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
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
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 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
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
Ni-rich layered oxides are the preferred cathode materials for high-energy-density lithium-ion batteries currently used in electric vehicles.In this paper,we present a systematic first-principles evaluation of the dei...Ni-rich layered oxides are the preferred cathode materials for high-energy-density lithium-ion batteries currently used in electric vehicles.In this paper,we present a systematic first-principles evaluation of the deintercalation process in the Li1-xNiO2-ySy.The partial density of states(PDOS)characters of the electrons near the Fermi level,redox behaviors,and thermal stability have been investigated within the GGA+U scheme.The results show that the introduction of sulfur alleviates the lattice distortion during charging,suppresses nickel migration,and enhances the stability of oxygen according to the contribution of sulfur anion redox to the charge compensation for the overcharged Li1-xNiO2-ySy.This study provides a new insight on improving the stability of Ni-rich cathode materials by tuning of the electrochemical behaviors based on sulfur anion redox.展开更多
Delay-dependent robust stability of cellular neural networks with time-varying discrete and distributed time-varying delays is considered. Based on Lyapunov stability theory and the linear matrix inequality （LMIs） t...Delay-dependent robust stability of cellular neural networks with time-varying discrete and distributed time-varying delays is considered. Based on Lyapunov stability theory and the linear matrix inequality （LMIs） technique, delay-dependent stability criteria are derived in terms of LMIs avoiding bounding certain cross terms, which often leads to conservatism. The effectiveness of the proposed stability criteria and the improvement over the existing results are illustrated in the numerical examples.展开更多
Underground energy and resource development,deep underground energy storage and other projects involve the global stability of multiple interconnected cavern groups under internal and external dynamic disturbances.An ...Underground energy and resource development,deep underground energy storage and other projects involve the global stability of multiple interconnected cavern groups under internal and external dynamic disturbances.An evaluation method of the global stability coefficient of underground caverns based on static overload and dynamic overload was proposed.Firstly,the global failure criterion for caverns was defined based on its band connection of plastic-strain between multi-caverns.Then,overloading calculation of the boundary geostress and seismic intensity on the caverns model was carried out,and the critical unstable state of multi-caverns can be identified,if the plastic-strain band appeared between caverns during these overloading processes.Thus,the global stability coefficient for the multi-caverns under static loading and earthquake was obtained based on the corresponding overloading coefficient.Practical analysis for the Yingliangbao(YLB)hydraulic caverns indicated that this method can not only effectively obtain the global stability coefficient of caverns under static and dynamic earthquake conditions,but also identify the caverns’high-risk zone of local instability through localized plastic strain of surrounding rock.This study can provide some reference for the layout design and seismic optimization of underground cavern group.展开更多
The traditional stability analysis method of geogrid reinforced slopes does not consider the effect of lateral swelling,so it is not applicable to reinforced expansive soil slopes.This paper reports a new stability an...The traditional stability analysis method of geogrid reinforced slopes does not consider the effect of lateral swelling,so it is not applicable to reinforced expansive soil slopes.This paper reports a new stability analysis method for geogrid reinforced expansive soil slopes.The additional pullout force of the free zone due to the lateral swelling and the anti-pullout safety factor of each geogrid layer were obtained by ensuring the overall stability of the reinforced slope.The optimum design was carried out to treat an expansive soil cut slope in Hubei Province,China,by changing the spacing and length of geogrid reinforcement.Calculation results show that the additional pullout force caused by lateral swelling has a great influence on the anti-pullout stability of geogrids,and the local stability of the reinforced slope will be overestimated if the swelling effect of soil in the free zone is not considered.展开更多
To investigate the stability of rock mass in high geostress underground powerhouse caverns subjected to excavation,a microseismic(MS)monitoring system was established and the discrete element method(DEM)-based numeric...To investigate the stability of rock mass in high geostress underground powerhouse caverns subjected to excavation,a microseismic(MS)monitoring system was established and the discrete element method(DEM)-based numerical simulation was carried out.The tempo-spatial damage characteristics of rock mass were analyzed.The evolution laws of MS source parameters during the formation of a rock collapse controlled by high geostress and geological structure were investigated.Additionally,a three-dimensional DEM model of the underground powerhouse caverns was built to reveal the deformation characteristics of rock mass.The results indicated that the MS events induced by excavation of high geostress underground powerhouse caverns occurred frequently.The large-stake crown of the main powerhouse was the main damage area.Prior to the rock collapse,the MS event count and accumulated energy release increased rapidly,while the apparent stress sharply increased and then decreased.The amount and proportion of shear and mixed MS events remarkably increased.The maximum displacement was generally located near the spandrel areas.The MS monitoring data and numerical simulation were in good agreement,which can provide significant references for damage evaluation and disaster forecasting in high geostress underground powerhouse caverns.展开更多
To keep the tunnel face stable is very important for tunnel construction.In this paper,the tunnel face stability under the advanced pipe was analyzed using the Winkler foundation model and rigid limit equilibrium.The ...To keep the tunnel face stable is very important for tunnel construction.In this paper,the tunnel face stability under the advanced pipe was analyzed using the Winkler foundation model and rigid limit equilibrium.The tunnel face deformation characteristics were also analyzed using the numerical simulation.The influence of parameters on the deflection of the pipe roof and the stability of the tunnel face were discussed.The results show that the tunnel face stability can be improved through increasing the pipe diameter,decreasing the initial displacement at the beginning of the pipe seat,and adopting the short round length and small excavation height.With the increase of tunnel burial depth,the safety factor of tunnel face stability first decreases,then increases,and then remains unchanged.The deformation at the center of the tunnel face is larger than the deformation at the surround sides and at the corner.The horizontal displacement varies little with the increasing of the pipe length.The horizontal displacement at the center of the tunnel face increases with the increase of the pipe ring spacing and the pipe longitudinal spacing.There is an optimum external angle.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(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].
文摘Ni-rich layered oxides are the preferred cathode materials for high-energy-density lithium-ion batteries currently used in electric vehicles.In this paper,we present a systematic first-principles evaluation of the deintercalation process in the Li1-xNiO2-ySy.The partial density of states(PDOS)characters of the electrons near the Fermi level,redox behaviors,and thermal stability have been investigated within the GGA+U scheme.The results show that the introduction of sulfur alleviates the lattice distortion during charging,suppresses nickel migration,and enhances the stability of oxygen according to the contribution of sulfur anion redox to the charge compensation for the overcharged Li1-xNiO2-ySy.This study provides a new insight on improving the stability of Ni-rich cathode materials by tuning of the electrochemical behaviors based on sulfur anion redox.
文摘Delay-dependent robust stability of cellular neural networks with time-varying discrete and distributed time-varying delays is considered. Based on Lyapunov stability theory and the linear matrix inequality （LMIs） technique, delay-dependent stability criteria are derived in terms of LMIs avoiding bounding certain cross terms, which often leads to conservatism. The effectiveness of the proposed stability criteria and the improvement over the existing results are illustrated in the numerical examples.
基金Project(2023YFC2907204)supported by the National Key Research and Development Program of ChinaProject(52325905)supported by the National Natural Science Foundation of ChinaProject(DJ-HXGG-2023-16)supported by the Key Technology Research Projects of Power China。
文摘Underground energy and resource development,deep underground energy storage and other projects involve the global stability of multiple interconnected cavern groups under internal and external dynamic disturbances.An evaluation method of the global stability coefficient of underground caverns based on static overload and dynamic overload was proposed.Firstly,the global failure criterion for caverns was defined based on its band connection of plastic-strain between multi-caverns.Then,overloading calculation of the boundary geostress and seismic intensity on the caverns model was carried out,and the critical unstable state of multi-caverns can be identified,if the plastic-strain band appeared between caverns during these overloading processes.Thus,the global stability coefficient for the multi-caverns under static loading and earthquake was obtained based on the corresponding overloading coefficient.Practical analysis for the Yingliangbao(YLB)hydraulic caverns indicated that this method can not only effectively obtain the global stability coefficient of caverns under static and dynamic earthquake conditions,but also identify the caverns’high-risk zone of local instability through localized plastic strain of surrounding rock.This study can provide some reference for the layout design and seismic optimization of underground cavern group.
基金Project(51978085)supported by the National Natural Science Foundation of ChinaProject(201808430102)supported by the China Scholarship Council+1 种基金Project(JTG-201507)supported by the Highway Industry Standard Compilation Project of Ministry of Transportation,ChinaProject(kfj180102)supported by the Open Fund of Changsha University of Science&Technology,China。
文摘The traditional stability analysis method of geogrid reinforced slopes does not consider the effect of lateral swelling,so it is not applicable to reinforced expansive soil slopes.This paper reports a new stability analysis method for geogrid reinforced expansive soil slopes.The additional pullout force of the free zone due to the lateral swelling and the anti-pullout safety factor of each geogrid layer were obtained by ensuring the overall stability of the reinforced slope.The optimum design was carried out to treat an expansive soil cut slope in Hubei Province,China,by changing the spacing and length of geogrid reinforcement.Calculation results show that the additional pullout force caused by lateral swelling has a great influence on the anti-pullout stability of geogrids,and the local stability of the reinforced slope will be overestimated if the swelling effect of soil in the free zone is not considered.
基金Project(2017YFC1501100)supported by the National Key R&D Program of ChinaProjects(51809221,51679158)supported by the National Natural Science Foundation of China。
文摘To investigate the stability of rock mass in high geostress underground powerhouse caverns subjected to excavation,a microseismic(MS)monitoring system was established and the discrete element method(DEM)-based numerical simulation was carried out.The tempo-spatial damage characteristics of rock mass were analyzed.The evolution laws of MS source parameters during the formation of a rock collapse controlled by high geostress and geological structure were investigated.Additionally,a three-dimensional DEM model of the underground powerhouse caverns was built to reveal the deformation characteristics of rock mass.The results indicated that the MS events induced by excavation of high geostress underground powerhouse caverns occurred frequently.The large-stake crown of the main powerhouse was the main damage area.Prior to the rock collapse,the MS event count and accumulated energy release increased rapidly,while the apparent stress sharply increased and then decreased.The amount and proportion of shear and mixed MS events remarkably increased.The maximum displacement was generally located near the spandrel areas.The MS monitoring data and numerical simulation were in good agreement,which can provide significant references for damage evaluation and disaster forecasting in high geostress underground powerhouse caverns.
基金Project(20A187)supported by the Hunan Provincial Department of Education,ChinaProjects(51408216,51308209)supported by the National Natural Science Foundation of China。
文摘To keep the tunnel face stable is very important for tunnel construction.In this paper,the tunnel face stability under the advanced pipe was analyzed using the Winkler foundation model and rigid limit equilibrium.The tunnel face deformation characteristics were also analyzed using the numerical simulation.The influence of parameters on the deflection of the pipe roof and the stability of the tunnel face were discussed.The results show that the tunnel face stability can be improved through increasing the pipe diameter,decreasing the initial displacement at the beginning of the pipe seat,and adopting the short round length and small excavation height.With the increase of tunnel burial depth,the safety factor of tunnel face stability first decreases,then increases,and then remains unchanged.The deformation at the center of the tunnel face is larger than the deformation at the surround sides and at the corner.The horizontal displacement varies little with the increasing of the pipe length.The horizontal displacement at the center of the tunnel face increases with the increase of the pipe ring spacing and the pipe longitudinal spacing.There is an optimum external angle.
