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    02 June 2017, Volume 22 Issue 3 Previous Issue    Next Issue

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    Numerical Study on Flow Structure of a Shallow Laminar Round Jet
    CHEN Ke* (陈科), ZHAO Kai (赵恺), YOU Yunxiang (尤云祥)
    2017, 22 (3):  257-264.  doi: 10.1007/s12204-017-1830-8
    Abstract ( 733 )  
    The evolution mechanism and characteristics of the submerged laminar round jet in a viscous homogenous shallow water layer are investigated through computational modeling. The laminar mode is used to solve the Navier-Stokes equations. In order to visualize the formation and evolution of the flow pattern, the volume of fluid (VOF) method is adopted to simulate the free surface of the water layer below the air and to trace the jet fluid. The results show that the jet forms a class of quasi-two-dimensional (Q2D) vortex structures in the ambient fluid with unequal influence from the bottom wall and free surface. The time dependence of three parameters, defined for the flow pattern as jet length, spiral radius and pattern length, is investigated quantitatively in their non-dimensional forms. Three different Reynolds numbers and two injection durations are further considered to discuss their influence on the flow pattern.
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    Lift Distribution Based Design of Two-Dimensional Sections
    RAO Zhiqiang (饶志强), YANG Chenjun* (杨晨俊)
    2017, 22 (3):  265-273.  doi: 10.1007/s12204-017-1831-7
    Abstract ( 610 )  
    A lift distribution based section design method has been proposed. Through Newton-Raphson iterations, the section geometry is efficiently designed to meet the requirements for total lift and lift distribution. The effect of fluid viscosity on total lift is taken into account by coupling Reynolds-averaged Navier-Stokes (RANS) simulation with the potential-flow based design procedure. The present method avoids the difficulty of assigning velocity or pressure distributions on section surfaces. As the loading and thickness distributions are expressed in parametric forms, it is easy to ensure that the designed geometry is continuous and smooth. The effects of lift and thickness distributions on cavitation bucket are numerically investigated. A shift of lift loading towards the aft part of section tends to decrease the margin of back cavitation, while the width of cavitation bucket can be kept almost unchanged. To have a wider cavitation bucket, one can increase the leading edge radius, move properly the location of maximum thickness towards the leading edge, or decrease the curvature at the location of maximum thickness.
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    Hybrid Process of Fabricating High-Quality Micro Wine-Glass Fused Silica Resonators
    XING Yaliang (邢亚亮), ZHANG Weiping* (张卫平), TANG Jian (唐健),SUN Dianjun (孙殿俊), LIU Zhaoyang (刘朝阳), OU Bin (欧斌)
    2017, 22 (3):  274-279.  doi: 10.1007/s12204-017-1832-6
    Abstract ( 678 )  
    A new hybrid method, which combines improved glass-blown technology with wet etching, is reported to fabricate micro wine-glass resonators with high-quality fused silica. The optimum placement is compared to achieve the resonators with good shell shape. The typical shell diameter is about 4mm and its thickness covers from dozens to hundreds of micrometers. The etching rates in corrosion solutions with different ratios and at different thicknesses of hemispherical shells are studied. We also conclude how to precisely control the thickness. The corrosion solutions with different ratios of HF solution to NH4F solution make the spherical shells rougher in different degrees. The best roughness is 0.581 nm in the 1 : 8 ratio corrosion solution while the original roughness is 0.537 nm. This fact shows that the resonator remains atomically smooth surface. Based on the glassblowing spherical fused silica structure, the thickness of the resonator is effectively controlled by buffered oxide etch (BOE) technology according to the measured etching rate. The measured resonant frequency of the hemispherical shell at ambient pressure and room temperature is 1.75 kHz of rocking mode which is close to the simulated frequency. Using such a low-cost hybrid approach, we can fabricate high-quality microscale resonators in batch.
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    Research on Reduction of Fe2O3 by Biomass Sawdust
    LIU Xiaominga,b* (刘晓明), ZHANG Hongleia (张宏雷), LI Suqina (李素芹),LI Dongshenga (李东升), HUANG Dongboa (黄冬波)
    2017, 22 (3):  280-285.  doi: 10.1007/s12204-017-1833-5
    Abstract ( 410 )  
    The research on biomass reduction of Fe2O3 was carried out by using sawdust as reductant. The direct reducing agents in the biomass magnetization process were determined by comparing various biomass pyrolysis products with the reduction degree (divalent iron content in total iron), reduction temperature range and valence change of Fe2O3 in the reduction process. The microstructure variation of Fe2O3 at different stages was also analyzed by scanning electron microscopy (SEM). Nonisothermal thermogravimetric analysis (TGA) was applied to explore the thermal reduction process. The results show that the direct reducing substances in the biomass reaction with Fe2O3 are H2 and bio-oil, and the reduction process can be divided into two steps: biomass pyrolyzing to release H2 and bio-oil, and reductive volatiles reacting with Fe2O3. The two steps are relatively independent. The kinetic of the reduction reaction follows a first-order reaction kinetic model, with 88.99 kJ/mol activation energy and 9.55 × 108 min ?1 frequency factor.
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    Microscopic Structure and Property of Double-Electrode Gas Metal Arc Welding of AZ31B Magnesium Alloy
    MA Guohong1* (马国红), SHEN Xu1 (沈旭), PING Qiwen1 (平齐文),NIE Jun1 (聂军), YE Jia2 (叶佳)
    2017, 22 (3):  286-290.  doi: 10.1007/s12204-017-1834-4
    Abstract ( 689 )  
    This paper focuses on the research on double-electrode gas metal arc welding (DE-GMAW) of AZ31B magnesium alloy sheet with 2mm thickness. During the welding process, stable hybrid arc of metal inert gas (MIG) and tungsten inert gas (TIG) is employed as welding heat source. Optical and electron microscopes are used to observe the microstructures of the weld joint. X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) are employed to identify the components in fusion zone. Microhardness is also tested. When the MIG current is 80A, the perfect weld joint is obtained, though figures of fish scales are observed in all joints in the research. The fusion zone is formed by dendrites, where β-Mg17(Al, Zn)12 is dispersed. The hardness in fusion zone and heat affected zone (HAZ) is lower than that in base metal (BM). The average Vickers hardness of fusion zone and HAZ is about 58 and 56 respectively, while the Vickers hardness of BM is about 63.
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    Semi-Supervised Learning in Large Scale Text Categorization
    XU Zewen1,2 (许泽文), LI Jianqiang1,2,3,4* (李建强), LIU Bo1 (刘博),BI Jing1 (毕敬), LI Rong1 (李蓉), MAO Rui3,4 (毛睿)
    2017, 22 (3):  291-302.  doi: 10.1007/s12204-017-1835-3
    Abstract ( 496 )  
    The rapid development of the Internet brings a variety of original information including text information, audio information, etc. However, it is difficult to find the most useful knowledge rapidly and accurately because of its huge number. Automatic text classification technology based on machine learning can classify a large number of natural language documents into the corresponding subject categories according to its correct semantics. It is helpful to grasp the text information directly. By learning from a set of hand-labeled documents, we obtain the traditional supervised classifier for text categorization (TC). However, labeling all data by human is labor intensive and time consuming. To solve this problem, some scholars proposed a semi-supervised learning method to train classifier, but it is unfeasible for various kinds and great number of Web data since it still needs a part of hand-labeled data. In 2012, Li et al. invented a fully automatic categorization approach for text (FACT) based on supervised learning, where no manual labeling efforts are required. But automatically labeling all data can bring noise into experiment and cause the fact that the result cannot meet the accuracy requirement. We put forward a new idea that part of data with high accuracy can be automatically tagged based on the semantic of category name, then a semi-supervised way is taken to train classifier with both labeled and unlabeled data, and ultimately a precise classification of massive text data can be achieved. The empirical experiments show that the method outperforms the supervised support vector machine (SVM) in terms of both F1 performance and classification accuracy in most cases. It proves the effectiveness of the semi-supervised algorithm in automatic TC.
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    Observer-Based Adaptive Neural Iterative Learning Control for a Class of Time-Varying Nonlinear Systems
    WEI Jianming1* (韦建明), ZHANG Youan2 (张友安), LIU Jingmao3 (刘京茂)
    2017, 22 (3):  303-312.  doi: 10.1007/s12204-017-1836-2
    Abstract ( 371 )  
    In this paper an adaptive iterative learning control scheme is presented for the output tracking of a class of nonlinear systems. An observer is designed to estimate the tracking errors. A mixed time domain and s-domain representation is constructed to derive an error model with relative degree one for our purpose. And time-varying radial basis function neural network is employed to deal with system uncertainty. A new signal is constructed by using a first-order filter, which removes the requirement of strict positive real (SPR) condition and identical initial condition of iterative learning control. Based on property of hyperbolic tangent function, the system tracing error is proved to converge to the origin as the iteration tends to infinity by constructing Lyapunov-like composite energy function, while keeping all the closed-loop signals bounded. Finally, a simulation example is presented to verify the effectiveness of the proposed approach.
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    Lattice-Based Group Signature with Verifier-Local Revocation
    GAO Wen* (高雯), HU Yupu (胡予濮), ZHANG Yanhua (张彦华), WANG Baocang (王保仓)
    2017, 22 (3):  313-321.  doi: 10.1007/s12204-017-1837-1
    Abstract ( 578 )  
    Among several post quantum primitives proposed in the past few decades, lattice-based cryptography is considered as the most promising one, due to its underlying rich combinatorial structure, and the worst-case to average-case reductions. The first lattice-based group signature scheme with verifier-local revocation (VLR) is treated as the first quantum-resistant scheme supported member revocation, and was put forward by Langlois et al. This VLR group signature (VLR-GS) has group public key size of O(nmlogN log q), and a signature size of O(tm logN log q log β). Nguyen et al. constructed a simple efficient group signature from lattice, with significant advantages in bit-size of both the group public key and the signature. Based on their work, we present a VLR-GS scheme with group public key size of O(nm log q) and signature size of O(tm log q). Our group signature has notable advantages: support of membership revocation, and short in both the public key size and the signature size.
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    Human Machine Collaborative Support Scheduling System of Intelligence Information from Multiple Unmanned Aerial Vehicles Based on Eye Tracker
    JIAN Lixuan* (简立轩), YIN Dong (尹栋), SHEN Lincheng (沈林成), NIU Yifeng (牛轶峰)
    2017, 22 (3):  322-328.  doi: 10.1007/s12204-017-1838-0
    Abstract ( 459 )  
    Many human-machine collaborative support scheduling systems are used to aid human decision making by providing several optimal scheduling algorithms that do not take operator’s attention into consideration. However, the current systems should take advantage of the operator’s attention to obtain the optimal solution. In this paper, we innovatively propose a human-machine collaborative support scheduling system of intelligence information from multi-UAVs based on eye-tracker. Firstly, the target recognition algorithm is applied to the images from the multiple unmanned aerial vehicles (multi-UAVs) to recognize the targets in the images. Then, the support system utilizes the eye tracker to gain the eye-gaze points which are intended to obtain the focused targets in the images. Finally, the heuristic scheduling algorithms take both the attributes of targets and the operator’s attention into consideration to obtain the sequence of the images. As the processing time of the images collected by the multi-UAVs is uncertain, however the upper bounds and lower bounds of the processing time are known before. So the processing time of the images is modeled by the interval processing time. The objective of the scheduling problem is to minimize mean weighted completion time. This paper proposes some new polynomial time heuristic scheduling algorithms which firstly schedule the images including the focused targets. We conduct the scheduling experiments under six different distributions. The results indicate that the proposed algorithm is not sensitive to the different distributions of the processing time and has a negligible computational time. The absolute error of the best performing heuristic solution is only about 1%. Then, we incorporate the best performing heuristic algorithm into the human-machine collaborative support systems to verify the performance of the system.
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    Three-Dimensional Geoscience Modeling and Simulation of Gas Explosion in Coal Mine
    CHE Defu* (车德福), ZHOU Honghe (周鸿鹤)
    2017, 22 (3):  329-333.  doi: 10.1007/s12204-017-1839-z
    Abstract ( 390 )  
    Gas explosion is one of the most serious events in coal mine. In consideration of the limitation of past research method about gas explosion, three-dimensional (3D) modeling and simulation are suggested. This paper analyzes the research achievements on 3D modeling, and studies the modeling method of strata and laneway based on geoscience modeling. After the 3D modeling of strata and laneways, the simulation of gas explosion (such as gas exploding, color, burning, virtual wandering and rock caving) is performed. The research method is meaningful for safety analysis and safety survey.
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    A Method to Analyze the Voltage-Actuation Response of a Pre-Strained Circular Dielectric Elastomer Actuator Model
    TRAN Danhquang (陈名光), LI Jin* (李锦), XUAN Fuzhen (轩福贞)
    2017, 22 (3):  334-342.  doi: 10.1007/s12204-017-1840-6
    Abstract ( 375 )  
    Dielectric elastomers (DEs) are the polymers capable of inducing deformation under electrical stimulation. When subject to a voltage across its thickness, the material reduces in thickness and expands in area. This paper presents a new method to analyze deformation and stress distribution response of the dielectric elastomer actuator (DEA) model under different applied voltage. An equal-biaxial pre-strained circular actuator model was built. The Yeoh strain energy potential and the collocation method are used for describing the large strain actuation response and stress distribution. The study in this paper has shown that: the stress and the stretch distributions in the passive region of the DE actuator depend on the radial distance from the center at the calculation point of the passive region and the magnitude of the applied voltage; with the same excitation applied voltage, we can get a larger deformation actuation by choosing an appropriate pre-stretch ratio; the influence of the non-ideal material has seriously affected the actual deformation of the DE actuators. This analytical model has a reference potential for the design optimization of high performance DEA systems and the model-based control of the DEA robot.
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    A Generalized Self-Consistent Model for Interfacial Debonding Behavior of Fiber Reinforced Rubber Matrix Sealing Composites
    ZHANG Bin1,2* (张斌), YU Xiaoming1 (宇晓明), GU Boqin3 (顾伯勤)
    2017, 22 (3):  343-348.  doi: 10.1007/s12204-017-1841-5
    Abstract ( 304 )  
    This paper presents an experimental and numerical study of short-fiber-reinforced rubber matrix sealing composites (SFRC). The transverse tensile stress-strain curves of SFRC are obtained by experiments. Based on the generalized self-consistent method, a representative volume element (RVE) model is established, and the cohesive zone model is employed to investigate the interfacial failure behavior. The effect of interphase properties on the interfacial debonding behavior of SFRC is numerically investigated. The results indicate that an interphase thickness of 0.3 μm and an interphase elastic modulus of about 502MPa are optimal to restrain the initiation of the interfacial debonding. The interfacial debonding of SFRC mainly occurs between the matrix/interphase interface, which agrees well with results by scanning electron microscope (SEM).
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    Graph Based Signal-Behavior-Structure Mapping for State Maintenance of Equipment
    ZHANG Wei1 (张伟), HOU Yuemin1,2* (侯悦民)
    2017, 22 (3):  349-354.  doi: 10.1007/s12204-017-1842-4
    Abstract ( 349 )  
    Equipment has dual nature: physical objects existing in nature, and artificial objects designed by human. The decision on the configuration and structural parameters of equipment is made by engineers based on technical-physical effects which control the behavioral parameters of the equipment. Sensors are mounted on the equipment to monitor the equipment state. Current methods for state monitoring and diagnosis mostly use mathematics and artificial intelligence technology to construct evaluation methods. This paper presents an integrated design and state maintenance method, in which graph and dual graph are used for recording design data and sensor arrangement and for mapping method from signals to substructures and connection pairs. An example of state maintenance of hydro power generating equipment is illustrated.
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    Research and Application of New Threshold De-noising Algorithm for Monitoring Data Analysis in Nuclear Power Plant
    CUI Yan* (崔妍), CHEN Shijun (陈世均), QU Meng (瞿勐), HE Shanhong (何善红)
    2017, 22 (3):  355-360.  doi: 10.1007/s12204-017-1843-3
    Abstract ( 344 )  
    Under the complex condition of nuclear power plant, all kinds of influence factors may cause distortion of on-line monitoring data. It is essential that on-line monitoring data should be de-noised in order to ensure the accuracy of diagnosis. Based on the research of wavelet analysis and threshold de-noising, a new threshold denoising method based on Mallat transform is proposed. This method adopts factor weighing method for threshold quantization. Through the specific case of nuclear power plant, it is verified that the algorithm is of validity and superiority.
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    Comparison Analysis of Efficiency Between Double-Synchronous Step-Down-Stress and Step-Up-Stress Accelerated Life Tests
    KOU Haixia (寇海霞), AN Zongwen* (安宗文), SUN Daoming (孙道明)
    2017, 22 (3):  361-364.  doi: 10.1007/s12204-017-1844-2
    Abstract ( 419 )  
    Double-crossed-step-stress (DCSS) accelerated life test (ALT) method is widely used for estimating the lifetime of products with high reliability and long lifetime. In order to further reduce the test time and test cost, a double-synchronous-step-stress (DSSS) ALT method which combines a double-synchronous-step-downstress (DSSDS) ALT method and a double-synchronous-step-up-stress (DSSUS) ALT method is proposed. The accelerated stresses decrease and increase in a synchronous way with one step in the DSSDS-ALT and DSSUSALT methods, respectively. Monte Carlo method is adopted to simulate the two methods, and the validity and efficiency of them are demonstrated by the simulation results. In addition, a comparison analysis of efficiency between DSSDS-ALT method and DSSUS-ALT method is carried out. The result shows that the DSSDS-ALT method compared with the DSSUS-ALT method can significantly improve the test efficiency under the same test condition.
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    Welded Joint Fatigue Reliability Analysis on Bogie Frame of High-Speed Electric Multiple Unit
    LI Yonghua* (李永华), QIN Qiang (秦强), WANG Yuedong (王悦东), HU Mingguang (胡明广)
    2017, 22 (3):  365-370.  doi: 10.1007/s12204-017-1845-1
    Abstract ( 394 )  
    A new method for welded joint fatigue reliability analysis on bogie frame of high-speed electric multiple unit (EMU) is proposed according to the International Union of Railways (UIC) standard, the Britain Standard Institute (BSI) standard and the Miner rule. Firstly, the fatigue calculation condition is loaded according to the UIC standard. The welded joint damage ratio is calculated by the BSI standard. Fatigue reliability analysis is conducted for a typical welded joint based on probabilistic design system (PDS) module in software ANSYS 14.0. In the system, the automatic program is prepared by ANSYS parametric design language (APDL) to calculate the welded joint fatigue damage ratio. Meantime, the relationship between the input variables and the output response is fitted by the response surface (RS) method. Then, the RS method is improved by the orthogonal design. Specifically, the selecting process optimization for the RS method based on the orthogonal design is conducted to improve the fitting efficiency of the RS method. Finally, a program of the automatic analysis documents is generated by Microsoft foundation class (MFC) technique. Through the self-defined interface, the researchers can easily import the automatic generation of the orthogonal table into the PDS module and analyze the fatigue reliability. Results show that the improved RS method can better fit the RS which covers the sample area, and the distribution law agrees well with the actual situation. At the same time, the improved RS method reduces the calculation time.
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    Adomian’s Method Applied to Solve Ordinary and Partial Fractional Differential Equations
    HAO Lili1,2 (郝丽丽), LI Xiaoyan1* (李晓艳), LIU Song1 (刘松), JIANG Wei1 (蒋威)
    2017, 22 (3):  371-376.  doi: 10.1007/s12204-017-1846-0
    Abstract ( 369 )  
    This paper presents a method to solve the problems of solutions for integer differential and partial differential equations using the convergence of Adomian’s Method. In this paper, we firstly use the convergence of Adomian’s Method to derive the solutions of high order linear fractional equations, and then the numerical solutions for nonlinear fractional equations. we also get the solutions of two fractional reaction-diffusion equations. We can see the advantage of this method to deal with fractional differential equations.
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    Automatic Outer Surface Extraction of Femoral Head in CT Images
    WAN Daqian1 (万大千), WANG Dong2 (王东), MA Anbang4 (马安邦),DAI Kerong2,4 (戴尅戎), AI Songtao3* (艾松涛), WANG Liao2* (王燎)
    2017, 22 (3):  377-384.  doi: 10.1007/s12204-017-1847-z
    Abstract ( 329 )  
    Computer-aided hip surgery planning and implant design applications require accurate segmentation of femoral head and proximal acetabulum. An accurate outer surface extraction of femoral head using marching cubes algorithm remains challenging due to deformed shapes and extremely narrow inter-bone regions. In this paper, we present an automatic and fast approach for segmentation of femoral head and proximal acetabulum which leads to accurate and compact representation of femoral head using marching cubes algorithm. At first, valley-emphasized images are constructed from original images so that valleys stand out in high relief. Otsu’s multiple thresholding technique is applied to seperate the images into bone and non-bone classes. Region growing method and threedimensional (3D) morphological operations are performed to fill holes in the bone. In the reclassification process, the bone regions are further segmented, and the boundaries of the bone regions are further refined based on Bayes decision rule. Finally, marching cubes algorithm is applied to reconstruct a 3D model and extract the outer surface of femoral head and proximal acetabulum. Experimental results show that this method is an accurate segmentation technique for femoral head and proximal acetabulum and it can be applied as a tool in medical practice.
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