Table of Content

28 February 2020, Volume 46 Issue 1    Next Issue

For Selected:

Download Citations EndNote Reference Manager ProCite BibTeX RefWorks

Toggle Thumbnails

Materials Science and Engineering

Select

Formation mechanism of core-shell structure in interface reaction layer of accumulative pack-rolled Al/Cu composite sheet CHEN Jian-hong, YU Yang-bo, ZHANG Xiao-bo 2020, 46 (1):  1-6.  Abstract ( 321 )   PDF (4790KB) ( 236 )   Save The Al/Cu composite sheet was fabricated by means of accumulative pack-roll (ARB) incorporated with multiple annealing treatment and the core-shell structure formation mechanism of Al/Cu interfacial reaction layer was emphatically investigated. The result showed that atomic diffusion of copper at Al/Cu interface during annealing would play a key role in the formation of Al/Cu interfacial reaction layer and the resultants would include intermetallic compounds Al2Cu, AlCu and Al4Cu9. The rolling deformation would make the reaction layer broken and distributed uniformly the matrix. The annealing treatment after rolling would lead to continuous formation of new interface reaction layer. Finally, after multiple pack-rolled pass and annealing treatment, the entire primary copper sheets would be transformed into axiolitic Al/Cu intermetallic compound particles with core-shell structure. The composite sheet after eight ARB passes would have highest ultimate tensile strength (UTS) of 176.8 MPa which would be 1.74 times of that of annealed 1060. The elongation of composite sheet without rolling would be better; this was basically due to that the aluminium layer would deform plastically and uniformly after Al/Cu interface delamination and the stress would slowly be released. References | Related Articles | Metrics

Select

Microstructure and performance of austenitic stainless steel with ionic permeation of N LAN Ye-feng, WANG Chuang-zao, HU Qiu-chen, HU Wei-wei, LI Qing-lin 2020, 46 (1):  7-12.  Abstract ( 302 )   PDF (5200KB) ( 224 )   Save The surface nitriding treatment of austenitic stainless steel ball valve is carried out with technique of glowing ion permeation of N, so that its surface structure is changed and surface wear resistance is improved. Three sets of temperature of 400, 440 and 480 ℃ are chosen for ion permeation of N respectively, and the time of permeation of N is set to be 12 h. Scanning electron microscope, optical microscope, X-ray diffractometer, Vickers microhardness tester and material surface comprehensive tester are used to test the surface morphology, cross-sectional morphology, microhardness and wear resistance of the N-modified layer. The result shows that the technique of ion permeation of N will be able to improve greatly the hardness and wear resistance of austenitic stainless steel, when the temperature of infiltration of N is 400 ℃, the N-modified layer will be the thinnest and the wear resistance will be the worst, the N-modified layer nitrided at 480 ℃ will be the thickest and its wear resistance — the best. References | Related Articles | Metrics

Select

Microstructure and performance of 316 austenitic stainless steel modified compositely by means of ion nitriding/CrN coating LI Qing-lin, ZHAO Shang, HU Qiu-chen, HU Wei-wei, LAN Ye-feng 2020, 46 (1):  13-19.  Abstract ( 364 )   PDF (5527KB) ( 279 )   Save 315 austenitic stainless steel was nitrided respectively at 400, 440, and 480 ℃ for 12 h, and then the physicalvapour deposition (PVD) and CrN film coating were carried out for the nitrided samples. The surface morphology, cross-section morphology, composition, microhardness, wear resistance, and corrosion resistance of the compositely modifying layer were tested by means of scanning electron microscope(SEM), optical microscope(OM) and X-ray diffractometer (XRD), Vickers hardness tester, material surface tester(HSR-2M), and electrochemical workstation. The result showed that the sample with ion nitriding at 400 ℃/CrN film coating would exhibit the best corrosion resistance and the worst wear resistance; the sample with ion nitriding at 480 ℃/CrN film coating would have the worst corrosion resistance and the best wear resistance, but its performance would better than that of a sample nitrided only at the same temperature. References | Related Articles | Metrics

Select

Technological process and performance of C/C composites densified with directional pulse airflow TG-CVI method JI Gen-shun, ZHAO Hao, JIA Jian-gang, ZHANG ShengLI Zhou, HAO Xiang-zhong 2020, 46 (1):  20-23.  Abstract ( 309 )   PDF (3519KB) ( 308 )   Save Taking the liquefied gas as carbon source precursor and the nitrogen as dilution gas, the general carbon felt with initial density of 0.14 g·cm－3 was densified by means of directional pulse airflow TG-CVI method. The densification process and density distribution of the C/C composites were studied under different experimental conditions. The microstructure, fracture morphology and flexural strength of the C/C composites were investigated by using polarized light microscopy, scanning electron microscopy and three-point bending method. The result showed that under condition of hot side temperature of 1 080 ℃ and pulse pressure of -3~0 kPa, the appearance density of the C/C composites after densified for 70 h would be 1.836 g·cm－3 with uniform density distribution. The microstructure would be a mixed structure of rough laminae(RL) with smooth laminae(SL).The fracture morphology of the samples would exhibit a progressive serrated distribution and the fibers would mainly be of pullout, showing a pseudoplastic fracture feature. In addition, the flexural strength would be 83.91 MPa. References | Related Articles | Metrics

Select

Simulation of dendrite free growth with phase-field model based on adaptive finite element method ZHU Chang-sheng, XU Sheng, LEI Peng, HAN Dan 2020, 46 (1):  24-31.  Abstract ( 604 )   PDF (8402KB) ( 130 )   Save Phase-field model is used to simulate the growth and morphological evolution of single intact equiaxed dendrite during its solidification in supercooled melt, the governing equations of the phase-field model are solved with adaptive finite element method, and the influence of physical parameters such as anisotropy and supercooling degree on the dendrite shape and growth under condition of larger computational domain and less interfacial layer thickness. The result shows that a competition will occur more intensively among the dendrites and their growth speed will be less when the supercooling degree is greater. However, the greater the anisotropy coefficient is, the stronger the dendrite growth tendency along a chosen direction will be, the faster the growth speed will be, the less the secondary dendrite spacing will be, and the more developed the lateral branch will be. Compared with the finite difference method (FDM), the adaptive finite element method (AFM) will reduce CPU time and storage space by one order of magnitude, and the larger the system size is, the more obvious the superiority of adaptive finite element method will be, which will facilitate the numeric simulation of greater dimensional and multi-field coupled phase field. By means of comparing to FDM and previous numerical simulation of crystal growth, the AFM is proved to be accurate, efficient and robust. References | Related Articles | Metrics

Select

Preparation of mesoporous rGO/TiO2hollow blocks with wide spectral response and photocatalytic performance related with them LI Cui-xia, SHI Xiao, SUN Hui-zhen, WANG Hui-kang, KANG Wei-chao 2020, 46 (1):  32-36.  Abstract ( 586 )   PDF (3545KB) ( 187 )   Save Mesoporous graphene oxide/TiO2 hollow bulk materials were synthesized in-situ with Sol-Gel method, by taking tetrabutyl titanate (TBT) and graphene oxide(GO) as raw materials, yeast as cavity template agent and citric acid as hydrolysis inhibitor and mesoporous template agent, and then the reduced graphene oxide/TiO2 (rGO/TiO2) bulk materials were obtained by means of ultraviolet radiation reduction. The samples were analyzed by means of various characterization means such as X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) and photoluminescence (PL) and the effect of yeast addition on degradation of tetracycline hydrochloride with rGO/TiO2 was studied. It was shown by experimental result that rGO/TiO2 would be mesoporous bulk materials with specific surface area of 50.66 m2/g and mesopores size of 4.3 nm in majority. The addition of yeast could effectively inhibit the recombination of the photo-generated electron-hole pair of catalyst, broaden the spectral response range and improve the photocatalytic performance. When the mass fraction of yeast was 5%, the catalytic performance of rGO/TiO2 would reach optimal level. Under visible light and ultraviolet light, the degradation rate of tetracycline hydrochloride would reach 84.97% and 96.96%, respectively. References | Related Articles | Metrics

Mechanical Engineering and Power Engineering

Select

Effect of kinematic pair clearance in scroll compressor on its tangential leakage gap ZHAO Man, YAN Peng-ju, ZHANG Qiang 2020, 46 (1):  37-43.  Abstract ( 253 )   PDF (3605KB) ( 253 )   Save Aimed at the problem of tangential leakage caused by kinematic pair clearance in scroll compressor with autorotation prevention mechanism of crankshaft pin and based on the parallel four-bar linkage model simplified with principle of mechanism, a mechanism with clearance in itself is converted into one with multiple components, multiple degrees of freedom and no gap, and analyzed there after, so that the influence of the clearance magnitude at anti-rotation crank pin on the autorotation angle and tangential leakage gap is determined with the help of Matlab numerical analysis software. The results show that the autorotation of the movable scroll disk will make the magnitude of leakage gap to change periodically with the rotation angle of the spindle and increase with the increase of the gap magnitude. The amount of change of the negative gap caused by the reverse rotation will make the wear of the movable and static scroll teeth increased. Therefore in the design stage of the compressor, the fitting tolerances should be strictly selected to reduce the adverse effect of the fitting clearance. References | Related Articles | Metrics

Select

Influences of inlet pressure of axial variable piston pump with cross porting disk on its swash plate moment WANG Jian-sen, LI Pei-yong, CHEN Bo, LI Li, YU Xin-hai 2020, 46 (1):  44-47.  Abstract ( 318 )   PDF (2215KB) ( 560 )   Save Taking axial variable piston pump with close-type swash plate and a mechanism of cross porting valve plate as example, a compressible flow distribution model of single displacement chamber and computation formula of swash plate moment are established, the variation curves of the area of flow passage section of oil suction and discharge of the valve plate and the precompression and preexpansion curve of single displacement chamber are found, and the variation regularity of swash plate moment is studied under different inlet pressure. It is found out by its result that with increase of inlet pressure, the average value of the component of moment of swash plate on three coordinate axes will decrease to some extent, where the ripple amplitude of the variable moment will decreases obviously.Therefore, properly increasing inlet pressure will be of advantage for decreasing variable moment of pump and weakening the mechanical vibration of swash plate. References | Related Articles | Metrics

Select

Constant frequency control of energy-storage power generation of wind turbine set with hydraulic energy regulation LIU Zeng-guang, YANG Guo-lai, WEI Lie-jiangZHAO Yu-yang, WANG Gang, YUE Da-ling 2020, 46 (1):  48-52.  Abstract ( 276 )   PDF (3197KB) ( 221 )   Save In order to eliminate the impact of wind fluctuation and intermittence on the smooth operation of power grid and realize the storage and regulation of the energy captured by wind wheel, on energy storage system is introduced into the closed-loop hydraulic system with pump-controlled motor in hydropower-type wind turbine set. A mathematical model of motor rotation driven independently by stored energy in energy storage system is established by using AMESim software in the case of still wind. Aimed at the composition and working principle of such a novel hydraulic system of hydropower-type wind turbine, a double closed-loop control strategy of motor with constant pressure difference plus constant speed is proposed to ensure that the power generator with always operate at synchronous speed in the case of power generation with stored energy. The response curves and changing trends of various system variables are compared and analyzed under condition of single closed-loop with constant pressure difference and double closed-loop control with constant pressure difference plus constant speed. The simulation result shows that the designed double closed-loop motor with constant speed control strategy will be able to stabilize the motor speed at 1 500 r/min, meeting the requirement of the output power frequency in case of independent power generation with stored energy. References | Related Articles | Metrics

Select

Effect of a kind of low-level jet on aerodynamic performance of horizontal-axis wind turbine YANG Cong-xin, LUO Song, LI Shou-tu, ZHANG Xu-yao 2020, 46 (1):  53-59.  Abstract ( 802 )   PDF (4922KB) ( 187 )   Save An 1.5 MW variable-pitch variable-speed three-blade horizontal-axiswind turbine was taken as research object. The similarities and differences of its aerodynamic performance were investigated under the three kinds of inflows and the effect of a typical low-level jet on its aerodynamic performance was studied emphatically. The results showed that the power and thrust of the rotor under low-level jet are larger than those under the uniform flow and the flow with wind shear. Surface pressure of the blade under low-level jetis generally larger than those of the other two inflows and there is a more noticeable flash-down zone of pressureon the section side of airfoil in the middle section due to jet attenuation.Under the condition of low-level jet, the normal and tangential force coefficients of the blade are generally larger than ones underthe other two inflows. The attack angles of each airfoil section under low-level jet are larger than ones unders shear flow by 0.05%~36.66%, the stall region on the blade surface are larger than those under other inflows, especially near blade root, the separation line moves close to the leading edge, and the separation vortexes on airfoil sections due to jet attenuation are more obvious. The study of effects of different kinds of low-level jets on aerodynamic performance of horizontal-axis wind turbine will be done in the future. References | Related Articles | Metrics

Select

Analysis of separation performance of novel integral hydrocyclone ZHANG Li, ZHANG Li-hua, XU Guang-yi, JIA Cun-qian, HAN Wen-jie 2020, 46 (1):  60-64.  Abstract ( 232 )   PDF (3277KB) ( 217 )   Save Aimed at the problem that there is no way for an ordinary cyclone to separate solid-phase particles with particle size about ten microns, a new structure of cyclone was presented for combined filtration separation with cyclone separation, the numerical simulation of the variation of velocity and pressure fields in the internal fluid and the stability of the air column there was carried out, and the filtration flux and separation efficiency of the filtering media were studied experimentally. It was found that the new integral filtering hydro-cyclone would have a more stable internal flow field, the internal velocity and pressure drop would be greater under condition of identical operation parameters and structure parameters. When the particle size was more than 5 μm, the separation efficiency of the hydrocyclone would be improved rapidly. The separation efficiency of solid particles of about 10 μm in diameter could reach 65% to 85% and the average separation efficiency of ordinary cyclone used in experiment would be below 60%. References | Related Articles | Metrics

Select

Experimental investigation of movement regularity of soil moisture during gravity-type underground hole irrigation FAN Yan-wei, BAI Gui-lin, ZHAO Wen-ju, WANG Zhi-jun, LIU Wen-guang 2020, 46 (1):  65-70.  Abstract ( 254 )   PDF (2966KB) ( 288 )   Save A system of gravity-type underground hole irrigation is designed, which has double functions of rainwater collection and irrigation. Through indoor soil box test, the movement regularity of soil moisture is investigated under condition of different pressure head, hole diameter on vertical tube, and its cover-up depth. The result shows that its infiltration process can be well described by Philip infiltration model and it is found that the decision coefficient will be greater than 0.99 and the cumulative infiltration will increase with the pressure head and hole diameter. The cover-up depth of vertical tube will have slight influence on it. The wetting front movement process can be well described with power function and the wetting front movement distance will assume such a variation regularity that vertical downward movement distant will greater than horizontal one and horizontal one will greater than vertical upward one. There will be a positive correlation between the wetting front movement distance in these three directions and the pressure head and hole diameter, however, will have slight influence on the cover-up depth of the vertical tube. The infiltration of soil moisture ofgravity-type underground hole irrigation will be mainly affected by the factors such as pressure head and hole diameter. References | Related Articles | Metrics

Chemical Industry and Light Industry

Select

Nitrogen doping of tubular hard carbon as conjugate microporous polymer and its lithium storage performance ZHANG Qing-tang, BAI Yong-bao, LI Meng 2020, 46 (1):  71-76.  Abstract ( 995 )   PDF (4508KB) ( 753 )   Save Conjugate microporous polymer (CMP) and nitrogen-contained conjugate microporous polymer (NCMP) were synthesized with chosen different monomers and the tubular hard carbon(THC) and N-doped tubular hard carbon(NTHC) were prepared by means of pyrolysis of those two kinds of CMP. The morphology and structure of the two tubular hard carbons were characterized with SEM, TEM and BET and it is shown that the materials of THC and NTHC have similar morphology and specific surface area. Further, The electrochemical property of THC and NTHC then compared with that of common carbon nanotube(CNT) was analyzed by constant current charge and discharge method and the result showed that the lithium storage performance of NTHC would be the best and it would have a high reversible lithium storage capacity of 541.2 mAh/g at 0.1 A/g and its specific capacity would retain around 458 mAh/g at 0.6 A/g after 500 cycles. References | Related Articles | Metrics

Select

CFD based performance prediction of blend-discharge integrated device and its experimental verification PAN Ling-yong, WU Gang, SONG Man-hua, LU Wen-qing, WANG Jun-qiao 2020, 46 (1):  77-82.  Abstract ( 206 )   PDF (3550KB) ( 215 )   Save Aimed at the working principle of the blend-discharge integrated device (BDID) and its internal flow field characteristics, the transient flow field and pressure characteristics were simulated under a specific rotation speed, the performance curves of axial power and suction/discharge pressure were calculated under different rotational speeds with CFD method, and an experimental device was designed and prepared to verify the result of the calculation. The result showed that the simulation result would be consistent basically with test result. This simulation model and the performance prediction method would have a effect of guidance to certain extent for optimization design of BDID and would be able to provide certain investigation basis for the future serialization design and engineering application of this device. References | Related Articles | Metrics

Automation Technique and Computer Technology

Select

Co-design method for fault-tolerant and attack-tolerance of NCS triggered by discrete event LI Wei, SHI Ya-hong 2020, 46 (1):  83-92.  Abstract ( 235 )   PDF (4811KB) ( 218 )   Save Aimed at the problem of actuator failure and network attack, the co-design problem of fault-tolerance and attack-tolerance of NCS was studied under DETCS. Firstly, the framework of NCS with fault-tolerant and attack-tolerant ability was given out under DETCS and based on it, a closed-loop NCS model with coexistent failure and attack was established, which integrated the trigger condition, actuator failure, and network attack into one uniform framework. Secondly, by means of constructing Lyapunov-Krasovskii functional and utilizing comprehensively the time-delay system theory, improved Wirtinger’s inequality and reciprocal convex combination lemma, a completeness sufficient condition for fault-tolerant and attack-tolerant NCS was deduced, so that the co-design method of robust H∞ fault-tolerant/attack-tolerant controller and event-triggered matrix was given out and the goal of co-design of the fault-tolerant and attack-tolerant control and the network communication was achieved. Finally, by means of simulative computational illustration, the effectiveness and feasibility of the theoretical result obtained were verified. References | Related Articles | Metrics

Select

Optimizing control method for sewage treatment based on improved multi-objective cuckoo algorithm ZHAO Xiao-qiang, LI Li-juan, FENG Xiao-lin 2020, 46 (1):  93-99.  Abstract ( 262 )   PDF (4949KB) ( 272 )   Save Aimed at the problems such as how to determine the optimal setting value of key variables in the process of optimizing control of wastewater treatment process (WWTP) to achieve the standard of effluent water quality and at the same time toreduce the energy consumption (EC) as much as possible, a multi-objective optimizing control method is proposed based on improved multi-objective cuckoo search algorithm (IMOCS). First, theEC and EQ models are presented based on neural network and analysis of wastewater treatment process. Then, both the EC and EQ models are simultaneously optimized by means of improved multi-objective cuckoo search algorithm and the optimal setting values of concentration of dissolved oxygen(DO) and nitrate-level nitrogen are obtained. Finally, the PID controller is chosen to conduct the tracing control of the optimal setting value, so that the multi-objective optimizing control of WWTP is achieved. Based on the international benchmark simulation platform No.1, and compared with other methods, it is shown that the proposed method can reduce EQ better in the process of sewage treatment and protect the environment, going on the premise of assuring the achievement of standard of the parameters of effluent water quality. References | Related Articles | Metrics

Select

Robust H∞ Fault-tolerant Controlof Markov jump system with mode-dependent time-delay uncertainty PANG Xin-rui, FU Xing-jian 2020, 46 (1):  100-105.  Abstract ( 181 )   PDF (2463KB) ( 255 )   Save Aimed at a class of singular Markov jump system with mode-dependent time-varying input time delay and state delay, its robust H∞ fault-tolerant control problem was studied when actuator failure took place. Based on integral-inequality method, the sufficient condition of existence of robust H∞ fault-tolerant control regularity ofmemory-less state feedback in such system was given by means of constructing Lyapunov-Krasovskii functional, and the robust H∞ fault-tolerant controller was designed to make the closed-loop system stable and satisfactory to certain H∞ interference inhibitation level. Finally, the effectiveness of the proposed method was verified by a simulation example. References | Related Articles | Metrics

Select

Investigation of particle variety based on target tracking of GDBA algorithm DU Xian-jun, MA Jin-dou 2020, 46 (1):  106-110.  Abstract ( 233 )   PDF (4044KB) ( 253 )   Save Aimed at the defect of small searching scope and low tracking accuracy of traditional target tracking algorithm, an improved bat algorithm(GDBA) is proposed based on genetic disturbance mechanism. In this algorithm, the genetic competitive mechanism is introduced to improve the bat algorithm, the crossover factor and the mutation rate in the genetic algorithm are adjusted according to the good-bad condition of optimization, so that the population will be made to have heritability and diversity and meantime, the searching range will be expanded and the tracking accuracy improved. References | Related Articles | Metrics

Select

Hierarchical and zonal optimizing control of voltage unbalance of multi-bus microgrid of power WU Li-zhen, WANG Xiao-ting, HAO Xiao-hong 2020, 46 (1):  111-117.  Abstract ( 207 )   PDF (3637KB) ( 294 )   Save There are different voltage quality requirements at different zones and busesof multi-bus microgrids on isolated island. In order to meet the needs of variety of power quality presented by each bus, a zonal control of voltage quality of multi-bus islanded microgrid should be carried out. Aimed at this problem, a hierarchical and zonal optimizing control strategy is proposed based on the analysis of compensation mechanism of voltage unbalance in multi-bus islanded microgrid. This hierarchical and zonal control configuration includes three levels and among them in the secondary control level, an unbalance compensation reference (UCR) is generated as the compensation basis of distributed generator(DG) to achieve voltage unbalance compensation at the public coupling point. In the tertiary control level, the artificial bee colony(ABC) algorithm is used to obtain the optimal tertiary compensation gain (TCGi), so that the DG output power reference value is adjusted to make each DG compensation amount distributed according to the proportion of its capacity and realize hierarchical and zonal optimizing control of voltage quality. It is verified by simulation result that the compensation policy proposed will be effective and feasible. References | Related Articles | Metrics

Architectural Sciences

Select

Stability analysis and evaluation of deep foundation pits in loess region based on constitutive models of different soils ZHOU Yong, SU Tian-tao 2020, 46 (1):  118-122.  Abstract ( 263 )   PDF (3745KB) ( 203 )   Save Two soil constitutive models with different hypothesis are selected:H-S model and M-C model, and the stability analysis of deep foundation pits in loess area is performed by means of finite element software PLAXIS, and compared with the calculation results of the slicing method. The following conclusions are summarized: since the H-S model exhibits harder than M-C model in the case of unloading, so that it will better reflect its better uprightability and higher strength of the loess, the resulting safety factor is higher, which will be more suitable for the stability analysis of foundation pits in loess areas; the construction of prestressed anchor will change the displacement field and stress field of the soil, making the potential slip facing the depth of soil and significantly increasing the stability coefficient of the foundation pit, and greatly contributing to the stability of the foundation pit; the strength reduction method will have a strong advantage over the conventional strip method. It will not need to divide the soil strip and assume the force and moment among the strips. The direct reduction of soil parameters will be more in line with the actual situation, and the resulting safety factor will be more accurate and can better reflect the formation process of the soil slip surface. References | Related Articles | Metrics

Select

Load-structure model of side pile deformation based on pile-tunnel method YUAN Yang-kou, JIAO You-quan, LUO Mu-chi, ZHANG HaoLIU Cheng-bin, FAN Zhi-yuan 2020, 46 (1):  123-128.  Abstract ( 912 )   PDF (5523KB) ( 393 )   Save Grasping the stress and deformation regularity of side pile is very important for the safety of pile-tunnel approach-based station. Based on the modified load-structure model, the deformation regularity of the side pile is studied and compared with the field-measured result. The result shows that the lateral displacement of the side pile from the top to the bottom plate will exhibit parabolic form and its lateral displacement below the bottom plate will basically be zero, and the initial branch system of the guide tunnel will be able to withstand the stress of largeportion of its surrounding rock. However, the lateral pressure coefficient near the bottom of the guide tunnel should be enlarged by 20 percent if the surrounding rock stress of the guide tunnel was ignored in the calculation model; and the lateral displacement of the side pile calculated with conventional load-structure model will be relatively small as a whole. The lateral displacement of the side pile calculated with modified load-structure model will be in better agreement with the field measured data. The axial force on side pile calculated with modified load-structure model will be greatly reduced and the shearing force in side pile and bending moment on it will bebasically unchanged. References | Related Articles | Metrics

Select

Distribution regularity of earth pressure on side wall ofpile-anchor supporting system SONG Jian-xue, LI Li-jian, XU Jian-wei, ZHANG Bao-bao 2020, 46 (1):  129-133.  Abstract ( 246 )   PDF (2719KB) ( 195 )   Save In order to investigate the distribution regularity of the earth pressure in pile-anchor supporting system of foundation pit engineering, the field measured data of an express way project in Zhengzhou was employed to calculate respectively the active, passive, static earth pressure and the results determined by earth pressure model under fournonlimit states compare them to their actually measured data, and the applicability of various models was discussed. The result showed that when thequasi-active displacement was small, the results of Zai Jinmin model, Xu Riqing model and Chen Yekai model would be approximately equal to the static earth pressure while the result of Lu Guosheng model would be small and the actually measured value would be between the static earth pressure and the active earth pressure. When the quasi-passive displacement was small, the results of Xu Riqing model and Chen Yekai model would be almost equal to the static earth pressure. The result of Zai Jinmin model would be approximately 1.3 times of the static earth pressure. The result of Lu Guosheng model would be relatively larger. For a practical project with sound geological condition and 3 mm less horizontal displacement of supporting pile in pile-anchor supporting system, the static earth pressure could be taken as the earth pressure in design and construction of the pile-anchor supporting system. References | Related Articles | Metrics

Select

Investigation of shear performance of outer ring-type node in spatial structure of concrete filled steel tube column-steel beam XIE Na 2020, 46 (1):  134-138.  Abstract ( 217 )   PDF (3070KB) ( 194 )   Save In order toprobe the shear performance of annular stiffener node in spatial structure ofconcrete filled steel tube (CFST) column-steel beam, the finite element models of circular and square spatial annular stiffener node were establishedunder three different loading modes on beam end by means of finite element software ABAQUS and the dependence of shear in node domain on displacement of beam end was analyzed. On this basis, four parameters that would affect the anti-shear performance of the node domain were selected and analyzed, so that the shear mechanism of spatial steel tube concrete node was clarified thereby. The result showed that the sequential loading at beam end in plane or out plane would make the shear performance of node domain mostunfavorable, the strength of steel beam, concrete column, and steel tube would be beneficial to the anti-shear performance of the node domain, and the axial compression ratio would be advantageous in a certain range, but more than that, the case would be opposite. References | Related Articles | Metrics

Select

Mechanical characteristicsof assembled base connection modes of asphalt concrete pavement SUN Jian-cheng, BAO Ke-duan 2020, 46 (1):  139-143.  Abstract ( 299 )   PDF (3480KB) ( 284 )   Save In order to study deeply the mechanical characteristics of assembled base structure of asphalt concrete pavement, the finite element software ABAQUS is used to simulate respectively the effects of concavo-convex fitting and plate-block side length on the mechanical characteristics of assembled base under dynamic loads or under the static load. The results show that the maximum vertical strain value at the bottom of the base course of the asphalt concrete pavement will be minimum when the plate-block side length is 1.5 m. After the concavo-convex connection is set, the strain at the bottom of the board will be further reduced and the cooperative working ability of the assembled base layer can be enhanced. In addition, the study shows, however, that the assembled base structure with and without connections can meet the requirements of maximum vertical strain and maximum horizontal tensile stress of the bottom of the board. References | Related Articles | Metrics

Select

Influencing factors upon runoff-type gully on linearly rammed earth ruins in arid area CUI Kai, WANG Guan-zhong, WANG Dong-hua, WANG Ze-lin 2020, 46 (1):  144-151.  Abstract ( 212 )   PDF (5824KB) ( 209 )   Save In order to investigate deeply the developmental mechanism and scientific prevention-cure method of the disease in the runoff-type gully on rammed earth ruins, the investigation of the factors of influence upon the activity of the runoff-type gully development is carried out. Therefore, by means of selecting the Great Wall of Mingdynasty with linear by rammed earth ruins, which has identical zone of preservation, era-technique attribution, and distribution of investigation, as investigation object and conducting the survey and statistics of the quantity and modal feature of the gully on the ruins with length of 1 km at 17 sites of Ming dynasty Great Wall, the linear density and shrinkage rate of the gully as its eigenvalues for characterization of activity of gully development at an area are presented. Then, the disintegration rate, liquidity index, cohesive force, annual average rainfall, annual average daily extreme rainfall, and annual average temperature diurnal variation as main influence factors are screened with regression analysis method. Finally, the evaluation model established by means of entropy weight and gray correlation method and it is found that the magnitude sequence of influence factors will be disintegration rate > liquidity index > cohesion force > annual average temperature diurnal variation > annual average rainfall > annual average daily extreme rainfall. The influence of internal factorof rammed earth is more significant than that of environmental factors in the process of runoff-type gully development of rammed earth ruins in arid areas of northwest China. References | Related Articles | Metrics

Scientific

Select

Dynamic behavior of stochastic predator-prey system with Lévy jumps HUANG Can-yun, LIANG Hong-yang, MENG Xin-you 2020, 46 (1):  152-157.  Abstract ( 704 )   PDF (2636KB) ( 196 )   Save Dynamic behavior of stochastic predator-prey model with Lévy jumps is investigated. By constructing an appropriate Lyapunov function and using It formula, the existence uniqueness of the global positive solution of the system is proven and the sufficient conditions that guarantee the stochastic permanence or extinction of the system are given out. Finally, numerical simulation is conducted to verify the validity of the theoretic result obtained. References | Related Articles | Metrics

Select

A class of maximum inequalities of conditional demi(sub)martingales FENG De-cheng, WEN Hui-min, YANG Ya-nan 2020, 46 (1):  158-161.  Abstract ( 207 )   PDF (1542KB) ( 309 )   Save A class of maximum inequalities of conditional demi(sub)martingales is given out and another maximum inequality of random variable sequence is obtained on the basis of maximum inequalities of demi-(sub)martingales. References | Related Articles | Metrics

Select

New multi-symplectic Fourier pseudospectral method for a class of DGH equation DAI Hong-bin, WANG Jun-jie, CAI Shan-shan, HOU Yuan-yuan 2020, 46 (1):  162-166.  Abstract ( 165 )   PDF (2825KB) ( 225 )   Save A numerical solution method of DGH equation was studied based on multi-symplectic theory in Hamilton space system. The multi-symplectic format of DGH equation was constructed with Fourier pseudospectral method and this format met the multi-symplectic conservation law. It was shown by the result of a numeric computation example that this multi-symplectic discrete format would have a better numeric value stability for a long time. References | Related Articles | Metrics

Select

Consensus of instantaneously coupled second-order multi-agent system and its time-delay effect ZHAO Li-yun, WANG Rui 2020, 46 (1):  167-172.  Abstract ( 229 )   PDF (3762KB) ( 228 )   Save An impulsive control algorithm is proposed for second-order multi-agent systems with communication and input time-delays. The consensus criteria for getting such algorithm are analyzed. In the meantime, the effects of communication and input time-delays on the consensus performance of second-order multi-agent systems are discussed. It is shown that communication time delay will be more important than input time-delay in connection with determining consensus dynamics of second-order multi-agent systems. Explicitly, when there is no communication time-delay, second-order multi-agent systems will be able to achieve dynamic consensus with a nonzero constant velocity of individual agent. Nevertheless, so long as there exists communication delay, the velocity consensus state of the system will be zero under certain condition. In addition, an even more interesting fact will be found that either the communication or input time-delay will enhance the synchronization performance of the second-order multi-agent systems under undirected network topology. Finally, some numerical simulations are used to verity the effectiveness of the theoretical result. References | Related Articles | Metrics