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Effect of Wheel Load on Wheel Vibration and Sound Radiation

Chinese Journal of Mechanical Engineering 2015年第1期28卷 46-54页

作者： HAN Jian WANG Ruiqian WANG Di GUAN Qinghua ZHANG Yumei XIAO Xinbiao JIN Xuesong State Key Laboratory of Traction Power Southwest Jiaotong University

The current researches of wheel vibration and sound radiation mainly focus on the low noise damped wheel. Compared with the traditional research, the relationship between the sound and wheel/rail contact is difficulty and worth studying. However, there are few studies on the effect of wheel load on wheel vibration and sound radiation. In this paper, laboratory test carried out in a semi-anechoic room investigates the effect of wheel load on wheel natural frequencies, damping ratios, wheel vibration and its sound radiation, The laboratory test results show that the vibration of the wheel and total sound radiation decrease significantly with the increase of the wheel load from 0 t to 1 t. The sound energy level of the wheel decreases by 3.7 dB. When the wheel load exceeds 1 t. the attenuation trend of the vibration and sound radiation of the wheel becomes slow. And the increase of the wheel load causes the growth of the wheel natural frequencies and the mode damping ratios. Based on the finite element method （FEM） and boundary element method （BEM）, a rolling noise prediction model is developed to calculate the influence of wheel load on the wheel vibration and sound radiation. In the calculation, the used wheel/rail excitation is the measured wheel/rail roughness. The calculated results show that the sound power level of the wheel decreases by about 0.4 dB when the wheel load increases by 0.5 t. The sound radiation of the wheel decreases slowly with wheel load increase, and this conclusion is verified by the field test. This research systematically studies the cffcct of wheel load on wheel vibration and sound radiation, gives the relationship between the sound and wheel/rail contact and analyzes the reasons, therefore, it provides a reference for further research.

关键词： wheel load vibration and sound radiation finite element method (FEM) boundary element method (BEM) laboratory test field test

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Application of gas wettability alteration to improve methane drainage performance:A case study

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International Journal of Mining Science and Technology 2021年第4期31卷 621-629页

作者： Lin Jia Kewen Li Xiaohong Shi Lipeng Zhao Jianshe Linghu School of Energy Resources China University of Geosciences(Beijing)Beijing 100083China Key Laboratory of Marine Reservoir Evolution and Hydrocarbon Enrichment Mechanism Ministry of EducationBeijing 100083China Department of Energy Resources Engineering Stanford UniversityStanfordCA 94305USA Huayang New Material Technology Group Co. Ltd.Yangquan 045000China School of Resources and Environment Henan Polytechnic UniversityJiaozuo 454000China

Hydraulic fracturing technique is widely used for methane drainage and has achieved good effects in numerous coal mines,but negative effects may occur as the fracturing fluids are absorbed into the coal *** wettability alteration(GWA)technology can be used as it can enhance the gas and water mobility during dewatering process as a result of capillary pressure ***,there have been few reported field tests in coal mines using GWA *** paper describes a pilot-scale field test in Xinjing coal mine,Yangquan,*** fluorocarbon surfactants perfluorooctyl methacrylate monomer-containing polymethacrylate(PMP)was used to alter the wettability of coal seam to strong gas-wetness during the hydraulic fracturing *** study focuses on the comparison of two boreholes(Boreholes#9 and#10)and one other borehole(Borehole#8)with and without using GWA approach.A well-defined monitoring program was established by measuring the dewatering volume of the fracturing fluid and the drainage volume of methane as well as the *** field test results showed that the average methane drainage rates of Boreholes#9(39.28 m^(3)/d)and#10(51.04 m^(3)/d)with GWA treatment exceeded that of Borehole#8(21.09 m^(3)/d)without GWA treatment,with an increase of 86.3%and 142.1%,*** average methane concentrations of Boreholes#9(4.05%)and#10(6.18%)were 64.6%and 151.2%higher than that of Borehole#8(2.46%),*** the other hand,the dewatering ratio of Boreholes#9(4.36%)and#10(3.11%)was almost 19 times and 13 times greater than that of Borehole#8(0.22%).These field test results were in agreement with the experimental *** significant increase in both methane concentration and dewatering ratio demonstrated that GWA technology could be applied for enhanced methane drainage in coal *** lessons learned at Xinjing coal mine might be applied to other coal mines in China and elsewhere.

关键词： field test Hydraulic fracturing Wettability alteration to gas-wetness Drainage of methane

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General Design and Thermodynamic Analysis of a Supercritical Carbon Dioxide Cannon

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Journal of Thermal Science 2021年第1期30卷 123-132页

作者： ZHANG Fan LIU Hongrui WU You LI Jiaqi YU Huazhang WANG Xiaoliang GUO Baoting YUAN Yixiang Key Laboratory of Light Duty Gas Turbine Institute of Engineering ThermophysicsChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Department of Fluid Control and Automation Harbin Institute of TechnologyHarbin 150001China Force Academy of People’s Armed Police Beijing 100012China

This paper presents a new supercritical carbon dioxide(SCO_(2))cannon based on the carbon dioxide(CO_(2))’s thermodynamic cycle under constant ***,Virial equation and NIST database are applied to formulate SCO_(2)’s property and analyze the thermodynamic cycle,which is aimed to get the optimization equation using the cannon’s exit velocity as objective *** the cannon’s structural parameters,such as diaphragm thickness and barrel length,and CO_(2)’s filling mass,are ***,the flow field and velocity’s change during the launch process is performed with *** field test,the ultra-high pressure sensor and ultra-high speed camera are used to measure the pressure distribution along the barrel’s axial direction and the projectile’s exit velocity under different *** results show that all the performance indexes meet the design *** innovative SCO_(2)cannon in this paper has obvious advantages such as high safety,low cost and fast loading,which can be applied in many situations such as disaster relief,peacekeeping and ***,the unique energy storage method and thermodynamic design ensure its subsequent development.

关键词： supercritical carbon dioxide(SCO_(2))cannon state equation thermodynamic analysis field test

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Water hammer in the pump-rising pipeline system with an air chamber

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Journal of Hydrodynamics 2014年第6期26卷 960-964页

作者： KIM Sang-Gyun LEE Kye-Bock KIM Kyung-Yup Korea Water Resources Corporation School of Mechanical Engineering Chungbuk National University School of Mechanical Engineering Korea Polytechnic University

Water hammer following the tripping of pumps can lead to overpressure and negative pressure. Reduction in overpressure and negative pressure may be necessary to avoid failure, to improve the efficiency of operation and to avoid fatigue of system components. The field tests on the water hammer have been conducted on the pump rising pipeline system with an air chamber. The hydraulic transient was simulated using the method of characteristics. Minimizing the least squares problem representing the difference between the measured and predicted transient response in the system performs the calibration of the simulation program. Among the input variables used in the water hammer analysis, the polytropic exponent, the discharge coefficient and the wave speed were calibrated. The computer program developed in this study will be useful in designing the optimum parameters of an air chamber for the real pump pipeline system. The correct selection of air chamber size and the effect of the inner diameter of the orifice to minimize water hammer have been investigated by both field measurements and numerical modeling.

关键词： air chamber design parameter field test pump pipeline system water hammer

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Influence of asymmetric blockage of the drainage system of a deep-buried tunnel on water gushing

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Journal of Mountain Science 2022年第7期19卷 2075-2085页

作者： FU He-lin AN Peng-tao WU Yi-min LI Jie CHEN Long School of Civil Engineering Central South UniversityChangsha410075China National Engineering Laboratory for Construction Technology of High Speed Railway Central South UniversityChangsha410075China

Asymmetric blockage of drainage systems occasionally occurs,which seriously threatens the safety of tunnel *** on theoretical analysis,a calculation expression of tunnel water inflow involving clogging parameters was *** of the analytical solution was analysed with the Taylor equation and series expansion theorem,and a tunnel under construction was considered to conduct field tests to verify the rationality of the established model and correctness of the derived *** have demonstrated that with increasing drainage system blockage degree,the amount of water inflow in the nonblocked area slowly increases,and the total amount of water in the tunnel gradually *** hydrodynamic pressure in the blocked area non-linearly decreased,and the water inrush velocity and hydraulic gradient in the non-blocked area gradually *** the drainage system was not blocked,the result of tunnel water inflow calculated by the formula derived in this paper was 8.3% higher than the measured *** the drainage system was blocked,the theoretical water inflow was 10.5% higher than the measured *** difference between the measured value and the theoretical value is small,which verifies the effectiveness of the calculation formula of water inflow deduced in this paper.

关键词： Drainage system Asymmetric blockage Water inflow field test

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Strengthening an in-service reinforcement concrete bridge with prestressed CFRP bars

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第5期10卷 635-644页

作者： Hai-long WANG Wei-liang JIN David J. CLELAND Ai-hui ZHANG Department of Civil Engineering Zhejiang University Hangzhou 310027 China School of Planning Architecture and Civil Engineering Queen's University Belfast Belfast BT9 5AG UK

Carbon fiber reinforced polymer (CFRP) bars were prestressed for the structural strengthening of 8 T-shaped rein-forced concrete (RC) beams of a 21-year-old bridge in China. The ultimate bearing capacity of the existing bridge after retrofit was discussed on the basis of concrete structures theory. The flexural strengths of RC beams strengthened with CFRP bars were controlled by the failure of concrete in compression and a prestressing method was applied in the retrofit. The field construction processes of strengthening with CFRP bars-including grouting cracks, cutting groove, grouting epoxy and embedding CFRP bars, surface treating, banding with the U-type CFRP sheets, releasing external prestressed steel tendons-were introduced in detail. In order to evaluate the effectiveness of this strengthening method, field tests using vehicles as live load were applied before and after the retrofit. The test results of deflection and concrete strain of the T-shaped beams with and without strengthening show that the capacity of the repaired bridge, including the bending strength and stiffness, is enhanced. The measurements of crack width also indicate that this strengthening method can enhance the durability of bridges. Therefore, the proposed strengthening technology is feasible and effective.

关键词： Carbon fiber reinforced polymer (CFRP) bar Reinforced concrete (RC) bridge Strengthening Construction pro-cedure field test T-shaped beam

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Axial bearing behavior of super-long piles in deep soft clay over stiff layers

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Journal of Central South University 2013年第7期20卷 2008-2016页

作者：邹新军赵明华 College of Civil Engineering Hunan University

In order to find out the bearing behavior of super-long piles located in deep soft clay over stiff layers around Dongting Lake, China, a test pile was first designed with the field loading test finished afterward. Based on the measured test results, load transfer mechanism and bearing behavior of the pile shaft were discussed in detail. Then, by introducing a bi-linear model for shaft friction and the tri-linear model for pile tip resistance, respectively, the governing differential equation of pile soil system was set up by the load transfer method with the analytical solutions derived as well, taking into account the effect by stratified feature and various bearing conditions of subsoil, material nonlinearity, and the sediment under pile tip. Furthermore, formulas to determine the axial capacity of super-long piles by the pile top settlement were advised and applied to analyze the test pile. Good agreement between the predicted load settlement variations and the measured data is obtained to verify the validity of the present method. The results also show that, the axial bearing capacity of super-long piles should be controlled by the allowable pile top settlement, and buckling stability of the pile shaft should be paid attention as well.

关键词： super-long pile settlement load transfer model axial load capacity field test

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Development and evaluation of a general-purpose electric off-road robot based on agricultural navigation

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International Journal of Agricultural and Biological Engineering 2014年第5期7卷 14-21页

作者： Yin Xiang Noboru Noguchi School of Agricultural and Food Engineering Shandong University of TechnologyZibo 255049China Bio-production Engineering Graduate School of AgricultureHokkaido UniversityKita-kuSapporo 060-8589Japan

The aim of this study was to develop a general-purpose electric off-road robot vehicle by using automatic control *** vehicle prototype used in this study was a commercially-purchased electricity utility vehicle that was designed originally for manual operations.A manipulating unit,an automatic steering system and a speed control system were developed and integrated into a CAN-bus network for operating on functions(forward,reverse,park or stop),realizing desired steering angles and maintaining a constant speed,respectively,in the mode of *** autonomous navigation system based on RTK-GPS and IMU was used to evaluate the performance of the newly developed off-road *** tests showed that the maximum error in speed control was 0.29 m/s and 0.22 m/s for speed tests and autonomous runs,*** lateral offset was less than 10 cm in terms of straight paths,indicating that the automatic steering control system was of good performance.

关键词： electric off-road robot automatic control automatic steering speed control autonomous navigation system field test

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Analysis of ground deformation development and settlement prediction by air-boosted vacuum preloading

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Journal of Rock Mechanics and Geotechnical Engineering 2022年第1期14卷 272-288页

作者： Shuangxi Feng Huayang Lei Cheng Lin Department of Civil Engineering Tianjin UniversityTianjin300354China Key Laboratory of Coast Civil Structure Safety of the Ministry of Education Tianjin UniversityTianjin300354China Key Laboratory of Comprehensive Simulation of Engineering Earthquake and Urban-Rural Seismic Resilience China Earthquak AdministrationTianjin300354China Department of Civil Engineering University of VictoriaVictoriaBCV8P 5C2Canada

Vacuum preloading has been widely used to improve soft soils in coastal areas of *** increasing amount of evidence from field operations has shown that conventional vacuum preloading is prone to clogging in prefabricated vertical drains(PVDs)and demands a large volume of sand *** recent years,air-boosted vacuum preloading has been developed to overcome these limitations;however,this method still requires more data to verify its *** this study,a field test for air-boosted vacuum preloading was conducted,and a large-strain two-dimensional(2D)finite element(FE)model was developed and validated against the field test ***,a series of FE parametric analyses was performed to assess key factors,*** air injection pressure,the injection spacing,and the characteristics of cyclic injection,which affect the performance of the air-boosted vacuum *** results showed that the ground settlement and lateral displacement of the soils increased due to an increase in the injection pressure,a decrease in the injection spacing,or increases in the number and duration of the injection *** on the parametric analyses,an empirical formula for ground settlement prediction was proposed and compared with a case history reported in the literature,showing good agreement.

关键词： Air-boosted vacuum preloading field test Numerical modeling Settlement Soft soils Ground improvement

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Full-scale pullout tests of rock anchors in a limestone quarry focusing on bond failure at the anchor-grout and grout-rock interfaces

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第9期15卷 2264-2279页

作者： Bjarte Grindheim Charlie CLi Are Håvard Høien Department of Geoscience and Petroleum Norwegian University of Science and Technology(NTNU)TrondheimNorway Norwegian Public Roads Administration(NPRA) BergenNorway

Rock anchors are a common safety measure for stabilising large-scale infrastructure,such as bridge towers,retaining walls,rock slopes and *** are four principal failure modes for rock anchors:(a)tensile failure of the steel anchor,(b)anchor-grout interface failure,(c)grout-rock interface failure,and(d)rock mass *** tests were performed in a limestone *** tests were designed to test failure modes B and C through *** the tests of failure mode B,the shear stress on the anchor-grout interface is the largest at the top of the grout column and attenuates towards the distal end for small *** shear stress becomes uniformly distributed when the applied load is approximately 50%of the ultimate pullout *** anchors designed to test failure mode C were installed with an endplate and had a higher toughness than the straight bar *** shear stress on the grout-rock interface is the largest at the endplate and attenuates upward before slip starts along the *** the ultimate pullout load is reached,and the grout column starts to slip,the shear stress is approximately *** bond shear strength on the anchor-grout interface was approximately 20%of the uniaxial compressive strength of the grout,and the bond strength of the grout-rock interface was around 5%for that of the *** grout-rock interface is likely determined by whichever is weaker,the grout or the rock.

关键词： Rock anchor Load transfer Shear stress distribution Bond shear strength field test

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