Grassland-type ecosystem stability in China differs under the influence of drought and wet events

Ecological stability is a core issue in ecological research and holds significant implications forhumanity. The increased frequency and intensity of drought and wet climate events resulting from climatechange pose a major threat to global ecological stability. Variations in stability among different ecosystemshave been confirmed, but it remains unclear whether there are differences in stability within the sameterrestrial vegetation ecosystem under the influence of climate events in different directions and intensities.China's grassland ecosystem includes most grassland types and is a good choice for studying this issue.This study used the Standardized Precipitation Evapotranspiration Index-12 (SPEI-12) to identify thedirections and intensities of different types of climate events, and based on Normalized DifferenceVegetation Index (NDVI), calculated the resistance and resilience of different grassland types for 30consecutive years from 1990 to 2019 (resistance and resilience are important indicators to measurestability). Based on a traditional regression model, standardized methods were integrated to analyze theimpacts of the intensity and duration of drought and wet events on vegetation stability. The resultsshowed that meadow steppe exhibited the highest stability, while alpine steppe and desert steppe had thelowest overall stability. The stability of typical steppe, alpine meadow, temperate meadow was at anintermediate level. Regarding the impact of the duration and intensity of climate events on vegetationecosystem stability for the same grassland type, the resilience of desert steppe during drought was mainlyaffected by the duration. In contrast, the impact of intensity was not significant. However, alpine steppewas mainly affected by intensity in wet environments, and duration had no significant impact. Ourconclusions can provide decision support for the future grassland ecosystem governance.

POSITIVE EQUILIBRIUM AND ITS STABILITY OF THE BEDDINGTON-DEANGELIS'TYPE PREDATOR-PREY DYNAMICAL SYSTEM

A class of Beddington-DeAngelis＇ type predator-prey dynamic system with prey and predator both having linear density restriction is considered. By using the qualitative methods of ODE, the existence and uniqueness of positive equilibrium and its global asymptotic stability are analyzed. The direct criterions for local stability of positive equilibrium and existence of limit cycle are also established when inference parameter of predator is small.

Effects of rapid quenching on structure and cycle stability of La-Mg-Ni-Co type hydrogen storage alloy

In order to improve the cycle stability of La-Mg-Ni-Co type alloy electrode, rapid quenching technology was employed. The effects of rapid quenching on the microstructure and cycle stability of the alloy were investigated. The obtained results show that the La2Mg(Ni0.85Co0.15)9M0.1 (M=B, Cr) alloy electrodes are composed of (La, Mg)Ni3 phase, LaNi5 phase and a small amount of the LaNi2 phase. A trace of the Ni2B phase exists in the as-cast MB alloy, and the Ni2B phase in the alloy nearly disappears after rapid quenching. Rapid quenching technology can slightly improve the cycling life of the alloy. When the quenching rate increases from 0 m·s-1 (As-cast is defined as quenching rate of 0 m·s-1) to 30 m·s-1, the cycle lives of the MB, MCr alloys enhance from 86 and 87 cycles to 106 and 119 cycles, respectively. On the other hand, the average capacity decay rates of the MB, MCr alloys decrease from 1.7172 and 1.7178 mAh·g-1·cycle-1 to 1.5751 and 1.3060 mAh·g-1·cycle-1 after 86 charge-discharges cycling, respectively.

The Unconditional Stability for the Hyperneutral Type Constant Linear Control System with Delays (I)

By means of the frequency domain method and the inequality analysis, we discuss the unconditional stability problem for the hyperneutral type constant linear control system with delays, and obtain some precise sufficient, sufficient and necessary conditions.

On the partial stability of nonlinear impulsive Caputo fractional systems

In this work,stability with respect to part of the variables of nonlinear impulsive Caputo fractional differential equations is investigated.Some effective sufficient conditions of stability,uniform stability,asymptotic uniform stability and Mittag Leffler stability.The approach presented is based on the specially introduced piecewise continuous Lyapunov functions.Furthermore,some numerical examples are given to show the effectiveness of our obtained theoretical results.

A FIXED POINT APPROACH TO THE STABILITY OF A GENERALIZED APOLLONIUS TYPE QUADRATIC FUNCTIONAL EQUATION

Using the fixed point method, this article proves the Hyers-Ulam-Rassias stability of a generalized Apollonius type quadratic functional equation in Banach spaces. The conditions of these results are demonstrated by the quadratic functional equation of Apollonius type.

Global Asymptotic Stability and Hopf Bifurcation in a Homogeneous Diffusive Predator-Prey System with Holling Type II Functional Response

In this paper, we considered a homogeneous reaction-diffusion predator-prey system with Holling type II functional response subject to Neumann boundary conditions. Some new sufficient conditions were analytically established to ensure that this system has globally asymptotically stable equilibria and Hopf bifurcation surrounding interior equilibrium. In the analysis of Hopf bifurcation, based on the phenomenon of Turing instability and well-done conditions, the system undergoes a Hopf bifurcation and an example incorporating with numerical simulations to support the existence of Hopf bifurcation is presented. We also derived a useful algorithm for determining direction of Hopf bifurcation and stability of bifurcating periodic solutions correspond to j ≠0 and j = 0, respectively. Finally, all these theoretical results are expected to be useful in the future study of dynamical complexity of ecological environment.

Long-term and short-term stability characteristics of receiver inter system bias for BDS3/BDS2

The study of inter-system bias(ISB)is important for multi-system fusion and the performance of different signal compatibility.In this paper,the stability of ISB at the BDS3/BDS2 receiver end is calculated and analyzed for different time spans(DOY 060~090 in 2021)from a total of 31 MGEX and iGMAS stations.We adopted two estimation strategies,random walk and constant approach,using the precision products of orbit and clock bias provided by WUM,the influence of which on ISB was also analyzed.Our results showed that the ISB value varied little within a day,and the mean of daily ISB standard deviation was only 0.037 m when the observation condition was good.The signal reception was continuous,indicating a high ISB stability for one day.If extending the time series to one month,however,the ISB standard deviation calculated by constant approach,in which a constant ISB is estimated on a daily basis was about 0.1 m,and the results of adjacent days were not continuous,with no apparent pattern.Concerning the random walk approach,the obtained ISB time series also had a jump,and the conclusion was the same as that of the constant strategy.Besides,receiver types showed a strong regularity in ISB numerical situation,and the distribution of ISB values corresponding to the same receiver type was relatively close.Therefore,we conclude that the ISB parameters remain stable in the short term(one day)and less stable in the long-term period.It is recommended that the ISB term should be set as a constant estimate every day in BDS3/BDS2 solutions,regardless of receiver type consistency.

THE UNCONDITIONAL STABILITY FOR THE HYPERNEUTRAL TYPE CONSTANT LINEAR CONTROL SYSTEM WITH DELAYS

In this paper, by means of the frequency domain method and the inequality analysis, unconditional stability problem for the hyperneutral type constant linear control system with delays are discussed, and some precise sufficient, sufficient and necessary conditions are obtained.

The Unconditional Stability for the Multigroup Multidelays Neutral Type Linear Constant Control System

Applying the frequency domain method and the inequality method, we discussed the unconditional stability problem of the multigroup multidelays neutral type linear constant continuous control system, and obtained some sufficient conditions.

On Nonlinear Evolution of C-type Instability in Nonparallel Boundary Layers

The process of evolution, especially that of nonlinear evolution, of C-type instability of laminar-turbulent flow transition in nonparallel boundary layers are studied by means of a newly developed method called parabolic stability equations （PSE）. Initial conditions, which are very important for the nonlinear problem, are investigated by computing initial solution of the harmonic waves, modifying the mean-flow-distortion, and giving initial value of TS wave and its subharmonic waves at initial station by solving linear PSE. A numerical method with high-order accuracy are developed in the text, the key normalization conditions in the PSE are satisfied, and nonlinear PSE are solved efficiently and implemented stably by the spatial marching. It has been shown that the computed process of nonlinear evolution of C-type instability in Blasius boundary layer is in good agreement with the experimental results.

Total conductivity,oxygen permeability and stability of perovskite-type oxide BaCo_(0.7)Fe_(0.2)Nb_(0.1)O_(3-δ)

The total conductivity,oxygen sorption property,oxygen permeability and stability of pure perovskite-type oxide BaCo0.7Fe0.2Nb0.1O3-δ (BCFNO) in real operating conditions were investigated. Its total conductivity was measured to be 3.6 S·cm-1 at 600°C. Though the total conductivity of the BCFNO membrane is much smaller than that of the Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCFO) membrane,the oxygen permeability of the BCFNO membrane is similar to that of the BSCFO membrane. SEM observation and EDX analysis of the BCFN...

Stability of Schrdinger-Poisson type equations

Variational methods are used to study the nonlinear SchrSdinger-Poisson type equations which model the electromagnetic wave propagating in the plasma in physics. By analyzing the Hamiltonian property to construct a constrained variational problem, the existence of the ground state of the system is obtained. Furthermore, it is shown that the ground state is orbitally stable.

Structural Types of Sea Embankment and Their Stability Analysis

In this paper based on investigation on the structural types of sea embankments in the southeast coastal area of China, as well as the related tidal stages, waves and strength of marine soils, the finite element method (FEM) calculations for seepage flow stability, including the overall stability against sliding and local stability of sloping surface under the action of tidal stage and waves are carried out. A comparison of the computational results of FEM for single circular slip, composite circular slip and geogrid reinforcement against sliding shows that for calculation of stability against sliding of marine soft soil foundation it is even more reasonable to use the composite circular slip. The stability of sloping type sea embankment against sliding is slightly better than that of the vertical face type; for the combination of three defences (wave, scour and seepage defences) the sea embankment structural type of a composite cross section with a platform should be a good one, but it still should be suitable to local conditions. For the local stability of riprap slope blocks and wall face loose masonry blocks, according to the analyses of wave-induced seepage flow fields, calculating formulas are given and they are verified by model test on block stability of breakwaters.

The Sufficient and Necessary Condition of Lagrange Stability of Quasi-periodic Pendulum Type Equations

The quasi-periodic pendulum type equations are considered. A sufficient and necessary condition of Lagrange stability for this kind of equations is obtained. The result obtained answers a problem proposed by Moser under the quasi-periodic case.

NECESSARY AND SUFFICIENT CONDITIONS FOR THE ABSOLUTE STABILITY OF DISCRETE TYPE LURIE CONTROL SYSTEM

In this paper. it is discussed that the absohue stability for zero solution of thediscrete type Lurie control systmin which the nonlinear function f(σ) satisfying conditions as followsIt gives the necessary and sufficent conditions for the absolute stability forystem (I) under conditions (2).We also obtain the sufficient criteria for absolutesiability of the simplified system of (I) under conditions (3) .

Characterization and Stability of Na-doped p-type ZnO Thin Films Preparation by Reactive DC Magnetron Sputtering

Na-doped p-type ZnO thin films have been realized by DC reactive magnetron sputtering with a set of metal-Zn targets doped with various Na contents and under different substrate temperatures, respectively. Hall effect measurement, field-emission SEM, X-ray diffraction and optical transmission were carried out to investigate the effects of Na content and substrate temperature on the properties of p-type films. Results indicate that all the Na-doped ZnO films are strongly (002) oriented, and have an average transmittance ~85% in the visible region. Na-doped p-type ZnO films with good structural, electrical, and optical properties can only be obtained at an intermediate amount of Na content and under appropriate substrate temperature. At the optimal condition, the Na-doped p-type ZnO has the lowest resistivity of 13.8 Ω·cm with the carrier concentration as high as 1.07×1018 cm-3. The stability of the Na-doped p-type ZnO is also studied in this paper and it is found that the electrical properties keep stable in a period of one month.

Orthogonal Stability of Mixed Additive-Quadratic Jensen Type Functional Equation in Multi-Banach Spaces

In this paper, we prove the Hyers-Ulam stability of the following mixed additive-quadratic Jensen type functional equation:

Global asymptotic stability for Hopfield-type neural networks with diffusion effects

The existence, uniqueness and global asymptotic stability for the equilibrium of Hopfield-type neural networks with diffusion effects are studied. When the activation functions are monotonously nondecreasing, differentiable, and the interconnected matrix is related to the Lyapunov diagonal stable matrix, the sufficient conditions guaranteeing the existence of the equilibrium of the system are obtained by applying the topological degree theory. By means of constructing the suitable average Lyapunov functions, the global asymptotic stability of the equilibrium of the system is also investigated. It is shown that the equilibrium （if it exists） is globally asymptotically stable and this implies that the equilibrium of the system is unique.

NECESSARY AND SUFFICIENT CONDITIONS FOR THE ABSOLUTE STABILITY OF DISCRETE TYPE LURIE CONTROL SYSTEM

In this paper. it is discussed that the absolute for zero solution of the discrete type Lurie control systemin which the nonlinear function f(σ)satisfying conditions followsIt gives the necessary and sufficient conditions for the absolute stability for system (1) under conditions (2).We also obtain the sufficient for absolute stability of the simplified system of (1) under conditions (3) .