A compact high-scanning-rate circular-polarized leaky-wave antenna(LWA)based on a meandering substrate integrated waveguide(SIW)with defected ground structures(DGSs)is presented.The meandering-SIW design is employed t...A compact high-scanning-rate circular-polarized leaky-wave antenna(LWA)based on a meandering substrate integrated waveguide(SIW)with defected ground structures(DGSs)is presented.The meandering-SIW design is employed to enhance the beam scanning rate,while circular polarization is achieved by etchingπ-shaped slots on the top plane.To suppress the open stopband at broadside,offset circular DGSs are periodically etched on the ground plane.Their impact on the reflection coefficient and axial ratio is then analyzed through a parametric study.A prototype of the antenna is simulated,fabricated,and measured.Both simulated and measured results indicate a scanning rate of approximately 8.6,with continuous beam scanning from-41°to 59°across the 11.3-12.7 GHz operating band.The antenna maintains an axial ratio below 3 dB within the 11.5-12.3 GHz range.This design shows promise for use in wireless communication systems,particularly in environments with increasingly limited spectrum resources.展开更多
In this paper, the control performance is investigated of Circular Tuned Liquid Column Dampers (CTLCD) over torsional response of offshore platform structures excited by ground motions. Based on the equation of motion...In this paper, the control performance is investigated of Circular Tuned Liquid Column Dampers (CTLCD) over torsional response of offshore platform structures excited by ground motions. Based on the equation of motion for the CTLCD-structure system, the optimal control parameters of CTLCD are given through some derivations on the supposition that the ground motion is a stochastic process. The influence of systematic parameters on the equivalent damping ratio of the structures is analyzed with purely torsional vibration and translational-torsional coupled vibration, respectively. The results show that the Circular Tuned Liquid Column Damper (CTLCD) is an effective torsional response control device.展开更多
We report a high-performance active image sensor pixel design by utilizing amorphous-indium-gallium-zinc-oxide(aIGZO) thin-film transistors(TFTs) with a circular structure. The TFT, configured with the inner electrode...We report a high-performance active image sensor pixel design by utilizing amorphous-indium-gallium-zinc-oxide(aIGZO) thin-film transistors(TFTs) with a circular structure. The TFT, configured with the inner electrode as source and outer electrode as drain, typically exhibits good saturation electrical characteristics, where the device has a constant drive current despite variations in drain voltage. Due to the very high output resistance exhibited by this asymmetric TFT structure with a circular shape, the pixel circuit considered here in common-drain configuration provides a higher gain of operation than a pixel circuit implemented with rectangular a-IGZO TFTs. They can be used as driving TFTs in active image sensor circuits. They are, therefore,good candidates for digital X-ray detectors in applications such as medical diagnostic procedures.展开更多
Hamiltonian structure of a rigid body in a circular orbit is established in this paper. With the reduction technique, the Hamiltonian structure of a rigid body in a circular orbit is derived from Lie-Poisson structure...Hamiltonian structure of a rigid body in a circular orbit is established in this paper. With the reduction technique, the Hamiltonian structure of a rigid body in a circular orbit is derived from Lie-Poisson structure of semidirect product, and Hamiltonian is derived from Jacobi's integral. The above method can be generalized to establish the Hamiltonian structure of a rigid body with a flexible attachment in a circular or- bit. At last, an example of stability analysis is given.展开更多
In this paper,we present a 1.8-kV circular AlGaN/GaN/AlGaN double-heterostructure high electron mobility transistor(DH HEMT)with a gate-drain spacing L_(GD)=18.8μm.Compared with the regular DH HEMT,our circular struc...In this paper,we present a 1.8-kV circular AlGaN/GaN/AlGaN double-heterostructure high electron mobility transistor(DH HEMT)with a gate-drain spacing L_(GD)=18.8μm.Compared with the regular DH HEMT,our circular structure has a high average breakdown electric-field strength that increases from 0.42 MV/cm to 0.96 MV/cm.The power figure of meritV_(BR)~2/RON for the circular HEMT is as high as 1.03×10~9 V^2·Ω^(-1)·cm^(-2).The divergence of electric field lines at the gate edge and no edge effect account for the breakdown enhancement capability of the circular structure.Experiments and analysis indicate that the circular structure is an effective method to modulate the electric field.展开更多
Based on the starch hydrolysis reaction accelerated by microwave irradiation with α-amylase, the circular dichroism （CD） and secondary structure changes of α-amylase under the condition of microwave irradiation an...Based on the starch hydrolysis reaction accelerated by microwave irradiation with α-amylase, the circular dichroism （CD） and secondary structure changes of α-amylase under the condition of microwave irradiation and water bath were studied by circular dichroism spectra. The results showed that, both the peak heights （at 2=193 nm） of the CD spectra of the samples treated by microwave irradiation and water bath reduced. The reduced rate by microwave irradiation ranged from 140% to 220%, while the reduced rate by water bath ranged from 60% to 140%. The peak of the sample treated by microwave irradiation for 60 min disappeared at λ=193 nm, while the sample showed a wake peak by water bath. The peak position by microwave irradiation emerged a blue shift in the range of 5-8 nm at λ=204 nm and λ=220 nm, while it emerged in the range of 3-5 nm by water bath. With time going on, the microwave irradiation and water bath have prompted the secondary structure of α-helix, β-sheet, β-turn and the mutual transformations of random coil, but the trends were different.展开更多
The results of design and experiment of a submerged semi-circular breakwater at the Yangtze estuary show that the submerged structure will be unsafe when the general empirical wave force formula for semi-circular brea...The results of design and experiment of a submerged semi-circular breakwater at the Yangtze estuary show that the submerged structure will be unsafe when the general empirical wave force formula for semi-circular breakwater is used in design. Therefore, a new calculation method for the wave forces acting on a submerged semi-circular structure is given in this paper, in which the wave force acting on the inside circumference of semi-circular arch is included, and the phase modification coefficient in the general empirical formula is adjusted as well. The new wave force calculation method has been Verified by the results of seven related physical model tests and adopted in the design of the south esturary jetty of the first stage project of Deep Channel Improvement Project of the Yangtze River Estuary, the total jetty length being 17.5 km.展开更多
The structural feature shown on a remote sensing image is a synthetic result ofcombination of the deformations produced during the entire geological history of an area.Therefore, the respective tectonic stress field o...The structural feature shown on a remote sensing image is a synthetic result ofcombination of the deformations produced during the entire geological history of an area.Therefore, the respective tectonic stress field of each of the different stages in the complexdeformation of an area can be reconstructed in three steps: (1) geological structures formed atdifferent times are distinguished in remote sensing image interpretation; (2) structuraldeformation fields at different stages are determined by analyzing relationships betweenmicrostructures (joints and fractures) and the related structures (folds and faults); and (3)tectonic stress fields at different stages are respectively recovered through a study of the featuresof structural deformation fields in different periods. Circular structures and related circlular and radial joints are correlated in space to con-cealed structural rises. The authors propose a new method for establishing a natural model ofthe concealed structural rises and calculating the tectonic stress field by using quantitative dataof the remote sensing information of circular structures and related linear structures.展开更多
Based on the transfer matrix method and the virtual source simulation technique, this paper proposes a novel semi-analytical and semi-numerical method for solving 2-D sound- structure interaction problems under a harm...Based on the transfer matrix method and the virtual source simulation technique, this paper proposes a novel semi-analytical and semi-numerical method for solving 2-D sound- structure interaction problems under a harmonic excitation.Within any integration segment, as long as its length is small enough,along the circumferential curvilinear coordinate,the non- homogeneous matrix differential equation of an elastic ring of complex geometrical shape can be rewritten in terms of the homogeneous one by the method of extended homogeneous capacity proposed in this paper.For the exterior fluid domain,the multi-circular virtual source simulation technique is adopted.The source density distributed on each virtual circular curve may be ex- panded as the Fourier's series.Combining with the inverse fast Fourier transformation,a higher accuracy and efficiency method for solving 2-D exterior Helmholtz's problems is presented in this paper.In the aspect of solution to the coupling equations,the state vectors of elastic ring induced by the given harmonic excitation and generalized forces of coefficients of the Fourier series can be obtained respectively by using a high precision integration scheme combined with the method of extended homogeneous capacity put forward in this paper.According to the superposition princi- ple and compatibility conditions at the interface between the elastic ring and fluid,the algebraic equation of system can be directly constructed by using the least square approximation.Examples of acoustic radiation from two typical fluid-loaded elastic rings under a harmonic concentrated force are presented.Numerical results show that the method proposed is more efficient than the mixed FE-BE method in common use.展开更多
The human telomere sequence (TTAGGG)4 folds into an unusual conformation possessing three G-tetrads linked by TTA loops. The first loop is a propeller loop while the second and third loops are transverse loops. Using ...The human telomere sequence (TTAGGG)4 folds into an unusual conformation possessing three G-tetrads linked by TTA loops. The first loop is a propeller loop while the second and third loops are transverse loops. Using Circular Dichroism (CD) spectroscopy, we have investigated the effect of sequence context on the structures and stabilities of intramolecular G-quadruplexes related to the human telomere sequence by considering all permutations of T and A within the loops. The results indicate that changing only one base in any one loop can have a dramatic effect on the conformation of the quadruplex as well as its melting temperature, Tm. Thus, each sequence studied has a unique CD spectrum and Tm. In general, variants with a modified second loop are the most stable while the wild type sequence is the least stable. The observed difference in CD spectra and melting temperature are discussed in terms of base stacking within the loop and stacking of the loop bases with adjacent G-tetrads.展开更多
The effects of the interaction between a gallery lining and surrounding ground are evaluated. The gallery is circular with constant thickness and surrounding ground as geotechnical characteristics is soft one. Two typ...The effects of the interaction between a gallery lining and surrounding ground are evaluated. The gallery is circular with constant thickness and surrounding ground as geotechnical characteristics is soft one. Two types of ground are successively considered with bulk modulus K = 9,260 kPa and K = 4,630 kPa. The analysis is carried out for a gallery with 3.80 m inner diameter and 25 cm thickness. This under construction is part of the irrigation system of the ＂Los Rios＂ county （Ecuador）. Comprehensive computations in various hypotheses pointed out the significant effects of the interaction. The sectional stresses （M, N） in the gallery lining embedded in soft ground depend mainly of the gallery depth versus ground surface. Contrary, the mechanical characteristics of the surrounding ground resulted to have little influence.展开更多
In this paper,a type of reinforcing structure for composite shell with single and through hole is presented.The experimental tests for the composite shells without hole,with single hole and reinforced structure,with t...In this paper,a type of reinforcing structure for composite shell with single and through hole is presented.The experimental tests for the composite shells without hole,with single hole and reinforced structure,with through hole and reinforced structure subjected to hydrostatic pressure were carried out by the designed experimental test system.The mechanical responses of the composite shells under hydrostatic pressure are obtained by the high-speed camera and strain measurement.The results show that the entire deformation process of the shell can be divided into three:uniform compression,"buckling mode formation"and buckling.The"buckling mode formation"process is captured and reported for the first time.For the composite shell with single hole,the proposed reinforcing structure has a significant reinforcement effect on the shell and the buckling capacity of the shell is not weaker than the complete composite shell.For the composite shell with through hole,sealing effect can be achieved by the proposed reinforcing structure,but the buckling capacity of the shell after reinforcement can only reach 77%of the original buckling capacity.展开更多
A compact low-profile dual-band Circularly Polarized(CP)microstrip antenna is proposed for the Bei Dou Navigation Satellite System(BDS).To achieve dual-band functionality,a single-layer multimode design is employed,in...A compact low-profile dual-band Circularly Polarized(CP)microstrip antenna is proposed for the Bei Dou Navigation Satellite System(BDS).To achieve dual-band functionality,a single-layer multimode design is employed,incorporating F-,L-,and T-shaped slots at the corners for CP performance.Additionally,a Defected Ground Structure(DGS)is implemented to further enhance the antenna's efficiency.A detailed parameter analysis is conducted to optimize the antenna's size and performance balance.After optimization,the final dimensions of the antenna are minimized while still meeting the design requirements.The prototype of the optimized antenna is fabricated and tested,demonstrating coverage of frequency bands from 1.182 GHz to 1.217 GHz and 1.547 GHz to 1.569 GHz.The antenna effectively supports dual-band CP for B1I and B2b frequency bands.A performance metric,the Ratio of relative Bandwidth to Volume(RBV),is introduced to evaluate the antenna's efficiency.Compared to similar designs,the proposed antenna offers a smaller size without sacrificing performance,making it well-suited for BDS airborne applications.展开更多
Semiconductor quantum dots(QDs)with circularly polarized luminescence(CPL)characteristics hold significant promise for a range of applications,including information security,three-dimensional(3D)display,quantum comput...Semiconductor quantum dots(QDs)with circularly polarized luminescence(CPL)characteristics hold significant promise for a range of applications,including information security,three-dimensional(3D)display,quantum computing,and spintronics.Recent approaches combining QDs with chiral liquid crystal assemblies have demonstrated amplified CPL performance(specifically,luminescence dissymmetry factor,glum>10-1).However,the inherent fluidity and alignment sensitivity of chiral liquid crystals,along with QD aggregation and phase separation,continue to hinder the uniformity and long-term stability of these systems.In this work,we developed an in-situ helical co-assembly polymerization strategy that covalently incorporated InP-based QDs into chiral liquid crystal polymer templates,forming QD-based polymeric superhelical structures.We synthesized high-quality InP/ZnSeS/ZnS QDs and functionalized their surfaces with polymerizable groups to enable reactivity.By precisely tuning the photonic bandgap of the chiral liquid crystal polymers,we achieved chiral parented templates with high chiroptical activity overlapping full-visible-spectrum.Through covalent crosslinking with the QDs,a polymer network was formed,resulting in a maximum glum of 1.0.This polymerization-with-assembly approach offers exceptionally flexible and precise control over both the composition and architecture of superhelical materials,paving the way for high-quality CPL materials with broad applications in advanced technologies.展开更多
In this paper, 2-D computational analyses were conducted for unsteady high Reynolds number flows around a smooth circular cylinder in the supercritical and upper-transition flow regimes, i.e. 8.21×104〈Re〈1.54&#...In this paper, 2-D computational analyses were conducted for unsteady high Reynolds number flows around a smooth circular cylinder in the supercritical and upper-transition flow regimes, i.e. 8.21×104〈Re〈1.54×106. The calculations were performed by means of solving the 2-D Unsteady Reynolds-Averaged Navier-Stokes （URANS） equations with a k-ε turbulence model. The calculated results, produced flow structure drag and lift coefficients, as well as Strouhal numbers. The findings were in good agreement with previous published data, which also supplied us with a good understanding of the flow across cylinders of different high Reynolds numbers. Meanwhile, an effective measure was presented to control the lift force on a cylinder, which points the way to decrease the vortex induced vibration of marine structure in future.展开更多
The mpox(formerly known as monkeypox)outbreak was declared a Public Health Emergency of International Concern(PHEIC)by the World Health Organization(WHO)on two separate occasions,with the PHEIC status remaining in eff...The mpox(formerly known as monkeypox)outbreak was declared a Public Health Emergency of International Concern(PHEIC)by the World Health Organization(WHO)on two separate occasions,with the PHEIC status remaining in effect following the second declaration on August 14,2024[1,2].The causative agent,mpox virus(MPXV),is a double-stranded DNA virus belonging to the genus Orthopoxvirus within the family Poxviridae[3].MPXV produce two antigenically distinct infectious virion forms:intracellular mature virions(IMVs)and extracellular enveloped virions(EEVs).Currently,the prevention and control of mpox have several challenges,including sustained human-to-human transmission,the increasing frequency and geographic spread of outbreaks,and ongoing viral adaptive evolution[4].These challenges are likely driven by the discontinuation of smallpox vaccination and the waning immunity in current population cohorts.展开更多
The second-harmonic generation （SHG） circular dichroism in the light of reflection from chiral films of tripod-like chiral molecules is investigated. The expressions of the second-harmonic generation circular dichro...The second-harmonic generation （SHG） circular dichroism in the light of reflection from chiral films of tripod-like chiral molecules is investigated. The expressions of the second-harmonic generation circular dichroism are derived from our presented three-coupled-oscillator model for the tripod-like chiral molecules. Spectral dependence of the circular dichroism of SHG from film surface composed of tripod-like chiral molecules is simulated numerically and analysed. Influence of ehiral parameters on the second-harmonic generation circular dichroism spectrum in chiral films is studied. The result shows that the second-harmonic generation circular dichroism is a sensitive method of detecting chirality compared with the ordinary circular dichroism in linear optics. All of our work indicates that the classical molecular models are very effective to explain the second-harmonic generation circular dichroism of chiral molecular system. The classical molecular model theory can give us a clear physical picture and brings us very instructive information about the link between the molecular configuration and the nonlinear processes.展开更多
The inclusion of vertically-suspended environmental enrichment in circular tanks has produced substantial benefits during fish rearing. This study examined the tank water velocity profiles of four different vertically...The inclusion of vertically-suspended environmental enrichment in circular tanks has produced substantial benefits during fish rearing. This study examined the tank water velocity profiles of four different vertically-suspended structures?(rod array, extended rod array, single angle array, double angle array) and a control (no environmental enrichment) at two incoming water velocities (18.3 cm/s and 54.9 cm/s) in 1.8-m diameter circular tanks. At both of the incoming water velocities, overall water velocities throughout the tank were significantly reduced with the addition of any environmental enrichment in comparison to the control. In addition, the overall water velocities in the double angle array were significantly lower than the other three enrichment treatments. The pattern of significant reductions in velocity with the use of any environmental enrichment, with further significant velocity reductions in the double angle treatment, was repeated when the data were?combined for each sampling depth, radius from the center, and degree (circular arc). Although considerable variation in water velocity was observed at each specific sampling location with both incoming velocities, significantly lower velocities?were observed at nearly every sampling location with the addition of any environmental enrichment to the circular tank. In addition, the double angle array consistently produced the lowest velocities among the environmental enrichment treatments. The changes in velocity profiles from vertically-suspended?environmental enrichment may be at least partially-responsible for the frequently-observed improvements in fish growth.展开更多
Abstract A vortex ring impacting a three-dimensional circular cylinder is studied using large eddy simulation （LES） for a Reynolds number Re = 4 × 10^4 based on the initial translation speed and diameter of the...Abstract A vortex ring impacting a three-dimensional circular cylinder is studied using large eddy simulation （LES） for a Reynolds number Re = 4 × 10^4 based on the initial translation speed and diameter of the vortex ring. We have investigated the evolution of vortical structures and identified three typical evolution phases. When the primary vortex closely approaches to the cylinder, a secondary vortex is generated and its segment parts move inward to the primary vortex ring. Then two large-scale loop-like vortices are formed to evolve in opposite directions. Thirdly, the two loop-like vortices collide with each other to form complicated small-scale vortical structures. Moreover, a series of hair-pin vortices are generated due to the stretching and deformation of the tertiary vortex. The trajectories of vortical structures and the relevant evolution speeds are analyzed. The total kinetic energy and enstrophy are investigated to reveal their properties relevant to the three evolution phases.展开更多
文摘A compact high-scanning-rate circular-polarized leaky-wave antenna(LWA)based on a meandering substrate integrated waveguide(SIW)with defected ground structures(DGSs)is presented.The meandering-SIW design is employed to enhance the beam scanning rate,while circular polarization is achieved by etchingπ-shaped slots on the top plane.To suppress the open stopband at broadside,offset circular DGSs are periodically etched on the ground plane.Their impact on the reflection coefficient and axial ratio is then analyzed through a parametric study.A prototype of the antenna is simulated,fabricated,and measured.Both simulated and measured results indicate a scanning rate of approximately 8.6,with continuous beam scanning from-41°to 59°across the 11.3-12.7 GHz operating band.The antenna maintains an axial ratio below 3 dB within the 11.5-12.3 GHz range.This design shows promise for use in wireless communication systems,particularly in environments with increasingly limited spectrum resources.
文摘In this paper, the control performance is investigated of Circular Tuned Liquid Column Dampers (CTLCD) over torsional response of offshore platform structures excited by ground motions. Based on the equation of motion for the CTLCD-structure system, the optimal control parameters of CTLCD are given through some derivations on the supposition that the ground motion is a stochastic process. The influence of systematic parameters on the equivalent damping ratio of the structures is analyzed with purely torsional vibration and translational-torsional coupled vibration, respectively. The results show that the Circular Tuned Liquid Column Damper (CTLCD) is an effective torsional response control device.
文摘We report a high-performance active image sensor pixel design by utilizing amorphous-indium-gallium-zinc-oxide(aIGZO) thin-film transistors(TFTs) with a circular structure. The TFT, configured with the inner electrode as source and outer electrode as drain, typically exhibits good saturation electrical characteristics, where the device has a constant drive current despite variations in drain voltage. Due to the very high output resistance exhibited by this asymmetric TFT structure with a circular shape, the pixel circuit considered here in common-drain configuration provides a higher gain of operation than a pixel circuit implemented with rectangular a-IGZO TFTs. They can be used as driving TFTs in active image sensor circuits. They are, therefore,good candidates for digital X-ray detectors in applications such as medical diagnostic procedures.
基金The projeet supported by National Natural Science Foundation of China and Aeronautic Science Foundation.
文摘Hamiltonian structure of a rigid body in a circular orbit is established in this paper. With the reduction technique, the Hamiltonian structure of a rigid body in a circular orbit is derived from Lie-Poisson structure of semidirect product, and Hamiltonian is derived from Jacobi's integral. The above method can be generalized to establish the Hamiltonian structure of a rigid body with a flexible attachment in a circular or- bit. At last, an example of stability analysis is given.
基金Project supported by the National Key Research and Development Program of China(Grant No.2016YFB0400100)the National Natural Science Foundation of China(Grant Nos.11435010,61474086,and 61804125)the Natural Science Basic Research Program of Shaanxi Province,China(Grant No.2016ZDJC-02)
文摘In this paper,we present a 1.8-kV circular AlGaN/GaN/AlGaN double-heterostructure high electron mobility transistor(DH HEMT)with a gate-drain spacing L_(GD)=18.8μm.Compared with the regular DH HEMT,our circular structure has a high average breakdown electric-field strength that increases from 0.42 MV/cm to 0.96 MV/cm.The power figure of meritV_(BR)~2/RON for the circular HEMT is as high as 1.03×10~9 V^2·Ω^(-1)·cm^(-2).The divergence of electric field lines at the gate edge and no edge effect account for the breakdown enhancement capability of the circular structure.Experiments and analysis indicate that the circular structure is an effective method to modulate the electric field.
基金Project(08A080) supported by the Scientific Research Fund of Hunan Provincial Education Department,China
文摘Based on the starch hydrolysis reaction accelerated by microwave irradiation with α-amylase, the circular dichroism （CD） and secondary structure changes of α-amylase under the condition of microwave irradiation and water bath were studied by circular dichroism spectra. The results showed that, both the peak heights （at 2=193 nm） of the CD spectra of the samples treated by microwave irradiation and water bath reduced. The reduced rate by microwave irradiation ranged from 140% to 220%, while the reduced rate by water bath ranged from 60% to 140%. The peak of the sample treated by microwave irradiation for 60 min disappeared at λ=193 nm, while the sample showed a wake peak by water bath. The peak position by microwave irradiation emerged a blue shift in the range of 5-8 nm at λ=204 nm and λ=220 nm, while it emerged in the range of 3-5 nm by water bath. With time going on, the microwave irradiation and water bath have prompted the secondary structure of α-helix, β-sheet, β-turn and the mutual transformations of random coil, but the trends were different.
文摘The results of design and experiment of a submerged semi-circular breakwater at the Yangtze estuary show that the submerged structure will be unsafe when the general empirical wave force formula for semi-circular breakwater is used in design. Therefore, a new calculation method for the wave forces acting on a submerged semi-circular structure is given in this paper, in which the wave force acting on the inside circumference of semi-circular arch is included, and the phase modification coefficient in the general empirical formula is adjusted as well. The new wave force calculation method has been Verified by the results of seven related physical model tests and adopted in the design of the south esturary jetty of the first stage project of Deep Channel Improvement Project of the Yangtze River Estuary, the total jetty length being 17.5 km.
基金This study was sponsored by The Open Research Laboratory of Quantitative Prediction,Exploration and Assessment of Mineral Resources,MGMR,China.
文摘The structural feature shown on a remote sensing image is a synthetic result ofcombination of the deformations produced during the entire geological history of an area.Therefore, the respective tectonic stress field of each of the different stages in the complexdeformation of an area can be reconstructed in three steps: (1) geological structures formed atdifferent times are distinguished in remote sensing image interpretation; (2) structuraldeformation fields at different stages are determined by analyzing relationships betweenmicrostructures (joints and fractures) and the related structures (folds and faults); and (3)tectonic stress fields at different stages are respectively recovered through a study of the featuresof structural deformation fields in different periods. Circular structures and related circlular and radial joints are correlated in space to con-cealed structural rises. The authors propose a new method for establishing a natural model ofthe concealed structural rises and calculating the tectonic stress field by using quantitative dataof the remote sensing information of circular structures and related linear structures.
基金Project supported by the National Natural Science Foundation of China (No.10172038)
文摘Based on the transfer matrix method and the virtual source simulation technique, this paper proposes a novel semi-analytical and semi-numerical method for solving 2-D sound- structure interaction problems under a harmonic excitation.Within any integration segment, as long as its length is small enough,along the circumferential curvilinear coordinate,the non- homogeneous matrix differential equation of an elastic ring of complex geometrical shape can be rewritten in terms of the homogeneous one by the method of extended homogeneous capacity proposed in this paper.For the exterior fluid domain,the multi-circular virtual source simulation technique is adopted.The source density distributed on each virtual circular curve may be ex- panded as the Fourier's series.Combining with the inverse fast Fourier transformation,a higher accuracy and efficiency method for solving 2-D exterior Helmholtz's problems is presented in this paper.In the aspect of solution to the coupling equations,the state vectors of elastic ring induced by the given harmonic excitation and generalized forces of coefficients of the Fourier series can be obtained respectively by using a high precision integration scheme combined with the method of extended homogeneous capacity put forward in this paper.According to the superposition princi- ple and compatibility conditions at the interface between the elastic ring and fluid,the algebraic equation of system can be directly constructed by using the least square approximation.Examples of acoustic radiation from two typical fluid-loaded elastic rings under a harmonic concentrated force are presented.Numerical results show that the method proposed is more efficient than the mixed FE-BE method in common use.
文摘The human telomere sequence (TTAGGG)4 folds into an unusual conformation possessing three G-tetrads linked by TTA loops. The first loop is a propeller loop while the second and third loops are transverse loops. Using Circular Dichroism (CD) spectroscopy, we have investigated the effect of sequence context on the structures and stabilities of intramolecular G-quadruplexes related to the human telomere sequence by considering all permutations of T and A within the loops. The results indicate that changing only one base in any one loop can have a dramatic effect on the conformation of the quadruplex as well as its melting temperature, Tm. Thus, each sequence studied has a unique CD spectrum and Tm. In general, variants with a modified second loop are the most stable while the wild type sequence is the least stable. The observed difference in CD spectra and melting temperature are discussed in terms of base stacking within the loop and stacking of the loop bases with adjacent G-tetrads.
文摘The effects of the interaction between a gallery lining and surrounding ground are evaluated. The gallery is circular with constant thickness and surrounding ground as geotechnical characteristics is soft one. Two types of ground are successively considered with bulk modulus K = 9,260 kPa and K = 4,630 kPa. The analysis is carried out for a gallery with 3.80 m inner diameter and 25 cm thickness. This under construction is part of the irrigation system of the ＂Los Rios＂ county （Ecuador）. Comprehensive computations in various hypotheses pointed out the significant effects of the interaction. The sectional stresses （M, N） in the gallery lining embedded in soft ground depend mainly of the gallery depth versus ground surface. Contrary, the mechanical characteristics of the surrounding ground resulted to have little influence.
基金supported by the Ningbo Major Research and Development Plan Project(Grant No.2024Z135)the Natural Science Basic Research Program of Shaanxi Province(Grant No.2024JC-YBMS-322)+1 种基金China Postdoctoral Science Foundation(Grant No.2020M673492)National Natural Science Foundation of China(Grant No.51909219)。
文摘In this paper,a type of reinforcing structure for composite shell with single and through hole is presented.The experimental tests for the composite shells without hole,with single hole and reinforced structure,with through hole and reinforced structure subjected to hydrostatic pressure were carried out by the designed experimental test system.The mechanical responses of the composite shells under hydrostatic pressure are obtained by the high-speed camera and strain measurement.The results show that the entire deformation process of the shell can be divided into three:uniform compression,"buckling mode formation"and buckling.The"buckling mode formation"process is captured and reported for the first time.For the composite shell with single hole,the proposed reinforcing structure has a significant reinforcement effect on the shell and the buckling capacity of the shell is not weaker than the complete composite shell.For the composite shell with through hole,sealing effect can be achieved by the proposed reinforcing structure,but the buckling capacity of the shell after reinforcement can only reach 77%of the original buckling capacity.
基金co-supported by the Natural Science Foundation of Tianjin,China(No.21JCZDJC00860)the Civil Aviation Security Capacity Building Funding Project,China(No.2020[142])。
文摘A compact low-profile dual-band Circularly Polarized(CP)microstrip antenna is proposed for the Bei Dou Navigation Satellite System(BDS).To achieve dual-band functionality,a single-layer multimode design is employed,incorporating F-,L-,and T-shaped slots at the corners for CP performance.Additionally,a Defected Ground Structure(DGS)is implemented to further enhance the antenna's efficiency.A detailed parameter analysis is conducted to optimize the antenna's size and performance balance.After optimization,the final dimensions of the antenna are minimized while still meeting the design requirements.The prototype of the optimized antenna is fabricated and tested,demonstrating coverage of frequency bands from 1.182 GHz to 1.217 GHz and 1.547 GHz to 1.569 GHz.The antenna effectively supports dual-band CP for B1I and B2b frequency bands.A performance metric,the Ratio of relative Bandwidth to Volume(RBV),is introduced to evaluate the antenna's efficiency.Compared to similar designs,the proposed antenna offers a smaller size without sacrificing performance,making it well-suited for BDS airborne applications.
基金supported by the National Key Research and Development Program of China(No.2021YFA1500400)the National Natural Science Foundation of China(Nos.22071226,22471253,and 224B2116)+4 种基金the Hundred Talent Program of the Chinese Academy of Sciences(No.KJ2060007002)the Collaborative Innovation Program of Hefei Science Center,Chinese Academy of Sciences(Nos.CX2060000017 and 2022HSC-CIP016)the Anhui Provincial Natural Science Foundation,China(No.BJ2060190120)the College Student Research Program(No.WW0000000888)the Funding of University of Science and Technology of China(Nos.KY2060000168,YD2060002013,and KY2060000198)。
文摘Semiconductor quantum dots(QDs)with circularly polarized luminescence(CPL)characteristics hold significant promise for a range of applications,including information security,three-dimensional(3D)display,quantum computing,and spintronics.Recent approaches combining QDs with chiral liquid crystal assemblies have demonstrated amplified CPL performance(specifically,luminescence dissymmetry factor,glum>10-1).However,the inherent fluidity and alignment sensitivity of chiral liquid crystals,along with QD aggregation and phase separation,continue to hinder the uniformity and long-term stability of these systems.In this work,we developed an in-situ helical co-assembly polymerization strategy that covalently incorporated InP-based QDs into chiral liquid crystal polymer templates,forming QD-based polymeric superhelical structures.We synthesized high-quality InP/ZnSeS/ZnS QDs and functionalized their surfaces with polymerizable groups to enable reactivity.By precisely tuning the photonic bandgap of the chiral liquid crystal polymers,we achieved chiral parented templates with high chiroptical activity overlapping full-visible-spectrum.Through covalent crosslinking with the QDs,a polymer network was formed,resulting in a maximum glum of 1.0.This polymerization-with-assembly approach offers exceptionally flexible and precise control over both the composition and architecture of superhelical materials,paving the way for high-quality CPL materials with broad applications in advanced technologies.
基金Foundation item： Supported by Supported by the National Natural Science Foundation of China （Grant No. 51009070）.
文摘In this paper, 2-D computational analyses were conducted for unsteady high Reynolds number flows around a smooth circular cylinder in the supercritical and upper-transition flow regimes, i.e. 8.21×104〈Re〈1.54×106. The calculations were performed by means of solving the 2-D Unsteady Reynolds-Averaged Navier-Stokes （URANS） equations with a k-ε turbulence model. The calculated results, produced flow structure drag and lift coefficients, as well as Strouhal numbers. The findings were in good agreement with previous published data, which also supplied us with a good understanding of the flow across cylinders of different high Reynolds numbers. Meanwhile, an effective measure was presented to control the lift force on a cylinder, which points the way to decrease the vortex induced vibration of marine structure in future.
基金supported by the National Key Research and Development Program of China(grant number 2025YFC2311800 to H.W.)the National Natural Science Foundation of China(grant number 32270157 to H.W.)the Beijing Nova Program(to H.W.).
文摘The mpox(formerly known as monkeypox)outbreak was declared a Public Health Emergency of International Concern(PHEIC)by the World Health Organization(WHO)on two separate occasions,with the PHEIC status remaining in effect following the second declaration on August 14,2024[1,2].The causative agent,mpox virus(MPXV),is a double-stranded DNA virus belonging to the genus Orthopoxvirus within the family Poxviridae[3].MPXV produce two antigenically distinct infectious virion forms:intracellular mature virions(IMVs)and extracellular enveloped virions(EEVs).Currently,the prevention and control of mpox have several challenges,including sustained human-to-human transmission,the increasing frequency and geographic spread of outbreaks,and ongoing viral adaptive evolution[4].These challenges are likely driven by the discontinuation of smallpox vaccination and the waning immunity in current population cohorts.
基金Project supported by the excellent Team in Harbin Institute of Technology,Chinathe Natural Science Foundation of Heilongjiang Province,China (Grant No. A200406)
文摘The second-harmonic generation （SHG） circular dichroism in the light of reflection from chiral films of tripod-like chiral molecules is investigated. The expressions of the second-harmonic generation circular dichroism are derived from our presented three-coupled-oscillator model for the tripod-like chiral molecules. Spectral dependence of the circular dichroism of SHG from film surface composed of tripod-like chiral molecules is simulated numerically and analysed. Influence of ehiral parameters on the second-harmonic generation circular dichroism spectrum in chiral films is studied. The result shows that the second-harmonic generation circular dichroism is a sensitive method of detecting chirality compared with the ordinary circular dichroism in linear optics. All of our work indicates that the classical molecular models are very effective to explain the second-harmonic generation circular dichroism of chiral molecular system. The classical molecular model theory can give us a clear physical picture and brings us very instructive information about the link between the molecular configuration and the nonlinear processes.
文摘The inclusion of vertically-suspended environmental enrichment in circular tanks has produced substantial benefits during fish rearing. This study examined the tank water velocity profiles of four different vertically-suspended structures?(rod array, extended rod array, single angle array, double angle array) and a control (no environmental enrichment) at two incoming water velocities (18.3 cm/s and 54.9 cm/s) in 1.8-m diameter circular tanks. At both of the incoming water velocities, overall water velocities throughout the tank were significantly reduced with the addition of any environmental enrichment in comparison to the control. In addition, the overall water velocities in the double angle array were significantly lower than the other three enrichment treatments. The pattern of significant reductions in velocity with the use of any environmental enrichment, with further significant velocity reductions in the double angle treatment, was repeated when the data were?combined for each sampling depth, radius from the center, and degree (circular arc). Although considerable variation in water velocity was observed at each specific sampling location with both incoming velocities, significantly lower velocities?were observed at nearly every sampling location with the addition of any environmental enrichment to the circular tank. In addition, the double angle array consistently produced the lowest velocities among the environmental enrichment treatments. The changes in velocity profiles from vertically-suspended?environmental enrichment may be at least partially-responsible for the frequently-observed improvements in fish growth.
基金supported by the National Natural Science Foundation of China (11132010 and 11072236)the 111 Project (B07033)
文摘Abstract A vortex ring impacting a three-dimensional circular cylinder is studied using large eddy simulation （LES） for a Reynolds number Re = 4 × 10^4 based on the initial translation speed and diameter of the vortex ring. We have investigated the evolution of vortical structures and identified three typical evolution phases. When the primary vortex closely approaches to the cylinder, a secondary vortex is generated and its segment parts move inward to the primary vortex ring. Then two large-scale loop-like vortices are formed to evolve in opposite directions. Thirdly, the two loop-like vortices collide with each other to form complicated small-scale vortical structures. Moreover, a series of hair-pin vortices are generated due to the stretching and deformation of the tertiary vortex. The trajectories of vortical structures and the relevant evolution speeds are analyzed. The total kinetic energy and enstrophy are investigated to reveal their properties relevant to the three evolution phases.
