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Table of Content

    25 April 2020, Volume 48 Issue 4
    Architecture & Civil Engineering
    WU Bo YE Wenjie
    2020, 48(4):  1-8.  doi:10.12141/j.issn.1000-565X.190502
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    Axially compressive behavior of 12 circular concrete-filled steel tubular columns with built-in high-strength steel tube was experimentally studied. The influences of yield strength of the inner tube,clearance between the outer and inner tubes,steel ratio of inner tube,and replacement ratio of demolished concrete lumps (DCLs) on the columns’behavior were investigated. The test results show that,firstly,when the total steel usage keeps un-changed,the column’s axial load bearing capacity as well as initial stiffness can be greatly improved by thinning the outer steel tube and placing a high-strength steel tube inside; secondly,the axial load bearing capacity of such co-lumn can be further improved by appropriate increasing the clearance between the inner and outer steel tubes;thirdly,steel ratio change of inner tube and the reusing of DCLs have limited influence on the axial behavior of such column; finally,the proposed calculation method proves a high precision in measuring axial load bearing capacities of such columns.
    PENG Jianxin ZHAO Lei JIANG Yanmei
    2020, 48(4):  9-14.  doi:10.12141/j.issn.1000-565X.180627
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    The listening evaluation for the elderly over 60 years old was carried out under different reverberation time,different signal-to-noise ratio and different noise azimuth angle conditions. The effect of loudspeaker repro-duction and headphone reproduction on the speech intelligibility of the elderly was investigated. The speech intelli-gibility evaluation results of the elderly were compared with those of young adults with normal hearing. The results show that Chinese speech intelligibility score obtained from loudspeaker reproduction is slightly higher than that ob-tained from headphone reproduction. But this difference is not significant. The difference in speech intelligibility scores of the elderly between two reproduction modes is slightly larger than those of the young adults. The results of Chinese speech intelligibility evaluation in rooms for the elderly by reproducing the signals recorded by the artificial head are basically consistent with those for the elderly by listening in the real environment.
    DING Xiaobin SHI Yu CHEN Junsheng
    2020, 48(4):  15-27.  doi:10.12141/j.issn.1000-565X.190454
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    The penetration process of the large-diameter steel cylinder in sandy soil was stimulated with a three-di-mensional particle flow code (PFC3D) based on the discrete element method (DEM). A scaled model based on the principle of the centrifuge and a full-scale model with adjusting the micro-parameters were developed to analyze the sliding friction force distribution of the cylinder during installation and the contact force chain of soil particles.The DEM model was validated by comparing the simulated results with theoretical values and reported experimental phenomena. The effects of micro parameters of particles and contacts on side friction were studied through further parametric analysis. The study results show that,unlike pile penetration,there is almost no soil-plug effect during penetration process of large-diameter steel cylinder. Besides,the inside friction is half of the total friction,and the side friction has the effect of friction fatigue during installation. Compared with the scale model,the full-scale mo-del with adjustable micro-parameters has better calculation efficiency. There is a close relationship between the side friction and micro parameters.
    TAO Wenbin, TAO Jie, HOU Junling, et al
    2020, 48(4):  28-37.  doi:10.12141/j.issn.1000-565X.190517
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    In view of the complex geological environment of deep roadways,the intense deformation of surrounding rocks,and the deformation of roadways reaching hundreds of millimeters,a dynamic optimal support design scheme was proposed. It is based on in-situ stress measurement,full-range monitoring of force-measuring bolts,and high pre-tightening force full-length anchoring technology,and modified by numerical simulation. Taking the transporta-tion roadway of 1621(1) working face of Pansan Coal Mine in Huainan as an example,the stress relief method was used to measure the in-situ stress,and the force measuring bolt was installed at the key position of the tunnel to mo-nitor and record the axial force of the bolt in real time. Combined with the numerical simulation,the support schemes before and after optimization were compared. The results show that horizontal stress is the main factor in deep roadway. With the increase of the angle between the direction of roadway driving and the direction of maxi-mum horizontal principal stress and the increase of the principal stress difference,the deformation of roadway in-creases rapidly. Due to its small pre-tightening force in existing support schemes,the full-length anchorage cannot
    play its full role,and the shallow roof of roadway shows intense deformation. In the optimized support design scheme,the anti-deformation ability of surrounding rock is improved by high pre-tightening force combined with full-length anchorage support. And the characteristics improvement and the effective stress increase of surrounding rock can reduce the deformation of roadway,thus contributing to a sound support effect.
    Mechanical Engineering
    ZHOU Zhaoyao LU Huangjun WANG Junwen
    2020, 48(4):  38-44.  doi:10.12141/j.issn.1000-565X.190447
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    Using 304 stainless steel wire mesh as raw material,the sintered stainless steel wire mesh porous plate was prepared by winding,pressing,rolling and vacuum sintering. The surface picture of the plate was obtained by scanning electron microscopy (SEM). The formation process of the interface and the pore was analyzed,and the pore size,pore distribution and porosity of the stainless steel wire mesh porous material were obtained. Based on the improved Darcy’s law,a device for testing the permeability of the porous plate was designed. The viscous per-meability coefficient and the inertial permeability coefficient were used as the air permeability index of the porous plate to evaluate the permeability of the stainless steel wire mesh porous material. Then the influence of porosity on the permeability of the stainless steel wire mesh porous material was determined. The study result shows that the plate has uniform pore distribution and continuous metal skeleton,with a pore diameter of 0 ~60μm and a porosity of 20% ~40%. The study also indicates a close relationship between permeability and porosity as well as thick-ness,which means the permeability of porous material increases with the increase of the porosity and the decrease of the thickness.
    GUO Mingjun, LI Weiguang, YANG Qijiang, et al
    2020, 48(4):  45-53.  doi:10.12141/j.issn.1000-565X.190622
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    A fault feature frequency extraction algorithm based on sparse decomposition theory was proposed to solve the problem of chaotic orbit of the rotor directly synthesized. According to the signal characteristics of the ro-tating machinery,the cosine wave model was used to construct a complete dictionary sets,and the matching pursuit algorithm was used to solve the sparse coefficient. The algorithm was used to purify the simulation axis trajectories polluted by white Gaussian noise. The results were almost identical with the ideal ones,and the validity of the algo-rithm is verified. Finally,the proposed algorithm was used to purify the multi-condition axis trajectories under vari-ous of large sliding bearing test-rig,and the corresponding fault types of the rotor were successfully identified. In addition,combined with the theory of dynamic pressure lubrication and the changing rule of spindle position,the fault causes were analyzed.
    SU Hailiang, LAN Fengchong, HE Yuyan, et al
    2020, 48(4):  54-64.  doi:10.12141/j.issn.1000-565X.190275
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    Traditional structural topology optimization analysis and design is a deterministic physical model based on specific parameters. However,in the actual design process,there are a wide range of uncertainties,which extreme-ly affect the physical properties of the structure. In this study,the variation of structural parameters was quantified by the non-probabilistic reliability based on multi-ellipsoidal convex model,and the topology optimization problem with uncertain but bounded parameter continuum structure was studied. Firstly,the reliability topology optimization model with variable uncertainty was established,taking the structural design quality minimization as the objective function. Then,based on the geometric meaning of the reliability index,the non-probability model was used to find the design point that satisfies the target reliability index constraint. On this basis,the interval Chebyshev zero poly-nomial was applied to approximate the real limit state function of the normalized random variable,and the single-loop reliability algorithm was used to calculate the optimal design points value under the corresponding target relia-bility index,so that the optimization problem of non-probability reliability can be transformed into deterministic op-timization problem. The effectiveness of the method was illustrated by two numerical examples. The results show that,compared with the deterministic structural topology optimization design,the reliability topology optimization with random variables can obtain more reliable topology structure.
    LIU Guang LIU Jike Lü Zhongrong
    2020, 48(4):  65-72,94.  doi:10.12141/j.issn.1000-565X.190117
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    Compared with the integer order differential operator,fractional order operator can describe some charac-teristics of the system more accurately,such as hereditary and memory properties. In order to find a more accurate and efficient way to solve the fractional order system,a new computational scheme designed to get the system re-sponse was put forward based on Adams-type scheme and the Newmark-β method. The inverse problem of parame-ter identification was considered as a nonlinear optimization problem. And the enhanced response sensitivity method was used to solve the identification equation. Numerical examples show that the calculation format of the direct problem proposed in the paper can quickly and accurately get response from the system,so the enhanced response sensitivity method can accurately identify the parameters of the fractional system and be insensitive to the measure-ment noise.
    Chemistry & Chemical Engineering
    CAO Xianwu, WEI Chuang, HE Guangjian, et al
    2020, 48(4):  73-79.  doi:10.12141/j.issn.1000-565X.190724
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    In order to improve the thermoplasticity of polyimide,a series of novel quaternary copolymerized poly-imide materials were successfully synthesized by two-step method with 1,2,4,5-benzenetetracarboxylic anhydride(PMDA) and 3,3',4,4'-biphenyltetracarboxylic dianhydride ( s-BPDA) as dianhydride,4,4'-oxydianiline(ODA) and 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP) as diamine. The synergistic effect of rigid bi-phenyl groups with flexible monomers and pendant methyl groups on the properties of polyimide was studied. The molecular structure,thermoplasticity and heat resistance of the polyimides were characterized by FTIR,XRD,DMA,TGA and other testing methods. The results show that the series of quaternary copolymerized polyimides have good thermoplasticity and heat resistance. Particularly,when the molar fraction ratio of PMDA ∶ s-BPDA ∶ ODA ∶BAPP is 70 ∶ 30 ∶ 70 ∶ 30,the polyimide exhibits excellent thermoplasticity and heat resistance. What’s more,its good solubility in aprotic polar solvent can greatly improve the processing properties of the polyimide in a solvent or molten state.
    SU Jianyu, GUAN Jingwei, FANG Liming, et al
    2020, 48(4):  80-86.  doi:10.12141/j.issn.1000-565X.190588
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    There is an urgent need for novel antimicrobial alternatives due to the increasing drug resistant bacteria and the slow development of antibiotics. Citral is a natural broad-spectrum antibacterial agent with poor stability and applicability. Metal organic framework is a porous material synthesized from metal ions and organic building blocks with large specific surface area. The metal ions endow it with antibacterial property,and rich organic ligands allow it for easier functionalization. As a result,nano-sized metal organic framework particles (IRMOF-3) with amino groups were synthesized by zinc acetate method,and the particle surface was grafted with citral (IRMOF-3-C).Fourier transform infrared spectroscopy and electrospray ionization mass spectrometry analysis indicates that citral and IRMOF-3 form a Schiff base bond with an acid responsibility. Antibacterial tests show that,as compared with citral and IRMOF-3,IRMOF-3-C can significantly improve the bacteriostatic and bactericidal properties against Escherichia coli and Staphylococcus aureus,and exhibits good antibacterial property and stability.
    JIANG Xiang, TIAN Mengmeng, LEI Yu, et al
    2020, 48(4):  87-94.  doi:10.12141/j.issn.1000-565X.190569
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    Superhydrophobic coating on the copper surface was prepared with a mixed aqueous solution of NaOH and ( NH4 )2S2O8 as oxidant and heptafluorodecyltrimethoxysilane ( FAS-17) as a low surface energy modifier to solve the problem that metal copper is easily corroded in a solution containing Cl- . The structure,morphology and composition of the coating were characterized by X-ray diffraction analysis ( XRD) ,scanning electron microscopy ( SEM) and X-ray photoelectron spectroscopy ( XPS) . The corrosion resistance of samples was analyzed by Tafel polarization curve and EIS spectrum in 3. 5% ( mass fraction,the same below) NaCl solution. The results show that,after being immersed in NaCl solution for 10 min,a dense and uniform CuO nanowire structure grows on the surface of the copper. The contact angle ( CA) of the chemically modified surface is greater than 160° and the slid-ing angle ( SA) is less than 3° for deionized water. Compared with bare Cu substrates,surfaces with super-hydro-phobic CuO nanowires exhibit a lower corrosion current density ( Icorr = 3. 285 × 10-6 A/cm2 ) ,and the corrosion re-sistance efficiency reaches 99. 65% . And after being soaked in 3. 5% NaCl solution for 6 days,the surfaces still
    own super-hydrophobicity. Compared with the current method of using corrosion inhibitors to inhibit copper corro-sion,the proposed method is more environmentally friendly and cheaper.
    YING Rui, JIANG Jin, LI Yanhui, et al
    2020, 48(4):  95-103.  doi:10.12141/j.issn.1000-565X.180623
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    Inner cone hydrocyclone ( ICH) is a new type of hydrocyclone with a reversed inner cone structure main- ly used in liquid-liquid separation at present. To investigate the feasibility of ICH for particle classification,Rey- nolds stress turbulence model and Eulerian two-fluid model (RSM + TFM) were coupled to construct the flow field with gas-liquid-solid phase of ICH and conventional hydrocyclone. The comparative analysis was conducted from the aspects of pressure drop,velocity distribution,particle motion behavior,and separation efficiency. Model valida- tion result shows that the CFD numerical model constructed in this study is consistent with relevant experiment re- sult,and that its prediction on tangential velocity,axial velocity,separation efficiency is reliable. The simulation results indicates that,compared with conventional hydrocyclone,ICH has a lower pressure drop,which can help to reduce the energy consumption of the separation operation,but also leads to a weaker centrifugal force field. In ad- dition,ICH has a better separation effect on coarse particles,and the refined production from the over flow is of higher quality. However,the recovery ability of ICH for fine particles is poor,which results in a larger fine particle loss from the underflow.
    Traffic & Transportation Engineering
    ZHANG Chi, HU Tao, LIN Xuancai, et al
    2020, 48(4):  104-113.  doi:10.12141/j.issn.1000-565X.190341
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    Exclusive low-speed lane for large trucks was designed to improve the driving safety of large trucks in continuous downhill section of highways. The driving characteristics of large trucks going downhill under the condi- tion of engine auxiliary braking were analyzed. Based on the brake drum temperature and speed characteristics,it was proposed that there is a necessity to construct an exclusive low-speed lane in continuous long downhill section of highways for large trucks. Taking the six-axis articulated vehicle as the guiding type,the low-speed lane structure system was studied for the driving safety of articulated vehicles when going downhill. the setting method of the low- speed lane was clarified. The lane structures including transition section,buffer zone,steady speed zone and its linear shape were proposed. Then the reasonable speed limit and recommended gear of the low-speed lane was ana- lyzed. Finally,taking a long downhill slope in G5 Jing-kun highway as an example,the temperature rise value of the truck brake drum under various traffic modes was simulated,and the passing safety of the low-speed lane was verified. The results show that,compared with the temperature of brake drum in downhill of free-flow speed lanes and in downhill of limit speed lanes,the temperature of brake drum on downhill bottom of the slow-speed lane is re- duced by 114 and 79 ℃,respectively,and the cooling amplitude can reaches 32. 9% and 25. 3% ,respectively. The maximum temperature in the low-speed lane section is lower than the critical safety temperature. It indicates that setting a low-speed lane in the continuous long downhill section can greatly reduce the rising temperature of the brake drum as well as the probability of brake failure.
    FANG Xiaoping, LIN Mei, CHEN Weiya, et al
    2020, 48(4):  114-122.  doi:10.12141/j.issn.1000-565X.190465
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    Identifying the feature of bus passenger flow is the key to improve the quality of short-time prediction. However,due to equipment failure,data collection constraint and other reasons,the attributes of passenger flow data are often incomplete,which brings challenges to feature recognition and passenger flow prediction. The card data of No. 104 bus in Changsha,lacking passenger attribute data,was taken as the sample in this paper. The cor- relation between card number and travel time was used to identify passengers’travel frequency,which was used as a variable to distinguish the feature of travel. The total passenger flow set was divided into different feature subsets, and the optimal value of variable was determined according to the subset size and variance value,and the attributes of passenger flow were inferred. Compared with direct prediction of total passenger flow,the Seasonal Auto-Regres- sive Integrated Moving Average ( SARIMA) model established for each subset was respectively used for prediction. The out of sample Mean Absolute Error ( MAE) obtained by integrating is improved by 36. 11% . The fitting degree of prediction model based on the feature of passengers’travel is 0. 95,thus can effectively identify the feature of bus passenger flow.
    TIAN Sheng, XU Kai, ZHU Zekun, et al
    2020, 48(4):  123-131.  doi:10.12141/j.issn.1000-565X.190413
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    A day-to-day model of hybrid traffic flow including traditional and autonomous vehicles was established, in order to study the influence of autonomous vehicles on the evolution of traffic flow. The different evolutionary ob- jects of the two flows were analyzed,and the prospect theory was used to describe the traveler’s behavior. The day-to-day model of traditional vehicle flow was established with the maximum prospect value of the path,and the day-to-day model of the autonomous vehicle flow was established with the minimum marginal impedance of the path. Finally,an example was used to simulate the day-to-day process of the hybrid traffic flow. The results show that,firstly,the time and evolutionary trend of the traffic flow between the traditional vehicle and the autonomous vehicle are significantly different,and the two interact with each other and constitute the evolution of hybrid flow; secondly,the higher proportion of autonomous vehicle,the less of total system time,and the path flow under differ- ent proportions evolves into different stable states; thirdly,the flow transfer threshold affects the stable condition of the hybrid flow,and its steady state is different from the no-threshold condition; finally,autonomous vehicles can affect the distribution of traffic flow before and after short-term events.
    CHEN Bo, ZHANG Xiaoning, YU Jiangmiao, et al
    2020, 48(4):  132-141.  doi:10.12141/j.issn.1000-565X.190459
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    The skid resistance performance of the pavement is the key to solve the traffic safety problem,and the contact behavior between the tire and the rough surface texture is essentially a contact mechanics problem. In order to obtain the complete contact stress information of tire and rough pavement,this study adopted flexible pressure film sensor technology. A tire-road contact stress testing method based on image registration and fusion technology was proposed with the help of medical image process technology. And the registration and fusion effect evaluation and adaptability analysis were carried out. The results show that,based on the dual objective characteristics of the contact imprints between tire and pavement,the problem of convergence and optimal solution of multi-specification film image registration can be resolved by evolutionary algorithms. The proposed dynamic reference image registra- tion ( DRIR) algorithm has high registration accuracy and computational efficiency,and it can be applied to diffe- rent asphalt pavements. The relative error of the contact stress concentration distribution index can be restricted within 5% . The proposed method is easy to operate,accurate and 3D visual,and provides a new technical means for the study of tire-ground characteristics and pavement skid resistance performance.
    CHANG Xin, LI Haijian, RONG Jian, et al
    2020, 48(4):  142-148.  doi:10.12141/j.issn.1000-565X.190371
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    Under the context of intelligent network,vehicles can enact cooperatively at a small headway,and con- tinuous connected vehicles will be in platoon configurations by information interaction of vehicle-to-vehicle or vehi- cle-to-infrastructure communication. Thus,the road capacity will be improved effectively. Considering the traffic flow randomly mixed with regular vehicles and connected vehicles,4 types of car-following characteristics and its spatial distribution probability in heterogeneous traffic flow were analyzed. Then the fundamental diagram model and the passenger car equivalents ( PCE) were obtained. And the sensitivity analyses on penetration rate of connected vehicle and platoon size were carried out.Research results show that the improvement of the penetration rate of the connected vehicles and the increase of the platoon scale will help enhance the traffic capacity and reduce the PCE. Moreover,the positive impacts will be more obvious with the increase of the penetration rate of the connected vehi- cles. When the vehicle platoon scale is larger than 4,its impact on the traffic capacity improvement and the PCE reduction will decrease significantly.
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