Fractal assembly in discrete structures,especially for artificial supramolecular species,has attracted significantly increased interest over the past two decades.In this study,we present the precisely controlled fract...Fractal assembly in discrete structures,especially for artificial supramolecular species,has attracted significantly increased interest over the past two decades.In this study,we present the precisely controlled fractal expanding synthesis of a novel triangular prism supramolecule featuring Sierpiński triangular face,which was achieved through a module-intervened self-expansion strategy.The homoleptic S1 was firstly synthesized through the assembly of ligand L1 with Zn^(2+)ions.Based on the triangular-faced prism S1,we further introduced Sierpiński triangular faces on the section of the heteroleptic supramolecular cage S2 with an expanded inner cavity and more abundant active sites for photocatalytic properties.The topotactic architectures for both S1 and S2 were fully characterized by nuclear magnetic resonance spectroscopy,high-resolution electrospray ionization mass spectrometry,transmission electron microscopy,and atomic force microscopy.Furthermore,the enhanced photocatalytic activity of the fractal expanded S2 was performed via the superior amine oxidative efficiency over S1.This study proposes the unprecedented fractal expanding strategy for three-dimensional supramolecular species with higher complexity,potentially opening new avenues for structural regulation of artificial fractal molecules.展开更多
Working memory is an executive memory process that includes encoding,maintenance,and retrieval.These processes can be modulated by transcranial alternating current stimulation(tACS)with sinusoidal waves.However,little...Working memory is an executive memory process that includes encoding,maintenance,and retrieval.These processes can be modulated by transcranial alternating current stimulation(tACS)with sinusoidal waves.However,little is known about the impact of the rate of current change on working memory.In this study,we aimed to investigate the effects of two types of tACS with different rates of current change on working memory performance and brain activity.We applied a randomized,single-blind design and divided 81 young participants who received triangular wave tACS,sinusoidal wave tACS,or sham stimulation into three groups.Participants performed n-back tasks,and electroencephalograms were recorded before,during,and after active or sham stimulation.Compared to the baseline,working memory performance(accuracy and response time)improved after stimulation under all stimulation conditions.According to drift-diffusion model analysis,triangular wave tACS significantly increased the efficiency of non-target information processing.In addition,compared with sham conditions,triangular wave tACS reduced alpha power oscillations in the occipital lobe throughout the encoding period,while sinusoidal wave tACS increased theta power in the central frontal region only during the later encoding period.The brain network connectivity results showed that triangular wave tACS improved the clustering coefficient,local efficiency,and node degree intensity in the early encoding stage,and these parameters were positively correlated with the non-target drift rate and decision starting point.Our findings on how tACS modulates working memory indicate that triangular wave tACS significantly enhances brain network connectivity during the early encoding stage,demonstrating an improvement in the efficiency of working memory processing.In contrast,sinusoidal wave tACS increased the theta power during the later encoding stage,suggesting its potential critical role in late-stage information processing.These findings provide valuable insights into the potential mechanisms by which tACS modulates working memory.展开更多
This paper presents an analysis of an equilateral triangular array formation initialization for space-based gravitational wave observatory(GWO)near Lagrange points in the circular-restricted three-body problem.A stabl...This paper presents an analysis of an equilateral triangular array formation initialization for space-based gravitational wave observatory(GWO)near Lagrange points in the circular-restricted three-body problem.A stable configuration is essential for the continuous observation of gravitational waves(GWs).However,the motion near the collinear libration points is highly unstable.This problem is examined by output regulation theory.Using the tracking aspect,the equilateral triangular array formation is established in two periods and the fuel consumption is calculated.Furthermore,the natural evolution of the formation without control input is analyzed,and the effective stability duration is quantified to determine the timing of control interventions.Finally,to observe the GWs in same direction with different frequency bands,scale reconfiguration is employed.展开更多
Thiswork explores aMagnetohydrodynamic(MHD)flowin a triangular cavitywith a thermally insulated baffle.Enclosure’s inclined wall is hotter,whereas the vertical border is adiabatic and the bottom is cooler.The study a...Thiswork explores aMagnetohydrodynamic(MHD)flowin a triangular cavitywith a thermally insulated baffle.Enclosure’s inclined wall is hotter,whereas the vertical border is adiabatic and the bottom is cooler.The study aims to clarify how geometric changes affect thermal performance and offers new perspectives on how to improve heat dissipation mechanisms.A COMSOL Multiphysics version 6.2 has been used to solve numerical solutions.Streamlines and thermal distributions are examined systematically in order to understand how the unique geometry and baffle size of triangular cavities can influence the fluid flow.This influence can result in optimized flow patterns,promoting efficient heat transfer by directing the fluid to specific areas that require more cooling.In comparison with conventional designs,this optimization results in more efficient convective heat transfer,which raises cooling efficiency and lowers thermal resistance.Furthermore,by strengthening heat transfer characteristics in heat transfer systems,these geometries increase thermal efficiency,which helps several sectors,including the production of electricity,HVAC,and the automobile industry.展开更多
As an important index to measure the degree of entanglement in quantum systems,concurrence plays an important role in practical research.In this paper,we study the concurrence between two qubits in triangular triple q...As an important index to measure the degree of entanglement in quantum systems,concurrence plays an important role in practical research.In this paper,we study the concurrence between two qubits in triangular triple quantum dot structure.Through calculation and simulation,it is found that concurrence is mainly affected by the interdot coupling strength t,Coulomb interactionU,temperature T,and electrode coupling G.Through comparative studies with parallel triple quantum dot structures,we demonstrate that the triangular geometry exhibits significantly enhanced concurrence under identical conditions.In addition,under the condition that concurrence exceeds 0.9,the functional relationship between t and U is obtained through simulation,which provides theoretical support for quantum dot regulation under high entanglement.Finally,we demonstrate the feasibility of implementing a three-qubit quantum gate,using the Toffoli gate as a representative example,under the condition that the triangular triple quantum dot system maintains high entanglement.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
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
Feature extraction of symmetrical triangular linear frequency modulation continuous wave （LFM- CW） signal is studied. Combined with its peculiar charaeteristics, a novel algorithm based on Wigner-Hough transform （...Feature extraction of symmetrical triangular linear frequency modulation continuous wave （LFM- CW） signal is studied. Combined with its peculiar charaeteristics, a novel algorithm based on Wigner-Hough transform （WHT） is presented for the deteetion and parameter estimation of this type of waveform. The initial frequency and chirp rate of each segment of this wave are estimated, and the peak-value searching steps in the parameter spaee is given. Compared with Wigner-Ville distribution （WVD）, Pseudo-Wigner-Ville distri- bution （PWD） and Smoothed-Peseudo-Wigner-Ville distribution （SPWD）, WHT has proven itself to be the best method for feature extraetion of symmetrical triangular LFMCW signal. In the end, Monte-Carlo simulations under different SNRs are earried out, with validating results on this method.展开更多
Similarity measure is an essential tool to compare and determine the degree of similarity between intuitionistic fuzzy sets (IFSs). In this paper, a new similarity measure between intuitionistic fuzzy sets based on th...Similarity measure is an essential tool to compare and determine the degree of similarity between intuitionistic fuzzy sets (IFSs). In this paper, a new similarity measure between intuitionistic fuzzy sets based on the mid points of transformed triangular fuzzy numbers is proposed. The proposed similarity measure provides reasonable results not only for the sets available in the literature but also gives very reasonable results, especially for fuzzy sets as well as for most intuitionistic fuzzy sets. To provide supportive evidence, the proposed similarity measure is tested on certain sets available in literature and is also applied to pattern recognition and medical diagnosis problems. It is observed that the proposed similarity measure provides a very intuitive quantification.展开更多
In this paper we study the formal triangular matrix ring T =and give some necessary and sufficient conditions for T to be (strongly) separative, m-fold stable and unit 1-stable. Moreover, a condition for finitely gene...In this paper we study the formal triangular matrix ring T =and give some necessary and sufficient conditions for T to be (strongly) separative, m-fold stable and unit 1-stable. Moreover, a condition for finitely generated projec-tive T-modules to have n in the stable range is given under the assumption that A and B are exchange rings.展开更多
The open-source finite element software,OpenSees,is widely used in the earthquake engineering community.However,the shell elements and explicit algorithm in OpenSees still require further improvements.Therefore,in thi...The open-source finite element software,OpenSees,is widely used in the earthquake engineering community.However,the shell elements and explicit algorithm in OpenSees still require further improvements.Therefore,in this work,a triangular shell element,NLDKGT,and an explicit algorithm are proposed and implemented in OpenSees.Specifically,based on the generalized conforming theory and the updated Lagrangian formulation,the proposed NLDKGT element is suitable for problems with complicated boundary conditions and strong nonlinearity.The accuracy and reliability of the NLDKGT element are validated through typical cases.Furthermore,by adopting the leapfrog integration method,an explicit algorithm in OpenSees and a modal damping model are developed.Finally,the stability and efficiency of the proposed shell element and explicit algorithm are validated through the nonlinear time-history analysis of a highrise building.展开更多
We consider the sufficient and necessary conditions for the formal triangular matrix ring being right minsymmetric, right DS, semicommutative, respectively.
In this paper we study Gorenstein(semiheredity)heredity,finite presentedness and F P-injectivity of modules over a formal triangular matrix ring.We provide necessary and sufficient conditions for such rings to be Gore...In this paper we study Gorenstein(semiheredity)heredity,finite presentedness and F P-injectivity of modules over a formal triangular matrix ring.We provide necessary and sufficient conditions for such rings to be Gorenstein(semihereditary)hereditary and investigate when a triangular matrix ring is an n-FC ring.展开更多
We implemented accurate FFD in terms of triangular Bezier surfaces as matrix multiplications in CUDA and rendered them via OpenGL. Experimental results show that the proposed algorithm is more efficient than the previ...We implemented accurate FFD in terms of triangular Bezier surfaces as matrix multiplications in CUDA and rendered them via OpenGL. Experimental results show that the proposed algorithm is more efficient than the previous GPU acceleration algorithm and tessel- lation shader algorithms.展开更多
A new method as a post-processing step is presented to improve the shape quality of triangular meshes, which uses a topological clean up procedure and discrete smoothing interpolate (DSI) algorithm together. T...A new method as a post-processing step is presented to improve the shape quality of triangular meshes, which uses a topological clean up procedure and discrete smoothing interpolate (DSI) algorithm together. This method can improve the angle distribution of mesh element. while keeping the resulting meshes conform to the predefined constraints which are inputted as a PSLG.展开更多
In this paper the sufficient and necessary conditions are given for a formal triangular matrix ring to be right PP, generalized right PP, or semihereditary, respectively.
基金supported by the Major Science and Technology Projects of Yunnan Province(No.202302AB080016)the National Natural Science Foundation of China(Nos.22101060,22371056,and 52303269)the Science and Technology Research Project of Guangzhou(Nos.202201020201 and 2023A03J0624)。
文摘Fractal assembly in discrete structures,especially for artificial supramolecular species,has attracted significantly increased interest over the past two decades.In this study,we present the precisely controlled fractal expanding synthesis of a novel triangular prism supramolecule featuring Sierpiński triangular face,which was achieved through a module-intervened self-expansion strategy.The homoleptic S1 was firstly synthesized through the assembly of ligand L1 with Zn^(2+)ions.Based on the triangular-faced prism S1,we further introduced Sierpiński triangular faces on the section of the heteroleptic supramolecular cage S2 with an expanded inner cavity and more abundant active sites for photocatalytic properties.The topotactic architectures for both S1 and S2 were fully characterized by nuclear magnetic resonance spectroscopy,high-resolution electrospray ionization mass spectrometry,transmission electron microscopy,and atomic force microscopy.Furthermore,the enhanced photocatalytic activity of the fractal expanded S2 was performed via the superior amine oxidative efficiency over S1.This study proposes the unprecedented fractal expanding strategy for three-dimensional supramolecular species with higher complexity,potentially opening new avenues for structural regulation of artificial fractal molecules.
基金supported by the Key-Area Research and Development Program of Guangdong Province(2023B0303030002)the Beijing Natural Science Foundation(IS23114,7242274)+4 种基金the China Postdoctoral Science Foundation(2023TQ0027 and 2024M754099)the STI 2030-Major Projects(2022ZD0208500)the National Natural Science Foundation of China(62336002,82071912,62406025,82202291,62373056,62306035)the Beijing Nova Program(20230484465)the Shenzhen Basic Research Program(JCYJ20241202124804007).
文摘Working memory is an executive memory process that includes encoding,maintenance,and retrieval.These processes can be modulated by transcranial alternating current stimulation(tACS)with sinusoidal waves.However,little is known about the impact of the rate of current change on working memory.In this study,we aimed to investigate the effects of two types of tACS with different rates of current change on working memory performance and brain activity.We applied a randomized,single-blind design and divided 81 young participants who received triangular wave tACS,sinusoidal wave tACS,or sham stimulation into three groups.Participants performed n-back tasks,and electroencephalograms were recorded before,during,and after active or sham stimulation.Compared to the baseline,working memory performance(accuracy and response time)improved after stimulation under all stimulation conditions.According to drift-diffusion model analysis,triangular wave tACS significantly increased the efficiency of non-target information processing.In addition,compared with sham conditions,triangular wave tACS reduced alpha power oscillations in the occipital lobe throughout the encoding period,while sinusoidal wave tACS increased theta power in the central frontal region only during the later encoding period.The brain network connectivity results showed that triangular wave tACS improved the clustering coefficient,local efficiency,and node degree intensity in the early encoding stage,and these parameters were positively correlated with the non-target drift rate and decision starting point.Our findings on how tACS modulates working memory indicate that triangular wave tACS significantly enhances brain network connectivity during the early encoding stage,demonstrating an improvement in the efficiency of working memory processing.In contrast,sinusoidal wave tACS increased the theta power during the later encoding stage,suggesting its potential critical role in late-stage information processing.These findings provide valuable insights into the potential mechanisms by which tACS modulates working memory.
基金supported by the China Scholarship Council(CSC)(No.202206290131)。
文摘This paper presents an analysis of an equilateral triangular array formation initialization for space-based gravitational wave observatory(GWO)near Lagrange points in the circular-restricted three-body problem.A stable configuration is essential for the continuous observation of gravitational waves(GWs).However,the motion near the collinear libration points is highly unstable.This problem is examined by output regulation theory.Using the tracking aspect,the equilateral triangular array formation is established in two periods and the fuel consumption is calculated.Furthermore,the natural evolution of the formation without control input is analyzed,and the effective stability duration is quantified to determine the timing of control interventions.Finally,to observe the GWs in same direction with different frequency bands,scale reconfiguration is employed.
文摘Thiswork explores aMagnetohydrodynamic(MHD)flowin a triangular cavitywith a thermally insulated baffle.Enclosure’s inclined wall is hotter,whereas the vertical border is adiabatic and the bottom is cooler.The study aims to clarify how geometric changes affect thermal performance and offers new perspectives on how to improve heat dissipation mechanisms.A COMSOL Multiphysics version 6.2 has been used to solve numerical solutions.Streamlines and thermal distributions are examined systematically in order to understand how the unique geometry and baffle size of triangular cavities can influence the fluid flow.This influence can result in optimized flow patterns,promoting efficient heat transfer by directing the fluid to specific areas that require more cooling.In comparison with conventional designs,this optimization results in more efficient convective heat transfer,which raises cooling efficiency and lowers thermal resistance.Furthermore,by strengthening heat transfer characteristics in heat transfer systems,these geometries increase thermal efficiency,which helps several sectors,including the production of electricity,HVAC,and the automobile industry.
文摘As an important index to measure the degree of entanglement in quantum systems,concurrence plays an important role in practical research.In this paper,we study the concurrence between two qubits in triangular triple quantum dot structure.Through calculation and simulation,it is found that concurrence is mainly affected by the interdot coupling strength t,Coulomb interactionU,temperature T,and electrode coupling G.Through comparative studies with parallel triple quantum dot structures,we demonstrate that the triangular geometry exhibits significantly enhanced concurrence under identical conditions.In addition,under the condition that concurrence exceeds 0.9,the functional relationship between t and U is obtained through simulation,which provides theoretical support for quantum dot regulation under high entanglement.Finally,we demonstrate the feasibility of implementing a three-qubit quantum gate,using the Toffoli gate as a representative example,under the condition that the triangular triple quantum dot system maintains high entanglement.
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Sponsored by the National Natural Science Foundation of China (6023201060572094)the National Natural Science Foundation of China for Distinguished Young Scholars (60625104)
文摘Feature extraction of symmetrical triangular linear frequency modulation continuous wave （LFM- CW） signal is studied. Combined with its peculiar charaeteristics, a novel algorithm based on Wigner-Hough transform （WHT） is presented for the deteetion and parameter estimation of this type of waveform. The initial frequency and chirp rate of each segment of this wave are estimated, and the peak-value searching steps in the parameter spaee is given. Compared with Wigner-Ville distribution （WVD）, Pseudo-Wigner-Ville distri- bution （PWD） and Smoothed-Peseudo-Wigner-Ville distribution （SPWD）, WHT has proven itself to be the best method for feature extraetion of symmetrical triangular LFMCW signal. In the end, Monte-Carlo simulations under different SNRs are earried out, with validating results on this method.
文摘Similarity measure is an essential tool to compare and determine the degree of similarity between intuitionistic fuzzy sets (IFSs). In this paper, a new similarity measure between intuitionistic fuzzy sets based on the mid points of transformed triangular fuzzy numbers is proposed. The proposed similarity measure provides reasonable results not only for the sets available in the literature but also gives very reasonable results, especially for fuzzy sets as well as for most intuitionistic fuzzy sets. To provide supportive evidence, the proposed similarity measure is tested on certain sets available in literature and is also applied to pattern recognition and medical diagnosis problems. It is observed that the proposed similarity measure provides a very intuitive quantification.
文摘In this paper we study the formal triangular matrix ring T =and give some necessary and sufficient conditions for T to be (strongly) separative, m-fold stable and unit 1-stable. Moreover, a condition for finitely generated projec-tive T-modules to have n in the stable range is given under the assumption that A and B are exchange rings.
基金The authors would like to acknowledge the financial supports of Beijing Natural Science Foundation(No.8182025).
文摘The open-source finite element software,OpenSees,is widely used in the earthquake engineering community.However,the shell elements and explicit algorithm in OpenSees still require further improvements.Therefore,in this work,a triangular shell element,NLDKGT,and an explicit algorithm are proposed and implemented in OpenSees.Specifically,based on the generalized conforming theory and the updated Lagrangian formulation,the proposed NLDKGT element is suitable for problems with complicated boundary conditions and strong nonlinearity.The accuracy and reliability of the NLDKGT element are validated through typical cases.Furthermore,by adopting the leapfrog integration method,an explicit algorithm in OpenSees and a modal damping model are developed.Finally,the stability and efficiency of the proposed shell element and explicit algorithm are validated through the nonlinear time-history analysis of a highrise building.
基金Foundation item： Supported by the Fund of Beijing Education Committee（KM200610005024） Supported by the National Natural Science Foundation of China（10671061）
文摘We consider the sufficient and necessary conditions for the formal triangular matrix ring being right minsymmetric, right DS, semicommutative, respectively.
基金Supported by the National Natural Science Foundation of China(Grant No.11671126)。
文摘In this paper we study Gorenstein(semiheredity)heredity,finite presentedness and F P-injectivity of modules over a formal triangular matrix ring.We provide necessary and sufficient conditions for such rings to be Gorenstein(semihereditary)hereditary and investigate when a triangular matrix ring is an n-FC ring.
基金Supported by the National Natural Science Foundation of China(61170138 and 61472349)
文摘We implemented accurate FFD in terms of triangular Bezier surfaces as matrix multiplications in CUDA and rendered them via OpenGL. Experimental results show that the proposed algorithm is more efficient than the previous GPU acceleration algorithm and tessel- lation shader algorithms.
文摘A new method as a post-processing step is presented to improve the shape quality of triangular meshes, which uses a topological clean up procedure and discrete smoothing interpolate (DSI) algorithm together. This method can improve the angle distribution of mesh element. while keeping the resulting meshes conform to the predefined constraints which are inputted as a PSLG.
基金Partially supported by the Fund (KM200610005024) of Beijing Education Committeethe NNSF (10671061) of China.
文摘In this paper the sufficient and necessary conditions are given for a formal triangular matrix ring to be right PP, generalized right PP, or semihereditary, respectively.
