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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Mathematical programming 70 (1995), S. 73-89 
    ISSN: 1436-4646
    Schlagwort(e): Stochastic integer programming ; Parametric integer programming ; Continuity ; Stability ; Weak convergence of probability measures
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract For two-stage stochastic programs with integrality constraints in the second stage, we study continuity properties of the expected recourse as a function both of the first-stage policy and the integrating probability measure. Sufficient conditions for lower semicontinuity, continuity and Lipschitz continuity with respect to the first-stage policy are presented. Furthermore, joint continuity in the policy and the probability measure is established. This leads to conclusions on the stability of optimal values and optimal solutions to the two-stage stochastic program when subjecting the underlying probability measure to perturbations.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Mathematical programming 23 (1982), S. 181-192 
    ISSN: 1436-4646
    Schlagwort(e): Linear Complementarity Problem ; Stability ; Classes of Matrices
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract It has been shown previously that the Linear Complementarity Problem is stable when the defining matrix is positive semidefinite and when (locally) the set of solutions is nonempty and bounded. We enlarge the class of matrices for which this is true and also demonstrate how the boundedness condition leads to other stability type questions.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Mathematics of control, signals, and systems 8 (1995), S. 1-26 
    ISSN: 1435-568X
    Schlagwort(e): Extended Kalman filter ; Stability ; Discrete-time nonlinear systems ; Frequency tracking
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Mathematik , Technik allgemein
    Notizen: Abstract The error dynamics of the extended Kalman filter (EKF), employed as an observer for a general nonlinear, stochastic discrete time system, are analyzed. Sufficient conditions for the boundedness of the errors of the EKF are determined. An expression for the bound on the errors is given in terms of the size of the nonlinearities of the system and the error covariance matrices used in the design of the EKF. The results are applied to the design of a stable EKF frequency tracker for a signal with time-varying frequency.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Mathematics of control, signals, and systems 9 (1996), S. 95-106 
    ISSN: 1435-568X
    Schlagwort(e): Lyapunov functions ; Stability ; Stabilization ; Feedback ; Nonlinear systems
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Mathematik , Technik allgemein
    Notizen: Abstract This paper gives some new stability sufficient conditions. It presents an extension of the classical Lyapunov theory by considering Lyapunov functions which are nonnegative semidefinite instead of positive definite. Several examples are presented to illustrate the various theorems and an application to the feedback stabilization problem of a nonlinear control system is given.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Mathematics of control, signals, and systems 9 (1996), S. 123-151 
    ISSN: 1435-568X
    Schlagwort(e): Small time-delays ; Stability ; Robustness ; Partial differential equations ; Boundary control ; In-span control ; Transfer functions
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Mathematik , Technik allgemein
    Notizen: Abstract It has been observed that for many stable feedback systems, the introduction of arbitrarily small time-delays into the loop causes instability. In this paper we present a systematic treatment of this phenomenon for a large class of boundary control systems which allows for in-span control. Our approach is based on a combination of input-output methods and modal analysis. We give a number of sufficient conditions for robustness/nonrobustness of closed-loop input-output stability with respect to delays. Our framework includes a large class of ill-posed systems, i.e., systems whose open-loop transfer function is unbounded on any right half-plane. We then analyze the relationship between the poles of the transfer function and the exponential modes of the underlying boundary-value problem to derive internal stability properties from external ones.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Annals of operations research 56 (1995), S. 313-322 
    ISSN: 1572-9338
    Schlagwort(e): Stability ; multistage stochastic program ; multistage multifunction ; epi-convergence
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Notizen: Abstract In this paper, we study the stability of multistage stochastic programming with recourse in a way that is different from that used in studying stability of two-stage stochastic programs. Here, we transform the multistage programs into mathematical programs in the space ℝ n ×L p with a simple objective function and multistage stochastic constraints. By investigating the continuity of the multistage multifunction defined by the multistage stochastic constraints and applying epi-convergence theory we obtain stability results for linear and linear-quadratic multistage stochastic programs.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Neural computing & applications 4 (1996), S. 2-9 
    ISSN: 1433-3058
    Schlagwort(e): Adaptive decay ; Lyapunov functions ; Stability ; Weights
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract Dynamical properties of a general neural network are discussed. A condition for the neural activation dynamics being stable is derived. The stability condition does not put any symmetry restriction on the weights. The transitions from stable to non-stable dynamics are analysed and their analogy to phase transitions in statistical mechanics discussed. In general, the network dynamics can violate the stability condition. To avoid that happening, a method is introduced which makes the dynamics adaptive such that the stability condition is sustained. Relations to some previous works on stability are discussed.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Algorithmica 16 (1996), S. 151-160 
    ISSN: 1432-0541
    Schlagwort(e): Sorting ; Stability ; Data moves ; In-place
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract Until recently, it was not known whether it was possible to sortstably (i.e., keeping equal elements in their initial order) an array ofn elements using onlyO(n) data moves andO(1) extra space. In [13] an algorithm was given to perform this task inO(n 2) comparisons in the worst case. Here, we develop a new algorithm for the problem that performs onlyO(n 1+ε) comparisons (0〈ε〈1 is any fixed constant) in the worst case. This bound on the number of comparisons matches (asymptotically) the best known bound for the same problem with the stability constraint dropped.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Applied mathematics & optimization 31 (1995), S. 297-326 
    ISSN: 1432-0606
    Schlagwort(e): Sufficient optimality conditions ; Stability ; Sensitivity ; Sequential quadratic programming ; Penalty/multiplier methods ; 49K40 ; 49M30
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract Sufficient optimality conditions for infinite-dimensional optimization problems are derived in a setting that is applicable to optimal control with endpoint constraints and with equality and inequality constraints on the controls. These conditions involve controllability of the system dynamics, independence of the gradients of active control constraints, and a relatively weak coercivity assumption for the integral cost functional. Under these hypotheses, we show that the solution to an optimal control problem is Lipschitz stable relative to problem perturbations. As an application of this stability result, we establish convergence results for the sequential quadratic programming algorithm and for penalty and multiplier approximations applied to optimal control problems.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 16 (1982), S. 49-55 
    ISSN: 1432-1416
    Schlagwort(e): Stability ; Diffusion ; Parabolic equations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract Models for a single species that inhabits an environment that is spatially varying are presented. Simple necessary and sufficient conditions for stability, which are independent of the exact details of the dispersal process, are developed in the case of large diffusion rates. The results highlight the important stabilizing nature of diffusion in a spatially varying environment.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 11
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 9 (1980), S. 65-83 
    ISSN: 1432-1416
    Schlagwort(e): Nonnegative equilibria ; Stability ; Decompositions ; Sub-communities ; Structural perturbations ; Connective stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Summary The major objective of this paper is to propose a new decomposition-aggregation framework for stability analysis of Lotka-Volterra equations employing the concept of vector Liapunov functions. Both the disjoint and the overlapping decompositions are introduced to increase flexibility in constructing Liapunov functions for the overall system. Our second objective is to consider the Lotka-Volterra equations under structural perturbations, and derive conditions under which a positive equilibrium is connectively stable. Both objectives of this paper are directed towards a better understanding of the intricate interplay between stability and complexity in the context of robustness of model ecosystems represented by Lotka-Volterra equations. Only stability of equilibria in models with constant parameters is considered here. Nonequilibrium analysis of models with nonlinear time-varying parameters is the subject of a companion paper.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 12
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 11 (1981), S. 65-84 
    ISSN: 1432-1416
    Schlagwort(e): Population dynamics ; Age-dependent models ; Equilibrium solutions ; Stability ; Evolution equations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Summary A mathematical model describing the dynamics of a population consisting of several species is studied. The interactions in the population are assumed to be age-specific. Using an evolution equation approach, sufficient conditions for well-posedness in L 1 of the dynamics and for existence as well as for stability of equilibrium solutions are given.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 13
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 11 (1981), S. 95-103 
    ISSN: 1432-1416
    Schlagwort(e): Epidemiology ; SIRS ; Deterministic models ; Distributed delays ; Stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract A detailed analysis of a general class of SIRS epidemic models is given. Sufficient conditions are derived which guarantee the global stability of the endemic equilibrium solution. Further conditions are found which ensure instability for the equilibrium. Finally, the dependence of the stability on the contact number and the ratio of the mean length of infection to the mean removed time is considered.
    Materialart: Digitale Medien
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  • 14
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 14 (1982), S. 71-75 
    ISSN: 1432-1416
    Schlagwort(e): Epidemiology ; Two host models ; Stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract An epidemic model is derived for a two host infectious disease. It is shown that if a non-trivial equilibrium solution exists, it is globally stable. This result is also proved for a similar one host model.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 15
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 16 (1982), S. 33-48 
    ISSN: 1432-1416
    Schlagwort(e): Sterile insect release ; Predation ; Stability ; Limit cycles ; Optimal control
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract A model for the sterile insect release method of pest control in which the target species is under predatory or parasitic regulation is analyzed. The equations are nondimensionalized and the rescaled parameters are interpreted. There are four types of equilibria, whose existence and stability depend on which of ten regions of parameter space contain the rescaled parameters, and in turn give minimal release rates to achieve eradication of the pest. In at least one region, Hopf bifurcation theory shows the existence of limit cycles, but they are found to be unstable. In addition, the optimal release rate to minimize a total cost functional for pest control by the sterile release method is studied. Both approaches show that when predation accounts for a large fraction of the natural deaths, the necessary release rate and total cost are higher than for weak predation. If the predators are removed without being replaced by any other source of mortality, the cost rises in all cases but rises much more dramatically for cases with strong predation. A definite danger of the sterile release method when some predatory control exists is that the predators are frequently driven extinct before the prey, so that the target species could explode to much higher levels and be more difficult to eradicate again after the sterile release is terminated.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 16
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 17 (1983), S. 289-304 
    ISSN: 1432-1416
    Schlagwort(e): Endemicity ; Epidemics ; Genetics ; Deterministic models ; Stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract A discrete time genetics model is developed for populations that are undergoing selection due to infectious disease. It is assumed that the generation time of the host and infectious agent are non-synchronous and that only the host population is evolving. Two classes of epidemic processes are considered. The first class is for infectious agents that confer immunity following infection, while the second class is for those that do not confer immunity. The necessary and sufficient conditions are found in order for the disease to persist in a stable polymorphic host population. These conditions are shown to depend on the density of susceptibles, the selection coefficients, and the severity and class of the disease process.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 17
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 11 (1981), S. 1-14 
    ISSN: 1432-1416
    Schlagwort(e): Ecological modelling ; Predator-prey systems ; Ordinary non-linear differential equations ; Stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract We examine the qualitative effects of constant-rate stocking of either or both species in a predator-prey system. The hypotheses are made as mild as possible so that several types of systems with different qualitative alternatives may be studied.
    Materialart: Digitale Medien
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  • 18
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 12 (1982), S. 101-114 
    ISSN: 1432-1416
    Schlagwort(e): Predator-prey systems ; Harvesting ; Stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract The global behaviour of a class of predator-prey systems, modelled by a pair of non-linear ordinary differential equations, under constant rate harvesting and/or stocking of both species, is presented. Theoretically possible structures and transitions are developed and validated by computer simulations. The results are presented as transition loci in the F-G (prey harvest rate-predator harvest rate) plane.
    Materialart: Digitale Medien
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  • 19
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 14 (1982), S. 231-250 
    ISSN: 1432-1416
    Schlagwort(e): Predator-prey ; Age structure ; Stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract A general predator-prey model is considered in which the predator population is assumed to have an age structure which significantly affects its fecundity. The model equations are derived from the general McKendrick equations for age structured populations. The existence, stability and destabilization of equilibria are studied as they depend on the prey's natural carrying capacity and the maturation periodm of the predator. The main result of the paper is that for a broad class of maturation functions positive equilibria are either unstable for smallm or are destabilized asm decreases to zero. This is in contrast to the usual rule of thumb that increasing (not decreasing) delays in growth rate responses cause instabilities.
    Materialart: Digitale Medien
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  • 20
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 15 (1982), S. 37-50 
    ISSN: 1432-1416
    Schlagwort(e): Reaction-diffusion system ; Stationary solution ; Stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract We consider a spatial population growth process which is described by a reaction-diffusion equation c(x)u t = (a 2(x)u x ) x +f(u), c(x) 〉0, a(x) 〉 0, defined on an interval [0, 1] of the spatial variable x. First we study the stability of nonconstant stationary solutions of this equation under Neumann boundary conditions. It is shown that any nonconstant stationary solution (if it exists) is unstable if a xx⩽0 for all xε[0, 1], and conversely ifa xx〉0 for some xε[0, 1], there exists a stable nonconstant stationary solution. Next we study the stability of stationary solutions under Dirichlet boundary conditions. We consider two types of stationary solutions, i.e., a solution u 0(x) which satisfies u 0 x≠0 for all xε[0, 1] (type I) and a solution u 0(x) which satisfies u 0x = 0 at two or more points in [0, 1] (type II). It is shown that any stationary solution of type I [type II] is stable [unstable] if a xx ⩾0 [a xx ⩽0] for all xε[0, 1]. Conversely, there exists an unstable [a stable] stationary solution of type I [type II] if a xx 〈0 [a xx 〉0] for some xε[0, 1].
    Materialart: Digitale Medien
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  • 21
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 15 (1982), S. 239-247 
    ISSN: 1432-1416
    Schlagwort(e): Predator-prey model ; Behavioral adaptation ; Stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract The Volterra-Lotka predator-prey equations are modified so that the predator's ability to utilize the prey varies in proportion to the average number of encounters between the two species in the past. The behavior of this adaptive system is then described in terms of three parameters — the carrying capacity of the prey, the relative death rate of the predator, and the predator's memoryspan. The most stable situation is shown to occur when the carrying capacity of the prey is large, the predator's death rate is close to zero, and the predator is able to adapt quickly to changing levels of prey density.
    Materialart: Digitale Medien
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  • 22
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 17 (1983), S. 331-349 
    ISSN: 1432-1416
    Schlagwort(e): Stability ; Delay equations ; Stretch reflexes ; Mathematical studies
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract Human stretch reflexes (SRs) are often too weak and ineffectual to provide adequate postural regulation or rhythmic movement boosting (e.g. in ankle pushoff at the end of stance phase in fast running). Recent improvements in methods of artificially enhancing skeletomotor responses, especially in therapeutic regimens, should not be widely employed until the clonus-resisting stability properties of SRs are better understood. We formulate an idealized linear servo model of a segmentally-mediated SR system which includes the often ignored electromechanical coupling delay. For typical closed-loop (delay/gain) ratios, the model is shown to be unstable for all values of loop gain when operating as a position servo, but maximally stable when operating as a velocity servo. We claim that the velocity servo or one of its nonlinear relatives is a better model for some well studied SRs than, e.g., Houk's stiff muscle hypothesis. We also present evidence that even feeble and quickly saturating monosynaptic postural servos are always unstable if operated as pure position regulators.
    Materialart: Digitale Medien
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  • 23
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 18 (1983), S. 93-102 
    ISSN: 1432-1416
    Schlagwort(e): Stability ; Time delay ; Feasible equilibrium ; Partially feasible equilibrium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract A sufficient condition for the existence of a globally asymptotically stable equilibrium in Volterra models with continuous time delay is obtained, and some properties of the stable equilibrium are proven. Furthermore, some applications in which asymptotic stability only depends on the sign of the coefficients are considered.
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  • 24
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 38 (1999), S. 79-102 
    ISSN: 1432-1416
    Schlagwort(e): Key words: Aggregating populations ; Stability ; Convergence of solutions ; Mathematics Subject Classification (1991):92D25 ; 34A34
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract.  In this paper we introduce a spatially discrete model for aggregating populations described by a system of ODEs. We study the long time behavior of the solutions and we show that the model contains mechanisms by which individuals in the population aggregate at particular points in space.
    Materialart: Digitale Medien
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  • 25
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 10 (1980), S. 33-51 
    ISSN: 1432-1416
    Schlagwort(e): Plankton ; Stability ; Perturbations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract Linear perturbation theory is used to examine the stability of steady-state distributions of marine phytoplankton in the presence of a mean current with shear. Solutions are obtained for the general initial-value problem and it is found that all distributions are asymptotically stable so long as the rate of shear is greater than the local production. On the other hand, the early time behavior indicates that the system can be altered, if accomplished soon enough, depending upon a relative combination of diffusion, advection and production. Quantitative assessments are made where data are available.
    Materialart: Digitale Medien
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  • 26
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 10 (1980), S. 65-77 
    ISSN: 1432-1416
    Schlagwort(e): Predator-prey ; Persistence ; Stability ; Differential inequalities
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Summary The time derivatives of prey and predator populations are assumed to satisfy a set of inequalities, instead of a precise differential equation, reflecting an uncertain environmental and/or lack of knowledge by the modeler. A system of differential equations is found whose solution gives the boundary of a persistent set, which is positive flow invariant for any system satisfying the inequalities. Conditions are given for the persistent set to be bounded away from both axes, which show that resonance effects cannot drive either predator or prey to extinction if that does not happen for an autonomous system satisfying the inequalities. In general predator-prey systems are more persistent when there is strong asymptotic stability, when there is correlation between prey and predator dynamics, when the effect of perturbations is density dependent, and are more persistent under perturbations of the prey than of the predator.
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  • 27
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 10 (1980), S. 97-100 
    ISSN: 1432-1416
    Schlagwort(e): Reaction diffusion equations ; Wave-trains ; Stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Summary Stability of a class of solutions to reaction-diffusion equations is studied numerically. It is found that the solutions do not persist under a variety of boundary conditions.
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  • 28
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 13 (1981), S. 185-198 
    ISSN: 1432-1416
    Schlagwort(e): Epidemiology ; Deterministic models ; Distributed delays ; Thresholds ; Stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Summary A cyclic, constant parameter epidemiological model is described for a closed population divided into susceptible, exposed and infectious classes. Distributed delays are introduced and the model is formulated as two coupled Volterra integral equations. The delays do not change the general nature of thresholds or asymptotic stability; in all cases considered the disease either dies out, or approaches an endemic steady state.
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  • 29
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 16 (1982), S. 25-31 
    ISSN: 1432-1416
    Schlagwort(e): Stability ; Community matrix ; Lotka-Volterra models
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract The explicit function of the community matrix of a three dimensional Lotka-Volterra model is delineated by a set of necessary and sufficient conditions for a positive equilibrium to be asymptotically stable. In the special case that the community matrix is quasi weakly diagonally dominant, it is shown that a positive determinant for the community matrix is not only necessary but is also sufficient for stability. The results are specific to three dimensional models and do not extend to communities of dimension greater than three.
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  • 30
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 19 (1984), S. 147-156 
    ISSN: 1432-1416
    Schlagwort(e): Stability ; delay ; difference equations ; whale models
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract This paper relates the stability properties of a class of delay-difference equations to those of an associated scalar difference equation. Simple but powerful conditions for testing global stability are presented which are independent of the length of the time delay involved. For models which do not have globally stable equilibria, estimates of stability regions are obtained. Some well known baleen whale models are used to illustrate the results.
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  • 31
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 34 (1996), S. 675-688 
    ISSN: 1432-1416
    Schlagwort(e): Evolutionary game theory ; Replicator dynamics ; Bimatrix games ; Hamiltonian systems ; Volume-preserving flows ; Bipartite systems ; Stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract We review some properties of the evolutionary dynamics for asymmetric conflicts, give a simplified approach to them, and present some new results on the stability and bifurcations occurring in these conservative systems. In particular, we compare their dynamics to those of Hamiltonian systems
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 32
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 35 (1996), S. 1-19 
    ISSN: 1432-1416
    Schlagwort(e): Key words: Delay differential equations ; Stability ; Control
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract.  A mathematical model for the delivery of drug directly to the macrophages by using the phagocytosis of senescent red blood cells is proposed. The model is based on the following assumption: At time t=0 a preassigned red blood cell population n(0, a)=φ(a), a〉0, loaded by the drug, is injected in the blood circulation. Among the cells of that population only those with an age a≧ā (ā=120 days) will be phagocytosed by macrophages. Of course, the lifetime of the drug must be higher than ā. Within the red blood cells it cannot be metabolized, neither can it diffuse through their membranes. The emphasis of the paper is on the mathematical properties and on the formulation of the control problem.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 33
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 38 (1999), S. 241-261 
    ISSN: 1432-1416
    Schlagwort(e): Key words: Cell division ; Stability ; Gamma distribution ; Measure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract.  This paper couples a general d-dimensional (d arbitrary) model for the intracellular biochemistry of a generic cell with a probabilistic division hypothesis and examines the consequence of division for stability of cell function and structure. We show rather surprisingly that cell division is capable of giving rise to a stable population of cells with respect to function and structure even if, in the absence of cell division, the underlying biochemical dynamics are unstable. In the context of a simple example, our stability condition suggests that rapid cell proliferation plays a stabilizing role for cellular populations.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 34
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 38 (1999), S. 346-358 
    ISSN: 1432-1416
    Schlagwort(e): Key words: Nonlinear advective processes ; Traveling waves ; Stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract.  We establish the existence of traveling wave solutions for a nonlinear partial differential equation that models a logistically growing population whose movement is governed by an advective process. Conditions are presented for which traveling wave solutions exist and for which they are stable to small semi-finite domain perturbations. The wave is of mathematical interest because its behavior is determined by a singular differential equation and those with small speed of propagation steepen into a shock-like solutions. Finally, we indicate that the smoothing presence of diffusion allows wave persistence when an advective slow moving wave may collapse.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 35
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 9 (1980), S. 37-47 
    ISSN: 1432-1416
    Schlagwort(e): Epidemiology ; Endemic infectious diseases ; Deterministic models ; Thresholds ; Distributed delays ; Stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Summary Endemic infectious diseases for which infection confers permanent immunity are described by a system of nonlinear Volterra integral equations of convolution type. These constant-parameter models include vital dynamics (births and deaths), immunization and distributed infectious period. The models are shown to be well posed, the threshold criteria are determined and the asymptotic behavior is analysed. It is concluded that distributed delays do not change the thresholds and the asymptotic behaviors of the models.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 36
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 10 (1980), S. 401-415 
    ISSN: 1432-1416
    Schlagwort(e): Stability ; Volterra ecosystems ; Linear complementarity theory
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract In this paper, global asymptotic stability of ecosystems of the generalized Volterra type $$dx_i /dt = x_i \left( {b_{i - } \mathop \sum \limits_{j = 1}^n a_{ij} x_j } \right),{\text{ }}i = 1,...,n,$$ is investigated. We obtain the conditions for the existence of a nonnegative and stable equilibrium point of the system by applying a result of linear complementarity theory. The results of this paper show that there exists a class of systems that do not have multiple domains of attractions. This class is defined in terms of the species interactions alone, and does not involve carrying capacities or species net birth rates.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 37
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 11 (1981), S. 207-233 
    ISSN: 1432-1416
    Schlagwort(e): Clines ; Population genetics ; Nonlinear diffusion problems ; Stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract If a population, which consists of individuals having genetic variation at one locus, with two alleles A and a, evolves under the influence of migration and selection, gradients in the distribution of alleles may arise. We consider the effect of asymmetry in the migration and spatial dependence of the selection process, upon the emergence and stability of such gradients.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 38
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 16 (1982), S. 103-112 
    ISSN: 1432-1416
    Schlagwort(e): Bifurcation ; Competition ; Diffusive Lotka-Volterra system ; Predator-prey interaction ; Stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract Three examples of the diffusive 3-species Lotka-Volterra system with constant interaction parameters are given, and by bifurcation techniques shown to have stable spatially non-constant equilibrium solutions. One example is competitive; the second one predator-two-competing prey and the third involves two predators and a single prey.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 39
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 16 (1983), S. 199-220 
    ISSN: 1432-1416
    Schlagwort(e): Nonlinear integral operator ; Travelling wave ; Wave speed ; Asymptotic speed of propagation ; Stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract In this paper, we establish the existence and stability property of travelling wave solutions of a nonlinear integral operator in the inferior case.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 40
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 18 (1983), S. 213-221 
    ISSN: 1432-1416
    Schlagwort(e): Diffusive Lotka-Volterra system ; Hopf-bifurcation ; Spatiotemporal oscillation ; Stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract A stability condition for Hopf-bifurcating solutions from the uniform equilibrium of clasical Lotka-Volterra interaction-diffusion equations is presented. Using this condition, it is shown that stable spatio-temporal oscillations exist in the framework of such equations.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 41
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 34 (1996), S. 675-688 
    ISSN: 1432-1416
    Schlagwort(e): Key words: Evolutionary game theory ; Replicator dynamics ; Bimatrix games ; Hamiltonian systems ; Volume-preserving flows ; Bipartite systems ; Stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract.  We review some properties of the evolutionary dynamics for asymmetric conflicts, give a simplified approach to them, and present some new results on the stability and bifurcations occurring in these conservative systems. In particular, we compare their dynamics to those of Hamiltonian systems.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 42
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 35 (1997), S. 729-747 
    ISSN: 1432-1416
    Schlagwort(e): AMS(MOS) subject classifications: 76E30 ; 92D25 ; 58G18 ; 58E50 ; Key words: Waves of invasion ; Fronts ; Phase transition ; Lyapunov functional ; Stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract.  The paper addresses the question of asymptotic stability for front solutions corresponding to certain models of phase transition, invasions in population genetics, or nonlinear dynamics of perturbations of partial differential equations. The structure of front solutions for these equations is discussed, with emphasis on the relationship between the monotone front with minimum velocity and known front speed results. For a class of scalar reaction-diffusion equations, a Lyapunov functional in a travelling frame of reference is derived. Solutions which are minimal for the Lyapunov functional in certain directions of function space are stable for perturbations in those directions. The well-known minimal monotonic front solution turns out to be a minimum for the Lyapunov functional. A description of the class of perturbations to which this front is stable is derived.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 43
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 36 (1997), S. 71-94 
    ISSN: 1432-1416
    Schlagwort(e): Key words: Depletion ; Conservation ; Population ; Pollution ; Stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract.  In this paper, a mathematical model is proposed to study the depletion of resources in a forest habitat due to the increase of both population and pollution. It is shown that if the rate of pollutant emission into the environment is either population dependent, constant, or periodic, the equilibrium biomass density of the resource settles down to a lower equilibrium than its original carrying capacity, the magnitude of which decreases as the equilibrium levels of the density of population and the concentration of pollutant increase. However, in the case of an instantaneous spill of pollutant into the environment, the equilibrium biomass density decreases with the increase of the equilibrium density of population only. It is found that if the population density and the emission rate of pollutant increase without control, the forestry resource may become extinct. A conservation model is also proposed, the analysis of which shows that the resource biomass can be maintained at a desired level by conserving the forestry resource and by controlling the growth of population and the emission rate of pollutant in the habitat.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 44
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 35 (1997), S. 908-934 
    ISSN: 1432-1416
    Schlagwort(e): Key words: Size-structured populations ; Discontinuous reproduction ; Variable environment ; Periodic cohort solutions ; Stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract.  We consider a size-structured population model with discontinuous reproduction and feedback through the environmental variable ‘substrate’. The model admits solutions with finitely many cohorts and in that case the problem is described by a system of ODEs involving a bifurcation parameter β. Existence of nontrivial periodic n-cohort solutions is investigated. Moreover, we discuss the question whether n cohorts (n≧2) with small size differences will tend to a periodic one-cohort solution as t→∞.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 45
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 36 (1997), S. 149-168 
    ISSN: 1432-1416
    Schlagwort(e): Key words: Predator ; prey ; Functional response ; Bifurcation ; Stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract.  A predator–prey interaction model based on a system of differential equations with temperature-dependent parameters chosen appropriately for a mite interaction on apple trees is analyzed to determine how the type of functional response influences bifurcation and stability behavior. Instances of type I, II, III, and IV functional responses are considered, the last of which incorporates prey interference with predation. It is shown that the model systems with the type I, II, and III functional responses exhibit qualitatively similar bifurcation and stability behavior over the interval of definition of the temperature parameter. Similar behavior is found in the system with the type IV functional response at low levels of prey interference. Higher levels of interference are destabilizing, as illustrated by the prevalence of bistability and by the presence of three attractors for some values of the model parameters. All four systems are capable of modeling population oscillations and outbreaks.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 46
    Digitale Medien
    Digitale Medien
    Springer
    Mathematics of control, signals, and systems 8 (1995), S. 334-351 
    ISSN: 1435-568X
    Schlagwort(e): Time-varying systems ; Input-output maps ; Point evaluation ; Transmission zero ; Transient term ; Stability ; Frequency response function
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Mathematik , Technik allgemein
    Notizen: Abstract It is well known that the steady-state response of a linear, time-invariant, finite-dimensional, exponentially stable system to a periodic input signal results, after a phase shift, in a periodic output signal of the same period with amplitude equal to the rescaling of the input amplitude by the modulus of the value of the transfer function at the given frequency. Moreover, the phase shift of the output signal is equal to the phase of the value of the transfer function at the given frequency. For this reason the transfer function is also referred to as the “frequency response function.” We present an analogue of this idea for linear, finite-dimensional, time-varying systems, in both the continuous- and discrete-time settings. The problem of constructing a time-varying system which associates a given output signal to each complex exponential input signal in a prescribed set can be posed as a modeling question. This leads to a new modeling interpretation for some of the time-varying interpolation problems which have recently been studied in the literature and a new motivation for the study of point evaluation for triangular operators recently introduced by Alpay, Dewilde, and Dym and by the authors for the continuous-time case.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 47
    Digitale Medien
    Digitale Medien
    Springer
    Nonlinear dynamics 10 (1996), S. 89-103 
    ISSN: 1573-269X
    Schlagwort(e): Stability ; synchronization ; perturbed systems ; Lorenz attractor
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract We present necessary and sufficient conditions for the existence of synchronization in a class of continuous-time nonlinear systems: the so-called ω-affine systems. We apply the results to the Lorenz attractor. The robustness of the synchronization against parameter value variations is discussed using the Lyapunov stability theory for perturbed systems. We obtain sufficient conditions that guarantee a bounded steady-state error. This technique gives conservative results; however, in some systems like that of Lorenz, it provides definitive results about the existence of the synchronization. Furthermore, we give estimates of the maximal error as a function of the difference between the parameter values of the systems to be synchronized.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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