Building prototyping has regularly been used in building performance analyses with statistically feasible models.The novelty of this research involves a new hybrid approach combining stratified sampling and k-means cl...Building prototyping has regularly been used in building performance analyses with statistically feasible models.The novelty of this research involves a new hybrid approach combining stratified sampling and k-means clustering to establish building geometry prototypes.The research focuses on residential buildings in Ningbo,China.Seventeen small residential districts(SRDs)containing 367 residential buildings were systemically selected for survey and data collection.The stratified sampling used building construction year as the main parameter to generate stratification.Floor numbers,shape coefficients,floor areas,and window-to-wall ratios were used as the four observations for k-means clustering.Based on this new approach,nine building geometry prototypes were identified and modelled.These statistically representative prototypes provide building geometrical information and characteristic-based evaluations for subsequent building performance analysis.展开更多
We provide a way to precisely control the geometry of a SiNx nanopore by adjusting the applied electric pulse. The pore is generated by applying the current pulse across a SiNx membrane, which is immersed in potassium...We provide a way to precisely control the geometry of a SiNx nanopore by adjusting the applied electric pulse. The pore is generated by applying the current pulse across a SiNx membrane, which is immersed in potassium chloride solution. We can generate single conical and cylindrical pores with different electric pulses. A theoretical model based on the Poisson and Nernst-Planck equations is employed to simulate the ion transport properties in the channel. In turn, we can analyze pore geometries by fitting the experimental current-voltage (I-V) curves. for the conical pores with a pore size of 0.5-2nm in diameter, the slope angles are around -2.5% to -10%. Moreover, the pore orifice can be enlarged slightly by additional repeating pulses. The conic pore lumen becomes close to a cylindrical channel, resulting in a symmetry I-V transport under positive and negative biases. A qualitative understanding of these effects will help us to prepare useful solid-nanopores as demanded.展开更多
An overview of the mathematical structure of the three-dimensional(3D) Ising model is given from the points of view of topology,algebra,and geometry.By analyzing the relationships among transfer matrices of the 3D I...An overview of the mathematical structure of the three-dimensional(3D) Ising model is given from the points of view of topology,algebra,and geometry.By analyzing the relationships among transfer matrices of the 3D Ising model,Reidemeister moves in the knot theory,Yang-Baxter and tetrahedron equations,the following facts are illustrated for the 3D Ising model.1) The complex quaternion basis constructed for the 3D Ising model naturally represents the rotation in a(3+1)-dimensional space-time as a relativistic quantum statistical mechanics model,which is consistent with the 4-fold integrand of the partition function obtained by taking the time average.2) A unitary transformation with a matrix that is a spin representation in 2 n·l·o-space corresponds to a rotation in 2n·l·o-space,which serves to smooth all the crossings in the transfer matrices and contributes the non-trivial topological part of the partition function of the 3D Ising model.3) A tetrahedron relationship would ensure the commutativity of the transfer matrices and the integrability of the 3D Ising model,and its existence is guaranteed by the Jordan algebra and the Jordan-von Neumann-Wigner procedures.4) The unitary transformation for smoothing the crossings in the transfer matrices changes the wave functions by complex phases φx,φy,and φz.The relationship with quantum field and gauge theories and the physical significance of the weight factors are discussed in detail.The conjectured exact solution is compared with numerical results,and the singularities at/near infinite temperature are inspected.The analyticity in β=1/(kBT) of both the hard-core and the Ising models has been proved only for β〉0,not for β=0.Thus the high-temperature series cannot serve as a standard for judging a putative exact solution of the 3D Ising model.展开更多
Using the underwater acoustic channel(UWA)for information dissemination requires a high data rate.However,some phenomena like refraction,reflection,phase shift,and high attenuation are undesirably apparent when the su...Using the underwater acoustic channel(UWA)for information dissemination requires a high data rate.However,some phenomena like refraction,reflection,phase shift,and high attenuation are undesirably apparent when the subject of using UWA is raised.Accordingly,sound communication would be a highly challenging task to be accomplished.Therefore,proposing a model of acoustic underwater communication channels is critical because of the multipath interference originating from the surface and bottom of the ocean.In this contribution,a straightforward geometry channel model for vertical and horizontal marine communications is presented.To do so,transmission loss and channel impulse response are analyzed as a function of transmitter and receiver distance,water depth,and reflection rate.The results of the model proposed in this paper are in very good agreement with those available in the literature.Initial findings indicate that the delay spread of horizontal communication with a 1000 m range reaches79 ms and 0.3 s for 30 m vertical communication.展开更多
The mathematical formulas are given for calculating the partial molar thermodynamic proper- ties in a ternary system from its three corresponding binary systems based on the new ternary symmetric model presented by th...The mathematical formulas are given for calculating the partial molar thermodynamic proper- ties in a ternary system from its three corresponding binary systems based on the new ternary symmetric model presented by the authors in the foregoing paper.Applying this model to NaCl-BaCl_2-SrCl_2 system,the phase diagram of which as well as some isothermal sections have been calculated.The devations of temperature between the calculated and experimen- tal diagrams are less than five degrees.展开更多
Network densification is a promising solution to fulfill network capacity requirement and transmission rate for beyond 5G and 6G wireless communications.Ultra-dense network(UDN)integrates heterogeneous network resourc...Network densification is a promising solution to fulfill network capacity requirement and transmission rate for beyond 5G and 6G wireless communications.Ultra-dense network(UDN)integrates heterogeneous network resources and coordinates technologies on quality of service controlling,to provide users with flexible service.However,dense deployment reduces coverage radius of the cell,resulting in an increase on handover frequency,which makes a serious impact on service continuity.In this paper,we propose a proactive selection method for dynamic access points grouping(DAPGing)in accordance with“user-centric”philosophy,which selects target Access Points(AP)and reduces handover times to ensure communication continuity.This method includes two criteria:1)the user’s sojourn time,which is determined by analyzing the AP coverage area;2)neighbor relationship between APs,which is determined by coverage area and signal strength characteristics between neighboring APs.Therefore,candidate APs become the proactive selected ones to update the AP group.Stochastic geometry is used to build system model and performance metrics are analyzed,including AP group coverage probability and average update frequency.Experimental analysis shows that the proposed proactive selection method brings similar coverage probability to traditional handover method,while average update frequency is reduced more than 20%selection criteria.展开更多
A practical approach for calculating the RCS (Radar Cross Section) of complex targets modeled with wire-grid-frame is presented. A way for generating a polyhedron model (facet-wedge model) with the wire-grid-frame dat...A practical approach for calculating the RCS (Radar Cross Section) of complex targets modeled with wire-grid-frame is presented. A way for generating a polyhedron model (facet-wedge model) with the wire-grid-frame data is described. For storing and reading the data of the polyhedron model in an easy way, a data structure is given.展开更多
This work introduces a scalable and efficient topological structure for tetrahedral and hexahedral meshes. The design of the data structure aims at maximal flexibility and high performance. It provides a high scalabil...This work introduces a scalable and efficient topological structure for tetrahedral and hexahedral meshes. The design of the data structure aims at maximal flexibility and high performance. It provides a high scalability by using hierarchical representa-tions of topological elements. The proposed data structure is array-based, and it is a compact representation of the half-edge data structure for volume elements and half-face data structure for volumetric meshes. This guarantees constant access time to the neighbors of the topological elements. In addition, an open-source implementation named Open Volumetric Mesh (OVM) of the pro-posed data structure is written in C++ using generic programming concepts.展开更多
Precise control of a magnetically suspended double-gimbal control moment gyroscope (MSDGCMG) is of vital importance and challenge to the attitude positioning of spacecraft owing to its multivariable, nonlinear and s...Precise control of a magnetically suspended double-gimbal control moment gyroscope (MSDGCMG) is of vital importance and challenge to the attitude positioning of spacecraft owing to its multivariable, nonlinear and strong coupled properties. This paper proposes a novel linearization and decoupling method based on differential geometry theory and combines it with the internal model controller (IMC) to guarantee the system robustness to the external disturbance and parameter uncertainty. Furthermore, by introducing the dynamic compensation for the inner-gimbal rate-servo system and the magnetically suspended rotor (MSR) system only, we can eliminate the influence of the unmodeled dynamics to the decoupling control accuracy as well as save costs and inhibit noises effectively. The simulation results verify the nice decoupling and robustness performance of the system using the proposed method.展开更多
The chiral geometry of multiple chiral doublet bands with identical configuration is discussed for different triaxial deformation parameters γ in the particle rotor model with πh11/2×γh11/2^-1.The energy spect...The chiral geometry of multiple chiral doublet bands with identical configuration is discussed for different triaxial deformation parameters γ in the particle rotor model with πh11/2×γh11/2^-1.The energy spectra,electromagnetic transition probabilities B(M1) and B(E2),angular momenta,and K-distributions are studied.It is demonstrated that the chirality still remains not only in the yrast and yrare bands,but also in the two higher excited bands whenγ deviates from 30°.The chiral geometry relies significantly on γ,and the chiral geometry of the two higher excited partner bands is not as good as that of the yrast and yrare doublet bands.展开更多
Our new method makes use of a CAD-based automatic modeling tool, MCAM, for geometry modeling and ray tracing of particle transport in method of characteristics (MOC). It was found that it could considerably enhance ...Our new method makes use of a CAD-based automatic modeling tool, MCAM, for geometry modeling and ray tracing of particle transport in method of characteristics (MOC). It was found that it could considerably enhance the capability of MOC to deal with more complicated models for neutron transport calculation. In our study, the diamond-difference scheme was applied to MOC to reduce the spatial discretization errors of the fiat flux approximation. Based on MCAM and MOC, a new 2D MOC code was developed and integrated into the SuperMC system, which is a Super Multi-function Computational system for neutronics and radiation simulation. The numerical results demonstrated the feasibility and effectiveness of the new method for neutron transport calculation in MOC.展开更多
基金sponsored by the Ningbo Natural Science Funding Scheme(Project code:2019A610393)The Zhejiang Provincial Department of Science and Technology is acknowledged for this research under its Provincial Key Laboratory Programme(2020E10018).
文摘Building prototyping has regularly been used in building performance analyses with statistically feasible models.The novelty of this research involves a new hybrid approach combining stratified sampling and k-means clustering to establish building geometry prototypes.The research focuses on residential buildings in Ningbo,China.Seventeen small residential districts(SRDs)containing 367 residential buildings were systemically selected for survey and data collection.The stratified sampling used building construction year as the main parameter to generate stratification.Floor numbers,shape coefficients,floor areas,and window-to-wall ratios were used as the four observations for k-means clustering.Based on this new approach,nine building geometry prototypes were identified and modelled.These statistically representative prototypes provide building geometrical information and characteristic-based evaluations for subsequent building performance analysis.
基金Supported by the National Natural Science Foundation of China under Grant Nos 61471336,51503207 and 61504146the Joint-Scholar of West Light Foundation of Chinese Academy of Sciences
文摘We provide a way to precisely control the geometry of a SiNx nanopore by adjusting the applied electric pulse. The pore is generated by applying the current pulse across a SiNx membrane, which is immersed in potassium chloride solution. We can generate single conical and cylindrical pores with different electric pulses. A theoretical model based on the Poisson and Nernst-Planck equations is employed to simulate the ion transport properties in the channel. In turn, we can analyze pore geometries by fitting the experimental current-voltage (I-V) curves. for the conical pores with a pore size of 0.5-2nm in diameter, the slope angles are around -2.5% to -10%. Moreover, the pore orifice can be enlarged slightly by additional repeating pulses. The conic pore lumen becomes close to a cylindrical channel, resulting in a symmetry I-V transport under positive and negative biases. A qualitative understanding of these effects will help us to prepare useful solid-nanopores as demanded.
基金Project supported by the National Natural Science Foundation of China (Grant No. 50831006)
文摘An overview of the mathematical structure of the three-dimensional(3D) Ising model is given from the points of view of topology,algebra,and geometry.By analyzing the relationships among transfer matrices of the 3D Ising model,Reidemeister moves in the knot theory,Yang-Baxter and tetrahedron equations,the following facts are illustrated for the 3D Ising model.1) The complex quaternion basis constructed for the 3D Ising model naturally represents the rotation in a(3+1)-dimensional space-time as a relativistic quantum statistical mechanics model,which is consistent with the 4-fold integrand of the partition function obtained by taking the time average.2) A unitary transformation with a matrix that is a spin representation in 2 n·l·o-space corresponds to a rotation in 2n·l·o-space,which serves to smooth all the crossings in the transfer matrices and contributes the non-trivial topological part of the partition function of the 3D Ising model.3) A tetrahedron relationship would ensure the commutativity of the transfer matrices and the integrability of the 3D Ising model,and its existence is guaranteed by the Jordan algebra and the Jordan-von Neumann-Wigner procedures.4) The unitary transformation for smoothing the crossings in the transfer matrices changes the wave functions by complex phases φx,φy,and φz.The relationship with quantum field and gauge theories and the physical significance of the weight factors are discussed in detail.The conjectured exact solution is compared with numerical results,and the singularities at/near infinite temperature are inspected.The analyticity in β=1/(kBT) of both the hard-core and the Ising models has been proved only for β〉0,not for β=0.Thus the high-temperature series cannot serve as a standard for judging a putative exact solution of the 3D Ising model.
文摘Using the underwater acoustic channel(UWA)for information dissemination requires a high data rate.However,some phenomena like refraction,reflection,phase shift,and high attenuation are undesirably apparent when the subject of using UWA is raised.Accordingly,sound communication would be a highly challenging task to be accomplished.Therefore,proposing a model of acoustic underwater communication channels is critical because of the multipath interference originating from the surface and bottom of the ocean.In this contribution,a straightforward geometry channel model for vertical and horizontal marine communications is presented.To do so,transmission loss and channel impulse response are analyzed as a function of transmitter and receiver distance,water depth,and reflection rate.The results of the model proposed in this paper are in very good agreement with those available in the literature.Initial findings indicate that the delay spread of horizontal communication with a 1000 m range reaches79 ms and 0.3 s for 30 m vertical communication.
文摘The mathematical formulas are given for calculating the partial molar thermodynamic proper- ties in a ternary system from its three corresponding binary systems based on the new ternary symmetric model presented by the authors in the foregoing paper.Applying this model to NaCl-BaCl_2-SrCl_2 system,the phase diagram of which as well as some isothermal sections have been calculated.The devations of temperature between the calculated and experimen- tal diagrams are less than five degrees.
基金This work was supported by the National Natural Science Foundation of China(NSFC)under Grant 61931005.
文摘Network densification is a promising solution to fulfill network capacity requirement and transmission rate for beyond 5G and 6G wireless communications.Ultra-dense network(UDN)integrates heterogeneous network resources and coordinates technologies on quality of service controlling,to provide users with flexible service.However,dense deployment reduces coverage radius of the cell,resulting in an increase on handover frequency,which makes a serious impact on service continuity.In this paper,we propose a proactive selection method for dynamic access points grouping(DAPGing)in accordance with“user-centric”philosophy,which selects target Access Points(AP)and reduces handover times to ensure communication continuity.This method includes two criteria:1)the user’s sojourn time,which is determined by analyzing the AP coverage area;2)neighbor relationship between APs,which is determined by coverage area and signal strength characteristics between neighboring APs.Therefore,candidate APs become the proactive selected ones to update the AP group.Stochastic geometry is used to build system model and performance metrics are analyzed,including AP group coverage probability and average update frequency.Experimental analysis shows that the proposed proactive selection method brings similar coverage probability to traditional handover method,while average update frequency is reduced more than 20%selection criteria.
文摘A practical approach for calculating the RCS (Radar Cross Section) of complex targets modeled with wire-grid-frame is presented. A way for generating a polyhedron model (facet-wedge model) with the wire-grid-frame data is described. For storing and reading the data of the polyhedron model in an easy way, a data structure is given.
基金Supported by Fundamental Research Funds for the Central Universities(Nos.2013ZM087,2012zz0062,2012zz0063)Doctoral Fund of Ministry of Education of China(No.20130172120010)
文摘This work introduces a scalable and efficient topological structure for tetrahedral and hexahedral meshes. The design of the data structure aims at maximal flexibility and high performance. It provides a high scalability by using hierarchical representa-tions of topological elements. The proposed data structure is array-based, and it is a compact representation of the half-edge data structure for volume elements and half-face data structure for volumetric meshes. This guarantees constant access time to the neighbors of the topological elements. In addition, an open-source implementation named Open Volumetric Mesh (OVM) of the pro-posed data structure is written in C++ using generic programming concepts.
文摘Precise control of a magnetically suspended double-gimbal control moment gyroscope (MSDGCMG) is of vital importance and challenge to the attitude positioning of spacecraft owing to its multivariable, nonlinear and strong coupled properties. This paper proposes a novel linearization and decoupling method based on differential geometry theory and combines it with the internal model controller (IMC) to guarantee the system robustness to the external disturbance and parameter uncertainty. Furthermore, by introducing the dynamic compensation for the inner-gimbal rate-servo system and the magnetically suspended rotor (MSR) system only, we can eliminate the influence of the unmodeled dynamics to the decoupling control accuracy as well as save costs and inhibit noises effectively. The simulation results verify the nice decoupling and robustness performance of the system using the proposed method.
基金Supported by Plan Project of Beijing College Students' Scientific Research and Entrepreneurial Action,Major State 973 Program of China(2013CB834400)National Natural Science Foundation of China(11175002,11335002,11375015,11461141002)+2 种基金National Fund for Fostering Talents of Basic Science(NFFTBS)(J1103206)Research Fund for Doctoral Program of Higher Education(20110001110087)China Postdoctoral Science Foundation(2015M580007)
文摘The chiral geometry of multiple chiral doublet bands with identical configuration is discussed for different triaxial deformation parameters γ in the particle rotor model with πh11/2×γh11/2^-1.The energy spectra,electromagnetic transition probabilities B(M1) and B(E2),angular momenta,and K-distributions are studied.It is demonstrated that the chirality still remains not only in the yrast and yrare bands,but also in the two higher excited bands whenγ deviates from 30°.The chiral geometry relies significantly on γ,and the chiral geometry of the two higher excited partner bands is not as good as that of the yrast and yrare doublet bands.
基金Supported by National Special Program for ITER(2011GB113006)Strategic Priority Research Program of Chinese Academy of Sciences(XDA03040000)National Natural Science Foundation of China(91026004)
文摘Our new method makes use of a CAD-based automatic modeling tool, MCAM, for geometry modeling and ray tracing of particle transport in method of characteristics (MOC). It was found that it could considerably enhance the capability of MOC to deal with more complicated models for neutron transport calculation. In our study, the diamond-difference scheme was applied to MOC to reduce the spatial discretization errors of the fiat flux approximation. Based on MCAM and MOC, a new 2D MOC code was developed and integrated into the SuperMC system, which is a Super Multi-function Computational system for neutronics and radiation simulation. The numerical results demonstrated the feasibility and effectiveness of the new method for neutron transport calculation in MOC.