This article introduces the design theory of ceramic waveguide filter and proposes a new type of negative coupling structure with a conical throughhole,which has fine-adjustment of negative coupling without significan...This article introduces the design theory of ceramic waveguide filter and proposes a new type of negative coupling structure with a conical throughhole,which has fine-adjustment of negative coupling without significantly increasing the insertion loss of the filter.Based on this,the article proposes an eightcavity ceramic waveguide filter design for 5G base stations.It also presents a detailed discussion on the influence of the cross-coupling slot lengths L2 and L4 on the transmission zeros positions during the filter optimization process and the relevant change rules.For the proposed optimized filter,the observed performance indicators include the center frequency of 3.5 GHz,working bandwidth of 200 MHz,an insertion loss of≤2.0 dB,return loss of≥19 dB,and out-of-band nearend suppression and out-of-band far-end suppression of≥39 dB and≥63 dB,respectively.The test performance results obtained for the sample,with structural parameters as per the simulation model,were in good agreement with the simulation results.展开更多
Photoluminescence(PL)was investigated as functions of the excitation intensity and temperature for a coupling surface quantum dots(SQDs)structure which consists of one In_(0.3)Ga_(0.7)As SQDs layer being stacked on mu...Photoluminescence(PL)was investigated as functions of the excitation intensity and temperature for a coupling surface quantum dots(SQDs)structure which consists of one In_(0.3)Ga_(0.7)As SQDs layer being stacked on multi-layers of In_(0.3)Ga_(0.7)As buried quantum dots(BQDs).Accompanied by considering the localized excitons effect induced by interface fluctuation,carrier transition between BQDs and SQDs were analyzed carefully.The PL measurements confirm that there is a strong carrier transition from BQDs to SQDs and this transition leads to obvious different PL characteristics between BQDs and SQDs.These results are useful for future application of SQDs as surface sensitive sensors.展开更多
Ladybirds(Coccinella septempunctata)are adept at living in humid conditions as their elytra can effectively shield their bodies from raindrops.However,due to technical difficulties in examining the delicate structure,...Ladybirds(Coccinella septempunctata)are adept at living in humid conditions as their elytra can effectively shield their bodies from raindrops.However,due to technical difficulties in examining the delicate structure,the understanding of the water-proofing mechanism of the coupling structure and its impact on the dome-like elytra response to the raindrops remain elusive.In this combined experimental and theoretical study,we showed that the coupling structure on the ladybird elytra can ward off the raindrops traveling at a velocity of 6 m/s,which generates an impact force equivalent to 600 times the body weight.The waterproofing mechanism relies on the deformability of the elytra and their microstructures,which collectively impedes the formation of microchannels for liquids.The enhanced water-proofing capabilities enabled by the coupling structures are validated through experimental testing on comparative 3D-printed models,showing the effectiveness of these structures in improving water resistance.Subsequently,we showcased a water-proofing device,which substantially improved the efficiency of solar panels in converting solar energy.This multidisciplinary study not only advances our understanding of the biomechanics of coupling systems in insects but also inspires the design of water-proofing deployable structures.展开更多
The air valve is the core component of the cyclic operation of the compressor cylinder,and its structure and performance largely determine whether the reciprocating compressor can operate more efficiently and economic...The air valve is the core component of the cyclic operation of the compressor cylinder,and its structure and performance largely determine whether the reciprocating compressor can operate more efficiently and economically.On the basis of analyzing the basic structure and working principle of the air valve,this article mainly studies the motion characteristics of the suction valve plate.Based on fluid structure coupling mechanics and using ADINA software as a platform,numerical simulation analysis was conducted on the suction valve of a certain compressor model.Studying the stress of the valve plate and the variation of its upper and lower surface pressure with the opening and closing of the valve plate during the suction process of the compressor provides theoretical guidance for the rationality of the design of the air valve and related components,thereby improving the service life of the air valve and the working efficiency of the compressor.展开更多
A broadband transducer with tube-beam coupling structure is presented. Flexural beams are put into a traditional segmented ring transducer including inactive portions to form a new tube-beam coupling structure with mo...A broadband transducer with tube-beam coupling structure is presented. Flexural beams are put into a traditional segmented ring transducer including inactive portions to form a new tube-beam coupling structure with more useful working modes. Using multiple-mode- coupling design technique, the bandwidth of transducer could be expanded efficiently towards low frequency range. The optimization study of the electroacoustic parameters is carried out by finite element analysis at first. Then a prototype is manufactured and measured. It is shown that this projector combines the fine qualities of flextensional transducer with those of circular ring transducer by both the simulated and experimental results. It could achieve low frequency, high power and wide band performance from compact size. In addition, it is suitable for deep submergence operation when using free-flooded design.展开更多
For understanding the possible deep-seated processes and geodynamic constrains on gold mineralization, comprehensive physicochemical and geochemical studies of gold mineralization have been undertaken within the paleo...For understanding the possible deep-seated processes and geodynamic constrains on gold mineralization, comprehensive physicochemical and geochemical studies of gold mineralization have been undertaken within the paleo-lithosphere framework during the metailogenic epoch from the northwestern part of the Jiaodong Peninsula in this paper. A general image of the paleo-crust has been remained although it has been superimposed and reformed by post-metailogenic tectonic movements. The gold ore deposits occur usually in local uplifts and gradient belts featuring a turn from steep to gentle in granite-metamorphic contact zones, relative uplifts of gradient zones of the Curier isothermal interfaces, depressions of the Moho discontinuity and areas where depth contours are cut by isotherms perpendicularly. Gold mineralization and lithogenesis are characterized by high temperature, low pressure and high strength of thermal flux. The depth of mineralization ranges from 0.8 to 4.5 km. The depth of the top interface of the granitic complex in the metallogenic epoch is about 3 km. There is a low-velocity layer （LVL） at the bottom of the upper crust with a depth close to 19.5 km, which may be a detachment belt in the crust. The appearance of the LVL indicates the existence of paleo-hyperthermal fluid or relics of molten magma chambers, which reflects partial melting within the crust during the diagenetic and metallogenic epochs and the superposition effects of strike-slip shearing of the Taulu fault zone. The subsidence of the Moho is probably attributed to the coupling process of the NW-SE continental collision between North China and the Yangtze Block and the strike-slip movement of the Tanlu fault accompanied with underplating of mantle magma in the northwestern part of the Jiaodong Peninsula. The underplating of mantle magma may result in partial melting and make granite magma transfer upwards. This is favorable for the migration of metallogenic materials from deep to shallow to be enriched to form deposits. Coupling interactions between the strike-slip of the Taulu fault, the underplating of mantle magma, partial melting within the crust, and hyperthermal fluid, etc. may be the important factors controlling the gold mineralization and spatial structures in the metailogenic system.展开更多
The dynamic characteristics of a single liquid-filled pipe have been broadly studied in the previous literature.The parallel liquid-filled pipe(PLFP)system is also widely used in engineering,and its structure is more ...The dynamic characteristics of a single liquid-filled pipe have been broadly studied in the previous literature.The parallel liquid-filled pipe(PLFP)system is also widely used in engineering,and its structure is more complex than that of a single pipe.However,there are few reports about the dynamic characteristics of the PLFPs.Therefore,this paper proposes improved frequency modeling and solution for the PLFPs,involving the logical alignment principle and coupled matrix processing.The established model incorporates both the fluid-structure interaction(FSI)and the structural coupling of the PLFPs.The validity of the established model is verified by modal experiments.The effects of some unique parameters on the dynamic characteristics of the PLFPs are discussed.This work provides a feasible method for solving the FSI of multiple pipes in parallel and potential theoretical guidance for the dynamic analysis of the PLFPs in engineering.展开更多
This work presents a numerical investigation of the thermal–fluid–structure coupling behavior of the liquid natural gas(LNG)transported in the flexible corrugated cryogenic hose.A three-dimensional model of the corr...This work presents a numerical investigation of the thermal–fluid–structure coupling behavior of the liquid natural gas(LNG)transported in the flexible corrugated cryogenic hose.A three-dimensional model of the corrugated hose structure composed of multiple layers of different materials is established and coupled with turbulent LNG flow and heat transfer models in the commercial software ANSYS Workbench.The flow transport behavior,heat transfer across the hose layers,and structural response caused by the flow are analyzed.Parametric studies are performed to evaluate the impacts of inlet flow rate and thermal conductivity of insulation material on the temperature and structural stress of the corrugated hose.The study found that,compared with a regular operating condition,higher inlet flow velocities not only suppress the heat gain of the LNG but also lower the flow-induced structural stress.The insulation layer exhibits excellent performance in maintaining the temperature at the fluid–structure interface,showing little temperature change with respect to material thermal conductivity and ambient temperature.The simulation results may contribute to the research and design of the flexible corrugated cryogenic hoses and provide guidance for safer and more efficient field operations.展开更多
In the light of results from study on coupling between deep and shallow structures in Xingtai earthquake area during the 'Ninth Five-Year Plan' period and other previous results from deep seismic refraction/re...In the light of results from study on coupling between deep and shallow structures in Xingtai earthquake area during the 'Ninth Five-Year Plan' period and other previous results from deep seismic refraction/reflection and seismic prospecting of petroleum, we infer that there exist a series of shallow faults in the upper crust above the 8 km-deep detachment surface in Xingtai macroseismic focal region, where none of the faults, including Aixinzhuang fault reaches the Quaternary stratum, except that the Xinhe fault cuts through the mid-Pleistocene formation upwards. Aixinzhuang fault and other faults extend downwards into Xinhe fault whereas the Xinhe listric fault stretches downwards at a low dip angle into the detachment surface. The abyssal fault with high dip angle under the detachment surface cutting through the middle and lower crust to Moho is the causative fault for the large Xingtai earthquake, whose dislocation can cause strong earthquakes, shallow fault activity and the motion of surface material. The shallow faults in the upper crust are not causative faults for strong earthquakes, although they may be active faults. The existence of the detachment surface brings about a special relationship between shallow and deep structures, i.e. they are relatively independent of each other and have effects on each other It not only transmits partial energy and deformation between the upper and lower crust,but also has a certain decoupling effect. Finally we conclude that active faults do not necessarily reach the latest stratum, and the age of uppermost faulted stratum cannot represent the latest active period of the fault. This put to us a significant question in regard to the age determination and study of active faults. Other noticeable questions are also inferred to in this study.展开更多
Conventional coupled BE/FE （Boundary-Element/Finite-Element） method and modeling of structural-acoustic interaction has shown its promise and potential in the design and analysis of various structural-acoustic inter...Conventional coupled BE/FE （Boundary-Element/Finite-Element） method and modeling of structural-acoustic interaction has shown its promise and potential in the design and analysis of various structural-acoustic interaction applications. Unified combined acoustic and aerodynamic loading on the structure is synthesized using two approaches. Firstly, by linear superposition of the acoustic pressure disturbance to the aeroelastic problem, the effect of acoustic pressure disturbance to the aeroelastic structure is considered to consist of structural motion independent incident acoustic pressure and structural motion dependent acoustic pressure, which is known as the scattering pressure, referred here as the acoustic aerodynamic analogy. Secondly, by synthesizing the acoustic and aerodynamic effects on elastic structure using an elegant, effective and unified approach, both acoustic and aerodynamic effect on solid structural boundaries can be formulated as a boundary value problem governed by second order differential equations which lead to solutions expressible as surface integral equations. The unified formulation of the acousto-aeroelastic problem is amenable for simultaneous solution, although certain prevailing situations allow the solution of the equations independently. For this purpose, the unsteady aerodynamic problem which was earlier utilizes well-established lifting surface method is reformulated using Boundary Element （BE） approach. These schemes are outlined and worked out with examples.展开更多
The coupling behavior of the imbedded weapon store occurring between the local unsteady flow field round the store and the structure response on the processing of opening its bay-door is simulated by using numerical m...The coupling behavior of the imbedded weapon store occurring between the local unsteady flow field round the store and the structure response on the processing of opening its bay-door is simulated by using numerical method based on computational fluid mechanics(CFD).The transient aerodynamic behaviors when opening door under various flight altitudes and the corresponding structure deformation evolution in the unsteady flow fields are analyzed respectively and presented.The rules of aircraft attitude parameters′impacting to the responses of structure and the bay-door′s opening process are obtained by comparing with the analysis results.These rules can be applied to the structure design of bay-door and route specification of missile when disengaged and launched from within store.展开更多
In this paper, the isogeometric analysis (IGA) is employed to develop an acoustic radiation model for a double plate-acoustic cavity coupling system, with a focus on analyzing the sound transmission loss (STL). The fu...In this paper, the isogeometric analysis (IGA) is employed to develop an acoustic radiation model for a double plate-acoustic cavity coupling system, with a focus on analyzing the sound transmission loss (STL). The functionally graded (FG) plate exhibits a different material properties in-plane, and the power-law rule is adopted as the governing principle for material mixing. To validate the harmonic response and demonstrate the accuracy and convergence of the isogeometric modeling, ANASYS is utilized to compare with numerical examples. A plane wave serves as the acoustic excitation, and the Rayleigh integral is applied to discretize the radiated plate. The STL results are compared with the literature, confirming the reliability of the coupling system. Finally, the investigation is conducted to study impact of cavity depth and power-law parameter on the STL.展开更多
The microstrip dual-mode filter （DMF） with conventional coupling structure has some limitations in- eluding the port coupling strength limited by fabrication tolerance and the existence of serious second order spuri...The microstrip dual-mode filter （DMF） with conventional coupling structure has some limitations in- eluding the port coupling strength limited by fabrication tolerance and the existence of serious second order spuri- ous band. Therefore, a novel DMF with a offset-feed bended coupling structure and a stepped-impedance dual- mode resonator is proposed for coupling enhancement and spurious response suppression. Based on the analysis of the change of spur frequencies and the current distribution of spur resonant modes, all spurs near passband of the cascaded DMF can be fully suppressed by optimizing the structure parameters of parasite resonators, which bene- fits from the inherent well-controlled transmission zeros. Experimental results show that the proposed DMF ex- hibits lower insertion loss ,much sharper rate of cutoff and wider spur-free stop band compared with conventional DMF. This design is applicable for spur suppression in wideband communication.展开更多
Detecting coupling pattern between elements in a complex system is a basic task in data-driven analysis. The trajectory for each specific element is a cooperative result of its intrinsic dynamic, its couplings with ot...Detecting coupling pattern between elements in a complex system is a basic task in data-driven analysis. The trajectory for each specific element is a cooperative result of its intrinsic dynamic, its couplings with other elements, and the environment. It is subsequently composed of many components, only some of which take part in the couplings. In this paper we present a framework to detect the component correlation pattern. Firstly, the interested trajectories are decomposed into components by using decomposing methods such as the Fourier expansion and the Wavelet transformation. Secondly, the cross-correlations between the components are calculated, resulting into a component cross-correlation matrix(network).Finally, the dominant structure in the network is identified to characterize the coupling pattern in the system. Several deterministic dynamical models turn out to be characterized with rich structures such as the clustering of the components. The pattern of correlation between respiratory(RESP) and ECG signals is composed of five sub-clusters that are mainly formed by the components in ECG signal. Interestingly, only 7 components from RESP(scattered in four sub-clusters) take part in the realization of coupling between the two signals.展开更多
The design of counter-rotating turbine is one of new techniques to improve the thrust-weight ratio of jet propulsion engines.Numerical analysis of a low pressure（LP）counter-rotating turbine rotor blade is presented ...The design of counter-rotating turbine is one of new techniques to improve the thrust-weight ratio of jet propulsion engines.Numerical analysis of a low pressure（LP）counter-rotating turbine rotor blade is presented by using ANSYS/CFX software.Interaction of aerodynamics and solid mechanics coupling in the computation is applied.In some rating of turbine,stress distribution and vibration characteristics of low pressure turbine（LPT）blade are computed.The wake aerodynamic forces and LPT blade vibration are transformed in frequency domain using fast Fourier transform（FFT）method.The results show that under wake aerodynamic force excitation,the first order modal vibration is more easily aroused and the higher order response cannot be ignored.Moreover,with different temperature fields,the vibration responses of blade are also different.展开更多
The structure and the acoustic medium of a passenger vehicle are modeled using the finite element method(FEM), and the interior noise is studied the help of the modal synthesis method (MSM). Sound pressure level (Lp) ...The structure and the acoustic medium of a passenger vehicle are modeled using the finite element method(FEM), and the interior noise is studied the help of the modal synthesis method (MSM). Sound pressure level (Lp) of the noise is calculated in several conditions of the models, and has good agreements with its test results. The MSM am be consequently used for predicting the vehicle interior noise in dssign stage so that the structure may be optimized for the Purpose of the most reduction of noise.展开更多
Through the Galerkin method the nonlinear ordinary differential equations （ODEs） in time are obtained from the nonlinear partial differential equations （PDEs） to describe the mo- tion of the coupled structure of a...Through the Galerkin method the nonlinear ordinary differential equations （ODEs） in time are obtained from the nonlinear partial differential equations （PDEs） to describe the mo- tion of the coupled structure of a suspended-cable-stayed beam. In the PDEs, the curvature of main cables and the deformation of cable stays are taken into account. The dynamics of the struc- ture is investigated based on the ODEs when the structure is subjected to a harmonic excitation in the presence of both high-frequency principle resonance and 1：2 internal resonance. It is found that there are typical jumps and saturation phenomena of the vibration amplitude in the struc- ture. And the structure may present quasi-periodic vibration or chaos, if the stiffness of the cable stays membrane and frequency of external excitation are disturbed.展开更多
Subcortical vascular mild cognitive impairment(svMCI)is a common prodromal stage of vascular dementia.Although mounting evidence has suggested abnormalities in several single brain network metrics,few studies have exp...Subcortical vascular mild cognitive impairment(svMCI)is a common prodromal stage of vascular dementia.Although mounting evidence has suggested abnormalities in several single brain network metrics,few studies have explored the consistency between functional and structural connectivity networks in svMCI.Here,we constructed such networks using resting-state f MRI for functional connectivity and diffusion tensor imaging for structural connectivity in 30 patients with svMCI and 30 normal controls.The functional networks were then parcellated into topological modules,corresponding to several well-defined functional domains.The coupling between the functional and structural networks was finally estimated and compared at the multiscale network level(whole brain and modular level).We found no significant intergroup differences in the functional–structural coupling within the whole brain;however,there was significantly increased functional–structural coupling within the dorsal attention module and decreased functional–structural coupling within the ventral attention module in the svMCI group.In addition,the svMCI patients demonstrated decreased intramodular connectivity strength in the visual,somatomotor,and dorsal attention modules as well as decreased intermodular connectivity strength between several modules in the functional network,mainly linking the visual,somatomotor,dorsal attention,ventral attention,and frontoparietal control modules.There was no significant correlation between the altered module-level functional–structural coupling and cognitive performance in patients with svMCI.These findings demonstrate for the first time that svMCI is reflected in a selective aberrant topological organization in multiscale brain networks and may improve our understanding of the pathophysiological mechanisms underlying svMCI.展开更多
The similitude theory helps to understand the physical behaviors of large structures through scaled models. Several papers have studied the similitude of shock issues. However, the dynamic similitude for shock respons...The similitude theory helps to understand the physical behaviors of large structures through scaled models. Several papers have studied the similitude of shock issues. However, the dynamic similitude for shock responses of coupled structures is rarely incorporated in open studies. In this paper, scaling laws are derived for the shock responses and spectra of coupled structures. In the presented scaling laws, the geometric distortion and energy loss are considered. The ability of the proposed scaling laws is demonstrated in the simulation and experimental cases. In both cases, the similitude prediction for the prototype's time-domain waveform and spectrum is conducted with the scaled model and scaling laws. The simulation and experimental cases indicate that the predicted shock responses and spectra agree well with those of the prototype, which verifies the proposed scaling laws for predicting shock responses.展开更多
This paper is the first in a two-part series that discusses the principal axes of M-DOF structures subjected to static and dynamic loads. The primary purpose of this series is to understand the magnitude of the dynami...This paper is the first in a two-part series that discusses the principal axes of M-DOF structures subjected to static and dynamic loads. The primary purpose of this series is to understand the magnitude of the dynamic response of structures to enable better design of structures and control modification devices/systems. Under idealized design conditions, the structural responses are obtained by using single direction input ground motions in the direction of the intended control devices/systems, and by assuming that the responses of the structure is decoupleable in three mutually perpendicular directions. This standard practice has been applied to both new and retrofitted structures using various seismic protective systems. Very limited information is available on the effects of neglecting the impact of directional couplings (cross effects - of which torsion is a component) of the dynamic response of structures. In order to quantify such effects, it is necessary to examine the principal axes of structures under both static and dynamic loading. This first paper deals with quantitative definitions of principal axes and “cross effects” of three-dimensional structures under static load by using linear algebra. It shows theoretically that, for three-dimensional structures, such principal axes rarely exist. Under static loading conditions, the cross effect is typically small and negligible from the viewpoint of engineering applications. However, it provides the theoretical base for subsequent quantification of the response couplings under dynamic loads, which is reported in part II of this series.展开更多
基金supported by the National Natural Science Fund Joint Fund Project(No.U21B2068)the Major Science and Technology Innovation Project of WenZhou(No.ZG2021014).
文摘This article introduces the design theory of ceramic waveguide filter and proposes a new type of negative coupling structure with a conical throughhole,which has fine-adjustment of negative coupling without significantly increasing the insertion loss of the filter.Based on this,the article proposes an eightcavity ceramic waveguide filter design for 5G base stations.It also presents a detailed discussion on the influence of the cross-coupling slot lengths L2 and L4 on the transmission zeros positions during the filter optimization process and the relevant change rules.For the proposed optimized filter,the observed performance indicators include the center frequency of 3.5 GHz,working bandwidth of 200 MHz,an insertion loss of≤2.0 dB,return loss of≥19 dB,and out-of-band nearend suppression and out-of-band far-end suppression of≥39 dB and≥63 dB,respectively.The test performance results obtained for the sample,with structural parameters as per the simulation model,were in good agreement with the simulation results.
基金supported by the National Natural Science Foundation of China(Nos.U1304608 and 61774053)the Project of Henan Provincial Department of Science and Technology(No.182102410047)the Program of Henan Polytechnic University(No.B2014-020)。
文摘Photoluminescence(PL)was investigated as functions of the excitation intensity and temperature for a coupling surface quantum dots(SQDs)structure which consists of one In_(0.3)Ga_(0.7)As SQDs layer being stacked on multi-layers of In_(0.3)Ga_(0.7)As buried quantum dots(BQDs).Accompanied by considering the localized excitons effect induced by interface fluctuation,carrier transition between BQDs and SQDs were analyzed carefully.The PL measurements confirm that there is a strong carrier transition from BQDs to SQDs and this transition leads to obvious different PL characteristics between BQDs and SQDs.These results are useful for future application of SQDs as surface sensitive sensors.
基金Shenzhen Science and Technology Program,Grant/Award Numbers:GXWD2021B03,20220817165030002National Natural Science Foundation of China,Grant/Award Numbers:T2422031,52275298Postdoctoral Fellowship Program of CPSF,Grant/Award Number:GZC20240192。
文摘Ladybirds(Coccinella septempunctata)are adept at living in humid conditions as their elytra can effectively shield their bodies from raindrops.However,due to technical difficulties in examining the delicate structure,the understanding of the water-proofing mechanism of the coupling structure and its impact on the dome-like elytra response to the raindrops remain elusive.In this combined experimental and theoretical study,we showed that the coupling structure on the ladybird elytra can ward off the raindrops traveling at a velocity of 6 m/s,which generates an impact force equivalent to 600 times the body weight.The waterproofing mechanism relies on the deformability of the elytra and their microstructures,which collectively impedes the formation of microchannels for liquids.The enhanced water-proofing capabilities enabled by the coupling structures are validated through experimental testing on comparative 3D-printed models,showing the effectiveness of these structures in improving water resistance.Subsequently,we showcased a water-proofing device,which substantially improved the efficiency of solar panels in converting solar energy.This multidisciplinary study not only advances our understanding of the biomechanics of coupling systems in insects but also inspires the design of water-proofing deployable structures.
文摘The air valve is the core component of the cyclic operation of the compressor cylinder,and its structure and performance largely determine whether the reciprocating compressor can operate more efficiently and economically.On the basis of analyzing the basic structure and working principle of the air valve,this article mainly studies the motion characteristics of the suction valve plate.Based on fluid structure coupling mechanics and using ADINA software as a platform,numerical simulation analysis was conducted on the suction valve of a certain compressor model.Studying the stress of the valve plate and the variation of its upper and lower surface pressure with the opening and closing of the valve plate during the suction process of the compressor provides theoretical guidance for the rationality of the design of the air valve and related components,thereby improving the service life of the air valve and the working efficiency of the compressor.
基金supported by the National Natural Science Foundation of China(11074276)
文摘A broadband transducer with tube-beam coupling structure is presented. Flexural beams are put into a traditional segmented ring transducer including inactive portions to form a new tube-beam coupling structure with more useful working modes. Using multiple-mode- coupling design technique, the bandwidth of transducer could be expanded efficiently towards low frequency range. The optimization study of the electroacoustic parameters is carried out by finite element analysis at first. Then a prototype is manufactured and measured. It is shown that this projector combines the fine qualities of flextensional transducer with those of circular ring transducer by both the simulated and experimental results. It could achieve low frequency, high power and wide band performance from compact size. In addition, it is suitable for deep submergence operation when using free-flooded design.
基金supported jointly by the Fostering Plan Fund for Trans-century Excellent Talents and the Key Project of Science and Technology Research of the Ministry of Education(No.03178)the National Natural Science Foundation of China(No.40572063 and No.40234051).
文摘For understanding the possible deep-seated processes and geodynamic constrains on gold mineralization, comprehensive physicochemical and geochemical studies of gold mineralization have been undertaken within the paleo-lithosphere framework during the metailogenic epoch from the northwestern part of the Jiaodong Peninsula in this paper. A general image of the paleo-crust has been remained although it has been superimposed and reformed by post-metailogenic tectonic movements. The gold ore deposits occur usually in local uplifts and gradient belts featuring a turn from steep to gentle in granite-metamorphic contact zones, relative uplifts of gradient zones of the Curier isothermal interfaces, depressions of the Moho discontinuity and areas where depth contours are cut by isotherms perpendicularly. Gold mineralization and lithogenesis are characterized by high temperature, low pressure and high strength of thermal flux. The depth of mineralization ranges from 0.8 to 4.5 km. The depth of the top interface of the granitic complex in the metallogenic epoch is about 3 km. There is a low-velocity layer （LVL） at the bottom of the upper crust with a depth close to 19.5 km, which may be a detachment belt in the crust. The appearance of the LVL indicates the existence of paleo-hyperthermal fluid or relics of molten magma chambers, which reflects partial melting within the crust during the diagenetic and metallogenic epochs and the superposition effects of strike-slip shearing of the Taulu fault zone. The subsidence of the Moho is probably attributed to the coupling process of the NW-SE continental collision between North China and the Yangtze Block and the strike-slip movement of the Tanlu fault accompanied with underplating of mantle magma in the northwestern part of the Jiaodong Peninsula. The underplating of mantle magma may result in partial melting and make granite magma transfer upwards. This is favorable for the migration of metallogenic materials from deep to shallow to be enriched to form deposits. Coupling interactions between the strike-slip of the Taulu fault, the underplating of mantle magma, partial melting within the crust, and hyperthermal fluid, etc. may be the important factors controlling the gold mineralization and spatial structures in the metailogenic system.
基金Project supported by the National Natural Science Foundation of China(No.11972112)the Fundamental Research Funds for the Central Universities of China(Nos.N2103024 and N2103002)the Major Projects of Aero-Engines and Gasturbines(No.J2019-I-0008-0008)。
文摘The dynamic characteristics of a single liquid-filled pipe have been broadly studied in the previous literature.The parallel liquid-filled pipe(PLFP)system is also widely used in engineering,and its structure is more complex than that of a single pipe.However,there are few reports about the dynamic characteristics of the PLFPs.Therefore,this paper proposes improved frequency modeling and solution for the PLFPs,involving the logical alignment principle and coupled matrix processing.The established model incorporates both the fluid-structure interaction(FSI)and the structural coupling of the PLFPs.The validity of the established model is verified by modal experiments.The effects of some unique parameters on the dynamic characteristics of the PLFPs are discussed.This work provides a feasible method for solving the FSI of multiple pipes in parallel and potential theoretical guidance for the dynamic analysis of the PLFPs in engineering.
基金financially supported by the National Natural Science Foundation of China(Grant No.U1906233)the Development Projects in Key Areas of Guangdong Province(Grant No.2020B1111040002)the Fundamental Research Funds for the Central Universities(Grant Nos.DUT20ZD213 and DUT20LAB308)。
文摘This work presents a numerical investigation of the thermal–fluid–structure coupling behavior of the liquid natural gas(LNG)transported in the flexible corrugated cryogenic hose.A three-dimensional model of the corrugated hose structure composed of multiple layers of different materials is established and coupled with turbulent LNG flow and heat transfer models in the commercial software ANSYS Workbench.The flow transport behavior,heat transfer across the hose layers,and structural response caused by the flow are analyzed.Parametric studies are performed to evaluate the impacts of inlet flow rate and thermal conductivity of insulation material on the temperature and structural stress of the corrugated hose.The study found that,compared with a regular operating condition,higher inlet flow velocities not only suppress the heat gain of the LNG but also lower the flow-induced structural stress.The insulation layer exhibits excellent performance in maintaining the temperature at the fluid–structure interface,showing little temperature change with respect to material thermal conductivity and ambient temperature.The simulation results may contribute to the research and design of the flexible corrugated cryogenic hoses and provide guidance for safer and more efficient field operations.
基金China Seismological Bureau during the "Ninth Five-Year Plan" period!Key Project(95-04-08-02)
文摘In the light of results from study on coupling between deep and shallow structures in Xingtai earthquake area during the 'Ninth Five-Year Plan' period and other previous results from deep seismic refraction/reflection and seismic prospecting of petroleum, we infer that there exist a series of shallow faults in the upper crust above the 8 km-deep detachment surface in Xingtai macroseismic focal region, where none of the faults, including Aixinzhuang fault reaches the Quaternary stratum, except that the Xinhe fault cuts through the mid-Pleistocene formation upwards. Aixinzhuang fault and other faults extend downwards into Xinhe fault whereas the Xinhe listric fault stretches downwards at a low dip angle into the detachment surface. The abyssal fault with high dip angle under the detachment surface cutting through the middle and lower crust to Moho is the causative fault for the large Xingtai earthquake, whose dislocation can cause strong earthquakes, shallow fault activity and the motion of surface material. The shallow faults in the upper crust are not causative faults for strong earthquakes, although they may be active faults. The existence of the detachment surface brings about a special relationship between shallow and deep structures, i.e. they are relatively independent of each other and have effects on each other It not only transmits partial energy and deformation between the upper and lower crust,but also has a certain decoupling effect. Finally we conclude that active faults do not necessarily reach the latest stratum, and the age of uppermost faulted stratum cannot represent the latest active period of the fault. This put to us a significant question in regard to the age determination and study of active faults. Other noticeable questions are also inferred to in this study.
文摘Conventional coupled BE/FE （Boundary-Element/Finite-Element） method and modeling of structural-acoustic interaction has shown its promise and potential in the design and analysis of various structural-acoustic interaction applications. Unified combined acoustic and aerodynamic loading on the structure is synthesized using two approaches. Firstly, by linear superposition of the acoustic pressure disturbance to the aeroelastic problem, the effect of acoustic pressure disturbance to the aeroelastic structure is considered to consist of structural motion independent incident acoustic pressure and structural motion dependent acoustic pressure, which is known as the scattering pressure, referred here as the acoustic aerodynamic analogy. Secondly, by synthesizing the acoustic and aerodynamic effects on elastic structure using an elegant, effective and unified approach, both acoustic and aerodynamic effect on solid structural boundaries can be formulated as a boundary value problem governed by second order differential equations which lead to solutions expressible as surface integral equations. The unified formulation of the acousto-aeroelastic problem is amenable for simultaneous solution, although certain prevailing situations allow the solution of the equations independently. For this purpose, the unsteady aerodynamic problem which was earlier utilizes well-established lifting surface method is reformulated using Boundary Element （BE） approach. These schemes are outlined and worked out with examples.
文摘The coupling behavior of the imbedded weapon store occurring between the local unsteady flow field round the store and the structure response on the processing of opening its bay-door is simulated by using numerical method based on computational fluid mechanics(CFD).The transient aerodynamic behaviors when opening door under various flight altitudes and the corresponding structure deformation evolution in the unsteady flow fields are analyzed respectively and presented.The rules of aircraft attitude parameters′impacting to the responses of structure and the bay-door′s opening process are obtained by comparing with the analysis results.These rules can be applied to the structure design of bay-door and route specification of missile when disengaged and launched from within store.
文摘In this paper, the isogeometric analysis (IGA) is employed to develop an acoustic radiation model for a double plate-acoustic cavity coupling system, with a focus on analyzing the sound transmission loss (STL). The functionally graded (FG) plate exhibits a different material properties in-plane, and the power-law rule is adopted as the governing principle for material mixing. To validate the harmonic response and demonstrate the accuracy and convergence of the isogeometric modeling, ANASYS is utilized to compare with numerical examples. A plane wave serves as the acoustic excitation, and the Rayleigh integral is applied to discretize the radiated plate. The STL results are compared with the literature, confirming the reliability of the coupling system. Finally, the investigation is conducted to study impact of cavity depth and power-law parameter on the STL.
基金Supported by the National Natural Science Foundation of China under Grant(60921063)the National Program on Key Basic Research Project(973Program)(2010CB327400)the National Science and Technology Major Project(2010ZX03007-002-01)~~
文摘The microstrip dual-mode filter （DMF） with conventional coupling structure has some limitations in- eluding the port coupling strength limited by fabrication tolerance and the existence of serious second order spuri- ous band. Therefore, a novel DMF with a offset-feed bended coupling structure and a stepped-impedance dual- mode resonator is proposed for coupling enhancement and spurious response suppression. Based on the analysis of the change of spur frequencies and the current distribution of spur resonant modes, all spurs near passband of the cascaded DMF can be fully suppressed by optimizing the structure parameters of parasite resonators, which bene- fits from the inherent well-controlled transmission zeros. Experimental results show that the proposed DMF ex- hibits lower insertion loss ,much sharper rate of cutoff and wider spur-free stop band compared with conventional DMF. This design is applicable for spur suppression in wideband communication.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11875042 and 11505114)the Shanghai Project for Construction of Top Disciplines (Grant No. USST-SYS-01)。
文摘Detecting coupling pattern between elements in a complex system is a basic task in data-driven analysis. The trajectory for each specific element is a cooperative result of its intrinsic dynamic, its couplings with other elements, and the environment. It is subsequently composed of many components, only some of which take part in the couplings. In this paper we present a framework to detect the component correlation pattern. Firstly, the interested trajectories are decomposed into components by using decomposing methods such as the Fourier expansion and the Wavelet transformation. Secondly, the cross-correlations between the components are calculated, resulting into a component cross-correlation matrix(network).Finally, the dominant structure in the network is identified to characterize the coupling pattern in the system. Several deterministic dynamical models turn out to be characterized with rich structures such as the clustering of the components. The pattern of correlation between respiratory(RESP) and ECG signals is composed of five sub-clusters that are mainly formed by the components in ECG signal. Interestingly, only 7 components from RESP(scattered in four sub-clusters) take part in the realization of coupling between the two signals.
文摘The design of counter-rotating turbine is one of new techniques to improve the thrust-weight ratio of jet propulsion engines.Numerical analysis of a low pressure（LP）counter-rotating turbine rotor blade is presented by using ANSYS/CFX software.Interaction of aerodynamics and solid mechanics coupling in the computation is applied.In some rating of turbine,stress distribution and vibration characteristics of low pressure turbine（LPT）blade are computed.The wake aerodynamic forces and LPT blade vibration are transformed in frequency domain using fast Fourier transform（FFT）method.The results show that under wake aerodynamic force excitation,the first order modal vibration is more easily aroused and the higher order response cannot be ignored.Moreover,with different temperature fields,the vibration responses of blade are also different.
文摘The structure and the acoustic medium of a passenger vehicle are modeled using the finite element method(FEM), and the interior noise is studied the help of the modal synthesis method (MSM). Sound pressure level (Lp) of the noise is calculated in several conditions of the models, and has good agreements with its test results. The MSM am be consequently used for predicting the vehicle interior noise in dssign stage so that the structure may be optimized for the Purpose of the most reduction of noise.
基金supported by the National Natural Science Foundation of China(Nos.10672121 and 11072125)
文摘Through the Galerkin method the nonlinear ordinary differential equations （ODEs） in time are obtained from the nonlinear partial differential equations （PDEs） to describe the mo- tion of the coupled structure of a suspended-cable-stayed beam. In the PDEs, the curvature of main cables and the deformation of cable stays are taken into account. The dynamics of the struc- ture is investigated based on the ODEs when the structure is subjected to a harmonic excitation in the presence of both high-frequency principle resonance and 1：2 internal resonance. It is found that there are typical jumps and saturation phenomena of the vibration amplitude in the struc- ture. And the structure may present quasi-periodic vibration or chaos, if the stiffness of the cable stays membrane and frequency of external excitation are disturbed.
基金supported by the Natural Science Foundation of Tianjin Municipal Science and Technology Commission(18JCQNJC10900)Tianjin Natural Science Foundation(17JCZDJC36300)。
文摘Subcortical vascular mild cognitive impairment(svMCI)is a common prodromal stage of vascular dementia.Although mounting evidence has suggested abnormalities in several single brain network metrics,few studies have explored the consistency between functional and structural connectivity networks in svMCI.Here,we constructed such networks using resting-state f MRI for functional connectivity and diffusion tensor imaging for structural connectivity in 30 patients with svMCI and 30 normal controls.The functional networks were then parcellated into topological modules,corresponding to several well-defined functional domains.The coupling between the functional and structural networks was finally estimated and compared at the multiscale network level(whole brain and modular level).We found no significant intergroup differences in the functional–structural coupling within the whole brain;however,there was significantly increased functional–structural coupling within the dorsal attention module and decreased functional–structural coupling within the ventral attention module in the svMCI group.In addition,the svMCI patients demonstrated decreased intramodular connectivity strength in the visual,somatomotor,and dorsal attention modules as well as decreased intermodular connectivity strength between several modules in the functional network,mainly linking the visual,somatomotor,dorsal attention,ventral attention,and frontoparietal control modules.There was no significant correlation between the altered module-level functional–structural coupling and cognitive performance in patients with svMCI.These findings demonstrate for the first time that svMCI is reflected in a selective aberrant topological organization in multiscale brain networks and may improve our understanding of the pathophysiological mechanisms underlying svMCI.
基金Project supported by the National Natural Science Foundation of China (Nos. 12272089 and U1908217)the Fundamental Research Funds for the Central Universities of China (Nos. N2224001-4 and N2003013)the Basic and Applied Basic Research Foundation of Guangdong Province of China (No. 2020B1515120015)。
文摘The similitude theory helps to understand the physical behaviors of large structures through scaled models. Several papers have studied the similitude of shock issues. However, the dynamic similitude for shock responses of coupled structures is rarely incorporated in open studies. In this paper, scaling laws are derived for the shock responses and spectra of coupled structures. In the presented scaling laws, the geometric distortion and energy loss are considered. The ability of the proposed scaling laws is demonstrated in the simulation and experimental cases. In both cases, the similitude prediction for the prototype's time-domain waveform and spectrum is conducted with the scaled model and scaling laws. The simulation and experimental cases indicate that the predicted shock responses and spectra agree well with those of the prototype, which verifies the proposed scaling laws for predicting shock responses.
基金funded through a contract from the Federal Highway Administration (Contract No.ETFH61-98-C-00094)a grant from the Earthquake Education Research Centers Program of the National Science Foundation to the Multidisciplinary Center for Earthquake Engineering Research (Grant No.ECC-9701471).
文摘This paper is the first in a two-part series that discusses the principal axes of M-DOF structures subjected to static and dynamic loads. The primary purpose of this series is to understand the magnitude of the dynamic response of structures to enable better design of structures and control modification devices/systems. Under idealized design conditions, the structural responses are obtained by using single direction input ground motions in the direction of the intended control devices/systems, and by assuming that the responses of the structure is decoupleable in three mutually perpendicular directions. This standard practice has been applied to both new and retrofitted structures using various seismic protective systems. Very limited information is available on the effects of neglecting the impact of directional couplings (cross effects - of which torsion is a component) of the dynamic response of structures. In order to quantify such effects, it is necessary to examine the principal axes of structures under both static and dynamic loading. This first paper deals with quantitative definitions of principal axes and “cross effects” of three-dimensional structures under static load by using linear algebra. It shows theoretically that, for three-dimensional structures, such principal axes rarely exist. Under static loading conditions, the cross effect is typically small and negligible from the viewpoint of engineering applications. However, it provides the theoretical base for subsequent quantification of the response couplings under dynamic loads, which is reported in part II of this series.
