Rotary friction welding is a highly effective solid-state technique for joining dissimilar materials,which offers the potential for significant weight reduction without compromising strength.Traditionally,during rotar...Rotary friction welding is a highly effective solid-state technique for joining dissimilar materials,which offers the potential for significant weight reduction without compromising strength.Traditionally,during rotary friction welding,the severely deformed material,or flash,is expelled from the interface and machined away to achieve the desired joint geometry.However,this work introduces a novel approach:trapping the flash within the joint to improve joint properties.The study investigates two different interface geometry combinationsdflat-flat and flat-taper interfaces.Previous research shows that Ni interlayer between steel and titanium can enhance the joint strength.This study builds on the existing knowledge(effect of Ni interlayer)by examining the influence of interface geometry to further improve the dissimilar joint performance.The experimental results,including tensile testing and microstructural characterization,highlight the superior performance of the flat-taper interface.The modified geometry minimizes flash loss,providing a cavity that retains both the flash and the Ni interlayer within the joint.This retention promotes dynamic recrystallization,resulting in refined grain structures near the interface.Moreover,the trapped Ni interlayer effectively prevents the formation of brittle Fe-Ti intermetallic compounds at the dissimilar material interface.The findings reveal that the flat-taper interface improved joint strength by an impressive 105%compared to the flat-flat interface.This innovative geometry modification demonstrates the potential to enhance mechanical properties of dissimilar joints through better flash and interlayer management.展开更多
This study introduces a comprehensive theoretical framework for accurately calculating the electronic band-structure of strained long-wavelength InAs/GaSb type-Ⅱsuperlattices.Utilizing an eight-band k·p Hamilto⁃...This study introduces a comprehensive theoretical framework for accurately calculating the electronic band-structure of strained long-wavelength InAs/GaSb type-Ⅱsuperlattices.Utilizing an eight-band k·p Hamilto⁃nian in conjunction with a scattering matrix method,the model effectively incorporates quantum confinement,strain effects,and interface states.This robust and numerically stable approach achieves exceptional agreement with experimental data,offering a reliable tool for analyzing and engineering the band structure of complex multi⁃layer systems.展开更多
Nowadays, ultrafine explosives are widely used in military fields. Ultrafine 2,2',4,4',6,6'-hexanitrostilbene(HNS) has emerged as an optimal primer for explosion foil initiators due to its excellent therma...Nowadays, ultrafine explosives are widely used in military fields. Ultrafine 2,2',4,4',6,6'-hexanitrostilbene(HNS) has emerged as an optimal primer for explosion foil initiators due to its excellent thermal stability and high-voltage short-pulse initiation performance. However, the solid phase ripening of ultrafine HNS leads to a degradation in its impact detonation performance. Previous studies have indicated that residual dimethyl formamide(DMF), which is present in ultrafine HNS prepared using the recrystallization method, affects ultrafine HNS ripening. The mechanism of residual solvent effects on solid phase ripening of ultrafine HNS is unclear. In this work, the specific surface area(SSA) derived from small angle X-ray scattering(SAXS) was utilized for kinetic fitting analysis to explore the mechanism by which residual solvents enhance the solid phase ripening of ultrafine HNS. The results of the SSA measured by insitu SAXS under conditions of 150℃ for 40 h revealed that the sample with 0.2% residual DMF exhibited a 21.51% decrease in SSA, whereas the sample with only 0.04% residual DMF showed a decrease of 15.66%.Furthermore, the higher amounts of residual DMF accelerated the reduction in SSA with time. Kinetic fitting analysis demonstrated that reducing residual DMF would lower both the activation energy and the pre-exponential factor, consequently decreasing the rate constant of solid phase ripening. The mechanism was speculated that it primarily facilitated the Ostwald ripening(OR). Additionally, contrast variation small angle X-ray scattering(CV-SAXS) confirmed that coating of ultrafine HNS particles is an effective method for inhibiting ripening, significantly reducing both the rate and extent of ripening of ultrafine HNS. This study predicts how residual solvents impact the solid phase ripening process of ultrafine HNS and proposes strategies for enhancing the long-term stability of ultrafine explosives.展开更多
In the last ten-odd years, Chinese oceanographers have accomplished alarge amount of work in analysing the characteristics,distribution andvariation of temperature, salinity, density and water masses in shallow seaare...In the last ten-odd years, Chinese oceanographers have accomplished alarge amount of work in analysing the characteristics,distribution andvariation of temperature, salinity, density and water masses in shallow seaareas near China and in their forecasting methods, and have formally pub-lished agreat number of treatises. If these treatises, which are scattered展开更多
In recent years,the field of mechanomaterials has emerged at the interface of mechanics,materials science,biology,medicine and data science,where materials are proactively designed or programmed to achieve targeted fu...In recent years,the field of mechanomaterials has emerged at the interface of mechanics,materials science,biology,medicine and data science,where materials are proactively designed or programmed to achieve targeted functionalities by leveraging the fundamental mechanics principles and force-geometry-property relationships.In the biological context,one may likewise introduce mechanobiomaterials as a field with the following goals:(1)proactive design or programming of materials for precisely mediating biomechanical environment of living systems for tissue repair/restoration;(2)proactive control/programming of living systems themselves by an external field via force-structure-function relationships.Here,we will discuss an example of research in mechanobiomaterials on using mechanics to guide the design of acellular epicardial patches for the treatment of myocardial infarction.This technology aims to employ a biocompatible material patch to help reverse left ventricular remodeling and restore heart function after myocardial infarction by increasing the mechanical integrity of damaged heart tissues.However,its application is currently limited by widely scattered therapeutic efficacy.Here,we develop a biomechanics-based simulation platform that allows us to test,design and optimize the performance of an epicardial patch.We show that the widely scattered therapeutic efficacy of this technology can be attributed to a“pre-strain sensitivity”caused by attaching an elastic patch to a dynamically beating heart.To mitigate this challenge,we introduce a viscoelastic epicardial patch,designed at the so-called‘gel point’of the material,that effectively accommodates the cyclic deformation of the myocardium.This then leads to the fabrication and experimentally validated epicardial patch that outperforms all existing ones in restoring heart function after both acute and subacute myocardial infarction in rats.Our study also demonstrates the potential of employing viscoelastic interfaces for better integration of synthetic materials with biological tissues.展开更多
CHARACTERIZATION OF EXTRAFOCAL DOSE INFLUENCE ON THE OUT-OF-FIELD DOSE DISTRIBUTION BY MONTE CARLO SIMULATIONS AND DOSE MEASUREMENTS Firass Ghareeb 1,Joana Lencart 1,2,Jorge Oliveira 1,Jo o A.M.Santos 1,2,3(1.Medical ...CHARACTERIZATION OF EXTRAFOCAL DOSE INFLUENCE ON THE OUT-OF-FIELD DOSE DISTRIBUTION BY MONTE CARLO SIMULATIONS AND DOSE MEASUREMENTS Firass Ghareeb 1,Joana Lencart 1,2,Jorge Oliveira 1,Jo o A.M.Santos 1,2,3(1.Medical Physics,Radiobiology and Radiation Protection Group,IPO Porto Research Center(CI-IPOP),Portuguese Oncology Institute of Porto(IPO Porto),Porto,Portugal;2.Medical Physics Department,Portuguese Oncology Institute of Porto(IPO Porto),Porto,Portugal;3.Instituto de Ciências Biomédicas Abel Salazar(ICBAS),University of Porto,Porto,Portugal)Abstract:Out-of-field scattered and transmitted extrafocal radiation may induce secondary cancer in long-term survivors of external radiotherapy.Pediatric patients have higher life expectancy and tend to receive higher secondary radiation damage due to geometric and biological factors.The goal of this study is to characterize the location and the magnitude of extrafocal dose regions in the case of three-dimensional conformal radiotherapy and volumetric arc therapy,to apply this information to clinical treatment cases,and to provide mitigation strategies.Extrafocal dose has been investigated in a Varian TrueBeam linac equipped with a high-definition 120 multileaf collimator using different physical and virtual phantoms,dose calculation(including Monte Carlo techniques),and dose measurement methods.All Monte Carlo calculations showed excellent agreement with measurements.展开更多
The method of establishing data structures plays an important role in the efficiency of parallel multilevel fast multipole algorithm（PMLFMA）.Considering the main complements of multilevel fast multipole algorithm（M...The method of establishing data structures plays an important role in the efficiency of parallel multilevel fast multipole algorithm（PMLFMA）.Considering the main complements of multilevel fast multipole algorithm（MLFMA） memory,a new parallelization strategy and a modified data octree construction scheme are proposed to further reduce communication in order to improve parallel efficiency.For far interaction,a new scheme called dynamic memory allocation is developed.To analyze the workload balancing performance of a parallel implementation,the original concept of workload balancing factor is introduced and verified by numerical examples.Numerical results show that the above measures improve the parallel efficiency and are suitable for the analysis of electrical large-scale scattering objects.展开更多
Based on a first-order state-vector differential equation representation of Maxwell's equations, an analytical formulation is derived for the equivalent currents on an anisotropic material backed by a metal surfa...Based on a first-order state-vector differential equation representation of Maxwell's equations, an analytical formulation is derived for the equivalent currents on an anisotropic material backed by a metal surface, and the relation between two currents is also considered. These expressions are degenerated into the common forms for some simple cases. This effort will provide the theoretical preparation for the approximate calculation of electromagnetic scattering from a conducting object coated by an anisotropic material.展开更多
文摘Rotary friction welding is a highly effective solid-state technique for joining dissimilar materials,which offers the potential for significant weight reduction without compromising strength.Traditionally,during rotary friction welding,the severely deformed material,or flash,is expelled from the interface and machined away to achieve the desired joint geometry.However,this work introduces a novel approach:trapping the flash within the joint to improve joint properties.The study investigates two different interface geometry combinationsdflat-flat and flat-taper interfaces.Previous research shows that Ni interlayer between steel and titanium can enhance the joint strength.This study builds on the existing knowledge(effect of Ni interlayer)by examining the influence of interface geometry to further improve the dissimilar joint performance.The experimental results,including tensile testing and microstructural characterization,highlight the superior performance of the flat-taper interface.The modified geometry minimizes flash loss,providing a cavity that retains both the flash and the Ni interlayer within the joint.This retention promotes dynamic recrystallization,resulting in refined grain structures near the interface.Moreover,the trapped Ni interlayer effectively prevents the formation of brittle Fe-Ti intermetallic compounds at the dissimilar material interface.The findings reveal that the flat-taper interface improved joint strength by an impressive 105%compared to the flat-flat interface.This innovative geometry modification demonstrates the potential to enhance mechanical properties of dissimilar joints through better flash and interlayer management.
文摘This study introduces a comprehensive theoretical framework for accurately calculating the electronic band-structure of strained long-wavelength InAs/GaSb type-Ⅱsuperlattices.Utilizing an eight-band k·p Hamilto⁃nian in conjunction with a scattering matrix method,the model effectively incorporates quantum confinement,strain effects,and interface states.This robust and numerically stable approach achieves exceptional agreement with experimental data,offering a reliable tool for analyzing and engineering the band structure of complex multi⁃layer systems.
基金the Presidential Foundation of CAEP(Grant No.YZJJZQ2023005)the National Natural Science Foundation of China(Grant No.22375191).
文摘Nowadays, ultrafine explosives are widely used in military fields. Ultrafine 2,2',4,4',6,6'-hexanitrostilbene(HNS) has emerged as an optimal primer for explosion foil initiators due to its excellent thermal stability and high-voltage short-pulse initiation performance. However, the solid phase ripening of ultrafine HNS leads to a degradation in its impact detonation performance. Previous studies have indicated that residual dimethyl formamide(DMF), which is present in ultrafine HNS prepared using the recrystallization method, affects ultrafine HNS ripening. The mechanism of residual solvent effects on solid phase ripening of ultrafine HNS is unclear. In this work, the specific surface area(SSA) derived from small angle X-ray scattering(SAXS) was utilized for kinetic fitting analysis to explore the mechanism by which residual solvents enhance the solid phase ripening of ultrafine HNS. The results of the SSA measured by insitu SAXS under conditions of 150℃ for 40 h revealed that the sample with 0.2% residual DMF exhibited a 21.51% decrease in SSA, whereas the sample with only 0.04% residual DMF showed a decrease of 15.66%.Furthermore, the higher amounts of residual DMF accelerated the reduction in SSA with time. Kinetic fitting analysis demonstrated that reducing residual DMF would lower both the activation energy and the pre-exponential factor, consequently decreasing the rate constant of solid phase ripening. The mechanism was speculated that it primarily facilitated the Ostwald ripening(OR). Additionally, contrast variation small angle X-ray scattering(CV-SAXS) confirmed that coating of ultrafine HNS particles is an effective method for inhibiting ripening, significantly reducing both the rate and extent of ripening of ultrafine HNS. This study predicts how residual solvents impact the solid phase ripening process of ultrafine HNS and proposes strategies for enhancing the long-term stability of ultrafine explosives.
文摘In the last ten-odd years, Chinese oceanographers have accomplished alarge amount of work in analysing the characteristics,distribution andvariation of temperature, salinity, density and water masses in shallow seaareas near China and in their forecasting methods, and have formally pub-lished agreat number of treatises. If these treatises, which are scattered
文摘In recent years,the field of mechanomaterials has emerged at the interface of mechanics,materials science,biology,medicine and data science,where materials are proactively designed or programmed to achieve targeted functionalities by leveraging the fundamental mechanics principles and force-geometry-property relationships.In the biological context,one may likewise introduce mechanobiomaterials as a field with the following goals:(1)proactive design or programming of materials for precisely mediating biomechanical environment of living systems for tissue repair/restoration;(2)proactive control/programming of living systems themselves by an external field via force-structure-function relationships.Here,we will discuss an example of research in mechanobiomaterials on using mechanics to guide the design of acellular epicardial patches for the treatment of myocardial infarction.This technology aims to employ a biocompatible material patch to help reverse left ventricular remodeling and restore heart function after myocardial infarction by increasing the mechanical integrity of damaged heart tissues.However,its application is currently limited by widely scattered therapeutic efficacy.Here,we develop a biomechanics-based simulation platform that allows us to test,design and optimize the performance of an epicardial patch.We show that the widely scattered therapeutic efficacy of this technology can be attributed to a“pre-strain sensitivity”caused by attaching an elastic patch to a dynamically beating heart.To mitigate this challenge,we introduce a viscoelastic epicardial patch,designed at the so-called‘gel point’of the material,that effectively accommodates the cyclic deformation of the myocardium.This then leads to the fabrication and experimentally validated epicardial patch that outperforms all existing ones in restoring heart function after both acute and subacute myocardial infarction in rats.Our study also demonstrates the potential of employing viscoelastic interfaces for better integration of synthetic materials with biological tissues.
文摘CHARACTERIZATION OF EXTRAFOCAL DOSE INFLUENCE ON THE OUT-OF-FIELD DOSE DISTRIBUTION BY MONTE CARLO SIMULATIONS AND DOSE MEASUREMENTS Firass Ghareeb 1,Joana Lencart 1,2,Jorge Oliveira 1,Jo o A.M.Santos 1,2,3(1.Medical Physics,Radiobiology and Radiation Protection Group,IPO Porto Research Center(CI-IPOP),Portuguese Oncology Institute of Porto(IPO Porto),Porto,Portugal;2.Medical Physics Department,Portuguese Oncology Institute of Porto(IPO Porto),Porto,Portugal;3.Instituto de Ciências Biomédicas Abel Salazar(ICBAS),University of Porto,Porto,Portugal)Abstract:Out-of-field scattered and transmitted extrafocal radiation may induce secondary cancer in long-term survivors of external radiotherapy.Pediatric patients have higher life expectancy and tend to receive higher secondary radiation damage due to geometric and biological factors.The goal of this study is to characterize the location and the magnitude of extrafocal dose regions in the case of three-dimensional conformal radiotherapy and volumetric arc therapy,to apply this information to clinical treatment cases,and to provide mitigation strategies.Extrafocal dose has been investigated in a Varian TrueBeam linac equipped with a high-definition 120 multileaf collimator using different physical and virtual phantoms,dose calculation(including Monte Carlo techniques),and dose measurement methods.All Monte Carlo calculations showed excellent agreement with measurements.
基金supported by the National Basic Research Program of China (973 Program) (61320)
文摘The method of establishing data structures plays an important role in the efficiency of parallel multilevel fast multipole algorithm（PMLFMA）.Considering the main complements of multilevel fast multipole algorithm（MLFMA） memory,a new parallelization strategy and a modified data octree construction scheme are proposed to further reduce communication in order to improve parallel efficiency.For far interaction,a new scheme called dynamic memory allocation is developed.To analyze the workload balancing performance of a parallel implementation,the original concept of workload balancing factor is introduced and verified by numerical examples.Numerical results show that the above measures improve the parallel efficiency and are suitable for the analysis of electrical large-scale scattering objects.
文摘Based on a first-order state-vector differential equation representation of Maxwell's equations, an analytical formulation is derived for the equivalent currents on an anisotropic material backed by a metal surface, and the relation between two currents is also considered. These expressions are degenerated into the common forms for some simple cases. This effort will provide the theoretical preparation for the approximate calculation of electromagnetic scattering from a conducting object coated by an anisotropic material.
