The precise characterization of hypersonic glide vehicle(HGV) maneuver laws in complex flight scenarios still faces challenges. Non-stationary changes in flight state due to abrupt changes in maneuver modes place high...The precise characterization of hypersonic glide vehicle(HGV) maneuver laws in complex flight scenarios still faces challenges. Non-stationary changes in flight state due to abrupt changes in maneuver modes place high demands on the accuracy of modeling methods. To address this issue, a novel maneuver laws modeling and analysis method based on higher order multi-resolution dynamic mode decomposition(HMDMD) is proposed in this work. A joint time-space-frequency decomposition of the vehicle's state sequence in the complex flight scenario is achieved with the higher order Koopman assumption and standard multi-resolution dynamic mode decomposition, and an approximate dynamic model is established. The maneuver laws can be reconstructed and analyzed with extracted multi-scale spatiotemporal modes with clear physical meaning. Based on the dynamic model of HGV, two flight scenarios are established with constant angle of attack and complex maneuver laws, respectively. Simulation results demonstrate that the maneuver laws obtained using the HMDMD method are highly consistent with those derived from the real dynamic model, the modeling accuracy is better than other common modeling methods, and the method has strong interpretability.展开更多
Higher Himalayan Crystalline (HHC) rocks often show metamorphic zonations from lower greenschist facies to migmatites associated with leucogranite intrusions that are classically described as examples of Tertiary inve...Higher Himalayan Crystalline (HHC) rocks often show metamorphic zonations from lower greenschist facies to migmatites associated with leucogranite intrusions that are classically described as examples of Tertiary inverted metamorphism. The present study, based on structural, petrological and geochronological investigations in the Kinnar Kailas Granite (KKG) and surrounding HHC sequence, evidences a discordant intrusive contact of the Ordovician KKG with respect to Pre\|Alpine high grade deformed HHC sequence in the Sutlej valley.Four main phases of deformation are recorded in this HHC sequence and pre\|Ordovician sediments. The first three phases of deformation occurred under high\|grade metamorphic conditions, before the intrusion of the KKG. The geometry of the main progressive ductile deformation (D2—D3) results from SW vergent doming and migmatisation. The latest deformation is expressed by local shearing under greenschist facies conditions. This late D4 deformation corresponds to N—S oriented ductile normal faults lowering the eastern blocks. The KKG is a shallow depth intrusion, showing discordant contacts with the surrounding basement rocks and large scale magmatic stoping. The KKG crosscuts the high\|grade deformation structures (D2—D3) but is locally affected by the local late D4 extensional deformation. The granite textures reflect only slight orientation related to magmatic deformation and even at few centimetres from the intrusion contact, the granite appears undeformed in contrast to the surrounding highly foliated rocks. Furthermore, xenoliths of Kyanite\|Sillimanite bearing basement rocks are present within the KKG.展开更多
This paper aims to examine the architecture design of a distributed antenna based Gbps wireless communication system using the high frequency band.In order to analyze the feasibility of the higher frequency band appli...This paper aims to examine the architecture design of a distributed antenna based Gbps wireless communication system using the high frequency band.In order to analyze the feasibility of the higher frequency band applications,the cumulative distribution of simulated user throughput in a cellular is investigated firstly.It shows that capacity improvement can be obtained using higher operating frequency band,especially in hotspot scenarios.Secondly,the architecture of the distributed antenna system(DAS) is introduced to overcome the disadvantages of weak coverage and rank deficient for the traditional multiple-input multiple-output(MIMO) systems using higher frequency bands in line-of-sight(LOS)environments.In addition,a software-defined-radio(SDR) based Gbps wireless transmission system with scalable hardware architecture is designed and implemented.Finally,a demo of outdoor DAS coverage for high data throughput application is given.Field trials show that 1 Gbps data rate and a large coverage in outdoor environments can be achieved over 6.05 GHz.It is proved that the Gbps DAS system at a higher frequency band can be a successful model for future wireless broadband coverage in hotspot scenarios.展开更多
This article deals with evaluating the frequency response of functionally graded carbon nanotube reinforced magneto-electro-elastic(FG-CNTMEE)plates subjected to open and closed electro-magnetic circuit conditions.In ...This article deals with evaluating the frequency response of functionally graded carbon nanotube reinforced magneto-electro-elastic(FG-CNTMEE)plates subjected to open and closed electro-magnetic circuit conditions.In this regard finite element formulation has been derived.The plate kinematics adjudged via higher order shear deformation theory(HSDT)is considered for evaluation.The equations of motion are obtained with the help of Hamilton’s principle and solved using condensation technique.It is found that the convergence and accuracy of the present FE formulation is very good to address the vibration problem of FG-CNTMEE plate.For the first time,frequency response analysis of FG-CNTMEE plates considering the effect of various circuit conditions associated with parameters such as CNT distributions,volume fraction,skew angle,aspect ratio,length-to-thickness ratio and coupling fields has been carried out.The results of this article can serve as benchmark for future development and analysis of smart structures.展开更多
The higher order displacement discontinuity method(HODDM) utilizing special crack tip elements has been used in the solution of linear elastic fracture mechanics(LEFM) problems. The paper has selected several example ...The higher order displacement discontinuity method(HODDM) utilizing special crack tip elements has been used in the solution of linear elastic fracture mechanics(LEFM) problems. The paper has selected several example problems from the fracture mechanics literature(with available analytical solutions) including center slant crack in an infinite and finite body, single and double edge cracks, cracks emanating from a circular hole. The numerical values of Mode Ⅰ and Mode Ⅱ SIFs for these problems using HODDM are in excellent agreement with analytical results(reaching up to 0.001% deviation from their analytical results). The HODDM is also compared with the XFEM and a modified XFEM results. The results show that the HODDM needs a considerably lower computational effort(with less than 400 nodes) than the XFEM and the modified XFEM(which needs more than 10000 nodes) to reach a much higher accuracy. The proposed HODDM offers higher accuracy and lower computation effort for a wide range of problems in LEFM.展开更多
This article deals with investigating the effect of cut-outs on the natural frequencies of magneto-electroelastic(MEE)plates incorporating finite element methods based on higher order shear deformation theory(HSDT).In...This article deals with investigating the effect of cut-outs on the natural frequencies of magneto-electroelastic(MEE)plates incorporating finite element methods based on higher order shear deformation theory(HSDT).In order to consider the influence of cut-out,the energy of the cut-out domain is subtracted from the total energy of the entire plate.The governing equations of motions are derived through incorporating Hamilton’s principle and the solution is obtained using condensation technique.The proposed numerical formulation is verified with the results of previously published literature as well as the numerical software.In addition,this research focuses on evaluating the effect of geometrical skewness and boundary conditions on the frequency response.The influence of cut-outs on the degree of coupling between magnetic,electric and elastic fields is also investigated.展开更多
An unsplit-field higher order nearly perfectly matched layer(NPML)based on the auxiliary differential equation approach is introduced in three-dimensional finite-difference timedomain lattices.The proposed scheme has ...An unsplit-field higher order nearly perfectly matched layer(NPML)based on the auxiliary differential equation approach is introduced in three-dimensional finite-difference timedomain lattices.The proposed scheme has the advantage of both the NPML scheme and the higher order concept in terms of the improved absorbing performance and considerable computational efficiency.By incorporating with the generalized material independent concept,the proposed implementation is indepen dent of the material’s type.Thus,it has the advantages of terminating arbitrary media without changing the updated equations in the PML regions.Its effectiveness and efficiency is further demonstrated through numerical examples.展开更多
Higher order spectral analysis can be used to identify nonlinearities in the complex dynamical systems.This proposal shows that the contributions of the bispectrum,trispectrum,reconstructed bispectrum and reconstructe...Higher order spectral analysis can be used to identify nonlinearities in the complex dynamical systems.This proposal shows that the contributions of the bispectrum,trispectrum,reconstructed bispectrum and reconstructed power spectrum in terms of the system frequency response function and elementary physical properties of the MR damping system.Subsequent estimates of the HOS based on the output stochastic oscillating signals appear distinct variation.An experimental platform for MR vibrating semi-active control is built,proper simplifications are presented,an AR(10) model is established with colored noises from the output signals.Comparison between power spectrum from second order moment function and bispectrum,trispectrum are taken.The later gives an indication of the correlation between the phases of different frequency components.Since time series model is a parametric model,the reconstructed bispectrum and power spectrum are smooth.It is demonstrated that the higher order spectra are effectively for recognition and description of nonlinear systems.展开更多
A generalized form of material gradation applicable to a more broad range of functionally graded materials(FGMs) was presented.With the material model,analytical expressions of crack tip higher order stress fields in ...A generalized form of material gradation applicable to a more broad range of functionally graded materials(FGMs) was presented.With the material model,analytical expressions of crack tip higher order stress fields in a series form for opening mode and shear mode cracks under quasi-static loading were developed through the approach of asymptotic analysis.Then,a numerical experiment was conducted to verify the accuracy of the developed expressions for representing crack tip stress fields and their validity in full field data analysis by using them to extract the stress intensity factors from the results of a finite element analysis by local collocation and then comparing the estimations with the existing solution.The expressions show that nonhomogeneity parameters are embedded in the angular functions associated with higher terms in a recursive manner and at least the first three terms in the expansions must be considered to explicitly account for material nonhomogeneity effects on crack tip stress fields in the case of FGMs.The numerical experiment further confirms that the addition of the nonhomogeneity specific terms in the expressions not only improves estimates of stress intensity factor,but also gives consistent estimates as the distance away from the crack tip increases.Hence,the analytical expressions are suitable for the representation of crack tip stress fields and the analysis of full field data.展开更多
Globalization is not the same as internationalization. Globalization creates a global environment for academic trends in the 21st century. Internationalization includes the practices conducted by academic institutions...Globalization is not the same as internationalization. Globalization creates a global environment for academic trends in the 21st century. Internationalization includes the practices conducted by academic institutions and leads the universities to enter international market. This article starts to examine the inter- relationship between globalization and internationalization,and then move on to a detailed analysis of the impact of globalization and internationalization on Australian higher education. Finally,after exploring the realities of Australian higher education,it is suggested that in order to obtain and maintain competitive advantages in a new globalizing market,mutual efforts by the government and universities are indispensible.展开更多
With the effective measure of curriculum maturity,curriculum development of higher education makes a breakthrough in the bottleneck period,ultimately providing an external driving force for the effective study on subs...With the effective measure of curriculum maturity,curriculum development of higher education makes a breakthrough in the bottleneck period,ultimately providing an external driving force for the effective study on substance of quality evaluation system in the development of higher education curriculum.The research shows that the development of higher education curriculum should make a comprehensive analysis of quality evaluation by following the principle of sustainability,which encourages the quality-oriented innovation of higher education curriculum,thus forming a substantive breakthrough in curriculum development.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 12302056)the Postdoctoral Fellowship Program of CPSF:GZC20233445。
文摘The precise characterization of hypersonic glide vehicle(HGV) maneuver laws in complex flight scenarios still faces challenges. Non-stationary changes in flight state due to abrupt changes in maneuver modes place high demands on the accuracy of modeling methods. To address this issue, a novel maneuver laws modeling and analysis method based on higher order multi-resolution dynamic mode decomposition(HMDMD) is proposed in this work. A joint time-space-frequency decomposition of the vehicle's state sequence in the complex flight scenario is achieved with the higher order Koopman assumption and standard multi-resolution dynamic mode decomposition, and an approximate dynamic model is established. The maneuver laws can be reconstructed and analyzed with extracted multi-scale spatiotemporal modes with clear physical meaning. Based on the dynamic model of HGV, two flight scenarios are established with constant angle of attack and complex maneuver laws, respectively. Simulation results demonstrate that the maneuver laws obtained using the HMDMD method are highly consistent with those derived from the real dynamic model, the modeling accuracy is better than other common modeling methods, and the method has strong interpretability.
文摘Higher Himalayan Crystalline (HHC) rocks often show metamorphic zonations from lower greenschist facies to migmatites associated with leucogranite intrusions that are classically described as examples of Tertiary inverted metamorphism. The present study, based on structural, petrological and geochronological investigations in the Kinnar Kailas Granite (KKG) and surrounding HHC sequence, evidences a discordant intrusive contact of the Ordovician KKG with respect to Pre\|Alpine high grade deformed HHC sequence in the Sutlej valley.Four main phases of deformation are recorded in this HHC sequence and pre\|Ordovician sediments. The first three phases of deformation occurred under high\|grade metamorphic conditions, before the intrusion of the KKG. The geometry of the main progressive ductile deformation (D2—D3) results from SW vergent doming and migmatisation. The latest deformation is expressed by local shearing under greenschist facies conditions. This late D4 deformation corresponds to N—S oriented ductile normal faults lowering the eastern blocks. The KKG is a shallow depth intrusion, showing discordant contacts with the surrounding basement rocks and large scale magmatic stoping. The KKG crosscuts the high\|grade deformation structures (D2—D3) but is locally affected by the local late D4 extensional deformation. The granite textures reflect only slight orientation related to magmatic deformation and even at few centimetres from the intrusion contact, the granite appears undeformed in contrast to the surrounding highly foliated rocks. Furthermore, xenoliths of Kyanite\|Sillimanite bearing basement rocks are present within the KKG.
基金supported in part by the National Natural Science Foundation of China(No.61402044)863 plan program of China(No.2015AA01 A706)+2 种基金Science Foundation of Beijing Education Commission(No.KM201511232011)Science Fundation of Beijing Information Science & Technology University(No.5211524100)Beijing Nova Program(No.Z161100004916086)
文摘This paper aims to examine the architecture design of a distributed antenna based Gbps wireless communication system using the high frequency band.In order to analyze the feasibility of the higher frequency band applications,the cumulative distribution of simulated user throughput in a cellular is investigated firstly.It shows that capacity improvement can be obtained using higher operating frequency band,especially in hotspot scenarios.Secondly,the architecture of the distributed antenna system(DAS) is introduced to overcome the disadvantages of weak coverage and rank deficient for the traditional multiple-input multiple-output(MIMO) systems using higher frequency bands in line-of-sight(LOS)environments.In addition,a software-defined-radio(SDR) based Gbps wireless transmission system with scalable hardware architecture is designed and implemented.Finally,a demo of outdoor DAS coverage for high data throughput application is given.Field trials show that 1 Gbps data rate and a large coverage in outdoor environments can be achieved over 6.05 GHz.It is proved that the Gbps DAS system at a higher frequency band can be a successful model for future wireless broadband coverage in hotspot scenarios.
文摘This article deals with evaluating the frequency response of functionally graded carbon nanotube reinforced magneto-electro-elastic(FG-CNTMEE)plates subjected to open and closed electro-magnetic circuit conditions.In this regard finite element formulation has been derived.The plate kinematics adjudged via higher order shear deformation theory(HSDT)is considered for evaluation.The equations of motion are obtained with the help of Hamilton’s principle and solved using condensation technique.It is found that the convergence and accuracy of the present FE formulation is very good to address the vibration problem of FG-CNTMEE plate.For the first time,frequency response analysis of FG-CNTMEE plates considering the effect of various circuit conditions associated with parameters such as CNT distributions,volume fraction,skew angle,aspect ratio,length-to-thickness ratio and coupling fields has been carried out.The results of this article can serve as benchmark for future development and analysis of smart structures.
文摘The higher order displacement discontinuity method(HODDM) utilizing special crack tip elements has been used in the solution of linear elastic fracture mechanics(LEFM) problems. The paper has selected several example problems from the fracture mechanics literature(with available analytical solutions) including center slant crack in an infinite and finite body, single and double edge cracks, cracks emanating from a circular hole. The numerical values of Mode Ⅰ and Mode Ⅱ SIFs for these problems using HODDM are in excellent agreement with analytical results(reaching up to 0.001% deviation from their analytical results). The HODDM is also compared with the XFEM and a modified XFEM results. The results show that the HODDM needs a considerably lower computational effort(with less than 400 nodes) than the XFEM and the modified XFEM(which needs more than 10000 nodes) to reach a much higher accuracy. The proposed HODDM offers higher accuracy and lower computation effort for a wide range of problems in LEFM.
文摘This article deals with investigating the effect of cut-outs on the natural frequencies of magneto-electroelastic(MEE)plates incorporating finite element methods based on higher order shear deformation theory(HSDT).In order to consider the influence of cut-out,the energy of the cut-out domain is subtracted from the total energy of the entire plate.The governing equations of motions are derived through incorporating Hamilton’s principle and the solution is obtained using condensation technique.The proposed numerical formulation is verified with the results of previously published literature as well as the numerical software.In addition,this research focuses on evaluating the effect of geometrical skewness and boundary conditions on the frequency response.The influence of cut-outs on the degree of coupling between magnetic,electric and elastic fields is also investigated.
基金This work was supported by the National Natural Science Foundation of China(6157102261971022).
文摘An unsplit-field higher order nearly perfectly matched layer(NPML)based on the auxiliary differential equation approach is introduced in three-dimensional finite-difference timedomain lattices.The proposed scheme has the advantage of both the NPML scheme and the higher order concept in terms of the improved absorbing performance and considerable computational efficiency.By incorporating with the generalized material independent concept,the proposed implementation is indepen dent of the material’s type.Thus,it has the advantages of terminating arbitrary media without changing the updated equations in the PML regions.Its effectiveness and efficiency is further demonstrated through numerical examples.
基金Project(A0610020) supported by the Natural Science of Fujian Province of China
文摘Higher order spectral analysis can be used to identify nonlinearities in the complex dynamical systems.This proposal shows that the contributions of the bispectrum,trispectrum,reconstructed bispectrum and reconstructed power spectrum in terms of the system frequency response function and elementary physical properties of the MR damping system.Subsequent estimates of the HOS based on the output stochastic oscillating signals appear distinct variation.An experimental platform for MR vibrating semi-active control is built,proper simplifications are presented,an AR(10) model is established with colored noises from the output signals.Comparison between power spectrum from second order moment function and bispectrum,trispectrum are taken.The later gives an indication of the correlation between the phases of different frequency components.Since time series model is a parametric model,the reconstructed bispectrum and power spectrum are smooth.It is demonstrated that the higher order spectra are effectively for recognition and description of nonlinear systems.
基金Project(20080431344) supported by Postdoctoral Science Foundation of ChinaProject(51021001) supported by the National Natural Science Foundation of China
文摘A generalized form of material gradation applicable to a more broad range of functionally graded materials(FGMs) was presented.With the material model,analytical expressions of crack tip higher order stress fields in a series form for opening mode and shear mode cracks under quasi-static loading were developed through the approach of asymptotic analysis.Then,a numerical experiment was conducted to verify the accuracy of the developed expressions for representing crack tip stress fields and their validity in full field data analysis by using them to extract the stress intensity factors from the results of a finite element analysis by local collocation and then comparing the estimations with the existing solution.The expressions show that nonhomogeneity parameters are embedded in the angular functions associated with higher terms in a recursive manner and at least the first three terms in the expansions must be considered to explicitly account for material nonhomogeneity effects on crack tip stress fields in the case of FGMs.The numerical experiment further confirms that the addition of the nonhomogeneity specific terms in the expressions not only improves estimates of stress intensity factor,but also gives consistent estimates as the distance away from the crack tip increases.Hence,the analytical expressions are suitable for the representation of crack tip stress fields and the analysis of full field data.
文摘Globalization is not the same as internationalization. Globalization creates a global environment for academic trends in the 21st century. Internationalization includes the practices conducted by academic institutions and leads the universities to enter international market. This article starts to examine the inter- relationship between globalization and internationalization,and then move on to a detailed analysis of the impact of globalization and internationalization on Australian higher education. Finally,after exploring the realities of Australian higher education,it is suggested that in order to obtain and maintain competitive advantages in a new globalizing market,mutual efforts by the government and universities are indispensible.
基金a staged achievement of Jiangsu regulated research project of education science,entitled“The Reform of College English Teaching with the Cultivation of‘Outstanding Engineering Talents’as the Core in Engineering Universities”(Y-b/2011/01)
文摘With the effective measure of curriculum maturity,curriculum development of higher education makes a breakthrough in the bottleneck period,ultimately providing an external driving force for the effective study on substance of quality evaluation system in the development of higher education curriculum.The research shows that the development of higher education curriculum should make a comprehensive analysis of quality evaluation by following the principle of sustainability,which encourages the quality-oriented innovation of higher education curriculum,thus forming a substantive breakthrough in curriculum development.
