In ecological environments,the survival environment of species is often inhomogeneous,and the reproductive process is affected by time delay.System with nonlocal effects and delay can more accurately simulate changes ...In ecological environments,the survival environment of species is often inhomogeneous,and the reproductive process is affected by time delay.System with nonlocal effects and delay can more accurately simulate changes in population density.In this paper,we consider a reaction-diffusion-advection model with nonlocal delay and Dirichlet boundary conditions.First of all,we investigate the well-posedness of solution of model.Then,the existence of positive steady state is proofed by implicit function theorem.Based on a priori estimate for the eigenvalue,we prove the stability of the positive steady state and conclude the associated distribution of Hopf bifurcation.Our research indicates that the combined effects of nonlocal and time delays have a certain impact on the dynamics of the model.展开更多
We investigate a class of non-integrable two-particle Calogero-Moser systems modulated by a power-law external potential.The local well-posedness of the Cauchy problem is established under the strict initial separatio...We investigate a class of non-integrable two-particle Calogero-Moser systems modulated by a power-law external potential.The local well-posedness of the Cauchy problem is established under the strict initial separation condition for the particles.For suitably prepared initial configurations,local solutions can be extended globally via energy conservation;conversely,negative energy conditions induce(in)finite-time blowup.The linear(in)stability of stationary solutions is analyzed,with their energy serving as a threshold.Numerical investigations employ a fourth-order Runge-Kutta scheme with adaptive step-size control.Simulations demonstrate that the trajectories either converge to steady states or exhibit blowup,depending on the power exponent α and initial conditions.Increasingαaccelerates the convergence rate and dampens oscillatory dynamics,promoting a transition from periodic behavior to static equilibrium.展开更多
In this paper,a high-fidelity computational fluid dynamics(CFD)and rigid body dynamics(RBD)coupled platform for virtual flight simulation is developed to investigate the flight stability of fixed canard dual-spin proj...In this paper,a high-fidelity computational fluid dynamics(CFD)and rigid body dynamics(RBD)coupled platform for virtual flight simulation is developed to investigate the flight stability of fixed canard dual-spin projectile.The platform's reliability is validated by reproducing the characteristic resonance instability of such projectiles.By coupling the solution of the Unsteady Reynolds-Averaged Navier-Stokes equations and the seven-degree-of-freedom RBD equations,the virtual flight simulations of fixed canard dual-spin projectiles at various curvature trajectories are achieved,and the dynamic mechanism of the trajectory following process is analyzed.The instability mechanism of the dynamic instability during trajectory following process of the fixed canard dual-spin projectile is elucidated by simulating the rolling/coning coupled forced motion,and subsequently validated through virtual flight simulations.The findings suggest that an appropriate yaw moment can drive the projectile axis to precession in the tangential direction of the trajectory,thereby enhancing the trajectory following stability.However,the damping of the projectile attains its minimum value when the forward body equilibrium rotational speed(-128 rad/s)is equal to the negative of the fast mode frequency of the projectile.Insufficient damping leads to the fixed canard dual-spin projectile exiting the dynamic stability domain during the trajectory following,resulting in weakly damped instability.Keeping the forward body not rotating or increasing the spin rates to-192 rad/s can enhance the projectile's damping,thereby improving its dynamic stability.展开更多
The simultaneous integration of high energy density,low sensitivity,and thermal stability in energetic materials has constituted a century-long scientific challenge.Herein,we address this through a dualzwitterionic el...The simultaneous integration of high energy density,low sensitivity,and thermal stability in energetic materials has constituted a century-long scientific challenge.Herein,we address this through a dualzwitterionic electronic delocalization strategy,yielding TYX-3,the first bis-inner salt triazolo-tetrazine framework combining these mutually exclusive properties.Uniformπ-electron distribution and elevated bond dissociation energy confer exceptional thermal stability(T_(d)=365℃)with TATB-level insensitivity(impact sensitivity IS>40 J,friction sensitivity FS>360 N).Engineeredπ-stacked networks enable record density(1.99 g·cm^(-3))with detonation performance surpassing HMX benchmarks(detonation velocity 9315 m·s^(-1),detonation pressure 36.6 GPa).Practical implementation in Poly(3-nitratomethyl-3-methyloxetane)(PNMMFO)solid propellants demonstrates 5.4-fold safety enhancement over conventional HMX-based formulations while maintaining equivalent specific impulse.This work establishes a new design paradigm for energetic materials,overcoming the historical trade-offs between molecular stability and energy output through rational zwitterionic engineering.展开更多
The paper considers the methodology for a comprehensive analysis of the stability of an open pit-dump system,using limit equilibrium(LEM)and finite element(FEM)methods in the Russian CAE(computer-aided engineering)sof...The paper considers the methodology for a comprehensive analysis of the stability of an open pit-dump system,using limit equilibrium(LEM)and finite element(FEM)methods in the Russian CAE(computer-aided engineering)software Fidesys.It briefly highlights the issues of comparing limit equilibrium methods using the VNIMI(Research Institute of Geomechanics and Mine Surveying-Intersectoral Scientific Center"VNIMI")methodology and a specialized software product with numerical methods.The main focus of this study is to compare the results of the stability analysis in the volumetric model of the open pit-dump system using limit equilibrium and finite element methods in the CAE software Fidesys.It was found that,when modeling the combined operation of an open pit-dump system in complex terrain,both methods should be used,as each has its own advantages.The finite element method,for instance,has certain features that are not present in the calculations using the limit equilibrium approach.As a key scientific contribution,this paper introduces an automation program for calculating the stability of open-pit walls using the limit equilibrium method in CAE Fidesys,which was not previously integrated in the original software.The calculations performed with the use of this newly developed module were compared to those obtained from other widely used software solutions available on the market.The findings demonstrate a remarkable level of convergence in the calculation results for all relevant parameters,including the safety factor,localization,instability type,and deformation.The proposed approach i mproves the accuracy of calculati ons and ensures consistency between the higher stress design zones and the actual deformation and fracture patterns.It also enhances the ability to predict the behavior of rock mass when calculating stability parameters for facilities,both during operation and desi gn.展开更多
Lithium-sulfur(Li-S)batteries have great promise for next-generation energy storage devices due to the high theoretical specific capacity(1675 mAh g^(-1))of sulfur with chemical conversion for charge storage.However,t...Lithium-sulfur(Li-S)batteries have great promise for next-generation energy storage devices due to the high theoretical specific capacity(1675 mAh g^(-1))of sulfur with chemical conversion for charge storage.However,their practical use is hindered by the slow redox kinetics of sulfur and the“shuttle effect”arising from dissolved lithium polysulfides(LiPSs).In recent years,various carbon-based materials have served as sulfur hosts and catalysts for accelerating sulfur conversion redox kinetics and alleviating LiPS shuttling.However,they often suffer from irreversible passivation and structural changes that destroy their long-term performance.We consider the main problems limiting their stability,including excessive LiPS adsorption,passivation by insulating Li2S,and surface reconstruction,and clarify how these factors lead to capacity fade.We then outline effective strategies for achieving long-term sulfur catalysis,focusing on functional carbon,such as designing suitable carbon-supported catalyst interfaces,creating well-distributed active sites,adding cocatalysts to improve electron transfer,and using carbon-based protective layers to suppress unwanted side reactions.Using this information should enable the development of stable,high-activity catalysts capable of long-term operation under practical conditions in Li-S batteries.展开更多
Thermal quenching(TQ)at elevated temperature is a major factor affecting the luminescent intensity and efficiency of phosphors.Improving the thermal stability of phosphors and weakening the TQ effect are of significan...Thermal quenching(TQ)at elevated temperature is a major factor affecting the luminescent intensity and efficiency of phosphors.Improving the thermal stability of phosphors and weakening the TQ effect are of significance for the high-quality illumination of phosphor-converted WLEDs.Here,a novel red-emitting phosphor K_(2)Zn(PO_(3))_(4)∶Mn^(2+)is synthesized by standard high temperature solid state reaction in ambient atmosphere,which is a new member of self-reduction system.An effective synthesis strategy is proposed to optimize its photoluminescent performances.Combined with X-ray photoelectron spectroscopy and X-ray absorption fine structure spectroscopy,oxygen vacancy defects introduced by Mn doping are proved to play an important role in the transition of Mn^(4+)→Mn^(2+).Thermoluminescence analysis reveals that the distribution of trap levels,especially the deep ones,is effectively regulated by the controllable crystallization and significantly affect the thermal stability of phosphors.Then a defect-assisted model is proposed to address the inner mechanism of the phenomenon.The carriers trapped by deep trap levels can be released under the high-temperature stimulus,which return back to the luminescent centers and participate in the radiative recombination to improve thermal stability.This study provides a new crystallographic idea and theoretical support for obtaining luminescent materials with high thermal stability.展开更多
To study the rolling motion of a ship in the presence of water on its deck,a linear-plus-quadratic damping term was incorporated into its equation of motion.Ship model tests indicates that the key dynamics of the phys...To study the rolling motion of a ship in the presence of water on its deck,a linear-plus-quadratic damping term was incorporated into its equation of motion.Ship model tests indicates that the key dynamics of the physical system are preserved in the ship rolling equation with the linear-plus-quadratic type damping term.To take into account the presence of randomness in the excitation and the response,a new method was developed and a Melnikov criterion was obtained to provide an upper bound on the domain of the potential chaotic rolling motion(erratic rocking).Additionally,the Melnikov criterion proposed in this study was verified by the utilization of phase plane diagrams and Poincare maps.Furthermore,this research has made the initial endeavor to systematically modify the system parameters in the rolling equation of motion for ship stability analysis.展开更多
Practical application of Na_(3)SbS_(4)(NSS)solid-state electrolyte in sodium metal batteries has been significantly hindered by poor interfacial stability and insufficient ionic conductivity.In this study,a series of ...Practical application of Na_(3)SbS_(4)(NSS)solid-state electrolyte in sodium metal batteries has been significantly hindered by poor interfacial stability and insufficient ionic conductivity.In this study,a series of dual-site doped Na_(3-2x)Sb_(1-x)W_(x)S_(4-x)F_(x)(x=0,0.12,0.24,0.36)electrolytes through high-energy ball milling followed by high-temperature sintering is prepared,where tungsten(W)substitutes for antimony(Sb)and fluorine(F)replaces sulfur(S)in the NSS lattice.The co-doping of W and F not only broadens the interplanar spacing of NSS but also promotes the stable formation of the cubic phase of NSS,thereby effectively enhancing the transport ability of sodium ions within NSS.Among them,Na_(2.52)Sb_(0.76)W_(0.24)S_(3.76)F_(0.24) exhibits the highest ionic conductivity of 4.45 mS·cm^(-1).Furthermore,F doping facilitates the in-situ formation of NaF between the electrolyte and metallic sodium,significantly improving interfacial stability.Electrochemical evaluation shows that the Na/Na_(2.52)Sb_(0.76)W_(0.24)S_(3.76)F_(0.24)/Na symmetric cell achieves a high critical current density of 1.65 mA·cm^(-2) and maintains stable sodium plating/stripping cycling for 500 h at 0.1 mA·cm^(-2).Additionally,the TiS2/Na_(2.52)Sb_(0.76)W_(0.24)S_(3.76)F_(0.24)/Na full cell exhibits outstanding cycling stability and rate capability.展开更多
Alpha-aluminum hydride(α-AlH_(3))is usually metastable due to the small enthalpy of formation,poor stability,high chemical activity,sensitivity to moisture and easy combination with water in the air.In order to inhib...Alpha-aluminum hydride(α-AlH_(3))is usually metastable due to the small enthalpy of formation,poor stability,high chemical activity,sensitivity to moisture and easy combination with water in the air.In order to inhibit the hygroscopicity ofα-AlH_(3) and improve its storage and stability,paraffin wax(PW)is selected as the coating material,and the solvent/non-solvent method is usually used to coat the surface ofα-AlH_(3).The structure and topography ofα-AlH_(3) before and after being coated by PW were characterized by Fourier transform infrared spectroscopy(FT-IR),X-ray diffractometer(XRD),X-ray electron spectroscopy(XPS),elemental analysis,and scanning electron microscopy(SEM).The results show that PW can form a uniform and complete coating layer on the surface ofα-AlH_(3),and the crystal structure and morphology of theα-AlH_(3) coated by PW are not changed.The moisture absorption weight gain rate is reduced from 12%to 0.8%,and the hygroscopicity is greatly reduced.Furthermore,theα-AlH_(3) coated by PW also showed excellent performance in resisting water erosion after theα-AlH_(3) coated by PW,and the hydrophobic angle increases from 27°to 98°after theα-AlH_(3) surface being coated by PW.展开更多
Rich-nickel layered ternary NCM811 has been widely used in the field of electric vehicles ascribed to its high theoretical specific capacity.However,poor cycling stability and rate-performance hindered its further dev...Rich-nickel layered ternary NCM811 has been widely used in the field of electric vehicles ascribed to its high theoretical specific capacity.However,poor cycling stability and rate-performance hindered its further development.Herein,different amounts of nitrogen-doped carbon were wrapped on the surface of NCM811 via a facile rheological phase method by regulating the amount of dopamine hydrochloride.The effects of the coating amounts on the structure and electrochemical performance are investigated.The DFT calculation,XRD,SEM and XPS reveal that an appropriate amount of nitrogen-doped carbon coating could uniformly form a protective layer on the NCM811 surface and the introduced N could anchor Ni atoms to inhibit the Li^(+)/Ni^(2+)mixing,but excessive amount would reduce Ni^(3+)to Ni^(2+)so as to conversely aggravate Li^(+)/Ni^(2+)mixing.Among the samples,the NCM811-CN0.75 sample exhibits the most excellent electrochemical performance,delivering a high-rate capacity of 151.6 mA·h/g at 10C,and long-term cyclability with 82.2%capacity retention after 300 cycles at 5C,exhibiting remarkable rate-performance and cyclability.展开更多
To accurately identify the factors affecting the formation of stable aggregates in bauxite residue during the soil formation process,the comprehensive effects of a combined chemical-biological amelioration strategy in...To accurately identify the factors affecting the formation of stable aggregates in bauxite residue during the soil formation process,the comprehensive effects of a combined chemical-biological amelioration strategy including solid wastes and a functional microorganism on aggregate size distribution and its stability in bauxite residue were investigated during a 365-d simulation experiment.The results showed that the combined amelioration effectively reduced the saline alkalinity of bauxite residue,and markedly changed the contents of aggregate-associated chemical binding agents.Desulfurization gypsum and maize straw-Penicillium oxalicum(P.oxalicum)differentiated the formation of aggregates within different sizes.Maize straw-P.oxalicum stimulated the formation of water-stable macroaggregates with more durable erosion resistance by the wet-sieving and laser dynamic diffraction analysis.The Pearson correlation analysis showed that exchangeable polyvalent metal ions,pyrophosphate extractable Fe oxide,and organic carbon exhibited positive correlations with aggregate stability during the 365-d incubation.The findings in this study may provide data support and engineering practical reference for ecological restoration in the disposal areas.展开更多
Background Hybrid cotton enjoys overwhelming patronage among cotton farmers because of its superior yield capacity and fiber quality.However,various environmental factors affect its yield and fiber quality.This study ...Background Hybrid cotton enjoys overwhelming patronage among cotton farmers because of its superior yield capacity and fiber quality.However,various environmental factors affect its yield and fiber quality.This study aimed to assess 30 cotton hybrids for the stability of four traits(single-plant seed cotton yield,fiber upper half mean length(UHML),fiber strength,and micronaire)across three environments.Recent techniques,including genotype and genotype×environment(GGE)biplot,which provides a visual representation of performance and adaptability;weighted average absolute scores of the best linear unbiased predictions(WAASB),which balances the performance of the trait with stability;and multi-trait stability index(MTSI),which integrates multi-trait performance and stability,were used to analyze the stability of the four traits.Results Analysis of variance revealed significant genotype and environment interactions for all the traits studied,highlighting the need for comprehensive stability analysis.The environment E2 was the most suitable for the evaluation of seed cotton yield,whereas E3 was suitable for the evaluation of UHML and fiber strength.A stable hybrid,H05(TVH002×MCU5),with superior performance for seed cotton yield and UHML,was identified based on the overall results from GGE and WAASB.The which-won-where bioplot showed that H25(SVPR3×MCU5)performed the best for seed cotton yield in E3,and H27(Suraj×Sunantha)in E2 and E1.The hybrid H04(TVH002×CO14)in E1 and H30(Suraj×MCU5)in E2 and E3 performed well for UHML.Similarly,H28(Suraj×Suraksha)for E2 and E3 and H26(Suraj×Subiksha)for E1 were the best performing in the case of fiber strength.Based on the MTSI,four promising hybrids,namely,H24(SVPR3×CO14),H09(TVH2010×CO14),H18(MCU7×Suraksha),and H29(Suraj×CO14),were identified as stable with average performance for all four traits.Conclusions The study identified a stable hybrid,H05(TVH002×MCU5),with superior performance for yield and UHML.The identified hybrids in this study hold significant potential for cultivation across Tamil Nadu,with a scope for further evaluation in diverse environments.展开更多
The“upper coal and lower bauxite”resource distribution pattern is widespread in China,where mining of the overlying coal seam significantly alters the stress environment of the underlying bauxite layer.This study in...The“upper coal and lower bauxite”resource distribution pattern is widespread in China,where mining of the overlying coal seam significantly alters the stress environment of the underlying bauxite layer.This study investigates the stability of inclined bauxite pillars under the influence of stress redistribution caused by coal seam extraction.A theoretical model is developed to calculate the direction and magnitude of principal stresses in the inclined floor strata,and a pillar stability analysis model is established that considers the effect of principal stress rotation.The research employs a combination of theoretical analysis,physical modeling,numerical simulation,and field observation.Findings indicate that stress rotation is most pronounced at both ends of the coal seam goaf,with the maximum clockwise and counterclockwise rotation angles of 19°and-40°,respectively,observed in the bauxite layer.Inclined bauxite pillars are subjected to combined compressive and shear loading.Under such conditions,clockwise rotation of principal stress increases the shear-to-normal stress ratio,thereby reducing pillar stability.Pillars located beneath the coal wall are the first to fail due to stress concentration and principal stress rotation,which can trigger a cascade of instability among the adjacent pillars.The findings provide a theoretical basis and practical guidance for ensuring the safe co-mining of coal seams and bauxite resources.展开更多
In the practical slope engineering,the stability of lower sliding mass(region A)with back tensile cracks of the jointed rock slope attracts more attentions,but the upper rock mass(region B)may also be unstable.Therefo...In the practical slope engineering,the stability of lower sliding mass(region A)with back tensile cracks of the jointed rock slope attracts more attentions,but the upper rock mass(region B)may also be unstable.Therefore,in this study,based on the stepped failure mode of bedding jointed rock slopes,considering the influence of the upper rock mass on the lower stepped sliding mass,the improved failure model for analyzing the interaction force(F_(AB))between two regions is constructed,and the safety factors(F_(S))of two regions and whole region are derived.In addition,this paper proposes a method to determine the existence of F_(AB) using their respective acceleration values(a_(A) and a_(B))when regions A and B are unstable.The influences of key parameters on two regions and the whole region are analyzed.The results show that the variation of the F_(AB) and F_(S) of two regions can be obtained accurately based on the improved failure model.The accuracy of the improved failure model is verified by comparative analysis.The research results can explain the interaction mechanism of two regions and the natural phenomenon of slope failure caused by the development of cracks.展开更多
This study proposes an alternative calculation mode for stresses on the slip surface(SS).The calculation of the normal stress(NS)on the SS involves examining its composition and expanding its unknown using the Taylor ...This study proposes an alternative calculation mode for stresses on the slip surface(SS).The calculation of the normal stress(NS)on the SS involves examining its composition and expanding its unknown using the Taylor series.This expansion enables the reasonable construction of a function describing the NS on the SS.Additionally,by directly incorporating the nonlinear Generalized Hoke-Brown(GHB)strength criterion and utilizing the slope factor of safety(FOS)definition,a function of the shear stress on the SS is derived.This function considers the mutual feedback mechanism between the NS and strength parameters of the SS.The stress constraints conditions are then introduced at both ends of the SS based on the spatial stress relation of one point.Determining the slope FOS and stress solution for the SS involves considering the mechanical equilibrium conditions and the stress constraint conditions satisfied by the sliding body.The proposed approach successfully simulates the tension-shear stress zone near the slope top and provides an intuitive description of the concentration effect of compression-shear stress of the SS near the slope toe.Furthermore,compared to other methods,the present method demonstrates superior processing capabilities for the embedded nonlinear GHB strength criterion.展开更多
The sufficient conditions of stability for uncertain discrete-time systems with state delay have been proposed by some researchers in the past few years, yet these results may be conservative in application. The stabi...The sufficient conditions of stability for uncertain discrete-time systems with state delay have been proposed by some researchers in the past few years, yet these results may be conservative in application. The stability analysis of these systems is discussed, and the necessary and sufficient condition of stability is derived by method other than constructing Lyapunov function and solving Riccati inequality. The root locations of system characteristic polynomial, which is obtained by augmentation approach and Laplace expansion, determine the stability of uncertain discrete-time systems with state delay, the system is stable if and only if all roots lie within the unit circle. In order to analyze robust stability of system characteristic polynomial effectively, Kharitonov theorem and edge theorem are applied. Example shows the practicability of these methods.展开更多
The stability of room mining coal pillars during their secondary mining for recovering coal was analyzed. An analysis was performed for the damage and instability mechanism of coal pillars recovered by the caving mini...The stability of room mining coal pillars during their secondary mining for recovering coal was analyzed. An analysis was performed for the damage and instability mechanism of coal pillars recovered by the caving mining method. During the damage progression of a single room coal pillar, the shape of the stress distribution in the pillar transformed from the initial stable saddle shape to the final arch-shaped distribution of critical instability. By combining the shapes of stress distribution in the coal pillars with the ultimate strength theory, the safe-stress value of coal pillar was obtained as 11.8 MPa. The mechanism of instability of coal pillar groups recovered by the caving mining method was explained by the domino effect. Since the room coal pillars mined and recovered by the traditional caving mining method were significantly influenced by the secondary mining during recovery, the coal pillars would go through a chain-type instability failure. Because of this limitation, the method of solid backfilling was proposed for mining and recovering room coal pillars, thus changing the transfer mechanism of stress caused by the secondary mining(recovery) of coal pillars. The mechanical model of the stope in the case of backfilling and recovering room coal pillars was built. The peak stress values inside coal pillars varied with the variance of backfilling ratio when the working face was advanced by 150 m. Furthermore, when the critical backfilling ratio was 80.6%, the instability failure of coal pillars would not occur during the solid backfill mining process. By taking Bandingliang Coal Mine as an example, the coal pillars' stability of stope under this backfilling ratio was studied, and a project scheme was designed.展开更多
Based on the nonlinear Barton–Bandis(B–B)failure criterion,this study considers the system reliability of rock wedge stability under the pseudo-static seismic load.The failure probability(Pf)of the system is calcula...Based on the nonlinear Barton–Bandis(B–B)failure criterion,this study considers the system reliability of rock wedge stability under the pseudo-static seismic load.The failure probability(Pf)of the system is calculated based on the Monte−Carlo method when considering parameter correlation and variability.Parameter analysis and sensitivity analysis are carried out to explore the influence of parameters on reliability.The relationships among the failure probability,safety factor(Fs),and variation coefficient are explored,and then stability probability curves of the rock wedge under the pseudo-static seismic load are drawn.The results show that the parameter correlation of the B–B failure criterion has a significant influence on the failure probability,but correlation increases system reliability or decreases system reliability affected by other parameters.Under the pseudo-static seismic action,sliding on both planes is the main failure mode of wedge system.In addition,the parameters with relatively high sensitivity are two angles related to the joint dip.When the coefficient of variation is consistent,the probability of system failure is a function of the safety factor.展开更多
To alleviate the conservativeness of the stability criterion for Takagi-Sugeno （T-S） fuzzy time-delay systems, a new delay-dependent stability criterion was proposed by introducing a new augmented Lyapunov function ...To alleviate the conservativeness of the stability criterion for Takagi-Sugeno （T-S） fuzzy time-delay systems, a new delay-dependent stability criterion was proposed by introducing a new augmented Lyapunov function with an additional triple-integral term, which was firstly u3ed to derive the stability criterion for T-S fuzzy time-delay systems. By the same approach, the robust stability issue for fuzzy time-delay systems with uncertain parameters was also considered. On the other hand, in order to enhance the design flexibility, a new design approach for uncertain fuzzy time-delay systems under imperfect premise matching was also proposed, which allows the fuzzy controller to employ different membership functions from the fuzzy time-delay model. By the numerical examples, the proposed stability conditions are less conservative in the sense of getting larger allowable time-delay and obtaining smaller feedback control gains. For instance, when the allowable time-delay increases from 7.3 s to 12 s for an uncertain T-S fuzzy control system with time-delay, the norm of the feedback gains decreases from （34.299 2, 38.560 3） to （10.073 3, 11.349 0）, respectively. Meanwhile, the effectiveness of the proposed design method was illustrated by the last example with the robustly stable curves of system state under the initial condition of x（0） = [3 -1].展开更多
基金Supported by the Natural Science Foundation of Shanghai(23ZR1401700)National Natural Science Foundation of China(12471157)。
文摘In ecological environments,the survival environment of species is often inhomogeneous,and the reproductive process is affected by time delay.System with nonlocal effects and delay can more accurately simulate changes in population density.In this paper,we consider a reaction-diffusion-advection model with nonlocal delay and Dirichlet boundary conditions.First of all,we investigate the well-posedness of solution of model.Then,the existence of positive steady state is proofed by implicit function theorem.Based on a priori estimate for the eigenvalue,we prove the stability of the positive steady state and conclude the associated distribution of Hopf bifurcation.Our research indicates that the combined effects of nonlocal and time delays have a certain impact on the dynamics of the model.
基金Supported by National Natural Science Foundation of China(12201118)Guangdong Basic and Applied Basic Research Foundation(2023A1515010706)。
文摘We investigate a class of non-integrable two-particle Calogero-Moser systems modulated by a power-law external potential.The local well-posedness of the Cauchy problem is established under the strict initial separation condition for the particles.For suitably prepared initial configurations,local solutions can be extended globally via energy conservation;conversely,negative energy conditions induce(in)finite-time blowup.The linear(in)stability of stationary solutions is analyzed,with their energy serving as a threshold.Numerical investigations employ a fourth-order Runge-Kutta scheme with adaptive step-size control.Simulations demonstrate that the trajectories either converge to steady states or exhibit blowup,depending on the power exponent α and initial conditions.Increasingαaccelerates the convergence rate and dampens oscillatory dynamics,promoting a transition from periodic behavior to static equilibrium.
基金supported by the National Natural Science Foundation of China(Grant Nos.U2141254 and U23B6009)。
文摘In this paper,a high-fidelity computational fluid dynamics(CFD)and rigid body dynamics(RBD)coupled platform for virtual flight simulation is developed to investigate the flight stability of fixed canard dual-spin projectile.The platform's reliability is validated by reproducing the characteristic resonance instability of such projectiles.By coupling the solution of the Unsteady Reynolds-Averaged Navier-Stokes equations and the seven-degree-of-freedom RBD equations,the virtual flight simulations of fixed canard dual-spin projectiles at various curvature trajectories are achieved,and the dynamic mechanism of the trajectory following process is analyzed.The instability mechanism of the dynamic instability during trajectory following process of the fixed canard dual-spin projectile is elucidated by simulating the rolling/coning coupled forced motion,and subsequently validated through virtual flight simulations.The findings suggest that an appropriate yaw moment can drive the projectile axis to precession in the tangential direction of the trajectory,thereby enhancing the trajectory following stability.However,the damping of the projectile attains its minimum value when the forward body equilibrium rotational speed(-128 rad/s)is equal to the negative of the fast mode frequency of the projectile.Insufficient damping leads to the fixed canard dual-spin projectile exiting the dynamic stability domain during the trajectory following,resulting in weakly damped instability.Keeping the forward body not rotating or increasing the spin rates to-192 rad/s can enhance the projectile's damping,thereby improving its dynamic stability.
基金supported by the National Natural Science Foundation of China(Grant Nos.22105156,22175139,22171136,and 22302156)the China National Science Fund for Distinguished Young Scholars(Grant No.22325504)。
文摘The simultaneous integration of high energy density,low sensitivity,and thermal stability in energetic materials has constituted a century-long scientific challenge.Herein,we address this through a dualzwitterionic electronic delocalization strategy,yielding TYX-3,the first bis-inner salt triazolo-tetrazine framework combining these mutually exclusive properties.Uniformπ-electron distribution and elevated bond dissociation energy confer exceptional thermal stability(T_(d)=365℃)with TATB-level insensitivity(impact sensitivity IS>40 J,friction sensitivity FS>360 N).Engineeredπ-stacked networks enable record density(1.99 g·cm^(-3))with detonation performance surpassing HMX benchmarks(detonation velocity 9315 m·s^(-1),detonation pressure 36.6 GPa).Practical implementation in Poly(3-nitratomethyl-3-methyloxetane)(PNMMFO)solid propellants demonstrates 5.4-fold safety enhancement over conventional HMX-based formulations while maintaining equivalent specific impulse.This work establishes a new design paradigm for energetic materials,overcoming the historical trade-offs between molecular stability and energy output through rational zwitterionic engineering.
文摘The paper considers the methodology for a comprehensive analysis of the stability of an open pit-dump system,using limit equilibrium(LEM)and finite element(FEM)methods in the Russian CAE(computer-aided engineering)software Fidesys.It briefly highlights the issues of comparing limit equilibrium methods using the VNIMI(Research Institute of Geomechanics and Mine Surveying-Intersectoral Scientific Center"VNIMI")methodology and a specialized software product with numerical methods.The main focus of this study is to compare the results of the stability analysis in the volumetric model of the open pit-dump system using limit equilibrium and finite element methods in the CAE software Fidesys.It was found that,when modeling the combined operation of an open pit-dump system in complex terrain,both methods should be used,as each has its own advantages.The finite element method,for instance,has certain features that are not present in the calculations using the limit equilibrium approach.As a key scientific contribution,this paper introduces an automation program for calculating the stability of open-pit walls using the limit equilibrium method in CAE Fidesys,which was not previously integrated in the original software.The calculations performed with the use of this newly developed module were compared to those obtained from other widely used software solutions available on the market.The findings demonstrate a remarkable level of convergence in the calculation results for all relevant parameters,including the safety factor,localization,instability type,and deformation.The proposed approach i mproves the accuracy of calculati ons and ensures consistency between the higher stress design zones and the actual deformation and fracture patterns.It also enhances the ability to predict the behavior of rock mass when calculating stability parameters for facilities,both during operation and desi gn.
文摘Lithium-sulfur(Li-S)batteries have great promise for next-generation energy storage devices due to the high theoretical specific capacity(1675 mAh g^(-1))of sulfur with chemical conversion for charge storage.However,their practical use is hindered by the slow redox kinetics of sulfur and the“shuttle effect”arising from dissolved lithium polysulfides(LiPSs).In recent years,various carbon-based materials have served as sulfur hosts and catalysts for accelerating sulfur conversion redox kinetics and alleviating LiPS shuttling.However,they often suffer from irreversible passivation and structural changes that destroy their long-term performance.We consider the main problems limiting their stability,including excessive LiPS adsorption,passivation by insulating Li2S,and surface reconstruction,and clarify how these factors lead to capacity fade.We then outline effective strategies for achieving long-term sulfur catalysis,focusing on functional carbon,such as designing suitable carbon-supported catalyst interfaces,creating well-distributed active sites,adding cocatalysts to improve electron transfer,and using carbon-based protective layers to suppress unwanted side reactions.Using this information should enable the development of stable,high-activity catalysts capable of long-term operation under practical conditions in Li-S batteries.
文摘Thermal quenching(TQ)at elevated temperature is a major factor affecting the luminescent intensity and efficiency of phosphors.Improving the thermal stability of phosphors and weakening the TQ effect are of significance for the high-quality illumination of phosphor-converted WLEDs.Here,a novel red-emitting phosphor K_(2)Zn(PO_(3))_(4)∶Mn^(2+)is synthesized by standard high temperature solid state reaction in ambient atmosphere,which is a new member of self-reduction system.An effective synthesis strategy is proposed to optimize its photoluminescent performances.Combined with X-ray photoelectron spectroscopy and X-ray absorption fine structure spectroscopy,oxygen vacancy defects introduced by Mn doping are proved to play an important role in the transition of Mn^(4+)→Mn^(2+).Thermoluminescence analysis reveals that the distribution of trap levels,especially the deep ones,is effectively regulated by the controllable crystallization and significantly affect the thermal stability of phosphors.Then a defect-assisted model is proposed to address the inner mechanism of the phenomenon.The carriers trapped by deep trap levels can be released under the high-temperature stimulus,which return back to the luminescent centers and participate in the radiative recombination to improve thermal stability.This study provides a new crystallographic idea and theoretical support for obtaining luminescent materials with high thermal stability.
文摘To study the rolling motion of a ship in the presence of water on its deck,a linear-plus-quadratic damping term was incorporated into its equation of motion.Ship model tests indicates that the key dynamics of the physical system are preserved in the ship rolling equation with the linear-plus-quadratic type damping term.To take into account the presence of randomness in the excitation and the response,a new method was developed and a Melnikov criterion was obtained to provide an upper bound on the domain of the potential chaotic rolling motion(erratic rocking).Additionally,the Melnikov criterion proposed in this study was verified by the utilization of phase plane diagrams and Poincare maps.Furthermore,this research has made the initial endeavor to systematically modify the system parameters in the rolling equation of motion for ship stability analysis.
文摘Practical application of Na_(3)SbS_(4)(NSS)solid-state electrolyte in sodium metal batteries has been significantly hindered by poor interfacial stability and insufficient ionic conductivity.In this study,a series of dual-site doped Na_(3-2x)Sb_(1-x)W_(x)S_(4-x)F_(x)(x=0,0.12,0.24,0.36)electrolytes through high-energy ball milling followed by high-temperature sintering is prepared,where tungsten(W)substitutes for antimony(Sb)and fluorine(F)replaces sulfur(S)in the NSS lattice.The co-doping of W and F not only broadens the interplanar spacing of NSS but also promotes the stable formation of the cubic phase of NSS,thereby effectively enhancing the transport ability of sodium ions within NSS.Among them,Na_(2.52)Sb_(0.76)W_(0.24)S_(3.76)F_(0.24) exhibits the highest ionic conductivity of 4.45 mS·cm^(-1).Furthermore,F doping facilitates the in-situ formation of NaF between the electrolyte and metallic sodium,significantly improving interfacial stability.Electrochemical evaluation shows that the Na/Na_(2.52)Sb_(0.76)W_(0.24)S_(3.76)F_(0.24)/Na symmetric cell achieves a high critical current density of 1.65 mA·cm^(-2) and maintains stable sodium plating/stripping cycling for 500 h at 0.1 mA·cm^(-2).Additionally,the TiS2/Na_(2.52)Sb_(0.76)W_(0.24)S_(3.76)F_(0.24)/Na full cell exhibits outstanding cycling stability and rate capability.
文摘Alpha-aluminum hydride(α-AlH_(3))is usually metastable due to the small enthalpy of formation,poor stability,high chemical activity,sensitivity to moisture and easy combination with water in the air.In order to inhibit the hygroscopicity ofα-AlH_(3) and improve its storage and stability,paraffin wax(PW)is selected as the coating material,and the solvent/non-solvent method is usually used to coat the surface ofα-AlH_(3).The structure and topography ofα-AlH_(3) before and after being coated by PW were characterized by Fourier transform infrared spectroscopy(FT-IR),X-ray diffractometer(XRD),X-ray electron spectroscopy(XPS),elemental analysis,and scanning electron microscopy(SEM).The results show that PW can form a uniform and complete coating layer on the surface ofα-AlH_(3),and the crystal structure and morphology of theα-AlH_(3) coated by PW are not changed.The moisture absorption weight gain rate is reduced from 12%to 0.8%,and the hygroscopicity is greatly reduced.Furthermore,theα-AlH_(3) coated by PW also showed excellent performance in resisting water erosion after theα-AlH_(3) coated by PW,and the hydrophobic angle increases from 27°to 98°after theα-AlH_(3) surface being coated by PW.
基金Project(2021H0028) supported by the Natural Scienceof Fujian Province,ChinaProject(JAT200455) supported by the Fujian Provincial Young and Middle-aged Teacher Education Project,ChinaProject(fma2023003) supported by the Open Fund of Fujian Provincial Key Laboratory of Functional Materials and Applications,China。
文摘Rich-nickel layered ternary NCM811 has been widely used in the field of electric vehicles ascribed to its high theoretical specific capacity.However,poor cycling stability and rate-performance hindered its further development.Herein,different amounts of nitrogen-doped carbon were wrapped on the surface of NCM811 via a facile rheological phase method by regulating the amount of dopamine hydrochloride.The effects of the coating amounts on the structure and electrochemical performance are investigated.The DFT calculation,XRD,SEM and XPS reveal that an appropriate amount of nitrogen-doped carbon coating could uniformly form a protective layer on the NCM811 surface and the introduced N could anchor Ni atoms to inhibit the Li^(+)/Ni^(2+)mixing,but excessive amount would reduce Ni^(3+)to Ni^(2+)so as to conversely aggravate Li^(+)/Ni^(2+)mixing.Among the samples,the NCM811-CN0.75 sample exhibits the most excellent electrochemical performance,delivering a high-rate capacity of 151.6 mA·h/g at 10C,and long-term cyclability with 82.2%capacity retention after 300 cycles at 5C,exhibiting remarkable rate-performance and cyclability.
基金Projects(42177391,42477437)supported by the National Natural Science Foundation of ChinaProject(2024RC3041)supported by the Science and Technology Innovation Program of Hunan Province,China+1 种基金Project(2023CXQD064)supported by the Innovation-Driven Research Programme of Central South University,ChinaProject(242102321124)supported by the Henan Provincal Science and Technology Research Project,China。
文摘To accurately identify the factors affecting the formation of stable aggregates in bauxite residue during the soil formation process,the comprehensive effects of a combined chemical-biological amelioration strategy including solid wastes and a functional microorganism on aggregate size distribution and its stability in bauxite residue were investigated during a 365-d simulation experiment.The results showed that the combined amelioration effectively reduced the saline alkalinity of bauxite residue,and markedly changed the contents of aggregate-associated chemical binding agents.Desulfurization gypsum and maize straw-Penicillium oxalicum(P.oxalicum)differentiated the formation of aggregates within different sizes.Maize straw-P.oxalicum stimulated the formation of water-stable macroaggregates with more durable erosion resistance by the wet-sieving and laser dynamic diffraction analysis.The Pearson correlation analysis showed that exchangeable polyvalent metal ions,pyrophosphate extractable Fe oxide,and organic carbon exhibited positive correlations with aggregate stability during the 365-d incubation.The findings in this study may provide data support and engineering practical reference for ecological restoration in the disposal areas.
基金The TNAU Master’s student fellowship to the senior author。
文摘Background Hybrid cotton enjoys overwhelming patronage among cotton farmers because of its superior yield capacity and fiber quality.However,various environmental factors affect its yield and fiber quality.This study aimed to assess 30 cotton hybrids for the stability of four traits(single-plant seed cotton yield,fiber upper half mean length(UHML),fiber strength,and micronaire)across three environments.Recent techniques,including genotype and genotype×environment(GGE)biplot,which provides a visual representation of performance and adaptability;weighted average absolute scores of the best linear unbiased predictions(WAASB),which balances the performance of the trait with stability;and multi-trait stability index(MTSI),which integrates multi-trait performance and stability,were used to analyze the stability of the four traits.Results Analysis of variance revealed significant genotype and environment interactions for all the traits studied,highlighting the need for comprehensive stability analysis.The environment E2 was the most suitable for the evaluation of seed cotton yield,whereas E3 was suitable for the evaluation of UHML and fiber strength.A stable hybrid,H05(TVH002×MCU5),with superior performance for seed cotton yield and UHML,was identified based on the overall results from GGE and WAASB.The which-won-where bioplot showed that H25(SVPR3×MCU5)performed the best for seed cotton yield in E3,and H27(Suraj×Sunantha)in E2 and E1.The hybrid H04(TVH002×CO14)in E1 and H30(Suraj×MCU5)in E2 and E3 performed well for UHML.Similarly,H28(Suraj×Suraksha)for E2 and E3 and H26(Suraj×Subiksha)for E1 were the best performing in the case of fiber strength.Based on the MTSI,four promising hybrids,namely,H24(SVPR3×CO14),H09(TVH2010×CO14),H18(MCU7×Suraksha),and H29(Suraj×CO14),were identified as stable with average performance for all four traits.Conclusions The study identified a stable hybrid,H05(TVH002×MCU5),with superior performance for yield and UHML.The identified hybrids in this study hold significant potential for cultivation across Tamil Nadu,with a scope for further evaluation in diverse environments.
基金Project(2021YFC2902101)supported by the National Key Research and Development Program of ChinaProjects(42271139,52174135)supported by the National Natural Science Foundation of China。
文摘The“upper coal and lower bauxite”resource distribution pattern is widespread in China,where mining of the overlying coal seam significantly alters the stress environment of the underlying bauxite layer.This study investigates the stability of inclined bauxite pillars under the influence of stress redistribution caused by coal seam extraction.A theoretical model is developed to calculate the direction and magnitude of principal stresses in the inclined floor strata,and a pillar stability analysis model is established that considers the effect of principal stress rotation.The research employs a combination of theoretical analysis,physical modeling,numerical simulation,and field observation.Findings indicate that stress rotation is most pronounced at both ends of the coal seam goaf,with the maximum clockwise and counterclockwise rotation angles of 19°and-40°,respectively,observed in the bauxite layer.Inclined bauxite pillars are subjected to combined compressive and shear loading.Under such conditions,clockwise rotation of principal stress increases the shear-to-normal stress ratio,thereby reducing pillar stability.Pillars located beneath the coal wall are the first to fail due to stress concentration and principal stress rotation,which can trigger a cascade of instability among the adjacent pillars.The findings provide a theoretical basis and practical guidance for ensuring the safe co-mining of coal seams and bauxite resources.
基金Projects(52208369,52309138,52108320)supported by the National Natural Science Foundation of ChinaProjects(2023NSFSC0284,2025ZNSFSC0409)supported by the Sichuan Science and Technology Program,ChinaProject(U22468214)supported by the Joint Fund Project for Railway Basic Research by the National Natural Science Foundation of China and China State Railway Group Co.,Ltd.
文摘In the practical slope engineering,the stability of lower sliding mass(region A)with back tensile cracks of the jointed rock slope attracts more attentions,but the upper rock mass(region B)may also be unstable.Therefore,in this study,based on the stepped failure mode of bedding jointed rock slopes,considering the influence of the upper rock mass on the lower stepped sliding mass,the improved failure model for analyzing the interaction force(F_(AB))between two regions is constructed,and the safety factors(F_(S))of two regions and whole region are derived.In addition,this paper proposes a method to determine the existence of F_(AB) using their respective acceleration values(a_(A) and a_(B))when regions A and B are unstable.The influences of key parameters on two regions and the whole region are analyzed.The results show that the variation of the F_(AB) and F_(S) of two regions can be obtained accurately based on the improved failure model.The accuracy of the improved failure model is verified by comparative analysis.The research results can explain the interaction mechanism of two regions and the natural phenomenon of slope failure caused by the development of cracks.
基金Project(52278380)supported by the National Natural Science Foundation of ChinaProject(2023JJ30670)supported by the National Science Foundation of and Technology Major Project of Hunan Province,China。
文摘This study proposes an alternative calculation mode for stresses on the slip surface(SS).The calculation of the normal stress(NS)on the SS involves examining its composition and expanding its unknown using the Taylor series.This expansion enables the reasonable construction of a function describing the NS on the SS.Additionally,by directly incorporating the nonlinear Generalized Hoke-Brown(GHB)strength criterion and utilizing the slope factor of safety(FOS)definition,a function of the shear stress on the SS is derived.This function considers the mutual feedback mechanism between the NS and strength parameters of the SS.The stress constraints conditions are then introduced at both ends of the SS based on the spatial stress relation of one point.Determining the slope FOS and stress solution for the SS involves considering the mechanical equilibrium conditions and the stress constraint conditions satisfied by the sliding body.The proposed approach successfully simulates the tension-shear stress zone near the slope top and provides an intuitive description of the concentration effect of compression-shear stress of the SS near the slope toe.Furthermore,compared to other methods,the present method demonstrates superior processing capabilities for the embedded nonlinear GHB strength criterion.
基金This project was supported by National "863" High Technology Research and Development Program of China (2001-AA413130) and the National Key Research Project (2001-BA201A04).
文摘The sufficient conditions of stability for uncertain discrete-time systems with state delay have been proposed by some researchers in the past few years, yet these results may be conservative in application. The stability analysis of these systems is discussed, and the necessary and sufficient condition of stability is derived by method other than constructing Lyapunov function and solving Riccati inequality. The root locations of system characteristic polynomial, which is obtained by augmentation approach and Laplace expansion, determine the stability of uncertain discrete-time systems with state delay, the system is stable if and only if all roots lie within the unit circle. In order to analyze robust stability of system characteristic polynomial effectively, Kharitonov theorem and edge theorem are applied. Example shows the practicability of these methods.
基金Project(2014ZDPY02)supported by the Fundamental Research Funds for the Central Universities
文摘The stability of room mining coal pillars during their secondary mining for recovering coal was analyzed. An analysis was performed for the damage and instability mechanism of coal pillars recovered by the caving mining method. During the damage progression of a single room coal pillar, the shape of the stress distribution in the pillar transformed from the initial stable saddle shape to the final arch-shaped distribution of critical instability. By combining the shapes of stress distribution in the coal pillars with the ultimate strength theory, the safe-stress value of coal pillar was obtained as 11.8 MPa. The mechanism of instability of coal pillar groups recovered by the caving mining method was explained by the domino effect. Since the room coal pillars mined and recovered by the traditional caving mining method were significantly influenced by the secondary mining during recovery, the coal pillars would go through a chain-type instability failure. Because of this limitation, the method of solid backfilling was proposed for mining and recovering room coal pillars, thus changing the transfer mechanism of stress caused by the secondary mining(recovery) of coal pillars. The mechanical model of the stope in the case of backfilling and recovering room coal pillars was built. The peak stress values inside coal pillars varied with the variance of backfilling ratio when the working face was advanced by 150 m. Furthermore, when the critical backfilling ratio was 80.6%, the instability failure of coal pillars would not occur during the solid backfill mining process. By taking Bandingliang Coal Mine as an example, the coal pillars' stability of stope under this backfilling ratio was studied, and a project scheme was designed.
基金Project(51878668)supported by the National Natural Science Foundation of ChinaProjects(2017-122-058,2018-123-040)supported by the Guizhou Provincial Department of Transportation Foundation,ChinaProject([2018]2815)supported by the Guizhou Provincial Department of Science and Technology Foundation,China。
文摘Based on the nonlinear Barton–Bandis(B–B)failure criterion,this study considers the system reliability of rock wedge stability under the pseudo-static seismic load.The failure probability(Pf)of the system is calculated based on the Monte−Carlo method when considering parameter correlation and variability.Parameter analysis and sensitivity analysis are carried out to explore the influence of parameters on reliability.The relationships among the failure probability,safety factor(Fs),and variation coefficient are explored,and then stability probability curves of the rock wedge under the pseudo-static seismic load are drawn.The results show that the parameter correlation of the B–B failure criterion has a significant influence on the failure probability,but correlation increases system reliability or decreases system reliability affected by other parameters.Under the pseudo-static seismic action,sliding on both planes is the main failure mode of wedge system.In addition,the parameters with relatively high sensitivity are two angles related to the joint dip.When the coefficient of variation is consistent,the probability of system failure is a function of the safety factor.
基金Project(61273095)supported by the National Natural Science Foundation of ChinaProject(135225)supported by the Academy of Finland
文摘To alleviate the conservativeness of the stability criterion for Takagi-Sugeno （T-S） fuzzy time-delay systems, a new delay-dependent stability criterion was proposed by introducing a new augmented Lyapunov function with an additional triple-integral term, which was firstly u3ed to derive the stability criterion for T-S fuzzy time-delay systems. By the same approach, the robust stability issue for fuzzy time-delay systems with uncertain parameters was also considered. On the other hand, in order to enhance the design flexibility, a new design approach for uncertain fuzzy time-delay systems under imperfect premise matching was also proposed, which allows the fuzzy controller to employ different membership functions from the fuzzy time-delay model. By the numerical examples, the proposed stability conditions are less conservative in the sense of getting larger allowable time-delay and obtaining smaller feedback control gains. For instance, when the allowable time-delay increases from 7.3 s to 12 s for an uncertain T-S fuzzy control system with time-delay, the norm of the feedback gains decreases from （34.299 2, 38.560 3） to （10.073 3, 11.349 0）, respectively. Meanwhile, the effectiveness of the proposed design method was illustrated by the last example with the robustly stable curves of system state under the initial condition of x（0） = [3 -1].
