The digital twin(DT)includes real-time data analytics based on the actual product or manufacturing processing parameters.Data from digital twins can predict asset maintenance requirements ahead of time.This saves mone...The digital twin(DT)includes real-time data analytics based on the actual product or manufacturing processing parameters.Data from digital twins can predict asset maintenance requirements ahead of time.This saves money by decreasing operating expenses and asset downtime,which improves company efficiency.In this paper,a digital twin in braiding machinery based on IoT(DTBM-IoT)used to diagnose faults.When an imbalance fault occurs,the system gathers experimental data.After that,the information is sent into a digital win model of the rotor system to see whether it can quantify and locate imbalance for defect detection.It is possible to anticipate asset maintenance requirements with DT technology by IoT(Internet of Things)sensors,XR(X-Ray)capabilities,and AI-powered analytics.A DT model’s appropriate design and flexibility remain difficult because of the nonlinear dynamics and unpre-dictability inherent in the degrading process of equipment.The results indicate that the DT in braiding machinery developed allows for precise diagnostic and dynamic deterioration analysis.At least there is 37%growth in efficiency over conventional approaches.展开更多
A biodegradable nerve regeneration conduit has been developed by the regular braided technique on a spindle-braiding machine. The geometry property indexes of braided nerve conduit consist of pitch, density, wall thic...A biodegradable nerve regeneration conduit has been developed by the regular braided technique on a spindle-braiding machine. The geometry property indexes of braided nerve conduit consist of pitch, density, wall thickness and porosity etc. In this article, the influences of the braiding parameters i.e. the linear density of yarn, gear ratio and spindle number of the braiding machine on these geometry property indexes of nerve conduit were discussed from which the optimal braiding parameters were obtained.展开更多
The relationships between braiding parameters and properties of medical silk braided suture are investigated. Experimental results indicate that the main factors affecting the suture properties include the proportion ...The relationships between braiding parameters and properties of medical silk braided suture are investigated. Experimental results indicate that the main factors affecting the suture properties include the proportion of core silk and shell silk, braiding density and braiding tension. The results show that the braiding technology significantly influences the suture properties and the optimal braiding parameters were obtained by using the regression method.展开更多
The automobiles, aircraft, and lightweight industries continuously demand thin near-net-shape preforms just out-of-machine as close to the final shape. This study addresses the possibilities of 3D thin shell textile p...The automobiles, aircraft, and lightweight industries continuously demand thin near-net-shape preforms just out-of-machine as close to the final shape. This study addresses the possibilities of 3D thin shell textile preform as the solution of lightweight reinforcement in various applications. Investigation into the development of 3D thin shells has led to different manufacturing processes. However, 3D thin shell preforms are mostly made by weaving and knitting, but nonwoven, winding, and/or layup techniques have been reported for over a decade. Owing to the complex thin shell manufacturing processes, they are not similar to the conventional methods. The different 3D thin shell preforms can extend the opportunities for new applications in various technical fields. This study presents existing research gaps and a few potential issues to be solved regarding 3D thin shell preforms in the near future.展开更多
The automobiles, aircraft, and lightweight industries continuously demand thin near-net-shape preforms just out-of-machine as close to the final shape. This study addresses the possibilities of 3D thin shell textile p...The automobiles, aircraft, and lightweight industries continuously demand thin near-net-shape preforms just out-of-machine as close to the final shape. This study addresses the possibilities of 3D thin shell textile preform as the solution of lightweight reinforcement in various applications. Investigation into the development of 3D thin shells has led to different manufacturing processes. However, 3D thin shell preforms are mostly made by weaving and knitting, but nonwoven, winding, and/or layup techniques have been reported for over a decade. Owing to the complex thin shell manufacturing processes, they are not similar to the conventional methods. The different 3D thin shell preforms can extend the opportunities for new applications in various technical fields. This study presents existing research gaps and a few potential issues to be solved regarding 3D thin shell preforms in the near future.展开更多
Three-dimensional unmanned aerial vehicle(UAV)oblique photogrammetric data were used to infer mountainous gravel braided river lithofacies,lithofacies associations and architectural elements.Hierarchical architecture ...Three-dimensional unmanned aerial vehicle(UAV)oblique photogrammetric data were used to infer mountainous gravel braided river lithofacies,lithofacies associations and architectural elements.Hierarchical architecture and lithofacies associations with detailed lithofacies characterizations were comprehensively described to document the architectural model,architectural element scale and gravel particle scale.(1)Nine lithofacies(i.e.,Gmm,Gcm,Gcc,Gci,Gcl,Ss,Sm,Fsm and Fl)were identified and classified as gravel,sand and fine matrix deposits.These are typical depositional features of a mountainous dryland gravel-braided river.(2)Three architectural elements were identified,including channel(CH),gravel bar(GB)and overbank(OB).CH can be further divided into flow channel and abandoned channel,while GB consists of Central Gravel bar(CGB)and Margin Gravel bar(MGB).(3)The gravel bar is the key architectural element of the gravel braided river,with its geological attributes.The dimensions of GBs and their particles are various,but exhibit good relationships with each other.The grain size of GB decreases downstream,but the dimensions of GB do not.The bank erosion affects the GB dimensions,whereas channel incision and water flow velocity influence the grain size of GB.The conclusions can be applied to the dryland gravel braided river studies in tectonically active areas.展开更多
In order to study the micro genetic mechanism and main geological controlling factors of low resistivity reservoir in NgIII formation of X oilfield in Bohai sea in China, the clay mineral composition, irreducible wate...In order to study the micro genetic mechanism and main geological controlling factors of low resistivity reservoir in NgIII formation of X oilfield in Bohai sea in China, the clay mineral composition, irreducible water saturation, salinity and conductive minerals of low resistivity reservoir were studied by using the data of core, cast thin section and analysis, and compared with normal resistivity reservoir. At the same time, the control effect of sedimentary environment on low resistivity reservoir was discussed. The results show that the additional conductivity of high bound water content and high montmorillonite content in the reservoir together leads to the significant reduction of reservoir resistivity, which is the main microscopic cause of the formation of low resistance, and is mainly controlled by the sedimentary background such as paleoclimate and sedimentary cycle. During the deposition period of NgIII formation, the paleoclimate was dry and cold, and it was at the end of the water advance of the medium-term sedimentary cycle. The hydrodynamic force of the river channel was weak, the carrying capacity of the riverbed was weak, and the river channel swayed frequently, resulting in fine lithologic particle size, high shale content and complex pore structure of the reservoir, resulting in significant reduction of reservoir resistance. The research conclusion would have strong guiding significance for the development of low resistivity reservoirs in this area.展开更多
BACKGROUND: Poly (glycolide-co-L-lactide) (PGLA) braided regeneration conduits have been shown to be biocompatible for the repair of damaged nerve. Mechanical properties, such as radial compression and torsion, g...BACKGROUND: Poly (glycolide-co-L-lactide) (PGLA) braided regeneration conduits have been shown to be biocompatible for the repair of damaged nerve. Mechanical properties, such as radial compression and torsion, greatly influence nerve regeneration and functional recovery. OBJECTIVE: To observe the influence of conduit parameters and coating methods on torsion properties in an in vitro-degradation environment and at normal temperature. DESIGN, TIME AND SE'I-FING: An in vitro, comparative study using repeated measures was performed at the College of Textiles, Donghua University, China from January 2005 to December 2007. MATERIALS: PGLA fiber and yarn (Shanghai Bio-TianQing, China), as well as torsion property testing instrument (LaiZhou Electronic Instrument, China), were used in the present study. METHODS: A total of 16 types of conduits were constructed according to braiding structures (regular/triaxial), angles (50°/55°/60°/65°)nd coating methods (coated/uncoated). At normal temperature, torsion properties of all conduits were tested at a predefined constant angle of 90°. Coated and uncoated conduits, which were triaxial and 65°, were incubated in a 5% CO2 incubator at 37 ℃ to simulate an in vitro degradation environment, and then torsion properties were tested at 4, 7, 11, 14, 17, 21,24, and 28 days in culture. MAIN OUTCOME MEASURES: Maximal torsion strength and torsion strength-torsion angle curve of conduits at normal temperature, as well as torsion strength-torsion angle curve, loss of torsion strength, and change in maximal torsion strength in an in vitro degradation environment. RESULTS: At normal temperature, the torsion properties of the triaxial structure were superior to the regular structure. Coated conduits performed better than uncoated ones, and the larger braiding angles exhibited superior torsion properties (P 〈 0.05). In the in vitro degradation environment, with degradation time, torsion strength of uncoated conduits was deceased gradually and the loss of torsion strength was increased fast. Torsion strength of coated conduits was increased first and decreased afterwards; the loss of torsion strength was decreased slowly till 14 days; both became identical after 14 days (P 〉 0.05). CONCLUSION: Torsion properties of coated conduits with a triaxial structure and large braiding angle were superior to uncoated conduits with regular structures and small braiding angles.展开更多
3D braided composite technology has stimulated a great deal of interest in the world at large. But due to the three-dimensional nature of these kinds of composites, coupled with the shortcomings of currently-adopted e...3D braided composite technology has stimulated a great deal of interest in the world at large. But due to the three-dimensional nature of these kinds of composites, coupled with the shortcomings of currently-adopted experimental test methods, it is difficult to measure the internal parameters of this materials, hence causes it difficult to understand the material performance. A new method is introduced herein to measure the internal strain of braided composite materials using co-braided fiber optic sensors. Two kinds of fiber optic sensors are co-braided into 3D braided composites to measure internal strain. One of these is the Fabry-Parrot (F-P) fiber optic sensor; the other is the polarimetric fiber optic sensor. Experiments are conducted to measure internal strain under tension, bending and thermal environments in the 3D carbon fiber braided composite specimens, both locally and globally. Experimental results show that multiple fiber optic sensors can be braided into the 3D braided composites to measure the internal parameters, providing a more accurate measurement method and leading to a better understanding of these materials.展开更多
This study proposed a new yarn-like strain sensor on the basis of the braided skin-core rope,and investigated the effect of braiding structures on the sensing properties of sensors.The morphology and electromechanical...This study proposed a new yarn-like strain sensor on the basis of the braided skin-core rope,and investigated the effect of braiding structures on the sensing properties of sensors.The morphology and electromechanical properties of the strain sensor with different braiding structures were compared and evaluated.The results show that the sensing performance of the sensor from a braided skin-core rope depends on both the number of yarns in braiding and the metallized process of braided rope.Generally,the present stretchable skin-core rope-based sensor provides a basis for the formation of a highly sensitive sensing structure.展开更多
The channel of Bhagirathi River is the branches off from the Ganga at Nurpur (lower course of the Ganga). Bhagirathi River is one of the main rivers in Murshidabad district. Analyzing the image of the Bhagirathi River...The channel of Bhagirathi River is the branches off from the Ganga at Nurpur (lower course of the Ganga). Bhagirathi River is one of the main rivers in Murshidabad district. Analyzing the image of the Bhagirathi River in Murshidabad district through the year 1970, 1977, 1990, 2000 and 2006, it is found that significant changed has been occurred in souththern part of the river and less change is found in the middle part which is close to the Berhampore town. Toposheet of the year 1970 is also compared with the image data to observe the change. Water discharge, soil types and transportation of sediment is the major contributing factor of morphological changes like bar or shoal, ox-bow Lake, meander etc. Maximum erosion takes place at Dear Balagachi and after Baidyanathpur. A cut-off has take place at Baidyanathpur in 1984 [1]. It is found from the study that there is a possibility of natural meander cut-off at Dear Balagachi and near Majayampur. The traditional bank protection works, concrete walls, cemented stone and brick, play a significant role in the modification of the hydraulic aspect of the discharge values and in the interference in the water dynamics of erosive and depositional phenomena both upstream and downstream.展开更多
The aim of this paper is to investigate the longitudinal modulus of three dimensional full five directional (3Df5d) braided composite. First, the analytical model of the internal unit cell is established based on its ...The aim of this paper is to investigate the longitudinal modulus of three dimensional full five directional (3Df5d) braided composite. First, the analytical model of the internal unit cell is established based on its topological structure. Then, according to the intrinsic relation of different cells, the axial moduli of internal, surface and corner cells are systematically deduced, and the influence of corner-cell periodic discontinuity on the moduli is also analyzed. Finally, considering the actual shape of axial yarns after consolidation, the longitudinal moduli of the different cells are modified based on energy theory. The technology factor λ is also proposed in this modification. The results show that the axial mechanical properties of this material can be strongly designable. The straightness of the axial yarns greatly affects the longitudinal modulus. Technology factor λ is between 1 to 2, corresponding to the minimum and the maximum modulus, respectively.展开更多
Based on unit cell model, the 3D 4-directional braided composites can be simplified as unidirectional composites with different local axial coordinate system and the compliance matrix of unidirectional composites can ...Based on unit cell model, the 3D 4-directional braided composites can be simplified as unidirectional composites with different local axial coordinate system and the compliance matrix of unidirectional composites can be defined utilizing the bridge model. The total stiffness matrix of braided composites can be obtained by the volume average stiffness of unidirectional composites with different local axial coordinate system and the engineering elastic constants of braided composites were computed further. Based on the iso-strain assumption and the bridge model, the stress distribution of fiber bundle and matrix of different unidirectional composites can be determined and the tensile strength of 3D 4-directional braided composites was predicted by means of the Hoffman's failure criterion for the fiber bundle and Mises' failure criterion for the matrix.展开更多
Quantum computers are in hot-spot with the potential to handle more complex problems than classical computers can.Realizing the quantum computation requires the universal quantum gate set {T,H,CNOT} so as to perform a...Quantum computers are in hot-spot with the potential to handle more complex problems than classical computers can.Realizing the quantum computation requires the universal quantum gate set {T,H,CNOT} so as to perform any unitary transformation with arbitrary accuracy.Here we first briefly review the Majorana fermions and then propose the realization of arbitrary two-qubit quantum gates based on chiral Majorana fermions.Elementary cells consist of a quantum anomalous Hall insulator surrounded by a topological superconductor with electric gates and quantum-dot structures,which enable the braiding operation and the partial exchange operation.After defining a qubit by four chiral Majorana fermions,the singlequbit T and H quantum gates are realized via one partial exchange operation and three braiding operations,respectively.The entangled CNOT quantum gate is performed by braiding six chiral Majorana fermions.Besides,we design a powerful device with which arbitrary two-qubit quantum gates can be realized and take the quantum Fourier transform as an example to show that several quantum operations can be performed with this space-limited device.Thus,our proposal could inspire further utilization of mobile chiral Majorana edge states for faster quantum computation.展开更多
A thermoplastic based composite material is suitable for automobile and aerospace applications. The recyclability of thermoplastic and clean processing further enhance its use. The only limitation encountered in using...A thermoplastic based composite material is suitable for automobile and aerospace applications. The recyclability of thermoplastic and clean processing further enhance its use. The only limitation encountered in using this material is its high-melt viscosity. Various techniques have been developed to overcome this problem. Commingled materials are one of such methods adopted for making proper use of thermoplastic. A major problem observed during the use of a commingled material is its de-commingling, wherein, the uniform distribution of fiber and thermoplastic yam gets disturbed and affects the final quality of the composite. The effects of the braiding process on laminate quality were investigated. Flat plaques were produced by braiding the commingled yam, using a 48- carrier braiding machine. The braids (and control woven samples) were subsequently heated and consolidated in a nonisothermal compression molding operation. Prior to the manufacture of the 'best quality' plaques, a series of moldings were produced under different consolidation conditions, to study the dependence of properties on the process variables. This enabled a processing window to be established for each material and helped to separate the respective effects of yam handling, textile processing, and consolidation on laminate properties.展开更多
In this research, the secondary current theory is used in investigating the role of phase shift angle between the secondary current and the channel axis displacement in stability analysis of a river channel. To achiev...In this research, the secondary current theory is used in investigating the role of phase shift angle between the secondary current and the channel axis displacement in stability analysis of a river channel. To achieve this, a small-perturbation stability analysis is developed for investigation of the role of the secondary current accompanying channel curvature in the initiation and early development of meanders in open channels. The secondary currents are generating in planes perpendicular to the primary direction of motion. The secondary currents form a helical motion in which the water in the upper part of the river is driven outward, whereas the water near the bottom is driven inward in a bend. Force-momentum equations for longitudinal and transverse direction in open channel bends were utilized. Assuming that the transverse force contributed by the bed is negligible, the pressure force associated with the transverse surface inclination is balanced by the centripetal force. Existing equations of the transverse velocity profile were analyzed. Since the magnitude of the vertical velocity is negligible compared to the transverse velocity in secondary currents, this study concentrates on the transverse velocity which is the radial component of the secondary current. This formulation leads to a linear differential equation which is solved for its orthogonal components which give the rates of meander growth and downstream migration. It is shown that instability increases with decrease in phase shift angle. Transition from straight to meandering and then from meandering to braiding occurs when phase shift angle is reduced.展开更多
The effects of microstructure on quasi-static transverse loading behavior of 3D circular braided composite tubes were studied. Transverse loading tests were conducted. Transverse load-deflection curves were obtained t...The effects of microstructure on quasi-static transverse loading behavior of 3D circular braided composite tubes were studied. Transverse loading tests were conducted. Transverse load-deflection curves were obtained to analyze the effects of braiding parameters including the braiding angle, the wall thickness, and the diameter on the transverse loading of 3D circular braided composite tubes. Breaking loads, moduli and strengths had also been used to describe the transverse loading behaviors. The failure morphologies were shown to reveal damage mechanisms. From the results, the increase in braiding angle, wall thickness and diameter increases the ability of anti-deformation and breaking load of braided tubes. The breaking load of specimen with a braiding angle of 45° is about 1.68 times that of specimen with a braiding angle of 15°. The breaking load of specimen with 4 layers of yarns is about 2.15 times that of specimen with 2 layers of yarns. The breaking load of the tube with a diameter of 25.5 mm is about 2.39 times that of the tube with a diameter of 20.5 mm.展开更多
It is vital to choose a factual and reasonable micro-structural model of braided composites for improving the calculating precision of thermal property of 3-D braided composites by finite element method (FEM). On th...It is vital to choose a factual and reasonable micro-structural model of braided composites for improving the calculating precision of thermal property of 3-D braided composites by finite element method (FEM). On the basis of new microstructure model of braided composites proposed recently, the model of FEM calculation for thermal conductivity of 3-dimennsional and 4-directional braided composites is set up in this paper. The curves of coefficient of effective thermal conductivity versus fiber volume ratio and interior braiding angle are obtained. Furthermore, comparing the results of FEM with the available experimental data, the reasonability and veracity of calculation are confirmed at the same time.展开更多
基金supported by the Fujian Province Natural Science Foundation (Grant No.2019J01711)Fujian ProvinceMiddle-aged Teachers Project (Grant No.JAT210670)Fujian Province Educational Reform Project (Grant No.FBJG2020316).
文摘The digital twin(DT)includes real-time data analytics based on the actual product or manufacturing processing parameters.Data from digital twins can predict asset maintenance requirements ahead of time.This saves money by decreasing operating expenses and asset downtime,which improves company efficiency.In this paper,a digital twin in braiding machinery based on IoT(DTBM-IoT)used to diagnose faults.When an imbalance fault occurs,the system gathers experimental data.After that,the information is sent into a digital win model of the rotor system to see whether it can quantify and locate imbalance for defect detection.It is possible to anticipate asset maintenance requirements with DT technology by IoT(Internet of Things)sensors,XR(X-Ray)capabilities,and AI-powered analytics.A DT model’s appropriate design and flexibility remain difficult because of the nonlinear dynamics and unpre-dictability inherent in the degrading process of equipment.The results indicate that the DT in braiding machinery developed allows for precise diagnostic and dynamic deterioration analysis.At least there is 37%growth in efficiency over conventional approaches.
文摘A biodegradable nerve regeneration conduit has been developed by the regular braided technique on a spindle-braiding machine. The geometry property indexes of braided nerve conduit consist of pitch, density, wall thickness and porosity etc. In this article, the influences of the braiding parameters i.e. the linear density of yarn, gear ratio and spindle number of the braiding machine on these geometry property indexes of nerve conduit were discussed from which the optimal braiding parameters were obtained.
文摘The relationships between braiding parameters and properties of medical silk braided suture are investigated. Experimental results indicate that the main factors affecting the suture properties include the proportion of core silk and shell silk, braiding density and braiding tension. The results show that the braiding technology significantly influences the suture properties and the optimal braiding parameters were obtained by using the regression method.
文摘The automobiles, aircraft, and lightweight industries continuously demand thin near-net-shape preforms just out-of-machine as close to the final shape. This study addresses the possibilities of 3D thin shell textile preform as the solution of lightweight reinforcement in various applications. Investigation into the development of 3D thin shells has led to different manufacturing processes. However, 3D thin shell preforms are mostly made by weaving and knitting, but nonwoven, winding, and/or layup techniques have been reported for over a decade. Owing to the complex thin shell manufacturing processes, they are not similar to the conventional methods. The different 3D thin shell preforms can extend the opportunities for new applications in various technical fields. This study presents existing research gaps and a few potential issues to be solved regarding 3D thin shell preforms in the near future.
文摘The automobiles, aircraft, and lightweight industries continuously demand thin near-net-shape preforms just out-of-machine as close to the final shape. This study addresses the possibilities of 3D thin shell textile preform as the solution of lightweight reinforcement in various applications. Investigation into the development of 3D thin shells has led to different manufacturing processes. However, 3D thin shell preforms are mostly made by weaving and knitting, but nonwoven, winding, and/or layup techniques have been reported for over a decade. Owing to the complex thin shell manufacturing processes, they are not similar to the conventional methods. The different 3D thin shell preforms can extend the opportunities for new applications in various technical fields. This study presents existing research gaps and a few potential issues to be solved regarding 3D thin shell preforms in the near future.
基金supported by the National Science and Technology Major Project(Grant No.2017ZX05008-006004-002)the National Natural Science Foundation of China(Grant Nos.41502126 and 41902155)the Open Foundation of Top Disciplines in Yangtze University(Grant No.2019KFJJ0818022)。
文摘Three-dimensional unmanned aerial vehicle(UAV)oblique photogrammetric data were used to infer mountainous gravel braided river lithofacies,lithofacies associations and architectural elements.Hierarchical architecture and lithofacies associations with detailed lithofacies characterizations were comprehensively described to document the architectural model,architectural element scale and gravel particle scale.(1)Nine lithofacies(i.e.,Gmm,Gcm,Gcc,Gci,Gcl,Ss,Sm,Fsm and Fl)were identified and classified as gravel,sand and fine matrix deposits.These are typical depositional features of a mountainous dryland gravel-braided river.(2)Three architectural elements were identified,including channel(CH),gravel bar(GB)and overbank(OB).CH can be further divided into flow channel and abandoned channel,while GB consists of Central Gravel bar(CGB)and Margin Gravel bar(MGB).(3)The gravel bar is the key architectural element of the gravel braided river,with its geological attributes.The dimensions of GBs and their particles are various,but exhibit good relationships with each other.The grain size of GB decreases downstream,but the dimensions of GB do not.The bank erosion affects the GB dimensions,whereas channel incision and water flow velocity influence the grain size of GB.The conclusions can be applied to the dryland gravel braided river studies in tectonically active areas.
文摘In order to study the micro genetic mechanism and main geological controlling factors of low resistivity reservoir in NgIII formation of X oilfield in Bohai sea in China, the clay mineral composition, irreducible water saturation, salinity and conductive minerals of low resistivity reservoir were studied by using the data of core, cast thin section and analysis, and compared with normal resistivity reservoir. At the same time, the control effect of sedimentary environment on low resistivity reservoir was discussed. The results show that the additional conductivity of high bound water content and high montmorillonite content in the reservoir together leads to the significant reduction of reservoir resistivity, which is the main microscopic cause of the formation of low resistance, and is mainly controlled by the sedimentary background such as paleoclimate and sedimentary cycle. During the deposition period of NgIII formation, the paleoclimate was dry and cold, and it was at the end of the water advance of the medium-term sedimentary cycle. The hydrodynamic force of the river channel was weak, the carrying capacity of the riverbed was weak, and the river channel swayed frequently, resulting in fine lithologic particle size, high shale content and complex pore structure of the reservoir, resulting in significant reduction of reservoir resistance. The research conclusion would have strong guiding significance for the development of low resistivity reservoirs in this area.
文摘BACKGROUND: Poly (glycolide-co-L-lactide) (PGLA) braided regeneration conduits have been shown to be biocompatible for the repair of damaged nerve. Mechanical properties, such as radial compression and torsion, greatly influence nerve regeneration and functional recovery. OBJECTIVE: To observe the influence of conduit parameters and coating methods on torsion properties in an in vitro-degradation environment and at normal temperature. DESIGN, TIME AND SE'I-FING: An in vitro, comparative study using repeated measures was performed at the College of Textiles, Donghua University, China from January 2005 to December 2007. MATERIALS: PGLA fiber and yarn (Shanghai Bio-TianQing, China), as well as torsion property testing instrument (LaiZhou Electronic Instrument, China), were used in the present study. METHODS: A total of 16 types of conduits were constructed according to braiding structures (regular/triaxial), angles (50°/55°/60°/65°)nd coating methods (coated/uncoated). At normal temperature, torsion properties of all conduits were tested at a predefined constant angle of 90°. Coated and uncoated conduits, which were triaxial and 65°, were incubated in a 5% CO2 incubator at 37 ℃ to simulate an in vitro degradation environment, and then torsion properties were tested at 4, 7, 11, 14, 17, 21,24, and 28 days in culture. MAIN OUTCOME MEASURES: Maximal torsion strength and torsion strength-torsion angle curve of conduits at normal temperature, as well as torsion strength-torsion angle curve, loss of torsion strength, and change in maximal torsion strength in an in vitro degradation environment. RESULTS: At normal temperature, the torsion properties of the triaxial structure were superior to the regular structure. Coated conduits performed better than uncoated ones, and the larger braiding angles exhibited superior torsion properties (P 〈 0.05). In the in vitro degradation environment, with degradation time, torsion strength of uncoated conduits was deceased gradually and the loss of torsion strength was increased fast. Torsion strength of coated conduits was increased first and decreased afterwards; the loss of torsion strength was decreased slowly till 14 days; both became identical after 14 days (P 〉 0.05). CONCLUSION: Torsion properties of coated conduits with a triaxial structure and large braiding angle were superior to uncoated conduits with regular structures and small braiding angles.
基金The writers acknowledge the support of the National Natural Science Foundation of China(No:59905021)Aeronautic Science Foundation of China(01G52075)Outstanding Youth Founda tion of Jiangsu Province(No.BK2002416).
文摘3D braided composite technology has stimulated a great deal of interest in the world at large. But due to the three-dimensional nature of these kinds of composites, coupled with the shortcomings of currently-adopted experimental test methods, it is difficult to measure the internal parameters of this materials, hence causes it difficult to understand the material performance. A new method is introduced herein to measure the internal strain of braided composite materials using co-braided fiber optic sensors. Two kinds of fiber optic sensors are co-braided into 3D braided composites to measure internal strain. One of these is the Fabry-Parrot (F-P) fiber optic sensor; the other is the polarimetric fiber optic sensor. Experiments are conducted to measure internal strain under tension, bending and thermal environments in the 3D carbon fiber braided composite specimens, both locally and globally. Experimental results show that multiple fiber optic sensors can be braided into the 3D braided composites to measure the internal parameters, providing a more accurate measurement method and leading to a better understanding of these materials.
基金Biomedical Textile Material Science and Technology,China(111 Project)(No.B07024)
文摘This study proposed a new yarn-like strain sensor on the basis of the braided skin-core rope,and investigated the effect of braiding structures on the sensing properties of sensors.The morphology and electromechanical properties of the strain sensor with different braiding structures were compared and evaluated.The results show that the sensing performance of the sensor from a braided skin-core rope depends on both the number of yarns in braiding and the metallized process of braided rope.Generally,the present stretchable skin-core rope-based sensor provides a basis for the formation of a highly sensitive sensing structure.
文摘The channel of Bhagirathi River is the branches off from the Ganga at Nurpur (lower course of the Ganga). Bhagirathi River is one of the main rivers in Murshidabad district. Analyzing the image of the Bhagirathi River in Murshidabad district through the year 1970, 1977, 1990, 2000 and 2006, it is found that significant changed has been occurred in souththern part of the river and less change is found in the middle part which is close to the Berhampore town. Toposheet of the year 1970 is also compared with the image data to observe the change. Water discharge, soil types and transportation of sediment is the major contributing factor of morphological changes like bar or shoal, ox-bow Lake, meander etc. Maximum erosion takes place at Dear Balagachi and after Baidyanathpur. A cut-off has take place at Baidyanathpur in 1984 [1]. It is found from the study that there is a possibility of natural meander cut-off at Dear Balagachi and near Majayampur. The traditional bank protection works, concrete walls, cemented stone and brick, play a significant role in the modification of the hydraulic aspect of the discharge values and in the interference in the water dynamics of erosive and depositional phenomena both upstream and downstream.
基金Supported by the National High Technology Research and Development Program of China(2012AA112201)
文摘The aim of this paper is to investigate the longitudinal modulus of three dimensional full five directional (3Df5d) braided composite. First, the analytical model of the internal unit cell is established based on its topological structure. Then, according to the intrinsic relation of different cells, the axial moduli of internal, surface and corner cells are systematically deduced, and the influence of corner-cell periodic discontinuity on the moduli is also analyzed. Finally, considering the actual shape of axial yarns after consolidation, the longitudinal moduli of the different cells are modified based on energy theory. The technology factor λ is also proposed in this modification. The results show that the axial mechanical properties of this material can be strongly designable. The straightness of the axial yarns greatly affects the longitudinal modulus. Technology factor λ is between 1 to 2, corresponding to the minimum and the maximum modulus, respectively.
基金Project supported by the Aeronautics Science Foundatioh of China (No.04B51045)the Common Construction Project of Education Committee of Beijing (No.XK10006052)
文摘Based on unit cell model, the 3D 4-directional braided composites can be simplified as unidirectional composites with different local axial coordinate system and the compliance matrix of unidirectional composites can be defined utilizing the bridge model. The total stiffness matrix of braided composites can be obtained by the volume average stiffness of unidirectional composites with different local axial coordinate system and the engineering elastic constants of braided composites were computed further. Based on the iso-strain assumption and the bridge model, the stress distribution of fiber bundle and matrix of different unidirectional composites can be determined and the tensile strength of 3D 4-directional braided composites was predicted by means of the Hoffman's failure criterion for the fiber bundle and Mises' failure criterion for the matrix.
基金Project supported by the National Key R&D Program of China(Grant No.2017YFA0303301)the National Natural Science Foundation of China(Grant No.11921005)+1 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB28000000)Beijing Municipal Science&Technology Commission,China(Grant No.Z191100007219013)。
文摘Quantum computers are in hot-spot with the potential to handle more complex problems than classical computers can.Realizing the quantum computation requires the universal quantum gate set {T,H,CNOT} so as to perform any unitary transformation with arbitrary accuracy.Here we first briefly review the Majorana fermions and then propose the realization of arbitrary two-qubit quantum gates based on chiral Majorana fermions.Elementary cells consist of a quantum anomalous Hall insulator surrounded by a topological superconductor with electric gates and quantum-dot structures,which enable the braiding operation and the partial exchange operation.After defining a qubit by four chiral Majorana fermions,the singlequbit T and H quantum gates are realized via one partial exchange operation and three braiding operations,respectively.The entangled CNOT quantum gate is performed by braiding six chiral Majorana fermions.Besides,we design a powerful device with which arbitrary two-qubit quantum gates can be realized and take the quantum Fourier transform as an example to show that several quantum operations can be performed with this space-limited device.Thus,our proposal could inspire further utilization of mobile chiral Majorana edge states for faster quantum computation.
文摘A thermoplastic based composite material is suitable for automobile and aerospace applications. The recyclability of thermoplastic and clean processing further enhance its use. The only limitation encountered in using this material is its high-melt viscosity. Various techniques have been developed to overcome this problem. Commingled materials are one of such methods adopted for making proper use of thermoplastic. A major problem observed during the use of a commingled material is its de-commingling, wherein, the uniform distribution of fiber and thermoplastic yam gets disturbed and affects the final quality of the composite. The effects of the braiding process on laminate quality were investigated. Flat plaques were produced by braiding the commingled yam, using a 48- carrier braiding machine. The braids (and control woven samples) were subsequently heated and consolidated in a nonisothermal compression molding operation. Prior to the manufacture of the 'best quality' plaques, a series of moldings were produced under different consolidation conditions, to study the dependence of properties on the process variables. This enabled a processing window to be established for each material and helped to separate the respective effects of yam handling, textile processing, and consolidation on laminate properties.
文摘In this research, the secondary current theory is used in investigating the role of phase shift angle between the secondary current and the channel axis displacement in stability analysis of a river channel. To achieve this, a small-perturbation stability analysis is developed for investigation of the role of the secondary current accompanying channel curvature in the initiation and early development of meanders in open channels. The secondary currents are generating in planes perpendicular to the primary direction of motion. The secondary currents form a helical motion in which the water in the upper part of the river is driven outward, whereas the water near the bottom is driven inward in a bend. Force-momentum equations for longitudinal and transverse direction in open channel bends were utilized. Assuming that the transverse force contributed by the bed is negligible, the pressure force associated with the transverse surface inclination is balanced by the centripetal force. Existing equations of the transverse velocity profile were analyzed. Since the magnitude of the vertical velocity is negligible compared to the transverse velocity in secondary currents, this study concentrates on the transverse velocity which is the radial component of the secondary current. This formulation leads to a linear differential equation which is solved for its orthogonal components which give the rates of meander growth and downstream migration. It is shown that instability increases with decrease in phase shift angle. Transition from straight to meandering and then from meandering to braiding occurs when phase shift angle is reduced.
文摘The effects of microstructure on quasi-static transverse loading behavior of 3D circular braided composite tubes were studied. Transverse loading tests were conducted. Transverse load-deflection curves were obtained to analyze the effects of braiding parameters including the braiding angle, the wall thickness, and the diameter on the transverse loading of 3D circular braided composite tubes. Breaking loads, moduli and strengths had also been used to describe the transverse loading behaviors. The failure morphologies were shown to reveal damage mechanisms. From the results, the increase in braiding angle, wall thickness and diameter increases the ability of anti-deformation and breaking load of braided tubes. The breaking load of specimen with a braiding angle of 45° is about 1.68 times that of specimen with a braiding angle of 15°. The breaking load of specimen with 4 layers of yarns is about 2.15 times that of specimen with 2 layers of yarns. The breaking load of the tube with a diameter of 25.5 mm is about 2.39 times that of the tube with a diameter of 20.5 mm.
基金Aeronautical Science Foundation of China (04B51045)
文摘It is vital to choose a factual and reasonable micro-structural model of braided composites for improving the calculating precision of thermal property of 3-D braided composites by finite element method (FEM). On the basis of new microstructure model of braided composites proposed recently, the model of FEM calculation for thermal conductivity of 3-dimennsional and 4-directional braided composites is set up in this paper. The curves of coefficient of effective thermal conductivity versus fiber volume ratio and interior braiding angle are obtained. Furthermore, comparing the results of FEM with the available experimental data, the reasonability and veracity of calculation are confirmed at the same time.