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
Developing precision forming of magnesium alloy micro-grooved heat pipes is of great significance for improving the lightweight level of aerospace thermal management systems.In this paper,the electrically-assisted ext...Developing precision forming of magnesium alloy micro-grooved heat pipes is of great significance for improving the lightweight level of aerospace thermal management systems.In this paper,the electrically-assisted extrusion of magnesium alloy heat pipes is explored,and the effects of extrusion and electrical parameters on the forming accuracy,microstructures,and mechanical properties are studied.Finite element simulation found that electrifying the extrusion ram and preheating the extrusion cylinder could effectively ensure the billet temperature,and an extrusion window(30-60 s)could be obtained.Reducing the extrusion velocity and increasing the current could both reduce the extrusion load.Within the range of the studied parameters,the micro-grooved heat pipes are relatively fully formed.It is found that increasing the extrusion velocity and electrical parameters would increase the grain size of the magnesium alloy.While the electrical parameter increases from 0 to 300 A,the grain size increases from~5.9 to~12.6μm,and the tensile strength and yield strength of the extruded profiles are also 20.7%and 16.8%lower than those without current.The tensile fracture surface shows that under the parameters of high extrusion velocity and high current,the fracture morphology changes from dimples and cleavage planes to large-area river patterns,and the fracture mode changes from the mixed ductile-brittle fracture to the brittle fracture.Under the extrusion parameters of 0.5 mm/s and 100 A,the extrusion load is reduced by 1.0-1.6 T,the cross-sectional filling rate is as high as 97.5%,and the size deviation of the micro-ribs(0.8 mm)is only±5μm.Simultaneously,under these parameters,the grain size does not significantly coarsen,and the strength and plasticity of the heat pipe increase slightly.This work provides theoretical and technical support for the development of precision forming technology of lightweight aerospace heat pipes.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
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
Auxin regulates plant growth by integrating transport and signaling.Polar auxin transport establishes auxin gradients essential for development,with PIN-FORMED(PIN)efflux carriers generating directionality and AUXIN1/...Auxin regulates plant growth by integrating transport and signaling.Polar auxin transport establishes auxin gradients essential for development,with PIN-FORMED(PIN)efflux carriers generating directionality and AUXIN1/LIKE-AUX1(AUX1/LAX)influx carriers ensuring efficient uptake.Canonical signaling begins when auxin binds TRANSPORT INHIBITOR RESPONSE 1/AUXIN SIGNALING F-BOX PROTEIN(TIR1/AFB)receptors,the F-box component of the SKP1-CULLIN1-F-box(SCF)E3 ubiquitin ligase complex(Gray et al.,2001).Auxin promotes recruitment and degradation of AUXIN/INDOLE-3-ACETIC ACID(AUX/IAA)repressors,thereby releasing AUXIN RESPONSE FACTOR(ARF)to activate transcription(Gray et al.,2001).Recent discoveries have expended this model.Cryo-electron microscopy(cryo-EM)structures of AUX1 clarified its proton(H+)-coupled import(Yang et al.,2025),and TIR1 was shown to function as an adenylate cyclase(AC),producing c AMP to activate transcription(Chen et al.,2025).Synthetic promoter studies further revealed a bi-layer ARF/cis-element code shaping cel type-specific gene expression(Martin-Arevalil o et al.,2025).展开更多
The Recommendations of the Central Committee of the Communist Party of China for Formulating the 15th Five-Year Plan for National Economic and Social Development call for inspiring the cultural creativity of our entir...The Recommendations of the Central Committee of the Communist Party of China for Formulating the 15th Five-Year Plan for National Economic and Social Development call for inspiring the cultural creativity of our entire nation,further integrating culture and technology,empowering cultural development with digital and intelligent technologies,and shifting to an IT-based development model,while working to foster new forms of cultural business,and extending the reach and appeal of Chinese civilization.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
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
In integrated circuit(IC)manufacturing,fast,nondestructive,and precise detection of defects in patterned wafers,realized by bright-field microscopy,is one of the critical factors for ensuring the final performance and...In integrated circuit(IC)manufacturing,fast,nondestructive,and precise detection of defects in patterned wafers,realized by bright-field microscopy,is one of the critical factors for ensuring the final performance and yields of chips.With the critical dimensions of IC nanostructures continuing to shrink,directly imaging or classifying deep-subwavelength defects by bright-field microscopy is challenging due to the well-known diffraction barrier,the weak scattering effect,and the faint correlation between the scattering cross-section and the defect morphology.Herein,we propose an optical far-field inspection method based on the form-birefringence scattering imaging of the defective nanostructure,which can identify and classify various defects without requiring optical super-resolution.The technique is built upon the principle of breaking the optical form birefringence of the original periodic nanostructures by the defect perturbation under the anisotropic illumination modes,such as the orthogonally polarized plane waves,then combined with the high-order difference of far-field images.We validated the feasibility and effectiveness of the proposed method in detecting deep subwavelength defects through rigid vector imaging modeling and optical detection experiments of various defective nanostructures based on polarization microscopy.On this basis,an intelligent classification algorithm for typical patterned defects based on a dual-channel AlexNet neural network has been proposed,stabilizing the classification accuracy ofλ/16-sized defects with highly similar features at more than 90%.The strong classification capability of the two-channel network on typical patterned defects can be attributed to the high-order difference image and its transverse gradient being used as the network’s input,which highlights the polarization modulation difference between different patterned defects more significantly than conventional bright-field microscopy results.This work will provide a new but easy-to-operate method for detecting and classifying deep-subwavelength defects in patterned wafers or photomasks,which thus endows current online inspection equipment with more missions in advanced IC manufacturing.展开更多
The influence of geometric configuration on the friction characteristics during incremental sheet forming of AA5052 was analyzed by integrating surface morphology and its characteristic parameters,along with plastic s...The influence of geometric configuration on the friction characteristics during incremental sheet forming of AA5052 was analyzed by integrating surface morphology and its characteristic parameters,along with plastic strain,contact pressure,and area.The interface promotes lubrication and support when wall angles were≤40°,a 0.5 mm-thin sheet was used,and a 10 mm-large tool radius was employed.This mainly results in micro-plowing and plastic extrusion flow,leading to lower friction coefficient.However,when wall angles exceed 40°,significant plastic strain roughening occurs,leading to inadequate lubrication on the newly formed surface.Increased sheet thickness and decreased tool radius elevate contact pressure.These actions trigger micro-cutting and adhesion,potentially leading to localized scuffing and dimple tears,and higher friction coefficient.The friction mechanisms remain unaffected by the part’s plane curve features.As the forming process progresses,abrasive wear intensifies,and surface morphology evolves unfavorably for lubrication and friction reduction.展开更多
The contact problem of deformed rough surfaces exists widely in complex engineering structures.How to reveal the influence mechanism of surface deformation on the contact properties is a key issue in evaluating the in...The contact problem of deformed rough surfaces exists widely in complex engineering structures.How to reveal the influence mechanism of surface deformation on the contact properties is a key issue in evaluating the interface performances of the engineering structures.In this paper,a contact model is established,which is suitable for tensile and bending deformed contact surfaces.Four contact forms of asperities are proposed,and their distribution characteristics are analyzed.This model reveals the mechanism of friction generation from the perspective of the force balance of asperity.The results show the contact behaviors of the deformed contact surface are significantly different from that of the plane contact,which is mainly reflected in the change in the number of contact asperities and the real contact area.This study suggests that the real contact area of the interface can be altered by applying tensile and bending strains,thereby regulating its contact mechanics and conductive behavior.展开更多
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.
基金supported by the National Natural Science Foundation of China(Grant Nos.U24B2056,52505361)China Postdoctoral Science Foundation(Grant No.2025M774308)。
文摘Developing precision forming of magnesium alloy micro-grooved heat pipes is of great significance for improving the lightweight level of aerospace thermal management systems.In this paper,the electrically-assisted extrusion of magnesium alloy heat pipes is explored,and the effects of extrusion and electrical parameters on the forming accuracy,microstructures,and mechanical properties are studied.Finite element simulation found that electrifying the extrusion ram and preheating the extrusion cylinder could effectively ensure the billet temperature,and an extrusion window(30-60 s)could be obtained.Reducing the extrusion velocity and increasing the current could both reduce the extrusion load.Within the range of the studied parameters,the micro-grooved heat pipes are relatively fully formed.It is found that increasing the extrusion velocity and electrical parameters would increase the grain size of the magnesium alloy.While the electrical parameter increases from 0 to 300 A,the grain size increases from~5.9 to~12.6μm,and the tensile strength and yield strength of the extruded profiles are also 20.7%and 16.8%lower than those without current.The tensile fracture surface shows that under the parameters of high extrusion velocity and high current,the fracture morphology changes from dimples and cleavage planes to large-area river patterns,and the fracture mode changes from the mixed ductile-brittle fracture to the brittle fracture.Under the extrusion parameters of 0.5 mm/s and 100 A,the extrusion load is reduced by 1.0-1.6 T,the cross-sectional filling rate is as high as 97.5%,and the size deviation of the micro-ribs(0.8 mm)is only±5μm.Simultaneously,under these parameters,the grain size does not significantly coarsen,and the strength and plasticity of the heat pipe increase slightly.This work provides theoretical and technical support for the development of precision forming technology of lightweight aerospace heat pipes.
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Young Scientists Fund of the National Natural Science Foundation of China(61572004,L.L.,32202496,H.H.)。
文摘Auxin regulates plant growth by integrating transport and signaling.Polar auxin transport establishes auxin gradients essential for development,with PIN-FORMED(PIN)efflux carriers generating directionality and AUXIN1/LIKE-AUX1(AUX1/LAX)influx carriers ensuring efficient uptake.Canonical signaling begins when auxin binds TRANSPORT INHIBITOR RESPONSE 1/AUXIN SIGNALING F-BOX PROTEIN(TIR1/AFB)receptors,the F-box component of the SKP1-CULLIN1-F-box(SCF)E3 ubiquitin ligase complex(Gray et al.,2001).Auxin promotes recruitment and degradation of AUXIN/INDOLE-3-ACETIC ACID(AUX/IAA)repressors,thereby releasing AUXIN RESPONSE FACTOR(ARF)to activate transcription(Gray et al.,2001).Recent discoveries have expended this model.Cryo-electron microscopy(cryo-EM)structures of AUX1 clarified its proton(H+)-coupled import(Yang et al.,2025),and TIR1 was shown to function as an adenylate cyclase(AC),producing c AMP to activate transcription(Chen et al.,2025).Synthetic promoter studies further revealed a bi-layer ARF/cis-element code shaping cel type-specific gene expression(Martin-Arevalil o et al.,2025).
文摘The Recommendations of the Central Committee of the Communist Party of China for Formulating the 15th Five-Year Plan for National Economic and Social Development call for inspiring the cultural creativity of our entire nation,further integrating culture and technology,empowering cultural development with digital and intelligent technologies,and shifting to an IT-based development model,while working to foster new forms of cultural business,and extending the reach and appeal of Chinese civilization.
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 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.
基金funded by National Natural Science Foundation of China(Grant Nos.52130504,52305577,and 52175509)the Key Research and Development Plan of Hubei Province(Grant No.2022BAA013)+4 种基金the Major Program(JD)of Hubei Province(Grant No.2023BAA008-2)the Interdisciplinary Research Program of Huazhong University of Science and Technology(2023JCYJ047)the Innovation Project of Optics Valley Laboratory(Grant No.OVL2023PY003)the Postdoctoral Fellowship Program(Grade B)of China Postdoctoral Science Foundation(Grant No.GZB20230244)the fellowship from the China Postdoctoral Science Foundation(2024M750995)。
文摘In integrated circuit(IC)manufacturing,fast,nondestructive,and precise detection of defects in patterned wafers,realized by bright-field microscopy,is one of the critical factors for ensuring the final performance and yields of chips.With the critical dimensions of IC nanostructures continuing to shrink,directly imaging or classifying deep-subwavelength defects by bright-field microscopy is challenging due to the well-known diffraction barrier,the weak scattering effect,and the faint correlation between the scattering cross-section and the defect morphology.Herein,we propose an optical far-field inspection method based on the form-birefringence scattering imaging of the defective nanostructure,which can identify and classify various defects without requiring optical super-resolution.The technique is built upon the principle of breaking the optical form birefringence of the original periodic nanostructures by the defect perturbation under the anisotropic illumination modes,such as the orthogonally polarized plane waves,then combined with the high-order difference of far-field images.We validated the feasibility and effectiveness of the proposed method in detecting deep subwavelength defects through rigid vector imaging modeling and optical detection experiments of various defective nanostructures based on polarization microscopy.On this basis,an intelligent classification algorithm for typical patterned defects based on a dual-channel AlexNet neural network has been proposed,stabilizing the classification accuracy ofλ/16-sized defects with highly similar features at more than 90%.The strong classification capability of the two-channel network on typical patterned defects can be attributed to the high-order difference image and its transverse gradient being used as the network’s input,which highlights the polarization modulation difference between different patterned defects more significantly than conventional bright-field microscopy results.This work will provide a new but easy-to-operate method for detecting and classifying deep-subwavelength defects in patterned wafers or photomasks,which thus endows current online inspection equipment with more missions in advanced IC manufacturing.
基金the support of the Key Research and Development Program of Shaanxi Province,China(No.2021GXLH-Z-049)。
文摘The influence of geometric configuration on the friction characteristics during incremental sheet forming of AA5052 was analyzed by integrating surface morphology and its characteristic parameters,along with plastic strain,contact pressure,and area.The interface promotes lubrication and support when wall angles were≤40°,a 0.5 mm-thin sheet was used,and a 10 mm-large tool radius was employed.This mainly results in micro-plowing and plastic extrusion flow,leading to lower friction coefficient.However,when wall angles exceed 40°,significant plastic strain roughening occurs,leading to inadequate lubrication on the newly formed surface.Increased sheet thickness and decreased tool radius elevate contact pressure.These actions trigger micro-cutting and adhesion,potentially leading to localized scuffing and dimple tears,and higher friction coefficient.The friction mechanisms remain unaffected by the part’s plane curve features.As the forming process progresses,abrasive wear intensifies,and surface morphology evolves unfavorably for lubrication and friction reduction.
基金This work are supported by the Natural Science Foundation of China General Program(Grant No.12272157)the Natural Science Foundation of China Major Program(Grant No.12327901)+1 种基金the Fundamental Research Funds for the Central Universities(Grant No.lzujbky-2023-ey05)the 111 Project(Grant No.B14044).
文摘The contact problem of deformed rough surfaces exists widely in complex engineering structures.How to reveal the influence mechanism of surface deformation on the contact properties is a key issue in evaluating the interface performances of the engineering structures.In this paper,a contact model is established,which is suitable for tensile and bending deformed contact surfaces.Four contact forms of asperities are proposed,and their distribution characteristics are analyzed.This model reveals the mechanism of friction generation from the perspective of the force balance of asperity.The results show the contact behaviors of the deformed contact surface are significantly different from that of the plane contact,which is mainly reflected in the change in the number of contact asperities and the real contact area.This study suggests that the real contact area of the interface can be altered by applying tensile and bending strains,thereby regulating its contact mechanics and conductive behavior.
