Considérée souvent en France comme discontinue,la transition du bati urbain-rural est largement envisagécomme continue au niveau international.Si la question de la forme urbaine n’est donc,aujourd’hui...Considérée souvent en France comme discontinue,la transition du bati urbain-rural est largement envisagécomme continue au niveau international.Si la question de la forme urbaine n’est donc,aujourd’hui,plus en suspens du fait des très nombreusesétudesàl’échelle internationale,la limite urbain périurbain et rural isoléconvient d’être néanmoins encore réinterrogée.La notion de proxémique développée dans les années 1970,pourrait permettre une résolution du problème.Utiliser cette notion pour revoir la métrique géographique pourrait permettre de réviser la limite urbain-campagne et raisonner alors sur un espace continu au-delàmême des limites du périurbain.展开更多
Taking half-tube part with curvature as an example,the Impact Hydroforming(IHF)characteristics were studied by combining the actual forming experiment and numerical simulation.The IHF experiment showed that wrinkles a...Taking half-tube part with curvature as an example,the Impact Hydroforming(IHF)characteristics were studied by combining the actual forming experiment and numerical simulation.The IHF experiment showed that wrinkles appeared at the bottom of the part during single-step forming,but no wrinkles were observed during double-step forming.The thinning rate and deviation of the wall thickness of the part in each area were less than 20%and 2.7 mm,correspondingly,and the drawing depth of the part reached 45.8 mm.The effect of double-step forming was better than that of single-step forming,which was related to the IHF forming law.Besides,the characteristics of the IHF process were studied by numerical simulation.The results indicated that when double-step forming was utilized,there was almost no velocity field in the opposite direction of deformation after the bottom of the part contacted the die,and the existence of stress state at the bottom would restrain and eliminate the wrinkles.The inertia effect evolved with the driving pressure.Specially,the inertia effect can improve the flow of metal and reduce the deviation of the wall thickness of the part under double-step forming.展开更多
RENEWING THE FORBIDDEN CITY’S CENTURY-OLD LEGACY.Oriental Outlook.27 November 2025.At sunrise,the Forbidden City glows under a veil of gold;at night,it retreats into quiet dignity.But the palace never really sleeps.A...RENEWING THE FORBIDDEN CITY’S CENTURY-OLD LEGACY.Oriental Outlook.27 November 2025.At sunrise,the Forbidden City glows under a veil of gold;at night,it retreats into quiet dignity.But the palace never really sleeps.As visitors depart,the“digital relic vault”awakens online,where porcelain,calligraphy,jade and timepieces reveal their beauty in virtual form.History continues to breathe in the data stream.展开更多
The multi-pass intermittent local loading process,which features a more flexible processing path,can further enhance the second material distribution during local loading,improve the formability of components,and redu...The multi-pass intermittent local loading process,which features a more flexible processing path,can further enhance the second material distribution during local loading,improve the formability of components,and reduce forming loads.However,the absence of compatible forming equipment makes it difficult to control the constraint in the unloaded zones during the forming process.This difficulty complicates coordination and control of deformation,particularly for asymmetric rib-web components.Additionally,the current implementation involves multi-fire heating,a long process flow,and high energy consumption,which limits the popularization and application of the local loading process.In this study,a new multi-pass local loading hydraulic forming apparatus that can quickly and reliably switch between heavy-load deformation and low-load constraint for different local loading sub-dies was developed.A 10-tonne laboratory prototype was developed,and the forming characteristics during the forming process as well as the response characteristics of the hydraulic system during the multi-pass intermittent local loading of rib-web component were investigated using numerical simulations and physical experiments.Results indicated that,compared to a whole loading process with the same initial geometry of billet,the total forming load(i.e.,the sum of loaded and restrained loads)is reduced by more than 40%with the local loading process,and by nearly 50%with multi-pass local loading.The multi-pass local loading process allows for more effective control of material flow compared to single-pass local loading,leading to improved cavity filling and reduced flow line disturbance.For a large-scale,complex titanium alloy bulkhead,the cavity filling problem was addressed by optimizing the multi-pass local loading path with an unequal thickness billet.The dynamic performance of the multi-pass local loading hydraulic system was found to be robust,with stable pressure transitions during motion and load switching for the sub-die(s).The dynamic characteristic of the hydraulic cylinder when switching from non-moving/unloaded state to a moving/loading state are consistent whether a load is present or not.However,the dynamic characteristics differ when switching from a moving/loading state to non-moving/unloaded state,showing opposite behavior.The developed hydraulic drive mechanism provides a way for implementation of multi-pass local loading without auxiliary operation and extra heating.The results of the study provide a foundation for the industrial production of large-scale,complex components with reduced force requirement and low-energy consumption.展开更多
In this paper,we studyλ-biharmonic hypersurfaces M_(r)^(5) of 6-dimensional pseudo Riemannian space form N_(p)^(6)(c)with the indexs 0≤p≤6,r=p−1 or p,and constant curvature c.It was proved that if the shape operato...In this paper,we studyλ-biharmonic hypersurfaces M_(r)^(5) of 6-dimensional pseudo Riemannian space form N_(p)^(6)(c)with the indexs 0≤p≤6,r=p−1 or p,and constant curvature c.It was proved that if the shape operator of M_(r)^(5) is diagonalizable,then the mean curvature is a constant.As an application,we find some types of biharmonic hypersurfaces of N_(p)^(6)(c)are minimal.展开更多
Aviation aluminum alloys,primarily from the Al-Cu,Al-Zn-Mg-(Cu),and Al-Li series,have been widely applied over six decades,greatly advancing the aviation industry.However,their Corrosion Fatigue(CF)properties impede f...Aviation aluminum alloys,primarily from the Al-Cu,Al-Zn-Mg-(Cu),and Al-Li series,have been widely applied over six decades,greatly advancing the aviation industry.However,their Corrosion Fatigue(CF)properties impede further advancements,prompting extensive research into their CF behaviors and underlying mechanisms.This review comprehensively evaluates previous studies on their development history,CF mechanisms,and key influencing factors.First,the historical evolution of aerospace aluminum alloys is summarized.Then,the currently recognized four crack initiation mechanisms and three crack propagation mechanisms are concluded,and the effects of external and internal factors on CF performance are discussed.The paper also reviews three methods and CF life prediction models for characterizing the CF behavior of aerospace aluminum alloys.Most existing studies on the CF behavior of aluminum alloys are based on the single corrosive environment,neglecting the fact that aircrafts experience multiple corrosive environments during service.However,the most critical scientific challenge is how to enhance their CF properties under increasingly demanding service conditions.For the purpose,this paper introduces advanced forming techniques based on the microstructural control,such as Equal Channel Angular Pressing(ECAP)and High-Pressure Torsion(HPT),aimed at laying the theoretical foundation for improving CF properties through microstructural regulation.展开更多
In order to investigate the penetration performance of Linear-Shaped Charge(LSC),Embowed LinearShaped Charge(ELSC),and Embowed Linear Explosively Formed Projectile(ELEFP)on T-shaped stiffened plates,a series of near-f...In order to investigate the penetration performance of Linear-Shaped Charge(LSC),Embowed LinearShaped Charge(ELSC),and Embowed Linear Explosively Formed Projectile(ELEFP)on T-shaped stiffened plates,a series of near-field air-burst experiments are conducted.The damage modes and characteristics of the target plates are compared and analyzed.Each flat plate section is completely punctured,resulting in a penetration hole.The damage modes induced by the three charge types on the stiffened plate structure are consistent,characterized by shear failure in the central region of the flat plate due to penetration by the penetrator,localized plastic deformation of the flat plate,and local penetration failure resulting from partial perforation of the central stiffener.The penetration lengths caused by ELSC and ELEFP are 45.1%and 46.1% larger than that of LSC,while the half-width of the penetration hole generated by ELEFP is 54.2% and 24.7% smaller than that of ELSC and LSC,respectively.The penetration height caused by ELEFP are 17.5%and 62.1% larger than that of ELSC and LSC,respectively.The stiffener effectively segments the damage area,enhancing the local structural strength and limiting the extent of plastic deformation in the flat plate section.The comparative results show that the ELSC proves to be more effective for efficient large-scale damage,and ELEFP is more suitable for achieving efficient localized damage.展开更多
In aerospace,nuclear power,and new energy vehicles industries,utilizing integrated metal components with extreme sizes and/or structures is crucial for achieving significant weight-saving,performance-improvement,and e...In aerospace,nuclear power,and new energy vehicles industries,utilizing integrated metal components with extreme sizes and/or structures is crucial for achieving significant weight-saving,performance-improvement,and excellent reliability.These components,made from metal sheets,rings,or tubes,exhibit characteristics like ultra-thin,ultra-thick,ultra-large,ultra-long,ultra-high ribs,and large variable diameters.During plastic de-formation in metal forming processes,defects such as ruptures,wrinkles,excessive strain differences,and un-expected weak performance areas are likely to occur due to the intersection of multiple effects in different research disciplines,including materials science,processes,and mechanics of materials.Consequently,the smooth forming of integrated parts is difficult.It is the first time to review,summarize,and analyze the ad-vancement of forming methods for producing integrated parts with extreme sizes and structures.The general academic ideas to change the process conditions and sequences to optimize stress state and improve plastic deformation ability for forming the components with extreme sizes/structures are introduced.Practical ex-amples,discussed in detail in the paper,include the forming of(i)integrated ultra-thin and ultra-thick sheet components;(ii)integrated ultra-large size ring components with thin wall and high ribs;and(iii)integrated ultra-long tube components with large perimeter difference.Various plasticity technologies and process se-quences have been developed.The key processes and applications of the technologies are discussed in detail,which achieve successful plastic forming of integrated components.This paper provides state-of-the-art and perspectives for the rapidly advancing material forming fields of key metal components for the next generation of equipment.展开更多
G protein-coupled receptor 37(GPR37)is an orphan receptor predominantly expressed in the brain,particularly in oligodendrocytes and certain types of neurons.Notably,it has been shown that the N-terminal domain of GPR3...G protein-coupled receptor 37(GPR37)is an orphan receptor predominantly expressed in the brain,particularly in oligodendrocytes and certain types of neurons.Notably,it has been shown that the N-terminal domain of GPR37 undergoes proteolysis under normal physiological conditions,resulting in the formation of cleaved receptor forms and the release of its ectodomain(ecto-GPR37)into the extracellular milieu(Mattila et al.,2021).Importantly,ecto-GPR37 density is increased in cerebrospinal fluid(CSF)of patients suffering from sporadic Parkinson’s disease(PD),together with an abnormal GPR37 processing in post-mortem PD substantia nigra(Moratóet al.,2021;Figure 1A).展开更多
Based on the microstructure characterization,electrochemical impedance spectroscopy,potentiodynamic polarization,and immersion corrosion,this work comparatively analyzed the differences in the electrochemical corrosio...Based on the microstructure characterization,electrochemical impedance spectroscopy,potentiodynamic polarization,and immersion corrosion,this work comparatively analyzed the differences in the electrochemical corrosion morphology and post-foil formation surface morphology of laser beam welded(LBW)sample and spin-formed sample,and compared the corrosion resistance and Cu foil formation ability of two samples in H_(2)SO_(4)/NaCl solution and CuSO_(4) reducing electrolyte.Results show that in H_(2)SO_(4) and NaCl solutions,LBW sample and spin-formed sample exhibit excellent passivation ability and corrosion resistance.Both samples show uniform corrosion morphologies and similar corrosion resistance in the strong acidic solution containing Cl^(-).Meanwhile,the Cu foil formation ability of the welded joint is similar to that of the spin-formed sample,and both samples obtain intact Cu foils with high-quality surfaces and small differences in properties.展开更多
Studies on plant diversity are usually based on the total number of species in a community.However,few studies have examined species richness(SR)of different plant life forms in a community along largescale environmen...Studies on plant diversity are usually based on the total number of species in a community.However,few studies have examined species richness(SR)of different plant life forms in a community along largescale environmental gradients.Particularly,the relative importance(RIV)of different plant life forms in a community and how they vary with environmental variables are still unclear.To fill these gaps,we determined plant diversity of ephemeral plants,annual herbs,perennial herbs,and woody plants from 187 sites across drylands in China.The SR patterns of herbaceous plants,especially perennial herbs,and their RIV in plant communities increased with increasing precipitation and soil nutrient content;however,the RIV of annual herbs was not altered along these gradients.The SR and RIV of ephemeral plants were affected mainly by precipitation seasonality.The SR of woody plants had a unimodal relationship with air temperature and exhibited the highest RIV and SR percentage in plant communities under the harshest environments.An obvious shift emerged in plant community composition,SR and their critical impact factors at 238.5 mm of mean annual precipitation(MAP).In mesic regions(>238.5 mm),herbs were the dominant species,and the SR displayed a relatively slow decreasing rate with increasing aridity,which was mediated mainly by MAP and soil nutrients.In arid regions(<238.5 mm),woody plants were the dominant species,and the SR displayed a relatively fast decreasing rate with increasing aridity,which was mediated mainly by climate variables,especially precipitation.Our findings highlight the importance of comparative life form studies in community structure and biodiversity,as their responses to gradients differed substantially on a large scale.展开更多
A new analytical model for geometric size and forming force prediction in incremental flanging(IF)is presented in this work.The complex deformation characteristics of IF are considered in the modeling process,which ca...A new analytical model for geometric size and forming force prediction in incremental flanging(IF)is presented in this work.The complex deformation characteristics of IF are considered in the modeling process,which can accurately describe the strain and stress states in IF.Based on strain analysis,the model can predict the material thickness distribution and neck height after IF.By considering contact area,strain characteristics,material thickness changes,and friction,the model can predict specific moments and corresponding values of maximum axial forming force and maximum horizontal forming force during IF.In addition,an IF experiment involving different tool diameters,flanging diameters,and opening hole diameters is conducted.On the basis of the experimental strain paths,the strain characteristics of different deformation zones are studied,and the stable strain ratio is quantitatively described through two dimensionless parameters:relative tool diameter and relative hole diameter.Then,the changing of material thickness and forming force in IF,and the variation of minimum material thickness,neck height,maximum axial forming force,and maximum horizontal forming force with flanging parameters are studied,and the reliability of the analytical model is verified in this process.Finally,the influence of the horizontal forming force on the tool design and the fluctuation of the forming force are explained.展开更多
The northwestern margin of Junggar Basin is the region with the richest oil sand resources in China.For better understanding the enrichment rules and deployment of exploration and development of regional oil sand,it i...The northwestern margin of Junggar Basin is the region with the richest oil sand resources in China.For better understanding the enrichment rules and deployment of exploration and development of regional oil sand,it is of great scientific significance to study the accumulation conditions of oil sand in different strata and mining areas of the Junggar Basin.Through a large number of field investigations,drilling verification and sampling tests,it is found that the oil sand in the region covers an area of 2000 km^(2),with shallow and thick reservoir,and predicted resource of 180 million tons.The oil sand resources are mainly distributed in four geological strata,namely the Middle Triassic Karamay Formation,Early Jurassic Badaowan Formation,Late Jurassic Qigu Formation,and Early Cretaceous Qingshuihe Formation.The reservoir is mainly composed of sandstone with high porosity and permeability,and the reservoir space is mainly intergranular pores with a medium average oil content.The oil sand deposit in the region is a typical destructive oil reservoir.The crude oil in the oil sand layer is degraded and thickened from the deep to the shallow,the content of saturated hydrocarbon decreased,and the content of aromatic hydrocarbon,non-hydrocarbon and asphaltene increased.The oil source comes from the deep Permian hydrocarbon-generating depression.Unconformities,faults and marginal fan delta-braided river depositional systems constitute effective migration and storage systems.Caprocks of the Upper Triassic Baijiantan Formation,Lower Jurassic Sangonghe Formation and Lower Cretaceous Hutubihe Formation were formed by three large scale lake transgressions.The Indosinian,Yanshan and Late Yanshan movements are the main driving forces for the migration of deep oil and gas to the shallow edge to form oil sand deposits.It is considered that the oil sand in the northwestern margin of Junggar Basin is of a slope complex migration type.展开更多
Lunar in-situ construction using additive manufacturing(AM)technology has emerged as a critical pathway for sustainable extraterrestrial exploration.This review systematically evaluates two dominant AM paradigms for l...Lunar in-situ construction using additive manufacturing(AM)technology has emerged as a critical pathway for sustainable extraterrestrial exploration.This review systematically evaluates two dominant AM paradigms for lunar regolith processing:low-temperature deposition forming(material extrusion and binder jetting),and high-energy beam additive manufacturing(powder bed fusion and directed energy deposition).Low-temperature methods achieve moderate compressive strength with low energy consumption but face challenges such as binder dependency and vacuum instability.By contrast,high-energy beam techniques enable binder-free fabrication with better compatibility for in-situ resource utilization,though they suffer from porosity,high energy intensity,and geometric limitations.In the context of lunar in-situ resource utilization(ISRU),low-temperature methods offer near-term feasibility for small-scale infrastructure,while high-energy approaches show promise for large-scale,autonomous construction by leveraging solar energy and raw regolith.Future advancements will hinge on hybrid systems that integrate material efficiency,energy sustainability,and robotic adaptability to overcome extreme environmental challenges.This review consolidates technological progress,identifies interdisciplinary synergies,and provides strategic insights into guiding the transition from Earth-dependent prototypes to self-sufficient lunar habitats,ultimately advancing the capability of humanity for a long-term extraterrestrial presence.展开更多
Osteogenesis is the process of bone formation mediated by the osteoblasts,participating in various bone-related physiological processes including bone development,bone homeostasis and fracture healing.It exhibits temp...Osteogenesis is the process of bone formation mediated by the osteoblasts,participating in various bone-related physiological processes including bone development,bone homeostasis and fracture healing.It exhibits temporal and spatial interconnectivity with angiogenesis,constructed by multiple forms of cell communication occurring between bone and vascular endothelial cells.Molecular regulation among different cell types is crucial for coordinating osteogenesis and angiogenesis to facilitate bone remodeling,fracture healing,and other bone-related processes.The transmission of signaling molecules and the activation of their corresponding signal pathways are indispensable for various forms of cell communication.This communication acts as a“bridge”in coupling osteogenesis to angiogenesis.This article reviews the modes and processes of cell communication in osteogenesisangiogenesis coupling over the past decade,mainly focusing on interactions among bone-related cells and vascular endothelial cells to provide insights into the mechanism of cell communication of osteogenesis-angiogenesis coupling in different bone-related contexts.Moreover,clinical relevance and applications are also introduced in this review.展开更多
The carcass layer is the innermost structure of flexible marine risers and is responsible for resisting external pressure.It has an“S”section with a spiral interlocking feature.After the multi-pass roll forming of a...The carcass layer is the innermost structure of flexible marine risers and is responsible for resisting external pressure.It has an“S”section with a spiral interlocking feature.After the multi-pass roll forming of a flat steel strip,a carcass layer is formed by lock forming.During roll forming,the steel strip undergoes significant plastic deformation,and its local area accumulates residual stress owing to multiple loading and unloading cycles.These phenomena complicate the design and analysis of the carcass layer multi-pass roll forming(CLMRF)process and cause issues in the carcass layer during manufacturing,such as strip fracture and low forming quality.Thus,herein,CLMRF was investigated to clarify the stress distribution,and a parameter analysis was performed.First,the CLMRF process was designed on the basis of classical roll-forming design theory.Second,a finite element model was established,and CLMRF was simulated.Third,the distributions of the forming stress and residual stress of the strip during CLMRF were investigated.Finally,the influences of the strip thickness,roll gap,roll distance,and angular increment were investigated.The conclusions of this study can be used to provide technical guidance in the manufacturing of flexible risers.展开更多
Spiral bevel gears are critical transmission components,and are widely used in the aerospace field.This paper proposes a new multi-DOF envelope forming process for fabricating spiral bevel gears.Firstly,the multi-DOF ...Spiral bevel gears are critical transmission components,and are widely used in the aerospace field.This paper proposes a new multi-DOF envelope forming process for fabricating spiral bevel gears.Firstly,the multi-DOF envelope forming principle of spiral bevel gears is proposed.Secondly,the design methods for the envelope tool geometry and movement are proposed based on the envelope geometry and movement relationships.Thirdly,the metal flow and tooth filling laws are revealed through 3D FE simulation of the multi-DOF envelope forming process of a typical spiral bevel gear.Fourthly,a new method for separating the envelope tool and the formed spiral bevel gear with back taper tooth is proposed to avoid their interference.Finally,experiments on multi-DOF envelope forming of this typical spiral bevel gear are conducted using new heavy load multi-DOF envelope forming equipment.The simulation and experimental results show the feasibility of the proposed multi-DOF envelope forming process for fabricating spiral bevel gears with back taper tooth and the corresponding process design methods.展开更多
文摘Considérée souvent en France comme discontinue,la transition du bati urbain-rural est largement envisagécomme continue au niveau international.Si la question de la forme urbaine n’est donc,aujourd’hui,plus en suspens du fait des très nombreusesétudesàl’échelle internationale,la limite urbain périurbain et rural isoléconvient d’être néanmoins encore réinterrogée.La notion de proxémique développée dans les années 1970,pourrait permettre une résolution du problème.Utiliser cette notion pour revoir la métrique géographique pourrait permettre de réviser la limite urbain-campagne et raisonner alors sur un espace continu au-delàmême des limites du périurbain.
基金financially supported by the National Key R&D Program of China(No.2024YFE0108800/T24KITG014)the National Natural Science Foundation of China(No:52475411)the International Partnership Program of Chinese Academy of Sciences(No.172GJHZ2022096FN)。
文摘Taking half-tube part with curvature as an example,the Impact Hydroforming(IHF)characteristics were studied by combining the actual forming experiment and numerical simulation.The IHF experiment showed that wrinkles appeared at the bottom of the part during single-step forming,but no wrinkles were observed during double-step forming.The thinning rate and deviation of the wall thickness of the part in each area were less than 20%and 2.7 mm,correspondingly,and the drawing depth of the part reached 45.8 mm.The effect of double-step forming was better than that of single-step forming,which was related to the IHF forming law.Besides,the characteristics of the IHF process were studied by numerical simulation.The results indicated that when double-step forming was utilized,there was almost no velocity field in the opposite direction of deformation after the bottom of the part contacted the die,and the existence of stress state at the bottom would restrain and eliminate the wrinkles.The inertia effect evolved with the driving pressure.Specially,the inertia effect can improve the flow of metal and reduce the deviation of the wall thickness of the part under double-step forming.
文摘RENEWING THE FORBIDDEN CITY’S CENTURY-OLD LEGACY.Oriental Outlook.27 November 2025.At sunrise,the Forbidden City glows under a veil of gold;at night,it retreats into quiet dignity.But the palace never really sleeps.As visitors depart,the“digital relic vault”awakens online,where porcelain,calligraphy,jade and timepieces reveal their beauty in virtual form.History continues to breathe in the data stream.
基金the supports of the National Natural Science Foundation of China(Grant No.52375378)。
文摘The multi-pass intermittent local loading process,which features a more flexible processing path,can further enhance the second material distribution during local loading,improve the formability of components,and reduce forming loads.However,the absence of compatible forming equipment makes it difficult to control the constraint in the unloaded zones during the forming process.This difficulty complicates coordination and control of deformation,particularly for asymmetric rib-web components.Additionally,the current implementation involves multi-fire heating,a long process flow,and high energy consumption,which limits the popularization and application of the local loading process.In this study,a new multi-pass local loading hydraulic forming apparatus that can quickly and reliably switch between heavy-load deformation and low-load constraint for different local loading sub-dies was developed.A 10-tonne laboratory prototype was developed,and the forming characteristics during the forming process as well as the response characteristics of the hydraulic system during the multi-pass intermittent local loading of rib-web component were investigated using numerical simulations and physical experiments.Results indicated that,compared to a whole loading process with the same initial geometry of billet,the total forming load(i.e.,the sum of loaded and restrained loads)is reduced by more than 40%with the local loading process,and by nearly 50%with multi-pass local loading.The multi-pass local loading process allows for more effective control of material flow compared to single-pass local loading,leading to improved cavity filling and reduced flow line disturbance.For a large-scale,complex titanium alloy bulkhead,the cavity filling problem was addressed by optimizing the multi-pass local loading path with an unequal thickness billet.The dynamic performance of the multi-pass local loading hydraulic system was found to be robust,with stable pressure transitions during motion and load switching for the sub-die(s).The dynamic characteristic of the hydraulic cylinder when switching from non-moving/unloaded state to a moving/loading state are consistent whether a load is present or not.However,the dynamic characteristics differ when switching from a moving/loading state to non-moving/unloaded state,showing opposite behavior.The developed hydraulic drive mechanism provides a way for implementation of multi-pass local loading without auxiliary operation and extra heating.The results of the study provide a foundation for the industrial production of large-scale,complex components with reduced force requirement and low-energy consumption.
基金Supported by National Natural Science Foundation of China(12161078)Foundation for Innovative Fundamental Research Group Project of Gansu Province(24JRRA778)Project of Northwest Normal University(20240010)。
文摘In this paper,we studyλ-biharmonic hypersurfaces M_(r)^(5) of 6-dimensional pseudo Riemannian space form N_(p)^(6)(c)with the indexs 0≤p≤6,r=p−1 or p,and constant curvature c.It was proved that if the shape operator of M_(r)^(5) is diagonalizable,then the mean curvature is a constant.As an application,we find some types of biharmonic hypersurfaces of N_(p)^(6)(c)are minimal.
基金co-supported by the National Natural Science Foundation of China(Nos 52475346 and U21A20130)the Natural Science Foundation of Hunan Province,China(No.2023JJ10019)+1 种基金China Postdoctoral Science Foundation(No.2022M712642)Hunan Science and Technology Innovation Plan,China(2023RC1068)。
文摘Aviation aluminum alloys,primarily from the Al-Cu,Al-Zn-Mg-(Cu),and Al-Li series,have been widely applied over six decades,greatly advancing the aviation industry.However,their Corrosion Fatigue(CF)properties impede further advancements,prompting extensive research into their CF behaviors and underlying mechanisms.This review comprehensively evaluates previous studies on their development history,CF mechanisms,and key influencing factors.First,the historical evolution of aerospace aluminum alloys is summarized.Then,the currently recognized four crack initiation mechanisms and three crack propagation mechanisms are concluded,and the effects of external and internal factors on CF performance are discussed.The paper also reviews three methods and CF life prediction models for characterizing the CF behavior of aerospace aluminum alloys.Most existing studies on the CF behavior of aluminum alloys are based on the single corrosive environment,neglecting the fact that aircrafts experience multiple corrosive environments during service.However,the most critical scientific challenge is how to enhance their CF properties under increasingly demanding service conditions.For the purpose,this paper introduces advanced forming techniques based on the microstructural control,such as Equal Channel Angular Pressing(ECAP)and High-Pressure Torsion(HPT),aimed at laying the theoretical foundation for improving CF properties through microstructural regulation.
基金supported by the National Natural Science Foundation of China(Grant Nos.52271307,52061135107,52192692,11802025)the Liao Ning Excellent Youth Fund Program(Grant No.2023JH3/10200012)+1 种基金the Liao Ning Revitalization Tal-ents Program(Grant No.XLYC1908027)the Fundamental Research Funds for the Central Universities(Grant Nos.DUT20RC(3)025,DUT20TD108,DUT20LAB308)。
文摘In order to investigate the penetration performance of Linear-Shaped Charge(LSC),Embowed LinearShaped Charge(ELSC),and Embowed Linear Explosively Formed Projectile(ELEFP)on T-shaped stiffened plates,a series of near-field air-burst experiments are conducted.The damage modes and characteristics of the target plates are compared and analyzed.Each flat plate section is completely punctured,resulting in a penetration hole.The damage modes induced by the three charge types on the stiffened plate structure are consistent,characterized by shear failure in the central region of the flat plate due to penetration by the penetrator,localized plastic deformation of the flat plate,and local penetration failure resulting from partial perforation of the central stiffener.The penetration lengths caused by ELSC and ELEFP are 45.1%and 46.1% larger than that of LSC,while the half-width of the penetration hole generated by ELEFP is 54.2% and 24.7% smaller than that of ELSC and LSC,respectively.The penetration height caused by ELEFP are 17.5%and 62.1% larger than that of ELSC and LSC,respectively.The stiffener effectively segments the damage area,enhancing the local structural strength and limiting the extent of plastic deformation in the flat plate section.The comparative results show that the ELSC proves to be more effective for efficient large-scale damage,and ELEFP is more suitable for achieving efficient localized damage.
基金Supported by National Natural Science Foundation of China(Grant Nos.52422510,52373320,52175360,50725517)the Young Elite Scientists Sponsorship Program by China Association for Science and Technology(Grant No.2021QNRC001)+1 种基金the Key R&D Program of Hubei Province(Grant No.2024BAB080)Natural Science Foundation of Wuhan(Grant No.2024040801020257).
文摘In aerospace,nuclear power,and new energy vehicles industries,utilizing integrated metal components with extreme sizes and/or structures is crucial for achieving significant weight-saving,performance-improvement,and excellent reliability.These components,made from metal sheets,rings,or tubes,exhibit characteristics like ultra-thin,ultra-thick,ultra-large,ultra-long,ultra-high ribs,and large variable diameters.During plastic de-formation in metal forming processes,defects such as ruptures,wrinkles,excessive strain differences,and un-expected weak performance areas are likely to occur due to the intersection of multiple effects in different research disciplines,including materials science,processes,and mechanics of materials.Consequently,the smooth forming of integrated parts is difficult.It is the first time to review,summarize,and analyze the ad-vancement of forming methods for producing integrated parts with extreme sizes and structures.The general academic ideas to change the process conditions and sequences to optimize stress state and improve plastic deformation ability for forming the components with extreme sizes/structures are introduced.Practical ex-amples,discussed in detail in the paper,include the forming of(i)integrated ultra-thin and ultra-thick sheet components;(ii)integrated ultra-large size ring components with thin wall and high ribs;and(iii)integrated ultra-long tube components with large perimeter difference.Various plasticity technologies and process se-quences have been developed.The key processes and applications of the technologies are discussed in detail,which achieve successful plastic forming of integrated components.This paper provides state-of-the-art and perspectives for the rapidly advancing material forming fields of key metal components for the next generation of equipment.
基金FEDER/Ministerio de Ciencia,Innovacióny Universidades-Agencia Estatal de Investigación(PID2023-147425OB-I00 to FC)Agència de Gestiód’Ajuts Universitaris i de Recerca(AGAUR)-Generalitat de Catalunya(2021 SGR 00698 to FC).
文摘G protein-coupled receptor 37(GPR37)is an orphan receptor predominantly expressed in the brain,particularly in oligodendrocytes and certain types of neurons.Notably,it has been shown that the N-terminal domain of GPR37 undergoes proteolysis under normal physiological conditions,resulting in the formation of cleaved receptor forms and the release of its ectodomain(ecto-GPR37)into the extracellular milieu(Mattila et al.,2021).Importantly,ecto-GPR37 density is increased in cerebrospinal fluid(CSF)of patients suffering from sporadic Parkinson’s disease(PD),together with an abnormal GPR37 processing in post-mortem PD substantia nigra(Moratóet al.,2021;Figure 1A).
基金Key Research and Development Program of Shaanxi Province(2022GY-410)Funding of Western Titanium Technologies Co.,Ltd(WX2210)。
文摘Based on the microstructure characterization,electrochemical impedance spectroscopy,potentiodynamic polarization,and immersion corrosion,this work comparatively analyzed the differences in the electrochemical corrosion morphology and post-foil formation surface morphology of laser beam welded(LBW)sample and spin-formed sample,and compared the corrosion resistance and Cu foil formation ability of two samples in H_(2)SO_(4)/NaCl solution and CuSO_(4) reducing electrolyte.Results show that in H_(2)SO_(4) and NaCl solutions,LBW sample and spin-formed sample exhibit excellent passivation ability and corrosion resistance.Both samples show uniform corrosion morphologies and similar corrosion resistance in the strong acidic solution containing Cl^(-).Meanwhile,the Cu foil formation ability of the welded joint is similar to that of the spin-formed sample,and both samples obtain intact Cu foils with high-quality surfaces and small differences in properties.
基金supported by the National Key Research and Development Program of China(2023YFF0805602)National Natural Science Foundation of China(32225032,32001192,32271597)+1 种基金the Innovation Base Project of Gansu Province(2021YFF0703904)the Science and Technology Program of Gansu Province(24JRRA515,22JR5RA525,23JRRA1157).
文摘Studies on plant diversity are usually based on the total number of species in a community.However,few studies have examined species richness(SR)of different plant life forms in a community along largescale environmental gradients.Particularly,the relative importance(RIV)of different plant life forms in a community and how they vary with environmental variables are still unclear.To fill these gaps,we determined plant diversity of ephemeral plants,annual herbs,perennial herbs,and woody plants from 187 sites across drylands in China.The SR patterns of herbaceous plants,especially perennial herbs,and their RIV in plant communities increased with increasing precipitation and soil nutrient content;however,the RIV of annual herbs was not altered along these gradients.The SR and RIV of ephemeral plants were affected mainly by precipitation seasonality.The SR of woody plants had a unimodal relationship with air temperature and exhibited the highest RIV and SR percentage in plant communities under the harshest environments.An obvious shift emerged in plant community composition,SR and their critical impact factors at 238.5 mm of mean annual precipitation(MAP).In mesic regions(>238.5 mm),herbs were the dominant species,and the SR displayed a relatively slow decreasing rate with increasing aridity,which was mediated mainly by MAP and soil nutrients.In arid regions(<238.5 mm),woody plants were the dominant species,and the SR displayed a relatively fast decreasing rate with increasing aridity,which was mediated mainly by climate variables,especially precipitation.Our findings highlight the importance of comparative life form studies in community structure and biodiversity,as their responses to gradients differed substantially on a large scale.
基金supported in part by financial support from the National Key R&D Program of China(No.2023YFB3407003)the National Natural Science Foundation of China(No.52375378).
文摘A new analytical model for geometric size and forming force prediction in incremental flanging(IF)is presented in this work.The complex deformation characteristics of IF are considered in the modeling process,which can accurately describe the strain and stress states in IF.Based on strain analysis,the model can predict the material thickness distribution and neck height after IF.By considering contact area,strain characteristics,material thickness changes,and friction,the model can predict specific moments and corresponding values of maximum axial forming force and maximum horizontal forming force during IF.In addition,an IF experiment involving different tool diameters,flanging diameters,and opening hole diameters is conducted.On the basis of the experimental strain paths,the strain characteristics of different deformation zones are studied,and the stable strain ratio is quantitatively described through two dimensionless parameters:relative tool diameter and relative hole diameter.Then,the changing of material thickness and forming force in IF,and the variation of minimum material thickness,neck height,maximum axial forming force,and maximum horizontal forming force with flanging parameters are studied,and the reliability of the analytical model is verified in this process.Finally,the influence of the horizontal forming force on the tool design and the fluctuation of the forming force are explained.
基金granted by the Xinjiang Geological Exploration Fund。
文摘The northwestern margin of Junggar Basin is the region with the richest oil sand resources in China.For better understanding the enrichment rules and deployment of exploration and development of regional oil sand,it is of great scientific significance to study the accumulation conditions of oil sand in different strata and mining areas of the Junggar Basin.Through a large number of field investigations,drilling verification and sampling tests,it is found that the oil sand in the region covers an area of 2000 km^(2),with shallow and thick reservoir,and predicted resource of 180 million tons.The oil sand resources are mainly distributed in four geological strata,namely the Middle Triassic Karamay Formation,Early Jurassic Badaowan Formation,Late Jurassic Qigu Formation,and Early Cretaceous Qingshuihe Formation.The reservoir is mainly composed of sandstone with high porosity and permeability,and the reservoir space is mainly intergranular pores with a medium average oil content.The oil sand deposit in the region is a typical destructive oil reservoir.The crude oil in the oil sand layer is degraded and thickened from the deep to the shallow,the content of saturated hydrocarbon decreased,and the content of aromatic hydrocarbon,non-hydrocarbon and asphaltene increased.The oil source comes from the deep Permian hydrocarbon-generating depression.Unconformities,faults and marginal fan delta-braided river depositional systems constitute effective migration and storage systems.Caprocks of the Upper Triassic Baijiantan Formation,Lower Jurassic Sangonghe Formation and Lower Cretaceous Hutubihe Formation were formed by three large scale lake transgressions.The Indosinian,Yanshan and Late Yanshan movements are the main driving forces for the migration of deep oil and gas to the shallow edge to form oil sand deposits.It is considered that the oil sand in the northwestern margin of Junggar Basin is of a slope complex migration type.
基金supported by National Key Research and Development Program of China(Grant Nos.2023YFB3711300,2021YFF0500300)Space Application System of China Manned Space ProgramStrategic Research and Consulting Project of the Chinese Academy of Engineering(Grant No.2023-JB-09-10)。
文摘Lunar in-situ construction using additive manufacturing(AM)technology has emerged as a critical pathway for sustainable extraterrestrial exploration.This review systematically evaluates two dominant AM paradigms for lunar regolith processing:low-temperature deposition forming(material extrusion and binder jetting),and high-energy beam additive manufacturing(powder bed fusion and directed energy deposition).Low-temperature methods achieve moderate compressive strength with low energy consumption but face challenges such as binder dependency and vacuum instability.By contrast,high-energy beam techniques enable binder-free fabrication with better compatibility for in-situ resource utilization,though they suffer from porosity,high energy intensity,and geometric limitations.In the context of lunar in-situ resource utilization(ISRU),low-temperature methods offer near-term feasibility for small-scale infrastructure,while high-energy approaches show promise for large-scale,autonomous construction by leveraging solar energy and raw regolith.Future advancements will hinge on hybrid systems that integrate material efficiency,energy sustainability,and robotic adaptability to overcome extreme environmental challenges.This review consolidates technological progress,identifies interdisciplinary synergies,and provides strategic insights into guiding the transition from Earth-dependent prototypes to self-sufficient lunar habitats,ultimately advancing the capability of humanity for a long-term extraterrestrial presence.
基金supported by central government-guided major science and technology project of Hebei province 236Z7709G(M.C.Q.)Tangshan science and technology project 23130216E(M.C.Q.)+8 种基金key research projects of North China University of Science and Technology ZD-YG-202309(M.C.Q.)National Natural Science Foundations of China 82230030 and 81871492(Y.L.)Beijing International Science and Technology Cooperation Project Z221100002722003(Y.L.)Beijing Natural Science Foundation L234017(Y.L.)Peking University Medicine plus X Pilot Program-Key Technologies R&D Project 2024YXXLHGG004(Y.L.)Key R&D Plan of Ningxia Hui Autonomous Region 2020BCG01001(Y.L.)First-Class Discipline Team of Kunming Medical University 2024XKTDTS08(Y.L.)Innovative Research Team of High-level Local Universities in Shanghai SHSMU-ZLCX20212402(Y.L.)Postdoctoral Fellowship Program of CPSF under Grant Number GZB20240038(X.J.C.).
文摘Osteogenesis is the process of bone formation mediated by the osteoblasts,participating in various bone-related physiological processes including bone development,bone homeostasis and fracture healing.It exhibits temporal and spatial interconnectivity with angiogenesis,constructed by multiple forms of cell communication occurring between bone and vascular endothelial cells.Molecular regulation among different cell types is crucial for coordinating osteogenesis and angiogenesis to facilitate bone remodeling,fracture healing,and other bone-related processes.The transmission of signaling molecules and the activation of their corresponding signal pathways are indispensable for various forms of cell communication.This communication acts as a“bridge”in coupling osteogenesis to angiogenesis.This article reviews the modes and processes of cell communication in osteogenesisangiogenesis coupling over the past decade,mainly focusing on interactions among bone-related cells and vascular endothelial cells to provide insights into the mechanism of cell communication of osteogenesis-angiogenesis coupling in different bone-related contexts.Moreover,clinical relevance and applications are also introduced in this review.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.U1906233 and 52201312)Dalian High-Level Talent Innovation Program(Grant No.2021RD16)the Natural Science Foundation of Liaoning Province of China(Grant No.2023-BSBA-052).
文摘The carcass layer is the innermost structure of flexible marine risers and is responsible for resisting external pressure.It has an“S”section with a spiral interlocking feature.After the multi-pass roll forming of a flat steel strip,a carcass layer is formed by lock forming.During roll forming,the steel strip undergoes significant plastic deformation,and its local area accumulates residual stress owing to multiple loading and unloading cycles.These phenomena complicate the design and analysis of the carcass layer multi-pass roll forming(CLMRF)process and cause issues in the carcass layer during manufacturing,such as strip fracture and low forming quality.Thus,herein,CLMRF was investigated to clarify the stress distribution,and a parameter analysis was performed.First,the CLMRF process was designed on the basis of classical roll-forming design theory.Second,a finite element model was established,and CLMRF was simulated.Third,the distributions of the forming stress and residual stress of the strip during CLMRF were investigated.Finally,the influences of the strip thickness,roll gap,roll distance,and angular increment were investigated.The conclusions of this study can be used to provide technical guidance in the manufacturing of flexible risers.
基金the National Science and Technology Major Project of China(No.2019-VII0017e0158)the National Natural Science Foundation of China(No.U21A20131)+1 种基金the Industry-University Research Cooperation Project,China(No.HFZL2020CXY025)the National Key Laboratory of Science and Technology on Helicopter Transmission,China(No.HTL-O-21G05).
文摘Spiral bevel gears are critical transmission components,and are widely used in the aerospace field.This paper proposes a new multi-DOF envelope forming process for fabricating spiral bevel gears.Firstly,the multi-DOF envelope forming principle of spiral bevel gears is proposed.Secondly,the design methods for the envelope tool geometry and movement are proposed based on the envelope geometry and movement relationships.Thirdly,the metal flow and tooth filling laws are revealed through 3D FE simulation of the multi-DOF envelope forming process of a typical spiral bevel gear.Fourthly,a new method for separating the envelope tool and the formed spiral bevel gear with back taper tooth is proposed to avoid their interference.Finally,experiments on multi-DOF envelope forming of this typical spiral bevel gear are conducted using new heavy load multi-DOF envelope forming equipment.The simulation and experimental results show the feasibility of the proposed multi-DOF envelope forming process for fabricating spiral bevel gears with back taper tooth and the corresponding process design methods.
