In order to conduct research and analysis on the construction of application-oriented undergraduate data science and big data technology courses,the professional development characteristics of universities and enterpr...In order to conduct research and analysis on the construction of application-oriented undergraduate data science and big data technology courses,the professional development characteristics of universities and enterprises should be taken into consideration,the development trend of the big data industry should be scrutinized,and professional application-oriented talents should be cultivated in line with job requirements.This paper expounds the demand for capacity-building professional development in application-oriented undergraduate data science and big data technology courses,conducts research and analysis on the current situation of professional development,and puts forward strategies in hope to provide reference for capacity-building professional development.展开更多
We investigate the ground-state Riemannian metric and the cyclic quantum distance of an inhomogeneous quantum spin-1/2 chain in a transverse field. This model can be diagonalized by using a general canonical transform...We investigate the ground-state Riemannian metric and the cyclic quantum distance of an inhomogeneous quantum spin-1/2 chain in a transverse field. This model can be diagonalized by using a general canonical transformation to the fermionic Hamiltonian mapped from the spin system. The ground-state Riemannian metric is derived exactly on a parameter manifold ring S^1, which is introduced by performing a gauge transformation to the spin Hamiltonian through a twist operator. The cyclic ground-state quantum distance and the second derivative of the ground-state energy are studied in different exchange coupling parameter regions. Particularly, we show that, in the case of exchange coupling parameter J a = J b, the quantum ferromagnetic phase can be characterized by an invariant quantum distance and this distance will decay to zero rapidly in the paramagnetic phase.展开更多
We investigate the quantum metric and topological Euler number in a cyclically modulated Su-Schrieffer-Heeger(SSH)model with long-range hopping terms.By computing the quantum geometry tensor,we derive exact expression...We investigate the quantum metric and topological Euler number in a cyclically modulated Su-Schrieffer-Heeger(SSH)model with long-range hopping terms.By computing the quantum geometry tensor,we derive exact expressions for the quantum metric and Berry curvature of the energy band electrons,and we obtain the phase diagram of the model marked by the first Chern number.Furthermore,we also obtain the topological Euler number of the energy band based on the Gauss-Bonnet theorem on the topological characterization of the closed Bloch states manifold in the first Brillouin zone.However,some regions where the Berry curvature is identically zero in the first Brillouin zone result in the degeneracy of the quantum metric,which leads to ill-defined non-integer topological Euler numbers.Nevertheless,the non-integer"Euler number"provides valuable insights and an upper bound for the absolute values of the Chern numbers.展开更多
A sandwich plate with a corrugation and auxetic honeycomb hybrid core is constructed,and its sound insulation and optimization are investigated.First,the motion governing equation of the sandwich plate is established ...A sandwich plate with a corrugation and auxetic honeycomb hybrid core is constructed,and its sound insulation and optimization are investigated.First,the motion governing equation of the sandwich plate is established by the third-order shear deformation theory(TSDT),and then combined with the fluid-structure coupling conditions,and the sound insulation is solved.The theoretical results are validated by COMSOL simulation results,and the effects of the structural parameter on the sound insulation are analyzed.Finally,the standard genetic algorithm is adopted to optimize the sound insulation of the sandwich plate.展开更多
William Butler Yeats ranks among the most widely admired and intensively studied poets of the 20th century.This paper intends to explore the women who have exerted the most critical influences upon Yeats,namely Gonne,...William Butler Yeats ranks among the most widely admired and intensively studied poets of the 20th century.This paper intends to explore the women who have exerted the most critical influences upon Yeats,namely Gonne,Lady Gregory,and Georgie Hyde-Lees.Even in Yeats’s poetry involved with symbolism,it is worth noting that his employment of symbols has used these women as the archetypes,and that the historical context rendered Yeats’s representations of them in his poetry all the more interesting.展开更多
The construction of demonstration digital archives is a key project for the innovative development of the archival industry vigorously promoted by the National Archives Administration. Taking the construction of the S...The construction of demonstration digital archives is a key project for the innovative development of the archival industry vigorously promoted by the National Archives Administration. Taking the construction of the Smart Archives in Dongcheng District, Beijing as an example, this paper deeply explores the work objectives, functional requirements, and technical means of creating a demonstration digital archive. One is scientific planning, which is building the basic framework of digital archives. Proposed the infrastructure of “three major supports, five major platforms, and three major guarantees”. The second is to highlight key points and improve the basic functions of digital archives. Including hardware construction, software configuration, digitization of library archives, electronic archive management, sharing and utilization of digital archive information, and formulation of management systems for digital archives. The third is to strive for practical results and deepen the construction of smart libraries. This includes vigorously promoting the construction of smart archive centers, establishing a comprehensive management platform for smart libraries, and introducing new-generation information technology to achieve the integration of smart libraries in order to explore some mature experiences and methods that can be referenced for the creation of demonstration digital archives.展开更多
The dual-rotor structure serves as the primary source of vibration in aero-engines. Understanding itsdynamical model and analyzing dynamic characteristics, such as critical speed and unbalanced response, arecrucial fo...The dual-rotor structure serves as the primary source of vibration in aero-engines. Understanding itsdynamical model and analyzing dynamic characteristics, such as critical speed and unbalanced response, arecrucial for rotor system dynamics. Previous work introduced a coaxial dual-rotor-support scheme for aeroengines,and a physical model featuring a high-speed flexible inner rotor with a substantial length-to-diameter ratiowas designed. Then a finite element (FE) dynamic model based on the Timoshenko beam elements and rigid bodykinematics of the dual-rotor system is modeled, with the Newmark method and Newton–Raphson method used forthe numerical calculation to study the dynamic characteristics of the system. Three different simulation models,including beam-based FE (1D) model, solid-based FE (3D) model, and transfer matrix model, were designed tostudy the characteristics of mode and the critical speed characteristic of the dual-rotor system. The unbalancedresponse of the dual-rotor system was analyzed to study the influence of mass unbalance on the rotor system. Theeffect of different disk unbalance phases and different speed ratios on the dynamic characteristics of the dual-rotorsystem was investigated in detail. The experimental result shows that the beam-based FE model is effective andsuitable for studying the dual-rotor system.展开更多
The modified Korteweg-de Vries (mKdV) typed equations can be used to describe certain nonlinear phenomena in fluids, plasmas, and optics. In this paper, the discretized mKdV lattice equation is investigated. With th...The modified Korteweg-de Vries (mKdV) typed equations can be used to describe certain nonlinear phenomena in fluids, plasmas, and optics. In this paper, the discretized mKdV lattice equation is investigated. With the aid of symbolic computation, the discrete matrix spectral problem for that system is constructed. Darboux transformation for that system is established based on the resulting spectral problem. Explicit solutions are derived via the Darboux transformation. Structures of those solutions are shown graphically, which might be helpful to understand some physical processes in fluids, plasmas, and optics.展开更多
Fault prediction technology of running state of electromechanical systems is one of the key technologies that ensure safe and reliable operation of electromechanical equipment in health state. For multiple types of mo...Fault prediction technology of running state of electromechanical systems is one of the key technologies that ensure safe and reliable operation of electromechanical equipment in health state. For multiple types of modern, high-end and key electromechanical equipment, this paper will describe the early faults prediction method for multi-type electromechanical systems, which is favorable for predicting early faults of complex electromechanical systems in non-stationary, nonlinear, variable working conditions and long-time running state; the paper shall introduce the reconfigurable integration technology of series safety monitoring systems based on which the integrated development platform of series safety monitoring systems is built. This platform can adapt to integrated R&D of series safety monitoring systems characterized by high technology, multiple species and low volume. With the help of this platform, series safety monitoring systems were developed, and the Remote Network Security Monitoring Center for Facility Groups was built. Experimental research and engineering applications show that: this new fault prediction method has realized the development trend features extraction of typical electromechanical systems, multi-information fusion, intelligent information decision-making and so on, improving the processing accuracy, relevance and applicability of information; new reconfigurable integration technologies have improved the integration level and R&D efficiency of series safety monitoring systems as well as expanded the scope of application; the series safety monitoring systems developed based on reconfigurable integration platform has already played an important role in many aspects including ensuring safety operation of equipment, stabilizing product quality, optimizing running state, saving energy consumption, reducing environmental pollution, improving working conditions, carrying out scientific maintenance, advancing equipment utilization, saving maintenance charge and enhancing the level of information management.展开更多
This study investigates the vibration and acoustic properties of porous foam functionally graded(FG)plates under the influence of the temperature field.The dynamics equations of the system are established based on Ham...This study investigates the vibration and acoustic properties of porous foam functionally graded(FG)plates under the influence of the temperature field.The dynamics equations of the system are established based on Hamilton's principle by using the higher-order shear deformation theory under the linear displacement-strain assumption.The displacement shape function is assumed according to the four-sided simply-supported(SSSS)boundary condition,and the characteristic equations of the system are derived by combining the motion control equations.The theoretical model of vibro-acoustic coupling is established by using the acoustic theory and fluid-structure coupling solution method under the simple harmonic acoustic wave.The system's natural frequency and sound transmission loss(STL)are obtained through programming calculations and compared with the literature and COMSOL simulation to verify the validity and reliability of the theoretical model.The effects of various factors,such as temperature,porosity coefficients,gradient index,core thickness,width-to-thickness ratio on the vibration,and STL characteristics of the system,are discussed.The results provide a theoretical basis for the application of porous foam FG plates in engineering to optimize vibration and sound transmission properties.展开更多
Bloody Mahjong is a kind of mahjong.It is very popular in China in recent years.It not only has the characteristics of mahjong's conventional state space,huge hidden information,complicated rules,and large randomn...Bloody Mahjong is a kind of mahjong.It is very popular in China in recent years.It not only has the characteristics of mahjong's conventional state space,huge hidden information,complicated rules,and large randomness of hand cards but also has special rules such as Change three,Hu must lack at least one suit,and Continue playing after Hu.These rules increase the difficulty of research.These special rules are used as the input of the deep learning DenseNet model.DenseNet is used to extract the Mahjong situation features.The learned features are used as the input of the classification algorithm XGBoost,and then the XGBoost algorithm is used to derive the card strategy.Experiments show that the fusion model of deep learning and XGBoost proposed in this paper has higher accuracy than the single model using only one of them in the case of highdimensional sparse features.In the case of fewer training rounds,accuracy of the model can still reach 83%.In the games against real people,it plays like human.展开更多
With the universal test machine and temperature test chamber, the effect of pressure and temperature on the behavior of 1-3 and 1-3-2 piezocomposites prepared with PZT/epoxy in our lab has been investigated through el...With the universal test machine and temperature test chamber, the effect of pressure and temperature on the behavior of 1-3 and 1-3-2 piezocomposites prepared with PZT/epoxy in our lab has been investigated through electrical impedance and dielectric analysis. The permittivity, resonant frequency and dielectric loss of the composites have been measured under vertical stress and temperature, and the variety of the material properties under pressure and temperature could also be obtained. The pressure and temperature stability of the composites have been assessed through experiments. The data of these two types of composites indicated that the stability of 1-342 composite with pressure was better than that of 1-3 composite, and two composites have almost the same dielectric stability with temperature. However, 1-3-2 composite showed slower frequency variation than 1-3 composite.展开更多
We investigate the perturbation to discrete conformal invariance and the adiabatic invariants of Lagrangian systems. A variational algorithm is proposed for a system subjected to the perturbation quantities. The discr...We investigate the perturbation to discrete conformal invariance and the adiabatic invariants of Lagrangian systems. A variational algorithm is proposed for a system subjected to the perturbation quantities. The discrete determining equations of the perturbations to conformal invariance are established. For perturbed Lagrangian systems, the condition of the existence of adiabatic invariant is derived from the discrete perturbation to conformal invariance. The numerical simulations demonstrate that the variational algorithm has the higher precision and the longer time stability than the standard numerical method.展开更多
By using of the invariant theory, we study a two energy-level Bose-Einstein condensate interacting with a timedependent laser field, the dynamical and geometric phases are given respectively. The Aharonov-Anandan phas...By using of the invariant theory, we study a two energy-level Bose-Einstein condensate interacting with a timedependent laser field, the dynamical and geometric phases are given respectively. The Aharonov-Anandan phase is also obtained under the cyclical evolution.展开更多
The concept of local resonance phononic crystals proposed in recent years provides a new chance for theoretical and technical breakthroughs in the structural vibration reduction.In this paper,a novel sandwich-like pla...The concept of local resonance phononic crystals proposed in recent years provides a new chance for theoretical and technical breakthroughs in the structural vibration reduction.In this paper,a novel sandwich-like plate model with local resonator to acquire specific low-frequency bandgaps is proposed.The core layer of the present local resonator is composed by the simply supported overhanging beam,linear spring and mass block,and well connected with the upper and lower surface panels.The simply supported overhanging beam is free at right end,and an additional linear spring is added at the left end.The wave equation is established based on the Hamilton principle,and the bending wave bandgap is further obtained.The theoretical results are verified by the COMSOL finite element software.The bandgaps and vibration characteristics of the local resonance sandwich-like plate are studied in detail.The factors which could have effects on the bandgap characteristics,such as the structural damping,mass of vibrator,position of vibrator,bending stiffness of the beam,and the boundary conditions of the sandwich-like plates,are analyzed.The result shows that the stopband is determined by the natural frequency of the resonator,the mass ratio of the resonator,and the surface panel.It shows that the width of bandgap is greatly affected by the damping ratio of the resonator.Finally,it can also be found that the boundary conditions can affect the isolation efficiency.展开更多
As the complexity of space exploration missions augments,how to enhance the overall performance of communication,ranging or other functions has become a challengeable problem.Considering the integration of communicati...As the complexity of space exploration missions augments,how to enhance the overall performance of communication,ranging or other functions has become a challengeable problem.Considering the integration of communication and ranging,we present a bit-level composite signal for simultaneous ranging and communication.In this composite method,through a specially designed mapping scheme using low-weight codewords,the information sequence is converted to a sparse sequence which is then superimposed on the ranging code.For ranging,the correlation characteristics of the ranging code component can be maintained to calculate the transmitter-receiver distance.For communications,the sparse sequence can be extracted without interference by eliminating the ranging code component.Simulation results show that the proposed composite signal can support communication and ranging simultaneously with limited sacrifice of ranging performance,and the performance loss of ranging can be controlled and minimized by lowering the density of information sequences using different sparsification encoding methods.展开更多
Under the background of“Internet plus”rapid development,the agricultural logistics industry should apply information technology to every link of the agricultural product logistics industry chain.By making full use o...Under the background of“Internet plus”rapid development,the agricultural logistics industry should apply information technology to every link of the agricultural product logistics industry chain.By making full use of the decision making module of the agricultural logistics information system,we can realize the full sharing of information and data resources,which makes the decision-making scheme of the agricultural logistics information system more optimized.In real economic society,the uncertainty and mismatch between the customer’s logistics service demand and the logistics service capability that the logistics service function provider can provide,that is,when the two information are asymmetric,how to use the third-party contract to coordinate the income and profit distribution of the two,to make the information system decision making more reasonable?This paper mainly studies the coordination scheme of agricultural logistics information system decision making under uncertain output and demand information by introducing the spot market.A joint coordination strategy based on revenue sharing and penalty feedback contracts proposes decentralized decision making based on game theory.Experiments show that the flexible ordering strategy proposed in this paper can reduce the logistics service supply chain’s uncertainty and significantly improve the logistics service supply chain’s overall income level through coordination contracts.展开更多
Energy harvesting induced from flowing fluids(e.g.,air and water flows)is a well-known process,which can be regarded as a sustainable and renewable energy source.In addition to traditional high-efficiency devices(e.g....Energy harvesting induced from flowing fluids(e.g.,air and water flows)is a well-known process,which can be regarded as a sustainable and renewable energy source.In addition to traditional high-efficiency devices(e.g.,turbines and watermills),the micro-power extracting technologies based on the flow-induced vibration(FIV)effect have sparked great concerns by virtue of their prospective applications as a self-power source for the microelectronic devices in recent years.This article aims to conduct a comprehensive review for the FIV working principle and their potential applications for energy harvesting.First,various classifications of the FIV effect for energy harvesting are briefly introduced,such as vortex-induced vibration(VIV),galloping,flutter,and wake-induced vibration(WIV).Next,the development of FIV energy harvesting techniques is reviewed to discuss the research works in the past three years.The application of hybrid FIV energy harvesting techniques that can enhance the harvesting performance is also presented.Furthermore,the nonlinear designs of FIV-based energy harvesters are reported in this study,e.g.,multi-stability and limit-cycle oscillation(LCO)phenomena.Moreover,advanced FIV-based energy harvesting studies for fluid engineering applications are briefly mentioned.Finally,conclusions and future outlook are summarized.展开更多
Based on the necessity of three dimensional modeling with computer in teaching reform, this paper is the summarization of reform practice of teaching engineering drawing in our institute. The teaching reform begins wi...Based on the necessity of three dimensional modeling with computer in teaching reform, this paper is the summarization of reform practice of teaching engineering drawing in our institute. The teaching reform begins with three dimensional modeling that used computer instead of board. On the basis of target of teaching reform, set of teaching content, arrangement of class hour and teaching method, the research of teaching practice have been done, and very good effects in teaching of engineering drawing have been achieved.展开更多
We first introduce the empirical mode decomposition (EMD) and holo-spectrum analysis. Then we decompose the vibration signal of the equipment by EMD, re-organize the signal closely associated with the original signa...We first introduce the empirical mode decomposition (EMD) and holo-spectrum analysis. Then we decompose the vibration signal of the equipment by EMD, re-organize the signal closely associated with the original signal, eliminate the noise signal better, and analyze the holographic re-signal spectrum, which makes the amplitude, frequency and phase combinecompletely, reflecting the equipment vibration morphology fully. Particularly applying a two-dimensional holo-spectrum can obtain the direction of rotation order harmonic, size, shape, and the relation- . ship between order harmonic generation rotor vibrations, and so on. The traditional signal processing methods can not eliminate noise well. We apply this method to the rotor vibration signal of fault diagnosis, eliminate noise and reflect the equipment vibration characteristics well.展开更多
文摘In order to conduct research and analysis on the construction of application-oriented undergraduate data science and big data technology courses,the professional development characteristics of universities and enterprises should be taken into consideration,the development trend of the big data industry should be scrutinized,and professional application-oriented talents should be cultivated in line with job requirements.This paper expounds the demand for capacity-building professional development in application-oriented undergraduate data science and big data technology courses,conducts research and analysis on the current situation of professional development,and puts forward strategies in hope to provide reference for capacity-building professional development.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11404023 and 11347131)
文摘We investigate the ground-state Riemannian metric and the cyclic quantum distance of an inhomogeneous quantum spin-1/2 chain in a transverse field. This model can be diagonalized by using a general canonical transformation to the fermionic Hamiltonian mapped from the spin system. The ground-state Riemannian metric is derived exactly on a parameter manifold ring S^1, which is introduced by performing a gauge transformation to the spin Hamiltonian through a twist operator. The cyclic ground-state quantum distance and the second derivative of the ground-state energy are studied in different exchange coupling parameter regions. Particularly, we show that, in the case of exchange coupling parameter J a = J b, the quantum ferromagnetic phase can be characterized by an invariant quantum distance and this distance will decay to zero rapidly in the paramagnetic phase.
基金Project supported by the Beijing Natural Science Foundation(Grant No.1232026)the Qinxin Talents Program of BISTU(Grant No.QXTCP C201711)+2 种基金the R&D Program of Beijing Municipal Education Commission(Grant No.KM202011232017)the National Natural Science Foundation of China(Grant No.12304190)the Research fund of BISTU(Grant No.2022XJJ32).
文摘We investigate the quantum metric and topological Euler number in a cyclically modulated Su-Schrieffer-Heeger(SSH)model with long-range hopping terms.By computing the quantum geometry tensor,we derive exact expressions for the quantum metric and Berry curvature of the energy band electrons,and we obtain the phase diagram of the model marked by the first Chern number.Furthermore,we also obtain the topological Euler number of the energy band based on the Gauss-Bonnet theorem on the topological characterization of the closed Bloch states manifold in the first Brillouin zone.However,some regions where the Berry curvature is identically zero in the first Brillouin zone result in the degeneracy of the quantum metric,which leads to ill-defined non-integer topological Euler numbers.Nevertheless,the non-integer"Euler number"provides valuable insights and an upper bound for the absolute values of the Chern numbers.
基金Project supported by the National Natural Science Foundation of China (Nos. 12172339 and 11732005)the Beijing Natural Science Foundation of China (No. 1222006)。
文摘A sandwich plate with a corrugation and auxetic honeycomb hybrid core is constructed,and its sound insulation and optimization are investigated.First,the motion governing equation of the sandwich plate is established by the third-order shear deformation theory(TSDT),and then combined with the fluid-structure coupling conditions,and the sound insulation is solved.The theoretical results are validated by COMSOL simulation results,and the effects of the structural parameter on the sound insulation are analyzed.Finally,the standard genetic algorithm is adopted to optimize the sound insulation of the sandwich plate.
文摘William Butler Yeats ranks among the most widely admired and intensively studied poets of the 20th century.This paper intends to explore the women who have exerted the most critical influences upon Yeats,namely Gonne,Lady Gregory,and Georgie Hyde-Lees.Even in Yeats’s poetry involved with symbolism,it is worth noting that his employment of symbols has used these women as the archetypes,and that the historical context rendered Yeats’s representations of them in his poetry all the more interesting.
文摘The construction of demonstration digital archives is a key project for the innovative development of the archival industry vigorously promoted by the National Archives Administration. Taking the construction of the Smart Archives in Dongcheng District, Beijing as an example, this paper deeply explores the work objectives, functional requirements, and technical means of creating a demonstration digital archive. One is scientific planning, which is building the basic framework of digital archives. Proposed the infrastructure of “three major supports, five major platforms, and three major guarantees”. The second is to highlight key points and improve the basic functions of digital archives. Including hardware construction, software configuration, digitization of library archives, electronic archive management, sharing and utilization of digital archive information, and formulation of management systems for digital archives. The third is to strive for practical results and deepen the construction of smart libraries. This includes vigorously promoting the construction of smart archive centers, establishing a comprehensive management platform for smart libraries, and introducing new-generation information technology to achieve the integration of smart libraries in order to explore some mature experiences and methods that can be referenced for the creation of demonstration digital archives.
文摘The dual-rotor structure serves as the primary source of vibration in aero-engines. Understanding itsdynamical model and analyzing dynamic characteristics, such as critical speed and unbalanced response, arecrucial for rotor system dynamics. Previous work introduced a coaxial dual-rotor-support scheme for aeroengines,and a physical model featuring a high-speed flexible inner rotor with a substantial length-to-diameter ratiowas designed. Then a finite element (FE) dynamic model based on the Timoshenko beam elements and rigid bodykinematics of the dual-rotor system is modeled, with the Newmark method and Newton–Raphson method used forthe numerical calculation to study the dynamic characteristics of the system. Three different simulation models,including beam-based FE (1D) model, solid-based FE (3D) model, and transfer matrix model, were designed tostudy the characteristics of mode and the critical speed characteristic of the dual-rotor system. The unbalancedresponse of the dual-rotor system was analyzed to study the influence of mass unbalance on the rotor system. Theeffect of different disk unbalance phases and different speed ratios on the dynamic characteristics of the dual-rotorsystem was investigated in detail. The experimental result shows that the beam-based FE model is effective andsuitable for studying the dual-rotor system.
基金Supported by the National Natural Science Foundation of China under Grant No. 60772023by the Open Fund of the State Key Laboratory of Software Development Environment under Grant No. BUAA-SKLSDE-09KF-04+2 种基金Beijing University of Aeronautics and Astronautics, by the National Basic Research Program of China (973 Program) under Grant No. 2005CB321901the Specialized Research Fund for the Doctoral Program of Higher Education under Grant Nos. 20060006024 and 200800130006Chinese Ministry of Education, and Scientific Research Common Program of Beijing Municipal Commission of Education under Grant No. KM201010772020
文摘The modified Korteweg-de Vries (mKdV) typed equations can be used to describe certain nonlinear phenomena in fluids, plasmas, and optics. In this paper, the discretized mKdV lattice equation is investigated. With the aid of symbolic computation, the discrete matrix spectral problem for that system is constructed. Darboux transformation for that system is established based on the resulting spectral problem. Explicit solutions are derived via the Darboux transformation. Structures of those solutions are shown graphically, which might be helpful to understand some physical processes in fluids, plasmas, and optics.
基金Supported by National Natural Science Fund Project(51275052)Key project supported by Beijing Municipal Natural Science Foundation(3131002)Open topic of Key Laboratory of Key Laboratory of Modern Measurement & Control Technology,Ministry of Education(KF20141123202,KF20111123201)
文摘Fault prediction technology of running state of electromechanical systems is one of the key technologies that ensure safe and reliable operation of electromechanical equipment in health state. For multiple types of modern, high-end and key electromechanical equipment, this paper will describe the early faults prediction method for multi-type electromechanical systems, which is favorable for predicting early faults of complex electromechanical systems in non-stationary, nonlinear, variable working conditions and long-time running state; the paper shall introduce the reconfigurable integration technology of series safety monitoring systems based on which the integrated development platform of series safety monitoring systems is built. This platform can adapt to integrated R&D of series safety monitoring systems characterized by high technology, multiple species and low volume. With the help of this platform, series safety monitoring systems were developed, and the Remote Network Security Monitoring Center for Facility Groups was built. Experimental research and engineering applications show that: this new fault prediction method has realized the development trend features extraction of typical electromechanical systems, multi-information fusion, intelligent information decision-making and so on, improving the processing accuracy, relevance and applicability of information; new reconfigurable integration technologies have improved the integration level and R&D efficiency of series safety monitoring systems as well as expanded the scope of application; the series safety monitoring systems developed based on reconfigurable integration platform has already played an important role in many aspects including ensuring safety operation of equipment, stabilizing product quality, optimizing running state, saving energy consumption, reducing environmental pollution, improving working conditions, carrying out scientific maintenance, advancing equipment utilization, saving maintenance charge and enhancing the level of information management.
基金Project supported by the National Natural Science Foundation of China(No.11972082)。
文摘This study investigates the vibration and acoustic properties of porous foam functionally graded(FG)plates under the influence of the temperature field.The dynamics equations of the system are established based on Hamilton's principle by using the higher-order shear deformation theory under the linear displacement-strain assumption.The displacement shape function is assumed according to the four-sided simply-supported(SSSS)boundary condition,and the characteristic equations of the system are derived by combining the motion control equations.The theoretical model of vibro-acoustic coupling is established by using the acoustic theory and fluid-structure coupling solution method under the simple harmonic acoustic wave.The system's natural frequency and sound transmission loss(STL)are obtained through programming calculations and compared with the literature and COMSOL simulation to verify the validity and reliability of the theoretical model.The effects of various factors,such as temperature,porosity coefficients,gradient index,core thickness,width-to-thickness ratio on the vibration,and STL characteristics of the system,are discussed.The results provide a theoretical basis for the application of porous foam FG plates in engineering to optimize vibration and sound transmission properties.
基金Promoting Research Level Program,Beijing Information Science and Technology University,Grant/Award Number:5211910927General Science and Technology Research program,Grant/Award Number:KM201911232002Graduated Education Program at Beijing Information Science and Technology University。
文摘Bloody Mahjong is a kind of mahjong.It is very popular in China in recent years.It not only has the characteristics of mahjong's conventional state space,huge hidden information,complicated rules,and large randomness of hand cards but also has special rules such as Change three,Hu must lack at least one suit,and Continue playing after Hu.These rules increase the difficulty of research.These special rules are used as the input of the deep learning DenseNet model.DenseNet is used to extract the Mahjong situation features.The learned features are used as the input of the classification algorithm XGBoost,and then the XGBoost algorithm is used to derive the card strategy.Experiments show that the fusion model of deep learning and XGBoost proposed in this paper has higher accuracy than the single model using only one of them in the case of highdimensional sparse features.In the case of fewer training rounds,accuracy of the model can still reach 83%.In the games against real people,it plays like human.
基金supported by the National Natural Science Foundation of China (No.60871038)the Beijing Natural Science Foundation (No.4092014)Foundation of PHR(IHLB)
文摘With the universal test machine and temperature test chamber, the effect of pressure and temperature on the behavior of 1-3 and 1-3-2 piezocomposites prepared with PZT/epoxy in our lab has been investigated through electrical impedance and dielectric analysis. The permittivity, resonant frequency and dielectric loss of the composites have been measured under vertical stress and temperature, and the variety of the material properties under pressure and temperature could also be obtained. The pressure and temperature stability of the composites have been assessed through experiments. The data of these two types of composites indicated that the stability of 1-342 composite with pressure was better than that of 1-3 composite, and two composites have almost the same dielectric stability with temperature. However, 1-3-2 composite showed slower frequency variation than 1-3 composite.
基金supported by the National Natural Science Foundation of China(Grant No.11502071)the Special Research Project of Beijing Information Science and Technology University,China
文摘We investigate the perturbation to discrete conformal invariance and the adiabatic invariants of Lagrangian systems. A variational algorithm is proposed for a system subjected to the perturbation quantities. The discrete determining equations of the perturbations to conformal invariance are established. For perturbed Lagrangian systems, the condition of the existence of adiabatic invariant is derived from the discrete perturbation to conformal invariance. The numerical simulations demonstrate that the variational algorithm has the higher precision and the longer time stability than the standard numerical method.
基金Supported by the National Natural Science Foundation of China under Grant No 10574060 and the Beijing Natural Science Foundation under Grant No 1072010.
文摘By using of the invariant theory, we study a two energy-level Bose-Einstein condensate interacting with a timedependent laser field, the dynamical and geometric phases are given respectively. The Aharonov-Anandan phase is also obtained under the cyclical evolution.
基金the National Natural Science Foundation of China(Nos.11872127,11832002,11732005)Qin Xin Talents Cultivation Program of Beijing Information Science and Technology University(No.QXTCP A201901)the Project High-Level Innovative Team Building Plan for Beijing Municipal Colleges and Universities(No.IDHT20180513)。
文摘The concept of local resonance phononic crystals proposed in recent years provides a new chance for theoretical and technical breakthroughs in the structural vibration reduction.In this paper,a novel sandwich-like plate model with local resonator to acquire specific low-frequency bandgaps is proposed.The core layer of the present local resonator is composed by the simply supported overhanging beam,linear spring and mass block,and well connected with the upper and lower surface panels.The simply supported overhanging beam is free at right end,and an additional linear spring is added at the left end.The wave equation is established based on the Hamilton principle,and the bending wave bandgap is further obtained.The theoretical results are verified by the COMSOL finite element software.The bandgaps and vibration characteristics of the local resonance sandwich-like plate are studied in detail.The factors which could have effects on the bandgap characteristics,such as the structural damping,mass of vibrator,position of vibrator,bending stiffness of the beam,and the boundary conditions of the sandwich-like plates,are analyzed.The result shows that the stopband is determined by the natural frequency of the resonator,the mass ratio of the resonator,and the surface panel.It shows that the width of bandgap is greatly affected by the damping ratio of the resonator.Finally,it can also be found that the boundary conditions can affect the isolation efficiency.
基金This work was supported in part by National Natural Science Foundation of China(61671324)the Director’s Funding from Pilot National Laboratory for Marine Science and Technology(Qingdao)(QNLM201712)Zhan Xu was supported in part by National Natural Science Foundation of China(61620106001).
文摘As the complexity of space exploration missions augments,how to enhance the overall performance of communication,ranging or other functions has become a challengeable problem.Considering the integration of communication and ranging,we present a bit-level composite signal for simultaneous ranging and communication.In this composite method,through a specially designed mapping scheme using low-weight codewords,the information sequence is converted to a sparse sequence which is then superimposed on the ranging code.For ranging,the correlation characteristics of the ranging code component can be maintained to calculate the transmitter-receiver distance.For communications,the sparse sequence can be extracted without interference by eliminating the ranging code component.Simulation results show that the proposed composite signal can support communication and ranging simultaneously with limited sacrifice of ranging performance,and the performance loss of ranging can be controlled and minimized by lowering the density of information sequences using different sparsification encoding methods.
基金The Agricultural Science and Technology Innovation Program(ASTIP-IAED-2021-08).
文摘Under the background of“Internet plus”rapid development,the agricultural logistics industry should apply information technology to every link of the agricultural product logistics industry chain.By making full use of the decision making module of the agricultural logistics information system,we can realize the full sharing of information and data resources,which makes the decision-making scheme of the agricultural logistics information system more optimized.In real economic society,the uncertainty and mismatch between the customer’s logistics service demand and the logistics service capability that the logistics service function provider can provide,that is,when the two information are asymmetric,how to use the third-party contract to coordinate the income and profit distribution of the two,to make the information system decision making more reasonable?This paper mainly studies the coordination scheme of agricultural logistics information system decision making under uncertain output and demand information by introducing the spot market.A joint coordination strategy based on revenue sharing and penalty feedback contracts proposes decentralized decision making based on game theory.Experiments show that the flexible ordering strategy proposed in this paper can reduce the logistics service supply chain’s uncertainty and significantly improve the logistics service supply chain’s overall income level through coordination contracts.
基金the National Natural Science Foundation of China (Nos. 11972051 and 11672008)the Opening Project Foundation of the State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures of China (No. KF-2020-11)+1 种基金the Seed Foundation of Beijing University of Technology for International Research Cooperation of China (No. 2021A08)the Innovation and Technology Commission of the Hong Kong Special Administrative Region to the Hong Kong Branch of National Rail Transit Electrification and Automation Engineering Technology Research Center of China (No. K-BBY1)
文摘Energy harvesting induced from flowing fluids(e.g.,air and water flows)is a well-known process,which can be regarded as a sustainable and renewable energy source.In addition to traditional high-efficiency devices(e.g.,turbines and watermills),the micro-power extracting technologies based on the flow-induced vibration(FIV)effect have sparked great concerns by virtue of their prospective applications as a self-power source for the microelectronic devices in recent years.This article aims to conduct a comprehensive review for the FIV working principle and their potential applications for energy harvesting.First,various classifications of the FIV effect for energy harvesting are briefly introduced,such as vortex-induced vibration(VIV),galloping,flutter,and wake-induced vibration(WIV).Next,the development of FIV energy harvesting techniques is reviewed to discuss the research works in the past three years.The application of hybrid FIV energy harvesting techniques that can enhance the harvesting performance is also presented.Furthermore,the nonlinear designs of FIV-based energy harvesters are reported in this study,e.g.,multi-stability and limit-cycle oscillation(LCO)phenomena.Moreover,advanced FIV-based energy harvesting studies for fluid engineering applications are briefly mentioned.Finally,conclusions and future outlook are summarized.
基金Supported by Beijing City Institution of Higher Learning Talent Education Program Project Foundation (PHR200906213PHR201007234)
文摘Based on the necessity of three dimensional modeling with computer in teaching reform, this paper is the summarization of reform practice of teaching engineering drawing in our institute. The teaching reform begins with three dimensional modeling that used computer instead of board. On the basis of target of teaching reform, set of teaching content, arrangement of class hour and teaching method, the research of teaching practice have been done, and very good effects in teaching of engineering drawing have been achieved.
文摘We first introduce the empirical mode decomposition (EMD) and holo-spectrum analysis. Then we decompose the vibration signal of the equipment by EMD, re-organize the signal closely associated with the original signal, eliminate the noise signal better, and analyze the holographic re-signal spectrum, which makes the amplitude, frequency and phase combinecompletely, reflecting the equipment vibration morphology fully. Particularly applying a two-dimensional holo-spectrum can obtain the direction of rotation order harmonic, size, shape, and the relation- . ship between order harmonic generation rotor vibrations, and so on. The traditional signal processing methods can not eliminate noise well. We apply this method to the rotor vibration signal of fault diagnosis, eliminate noise and reflect the equipment vibration characteristics well.