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    28 April 2020, Volume 46 Issue 2 Previous Issue    Next Issue
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    Materials Science and Engineering
    Effect of aging on microstructure and properties of deformed Cu-Zr-Si alloy
    GUO Ting-biao, WU Yi-bo, WEI Shi-ru, WANG Bing, MA Di, JIA Zhi
    2020, 46 (2):  1-6. 
    Abstract ( 278 )   PDF (23665KB) ( 326 )   Save
    Equal-channel angular pressing (ECAP) technique was employed to perform single-pass deformation of Cu-0.16Zr-0.04Si alloy at room temperature and liquid-nitrogen low temperature, and then the alloy was aged at 450 ℃ for 4 h. The effect of aging on the microstructure of the alloy were investigated by scanning electron microscopy (SEM) and X-ray energy spectroscopy (EDS) and the alteration of mechanical properties and electrical conductivity of the alloy were analyzed. The result showed that after the alloy being deformed and aged, an ununiformity distributed rod-like or granular precipitated phase would appear at the grain boundary and a dispersively distributed fine point-like precipitated phase would appear in the matrix. The tensile strength and electrical conductivity of the alloy would be improved synchronously after deformation and aging treatment. With the aging time prolonged, the fracture toughness of the alloy would gradually deteriorate.
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    Influence of Zr atom fraction on corrosion resistance behavior of Ti-based amorphous composite
    ZHAO Yan-chun, JIANG Jian-long, MAO Rui-peng, SUN Hao, KOU Sheng-zhong
    2020, 46 (2):  7-12. 
    Abstract ( 215 )   PDF (9376KB) ( 96 )   Save
    Samples of (Ti0.5Ni0.5-xZrx)80Cu20 bulk metallic glass with x=0, 0.02, 0.04 and 0.06 were prepared with method of magneto-suspension melting plus absorptive casting in water-cooling crucible and negative-pressure copper mold. The phase-composition of the alloy samples was analyzed, and the polarization curves of the samples in artificial sea-water and simulated human PBS solution were tested. The morphology of electrochemical corrosion was observed and the electrochemical corrosion productwas precipitated and characterized. The result show that the microstructure of the alloy would be composed of amorphous matrix plus crystal phase B2-Ti (Ni, Cu) austenite phase and B19’-Ti (Ni, Cu) martensite phase. It would be gotten that compared with the crystalline TC4 alloy, several alloys would have better corrosion resistance in both artificial sea-water solution and PBS solution, and the corrosion resistance of the alloy would increase with the Zr content. When x=0.06, the alloy would exhibit the most excellent corrosion resistance, its self-corrosion potential was so high as -0.218 V, thermodynamic tendency was so feeble that hard to be corroded, self-corrosion current density was lower as 0.912 μA·cm-2, polarization resistance was large as 3.4 MΩ·cm2 and corrosion kinetic rate was low, and the alloy would have more excellent corrosion resistance in PBS solution and would be no obvious dotted corrosion pit to be found in the corrosion morphology.
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    Electrochemical corrosion behavior of micro-arc oxide film on AM60B magnesium alloy
    MA Ying, LIU Jin-zhong, AN Ling-yun, WANG Xing-ping, SUN Le, WANG Sheng
    2020, 46 (2):  13-18. 
    Abstract ( 249 )   PDF (7736KB) ( 190 )   Save
    AM60B magnesium alloy was treated by means of micro-arc oxidation (MAO) in silicate system. The corrosion behavior of the film coated in 3.5 % NaCl medium was studied by using cyclic voltammetry (CV), Tafel polarization curve and electrochemical impedance spectroscopy (EIS). The result showed that the corrosion resistance of the film on AM60B magnesium alloy would be significantly improved after MAO treatment. Compared with the film coated under low voltage, the micro-pore size in the film coated under high voltage would be slightly larger, but the number of micropores would significantly reduce, and the thickness of the film would obviously increase, so that making the film exhibit extremely strong resistance and excellent corrosion resistance in entire corrosion process. Even at the end of the test, the corrosive medium would still not penetrate the coating into the interface between the film and the substrate. Nevertheless, when the film was coated under low voltage, the corrosive medium would already penetrate the film to erode the substrate.
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    Effect of the feeding rates on the performance of RF plasma spheroidized powders
    YIN Yan, ZHAO Chao, PAN Cun-liang, ZHANG Rui-hua
    2020, 46 (2):  19-23. 
    Abstract ( 269 )   PDF (8745KB) ( 243 )   Save
    The property modification of GH4169 alloy powder particles discarded by 3D laser printing was carried out by RF plasma spheroidization technology. In this work, the influence of powder feeding rate on the effect of powder spheroidization was studied, and the difference of microstructure along with properties before and after powder spheroidization was analyzed either. Our research results indicated that the smaller the powder feeding rate is, the more heat the unit mass powder absorbs, leading to its vaporization. The more “adsorbed small particle powder” on the particle surface, the smaller the spherical powder yield. On the other hand, the higher the powder feeding rate is, the heat absorbed by the powder per unit mass is not enough to melt all the powder particles. Some defects such as satellite ball and coated powder appear, and the spheroidization rate of the powder decreases as a result. The microstructure of granulated powder particles consists mainly of cellular crystals, columnar crystals and crystallites. By adopting appropriate parameters of plasma spheroidization, the obtained powder particles have excellent sphericity, improved fluidity and looseness ratio significantly, increased average particle size and more uniform particle size distribution.
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    Effect of Sb2O3 with different particle sizes on flame-retardancy of PBT
    XU Jian-lin, MA Bing-xue, KANG Cheng-hu, MA Ji-qiangXU Cheng-cheng, CHEN Zhou
    2020, 46 (2):  24-28. 
    Abstract ( 274 )   PDF (7848KB) ( 193 )   Save
    In order to improve the flame retardant performance of polybutylenes terephthalate (PBT), an Sb2O3/BPS-PBT composite was prepared by means of mechanical ball milling first and then melting injection molding method. The effect of Sb2O3 particle size on flame retardancy of PBT-matrix composite was studied and the flame retardant mechanism of the PBT-matrix composite was analyzed. The result showed that Sb2O3 would make the initial decomposition temperature of PBT advanced and the thermal decomposition rate slowed down; Adding Sb2O3 with the same mass fraction, the efficiency of nano-Sb2O3 in the case of gas-phase flame retardance and the catalytic effect of promoting carbon residue formation would be superior to micro-Sb2O3; When the mass fraction of bromide of polystyrene (BPS) and nano-Sb2O3 were 10% and 5%, respectively, the LOI of the composite would be 28.3% and theUL94 would reach level V-0.
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    Effects of degree of fluorination and uniaxial stress on structural stability and energy band of fluorinated graphene
    LIANG Ze-fen, MA Sheng-ling, XUE Hong-tao, TANG Fu-ling WANG Lan-xi, FAN Ding
    2020, 46 (2):  29-34. 
    Abstract ( 245 )   PDF (8901KB) ( 99 )   Save
    The first-principles approach based on density functional theory (DFT) is used to computationally investigate four kinds of(NCNF=1∶1)configurations (Chair, Zigzag, Boat, Armchair). The results coming out from computations show that the fluorinated graphene configuration in the form of Chair maintains the most stable. The effects of fluoridation plus uniaxial stress on the structural stability and energy band of fluorine fossils were also studied. Resulting research findings indicate: the higher fluoridation, the more stable fluorine fossils, while double fluorinated graphene seems more stable than single side fluorination. When compressive (tensile) strain is applied to the constructed perfluoroene graphene system along the X direction, the undulating peak of the graphene system decreases with the increase of the single-axis strain. The conduction band bottom and the valence band top both move slightly respectively, and the band gap decreases gradually. The band gap becomes reduced faster under axial compressive stress in this case.
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    Mechanical Engineering and Power Engineering
    Structural design and modeling simulation of standing-to-lying changing angle swing head of five-faced body machining center
    YAN Chang-feng, LI Hui-long, LI Qiang, GAO Gang-gang, GOU Wei-dong
    2020, 46 (2):  35-40. 
    Abstract ( 429 )   PDF (4323KB) ( 901 )   Save
    Aimed at the problem of five-face body machining center that the transmission chain was excessive long and unfavorable for improving the machining accuracy in the case of standing-to-lying change, a novel project of angle swing head for standing-to-lying change was proposed. In this project, the measure of transmission was dropped, where the angle swing head employed individual set of power supply for cutting power transmission and also for standing-to-lying change, and a simple set of power supply was used either for cutting power transmission or for standing-to-lying change, so that the transmission chain was contracted extremely. A three-dimensional mechanical structure model of the assembly of angle swing head, spindle and its key components was established with software SolidWorks. The software Romax was used to conduct the modelling of the driven system of the angle swing head, and the reliability of the driven system was analyzed under different working conditions. The result showed that under given operation conditions the design of the drive system would be reasonable and the operational reliability would meet the design requirements. To ensure rigidity and stability of the standing-to-lying change spindle of angle swing head, the modality analysis was carried out by using the ABAQUS. The result showed that the spindle would not resonate within the range of rated operating speed.
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    Characteristics analysis of stator curve of double-valve plate radial piston pump
    YANG Guo-lai, DONG Ji-cheng, CAO Wen-bin, CHEN Chen, GAO Wen-tao
    2020, 46 (2):  41-47. 
    Abstract ( 271 )   PDF (1511KB) ( 580 )   Save
    Aimed at the problem of vibration and shock in double-valve plate radial piston pump, the mathematic models of seven kind of stator curve are established for double-valve plate radial piston pump, and the motion equation of roller center, which follows the argument-revised equally accelerated motion regularity and uniformly varied accelerated motion regularity, is revised and by means of Matlab simulation, several stator curves with different periodic angle are drawn. The characteristic parameters of the plunger pair such as degree velocity, degree acceleration, pressure angle, instantaneous torque and instantaneous flow are comprehensively compared for different stator curves and it is found by analysis that the angle velocity and acceleration curve of eighth-power stator curve will vary continuously and smoothly, the pressure angle will be moderate, the change of instantaneous torque and flow will be the smallest and the maximum of the instantaneous torque will be minimized to the full extent.
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    Energy performance prediction of single-stage single-suction centrifugal pump under multiple operating conditions
    YANG Jun-hu, JI Ya-ya, LIN Bin, MA Qi-hang, LUO Yu-tong, LI Zhi-fan
    2020, 46 (2):  48-54. 
    Abstract ( 323 )   PDF (2022KB) ( 730 )   Save
    In order to predict accurately the energy performance of centrifugal pumps under different working conditions, their hydraulic loss models are established based on the existing theoretical and empirical formulas at home and abroad. The linear regression method is used to find out the functional relationship between the impeller inlet angle of attack and the impact loss, so that the impact loss formula is revised. Thereby, to verify the accuracy of this model in predicting the energy performance of centrifugal pumps under different working conditions, a centrifugal pump with a specific speed of 92.8 is selected to calculate the head, efficiency and shaft power at nine operating points, and the result is compared with that of experiment and analyzed. The results show that the prediction results of the head will be basically consistent with the test results. The error between the predicted head and the test head at nine operating points will be less than 5%. This shows that the hydraulic loss equation can be used to predict the energy performance of centrifugal pumps well under different working conditions.
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    Design exploration of blade number of impeller and guide vane of sodium pump in secondary circuit of fast reactor
    YANG Cong-xin, HOU Kai-wen, YU Hong-chang, NIU Hong-jun
    2020, 46 (2):  55-61. 
    Abstract ( 322 )   PDF (6220KB) ( 347 )   Save
    The sodium pump in secondary circuit of fast reactor is one ofkey equipment of the most advanced fourth-generation nuclear power in the world at present. It is very important to improve pump efficiency under the conditions of safe operation. Hydraulic design of the pump was carried out bycombining one-dimensional design method with computional fluid dynamics(CFD) based on its performance requirements and dimensional limitation and the matching rules of the blade number of the pump impeller and guide vane were discussed. The results show that the maximum influences of blade number of guide vane on its efficiency and head are 4.01% and 9.75% of their designing values, respectively, when the blade number of the impeller is kept constant. The optimal matching ratio of the blade number of impeller and guide vane for each other under designing condition is 5∶8, or 6∶9, or 7∶11, namely, the pump hydraulic performance reaches its optimal value when the matching ratio is about 1∶1.5. Nevertheless, the matching ratio of blade number of impeller and guide vane is at 6∶11, the sodium pump gets the best hydraulic performance.
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    Effect of impeller exit width on performance and pressure fluctuation of centrifugal pump
    ZHAO Wei-guo, ZHAI Li-jing, XIAN Li-xia, MA Liang-liang
    2020, 46 (2):  62-68. 
    Abstract ( 843 )   PDF (6499KB) ( 949 )   Save
    Taking a single-stage end-suction centrifugal pump as study object and assuring the inlet and outlet setting angle and diameter and as well as other parameters unchanged, five sets of pump models with different outlet width of impeller were designed respectively, their numerical simulation was carried out one after another and the influence of impeller outlet width on the performance and pressure fluctuation was analyzed. It was shown by the study result that with the increase of impeller outlet width, the lift and shaft power would increase to different extent, the efficiency curve would be hump shaped, indicating that there would be an optimum impeller outlet width to make the flow loss minimum; increasing the width of the impeller outlet, flow separation phenomenon in flow channel would be enhanced, blocking phenomenon there would decrease hydraulic loss would decrease thereby, indicating that an appropriate width of impeller outlet would be effective for reducing the energy loss of centrifugal pump. With progressive decrease of impeller outlet width, the shaft frequency peak would change obviously, assuming progressive increase trend, indicating that an excessive narrow impeller outlet width would easily lead to flow blocking in flow passage and hinder the development of the flow mode, At the same time, the impeller outlet width would also have a greater effect on pressure pulsation in centrifugal pump.
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    Chemical Industry and Light Industry
    Comparative test of effect of heating with suspended kang and landed kang on indoor environment
    LI Jin-ping, GUO Jing-tao, WANG Chun-long, LI Hong-bo
    2020, 46 (2):  69-74. 
    Abstract ( 329 )   PDF (7270KB) ( 150 )   Save
    Suspended kang and landed kang are two types of heating device used popularly in northern China in winter currently. Their structure and sealing performance have an obvious influence on the indoor thermal environment and indoor air quality. Referring to relevant National Standards, a continuous comparative experimental investigation of indoor thermal environment and air quality of heating with those two kinds of kangs was conducted in county Lintao, Gansu. The result showed that the indoor daily mean temperature of heating with suspended kang would be 12.6 ℃, being 1.8 ℃ higher than that of heating with landed kang (10.8 ℃). It was found by employing PMV-PPD index evaluation that the comprehensive evaluation grade of indoor thermal comfortableness would be class-Ⅱ for the suspended kang, and that of landed kang would be class-Ⅲ. Indoor air quality PM2.5, PM10 and CO index of heating with suspended kang would be superior to that of landed kang, the indoor primary pollutant of heating with both types of kang would be PM10. The indoor air quality grade of heating with suspended kang would be pollution, the indoor air quality grade of heating with landed kang would be heavy pollution.
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    Microwave-aided synthesis of a novel thiazolium salt and its catalytic function for benzoin condensation
    ZHANG Zhen-ming, ZHAN Yao, CHEN Da, LI Shu’an, PENG Xiao-han, XIA Tian
    2020, 46 (2):  75-79. 
    Abstract ( 412 )   PDF (1250KB) ( 635 )   Save
    The 4-methyl-5-hydroxyethyl thiazole and p-cyanobenzyl cloride were taken as raw materials to synthesize a novel thiazolium salt of 3-(p-cyanobenzyl)-4-methyl-5-(2-hydroxyethyl)-1, 3-thiazolium chloride with microwave technique and then the VB1 was substituted by this thiazolium salt as catalyst of benzoin condensation reaction. Its catalytic performance was checked and it was found that when it was used to catalyze benzaldehyde, the benzoin would be obtained, with yield-rate of 74.5%; when it was used to catalyze furaldehyde, the furoin would be obtained, having yield-rate of 76.1%. This thiazolium salt would be not only without toxicity but also could be recovered and reused. The influence of a mount of substance putting ratio, reaction duration, reaction temperature, and power of microwave reactor on the yield-rate of this thiazolium salt was investigated. The purity of the resultant was determined with HPLC and the property of thiazolium salt and structure of benzoin were characterized by means of analysis of element composition and melting-point, IR, and LC-MS.
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    Automation Technique and Computer Technology
    Shielding characteristics of ferritesin WCR-MPT
    WANG Hui-zhong, XUE Chao, ZHUANG Ya-jie
    2020, 46 (2):  80-85. 
    Abstract ( 307 )   PDF (4401KB) ( 514 )   Save
    Aimed at the lack of definite guidance method for design and selection of ferrite shielding materials during the process of magnetically coupled resonant wireless power transfer and the direct influence of the addition of ferrite shielding materials on the transmission performance of the system, mathematic modelling is carried out for the foregoing power transmission based on circuit theory and Maxwell equations, a magnetically coupled resonant wireless power transfer device with ferrite shielding material is built on Maxwell simulation platform, and the influence of addition of ferrite shielding materials on the mutual inductance and coupling coefficient between coils, the resistance and quality factor of the coil itself is analyzed. Finally, a hardware circuit is built for carrying out the test and explore the influence of ferrite shielding materials with different coverage area and shape and at different distance on system transmission efficiency. The result shows that the system transmission efficiency induction can be effectively improved only under the condition of full shielding of receiving end and close leaning on the receiving coil.
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    Fault detection of batch process based on improved NPE algorithm
    ZHAO Xiao-qiang, ZHANG He-hui
    2020, 46 (2):  86-91. 
    Abstract ( 272 )   PDF (2935KB) ( 441 )   Save
    Because batch process has the feature of multi-modality and data Gaussian and non-Gaussian mixing, so that the accuracy of fault detection often is not high and the monitoring performance is affected. Therefore, an improved NPE algorithm is proposed in this paper. Firstly, in this algorithm, the local k-nearest neighbor set of each sample is found, the local neighbors are normalised by seeking their mean and standard deviation, and, therefore, a single mode is generated and the normalized data is made to obey approximately the multivariate Gaussian distribution. Then, neighborhood preserving embedding (NPE) algorithm is corporated to perform dimensional reduction for new data, the local information between the neighbors of data sample and sample information are fully exploited, and the local structural information of data is extracted. Finally, support vector data description (SVDD) is used to construct monitoring statistics Ω and control limits for fault detection, so that a faster and better result than standard statistic SPE detection is realized. By means of test on penicillin fers montation simulation plat form and compared with the two types of faults of the SPE and Ω statistics of NPE, the effectiveness of the proposed LNSNPE-SVDD algorithm is verified.
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    Anti-sway design of overhead crane based on model predictive control
    TANG Wei-qiang, HUANG Xiao-li, LONG Wen-kun, SUN Li-juan
    2020, 46 (2):  92-96. 
    Abstract ( 632 )   PDF (1787KB) ( 774 )   Save
    Aimed at the sway problem of lifted weight in the working process of overhead crane, an electronic anti-swing design method is proposed based on predictive control strategy. Firstly, dynamic analysis is carried out for the overhead crane, and a control-oriented mathematical model is established by using Lagrange equation, Secondly, according to the historical information of the object and the future input, the future output is predicted and a control rule is obtained by optimizing the performance function combined with prediction error compensation. Finally, it is shown by simulation result that the designed anti-sway system can be used to realize rapid positioning of the trolley and effective restriction of the swing angle of lifted weight. Compared with an optimal anti-sway control, the system overshoot and swing angle amplitude will be greatly reduced, manifesting the superiority of this anti-sway method; When a parameter perturbation or measurement noise is added onto this system, the anti-sway system can still achieve the control purpose very well, showing that this anti-swing method has a better robustness.
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    Application of embedded-type system in anti-sway control of suspensory device of crane
    SUN Li-juan, TANG Wei-qiang, HUANG Xiao-li, LONG Wen-kun
    2020, 46 (2):  97-102. 
    Abstract ( 342 )   PDF (1571KB) ( 680 )   Save
    Aimed at the problems of time delay and laborsome work of programming of PLC to implement fuzzy PID control algorithm in anti-sway control system of suspensory device of crane, a design idea of applying embedded-type system to control the anti-sway system of crane is proposed. The system adopts host-slave control mode, in which the embedded-type processor is set to the slave working mode and the PLC is set to the host working mode; the slave is responsible for the sampling of the crane suspensory device parameters and the running of fuzzy PID control algorithm. According to the calculation result of slave operation, the host is responsible for control the speed and direction of the crane trolley motor. Through the coordinated control of the host and slave operation, the purpose of anti-swaying of crane suspensory device can be realized. RS485 is a serial communication interface that ensures the reliable communication of the data between the host and the slave. The fuzzy PID anti-sway control algorithm is run on the embedded-type processor computing platform with C-programming. The program is simple, and the processor performs instructions of reading and writing operations in short period. This design method improves the ability of the system to process data and control efficiency of the system. The control mode with embedded-type processor as the host and the PLC as the slave increases the flexibility of the system structure. Meanwhile, the system combined with the fuzzy PID algorithm has strong robustness.
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    Robust reversible data hiding method forencrypted color images
    ZHANG Qiu-yu, FENG Yu-chun
    2020, 46 (2):  103-110. 
    Abstract ( 221 )   PDF (11578KB) ( 59 )   Save
    In order to improve the imperceptibility, robustness and embedding capacity of available reversible data hiding (RDH) in encrypted color images, a high capacity reversible data hiding method forencrypted color images was proposed. At its transmission end, firstly the color image was encrypted by logistic chaotic mapping encryption algorithm and separated into RGB three color channels, and the three channels were divided into blocks and processed by two-dimensional discrete cosine transform (2D-DCT). Then, its low-frequency region with better robustness was selected to embed secret information and its anti-attack performance was improved. Finally, pixel complementary method was adopted to embed large-capacity secret information. At the receiving end, the encrypted image was decrypted firstly and then the secret information was extracted and the original image was recovered by means of inverse process of information embedment. Experimental result showed that compared with the hiding methods available, the proposed method would have much better performance in connection with image quality, embedding capacity, robustness and encryption; and the embedding capacity could be adaptively selected. When the capacity reached to 1.15 bpp, the average value of peak signal-to-noise ratio would amount to 39.39 dB.
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    Importance identification method of complex network nodes based on betweenness and degree entropy
    LU Peng-li, GUO Xu-dong, DONG Men, CAO Le
    2020, 46 (2):  111-115. 
    Abstract ( 437 )   PDF (3156KB) ( 719 )   Save
    Existent complex networks will usually be subject to random attacks and deliberate attacks, resulting in reduced reliability of complex network topologies. In order to solve the above-mentione problems, a new attack strategy is proposed based on graph entropy and incorporated with the betweenness centrality of nodes and the degree centrality of all their neighbor nodes, namely the betweenness and degree entropy (BE), which is used to identify important nodes in the network and protect them. Experimentally, the efficiency of attack strategies of three standard network models and three real networks is evaluated under condition of static attacks and dynamic attacks. By means of comparison, it is found that the betweenness and degree entropy will have higher attack efficiency than the traditional attack strategy.
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    Architectural Sciences
    Research advance on seismic performance of bridges in permafrost regions
    ZHANG Xi-yin, CHEN Xing-chong, GAO Jian-qiang
    2020, 46 (2):  116-120. 
    Abstract ( 350 )   PDF (1103KB) ( 538 )   Save
    This study summarizes the domestic research status of bridge seismic resistance in permafrost area from three aspects: effect of permafrost site, effect of permafrost on bridge seismic response, interaction between permafrost and bridge structure. Results show that frozen soils have significant effect on response within the seismic site in permafrost regions. Existing seismic design of bridges is performed without taking the response within the permafrost site into account, and there are no provisions in current seismic codes. Larger numbers of numerical studies show that both seasonally frozen soil and permafrost have significantly effects on seismic responses of bridges in cold regions. However, the present researches on energy dissipation mechanism and failure characteristics of bridge structure-frozen soil system in permafrost regions under earthquakes are still insufficiently clear so far. For the bridges with pile foundation widely used in permafrost regions, the pile-frozen soil interaction mechanism becomes more complicated due to the frozen soils, therefore, the existing predictive model of pile-frozen soil interaction should be improved. Without the improvement, the influence of the hydrothermal effect caused by frozen soils (changes of the hydrothermal properties such as temperature and water content may lead to the change of mechanical properties of the frozen soils), will not been fully taken into account in seismic analyses of bridges. All of above problems should be the focus of seismic research of bridges in permafrost area in the future.
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    Seismic reduction-isolation effect of hybrid passive control system in case of different frequency-domain ground motion with
    WU Qiao-yun, HE Wan-cheng, ZHU Hong-ping
    2020, 46 (2):  121-126. 
    Abstract ( 233 )   PDF (6342KB) ( 311 )   Save
    Taking the high-storey framework structure as object, a new type hybrid passive control system is proposed based on segmental seismic isolation combined with energy dissipation of inter-connected adjacent buildings as dampers, which can effectively cope with wide-range ground motion and has higher robustness and redundancy. Through numerical simulations of an identical high-rise building structure respectively with non-isolated form, segmental seismic isolation form and hybrid passive control form, the effect of seismic reduction and isolation of the segmental seismic isolation system and hybrid passive control system is investigated under the action of short-period wave, sliding effect included impulse wave and long-period wave. It is shown by the investigation that the control effect of segmental seismic isolation system will be better under the action of short-period wave, but its control effect will not so good under the action of impulse wave and long-period wave due to the greater displacement of the base seismic isolation storey and intermediate seismic isolation storey and there will be a possibility that this displacement is larger than the limit value of the support displacement. Nevertheless, the hybrid passive control system will be able to reduce effectively the displacement of the seismic isolation storey and improve obviously the seismic reduction and isolation effect of the structure. And the hybrid passive control system will have better seismic reduction and isolation effect when the intermediate isolation storey is set in the middle of the structure.
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    Shaking table test for anti-seismic performance of subway station in loess area with two floors aboveground
    HAN Jian-ping, NIE Wen-rui
    2020, 46 (2):  127-132. 
    Abstract ( 232 )   PDF (6965KB) ( 213 )   Save
    In order to investigate the anti-seismic performance of subway station with 2 aboveground storeys and 1 underground storey in the loess area, the shake table test of the both aboveground and underground structure and the surrounding soil layer is carried out. Based on the brief introduction of model design and loading condition, the boundary effect of model soil box, dynamic response of model soil and model structure, and the soil-structure interaction are emphatically analyzed and discussed according to the data recorded by sensors in the tests. Test results show that the aboveground part of the model subway station with 2 aboveground storeys and 1 underground storey in the loess area will be subjected to the larger influence of peak ground acceleration of input earthquake. The final failure pattern of the aboveground part will be the overall sidesway collapse. The underground part of the subway station will be subjected to the larger influence of the soil around the underground structure. There will be no obvious damage in the underground structure when the displacement of surrounding soil is small. The interface part between aboveground and underground structure will be subjected to the worst damage. The model subway station structure will have little influence on the dynamic response of surrounding soil, and the influence will decrease with the increase of the peak ground acceleration of input earthquake.
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    Discussion on calculation method of active earth pressure for limited soils
    ZHU Yan-peng, WEI Peng-yun, MA Xiao-rui, LI Geng, LIU Xin
    2020, 46 (2):  133-137. 
    Abstract ( 455 )   PDF (2711KB) ( 927 )   Save
    Based on the sliding plane hypothesis of Coulomb’s earth pressure theory and the limit equilibrium theory, a modified formulation for active earth pressure is derived according to the relationship between limited soils’ width b0 (a distance between a supporting structure and an existing building) and triangular sliding wedge’s width b. Assumptions of formulation are that the limited soil is in horizontal and the support structure is in vertical. In addition, the formulation takes into account not only the adhesion between the supporting structure and soils but also the cohesion between the static soils and sliding soils. It is then analyzed that the impact of the external friction angle as well as the adhesion between the supporting structure and soils on the sliding soil mass’ cracking angle (failure angle of sliding soils) and active earth pressure. A viewpointabout generalized active earth pressure coefficient is also put forward in this paper. All results gaining from our calculated examples show that the formulation becomes more effective in practices. Evidently, taking the impact of the external friction angle into account in the formulation will reduce cost indeed.
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    Analysis and calculation of bending performance of concrete-filled circular steel tubular component with encased profile steel
    SHI Yan-li, LI Xing-guo, WANG Feng
    2020, 46 (2):  138-144. 
    Abstract ( 243 )   PDF (5802KB) ( 439 )   Save
    Finite element software ABAQUS was used to establish a mechanical model of concrete-filled steel tubular component with encased profile steel subjected to the action of the bending. With the help of the rationality of experimental verification models available, based on checking the accuracy of those, the deflection regularity, stressing process, and failure mode of this kind of components under action of bending moment influence of component parameters such as material property, steel inclusion rate in profile steel, and its sectional form on the ultimate bearing capacity and flexural stiffness of the bent component was analyzed, also. Its evaluation was carried out by means of introduction of calculation formula of flexural bearing capacity of integral column in European Code, and its calculation result was compared with the results of experiment and finite element simulation available. Their agreement was fine enough, showing that that formula of composite columns in European Code can be used for the design of that category of component. The result of this investigation can provide certain reference for the design of the concrete-filled steel tubes with encased profile steel under bending load.
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    Shaking table test on 110 kV capacitor bank
    WANG Xiao-ning, SUN Yu-han, CHENG Yong-feng, LU Zhi-cheng
    2020, 46 (2):  145-149. 
    Abstract ( 346 )   PDF (3716KB) ( 353 )   Save
    Real 110 kV capacitor group equipment in an UHV substation was tested in this study on a simulated seismic vibration test bench. Through the white noise random excitation, dynamic characteristics of the real equipment is clearly defined, while the acceleration, strain and displacement parameters of key parts of the equipment in the case of earthquake are measured by standard time-history wave excitation, and consequently seismic responses of capacitor banks are determined. Our test results show that the first-order frequencies in two horizontal directions of the capacitor bank equipment are 2.27 Hz and 2.31 Hz respectively, so they are highly seismically vulnerable. When inputting a standard time-history wave form with a peak acceleration of 0.4g in the test, the maximum stress of insulator at root of the capacitor bank is 40.80 MPa, which is less than the stress to cause material failure. Test results also show that an amplification effect to seismic acceleration exists in each layer structure of the capacitor bank. Under the action of seismic, the pillar insulator of the equipment becomes a vulnerable part in earthquake. In this regard, the anti-seismic capability of the insulator can be strengthened by improving the strength of materials and the stiffness of concerned connections.
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    Scientific
    Pascal rhombus and Riordan array
    YANG Sheng-liang, GAO Yuan-yuan
    2020, 46 (2):  150-154. 
    Abstract ( 265 )   PDF (1375KB) ( 447 )   Save
    Riordan array representation of Pascal rhombus is obtained with 2-Motzkin paths and several generalized Pascal rhombus and their Riordan array representation are given out with weighted 2-Motzkin paths and 3-Motzkin paths.
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    Completely regular semigroups whose lattice of completely regular subsemigroups is semimodular
    TIAN Zhen-ji, HU Yun-hua, TAO Yu-hua
    2020, 46 (2):  155-157. 
    Abstract ( 250 )   PDF (1045KB) ( 348 )   Save
    Otain the necessary and sufficient condition that the subsystem lattice of a completely regular semigroup S is a semimodular lattice, that is, the subsystem lattice of S is a semimodular lattice if and only if S is the order sum of some UM-groups or left [right] groups whose maximal subgroups are UM-groups.
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    Upper bound of spectral radius of Hadamard product of nonnegative matrices
    ZHONG Qin
    2020, 46 (2):  158-160. 
    Abstract ( 258 )   PDF (1046KB) ( 383 )   Save
    Based on the Gerschgorin disc theorem and Brauer oval theorem, the upper bound of the spectral radius of Hadamard product of nonnegative matrices is given by applying the fact that the similar matrices have the same eigenvalues, the result obtained depends only on two entries of nonnegative matrices,so that they are easy to calculate. Numerical example shows that the newestimation formula will improve several existing resultsunder certain condition.
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    A unified variable selection approach forvarying coefficient models based modal regression
    XIA Ya-feng, JIA Xin-yi
    2020, 46 (2):  161-165. 
    Abstract ( 253 )   PDF (1087KB) ( 284 )   Save
    A unified variable selection invarying coefficient model with modal regressionis studied. B spline basis function is adopted to approximate the nonparametric part, and SCAD penalty function is established under modal regression. The proposed procedure using SCAD penalty function to select important variables simultaneously for the varying coefficient model can also identify the covariates with constant effects. Under certain conditions, the concoherence and sparseness of penalty estimation are proved. Finally, the effectiveness of the proposed variable selection method is evaluated by numerical simulation.
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    Evaluation and analysis of electronic structure and optical properties of Cu-Cd co-doped ZnO by means of primary principle
    LI Wei-Xue, XUE Xiao-feng, DAI Jian-feng, WANG Qing, SUO Zhong-qiang
    2020, 46 (2):  166-172. 
    Abstract ( 394 )   PDF (1887KB) ( 606 )   Save
    Based on the primary principle of density functional theory (DFT) system, five super-cell models of the pure ZnO, Cd doped ZnO, Cu doped ZnO, Cu-Cd co-doped ZnO, and Cu-2Cd co-doped ZnO, were optimized respectively for their geometric structure. The cell structure, energy band structure, state density, and their optical properties such as the imaginary component of dielectric function, absorption rate and reflectivity of each system were calculated and analyzed. The investigation result showed that the single doping of Cu or Cd could increase the carrier concentration of the ZnO and make the conductivity of ZnO improved. Never the less, in the case of Cu-Cd co-doping, the state of ZnO system would be more stable due to lower E. In connection with optical properties, the Cd-doping would make red shift of the edge of the ultraviolet region and the absorption would be slightly enhanced. When the ZnO was doped by Cu and Cu-Cd co-doped, the absorption coefficient of the system at the visible light and ultraviolet band would increase remarkably, making the photocatalytic activity of ZnO enhanced. When the characteristics single doping of ZnO with Cu and Cd was taken into consideration, the Cu-Cd co-doping of ZnO would make the semiconductor produce different transmittance if the doping concentration of Cd was controlled. So that the transparent devices with different efficiency could be propered by managing the doping of ZnO with different ratio of Cu-Cd.
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