The purpose of this research is to explore the feasibility of roller hemming of AZ31 B magnesium alloy sheet. During the test, a special experimental setup considering the current flow and insulation was designed and ...The purpose of this research is to explore the feasibility of roller hemming of AZ31 B magnesium alloy sheet. During the test, a special experimental setup considering the current flow and insulation was designed and employed. For the sake of simplicity, the flat surface-straight edge hemming style was selected. Electrical pulses were introduced in the pre-hemming and final hemming processes. The results show that when hemming at 448 K with hemming speed of 30 mm/min, AZ31 B magnesium alloy sheet was successfully hemmed with excellent perceived quality. No recoil/warp defect, cracking or springback was observed. Electrical pulses induced dynamic recrystallized grains were observed along the grain boundaries in the severely deformed area, which is of great importance to the improvement of the ductility of the material. The hardness was slightly increased after hemming with electrical pulses, and this fact could improve the friction resistance performance of the hemmed part.展开更多
Improving the permeability of coal seam is the key factor to realize efficient and safe mining of coalbed gas.In order to study the effect of high-voltage pulse breakdown on coal permeability,the multi-field coupling ...Improving the permeability of coal seam is the key factor to realize efficient and safe mining of coalbed gas.In order to study the effect of high-voltage pulse breakdown on coal permeability,the multi-field coupling high-voltage pulse crack coal permeability test equipment was used to carry out breakdown tests on bituminous coal samples soaked in conductive fluid under different voltage conditions.Subsequently,the breakdown effect of high voltage electrical pulse was characterized by comparison of breakdown energy,coal sample permeability and pore distribution,and the mechanism of voltage effect and the concentration of conductive liquid on the cracking effect was explored.The results show that the higher the pulse voltage,the faster the formation rate of plasma channel in coal and the more obvious the breakdown effect.With the increase of pulse voltage,the increment of coal porosity first increases and then decreases,the maximum increase is 31.4%,and the cracking effect is obvious.By comparing the changes of permeability and pore distribution of coal samples before and after pulse voltage treatment,it is found that conductive liquid can improve the conductivity in fragile cracks,crack growth and pore connectivity under pulse voltage.This paper provides a basis for high voltage electric pulse as a method to enhance coal permeability.展开更多
In this study,to investigate the mechanism through which high-voltage electrical pulses(HVEPs)enhance coal permeability and improve coalbed methane(CBM)extraction efficiency,liquid nitrogen adsorption analysis,nuclear...In this study,to investigate the mechanism through which high-voltage electrical pulses(HVEPs)enhance coal permeability and improve coalbed methane(CBM)extraction efficiency,liquid nitrogen adsorption analysis,nuclear magnetic resonance,infrared spectroscopy,and scanning electron microscopy were performed on HVEPtreated coal samples.The mentioned techniques were used to analyze the crack structures,pore distribution patterns,and changes in the chemical functional groups in the coal samples.The permeability enhancement mechanism of HVEP in coal was explored from macroscopic,mesoscopic,and microscopic perspectives.The chemical modification of coal through the breakdown of its oxygen-containing functional groups reduced the gas adsorption capacity of the coal samples and enhanced their desorption abilities.Simultaneously,the number of pores within the bottleneck pore interval of the coal samples increased significantly.The closed pores transformed into semi-closed and open pores.The pore volume was 2.86 times the pore volume of the original coal,while the pore specific surface area growth rate was 48.67%.This pronounced pore expansion effect eliminated the bottleneck pore interval,which reduced CBM seepage efficiency and enabled cross-scale CBM transport.Extensive parallel fractures and fissures appeared throughout the coal body.The connectivity within the porefracture network was enhanced substantially.This improved connectivity provided efficient pathways for gas transport.展开更多
Most studies on peripheral nerve injury have focused on repair at the site of injury, but very few have examined the effects of repair strategies on the more proximal neuronal cell bodies. In this study, an approximat...Most studies on peripheral nerve injury have focused on repair at the site of injury, but very few have examined the effects of repair strategies on the more proximal neuronal cell bodies. In this study, an approximately 10-mm-long nerve segment from the ischial tuberosity in the rat was transected and its proximal and distal ends were inverted and sutured. The spinal cord was subjected to pulsed electrical stimulation at T10 and L3, at a current of 6.5 m A and a stimulation frequency of 15 Hz, 15 minutes per session, twice a day for 56 days. After pulsed electrical stimulation, the number of neurons in the dorsal root ganglion and anterior horn was increased in rats with sciatic nerve injury. The number of myelinated nerve fibers was increased in the sciatic nerve. The ultrastructure of neurons in the dorsal root ganglion and spinal cord was noticeably improved. Conduction velocity of the sciatic nerve was also increased. These results show that pulsed electrical stimulation protects sensory neurons in the dorsal root ganglia as well as motor neurons in the anterior horn of the spinal cord after peripheral nerve injury, and that it promotes the regeneration of peripheral nerve fibers.展开更多
Two methods of calculating the parameters and characterizing the degree of pulse electrical disturbances influence on digital devices functioning, both analytical and numerical, are considered here. The analytical met...Two methods of calculating the parameters and characterizing the degree of pulse electrical disturbances influence on digital devices functioning, both analytical and numerical, are considered here. The analytical method permits one to assess the error occurrence probability in transmitting the data packets considering the dependence on the signal pulses energies-to-pulse disturbances energies ratio and the disturbances repetition frequency-to-data transmission rate ratio and also the dependence on the bits quantity in the packet. The numerical method allows one to assess the specific effect of the repetitive pulse disturbance influence on the digital devices functioning （the number of errors in transmitted data packets, transmission rate, etc.） depending on such factors as the repetition frequency, the disturbance waveform and duration, the mode of data coding, etc..展开更多
Non-metallic inclusions in steel are a significant challenge,affecting material properties and leading to issues such as stress concentration,cracking,and accelerated corrosion.Current methods for removing inclusions,...Non-metallic inclusions in steel are a significant challenge,affecting material properties and leading to issues such as stress concentration,cracking,and accelerated corrosion.Current methods for removing inclusions,including bubble,electromagnetic stirring,filtration separation,fluid flow,and sedimentation,often struggle with the removal of fine inclusions.Apart from these known methods,pulsed electric current(PEC),as an emerging technology,has demonstrated immense potential and environmental advantages.PEC offers adjustable current parameters and simple equipment,making it an attractive alternative to traditional methods.Its green energy-saving features and excellent results in regulating inclusion morphology and migration,as well as inhibiting submerged entry nozzle(SEN)clogging,make it a promising technology.In comparison to continuous current technology,PEC has shown significant advantages in regulating inclusions,not only improving purification efficiency but also demonstrating outstanding performance in flow stability and energy consumption.The ability of PEC to efficiently reduce inclusion numbers enhances the purity and quality of molten steel,improving its mechanical properties.Currently,the theoretical basis for controlling the movement of inclusions by current is mainly composed of three major theories:the double electric layer theory,electromagnetic force reverse separation theory,and electric free energy drive theory.These theories together form an important framework for researchers to understand and optimize the behavior of impurity movement controlled by electric current.Looking ahead,PEC is expected to pave the way for new solutions in directional regulation of inclusion migration,efficient inclusion removal,SEN clogging prevention,and the purification of molten steel.展开更多
Objective: to explore the application effect of low frequency electrical stimulation pulse intervention combined with manual massage nursing in postpartum pubic combined separation. Methods: 58 postpartum combined pub...Objective: to explore the application effect of low frequency electrical stimulation pulse intervention combined with manual massage nursing in postpartum pubic combined separation. Methods: 58 postpartum combined pubic bone separation women admitted from June 2019 to December 2021 were selected and grouped by clinic order number. Control group: conventional intervention, observation group: low-frequency electrical stimulation pulse intervention and manual massage intervention. The nursing effect, pain score, pubic joint distance, quality of life, satisfaction, and clinical indicators were observed. Results: the total effectiveness of the observation group and the control group was, respectively, as follows: 96.55%, 79.31%, and P < 0.05. The corresponding data of pain score and pubic distance in the observation group were all smaller after the intervention, P < 0.05. The observation group each quality of life index was higher by intervention than the control group, P < 0.05. The total satisfaction rates of the observation group and the control group were, respectively: 96.55%, 75.86%, and P < 0.05. The hospitalization and ambulation were shorter than the control group, P < 0.05. Conclusion: the intervention of low-frequency electrical stimulation pulse is helpful to accelerate the speed of maternal rehabilitation, and is important to relieve the pain and optimize the quality of life. The corresponding effect is good, and the overall prognosis is relatively optimistic. This method is worthy of further praise and development.展开更多
Traditional heat treatment methods require a significant amount of time and energy to affect atomic diffusion and enhance the spheroidization process of carbides in bearing steel,while pulsed current can accelerate at...Traditional heat treatment methods require a significant amount of time and energy to affect atomic diffusion and enhance the spheroidization process of carbides in bearing steel,while pulsed current can accelerate atomic diffusion to achieve ultra-fast spheroidization of carbides.However,the understanding of the mechanism by which different pulse current parameters regulate the dissolution behavior of carbides requires a large amount of experimental data to support,which limits the application of pulse current technology in the field of heat treatment.Based on this,quantify the obtained pulse current processing data to create an important dataset that could be applied to machine learning.Through machine learning,the mechanism of mutual influence between carbide regulation and various factors was elucidated,and the optimal spheroidization process parameters were determined.Compared to the 20 h required for traditional heat treatment,the application of pulsed electric current technology achieved ultra-fast spheroidization of GCr15 bearing steel within 90 min.展开更多
In this work,we aim to develop a novel post-treatment process combining cryogenic and pulsed electric field treatment to enhance WC-Co cemented carbides.The results show a 15.62%increase in hardness from 1831.38 to 21...In this work,we aim to develop a novel post-treatment process combining cryogenic and pulsed electric field treatment to enhance WC-Co cemented carbides.The results show a 15.62%increase in hardness from 1831.38 to 2117.38 HV30,a 9.60%rise in fracture toughness from 9.06 to 9.93 MPa·m^(1/2),while the friction coefficient decreases from 0.63 to 0.47.Through the residual stress evolution,WC orientation change and the martensitic transformation of Co,and the internal enhancement mechanism of cryogenic combined with pulsed electric field treatment are revealed.The electron wind generated by the pulsed electric field can efficiently reduce the residual stress induced by cryogenic process.The evolution of residual stress promotes the base slip of WC,increasing the degree of{0001}orientation.In addition,the degree of martensitic transformation of Co intensifies,with the hcp-Co/fcc-Co ratio rising from 0.41%to 17.86%.The enhanced WC{0001}orientation and increased hcp-Co content contribute to significant improvements in hardness and wear resistance.This work provides a novel efficient enhancement strategy for ceramics and alloys,with the potential to be a mainstream strengthening method in the future.展开更多
The reactor pressure vessel(RPV)is susceptible to brittle fracture due to the influence of ion irradiation and high temperature,which presents a significant risk to the safe operation of nuclear reactors.It has been d...The reactor pressure vessel(RPV)is susceptible to brittle fracture due to the influence of ion irradiation and high temperature,which presents a significant risk to the safe operation of nuclear reactors.It has been demonstrated that pulsed electric current can effectively address the issue of embrittlement in RPV steel.However,the relationship between pulse parameters(duty ratio,frequency,current,and time)and the effectiveness of pulse current processing has not been systematically studied.The application of machine learning methods enables autonomous exploration and learning of the relationship between data.Consequently,this study proposes a machine learning method based on the random forest model to establish the relationship between the parameters of electrical pulses and the repair effect of RPV steel.A generative adversarial network is employed to enhance data diversity and scalability,while a particle swarm optimization algorithm is utilized to optimize the initialization weights and biases of the random forest model,aiming to improve the model’s fitting ability and training performance.The results indicate that the coefficient of determination R-square(R^(2)),root mean squared error and mean absolute error values are 0.934,0.045,and 0.036,respectively,suggesting that the model has the potential to predict the performance recovery of RPV steel after pulsed electric field treatment.The prediction of the impact of pulse current parameters on the repair effect will help to enhance and optimize the repair process,thereby providing a scientific basis for pulse current repair processing.展开更多
A mathematical model considering free nuclei was developed to reveal the migration behavior of the free nuclei. Numerical simulation results show that most of the nuclei on the top surface of the melt move downwards a...A mathematical model considering free nuclei was developed to reveal the migration behavior of the free nuclei. Numerical simulation results show that most of the nuclei on the top surface of the melt move downwards and distribute randomly inside the Al melt, which induces more nucleation sites resulting in grain refinement. At the same time, the effect of nuclei size on the nuclei distribution and refinement employing electric current pulse （ECP） was also investigated. The smaller nuclei migrate a short distance with the Al melt at lower speed. But for the larger nuclei, the migration downwards with higher speed benefits the refinement of interior grains of the melt. The research results help to better understand the refinement process and provide a more reasonable explanation of the grain refinement mechanism using ECP.展开更多
The application of electric current pulse（ECP） to a solidification process refers to the immersion of electrodes into the liquid metal and the employment of thermal insulators on the upper surface of metal.In order ...The application of electric current pulse（ECP） to a solidification process refers to the immersion of electrodes into the liquid metal and the employment of thermal insulators on the upper surface of metal.In order to ascertain the effects of these two factors on the structure refinement by the ECP technique,three groups of experiments were performed with different types of electrodes or various thermal insulators.By the comparison between solidification structures under different conditions,it is followed that the electrode and the thermal insulator have an obvious influence on the grain refinement under an applied ECP,and further analysis demonstrates that the thermal conditions of the liquid surface play a vital role in the modification of solidification structure.Also,the results support the viewpoint that most of the equiaxed grains originate from the liquid surface subjected to an ECP.展开更多
The electric pulse modification （EP, EPM） of liquid metal is a novel method for grain refinement. The structure of EP-modified Al-5%Cu melt was characterized by high-temperature X-ray diffractometry. The results sho...The electric pulse modification （EP, EPM） of liquid metal is a novel method for grain refinement. The structure of EP-modified Al-5%Cu melt was characterized by high-temperature X-ray diffractometry. The results show that the Cu-containing Al clusters remarkably increase in the EP-modified melt, furthermore, these clusters in that case tend to contract due to the decrease of relevant atomic radius and the co-ordination number. This kind of liquid-phase structure leads to a more homogeneous Cu-rich phase distribution in the final solidification structure. Differential scanning calorimetry （DSC） tests indicate that the solidification super-cooling degree of the EP-modified liquid phase is 2.36 times that of the unmodified. These facts suggest that the atom cluster changes in EP-modified Al-5%Cu melt would disagree with that by EPM model previously proposed in liquid pure metal.展开更多
The electropulsing process can be used to tailor the microstructure and deformability of metallic glasses(MGs).Here,we report the microstructural origin of enhanced electroplasticity of monatomic Ta MG nanowires.Under...The electropulsing process can be used to tailor the microstructure and deformability of metallic glasses(MGs).Here,we report the microstructural origin of enhanced electroplasticity of monatomic Ta MG nanowires.Under electromechanical loading,the Ta MG nanowire exhibits improved ductility and ob-vious necking behavior.By evaluating the dynamic structural evolution via in situ diffraction,it is found that the atomic mobility in flow units of Ta MG can be improved significantly under the stimulation of pulse current,mainly through the athermal electron-atom interaction,which results in the fast annihila-tion of flow units and,thereby,fast structural relaxation.These structural evolution processes can help to eliminate the formation of the obvious shear band.These findings provide insight into the origin of elec-troplasticity in amorphous materials,which is of scientific and technological significance for the design and processing of a variety of MGs.展开更多
The heredity of aluminum melt under the action of pulse electric field was investigated by means of the remelt experiment. A new hereditary criterion under this condition was proposed; in the meantime, the differentia...The heredity of aluminum melt under the action of pulse electric field was investigated by means of the remelt experiment. A new hereditary criterion under this condition was proposed; in the meantime, the differential transferability of genetic carrier in activated melt among filial generations was validated with the aid of DSC.展开更多
The number of liver cancer patients is likely to continue to increase in the coming decades due to the aging of the population and changing risk factors.Traditional treatments cannot meet the needs of all patients.New...The number of liver cancer patients is likely to continue to increase in the coming decades due to the aging of the population and changing risk factors.Traditional treatments cannot meet the needs of all patients.New treatment methods evolved from pulsed electric field ablation are expected to lead to breakthroughs in the treatment of liver cancer.This paper reviews the safety and efficacy of irreversible electroporation in clinical studies,the methods to detect and evaluate its ablation effect,the improvements in equipment and its antitumor effect,and animal and clinical trials on electrochemotherapy.We also summarize studies on the most novel nanosecond pulsed electric field ablation techniques in vitro and in vivo.These research results are certain to promote the progress of pulsed electric field in the treatment of liver cancer.展开更多
The effect of electric pulse modifying on the solidification structure of an Al-15%Si alloy was investigated. The result shows that the primary silicon disappears sometimes and the eutectic phase is refined after the ...The effect of electric pulse modifying on the solidification structure of an Al-15%Si alloy was investigated. The result shows that the primary silicon disappears sometimes and the eutectic phase is refined after the treatrnent of EP （electric pulse） though there are different modalities in different treating durations. DSC （differential scanning calorimetry） analysis indicates that the super-cooling texture decreases and the freezing range narrows evidently after the electric pulse treatment.展开更多
In this work, low-density electric current pulse （ECP） has been applied to submerged entry nozzle （SEN） and its effect on the morphology of the inclusion buildup and the distribution of the inclusions in slab has ...In this work, low-density electric current pulse （ECP） has been applied to submerged entry nozzle （SEN） and its effect on the morphology of the inclusion buildup and the distribution of the inclusions in slab has been explored. The results reveal that under the unique effects of ECP, part of small inclusions less than 10 μm is expelled through the boundary layer along the current direction to form dense inclusion buildup. This method is of great potential to prolong the service life of SEN and improve the quality of the steel product.展开更多
A new approach to applying the electric current pulse （ECP） with parallel electrodes to the promotion of the transition from columnar crystal to equiaxed crystal and the improvement of macrosegregation was introduce...A new approach to applying the electric current pulse （ECP） with parallel electrodes to the promotion of the transition from columnar crystal to equiaxed crystal and the improvement of macrosegregation was introduced. The ECP was applied to different stages of the solidification. The results showed that the application of the ECP in both the initial stage （the thickness of solidified shell reached 2 mm approximately） and the late stage （the thickness of solidified shell reached 14 mm approximately） of solidification can promote the columnar to equiaxed transition （CET）. The analysis showed that during solidification, a large number of nuclei around the upper surface fell off due to ECP, which subsequently showered on the melt and impinged the growth front of the columnar crystal. Therefore, the CEToccurred. In addition, this method was also employed to influence the solidification process of bearing steel, and the results showed that the structure was changed from columnar crystal to equiaxed crystal, indicating that ECP can enhance the homogeneity of structure and composition of bearing steel.展开更多
The metallographic structure of LM-29 aluminum-silicon alloy modified by electric pulse treatment has been investigated and compared with those untreated.The solidification structure of LM-29 alloy has been analyzed b...The metallographic structure of LM-29 aluminum-silicon alloy modified by electric pulse treatment has been investigated and compared with those untreated.The solidification structure of LM-29 alloy has been analyzed by means of M1AP3 Quantimet image processing and analysis system,and then the solidification process has been analyzed by means of differential scanning calorimetry(DSC).The results indicate that the primary silicon phase was refined remarkably by electric pulse while the tensile strength and elongation properties increased accordingly.Electric pulse treatment can also increase the binding power between silicon clusters and alloy melt matrix,as a result,the precipitation of primary silicon phase is suppressed to meet the demand of supercooling degree for nucleating,correspondingly.The electric pulse modification has great influence on the size of silicon atomic cluster as well as its distribution in the melt,subsequently,leads to the refinement of solidification structure.展开更多
基金the National Natural Science Foundation of China(Nos.50975174 and 51275297)
文摘The purpose of this research is to explore the feasibility of roller hemming of AZ31 B magnesium alloy sheet. During the test, a special experimental setup considering the current flow and insulation was designed and employed. For the sake of simplicity, the flat surface-straight edge hemming style was selected. Electrical pulses were introduced in the pre-hemming and final hemming processes. The results show that when hemming at 448 K with hemming speed of 30 mm/min, AZ31 B magnesium alloy sheet was successfully hemmed with excellent perceived quality. No recoil/warp defect, cracking or springback was observed. Electrical pulses induced dynamic recrystallized grains were observed along the grain boundaries in the severely deformed area, which is of great importance to the improvement of the ductility of the material. The hardness was slightly increased after hemming with electrical pulses, and this fact could improve the friction resistance performance of the hemmed part.
基金financially supported by the National Natural Science Foundation of China(Grant no.52274173).
文摘Improving the permeability of coal seam is the key factor to realize efficient and safe mining of coalbed gas.In order to study the effect of high-voltage pulse breakdown on coal permeability,the multi-field coupling high-voltage pulse crack coal permeability test equipment was used to carry out breakdown tests on bituminous coal samples soaked in conductive fluid under different voltage conditions.Subsequently,the breakdown effect of high voltage electrical pulse was characterized by comparison of breakdown energy,coal sample permeability and pore distribution,and the mechanism of voltage effect and the concentration of conductive liquid on the cracking effect was explored.The results show that the higher the pulse voltage,the faster the formation rate of plasma channel in coal and the more obvious the breakdown effect.With the increase of pulse voltage,the increment of coal porosity first increases and then decreases,the maximum increase is 31.4%,and the cracking effect is obvious.By comparing the changes of permeability and pore distribution of coal samples before and after pulse voltage treatment,it is found that conductive liquid can improve the conductivity in fragile cracks,crack growth and pore connectivity under pulse voltage.This paper provides a basis for high voltage electric pulse as a method to enhance coal permeability.
基金supported by the National Key Research and Development Program of China(No.2024YFC3013804)the National Natural Science Foundation of China(No.52274173)the Open Fund of State Key Laboratory of Coal Mine Disaster Dynamics and Control(No.2011DA105287-FW202305)。
文摘In this study,to investigate the mechanism through which high-voltage electrical pulses(HVEPs)enhance coal permeability and improve coalbed methane(CBM)extraction efficiency,liquid nitrogen adsorption analysis,nuclear magnetic resonance,infrared spectroscopy,and scanning electron microscopy were performed on HVEPtreated coal samples.The mentioned techniques were used to analyze the crack structures,pore distribution patterns,and changes in the chemical functional groups in the coal samples.The permeability enhancement mechanism of HVEP in coal was explored from macroscopic,mesoscopic,and microscopic perspectives.The chemical modification of coal through the breakdown of its oxygen-containing functional groups reduced the gas adsorption capacity of the coal samples and enhanced their desorption abilities.Simultaneously,the number of pores within the bottleneck pore interval of the coal samples increased significantly.The closed pores transformed into semi-closed and open pores.The pore volume was 2.86 times the pore volume of the original coal,while the pore specific surface area growth rate was 48.67%.This pronounced pore expansion effect eliminated the bottleneck pore interval,which reduced CBM seepage efficiency and enabled cross-scale CBM transport.Extensive parallel fractures and fissures appeared throughout the coal body.The connectivity within the porefracture network was enhanced substantially.This improved connectivity provided efficient pathways for gas transport.
基金supported by the Key Scientific and Technological Program of Linyi City of China,No.201313026
文摘Most studies on peripheral nerve injury have focused on repair at the site of injury, but very few have examined the effects of repair strategies on the more proximal neuronal cell bodies. In this study, an approximately 10-mm-long nerve segment from the ischial tuberosity in the rat was transected and its proximal and distal ends were inverted and sutured. The spinal cord was subjected to pulsed electrical stimulation at T10 and L3, at a current of 6.5 m A and a stimulation frequency of 15 Hz, 15 minutes per session, twice a day for 56 days. After pulsed electrical stimulation, the number of neurons in the dorsal root ganglion and anterior horn was increased in rats with sciatic nerve injury. The number of myelinated nerve fibers was increased in the sciatic nerve. The ultrastructure of neurons in the dorsal root ganglion and spinal cord was noticeably improved. Conduction velocity of the sciatic nerve was also increased. These results show that pulsed electrical stimulation protects sensory neurons in the dorsal root ganglia as well as motor neurons in the anterior horn of the spinal cord after peripheral nerve injury, and that it promotes the regeneration of peripheral nerve fibers.
文摘Two methods of calculating the parameters and characterizing the degree of pulse electrical disturbances influence on digital devices functioning, both analytical and numerical, are considered here. The analytical method permits one to assess the error occurrence probability in transmitting the data packets considering the dependence on the signal pulses energies-to-pulse disturbances energies ratio and the disturbances repetition frequency-to-data transmission rate ratio and also the dependence on the bits quantity in the packet. The numerical method allows one to assess the specific effect of the repetitive pulse disturbance influence on the digital devices functioning （the number of errors in transmitted data packets, transmission rate, etc.） depending on such factors as the repetition frequency, the disturbance waveform and duration, the mode of data coding, etc..
基金supported by the Fundamental Research Funds for the Central Universities(No.FRF-BD-23-01).
文摘Non-metallic inclusions in steel are a significant challenge,affecting material properties and leading to issues such as stress concentration,cracking,and accelerated corrosion.Current methods for removing inclusions,including bubble,electromagnetic stirring,filtration separation,fluid flow,and sedimentation,often struggle with the removal of fine inclusions.Apart from these known methods,pulsed electric current(PEC),as an emerging technology,has demonstrated immense potential and environmental advantages.PEC offers adjustable current parameters and simple equipment,making it an attractive alternative to traditional methods.Its green energy-saving features and excellent results in regulating inclusion morphology and migration,as well as inhibiting submerged entry nozzle(SEN)clogging,make it a promising technology.In comparison to continuous current technology,PEC has shown significant advantages in regulating inclusions,not only improving purification efficiency but also demonstrating outstanding performance in flow stability and energy consumption.The ability of PEC to efficiently reduce inclusion numbers enhances the purity and quality of molten steel,improving its mechanical properties.Currently,the theoretical basis for controlling the movement of inclusions by current is mainly composed of three major theories:the double electric layer theory,electromagnetic force reverse separation theory,and electric free energy drive theory.These theories together form an important framework for researchers to understand and optimize the behavior of impurity movement controlled by electric current.Looking ahead,PEC is expected to pave the way for new solutions in directional regulation of inclusion migration,efficient inclusion removal,SEN clogging prevention,and the purification of molten steel.
文摘Objective: to explore the application effect of low frequency electrical stimulation pulse intervention combined with manual massage nursing in postpartum pubic combined separation. Methods: 58 postpartum combined pubic bone separation women admitted from June 2019 to December 2021 were selected and grouped by clinic order number. Control group: conventional intervention, observation group: low-frequency electrical stimulation pulse intervention and manual massage intervention. The nursing effect, pain score, pubic joint distance, quality of life, satisfaction, and clinical indicators were observed. Results: the total effectiveness of the observation group and the control group was, respectively, as follows: 96.55%, 79.31%, and P < 0.05. The corresponding data of pain score and pubic distance in the observation group were all smaller after the intervention, P < 0.05. The observation group each quality of life index was higher by intervention than the control group, P < 0.05. The total satisfaction rates of the observation group and the control group were, respectively: 96.55%, 75.86%, and P < 0.05. The hospitalization and ambulation were shorter than the control group, P < 0.05. Conclusion: the intervention of low-frequency electrical stimulation pulse is helpful to accelerate the speed of maternal rehabilitation, and is important to relieve the pain and optimize the quality of life. The corresponding effect is good, and the overall prognosis is relatively optimistic. This method is worthy of further praise and development.
基金supported by the National Key R&D Program of China(2020YFA0714900,2023YFB3709903)the National Natural Science Foundation of China(U21B2082,52474410)+6 种基金the Key R&D Program of Shandong Province,China(2023CXGC010406)the Scientific Research Special Project for First-Class Disciplines in Inner Mongolia Autonomous Region(YLXKZX-NKD-001)the International Science and Technology Cooperation Project of Higher Education Institutions in Inner Mongolia Autonomous Region(GHXM-002)the Natural Science Foundation of Inner Mongolia Autonomous Region of China(2024ZD06)the Technology Support Project for the Construction of Major Innovation Platforms in Inner Mongolia Autonomous Region(XM2024XTGXQ16)the Beijing Municipal Natural Science Foundation(2222065)the Fundamental Research Funds for the Central Universities(FRF-TP-22-02C2).
文摘Traditional heat treatment methods require a significant amount of time and energy to affect atomic diffusion and enhance the spheroidization process of carbides in bearing steel,while pulsed current can accelerate atomic diffusion to achieve ultra-fast spheroidization of carbides.However,the understanding of the mechanism by which different pulse current parameters regulate the dissolution behavior of carbides requires a large amount of experimental data to support,which limits the application of pulse current technology in the field of heat treatment.Based on this,quantify the obtained pulse current processing data to create an important dataset that could be applied to machine learning.Through machine learning,the mechanism of mutual influence between carbide regulation and various factors was elucidated,and the optimal spheroidization process parameters were determined.Compared to the 20 h required for traditional heat treatment,the application of pulsed electric current technology achieved ultra-fast spheroidization of GCr15 bearing steel within 90 min.
基金supported by the National Natural Science Foundation of China(Nos.U21A20399 and 52274407)Liaoning Province Applied Basic Research Program(No.2022JH2/101300212).
文摘In this work,we aim to develop a novel post-treatment process combining cryogenic and pulsed electric field treatment to enhance WC-Co cemented carbides.The results show a 15.62%increase in hardness from 1831.38 to 2117.38 HV30,a 9.60%rise in fracture toughness from 9.06 to 9.93 MPa·m^(1/2),while the friction coefficient decreases from 0.63 to 0.47.Through the residual stress evolution,WC orientation change and the martensitic transformation of Co,and the internal enhancement mechanism of cryogenic combined with pulsed electric field treatment are revealed.The electron wind generated by the pulsed electric field can efficiently reduce the residual stress induced by cryogenic process.The evolution of residual stress promotes the base slip of WC,increasing the degree of{0001}orientation.In addition,the degree of martensitic transformation of Co intensifies,with the hcp-Co/fcc-Co ratio rising from 0.41%to 17.86%.The enhanced WC{0001}orientation and increased hcp-Co content contribute to significant improvements in hardness and wear resistance.This work provides a novel efficient enhancement strategy for ceramics and alloys,with the potential to be a mainstream strengthening method in the future.
基金financially supported by the National Natural Science Foundation of China(U21B2082,52474410)the National Key R&D Program of China(2023YFB3709903,2020 YFA0714900)+5 种基金the Key R&D Program of Shandong Province,China(2023CXGC010406)the Scientific Research Special Project for First-Class Disciplines in Inner Mongolia Autonomous Region(YLXKZXNKD-001)the Natural Science Foundation of Inner Mongolia Autonomous Region of China(2024ZD06)the Technology Support Project for the Construction of Major Innovation Platforms in Inner Mongolia Autonomous Region(XM2024XTGXQ16)the Beijing Municipal Natural Science Foundation(2222065)the Fundamental Research Funds for the Central Universities(FRF-TP-22-02C2).
文摘The reactor pressure vessel(RPV)is susceptible to brittle fracture due to the influence of ion irradiation and high temperature,which presents a significant risk to the safe operation of nuclear reactors.It has been demonstrated that pulsed electric current can effectively address the issue of embrittlement in RPV steel.However,the relationship between pulse parameters(duty ratio,frequency,current,and time)and the effectiveness of pulse current processing has not been systematically studied.The application of machine learning methods enables autonomous exploration and learning of the relationship between data.Consequently,this study proposes a machine learning method based on the random forest model to establish the relationship between the parameters of electrical pulses and the repair effect of RPV steel.A generative adversarial network is employed to enhance data diversity and scalability,while a particle swarm optimization algorithm is utilized to optimize the initialization weights and biases of the random forest model,aiming to improve the model’s fitting ability and training performance.The results indicate that the coefficient of determination R-square(R^(2)),root mean squared error and mean absolute error values are 0.934,0.045,and 0.036,respectively,suggesting that the model has the potential to predict the performance recovery of RPV steel after pulsed electric field treatment.The prediction of the impact of pulse current parameters on the repair effect will help to enhance and optimize the repair process,thereby providing a scientific basis for pulse current repair processing.
基金Project(SELF-2011-01)supported by the Open Project of Shanghai Key Laboratory of Modern Metallurgy and Materials Processing,ChinaProjects(51204109,51035004)supported by the National Natural Science Foundation of China
文摘A mathematical model considering free nuclei was developed to reveal the migration behavior of the free nuclei. Numerical simulation results show that most of the nuclei on the top surface of the melt move downwards and distribute randomly inside the Al melt, which induces more nucleation sites resulting in grain refinement. At the same time, the effect of nuclei size on the nuclei distribution and refinement employing electric current pulse （ECP） was also investigated. The smaller nuclei migrate a short distance with the Al melt at lower speed. But for the larger nuclei, the migration downwards with higher speed benefits the refinement of interior grains of the melt. The research results help to better understand the refinement process and provide a more reasonable explanation of the grain refinement mechanism using ECP.
基金Project(2009AA03Z110) supported by the National High Technology Research and Development Program of ChinaProject (2011CB012902) supported by the National Basic Research Program of China
文摘The application of electric current pulse（ECP） to a solidification process refers to the immersion of electrodes into the liquid metal and the employment of thermal insulators on the upper surface of metal.In order to ascertain the effects of these two factors on the structure refinement by the ECP technique,three groups of experiments were performed with different types of electrodes or various thermal insulators.By the comparison between solidification structures under different conditions,it is followed that the electrode and the thermal insulator have an obvious influence on the grain refinement under an applied ECP,and further analysis demonstrates that the thermal conditions of the liquid surface play a vital role in the modification of solidification structure.Also,the results support the viewpoint that most of the equiaxed grains originate from the liquid surface subjected to an ECP.
基金Project(51074087)supported by the National Natural Science Foundation of ChinaProject(201102088)supported by the Natural Science Foundation of Liaoning Province,China+1 种基金Project(LJQ2011065)supported by Liaoning Excellent Talents in University,ChinaProject(2010921096)supported by Liaoning Baiqianwan Talents Program,China
文摘The electric pulse modification （EP, EPM） of liquid metal is a novel method for grain refinement. The structure of EP-modified Al-5%Cu melt was characterized by high-temperature X-ray diffractometry. The results show that the Cu-containing Al clusters remarkably increase in the EP-modified melt, furthermore, these clusters in that case tend to contract due to the decrease of relevant atomic radius and the co-ordination number. This kind of liquid-phase structure leads to a more homogeneous Cu-rich phase distribution in the final solidification structure. Differential scanning calorimetry （DSC） tests indicate that the solidification super-cooling degree of the EP-modified liquid phase is 2.36 times that of the unmodified. These facts suggest that the atom cluster changes in EP-modified Al-5%Cu melt would disagree with that by EPM model previously proposed in liquid pure metal.
基金supported by the open research fund of Songshan Lake Materials Laboratory(No.2021SLABFN15)the National Natural Science Foundation of China(No.52071284)+1 种基金the Zhejiang Provincial Natural Science Foundation of China(No.LR24E010002)the Zhejiang University Global Partnership Fund.
文摘The electropulsing process can be used to tailor the microstructure and deformability of metallic glasses(MGs).Here,we report the microstructural origin of enhanced electroplasticity of monatomic Ta MG nanowires.Under electromechanical loading,the Ta MG nanowire exhibits improved ductility and ob-vious necking behavior.By evaluating the dynamic structural evolution via in situ diffraction,it is found that the atomic mobility in flow units of Ta MG can be improved significantly under the stimulation of pulse current,mainly through the athermal electron-atom interaction,which results in the fast annihila-tion of flow units and,thereby,fast structural relaxation.These structural evolution processes can help to eliminate the formation of the obvious shear band.These findings provide insight into the origin of elec-troplasticity in amorphous materials,which is of scientific and technological significance for the design and processing of a variety of MGs.
基金Item Sponsored by National Natural Science Foundation of China(50174028and50674054)
文摘The heredity of aluminum melt under the action of pulse electric field was investigated by means of the remelt experiment. A new hereditary criterion under this condition was proposed; in the meantime, the differential transferability of genetic carrier in activated melt among filial generations was validated with the aid of DSC.
基金Supported by the National Science and Technology Major Project of China,No.2018ZX10301201 and No.2017ZX10302201National Key Research and Development Program of China,No.2018YFC2000500。
文摘The number of liver cancer patients is likely to continue to increase in the coming decades due to the aging of the population and changing risk factors.Traditional treatments cannot meet the needs of all patients.New treatment methods evolved from pulsed electric field ablation are expected to lead to breakthroughs in the treatment of liver cancer.This paper reviews the safety and efficacy of irreversible electroporation in clinical studies,the methods to detect and evaluate its ablation effect,the improvements in equipment and its antitumor effect,and animal and clinical trials on electrochemotherapy.We also summarize studies on the most novel nanosecond pulsed electric field ablation techniques in vitro and in vivo.These research results are certain to promote the progress of pulsed electric field in the treatment of liver cancer.
基金This work is financially supported by the National High Technology Research and Development Program of China (No.2001AA337040).
文摘The effect of electric pulse modifying on the solidification structure of an Al-15%Si alloy was investigated. The result shows that the primary silicon disappears sometimes and the eutectic phase is refined after the treatrnent of EP （electric pulse） though there are different modalities in different treating durations. DSC （differential scanning calorimetry） analysis indicates that the super-cooling texture decreases and the freezing range narrows evidently after the electric pulse treatment.
基金financially supported by the National Natural Science Foundation of China(No.51304039)the Fundamental Research Funds for the Central Universities(Nos.N110402008 and N130402021)Meishan Steel Plant Research Fund
文摘In this work, low-density electric current pulse （ECP） has been applied to submerged entry nozzle （SEN） and its effect on the morphology of the inclusion buildup and the distribution of the inclusions in slab has been explored. The results reveal that under the unique effects of ECP, part of small inclusions less than 10 μm is expelled through the boundary layer along the current direction to form dense inclusion buildup. This method is of great potential to prolong the service life of SEN and improve the quality of the steel product.
基金Item Sponsored by National Natural Science Foundation of China(50674064,50734008)
文摘A new approach to applying the electric current pulse （ECP） with parallel electrodes to the promotion of the transition from columnar crystal to equiaxed crystal and the improvement of macrosegregation was introduced. The ECP was applied to different stages of the solidification. The results showed that the application of the ECP in both the initial stage （the thickness of solidified shell reached 2 mm approximately） and the late stage （the thickness of solidified shell reached 14 mm approximately） of solidification can promote the columnar to equiaxed transition （CET）. The analysis showed that during solidification, a large number of nuclei around the upper surface fell off due to ECP, which subsequently showered on the melt and impinged the growth front of the columnar crystal. Therefore, the CEToccurred. In addition, this method was also employed to influence the solidification process of bearing steel, and the results showed that the structure was changed from columnar crystal to equiaxed crystal, indicating that ECP can enhance the homogeneity of structure and composition of bearing steel.
基金supported by the National Natural Science Foundation of China (No. 50674054)the Doctorate Foundation of Science and Technology Department,Liaoning Province (20081097)
文摘The metallographic structure of LM-29 aluminum-silicon alloy modified by electric pulse treatment has been investigated and compared with those untreated.The solidification structure of LM-29 alloy has been analyzed by means of M1AP3 Quantimet image processing and analysis system,and then the solidification process has been analyzed by means of differential scanning calorimetry(DSC).The results indicate that the primary silicon phase was refined remarkably by electric pulse while the tensile strength and elongation properties increased accordingly.Electric pulse treatment can also increase the binding power between silicon clusters and alloy melt matrix,as a result,the precipitation of primary silicon phase is suppressed to meet the demand of supercooling degree for nucleating,correspondingly.The electric pulse modification has great influence on the size of silicon atomic cluster as well as its distribution in the melt,subsequently,leads to the refinement of solidification structure.
