We report a unique case of lumbar disc herniation, in particular, with end-plate and surrounded by extensive ossification, mimicking a tumor with calcification. A 69-year-old female suffered from right buttock and leg...We report a unique case of lumbar disc herniation, in particular, with end-plate and surrounded by extensive ossification, mimicking a tumor with calcification. A 69-year-old female suffered from right buttock and leg pain. Computed tomography (CT) showed an intracanalar mass with calcification or ossification, which most likely originated from the vertebral body at the L1/2 level epidural space. On a T1-weighted gadolinium magnetic resonance image, the capsule of the mass was enhanced and not only the content of the mass but also that of the L2 vertebral body were partially and slightly enhanced. The final pathological diagnosis was disc herniation with end-plate fracture and secondary ossification. A combination of these pathological conditions as accompanied by both end-plate fractures and extensive secondary ossifications has not been previously reported. This rare pathological condition needs to be recognized as a differential diagnosis.展开更多
This study involves the development of an analytical model for understanding the behavior of the extended, stiffened end-plate moment connections with eight high strength bolts. Modeling of the connection as an assemb...This study involves the development of an analytical model for understanding the behavior of the extended, stiffened end-plate moment connections with eight high strength bolts. Modeling of the connection as an assemblage of finite elements (FE) used for load deformation analysis, with material, and contact nonlinearities are developed. Results from the FE mathematical model are verified with results from the ANSYS computer program as well as with the test results. Sensitivity and feasibility studies are carried out. Significant geometry and force related variables are introduced;and by varying the geometric variables of the connections within a practical range, a matrix of test cases is obtained. Maximum end-plate separation, maximum bending stresses in the end-plate, and the forces from the connection bolts for these test cases are obtained. From the FE analysis, a database is produced to collect results for the artificial neural network analysis. Finally, salient features of the optimized Artificial Neural Network (ANN) via Genetic Algorithm (GA) analysis are introduced and implemented with the aim of predicting the overall behavior of the connection.展开更多
Based on full scale model of 1-beam and end-plate welding assembly with medium plate, welding temperature field and residual stress were simulated, infrared thermometers were employed to measure the real-time temperat...Based on full scale model of 1-beam and end-plate welding assembly with medium plate, welding temperature field and residual stress were simulated, infrared thermometers were employed to measure the real-time temperature Jbr verification purposes. Results show that the measured thermal cycle curves match well with the simulation result. Simulation results of welding residual stress indicate that the values of longitudinal and transverse stress on the upper surface of the plate are higher than the normal stress; higher tensile stresses exist at the end of the web weld toes and in the central area of the flange weld toes. The dangerous zones are located at the central areas of weld toes of the flange welds and near weld toes of the web welds.展开更多
In beam-to-column joint with bolted end-plate connection,the structural details of column flange reinforced by backing plate and column web panel reinforced by supplementary plate are analyzed.The joint is divided int...In beam-to-column joint with bolted end-plate connection,the structural details of column flange reinforced by backing plate and column web panel reinforced by supplementary plate are analyzed.The joint is divided into some basic components,and the initial stiffness of each component is obtained.Especially,the initial stiffness of reinforced components is drawn by theoretical model and finite element analysis.The initial stiffness of reinforced joint can be obtained by assembling the initial stiffness of each component.The design moment resistance of column flange reinforced by backing plate is deduced based on yield line method,and the design moment resistances of other components are deduced based on present codes.The design moment resistance of the reinforced joint is then determined by the minimum of the design moment resistances of all components.By comparison with the results of finite element calculation,it is verified that the method to calculate the initial stiffness of reinforced joint is accurate enough to be used to estimate the rigid behavior of the joint and to make parametric study.展开更多
针对某电厂QF R-135-2型135 M W空冷发电机在长期运行中出现的定子绕组绝缘磨损、槽楔松动和铁心过热等故障,开展了定子结构优化改造方案研究。通过定子线圈结构改进、定子铁心发热点修复、定子槽楔结构改进和定子绕组端部支撑结构改进...针对某电厂QF R-135-2型135 M W空冷发电机在长期运行中出现的定子绕组绝缘磨损、槽楔松动和铁心过热等故障,开展了定子结构优化改造方案研究。通过定子线圈结构改进、定子铁心发热点修复、定子槽楔结构改进和定子绕组端部支撑结构改进,对发电机进行了改造。改造后,机组满负荷运行时的定子层间温度平均下降约10℃,端部模态频率有效避开了工频和倍频共振区间,相关电气试验结果均合格。由此表明,改造后发电机发热量下降,显著提升了机组的运行安全性和可靠性。展开更多
During the development of the nervous system,there is an overproduction of neurons and synapses.Hebbian competition between neighboring nerve endings and synapses performing different activity levels leads to their el...During the development of the nervous system,there is an overproduction of neurons and synapses.Hebbian competition between neighboring nerve endings and synapses performing different activity levels leads to their elimination or strengthening.We have extensively studied the involvement of the brain-derived neurotrophic factor-Tropomyosin-related kinase B receptor neurotrophic retrograde pathway,at the neuromuscular junction,in the axonal development and synapse elimination process versus the synapse consolidation.The purpose of this review is to describe the neurotrophic influence on developmental synapse elimination,in relation to other molecular pathways that we and others have found to regulate this process.In particular,we summarize our published results based on transmitter release analysis and axonal counts to show the different involvement of the presynaptic acetylcholine muscarinic autoreceptors,coupled to downstream serine-threonine protein kinases A and C(PKA and PKC)and voltage-gated calcium channels,at different nerve endings in developmental competition.The dynamic changes that occur simultaneously in several nerve terminals and synapses converge across a postsynaptic site,influence each other,and require careful studies to individualize the mechanisms of specific endings.We describe an activity-dependent balance(related to the extent of transmitter release)between the presynaptic muscarinic subtypes and the neurotrophin-mediated TrkB/p75NTR pathways that can influence the timing and fate of the competitive interactions between the different axon terminals.The downstream displacement of the PKA/PKC activity ratio to lower values,both in competing nerve terminals and at postsynaptic sites,plays a relevant role in controlling the elimination of supernumerary synapses.Finally,calcium entry through L-and P/Q-subtypes of voltage-gated calcium channels(both channels are present,together with the N-type channel in developing nerve terminals)contributes to reduce transmitter release and promote withdrawal of the most unfavorable nerve terminals during elimination(the weakest in acetylcholine release and those that have already become silent).The main findings contribute to a better understanding of punishment-rewarding interactions between nerve endings during development.Identifying the molecular targets and signaling pathways that allow synapse consolidation or withdrawal of synapses in different situations is important for potential therapies in neurodegenerative diseases.展开更多
文摘We report a unique case of lumbar disc herniation, in particular, with end-plate and surrounded by extensive ossification, mimicking a tumor with calcification. A 69-year-old female suffered from right buttock and leg pain. Computed tomography (CT) showed an intracanalar mass with calcification or ossification, which most likely originated from the vertebral body at the L1/2 level epidural space. On a T1-weighted gadolinium magnetic resonance image, the capsule of the mass was enhanced and not only the content of the mass but also that of the L2 vertebral body were partially and slightly enhanced. The final pathological diagnosis was disc herniation with end-plate fracture and secondary ossification. A combination of these pathological conditions as accompanied by both end-plate fractures and extensive secondary ossifications has not been previously reported. This rare pathological condition needs to be recognized as a differential diagnosis.
文摘This study involves the development of an analytical model for understanding the behavior of the extended, stiffened end-plate moment connections with eight high strength bolts. Modeling of the connection as an assemblage of finite elements (FE) used for load deformation analysis, with material, and contact nonlinearities are developed. Results from the FE mathematical model are verified with results from the ANSYS computer program as well as with the test results. Sensitivity and feasibility studies are carried out. Significant geometry and force related variables are introduced;and by varying the geometric variables of the connections within a practical range, a matrix of test cases is obtained. Maximum end-plate separation, maximum bending stresses in the end-plate, and the forces from the connection bolts for these test cases are obtained. From the FE analysis, a database is produced to collect results for the artificial neural network analysis. Finally, salient features of the optimized Artificial Neural Network (ANN) via Genetic Algorithm (GA) analysis are introduced and implemented with the aim of predicting the overall behavior of the connection.
基金This research was supported by the National Natural Science Foundation of China （51171093）.
文摘Based on full scale model of 1-beam and end-plate welding assembly with medium plate, welding temperature field and residual stress were simulated, infrared thermometers were employed to measure the real-time temperature Jbr verification purposes. Results show that the measured thermal cycle curves match well with the simulation result. Simulation results of welding residual stress indicate that the values of longitudinal and transverse stress on the upper surface of the plate are higher than the normal stress; higher tensile stresses exist at the end of the web weld toes and in the central area of the flange weld toes. The dangerous zones are located at the central areas of weld toes of the flange welds and near weld toes of the web welds.
文摘In beam-to-column joint with bolted end-plate connection,the structural details of column flange reinforced by backing plate and column web panel reinforced by supplementary plate are analyzed.The joint is divided into some basic components,and the initial stiffness of each component is obtained.Especially,the initial stiffness of reinforced components is drawn by theoretical model and finite element analysis.The initial stiffness of reinforced joint can be obtained by assembling the initial stiffness of each component.The design moment resistance of column flange reinforced by backing plate is deduced based on yield line method,and the design moment resistances of other components are deduced based on present codes.The design moment resistance of the reinforced joint is then determined by the minimum of the design moment resistances of all components.By comparison with the results of finite element calculation,it is verified that the method to calculate the initial stiffness of reinforced joint is accurate enough to be used to estimate the rigid behavior of the joint and to make parametric study.
文摘针对某电厂QF R-135-2型135 M W空冷发电机在长期运行中出现的定子绕组绝缘磨损、槽楔松动和铁心过热等故障,开展了定子结构优化改造方案研究。通过定子线圈结构改进、定子铁心发热点修复、定子槽楔结构改进和定子绕组端部支撑结构改进,对发电机进行了改造。改造后,机组满负荷运行时的定子层间温度平均下降约10℃,端部模态频率有效避开了工频和倍频共振区间,相关电气试验结果均合格。由此表明,改造后发电机发热量下降,显著提升了机组的运行安全性和可靠性。
基金supported by Catalan Government,Nos.2014SGR344(to JT),2017SGR704(to JT),2021SGR01214(to MAL)MCIN/AEI/10.13039/501100011033/by“ERDF A way of making Europe,”Nos.SAF2015-67143(to JT),PID2019-106332GB-I00(to JT and MAL)and PID2022-141252NB-I00(to MAL).
文摘During the development of the nervous system,there is an overproduction of neurons and synapses.Hebbian competition between neighboring nerve endings and synapses performing different activity levels leads to their elimination or strengthening.We have extensively studied the involvement of the brain-derived neurotrophic factor-Tropomyosin-related kinase B receptor neurotrophic retrograde pathway,at the neuromuscular junction,in the axonal development and synapse elimination process versus the synapse consolidation.The purpose of this review is to describe the neurotrophic influence on developmental synapse elimination,in relation to other molecular pathways that we and others have found to regulate this process.In particular,we summarize our published results based on transmitter release analysis and axonal counts to show the different involvement of the presynaptic acetylcholine muscarinic autoreceptors,coupled to downstream serine-threonine protein kinases A and C(PKA and PKC)and voltage-gated calcium channels,at different nerve endings in developmental competition.The dynamic changes that occur simultaneously in several nerve terminals and synapses converge across a postsynaptic site,influence each other,and require careful studies to individualize the mechanisms of specific endings.We describe an activity-dependent balance(related to the extent of transmitter release)between the presynaptic muscarinic subtypes and the neurotrophin-mediated TrkB/p75NTR pathways that can influence the timing and fate of the competitive interactions between the different axon terminals.The downstream displacement of the PKA/PKC activity ratio to lower values,both in competing nerve terminals and at postsynaptic sites,plays a relevant role in controlling the elimination of supernumerary synapses.Finally,calcium entry through L-and P/Q-subtypes of voltage-gated calcium channels(both channels are present,together with the N-type channel in developing nerve terminals)contributes to reduce transmitter release and promote withdrawal of the most unfavorable nerve terminals during elimination(the weakest in acetylcholine release and those that have already become silent).The main findings contribute to a better understanding of punishment-rewarding interactions between nerve endings during development.Identifying the molecular targets and signaling pathways that allow synapse consolidation or withdrawal of synapses in different situations is important for potential therapies in neurodegenerative diseases.
