF algorithm’s feasibility and calculation accuracy is verified.
Mao Xiaobo, Zhang Qun,Liang Jing, Liu Yanhong
Abstract: In this paper,a new algorithm of license plate recognition in the hazy weather was designed.Firstly,defogging operation was introduced for license plate image in the environment of hazy by using improved dark channel prior.Then after the pretreatment,positioning,segmentation and extraction,coarse grid characteristic matrix is obtained.Finally,radial basis function (RBF) neural network,which was optimized by particle swarm algorithm in advance,was used to identify the character.The experiment results showed that the improved algorithm not only had a good effect on haze removal,but also reduced the duration of defogging,which effectively improve the license plate recognition speed and accuracy in fog and haze weather.
Wang Junying1,Yan Fenfen1,Chen Peng2,Dong Fangmin1,Zang Zhaoxiang2
Abstract: The basic ant colony algorithm tended to be trapped in local optimum in solving task scheduling problems of cloud computing.A probability adaptive ant colony optimization was proposed.This algorithm rankd the tasks in descending order according to their size,defines the task concentration degree,and introduces the probability adaptive adjustment factor to adjust the assignment probability of over-concentrated resource noded.The results showed that the proposed algorithm shortened the task completion time,and had some improvements on convergence speed,compared with the Ant Colony Optimization and Modified Ant Colony Optimization.
Baiyang1,Wang Zhihai1,Sun Yange2
Abstract: Concept drift was a challenging problem in stream mining.When the concept drift occured,the accuracy of the original predictive model may decrease significantly.So it was necessary to put forward a feasible method to detect concept drift.Recurring concept is a special case of concept drift.However,most of existing algorithms have not taken full account of this case.This research proposed an approach to the recurring concept detection problem.Extensive experiment revealed that the method we proposed could detect not only the concept drift with relatively low delay and rate of false positive,but also the recurring concepts.Moreover,the accuracy of the classification would be greatly improved.
Lu Yanhui, Miao Panpan, Yang Shouyi
Abstract: In order to improve the energy efficiency of massive multi-input multi-output(MU-MIMO) downlink systems,the power among users was not allocated equally.The pseudo-concavity of the energy efficiency function with respect to the power of the user allocation was derived through the analysis of energy efficiency function.An optimal power allocation alogrirhm was proposed.Because of the large number of base station antenna in MIMO,the power consumption of radio frequency chain could not be ignored.Thus a new power assumption model was put forward,while both the power of the user allocation and circuit power consumption were considered.Based on this model,the influence of the power of the user allocation on the total power consumption as well as energy efficiency was analysed.By exploiting the pseudo-concavity of the energy efficiency function with respect to the power of the user allocation,an optimal energy-efficiency power allocation algorithm was proposed.Finally,a detailed energy efficiency performance comparison was made between the proposed power allocation algorithm and the power allocation.The simulation results showed that the proposed algorithm could effectively improve the energy efficiency of the MIMO systems.
Yan Xinfang, Zhang Xiaodan, Yan Jingjing, Feng Yan
Abstract: To solve the problem in HCAGG that the nodes far away from the cluster head had less energy,and were are prone to be blind nodes,a Hierarchical Clustering Topology Optimization based on Discrete Artificial Fish Swarm (HCTO-DAFS) was proposed.The HCTO-DAFS introduced a new comprehensive weights and acquired the new cluster heads.The member nodes would have more energy when they were away from the cluster head.The DAFS could reduce the probability of blind nodes.Simulation experiments demonstrated that this algorithm could efficiently balance the nodes’ energy and prolong the network’s lifetime.
Fang Wei,Mei Xiwei
Abstract: For the problem of coverage optimization in Wireless Sensor Network (WSN),a blind-zone centroid-based scheme in three dimensional area(BCBS-3D) was proposed.In the three-dimensional monitoring region,BCBS-3D partitioned random sensors by Voronoi diagram.According to the coverage of three dimensional Voronoi polyhedron,blind-zone diagram could be constructed clearly.BCBS-3D also regarded the centroid of blind-zone area as the optimal position,so as to maximize the monitoring area.Simulation results showed that BCBS-3 D hadobvious advantages in coverage rate and distance compared with other algorithms that based on Voronoi diagram.
Sun Yanjun1,Yang Junsheng2,Zhang Jian2,Wang Shuying2
Abstract: Weathering action will not only change the mineral composition of rocks,but also cause significant reduction of rock material strength.As the surrounding rock pressure acting on the lining increases,lining cracks could be developed gradually,and lining destruction even occurs if the cracks are not disposed in time.It could bring adverse effect to the tunnel operation safety.In this paper a case history of the highway tunnel which located in weathered granite was presented.The stability of surrounding rock for the XJD tunnel was relatively good and the linings were constructed according to Ⅱ-class tunnel lining design during the excavation process.However,the lining cracks appeared after the tunnel had been established.To analyze the reason,some experiments on the physical and mechanical properties of granites with different weathering degrees had been done through core sampling drilling.The mineral compositions of granites were studied using fully automatic X-ray diffractometer,and rock material strengths were also tested.The mechanical properties of lining for the tunnel buried in granites with different weathering degrees were also analyzed by using numerical simulation method.The result comparison between the numerical simulations and experiments showed that the weathering of granite was the main reason to cause the lining cracks.At last,some corresponding treatment measures for the problem were proposed,which could be used as a reference for the similar projects.
Abstract: Dynamics performance of suspension monorail vehicles was tested in virtual prototyping simulation platform to analyze the changing law of line adaptability under multiple operating conditions and the relationship between line adaptability and load conditions (empty and heavy).Test results showed that in linear conditions,the index of stability conformed to the regulations of “Railway vehicles-Specification for evaluation the dynamic performance and accreditation test” (GB/T 5599-1985);The maximum vibration acceleration conformed to the regulations of “the international standard of railway transportation” (UIC-513),which was promulgated by the international union of Railways.These results showed that the standard vehicle had good adaptability in linear conditions.In curve conditions,the maximum guiding force did not exceed the maximum load value and conformed to the safety operation standard,but the composition guiding forces of heavy vehicle was bigger than the safety operation standard,so the vehicle speed should be slow down.
Zhai Kewei1Du Chaowei2Zheng Fengxi3Zheng Yuanxun4
Abstract: A comprehensive evaluation method of bearing capacity was proposed for highway T beam bridge based on fuzzy stochastic theory.Factor indexes of load bearing capability were produced by stochastic simulation according to on-site test data.Then the probability distribution of the bearing capacity partial check coefficients and the load bearing capacity were obtained by fuzzy comprehensive evaluation theory.Finally the load bearing capacity with certain guarantee rate was figured out.An example of reinforced concrete (RC) T type beam bridge was analyzed and the feasibility of the proposed method was demonstrated.The results provided reference for highway bridge bearing capacity evaluation and repair management.
Kang Beibei, Dong Yunda, Wang Yali
Abstract: In a real infinite-dimensional Hilbert space,Douglas-Rachford splitting method for convex minimization was studied.Iff and g in the objective function were closed,proper convex,and the f’s gradient was Lipschitz continuous,then the method’s weak convergence was analyzed.Our analysis allowed the corresponding proximal parameters to vary from iteration to iteration and their upper bound relied on Lipschitz constant off’s gradient.
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