The end windings of generators are excited to vibrations due to electromagnetic forces which can cause severe damage （especially in case of resonance） and noise. To avoid this, it is important to predict the natural...The end windings of generators are excited to vibrations due to electromagnetic forces which can cause severe damage （especially in case of resonance） and noise. To avoid this, it is important to predict the natural frequencies and modes of the end windings with finite elements during the design process. Hence, a material model of the complete stator bar is necessary. This paper shows the development of such a material model. The composite structure of a stator bar is quite complex and makes it impossible to provide a quick calculation of the eigenvalues. That is the reason for using a suitable, homogeneously, geometry based solid model. Special attention was paid to the experimental determination of the material characteristics of the orthotropic composite space brackets. The numerical results have been evaluated against measurements. Eigenvalues, Young＇s modulus, and shear modulus have been experimentally investigated.展开更多
We have developed a simple, productive, and ettectlve poly（cllmetnysltoxane） rranu fer method to fabricate highly conductive Pd nanowires following DNA scaffolds on various substrates, based on ethanolreduction at l...We have developed a simple, productive, and ettectlve poly（cllmetnysltoxane） rranu fer method to fabricate highly conductive Pd nanowires following DNA scaffolds on various substrates, based on ethanolreduction at low temperature. Pd nanoparticles were selectively deposited and confined onto the DNA templates on a PDMS sheet to form Pd nanowires and then the nanowires were transferred to other various substrates with a low occurrence of par asitic nanoparticles. The structure, morphology and the conductance of Pd nanowires were characterized with transmission electron microscopy, field emission scanning electron mi croscopy, and electrical transport measurement, respectively. Moreover, the growth process of the Pd nanowires was investigated by varying the incubation time and reaction temper ature. The present strategy provides a new method to fabricate extremely dense, highly conductive, and well aligned Pd nanowires on various substrates, which make it promising for building nanosensors and nanoelectronic devices.展开更多
In present paper application of Endurance Time Analysis （ETA） method in nonlinear seismic assessment of steel concentrically braced frames is studied. In this method structure is subjected to a set of predesigned in...In present paper application of Endurance Time Analysis （ETA） method in nonlinear seismic assessment of steel concentrically braced frames is studied. In this method structure is subjected to a set of predesigned increasing acceleration functions and various responses of the structure are recorded during synthetic seismic excitation. The averages of maximum values for various responses in Nonlinear Time-History Analyses （NTHA） extracted from real ground motions are expected to be close to those obtained from ETA up to equivalent target time. For this purpose a set of 9, 11, 13 and 15 stories steel frames were designed and plastic hinge method was selected as source of nonlinearity in all cases. Responses were compared based on interstory drift ratio and story shear in two methods and results show satisfactory consistency between two methods. Finally, it was concluded that the ETA method can be used as alternative method in nonlinear seismic analysis of concentrically braced steel frames.展开更多
PLLA and PGLA sutures for decomposable esophageal stent were investigated in phosphate buffer solution （PBS） （pH=7.4） at 37 ℃ for a period of 8 weeks. In vitro degradation was studied by determining the change of...PLLA and PGLA sutures for decomposable esophageal stent were investigated in phosphate buffer solution （PBS） （pH=7.4） at 37 ℃ for a period of 8 weeks. In vitro degradation was studied by determining the change of weight loss, pH value, intrinsic viscosity, tensile strength, orientation degree, degree of crystallinity, melting point and surface morphology of the suture samples. The results showed that all properties of PLLA sutures had no obvious changes, however, the properties of PGLA sutures all changed significantly. The pH value, intrinsic viscosity, tensile strength, orientation degree and degree of crystallinity decreased gradually, and the weight loss of PGLA sutures increased with the degradation time. At 6th week, tensile strength of PGLA sutures nearly reached O, and weight loss approached to 70% at 8th week. The results of DSC showed that melting point of crystalline region of PGLA sutures substantially remained unchanged and melting heat enthalpy increased gradually during in vitro degradation, and the new ordered regions appeared in the amorphous area. The results of SEM showed that surface coating of PGLA sutures spalled initially, and then the sutures occured transverse rupture. Therefore, PGLA suture is suitable to prepare decomposable esophageal stent to expand benign esophageal stenosis or stricture, but stent prepared by PLLA suture is not appropriate for the treatment of benign esophageal stenosis because it is decomposed for more than 2 months.展开更多
Traumatic spinal cord injury(SCI) is a major challenge in the clinic. In this study, we sought to examine the synergistic effects of linear ordered collagen scaffold(LOCS) and human placenta-derived mesenchymal stem c...Traumatic spinal cord injury(SCI) is a major challenge in the clinic. In this study, we sought to examine the synergistic effects of linear ordered collagen scaffold(LOCS) and human placenta-derived mesenchymal stem cells(hPMSCs) when transplanted into completely transected beagle dogs. After 36 weeks observation, we found that LOCS+hPMSCs implants promoted better hindlimb locomotor recovery than was observed in the non-treatment(control) group and LOCS group. Histological analysis showed that the regenerated tissue after treatment was well integrated with the host tissue, and dramatically reduced the volume of cystic and chondroitin sulfate proteoglycans(CSPGs) expression. Furthermore, the LOCS+hPMSCs group also showed more neuron-specific βIII-tubulin(Tuj-1)-and NeuN-positive neurons in the lesion area, as well as axonal regeneration, remyelination and synapse formation in the lesion site. Additionally, dogs in the LOCS+hPMSCs group experienced enhanced sprouting of both ascending(CGRP-positive) sensory fibers and descending(5-HT-and TH-positive) motor fibers at the lesion area. All these data together suggested that the combined treatment had beneficial effects on neuronal regeneration and functional improvement in a canine complete transection model. Therefore, LOCS+hPMSCs implantation holds a great promise for bridging the nerve defect and may be clinically useful in the near future.展开更多
文摘The end windings of generators are excited to vibrations due to electromagnetic forces which can cause severe damage （especially in case of resonance） and noise. To avoid this, it is important to predict the natural frequencies and modes of the end windings with finite elements during the design process. Hence, a material model of the complete stator bar is necessary. This paper shows the development of such a material model. The composite structure of a stator bar is quite complex and makes it impossible to provide a quick calculation of the eigenvalues. That is the reason for using a suitable, homogeneously, geometry based solid model. Special attention was paid to the experimental determination of the material characteristics of the orthotropic composite space brackets. The numerical results have been evaluated against measurements. Eigenvalues, Young＇s modulus, and shear modulus have been experimentally investigated.
文摘We have developed a simple, productive, and ettectlve poly（cllmetnysltoxane） rranu fer method to fabricate highly conductive Pd nanowires following DNA scaffolds on various substrates, based on ethanolreduction at low temperature. Pd nanoparticles were selectively deposited and confined onto the DNA templates on a PDMS sheet to form Pd nanowires and then the nanowires were transferred to other various substrates with a low occurrence of par asitic nanoparticles. The structure, morphology and the conductance of Pd nanowires were characterized with transmission electron microscopy, field emission scanning electron mi croscopy, and electrical transport measurement, respectively. Moreover, the growth process of the Pd nanowires was investigated by varying the incubation time and reaction temper ature. The present strategy provides a new method to fabricate extremely dense, highly conductive, and well aligned Pd nanowires on various substrates, which make it promising for building nanosensors and nanoelectronic devices.
文摘In present paper application of Endurance Time Analysis （ETA） method in nonlinear seismic assessment of steel concentrically braced frames is studied. In this method structure is subjected to a set of predesigned increasing acceleration functions and various responses of the structure are recorded during synthetic seismic excitation. The averages of maximum values for various responses in Nonlinear Time-History Analyses （NTHA） extracted from real ground motions are expected to be close to those obtained from ETA up to equivalent target time. For this purpose a set of 9, 11, 13 and 15 stories steel frames were designed and plastic hinge method was selected as source of nonlinearity in all cases. Responses were compared based on interstory drift ratio and story shear in two methods and results show satisfactory consistency between two methods. Finally, it was concluded that the ETA method can be used as alternative method in nonlinear seismic analysis of concentrically braced steel frames.
基金Shandong Provincial Science and Technology Development Program grant number: 2009GG10002077
文摘PLLA and PGLA sutures for decomposable esophageal stent were investigated in phosphate buffer solution （PBS） （pH=7.4） at 37 ℃ for a period of 8 weeks. In vitro degradation was studied by determining the change of weight loss, pH value, intrinsic viscosity, tensile strength, orientation degree, degree of crystallinity, melting point and surface morphology of the suture samples. The results showed that all properties of PLLA sutures had no obvious changes, however, the properties of PGLA sutures all changed significantly. The pH value, intrinsic viscosity, tensile strength, orientation degree and degree of crystallinity decreased gradually, and the weight loss of PGLA sutures increased with the degradation time. At 6th week, tensile strength of PGLA sutures nearly reached O, and weight loss approached to 70% at 8th week. The results of DSC showed that melting point of crystalline region of PGLA sutures substantially remained unchanged and melting heat enthalpy increased gradually during in vitro degradation, and the new ordered regions appeared in the amorphous area. The results of SEM showed that surface coating of PGLA sutures spalled initially, and then the sutures occured transverse rupture. Therefore, PGLA suture is suitable to prepare decomposable esophageal stent to expand benign esophageal stenosis or stricture, but stent prepared by PLLA suture is not appropriate for the treatment of benign esophageal stenosis because it is decomposed for more than 2 months.
基金supported by the "Strategic Priority Research Program of the Chinese Academy of Sciences" (XDA01030000)the key Research Program of the Chinese Academy of Sciences (ZDRW-ZS-2016-2)+3 种基金the National Natural Science Foundation of China (81572131, 81571213)the Natural Science Foundation of Jiangsu Province (BL2012004, BK20151210)the Priority Academic Program Development of Jiangsu Higher Education Institutionsthe key Research and Development Program of Ministry of Science and Technology (2016YFC1101500)
文摘Traumatic spinal cord injury(SCI) is a major challenge in the clinic. In this study, we sought to examine the synergistic effects of linear ordered collagen scaffold(LOCS) and human placenta-derived mesenchymal stem cells(hPMSCs) when transplanted into completely transected beagle dogs. After 36 weeks observation, we found that LOCS+hPMSCs implants promoted better hindlimb locomotor recovery than was observed in the non-treatment(control) group and LOCS group. Histological analysis showed that the regenerated tissue after treatment was well integrated with the host tissue, and dramatically reduced the volume of cystic and chondroitin sulfate proteoglycans(CSPGs) expression. Furthermore, the LOCS+hPMSCs group also showed more neuron-specific βIII-tubulin(Tuj-1)-and NeuN-positive neurons in the lesion area, as well as axonal regeneration, remyelination and synapse formation in the lesion site. Additionally, dogs in the LOCS+hPMSCs group experienced enhanced sprouting of both ascending(CGRP-positive) sensory fibers and descending(5-HT-and TH-positive) motor fibers at the lesion area. All these data together suggested that the combined treatment had beneficial effects on neuronal regeneration and functional improvement in a canine complete transection model. Therefore, LOCS+hPMSCs implantation holds a great promise for bridging the nerve defect and may be clinically useful in the near future.
