Loading...

Archive

    For Selected: Toggle Thumbnails
    Information & Control
    Document Clustering of Fuzzy C-Means Based on Black Hole Algorithm
    LIU Yu-hui, WANG Wei-chao, MENG Lei
    2017, 38 (8):  1065-1069.  DOI: 10.12068/j.issn.1005-3026.2017.08.001
    Abstract ( 696 )   HTML   PDF (453KB) ( 945 )  
    When fuzzy c-means (FCM) algorithm is applied to document clustering, the result is not ideal because of its initial cluster center points’ random selection and falling into the local optimal solution easily. Aiming at improving the FCM’s clustering accuracy, a method is proposed which uses the black hole algorithm (BHA), a heuristic algorithm, to find FCM’s optimal initial clustering centers. During searching for the FCM’s best initial clustering centers, the black hole is considered as the optimal option, and the FCM’s best initial clustering centers can be found. The experiment’s results show that the document clustering of FCM based on black hole algorithm can solve the problem that FCM is sensitive to initial centers and easy to fall into the local optimal solution, and finally, the clustering accuracy is improved significantly.
    References | Related Articles | Metrics
    Design and Implementation of a QoS-Enabled Measuring and Routing System Based on SDNs
    LIN Chuan, ZHAO Hai, BI Yuan-guo, CAI Wei
    2017, 38 (8):  1069-1074.  DOI: 10.12068/j.issn.1005-3026.2017.08.002
    Abstract ( 842 )   HTML   PDF (2033KB) ( 1345 )  
    The QoS-enabled measuring and routing system is designed and realized by adopting the OpenFlow. The abilities of measuring link delay, load and packet loss are realized by utilizing the interactive messages between the controller and the OpenFlow-enabled switch. In order to solve the problem of multiple constraints during QoS routing, a multiple constraints routing algorithm is improved and realized with the QoS metrics (link delay, load and packet loss) considered. The experimental results show that the system proposed is able to measure the QoS metric and change the routing path based on QoS measurement, and it meets the needs of system design.
    References | Related Articles | Metrics
    A Method of Blood Pressure Estimation Based on Cellphone Camera
    ZHAO Hai, XU Jin, CHEN Xing-chi, LI Yu-zhe
    2017, 38 (8):  1075-1078.  DOI: 10.12068/j.issn.1005-3026.2017.08.003
    Abstract ( 884 )   HTML   PDF (422KB) ( 1426 )  
    A method of blood pressure estimation is proposed based on pulse waves collected by the cellphone cameras, referred to as multiparameter estimation of systolic blood pressure based on pulse waves (MBPP). Through the exercise test, some different timing pulse wave data and blood pressure data are obtained. Then, the pulse wave data are denoised and the acceleration pulse waves are calculated, to get the pulse wave transit time. And then, the characteristics of the pulse wave are calculated to get the heart rate. At last, the pulse wave transit time, heart rate and blood pressure can be selected to generate the linear fitting formula. Experimental results show that the MBPP proposed is a high accuracy method, and can be used to measure blood pressure.
    References | Related Articles | Metrics
    Improved ASFCM-based Algorithm for Infant Brain MRI Segmentation
    WEI Ying, ZHANG Kai, HAN Feng
    2017, 38 (8):  1079-1084.  DOI: 10.12068/j.issn.1005-3026.2017.08.004
    Abstract ( 757 )   HTML   PDF (1095KB) ( 792 )  
    Among many modified fuzzy c-mean (FCM) algorithms, the adaptive spatial fuzzy c-means (ASFCM) clustering algorithm is quite advantageous, as it has the adaptive parameters and changes the structure of spatial penalty to make the objective function continuous, but it cannot restrain the large noise contained by infant brain MR images. In response to this issue, we improve the ASFCM algorithm with non-local weights and the kernel function, which is named as the improved ASFCM algorithm with kernel function and non-local weights. Then, the FCM algorithm, RFCM algorithm, ASFCM algorithm and the algorithm we proposed are used to segment the clinical infant brain MR images with different kinds and intensities of noise. Results show that the segmentation accuracy and denoising ability of the proposed algorithm are greatly improved compared with the other three algorithms, and our algorithm has obvious advantages for the infant brain MR image segmentation.
    References | Related Articles | Metrics
    Materials & Metallurgy
    Effect of Austenitizing Temperature on the Microstructure and Tensile Properties of Fe-17Mn-0.05C Steel
    LI Xing, CHEN Li-qing
    2017, 38 (8):  1084-1087.  DOI: 10.12068/j.issn.1005-3026.2017.08.005
    Abstract ( 591 )   HTML   PDF (2652KB) ( 754 )  
    The effect of austenitizing temperature (tA) on the microstructure and tensile properties for a hot-rolled high-Mn structure steel with excellent damping capacity after heat treatment with different tA has been investigated. The results show that when the tA is up to 600℃, the only recovery occurs in the reversed austenite,and the ε-martensite amount, tensile stress and work hardening rate of the treated steel are higher than those of the rolling state one. When the tA is over 800℃, the completely static recrystallization of austenite can be observed. Moreover, the austenite size and ε-martensite amount of the steel increase with the tA, which results in the deterioration of its tensile properties. Furthermore, after treated at tA=1200℃, the ε-martensite plate becomes very thin,and the fracture along grain boundary is also observed during tensile test owing to the over-sized austenite grains.
    References | Related Articles | Metrics
    Corrosion Behavior of Armor Layer Steel of Flexible Pipes Exposed to Seawater Environment
    LIU Zhen-guang, GAO Xiu-hua, DU Lin-xiu, LI Jian-ping
    2017, 38 (8):  1088-1092.  DOI: 10.12068/j.issn.1005-3026.2017.08.006
    Abstract ( 549 )   HTML   PDF (5021KB) ( 724 )  
    Immersion experiment was carried out to investigate the corrosion behavior of armor layer steel immersed in a simulated seawater environment. The experimental results demonstrate that the microstructure of the designed steel is made of tempered martensite. Meanwhile, Cr-rich precipitated particles are observed in the substrate of the steel. Corrosion rate decreases with prolonging corrosion time, and the final corrosion rate is 0.0689mm·a-1. The corrosion behavior can be divided into three stages: the fast decreasing stage, stable transitional stage and slow decreasing stage. The major corrosion products are α-FeOOH, γ-FeOOH, Fe3O4, and Fe2O3. With increasing corrosion time, the structure of corrosion products becomes more compact and their thickness is wider. Chromium element tends to accumulate in the corrosion products.
    References | Related Articles | Metrics
    Heat Transfer Coefficient for ESR Inner Mold of Hollow Cylindrical Casting
    WANG An-guo, JIANG Zhou-hua, LOU Yan-chun, XIONG Yun-long
    2017, 38 (8):  1093-1098.  DOI: 10.12068/j.issn.1005-3026.2017.08.007
    Abstract ( 669 )   HTML   PDF (1788KB) ( 830 )  
    ESR hollow cylindrical casting inner mold heat transfer coefficient α○in is the core parameter to measure the effect of inner mold cooling. The range of α○in was determined by inputting the measured values, including cooling surface temperature of the inner mold copper plate and water temperature, into basic formula and finite element analysis. The empirical formula for calculating αin was determined by comparing with the empirical formula of heat transfer coefficient for annular casting. The experiential formula of α○in explicates the effects of temperature difference, the short pipe effect and the shape factor of inner mold water model on αin by using temperature difference function, effector and velocity function, which provides a theoretical basis for α○in database establishment.
    References | Related Articles | Metrics
    Bubble Bottom Edge Migration Behavior During Bubble Growth and Detachment Process
    GENG Dian-qiao, ZHANG Li-an, GOU Da-zhao, LEI Hong
    2017, 38 (8):  1098-1101.  DOI: 10.12068/j.issn.1005-3026.2017.08.008
    Abstract ( 652 )   HTML   PDF (548KB) ( 894 )  
    The bubble growth and detachment was recorded using a high speed video technology. The post-processing of photos was completed by Image-Pro Plus 6.0 software. The bubble shape variation during bubble growth under the condition of two kinds of different tube diameters was investigated. The experimental results show that the dominant force during bubble growth is different for different diameter tube. The increment of bubble aspect ratio from the small diameter tube with time is greater at first and then becomes smaller, while that from the large diameter one with time is firstly smaller and then greater afterward. Since the bubble detachment condition cannot be satisfied for the small diameter tube, the bubble bottom edge migrates towards liquid side. On the other hand, the bubble detachment condition can be reached for the large tube when the angle between gas-liquid line and solid-liquid line is smaller than the contact angle, therefore the bubble bottom edge cannot migrate towards liquid side. The critical bubble aspect ratio for detachment of 3.80mm bubble is slightly larger than that of 9.28mm bubble.
    References | Related Articles | Metrics
    Preparation of High Purity Al(OH)3from the Sulfating Solution of Potash Feldspar Roasting Residue
    LIU Jia-nan, HUANG Jian-di, WU Yan , ZHAI Yu-chun
    2017, 38 (8):  1102-1106.  DOI: 10.12068/j.issn.1005-3026.2017.08.009
    Abstract ( 525 )   HTML   PDF (1098KB) ( 706 )  
    Employing the sulfating solution of potash feldspar roasting residue as raw materials and Na2CO3 solution as precipitator, the high purity Al(OH)3 was prepared. The effects of the pH value at the end of precipitating Al, reaction temperature, aging time and the mass concentration of Na2CO3 solution on the precipitation rate of Al were investigated. Al(OH)3 powder was characterized by chemical component analysis, X-ray diffraction(XRD), scanning election microscope(SEM), and Fourier transform infrared spectroscopy (FTIR). The optimum technological conditions, which could guarantee the precipitation rate of Al more than 99%,were to keep reaction temperature at 50℃, add the Na2CO3 solution with the mass concentration of 300g/L into Al2(SO4)3 solution, control the pH value at 4.8 and the aging time for 40min. The features for the produced Al(OH)3 powder were that the crystal was amorphous, the particles were homogeneous with rough surface and the particles agglomeration occurred.
    References | Related Articles | Metrics
    Study on Technological Mineralogy of Rare Earth Tailings from Bayan Obo
    ZHENG Qiang, BIAN Xue, WU Wen-yuan
    2017, 38 (8):  1107-1111.  DOI: 10.12068/j.issn.1005-3026.2017.08.010
    Abstract ( 697 )   HTML   PDF (2338KB) ( 1293 )  
    The chemical composition, mineral composition and dissemination characteristics of rare earth tailings from Bayan Obo were investigated by the means of X-ray diffraction, scanning electron microscopy, mineral liberation analyzer, electron probe microanalysis and chemical analysis. The results show that the tailings have complex compositions and fine disseminated size. In the tailings, the rare earth minerals contain bastnaesite and monazite, while iron mainly exists in the form of hematite and fluorine is in the fluorite. The liberation degrees of rare earth minerals, hematite and fluorite are 87.28%,89.15% and 96.70%, respectively. Niobium occurs in the niobium minerals, such as pyrochlore, niobite, teshirogilite, ilmenorutile and etc. Scandium distributes in the silicate minerals and thorium occurs in the rare earth minerals in isomorphism. The results may provide the evidence for the efficient and comprehensive utilization of the rare earth tailing from Bayan Obo.
    References | Related Articles | Metrics
    Mechanical Engineering
    An Evaluating Method for Transmission Gear Undercutting in a Power Tool Turret
    LIANG Song, ZHANG Yi-min
    2017, 38 (8):  1112-1117.  DOI: 10.12068/j.issn.1005-3026.2017.08.011
    Abstract ( 710 )   HTML   PDF (749KB) ( 752 )  
    A brief evaluating method for transmission gear undercutting is proposed. The method is based on the technology of polynomial mutation operator and particle swarm optimization (PMOPSO). The undercutting model is established based on the parametric equations for involute gear profiles and the relationship between model solutions and undercutting points is investigated. The as-proposed method is used for evaluating undercutting of key gears in a power turret. The effects of modules and modification coefficients on undercutting are studied. The results imply that the proposed method is able to calculate gear undercutting rapidly. Meanwhile, the accuracy is geared to design requirements flexibly. The situation of key gear undercutting can be analyzed accurately by the proposed way, which may contribute to improve the transmission performance of turrets.
    References | Related Articles | Metrics
    Dynamics of Rotor Bearing System with New Rubbing Model in Maneuvering Flight
    LI Xiao-peng, LI Jia-sheng, LI Mu-yan, WEN Bang-chun
    2017, 38 (8):  1118-1122.  DOI: 10.12068/j.issn.1005-3026.2017.08.012
    Abstract ( 728 )   HTML   PDF (1044KB) ( 816 )  
    A new rubbing model is proposed, which considers the change in rotor-stator clearance and the number of blades. The maneuver load caused by maneuvering flight and nonlinear Hertz contact force of rolling bearing are also considered. The nonlinear dynamic differential equation of rotor-ball bearings-rubbing coupling system is established by using the finite element method. The effects of rotational speed and maneuver load on the dynamic behavior of the system are analyzed. It is shown that the sub-harmonic resonance of rotor system increases under the rubbing fault. The high frequency components are excited by the rubbing fault at lower speeds, while the low frequency components are excited by the rubbing fault at high speeds. The maneuver load makes the rotor’s vibration increase, which may result in the rubbing fault between the rotor and the stator.
    References | Related Articles | Metrics
    Analytical Analysis of Natural Characteristics for Cantilevered Laminate Plate with Hard-Coating
    SUN Wei, LIU Xiao-zhou, WANG Zhuo, ZHU Ming-wei
    2017, 38 (8):  1123-1127.  DOI: 10.12068/j.issn.1005-3026.2017.08.013
    Abstract ( 585 )   HTML   PDF (1520KB) ( 688 )  
    Based on the Ritz theory, an analytical method of solving the natural characteristics of hard-coating cantilever laminate plate was developed. The strain and kinetic energy of composite plate was characterized by the displacement of neutral surface, then the free vibration equation was derived and the methods of solving natural frequency, mode shape and modal loss factor were presented. A T300/QY89l1 laminate plate coated with NiCoCrAlY+YSZ hard coating was chosen to demonstrate the as-proposed method. The natural characteristics were calculated by the as-proposed method and ANSYS software, respectively. The obtained results were compared with the purpose of assessing the rationality of the method proposed. The practice shows that the natural characteristic parameters of hard-coating cantilever laminate plate with engineering significance can be obtained by treating the hard-coating layer as a special layer and implementing the inverse transformation of dimension.
    References | Related Articles | Metrics
    Experimental Research on Wear Mechanism of Micro-grinding Tool in Grinding Soda-Lime Glass
    GONG Ya-dong, HUANG Xiong-jun, WEN Xue-long, ZHOU Jun
    2017, 38 (8):  1128-1132.  DOI: 10.12068/j.issn.1005-3026.2017.08.014
    Abstract ( 607 )   HTML   PDF (701KB) ( 654 )  
    Single grain abrasive wear model is established for the micro grinding process. The abrasive wear at different stages in micro-grinding process is analyzed by the observation toward the diameter variation and the surface appearance of the micro-grinding tools as well as the surface quality variation of the workpieces. Tool wearing influence rules caused by various grinding influence factors are also studied through single-factor experiments on soda-lime glass, with #500 particle size micro-grinding tools adopted. The experiment results indicate that the wear and breakage of abrasive grains are increased as long as the feed speed and feed rate increase during the micro grinding process. In addition, as the material removal volume increases, the diameter of the micro grinding tool decreases sharply at first, and then decreases linearly. Generally, a decrease trend of the roughness value is observed form the machine surface. The achievements of this paper provides theoretical and experimental basis for increasing working life and improving processing performance of micro-grinding tool.
    References | Related Articles | Metrics
    Experimental Analysis Toward Wear Characteristics and Mechanisms for S30T Tools Through Orthogonal Turning-Milling on TC4 Titanium Alloy
    SHI Li, GONG Ya-dong, JIANG Zeng-hui
    2017, 38 (8):  1133-1136.  DOI: 10.12068/j.issn.1005-3026.2017.08.015
    Abstract ( 632 )   HTML   PDF (1878KB) ( 708 )  
    Orthogonal turning-milling experiments toward S30T tools machining on TC4 titanium alloy under dry cutting conditions with 100-250m/min cutting speeds were performed with Mazak Integrex 200Y machining center. The results indicated that BUE(build-up edge) and crater wear occured, as well as coating wear and delamination on the rake face after dry cutting. On the flank face, tips, groove and tipping were observed. The main causes of the tool wear were adhesion wear, oxidation wear and delamination of coating.X-ray photoelectron spectroscopy (XPS) observation showed that a lot of oxides, such as TiO2,Al2O3,CoO etc were generated in the oxidation.
    References | Related Articles | Metrics
    Research and Design on Modular Humanoid Finger with SMA Actuator
    HAO Li-na, GUO Shao-fei, CHEN Yang
    2017, 38 (8):  1137-1141.  DOI: 10.12068/j.issn.1005-3026.2017.08.016
    Abstract ( 877 )   HTML   PDF (1341KB) ( 1035 )  
    Modularized underactuated mechanical fingers are designed.For the actuator, SMA(shape memory alloy) wires are adopted, and permanent magnet devices are also used as the source of pre-stretching and restoring forces. This novel design increases the SMA output force for over 6N more than the conventional SMA actuators, in which bias springs are adopted as the pre-stretching elements. A pulley system is also developed for amplifying the displacement output capacity of the actuator by 2.1 times. The mechanical fingers are fabricated by 3D printing technology, and general grasping experiments are carried out with daily commodities. This paper proposes the method for resolving the conflicts among the displacement output capacity, the pre-stretching force and the output force. The achievements will facilitate the further application of the SMA materials in biomimetic actuating fields.
    References | Related Articles | Metrics
    Analysis on Critical Influential Factors of Axial Load Uniform Distribution in Bolted Joint
    CHEN Yan, LU Xu, JIANG Peng, GUAN Zhen-qun
    2017, 38 (8):  1142-1147.  DOI: 10.12068/j.issn.1005-3026.2017.08.017
    Abstract ( 877 )   HTML   PDF (681KB) ( 914 )  
    The critical influential factors of axial load uniform distribution in bolted joint are explored by theoretical analysis and numerical simulation. Firstly, theoretical analysis was done toward the axial load distribution of the bolted joint. An analytical method of confirming the axial load distribution by using the relationship between axial load per unit length F and relative deformation u is proposed. Besides, the result of theoretical analysis shows that the axial load distribution is more uniform when the shape of F-u curve presents yield-type. Secondly, through the analysis on Spiralock thread, the shape of F-u curve is also observed as yield-type. Then the mechanics mechanism for the Spiralock thread having better distribution uniformity is clarified from three aspects: tooth design, material plasticity and thread slip. Lastly, the factors, such as radial dimension coefficient, friction coefficient and material elastic modulus ratio which affect the load distribution are systematically studied.
    References | Related Articles | Metrics
    Effect of Hydrogen Content of CH4-H2 Mixture on Structure of Turbulent Diffusion Flame Under MILD Condition
    XIE Yi, ZHONG Chen, TAN Chuan-zhi, LIU Xiao-bing
    2017, 38 (8):  1148-1153.  DOI: 10.12068/j.issn.1005-3026.2017.08.018
    Abstract ( 593 )   HTML   PDF (1339KB) ( 671 )  
    MILD combustion in the second stage of JHC experiment was simulated by using two-dimensional axisymmetric numerical simulation method. The influence of hydrogen content of CH4-H2 mixture on the turbulent diffusion flame was studied under the condition of constant volume flux of fuel mixture. The results show that the mixing between fuel and oxidant augments, the velocity magnitude and its radial component falls down with the increase of hydrogen content of fuel mixture. In addition, as the hydrogen content of fuel mixture goes up, the flame front gradually leans to the oxidant side and the max mass fraction of OH free radical goes up firstly and then goes down. As for the combustion temperature, although the combustion temperature in the main exothermic reaction zone increases with increasing the hydrogen content of fuel mixture, the influence of hydrogen content on the temperature is very small when it is over 20%.
    References | Related Articles | Metrics
    Resources & Civil Engineering
    Effect of Serpentine on Flotation of Ascharite
    LI Zhi-hang, HAN Yue-xin, LI Yan-jun, GAO Peng
    2017, 38 (8):  1154-1157.  DOI: 10.12068/j.issn.1005-3026.2017.08.019
    Abstract ( 620 )   HTML   PDF (466KB) ( 756 )  
    Aiming at the problem that serpentine can deteriorate the flotation environment of ascharite, the effects of different sizes of serpentine and minerals ratio on the flotation efficiency of ascharite were investigated by flotation experiments. The results showed that the interaction between serpentine and ascharite particles can occur easily during flotation process. With the increase of content and the decrease of particle size for serpentine,the recovery of ascharite decreases gradually. Besides, fine serpentine has more prominent effect on flotation recovery of ascharite and can lower the recovery of ascharite more remarkably. The mechanism of mineral particles interaction was also studied through zeta potential analysis and DLVO theory calculation. The result indicated that minerals surfaces with opposite charges are the basic reason of the interaction between mineral particles.
    References | Related Articles | Metrics
    Testing Investigation on Effective Stress Increment of Unsaturated Sandy Soils
    LI Chun, ZHAO Fu-li, XIU Zhan-guo, WANG Qiu-hong
    2017, 38 (8):  1158-1162.  DOI: 10.12068/j.issn.1005-3026.2017.08.020
    Abstract ( 751 )   HTML   PDF (526KB) ( 715 )  
    In order to investigate the vertical deformation contributed by effective stress increment of soils overlying foundation base, the saturation test of unsaturated sandy soil and the static load test were conducted with different axial loads and cell pressures, and work of calculation and analysis based on Mohr-Coulomb’s method was finished. The main physical and mechanical indexes of gravelly sand and gravel, such as natural gravity, cohesion and angle of internal friction etc., were obtained under condition of saturation. Effective stress increment and its vertical deformation were obtained by using the indexes. The results indicate that degree of saturation of gravel is more easily to reach 100% compared with gravelly sand, and saturated unit weight of gravel is larger, but porosity and water content of gravel are smaller than that of gravelly sand. As to saturated sandy soil, the principal stress computed by effective stress method is usually larger than that by total stress method, thus angle of internal friction and cohesion obtained by effective stress method are more reasonable. In addition, vertical deformation contributed by effective stress increment can not be ignored.
    References | Related Articles | Metrics
    Experimental Study on the New Filter Made from Sea-Island Fibers
    TIAN Xin-jiao, LIU Jing-xian, MAO Ning, CHANG De-qiang
    2017, 38 (8):  1163-1166.  DOI: 10.12068/j.issn.1005-3026.2017.08.021
    Abstract ( 690 )   HTML   PDF (1402KB) ( 744 )  
    Developing superfine fiber filter is one of the main technical methods to control PM2.5. An experimental setup was used according to the national standards, and the filtration performance of sea-island-fiber filters was studied comprehensively.Such parameters as the filter efficiency of filter material, the residual resistance and the ash cleaning cycle were obtained, and a comparison was made with the traditional needle felt filters and membrane filters. The results showed that the counting efficiency of sea-island-fiber filters for PM2.5 is 94.9%, which is far higher than that of the traditional filters and similar to that of the membrane filters; meanwhile, the residual resistance of the dynamic filtration process is lower than that of the membrane filters, the residual resistance increases slowly, and the ash cleaning cycle becomes longer, which is conducive to prolonging the filterlife and saving cost.
    References | Related Articles | Metrics
    Simulation Model of Granular Flow of the Non-uniform Caved Ore and Rock
    LIU Xiao-bo, WANG Lian-cheng
    2017, 38 (8):  1167-1172.  DOI: 10.12068/j.issn.1005-3026.2017.08.022
    Abstract ( 561 )   HTML   PDF (1204KB) ( 708 )  
    By combining the discrete element method with the stochastic medium theory, the collision movement model of non-uniform granular media is proposed, which includes random generation of particles, stability analysis of granular units, initial movement of granular unit, collision process of granular unit and randomness of movement of particles and so on. Based on the established collision movement model of non-uniform granular media, a 2D drawing simulation system was developed using C# language, which includes four modules of parameter input, model generation, emulational simulation, and data statistics. A pillarless sublevel drawing simulation scheme was designed and was found to be consistent with the study from relevant literatures, indicating it is feasible to simulate discrete granule flow using collision movement model of non-uniform granular media.
    References | Related Articles | Metrics
    Preparation and Dry-Shrinkage Performance of Nano-Concrete
    LI Wei, ZHU Fu-sheng, WANG Xiao-chu, ZHAO Yan-ming
    2017, 38 (8):  1173-1177.  DOI: 10.12068/j.issn.1005-3026.2017.08.023
    Abstract ( 698 )   HTML   PDF (556KB) ( 736 )  
    Based on experimental and theoretical analysis, new nano-concrete was made by adding different dosage of nano-SiO2 and nano-CaCO3 into ordinary concrete. The influence of nano-materials on the internal structure of concrete was analyzed by electron microscope observation. The impact of different nano-materials on the dry-shrinkage rate of concrete was compared through the dry-shrinkage tests, and the optimal dosage of nano-material was found. Results show that both nano-SiO2 and nano-CaCO3 can change the dry-shrinkage rate of the concrete, however, the changing rate of dry-shrinkage for concrete with nano-SiO2 is more obvious than that with nano-CaCO3. When the nano-SiO2 content is 0.5% or when the nano-CaCO3 content is 2.0%, the dry-shrinkage rate is the minimum. It is also found that there exists dynamic equilibrium relationship between the concrete shrinkage, the dense degree of concrete and the number of meniscus and internal humidity.
    References | Related Articles | Metrics
    Electrical Resistivity Characteristic and Influence Factors of Diesel Contaminated Silty Clay
    BIAN Han-liang, LIU Song-yu, CAI Guo-jun, CHU Ya
    2017, 38 (8):  1177-1182.  DOI: 10.12068/j.issn.1005-3026.2017.08.024
    Abstract ( 736 )   HTML   PDF (588KB) ( 739 )  
    Silty clay from Nanjing city was used as parent soil for preparing diesel-contaminated soils with various moisture content and diesel content. The soil resistivity of diesel-contaminated soils was then determined by a Miller Soil Box to estimate the variation of the resistivity with moisture content, diesel content and saturation degree. Results indicate that soil resistivity increases with decreased moisture content and saturation degree for a given diesel content, which can be expressed using a series of power functions. The soil resistivity increases linearly with increased diesel content for a given moisture content. A new characteristic parameter, volume moisture content, is developed to better understand the influence of water- diesel interaction on the soil resistivity. It is found that the soil resistivity increases linearly with an increase in the volume moisture content for a given saturation. Orthogonal analysis was performed to rank the importance of influence factors on the soil resistivity, indicating the following order: degree of saturation > water content > oil content.
    References | Related Articles | Metrics
    Flexural Performance of Steel Fiber Reinforced Self-Stressing Concrete Continuous Composite Beams
    WANG Bo-xin, WANG Guo-chao, WANG Qing
    2017, 38 (8):  1183-1188.  DOI: 10.12068/j.issn.1005-3026.2017.08.025
    Abstract ( 669 )   HTML   PDF (1748KB) ( 773 )  
    Owing to the excellent crack resistance of steel fiber reinforced self-stressing concrete (SFRSSC for short), the flexural performance and crack resistance of a two-span continuous composite beam with SFRSSC laminated layers were investigated. The experimental results show that the cracking load and the ultimate mid-span deflection of the test beams are increased greatly. Meanwhile, the cracks develop slowly around the support and the flexural behavior of continuous composite beam is improved obviously. Furthermore, a procedure to determine the crack load of SFRSSC continuous composite beams was established and a FEM simulation was given. The theoretical results are in good agreement with the test results and the numerical results, which indicates that the method can evaluate the crack resistance of continuous composite beams.
    References | Related Articles | Metrics
    Numerical Analysis and Field Measurement of Force on Diaphragm Walls in Adjacent Deep Excavations
    CHEN Jiang, YANG Jun-sheng, ZHANG Xue-min, OU Xue-feng
    2017, 38 (8):  1189-1194.  DOI: 10.12068/j.issn.1005-3026.2017.08.026
    Abstract ( 630 )   HTML   PDF (1176KB) ( 716 )  
    This paper focused on the study of shared diaphragm walls in the foundation pits of Chegongmiao station of Shenzhen subway line 11. During the study, typical tested section was selected, and concrete strain meters were embedded so as to carry out internal force test for diaphragm walls. Stability of the station structure was evaluated. The ABAQUS software was used to analyze it, and shared diaphragm walls were affected greatly by construction of adjacent excavation, and internal forces varied significantly, while other diaphragm walls were affected slightly by construction of adjacent excavation, and the effect could be ignored. In the end, it provides a reference for the construction of subway station in Shenzhen area.
    References | Related Articles | Metrics
    Representative Values of Temperature Action of the Box Girder-Track System Based on the Higher-Order Moment Method
    ZHU Jun-pu , DAI Gong-lian , SU Hai-ting , LIANG Jin-bao
    2017, 38 (8):  1195-1200.  DOI: 10.12068/j.issn.1005-3026.2017.08.027
    Abstract ( 542 )   HTML   PDF (779KB) ( 737 )  
    A structure temperature statistical method was proposed based on the higher-order moment method, which can avoid the uncertainty of the traditional fitting curve method to seeking a distribution as well as can reach a high computational efficiency and accuracy. Based on the long-term monitoring data of a high speed railway bridge in the east China area, by taking box girder and track as an integrated system, the representative values of temperature and its difference in vertical and horizontal direction were calculated. The temperature distribution nephogram and the temperature-difference distribution rules were analyzed. The covering effect of track on the temperature of the box girder surface was studied. Results show that the annual temperature sample of the girder-track system has a middle variability. The distribution is relatively stable with a high temperature standard values of 35.4℃ and 38.15℃ respectively. The largest vertical temperature gradients are 10.33℃ and 12.93℃ respectively. The vertical effective thermal conductivity length of the concrete is approximate 60cm, and the covering effect of the track on the box-girder surface temperature is 4.4℃ declined.
    References | Related Articles | Metrics
    Testing Technology of Under-Anchorage Effective Prestress of Steel Strand in Construction Period
    ZHANG Feng, GAO Lei, XU Xiang-feng, CAO Yuan
    2017, 38 (8):  1201-1205.  DOI: 10.12068/j.issn.1005-3026.2017.08.028
    Abstract ( 813 )   HTML   PDF (658KB) ( 796 )  
    To accurately detect under-anchorage effective prestress, a test system for prestressed steel strand was developed and its working mechanism was revealed based on the equivalent stiffness theory. A specific criterion of tension for two kinds of situations was given and the tension-elongation characteristic curve was explained. Results show that tension-elongation curve can be divided into inelastic deformation eliminating section, elastic deformation of the reverse stretching section and co-work of both reverse stretching section and anchorage section. Specific tension criterion can be given according to whether there exists an inflection point in the tension-elongation curve, which can be used for detecting under-anchorage effective prestress. The error between actual working tension and the tested tension is less than 3%. It is suggested that the prestress loss should be considered in the evaluation standard of under-anchorage effective prestress.
    References | Related Articles | Metrics
    Management Science
    Relationship Between Manager Characteristics and Work Performance in the Service Industry
    TAN Guo-wei, MA Qin-hai, SUN Qi
    2017, 38 (8):  1206-1210.  DOI: 10.12068/j.issn.1005-3026.2017.08.029
    Abstract ( 599 )   HTML   PDF (368KB) ( 784 )  
    The manager characteristics in the service industry were extracted by applying the behavioral event interview method. A questionnaire on manager characteristics in the service industry was designed, and the model of manager characteristics in the service industry was established based on the results of the questionnaire. Accordingly, an 11-dimensional manager characteristics model was proposed, including decision ability, learning ability, affective intelligence, self-control ability, innovation ability, achievement motivation, social ability, communication ability, leadership, application ability and caring ability. Moreover, an evaluation model on work performance in the service industry was put forward, including task performance and contextual performance. Finally, the relationship model between manager characteristics and work performance was built using the partial least square regression.
    References | Related Articles | Metrics
    Selection Model of Eco-city Evaluation Indexes and Its Application
    YI Ping-tao, LI Xue, ZHOU Ying, LI Wei-wei
    2017, 38 (8):  1211-1216.  DOI: 10.12068/j.issn.1005-3026.2017.08.030
    Abstract ( 667 )   HTML   PDF (395KB) ( 850 )  
    Based on the problems emerging in the process of urban development, the connotations of eco-city were explored and a new index system in combination with the DPSIR model was established from such perspectives as economic level, environmental problems, social issues, urban current status and government control. Faced with a large number of evaluation indexes, a new method of index selection was proposed by taking multiple factors such as importance, correlation and discrimination. Specifically, the Delphi method, the improved entropy method and the Person correlation theory were used to select the core indexes, and the rationality of index construction were confirmed by the measurement criterion,i.e.,index information contribution rate. Finally, eight cities in Liaoning Province were taken as the research objects in order to verify the validity of the proposed method.
    References | Related Articles | Metrics