Background Inside out transobturator vaginal tape （TVT-O） and tension-free vaginal tape （TVT） are predominant surgical treatments for female stress urinary incontinence. This meta-analysis evaluated the complicati...Background Inside out transobturator vaginal tape （TVT-O） and tension-free vaginal tape （TVT） are predominant surgical treatments for female stress urinary incontinence. This meta-analysis evaluated the complications and cure rates of TVT-O versus TVT. Methods A comprehensive literature search was conducted according to the Cochrane Collaboration methodology to identify randomized controlled clinical trials with no language restriction. Two authors independently assessed papers for eligibility and methodological quality. Estimates were measured by relative risk with 95% confidence intervals. Outcome measures were objective cure, subjective cure and complications. Quality rating for each outcome of the meta-analysis and recommendations were performed by the Grading of Recommendations Assessment, Development, and Evaluation （GRADE） system. Results Twenty randomized controlled trials met the inclusion criteria, and a pooled estimate of effectiveness and complications was made. Relative risks with 95% confidence intervals for pooled effects under the fixed effects model were： 0.20 （0.09-0.45）, for bladder injury, 0.37 （0.16-0.86） for hematoma, and 2.35 （1.57-3.51） for postoperative pain, suggesting an 80% risk reduction of bladder injury, 63% risk reduction of hematoma, and a 1.35% risk elevation for postoperative pain with TVT-O. There was no significant difference between complications of urinary tract infection 1.14 （0.78-1.65）, lower urinary tract symptoms 1.60 （0.67-3.79）, recatheterization 0.93 （0.59-1.44）, and tape erosion 0.90 （0.48-1.67）, total objective cure rate 1.06 （0.39-2.84） and for the subjective cure rate 0.98 （0.93-1.04）. The quality rating for each outcome and recommendations was high for objective cure, bladder injury, hematoma, lower urinary tract symptoms, and tape erosion and moderate for subjective cure, pain, and urinary tract infection. Conclusions TVT-O is associated with a reduced risk of bladder injury and hematoma and an elevated risk of 展开更多
This paper presents analytical and numerical models to predict the behavior of unbonded flexible risers under torsion.The analytical model takes local bending and torsion of tensile armor wires into consideration,and ...This paper presents analytical and numerical models to predict the behavior of unbonded flexible risers under torsion.The analytical model takes local bending and torsion of tensile armor wires into consideration,and equilibrium equations of forces and displacements of layers are deduced.The numerical model includes lay angle,cross-sectional profiles of carcass,pressure armor layer and contact between layers.Abaqus/Explicit quasi-static simulation and mass scaling are adopted to avoid convergence problem and excessive computation time caused by geometric and contact nonlinearities.Results show that local bending and torsion of helical strips may have great influence on torsional stiffness,but stress related to bending and torsion is negligible;the presentation of anti-friction tapes may have great influence both on torsional stiffness and stress;hysteresis of torsion-twist relationship under cyclic loading is obtained by numerical model,which cannot be predicted by analytical model because of the ignorance of friction between layers.展开更多
Heteroconchia,a widespread and abundant aquatic invertebrate,is an important clade of bivalve mollusks.The relationship between the three branches of Heteroconchia,Palaeoheterodonta,Archiheterodonta,and Euheterodonta ...Heteroconchia,a widespread and abundant aquatic invertebrate,is an important clade of bivalve mollusks.The relationship between the three branches of Heteroconchia,Palaeoheterodonta,Archiheterodonta,and Euheterodonta has become a main controversy in molecular studies of the relationships between bivalves.In the present study,we assembled the complete mitochondrial genomes of Tapes dorsatus(Veneridae)and Cardita variegata(Carditidae)using high-throughput sequencing.C.variegata is the first mitochondrial genome belonging to the family Carditidae to be reported.We used 12 protein coding genes(excluding atp8)from the complete mitochondrial genomes of 146 species to recover the internal relationships of Heteroconchia.Our results support the traditional view of early branching of Palaeoheterodonta and the recovery of the monophyly of Palaeoheterodonta,Anomalodesmata,Imparidentia.Rearrangement analysis show that gene arrangement within Venerida was highly variable.Time-calibrated phylogenetic studies based on a relaxed molecular clock model suggested that Veneridae originated approximately 337.62 million years ago(Ma)and split into two major clades,whereas Carditidae originated approximately 510.09 Ma.Our results provide evidence of the internal relationships of Heteroconchia.展开更多
The elastoplastic mechanical behaviour of an epoxy-impregnated REBCO pancake winding under cryogenics and high magnetic field is investigated in the frame of finite element(FE)modelling.A two-dimensional axisymmetric ...The elastoplastic mechanical behaviour of an epoxy-impregnated REBCO pancake winding under cryogenics and high magnetic field is investigated in the frame of finite element(FE)modelling.A two-dimensional axisymmetric electromagnetic-thermal-structure multi-physics multi-layer FE model with main layers of the coated conductor and insulation materials is developed.The radial stress and hoop stress on each constituent layer induced by thermal mismatch stress during cooling are investigated.The mechanical behaviour of each constituent material is also analysed by considering the thermal mismatch stress and electromagnetic force under 20 T background field.The results show that discrete stresses appear in all the constituent materials indicating that the multi-layer winding model containing the main constituent materials is necessary for the accurate stress analysis in an epoxy-impregnated REBCO winding.The stress of each constituent material induced by thermal mismatch during cooling process are too high to be ignored in the subsequent electromagnetic structure analysis.The mechanical-magnetic coupling analyses show that the stresses of all the constituent materials increase with the transport current.The plastic failure mainly induced by hoop stress successively occurs on copper stabilizer and Hastelloy substrate of the innermost turn,and the plastic region propagates from the inner turns to the outer turns with the increase of transport current.The failure of the superconducting layer occurs before the yield in Hastelloy due to the direct action of Lorentz force on the superconducting layers.The transverse tensile stress increases with the increasing transport current,indicating that the risk of transverse delamination failure increases with the increase of transport current.The mechanical failure modes including delamination within the conductor,plastic deformation in substrate and crack in superconducting layer should be seriously considered.展开更多
To reduce the production cost of Bi-2223 superconducting tapes, Bi-2223/Ag/Ni tapes were fabricated by the powder-in-tube process. The effect of heat treatment on the microstructure and critical current of the Bi-2223...To reduce the production cost of Bi-2223 superconducting tapes, Bi-2223/Ag/Ni tapes were fabricated by the powder-in-tube process. The effect of heat treatment on the microstructure and critical current of the Bi-2223/Ag/Ni tapes were studied. The phase compositions of the samples were characterized using XRD. The microstructure was observed using SEM. Experimental results indicate that higher temperature is more conducive to the formation of Bi-2223 phase at an atmosphere of 8.5% O 2 . After the two-step heat treatment, the critical current of samples is about 67.5 A.展开更多
Conductive adhesive tape is one kind of electromagnetic interference(EMI)shielding materials for electronic packaging.However,the inferior conductivity of the pressure-sensitive adhesive(PSA)layer results in serious e...Conductive adhesive tape is one kind of electromagnetic interference(EMI)shielding materials for electronic packaging.However,the inferior conductivity of the pressure-sensitive adhesive(PSA)layer results in serious electromagnetic leakage at the conjunctions between the conductive tapes and target objects.Adding conductive fillers is a traditional method for highly conductive adhesive tapes.However,the content of conductive fillers is needed to reach the percolation threshold,which is usually as high as tens of percent.High-content fillers result in significant loss of adhesive property and high fabrication cost.Herein,we introduce a rational architecture of conductive microsphere monolayer(CMM)in the PSA layer.The CMM connects the top and bottom surfaces of the PSA layer and improves its conductivity in the z-direction.Importantly,low contents of conductive microspheres(≤5%(mass fraction,w))can achieve the target of conductivity improvement,but not result in the serious loss of the adhesive property.Therefore,the strategy of CMMs can balance the tradeoff between the conductivity and the adhesive property of conductive PSA tapes.Finally,we demonstrate the superior EMI shielding performance of as-made conductive adhesive tapes,indicating their potential applications as the advanced EMI shielding materials in the electronic packaging.展开更多
The second-generation high-temperature superconductor tape(2G-HTS,also known as a coated conductor)based on REBaCuO(REBa_(2)Cu_(3)O_(7-δ))exhibits high current density and potential cost-effective price/performance,c...The second-generation high-temperature superconductor tape(2G-HTS,also known as a coated conductor)based on REBaCuO(REBa_(2)Cu_(3)O_(7-δ))exhibits high current density and potential cost-effective price/performance,compared with conventional superconducting materials.Using commercial 2G-HTS tapes,more than a dozen cable vendors had been manufacturing REBCO cables,such as the latest kilometer-class REBCO cable,which was incorporated into a civil grid on December 2021,as part of the recordbreaking 35-kV-voltage superconductor cable demonstration project in downtown Shanghai.This paper describes the development of HTS-coated conductors,then outlines the various technological routes for their preparation,reviews the artificial flux pinning of coated conductors,and finally summarizes the technological breakthroughs,the latest research advances,and provides an outlook on their application prospects.展开更多
RE‐Ba‐Cu‐O(REBCO,where RE=Y,Gd,Sm,and other rare earth elements)coated conductor(CC)tapes are promising for applications in high‐energy physics and high‐field science owing to their significant advantages such as...RE‐Ba‐Cu‐O(REBCO,where RE=Y,Gd,Sm,and other rare earth elements)coated conductor(CC)tapes are promising for applications in high‐energy physics and high‐field science owing to their significant advantages such as high critical magnetic field,high current density,and the ability to achieve superconductivity at liquid nitrogen temperatures.Nevertheless,the mechanical and superconducting performances of these CC tapes are significantly affected by interface failures,such as interfacial delamination and coating fractures,which arise from the complex interplay of mechanical stress induced by magnet processing,thermal mismatch stress during cooling,electromagnetic stress under high magnetic fields,and thermal stress during quenching.This study comprehensively reviews the interface properties and failure behavior of REBCO CC tapes.First,the research progress in characterizing the intricate interface properties of REBCO CC is systematically reviewed.Furthermore,the interface failure behavior in extreme multifield environments was analyzed and summarized.Subsequently,this study outlines optimization strategies to mitigate interface failure risks in REBCO superconducting magnet structures.Finally,we address the current challenges and future perspectives on interface issues in REBCO CC tapes.By addressing these challenges,this study offers valuable insights for advancing the development and practical implementation of superconducting technologies in diverse applications.展开更多
The natural convection heat transfer of a 60% sucrose solution in a vertical converging-diverging tube(CD) with regularly-spaced twisted tapes(RSTT) has been investigated numerically and experimentally. The effects of...The natural convection heat transfer of a 60% sucrose solution in a vertical converging-diverging tube(CD) with regularly-spaced twisted tapes(RSTT) has been investigated numerically and experimentally. The effects of wall temperature and number of RSTT on the Nusselt number were studied in detail. The distributions of velocity and temperature in the 60% sucrose solution were studied and the simulated results of CD with RSTT were compared with those of the smooth tube. The influence of Rayleigh number and RSTT on the Nusselt number was conducted experimentally. The results indicate that the Nusselt number of the 60% sucrose solution obviously increased with the number of RSTT but increased inconspicuously with 2 and more twisted tapes. The simulation shows that the distance for achieving an optimal heat transfer performance is 46 times the diameter of the tube. The mechanism of the natural convection heat transfer enhancement of the 60% sucrose solution in relationship with the CD and the RSTT was analyzed, and the change of average tangential velocity with the axial distance was presented to demonstrate that the enhancement of heat transfer was realized mainly because of the increase in tangential velocity.展开更多
The results of the preliminary development of the HTS conductor based on the VS-type design and parallel stacks for the central solenoid of the compact thermonuclear reactor TRT are presented. One of the main problems...The results of the preliminary development of the HTS conductor based on the VS-type design and parallel stacks for the central solenoid of the compact thermonuclear reactor TRT are presented. One of the main problems that need to be solved for the successful implementation of such projects is the creation of high-current high-temperature superconducting (HTS) conductors for Toroidal Field coils (TF) and Central Solenoid (CS) sections. The conductor must have a high engineering current density of at least 90 A/mm<sup>2</sup>. The induction of the magnetic field in the central solenoid reaches 14 T, which leads to the occurrence of large mechanical stresses due to the influence of Lorentz forces. Like many large magnets, CS has a lot of stored energy. For the safe withdrawal of stored energy from the magnet, it requires the inclusion of elements in the conductor that provide an acceptable level of electrical voltage and heating of the conductor insulation. Thus, a sufficient amount of stabilizing and reinforcing materials should be placed in the conductor. In addition, the “cable-in-conduit” type of conductor must have channels for pumping the refrigerant. Two fundamentally different versions of the conductor based on radially arranged REBCO tapes and on the basis of pre-assembled tape packages are considered. Based on the analysis of the magnetic field distribution in the conductor by finite element method, the design characteristics of the proposed conductors under various operating modes of the electromagnetic system (EMS) of the tokamak TRT was evaluated. The results of the evaluation of the current carrying capacity of the conductor and the estimation of energy losses in a changing magnetic field in comparison with known methods are also presented.展开更多
We present a new test method for the accurate measurement of the transverse tensile interfacial strength of rare-earth barium copper oxide(REBCO)-coated conductor(CC)tapes to overcome heavy scattering of data tested u...We present a new test method for the accurate measurement of the transverse tensile interfacial strength of rare-earth barium copper oxide(REBCO)-coated conductor(CC)tapes to overcome heavy scattering of data tested using regular test methods.A new composite structure specimen is designed and constructed by solidifying a standard epoxy resin tensile specimen using the three-dimensional printing technology,where a short REBCO CC tape is embedded.The feasibility of the proposed test method is numerically validated through finite element(FE)calculations.Experimental results show that the valid delaminated strength is 2.19-2.51 MPa with the maximum relative error of 7.3%,indicating the elimination of significant scattering in the tested data.By analysing the morphology of the delaminated interfaces and energy-dispersive spectroscopy results,it is discovered that delamination primarily occurs at the interface between the REBCO superconducting layer and the buffer layer and that a small portion of the REBCO and buffer layers peels off.Further error analysis based on the FE method indicates that the tape is more likely to delaminate because of initial defects,whereas the adhesion at the edges of the CC tape due to the redundancy of the epoxy resin increases the resistance of the CC tape to delamination,resulting in a higher testing value than the real one.展开更多
We prepared a series of MgB2 bulk samples under different temperatures, holding time and increasing rates in temperature by the solid state reaction. The thermodynamic behavior and phase formation in the Mg-B system w...We prepared a series of MgB2 bulk samples under different temperatures, holding time and increasing rates in temperature by the solid state reaction. The thermodynamic behavior and phase formation in the Mg-B system were studied by using DTA, XRD and SEM. The results indicate that the formation of the MgB2 phase is very fast and the high increasing rate in temperature is necessary to obtain high quality MgB2. In addition, the effects of the Zr-doping in Mg1-xZrxB2 bulk samples fabricated by the solid state reaction at ambient pressure on phase compositions, microstructure and flux pinning behavior were investigated by using XRD, SQUID magnetometer, SEM and TEM. Critical current density Jc can be significantly enhanced by the Zr-doping and the best data are achieved in Mg0.9Zr0.1B2. For this sample, Jc values are remarkably improved to 1. 83 × 106 A/cm2 in self-field and 5. 51 × 105 A/cm2in 1T at 20K. Also, high quality MgB2/Ta/Cu wires and tapes with and without Ti-doping, MgB2/Fe wires and 18 filament MgB2/NbZr/Cu tapes were fabricated by the powder-in-tube (PIT) method at ambient pressure. The phase compositions, microstructure features and flux pinning properties were studied. The results suggest that Fe is the best metal for these sheaths. MgB2/Fe wires exhibit very high Jc at high temperatures and high fields. Jc values reach as high as 1.43 × 105A/cm2(4. 2K, 4T) and 3.72 × 104 A/cm2(15K, 4T).展开更多
Bi system tapes were prepared using the powder in tube method. The tapes were processed to their final thickness by repeated rolling and pressing and by a combination of rolling and pressing with intermediate heat tre...Bi system tapes were prepared using the powder in tube method. The tapes were processed to their final thickness by repeated rolling and pressing and by a combination of rolling and pressing with intermediate heat treatment. The different processing techniques greatly affected the critical current density J c of the tapes because the homogeneity of the ceramic core and the propensity for crack formation within the tapes mainly depended on the deformation process.展开更多
Silver-clad （Bi,Pb）2Sr2Ca2Cu3O10＋x long wires produced by powder-in-tube techniques, which have been recognized as the first generation of the High Temperature Superconducting （HTS） wires, are expected to apply w...Silver-clad （Bi,Pb）2Sr2Ca2Cu3O10＋x long wires produced by powder-in-tube techniques, which have been recognized as the first generation of the High Temperature Superconducting （HTS） wires, are expected to apply widely especially in strong current applications. In this work, the processing, characterization and application of the silver-clad （Bi,Pb）2Sr2Ca2Cu3Ol0＋x HTS wires are summarized. The HTS wires are fabricated using the combination of powder-in-tube technique, and the resulting wires are fully characterized by the means of chemical analyses, microstructural observation, electrical and magnetic measurements. The relationship among fabrication parameters, chemical and microstructural characteristics, and electrical and magnetic properties are analyzed. Applications of the HTS wires have also been introduced according to their strong current behaviors with various prototype devices made.展开更多
Three kinds of silver-sheathed Bi(2223) oxide superconductor tapes (single-core tape, Ag-powder-added tape and multifilamentary type) were successfully prepared, namely, through the powder-in-tube method. The critical...Three kinds of silver-sheathed Bi(2223) oxide superconductor tapes (single-core tape, Ag-powder-added tape and multifilamentary type) were successfully prepared, namely, through the powder-in-tube method. The critical current density (Jc), the Jc-B characteristics, microstructures and the relation between Jc and strain of three kinds of tapes were evaluated and compared. The maximum Jc of three kinds of tapes at 77.7 K in zero magnetic field are 28700 A/cm2 for single-core tape, 20800 A/cm2 for Ag-powder-added tape, 11700 A/cm2 for multifilamentary tape. Single-core tapes exhibit high Jc values and good Jc-B characteristics.展开更多
文摘Background Inside out transobturator vaginal tape （TVT-O） and tension-free vaginal tape （TVT） are predominant surgical treatments for female stress urinary incontinence. This meta-analysis evaluated the complications and cure rates of TVT-O versus TVT. Methods A comprehensive literature search was conducted according to the Cochrane Collaboration methodology to identify randomized controlled clinical trials with no language restriction. Two authors independently assessed papers for eligibility and methodological quality. Estimates were measured by relative risk with 95% confidence intervals. Outcome measures were objective cure, subjective cure and complications. Quality rating for each outcome of the meta-analysis and recommendations were performed by the Grading of Recommendations Assessment, Development, and Evaluation （GRADE） system. Results Twenty randomized controlled trials met the inclusion criteria, and a pooled estimate of effectiveness and complications was made. Relative risks with 95% confidence intervals for pooled effects under the fixed effects model were： 0.20 （0.09-0.45）, for bladder injury, 0.37 （0.16-0.86） for hematoma, and 2.35 （1.57-3.51） for postoperative pain, suggesting an 80% risk reduction of bladder injury, 63% risk reduction of hematoma, and a 1.35% risk elevation for postoperative pain with TVT-O. There was no significant difference between complications of urinary tract infection 1.14 （0.78-1.65）, lower urinary tract symptoms 1.60 （0.67-3.79）, recatheterization 0.93 （0.59-1.44）, and tape erosion 0.90 （0.48-1.67）, total objective cure rate 1.06 （0.39-2.84） and for the subjective cure rate 0.98 （0.93-1.04）. The quality rating for each outcome and recommendations was high for objective cure, bladder injury, hematoma, lower urinary tract symptoms, and tape erosion and moderate for subjective cure, pain, and urinary tract infection. Conclusions TVT-O is associated with a reduced risk of bladder injury and hematoma and an elevated risk of
基金financially supported by the National Natural Science Foundation of China(Grant Nos.51579146 and 51490674)Shanghai Municipal Natural Science Foundation(Grant No.15ZR1423500)Shanghai Rising-Star Program(Grant No.16QA1402300)
文摘This paper presents analytical and numerical models to predict the behavior of unbonded flexible risers under torsion.The analytical model takes local bending and torsion of tensile armor wires into consideration,and equilibrium equations of forces and displacements of layers are deduced.The numerical model includes lay angle,cross-sectional profiles of carcass,pressure armor layer and contact between layers.Abaqus/Explicit quasi-static simulation and mass scaling are adopted to avoid convergence problem and excessive computation time caused by geometric and contact nonlinearities.Results show that local bending and torsion of helical strips may have great influence on torsional stiffness,but stress related to bending and torsion is negligible;the presentation of anti-friction tapes may have great influence both on torsional stiffness and stress;hysteresis of torsion-twist relationship under cyclic loading is obtained by numerical model,which cannot be predicted by analytical model because of the ignorance of friction between layers.
基金Supported by the Research and Development Program of Shandong Province,China(Major Science and Technology Innovation Project)(No.2021CXGC011306)the MNR Key Laboratory of Eco-Environmental Science and Technology,China(No.MEEST-2021-05)+2 种基金the Natural Science Foundation of Shandong Province(No.ZR2020MD002)the Doctoral Science Research Foundation of Yantai University(Nos.SM15B01,SM19B70,SM19B28)the“Double-Hundred Action”of Yantai City(No.2320004-SM20RC02)。
文摘Heteroconchia,a widespread and abundant aquatic invertebrate,is an important clade of bivalve mollusks.The relationship between the three branches of Heteroconchia,Palaeoheterodonta,Archiheterodonta,and Euheterodonta has become a main controversy in molecular studies of the relationships between bivalves.In the present study,we assembled the complete mitochondrial genomes of Tapes dorsatus(Veneridae)and Cardita variegata(Carditidae)using high-throughput sequencing.C.variegata is the first mitochondrial genome belonging to the family Carditidae to be reported.We used 12 protein coding genes(excluding atp8)from the complete mitochondrial genomes of 146 species to recover the internal relationships of Heteroconchia.Our results support the traditional view of early branching of Palaeoheterodonta and the recovery of the monophyly of Palaeoheterodonta,Anomalodesmata,Imparidentia.Rearrangement analysis show that gene arrangement within Venerida was highly variable.Time-calibrated phylogenetic studies based on a relaxed molecular clock model suggested that Veneridae originated approximately 337.62 million years ago(Ma)and split into two major clades,whereas Carditidae originated approximately 510.09 Ma.Our results provide evidence of the internal relationships of Heteroconchia.
基金the National Natural Science Foundation of China(11902129,11932008)the China Postdoctoral Science Foundation(2019T120963)the Fundamental Research Funds for the Central Universities(lzujbky-2020-pd03,lzujbky-2021-kb06).
文摘The elastoplastic mechanical behaviour of an epoxy-impregnated REBCO pancake winding under cryogenics and high magnetic field is investigated in the frame of finite element(FE)modelling.A two-dimensional axisymmetric electromagnetic-thermal-structure multi-physics multi-layer FE model with main layers of the coated conductor and insulation materials is developed.The radial stress and hoop stress on each constituent layer induced by thermal mismatch stress during cooling are investigated.The mechanical behaviour of each constituent material is also analysed by considering the thermal mismatch stress and electromagnetic force under 20 T background field.The results show that discrete stresses appear in all the constituent materials indicating that the multi-layer winding model containing the main constituent materials is necessary for the accurate stress analysis in an epoxy-impregnated REBCO winding.The stress of each constituent material induced by thermal mismatch during cooling process are too high to be ignored in the subsequent electromagnetic structure analysis.The mechanical-magnetic coupling analyses show that the stresses of all the constituent materials increase with the transport current.The plastic failure mainly induced by hoop stress successively occurs on copper stabilizer and Hastelloy substrate of the innermost turn,and the plastic region propagates from the inner turns to the outer turns with the increase of transport current.The failure of the superconducting layer occurs before the yield in Hastelloy due to the direct action of Lorentz force on the superconducting layers.The transverse tensile stress increases with the increasing transport current,indicating that the risk of transverse delamination failure increases with the increase of transport current.The mechanical failure modes including delamination within the conductor,plastic deformation in substrate and crack in superconducting layer should be seriously considered.
基金financially supported by the National High Technology Research and Development Program(863program)(No.2009AA03Z202)the Fundamental Research Funds for the Central Universities(No.N100423006and No.N110823001)
文摘To reduce the production cost of Bi-2223 superconducting tapes, Bi-2223/Ag/Ni tapes were fabricated by the powder-in-tube process. The effect of heat treatment on the microstructure and critical current of the Bi-2223/Ag/Ni tapes were studied. The phase compositions of the samples were characterized using XRD. The microstructure was observed using SEM. Experimental results indicate that higher temperature is more conducive to the formation of Bi-2223 phase at an atmosphere of 8.5% O 2 . After the two-step heat treatment, the critical current of samples is about 67.5 A.
基金the financial support from the National Natural Science Foundation of China(Grant No.62074154)Shenzhen Science and Technology Program(Grant Nos.JSGG20210802153000002,JCYJ20210324102208023).
文摘Conductive adhesive tape is one kind of electromagnetic interference(EMI)shielding materials for electronic packaging.However,the inferior conductivity of the pressure-sensitive adhesive(PSA)layer results in serious electromagnetic leakage at the conjunctions between the conductive tapes and target objects.Adding conductive fillers is a traditional method for highly conductive adhesive tapes.However,the content of conductive fillers is needed to reach the percolation threshold,which is usually as high as tens of percent.High-content fillers result in significant loss of adhesive property and high fabrication cost.Herein,we introduce a rational architecture of conductive microsphere monolayer(CMM)in the PSA layer.The CMM connects the top and bottom surfaces of the PSA layer and improves its conductivity in the z-direction.Importantly,low contents of conductive microspheres(≤5%(mass fraction,w))can achieve the target of conductivity improvement,but not result in the serious loss of the adhesive property.Therefore,the strategy of CMMs can balance the tradeoff between the conductivity and the adhesive property of conductive PSA tapes.Finally,we demonstrate the superior EMI shielding performance of as-made conductive adhesive tapes,indicating their potential applications as the advanced EMI shielding materials in the electronic packaging.
基金supported in part by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB25000000)by the National Natural Science Foundation(Grant No.52172271)by the National Key R&D Program of China(Grant No.2022YFE03150200)。
文摘The second-generation high-temperature superconductor tape(2G-HTS,also known as a coated conductor)based on REBaCuO(REBa_(2)Cu_(3)O_(7-δ))exhibits high current density and potential cost-effective price/performance,compared with conventional superconducting materials.Using commercial 2G-HTS tapes,more than a dozen cable vendors had been manufacturing REBCO cables,such as the latest kilometer-class REBCO cable,which was incorporated into a civil grid on December 2021,as part of the recordbreaking 35-kV-voltage superconductor cable demonstration project in downtown Shanghai.This paper describes the development of HTS-coated conductors,then outlines the various technological routes for their preparation,reviews the artificial flux pinning of coated conductors,and finally summarizes the technological breakthroughs,the latest research advances,and provides an outlook on their application prospects.
基金supported by the National Natural Science Foundation of China(12272156 and 11932008)Shanghai Superconductor Technology Co.,Ltd–Lanzhou University Superconducting Materials and Mechanics Open Foundation for Industry-University-Research.
文摘RE‐Ba‐Cu‐O(REBCO,where RE=Y,Gd,Sm,and other rare earth elements)coated conductor(CC)tapes are promising for applications in high‐energy physics and high‐field science owing to their significant advantages such as high critical magnetic field,high current density,and the ability to achieve superconductivity at liquid nitrogen temperatures.Nevertheless,the mechanical and superconducting performances of these CC tapes are significantly affected by interface failures,such as interfacial delamination and coating fractures,which arise from the complex interplay of mechanical stress induced by magnet processing,thermal mismatch stress during cooling,electromagnetic stress under high magnetic fields,and thermal stress during quenching.This study comprehensively reviews the interface properties and failure behavior of REBCO CC tapes.First,the research progress in characterizing the intricate interface properties of REBCO CC is systematically reviewed.Furthermore,the interface failure behavior in extreme multifield environments was analyzed and summarized.Subsequently,this study outlines optimization strategies to mitigate interface failure risks in REBCO superconducting magnet structures.Finally,we address the current challenges and future perspectives on interface issues in REBCO CC tapes.By addressing these challenges,this study offers valuable insights for advancing the development and practical implementation of superconducting technologies in diverse applications.
基金the Major Science and Technology Projects of Guangdong Province (No. 2011A080804012)
文摘The natural convection heat transfer of a 60% sucrose solution in a vertical converging-diverging tube(CD) with regularly-spaced twisted tapes(RSTT) has been investigated numerically and experimentally. The effects of wall temperature and number of RSTT on the Nusselt number were studied in detail. The distributions of velocity and temperature in the 60% sucrose solution were studied and the simulated results of CD with RSTT were compared with those of the smooth tube. The influence of Rayleigh number and RSTT on the Nusselt number was conducted experimentally. The results indicate that the Nusselt number of the 60% sucrose solution obviously increased with the number of RSTT but increased inconspicuously with 2 and more twisted tapes. The simulation shows that the distance for achieving an optimal heat transfer performance is 46 times the diameter of the tube. The mechanism of the natural convection heat transfer enhancement of the 60% sucrose solution in relationship with the CD and the RSTT was analyzed, and the change of average tangential velocity with the axial distance was presented to demonstrate that the enhancement of heat transfer was realized mainly because of the increase in tangential velocity.
文摘The results of the preliminary development of the HTS conductor based on the VS-type design and parallel stacks for the central solenoid of the compact thermonuclear reactor TRT are presented. One of the main problems that need to be solved for the successful implementation of such projects is the creation of high-current high-temperature superconducting (HTS) conductors for Toroidal Field coils (TF) and Central Solenoid (CS) sections. The conductor must have a high engineering current density of at least 90 A/mm<sup>2</sup>. The induction of the magnetic field in the central solenoid reaches 14 T, which leads to the occurrence of large mechanical stresses due to the influence of Lorentz forces. Like many large magnets, CS has a lot of stored energy. For the safe withdrawal of stored energy from the magnet, it requires the inclusion of elements in the conductor that provide an acceptable level of electrical voltage and heating of the conductor insulation. Thus, a sufficient amount of stabilizing and reinforcing materials should be placed in the conductor. In addition, the “cable-in-conduit” type of conductor must have channels for pumping the refrigerant. Two fundamentally different versions of the conductor based on radially arranged REBCO tapes and on the basis of pre-assembled tape packages are considered. Based on the analysis of the magnetic field distribution in the conductor by finite element method, the design characteristics of the proposed conductors under various operating modes of the electromagnetic system (EMS) of the tokamak TRT was evaluated. The results of the evaluation of the current carrying capacity of the conductor and the estimation of energy losses in a changing magnetic field in comparison with known methods are also presented.
基金the National Natural Science Foundation of China(11902129,11932008)the China Postdoctoral Science Foundation(2019T120963)the Fundamental Research Funds for the Central Universities(lzujbky-2020-pd03,lzujbky-2021-kb06).
文摘We present a new test method for the accurate measurement of the transverse tensile interfacial strength of rare-earth barium copper oxide(REBCO)-coated conductor(CC)tapes to overcome heavy scattering of data tested using regular test methods.A new composite structure specimen is designed and constructed by solidifying a standard epoxy resin tensile specimen using the three-dimensional printing technology,where a short REBCO CC tape is embedded.The feasibility of the proposed test method is numerically validated through finite element(FE)calculations.Experimental results show that the valid delaminated strength is 2.19-2.51 MPa with the maximum relative error of 7.3%,indicating the elimination of significant scattering in the tested data.By analysing the morphology of the delaminated interfaces and energy-dispersive spectroscopy results,it is discovered that delamination primarily occurs at the interface between the REBCO superconducting layer and the buffer layer and that a small portion of the REBCO and buffer layers peels off.Further error analysis based on the FE method indicates that the tape is more likely to delaminate because of initial defects,whereas the adhesion at the edges of the CC tape due to the redundancy of the epoxy resin increases the resistance of the CC tape to delamination,resulting in a higher testing value than the real one.
基金National Natural Science Foundation of China(No.50172040)National High-Technology Development Program of China(No.2002AA306251)
文摘We prepared a series of MgB2 bulk samples under different temperatures, holding time and increasing rates in temperature by the solid state reaction. The thermodynamic behavior and phase formation in the Mg-B system were studied by using DTA, XRD and SEM. The results indicate that the formation of the MgB2 phase is very fast and the high increasing rate in temperature is necessary to obtain high quality MgB2. In addition, the effects of the Zr-doping in Mg1-xZrxB2 bulk samples fabricated by the solid state reaction at ambient pressure on phase compositions, microstructure and flux pinning behavior were investigated by using XRD, SQUID magnetometer, SEM and TEM. Critical current density Jc can be significantly enhanced by the Zr-doping and the best data are achieved in Mg0.9Zr0.1B2. For this sample, Jc values are remarkably improved to 1. 83 × 106 A/cm2 in self-field and 5. 51 × 105 A/cm2in 1T at 20K. Also, high quality MgB2/Ta/Cu wires and tapes with and without Ti-doping, MgB2/Fe wires and 18 filament MgB2/NbZr/Cu tapes were fabricated by the powder-in-tube (PIT) method at ambient pressure. The phase compositions, microstructure features and flux pinning properties were studied. The results suggest that Fe is the best metal for these sheaths. MgB2/Fe wires exhibit very high Jc at high temperatures and high fields. Jc values reach as high as 1.43 × 105A/cm2(4. 2K, 4T) and 3.72 × 104 A/cm2(15K, 4T).
文摘Bi system tapes were prepared using the powder in tube method. The tapes were processed to their final thickness by repeated rolling and pressing and by a combination of rolling and pressing with intermediate heat treatment. The different processing techniques greatly affected the critical current density J c of the tapes because the homogeneity of the ceramic core and the propensity for crack formation within the tapes mainly depended on the deformation process.
文摘Silver-clad （Bi,Pb）2Sr2Ca2Cu3O10＋x long wires produced by powder-in-tube techniques, which have been recognized as the first generation of the High Temperature Superconducting （HTS） wires, are expected to apply widely especially in strong current applications. In this work, the processing, characterization and application of the silver-clad （Bi,Pb）2Sr2Ca2Cu3Ol0＋x HTS wires are summarized. The HTS wires are fabricated using the combination of powder-in-tube technique, and the resulting wires are fully characterized by the means of chemical analyses, microstructural observation, electrical and magnetic measurements. The relationship among fabrication parameters, chemical and microstructural characteristics, and electrical and magnetic properties are analyzed. Applications of the HTS wires have also been introduced according to their strong current behaviors with various prototype devices made.
文摘Three kinds of silver-sheathed Bi(2223) oxide superconductor tapes (single-core tape, Ag-powder-added tape and multifilamentary type) were successfully prepared, namely, through the powder-in-tube method. The critical current density (Jc), the Jc-B characteristics, microstructures and the relation between Jc and strain of three kinds of tapes were evaluated and compared. The maximum Jc of three kinds of tapes at 77.7 K in zero magnetic field are 28700 A/cm2 for single-core tape, 20800 A/cm2 for Ag-powder-added tape, 11700 A/cm2 for multifilamentary tape. Single-core tapes exhibit high Jc values and good Jc-B characteristics.
