Advanced intensity measures(IMs)based on an inelastic deformation spectrum improved the evaluation of the median engineering demand parameters(EDPs)and reduced dispersion.In this regard,an optimized two-degreefreedom(...Advanced intensity measures(IMs)based on an inelastic deformation spectrum improved the evaluation of the median engineering demand parameters(EDPs)and reduced dispersion.In this regard,an optimized two-degreefreedom(2DOF)modal pushover-based scaling procedure(2DMPS)has been developed for a nonlinear dynamic analysis of asymmetric in-plan buildings.The 2DMPS procedure scales ground motions to approach close enough to a target value of the inelastic displacement of the first-mode inelastic 2DOF modal stick,extended for structures with significant contributions of higher modes.Further,4-,6-and 13-story RC SMRF buildings were selected for analyses using ground motion records scaled by the 2DMPS procedure,the modal pushover-based scaling method(MPS),and ASCE/SEI 7-16 scaling procedures.The median values of EDPs on scaled records closely matched the benchmark results.The bias in the EDP values due to the scaled records in every group regarding their median value was lower than the dispersion of the 21 unscaled records.These results generally demonstrate the accuracy and efficiency of the 2DMPS method.Additionally,the 2DOF modal stick’s inelastic response spectra are better suited for calculating seismic demands for one-way asymmetric-plan structures than the SDOF inelastic response spectra.展开更多
Finding an optimal isolator arrangement for asymmetric structures using traditional conceptual design methods that can significantly minimize torsional response while ensuring efficient horizontal seismic isolation is...Finding an optimal isolator arrangement for asymmetric structures using traditional conceptual design methods that can significantly minimize torsional response while ensuring efficient horizontal seismic isolation is cumbersome and inefficient.Thus,this work develops a multi-objective optimization method to enhance the torsional resistance of asymmetric base-isolated structures.The primary objective is to simultaneously minimize the interstory rotation of the superstructure,the rotation of the isolation layer,and the interstory displacement of the superstructure without exceeding the isolator displacement limits.A fast non-dominated sorting genetic algorithm(NSGA-Ⅱ)is employed to satisfy this optimization objective.Subsequently,the isolator arrangement,encompassing both positions and categories,is optimized according to this multi-objective optimization method.Additionally,an optimization design platform is developed to streamline the design operation.This platform integrates the input of optimization parameters,the output of optimization results,the finite element analysis,and the multi-objective optimization method proposed herein.Finally,the application of this multi-objective optimization method and its associated platform are demonstrated on two asymmetric base-isolated structures of varying heights and plan configurations.The results indicate that the optimal isolator arrangement derived from the optimization method can further improve the control over the lateral and torsional responses of asymmetric base-isolated structures compared to conventional conceptual design methods.Notably,the interstory rotation of the optimal base-isolated structure is significantly reduced,constituting only approximately 33.7%of that observed in the original base-isolated structure.The proposed platform facilitates the automatic generation of the optimal design scheme for the isolators of asymmetric base-isolated structures,offering valuable insights and guidance for the burgeoning field of intelligent civil engineering design.展开更多
The analysis of the SPECTRUM (Special Experiment Concerning Typhoon Recurvature and Unusual Movement) data indicates that the structure of recurving target typhoons 9015 (Abe),9019 (Flo) and 9020 (Gene) at different s...The analysis of the SPECTRUM (Special Experiment Concerning Typhoon Recurvature and Unusual Movement) data indicates that the structure of recurving target typhoons 9015 (Abe),9019 (Flo) and 9020 (Gene) at different stages of moving processes showed different motion features.On different time scales,temporal variations of typhoon structure and motion speed displayed different features.展开更多
It is of significance to prepare biodegradable electromagnetic interference(EMI)shielding materials with high EMI shielding effectiveness(SE)in order to solve electromagnetic and environmental pollution problems.In th...It is of significance to prepare biodegradable electromagnetic interference(EMI)shielding materials with high EMI shielding effectiveness(SE)in order to solve electromagnetic and environmental pollution problems.In this paper,environmentally friendly EMI shielding silver nanowires(AgNWs)/poly(L-lactic acid)(PLLA)/poly(D-lactic acid)(PDLA)/ferroferric oxide(Fe_(3)O_(4))composites with step-wise asymmetric structures were prepared by a facile one-step non-solvent-induced phase separation method.The conductive AgNW network was constructed at a low mass fraction of 5 wt.%on the surface of stereo-complexed crystalline poly(lactic acid)(SC-PLA)film(1.08×10^(4) S/m).Moreover,magnetic Fe_(3)O_(4)is mainly distributed in the skeleton of porous SC-PLA film.Due to the synergistic effect of AgNWs and Fe_(3)O_(4),the EMI SE of SC-PLA films reaches up to 50.3 dB.Interestingly,SC-PLA film modified with triethoxy-1H,1H,2H,2H-tridecafluoro-n-octylsilane(TTO)demonstrates an outstanding water contact angle of about 150.2°compared with the pure PLLA film(134.7°),stemming from the synergistic effect of denser SC-PLA nano-protrusions and low-surface-energy TTO.Thus,we successfully fabricated the high EMI shielding SC-PLA film with wonderful superhydrophobicity,which extends the application performance and service life of portable electronics in moist environments.展开更多
The Arctic Oscillation (AO), though basically is a zonal symmetricphenomenon, also shows zonal asymmetric variation. The dynamics of this zonal variation isconsidered here from the point of view of the planetary propa...The Arctic Oscillation (AO), though basically is a zonal symmetricphenomenon, also shows zonal asymmetric variation. The dynamics of this zonal variation isconsidered here from the point of view of the planetary propagation on the earth sphere. Based onthe linear barotropic vorticity e-quation, the planetary wave ray path is calculated in the winterJanuary. It shows that NAO( North Atlantic Oscillation), AO and North Pacific could be linkedthrough the planetary wave propagation, which acts as the atmospheric bridge. The zonal symmetricand asymmetric structures both have association with these Rossby wave activities.展开更多
The modulation of resonance features in microcavities is important to applications in nanophotonics.Based on the asymmetric whispering-gallery modes(WGMs)in a plasmonic resonator,we theoretically studied the mode evol...The modulation of resonance features in microcavities is important to applications in nanophotonics.Based on the asymmetric whispering-gallery modes(WGMs)in a plasmonic resonator,we theoretically studied the mode evolution in an asymmetric WGM plasmonic system.Exploiting the gap or nano-scatter in the plasmonic ring cavity,the symmetry of the system will be broken and the standing wave in the cavity will be tunable.Based on this asymmetric structure,the output coupling rate between the two cavity modes can also be tuned.Moreover,the proposed method could further be applied for sensing and detecting the position of defects in a WGM system.展开更多
The primary purpose of this research is to improve the seismic response of a complex asymmetric tall structure using viscoelastic(VE) dampers. Asymmetric structures have detrimental effects on the seismic performance ...The primary purpose of this research is to improve the seismic response of a complex asymmetric tall structure using viscoelastic(VE) dampers. Asymmetric structures have detrimental effects on the seismic performance because such structures create abrupt changes in the stiffness or strength that may lead to undesirable stress concentrations at weak locations. Structural control devices are one of the effective ways to reduce seismic impacts, particularly in asymmetric structures. For passive vibration control of structures, VE dampers are considered among the most preferred devices for energy dissipation. Therefore, in this research, VE dampers are implemented at strategic locations in a realistic case study structure to increase the level of distributed damping without occupying significant architectural space and reducing earthquake vibrations in terms of story displacements(drifts) and other design forces. It has been concluded that the seismic response of the considered structure retrofitted with supplemental VE dampers corresponded well in controlling the displacement demands. Moreover, it has been demonstrated that seismic response in terms of interstory drifts was effectively mitigated with supplemental damping when added up to a certain level. Exceeding the supplemental damping from this level did not contribute to additional mitigation of the seismic response of the considered structure. In addition, it was found that the supplemental damping increased the total acceleration of the considered structure at all floor levels, which indicates that for irregular tall structures of this type, VE dampers were only a good retrofitting measure for earthquake induced interstory deformations and their use may not be suitable for acceleration sensitive structures. Overall, the research findings demonstrate how seismic hazards to these types of structures can be reduced by introducing additional damping into the structure.展开更多
The structural characteristics of 2004 typhoon Aere's precipitation are analyzed using the high-resolution data from the Tropical Rainfall Measuring Mission(TRMM) of the National Aeronautics Space Administration(N...The structural characteristics of 2004 typhoon Aere's precipitation are analyzed using the high-resolution data from the Tropical Rainfall Measuring Mission(TRMM) of the National Aeronautics Space Administration(NASA).It is found that the typhoon's characteristics vary at different stages of its development.To analyze the asymmetric causation of precipitation distribution,data from the National Center for Environmental Prediction(NCEP) reanalysis are used to calculate the vertical integral of the water vapor flux vector.The results show that because of this process,along with the unique phenomenon of twin-typhoon circulation,the easterly air current of the typhoon's northern side and the southwesterly air current of its southern side play a joint role in transporting water vapor.Furthermore,its transport effects vary greatly at the different stages of development,showing the peculiarity of the water source for this typhoon process.The distributions of the typhoon convection area—characterized by heavy precipitation and a maximum-value area of the water vapor flux,as well as a strong ascending-motion area—differ at different stages of the typhoon's development.The non-uniform distribution of water vapor flux and the vertical motion bring about asymmetrical distribution of the typhoon precipitation.展开更多
We present a stable linear-cavity single longitudinal mode （SLM） erbium-doped silica fiber laser. It consists of four fiber Bragg gratings （FBGs） directly written in a section of photosensitive erbium-doped fiber ...We present a stable linear-cavity single longitudinal mode （SLM） erbium-doped silica fiber laser. It consists of four fiber Bragg gratings （FBGs） directly written in a section of photosensitive erbium-doped fiber （EDF） to form an asymmetric three-cavity structure. The stable SLM operation at a wavelength of 1545.112 nm with a 3-dB bandwidth of 0.012 nm and an optical signal-to-noise ratio （OSNR） of about 60 dB is verified experimentally. Under laboratory conditions, the performance of a power fluctuation of less than 0.05 dB observed from the power meter for 6 h and a wavelength variation of less than 0.01 nm obtained from the optical spectrum analyzer （OSA） for about 1.5 h are demonstrated. The gain fiber length is no longer limited to only several centimeters for SLM operation because of the excellent mode-selecting ability of the asymmetric three-cavity structure. The proposed scheme provides a simple and cost-effective approach to realizing a stable SLM fiber laser.展开更多
An inter-story shear model of asymmetric base-isolated structures incorporating deformation of each isolation bearing was built, and a method to simultaneously simulate bi-directional near-fault and far-field ground m...An inter-story shear model of asymmetric base-isolated structures incorporating deformation of each isolation bearing was built, and a method to simultaneously simulate bi-directional near-fault and far-field ground motions was proposed. A comparative study on the dynamic responses of asymmetric base-isolated structures under near-fault and far-field ground motions were conducted to investigate the effects of eccentricity in the isolation system and in the superstructures, the ratio of the uncoupled torsional to lateral frequency of the superstructure and the pulse period of near-fault ground motions on the nonlinear seismic response of asymmetric base-isolated structures. Numerical results show that eccentricity in the isolation system makes asymmetric base-isolated structure more sensitive to near-fault ground motions, and the pulse period of near-fault ground motions plays an import role in governing the seismic responses of asymmetric base-isolated structures.展开更多
Based on the symmetric re-entrant honeycomb(S-RH)structure with negative Poisson’s ratios,a novel asymmetric and rotatable re-entrant honeycomb(AR-RH)structure was proposed.Both the S-RH structure and AR-RH structure...Based on the symmetric re-entrant honeycomb(S-RH)structure with negative Poisson’s ratios,a novel asymmetric and rotatable re-entrant honeycomb(AR-RH)structure was proposed.Both the S-RH structure and AR-RH structure were produced by the 3D printing technology.Through experimental test and finite element simulation,the deformation mechanism and energy absorption characteristics of the AR-RH structure and the S-RH structure with negative Poisson’s ratios at different impact velocities were compared.The experimental test and finite element simulation results show that the novel AR-RH structure with negative Poisson’s ratios has stronger energy absorption capacity than the S-RH structure,and it has been verified that the rotatability of AR-RH can indeed absorb energy.Furthermore,the degree of asymmetry of the AR-RH structure was discussed.展开更多
In this paper, an asymmetric array structure of space laser communication receiver is proposed. This structure can greatly reduce alignment requirement, and lighten the signal strength jitter caused by atmospheric tur...In this paper, an asymmetric array structure of space laser communication receiver is proposed. This structure can greatly reduce alignment requirement, and lighten the signal strength jitter caused by atmospheric turbulence. A prototype of the proposed structure is fabricated and a 2.5 Mbit/s on-off keying(OOK) modulated demonstration link over 40 m free space is built. This asymmetric array structure can effectively collect optical signal while rotating in a window angle of ±17°, and the bit error ratio(BER) keeps zero.展开更多
Compound Co_3(o-HOC_6H_4S)_2(o-OC_6H_4S)_2(PEt_3)_3 was obtained by reaction of CoCl_2, o-HOC_6H_4SH(H_2mD)and PEt_3 in ethanol in the presence of NaOCH_3.The three Co atoms are triangularly arranged and asymmetricall...Compound Co_3(o-HOC_6H_4S)_2(o-OC_6H_4S)_2(PEt_3)_3 was obtained by reaction of CoCl_2, o-HOC_6H_4SH(H_2mD)and PEt_3 in ethanol in the presence of NaOCH_3.The three Co atoms are triangularly arranged and asymmetrically bridged by four S and one O atoms from the four H_2mp ligands and terminally ligated by one O and three P atoms.Two free hydroxyl groups form two internal hydrogen bonds with adjacent oxo donor atoms.展开更多
A flexible asymmetric supercapacitor with high energy density was constructed by using a flexible substrate of carbonized silk-fabrics decorated with carbon nanotube, electroplating MnO2 nanosheets and dip-coating act...A flexible asymmetric supercapacitor with high energy density was constructed by using a flexible substrate of carbonized silk-fabrics decorated with carbon nanotube, electroplating MnO2 nanosheets and dip-coating activated carbon powders as the positive and the negative electrodes, respectively. By controlling the electroplating time, the MnO2 nanosheets can be self-assembled to honeycomb structure and showed excellent electrochemical performance in 1 mol/L Na2SO4 electrolyte with SC950-EP30 performing the best. It exhibited a high specific capacitance（1110.85 F/g at a current density of 1 A/g based on the mass of MnO2） and superior rate capability（77.44% capacity retention from 1 A/g to 10 A/g）.Thus, the optimal asymmetric device assembled with this material as positive electrode can deliver a maximum energy density of 43.84 Wh/kg and a maximum power density of 6.62 kW/kg.展开更多
The effects of journal misalignment on a journal bearing caused by an asymmetric rotor structure are presented in this study.A new model considering the asymmetric deflection is applied.Also,the thermo-hydrodynamic of...The effects of journal misalignment on a journal bearing caused by an asymmetric rotor structure are presented in this study.A new model considering the asymmetric deflection is applied.Also,the thermo-hydrodynamic of the oil film in the journal bearing and straightforward elasticity theory are considered in the analysis.Based on the structure stiffness equivalent characteristic,a simple stepped shaft can reflect the entire complex structure model.The existing lubrication model,which does not consider this angle component,is not very precise for journal bearings.Film pressure,misalignment angle,velocity field,oil leakage,and temperature field were calculated and compared in the journal bearing analysis.The results indicate that bearing performances are greatly affected by misalignment caused by the asymmetric structure.A simple stepped shaft can effectively represent a misaligned journal bearing in a rotor-bearing system.展开更多
Solid-state lithium metal batteries(SSLMBs)show great promise in terms of high-energy-density and high-safety performance.However,there is an urgent need to address the compatibility of electrolytes with high-voltage ...Solid-state lithium metal batteries(SSLMBs)show great promise in terms of high-energy-density and high-safety performance.However,there is an urgent need to address the compatibility of electrolytes with high-voltage cathodes/Li anodes,and to minimize the electrolyte thickness to achieve highenergy-density of SSLMBs.Herein,we develop an ultrathin(12.6μm)asymmetric composite solid-state electrolyte with ultralight areal density(1.69 mg cm^(−2))for SSLMBs.The electrolyte combining a garnet(LLZO)layer and a metal organic framework(MOF)layer,which are fabricated on both sides of the polyethylene(PE)separator separately by tape casting.The PE separator endows the electrolyte with flexibility and excellent mechanical properties.The LLZO layer on the cathode side ensures high chemical stability at high voltage.The MOF layer on the anode side achieves a stable electric field and uniform Li flux,thus promoting uniform Li^(+)deposition.Thanks to the well-designed structure,the Li symmetric battery exhibits an ultralong cycle life(5000 h),and high-voltage SSLMBs achieve stable cycle performance.The assembled pouch cells provided a gravimetric/volume energy density of 344.0 Wh kg^(−1)/773.1 Wh L^(−1).This simple operation allows for large-scale preparation,and the design concept of ultrathin asymmetric structure also reveals the future development direction of SSLMBs.展开更多
Carbon-and silica-based nanomaterials possess a set of merits including large surface area,good structural stability,diversified morphology,adjustable structure,and biocompatibility.These outstanding features make the...Carbon-and silica-based nanomaterials possess a set of merits including large surface area,good structural stability,diversified morphology,adjustable structure,and biocompatibility.These outstanding features make them widely applied in different fields.However,limited by the surface free energy effect,the current studies mainly focus on the symmetric structures,such as nanospheres,nanoflowers,nanowires,nanosheets,and core-shell structured composites.By comparison,the asymmetric structure with ingenious adjustability not only exhibits a larger effective surface area accompanied with more active sites,but also enables each component to work independently or corporately to harness their own merits,thus showing the unusual performances in some specific applications.The current review mainly focuses on the recent progress of design principles and synthesis methods of asymmetric carbon-and silica-based nanomaterials,and their applications in energy storage,catalysis,and biomedicine.Particularly,we provide some deep insights into their unique advantages in related fields from the perspective of materials’structure-performance relationship.Furthermore,the challenges and development prospects on the synthesis and applications of asymmetric carbon-and silica-based nanomaterials are also presented and highlighted.展开更多
In this article,a single-board integrated millimeter-wave(mm-Wave)asymmetric full-digital beamforming(AFDBF)array is developed for beyond-fifth-generation(B5G)and sixth-generation(6G)communications.The proposed integr...In this article,a single-board integrated millimeter-wave(mm-Wave)asymmetric full-digital beamforming(AFDBF)array is developed for beyond-fifth-generation(B5G)and sixth-generation(6G)communications.The proposed integrated array effectively addresses the challenge of arranging a large number of ports in a full-digital array by designing vertical connections in a three-dimensional space and successfully integrating full-digital transmitting(Tx)and receiving(Rx)arrays independently in a single board.Unlike the traditional symmetric array,the proposed asymmetric array is composed of an 8×8 Tx array arranged in a square shape and an 8+8 Rx array arranged in an L shape.The center-to-center distance between two adjacent elements is 0.54k0 for both the Tx and Rx arrays,where k0 is the free-space wavelength at 27 GHz.The proposed AFDBF array possesses a more compact structure and lower system hardware cost and power consumption compared with conventional brick-type full-digital arrays.In addition,the energy efficiency of the proposed AFDBF array outperforms that of a hybrid beamforming array.The measurement results indicate that the operating frequency band of the proposed array is 24.25–29.50 GHz.An eight-element linear array within the Tx array can achieve a scanning angle ranging from-47°to+47°in both the azimuth and the elevation planes,and the measured scanning range of each eight-element Rx array is–45°to+45°.The measured maximum effective isotropic radiated power(EIRP)of the eight-element Tx array is 43.2 dBm at 28.0 GHz(considering the saturation point).Furthermore,the measured error vector magnitude(EVM)is less than 3%when 64-quadrature amplitude modulation(QAM)waveforms are used.展开更多
Since electromagnetic pollution is detrimental to human health and the environment,numerous efforts have been successively made to achieve excellent electromagnetic interference shielding effectiveness(EMI SE)via desi...Since electromagnetic pollution is detrimental to human health and the environment,numerous efforts have been successively made to achieve excellent electromagnetic interference shielding effectiveness(EMI SE)via designing the hierarchical structures for electromagnetic interference(EMI)shielding polymer composites.Among the plentiful structures,the asymmetric structures are currently a hot spot,principally categorizing into multi-layered,porous,fibrous,and segregated asymmetric structures,which endows the high EMI shielding performance for polymer composites incorporated with magnetic,conductive,and/or dielectric micro/nano-fillers,due to the“absorption-reflection-reabsorption”shielding mechanism.Therefore,this review provides the retrospection and summary of the efforts with respect to abundant asymmetric structures and multifunctional micro/nano-fillers for enhancing EMI shielding properties,which is conducive to the booming development of polymeric EMI shielding materials for the promising prospect in modern electronics and 5-generation(5G)technology.展开更多
A novel asymmetric Ni/PVC film has been developed by solution casting method. The structure, electrical conductivity, electromagnetic interference （EMI） shielding, and impact resistance were investigated. The result...A novel asymmetric Ni/PVC film has been developed by solution casting method. The structure, electrical conductivity, electromagnetic interference （EMI） shielding, and impact resistance were investigated. The results showed that the Ni particles were asymmetrically distributed along the thickness direction in the film. The top surface resistivity increased with film thickness, while the bottom surface exhibited the different trend. EMI shielding effectiveness （SE） depended on formation of closed packed conductive Ni network, which was influenced by both Ni content and film thickness. A linear relationship was observed between EMI SE and film thickness. The films with lower Ni content showed the faster increasing rate of EMI SE with film thickness. Some of the films show appreciably high EMI SE （〉 40 dB）, indicating the promising application in EMI shielding field. Moreover, the films exhibit different impact performance under different impacting directions. All the experimental facts demonstrate that the asymmetric structure endows the film achieving high-performance EMI shielding function.展开更多
文摘Advanced intensity measures(IMs)based on an inelastic deformation spectrum improved the evaluation of the median engineering demand parameters(EDPs)and reduced dispersion.In this regard,an optimized two-degreefreedom(2DOF)modal pushover-based scaling procedure(2DMPS)has been developed for a nonlinear dynamic analysis of asymmetric in-plan buildings.The 2DMPS procedure scales ground motions to approach close enough to a target value of the inelastic displacement of the first-mode inelastic 2DOF modal stick,extended for structures with significant contributions of higher modes.Further,4-,6-and 13-story RC SMRF buildings were selected for analyses using ground motion records scaled by the 2DMPS procedure,the modal pushover-based scaling method(MPS),and ASCE/SEI 7-16 scaling procedures.The median values of EDPs on scaled records closely matched the benchmark results.The bias in the EDP values due to the scaled records in every group regarding their median value was lower than the dispersion of the 21 unscaled records.These results generally demonstrate the accuracy and efficiency of the 2DMPS method.Additionally,the 2DOF modal stick’s inelastic response spectra are better suited for calculating seismic demands for one-way asymmetric-plan structures than the SDOF inelastic response spectra.
基金National Natural Science Foundation of China under Grant No.52278490。
文摘Finding an optimal isolator arrangement for asymmetric structures using traditional conceptual design methods that can significantly minimize torsional response while ensuring efficient horizontal seismic isolation is cumbersome and inefficient.Thus,this work develops a multi-objective optimization method to enhance the torsional resistance of asymmetric base-isolated structures.The primary objective is to simultaneously minimize the interstory rotation of the superstructure,the rotation of the isolation layer,and the interstory displacement of the superstructure without exceeding the isolator displacement limits.A fast non-dominated sorting genetic algorithm(NSGA-Ⅱ)is employed to satisfy this optimization objective.Subsequently,the isolator arrangement,encompassing both positions and categories,is optimized according to this multi-objective optimization method.Additionally,an optimization design platform is developed to streamline the design operation.This platform integrates the input of optimization parameters,the output of optimization results,the finite element analysis,and the multi-objective optimization method proposed herein.Finally,the application of this multi-objective optimization method and its associated platform are demonstrated on two asymmetric base-isolated structures of varying heights and plan configurations.The results indicate that the optimal isolator arrangement derived from the optimization method can further improve the control over the lateral and torsional responses of asymmetric base-isolated structures compared to conventional conceptual design methods.Notably,the interstory rotation of the optimal base-isolated structure is significantly reduced,constituting only approximately 33.7%of that observed in the original base-isolated structure.The proposed platform facilitates the automatic generation of the optimal design scheme for the isolators of asymmetric base-isolated structures,offering valuable insights and guidance for the burgeoning field of intelligent civil engineering design.
基金This work was supported by the National 8th Five-Year Plan ScienceTechnology Key Item Foundation under Grant 85-906-07.
文摘The analysis of the SPECTRUM (Special Experiment Concerning Typhoon Recurvature and Unusual Movement) data indicates that the structure of recurving target typhoons 9015 (Abe),9019 (Flo) and 9020 (Gene) at different stages of moving processes showed different motion features.On different time scales,temporal variations of typhoon structure and motion speed displayed different features.
基金This work was supported by the National Natural Science Foundation of China(Nos.52263003 and 51963003)the Guizhou Provincial Science and Technology Projects(Nos.[2020]1Z044 and ZK[2022]Maj019).
文摘It is of significance to prepare biodegradable electromagnetic interference(EMI)shielding materials with high EMI shielding effectiveness(SE)in order to solve electromagnetic and environmental pollution problems.In this paper,environmentally friendly EMI shielding silver nanowires(AgNWs)/poly(L-lactic acid)(PLLA)/poly(D-lactic acid)(PDLA)/ferroferric oxide(Fe_(3)O_(4))composites with step-wise asymmetric structures were prepared by a facile one-step non-solvent-induced phase separation method.The conductive AgNW network was constructed at a low mass fraction of 5 wt.%on the surface of stereo-complexed crystalline poly(lactic acid)(SC-PLA)film(1.08×10^(4) S/m).Moreover,magnetic Fe_(3)O_(4)is mainly distributed in the skeleton of porous SC-PLA film.Due to the synergistic effect of AgNWs and Fe_(3)O_(4),the EMI SE of SC-PLA films reaches up to 50.3 dB.Interestingly,SC-PLA film modified with triethoxy-1H,1H,2H,2H-tridecafluoro-n-octylsilane(TTO)demonstrates an outstanding water contact angle of about 150.2°compared with the pure PLLA film(134.7°),stemming from the synergistic effect of denser SC-PLA nano-protrusions and low-surface-energy TTO.Thus,we successfully fabricated the high EMI shielding SC-PLA film with wonderful superhydrophobicity,which extends the application performance and service life of portable electronics in moist environments.
文摘The Arctic Oscillation (AO), though basically is a zonal symmetricphenomenon, also shows zonal asymmetric variation. The dynamics of this zonal variation isconsidered here from the point of view of the planetary propagation on the earth sphere. Based onthe linear barotropic vorticity e-quation, the planetary wave ray path is calculated in the winterJanuary. It shows that NAO( North Atlantic Oscillation), AO and North Pacific could be linkedthrough the planetary wave propagation, which acts as the atmospheric bridge. The zonal symmetricand asymmetric structures both have association with these Rossby wave activities.
基金National Natural Science Foundation of China(NSFC)(61622103,61471050,61671083,11404031)Fok Ying-Tong Education Foundation for Young Teachers in the Higher Education Institutions of China(151063)Open Research Fund Program of the State Key Laboratory of Low-Dimensional Quantum Physics,Tsinghua University(KF201610)
文摘The modulation of resonance features in microcavities is important to applications in nanophotonics.Based on the asymmetric whispering-gallery modes(WGMs)in a plasmonic resonator,we theoretically studied the mode evolution in an asymmetric WGM plasmonic system.Exploiting the gap or nano-scatter in the plasmonic ring cavity,the symmetry of the system will be broken and the standing wave in the cavity will be tunable.Based on this asymmetric structure,the output coupling rate between the two cavity modes can also be tuned.Moreover,the proposed method could further be applied for sensing and detecting the position of defects in a WGM system.
基金Supported by:Ministry of Science and Technology of China under Grant No.2017YFC0703603National Natural Science Foundation of China under Grant No.51678322
文摘The primary purpose of this research is to improve the seismic response of a complex asymmetric tall structure using viscoelastic(VE) dampers. Asymmetric structures have detrimental effects on the seismic performance because such structures create abrupt changes in the stiffness or strength that may lead to undesirable stress concentrations at weak locations. Structural control devices are one of the effective ways to reduce seismic impacts, particularly in asymmetric structures. For passive vibration control of structures, VE dampers are considered among the most preferred devices for energy dissipation. Therefore, in this research, VE dampers are implemented at strategic locations in a realistic case study structure to increase the level of distributed damping without occupying significant architectural space and reducing earthquake vibrations in terms of story displacements(drifts) and other design forces. It has been concluded that the seismic response of the considered structure retrofitted with supplemental VE dampers corresponded well in controlling the displacement demands. Moreover, it has been demonstrated that seismic response in terms of interstory drifts was effectively mitigated with supplemental damping when added up to a certain level. Exceeding the supplemental damping from this level did not contribute to additional mitigation of the seismic response of the considered structure. In addition, it was found that the supplemental damping increased the total acceleration of the considered structure at all floor levels, which indicates that for irregular tall structures of this type, VE dampers were only a good retrofitting measure for earthquake induced interstory deformations and their use may not be suitable for acceleration sensitive structures. Overall, the research findings demonstrate how seismic hazards to these types of structures can be reduced by introducing additional damping into the structure.
基金A key project of National Foundation of Natural Science (40533015)Foundation for Meteorological Research of Jiangsu Province (K200715)a project of Foundation for Fundamental Theoretic Research of Institute of Meteorology,PLA University of Science and Technology
文摘The structural characteristics of 2004 typhoon Aere's precipitation are analyzed using the high-resolution data from the Tropical Rainfall Measuring Mission(TRMM) of the National Aeronautics Space Administration(NASA).It is found that the typhoon's characteristics vary at different stages of its development.To analyze the asymmetric causation of precipitation distribution,data from the National Center for Environmental Prediction(NCEP) reanalysis are used to calculate the vertical integral of the water vapor flux vector.The results show that because of this process,along with the unique phenomenon of twin-typhoon circulation,the easterly air current of the typhoon's northern side and the southwesterly air current of its southern side play a joint role in transporting water vapor.Furthermore,its transport effects vary greatly at the different stages of development,showing the peculiarity of the water source for this typhoon process.The distributions of the typhoon convection area—characterized by heavy precipitation and a maximum-value area of the water vapor flux,as well as a strong ascending-motion area—differ at different stages of the typhoon's development.The non-uniform distribution of water vapor flux and the vertical motion bring about asymmetrical distribution of the typhoon precipitation.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61077069 and 61107094)the Innovation Foundation for Excellent Doctoral Candidates of Beijing Jiaotong University, China (Grant No. 2011YJS202)
文摘We present a stable linear-cavity single longitudinal mode （SLM） erbium-doped silica fiber laser. It consists of four fiber Bragg gratings （FBGs） directly written in a section of photosensitive erbium-doped fiber （EDF） to form an asymmetric three-cavity structure. The stable SLM operation at a wavelength of 1545.112 nm with a 3-dB bandwidth of 0.012 nm and an optical signal-to-noise ratio （OSNR） of about 60 dB is verified experimentally. Under laboratory conditions, the performance of a power fluctuation of less than 0.05 dB observed from the power meter for 6 h and a wavelength variation of less than 0.01 nm obtained from the optical spectrum analyzer （OSA） for about 1.5 h are demonstrated. The gain fiber length is no longer limited to only several centimeters for SLM operation because of the excellent mode-selecting ability of the asymmetric three-cavity structure. The proposed scheme provides a simple and cost-effective approach to realizing a stable SLM fiber laser.
基金The National Natural Science Foundation of China (No. 50778078)
文摘An inter-story shear model of asymmetric base-isolated structures incorporating deformation of each isolation bearing was built, and a method to simultaneously simulate bi-directional near-fault and far-field ground motions was proposed. A comparative study on the dynamic responses of asymmetric base-isolated structures under near-fault and far-field ground motions were conducted to investigate the effects of eccentricity in the isolation system and in the superstructures, the ratio of the uncoupled torsional to lateral frequency of the superstructure and the pulse period of near-fault ground motions on the nonlinear seismic response of asymmetric base-isolated structures. Numerical results show that eccentricity in the isolation system makes asymmetric base-isolated structure more sensitive to near-fault ground motions, and the pulse period of near-fault ground motions plays an import role in governing the seismic responses of asymmetric base-isolated structures.
基金This work is supported by the State Key for Strength and Vibration of Mechanical Structures of Xi’an Jiaotong University(No.SV2018-KF-32)the Natural Science Foundation of Guangdong Province of China(2020A1515011064).
文摘Based on the symmetric re-entrant honeycomb(S-RH)structure with negative Poisson’s ratios,a novel asymmetric and rotatable re-entrant honeycomb(AR-RH)structure was proposed.Both the S-RH structure and AR-RH structure were produced by the 3D printing technology.Through experimental test and finite element simulation,the deformation mechanism and energy absorption characteristics of the AR-RH structure and the S-RH structure with negative Poisson’s ratios at different impact velocities were compared.The experimental test and finite element simulation results show that the novel AR-RH structure with negative Poisson’s ratios has stronger energy absorption capacity than the S-RH structure,and it has been verified that the rotatability of AR-RH can indeed absorb energy.Furthermore,the degree of asymmetry of the AR-RH structure was discussed.
基金supported by the National Natural Science Foundation of China (Nos.61674142 and 62041502)。
文摘In this paper, an asymmetric array structure of space laser communication receiver is proposed. This structure can greatly reduce alignment requirement, and lighten the signal strength jitter caused by atmospheric turbulence. A prototype of the proposed structure is fabricated and a 2.5 Mbit/s on-off keying(OOK) modulated demonstration link over 40 m free space is built. This asymmetric array structure can effectively collect optical signal while rotating in a window angle of ±17°, and the bit error ratio(BER) keeps zero.
文摘Compound Co_3(o-HOC_6H_4S)_2(o-OC_6H_4S)_2(PEt_3)_3 was obtained by reaction of CoCl_2, o-HOC_6H_4SH(H_2mD)and PEt_3 in ethanol in the presence of NaOCH_3.The three Co atoms are triangularly arranged and asymmetrically bridged by four S and one O atoms from the four H_2mp ligands and terminally ligated by one O and three P atoms.Two free hydroxyl groups form two internal hydrogen bonds with adjacent oxo donor atoms.
基金financially supported by the National Natural Science Foundation of China(No.51672151)973 Program of China(No.2014CB932401)
文摘A flexible asymmetric supercapacitor with high energy density was constructed by using a flexible substrate of carbonized silk-fabrics decorated with carbon nanotube, electroplating MnO2 nanosheets and dip-coating activated carbon powders as the positive and the negative electrodes, respectively. By controlling the electroplating time, the MnO2 nanosheets can be self-assembled to honeycomb structure and showed excellent electrochemical performance in 1 mol/L Na2SO4 electrolyte with SC950-EP30 performing the best. It exhibited a high specific capacitance（1110.85 F/g at a current density of 1 A/g based on the mass of MnO2） and superior rate capability（77.44% capacity retention from 1 A/g to 10 A/g）.Thus, the optimal asymmetric device assembled with this material as positive electrode can deliver a maximum energy density of 43.84 Wh/kg and a maximum power density of 6.62 kW/kg.
基金Project supported by the National Natural Science Foundation of China (No. 60879002)the Tianjin Support Plan of China(No. 10ZCKFGX03800)
文摘The effects of journal misalignment on a journal bearing caused by an asymmetric rotor structure are presented in this study.A new model considering the asymmetric deflection is applied.Also,the thermo-hydrodynamic of the oil film in the journal bearing and straightforward elasticity theory are considered in the analysis.Based on the structure stiffness equivalent characteristic,a simple stepped shaft can reflect the entire complex structure model.The existing lubrication model,which does not consider this angle component,is not very precise for journal bearings.Film pressure,misalignment angle,velocity field,oil leakage,and temperature field were calculated and compared in the journal bearing analysis.The results indicate that bearing performances are greatly affected by misalignment caused by the asymmetric structure.A simple stepped shaft can effectively represent a misaligned journal bearing in a rotor-bearing system.
基金the National Natural Science Foundation of China(22178120)the China Postdoctoral Science Foundation(2022TQ0173,2023M731922,2022M720076,BX20220182,2023M731921,2023M731919,2023M741919).
文摘Solid-state lithium metal batteries(SSLMBs)show great promise in terms of high-energy-density and high-safety performance.However,there is an urgent need to address the compatibility of electrolytes with high-voltage cathodes/Li anodes,and to minimize the electrolyte thickness to achieve highenergy-density of SSLMBs.Herein,we develop an ultrathin(12.6μm)asymmetric composite solid-state electrolyte with ultralight areal density(1.69 mg cm^(−2))for SSLMBs.The electrolyte combining a garnet(LLZO)layer and a metal organic framework(MOF)layer,which are fabricated on both sides of the polyethylene(PE)separator separately by tape casting.The PE separator endows the electrolyte with flexibility and excellent mechanical properties.The LLZO layer on the cathode side ensures high chemical stability at high voltage.The MOF layer on the anode side achieves a stable electric field and uniform Li flux,thus promoting uniform Li^(+)deposition.Thanks to the well-designed structure,the Li symmetric battery exhibits an ultralong cycle life(5000 h),and high-voltage SSLMBs achieve stable cycle performance.The assembled pouch cells provided a gravimetric/volume energy density of 344.0 Wh kg^(−1)/773.1 Wh L^(−1).This simple operation allows for large-scale preparation,and the design concept of ultrathin asymmetric structure also reveals the future development direction of SSLMBs.
基金support from the Shuguang Program supported by Shanghai Education Development Foundation and Shanghai Municipal Education Commission(18SG035)Shanghai Engineering Research Center of Advanced Thermal Functional Materials(Shanghai Polytechnic University).
文摘Carbon-and silica-based nanomaterials possess a set of merits including large surface area,good structural stability,diversified morphology,adjustable structure,and biocompatibility.These outstanding features make them widely applied in different fields.However,limited by the surface free energy effect,the current studies mainly focus on the symmetric structures,such as nanospheres,nanoflowers,nanowires,nanosheets,and core-shell structured composites.By comparison,the asymmetric structure with ingenious adjustability not only exhibits a larger effective surface area accompanied with more active sites,but also enables each component to work independently or corporately to harness their own merits,thus showing the unusual performances in some specific applications.The current review mainly focuses on the recent progress of design principles and synthesis methods of asymmetric carbon-and silica-based nanomaterials,and their applications in energy storage,catalysis,and biomedicine.Particularly,we provide some deep insights into their unique advantages in related fields from the perspective of materials’structure-performance relationship.Furthermore,the challenges and development prospects on the synthesis and applications of asymmetric carbon-and silica-based nanomaterials are also presented and highlighted.
基金supported by the National Key Research and Development Program of China(2020YFB1804900 and 2022YFE0210900)the Fundamental Research Funds for the Central Universities(2242022k60008 and 2242022k30003)+2 种基金the National Natural Science Foundation of China(62301152 and 61627801)the Youth Talent Promotion Foundation of Jiangsu Science and Technology Association(TJ-2023-074)the Startup Research Fund of Southeast University(RF1028623286).
文摘In this article,a single-board integrated millimeter-wave(mm-Wave)asymmetric full-digital beamforming(AFDBF)array is developed for beyond-fifth-generation(B5G)and sixth-generation(6G)communications.The proposed integrated array effectively addresses the challenge of arranging a large number of ports in a full-digital array by designing vertical connections in a three-dimensional space and successfully integrating full-digital transmitting(Tx)and receiving(Rx)arrays independently in a single board.Unlike the traditional symmetric array,the proposed asymmetric array is composed of an 8×8 Tx array arranged in a square shape and an 8+8 Rx array arranged in an L shape.The center-to-center distance between two adjacent elements is 0.54k0 for both the Tx and Rx arrays,where k0 is the free-space wavelength at 27 GHz.The proposed AFDBF array possesses a more compact structure and lower system hardware cost and power consumption compared with conventional brick-type full-digital arrays.In addition,the energy efficiency of the proposed AFDBF array outperforms that of a hybrid beamforming array.The measurement results indicate that the operating frequency band of the proposed array is 24.25–29.50 GHz.An eight-element linear array within the Tx array can achieve a scanning angle ranging from-47°to+47°in both the azimuth and the elevation planes,and the measured scanning range of each eight-element Rx array is–45°to+45°.The measured maximum effective isotropic radiated power(EIRP)of the eight-element Tx array is 43.2 dBm at 28.0 GHz(considering the saturation point).Furthermore,the measured error vector magnitude(EVM)is less than 3%when 64-quadrature amplitude modulation(QAM)waveforms are used.
基金financially supported by the National Natural Science Foundation of China(Nos.52363004,51963003 and 52263003)Guizhou Provincial Science and Technology Projects(Nos.ZK[2022]Maj019 and ZK[2023]-Nor160)Guizhou Province High-level Innovative Talent Selection and Training Program(No.GCC2022-046)。
文摘Since electromagnetic pollution is detrimental to human health and the environment,numerous efforts have been successively made to achieve excellent electromagnetic interference shielding effectiveness(EMI SE)via designing the hierarchical structures for electromagnetic interference(EMI)shielding polymer composites.Among the plentiful structures,the asymmetric structures are currently a hot spot,principally categorizing into multi-layered,porous,fibrous,and segregated asymmetric structures,which endows the high EMI shielding performance for polymer composites incorporated with magnetic,conductive,and/or dielectric micro/nano-fillers,due to the“absorption-reflection-reabsorption”shielding mechanism.Therefore,this review provides the retrospection and summary of the efforts with respect to abundant asymmetric structures and multifunctional micro/nano-fillers for enhancing EMI shielding properties,which is conducive to the booming development of polymeric EMI shielding materials for the promising prospect in modern electronics and 5-generation(5G)technology.
基金financially supported by the National Natural Science Foundation of China(Nos.21274007 and 51021064)the Project of Science and Technology Innovation Platform of Beijing Municipal Education Commission(No.PXM2012-014213-000025)+1 种基金the Tribology Science Fund of State Key Laboratory of Tribology(No.SKLTKF12A10)Beijing Technology and Business University Natural Science Youth Foundation(No.QNJJ2012-29)
文摘A novel asymmetric Ni/PVC film has been developed by solution casting method. The structure, electrical conductivity, electromagnetic interference （EMI） shielding, and impact resistance were investigated. The results showed that the Ni particles were asymmetrically distributed along the thickness direction in the film. The top surface resistivity increased with film thickness, while the bottom surface exhibited the different trend. EMI shielding effectiveness （SE） depended on formation of closed packed conductive Ni network, which was influenced by both Ni content and film thickness. A linear relationship was observed between EMI SE and film thickness. The films with lower Ni content showed the faster increasing rate of EMI SE with film thickness. Some of the films show appreciably high EMI SE （〉 40 dB）, indicating the promising application in EMI shielding field. Moreover, the films exhibit different impact performance under different impacting directions. All the experimental facts demonstrate that the asymmetric structure endows the film achieving high-performance EMI shielding function.
