Reticulated shell structures (RSSs) are characterized as cyclically periodic structures. Mistuning of RSSs will induce structural mode localization. Mode localization has the following two features: some modal vect...Reticulated shell structures (RSSs) are characterized as cyclically periodic structures. Mistuning of RSSs will induce structural mode localization. Mode localization has the following two features: some modal vectors of the structure change remarkably when the values of its physical parameters (mass or stiffness) have a slight change; and the vibration of some modes is mainly restricted in some local areas of the structure. In this paper, two quantitative assessment indexes are introduced that correspond to these two features. The first feature is studied through a numerical example of a RSS, and its induced causes are analyzed by using the perturbation theory. The analysis showed that internally, mode localization is closely related to structural frequencies and externally, slight changes of the physical parameters of the structure cause instability to the RSS. A scaled model experiment to examine mode localization was carried out on a Kiewit single-layer spherical RSS, and both features of mode localization are studied. Eight tests that measured the changes of the physical parameters were carried out in the experiment. Since many modes make their contribution in structural dynamic response, six strong vibration modes were tested at random in the experimental analysis. The change and localization of the six modes are analyzed for each test. The results show that slight changes to the physical parameters are likely to induce remarkable changes and localization of some modal vectors in the RSSs.展开更多
According to the mapping theory in complex plane, the geometric features of eigen frequency loci of systems undergoing free vibrations are investigated. It is concluded that the phenomena of curve coalescence and veer...According to the mapping theory in complex plane, the geometric features of eigen frequency loci of systems undergoing free vibrations are investigated. It is concluded that the phenomena of curve coalescence and veering can be described in a unified manner from the singularities of mapping from the complex parameter plane onto the complex frequency plane. The formation of a branch point in the parameter Space is the foundation of explaining localization and veering phenomena. By the use of condensation to reduce the dimension of a system, the scope of application of the geometric theory is widely expanded. The theory is applied to examples to verify the validity of the proposed approach. The present work is an improvement and extension of recent work by M. S. Traintafyllou et al..展开更多
By use of the Hartree approximation and the method of multiple scales, we investigate quantum solitons and intrinsic localized modes in a one-dimensional antiferromagnetic chain. It is shown that there exist solitons ...By use of the Hartree approximation and the method of multiple scales, we investigate quantum solitons and intrinsic localized modes in a one-dimensional antiferromagnetic chain. It is shown that there exist solitons of two different quantum frequency bands: i.e., magnetic optical solitons and acoustic solitons. At the boundary of the Brillouin zone, these solitons becornc quantum intrinsic localized modes: their quantum eigenfrequencics are below the bottom of the harmonic optical frequency band and above the top of the harmonic acoustic frequency band.展开更多
By means of the Glauber's coherent state method combined with multiple-scale method, this paper investigates the localized modes in a quantum one-dimensional Klein-Gordon chain and finds that the equation of motion o...By means of the Glauber's coherent state method combined with multiple-scale method, this paper investigates the localized modes in a quantum one-dimensional Klein-Gordon chain and finds that the equation of motion of annihilation operator is reduced to the nonlinear Schroedinger equation. Interestingly, the model can support both bright and dark small amplitude travelling and non-travelling nonlinear localized modes in different parameter spaces.展开更多
In the classical lattice theory, solitons and localized modes can exist in many one-dimensional nonlinear lattice chains, however, in the quantum lattice theory, whether quantum solitons and localized modes can exist ...In the classical lattice theory, solitons and localized modes can exist in many one-dimensional nonlinear lattice chains, however, in the quantum lattice theory, whether quantum solitons and localized modes can exist or not in the one-dimensional lattice chains is an interesting problem. By using the number state method and the Hartree approximation combined with the method of multiple scales, we investigate quantum solirons and localized modes in a one-dimensional lattice chain with the nonlinear substrate potential. It is shown that quantum solitons do exist in this nonlinear lattice chain, and at the boundary of the phonon Brillouin zone, quantum solitons become quantum localized modes, phonons are pinned to the lattice of the vicinity at the central position j = j0.展开更多
Based upon empirical mode decomposition (EMD) method and Hilbert spectrum, a method for fault diagnosis of roller bearing is proposed. The orthogonal wavelet bases are used to translate vibration signals of a roller b...Based upon empirical mode decomposition (EMD) method and Hilbert spectrum, a method for fault diagnosis of roller bearing is proposed. The orthogonal wavelet bases are used to translate vibration signals of a roller bearing into time-scale representation, then, an envelope signal can be obtained by envelope spectrum analysis of wavelet coefficients of high scales. By applying EMD method and Hilbert transform to the envelope signal, we can get the local Hilbert marginal spectrum from which the faults in a roller bearing can be diagnosed and fault patterns can be identified. Practical vibration signals measured from roller bearings with out-race faults or inner-race faults are analyzed by the proposed method. The results show that the proposed method is superior to the traditional envelope spectrum method in extracting the fault characteristics of roller bearings.展开更多
Intrinsic localized modes in an order-parameter-preserving antiferromagnet are investigated with employing the Dyson-Maleev transformation and the coherent-state ansatz. These modes which be- low the magnon frequency ...Intrinsic localized modes in an order-parameter-preserving antiferromagnet are investigated with employing the Dyson-Maleev transformation and the coherent-state ansatz. These modes which be- low the magnon frequency band correspond to a local large-angle, low-frequency precessional mo- tion of spins, quantum states of which are characterized by the indefiniteness of the number of rele- vant magnons.展开更多
During edge localized modes(ELMs), the sheath evolution in front of the Experimental Advanced Superconducting Tokamak(EAST) upper divertor is studied to estimate the sputtered tungsten(W) atoms from the divertor targe...During edge localized modes(ELMs), the sheath evolution in front of the Experimental Advanced Superconducting Tokamak(EAST) upper divertor is studied to estimate the sputtered tungsten(W) atoms from the divertor target. A large potential drop across the sheath is formed during ELMs by compared with inter-ELMs, and the maximum of sheath potential drop can exceed one thousand of e V in current EAST operation. Due to the enhancement of the sheath potential drop during ELMs, the W physical sputtering yield from the deuterium(D) ions and the impurity ions on the upper divertor target is found to be significant. It is established that the sputtered W yield during ELMs is at least higher by an order of magnitude than inter-ELMs, and D ions and carbon(C) ions are the main ions governing the W production for the current H-mode with ELMs discharges. With increase in the pedestal electron temperature, the maximum of the D and C ion impact energy during ELMs shows a nearly linear increase, and the D ions have sufficient impact energy to cause the strong W physical sputtering. As a consequence, the D ions may dominate the sputtered W flux from the divertor target when the C concentration is controlled less than one percent for the higher heating power H-mode with ELM discharges in near future.展开更多
The effects of impurity on eigenmodes in one-dimensional dusty plasma lattices are studied. It is found that local modes can be excited besides lattice waves, due to the existence of an impurity particle. The dispersi...The effects of impurity on eigenmodes in one-dimensional dusty plasma lattices are studied. It is found that local modes can be excited besides lattice waves, due to the existence of an impurity particle. The dispersion relations of the modes are derived accordingly. Properties of the lattice and local modes are also analyzed and discussed, particularly for their symmetric features and conditions of the mode excitation.展开更多
The local vibration mode(LVM)of carbon acceptor in GaAs is studied by measuring directly the change in LVM absorption with a NIC-170 SX FT-IR spectrometer.The change in the charge state of carbon acceptor and the temp...The local vibration mode(LVM)of carbon acceptor in GaAs is studied by measuring directly the change in LVM absorption with a NIC-170 SX FT-IR spectrometer.The change in the charge state of carbon acceptor and the temperature dependence of the LVM absorption were investigated also.The contents of the impurities other than carbon were estimated by secondary ion mass spectrometry.It is observed that the frequency,the spectral form and the integrated absorption of the LVM are not affected by the change in charge state of car- bon acceptor.展开更多
H-mode discharges with lower hybrid current drive (LHCD) alone are achieved in EAST divertor plasma over a wide parameter range. These H-mode discharges are characterized by a sudden drop in Da emission and a sponta...H-mode discharges with lower hybrid current drive (LHCD) alone are achieved in EAST divertor plasma over a wide parameter range. These H-mode discharges are characterized by a sudden drop in Da emission and a spontaneous rise in main plasma density. Good lower hybrid (LH) coupling during H-mode is obtained by putting the plasma close to the antenna and by injecting D2 gas from a pipe near the grill mouse. The analysis of lower hybrid current drive properties shows that the LH deposition profile shifts off axis during H-mode, and current drive (CD) efficiency decreases due to the increase in density. Modeling results of H-mode discharges with a general ray trueing code GENRAY are reported.展开更多
The local vibrational mode (LVM) optical absorption band of carbon acceptor was investigated carefully. Because of the appearance of a sideband on the low energy side of the LVM main absorption band, it is found that ...The local vibrational mode (LVM) optical absorption band of carbon acceptor was investigated carefully. Because of the appearance of a sideband on the low energy side of the LVM main absorption band, it is found that the measured value of the integrated area for the main absorption band is sensitive to the choice of integration baseline wavenumber range (BWR). This is the main cause that the experimental results from different investigators show a wide spread for the temperature dependence of the integrated area. The origin of the sideband is also discussed.展开更多
As the basic level of national governance, local governance is deeply influenced by administrative tradition, political system and economic development level of a country. With more than thirty years of reform and ope...As the basic level of national governance, local governance is deeply influenced by administrative tradition, political system and economic development level of a country. With more than thirty years of reform and opening up, the pattern of local governance has become diversified. The diversity of governance model cannot be managed in the same way, however, it cannot affect the government’s ability to play the initiative role of governance. We need to innovate and improve the existing local governance models.展开更多
Structural dynamic problems encountered within launch vehicles are sometimes related to entire dynamic characteristics of the vehicle,and sometimes related to local dynamic characteristics of some parts of vehicles.To...Structural dynamic problems encountered within launch vehicles are sometimes related to entire dynamic characteristics of the vehicle,and sometimes related to local dynamic characteristics of some parts of vehicles.To acquire local dynamic characteristics,it usually requires the building of a three-dimensional detailed FEM model.It is important that the simulation of mass and stiffness of local part is accurate.The local mode acquisition of a gas tank and its bracket installed in the inter-tank section is taken as an example in this paper.It can be seen that the local modes are consistent with the section modal test results.Finally,the verified three-dimensional detailed FEM model of the inter-tank section is assembled within the entire launch vehicle,and the local modes of the gas tank and its bracket under flight conditions are predicted.展开更多
It has been found in recent years that using setpoint temperatures based on adaptive thermal comfort models is a successful method of energy conservation.Recent studies using adaptive setpoint temperatures incorporate...It has been found in recent years that using setpoint temperatures based on adaptive thermal comfort models is a successful method of energy conservation.Recent studies using adaptive setpoint temperatures incorporate international models from ASHRAE Standard 55 and EN16798-1.This study,however,has instead considered a regional Brazilian adaptive comfort model.This study investigates the energy demand arising from the use of a local Brazilian comfort model in order to assess the energy implications from the use of the worldwide ASHRAE Standard 55 adaptive model and various fixed setpoint temperatures.All of Brazil’s climate zones,full air-conditioning,mixed-mode building operating modes,present-day climate change scenarios,and future scenarios—specifically Representative Concentration Pathways(RCP)2.6,4.5,and 8.5 for the years 2050 and 2100—have all been taken into account in building energy simulations.The use of adaptive setpoint temperatures based on the Brazilian local model considering mixed-mode has been found to significantly reduce energy consumption when compared to static setpoint temperatures(average energy-saving values ranging from 52%to 58%)and the ASHRAE 55 adaptive model(average values ranging from 15%to 21%).Considering climate change and the mixed-mode Brazilian model,the overall energy demand for the three groups of climatic zones(annual average outdoor temperatures≤21℃,>21 and≤25℃and>25℃)ranged between 2%decrease and 5%increase,4%and 27%increase,and 13%and 45%increase,respectively.It is concluded as a consequence that setting setpoint temperatures based on the Brazilian local adaptive comfort model is a very efficient energy-saving method.展开更多
A simplified dynamic model of a dish antenna in satellite is established in this article.The modelcan be easily used to analyze the dynamic behaviour of the antenna structure.In terms of the simplifiedmodel,effects on...A simplified dynamic model of a dish antenna in satellite is established in this article.The modelcan be easily used to analyze the dynamic behaviour of the antenna structure.In terms of the simplifiedmodel,effects on dynamic characters due to the disorder of parameters are investigated in details.Thefrequencies calculated by the simplified model accord with those computed by ANSYS.Based on the modeshapes of disordered and perfect structure,the influence law and varying trend of dynamic characters ofantenna structures in satellites produced by stiffness and mass of antenna ribs,stiffness of antenna mem-branes and angles between adjacent ribs,are obtained.The analyses in the paper indicate that the effectsby disordered parameters can not be ignored in the dynamic analysis of such structures.展开更多
Localized nature of damage in structures requires local measurements for structural health monitoring. The local measurement means to measure the local, usually higher modes of the vibration in a structure. Three fund...Localized nature of damage in structures requires local measurements for structural health monitoring. The local measurement means to measure the local, usually higher modes of the vibration in a structure. Three fundamental issues about the local measurement for structural health monitoring including (1) the necessity of making local measurement, (2) the difficulty of making local measurement and (3) how to make local measurement are addressed in this paper. The results from both the analysis and the tests show that the local measurement can successfully monitor the structural health status as long as the local modes are excited. Unfortunately, the results also illustrate that it is difficult to excite local modes in a structure. Therefore, in order to carry structural health monitoring into effect, we must (1) ensure that the local modes are excited, and (2) deploy enough sensors in a structure so that the local modes can be monitored.展开更多
Stretching vibrational band intensities of XH3 (X=N, Sb) molecules are investigated employing three-dimensional dipole moment surfaces combined with the local mode Hamiltonian model. The dipole moment surfaces of NH...Stretching vibrational band intensities of XH3 (X=N, Sb) molecules are investigated employing three-dimensional dipole moment surfaces combined with the local mode Hamiltonian model. The dipole moment surfaces of NH3 and SbH3 are calculated with the density functional theory and at the correlated MP2 level, respectively. The calculated band intensities are in good agreement with the available experimental data. The contribution to the band intensities from the different terms in the polynomial expansion of the dipole moments of four group V hydrides (NH3, PH3, AsH3 and SbH3) are discussed. It is concluded that the breakdown of the bond dipole approximation must be considered. The intensity “borrowing” effect due to the wave function mixing among the stretching vibrational states is found to be less significant for the molecules that reach the local mode limit.展开更多
We have theoretically resolved phonon excitations in quasi-two-dimensional organic crystals of polyacenic semiconductor material which may be obtained by the pyrolytic treatment of phenol-formaldehyde resin. A model f...We have theoretically resolved phonon excitations in quasi-two-dimensional organic crystals of polyacenic semiconductor material which may be obtained by the pyrolytic treatment of phenol-formaldehyde resin. A model for studying the dynamical properties using three polyacene chains is proposed with the aim to present the vibrational properties of this structure. It employs the formalism of solid states in two dimensions which admit phonons. A simulation process of the two-dimensional lattice structure shows that elastic waves may explain the existence of vibrational modes in the frequency range 100-400 cm^-1. The presence of acoustic and optical like phonons is discussed in terms of the elastic force constants. A hyperfine resonance structure is obtained. It allows the analysis of the dynamical evolution in thin films of polyacene. It is found that the behavior of the phonon density of states exhibits resonance between modes in the structure.展开更多
The high confinement mode (H-mode) operation is recently obtained in HL-2A divertor configuration, the corresponding edge localized mode (ELM) is recognized as being of type III. Time intervals in ELM time series ...The high confinement mode (H-mode) operation is recently obtained in HL-2A divertor configuration, the corresponding edge localized mode (ELM) is recognized as being of type III. Time intervals in ELM time series are analysed to obtain the information about the ELM process. Signatures of unstable periodic orbits (UPOs) are detected, which are indicators of chaos and may be used to control the big ELM events.展开更多
基金National Natural Science Foundation of China Under Grant No. 50878010
文摘Reticulated shell structures (RSSs) are characterized as cyclically periodic structures. Mistuning of RSSs will induce structural mode localization. Mode localization has the following two features: some modal vectors of the structure change remarkably when the values of its physical parameters (mass or stiffness) have a slight change; and the vibration of some modes is mainly restricted in some local areas of the structure. In this paper, two quantitative assessment indexes are introduced that correspond to these two features. The first feature is studied through a numerical example of a RSS, and its induced causes are analyzed by using the perturbation theory. The analysis showed that internally, mode localization is closely related to structural frequencies and externally, slight changes of the physical parameters of the structure cause instability to the RSS. A scaled model experiment to examine mode localization was carried out on a Kiewit single-layer spherical RSS, and both features of mode localization are studied. Eight tests that measured the changes of the physical parameters were carried out in the experiment. Since many modes make their contribution in structural dynamic response, six strong vibration modes were tested at random in the experimental analysis. The change and localization of the six modes are analyzed for each test. The results show that slight changes to the physical parameters are likely to induce remarkable changes and localization of some modal vectors in the RSSs.
基金This work was partially supported by the NNSFC and the ASFC.
文摘According to the mapping theory in complex plane, the geometric features of eigen frequency loci of systems undergoing free vibrations are investigated. It is concluded that the phenomena of curve coalescence and veering can be described in a unified manner from the singularities of mapping from the complex parameter plane onto the complex frequency plane. The formation of a branch point in the parameter Space is the foundation of explaining localization and veering phenomena. By the use of condensation to reduce the dimension of a system, the scope of application of the geometric theory is widely expanded. The theory is applied to examples to verify the validity of the proposed approach. The present work is an improvement and extension of recent work by M. S. Traintafyllou et al..
基金Project supported by the Natural Science Foundation of Hunan Province, China (Grant No 03JJY6008).
文摘By use of the Hartree approximation and the method of multiple scales, we investigate quantum solitons and intrinsic localized modes in a one-dimensional antiferromagnetic chain. It is shown that there exist solitons of two different quantum frequency bands: i.e., magnetic optical solitons and acoustic solitons. At the boundary of the Brillouin zone, these solitons becornc quantum intrinsic localized modes: their quantum eigenfrequencics are below the bottom of the harmonic optical frequency band and above the top of the harmonic acoustic frequency band.
基金Project supported by the Key Project of Hunan Provincial Educational Department of China (Grant No 04A058)
文摘By means of the Glauber's coherent state method combined with multiple-scale method, this paper investigates the localized modes in a quantum one-dimensional Klein-Gordon chain and finds that the equation of motion of annihilation operator is reduced to the nonlinear Schroedinger equation. Interestingly, the model can support both bright and dark small amplitude travelling and non-travelling nonlinear localized modes in different parameter spaces.
基金The project supported by the Natural Science Foundation of Hunan Province of China under Grant No. 03JJY6008
文摘In the classical lattice theory, solitons and localized modes can exist in many one-dimensional nonlinear lattice chains, however, in the quantum lattice theory, whether quantum solitons and localized modes can exist or not in the one-dimensional lattice chains is an interesting problem. By using the number state method and the Hartree approximation combined with the method of multiple scales, we investigate quantum solirons and localized modes in a one-dimensional lattice chain with the nonlinear substrate potential. It is shown that quantum solitons do exist in this nonlinear lattice chain, and at the boundary of the phonon Brillouin zone, quantum solitons become quantum localized modes, phonons are pinned to the lattice of the vicinity at the central position j = j0.
基金This project is supported by National Natural Science Foundation of China (No.50205050).
文摘Based upon empirical mode decomposition (EMD) method and Hilbert spectrum, a method for fault diagnosis of roller bearing is proposed. The orthogonal wavelet bases are used to translate vibration signals of a roller bearing into time-scale representation, then, an envelope signal can be obtained by envelope spectrum analysis of wavelet coefficients of high scales. By applying EMD method and Hilbert transform to the envelope signal, we can get the local Hilbert marginal spectrum from which the faults in a roller bearing can be diagnosed and fault patterns can be identified. Practical vibration signals measured from roller bearings with out-race faults or inner-race faults are analyzed by the proposed method. The results show that the proposed method is superior to the traditional envelope spectrum method in extracting the fault characteristics of roller bearings.
文摘Intrinsic localized modes in an order-parameter-preserving antiferromagnet are investigated with employing the Dyson-Maleev transformation and the coherent-state ansatz. These modes which be- low the magnon frequency band correspond to a local large-angle, low-frequency precessional mo- tion of spins, quantum states of which are characterized by the indefiniteness of the number of rele- vant magnons.
基金Project supported by the National Key R&D Program of China(Grant Nos.2017YFE0300400 and 2017YFE0301300)the National Natural Science Foundation of China(Grant Nos.11475223 and 11775257)+1 种基金the National Magnetic Confinement Fusion Science Program of China(Grant No.2015GB101003)partly supported by AHNSF of China(Grant No.1808085J07)
文摘During edge localized modes(ELMs), the sheath evolution in front of the Experimental Advanced Superconducting Tokamak(EAST) upper divertor is studied to estimate the sputtered tungsten(W) atoms from the divertor target. A large potential drop across the sheath is formed during ELMs by compared with inter-ELMs, and the maximum of sheath potential drop can exceed one thousand of e V in current EAST operation. Due to the enhancement of the sheath potential drop during ELMs, the W physical sputtering yield from the deuterium(D) ions and the impurity ions on the upper divertor target is found to be significant. It is established that the sputtered W yield during ELMs is at least higher by an order of magnitude than inter-ELMs, and D ions and carbon(C) ions are the main ions governing the W production for the current H-mode with ELMs discharges. With increase in the pedestal electron temperature, the maximum of the D and C ion impact energy during ELMs shows a nearly linear increase, and the D ions have sufficient impact energy to cause the strong W physical sputtering. As a consequence, the D ions may dominate the sputtered W flux from the divertor target when the C concentration is controlled less than one percent for the higher heating power H-mode with ELM discharges in near future.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 40731056 and 10975012)the President Fund for Undergraduate Research of Peking University,China
文摘The effects of impurity on eigenmodes in one-dimensional dusty plasma lattices are studied. It is found that local modes can be excited besides lattice waves, due to the existence of an impurity particle. The dispersion relations of the modes are derived accordingly. Properties of the lattice and local modes are also analyzed and discussed, particularly for their symmetric features and conditions of the mode excitation.
文摘The local vibration mode(LVM)of carbon acceptor in GaAs is studied by measuring directly the change in LVM absorption with a NIC-170 SX FT-IR spectrometer.The change in the charge state of carbon acceptor and the temperature dependence of the LVM absorption were investigated also.The contents of the impurities other than carbon were estimated by secondary ion mass spectrometry.It is observed that the frequency,the spectral form and the integrated absorption of the LVM are not affected by the change in charge state of car- bon acceptor.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10875149 and 10805057)the National Magnetic Confinement Fusion Science Program of China (Grant No. 2010GB105004)
文摘H-mode discharges with lower hybrid current drive (LHCD) alone are achieved in EAST divertor plasma over a wide parameter range. These H-mode discharges are characterized by a sudden drop in Da emission and a spontaneous rise in main plasma density. Good lower hybrid (LH) coupling during H-mode is obtained by putting the plasma close to the antenna and by injecting D2 gas from a pipe near the grill mouse. The analysis of lower hybrid current drive properties shows that the LH deposition profile shifts off axis during H-mode, and current drive (CD) efficiency decreases due to the increase in density. Modeling results of H-mode discharges with a general ray trueing code GENRAY are reported.
文摘The local vibrational mode (LVM) optical absorption band of carbon acceptor was investigated carefully. Because of the appearance of a sideband on the low energy side of the LVM main absorption band, it is found that the measured value of the integrated area for the main absorption band is sensitive to the choice of integration baseline wavenumber range (BWR). This is the main cause that the experimental results from different investigators show a wide spread for the temperature dependence of the integrated area. The origin of the sideband is also discussed.
文摘As the basic level of national governance, local governance is deeply influenced by administrative tradition, political system and economic development level of a country. With more than thirty years of reform and opening up, the pattern of local governance has become diversified. The diversity of governance model cannot be managed in the same way, however, it cannot affect the government’s ability to play the initiative role of governance. We need to innovate and improve the existing local governance models.
文摘Structural dynamic problems encountered within launch vehicles are sometimes related to entire dynamic characteristics of the vehicle,and sometimes related to local dynamic characteristics of some parts of vehicles.To acquire local dynamic characteristics,it usually requires the building of a three-dimensional detailed FEM model.It is important that the simulation of mass and stiffness of local part is accurate.The local mode acquisition of a gas tank and its bracket installed in the inter-tank section is taken as an example in this paper.It can be seen that the local modes are consistent with the section modal test results.Finally,the verified three-dimensional detailed FEM model of the inter-tank section is assembled within the entire launch vehicle,and the local modes of the gas tank and its bracket under flight conditions are predicted.
基金This study was funded by the Urban Innovative Actions initiative(European Commission),under the research project UIA04-212 Energy Poverty Intelligence Unit(EPIU),the Spanish Ministry of Science and Innovation,under the research project PID2021-122437OA-I00“Positive Energy Buildings Potential for Climate Change Adaptation and Energy Poverty Mitigation(+ENERPOT)”the Andalusian Ministry of Development,Articulation of the Territory and Housing,under the research project US.22-02“Implicaciones en la mitigación del cambio climático y de la pobreza energética mediante nuevo modelo de confort adaptativo para viviendas sociales(ImplicAdapt)”.The authors also acknowledge the support provided by the Thematic Network 722RT0135“Red Iberoamericana de Pobreza Energética y Bienestar Ambiental(RIPEBA)”financed by the call for Thematic Networks of the CYTED Program for 2021.
文摘It has been found in recent years that using setpoint temperatures based on adaptive thermal comfort models is a successful method of energy conservation.Recent studies using adaptive setpoint temperatures incorporate international models from ASHRAE Standard 55 and EN16798-1.This study,however,has instead considered a regional Brazilian adaptive comfort model.This study investigates the energy demand arising from the use of a local Brazilian comfort model in order to assess the energy implications from the use of the worldwide ASHRAE Standard 55 adaptive model and various fixed setpoint temperatures.All of Brazil’s climate zones,full air-conditioning,mixed-mode building operating modes,present-day climate change scenarios,and future scenarios—specifically Representative Concentration Pathways(RCP)2.6,4.5,and 8.5 for the years 2050 and 2100—have all been taken into account in building energy simulations.The use of adaptive setpoint temperatures based on the Brazilian local model considering mixed-mode has been found to significantly reduce energy consumption when compared to static setpoint temperatures(average energy-saving values ranging from 52%to 58%)and the ASHRAE 55 adaptive model(average values ranging from 15%to 21%).Considering climate change and the mixed-mode Brazilian model,the overall energy demand for the three groups of climatic zones(annual average outdoor temperatures≤21℃,>21 and≤25℃and>25℃)ranged between 2%decrease and 5%increase,4%and 27%increase,and 13%and 45%increase,respectively.It is concluded as a consequence that setting setpoint temperatures based on the Brazilian local adaptive comfort model is a very efficient energy-saving method.
基金Supported by the Innovative Fund of China Aerospace Science and Technology Corporation (CASC0113)
文摘A simplified dynamic model of a dish antenna in satellite is established in this article.The modelcan be easily used to analyze the dynamic behaviour of the antenna structure.In terms of the simplifiedmodel,effects on dynamic characters due to the disorder of parameters are investigated in details.Thefrequencies calculated by the simplified model accord with those computed by ANSYS.Based on the modeshapes of disordered and perfect structure,the influence law and varying trend of dynamic characters ofantenna structures in satellites produced by stiffness and mass of antenna ribs,stiffness of antenna mem-branes and angles between adjacent ribs,are obtained.The analyses in the paper indicate that the effectsby disordered parameters can not be ignored in the dynamic analysis of such structures.
文摘Localized nature of damage in structures requires local measurements for structural health monitoring. The local measurement means to measure the local, usually higher modes of the vibration in a structure. Three fundamental issues about the local measurement for structural health monitoring including (1) the necessity of making local measurement, (2) the difficulty of making local measurement and (3) how to make local measurement are addressed in this paper. The results from both the analysis and the tests show that the local measurement can successfully monitor the structural health status as long as the local modes are excited. Unfortunately, the results also illustrate that it is difficult to excite local modes in a structure. Therefore, in order to carry structural health monitoring into effect, we must (1) ensure that the local modes are excited, and (2) deploy enough sensors in a structure so that the local modes can be monitored.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 20103007 and 20473079).
文摘Stretching vibrational band intensities of XH3 (X=N, Sb) molecules are investigated employing three-dimensional dipole moment surfaces combined with the local mode Hamiltonian model. The dipole moment surfaces of NH3 and SbH3 are calculated with the density functional theory and at the correlated MP2 level, respectively. The calculated band intensities are in good agreement with the available experimental data. The contribution to the band intensities from the different terms in the polynomial expansion of the dipole moments of four group V hydrides (NH3, PH3, AsH3 and SbH3) are discussed. It is concluded that the breakdown of the bond dipole approximation must be considered. The intensity “borrowing” effect due to the wave function mixing among the stretching vibrational states is found to be less significant for the molecules that reach the local mode limit.
文摘We have theoretically resolved phonon excitations in quasi-two-dimensional organic crystals of polyacenic semiconductor material which may be obtained by the pyrolytic treatment of phenol-formaldehyde resin. A model for studying the dynamical properties using three polyacene chains is proposed with the aim to present the vibrational properties of this structure. It employs the formalism of solid states in two dimensions which admit phonons. A simulation process of the two-dimensional lattice structure shows that elastic waves may explain the existence of vibrational modes in the frequency range 100-400 cm^-1. The presence of acoustic and optical like phonons is discussed in terms of the elastic force constants. A hyperfine resonance structure is obtained. It allows the analysis of the dynamical evolution in thin films of polyacene. It is found that the behavior of the phonon density of states exhibits resonance between modes in the structure.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10990213)
文摘The high confinement mode (H-mode) operation is recently obtained in HL-2A divertor configuration, the corresponding edge localized mode (ELM) is recognized as being of type III. Time intervals in ELM time series are analysed to obtain the information about the ELM process. Signatures of unstable periodic orbits (UPOs) are detected, which are indicators of chaos and may be used to control the big ELM events.