Based on the working of Lighthill and Hunt et al., in the present paper the author has established the topological rules adapting to analysing the skin-friction lines and the section streamlines in cascades. These rul...Based on the working of Lighthill and Hunt et al., in the present paper the author has established the topological rules adapting to analysing the skin-friction lines and the section streamlines in cascades. These rules are (1) for a rotor cascade without shroud band, the total number of nodal points equals that the saddle points on the skin-friction line vector fields in eachpitch range; (2) for an annular or straight cascade with no-clearances at blade ends, the total number of saddle points is two more than that of nodal points on the skin-friction line fields in a pitch; (3) the total number of saddles in the secondary flow fields on cross-sections in cascade is one less than that of nodes; (4) in the section streamline vector fields on a meridian surface penetrating a flow passage, and on leading and trailing edge sections, the total number of nodes is equal to that of saddles; (5) on the streamline vector fields of a blade-to-blade surface, the total number of nodes is one less than that of saddles.展开更多
With an application of topological analysis,in this paper the skin-friction line patterns on compressor and turbine cascade surfaces are depicted and the streamline patterns of the secondary flow fields in the cross-s...With an application of topological analysis,in this paper the skin-friction line patterns on compressor and turbine cascade surfaces are depicted and the streamline patterns of the secondary flow fields in the cross-section of a curved pipe and a turbine cascade are drawn under given conditions.In addition the structures of vortices within three-dimensional viscous flow fields in cascades are analysed.展开更多
Semantic communication(SemCom)aims to achieve high-fidelity information delivery under low communication consumption by only guaranteeing semantic accuracy.Nevertheless,semantic communication still suffers from unexpe...Semantic communication(SemCom)aims to achieve high-fidelity information delivery under low communication consumption by only guaranteeing semantic accuracy.Nevertheless,semantic communication still suffers from unexpected channel volatility and thus developing a re-transmission mechanism(e.g.,hybrid automatic repeat request[HARQ])becomes indispensable.In that regard,instead of discarding previously transmitted information,the incremental knowledge-based HARQ(IK-HARQ)is deemed as a more effective mechanism that could sufficiently utilize the information semantics.However,considering the possible existence of semantic ambiguity in image transmission,a simple bit-level cyclic redundancy check(CRC)might compromise the performance of IK-HARQ.Therefore,there emerges a strong incentive to revolutionize the CRC mechanism,thus more effectively reaping the benefits of both SemCom and HARQ.In this paper,built on top of swin transformer-based joint source-channel coding(JSCC)and IK-HARQ,we propose a semantic image transmission framework SC-TDA-HARQ.In particular,different from the conventional CRC,we introduce a topological data analysis(TDA)-based error detection method,which capably digs out the inner topological and geometric information of images,to capture semantic information and determine the necessity for re-transmission.Extensive numerical results validate the effectiveness and efficiency of the proposed SC-TDA-HARQ framework,especially under the limited bandwidth condition,and manifest the superiority of TDA-based error detection method in image transmission.展开更多
The bandwidth of internet connections is still a bottleneck when transmitting large amounts of images,making the image quality assessment essential.Neurophysiological assessment of image quality has highlight advantag...The bandwidth of internet connections is still a bottleneck when transmitting large amounts of images,making the image quality assessment essential.Neurophysiological assessment of image quality has highlight advantages for it does not interfere with natural viewing behavior.However,in JPEG compression,the previous study is hard to tell the difference between the electroencephalogram(EEG)evoked by different quality images.In this paper,we propose an EEG analysis approach based on algebraic topology analysis,and the result shows that the difference between Euler characteristics of EEG evoked by different distortion images is striking both in the alpha and beta band.Moreover,we further discuss the relationship between the images and the EEG signals,and the results implied that the algebraic topological properties of images are consistent with that of brain perception,which is possible to give birth to braininspired image compression based on algebraic topological features.In general,an algebraic topologybased approach was proposed in this paper to analyze the perceptual characteristics of image quality,which will be beneficial to provide a reliable score for data compression in the network and improve the network transmission capacity.展开更多
This study presents a method for classifying cow and horse leather using a small number of digital microscope images and topological data analysis.In this method,hair pore coordinates in the images are used as essenti...This study presents a method for classifying cow and horse leather using a small number of digital microscope images and topological data analysis.In this method,hair pore coordinates in the images are used as essential information for classification.First,the coordinates were semiautomatically extracted using conventional image processing methods and persistent homology(PH)computation.Binary images with white pixels corresponding to the coordinates were generated,and their PHs were computed using filtration based on the Manhattan distance.In addition to the pairwise distance between the two pores,zeroth-and first-order lifetimes were used as explanatory variables to construct the classifier.Among the three explanatory variables,the zeroth-order lifetime resulted in the highest classification accuracy(86%)for the test data.Furthermore,we constructed logistic regression(LR)and random forest(RF)models using the zeroth-order lifetime computed from all images and conducted model interpretation.In both LR and RF,information on a zeroth-order lifetime of less than 10 was used as an important explanatory variable.Additionally,the inverse analysis of birth-death pairs suggested that the zeroth-order lifetime contains topological information distinct from the conventional pairwise distance.Our proposed method is designed to be robust in datalimited situations because it only uses hair pore coordinates as explanatory variables and does not require other information,such as hair pore density or pore size.This study demonstrates that accurate classifiers can be obtained using topological features related to hair pore arrangement.展开更多
Rotating stall is a complex nonlinear dynamic phenomenon which is always characterized by catastrophe and hysteresis in high aerodynamic-loading compressor. Exploring the key contributing factors and characteristic ru...Rotating stall is a complex nonlinear dynamic phenomenon which is always characterized by catastrophe and hysteresis in high aerodynamic-loading compressor. Exploring the key contributing factors and characteristic rules of hysteresis is very important for compressor design and flow instability control. In this paper, a novel model method is proposed to analyze the hysteresis behaviors to extend the understanding of compressor rotating stall. The equilibrium states of compressor system under different conditions are first described based on Moore-Greitzer model. Then,through assessing the stability of the equilibrium points by Liapunov＇s theorem, the ratio of shutoff head to compressor characteristic semi-height is found to affect the stall hysteresis： the size of hysteresis loop will gradually decrease, even disappear with the increase of the ratio. Combing the effects of both the ratio and throttle coefficient, the hysteresis behaviors of compressor stall under multi-parameters can be found to be consistent with the topological properties of cusp catastrophic model by Thom＇s catastrophe theory. Finally, according to topological invariant rules, from the perspective of potential function, the equilibrium surface equation of compressor system is developed by standard cusp catastrophic model to describe the various hysteresis behaviors of compressor rotating stall along different control routes.展开更多
The geometries,electronic structure,IR spectrum and other properties of hydrogen interaction between 5-fluorouracil and glycine were studied at the B3LYP/6-31＋G＊ level.Single point energy calculations were executed ...The geometries,electronic structure,IR spectrum and other properties of hydrogen interaction between 5-fluorouracil and glycine were studied at the B3LYP/6-31＋G＊ level.Single point energy calculations were executed at the B3LYP/6-311＋＋G＊＊ and B3LYP/aug-cc-pvdz levels,and natural bond orbital （NBO） analysis was carried out at the B3LYP/6-31＋G＊ level.Finally,the hydrogen bonds were discussed via AIM electronic density topology analysis.展开更多
A combined shape and topology optimization algorithm based on isogeometric boundary element method for 3D acoustics is developed in this study.The key treatment involves using adjoint variable method in shape sensitiv...A combined shape and topology optimization algorithm based on isogeometric boundary element method for 3D acoustics is developed in this study.The key treatment involves using adjoint variable method in shape sensitivity analysis with respect to non-uniform rational basis splines control points,and in topology sensitivity analysis with respect to the artificial densities of sound absorption material.OpenMP tool in Fortran code is adopted to improve the efficiency of analysis.To consider the features and efficiencies of the two types of optimization methods,this study adopts a combined iteration scheme for the optimization process to investigate the simultaneous change of geometry shape and distribution of material to achieve better noise control.Numerical examples,such as sound barrier,simple tank,and BeTSSi submarine,are performed to validate the advantage of combined optimization in noise reduction,and to demonstrate the potential of the proposed method for engineering problems.展开更多
A method based on the metamorphic principle is proposed for the analysis of the configuration design of a space truss deployable mechanism. The configuration change and correspondent topological graphs and adjacency m...A method based on the metamorphic principle is proposed for the analysis of the configuration design of a space truss deployable mechanism. The configuration change and correspondent topological graphs and adjacency matrixes at different work-stage of the mechanism, which is helpful to completely understand the composition and change rules of the metamorphic mechanism, are analyzed to indicate the metamorphic relationship in one working cycle. Furthermore, the static distance matrix, dynamic distance matrix and stiffness matrix of the mechanism are derived to assess the ability of the designed configuration to reveal some of the topological characteristics like compactness, dynamic sensitivity and stiffness. Using this proposed method in a space truss deployable mechanism helps the designer to evaluate its performance at the conceptual stage of design and make a rapid, reasonable selection for configuration design, which provides means for processing its type of analysis by computer.展开更多
In order to explore the evolution process of the Weibo local network,this study first defines four factors influencing the evolution of the Weibo network.On this basis,the BA scale-free network model was enhanced by i...In order to explore the evolution process of the Weibo local network,this study first defines four factors influencing the evolution of the Weibo network.On this basis,the BA scale-free network model was enhanced by incorporating these four factors and accounting for directionality,resulting in a Weibo local network evolution model based on user attributes and behavioral similarity.The model's validity was validated by comparing simulation results with real data.The findings indicate that the Weibo local network exhibits both small-world characteristics and distinctive features.The results show that the Weibo local network exhibits both small-world characteristics and distinctive properties.The in-degree distribution follows a mixed pattern of exponential and power-law distributions,the degree-degree shows isomatching,and both the in-degree centrality and eigenvector centrality values are relatively low.This research contributes to our understanding of user behaviour in the Weibo network,and provides a structural basis for exploring the impact of Weibo network structure on information dissemination.展开更多
The reaction of CH2SH radical with fluorine atom was studied at the levels of B3LYP/6-311G（d,p） and MP2（Full）/6-311G（d,p）. The computational results show that the reaction has three channels and proceeds by the ...The reaction of CH2SH radical with fluorine atom was studied at the levels of B3LYP/6-311G（d,p） and MP2（Full）/6-311G（d,p）. The computational results show that the reaction has three channels and proceeds by the addition of fluorine atoms on carbon or sulfur sites of CH2SH, forming initial intermediates. The calculated results show that the channel, in which fluorine attaches to the carbon atom to form CH2S and HF, is the most likely reaction pathway. Topological analysis of electron density was carried out for the three channels. The change trends of the chemical bonds on the reaction paths were discussed. The energy transition states and the structure transition regions （states） of the three channels were found. The calculated results show that the structure transition regions are broad in unobvious exothermic reactions or unobvious endothermic reactions, and are narrow in obvious exothermic reactions or obvious endothermic reactions.展开更多
By means of ink trace visualization and topological allalysis, this paper investigates the topological structure of the flow pattern surrounding both endwalls and blade surfaces for a low aspect ratio linear rotor cas...By means of ink trace visualization and topological allalysis, this paper investigates the topological structure of the flow pattern surrounding both endwalls and blade surfaces for a low aspect ratio linear rotor cascade with tip cIearance. The structure of the flow pattern shows that most of the singular points and separation lines are located in the upper half span region of the tested cascade where the aerodynamic behaviors are deteriorated.展开更多
Two coordination compounds with a flexible ligand N,N？-diacetic acid imidazolium（HDAM）,{[Co（trans-DAM）（bipy）（H2O）2]（OH）·4H2O}n 1 and {[Cd（trans-DAM）（bipy）（H2O）]（NO3）？2H2O}n 2（bipy = 4,4＇-bip...Two coordination compounds with a flexible ligand N,N？-diacetic acid imidazolium（HDAM）,{[Co（trans-DAM）（bipy）（H2O）2]（OH）·4H2O}n 1 and {[Cd（trans-DAM）（bipy）（H2O）]（NO3）？2H2O}n 2（bipy = 4,4＇-bipyridine）,were prepared and characterized by single-crystal X-ray diffraction.Compound 1 crystallizes in monoclinic,space group P2/n with a = 7.589（6）,b = 11.444（2）,c = 12.894（3）（A°）,β = 90.99（3）°,V = 1119.8（4）（A°）^3,Z = 4,C8.5H14N2O5.5Co0.5,Mr = 261.68,Dc = 1.552 g/cm^3,F（000） = 546,μ = 0.832 mm^-1,the final R = 0.0657 and wR = 0.1958.Compound 2 crystallizes in the monoclinic C2 space group with a = 17.479（4）,b = 11.689（2）,c = 11.670（2）,β = 117.13（3）°,V = 2121.9（7）3,Z = 4,C17H21N5O10Cd,Mr = 567.79,Dc = 1.777 g/cm^3,F（000） = 1144,μ = 1.096 mm^-1,the final R = 0.0233 and wR = 0.0638.In 1,the Co（II） ions are linked by μ2-trans-DAM-and bipy ligands to build a 2D（4,4） rectangular grid layer,exhibiting a 4-connected sql net.As for 2,μ3-trans-DAM-and bipy bridge Cd（II） ions form a 2D double-layer,consisting of a couple of（4,4） grid layers,which can be viewed as a（3,4）-connected network.In both compounds,the 2D structures are stabilized by hydrogen bonding interactions to give 3D supramolecular frameworks.Additionally,FT-IR spectroscopy,UV-Visible spectroscopy,and the fluorescent properties are discussed.展开更多
The thermodynamic properties of dibenzofurans （DFs）, xanthones （XTs） and an-thraquinones （AQs） with one and two positions substituted with hydroxyls in the ideal gas state at 298.15 K and 1.013×10^5 pa were...The thermodynamic properties of dibenzofurans （DFs）, xanthones （XTs） and an-thraquinones （AQs） with one and two positions substituted with hydroxyls in the ideal gas state at 298.15 K and 1.013×10^5 pa were calculated at the B3LYP/6-311G^＊ level using Gaussian 03 program. The isodesmic reactions were designed to calculate the standard free energy of formation （△fG^θ）. Three types of hydrogen bonds exist in the three kinds of chemicals and their bond energies were ascertained as 7-15, 15-23 and 49-58 kJ·mo1^-1 respectively by comparing the △fG^θ values. Electronic density topology analysis was applied to validate the strength of bond.展开更多
In this study,a multisensor system consisting of 23 potentiometric sensors was applied for long-term online measurements in outlet flow of the water treatment plant.Within 1 month of continuous measurements,the data s...In this study,a multisensor system consisting of 23 potentiometric sensors was applied for long-term online measurements in outlet flow of the water treatment plant.Within 1 month of continuous measurements,the data set of more than 295,000 observations was acquired.The processing of this dataset with conventional chemometric tools was cumbersome and not very informative.Topological data analysis(TDA)was recently suggested in chemometric literature to deal with large spectroscopic datasets.In this research,we explore the opportunities of TDA with respect to multisensor data with only 23 variables.It is shown that TDA allows for convenient data visualization,studying the evolution of water quality during the measurements and tracking the periodical structure in the data related to the water quality depending on the time of the day and the day of the week.TDA appears to be a valuable tool for multisensor data exploration.展开更多
This study explores the interaction between spatial configuration,natural mobility,and visual accessibility in exhibition spaces,an area that remains underexplored.By integrating visibility graph analysis(VGA),intelli...This study explores the interaction between spatial configuration,natural mobility,and visual accessibility in exhibition spaces,an area that remains underexplored.By integrating visibility graph analysis(VGA),intelligent agent simulation(IAS),topological analysis,and field observation,the research examines functional layout and accessibility across four museums.Findings indicate that corridors and pathways,second only to exhibition halls,play a crucial role in spatial mobility.Composite layouts(e.g.,circular and L-shaped designs)exhibit superior mean depth and integration,yet connectivity and mean depth demonstrate a nonlinear relationship.Elongated or complex path turns increase cognitive load,complicating navigation,while open passageways promote smoother visitor distribution.Topological analysis effectively identifies optimal nodes,key locations,and path-turn efficiency under accessibility constraints.Visitor dwell time is shaped not only by exhibit content but also by spatial location,entry sequence,and visitor density.Results support the assumption that space syntax models align with realworld visitor flow patterns,yet predictive models fail to fully capture variations in mobility across different timeframes and behavioral contexts.These insights contribute to optimizing museum design for improved visitor experience and spatial efficiency.展开更多
In multicellular and even single-celled organisms,individual components are interconnected at multiscale levels to produce enormously complex biological networks that help these systems maintain homeostasis for develo...In multicellular and even single-celled organisms,individual components are interconnected at multiscale levels to produce enormously complex biological networks that help these systems maintain homeostasis for development and environmental adaptation.Systems biology studies initially adopted network analysis to explore how relationships between individual components give rise to complex biological processes.Network analysis has been applied to dissect the complex connectivity of mammalian brains across different scales in time and space in The Human Brain Project.In plant science,network analysis has similarly been applied to study the connectivity of plant components at the molecular,subcellular,cellular,organic,and organism levels.Analysis of these multiscale networks contributes to our understanding of how genotype determines phenotype.In this review,we summarized the theoretical framework of plant multiscale networks and introduced studies investigating plant networks by various experimental and computational modalities.We next discussed the currently available analytic methodologies and multi-level imaging techniques used to map multiscale networks in plants.Finally,we highlighted some of the technical challenges and key questions remaining to be addressed in this emerging field.展开更多
With the great advancement of experimental tools,a tremendous amount of biomolecular data has been generated and accumulated in various databases.The high dimensionality,structural complexity,the nonlinearity,and enta...With the great advancement of experimental tools,a tremendous amount of biomolecular data has been generated and accumulated in various databases.The high dimensionality,structural complexity,the nonlinearity,and entanglements of biomolecular data,ranging from DNA knots,RNA secondary structures,protein folding configurations,chromosomes,DNA origami,molecular assembly,to others at the macromolecular level,pose a severe challenge in their analysis and characterization.In the past few decades,mathematical concepts,models,algorithms,and tools from algebraic topology,combinatorial topology,computational topology,and topological data analysis,have demonstrated great power and begun to play an essential role in tackling the biomolecular data challenge.In this work,we introduce biomolecular topology,which concerns the topological problems and models originated from the biomolecular systems.More specifically,the biomolecular topology encompasses topological structures,properties and relations that are emerged from biomolecular structures,dynamics,interactions,and functions.We discuss the various types of biomolecular topology from structures(of proteins,DNAs,and RNAs),protein folding,and protein assembly.A brief discussion of databanks(and databases),theoretical models,and computational algorithms,is presented.Further,we systematically review related topological models,including graphs,simplicial complexes,persistent homology,persistent Laplacians,de Rham-Hodge theory,Yau-Hausdorff distance,and the topology-based machine learning models.展开更多
The continuum structural-acoustic topology optimization with external loading is investigated herein. Finite element method （FEM） is used to obtain the structural frequency response and boundary element method （BEM...The continuum structural-acoustic topology optimization with external loading is investigated herein. Finite element method （FEM） is used to obtain the structural frequency response and boundary element method （BEM） is adopted to perform exterior acoustic radiation analysis. The evolutionary structural optimization （ESO） is served as an optimization method in structural-acoustic radiation topology analysis. The acoustic radiation optimization of a plate under harmonic excitation is given for example. The numerical results show that using ESO solution to analyze structural-acoustic topology optimization is feasible and effective.展开更多
To identify time-space locations where public transit infrastructure fails to provide a reliable and timely alternative to private vehicles,this paper proposes a new travel demand-independent persistent homology-based...To identify time-space locations where public transit infrastructure fails to provide a reliable and timely alternative to private vehicles,this paper proposes a new travel demand-independent persistent homology-based method to locate and rank the severity of the modal travel desert.Persistent homology,which is a tool from algebraic topology,is incorporated and the severity of a transit desert ismeasured as a trade-off between its proximity to existing transit infrastructure and the travel time required to travel through it.The proposed method highlights entire regions of cities that are bereft of suitable public transit,providing reasonable estimates even in the absence of travel demand data.This paper presents the techniques and software tools used to study the Stockholm public transit network.The proposed method is potentially useful for city planners to consider the trade-off between how severe a bottleneck is and how difficult the bottleneck is to fix.展开更多
文摘Based on the working of Lighthill and Hunt et al., in the present paper the author has established the topological rules adapting to analysing the skin-friction lines and the section streamlines in cascades. These rules are (1) for a rotor cascade without shroud band, the total number of nodal points equals that the saddle points on the skin-friction line vector fields in eachpitch range; (2) for an annular or straight cascade with no-clearances at blade ends, the total number of saddle points is two more than that of nodal points on the skin-friction line fields in a pitch; (3) the total number of saddles in the secondary flow fields on cross-sections in cascade is one less than that of nodes; (4) in the section streamline vector fields on a meridian surface penetrating a flow passage, and on leading and trailing edge sections, the total number of nodes is equal to that of saddles; (5) on the streamline vector fields of a blade-to-blade surface, the total number of nodes is one less than that of saddles.
文摘With an application of topological analysis,in this paper the skin-friction line patterns on compressor and turbine cascade surfaces are depicted and the streamline patterns of the secondary flow fields in the cross-section of a curved pipe and a turbine cascade are drawn under given conditions.In addition the structures of vortices within three-dimensional viscous flow fields in cascades are analysed.
基金supported in part by the National Key Research and Development Program of China under Grant 2024YFE0200600in part by the National Natural Science Foundation of China under Grant 62071425+3 种基金in part by the Zhejiang Key Research and Development Plan under Grant 2022C01093in part by the Zhejiang Provincial Natural Science Foundation of China under Grant LR23F010005in part by the National Key Laboratory of Wireless Communications Foundation under Grant 2023KP01601in part by the Big Data and Intelligent Computing Key Lab of CQUPT under Grant BDIC-2023-B-001.
文摘Semantic communication(SemCom)aims to achieve high-fidelity information delivery under low communication consumption by only guaranteeing semantic accuracy.Nevertheless,semantic communication still suffers from unexpected channel volatility and thus developing a re-transmission mechanism(e.g.,hybrid automatic repeat request[HARQ])becomes indispensable.In that regard,instead of discarding previously transmitted information,the incremental knowledge-based HARQ(IK-HARQ)is deemed as a more effective mechanism that could sufficiently utilize the information semantics.However,considering the possible existence of semantic ambiguity in image transmission,a simple bit-level cyclic redundancy check(CRC)might compromise the performance of IK-HARQ.Therefore,there emerges a strong incentive to revolutionize the CRC mechanism,thus more effectively reaping the benefits of both SemCom and HARQ.In this paper,built on top of swin transformer-based joint source-channel coding(JSCC)and IK-HARQ,we propose a semantic image transmission framework SC-TDA-HARQ.In particular,different from the conventional CRC,we introduce a topological data analysis(TDA)-based error detection method,which capably digs out the inner topological and geometric information of images,to capture semantic information and determine the necessity for re-transmission.Extensive numerical results validate the effectiveness and efficiency of the proposed SC-TDA-HARQ framework,especially under the limited bandwidth condition,and manifest the superiority of TDA-based error detection method in image transmission.
基金supported by the Key Research and Development Program of Zhejiang Province(Grant No.2019C03138 and No.2019C01002)。
文摘The bandwidth of internet connections is still a bottleneck when transmitting large amounts of images,making the image quality assessment essential.Neurophysiological assessment of image quality has highlight advantages for it does not interfere with natural viewing behavior.However,in JPEG compression,the previous study is hard to tell the difference between the electroencephalogram(EEG)evoked by different quality images.In this paper,we propose an EEG analysis approach based on algebraic topology analysis,and the result shows that the difference between Euler characteristics of EEG evoked by different distortion images is striking both in the alpha and beta band.Moreover,we further discuss the relationship between the images and the EEG signals,and the results implied that the algebraic topological properties of images are consistent with that of brain perception,which is possible to give birth to braininspired image compression based on algebraic topological features.In general,an algebraic topologybased approach was proposed in this paper to analyze the perceptual characteristics of image quality,which will be beneficial to provide a reliable score for data compression in the network and improve the network transmission capacity.
文摘This study presents a method for classifying cow and horse leather using a small number of digital microscope images and topological data analysis.In this method,hair pore coordinates in the images are used as essential information for classification.First,the coordinates were semiautomatically extracted using conventional image processing methods and persistent homology(PH)computation.Binary images with white pixels corresponding to the coordinates were generated,and their PHs were computed using filtration based on the Manhattan distance.In addition to the pairwise distance between the two pores,zeroth-and first-order lifetimes were used as explanatory variables to construct the classifier.Among the three explanatory variables,the zeroth-order lifetime resulted in the highest classification accuracy(86%)for the test data.Furthermore,we constructed logistic regression(LR)and random forest(RF)models using the zeroth-order lifetime computed from all images and conducted model interpretation.In both LR and RF,information on a zeroth-order lifetime of less than 10 was used as an important explanatory variable.Additionally,the inverse analysis of birth-death pairs suggested that the zeroth-order lifetime contains topological information distinct from the conventional pairwise distance.Our proposed method is designed to be robust in datalimited situations because it only uses hair pore coordinates as explanatory variables and does not require other information,such as hair pore density or pore size.This study demonstrates that accurate classifiers can be obtained using topological features related to hair pore arrangement.
基金supported by the National Natural Science Foundation of China(Nos.51676006 and 51636001)the Aeronautics Power Foundation of China(No.6141B090315)China Postdoctoral Science Foundation(No.2017M610742)
文摘Rotating stall is a complex nonlinear dynamic phenomenon which is always characterized by catastrophe and hysteresis in high aerodynamic-loading compressor. Exploring the key contributing factors and characteristic rules of hysteresis is very important for compressor design and flow instability control. In this paper, a novel model method is proposed to analyze the hysteresis behaviors to extend the understanding of compressor rotating stall. The equilibrium states of compressor system under different conditions are first described based on Moore-Greitzer model. Then,through assessing the stability of the equilibrium points by Liapunov＇s theorem, the ratio of shutoff head to compressor characteristic semi-height is found to affect the stall hysteresis： the size of hysteresis loop will gradually decrease, even disappear with the increase of the ratio. Combing the effects of both the ratio and throttle coefficient, the hysteresis behaviors of compressor stall under multi-parameters can be found to be consistent with the topological properties of cusp catastrophic model by Thom＇s catastrophe theory. Finally, according to topological invariant rules, from the perspective of potential function, the equilibrium surface equation of compressor system is developed by standard cusp catastrophic model to describe the various hysteresis behaviors of compressor rotating stall along different control routes.
基金supported by the Foundation Study Fund of Tangshan Normal College (No.07C22)Education Committee Fund of Hebei Province (No.Z2007204,No.Z2007205)+1 种基金Application Foundation Study Fund of Tangshan City (No.06234501A-10)Science Study Fund of Tangshan Normal College (No.06D08)
文摘The geometries,electronic structure,IR spectrum and other properties of hydrogen interaction between 5-fluorouracil and glycine were studied at the B3LYP/6-31＋G＊ level.Single point energy calculations were executed at the B3LYP/6-311＋＋G＊＊ and B3LYP/aug-cc-pvdz levels,and natural bond orbital （NBO） analysis was carried out at the B3LYP/6-31＋G＊ level.Finally,the hydrogen bonds were discussed via AIM electronic density topology analysis.
基金This study was financially supported by the National Natural Science Foundation of China(NSFC)under Grant No.11772322the Strategic Priority Research Program of the Chinese Academy of Sciences under Grant No.XDB22040502.
文摘A combined shape and topology optimization algorithm based on isogeometric boundary element method for 3D acoustics is developed in this study.The key treatment involves using adjoint variable method in shape sensitivity analysis with respect to non-uniform rational basis splines control points,and in topology sensitivity analysis with respect to the artificial densities of sound absorption material.OpenMP tool in Fortran code is adopted to improve the efficiency of analysis.To consider the features and efficiencies of the two types of optimization methods,this study adopts a combined iteration scheme for the optimization process to investigate the simultaneous change of geometry shape and distribution of material to achieve better noise control.Numerical examples,such as sound barrier,simple tank,and BeTSSi submarine,are performed to validate the advantage of combined optimization in noise reduction,and to demonstrate the potential of the proposed method for engineering problems.
基金supported by the Science and Technology Commission of Shanghai Municipality under Grant No. 06dz22105
文摘A method based on the metamorphic principle is proposed for the analysis of the configuration design of a space truss deployable mechanism. The configuration change and correspondent topological graphs and adjacency matrixes at different work-stage of the mechanism, which is helpful to completely understand the composition and change rules of the metamorphic mechanism, are analyzed to indicate the metamorphic relationship in one working cycle. Furthermore, the static distance matrix, dynamic distance matrix and stiffness matrix of the mechanism are derived to assess the ability of the designed configuration to reveal some of the topological characteristics like compactness, dynamic sensitivity and stiffness. Using this proposed method in a space truss deployable mechanism helps the designer to evaluate its performance at the conceptual stage of design and make a rapid, reasonable selection for configuration design, which provides means for processing its type of analysis by computer.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.62266030 and 61863025)。
文摘In order to explore the evolution process of the Weibo local network,this study first defines four factors influencing the evolution of the Weibo network.On this basis,the BA scale-free network model was enhanced by incorporating these four factors and accounting for directionality,resulting in a Weibo local network evolution model based on user attributes and behavioral similarity.The model's validity was validated by comparing simulation results with real data.The findings indicate that the Weibo local network exhibits both small-world characteristics and distinctive features.The results show that the Weibo local network exhibits both small-world characteristics and distinctive properties.The in-degree distribution follows a mixed pattern of exponential and power-law distributions,the degree-degree shows isomatching,and both the in-degree centrality and eigenvector centrality values are relatively low.This research contributes to our understanding of user behaviour in the Weibo network,and provides a structural basis for exploring the impact of Weibo network structure on information dissemination.
基金This work was supported by the National Natural Science Foundation of China （No.20573032）,the Natural Science Foundation of Hebei Province （No.B2006000137）, the Education Department Foundation of Hebei Province （No.2007123）, and the Doctoral Foundation of Hebei Normal University （No.L2005B12）.
文摘The reaction of CH2SH radical with fluorine atom was studied at the levels of B3LYP/6-311G（d,p） and MP2（Full）/6-311G（d,p）. The computational results show that the reaction has three channels and proceeds by the addition of fluorine atoms on carbon or sulfur sites of CH2SH, forming initial intermediates. The calculated results show that the channel, in which fluorine attaches to the carbon atom to form CH2S and HF, is the most likely reaction pathway. Topological analysis of electron density was carried out for the three channels. The change trends of the chemical bonds on the reaction paths were discussed. The energy transition states and the structure transition regions （states） of the three channels were found. The calculated results show that the structure transition regions are broad in unobvious exothermic reactions or unobvious endothermic reactions, and are narrow in obvious exothermic reactions or obvious endothermic reactions.
文摘By means of ink trace visualization and topological allalysis, this paper investigates the topological structure of the flow pattern surrounding both endwalls and blade surfaces for a low aspect ratio linear rotor cascade with tip cIearance. The structure of the flow pattern shows that most of the singular points and separation lines are located in the upper half span region of the tested cascade where the aerodynamic behaviors are deteriorated.
基金supported by the National Natural Science Foundation of China (No. 20873021)
文摘Two coordination compounds with a flexible ligand N,N？-diacetic acid imidazolium（HDAM）,{[Co（trans-DAM）（bipy）（H2O）2]（OH）·4H2O}n 1 and {[Cd（trans-DAM）（bipy）（H2O）]（NO3）？2H2O}n 2（bipy = 4,4＇-bipyridine）,were prepared and characterized by single-crystal X-ray diffraction.Compound 1 crystallizes in monoclinic,space group P2/n with a = 7.589（6）,b = 11.444（2）,c = 12.894（3）（A°）,β = 90.99（3）°,V = 1119.8（4）（A°）^3,Z = 4,C8.5H14N2O5.5Co0.5,Mr = 261.68,Dc = 1.552 g/cm^3,F（000） = 546,μ = 0.832 mm^-1,the final R = 0.0657 and wR = 0.1958.Compound 2 crystallizes in the monoclinic C2 space group with a = 17.479（4）,b = 11.689（2）,c = 11.670（2）,β = 117.13（3）°,V = 2121.9（7）3,Z = 4,C17H21N5O10Cd,Mr = 567.79,Dc = 1.777 g/cm^3,F（000） = 1144,μ = 1.096 mm^-1,the final R = 0.0233 and wR = 0.0638.In 1,the Co（II） ions are linked by μ2-trans-DAM-and bipy ligands to build a 2D（4,4） rectangular grid layer,exhibiting a 4-connected sql net.As for 2,μ3-trans-DAM-and bipy bridge Cd（II） ions form a 2D double-layer,consisting of a couple of（4,4） grid layers,which can be viewed as a（3,4）-connected network.In both compounds,the 2D structures are stabilized by hydrogen bonding interactions to give 3D supramolecular frameworks.Additionally,FT-IR spectroscopy,UV-Visible spectroscopy,and the fluorescent properties are discussed.
文摘The thermodynamic properties of dibenzofurans （DFs）, xanthones （XTs） and an-thraquinones （AQs） with one and two positions substituted with hydroxyls in the ideal gas state at 298.15 K and 1.013×10^5 pa were calculated at the B3LYP/6-311G^＊ level using Gaussian 03 program. The isodesmic reactions were designed to calculate the standard free energy of formation （△fG^θ）. Three types of hydrogen bonds exist in the three kinds of chemicals and their bond energies were ascertained as 7-15, 15-23 and 49-58 kJ·mo1^-1 respectively by comparing the △fG^θ values. Electronic density topology analysis was applied to validate the strength of bond.
基金The authors are grateful to O.Lominoga and Zh.Lyadova from SUE“Vodokanal of St.Petersburg”for their valuable help in organizing the experiments.DK acknowledges financial support from RFBR project#17-33-50101.EL and AL acknowledge partial financial support from the Government of Russian Federation,Grant 08-08.VB thanks the Russian Ministry of Education and Science for support of this work within the framework of the basic part of the state task on the theme:“Adaptive technologies of analytical control based on optical sensors”(Project No.4.7001.2017/BP).
文摘In this study,a multisensor system consisting of 23 potentiometric sensors was applied for long-term online measurements in outlet flow of the water treatment plant.Within 1 month of continuous measurements,the data set of more than 295,000 observations was acquired.The processing of this dataset with conventional chemometric tools was cumbersome and not very informative.Topological data analysis(TDA)was recently suggested in chemometric literature to deal with large spectroscopic datasets.In this research,we explore the opportunities of TDA with respect to multisensor data with only 23 variables.It is shown that TDA allows for convenient data visualization,studying the evolution of water quality during the measurements and tracking the periodical structure in the data related to the water quality depending on the time of the day and the day of the week.TDA appears to be a valuable tool for multisensor data exploration.
基金funded by the 2024 Individual Academic Enhancement Project of the University Project Pool,entitled“Reproduction and Reconstruction of Historical and Cultural Spaces in the Theoretical Perspective of the Field of Memory(Grant No.24XSC14)”the R&D Program of Beijing Municipal Education Commission(Grant No.SZ202110009003).
文摘This study explores the interaction between spatial configuration,natural mobility,and visual accessibility in exhibition spaces,an area that remains underexplored.By integrating visibility graph analysis(VGA),intelligent agent simulation(IAS),topological analysis,and field observation,the research examines functional layout and accessibility across four museums.Findings indicate that corridors and pathways,second only to exhibition halls,play a crucial role in spatial mobility.Composite layouts(e.g.,circular and L-shaped designs)exhibit superior mean depth and integration,yet connectivity and mean depth demonstrate a nonlinear relationship.Elongated or complex path turns increase cognitive load,complicating navigation,while open passageways promote smoother visitor distribution.Topological analysis effectively identifies optimal nodes,key locations,and path-turn efficiency under accessibility constraints.Visitor dwell time is shaped not only by exhibit content but also by spatial location,entry sequence,and visitor density.Results support the assumption that space syntax models align with realworld visitor flow patterns,yet predictive models fail to fully capture variations in mobility across different timeframes and behavioral contexts.These insights contribute to optimizing museum design for improved visitor experience and spatial efficiency.
基金supported by the National Natural Science Foundation of China(31530084,32000558,32000483,and31800504)the Programme of Introducing Talents of Discipline to Universities(111 project,B13007)the China Postdoctoral Science Foundation Grant(2019M660494)。
文摘In multicellular and even single-celled organisms,individual components are interconnected at multiscale levels to produce enormously complex biological networks that help these systems maintain homeostasis for development and environmental adaptation.Systems biology studies initially adopted network analysis to explore how relationships between individual components give rise to complex biological processes.Network analysis has been applied to dissect the complex connectivity of mammalian brains across different scales in time and space in The Human Brain Project.In plant science,network analysis has similarly been applied to study the connectivity of plant components at the molecular,subcellular,cellular,organic,and organism levels.Analysis of these multiscale networks contributes to our understanding of how genotype determines phenotype.In this review,we summarized the theoretical framework of plant multiscale networks and introduced studies investigating plant networks by various experimental and computational modalities.We next discussed the currently available analytic methodologies and multi-level imaging techniques used to map multiscale networks in plants.Finally,we highlighted some of the technical challenges and key questions remaining to be addressed in this emerging field.
基金supported by Nanyang Technological University Startup Grant M4081842Singapore Ministry of Education Academic Research fund Tier 1 RG109/19,MOE-T2EP20120-0013 and MOE-T2EP20220-0010+10 种基金supported by NIH grant GM126189NSF grants DMS-2052983,DMS-1761320,and IIS-1900473supported by Natural Science Foundation of China(NSFC)grant(11971144)Highlevel Scientific Research Foundation of Hebei Provincethe Start-up Research Fund from Yanqi Lake Beijing Institute of Mathematical Sciences and Applicationssupported by Tianjin Natural Science Foundation(Grant No.19JCYBJC30200)supported by National Natural Science Foundation of China(NSFC)grant(12171275)Tsinghua University Spring Breeze Fund(2020Z99CFY044)Tsinghua University Start-up FundTsinghua University Education Foundation fund(042202008)National Center for Theoretical Sciences(NCTS)for providing an excellent research environment while part of this research was done。
文摘With the great advancement of experimental tools,a tremendous amount of biomolecular data has been generated and accumulated in various databases.The high dimensionality,structural complexity,the nonlinearity,and entanglements of biomolecular data,ranging from DNA knots,RNA secondary structures,protein folding configurations,chromosomes,DNA origami,molecular assembly,to others at the macromolecular level,pose a severe challenge in their analysis and characterization.In the past few decades,mathematical concepts,models,algorithms,and tools from algebraic topology,combinatorial topology,computational topology,and topological data analysis,have demonstrated great power and begun to play an essential role in tackling the biomolecular data challenge.In this work,we introduce biomolecular topology,which concerns the topological problems and models originated from the biomolecular systems.More specifically,the biomolecular topology encompasses topological structures,properties and relations that are emerged from biomolecular structures,dynamics,interactions,and functions.We discuss the various types of biomolecular topology from structures(of proteins,DNAs,and RNAs),protein folding,and protein assembly.A brief discussion of databanks(and databases),theoretical models,and computational algorithms,is presented.Further,we systematically review related topological models,including graphs,simplicial complexes,persistent homology,persistent Laplacians,de Rham-Hodge theory,Yau-Hausdorff distance,and the topology-based machine learning models.
文摘The continuum structural-acoustic topology optimization with external loading is investigated herein. Finite element method （FEM） is used to obtain the structural frequency response and boundary element method （BEM） is adopted to perform exterior acoustic radiation analysis. The evolutionary structural optimization （ESO） is served as an optimization method in structural-acoustic radiation topology analysis. The acoustic radiation optimization of a plate under harmonic excitation is given for example. The numerical results show that using ESO solution to analyze structural-acoustic topology optimization is feasible and effective.
文摘To identify time-space locations where public transit infrastructure fails to provide a reliable and timely alternative to private vehicles,this paper proposes a new travel demand-independent persistent homology-based method to locate and rank the severity of the modal travel desert.Persistent homology,which is a tool from algebraic topology,is incorporated and the severity of a transit desert ismeasured as a trade-off between its proximity to existing transit infrastructure and the travel time required to travel through it.The proposed method highlights entire regions of cities that are bereft of suitable public transit,providing reasonable estimates even in the absence of travel demand data.This paper presents the techniques and software tools used to study the Stockholm public transit network.The proposed method is potentially useful for city planners to consider the trade-off between how severe a bottleneck is and how difficult the bottleneck is to fix.
