Objective:To gain insight into the potential factors that may cause perceived stress and anxiety in simulation education.Methods:A secondary qualitative analysis study using qualitative thematic synthesis.A local high...Objective:To gain insight into the potential factors that may cause perceived stress and anxiety in simulation education.Methods:A secondary qualitative analysis study using qualitative thematic synthesis.A local higher education institution that conducted pre-registration nursing programs.A total of 189 undergraduate nursing students that were never attained any clinical placement prior to the parent study.Focus group interviews were conducted to collect data that were then transcribed and analyzed through the qualitative thematic synthesis approach to develop themes.Results:Three themes were emerged from the participants’simulation experiences in terms of peoples(the observers vs the observed),actions(the prepared vs the unprepared),and settings(the realism vs the simulation).Conclusions:By considering and reviewing the current design and development of the simulation practice,the findings of this study contribute to the body of knowledge with valuable insights on stress and anxiety that may affect students’learning in simulation.展开更多
Background:High-fidelity simulation has been demonstrated to make great progress in learning.However,there is still ongoing exploration on how to fully harness the advantages of this teaching method and enhance its ef...Background:High-fidelity simulation has been demonstrated to make great progress in learning.However,there is still ongoing exploration on how to fully harness the advantages of this teaching method and enhance its effectiveness.This study conducted high-fidelity simulation in medical nursing based on the Healthcare Simulation Standards of Best Practice and evaluated its effect.Methods:The study was conducted from September 2019 to June 2020.A total of 82 undergraduate nursing students from a university in Shanghai participated in the high-fidelity simulation in medical nursing.The simulation design scale,educational practices in simulation scale,and students’satisfaction and self-confidence were used to evaluate the effect.Results:The mean score of simulation design scale was 4.06±0.63 with the mean scores of all dimensions being over 3.0.The mean score of educational practices in simulation scale was 4.14±0.56 with the mean scores of all dimensions being over 4.0.The mean scores of students’satisfaction and self-confidence were 4.07±0.72 and 3.89±0.58,respectively.Conclusion:Students reported high levels of simulation design and educational practices in simulation.They were also satisfied with learning and reported high levels of self-confidence.Some key points need to be considered so that the learning effects might be optimized.展开更多
Objective： Clinical reasoning is an essential feature of health care practice; it is also a crucial ability for providing patient care of high quality. It has been identified that graduate nurses may lack the clinica...Objective： Clinical reasoning is an essential feature of health care practice; it is also a crucial ability for providing patient care of high quality. It has been identified that graduate nurses may lack the clinical reasoning skills to deliver safe and effective patient cam. It is therefore of paramount importance to enhance nursing students＇ clinical reasoning ability. High-fidelity simulation （HFS） is proved to be an effective teaching and learning method, which may also have some advantages over other teaching methods. Methods： The authors retrospectively reviewed the related literature, illustrated the application of high-fidelity simulation teaching method in nursing education, putting the focus on the use of it in teaching with clinical reasoning. Results： The application of high-fidelity simulation to nursing education can simulate the clinical situation, thus to create a safe, continuous and efficient learning environment for students, and it can effectively improve students＇ clinical reasoning ability. Conclusions： high-fidelity simulation is effective for clinical reasoning teaching in nursing education. The extension of its application in China should be of great value. The relevant further study is suggested focusing on how to overcome its own limitations and have it better applied in nursing education in China.展开更多
Objective:To evaluate nursing students’assessment and communication skills through an objective structured clinical examination(OSCE)within a high-fidelity simulation using a student-simulated patient(SSP)and analyze...Objective:To evaluate nursing students’assessment and communication skills through an objective structured clinical examination(OSCE)within a high-fidelity simulation using a student-simulated patient(SSP)and analyze the validity,reliability,degree of difficulty,and discriminability of the OSCE.Methods:A descriptive study was conducted at one nursing school in Macao.All scenarios were designed using a high-fidelity simulator combined with SSPs.A convenience sample of 54 baccalaureate nursing students completed the OSCE.The nursing assessment OSCE checklist(NAOC)and the communication evaluation rubric(CER)were used as observational measurements with three-point Likert scales(2=Achieved,1=Partly achieved,0=Not completed/Incorrect).Results:Difficulty coefficients of the exam were 0.63 for nursing assessment skills and 0.56 for communication skills.The discrimination index of the majority items of the NAOC(86.4%)was>0.20,showing a better to good discriminability.The items of the CER had satisfactory indexes of item discrimination(from 0.38 to 0.84).Students received high scores in conducting blood oxygen saturation and cardiac and lung auscultation but low scores in vomiting and diarrhea assessment.Students presented good communication skills in eye contacting and listening,but culture assessment needs to be improved.The students with experiences in simulation or simulated patient(SP)interactions had better assessment and communication skills than students without those experiences.There was a positive relationship between nursing assessment and communication skills(r=0.67,P=0.000).Conclusions:SSPs were involved in enhancing the realism of interactions in simulated scenarios.Nursing students can conduct nursing assessments specific to patient conditions,explain the conditions to the patient,and ensure that the patient remains informed at all times of the precautions to be taken.However,students’cultural awareness and some communication skills need further training.With moderate difficulty and high discrimination index,OSCE showed satisfactory reliability and validity.展开更多
Objective The purpose of this study was to explore student perspectives of high-fidelity simulation.Methods A descriptive study with semi-structured focus group interviews was conducted in Macao.Twenty-one focus group...Objective The purpose of this study was to explore student perspectives of high-fidelity simulation.Methods A descriptive study with semi-structured focus group interviews was conducted in Macao.Twenty-one focus group interviews were held with 113 baccalaureate nursing students who had experienced 36-hour of simulation.Results Students perceived that simulation created a nonrisk learning environment,and was helpful in knowledge and skill enhancement and nurse role understanding.However,lack of realistic interactions in psychosocial responses made it difficult for students to relate simulation experience to real-working situations,and poor group contributions affected their learning.ConclusionInteracting with a human patient simulator does not replicate the experience of working with a live patient.Tutors need to come up with ideas about how to make scenarios more real and give more forthright responses to improve the realism of psychosocial responses during simulation.Students experienced uncertainty with clinical decision making and commented on the minimal contributions of some group members.Tutors should be prepared to provide students with substantial supports in developing their understanding of simulation and engaging in the learning process.展开更多
Objective:This study is aimed to develop student simulated patient(SSP)training content and evaluation indicators,and further explores their validity and reliabilities.Methods:Delphi consultations with 20 nursing expe...Objective:This study is aimed to develop student simulated patient(SSP)training content and evaluation indicators,and further explores their validity and reliabilities.Methods:Delphi consultations with 20 nursing exper ts were conducted.The weights of indicators were calculated through the analytic hierarchy process.SSP training was conducted with a high-fidelity nursing simulation.Results:The expert positive coefficients were 0.952 in the first round consultation and 1.00 in the second round consultation.The expert authority coefficient was reported as 0.87.The training included role and responsibility of simulated patient(SP),script interpretation,plot performance,and training for a rater,with a total of 17 indicators.SSP evaluation consisted of disease knowledge,role portrayal,and performance fidelity and since being a rater,it consists of 20 indicators in total.The coordination coefficients of two rounds of consultation ranged from 0.530 to 0.918.The content validity of SSP evaluation indicators was 0.95.The inter-rater reliability was repor ted as 0.866,and the internal consistency established using Cronbach’sαwas 0.727.Conclusions:Students as SPs should have first-hand knowledge and experience within the simulated scenarios.SSP training content and evaluation indicators were determined through the Delphi consensus combined with analytic hierarchy process.The evaluation indicators were valid and reliable,and provided the objective and quantifiable measurements for SSP training in nursing。展开更多
Because of the challenge of compounding lightweight,high-strength Ti/Al alloys due to their considerable disparity in properties,Al 6063 as intermediate layer was proposed to fabricate TC4/Al 6063/Al 7075 three-layer ...Because of the challenge of compounding lightweight,high-strength Ti/Al alloys due to their considerable disparity in properties,Al 6063 as intermediate layer was proposed to fabricate TC4/Al 6063/Al 7075 three-layer composite plate by explosive welding.The microscopic properties of each bonding interface were elucidated through field emission scanning electron microscope and electron backscattered diffraction(EBSD).A methodology combining finite element method-smoothed particle hydrodynamics(FEM-SPH)and molecular dynamics(MD)was proposed for the analysis of the forming and evolution characteristics of explosive welding interfaces at multi-scale.The results demonstrate that the bonding interface morphologies of TC4/Al 6063 and Al 6063/Al 7075 exhibit a flat and wavy configuration,without discernible defects or cracks.The phenomenon of grain refinement is observed in the vicinity of the two bonding interfaces.Furthermore,the degree of plastic deformation of TC4 and Al 7075 is more pronounced than that of Al 6063 in the intermediate layer.The interface morphology characteristics obtained by FEM-SPH simulation exhibit a high degree of similarity to the experimental results.MD simulations reveal that the diffusion of interfacial elements predominantly occurs during the unloading phase,and the simulated thickness of interfacial diffusion aligns well with experimental outcomes.The introduction of intermediate layer in the explosive welding process can effectively produce high-quality titanium/aluminum alloy composite plates.Furthermore,this approach offers a multi-scale simulation strategy for the study of explosive welding bonding interfaces.展开更多
Recent progress in microwave absorption materials stimulates the extensive exploration of rare earth oxide materials.Herein,we report the synthesis of a hollow sphere-based carbon material compounded with rare earth o...Recent progress in microwave absorption materials stimulates the extensive exploration of rare earth oxide materials.Herein,we report the synthesis of a hollow sphere-based carbon material compounded with rare earth oxides.Hollow N-doped carbon nano-spheres loaded ceria composites(H-NC@CeO_(2))were designed and prepared by the template method,combined with in-situ coating,pyrolysis and chemical etching.By controlling the loading content of H-NC@CeO_(2)and adjusting the impedance matching of the material,the H-NC@CeO_(2)/PS(polystyrene)composite exhibited a minimum reflection loss(RL)of-50.8 dB and an effective absorption band-width(EAB)of 4.64 GHz at a filler ratio of 20wt%and a thickness of 2 mm.In accordance with measured electromagnetic parameters,simulations using the high frequency structure simulator(HFSS)software were conducted to investigate the impact of the honeycomb structure on the electromagnetic wave performance of H-NC@CeO_(2)/PS.By calculating the surface electric field and the material’s bulk loss density,the mechanism of electromagnetic loss for the honeycomb structure was elaborated.A method for structural design and man-ufacturing of broadband absorbing devices was proposed and a broadband absorber with an EAB of 11.9 GHz was prepared.This study presents an innovative approach to designing advanced electromagnetic(EM)wave absorbing materials with broad absorption band-widths.展开更多
As coal mining depth increases,the combined effects of high stress,mining stress,and fault structures make dynamic impact hazards more frequent.The reproduction of dynamic impact phenomena is basis for studying their ...As coal mining depth increases,the combined effects of high stress,mining stress,and fault structures make dynamic impact hazards more frequent.The reproduction of dynamic impact phenomena is basis for studying their occurrence patterns and control mechanisms.Physical simulation test represents an efficacious methodology.However,there is currently a lack of simulation devices that can effectively simulate two types of dynamic impact phenomena,including high stress and fault slip dynamic impact.To solve aforementioned issues,the physical simulation test system for dynamic impact in deep roadways developed by authors is employed to carry out comparative tests of high stress and fault slip dynamic impact.The phenomena of high stress and fault slip dynamic impact are reproduced successfully.A comparative analysis is conducted on dynamic phenomena,stress evolution,roadway deformation,and support force.The high stress dynamic impact roadway instability mode,which is characterized by the release of high energy accompanied by symmetric damage,and the fault slip dynamic impact roadway instability mode,which is characterized by the propagation of unilateral stress waves accompanied by asymmetric damage,are clarified.On the basis,the differentiated control concepts for different types of dynamic impact in deep roadways are proposed.展开更多
Large size titanium alloy parts are widely used in aerospace.However,they are difficult to manufacture using mechanical cutting technology because of severe tool wear.Electrochemical jet machining is a promising techn...Large size titanium alloy parts are widely used in aerospace.However,they are difficult to manufacture using mechanical cutting technology because of severe tool wear.Electrochemical jet machining is a promising technology to achieve high efficiency,because it has high machining flexibility and no machining tool wear.However,reports on the macro electrochemical jet machining of large size titanium alloy parts are very scarce,because it is difficult to achieve effective constraint of the flow field in macro electrochemical jet machining.In addition,titanium alloy is very sensitive to fluctuation of the flow field,and a turbulent flow field would lead to serious stray corrosion.This paper reports a series of investigations of the electrochemical jet machining of titanium alloy parts.Based on the flow analysis and experiments,the machining flow field was effectively constrained.TB6 titanium alloy part with a perimeter of one meter was machined.The machined surface was smooth with no obvious machining defects.The machining process was particularly stable with no obvious spark discharge.The research provides a reference for the application of electrochemical jet machining technology to achieve large allowance material removal in the machining of large titanium alloy parts.展开更多
The pre-wetting of aggregate surface is a means to improve the interface performance of SBS modified asphalt and aggregate.The effect of pre-wetting technology on the interaction between SBS modified asphalt and aggre...The pre-wetting of aggregate surface is a means to improve the interface performance of SBS modified asphalt and aggregate.The effect of pre-wetting technology on the interaction between SBS modified asphalt and aggregate was analyzed by molecular dynamics simulation.The diffusion coefficient and concentration distribution of SBS modified asphalt on aggregate surface are included.The simulation results show that the diffusion coefficient of the aggregate surface of SBS modified asphalt is increased by 47.6%and 70.5%respectively after 110#asphalt and 130#asphalt are pre-wetted.The concentration distribution of SBS modified asphalt on the aggregate surface after pre-wetting is more uniform.According to the results of interface energy calculation,the interface energy of SBS modified bitumen and aggregate can be increased by about 5%after pre-wetting.According to the results of molecular dynamics simulation,the pre-wetting technology can effectively improve the interface workability of SBS modified bitumen and aggregate,so as to improve the interface performance.展开更多
Burial dissolution is a critical diagenetic process influencing ultra-deep carbonate reservoir development and preservation.Artificial carbonate samples with different internal structures were prepared,and high-temper...Burial dissolution is a critical diagenetic process influencing ultra-deep carbonate reservoir development and preservation.Artificial carbonate samples with different internal structures were prepared,and high-temperature and highpressure dissolution kinetic simulations were conducted.The results demonstrate that the intensity of burial dissolution is controlled by temperature and pressure,while tectonic-fluid activity influences the development pattern of burial dissolution,ultimately determining the direction of its differential modification.Extensive burial dissolution is likely to occur primarily at relatively shallow depths,significantly influencing reservoir formation,preservation,modification,and adjustment.The development of faults facilitates the maintenance of the intensity of burial dissolution.The maximum intensity of burial dissolution occurs at the tips and overlap zones of faults and intersections of multiple faults.The larger the scale of the faults,the more conducive it is to the development of burial dissolution.Burial dissolution fosters the formation of fault networks characterized by enhanced reservoir capacity and permeability.Burial dissolution controlled by episodic tectonic-fluid activity is a plausible explanation for forming the Tarim Basin's ultra-deep fault-controlled“stringbead-like”reservoirs.展开更多
Bedding parallel stepped rock slopes exist widely in nature and are used in slope engineering.They are characterized by complex topography and geological structure and are vulnerable to shattering under strong earthqu...Bedding parallel stepped rock slopes exist widely in nature and are used in slope engineering.They are characterized by complex topography and geological structure and are vulnerable to shattering under strong earthquakes.However,no previous studies have assessed the mechanisms underlying seismic failure in rock slopes.In this study,large-scale shaking table tests and numerical simulations were conducted to delineate the seismic failure mechanism in terms of acceleration,displacement,and earth pressure responses combined with shattering failure phenomena.The results reveal that acceleration response mutations usually occur within weak interlayers owing to their inferior performance,and these mutations may transform into potential sliding surfaces,thereby intensifying the nonlinear seismic response characteristics.Cumulative permanent displacements at the internal corners of the berms can induce quasi-rigid displacements at the external corners,leading to greater permanent displacements at the internal corners.Therefore,the internal corners are identified as the most susceptible parts of the slope.In addition,the concept of baseline offset was utilized to explain the mechanism of earth pressure responses,and the result indicates that residual earth pressures at the internal corners play a dominant role in causing deformation or shattering damage.Four evolutionary deformation phases characterize the processes of seismic responses and shattering failure of the bedding parallel stepped rock slope,i.e.the formation of tensile cracks at the internal corners of the berm,expansion of tensile cracks and bedding surface dislocation,development of vertical tensile cracks at the rear edge,and rock mass slipping leading to slope instability.Overall,this study provides a scientific basis for the seismic design of engineering slopes and offers valuable insights for further studies on preventing seismic disasters in bedding parallel stepped rock slopes.展开更多
基金supported by School Research Grant of Tung Wah College(SRG210401).
文摘Objective:To gain insight into the potential factors that may cause perceived stress and anxiety in simulation education.Methods:A secondary qualitative analysis study using qualitative thematic synthesis.A local higher education institution that conducted pre-registration nursing programs.A total of 189 undergraduate nursing students that were never attained any clinical placement prior to the parent study.Focus group interviews were conducted to collect data that were then transcribed and analyzed through the qualitative thematic synthesis approach to develop themes.Results:Three themes were emerged from the participants’simulation experiences in terms of peoples(the observers vs the observed),actions(the prepared vs the unprepared),and settings(the realism vs the simulation).Conclusions:By considering and reviewing the current design and development of the simulation practice,the findings of this study contribute to the body of knowledge with valuable insights on stress and anxiety that may affect students’learning in simulation.
基金supported by Fudan Good Practice Program of Teaching and Learning(2019C003).
文摘Background:High-fidelity simulation has been demonstrated to make great progress in learning.However,there is still ongoing exploration on how to fully harness the advantages of this teaching method and enhance its effectiveness.This study conducted high-fidelity simulation in medical nursing based on the Healthcare Simulation Standards of Best Practice and evaluated its effect.Methods:The study was conducted from September 2019 to June 2020.A total of 82 undergraduate nursing students from a university in Shanghai participated in the high-fidelity simulation in medical nursing.The simulation design scale,educational practices in simulation scale,and students’satisfaction and self-confidence were used to evaluate the effect.Results:The mean score of simulation design scale was 4.06±0.63 with the mean scores of all dimensions being over 3.0.The mean score of educational practices in simulation scale was 4.14±0.56 with the mean scores of all dimensions being over 4.0.The mean scores of students’satisfaction and self-confidence were 4.07±0.72 and 3.89±0.58,respectively.Conclusion:Students reported high levels of simulation design and educational practices in simulation.They were also satisfied with learning and reported high levels of self-confidence.Some key points need to be considered so that the learning effects might be optimized.
文摘Objective： Clinical reasoning is an essential feature of health care practice; it is also a crucial ability for providing patient care of high quality. It has been identified that graduate nurses may lack the clinical reasoning skills to deliver safe and effective patient cam. It is therefore of paramount importance to enhance nursing students＇ clinical reasoning ability. High-fidelity simulation （HFS） is proved to be an effective teaching and learning method, which may also have some advantages over other teaching methods. Methods： The authors retrospectively reviewed the related literature, illustrated the application of high-fidelity simulation teaching method in nursing education, putting the focus on the use of it in teaching with clinical reasoning. Results： The application of high-fidelity simulation to nursing education can simulate the clinical situation, thus to create a safe, continuous and efficient learning environment for students, and it can effectively improve students＇ clinical reasoning ability. Conclusions： high-fidelity simulation is effective for clinical reasoning teaching in nursing education. The extension of its application in China should be of great value. The relevant further study is suggested focusing on how to overcome its own limitations and have it better applied in nursing education in China.
基金This project was supported by research funding from the Macao Polytechnic Institute(No.RP/ESS-06/2017).
文摘Objective:To evaluate nursing students’assessment and communication skills through an objective structured clinical examination(OSCE)within a high-fidelity simulation using a student-simulated patient(SSP)and analyze the validity,reliability,degree of difficulty,and discriminability of the OSCE.Methods:A descriptive study was conducted at one nursing school in Macao.All scenarios were designed using a high-fidelity simulator combined with SSPs.A convenience sample of 54 baccalaureate nursing students completed the OSCE.The nursing assessment OSCE checklist(NAOC)and the communication evaluation rubric(CER)were used as observational measurements with three-point Likert scales(2=Achieved,1=Partly achieved,0=Not completed/Incorrect).Results:Difficulty coefficients of the exam were 0.63 for nursing assessment skills and 0.56 for communication skills.The discrimination index of the majority items of the NAOC(86.4%)was>0.20,showing a better to good discriminability.The items of the CER had satisfactory indexes of item discrimination(from 0.38 to 0.84).Students received high scores in conducting blood oxygen saturation and cardiac and lung auscultation but low scores in vomiting and diarrhea assessment.Students presented good communication skills in eye contacting and listening,but culture assessment needs to be improved.The students with experiences in simulation or simulated patient(SP)interactions had better assessment and communication skills than students without those experiences.There was a positive relationship between nursing assessment and communication skills(r=0.67,P=0.000).Conclusions:SSPs were involved in enhancing the realism of interactions in simulated scenarios.Nursing students can conduct nursing assessments specific to patient conditions,explain the conditions to the patient,and ensure that the patient remains informed at all times of the precautions to be taken.However,students’cultural awareness and some communication skills need further training.With moderate difficulty and high discrimination index,OSCE showed satisfactory reliability and validity.
基金the Macao Polytechnic Institute(code RP/ESS-01/2012)for providing funding for this research
文摘Objective The purpose of this study was to explore student perspectives of high-fidelity simulation.Methods A descriptive study with semi-structured focus group interviews was conducted in Macao.Twenty-one focus group interviews were held with 113 baccalaureate nursing students who had experienced 36-hour of simulation.Results Students perceived that simulation created a nonrisk learning environment,and was helpful in knowledge and skill enhancement and nurse role understanding.However,lack of realistic interactions in psychosocial responses made it difficult for students to relate simulation experience to real-working situations,and poor group contributions affected their learning.ConclusionInteracting with a human patient simulator does not replicate the experience of working with a live patient.Tutors need to come up with ideas about how to make scenarios more real and give more forthright responses to improve the realism of psychosocial responses during simulation.Students experienced uncertainty with clinical decision making and commented on the minimal contributions of some group members.Tutors should be prepared to provide students with substantial supports in developing their understanding of simulation and engaging in the learning process.
基金supported by research funding from the Macao Polytechnic Institute(No.RP/ESS-06/2017)。
文摘Objective:This study is aimed to develop student simulated patient(SSP)training content and evaluation indicators,and further explores their validity and reliabilities.Methods:Delphi consultations with 20 nursing exper ts were conducted.The weights of indicators were calculated through the analytic hierarchy process.SSP training was conducted with a high-fidelity nursing simulation.Results:The expert positive coefficients were 0.952 in the first round consultation and 1.00 in the second round consultation.The expert authority coefficient was reported as 0.87.The training included role and responsibility of simulated patient(SP),script interpretation,plot performance,and training for a rater,with a total of 17 indicators.SSP evaluation consisted of disease knowledge,role portrayal,and performance fidelity and since being a rater,it consists of 20 indicators in total.The coordination coefficients of two rounds of consultation ranged from 0.530 to 0.918.The content validity of SSP evaluation indicators was 0.95.The inter-rater reliability was repor ted as 0.866,and the internal consistency established using Cronbach’sαwas 0.727.Conclusions:Students as SPs should have first-hand knowledge and experience within the simulated scenarios.SSP training content and evaluation indicators were determined through the Delphi consensus combined with analytic hierarchy process.The evaluation indicators were valid and reliable,and provided the objective and quantifiable measurements for SSP training in nursing。
基金Opening Foundation of Key Laboratory of Explosive Energy Utilization and Control,Anhui Province(BP20240104)Graduate Innovation Program of China University of Mining and Technology(2024WLJCRCZL049)Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX24_2701)。
文摘Because of the challenge of compounding lightweight,high-strength Ti/Al alloys due to their considerable disparity in properties,Al 6063 as intermediate layer was proposed to fabricate TC4/Al 6063/Al 7075 three-layer composite plate by explosive welding.The microscopic properties of each bonding interface were elucidated through field emission scanning electron microscope and electron backscattered diffraction(EBSD).A methodology combining finite element method-smoothed particle hydrodynamics(FEM-SPH)and molecular dynamics(MD)was proposed for the analysis of the forming and evolution characteristics of explosive welding interfaces at multi-scale.The results demonstrate that the bonding interface morphologies of TC4/Al 6063 and Al 6063/Al 7075 exhibit a flat and wavy configuration,without discernible defects or cracks.The phenomenon of grain refinement is observed in the vicinity of the two bonding interfaces.Furthermore,the degree of plastic deformation of TC4 and Al 7075 is more pronounced than that of Al 6063 in the intermediate layer.The interface morphology characteristics obtained by FEM-SPH simulation exhibit a high degree of similarity to the experimental results.MD simulations reveal that the diffusion of interfacial elements predominantly occurs during the unloading phase,and the simulated thickness of interfacial diffusion aligns well with experimental outcomes.The introduction of intermediate layer in the explosive welding process can effectively produce high-quality titanium/aluminum alloy composite plates.Furthermore,this approach offers a multi-scale simulation strategy for the study of explosive welding bonding interfaces.
基金supported by the Research Funding of Hangzhou International Innovation Institute of Beihang Uni-versity,China(No.2024KQ130)the National Natural Science Foundation of China(Nos.52073010 and 52373259).
文摘Recent progress in microwave absorption materials stimulates the extensive exploration of rare earth oxide materials.Herein,we report the synthesis of a hollow sphere-based carbon material compounded with rare earth oxides.Hollow N-doped carbon nano-spheres loaded ceria composites(H-NC@CeO_(2))were designed and prepared by the template method,combined with in-situ coating,pyrolysis and chemical etching.By controlling the loading content of H-NC@CeO_(2)and adjusting the impedance matching of the material,the H-NC@CeO_(2)/PS(polystyrene)composite exhibited a minimum reflection loss(RL)of-50.8 dB and an effective absorption band-width(EAB)of 4.64 GHz at a filler ratio of 20wt%and a thickness of 2 mm.In accordance with measured electromagnetic parameters,simulations using the high frequency structure simulator(HFSS)software were conducted to investigate the impact of the honeycomb structure on the electromagnetic wave performance of H-NC@CeO_(2)/PS.By calculating the surface electric field and the material’s bulk loss density,the mechanism of electromagnetic loss for the honeycomb structure was elaborated.A method for structural design and man-ufacturing of broadband absorbing devices was proposed and a broadband absorber with an EAB of 11.9 GHz was prepared.This study presents an innovative approach to designing advanced electromagnetic(EM)wave absorbing materials with broad absorption band-widths.
基金supported by the National Natural Science Foundation of China(Nos.U24A2088,42177130,42277174,and 42477166).
文摘As coal mining depth increases,the combined effects of high stress,mining stress,and fault structures make dynamic impact hazards more frequent.The reproduction of dynamic impact phenomena is basis for studying their occurrence patterns and control mechanisms.Physical simulation test represents an efficacious methodology.However,there is currently a lack of simulation devices that can effectively simulate two types of dynamic impact phenomena,including high stress and fault slip dynamic impact.To solve aforementioned issues,the physical simulation test system for dynamic impact in deep roadways developed by authors is employed to carry out comparative tests of high stress and fault slip dynamic impact.The phenomena of high stress and fault slip dynamic impact are reproduced successfully.A comparative analysis is conducted on dynamic phenomena,stress evolution,roadway deformation,and support force.The high stress dynamic impact roadway instability mode,which is characterized by the release of high energy accompanied by symmetric damage,and the fault slip dynamic impact roadway instability mode,which is characterized by the propagation of unilateral stress waves accompanied by asymmetric damage,are clarified.On the basis,the differentiated control concepts for different types of dynamic impact in deep roadways are proposed.
基金the National Natural Science Foundation of China(No.52205468)China Postdoctoral Science Foundation(No.2022M710061 and No.2023T160277)Natural Science Foundation of Jiangsu Province(No.BK20210755)。
文摘Large size titanium alloy parts are widely used in aerospace.However,they are difficult to manufacture using mechanical cutting technology because of severe tool wear.Electrochemical jet machining is a promising technology to achieve high efficiency,because it has high machining flexibility and no machining tool wear.However,reports on the macro electrochemical jet machining of large size titanium alloy parts are very scarce,because it is difficult to achieve effective constraint of the flow field in macro electrochemical jet machining.In addition,titanium alloy is very sensitive to fluctuation of the flow field,and a turbulent flow field would lead to serious stray corrosion.This paper reports a series of investigations of the electrochemical jet machining of titanium alloy parts.Based on the flow analysis and experiments,the machining flow field was effectively constrained.TB6 titanium alloy part with a perimeter of one meter was machined.The machined surface was smooth with no obvious machining defects.The machining process was particularly stable with no obvious spark discharge.The research provides a reference for the application of electrochemical jet machining technology to achieve large allowance material removal in the machining of large titanium alloy parts.
基金Funded by the Research Funds of China University of Mining and Technology(No.102523215)。
文摘The pre-wetting of aggregate surface is a means to improve the interface performance of SBS modified asphalt and aggregate.The effect of pre-wetting technology on the interaction between SBS modified asphalt and aggregate was analyzed by molecular dynamics simulation.The diffusion coefficient and concentration distribution of SBS modified asphalt on aggregate surface are included.The simulation results show that the diffusion coefficient of the aggregate surface of SBS modified asphalt is increased by 47.6%and 70.5%respectively after 110#asphalt and 130#asphalt are pre-wetted.The concentration distribution of SBS modified asphalt on the aggregate surface after pre-wetting is more uniform.According to the results of interface energy calculation,the interface energy of SBS modified bitumen and aggregate can be increased by about 5%after pre-wetting.According to the results of molecular dynamics simulation,the pre-wetting technology can effectively improve the interface workability of SBS modified bitumen and aggregate,so as to improve the interface performance.
基金supported by the National Natural Science Foundation of China(Grant No.U21B2062)supported by the Key Laboratory for Carbonate Reservoirs of China National Petroleum Corporation。
文摘Burial dissolution is a critical diagenetic process influencing ultra-deep carbonate reservoir development and preservation.Artificial carbonate samples with different internal structures were prepared,and high-temperature and highpressure dissolution kinetic simulations were conducted.The results demonstrate that the intensity of burial dissolution is controlled by temperature and pressure,while tectonic-fluid activity influences the development pattern of burial dissolution,ultimately determining the direction of its differential modification.Extensive burial dissolution is likely to occur primarily at relatively shallow depths,significantly influencing reservoir formation,preservation,modification,and adjustment.The development of faults facilitates the maintenance of the intensity of burial dissolution.The maximum intensity of burial dissolution occurs at the tips and overlap zones of faults and intersections of multiple faults.The larger the scale of the faults,the more conducive it is to the development of burial dissolution.Burial dissolution fosters the formation of fault networks characterized by enhanced reservoir capacity and permeability.Burial dissolution controlled by episodic tectonic-fluid activity is a plausible explanation for forming the Tarim Basin's ultra-deep fault-controlled“stringbead-like”reservoirs.
基金supported by the National Natural Science Foundation of China (Grant No.52108361)the Sichuan Science and Technology Program of China (Grant No.2023YFS0436)the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Independent Research Project (Grant No.SKLGP2022Z015).
文摘Bedding parallel stepped rock slopes exist widely in nature and are used in slope engineering.They are characterized by complex topography and geological structure and are vulnerable to shattering under strong earthquakes.However,no previous studies have assessed the mechanisms underlying seismic failure in rock slopes.In this study,large-scale shaking table tests and numerical simulations were conducted to delineate the seismic failure mechanism in terms of acceleration,displacement,and earth pressure responses combined with shattering failure phenomena.The results reveal that acceleration response mutations usually occur within weak interlayers owing to their inferior performance,and these mutations may transform into potential sliding surfaces,thereby intensifying the nonlinear seismic response characteristics.Cumulative permanent displacements at the internal corners of the berms can induce quasi-rigid displacements at the external corners,leading to greater permanent displacements at the internal corners.Therefore,the internal corners are identified as the most susceptible parts of the slope.In addition,the concept of baseline offset was utilized to explain the mechanism of earth pressure responses,and the result indicates that residual earth pressures at the internal corners play a dominant role in causing deformation or shattering damage.Four evolutionary deformation phases characterize the processes of seismic responses and shattering failure of the bedding parallel stepped rock slope,i.e.the formation of tensile cracks at the internal corners of the berm,expansion of tensile cracks and bedding surface dislocation,development of vertical tensile cracks at the rear edge,and rock mass slipping leading to slope instability.Overall,this study provides a scientific basis for the seismic design of engineering slopes and offers valuable insights for further studies on preventing seismic disasters in bedding parallel stepped rock slopes.
