This study explores the nonlinear resonance of a rotating solar sail membrane exposed to time-varying solar thermal and solar radiation pressure.The sail membrane is modeled using a cantilever membrane,applying the vo...This study explores the nonlinear resonance of a rotating solar sail membrane exposed to time-varying solar thermal and solar radiation pressure.The sail membrane is modeled using a cantilever membrane,applying the von Kármán theory for membrane large deflection.The membrane’s nonlinear equation is derived by employing the Lagrange equation while accounting for excitations from solar thermal and radiation pressure.The equation is solved via the Rayleigh-Ritz method.The bifurcation diagram of membrane motion is applied to reveal membrane resonance responses under different solar sail rotating frequencies.The displacement time history,phase portrait,Poincarémap,frequency spectrum,and the largest Lyapunov exponent are used to study nonlinear vibrations that occur near resonance regions.The results indicate that time-varying thermal loading excites membrane motions with multiple natural frequencies by the parametric resonance mechanics,leading to the onset of membrane chaotic motion.The membrane’s primary resonance is stimulated in harmonic oscillation by the time-varying radiation pressure.The divergence instability caused by thermal excitation is also illustrated by comparing the membrane’s vibration amplitude with and without thermal excitation.The membrane’s nonlinear vibration characteristics vary significantly with solar illumination angles,the membrane’s thermal expansion coefficients,and structural damping.展开更多
Unmanned aircraft are highly vulnerable to crosswind-induced turbulence during complex maneuvers such as turning,which can significantly compromise control and reduce autopilot effectiveness.This paper presents a nove...Unmanned aircraft are highly vulnerable to crosswind-induced turbulence during complex maneuvers such as turning,which can significantly compromise control and reduce autopilot effectiveness.This paper presents a novel control strategy to improve the controllability of unmanned aircraft in challenging wind conditions.First,the equations of motion for the aircraft are reformulated as a system of stochastic differential equations,which are subsequently transformed into a deterministic form.By modeling turbulence as a Gaussian random process and incorporating it directly into the control system,the proposed method proactively compensates for the adverse effects of turbulence.The transformation is achieved using semi-invariant techniques.Second,the control problem is formulated as an optimization task,aiming to minimize the deviation between the actual and desired turn characteristics,specifically the angular velocity.Finally,a new numerical method with proven global convergence is employed to compute the optimal autopilot parameters.Simulation results using a medium-range unmanned aircraft model under continuous turbulent gusts demonstrate that the proposed method significantly outperforms existing approaches,ensuring both stability and precision in turbulent wind conditions.展开更多
Automation and intelligence have become the primary trends in the design of investment casting processes.However,the design of gating and riser systems still lacks precise quantitative evaluation criteria.Numerical si...Automation and intelligence have become the primary trends in the design of investment casting processes.However,the design of gating and riser systems still lacks precise quantitative evaluation criteria.Numerical simulation plays a significant role in quantitatively evaluating current processes and making targeted improvements,but its limitations lie in the inability to dynamically reflect the formation outcomes of castings under varying process conditions,making real-time adjustments to gating and riser designs challenging.In this study,an automated design model for gating and riser systems based on integrated parametric 3D modeling-simulation framework is proposed,which enhances the flexibility and usability of evaluating the casting process by simulation.Firstly,geometric feature extraction technology is employed to obtain the geometric information of the target casting.Based on this information,an automated design framework for gating and riser systems is established,incorporating multiple structural parameters for real-time process control.Subsequently,the simulation results for various structural parameters are analyzed,and the influence of these parameters on casting formation is thoroughly investigated.Finally,the optimal design scheme is generated and validated through experimental verification.Simulation analysis and experimental results show that using a larger gate neck(24 mm in side length) and external risers promotes a more uniform temperature distribution and a more stable flow state,effectively eliminating shrinkage cavities and enhancing process yield by 15%.展开更多
Curtain wall systems have evolved from aesthetic facade elements into multifunctional building envelopes that actively contribute to energy efficiency and climate responsiveness.This reviewpresents a comprehensive exa...Curtain wall systems have evolved from aesthetic facade elements into multifunctional building envelopes that actively contribute to energy efficiency and climate responsiveness.This reviewpresents a comprehensive examination of curtain walls from an energy-engineering perspective,highlighting their structural typologies(Stick and Unitized),material configurations,and integration with smart technologies such as electrochromic glazing,parametric design algorithms,and Building Management Systems(BMS).Thestudy explores the thermal,acoustic,and solar performance of curtain walls across various climatic zones,supported by comparative analyses and iconic case studies including Apple Park,Burj Khalifa,and Milad Tower.Key challenges—including installation complexity,high maintenance costs,and climate sensitivity—are critically assessed alongside proposed solutions.A central innovation of this work lies in framing curtain walls not only as passive architectural elements but as dynamic interfaces that modulate energy flows,reduce HVAC loads,and enhance occupant comfort.The reviewed data indicate that optimized curtain wall configurations—especially those integrating electrochromic glazing and BIPV modules—can achieve annual energy consumption reductions ranging fromapproximately 5%to 27%,depending on climate,control strategy,and facade typology.The findings offer a valuable reference for architects,energy engineers,and decision-makers seeking to integrate high-performance facades into future-ready building designs.展开更多
This paper presents a novel artificial intelligence(AI)-assisted two-stage method for optimising rock slope stability by integrating advanced 3D modelling with rock support design,aiming at minimising risks,material u...This paper presents a novel artificial intelligence(AI)-assisted two-stage method for optimising rock slope stability by integrating advanced 3D modelling with rock support design,aiming at minimising risks,material usage,and costs.In the first stage,an extended key block analysis identifies key blocks and key block groups,accounting for progressive failure and force interactions.The second stage uses AI algorithms to optimise rockbolting design,balancing stability,cost,and material use.The most efficient algorithms include the multi-objective tree-structured Parzen estimator(MOTPE)and non-dominated sorting genetic algorithms(NSGA-II and NSGA-III).Applied to the Larvik rock slope,the optimised solution uses 18 pre-tensioned cablebolts,providing 13.2 MN of active force and achieving a factor of safety of 1.31 while reducing the average anchorage length by approximately 16%compared to traditional design.The AI-assisted approach also reduces computation time by over 90%compared to Quasi-Monte Carlo(QMC)methods,demonstrating its efficiency for small-scale civil engineering projects and large-scale mining operations.The developed tool is practical,compatible with Building Information Modelling(BIM),and ready for engineering implementation,supporting sustainable and cost-effective rock slope stabilisation.While the method is largely automated,professional judgement remains crucial for verifying ground conditions and selecting the final solution.Future work will focus on integrating data uncertainties,addressing complex block deformation mechanisms,refining optimisation objectives,and improving the performance of multi-objective optimisation for slope rockboling applications to further enhance the method's versatility.展开更多
Tunable mid-infrared and far-infrared laser output was demonstrated based on BaGa_(4)Se_(7)crystals and an optical parametric oscillator(OPO).With a 1.06μm Nd:YAG laser and a double-pass singly resonant OPO cavity,a ...Tunable mid-infrared and far-infrared laser output was demonstrated based on BaGa_(4)Se_(7)crystals and an optical parametric oscillator(OPO).With a 1.06μm Nd:YAG laser and a double-pass singly resonant OPO cavity,a laser energy output of 2.2 mJ at 10μm was obtained.By tuning the angle and temperature,a tunable laser output covering the wavelength range from 6μm to 17μm was obtained with a tuning precision better than 3 nm.The corresponding optical-to-optical conversion efficiency was 2.8%,and the slope efficiency was 4.4%.The damage effect of the output laser on detectors was also investigated,and point damage to the detector occurred at an output energy of 16.4μJ.The laser system has the advantages of miniaturization,a wide tuning range,high energy and high tuning resolution.Its broadband laser characteristics make it highly valuable for applications in atmospheric detection,infrared spectroscopy and electro-optical countermeasures.展开更多
A high-temperature and high-pressure valve is the key equipment of a wind tunnel system;it controls the generation of high-temperature and high-pressure gas.To reduce the adverse impact of high-temperature and high-pr...A high-temperature and high-pressure valve is the key equipment of a wind tunnel system;it controls the generation of high-temperature and high-pressure gas.To reduce the adverse impact of high-temperature and high-pressure gas on the strength of the valve body,a cooling structure is set on the valve seat.This can significantly reduce the temperature of the valve body and valve seat.The effects of its structure on the cooling characteristics and stress of the valve seat are studied,and six main parameters that can completely describe the geometry of the cooling structure are proposed.The central composite design method is used to select sample points,and the multi-objective genetic algorithm(MOGA)method is used for optimal structural design.A modification method according to the main parameters for the valve seat is proposed.The results show that the cooling structure weakens the pressure-bearing capability of the valve seat.Among the six main parameters of the valve seat,the distance from the end face of the lower hole to the Z-axis and the distance from the axis of the lower hole to the origin of the coordinates have the most obvious effects on the average stress of the valve seat.An optimum design value is proposed.This work can provide a reference for the design of high-temperature and high-pressure valves.展开更多
In recent years,the concept of digital human has attracted widespread attention from all walks of life,and the modelling of high-fidelity human bodies,heads,and hands has been intensively studied.This paper focuses on...In recent years,the concept of digital human has attracted widespread attention from all walks of life,and the modelling of high-fidelity human bodies,heads,and hands has been intensively studied.This paper focuses on head modelling and proposes a generic head parametric model based on neural radiance fields.Specifically,we first use face recognition networks and 3D facial expression database FaceWarehouse to parameterize identity and expression semantics,respectively,and use both as conditional inputs to build a neural radiance field for the human head,thereby improving the head model’s representation ability while ensuring editing capabilities for the identity and expression of the rendered results;then,through a combination of volume rendering and neural rendering,the 3D representation of the head is rapidly rendered into the 2D plane,producing a high-fidelity image of the human head.Thanks to the well-designed loss functions and good implicit representation of the neural radiance field,our model can not only edit the identity and expression independently,but also freely modify the virtual camera position of the rendering results.It has excellent multi-view consistency,and has many applications in novel view synthesis,pose driving and more.展开更多
An experimental investigation of the dynamics of the interface between two low-viscosity fluids with high density contrast oscillating in a fixed vertical slotted channel has been conducted.It has been found that as t...An experimental investigation of the dynamics of the interface between two low-viscosity fluids with high density contrast oscillating in a fixed vertical slotted channel has been conducted.It has been found that as the amplitude of the liquid column oscillations increases,parametric oscillations of the interface are excited in the form of a standing wave located in the channel plane.In particular,depending on the interfacial tension,the standing waves have a frequency equal to that of liquid piston oscillations(harmonic response),or half of the frequency of oscillations of the liquid column in the channel(subharmonic response).The detected type of instability has a gravitational-capillary nature and is analogous to Faraday waves.The analysis of the overcritical dynamics of wave oscillations indicates that interfacial tension plays a crucial role in determining the type of parametric instability.At high interfacial tension,only synchronous(harmonic)wave modes are observed,and the threshold of the wave excitation is determined by the amplitude of piston oscillations of the liquid column.In this case,the oscillation acceleration does not play a role and has a small value in the threshold of the synchronous mode response.In the case of weak surface tension,subharmonic oscillations are observed.The threshold for the development of these oscillations is determined by the dimensionless acceleration of the oscillating liquid column and remains almost constant with variations in the dimensionless frequency of oscillations.At moderate values of interfacial tension(in the region of moderate dimensionless frequencies),a synchronous wave mode emerges in the stability threshold of the oscillating interface.As the dimensionless acceleration is increased further,a subharmonic mode is excited.The growth of subharmonic oscillations occurs against the background of harmonic wave oscillations,with the oscillations of the interface representing a combination of two standing waves.展开更多
Multi-cell structures and corrugated tubes illustrate excellent energy absorption capacities.Besides,bamboo with continuously changing contours demonstrates superior impact-resisting capacities.As a result,a bionic mu...Multi-cell structures and corrugated tubes illustrate excellent energy absorption capacities.Besides,bamboo with continuously changing contours demonstrates superior impact-resisting capacities.As a result,a bionic multi-cell double corrugated(BMDC)tube,inspired by Buddha bamboo,is investigated to assess whether it is an ideal energy absorber candidate.Compared to a corrugated tube,a BMDC contains an outer structure,an inner structure,and diaphragms,which are like webs bridging the inner and outer structures.A basic numerical model is correlated using a physical experiment,followed by an investigation of BMDC tubes’energy absorption performance under axial loading,considering thickness and mass effects.Results indicate that the EA,MCF,and SEA of a BMDC containing 5 diaphragms(BMDC-5)with a 1.5 mm thickness can improve their respective responses by 112.89,112.89,and 83.32%higher compared to a BMDC with no diaphragm(BMDC-0).In addition,the BMDC-5 with 0.156 kg mass generates the highest EA,MCF,and SEA,which is 79.78%higher than a BMDC-0 with the same mass.The parametric analysis illustrates that diaphragms’amplitude and diameter have a decisive influence on energy absorption characteristics.This study emphasizes that BMDC tubes are innovative and practical,possessing excellent energy absorption performance.展开更多
Semi-submersible platforms operating in deep seas encounter complex environmental conditions,making experimental studies on their global performance essential for new platform designs.Model tests were conducted to exa...Semi-submersible platforms operating in deep seas encounter complex environmental conditions,making experimental studies on their global performance essential for new platform designs.Model tests were conducted to examine the 6-DOF motion characteristics of a conceptual semi-submersible platform equipped with a hollow moonpool(SPHM).The experimental results indicate that heave motions of the SPHM demonstrate suboptimal performance,potentially due to the natural heave period coinciding with the predominant wave energy range in the South China Sea.Furthermore,parametric rolling was observed during both regular and irregular wave tests and analyzed through Mathieu's equation.The analysis reveals that parametric rolling of the SPHM exhibits primarily low-frequency motion with substantial amplitudes,with its period matching the natural roll period.Notably,parametric rolling persists for only several natural roll periods of the platform,leading to considerable variance in roll motions.展开更多
Tensegrity structures,embodying the principles of continuous tensioning and discrete compression,have emerged as fundamental frameworks in locomotive soft robotics for navigating uneven and unpredictable environments,...Tensegrity structures,embodying the principles of continuous tensioning and discrete compression,have emerged as fundamental frameworks in locomotive soft robotics for navigating uneven and unpredictable environments,owing to their flexible and resilient traits.By means of a straightforward and cost-effective method to achieve structure-driven,vibration-driven tensegrity shows great potential,particularly in tasks demanding random exploration.However,the design guidance for vibration-driven tensegrity and their performance evaluation in unstructured terrain remain unrevealed due to the complex dynamics of the structure.This paper presents a small six-bar tensegrity robot,driven by wireless vibration motors,designed for deployment in disaster rescue and search scenarios.Finite element simulation is used to investigate how structural characteristics,excitation parameters,and the arrangement of motors affect the kinematic performance of this tensegrity system.A prototype of the six-bar tensegrity robot with three motors located on the lower ends of the three lower struts is designed and manufactured after the numerical simulations.A simple control policy which adjusts the motion of the tensegrity robot by turning on or off the motors on different locations is proposed.The prototype with and without the control policy is tested in man-made environments of various complexity.It shows that the ability and efficiency of the tensegrity robot in exploring unstructured environments is significantly enhanced by the proposed control policy.It is believed that the potential of the vibration-driven tensegrity robot could be further exploited by integrating multi-source sensors and more intelligent control policies.展开更多
Accurately modeling heavy-tailed data is critical across applied sciences,particularly in finance,medicine,and actuarial analysis.This work presents the heavy-tailed power XLindley distribution(HTPXLD),a unique heavy-...Accurately modeling heavy-tailed data is critical across applied sciences,particularly in finance,medicine,and actuarial analysis.This work presents the heavy-tailed power XLindley distribution(HTPXLD),a unique heavy-tailed distribution.Adding one more parameter to the power XLindley distribution improves this new distribution,especially when modeling leptokurtic lifetime data.The suggested density provides greater flexibility with asymmetric forms and different degrees of peakedness.Its statistical features,like the quantile function,moments,extropy measures,incomplete moments,stochastic ordering,and stress-strength parameters,are explored.We further investigate its use in actuarial science through the computation of pertinent metrics,such as value-at-risk,tail value-at-risk,tail variance,and tail variance premium.To obtain the point and interval parameter estimates,we use the maximum likelihood estimation approach.We do many simulation tests to evaluate the performance of our proposed estimator.Metrics like bias,relative bias,mean squared error,root mean squared error,average interval length,and coverage probability will be used in these tests to assess the estimator’s performance.To illustrate the practical value of our proposed model,we apply it to analyze three real-world datasets.We then compare its performance to established competing models,highlighting its advantages.展开更多
Inflatable deployable structures inspired by origami have significant applications in space missions such as solar arrays and antennas.In this paper,a generalized Miura-ori tubular cell(GMTC)is presented as the basic ...Inflatable deployable structures inspired by origami have significant applications in space missions such as solar arrays and antennas.In this paper,a generalized Miura-ori tubular cell(GMTC)is presented as the basic cell to design a family of inflatable origami tubular structures with the targeted configuration.First,the classification of rigid foldable degree-4 vertices is studied thoroughly.Since the proposed GMTC is comprised of forming units(FU)and linking units(LU),types of FUs and LUs are investigated based on the classification of degree-4 vertices,respectively.The rigid foldability of the GMTC is presented by studying the kinematics of the FUs and LUs.Volume of the GMTC is analyzed to investigate multistable configurations of the basic cell.The variations in volume of the GMTC offer great potential for developing the inflatable tubular structure.Design method and parametric optimization of the tubular structure with targeted configuration are proposed.The feasibility of the approach is validated by the approximation of four different cases,namely parabolic,semicircular,trapezoidal,and straight-arc hybrid tubular structures.展开更多
Purpose: The purpose of the current study is to investigate the within-pitcher differences in time series angular velocities of the pelvis, trunk, shoulder, and elbow for high and low velocity fastballs in college bas...Purpose: The purpose of the current study is to investigate the within-pitcher differences in time series angular velocities of the pelvis, trunk, shoulder, and elbow for high and low velocity fastballs in college baseball pitchers.Methods: In-game data were retrospectively analyzed from 82 NCAA Division 1 pitchers([1.89 ± 0.06] m, [92.8± 9.5] kg). Kinematic data were collected using an in-game markerless motion capture system. Time series data of pelvis, trunk, shoulder, and elbow angular velocities for each pitcher’s fastest and slowest fastball were extracted for the pitch cycle(foot contact to ball release) and used for analysis. Within-subject time series comparisons were conducted using statistical parametric mapping(SPM) paired samples t-tests(α = 0.012 5).Results: Each of the tested segments were significantly faster in the fastest fastball trial compared to the slowest fastball trial. The duration of significance in reference to the pitch cycle, test statistic, and p-value, for each segment are as follows: Pelvis: 0%–4%, t = 3.54, p = 0.012;Trunk: 30%–67%, t = 5.62, p < 0.001;Shoulder External Rotation: 3%–50%, t =-6.03, p < 0.001;Shoulder Internal Rotation: 96%–100%, t = 4.11, p = 0.008;Elbow: 75%–86%, t = 4.13, p < 0.001.Discussion: Within-subjects differences exist in time series angular velocities when comparing the fastest and slowest fastball. These time series differences provide additional information to distinguish fastball velocity beyond what discrete metrics can provide. Pitchers should look to rotate each segment faster, and optimize the sequencing of these movements, to increase pitch velocity.展开更多
We prove the boundedness of the parametric Lusin's S functionμ_(S)^(?)(f)and Littlewood-Paley's g_(λ)^(*)-funtionμ_(λ),^(*,?)(f)on grand Herz-Morrey spaces with variable exponents.Additionally,we establish...We prove the boundedness of the parametric Lusin's S functionμ_(S)^(?)(f)and Littlewood-Paley's g_(λ)^(*)-funtionμ_(λ),^(*,?)(f)on grand Herz-Morrey spaces with variable exponents.Additionally,we establish the boundedness of higher-order commutators ofμ_(S)^(?)andμ_(λ),^(*,?)with BMO functions applying some properties of variable exponents and generalized BMO norms.展开更多
We utilize conventional wave-vector-resolved Brillouin light scattering technology to investigate the spin wave response in YIG thin films under high-power microwave excitation. By varying the microwave frequency, ext...We utilize conventional wave-vector-resolved Brillouin light scattering technology to investigate the spin wave response in YIG thin films under high-power microwave excitation. By varying the microwave frequency, external bias magnetic field, and in-plane wave vector, in addition to observing the dipole-exchange spin waves excited by parallel parametric pumping, we further observe broadband spin wave excitation within the dipole-exchange spin wave spectrum. This broadband excitation results from the combined effects of parallel and perpendicular parametric pumping, induced by irregularities in the excitation geometry, as well as magnon–magnon scattering arising from the absence of certain spin wave modes. Our findings offer new insights into the mechanisms of energy dissipation and relaxation processes caused by spin wave excitation in magnetic devices operating at high power.展开更多
To further enhance the recovery rate of low-temperature waste heat,the low-temperature flue gas in the sinter annular cooler was chosen as the heat source of an organic Rankine cycle(ORC)system,and the comprehensive e...To further enhance the recovery rate of low-temperature waste heat,the low-temperature flue gas in the sinter annular cooler was chosen as the heat source of an organic Rankine cycle(ORC)system,and the comprehensive evaluation of energy,exergy and economic performance of the ORC system was conducted deeply.The energy,exergy and economic performance models of the ORC system were established,and proper candidate organic working fluids(OWFs)were selected based on the thermo-physical properties of OWF and operating characteristics of ORC system.Then,the effects of ORC crucial parameters on the system energy,exergy and economic performances were evaluated in detail.Finally,the bi-objective optimization based on the genetic algorithm was conducted to analyze the optimal performance of the ORC system under the designed ORC crucial parameters,and the exergy efficiency and electricity production cost were set as the evaluation indexes of parametric optimization.The results indicate that the ORC system with the higher evaporation temperature and lower condensation temperature can obtain the larger system exergy efficiency and smaller electricity production cost.The smaller the superheat degree of OWF and pinch-point temperature difference in the evaporator are,the better the energy and exergy performances of the ORC system are.Under the optimization results,R245fa has the best comprehensive performance with the exergy efficiency of 46.34%and electricity production cost of 0.12123$/kWh among the selected candidate OWFs,which should be preferentially chosen as the OWF of the ORC system.展开更多
To analyze the correlation between the input energy parameters(V_(E))and typical intensity measures(IMs)of offshore ground motions,based on 273 earthquake events recorded by the K-NET in Japan,892 offshore ground moti...To analyze the correlation between the input energy parameters(V_(E))and typical intensity measures(IMs)of offshore ground motions,based on 273 earthquake events recorded by the K-NET in Japan,892 offshore ground motion records with moment magnitudes from 4.0 to 7.0 were used in this study.Residuals obtained through a ground motion model were calculated and analyzed for the correlation between V_(E) and amplitude,duration,frequency content and cumulative IMs.The results indicate that PGV and PGD have strong correlation with the V_(E)(T>0.2 s and T>0.4 s),the duration IMs have weakly negative correlation with the V_(E),Sd_(1) has a strong correlation with the V_(E) in the periods of T>0.4 s,T_(g) has a weak correlation with V_(E) and the cumulative IMs have strong correlation with the V_(E).The parametric predictive equations between typical IMs and V_(E) was proposed,and the differences between the prediction equations from the onshore ground motion records were compared.The differences in parametric predicted equations between offshore and onshore ground motions were confirmed in this study.Proposed correlation equations can be applied to offshore probabilistic seismic hazard analysis and the selection of ground motion records by generalized conditional intensity measures.展开更多
The pulse duration is a critical parameter of picosecond-petawatt laser systems because it directly affects the results of high-energy-density physics experiments.This study systematically investigated the effects of ...The pulse duration is a critical parameter of picosecond-petawatt laser systems because it directly affects the results of high-energy-density physics experiments.This study systematically investigated the effects of the spectral width,central wavelength and beam-pointing deviations on pulse duration stability at the SG-Ⅱfacility.A theoretical analysis of the relationship between spectra and pulse duration is conducted to quantify the impact on pulse duration stability,and the results are further validated through experimental measurements.In addition,beam-pointing deviations at the stretcher significantly affect the pulse duration.For example,a 27μrad deviation can induce a 30%pulse duration variation.In contrast,the compressor exhibits greater robustness.Based on simulation and experimental results,we identify operational tolerance ranges for spectral width and beam-pointing deviation to maintain pulse duration stability within 5%at the SG-Ⅱfacility.These findings provide critical guidance for optimizing the performance and reliability of chirped-pulse amplification/optical parametric chirped-pulse amplification-based high-power laser systems.展开更多
基金supported by the Science Fund of NPU-Duke China Seeds Program(Grant No.119003067)the CAST-BISEE Fund(Grant No.MC010175)+1 种基金the Project of National Natural Science Foundation of China(Grant No.12372233)the“111”project of China(Grant No.B17037).
文摘This study explores the nonlinear resonance of a rotating solar sail membrane exposed to time-varying solar thermal and solar radiation pressure.The sail membrane is modeled using a cantilever membrane,applying the von Kármán theory for membrane large deflection.The membrane’s nonlinear equation is derived by employing the Lagrange equation while accounting for excitations from solar thermal and radiation pressure.The equation is solved via the Rayleigh-Ritz method.The bifurcation diagram of membrane motion is applied to reveal membrane resonance responses under different solar sail rotating frequencies.The displacement time history,phase portrait,Poincarémap,frequency spectrum,and the largest Lyapunov exponent are used to study nonlinear vibrations that occur near resonance regions.The results indicate that time-varying thermal loading excites membrane motions with multiple natural frequencies by the parametric resonance mechanics,leading to the onset of membrane chaotic motion.The membrane’s primary resonance is stimulated in harmonic oscillation by the time-varying radiation pressure.The divergence instability caused by thermal excitation is also illustrated by comparing the membrane’s vibration amplitude with and without thermal excitation.The membrane’s nonlinear vibration characteristics vary significantly with solar illumination angles,the membrane’s thermal expansion coefficients,and structural damping.
基金co-supported by the Fund of Robot Technology Used for Special Environment Key Laboratory of Sichuan Province(No.22kftk01)the Key Research and Development Program of Heilongjiang,China(No.2024ZXJ07B05)the National Natural Science Foundation of China(No.92471103)。
文摘Unmanned aircraft are highly vulnerable to crosswind-induced turbulence during complex maneuvers such as turning,which can significantly compromise control and reduce autopilot effectiveness.This paper presents a novel control strategy to improve the controllability of unmanned aircraft in challenging wind conditions.First,the equations of motion for the aircraft are reformulated as a system of stochastic differential equations,which are subsequently transformed into a deterministic form.By modeling turbulence as a Gaussian random process and incorporating it directly into the control system,the proposed method proactively compensates for the adverse effects of turbulence.The transformation is achieved using semi-invariant techniques.Second,the control problem is formulated as an optimization task,aiming to minimize the deviation between the actual and desired turn characteristics,specifically the angular velocity.Finally,a new numerical method with proven global convergence is employed to compute the optimal autopilot parameters.Simulation results using a medium-range unmanned aircraft model under continuous turbulent gusts demonstrate that the proposed method significantly outperforms existing approaches,ensuring both stability and precision in turbulent wind conditions.
基金financially supported by the National Key Research and Development Program of China (2022YFB3706802)。
文摘Automation and intelligence have become the primary trends in the design of investment casting processes.However,the design of gating and riser systems still lacks precise quantitative evaluation criteria.Numerical simulation plays a significant role in quantitatively evaluating current processes and making targeted improvements,but its limitations lie in the inability to dynamically reflect the formation outcomes of castings under varying process conditions,making real-time adjustments to gating and riser designs challenging.In this study,an automated design model for gating and riser systems based on integrated parametric 3D modeling-simulation framework is proposed,which enhances the flexibility and usability of evaluating the casting process by simulation.Firstly,geometric feature extraction technology is employed to obtain the geometric information of the target casting.Based on this information,an automated design framework for gating and riser systems is established,incorporating multiple structural parameters for real-time process control.Subsequently,the simulation results for various structural parameters are analyzed,and the influence of these parameters on casting formation is thoroughly investigated.Finally,the optimal design scheme is generated and validated through experimental verification.Simulation analysis and experimental results show that using a larger gate neck(24 mm in side length) and external risers promotes a more uniform temperature distribution and a more stable flow state,effectively eliminating shrinkage cavities and enhancing process yield by 15%.
文摘Curtain wall systems have evolved from aesthetic facade elements into multifunctional building envelopes that actively contribute to energy efficiency and climate responsiveness.This reviewpresents a comprehensive examination of curtain walls from an energy-engineering perspective,highlighting their structural typologies(Stick and Unitized),material configurations,and integration with smart technologies such as electrochromic glazing,parametric design algorithms,and Building Management Systems(BMS).Thestudy explores the thermal,acoustic,and solar performance of curtain walls across various climatic zones,supported by comparative analyses and iconic case studies including Apple Park,Burj Khalifa,and Milad Tower.Key challenges—including installation complexity,high maintenance costs,and climate sensitivity—are critically assessed alongside proposed solutions.A central innovation of this work lies in framing curtain walls not only as passive architectural elements but as dynamic interfaces that modulate energy flows,reduce HVAC loads,and enhance occupant comfort.The reviewed data indicate that optimized curtain wall configurations—especially those integrating electrochromic glazing and BIPV modules—can achieve annual energy consumption reductions ranging fromapproximately 5%to 27%,depending on climate,control strategy,and facade typology.The findings offer a valuable reference for architects,energy engineers,and decision-makers seeking to integrate high-performance facades into future-ready building designs.
基金support from Research Council of Norway via STIPINST PhD grant(Grant No.323307),Bever Control AS,and Bane NOR.
文摘This paper presents a novel artificial intelligence(AI)-assisted two-stage method for optimising rock slope stability by integrating advanced 3D modelling with rock support design,aiming at minimising risks,material usage,and costs.In the first stage,an extended key block analysis identifies key blocks and key block groups,accounting for progressive failure and force interactions.The second stage uses AI algorithms to optimise rockbolting design,balancing stability,cost,and material use.The most efficient algorithms include the multi-objective tree-structured Parzen estimator(MOTPE)and non-dominated sorting genetic algorithms(NSGA-II and NSGA-III).Applied to the Larvik rock slope,the optimised solution uses 18 pre-tensioned cablebolts,providing 13.2 MN of active force and achieving a factor of safety of 1.31 while reducing the average anchorage length by approximately 16%compared to traditional design.The AI-assisted approach also reduces computation time by over 90%compared to Quasi-Monte Carlo(QMC)methods,demonstrating its efficiency for small-scale civil engineering projects and large-scale mining operations.The developed tool is practical,compatible with Building Information Modelling(BIM),and ready for engineering implementation,supporting sustainable and cost-effective rock slope stabilisation.While the method is largely automated,professional judgement remains crucial for verifying ground conditions and selecting the final solution.Future work will focus on integrating data uncertainties,addressing complex block deformation mechanisms,refining optimisation objectives,and improving the performance of multi-objective optimisation for slope rockboling applications to further enhance the method's versatility.
基金supported by Independent Innovation Science Foundation of National University of Defense Technology(Grant No.23-ZZCX-JDZ-44)。
文摘Tunable mid-infrared and far-infrared laser output was demonstrated based on BaGa_(4)Se_(7)crystals and an optical parametric oscillator(OPO).With a 1.06μm Nd:YAG laser and a double-pass singly resonant OPO cavity,a laser energy output of 2.2 mJ at 10μm was obtained.By tuning the angle and temperature,a tunable laser output covering the wavelength range from 6μm to 17μm was obtained with a tuning precision better than 3 nm.The corresponding optical-to-optical conversion efficiency was 2.8%,and the slope efficiency was 4.4%.The damage effect of the output laser on detectors was also investigated,and point damage to the detector occurred at an output energy of 16.4μJ.The laser system has the advantages of miniaturization,a wide tuning range,high energy and high tuning resolution.Its broadband laser characteristics make it highly valuable for applications in atmospheric detection,infrared spectroscopy and electro-optical countermeasures.
基金supported by the National Natural Science Foundation of China(No.52175067)the Zhejiang Key Research&Development Project(No.2021C01021)+1 种基金the Natural Science Foundation of Zhejiang Province(No.LY20E050016)the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(CPSF)(No.GZC20241478)。
文摘A high-temperature and high-pressure valve is the key equipment of a wind tunnel system;it controls the generation of high-temperature and high-pressure gas.To reduce the adverse impact of high-temperature and high-pressure gas on the strength of the valve body,a cooling structure is set on the valve seat.This can significantly reduce the temperature of the valve body and valve seat.The effects of its structure on the cooling characteristics and stress of the valve seat are studied,and six main parameters that can completely describe the geometry of the cooling structure are proposed.The central composite design method is used to select sample points,and the multi-objective genetic algorithm(MOGA)method is used for optimal structural design.A modification method according to the main parameters for the valve seat is proposed.The results show that the cooling structure weakens the pressure-bearing capability of the valve seat.Among the six main parameters of the valve seat,the distance from the end face of the lower hole to the Z-axis and the distance from the axis of the lower hole to the origin of the coordinates have the most obvious effects on the average stress of the valve seat.An optimum design value is proposed.This work can provide a reference for the design of high-temperature and high-pressure valves.
文摘In recent years,the concept of digital human has attracted widespread attention from all walks of life,and the modelling of high-fidelity human bodies,heads,and hands has been intensively studied.This paper focuses on head modelling and proposes a generic head parametric model based on neural radiance fields.Specifically,we first use face recognition networks and 3D facial expression database FaceWarehouse to parameterize identity and expression semantics,respectively,and use both as conditional inputs to build a neural radiance field for the human head,thereby improving the head model’s representation ability while ensuring editing capabilities for the identity and expression of the rendered results;then,through a combination of volume rendering and neural rendering,the 3D representation of the head is rapidly rendered into the 2D plane,producing a high-fidelity image of the human head.Thanks to the well-designed loss functions and good implicit representation of the neural radiance field,our model can not only edit the identity and expression independently,but also freely modify the virtual camera position of the rendering results.It has excellent multi-view consistency,and has many applications in novel view synthesis,pose driving and more.
基金supported by the Ministry of Education of the Russian Federation(Project No.1023032300071-6-2.3.1).
文摘An experimental investigation of the dynamics of the interface between two low-viscosity fluids with high density contrast oscillating in a fixed vertical slotted channel has been conducted.It has been found that as the amplitude of the liquid column oscillations increases,parametric oscillations of the interface are excited in the form of a standing wave located in the channel plane.In particular,depending on the interfacial tension,the standing waves have a frequency equal to that of liquid piston oscillations(harmonic response),or half of the frequency of oscillations of the liquid column in the channel(subharmonic response).The detected type of instability has a gravitational-capillary nature and is analogous to Faraday waves.The analysis of the overcritical dynamics of wave oscillations indicates that interfacial tension plays a crucial role in determining the type of parametric instability.At high interfacial tension,only synchronous(harmonic)wave modes are observed,and the threshold of the wave excitation is determined by the amplitude of piston oscillations of the liquid column.In this case,the oscillation acceleration does not play a role and has a small value in the threshold of the synchronous mode response.In the case of weak surface tension,subharmonic oscillations are observed.The threshold for the development of these oscillations is determined by the dimensionless acceleration of the oscillating liquid column and remains almost constant with variations in the dimensionless frequency of oscillations.At moderate values of interfacial tension(in the region of moderate dimensionless frequencies),a synchronous wave mode emerges in the stability threshold of the oscillating interface.As the dimensionless acceleration is increased further,a subharmonic mode is excited.The growth of subharmonic oscillations occurs against the background of harmonic wave oscillations,with the oscillations of the interface representing a combination of two standing waves.
基金2022 Guangxi University Young and Middle-aged Teachers’Basic Research Ability Improvement Project,2022KY0781,Rui Liang。
文摘Multi-cell structures and corrugated tubes illustrate excellent energy absorption capacities.Besides,bamboo with continuously changing contours demonstrates superior impact-resisting capacities.As a result,a bionic multi-cell double corrugated(BMDC)tube,inspired by Buddha bamboo,is investigated to assess whether it is an ideal energy absorber candidate.Compared to a corrugated tube,a BMDC contains an outer structure,an inner structure,and diaphragms,which are like webs bridging the inner and outer structures.A basic numerical model is correlated using a physical experiment,followed by an investigation of BMDC tubes’energy absorption performance under axial loading,considering thickness and mass effects.Results indicate that the EA,MCF,and SEA of a BMDC containing 5 diaphragms(BMDC-5)with a 1.5 mm thickness can improve their respective responses by 112.89,112.89,and 83.32%higher compared to a BMDC with no diaphragm(BMDC-0).In addition,the BMDC-5 with 0.156 kg mass generates the highest EA,MCF,and SEA,which is 79.78%higher than a BMDC-0 with the same mass.The parametric analysis illustrates that diaphragms’amplitude and diameter have a decisive influence on energy absorption characteristics.This study emphasizes that BMDC tubes are innovative and practical,possessing excellent energy absorption performance.
基金financially supported by the National Key Research and Development Program of China(Grant No.2022YFC2806300)。
文摘Semi-submersible platforms operating in deep seas encounter complex environmental conditions,making experimental studies on their global performance essential for new platform designs.Model tests were conducted to examine the 6-DOF motion characteristics of a conceptual semi-submersible platform equipped with a hollow moonpool(SPHM).The experimental results indicate that heave motions of the SPHM demonstrate suboptimal performance,potentially due to the natural heave period coinciding with the predominant wave energy range in the South China Sea.Furthermore,parametric rolling was observed during both regular and irregular wave tests and analyzed through Mathieu's equation.The analysis reveals that parametric rolling of the SPHM exhibits primarily low-frequency motion with substantial amplitudes,with its period matching the natural roll period.Notably,parametric rolling persists for only several natural roll periods of the platform,leading to considerable variance in roll motions.
基金supported by the National Natural Science Foundation of China(Grant Nos.52178175 and 52108182)the National Natural Science Foundation of Zhejiang Province(Grant No.LZ23E080003).
文摘Tensegrity structures,embodying the principles of continuous tensioning and discrete compression,have emerged as fundamental frameworks in locomotive soft robotics for navigating uneven and unpredictable environments,owing to their flexible and resilient traits.By means of a straightforward and cost-effective method to achieve structure-driven,vibration-driven tensegrity shows great potential,particularly in tasks demanding random exploration.However,the design guidance for vibration-driven tensegrity and their performance evaluation in unstructured terrain remain unrevealed due to the complex dynamics of the structure.This paper presents a small six-bar tensegrity robot,driven by wireless vibration motors,designed for deployment in disaster rescue and search scenarios.Finite element simulation is used to investigate how structural characteristics,excitation parameters,and the arrangement of motors affect the kinematic performance of this tensegrity system.A prototype of the six-bar tensegrity robot with three motors located on the lower ends of the three lower struts is designed and manufactured after the numerical simulations.A simple control policy which adjusts the motion of the tensegrity robot by turning on or off the motors on different locations is proposed.The prototype with and without the control policy is tested in man-made environments of various complexity.It shows that the ability and efficiency of the tensegrity robot in exploring unstructured environments is significantly enhanced by the proposed control policy.It is believed that the potential of the vibration-driven tensegrity robot could be further exploited by integrating multi-source sensors and more intelligent control policies.
基金supported by researchers Supporting Project Number(RSPD2025R548)King Saud University,Riyadh,Saudi Arabia.
文摘Accurately modeling heavy-tailed data is critical across applied sciences,particularly in finance,medicine,and actuarial analysis.This work presents the heavy-tailed power XLindley distribution(HTPXLD),a unique heavy-tailed distribution.Adding one more parameter to the power XLindley distribution improves this new distribution,especially when modeling leptokurtic lifetime data.The suggested density provides greater flexibility with asymmetric forms and different degrees of peakedness.Its statistical features,like the quantile function,moments,extropy measures,incomplete moments,stochastic ordering,and stress-strength parameters,are explored.We further investigate its use in actuarial science through the computation of pertinent metrics,such as value-at-risk,tail value-at-risk,tail variance,and tail variance premium.To obtain the point and interval parameter estimates,we use the maximum likelihood estimation approach.We do many simulation tests to evaluate the performance of our proposed estimator.Metrics like bias,relative bias,mean squared error,root mean squared error,average interval length,and coverage probability will be used in these tests to assess the estimator’s performance.To illustrate the practical value of our proposed model,we apply it to analyze three real-world datasets.We then compare its performance to established competing models,highlighting its advantages.
基金supported by the National Natural Science Foundation of China(No.52222501,52075016,52192632)the Fundamental Research Funds for the Central Universities(Grant No.YWF-23-L-904).
文摘Inflatable deployable structures inspired by origami have significant applications in space missions such as solar arrays and antennas.In this paper,a generalized Miura-ori tubular cell(GMTC)is presented as the basic cell to design a family of inflatable origami tubular structures with the targeted configuration.First,the classification of rigid foldable degree-4 vertices is studied thoroughly.Since the proposed GMTC is comprised of forming units(FU)and linking units(LU),types of FUs and LUs are investigated based on the classification of degree-4 vertices,respectively.The rigid foldability of the GMTC is presented by studying the kinematics of the FUs and LUs.Volume of the GMTC is analyzed to investigate multistable configurations of the basic cell.The variations in volume of the GMTC offer great potential for developing the inflatable tubular structure.Design method and parametric optimization of the tubular structure with targeted configuration are proposed.The feasibility of the approach is validated by the approximation of four different cases,namely parabolic,semicircular,trapezoidal,and straight-arc hybrid tubular structures.
文摘Purpose: The purpose of the current study is to investigate the within-pitcher differences in time series angular velocities of the pelvis, trunk, shoulder, and elbow for high and low velocity fastballs in college baseball pitchers.Methods: In-game data were retrospectively analyzed from 82 NCAA Division 1 pitchers([1.89 ± 0.06] m, [92.8± 9.5] kg). Kinematic data were collected using an in-game markerless motion capture system. Time series data of pelvis, trunk, shoulder, and elbow angular velocities for each pitcher’s fastest and slowest fastball were extracted for the pitch cycle(foot contact to ball release) and used for analysis. Within-subject time series comparisons were conducted using statistical parametric mapping(SPM) paired samples t-tests(α = 0.012 5).Results: Each of the tested segments were significantly faster in the fastest fastball trial compared to the slowest fastball trial. The duration of significance in reference to the pitch cycle, test statistic, and p-value, for each segment are as follows: Pelvis: 0%–4%, t = 3.54, p = 0.012;Trunk: 30%–67%, t = 5.62, p < 0.001;Shoulder External Rotation: 3%–50%, t =-6.03, p < 0.001;Shoulder Internal Rotation: 96%–100%, t = 4.11, p = 0.008;Elbow: 75%–86%, t = 4.13, p < 0.001.Discussion: Within-subjects differences exist in time series angular velocities when comparing the fastest and slowest fastball. These time series differences provide additional information to distinguish fastball velocity beyond what discrete metrics can provide. Pitchers should look to rotate each segment faster, and optimize the sequencing of these movements, to increase pitch velocity.
基金Supported by the Natural Science Research Project of Anhui Educational Committee(Grant No.2024AH050129)。
文摘We prove the boundedness of the parametric Lusin's S functionμ_(S)^(?)(f)and Littlewood-Paley's g_(λ)^(*)-funtionμ_(λ),^(*,?)(f)on grand Herz-Morrey spaces with variable exponents.Additionally,we establish the boundedness of higher-order commutators ofμ_(S)^(?)andμ_(λ),^(*,?)with BMO functions applying some properties of variable exponents and generalized BMO norms.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 52471200, 12174165, and 52201219)。
文摘We utilize conventional wave-vector-resolved Brillouin light scattering technology to investigate the spin wave response in YIG thin films under high-power microwave excitation. By varying the microwave frequency, external bias magnetic field, and in-plane wave vector, in addition to observing the dipole-exchange spin waves excited by parallel parametric pumping, we further observe broadband spin wave excitation within the dipole-exchange spin wave spectrum. This broadband excitation results from the combined effects of parallel and perpendicular parametric pumping, induced by irregularities in the excitation geometry, as well as magnon–magnon scattering arising from the absence of certain spin wave modes. Our findings offer new insights into the mechanisms of energy dissipation and relaxation processes caused by spin wave excitation in magnetic devices operating at high power.
基金the financial support for this work provided by the National Natural Science Foundation of China(51974087)Anhui Provincial Natural Science Foundation(1908085QE203)+1 种基金University Natural Science Research Foundation of Anhui Province(2022AH050262)Science Research Foundation of Anhui Jianzhu University(2020QDZ02).
文摘To further enhance the recovery rate of low-temperature waste heat,the low-temperature flue gas in the sinter annular cooler was chosen as the heat source of an organic Rankine cycle(ORC)system,and the comprehensive evaluation of energy,exergy and economic performance of the ORC system was conducted deeply.The energy,exergy and economic performance models of the ORC system were established,and proper candidate organic working fluids(OWFs)were selected based on the thermo-physical properties of OWF and operating characteristics of ORC system.Then,the effects of ORC crucial parameters on the system energy,exergy and economic performances were evaluated in detail.Finally,the bi-objective optimization based on the genetic algorithm was conducted to analyze the optimal performance of the ORC system under the designed ORC crucial parameters,and the exergy efficiency and electricity production cost were set as the evaluation indexes of parametric optimization.The results indicate that the ORC system with the higher evaporation temperature and lower condensation temperature can obtain the larger system exergy efficiency and smaller electricity production cost.The smaller the superheat degree of OWF and pinch-point temperature difference in the evaporator are,the better the energy and exergy performances of the ORC system are.Under the optimization results,R245fa has the best comprehensive performance with the exergy efficiency of 46.34%and electricity production cost of 0.12123$/kWh among the selected candidate OWFs,which should be preferentially chosen as the OWF of the ORC system.
基金National Natural Science Foundation of China under Grant No.52478568National Key R&D Program of China under Grant Nos.2021YFC3100701 and 2022YFC3003503the Nature Science Foundation of Hubei Province under Grant No.2023AFA030。
文摘To analyze the correlation between the input energy parameters(V_(E))and typical intensity measures(IMs)of offshore ground motions,based on 273 earthquake events recorded by the K-NET in Japan,892 offshore ground motion records with moment magnitudes from 4.0 to 7.0 were used in this study.Residuals obtained through a ground motion model were calculated and analyzed for the correlation between V_(E) and amplitude,duration,frequency content and cumulative IMs.The results indicate that PGV and PGD have strong correlation with the V_(E)(T>0.2 s and T>0.4 s),the duration IMs have weakly negative correlation with the V_(E),Sd_(1) has a strong correlation with the V_(E) in the periods of T>0.4 s,T_(g) has a weak correlation with V_(E) and the cumulative IMs have strong correlation with the V_(E).The parametric predictive equations between typical IMs and V_(E) was proposed,and the differences between the prediction equations from the onshore ground motion records were compared.The differences in parametric predicted equations between offshore and onshore ground motions were confirmed in this study.Proposed correlation equations can be applied to offshore probabilistic seismic hazard analysis and the selection of ground motion records by generalized conditional intensity measures.
基金partially supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA25020306)the National Natural Science Foundation of China(NSFC)(Grant No.62175247)。
文摘The pulse duration is a critical parameter of picosecond-petawatt laser systems because it directly affects the results of high-energy-density physics experiments.This study systematically investigated the effects of the spectral width,central wavelength and beam-pointing deviations on pulse duration stability at the SG-Ⅱfacility.A theoretical analysis of the relationship between spectra and pulse duration is conducted to quantify the impact on pulse duration stability,and the results are further validated through experimental measurements.In addition,beam-pointing deviations at the stretcher significantly affect the pulse duration.For example,a 27μrad deviation can induce a 30%pulse duration variation.In contrast,the compressor exhibits greater robustness.Based on simulation and experimental results,we identify operational tolerance ranges for spectral width and beam-pointing deviation to maintain pulse duration stability within 5%at the SG-Ⅱfacility.These findings provide critical guidance for optimizing the performance and reliability of chirped-pulse amplification/optical parametric chirped-pulse amplification-based high-power laser systems.
