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
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
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
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
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 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
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
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
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
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
In recent years,the solid oxide fuel cell(SOFC)scientific community has invested continuous efforts to employ artificial intelligence methods to design and develop new energy systems.It is crucial to gain a better und...In recent years,the solid oxide fuel cell(SOFC)scientific community has invested continuous efforts to employ artificial intelligence methods to design and develop new energy systems.It is crucial to gain a better understanding of the microscale phenomena that occur in the electrodes.In this review,we present a literature review of the field,discussing the limitations of including microstructural data in existing research and possible research directions to overcome them.This review focuses on a particular research area that uses artificial neural networks(ANNs)to predict the performance of SOFCs.Herein,we show that neural networks are used not only to conform to the newest trends but also for improving the design and providing a better understanding of microscale phenomena that occur in the electrodes.The review concludes by highlighting topological data analysis as a promising area of research that can incorporate detailed microstructure characterization in ANNs for performance prediction.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
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
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
To satisfy the requirements of accurate operationalrisk assessment of integrated transmission and distribution networks (I-T&D), an integrated operational risk assessment (IORA) algorithm is proposed. Specific cas...To satisfy the requirements of accurate operationalrisk assessment of integrated transmission and distribution networks (I-T&D), an integrated operational risk assessment (IORA) algorithm is proposed. Specific cases demonstrate thatan I-ORA is necessary because it provides accurate handlingof the coupling between transmission and distribution networks,accurate analysis of power supply mode (PSM) changes ofimportant users and helps to improve security and stability ofpower grid operations. Two key technical requirements in theI-ORA algorithm are realized, i.e., integrated topology analysisand integrated power flow calculation. Under a certain contingency, integrated topology analysis is used to assess the risksof substation power cuts, network split and PSM changes ofimportant users, while the integrated power flow calculation,based on the self-adaptive Levenburg-Marquard method andNewton method, can be implemented to assess risks of heavyload/overload and voltage deviation. In addition, the graphicsprocessing unit is used to parallelly process some computationintensive steps. Numerical experiments show that the proposedI-ORA algorithm can realize accurate assessment for the entireI-T&D. In addition, the efficiency and convergence are satisfying,indicating the proposed I-ORA algorithm can significantly benefitreal practice in the coordination operation of I-T&D in the future.展开更多
With integration of a larger amount of clean power sources and power electronic equipment,operation and dynamic characteristics of the power grid are becoming more and more complicated and stochastic.Therefore,it is n...With integration of a larger amount of clean power sources and power electronic equipment,operation and dynamic characteristics of the power grid are becoming more and more complicated and stochastic.Therefore,it is necessary and urgent to obtain accurate real-time states,which is difficult from traditional state estimation.This paper systematically develops a phasor measurement unit(PMU)based real-time state estimator for a realistic large-scale power grid for the first time.The estimator mainly relies on three refined algorithms,i.e.,an improved linear state estimation algorithm,a practical bad data identification method and a distributed topology check technique.Furthermore,a novel system architecture is designed and implemented for the China Southern Power Grid.Numerical simulations and extensive field operation results of the state estimator recorded under both normal and abnormal situations are presented.All the tests and field results demonstrate the advantages of the proposed algorithms in terms of online system monitoring and feasibility of refreshing the states of the whole system at intervals of tens of milliseconds.展开更多
Multi-agent technology has been applied extensively to many areas, including Decision Support Systems （DSS）. However, the applications of multi-agent technology in DSS are still very preliminary. Most of the current...Multi-agent technology has been applied extensively to many areas, including Decision Support Systems （DSS）. However, the applications of multi-agent technology in DSS are still very preliminary. Most of the current agent frameworks, such as middle-agent-based or agent-facilitator-based frameworks, are basically agent-to-agent model. These agent-based frameworks often neglect the living environment for agents and they suffer from： （i） inability to adapt to the environment, （ii） inability to self-upgrade, and （iii） inefficiency in information acquisition. Here, we introduce a recently proposed multi-agent framework, namely Agent-based Open Connectivity for Decision Support Systems （AOCD）. In this new framework, the communication and cooperation between agents are through a key component, the Matrix, which provides a virtual platform for agents. We use a unified Matrices framework to solve the bottleneck problem in the AOCD framework. Our experimental results based on different agent network topologies indicate that the hybrid topology presents superior performance compared with the centralised and decentralised topologies.展开更多
A numerical simulation method for parachute Fluid-Structure Interaction （FSI） problem using Semi-Implicit Method for Pres- sure-Linked Equations （SIMPLE） algorithm is proposed. This method could be used in both co...A numerical simulation method for parachute Fluid-Structure Interaction （FSI） problem using Semi-Implicit Method for Pres- sure-Linked Equations （SIMPLE） algorithm is proposed. This method could be used in both coupling computation of para- chute FSI and flow field analysis. Both fiat circular parachute and conical parachute are modeled and simulated by this new method. Flow field characteristics at various angles of attack are further simulated for the conical parachute model. Compari- son with the space-time FSI technique shows that this method also provides similar and reasonable results.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
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.
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.
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 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.
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.
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.
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In recent years,the solid oxide fuel cell(SOFC)scientific community has invested continuous efforts to employ artificial intelligence methods to design and develop new energy systems.It is crucial to gain a better understanding of the microscale phenomena that occur in the electrodes.In this review,we present a literature review of the field,discussing the limitations of including microstructural data in existing research and possible research directions to overcome them.This review focuses on a particular research area that uses artificial neural networks(ANNs)to predict the performance of SOFCs.Herein,we show that neural networks are used not only to conform to the newest trends but also for improving the design and providing a better understanding of microscale phenomena that occur in the electrodes.The review concludes by highlighting topological data analysis as a promising area of research that can incorporate detailed microstructure characterization in ANNs for performance prediction.
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.
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the State Grid Zhejiang Electric Power Co.,Ltd.(Science and Technology Project under Grant 5211JH180081:Research on security evaluation and control technology of smart platform based on dispatch cloud.)。
文摘To satisfy the requirements of accurate operationalrisk assessment of integrated transmission and distribution networks (I-T&D), an integrated operational risk assessment (IORA) algorithm is proposed. Specific cases demonstrate thatan I-ORA is necessary because it provides accurate handlingof the coupling between transmission and distribution networks,accurate analysis of power supply mode (PSM) changes ofimportant users and helps to improve security and stability ofpower grid operations. Two key technical requirements in theI-ORA algorithm are realized, i.e., integrated topology analysisand integrated power flow calculation. Under a certain contingency, integrated topology analysis is used to assess the risksof substation power cuts, network split and PSM changes ofimportant users, while the integrated power flow calculation,based on the self-adaptive Levenburg-Marquard method andNewton method, can be implemented to assess risks of heavyload/overload and voltage deviation. In addition, the graphicsprocessing unit is used to parallelly process some computationintensive steps. Numerical experiments show that the proposedI-ORA algorithm can realize accurate assessment for the entireI-T&D. In addition, the efficiency and convergence are satisfying,indicating the proposed I-ORA algorithm can significantly benefitreal practice in the coordination operation of I-T&D in the future.
基金supported by the National Natural Science Foundation of China(U1766214,U2066601).
文摘With integration of a larger amount of clean power sources and power electronic equipment,operation and dynamic characteristics of the power grid are becoming more and more complicated and stochastic.Therefore,it is necessary and urgent to obtain accurate real-time states,which is difficult from traditional state estimation.This paper systematically develops a phasor measurement unit(PMU)based real-time state estimator for a realistic large-scale power grid for the first time.The estimator mainly relies on three refined algorithms,i.e.,an improved linear state estimation algorithm,a practical bad data identification method and a distributed topology check technique.Furthermore,a novel system architecture is designed and implemented for the China Southern Power Grid.Numerical simulations and extensive field operation results of the state estimator recorded under both normal and abnormal situations are presented.All the tests and field results demonstrate the advantages of the proposed algorithms in terms of online system monitoring and feasibility of refreshing the states of the whole system at intervals of tens of milliseconds.
文摘Multi-agent technology has been applied extensively to many areas, including Decision Support Systems （DSS）. However, the applications of multi-agent technology in DSS are still very preliminary. Most of the current agent frameworks, such as middle-agent-based or agent-facilitator-based frameworks, are basically agent-to-agent model. These agent-based frameworks often neglect the living environment for agents and they suffer from： （i） inability to adapt to the environment, （ii） inability to self-upgrade, and （iii） inefficiency in information acquisition. Here, we introduce a recently proposed multi-agent framework, namely Agent-based Open Connectivity for Decision Support Systems （AOCD）. In this new framework, the communication and cooperation between agents are through a key component, the Matrix, which provides a virtual platform for agents. We use a unified Matrices framework to solve the bottleneck problem in the AOCD framework. Our experimental results based on different agent network topologies indicate that the hybrid topology presents superior performance compared with the centralised and decentralised topologies.
基金supported by the National Natural Science Foundation of China (Grant No. 10577003)Monash University of Australia
文摘A numerical simulation method for parachute Fluid-Structure Interaction （FSI） problem using Semi-Implicit Method for Pres- sure-Linked Equations （SIMPLE） algorithm is proposed. This method could be used in both coupling computation of para- chute FSI and flow field analysis. Both fiat circular parachute and conical parachute are modeled and simulated by this new method. Flow field characteristics at various angles of attack are further simulated for the conical parachute model. Compari- son with the space-time FSI technique shows that this method also provides similar and reasonable results.
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.
