This paper investigates global solutions and long-time dynamics for the stochastic reaction-diffusion equation du=(Δu+f(u)+g(x,t))dt+σ(u)dW on a bounded domain,where the drift term f(u),with polynomial growth rate ...This paper investigates global solutions and long-time dynamics for the stochastic reaction-diffusion equation du=(Δu+f(u)+g(x,t))dt+σ(u)dW on a bounded domain,where the drift term f(u),with polynomial growth rate β,is strongly dissipative and the diffusion term σ(u)has growth rate γ,satisfying β+1>2γ.Under this condition,we establish the existence,uniqueness,and regularity of solutions in Bochner spaces.Our analysis relies only on weak monotonicity conditions and requires no further growth restrictions on f andσ.Moreover,we prove the existence of a weak mean random attractor for the system.These results offer new insights into the balance mechanism between stochastic perturbations and dissipative effects in superlinear regimes.展开更多
A new definition of dissipativity for neural networks is presented in this paper. By constructing proper Lyapunov functionals and using some analytic techniques, sufficient conditions are given to ensure the dissipati...A new definition of dissipativity for neural networks is presented in this paper. By constructing proper Lyapunov functionals and using some analytic techniques, sufficient conditions are given to ensure the dissipativity of neural networks with or without time-varying parametric uncertainties and the integro-differential neural networks in terms of linear matrix inequalities. Numerical examples are given to illustrate the effectiveness of the obtained results.展开更多
This paper is concerned with the numerical dissipativity of multistep Runge-Kutta methods for nonlinear neutral delay-integro-differential equations.We investigate the dissipativity properties of-algebraically stable ...This paper is concerned with the numerical dissipativity of multistep Runge-Kutta methods for nonlinear neutral delay-integro-differential equations.We investigate the dissipativity properties of-algebraically stable multistep Runge-Kutta methods with constrained grid.The finite-dimensional and infinite-dimensional dissipativity results of-algebraically stable multistep Runge-Kutta methods are obtained.展开更多
The analytic and discretized dissipativity of nonlinear infinite-delay systems of the form x＇（t） = g（x（t）,x（qt））（q∈ （0, 1）, t 〉 0） is investigated. A sufficient condition is presented to ensure that the...The analytic and discretized dissipativity of nonlinear infinite-delay systems of the form x＇（t） = g（x（t）,x（qt））（q∈ （0, 1）, t 〉 0） is investigated. A sufficient condition is presented to ensure that the above nonlinear system is dissipative. It is proved the backward Euler method inherits the dissipativity of the underlying system. Numerical examples are given to confirm the theoretical results.展开更多
This paper is concerned with the numerical dissipativity of multistep Runge-Kutta methods for nonlinear Volterra delay-integro-differential equations. We investigate the dissipativity properties of （k, l）- algebraic...This paper is concerned with the numerical dissipativity of multistep Runge-Kutta methods for nonlinear Volterra delay-integro-differential equations. We investigate the dissipativity properties of （k, l）- algebraically stable multistep Runge-Kutta methods with constrained grid and an uniform grid. The finite- dimensional and infinite-dimensional dissipativity results of （k, /）-algebraically stable Runge-Kutta methods are obtained.展开更多
This paper deals with analytic and numerical dissipativity and exponential stability of singularly perturbed delay differential equations with any bounded state-independent lag. Sufficient conditions will be presented...This paper deals with analytic and numerical dissipativity and exponential stability of singularly perturbed delay differential equations with any bounded state-independent lag. Sufficient conditions will be presented to ensure that any solution of the singularly perturbed delay differential equations (DDEs) with a bounded lag is dissipative and exponentially stable uniformly for sufficiently small ε > 0. We will study the numerical solution defined by the linear θ-method and one-leg method and show that they are dissipative and exponentially stable uniformly for sufficiently small ε > 0 if and only if θ = 1.展开更多
In this paper, a class of stochastic Lotka Volterra system with feedback controls is considered. The purpose is to establish some criteria to ensure the system is globally dissipative in the mean square. By constructi...In this paper, a class of stochastic Lotka Volterra system with feedback controls is considered. The purpose is to establish some criteria to ensure the system is globally dissipative in the mean square. By constructing suitable Lyapunov functions as well as combining with Jensen inequality and Ito formula, the sufficient conditions are established and they are expressed in terms of the feasibility to a couple linear matrix inequalities （LMIs）. Finally, the main results are illustrated by examples.展开更多
A multi-physics approach was used to quantify the effect of process parameters (laser power, scanning speed, hatch spacing, and scanning strategy) on the thermal history and corresponding microstructure evolution of T...A multi-physics approach was used to quantify the effect of process parameters (laser power, scanning speed, hatch spacing, and scanning strategy) on the thermal history and corresponding microstructure evolution of Ti-25Nb (at%) alloy during the dual-track selective laser melting (SLM) process. Simulation results reveal that during the dual-track SLM process, increasing laser power results in greater thermal accumulation, leading to a molten pool of larger volume and coarser grains. Reducing scanning speed enhances remelting and promotes cellular growth at the top of molten pool, whereas faster scanning speed leads to rougher melt tracks and finer grains. Notably, hatch spacing significantly influences the molten pool dimensions and microstructures, and smaller hatch spacing promotes remelting. Furthermore, the orientations of grains in the second track during zigzag scanning differ markedly from those in the first track. More importantly, compared with those after the first track, both the temperature gradient and cooling rate at the boundaries of remelting molten pool are reduced after the second track scanning, resulting in slower interface velocity and significant change in solidification microstructure. This research provides a theoretical foundation for controlling non-equilibrium microstructure and offering novel insights into the optimization of SLM process parameters of titanium alloys.展开更多
This paper pays close attention to the global polynomial dissipativity(GPD)for proportional delayed BAM neural networks(PDBAMNNs).The global exponential dissipativity(GED)and the global dissipativity(GD)are also talke...This paper pays close attention to the global polynomial dissipativity(GPD)for proportional delayed BAM neural networks(PDBAMNNs).The global exponential dissipativity(GED)and the global dissipativity(GD)are also talked about.Under the help of novel Lyapunov functionals and a generalized Halanay inequality,a set of dissipative criteria for such systems are led out,together with the global polynomial attracting set(GPAS)and the global attracting set(GAS).Further,the relationship among GPD,GED and GD is unveiled.Finally,a proposed theoretical condition is validated through a simulation experiment.展开更多
Optimization of heat and mass transfer between humid air and water can signicantly enhance the performance of HVAC sys-tems and equipment.Based on entransy theory,this study examines how entransy dissipation varies in...Optimization of heat and mass transfer between humid air and water can signicantly enhance the performance of HVAC sys-tems and equipment.Based on entransy theory,this study examines how entransy dissipation varies in moist air and water un-der isothermal and isenthalpic conditions within a vertical spray chamber.An entransy dissipation coefcient,X,is dened to quantify the irreversibility of the heat and mass transfer process.The results reveal that for a given heat exchange between moist air and water,when the inlet moist air is near saturation the system achieves minimal entransy dissipation,reduced mois-ture-based thermal resistance(TRMED),and a lower X value,indicating that the overall heat and mass transfer losses are nearly minimized.展开更多
To explore the distribution law of the temperature field in the motor pump and the influence of the fanshaped DC channel with spoiler in the pump housing on its heat dissipation performance.This study takes the arc-ge...To explore the distribution law of the temperature field in the motor pump and the influence of the fanshaped DC channel with spoiler in the pump housing on its heat dissipation performance.This study takes the arc-gear type hydraulicmotor pump as the research object.In COMSOL,a coupled heat transfer simulationmodel of themotor pump’s fluid-solid coupling is established,and the internal temperature field characteristics are analyzed.To improve the heat dissipation effect of the motor pump,it is proposed to arrange spoiler in the fan-shaped DC channel of the pump housing to enhance heat dissipation.Three types of spoilers,namely,wing-shaped,inclined rectangle-shaped,and wave-shaped,are designed.The simulation results show that when the motor pump operates under rated conditions,due to the poor heat dissipation environment inside the motor pump,the high-temperature areas of the motor pump are concentrated in the rotor and permanent magnet parts.After arranging the spoiler,the turbulent kinetic energy and vorticity in the fan-shaped DC channel of the pump housing are significantly enhanced.All three spoiler structures can reduce the maximum temperature of each component of the motor.According to the comprehensive performance evaluation criterion(PEC),the inclined rectangle-shaped structure has the best comprehensive heat transfer performance(PEC=1.114),while the wave-shaped structure has higher heat transfer efficiency but greater pressure loss.The wing-shaped structure has relatively limited enhancement effect on heat dissipation.This study systematically quantifies the influence of different spoiler structures on heat dissipation performance and flowresistance characteristics,providing a solution for enhancing the heat dissipation of the motor pump.展开更多
China has limited acaricide options for tea plantations.Cyetpyrafen,a novel domestic acaricide with high efficacy,low toxicity and a negative temperature coefficient,offers an alternative for tea pest control;however,...China has limited acaricide options for tea plantations.Cyetpyrafen,a novel domestic acaricide with high efficacy,low toxicity and a negative temperature coefficient,offers an alternative for tea pest control;however,its residue fate in tea remains unclear.This study developed a method to simultaneously detect cyetpyrafen and its metabolites(M-309,M-325-1,and M-409-3)in different tea matrices to investigate their fate.Recoveries of compounds ranged from 73.4 to 106.2%with the relative standard deviations(RSDs)below 12.0%.During tea cultivation,the dissipation half-life of cyetpyrafen was 0.59 d,with M-309 as a major metabolite.The residues of cyetpyrafen and M-309 were affected by different processing stages,especially water loss and high temperatures during fixing,drying and withering.The total processing factors ranged from 1.39 to 1.71 for green tea and 1.48 to 2.28 for black tea(processed from fresh tea leaves sampled at 1,5,and 7 d),respectively.The leaching rates of cyetpyrafen from green tea and black tea into tea infusions were 7.4 and 6%,respectively.The risk associated with cyetpyrafen intake from tea consumption was low,with risk quotient values below 100%.However,theoretical calculation indicated potential harm to non-target organisms from its metabolites.This research provides a reference for the safe and efficient use of cyetpyrafen in tea gardens.展开更多
A critical scientific gap exists in quantifying the intrinsic mechanisms of shale mechanical property degradation induced by the combined effects of perforation(impact)and acidization—two core techniques for shale re...A critical scientific gap exists in quantifying the intrinsic mechanisms of shale mechanical property degradation induced by the combined effects of perforation(impact)and acidization—two core techniques for shale reservoir permeability enhancement.To address this gap,this study proposed an innovative coupled experimental framework integrating dynamic-static cyclic loading(to simulate perforation impact)and acid erosion.Static uniaxial compression tests were performed on treated damaged shale samples,with microstructural characterization via X-ray diffraction(XRD)and scanning electron microscopy(SEM).Key findings include:(1)The damage factor(characterized by longitudinal wave velocity)showed a significant positive correlation with acid concentration;(2)Combined damage(impact+acidization)caused far more severe mechanical deterioration than single damage modes—for instance,samples under combined damage with 20%hydrochloric acid exhibited a strength reduction to 158.97 MPa,with sharp decreases in peak strength and elastic modulus;(3)Damage reduced total energy and elastic strain energy of samples while increasing dissipated energy proportion,leading to more developed internal fractures and severe failure in combined damage samples;(4)Acidization promoted sample fragmentation into smaller debris,resulting in significantly higher fractal dimensions of acidized shale than other damage types under the same acid concentration;(5)XRD and SEM analyses confirmed that high-concentration acid erosion reduced shale carbonate content,and the synergy of mechanical pre-damage and chemical dissolution in combined damage accelerated acid-rock reactions,significantly increasing micro-interfacial pores and degrading shale structural integrity.This study’s innovation lies in establishing a coupled experimental framework that reproduces the actual“perforation-acidization”sequence,quantitatively revealing the synergistic degradation mechanism of shale mechanical properties under combined damage—providing a novel theoretical basis for optimizing shale reservoir stimulation parameters.展开更多
By combining the merits of radiative cooling(RC)and evaporation cooling(EC),radiative coupled evaporative cooling(REC)has attracted considerable attention for sub-ambient cooling purposes.However,for outdoor devices,t...By combining the merits of radiative cooling(RC)and evaporation cooling(EC),radiative coupled evaporative cooling(REC)has attracted considerable attention for sub-ambient cooling purposes.However,for outdoor devices,the interior heating power would increase the working temperature and fire risk,which would suppress their above-ambient heat dissipation capabilities and passive water cycle properties.In this work,we introduced a REC design based on an all-in-one photonic hydrogel for above-ambient heat dissipation and flame retardancy.Unlike conventional design RC film for heat dissipation with limited cooling power and fire risk,REC hydrogel can greatly improve the heat dissipation performance in the daytime with a high workload,indicating a 12.0℃lower temperature than the RC film under the same conditions in the outdoor experiment.In the nighttime with a low workload,RC-assisted adsorption can improve atmospheric water harvesting to ensure EC in the daytime.In addition,our REC hydrogel significantly enhanced flame retardancy by absorbing heat without a corresponding temperature rise,thus mitigating fire risks.Thus,our design shows a promising solution for the thermal management of outdoor devices,delivering outstanding performance in both heat dissipation and flame retardancy.展开更多
Understanding the shakedown behavior of fill material is paramount to estimate the deformation stability of railway subgrade.Especially for red mudstone fill material(RMF),the noticeable overestimation of bearing capa...Understanding the shakedown behavior of fill material is paramount to estimate the deformation stability of railway subgrade.Especially for red mudstone fill material(RMF),the noticeable overestimation of bearing capacity would be encountered if the conventional strength method is used.This paper presents the shakedown analysis on RMF,with a specific emphasis on the effect of water content.A series of cyclic triaxial tests with 50,000 loading cycles was conducted.Two-stage behavior of permanent deformation and dissipated energy responses was clearly characterized,from which an energy-based criterion was proposed to determine the shakedown limits.The proposed energy-based criterion was validated by examining its performance to various geomaterials including cohesive soils and unbound granular materials(UGMs).By applying the proposed method to RMF,the S-shape evolution curve was obtained in terms of shakedown limits with initial suction.Microfabric difference was believed as the main consequence of the S-shape mode.Demonstration was confirmed by the mercury intrusion porosimetry(MIP)and scanning electron microscope(SEM)analyses.By applying the proposed method to different geomaterials,an extensive comparison was made between the shakedown limits and the static shear strength.The ratio of shakedown limits to the static shear strength for saturated RMF specimen fell within the range of soft clays,while that of unsaturated specimen lies within the range of UGMs.展开更多
Nociceptive pain is a cardinal feature of traumatic and inflammatory bone diseases.However,whether and how nociceptors actively regulate the immune response during bone regeneration remains unclear.Here,we found that ...Nociceptive pain is a cardinal feature of traumatic and inflammatory bone diseases.However,whether and how nociceptors actively regulate the immune response during bone regeneration remains unclear.Here,we found that neutrophil-triggered nociceptive ingrowth functioned as negative feedback regulation to inflammation during bone healing.A unique Il4ra^(+)Ccl2^(high) neutrophil subset drove intense postinjury TRPV1^(+)nociceptive ingrowth,which in return dissipated inflammation by activating the production of pro-resolving mediator lipoxin A4(LXA4)in osteoblasts.Mechanistically,osteoblastic autophagy activated by nociceptor-derived calcitonin gene-related peptide(CGRP)suppressed the nuclear translocation of arachidonate 5-lipoxygenase(5-LOX)to favor the LXA4 biosynthesis.Moreover,in alveolar bone from patients with Type Ⅱ diabetes,we found diminished nociceptive innervation correlated with reduced autophagy,increased inflammation,and impaired bone formation.Activating nociceptive nerves by spicy diet or topical administration of a clinical-approved TRPV1 agonist showed therapeutic benefits on alveolar bone healing in diabetic mice.These results reveal a critical neuroimmune interaction underlying the inflammation-regeneration balance during bone repairing and may lead to novel therapeutic strategies for inflammatory bone diseases.展开更多
To enhance the mechanical reliability of dental prostheses under long-term service conditions,this study aimed to evaluate the fracture behavior and energy dissipation characteristics of three commonly used prosthetic...To enhance the mechanical reliability of dental prostheses under long-term service conditions,this study aimed to evaluate the fracture behavior and energy dissipation characteristics of three commonly used prosthetic materials,namely,zirconia ceramics(ZrO_(2)),cobalt-chromium alloy(Co-Cr),and titanium-zirconium alloy(Ti-13Zr),under various crack configurations.A three-dimensional finite element model of a single-crown prosthesis incorporating predefined cracks was established,and both axial and oblique multidirectional loads were applied.Using LS-DYNA software,the deformation patterns,principal stress distribution,and energy release characteristics during crack propagation were systematically analyzed.The experimental results indicate that Ti-13Zr alloy exhibited the highest crack resistance,making it particularly suitable for patients with insufficient bone volume or limited implant space.Co-Cr alloy demonstrated favorable structural stability and mechanical performance under high-load conditions.In contrast,due to its inherent brittleness,ZrO_(2)was more prone to rapid fracture propagation in long-span or high-stress scenarios,although it remains a preferred option for anterior esthetic zones and patients with metal sensitivities.Furthermore,the simulation outcomes were theoretically validated using Griffith's energy-based fracture criterion,reinforcing the accuracy of failure predictions based on principal stress analysis.This study elucidates the differences in clinical applicability among prosthetic materials and reveals their distinct fracture mechanisms,thereby providing a theoretical foundation for optimizing material selection and structural design.The findings contribute to improving the long-term safety and functional stability of implant-supported dental restorations.展开更多
To enhance the heat-dissipation capacity of infrared(IR)stealth structures in high-temperature environments,a selective heat emitter with multi-band thermal management is fabricated.This emitter comprises a hightemper...To enhance the heat-dissipation capacity of infrared(IR)stealth structures in high-temperature environments,a selective heat emitter with multi-band thermal management is fabricated.This emitter comprises a hightemperature-resistant titanium dioxide(TiO_(2))/hafnium dioxide(HfO_(2))/Cr/Ge/Mo multi-film-layer structure.Additionally,the thickness of each layer is determined by the transfer-matrix algorithm.The emissivity of the structure across the IR band is simulated,and its electric field distributions are analyzed across different wavelengths.The stealth-and heat-dissipation bands of the structure are calculated to confirm its overall stealth and heat-dissipation capabilities.The results reveal that the average emissivities of the fabricated TiO_(2)/HfO_(2)/Cr/Ge/Mo multi-film-layer structure decrease to 0.21 and 0.27 within 3-5 and 8-14μm atmospheric window bands,respectively,achieving the IR concealment effect.Conversely,the average emissivities of the structure increase to 0.56 and 0.80 within the 2.5-3 and 5-8μm non-atmospheric window(NAW)bands,respectively.These high-emissivity bands enhance radiative heat dissipation to reduce heat accumulation and further weaken the detection and characterization of thermal signals.The simulated thermal images confirm the IR-stealth effect of the structure within a wide temperature range.Moreover,its efficient NAW heat-dissipation capability improves its operating life in high-temperature environments.展开更多
Bolting steel angles at the bottom ends of columns provides a rapid and efficient method for repairing damaged structures,while also offering a viable approach to restore their potential bearing capacity.To validate t...Bolting steel angles at the bottom ends of columns provides a rapid and efficient method for repairing damaged structures,while also offering a viable approach to restore their potential bearing capacity.To validate the suitability of specific strengthening strategies,particularly the utilization of bolted steel angles,three reinforced concrete frame specimens were subjected to hysteresis testing.These specimens all featured RC columns strengthened with steel angle ends.Additionally,one control specimen without steel angle ends was included in the testing.The hysteresis effects of bolting steel angles were discussed in terms of typical failure mode,hysteresis and skeleton curves,stiffness degradation and energy dissipation.The experimental results revealed that the three specimens that had bolted steel angles exhibited ductile failure behavior.Through analysis of hysteresis and skeleton curves,it was observed that the frame demonstrated distinct plasticity,maintaining sufficient load-bearing capacity even after yielding and exhibiting superior displacement ductility performance.Considering equivalent viscous damping,the energy dissipation capacity of the RC frame increased linearly with drift and remained largely unaffected by structural damage.Therefore,bolting steel angles at specified cross-sections proved to be a viable technique for structural repair and restoration.展开更多
This paper proposes two types of integrated sound absorbing-insulating metamaterials with low thickness and efficient sound attenuation in the low-frequency bandwidth,i.e.,labyrinth-type metamaterial and multi-order r...This paper proposes two types of integrated sound absorbing-insulating metamaterials with low thickness and efficient sound attenuation in the low-frequency bandwidth,i.e.,labyrinth-type metamaterial and multi-order resonator metamaterial.The labyrinth-type metamaterial is designed through spatial dimension transfer,transferring the required dimension in the thickness direction to the planar thin layer.Based on the Helmholtz resonance,the metamaterial achieves noise reduction through the reflection of sound waves and the thermoviscous dissipation of holes and cavities.This mechanism enables its sound insulation performance to produce the same gain effect as absorption,thereby accomplishing the broadband absorbing-insulating integrated design.With a thickness of only 33 mm,it achieves both sound absorption and insulation effects over more than one octave.The multi-order resonator metamaterial has a larger working bandwidth than the labyrinth-type metamaterial.It is designed based on the multiorder resonance absorption mechanism,and consists of 9 different orders of resonator units.The metamaterial obtains a continuous sound absorption coefficient curve in the low-frequency range of 362–1712 Hz,and possesses high transmission loss(TL)above 346 Hz.In addition,this paper deeply explores the sound absorbing-insulating mechanism through the correlation analysis between the sound absorption coefficient and TL curves.The experimental results verify the continuous and efficient absorption effects of the two metamaterials,as well as their insulation performance that breaks the mass law.In low-frequency engineering applications,the two designed metamaterials demonstrate great potential and value at sub-wavelength dimensions.展开更多
基金supported by the National Natural Science Foundation of China(No.12271399)the Fundamental Research Funds for the Central Universities(No.3122025090)。
文摘This paper investigates global solutions and long-time dynamics for the stochastic reaction-diffusion equation du=(Δu+f(u)+g(x,t))dt+σ(u)dW on a bounded domain,where the drift term f(u),with polynomial growth rate β,is strongly dissipative and the diffusion term σ(u)has growth rate γ,satisfying β+1>2γ.Under this condition,we establish the existence,uniqueness,and regularity of solutions in Bochner spaces.Our analysis relies only on weak monotonicity conditions and requires no further growth restrictions on f andσ.Moreover,we prove the existence of a weak mean random attractor for the system.These results offer new insights into the balance mechanism between stochastic perturbations and dissipative effects in superlinear regimes.
基金This work was supported by National Natural Science Foundation of China (No. 60674026)Key Project of Chinese Ministry of Edu- cation (No. 107058)Jiangsu Provincial Natural Science Foundation of China (No. BK2007016)
文摘A new definition of dissipativity for neural networks is presented in this paper. By constructing proper Lyapunov functionals and using some analytic techniques, sufficient conditions are given to ensure the dissipativity of neural networks with or without time-varying parametric uncertainties and the integro-differential neural networks in terms of linear matrix inequalities. Numerical examples are given to illustrate the effectiveness of the obtained results.
基金Inner Mongolia University 2020 undergraduate teaching reform research and construction project-NDJG2094。
文摘This paper is concerned with the numerical dissipativity of multistep Runge-Kutta methods for nonlinear neutral delay-integro-differential equations.We investigate the dissipativity properties of-algebraically stable multistep Runge-Kutta methods with constrained grid.The finite-dimensional and infinite-dimensional dissipativity results of-algebraically stable multistep Runge-Kutta methods are obtained.
基金This work is supported by the National Natural Science Foundation of China(Grant No.10571147).
文摘The analytic and discretized dissipativity of nonlinear infinite-delay systems of the form x＇（t） = g（x（t）,x（qt））（q∈ （0, 1）, t 〉 0） is investigated. A sufficient condition is presented to ensure that the above nonlinear system is dissipative. It is proved the backward Euler method inherits the dissipativity of the underlying system. Numerical examples are given to confirm the theoretical results.
基金supported by National Natural Science Foundation of China (No. 11171125,91130003)Natural Science Foundation of Hubei (No. 2011CDB289)Youth Foundation of Naval University of Engineering (No.HGDQNJJ10003)
文摘This paper is concerned with the numerical dissipativity of multistep Runge-Kutta methods for nonlinear Volterra delay-integro-differential equations. We investigate the dissipativity properties of （k, l）- algebraically stable multistep Runge-Kutta methods with constrained grid and an uniform grid. The finite- dimensional and infinite-dimensional dissipativity results of （k, /）-algebraically stable Runge-Kutta methods are obtained.
基金This project is supported by NSF of China (No.10101012)Shanghai Rising Star Program (No.03QA14036) The Special Funds for Major Specialties of Shanghai Education Committee.
文摘This paper deals with analytic and numerical dissipativity and exponential stability of singularly perturbed delay differential equations with any bounded state-independent lag. Sufficient conditions will be presented to ensure that any solution of the singularly perturbed delay differential equations (DDEs) with a bounded lag is dissipative and exponentially stable uniformly for sufficiently small ε > 0. We will study the numerical solution defined by the linear θ-method and one-leg method and show that they are dissipative and exponentially stable uniformly for sufficiently small ε > 0 if and only if θ = 1.
基金The authors would like to thank the editors and reviewers for their valuable comments and constructive suggestions which improved the quality of the paper. This work is supported by the National Natural Science Foundation of China （Grant Nos. 11661054 and 11461053）.
文摘In this paper, a class of stochastic Lotka Volterra system with feedback controls is considered. The purpose is to establish some criteria to ensure the system is globally dissipative in the mean square. By constructing suitable Lyapunov functions as well as combining with Jensen inequality and Ito formula, the sufficient conditions are established and they are expressed in terms of the feasibility to a couple linear matrix inequalities （LMIs）. Finally, the main results are illustrated by examples.
基金Guangdong Basic and Applied Basic Research Foundation (2024A1515011873)Shenzhen Basic Research Project (JCYJ20241202123504007)Shenzhen Science and Technology Innovation Commission (KJZD20240903101400001, KJZD20240903102006009)。
文摘A multi-physics approach was used to quantify the effect of process parameters (laser power, scanning speed, hatch spacing, and scanning strategy) on the thermal history and corresponding microstructure evolution of Ti-25Nb (at%) alloy during the dual-track selective laser melting (SLM) process. Simulation results reveal that during the dual-track SLM process, increasing laser power results in greater thermal accumulation, leading to a molten pool of larger volume and coarser grains. Reducing scanning speed enhances remelting and promotes cellular growth at the top of molten pool, whereas faster scanning speed leads to rougher melt tracks and finer grains. Notably, hatch spacing significantly influences the molten pool dimensions and microstructures, and smaller hatch spacing promotes remelting. Furthermore, the orientations of grains in the second track during zigzag scanning differ markedly from those in the first track. More importantly, compared with those after the first track, both the temperature gradient and cooling rate at the boundaries of remelting molten pool are reduced after the second track scanning, resulting in slower interface velocity and significant change in solidification microstructure. This research provides a theoretical foundation for controlling non-equilibrium microstructure and offering novel insights into the optimization of SLM process parameters of titanium alloys.
基金supported by the National Science Foundation of Tianjin(No.18JCYBJC85800)Innovation Project for Young and Middle-aged Key Teachers in Tianjin Universities(No.135205GC38).
文摘This paper pays close attention to the global polynomial dissipativity(GPD)for proportional delayed BAM neural networks(PDBAMNNs).The global exponential dissipativity(GED)and the global dissipativity(GD)are also talked about.Under the help of novel Lyapunov functionals and a generalized Halanay inequality,a set of dissipative criteria for such systems are led out,together with the global polynomial attracting set(GPAS)and the global attracting set(GAS).Further,the relationship among GPD,GED and GD is unveiled.Finally,a proposed theoretical condition is validated through a simulation experiment.
基金supported by the Foundation of Central Universities of Education Department of China(Grant No.2021YQJD31).
文摘Optimization of heat and mass transfer between humid air and water can signicantly enhance the performance of HVAC sys-tems and equipment.Based on entransy theory,this study examines how entransy dissipation varies in moist air and water un-der isothermal and isenthalpic conditions within a vertical spray chamber.An entransy dissipation coefcient,X,is dened to quantify the irreversibility of the heat and mass transfer process.The results reveal that for a given heat exchange between moist air and water,when the inlet moist air is near saturation the system achieves minimal entransy dissipation,reduced mois-ture-based thermal resistance(TRMED),and a lower X value,indicating that the overall heat and mass transfer losses are nearly minimized.
基金supported by the Henan Provincial Key Research and Development Special Project(251111220200)Natural Science Foundation of Henan Province Project(252300420446).
文摘To explore the distribution law of the temperature field in the motor pump and the influence of the fanshaped DC channel with spoiler in the pump housing on its heat dissipation performance.This study takes the arc-gear type hydraulicmotor pump as the research object.In COMSOL,a coupled heat transfer simulationmodel of themotor pump’s fluid-solid coupling is established,and the internal temperature field characteristics are analyzed.To improve the heat dissipation effect of the motor pump,it is proposed to arrange spoiler in the fan-shaped DC channel of the pump housing to enhance heat dissipation.Three types of spoilers,namely,wing-shaped,inclined rectangle-shaped,and wave-shaped,are designed.The simulation results show that when the motor pump operates under rated conditions,due to the poor heat dissipation environment inside the motor pump,the high-temperature areas of the motor pump are concentrated in the rotor and permanent magnet parts.After arranging the spoiler,the turbulent kinetic energy and vorticity in the fan-shaped DC channel of the pump housing are significantly enhanced.All three spoiler structures can reduce the maximum temperature of each component of the motor.According to the comprehensive performance evaluation criterion(PEC),the inclined rectangle-shaped structure has the best comprehensive heat transfer performance(PEC=1.114),while the wave-shaped structure has higher heat transfer efficiency but greater pressure loss.The wing-shaped structure has relatively limited enhancement effect on heat dissipation.This study systematically quantifies the influence of different spoiler structures on heat dissipation performance and flowresistance characteristics,providing a solution for enhancing the heat dissipation of the motor pump.
基金financially supported by the National Key Research and Development Program of China(2022YFD1600803)the National Natural Science Foundation of China(31772077)+1 种基金the Yunnan Provincial Tea Industry Technology Innovation Center,China(202505AK340010)the Chinese Academy of Agricultural Sciences for Agricultural Science and Technology Innovation Program of Tea Research Institute(CAAS-ASTIP-2021-TRI)。
文摘China has limited acaricide options for tea plantations.Cyetpyrafen,a novel domestic acaricide with high efficacy,low toxicity and a negative temperature coefficient,offers an alternative for tea pest control;however,its residue fate in tea remains unclear.This study developed a method to simultaneously detect cyetpyrafen and its metabolites(M-309,M-325-1,and M-409-3)in different tea matrices to investigate their fate.Recoveries of compounds ranged from 73.4 to 106.2%with the relative standard deviations(RSDs)below 12.0%.During tea cultivation,the dissipation half-life of cyetpyrafen was 0.59 d,with M-309 as a major metabolite.The residues of cyetpyrafen and M-309 were affected by different processing stages,especially water loss and high temperatures during fixing,drying and withering.The total processing factors ranged from 1.39 to 1.71 for green tea and 1.48 to 2.28 for black tea(processed from fresh tea leaves sampled at 1,5,and 7 d),respectively.The leaching rates of cyetpyrafen from green tea and black tea into tea infusions were 7.4 and 6%,respectively.The risk associated with cyetpyrafen intake from tea consumption was low,with risk quotient values below 100%.However,theoretical calculation indicated potential harm to non-target organisms from its metabolites.This research provides a reference for the safe and efficient use of cyetpyrafen in tea gardens.
基金funded by the National Natural Science Foundation of China(No.52474120)the National Key Research and Development Program of China—2023 Key Special Project(No.2023YFC2907400)+1 种基金the Fundamental Research Funds for the Central Universities(No.2023CXQD045)the Hunan Provincial Natural Science Foundation for Distinguished Young Scholars(No.2023JJ10072).
文摘A critical scientific gap exists in quantifying the intrinsic mechanisms of shale mechanical property degradation induced by the combined effects of perforation(impact)and acidization—two core techniques for shale reservoir permeability enhancement.To address this gap,this study proposed an innovative coupled experimental framework integrating dynamic-static cyclic loading(to simulate perforation impact)and acid erosion.Static uniaxial compression tests were performed on treated damaged shale samples,with microstructural characterization via X-ray diffraction(XRD)and scanning electron microscopy(SEM).Key findings include:(1)The damage factor(characterized by longitudinal wave velocity)showed a significant positive correlation with acid concentration;(2)Combined damage(impact+acidization)caused far more severe mechanical deterioration than single damage modes—for instance,samples under combined damage with 20%hydrochloric acid exhibited a strength reduction to 158.97 MPa,with sharp decreases in peak strength and elastic modulus;(3)Damage reduced total energy and elastic strain energy of samples while increasing dissipated energy proportion,leading to more developed internal fractures and severe failure in combined damage samples;(4)Acidization promoted sample fragmentation into smaller debris,resulting in significantly higher fractal dimensions of acidized shale than other damage types under the same acid concentration;(5)XRD and SEM analyses confirmed that high-concentration acid erosion reduced shale carbonate content,and the synergy of mechanical pre-damage and chemical dissolution in combined damage accelerated acid-rock reactions,significantly increasing micro-interfacial pores and degrading shale structural integrity.This study’s innovation lies in establishing a coupled experimental framework that reproduces the actual“perforation-acidization”sequence,quantitatively revealing the synergistic degradation mechanism of shale mechanical properties under combined damage—providing a novel theoretical basis for optimizing shale reservoir stimulation parameters.
基金financially supported by the Science and Technology Innovation Program of Hunan Province(2024RC3003)the Central South University Innovation-Driven Research Programme(2023CXQD012)the Initiative for Sustainable Energy for its financial support。
文摘By combining the merits of radiative cooling(RC)and evaporation cooling(EC),radiative coupled evaporative cooling(REC)has attracted considerable attention for sub-ambient cooling purposes.However,for outdoor devices,the interior heating power would increase the working temperature and fire risk,which would suppress their above-ambient heat dissipation capabilities and passive water cycle properties.In this work,we introduced a REC design based on an all-in-one photonic hydrogel for above-ambient heat dissipation and flame retardancy.Unlike conventional design RC film for heat dissipation with limited cooling power and fire risk,REC hydrogel can greatly improve the heat dissipation performance in the daytime with a high workload,indicating a 12.0℃lower temperature than the RC film under the same conditions in the outdoor experiment.In the nighttime with a low workload,RC-assisted adsorption can improve atmospheric water harvesting to ensure EC in the daytime.In addition,our REC hydrogel significantly enhanced flame retardancy by absorbing heat without a corresponding temperature rise,thus mitigating fire risks.Thus,our design shows a promising solution for the thermal management of outdoor devices,delivering outstanding performance in both heat dissipation and flame retardancy.
基金support from the National Natural Science Foundation of China(Grant Nos.52278432 and 52478475)the Science and Technology Research and Development Plan of China National Railway Group Co.,Ltd.(Grant No.K2023G033)were greatly appreciated.
文摘Understanding the shakedown behavior of fill material is paramount to estimate the deformation stability of railway subgrade.Especially for red mudstone fill material(RMF),the noticeable overestimation of bearing capacity would be encountered if the conventional strength method is used.This paper presents the shakedown analysis on RMF,with a specific emphasis on the effect of water content.A series of cyclic triaxial tests with 50,000 loading cycles was conducted.Two-stage behavior of permanent deformation and dissipated energy responses was clearly characterized,from which an energy-based criterion was proposed to determine the shakedown limits.The proposed energy-based criterion was validated by examining its performance to various geomaterials including cohesive soils and unbound granular materials(UGMs).By applying the proposed method to RMF,the S-shape evolution curve was obtained in terms of shakedown limits with initial suction.Microfabric difference was believed as the main consequence of the S-shape mode.Demonstration was confirmed by the mercury intrusion porosimetry(MIP)and scanning electron microscope(SEM)analyses.By applying the proposed method to different geomaterials,an extensive comparison was made between the shakedown limits and the static shear strength.The ratio of shakedown limits to the static shear strength for saturated RMF specimen fell within the range of soft clays,while that of unsaturated specimen lies within the range of UGMs.
基金The National Natural Science Foundation of China(No.82130027,82301020,82100966)Young Elite Scientists Sponsorship Program by CAST(2024QNRC001)+5 种基金The China Postdoctoral Science Foundation(2023M732283)The National Key Research and Development Program of China(No.2023YFC2413600)The Shanghai Sailing Program(23YF1422000,21YF1424400)Innovative Research Team of High-level Local Universities in Shanghai(SHSMU-ZLCX20212400)Young Elite Scientists Sponsorship Program by CAST(2021QNRC001)Shanghai Pujiang Program(24PJD054).
文摘Nociceptive pain is a cardinal feature of traumatic and inflammatory bone diseases.However,whether and how nociceptors actively regulate the immune response during bone regeneration remains unclear.Here,we found that neutrophil-triggered nociceptive ingrowth functioned as negative feedback regulation to inflammation during bone healing.A unique Il4ra^(+)Ccl2^(high) neutrophil subset drove intense postinjury TRPV1^(+)nociceptive ingrowth,which in return dissipated inflammation by activating the production of pro-resolving mediator lipoxin A4(LXA4)in osteoblasts.Mechanistically,osteoblastic autophagy activated by nociceptor-derived calcitonin gene-related peptide(CGRP)suppressed the nuclear translocation of arachidonate 5-lipoxygenase(5-LOX)to favor the LXA4 biosynthesis.Moreover,in alveolar bone from patients with Type Ⅱ diabetes,we found diminished nociceptive innervation correlated with reduced autophagy,increased inflammation,and impaired bone formation.Activating nociceptive nerves by spicy diet or topical administration of a clinical-approved TRPV1 agonist showed therapeutic benefits on alveolar bone healing in diabetic mice.These results reveal a critical neuroimmune interaction underlying the inflammation-regeneration balance during bone repairing and may lead to novel therapeutic strategies for inflammatory bone diseases.
基金Funded by the National Key R&D Program of China(No.2023YFC2412300)the Technology Development Project of Shan-dong Weigao Orthopedic Materials Co.,Ltd.(No.20221h0074)the Independent Innovation Research Fund of Wuhan University of Technology(No.104972024ZHZXhp0027)。
文摘To enhance the mechanical reliability of dental prostheses under long-term service conditions,this study aimed to evaluate the fracture behavior and energy dissipation characteristics of three commonly used prosthetic materials,namely,zirconia ceramics(ZrO_(2)),cobalt-chromium alloy(Co-Cr),and titanium-zirconium alloy(Ti-13Zr),under various crack configurations.A three-dimensional finite element model of a single-crown prosthesis incorporating predefined cracks was established,and both axial and oblique multidirectional loads were applied.Using LS-DYNA software,the deformation patterns,principal stress distribution,and energy release characteristics during crack propagation were systematically analyzed.The experimental results indicate that Ti-13Zr alloy exhibited the highest crack resistance,making it particularly suitable for patients with insufficient bone volume or limited implant space.Co-Cr alloy demonstrated favorable structural stability and mechanical performance under high-load conditions.In contrast,due to its inherent brittleness,ZrO_(2)was more prone to rapid fracture propagation in long-span or high-stress scenarios,although it remains a preferred option for anterior esthetic zones and patients with metal sensitivities.Furthermore,the simulation outcomes were theoretically validated using Griffith's energy-based fracture criterion,reinforcing the accuracy of failure predictions based on principal stress analysis.This study elucidates the differences in clinical applicability among prosthetic materials and reveals their distinct fracture mechanisms,thereby providing a theoretical foundation for optimizing material selection and structural design.The findings contribute to improving the long-term safety and functional stability of implant-supported dental restorations.
基金The National Natural Science Foundation of China(No.52106099)the Science and Technology Development Joint Fundof Henan province(No.225200810077).
文摘To enhance the heat-dissipation capacity of infrared(IR)stealth structures in high-temperature environments,a selective heat emitter with multi-band thermal management is fabricated.This emitter comprises a hightemperature-resistant titanium dioxide(TiO_(2))/hafnium dioxide(HfO_(2))/Cr/Ge/Mo multi-film-layer structure.Additionally,the thickness of each layer is determined by the transfer-matrix algorithm.The emissivity of the structure across the IR band is simulated,and its electric field distributions are analyzed across different wavelengths.The stealth-and heat-dissipation bands of the structure are calculated to confirm its overall stealth and heat-dissipation capabilities.The results reveal that the average emissivities of the fabricated TiO_(2)/HfO_(2)/Cr/Ge/Mo multi-film-layer structure decrease to 0.21 and 0.27 within 3-5 and 8-14μm atmospheric window bands,respectively,achieving the IR concealment effect.Conversely,the average emissivities of the structure increase to 0.56 and 0.80 within the 2.5-3 and 5-8μm non-atmospheric window(NAW)bands,respectively.These high-emissivity bands enhance radiative heat dissipation to reduce heat accumulation and further weaken the detection and characterization of thermal signals.The simulated thermal images confirm the IR-stealth effect of the structure within a wide temperature range.Moreover,its efficient NAW heat-dissipation capability improves its operating life in high-temperature environments.
基金National Key R&D Program of China under Grant No.2023YFC3805100Technologies R&D Project of China Construction First Group Corporation Limited under Grant No.PT-2022-09National Natural Science Foundation of China under Grant No.52178126。
文摘Bolting steel angles at the bottom ends of columns provides a rapid and efficient method for repairing damaged structures,while also offering a viable approach to restore their potential bearing capacity.To validate the suitability of specific strengthening strategies,particularly the utilization of bolted steel angles,three reinforced concrete frame specimens were subjected to hysteresis testing.These specimens all featured RC columns strengthened with steel angle ends.Additionally,one control specimen without steel angle ends was included in the testing.The hysteresis effects of bolting steel angles were discussed in terms of typical failure mode,hysteresis and skeleton curves,stiffness degradation and energy dissipation.The experimental results revealed that the three specimens that had bolted steel angles exhibited ductile failure behavior.Through analysis of hysteresis and skeleton curves,it was observed that the frame demonstrated distinct plasticity,maintaining sufficient load-bearing capacity even after yielding and exhibiting superior displacement ductility performance.Considering equivalent viscous damping,the energy dissipation capacity of the RC frame increased linearly with drift and remained largely unaffected by structural damage.Therefore,bolting steel angles at specified cross-sections proved to be a viable technique for structural repair and restoration.
基金Project supported by the National Natural Science Foundation of China(No.52250287)the Outstanding Youth Science Fund Project of Shaanxi Province of China(No.2024JC-JCQN-49)。
文摘This paper proposes two types of integrated sound absorbing-insulating metamaterials with low thickness and efficient sound attenuation in the low-frequency bandwidth,i.e.,labyrinth-type metamaterial and multi-order resonator metamaterial.The labyrinth-type metamaterial is designed through spatial dimension transfer,transferring the required dimension in the thickness direction to the planar thin layer.Based on the Helmholtz resonance,the metamaterial achieves noise reduction through the reflection of sound waves and the thermoviscous dissipation of holes and cavities.This mechanism enables its sound insulation performance to produce the same gain effect as absorption,thereby accomplishing the broadband absorbing-insulating integrated design.With a thickness of only 33 mm,it achieves both sound absorption and insulation effects over more than one octave.The multi-order resonator metamaterial has a larger working bandwidth than the labyrinth-type metamaterial.It is designed based on the multiorder resonance absorption mechanism,and consists of 9 different orders of resonator units.The metamaterial obtains a continuous sound absorption coefficient curve in the low-frequency range of 362–1712 Hz,and possesses high transmission loss(TL)above 346 Hz.In addition,this paper deeply explores the sound absorbing-insulating mechanism through the correlation analysis between the sound absorption coefficient and TL curves.The experimental results verify the continuous and efficient absorption effects of the two metamaterials,as well as their insulation performance that breaks the mass law.In low-frequency engineering applications,the two designed metamaterials demonstrate great potential and value at sub-wavelength dimensions.
