Superconducting films with the same hole density but different geometric symmetry have been designed and fabricated. The R(H) curves show obvious periodic oscillations with several dips at fractional matching fields. ...Superconducting films with the same hole density but different geometric symmetry have been designed and fabricated. The R(H) curves show obvious periodic oscillations with several dips at fractional matching fields. It is found that the period of the oscillations in the low field is not necessary equal to that derived from the hole density, but consistent with that from the corresponding wire networks when the large disk-like film regions are regarded as nodes. The experimental results of R(H), T_(c)(H) and j_(c)(H) at fractional matching fields within the first oscillation also support the rationality of considering films with large-diametered hole arrays as wire networks. Our results demonstrate that the connectivity of superconducting films with large-diametered hole arrays plays a more important role in the oscillations of R(H) curves.展开更多
Ice cover on transmission lines is a significant issue that affects the safe operation of the power system.Accurate calculation of the thickness of wire icing can effectively prevent economic losses caused by ice disa...Ice cover on transmission lines is a significant issue that affects the safe operation of the power system.Accurate calculation of the thickness of wire icing can effectively prevent economic losses caused by ice disasters and reduce the impact of power outages on residents.However,under extreme weather conditions,strong instantaneous wind can cause tension sensors to fail,resulting in significant errors in the calculation of icing thickness in traditional mechanics-based models.In this paper,we propose a dynamic prediction model of wire icing thickness that can adapt to extreme weather environments.The model expands scarce raw data by the Wasserstein Generative Adversarial Network with Gradient Penalty(WGAN-GP)technique,records historical environmental information by a recurrent neural network,and evaluates the ice warning levels by a classifier.At each time point,the model diagnoses whether the current sensor failure is due to icing or strong winds.If it is determined that the wire is covered with ice,the icing thickness will be calculated after the wind-induced tension is removed from the ice-wind coupling tension.Our new model was evaluated using data from the power grid in an area with extreme weather.The results show that the proposed model has significant improvements in accuracy compared with traditional models.展开更多
We theoretically investigate the electronic structure of cylindrical magnetic topological insulator quantum wires in MnBi_(2)Te_(4).Our study reveals the emergence of topological surface states in the ferromagnetic ph...We theoretically investigate the electronic structure of cylindrical magnetic topological insulator quantum wires in MnBi_(2)Te_(4).Our study reveals the emergence of topological surface states in the ferromagnetic phase,characterized by spin-polarized subbands resulting from intrinsic magnetization.In the antiferromagnetic phase,we identify the coexistence of three distinct types of topological states,encompassing both surface states and central states.展开更多
Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing addit...Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing additive-induced defects,and alleviating residual stress and deformation,all of which are critical for enhancing the mechanical performance of the manufactured parts.Integrating interlayer friction stir processing(FSP)into WAAM significantly enhances the quality of deposited materials.However,numerical simulation research focusing on elucidating the associated thermomechanical coupling mechanisms remains insufficient.A comprehensive numerical model was developed to simulate the thermomechanical coupling behavior in friction stir-assisted WAAM.The influence of post-deposition FSP on the coupled thermomechanical response of the WAAM process was analyzed quantitatively.Moreover,the residual stress distribution and deformation behavior under both single-layer and multilayer deposition conditions were investigated.Thermal analysis of different deposition layers in WAAM and friction stir-assisted WAAM was conducted.Results show that subsequent layer deposition induces partial remelting of the previously solidified layer,whereas FSP does not cause such remelting.Furthermore,thermal stress and deformation analysis confirm that interlayer FSP effectively mitigates residual stresses and distortion in WAAM components,thereby improving their structural integrity and mechanical properties.展开更多
In this study,multilayer lamination welding was employed to prepare graphene/copper(Gr/Cu)composite billets from graphene-coated copper foils,followed by multi-pass cold drawing to produce Φ1 mm Gr/Cu composite wires...In this study,multilayer lamination welding was employed to prepare graphene/copper(Gr/Cu)composite billets from graphene-coated copper foils,followed by multi-pass cold drawing to produce Φ1 mm Gr/Cu composite wires.Microstructure and property analyses in both the cold-drawn and annealed states show that the incorporation of graphene significantly improves the ductility and electrical conductivity of the copper wire.After annealing at 350℃ for 30 minutes,the composite wire demonstrates a tensile strength of 270 MPa and an electrical conductivity of 102.74%IACS,both superior to those of pure copper wire under identical conditions.At 150℃,the electrical conductivity of the annealed composite wire reaches 72.60%IACS,notably higher than the 68.19%IACS of pure copper.The results suggest that graphene is uniformly distributed within the composite wire,with minimal impact on conductivity,while effectively refining the copper grain structure to enhance ductility.Moreover,graphene suppresses copper lattice vibrations at elevated temperatures,reducing the rate of conductivity degradation.展开更多
（Fes3Ga17）98Cr2 wires each with a diameter of 0.7 mm are prepared by hot swaging and warm drawing from the casting rods directly, because the ductility of Fes3Ga17alloy is improved by adding Cr element. The Wiedeman...（Fes3Ga17）98Cr2 wires each with a diameter of 0.7 mm are prepared by hot swaging and warm drawing from the casting rods directly, because the ductility of Fes3Ga17alloy is improved by adding Cr element. The Wiedemann twists and dependences on magnetostrictions of Fe83Ga17 and （Fe83Ga17）98Cr2 wires are investigated. The largest observed Wiedemann twists of 245 s.cm-1 and 182 s.cm-1 are detected in the annealed Fes3Ga17 and （Fe83Ga17）98Cr2 wires, respectively. The magnetostrictions of the annealed Fes3Ga17 and （Fes3Ga17）98Cr2 wires are 160 ppm and 107 ppm, respectively. The maximum of the Wiedemann twist increases with magnetostriction increasing. However the magnetostriction is just one important factor that affects the Wiedemann effect of alloy wire, and the relationship between magnetostriction and Wiedemann effect is a complex function rather than a simple function.展开更多
With the use of variational method of Pekar type, this paper studied the energy levels of magnetopolaron in quantum wire with strong electron phonon interaction. The magnetopolaron binding energy in the ground state a...With the use of variational method of Pekar type, this paper studied the energy levels of magnetopolaron in quantum wire with strong electron phonon interaction. The magnetopolaron binding energy in the ground state and in the excited state, as well as the resonance frequency of magnetopolaron were calculated. Their dependence on the cyclotron frequency and the confinement strength of quantum wire was depicted. The limiting case of bulk type and strict two dimensional type was discussed.展开更多
The magneto-impedance(MI) effect in amorphous and current annealed Fe_(73.5)Cu_1Nb_3Si_(13.5)B_9 wires has been measured to investigate the influence of DC annealing,highcurrent-density electropulsing annealing and te...The magneto-impedance(MI) effect in amorphous and current annealed Fe_(73.5)Cu_1Nb_3Si_(13.5)B_9 wires has been measured to investigate the influence of DC annealing,highcurrent-density electropulsing annealing and tensile stress applied during annealing process.The results showed that the MI of DC annealed sample exhibits a sharp maximum.The Maximum MI ratio of 60%was observed in the sample of high-current-density electropulsing annealed under applied tensile stress.展开更多
Prestressed wire winded framework （PWWF） is an advanced structure and the most expensive part in the large-scale equip- ment. The traditional design of PWWF is complicated, highly iterative and cost uncontrolable, b...Prestressed wire winded framework （PWWF） is an advanced structure and the most expensive part in the large-scale equip- ment. The traditional design of PWWF is complicated, highly iterative and cost uncontrolable, because PWWF is a variable stiffness multi-agent structure, with non-linear loading and deformation coordination. In this paper, cost optimization method of large-scale PWWF by multiple-island genetic algorithm （MIGA） is presented. Optimization design flow and optimization model are proposed based on variable-tension wire winding theory. An example of the PWWF cost optimization of isostatic equipment with axial load 6 000 kN is given. The optimization cost is reduced by 21.6% compared with traditional design. It has also been verified by the finite-element analysis and successfully applied to an actual PWWF design of isostatic press. The results show that this method is efficient and reliable. This method can also provide a guide for optimal design for ultra-large dimension muti-frame structure of 546 MN and 907 MN isostatic press equipment.展开更多
To improve the quality of high carbon wire rods,combined electromagnetic stirring was introduced in the continuous casting of round billets with a diameter of 250mm at Tianjin Rockcheck Steel Group Co.In this paper,th...To improve the quality of high carbon wire rods,combined electromagnetic stirring was introduced in the continuous casting of round billets with a diameter of 250mm at Tianjin Rockcheck Steel Group Co.In this paper,the positioning of final electromagnetic stirring(F-EMS)was determined by nail-shooting method.Furthermore,the effect of mold electromagnetic stirring(M-EMS)on the macrostructure and internal defects in the round billets was investigated to find out the optimal operating parameters for continuous casting of SWRH 82B round billets.The results show the desirable positioning of F-EMS locates 9.7m below the mold level where the molten steel can be effectively driven by electromagnetic force and disperse central composition segregation.The shrinkage cavity is totally eliminated with the rotational M-EMS.The ratio and index of central composition segregation and center porosity can be reduced significantly. Furthermore,the equiaxed crystal ratio is considerably increased to 64%under 480A/3Hz M-EMS and 500A/10Hz F-EMS. Fine microstructure and mechanical property of wire rod are presented after optimization of combined electromagnetic stirring.Accordingly,the probability of occurrence of cup-cone fracture of wire rod is reduced dramatically.展开更多
Through magnetization measurement with a SQUID magnetometer the heat treatment optimization of an international thermonuclear experimental reactor （ITER）-type internal-Sn Nb3Sn superconducting wire has been investig...Through magnetization measurement with a SQUID magnetometer the heat treatment optimization of an international thermonuclear experimental reactor （ITER）-type internal-Sn Nb3Sn superconducting wire has been investigated. The irreversibility temperature T^＊ （H）, which is mainly dependent on A15 phase composition, was obtained by a warming and cooling cycle at a fixed field. The hysteresis width △M（H） which reflects the flux pinning situation of the A15 phase is determined by the sweeping of magnetic field at a constant temperature. The results obtained from differently heat-treated samples show that the combination of T^＊ （H） with AM（H） measurement is very effective for optimizing the heat reaction process. The heat treatment condition of the ITER-type wire is optimized at 675℃/128 h, which results in a composition closer to stoichiometric Nb3Sn and a state with best flux pinning.展开更多
In this study,magnetic abrasives were obtained by crushing and sieving sintered iron-silicon carbide(Fe-SiC)composites.Fe and SiC powders with different mesh numbers were pre-compacted using different pressures and th...In this study,magnetic abrasives were obtained by crushing and sieving sintered iron-silicon carbide(Fe-SiC)composites.Fe and SiC powders with different mesh numbers were pre-compacted using different pressures and then sintered at various temperatures and with different holding times.The dispersion uniformity of the SiC powder was improved through surface modification using polyethylene glycol(PEG)300.The resulting magnetic abrasives were characterized in terms of phase composition,density,relative permeability,and microstructure;this was followed by a comprehensive analysis to reveal the optimal processing parameters.The ideal combination of process parameters for preparing SiC magnetic-abrasive grains for the magnetic induction-wire sawing process was obtained,which are preparation load of 60 kN,a SiC mesh number of 1,500,a sintering temperature of 1100℃,and a holding time of 4 h.展开更多
In this paper, an artificial neural network method that can predict the chemical composition of deposited weld metal by CO 2 Shielded Flux Cored Wire Surfacing was studied. It is found that artificial neural networ...In this paper, an artificial neural network method that can predict the chemical composition of deposited weld metal by CO 2 Shielded Flux Cored Wire Surfacing was studied. It is found that artificial neural network is a good approach on studying welding metallurgy processes that cannot be described by conventional mathematical methods. In the same time we explored a new way to study the no equilibrium welding metallurgy processes.展开更多
In order to increase the reaction rates between the molten steel and the slag and cut down the reduction time when the top slag of manganese ore is added into the molten steel,a method of directly alloying manganese o...In order to increase the reaction rates between the molten steel and the slag and cut down the reduction time when the top slag of manganese ore is added into the molten steel,a method of directly alloying manganese ore has been experimented in a 500-kg induction furnace.The results show that the manganese yield is greater than 90%when the wire feeding method is used.The manganese yield is 43.26%within 1 min.In contrast,the manganese yield for the top-slag adding process is only 10.98%for the same duration.The mass transfer rate of the manganese is greater in the molten steel than in the slag,and the limiting factor is the mass transfer rate of the manganese in the slag in the period of 10-30 min.The slag composition area is closer to the area of high melting point for the wire feeding method than for the top-slag adding process.During the slagging process,refining slag composed of C a O and SiO:is formed after 15 min;after 25-30 min,refining slag with a high basicity is formed and consists of CaO,SiO2 and Al203.展开更多
Aiming at the major failure mode of prestressed concrete cylinder pipes (PCCP),namely the fracture of prestressed steel wires,the broken wire detection technology based on orthogonal electromagnetic principle is studi...Aiming at the major failure mode of prestressed concrete cylinder pipes (PCCP),namely the fracture of prestressed steel wires,the broken wire detection technology based on orthogonal electromagnetic principle is studied. The detection system model is established and optimized by using COMSOL finite element simulation software. Furthermore,the theoretical analysis of the wire-breaking effect is carried out. The influence of factors on broken wire signal characteristics such as edge effect,circumferential relative position of the detector and broken wires,excitation frequency and relative permeability of steel wires is analyzed,which provides a theoretical guidance for the field detection. The influence of the steel cylinder structure on the simulation results is analyzed,which provides a reference for the improvement of calculation efficiency. The corresponding detection system is designed and implemented. Concretely,a high-voltage and high-power sinusoidal signal coil drive scheme based on sinusoidal pulse width modulation technology and an intelligent power module is innovatively proposed and the corresponding protection circuit is designed. The broken wire signal could be effectively extracted through a lock-in amplifier. The experimental results show that this system can effectively identify the broken wires with low cost.展开更多
Composite structure materials were potential sensing elements for magnetic sensors due to Giant magnetoimpedance(GMI) effect. Two kinds of composite wires with different magnetic/non-magnetic structures were fabricate...Composite structure materials were potential sensing elements for magnetic sensors due to Giant magnetoimpedance(GMI) effect. Two kinds of composite wires with different magnetic/non-magnetic structures were fabricated by using electroless deposition methods and the magnetoimpedance properties were investigated. The maximum GMI ratio of 114% was acquired at 60 MHz in the composite wires with a ferromagnetic core, whereas, 116% of maximum GMI ratio was found in the composite wires with a conductive core at low frequency of 600 k Hz. These results exhibit that the GMI ratio reaches the maximum when magnetoresistance ratio ?R/R and magnetoinductance ratio ?X/X make the comparative contributions to the total magnetoimpedance(MI). The obvious GMI effect obtained in the composite wires with conductive core frequency may provide a candidate for applications in magnetic sensors, especially at low frequencies.展开更多
By simplifying saturatedly magnetized wire-rope to magnetic dipoles of the same magnetic field strength, an equivalent magnetic dipoles model is developed and the measuring principle for recognising damage of broken w...By simplifying saturatedly magnetized wire-rope to magnetic dipoles of the same magnetic field strength, an equivalent magnetic dipoles model is developed and the measuring principle for recognising damage of broken wire was presented. The relevant calculation formulas were also deduced. A composite solution method about nonlinear optimization was given. An example was given to illustrate the use of the equivalent magnetic dipoles method for quantitative damage recognition, and demonstrates that the result of this method is consistent with the real situation, so the method is valid and practical. wire-rope, damage of broken wires, quantitative recognition, equivalent magnetic dipoles, simulate展开更多
The hole-hole interaction(Ehh) has been considered in a CdTe/Cd1-x Mnx Te Semimagnetic Quantum Well Wire(SQWW). The influence of the shape of the confining potential like square well and parabolic well type on the bin...The hole-hole interaction(Ehh) has been considered in a CdTe/Cd1-x Mnx Te Semimagnetic Quantum Well Wire(SQWW). The influence of the shape of the confining potential like square well and parabolic well type on the binding energy of an acceptor impurity with two holes and their Coulomb interaction between them has been studied for various impurity locations. Magnetic field has been used as a probe to understand the carrier-carrier correlation in such Quasi 1-Dimensional QWW since it alters the strength of the confining potential tremendously. In order to show the significance of the correlation between the two holes, the calculations have been done with and without including the correlation effect in the ground state wavefunction of the hyderogenic acceptor impurity and the results have been compared. The expectation value of the Hamiltonian, H, is minimized variationaly in the effective mass approximation through which(Ehh) has been obtained.展开更多
Monolayered Co and trilayered Co/Cu/Co were electroplated on 485 μm-diameter Cu wires using the bath pH 2.5. These wires can be functioned as magnetic sensors owing to their magnetoimpedance （MI） effect. By measuri...Monolayered Co and trilayered Co/Cu/Co were electroplated on 485 μm-diameter Cu wires using the bath pH 2.5. These wires can be functioned as magnetic sensors owing to their magnetoimpedance （MI） effect. By measuring at four different frequencies （100, 250, 500, and 1000 kHz） and Co thicknesses （2.5, 5.0, 10.0, and 25.0μm）, the MI ratio of electroplated Co on Cu wires tended to increase with increasing Co thickness and frequency of the driving current. The Co/Cu/Co on Cu wires exhibited even higher MI ratio. The magnetic layer also regulated the magnetic inductions and anisotropy regardless of the size of nonmagnetic core. Nevertheless, the diameter of the Cu core had a significant effect on the MI ratio. By comparing with the 47.7 μm-diameter Ag cores electroplated by Co and Co/Cu/Co of the same thickness, the Cu cores with a larger diameter gave rise to a larger MI ratio because their lower electrical resistance enhanced the crossing effect. Substantial MI ratio was observed even in a low frequency regime because the skin effect occurred at a low frequency in the case of electroplated wires with large core diameters.展开更多
According to the characteristics of remote welding, including multiple parameters, real-time, and reliability of long wire transmitting, a distributing computer control scheme is adopted. A serial communication networ...According to the characteristics of remote welding, including multiple parameters, real-time, and reliability of long wire transmitting, a distributing computer control scheme is adopted. A serial communication network between the master and the slavery computers is constructed. A synchro-control network among slavery computers is designed. Uniform message format and communication protocols are made. Considering intensive high-frequency noises at the welding zone, a quadruple check mode, including data sum check, parameter type check, welding parameters check and Exclusive OR （ XOR ） check, is adopted to assure the reliability of communication among multiple computers. Based on disturbing circuit, common circuit and sensitive circuit, the measures are brought forward to ensure the stabilization of communication network of remote arc welding by analyzing the wiring principle of anti-high-frequency interference of system bus, signal wires and shielding twisted-pair（STP） wires. The results provide the theoretical and practical references for the manufacture of remote welding robot and the quality of remote welding.展开更多
基金support from the National Natural Science Foundation of China (Grant Nos. 11974412 and 11774400)the National Key R&D Program of China (Grant Nos. 2017YFA0302903 and 2018YFA0305703)。
文摘Superconducting films with the same hole density but different geometric symmetry have been designed and fabricated. The R(H) curves show obvious periodic oscillations with several dips at fractional matching fields. It is found that the period of the oscillations in the low field is not necessary equal to that derived from the hole density, but consistent with that from the corresponding wire networks when the large disk-like film regions are regarded as nodes. The experimental results of R(H), T_(c)(H) and j_(c)(H) at fractional matching fields within the first oscillation also support the rationality of considering films with large-diametered hole arrays as wire networks. Our results demonstrate that the connectivity of superconducting films with large-diametered hole arrays plays a more important role in the oscillations of R(H) curves.
基金supported by the Science and Technology Project of State Grid Corporation of China(SGXJDK00GYJS2400035).
文摘Ice cover on transmission lines is a significant issue that affects the safe operation of the power system.Accurate calculation of the thickness of wire icing can effectively prevent economic losses caused by ice disasters and reduce the impact of power outages on residents.However,under extreme weather conditions,strong instantaneous wind can cause tension sensors to fail,resulting in significant errors in the calculation of icing thickness in traditional mechanics-based models.In this paper,we propose a dynamic prediction model of wire icing thickness that can adapt to extreme weather environments.The model expands scarce raw data by the Wasserstein Generative Adversarial Network with Gradient Penalty(WGAN-GP)technique,records historical environmental information by a recurrent neural network,and evaluates the ice warning levels by a classifier.At each time point,the model diagnoses whether the current sensor failure is due to icing or strong winds.If it is determined that the wire is covered with ice,the icing thickness will be calculated after the wind-induced tension is removed from the ice-wind coupling tension.Our new model was evaluated using data from the power grid in an area with extreme weather.The results show that the proposed model has significant improvements in accuracy compared with traditional models.
基金Project sponsored by the Natural Science Foundation of Chongqing,China(Grant No.CSTB2024NSCQMSX0736)the Special Project of Chongqing Technology Innovation and Application Development(Major Project)(Grant No.CSTB2024TIAD-STX0035)the Research Foundation of Institute for Advanced Sciences of CQUPT(Grant No.E011A2022328)。
文摘We theoretically investigate the electronic structure of cylindrical magnetic topological insulator quantum wires in MnBi_(2)Te_(4).Our study reveals the emergence of topological surface states in the ferromagnetic phase,characterized by spin-polarized subbands resulting from intrinsic magnetization.In the antiferromagnetic phase,we identify the coexistence of three distinct types of topological states,encompassing both surface states and central states.
基金National Key Research and Development Program of China(2022YFB4600902)Shandong Provincial Science Foundation for Outstanding Young Scholars(ZR2024YQ020)。
文摘Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing additive-induced defects,and alleviating residual stress and deformation,all of which are critical for enhancing the mechanical performance of the manufactured parts.Integrating interlayer friction stir processing(FSP)into WAAM significantly enhances the quality of deposited materials.However,numerical simulation research focusing on elucidating the associated thermomechanical coupling mechanisms remains insufficient.A comprehensive numerical model was developed to simulate the thermomechanical coupling behavior in friction stir-assisted WAAM.The influence of post-deposition FSP on the coupled thermomechanical response of the WAAM process was analyzed quantitatively.Moreover,the residual stress distribution and deformation behavior under both single-layer and multilayer deposition conditions were investigated.Thermal analysis of different deposition layers in WAAM and friction stir-assisted WAAM was conducted.Results show that subsequent layer deposition induces partial remelting of the previously solidified layer,whereas FSP does not cause such remelting.Furthermore,thermal stress and deformation analysis confirm that interlayer FSP effectively mitigates residual stresses and distortion in WAAM components,thereby improving their structural integrity and mechanical properties.
基金Funded by Hunan Provincial Natural Science Foundation(No.2023JJ40074)Hunan Provincial Education Department Excellent Youth Project(No.21B0757)Hunan Provincial Engineering Technology Center(No.2022TP2036)。
文摘In this study,multilayer lamination welding was employed to prepare graphene/copper(Gr/Cu)composite billets from graphene-coated copper foils,followed by multi-pass cold drawing to produce Φ1 mm Gr/Cu composite wires.Microstructure and property analyses in both the cold-drawn and annealed states show that the incorporation of graphene significantly improves the ductility and electrical conductivity of the copper wire.After annealing at 350℃ for 30 minutes,the composite wire demonstrates a tensile strength of 270 MPa and an electrical conductivity of 102.74%IACS,both superior to those of pure copper wire under identical conditions.At 150℃,the electrical conductivity of the annealed composite wire reaches 72.60%IACS,notably higher than the 68.19%IACS of pure copper.The results suggest that graphene is uniformly distributed within the composite wire,with minimal impact on conductivity,while effectively refining the copper grain structure to enhance ductility.Moreover,graphene suppresses copper lattice vibrations at elevated temperatures,reducing the rate of conductivity degradation.
基金Project supported by the State Key Development Program for Basic Research of China (Grant No. 2011CB606304)the National Natural Science Foundation for Postdoctoral Scientists of China (Grant No. 2011M500229)the Program for New Century Excellent Talents in University,China (Grant No. NCET-09-02120)
文摘（Fes3Ga17）98Cr2 wires each with a diameter of 0.7 mm are prepared by hot swaging and warm drawing from the casting rods directly, because the ductility of Fes3Ga17alloy is improved by adding Cr element. The Wiedemann twists and dependences on magnetostrictions of Fe83Ga17 and （Fe83Ga17）98Cr2 wires are investigated. The largest observed Wiedemann twists of 245 s.cm-1 and 182 s.cm-1 are detected in the annealed Fes3Ga17 and （Fe83Ga17）98Cr2 wires, respectively. The magnetostrictions of the annealed Fes3Ga17 and （Fes3Ga17）98Cr2 wires are 160 ppm and 107 ppm, respectively. The maximum of the Wiedemann twist increases with magnetostriction increasing. However the magnetostriction is just one important factor that affects the Wiedemann effect of alloy wire, and the relationship between magnetostriction and Wiedemann effect is a complex function rather than a simple function.
基金Science Foundation of Shanghai MunicipalCommission of Education(99QF5 5 ) Oneof us(S.Gu) also acknowledged the fi-nancial support of National Natural Sci-ence Foundation of China(No.197740 40 )
文摘With the use of variational method of Pekar type, this paper studied the energy levels of magnetopolaron in quantum wire with strong electron phonon interaction. The magnetopolaron binding energy in the ground state and in the excited state, as well as the resonance frequency of magnetopolaron were calculated. Their dependence on the cyclotron frequency and the confinement strength of quantum wire was depicted. The limiting case of bulk type and strict two dimensional type was discussed.
文摘The magneto-impedance(MI) effect in amorphous and current annealed Fe_(73.5)Cu_1Nb_3Si_(13.5)B_9 wires has been measured to investigate the influence of DC annealing,highcurrent-density electropulsing annealing and tensile stress applied during annealing process.The results showed that the MI of DC annealed sample exhibits a sharp maximum.The Maximum MI ratio of 60%was observed in the sample of high-current-density electropulsing annealed under applied tensile stress.
文摘Prestressed wire winded framework （PWWF） is an advanced structure and the most expensive part in the large-scale equip- ment. The traditional design of PWWF is complicated, highly iterative and cost uncontrolable, because PWWF is a variable stiffness multi-agent structure, with non-linear loading and deformation coordination. In this paper, cost optimization method of large-scale PWWF by multiple-island genetic algorithm （MIGA） is presented. Optimization design flow and optimization model are proposed based on variable-tension wire winding theory. An example of the PWWF cost optimization of isostatic equipment with axial load 6 000 kN is given. The optimization cost is reduced by 21.6% compared with traditional design. It has also been verified by the finite-element analysis and successfully applied to an actual PWWF design of isostatic press. The results show that this method is efficient and reliable. This method can also provide a guide for optimal design for ultra-large dimension muti-frame structure of 546 MN and 907 MN isostatic press equipment.
基金Item Sponsored by National Natural Science Foundation of China[No.50834009]the National Natural Science Foundation of China[No.51004038]+1 种基金Key Grant Project of China Ministry of Education(No.311014)the 111 Project of China(No.B07015)
文摘To improve the quality of high carbon wire rods,combined electromagnetic stirring was introduced in the continuous casting of round billets with a diameter of 250mm at Tianjin Rockcheck Steel Group Co.In this paper,the positioning of final electromagnetic stirring(F-EMS)was determined by nail-shooting method.Furthermore,the effect of mold electromagnetic stirring(M-EMS)on the macrostructure and internal defects in the round billets was investigated to find out the optimal operating parameters for continuous casting of SWRH 82B round billets.The results show the desirable positioning of F-EMS locates 9.7m below the mold level where the molten steel can be effectively driven by electromagnetic force and disperse central composition segregation.The shrinkage cavity is totally eliminated with the rotational M-EMS.The ratio and index of central composition segregation and center porosity can be reduced significantly. Furthermore,the equiaxed crystal ratio is considerably increased to 64%under 480A/3Hz M-EMS and 500A/10Hz F-EMS. Fine microstructure and mechanical property of wire rod are presented after optimization of combined electromagnetic stirring.Accordingly,the probability of occurrence of cup-cone fracture of wire rod is reduced dramatically.
文摘Through magnetization measurement with a SQUID magnetometer the heat treatment optimization of an international thermonuclear experimental reactor （ITER）-type internal-Sn Nb3Sn superconducting wire has been investigated. The irreversibility temperature T^＊ （H）, which is mainly dependent on A15 phase composition, was obtained by a warming and cooling cycle at a fixed field. The hysteresis width △M（H） which reflects the flux pinning situation of the A15 phase is determined by the sweeping of magnetic field at a constant temperature. The results obtained from differently heat-treated samples show that the combination of T^＊ （H） with AM（H） measurement is very effective for optimizing the heat reaction process. The heat treatment condition of the ITER-type wire is optimized at 675℃/128 h, which results in a composition closer to stoichiometric Nb3Sn and a state with best flux pinning.
基金supported by Talents Introduction Research Projects of NBPT[Grant Number RC201807]the National Nature Science Foundation of China(NSFC)[Grant Number 51475427].
文摘In this study,magnetic abrasives were obtained by crushing and sieving sintered iron-silicon carbide(Fe-SiC)composites.Fe and SiC powders with different mesh numbers were pre-compacted using different pressures and then sintered at various temperatures and with different holding times.The dispersion uniformity of the SiC powder was improved through surface modification using polyethylene glycol(PEG)300.The resulting magnetic abrasives were characterized in terms of phase composition,density,relative permeability,and microstructure;this was followed by a comprehensive analysis to reveal the optimal processing parameters.The ideal combination of process parameters for preparing SiC magnetic-abrasive grains for the magnetic induction-wire sawing process was obtained,which are preparation load of 60 kN,a SiC mesh number of 1,500,a sintering temperature of 1100℃,and a holding time of 4 h.
文摘In this paper, an artificial neural network method that can predict the chemical composition of deposited weld metal by CO 2 Shielded Flux Cored Wire Surfacing was studied. It is found that artificial neural network is a good approach on studying welding metallurgy processes that cannot be described by conventional mathematical methods. In the same time we explored a new way to study the no equilibrium welding metallurgy processes.
基金This research has been financially supported by the National Key R&D Program(2017YFB0304000)the Beijing Natural Science Foundation(2172057)in China+1 种基金the State Key Laboratory of Refractories and Metallurgy Foundation(G201804)the National Natural Science Foundation of China(51704080,51874102).
文摘In order to increase the reaction rates between the molten steel and the slag and cut down the reduction time when the top slag of manganese ore is added into the molten steel,a method of directly alloying manganese ore has been experimented in a 500-kg induction furnace.The results show that the manganese yield is greater than 90%when the wire feeding method is used.The manganese yield is 43.26%within 1 min.In contrast,the manganese yield for the top-slag adding process is only 10.98%for the same duration.The mass transfer rate of the manganese is greater in the molten steel than in the slag,and the limiting factor is the mass transfer rate of the manganese in the slag in the period of 10-30 min.The slag composition area is closer to the area of high melting point for the wire feeding method than for the top-slag adding process.During the slagging process,refining slag composed of C a O and SiO:is formed after 15 min;after 25-30 min,refining slag with a high basicity is formed and consists of CaO,SiO2 and Al203.
基金National Natural Science Foundation of China(No.61304244)
文摘Aiming at the major failure mode of prestressed concrete cylinder pipes (PCCP),namely the fracture of prestressed steel wires,the broken wire detection technology based on orthogonal electromagnetic principle is studied. The detection system model is established and optimized by using COMSOL finite element simulation software. Furthermore,the theoretical analysis of the wire-breaking effect is carried out. The influence of factors on broken wire signal characteristics such as edge effect,circumferential relative position of the detector and broken wires,excitation frequency and relative permeability of steel wires is analyzed,which provides a theoretical guidance for the field detection. The influence of the steel cylinder structure on the simulation results is analyzed,which provides a reference for the improvement of calculation efficiency. The corresponding detection system is designed and implemented. Concretely,a high-voltage and high-power sinusoidal signal coil drive scheme based on sinusoidal pulse width modulation technology and an intelligent power module is innovatively proposed and the corresponding protection circuit is designed. The broken wire signal could be effectively extracted through a lock-in amplifier. The experimental results show that this system can effectively identify the broken wires with low cost.
基金Shanghai Automotive Science and Technology Development Foundation (SAISTDF/12-06)East China Normal University Program (78210142, 78210183)Shanghai Ocean University Program (A-2600-10-0054, B-5406-12-0012)
文摘Composite structure materials were potential sensing elements for magnetic sensors due to Giant magnetoimpedance(GMI) effect. Two kinds of composite wires with different magnetic/non-magnetic structures were fabricated by using electroless deposition methods and the magnetoimpedance properties were investigated. The maximum GMI ratio of 114% was acquired at 60 MHz in the composite wires with a ferromagnetic core, whereas, 116% of maximum GMI ratio was found in the composite wires with a conductive core at low frequency of 600 k Hz. These results exhibit that the GMI ratio reaches the maximum when magnetoresistance ratio ?R/R and magnetoinductance ratio ?X/X make the comparative contributions to the total magnetoimpedance(MI). The obvious GMI effect obtained in the composite wires with conductive core frequency may provide a candidate for applications in magnetic sensors, especially at low frequencies.
基金Supported by the National Natural Science Foundation of China(50475166) and Natural Science Foundation of Shandong Province (Y2002F09) and Qingdao Scientific Bureau(04-3NS-10)
文摘By simplifying saturatedly magnetized wire-rope to magnetic dipoles of the same magnetic field strength, an equivalent magnetic dipoles model is developed and the measuring principle for recognising damage of broken wire was presented. The relevant calculation formulas were also deduced. A composite solution method about nonlinear optimization was given. An example was given to illustrate the use of the equivalent magnetic dipoles method for quantitative damage recognition, and demonstrates that the result of this method is consistent with the real situation, so the method is valid and practical. wire-rope, damage of broken wires, quantitative recognition, equivalent magnetic dipoles, simulate
基金Supported by University Grants Commission,New Delhi,India under Major Research Project F.No.42-816/2013(SR)
文摘The hole-hole interaction(Ehh) has been considered in a CdTe/Cd1-x Mnx Te Semimagnetic Quantum Well Wire(SQWW). The influence of the shape of the confining potential like square well and parabolic well type on the binding energy of an acceptor impurity with two holes and their Coulomb interaction between them has been studied for various impurity locations. Magnetic field has been used as a probe to understand the carrier-carrier correlation in such Quasi 1-Dimensional QWW since it alters the strength of the confining potential tremendously. In order to show the significance of the correlation between the two holes, the calculations have been done with and without including the correlation effect in the ground state wavefunction of the hyderogenic acceptor impurity and the results have been compared. The expectation value of the Hamiltonian, H, is minimized variationaly in the effective mass approximation through which(Ehh) has been obtained.
基金supported by the Walailak Universitys Research Unit Fund
文摘Monolayered Co and trilayered Co/Cu/Co were electroplated on 485 μm-diameter Cu wires using the bath pH 2.5. These wires can be functioned as magnetic sensors owing to their magnetoimpedance （MI） effect. By measuring at four different frequencies （100, 250, 500, and 1000 kHz） and Co thicknesses （2.5, 5.0, 10.0, and 25.0μm）, the MI ratio of electroplated Co on Cu wires tended to increase with increasing Co thickness and frequency of the driving current. The Co/Cu/Co on Cu wires exhibited even higher MI ratio. The magnetic layer also regulated the magnetic inductions and anisotropy regardless of the size of nonmagnetic core. Nevertheless, the diameter of the Cu core had a significant effect on the MI ratio. By comparing with the 47.7 μm-diameter Ag cores electroplated by Co and Co/Cu/Co of the same thickness, the Cu cores with a larger diameter gave rise to a larger MI ratio because their lower electrical resistance enhanced the crossing effect. Substantial MI ratio was observed even in a low frequency regime because the skin effect occurred at a low frequency in the case of electroplated wires with large core diameters.
文摘According to the characteristics of remote welding, including multiple parameters, real-time, and reliability of long wire transmitting, a distributing computer control scheme is adopted. A serial communication network between the master and the slavery computers is constructed. A synchro-control network among slavery computers is designed. Uniform message format and communication protocols are made. Considering intensive high-frequency noises at the welding zone, a quadruple check mode, including data sum check, parameter type check, welding parameters check and Exclusive OR （ XOR ） check, is adopted to assure the reliability of communication among multiple computers. Based on disturbing circuit, common circuit and sensitive circuit, the measures are brought forward to ensure the stabilization of communication network of remote arc welding by analyzing the wiring principle of anti-high-frequency interference of system bus, signal wires and shielding twisted-pair（STP） wires. The results provide the theoretical and practical references for the manufacture of remote welding robot and the quality of remote welding.
