Structure learning of Bayesian networks is a wellresearched but computationally hard task.For learning Bayesian networks,this paper proposes an improved algorithm based on unconstrained optimization and ant colony opt...Structure learning of Bayesian networks is a wellresearched but computationally hard task.For learning Bayesian networks,this paper proposes an improved algorithm based on unconstrained optimization and ant colony optimization（U-ACO-B） to solve the drawbacks of the ant colony optimization（ACO-B）.In this algorithm,firstly,an unconstrained optimization problem is solved to obtain an undirected skeleton,and then the ACO algorithm is used to orientate the edges,thus returning the final structure.In the experimental part of the paper,we compare the performance of the proposed algorithm with ACO-B algorithm.The experimental results show that our method is effective and greatly enhance convergence speed than ACO-B algorithm.展开更多
The learning Bayesian network （BN） structure from data is an NP-hard problem and still one of the most exciting chal- lenges in the machine learning. In this work, a novel algorithm is presented which combines ideas...The learning Bayesian network （BN） structure from data is an NP-hard problem and still one of the most exciting chal- lenges in the machine learning. In this work, a novel algorithm is presented which combines ideas from local learning, constraint- based, and search-and-score techniques in a principled and ef- fective way. It first reconstructs the junction tree of a BN and then performs a K2-scoring greedy search to orientate the local edges in the cliques of junction tree. Theoretical and experimental results show the proposed algorithm is capable of handling networks with a large number of variables. Its comparison with the well-known K2 algorithm is also presented.展开更多
Vector beams have attracted widespread attention because of their unique optical properties;in particular,their combination with tight focusing can produce many interesting phenomena.The rise of 3D printing technology...Vector beams have attracted widespread attention because of their unique optical properties;in particular,their combination with tight focusing can produce many interesting phenomena.The rise of 3D printing technology provides more possibilities for exploration.In this work,a cascading method involving a metamaterial and a metalens is used to generate a tightly focused field of vector beams in the terahertz band,which is prepared via 3D printing.As a proof-of-concept demonstration,a series of metamaterial modules capable of generating states of different orbital angular momentum are proposed by cascading with a metalens.The experimental results are in good agreement with the simulation results,fully verifying the feasibility of the scheme.The proposed design and fabrication strategy provides a new idea for the tight focusing of terahertz vector beams.展开更多
Voltage control of magnetism in multiferroics,where the ferromagnetism and ferroelectricity are simultaneously exhibiting,is of great importance to achieve compact,fast and energy efficient voltage controllable magnet...Voltage control of magnetism in multiferroics,where the ferromagnetism and ferroelectricity are simultaneously exhibiting,is of great importance to achieve compact,fast and energy efficient voltage controllable magnetic/microwave devices.Particularly,these devices are widely used in radar,aircraft,cell phones and satellites,where volume,response time and energy consumption is critical.Researchers realized electric field tuning of magnetic properties like magnetization,magnetic anisotropy and permeability in varied multiferroic heterostructures such as bulk,thin films and nanostructure by different magnetoelectric(ME)coupling mechanism:strain/stress,interfacial charge,spin–electromagnetic(EM)coupling and exchange coupling,etc.In this review,we focus on voltage control of ferromagnetic resonance(FMR)in multiferroics.ME coupling-induced FMR change is critical in microwave devices,where the electric field tuning of magnetic effective anisotropic field determines the tunability of the performance of microwave devices.Experimentally,FMR measurement technique is also an important method to determine the small effective magnetic field change in small amount of magnetic material precisely due to its high sensitivity and to reveal the deep science of multiferroics,especially,voltage control of magnetism in novel mechanisms like interfacial charge,spin–EM coupling and exchange coupling.展开更多
We report the preparation of epitaxial La_(0.7)Sr_(0.3)MnO_(3) thin films grown on(001)-oriented 0.72Pb(Mg_(1/3)Nb_(2/3))TO_(3)-0.28PbTiO_(3) substrates by the sol–gel technique.The phase structure,magnetic propertie...We report the preparation of epitaxial La_(0.7)Sr_(0.3)MnO_(3) thin films grown on(001)-oriented 0.72Pb(Mg_(1/3)Nb_(2/3))TO_(3)-0.28PbTiO_(3) substrates by the sol–gel technique.The phase structure,magnetic properties and magnetoresistance of the samples are investigated by using high solution X-ray diffraction,atomic force microscopy,physical property measurement system,respectively.The La_(0.7)Sr_(0.3)MnO_(3) thin films display a well-defined hysteresis loop and typical ferromagnetism behavior at lower temperature.High magnetoresistance at 5 T of 42%appears at 227K for La_(0.7)Sr_(0.3)MnO_(3) thin film.展开更多
基金supported by the National Natural Science Foundation of China (60974082,11171094)the Fundamental Research Funds for the Central Universities (K50510700004)+1 种基金the Foundation and Advanced Technology Research Program of Henan Province (102300410264)the Basic Research Program of the Education Department of Henan Province (2010A110010)
文摘Structure learning of Bayesian networks is a wellresearched but computationally hard task.For learning Bayesian networks,this paper proposes an improved algorithm based on unconstrained optimization and ant colony optimization（U-ACO-B） to solve the drawbacks of the ant colony optimization（ACO-B）.In this algorithm,firstly,an unconstrained optimization problem is solved to obtain an undirected skeleton,and then the ACO algorithm is used to orientate the edges,thus returning the final structure.In the experimental part of the paper,we compare the performance of the proposed algorithm with ACO-B algorithm.The experimental results show that our method is effective and greatly enhance convergence speed than ACO-B algorithm.
基金supported by the National Natural Science Fundation of China (6097408261075055)the Fundamental Research Funds for the Central Universities (K50510700004)
文摘The learning Bayesian network （BN） structure from data is an NP-hard problem and still one of the most exciting chal- lenges in the machine learning. In this work, a novel algorithm is presented which combines ideas from local learning, constraint- based, and search-and-score techniques in a principled and ef- fective way. It first reconstructs the junction tree of a BN and then performs a K2-scoring greedy search to orientate the local edges in the cliques of junction tree. Theoretical and experimental results show the proposed algorithm is capable of handling networks with a large number of variables. Its comparison with the well-known K2 algorithm is also presented.
基金This work was supported by the Science and technology innovation leading talent project of special support plan for high-level talents in Zhejiang Province(2021R52032).
文摘Vector beams have attracted widespread attention because of their unique optical properties;in particular,their combination with tight focusing can produce many interesting phenomena.The rise of 3D printing technology provides more possibilities for exploration.In this work,a cascading method involving a metamaterial and a metalens is used to generate a tightly focused field of vector beams in the terahertz band,which is prepared via 3D printing.As a proof-of-concept demonstration,a series of metamaterial modules capable of generating states of different orbital angular momentum are proposed by cascading with a metalens.The experimental results are in good agreement with the simulation results,fully verifying the feasibility of the scheme.The proposed design and fabrication strategy provides a new idea for the tight focusing of terahertz vector beams.
基金the Natural Science Foundation of China(Grant Nos.51472199,11534015)the National 111 Project of China(B14040)the Beijing Institute of Technology Research Fund Program for Young Scholars(Grant No.3050012261527)。
文摘Voltage control of magnetism in multiferroics,where the ferromagnetism and ferroelectricity are simultaneously exhibiting,is of great importance to achieve compact,fast and energy efficient voltage controllable magnetic/microwave devices.Particularly,these devices are widely used in radar,aircraft,cell phones and satellites,where volume,response time and energy consumption is critical.Researchers realized electric field tuning of magnetic properties like magnetization,magnetic anisotropy and permeability in varied multiferroic heterostructures such as bulk,thin films and nanostructure by different magnetoelectric(ME)coupling mechanism:strain/stress,interfacial charge,spin–electromagnetic(EM)coupling and exchange coupling,etc.In this review,we focus on voltage control of ferromagnetic resonance(FMR)in multiferroics.ME coupling-induced FMR change is critical in microwave devices,where the electric field tuning of magnetic effective anisotropic field determines the tunability of the performance of microwave devices.Experimentally,FMR measurement technique is also an important method to determine the small effective magnetic field change in small amount of magnetic material precisely due to its high sensitivity and to reveal the deep science of multiferroics,especially,voltage control of magnetism in novel mechanisms like interfacial charge,spin–EM coupling and exchange coupling.
基金financially supported by International Science&Technology Cooperation Program of China(Grant no.2011DFA51880)111 Project of China(B14040).
文摘We report the preparation of epitaxial La_(0.7)Sr_(0.3)MnO_(3) thin films grown on(001)-oriented 0.72Pb(Mg_(1/3)Nb_(2/3))TO_(3)-0.28PbTiO_(3) substrates by the sol–gel technique.The phase structure,magnetic properties and magnetoresistance of the samples are investigated by using high solution X-ray diffraction,atomic force microscopy,physical property measurement system,respectively.The La_(0.7)Sr_(0.3)MnO_(3) thin films display a well-defined hysteresis loop and typical ferromagnetism behavior at lower temperature.High magnetoresistance at 5 T of 42%appears at 227K for La_(0.7)Sr_(0.3)MnO_(3) thin film.
