In order to overcome the flaws of present domestic devices for detecting faulty wires such as low precision,low sensitivity and instability,a new instrument for detecting and processing the signal of flux leakage caus...In order to overcome the flaws of present domestic devices for detecting faulty wires such as low precision,low sensitivity and instability,a new instrument for detecting and processing the signal of flux leakage caused by bro-ken wires of coal mine-hoist cables is investigated. The principle of strong magnetic detection was adopted in the equipment. Wires were magnetized by a pre-magnetic head to reach magnetization saturation. Our special feature is that the number of flux-gates installed along the circle direction on the wall of sensors is twice as large as the number of strands in the wire cable. Neighboring components are connected in series and the interference on the surface of the wire cable,produced by leakage from the flux field of the wire strands,is efficiently filtered. The sampled signal se-quence produced by broken wires,which is characterized by a three-dimensional distribution of the flux-leakage field on the surface of the wire cable,can be dimensionally condensed and characteristically extracted. A model of a BP neu-ral network is built and the algorithm of the BP neural network is then used to identify the number of broken wires quantitatively. In our research,we used a 6×37+FC,Φ24 mm wire cable as our test object. Randomly several wires were artificially broken and damaged to different degrees. The experiments were carried out 100 times to obtain data for 100 groups from our samples. The data were then entered into the BP neural network and trained. The network was then used to identify a total 16 wires,broken at five different locations. The test data proves that our new device can enhance the precision in detecting broken and damaged wires.展开更多
The carrier-based aircraft landing and arrest process is complex and nonlinear,and includes the coupling effect between the aircraft and arresting system.It has many uncertain factors,which lead to difficulty in the r...The carrier-based aircraft landing and arrest process is complex and nonlinear,and includes the coupling effect between the aircraft and arresting system.It has many uncertain factors,which lead to difficulty in the reliability analysis.To make the reliability analysis more accurate and effective,this paper presents some studies.Taking a certain type of carrier-based aircraft as the research object,a dynamic model of the landing and arrest cable was established,and the accuracy of the model was verified using laboratory test results.Based on the model,this paper shows how the key parameters,including the sinking velocity,pitch angle and horizontal velocity,affect the collision rebound performance of the arresting hook.After that,a limit state equation of the arresting hook system’s reliability was established.For the implicit limit state equation,a surrogate model of the reliability of the arresting hook was established using the Support Vector Machine(SVM)method,and then reliability analysis was carried out using the Monte Carlo method.Finally,it was explained in detail how the key parameters affect the reliability of the hook engaging the arresting cable,and some meaningful conclusions were obtained.This analysis method and its results can provide a reference for the top-level parameter design of carrier-based aircraft and reliability research on the arresting systems.展开更多
During past strong earthquakes, highway bridges have sustained severe damage or even collapse due to excessive displacements and/or very large lateral forces. For commonly used isolation bearings with a pure friction ...During past strong earthquakes, highway bridges have sustained severe damage or even collapse due to excessive displacements and/or very large lateral forces. For commonly used isolation bearings with a pure friction sliding surface, seismic forces may be reduced but displacements are often unconstrained. In this paper, an alternative seismic bearing system, called the cable-sliding friction bearing system, is developed by integrating seismic isolation devices with displacement restrainers consisting of cables attached to the upper and lower plates of the bearing. Restoring forces are provided to limit the displacements of the sliding component. Design parameters including the length and stiffness of the cables, friction coefficient, strength of the shear bolt in a fixed-type bearing, and movements under earthquake excitations are discussed. Laboratory testing of a prototype bearing subjected to vertical loads and quasi-static cyclic lateral loads, and corresponding numerical finite element simulation analysis, were carried out. It is shown that the numerical simulation shows good agreement with the experimental force-displacement hysteretic response, indicating the viability of the new bearing system. In addition, practical application of this bearing system to a multi-span bridge in China and its design advantages are discussed.展开更多
A 3D finite element （FE） model for the Sutong cable-stayed bridge （SCB） is established based on ANSYS. The dynamic characteristics of the bridge are analyzed using a subspace iteration method. Based on recorded wi...A 3D finite element （FE） model for the Sutong cable-stayed bridge （SCB） is established based on ANSYS. The dynamic characteristics of the bridge are analyzed using a subspace iteration method. Based on recorded wind data, the measured spectra expression is presented using the nonlinear least-squares regression method. Turbulent winds at the bridge site are simulated based on the spectral representation method and the FFT technique. The influence of some key structural parameters and measures on the dynamic characteristics of the bridge are investigated. These parameters include dead load intensity, as well as vertical, lateral and torsional stiffness of the steel box girder. In addition, the influence of elastic stiffness of the connection device employed between the towers and the girder on the vibration mode of the steel box girder is investigated. The analysis shows that all of the vertical, lateral and torsional buffeting displacement responses reduce gradually as the dead load intensity increases. The dynamic characteristics and the structural buffeting displacement response of the SCB are only slightly affected by the vertical and torsional stiffness of the steel box girder, and the lateral and torsional buffeting displacement responses reduce gradually as the lateral stiffness increases. These results provide a reference for dynamic analysis and design of super-long-span cable-stayed bridges.展开更多
文摘In order to overcome the flaws of present domestic devices for detecting faulty wires such as low precision,low sensitivity and instability,a new instrument for detecting and processing the signal of flux leakage caused by bro-ken wires of coal mine-hoist cables is investigated. The principle of strong magnetic detection was adopted in the equipment. Wires were magnetized by a pre-magnetic head to reach magnetization saturation. Our special feature is that the number of flux-gates installed along the circle direction on the wall of sensors is twice as large as the number of strands in the wire cable. Neighboring components are connected in series and the interference on the surface of the wire cable,produced by leakage from the flux field of the wire strands,is efficiently filtered. The sampled signal se-quence produced by broken wires,which is characterized by a three-dimensional distribution of the flux-leakage field on the surface of the wire cable,can be dimensionally condensed and characteristically extracted. A model of a BP neu-ral network is built and the algorithm of the BP neural network is then used to identify the number of broken wires quantitatively. In our research,we used a 6×37+FC,Φ24 mm wire cable as our test object. Randomly several wires were artificially broken and damaged to different degrees. The experiments were carried out 100 times to obtain data for 100 groups from our samples. The data were then entered into the BP neural network and trained. The network was then used to identify a total 16 wires,broken at five different locations. The test data proves that our new device can enhance the precision in detecting broken and damaged wires.
基金co-supported by the Natural Science Foundation of Jiangsu Province, China (No. BK20220910)National Natural Science Foundation of China (No. 52202441)+2 种基金Fundamental Research Funds for the Central Universities, China (No. NT2022002)the National Defense Excellence Youth Science Fun of China (No. 2018-JCJQ-ZQ-053)A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘The carrier-based aircraft landing and arrest process is complex and nonlinear,and includes the coupling effect between the aircraft and arresting system.It has many uncertain factors,which lead to difficulty in the reliability analysis.To make the reliability analysis more accurate and effective,this paper presents some studies.Taking a certain type of carrier-based aircraft as the research object,a dynamic model of the landing and arrest cable was established,and the accuracy of the model was verified using laboratory test results.Based on the model,this paper shows how the key parameters,including the sinking velocity,pitch angle and horizontal velocity,affect the collision rebound performance of the arresting hook.After that,a limit state equation of the arresting hook system’s reliability was established.For the implicit limit state equation,a surrogate model of the reliability of the arresting hook was established using the Support Vector Machine(SVM)method,and then reliability analysis was carried out using the Monte Carlo method.Finally,it was explained in detail how the key parameters affect the reliability of the hook engaging the arresting cable,and some meaningful conclusions were obtained.This analysis method and its results can provide a reference for the top-level parameter design of carrier-based aircraft and reliability research on the arresting systems.
基金Ministry of Science and Technology of China Under Grant No. SLDRCE09-B-08Kwang-Hua Fund for College of Civil Engineering, Tongji Universitythe National Natural Science Foundation of China Under Grants No.50978194 and No.90915011
文摘During past strong earthquakes, highway bridges have sustained severe damage or even collapse due to excessive displacements and/or very large lateral forces. For commonly used isolation bearings with a pure friction sliding surface, seismic forces may be reduced but displacements are often unconstrained. In this paper, an alternative seismic bearing system, called the cable-sliding friction bearing system, is developed by integrating seismic isolation devices with displacement restrainers consisting of cables attached to the upper and lower plates of the bearing. Restoring forces are provided to limit the displacements of the sliding component. Design parameters including the length and stiffness of the cables, friction coefficient, strength of the shear bolt in a fixed-type bearing, and movements under earthquake excitations are discussed. Laboratory testing of a prototype bearing subjected to vertical loads and quasi-static cyclic lateral loads, and corresponding numerical finite element simulation analysis, were carried out. It is shown that the numerical simulation shows good agreement with the experimental force-displacement hysteretic response, indicating the viability of the new bearing system. In addition, practical application of this bearing system to a multi-span bridge in China and its design advantages are discussed.
基金The National Science Foundation of China under Grant No.51378111the Program for New Century Excellent Talents in University of Ministry of Education of China under Grant No.NCET-13-0128+2 种基金the Fok Ying-Tong Education Foundation for Young Teachersin the Higher Education Institutions of China under Grant No.142007the Fundamental Research Funds for the Central Universities under Grant No.2242012R30002the Open Fund of Jiangsu Key Laboratory of Environmental Impact and Structural Safety in Engineering under Grant No.JSKL2011YB02
文摘A 3D finite element （FE） model for the Sutong cable-stayed bridge （SCB） is established based on ANSYS. The dynamic characteristics of the bridge are analyzed using a subspace iteration method. Based on recorded wind data, the measured spectra expression is presented using the nonlinear least-squares regression method. Turbulent winds at the bridge site are simulated based on the spectral representation method and the FFT technique. The influence of some key structural parameters and measures on the dynamic characteristics of the bridge are investigated. These parameters include dead load intensity, as well as vertical, lateral and torsional stiffness of the steel box girder. In addition, the influence of elastic stiffness of the connection device employed between the towers and the girder on the vibration mode of the steel box girder is investigated. The analysis shows that all of the vertical, lateral and torsional buffeting displacement responses reduce gradually as the dead load intensity increases. The dynamic characteristics and the structural buffeting displacement response of the SCB are only slightly affected by the vertical and torsional stiffness of the steel box girder, and the lateral and torsional buffeting displacement responses reduce gradually as the lateral stiffness increases. These results provide a reference for dynamic analysis and design of super-long-span cable-stayed bridges.
文摘目的探讨Cable-Ready~?GTR装置治疗髋关节置换术后股骨假体周围骨折的可行性及疗效。方法 2012年5月至2013年12月起收治12例股骨假体周围骨折患者,均采用Cable-Ready~?GTR装置治疗。男7例,女5例,年龄62～78岁,平均70.2岁;10例为跌跤受伤,2例为车祸撞伤;假体周围骨折距初次髋关节置换手术的时间为6～120个月,平均16.5个月;非骨水泥型假体9例,骨水泥型假体3例;初次全髋置换术为3例,半髋关节置换术为9例;按照Vancouver分型标准,A型3例,B1型7例,B2型2例;观察切口大小、手术时间、出血量、引流量和并发症。手术前、后采用Harris评分系统进行功能评定。结果 12例患者术中出血250～550 m L,平均375.3 m L;手术时间为98～150 min,平均142.6 min。全部病例术后随访52～71个月,平均60.8个月。12例术后随访骨折临床愈合时间为3～8个月,平均为5.2个月。末次随访Harris平均得分为88.9分(75～92分),优5例,良4例,可3例。术后1例高龄患者发生心功能衰竭,经内科保守治疗病情缓解。无1例出现下肢深静脉血栓(DVT)。所有患者未发生骨折再次移位、螺钉松动、内固定断裂、感染等并发症。结论 Cable-Ready~?GTR装置治疗股骨假体周围骨折操作简便,内固定效果确切,是一种可供选择的较好的治疗方式。
