noncoherent decorrelative detection for nonorthogonal multipulse modulation over the multiuser gaussian channel this paper introduces the problem of noncoherent detection for nonorthogonal multipulse modulation in the context of the synchronous multiuser gaussian channel each user sends an m ary information symbol by transmitting one of m possibly nonorthogonal waveforms furthermore the m signals of one user are allowed to be correlated with the signals of all other users a key idea proposed here is that of a noncoherent decorrelative receiver front end like its counterpart in single pulse modulation this front end eliminates multiuser interference it therefore reduces the multiuser detection problem into decoupled single user problems over equivalent noise enhanced single user channels each equivalent single user channel is rather general and can be described as one where the waveforms employed are not only correlated but are also of unequal energies several new results pertaining to the design and analysis of optimum and suboptimum noncoherent detectors for this single user channel are obtained in the multiuser channel these detectors constitute the post decorrelative processing units for each user

global attractivity of a positive periodic solution for a nonautonomous stage structured population dynamics with time delay and diffusion by employing the continuation theorem of coincidence degree theory the existence of a positive periodic solution for a nonautonomous stage structured population dynamics with time delay and diffusion is established further by constructing a lyapunov functional and using the result of the existence of positive periodic solution the attractivity of a positive periodic solution for above system is obtained

stability and bifurcation analysis of a stage structured predator prey model with time delay abstract in this paper we proposed and analyzed a prey predator system with stage structured for the predator population a time delay is incorporated due to the gestation for the matured predator all the possible non negative equilibria are obtained and their local as well as global behavior are studied choosing delay as a bifurcation parameter the existence of the hopf bifurcation of the system has been investigated moreover we use the normal form method and the center manifold theorem to examine the direction of the hopf bifurcation and the nature of the bifurcating periodic solution some numerical simulations are given to support the analytical results some interesting conclusions are obtained from our analysis and it is given at the end of the paper

global stability of a lotka volterra type predator prey model with stage structure and time delay a delayed lotka volterra type predator prey model with stage structure for predator is investigated it is assumed in the model that the individuals in the predator population may belong to one of two classes the immatures and the matures the age to maturity is presented by a time delay and that the immature predators do not have the ability to prey by analyzing characteristic equations and using an iterative technique a set of easily verifiable sufficient conditions are derived for the local and global stability of the nonnegative equilibria of the model numerical simulations are carried out to illustrate the validity of our results

asymptotic behaviors of competitive lotka volterra system with stage structure in this paper a two species competitive model with stage structure is presented and studied results on the global extinction and permanence are given which generalize the well known three theorems for the two species competitive system and moreover they confirm the negative effect of stage structure on the permanence of populations as well as estimate the degree of such effect conclusions in this paper suggest that for a competitive community stage structure is also one of the important reasons that cause permanence and extinction

global attractivity of nonautonomous stage structured population models with dispersal and harvest the nonautonomous stage structured single species dispersal model with harvesting of mature individuals in an n patch environment is considered in which the individual members of the population have a life history that takes them through two stages immature and mature by using the theory of monotone and concave operators to functional differential equations we establish conditions under which this population dynamical system admits a positive periodic solution which attracts all positive solutions

a delayed stage structured predator prey model with impulsive stocking on prey and continuous harvesting on predator abstract in this work we investigate a delayed stage structured holling ii predator prey model with impulsive stocking on prey and continuous harvesting on predator sufficient conditions of the global attractivity of predator extinction periodic solution and the permanence of the system are obtained these results show that the behavior of impulsive stocking on prey plays an important role for the permanence of the system we also prove that all solutions of the system are uniformly ultimately bounded our results provide reliable tactical basis for the biological resource management

on state dependent delay partial neutral functional integro differential equations in this paper the existence of mild solutions for a class of abstract neutral integro differential equations with state dependent delay is studied

periodic solutions of a nonautonomous predator prey system with stage structure and time delays a nonautonomous lotka volterra type predator prey model with stage structure and time delays is investigated it is assumed in the model that the individuals in each species may belong to one of two classes the immatures and the matures the age to maturity is presented by a time delay and that the immature predators do not feed on prey and do not have the ability to reproduce by some comparison arguments we first discuss the permanence of the model by using the continuation theorem of coincidence degree theory sufficient conditions are derived for the existence of positive periodic solutions to the model by means of a suitable lyapunov functional sufficient conditions are obtained for the uniqueness and global stability of the positive periodic solutions to the model

stability of nonlinear differential systems with state dependent delayed impulses we consider nonlinear differential systems with state dependent delayed impulses impulses which involve the delayed state of the system for which the delay is state dependent such systems arise naturally from a number of applications and the stability issue is complex due to the state dependence of the delay we establish general and applicable results for uniform stability uniform asymptotic stability and exponential stability of the systems by using the impulsive control theory and some comparison arguments we show how restrictions on the change rates of states and impulses should be imposed to achieve system s stability in comparison with general impulsive delay differential systems with state dependent delay in the nonlinearity or the differential systems with constant delays in our approach the boundedness of the state dependent delay is not required but derives from the stability result obtained examples are given to demonstrate the sharpness and applicability of our general results and the proposed approach

wavefronts and global stability in a time delayed population model with stage structure we formulate and study a one dimensional single species diffusive delay population model the time delay is the time taken from birth to maturity without diffusion the delay differential model extends the well known logistic differential equation by allowing delayed constant birth processes and instantaneous quadratically regulated death processes this delayed model is known to have simple global dynamics similar to that of the logistic equation through the use of a sub supersolution pair method we show that the diffusive delay model continues to generate simple global dynamics this has the important biological implication that quadratically regulated death processes dramatically simplify the growth dynamics we also consider the possibility of travelling wavefront solutions of the scalar equation for the mature population connecting the zero solution of that equation with the positive steady state our main finding here is that our fronts appear to be all monotone regardless of the size of the delay this is in sharp contrast to the frequently reported findings that delay causes a loss of monotonicity with the front developing a prominent hump in some other delay models

persistence and periodicity of a delayed ratio dependent predator prey model with stage structure and prey dispersal a delayed periodic ratio dependent predator prey model with prey dispersal and stage structure for predator is investigated it is assumed that immature individuals and mature individuals of the predator species are divided by a fixed age and that immature predators don t have the ability to attack prey and that predator species is confined to one of the patches while the prey species can disperse between two patches we first discuss the uniform persistence and impermanence of the model by using gaines and mawhin s continuation theorem of coincidence degree theory a set of easily verifiable sufficient conditions are derived for the existence of positive periodic solutions of the proposed model numerical simulations are presented to illustrate the feasibility of our main results

variational iteration method for solving a generalized pantograph equation the variational iteration method is applied to solve the generalized pantograph equation this technique provides a sequence of functions which converges to the exact solution of the problem and is based on the use of lagrange multipliers for identification of optimal value of a parameter in a functional employing this technique it is possible to find the exact solution or an approximate solution of the problem some examples are given to demonstrate the validity and applicability of the method and a comparison is made with existing results

existence of periodic solutions for delay differential equations with state dependent delay abstract in this paper we study the existence of periodic solutions of a delay differential equation with delay depending indirectly on the state a fixed point problem related to a poincare operator is constructed and solved using an ejective fixed point theorem

hopf bifurcation analysis for a ratio dependent predator prey system with two delays and stage structure for the predator the ratio dependent theory is favored by researchers since it is more suitable for describing the relationship between predator and its prey in this paper a ratio dependent predator prey system with holling type ii functional response two time delays and stage structure for the predator is investigated firstly by choosing the two time delays as the bifurcation parameter the sufficient conditions for the local stability and the existence of hopf bifurcation with respect to both delays are established furthermore based on the normal form method and center manifold theorem explicit formulas are derived to determine the direction of hopf bifurcation and stability of the bifurcating periodic solution finally numerical simulations are given to verify the theoretical analysis

minimal sets in monotone and concave skew product semiflows ii two dimensional systems of differential equations abstract recurrent nonautonomous two dimensional systems of differential equations of ordinary finite delay and reaction diffusion types given by cooperative and concave vector fields define monotone and concave skew product semiflows whose dynamics is analyzed in this paper a complete description of all the minimal sets in a very interesting dynamical situation is provided and some criteria to determine its possible existence and the area on which they lie are given suitable examples prove the optimality of the results

towards a general theory of action and time abstract a formalism for reasoning about actions is proposed that is based on a temporal logic it allows a much wider range of actions to be described than with previous approaches such as the situation calculus this formalism is then used to characterize the different types of events processes actions and properties that can be described in simple english sentences in addressing this problem we consider actions that involve non activity as well as actions that can only be defined in terms of the beliefs and intentions of the actors finally a framework for planning in a dynamic world with external events and multiple agents is suggested

stability and delays in a predator prey system abstract sufficient conditions for both local and global stability of the positive equilibrium in a predator prey system with time delays are obtained by constructing suitable lyapunov functionals a remark on the mistake by k n murty and m a s srinivas j math anal appl 158 1991 333 341 is also included

runge kutta methods for the multi pantograph delay equation this paper deals with the properties of the numeric solution of the multi pantograph equationu t email protected t email protected 1u q 1t email protected 2u q 2t email protected lu q lt u 0 u 0 where 0

a stage structured prey predator model with discrete time delay abstract a stage structured predator prey model stage structure on prey with gestation delay has been presented in this paper linear stability analysis reveals that certain thresholds on the rate at which juveniles becomes adults in terms of the predation rate and other system parameters a stability switch in the system due to variation of delay parameter has been observed so is the phenomena of hopf bifurcation and stable limit cycle the estimation of the length of delay to preserve stability has also been calculated numerical simulation with a hypothetical set of data has been done to support the analytical findings

generalized stokes parameters shift keying a new perspective on optimal detection over electrical and optical vector incoherent channels we consider block transmission over the incoherent channel whereby several symbols either launched consecutively in time or in parallel over several diversity paths are equally affected by common isotropic phase and additively corrupted by circularly gaussian additive noise our novel approach toward transmission over such a vector incoherent channel vic model is based on coherency matrix and generalized stokes parameters gsp descriptions of optimal detection inspired by classical optical polarization theory but further extended to the dual context of generic electrical as well as optical communication the four classical real valued parameters introduced into optics by stokes in 1853 to characterize the state of polarization of an optical beam extended to d sup 2 gsp underlie our new alternative novel description of maximum a posteriori maximum likelihood map ml optimal detection over the vic channel the modulation formats of polarization shift keying polsk differential phase shift keying and amplitude shift keying as well as recent and novel combinations thereof will all be seen to be equivalent to a new conceptual form of modulation called gsp shift keying several forms of the optimal map ml receiver for vector multienergy transmission are developed generalizing the classical scalar incoherent receiver and the known polsk receivers

commonsense reasoning about causality deriving behavior from structure abstract this paper presents a qualitative reasoning method for predicting the behavior of mechanisms characterized by continuous time varying parameters the structure of a mechanism is described in terms of a set of parameters and the constraints that hold among them essentially a qualitative differential equation the qualitative behavior description consists of a discrete set of time points at which the values of the parameters are described in terms of ordinal relations and directions of change the behavioral description or envisionment is derived by two sets of rules propagation rules which elaborate the description of the current time point and prediction rules which determine what is known about the next qualitatively distinct state of the mechanism a detailed example shows how the envisionment method can detect a previously unsuspected landmark point at which the system is in stable equilibrium

noncoherent sequence detection new noncoherent sequence detection algorithms for combined demodulation and decoding of coded linear modulations transmitted over additive white gaussian noise channels possibly affected by intersymbol interference are presented optimal sequence detection in the presence of a random rotation of the signal phase assumed to be constant during the entire transmission requires a receiver complexity exponentially increasing with the duration of the transmission based on proper approximations simple suboptimal detection schemes based on the viterbi algorithm are presented whose performance approaches that of coherent detection in a companion paper by colavolpe and raheli see ibid vol 47 no 9 p 1303 7 1999 noncoherent sequence detection is extended to continuous phase modulations in the proposed schemes the tradeoff between complexity and performance is simply controlled by a parameter referred to as implicit phase memory and the number of states of a trellis diagram besides being realizable these schemes have the convenient feature of allowing us to remove the constant phase assumption and encompass time varying phase models the proposed schemes compare favorably with other solutions previously proposed in the technical literature

dynamics in a periodic competitive model with stage structure in this paper we consider a time delayed periodic system which describes the competition among mature populations by appealing to theories of monotone dynamical systems periodic semiflows and uniform persistence we analyze the evolutionary behavior of the system and establish sufficient conditions for competitive coexistence and exclusion

permanence and stability of a stage structured predator prey model abstract a predator prey model with a stage structure for the predator which improves the assumption that each individual predator has the same ability to capture prey is proposed it is assumed that immature individuals and mature individuals of the predator are divided by a fixed age and that immature predators do not have the ability to attack prey we obtain conditions that determine the permanence of the populations and the extinction of the populations furthermore we establish necessary and sufficient conditions for the local stability of the positive equilibrium of the model by exploiting the monotonicity of one equation of the model we obtain conditions for the global attractivity of the positive equilibrium which allow for long delay as long as the predator birth rate is large or the death rate of immature predators is small by constructing liapunov functionals we also obtain conditions under which the positive equilibrium is globally stable when the delay is small

the existence of nonoscillatory solutions to a generalized nonautonomous delay logistic equation sufficient conditions for the existence of nonoscillatory solutions to the delay logistic equation x t r t x t 1 x g t k are obtained where 1

optimal harvesting policy for single population with stage structure it is the purpose of this paper to analyze the exploitation of the stage structured singleautonomous population model we analyze the harvesting population equation and obtain existence local and global geometric properties of nonnegative equilibria explicit expressions are obtained for the optimal harvesting effort the maximum sustainable yield and the corresponding population level

laguerre polynomial approach for solving linear delay difference equations this paper presents a numerical method for the approximate solution of mth order linear delay difference equations with variable coefficients under the mixed conditions in terms of laguerre polynomials the aim of this article is to present an efficient numerical procedure for solving mth order linear delay difference equations with variable coefficients our method depends mainly on a laguerre series expansion approach this method transforms linear delay difference equations and the given conditions into matrix equation which corresponds to a system of linear algebraic equation the reliability and efficiency of the proposed scheme are demonstrated by some numerical experiments and performed on the computer algebraic system maple

numerical solution of nonlinear delay differential equations of fractional order in reproducing kernel hilbert space in this paper approximate solutions to a class of fractional differential equations with delay are presented by using a semi analytical approach in hilbert function space further the uniqueness of the solution is proved in the space of real valued continuous functions as well as the existence of the solution is proved in hilbert function space we also prove convergence and perform an analysis error for the proposed approach sophisticated delay differential equations of fractional order are considered as test examples numerical results illustrate the efficiency of the proposed approach computationally

permanence of variable coefficients predator prey system with stage structure abstract we studied a finite delay predator prey model with stage structure for predator by analyzing right hand of function and the standard comparison theorem some new sufficient conditions are derived for the permanence of population and some biological explanations are made

differential equations with discrete state dependent delay uniqueness and well posedness in the space of continuous functions abstract partial differential equations with discrete concentrated state dependent delays in the space of continuous functions are investigated in general the corresponding initial value problem is not well posed so we find an additional assumption on the state dependent delay function to guarantee the well posedness for the constructed dynamical system we study the long time asymptotic behavior and prove the existence of a compact global attractor

the effect of state dependent delay and harvesting on a stage structured predator prey model we propose and analyze a stage structured predator prey model in which the time from birth to maturity is directly related to the number of individuals present individuals mature more quickly when there are fewer of them around the state dependent time delay is taken to be an increasing differentiable bounded function in this research we study the dynamics of our model analytically we present results on positivity and boundedness of all populations criteria for the existence of all equilibria and uniqueness of a positive equilibrium are given in order to observe the effect of state dependent maturation delay local stability analysis around all equilibria of the proposed model is discussed due to variation of maturation delay also global stability of trivial and the boundary equilibria is investigated using liapunov functional and lasalle invariant principle to investigate the effect of state dependent maturation delay and the harvesting effort of all species we carried out numerical simulations

a nonautonomous predator prey system with stage structure and double time delays in the present paper we study a nonautonomous predator prey model with stage structure and double time delays due to maturation time for both prey and predator we assume that the immature and mature individuals of each species are divided by a fixed age and the mature predator only attacks the immature prey based on some comparison arguments we discuss the permanence of the species by virtue of the continuation theorem of coincidence degree theory we prove the existence of positive periodic solution by means of constructing an appropriate lyapunov functional we obtain sufficient conditions for the uniqueness and the global stability of positive periodic solution two examples are given to illustrate the feasibility of our main results

numerical simulation for the space fractional diffusion equations abstract this paper presents a novel semi analytical algorithm based on the chebyshev collocation method for the solution of space fractional diffusion equations the original fractional equation is transformed into a system of ordinary differential equations odes by the chebyshev collocation method a new semi analytical method is then used to approximate the solution of the resulting system to emphasize the reliability of the new scheme a convergence analysis is presented it is shown that highly accurate solutions can be achieved with relatively few approximating terms and absolute errors are rapidly decrease as the number of approximating terms is increased by presenting some numerical examples we show that the proposed method is a powerful and reliable algorithm for solving space fractional diffusion equations and can be extended to solve another space fractional partial differential equations comparison with other methods in the literature demonstrates that the proposed method is both efficient and accurate

global stability of a stage structured predator prey model with prey dispersal a delayed lotka volterra type predator prey model with stage structure for predator and prey dispersal in two patch environments is investigated it is assumed that immature individuals and mature individuals of predator species are divided by a fixed age and that immature predators do not feed on prey and do not have the ability to reproduce on the other hand it is assumed that the prey species can disperse between one patch with a low level of food and without predation and one patch with a higher level of food but with predation by means of two different kinds of lyapunov functionals sufficient conditions are derived respectively for the global asymptotic stability of a positive equilibrium of the model by analyzing the characteristic equation criterion is established for the local stability of the positive equilibrium numerical simulations are presented to illustrate our main results

the local structure of image discontinuities in one dimension the detailed structure of intensities in the local neighborhood of an edge can often indicate the nature of the physical event givinig rise to that edge we argue that the limit as we approach arbitrarily close to either side of an edge of such image parameters as type of texture texture gradient color appropriate directional derivatives of intensity etc is a key aspect of this structure however the general problem of capturing this local structure is surprisingly complex thus we restrict ourselves in this paper to a relatively simple domain one dimensional cuts through idealized images modeled by piecewise smooth c1 functions corrupted by gaussian noise within this domain we define local structure to be the limit of the uncorrupted intensity and of its derivatives as we approach arbitrarily close to either side of a discontinuity we develop a technique that captures this local structure while simultaneously locating the discontinuities and demonstrate that these tasks are in fact inseparable the technique is an extension using estimation theory of the classical definition of discontinuity it handles in a consistent fashion both jump discontinuities in the function and jump discontinuities in its first derivative so called step edges are a special case of the former and roof edges of the latter it also integrates again in a consistent fashion information derived from a number of different neighborhood sizes

stability and traveling fronts in lotka volterra competition models with stage structure this paper is concerned with a delay differential equation model for the interaction between two species the adult members of which are in competition the competitive effects are of the lotka volterra kind and in the absence of competition it is assumed that each species evolves according to the predictions of a simple age structured model which reduces to a single equation for the total adult population for each of the two species the model incorporates a time delay which represents the time from birth to maturity of that species thus the time delays appear in the adult recruitment terms the dynamics of the model are determined and global stability results are established for each equilibrium the equilibria of the model involve the maturation delays the criteria for global convergence to each equilibrium are sharp and involve these delays a reaction diffusion extension of the model is also studied for the case when only the adult members of each species can diffuse we prove the existence of a

boundary layer phenomena for differential delay equations with state dependent time lags iii in this paper we begin a study of the differential delay equation varepsilon x t x t f x t r r r x t

the topology of boundaries abstract high level representations used in reasoning distinguish a special set of boundary locations at which function values can change abruptly and across which adjacent regions may not be connected standard models of space and time based on segmenting r n do not allow these possibilities because they have the wrong topological structure at boundaries this mismatch has made it difficult to develop formal mathematical models for high level reasoning algorithms this paper shows how to modify an r n model so as to have an appropriate topological structure it then illustrates how the new models support standard reasoning algorithms provide simple models for previously difficult situations and suggest interesting new analyses based on change or non change in scene topology

minimal sets in monotone and concave skew product semiflows i a general theory abstract the long term dynamics of a general monotone and concave skew product semiflow is analyzed paying special attention to the region delimited from below by the graph of a semicontinuous subequilibrium or by a minimal set admitting a flow extension different possibilities arise depending on the existence and number or absence of minimal sets strongly above the initially fixed one as well as on the coexistence or not of bounded and unbounded semiorbits on the region previous results are unified and extended and significative differences with the sublinear case are established some scenarios which are impossible in the autonomous or periodic cases may occur in this setting

permanence and periodicity of a delayed ratio dependent predator prey model with holling type functional response and stage structure a periodic and delayed ratio dependent predator prey system with holling type iii functional response and stage structure for both prey and predator is investigated it is assumed that immature predator and mature individuals of each species are divided by a fixed age and immature predator do not have the ability to attack prey sufficient conditions are derived for the permanence and existence of positive periodic solution of the model numerical simulations are presented to illustrate the feasibility of our main results

the dynamics of a mutual interference age structured predator prey model with time delay and impulsive perturbations on predators in this paper we introduce a mutual interference age structured predator prey natural enemy pest model with constant maturation time delay for the prey and then propose a pest management strategy by constant periodic releasing for the predator we show that there exists a global attractive pest eradication periodic solution when the periodic releasing amount m 1 and m 2 are lager than some critical value further to obtain a more effective pest control strategy we give the conditions involving the estimate of m 1 and m 2 in which the model is uniformly permanent and the pest population is under the economic threshold level we believe that the results will provide reliable tactic basis for the practical pest management

pattern formation in a predator prey diffusion model with stage structure for the predator in this paper we study a neumann boundary value problem in a d dimensional box t d 0 d d 1 2 3 for the predator prey diffusion model u 1 t d 1 u 1 u 1 a u 1 u 2 u 3 u 2 t d 2 u 2 d 4 u 2 u 3 2 k u 1 u 3 u 2 u 3 t d 3 u 3 b u 2 m u 3 with predator stage structure by using the bootstrap technique guo and hwang 2010 and higher order energy estimates we provide a rigorous quantitative characterization for the nonlinear evolution of early spatiotemporal pattern formation on the unstable positive constant equilibrium as a consequence the nonlinear instability occurs

noncoherent coded modulation trellis coded modulation with two or multidimensional signal constellations together with coherent maximum likelihood detection is considered an attractive solution for communications over the additive white gaussian noise awgn channel in this paper a new noncoherent communication system is introduced called noncoherent coded modulation ncm as an alternative to coherent coded modulation ncm achieves almost the same power efficiency without bandwidth expansion or an extensive increase in complexity as a noncoherent system the method does not need carrier phase estimation nonetheless differential encoding is not required high performance noncoherent detection is achieved by using multiple symbol observations unlike previous approaches a sliding window for the observations is used with each observation covering several branches of the trellis such that the observations are time overlapped we define a new type of noncoherent maximum likelihood sequence estimator mlse and analyze its performance over the awgn channel by numerical calculation of the union bound we perform a computerized search and present new codes for noncoherent detection with their performance the new codes cover many useful rates and complexities and achieve higher performance than existing codes for noncoherent detection the method can also be used for multiple symbol demodulation of mdpsk with better results than existing methods

hopf bifurcation of a predator prey system with stage structure and harvesting abstract in this paper a two species predator prey system with stage structure and harvesting is investigated the existence of hopf bifurcations of the system is given and the stability and directions of hopf bifurcations are determined by applying the normal form theory and the center manifold theorem

stability of a competition model with two stage structure a population model with stage structure which describes the competition of two species for space is considered the model is established under the assumptions that reproductive rates of two species are affected by competition and that the space occupied by one type of juveniles cannot be neglected estimates on the length of delays for which positive equilibrium of the model remains stable are given sufficient conditions are also derived that ensure global stability of positive equilibrium

bifurcation analysis in an approachable haematopoietic stem cells model a haematopoietic stem cells model hsc with one delay is considered at first we investigate the stability and existence of hopf bifurcations by analyzing the distribution of the roots of associated characteristic equation then an explicit formula for determining the stability and the direction of periodic solutions bifurcating from hopf bifurcations is derived using the normal form theory and center manifold argument finally some numerical simulations are carried out for supporting the analytic results

global hopf bifurcation for differential equations with state dependent delay abstract we develop a global hopf bifurcation theory for a system of functional differential equations with state dependent delay the theory is based on an application of the homotopy invariance of s 1 equivariant degree using the formal linearization of the system at a stationary state our results show that under a set of mild conditions the information about the characteristic equation of the formal linearization with frozen delay can be utilized to detect the local hopf bifurcation and to describe the global continuation of periodic solutions for such a system with state dependent delay

multilevel polarization shift keying optimum receiver structure and performance evaluation multilevel digital coherent optical modulation schemes based on the state of polarization of a fully polarized lightwave are proposed and analyzed based on the complete statistical characterization of the stokes parameters extracted through appropriate signal processing in the presence of shot and additive gaussian noise the optimum maximum likelihood receiver operating symbol by symbol is derived the exact performance in terms of the average symbol error probability is found optimum constellations for the case of equipower 4 8 16 and 32 signals are found on the basis of the minimization of the error probability for a given average power their performance turns out to be promising as compared to other standard modulation techniques the spectral analysis of polarization modulated signals is presented a new receiver structure which solves the problem of the excess penalties incurred in the presence of channel dichroism is proposed and analyzed

smoothness of semiflows for parabolic partial differential equations with state dependent delay in this paper the smoothness properties of semiflows on c1 solution submanifold of a parabolic partial differential equations with state dependent delay are investigated the problem is formulated as an abstract ordinary retarded functional differential equation of the form du t dt au t f ut with a continuously differentiable map g from an open subset u of the space c1 h 0 l2 where a is the infinitesimal generator of a compact c0 semigroup the present study is continuation of a previous work 14 that highlights the classical solutions and c1 smoothness of solution manifold here we further prove the continuous differentiability of the semiflow we finally verify all hypotheses by a biological example which describes a stage structured diffusive model where the delay which is the time taken from birth to maturity is assumed as a function of a immature species population

permanence of a predator prey system with stage structure and time delay abstract a stage structured predator prey system stage structure for both predator and prey with discrete time delay has been presented in this paper by analyzing the model and using the standard comparison theorem the sufficient conditions are derived for permanence of the system and non permanence of predators

global attractivity in concave or sublinear monotone infinite delay differential equations abstract we study the dynamical behavior of the trajectories defined by a recurrent family of monotone functional differential equations with infinite delay and concave or sublinear nonlinearities we analyze different sceneries which require the existence of a lower solution and of a bounded trajectory ordered in an appropriate way for which we prove the existence of a globally asymptotically stable minimal set given by a 1 cover of the base flow we apply these results to the description of the long term dynamics of a nonautonomous model representing a stage structured population growth without irreducibility assumptions on the coefficient matrices

role of constant prey refuge on stage structure predator prey model with ratio dependent functional response abstract a constant prey refuge has been incorporated in a stage structured predator prey model with ratio dependent functional response sufficient conditions are obtained for the uniform persistence and global asymptotic stability by constructing suitable lyapunov function our model analysis demonstrates that the constant prey refuge plays an important role on the coexistence of stage structured predator prey species

stability and hopf bifurcation analysis of an eco epidemic model with a stage structure abstract in this paper an eco epidemiological model with a stage structure is considered the asymptotical stability of the five equilibria the existence of stability switches about positive equilibrium is investigated it is found that hopf bifurcation occurs when the delay passes though a critical value some explicit formulae determining the stability and the direction of the hopf bifurcation periodic solutions bifurcating from hopf bifurcations are obtained by using the normal form theory and center manifold theory some numerical simulations for justifying the theoretical analysis are also provided finally biological explanations and main conclusions are given

analysis of a model representing stage structured population growth with state dependent time delay a stage structured model of population growth is proposed where the time to ma turity is itself state dependent it is shown that under appropriate assumptions all solutions are positive and bounded criteria for the existence of positive equilibria and further conditions for the uniqueness of the equilibria are given the stability of the equilibria are also discussed in addition an attracting region is determined for solutions such that this region collapses to the unique positive equilibrium in the state independent case

a computational approach to edge detection this paper describes a computational approach to edge detection the success of the approach depends on the definition of a comprehensive set of goals for the computation of edge points these goals must be precise enough to delimit the desired behavior of the detector while making minimal assumptions about the form of the solution we define detection and localization criteria for a class of edges and present mathematical forms for these criteria as functionals on the operator impulse response a third criterion is then added to ensure that the detector has only one response to a single edge we use the criteria in numerical optimization to derive detectors for several common image features including step edges on specializing the analysis to step edges we find that there is a natural uncertainty principle between detection and localization performance which are the two main goals with this principle we derive a single operator shape which is optimal at any scale the optimal detector has a simple approximate implementation in which edges are marked at maxima in gradient magnitude of a gaussian smoothed image we extend this simple detector using operators of several widths to cope with different signal to noise ratios in the image we present a general method called feature synthesis for the fine to coarse integration of information from operators at different scales finally we show that step edge detector performance improves considerably as the operator point spread function is extended along the edge

stage structured models of intra and inter specific competition within age classes abstract in some species larvae and adults experience competition in completely different ways simple stage structured models without larval competition usually yield a single delay equation for the adults using an age structured system incorporating competition among both larvae and adults we derive a system of distributed delay equations for the numbers of larvae and adults the system is neither cooperative nor reducible to a single equation for either variable positivity boundedness and uniform strong persistence are established linear stability analysis of equilibria is difficult due to the strong coupling but results are proved for small delays using monotone systems theory and exponential ordering for small delay we prove a theorem on generic convergence to equilibria which does not directly follow from standard theory but can be proved indirectly using comparison arguments finally we consider an extension to two strain competition and prove theorems on the linear stability of the boundary equilibria

global convergence of a reaction diffusion predator prey model with stage structure for the predator abstract a lotka volterra type reaction diffusion predator prey model with stage structure for the predator and time delay due to maturity is investigated by successively modifying the coupled lower upper solution pairs sufficient conditions independent of the effect of spatial diffusion are derived for the global convergence of positive solutions to the proposed problem

a taylor method for numerical solution of generalized pantograph equations with linear functional argument this paper is concerned with a generalization of a functional differential equation known as the pantograph equation which contains a linear functional argument in this paper we introduce a numerical method based on the taylor polynomials for the approximate solution of the pantograph equation with retarded case or advanced case the method is illustrated by studying the initial value problems the results obtained are compared by the known results

analysis of a periodic bacteria immunity model with delayed quorum sensing based on j zhang m cerasuolo p fergola z e ma on the influence of quorum sensing in the competition between bacteria and immune system in press a bacteria immunity model with periodically bacterial quorum sensing is formulated which describes the competition between bacteria and immune cells a discrete delay is introduced to characterize the time in which bacteria receive signal molecules and combat with immune cells in this paper we focus on a subsystem of the bacteria immunity model investigate the existence and stability of the positively periodic solution and discuss the existence of subharmonic bifurcation by the perturbation method

periodic solutions of a predator prey system with stage structures for predator and prey abstract by using the continuation theorem of coincidence degree theory the existence of a positive periodic solution for the predator prey system with stage structures for predator and prey is established

optimal control of harvest and bifurcation of a prey predator model with stage structure abstract this paper describes a prey predator model with stage structure for prey the adult prey and predator populations are harvested in the proposed system the dynamic behavior of the model system is discussed it is observed that singularity induced bifurcation phenomenon is appeared when variation of the economic interest of harvesting is taken into account state feedback controller is incorporated to stabilize the model system in case of positive economic interest harvesting of prey and predator population are used as controls to develop a dynamic framework to investigate the optimal utilization of the resource sustainability properties of the stock and the resource rent earned from the resource the pontryagin s maximum principle is used to characterize the optimal controls the optimality system is derived and then solved numerically using an iterative method with runge kutta fourth order scheme simulation results show that the optimal control scheme can achieve sustainable ecosystem

global stability and wavefronts in a cooperation model with state dependent time delay abstract this article deals with a diffusive cooperative model with state dependent delay which is assumed to be an increasing function of the population density with lower and upper bounds for the cooperative dde system the positivity and boundedness of solutions are firstly given using the comparison principle of the state dependent delay equations obtained the stability criterion of model is analyzed both from local and global points of view when the diffusion is properly introduced the existence of traveling waves is obtained by constructing a pair of upper lower solutions and schauder s fixed point theorem calculating the minimum wave speed shows that the wave is slowed down by the state dependent delay finally the traveling wavefront solutions for large wave speed are also discussed and the fronts appear to be all monotone regardless of the state dependent time delay this is an interesting property since many findings are frequently reported that delay causes a loss of monotonicity with the front developing a prominent hump in some other delay models

a lotka volterra type food chain model with stage structure and time delays abstract a three species lotka volterra type food chain model with stage structure and time delays is investigated it is assumed in the model that the individuals in each species may belong to one of two classes the immatures and the matures the age to maturity is presented by a time delay and that the immature predators immature top predators do not have the ability to feed on prey predator by using some comparison arguments we first discuss the permanence of the model by means of an iterative technique a set of easily verifiable sufficient conditions are established for the global attractivity of the nonnegative equilibria of the model

an approximate solution for a neutral functional differential equation with proportional delays in this paper a novel algorithm based on reproducing kernel theory for neutral functional differential equation with proportional delays is proposed the advantages of the presented method are the establishment of complete approximate solution theory and high precision of absolute error some examples are given to demonstrate the validity and applicability of the new method and some comparisons are made with the existing results

semigroup properties and the crandall liggett approximation for a class of differential equations with state dependent delays abstract we present an approach for the resolution of a class of differential equations with state dependent delays by the theory of strongly continuous nonlinear semigroups we show that this class determines a strongly continuous semigroup in a closed subset of c 0 1 we characterize the infinitesimal generator of this semigroup through its domain finally an approximation of the crandall liggett type for the semigroup is obtained in a dense subset of c as far as we know this approach is new in the context of state dependent delay equations while it is classical in the case of constant delay differential equations

hopf bifurcation and global stability for a delayed predator prey system with stage structure for predator abstract in this paper a delayed predator prey system with stage structure for predator is proposed and studied it is found that the time delay is harmless for permanence of the stage structured system if 1 we show that the unique positive equilibrium is locally asymptotically stable when time delay is sufficiently small while loss of stability by a hopf bifurcation can occur as the delay increases

multiple symbol differential detection of mpsk a differential detection technique for mpsk multiple phase shift keying which uses a multiple symbol observation interval is presented and its performance is analyzed and simulated the technique makes use of maximum likelihood sequence estimation of the transmitted phases rather than symbol by symbol detection as in the conventional differential detection thus the performance of this multiple symbol detection scheme fills the gap between conventional two symbol observation differentially coherent detection of mpsk and ideal coherent of mpsk with differential encoding the amount of improvement gained over conventional differential detection depends on the number of phases m and the number of additional symbol intervals added to the observation what is particularly interesting is that substantial performance improvement can be obtained for only one or two additional symbol intervals of observation the analysis and simulation results presented are for uncoded mpsk

stability and hopf bifurcation in a delayed ratio dependent holling tanner type model in this study a delayed ratio dependent holling tanner type predator prey model is investigated first the local stability of a positive equilibrium is studied and then the existence of hopf bifurcations is established by using the normal form theory and center manifold theorem the explicit algorithm determining the stability direction of the bifurcating periodic solutions are derived finally we perform the numerical simulations for justifying the theoretical results

extinction in periodic competitive stage structured lotka volterra model with the effects of toxic substances in this paper we consider a periodic competitive stage structured lotka volterra model with the effects of toxic substances it is shown that toxic substances play an important role in the extinction of species we obtain a set of sufficient conditions which guarantee that one of the components is driven to extinction while the other is globally attractive the numerical simulation of an example verifies our main results

some defects in finite difference edge finders this work illustrates and explains various artifacts in the output of five finite difference edge finders those of j f canny 1983 1986 r a boie et al 1986 and r a boie and i j cox 1987 and three variations on that of d marr and e c hildreth 1980 reimplemented with a common output format and method of noise suppression these artifacts include gaps in boundaries spurious boundaries and deformation of region shape

a predator prey system with stage structure for predator abstract this paper studies the asymptotoc behavior of a predator prey model with stage structure it is found that an orbitally asymptotically stable periodic orbit exists in that model when time delay due to gestation of predator and time delay from crowding effect of prey are incorporated we establish the condition for the permanence of populations and sufficient conditions under which positive equilibrium of the model is globally stable

persistence of some stage structured ecosystems with finite and infinite delay abstract the persistence of some stage structured predator prey model with finite and infinite delay was studied in this paper by analyzing right hand functions and using the comparison theorem some sufficient conditions for the persistence of populations with finite and infinite delay were derived

on abstract differential equations with state dependent non local conditions abstract in this paper we introduce the concept of state dependent nonlocal condition and study the existence and uniqueness of solution for a general class of abstract differential equations with state dependent delay subject to this class of conditions in this type of problem the nonlocal condition can be dependent on times or time intervals determined by the unknown solution some examples on partial differential equations with state dependent delay arising in population dynamics are presented

solving generalized pantograph equations by shifted orthonormal bernstein polynomials abstract in this paper we introduce shifted orthonormal bernstein polynomials sobps and derive the operational matrices of integration and delays for these polynomials then we apply them to convert the pantograph equations to a system of linear equations an important property of this method is that the condition number of the coefficient matrix of the system is small which confirms that our method is stable error analysis and comparison with other methods are given to confirm the validity efficiency and applicability of the proposed method

extinction and permanence in nonautonomous competitive system with stage structure in this paper the n species nonautonomous stage structured competitive system is constructed and considered sufficient conditions for its extinction and permanence are obtained results here generalize and unify some previous ones moreover it is concluded that stage structure in this system is one of the important factors that effect the extinction and permanence of species

periodic and almost periodic solution for a non autonomous epidemic predator prey system with time delay in this paper we studied a non autonomous predator prey system with discrete time delay where there is epidemic disease in the predator by using some techniques of the differential inequalities and delay differential inequalities we proved that the system is permanent under some appropriate conditions when all the coefficients of the system is periodic we obtained the existence and global attractivity of the positive periodic solution by mawhin s continuation theorem and constructing a suitable lyapunov functional furthermore when the coefficients of the system are not absolutely periodic but almost periodic sufficient conditions are also derived for the existence and asymptotic stability of the almost periodic solution

permanence and stability of a predator prey system with stage structure for predator a stage structured predator prey system with delays for prey and predator respectively is proposed and analyzed mathematical analysis of the model equations with regard to boundedness of solutions permanence and stability are analyzed some sufficient conditions which guarantee the permanence of the system and the global asymptotic stability of the boundary and positive equilibrium respectively are obtained

the asymptotic behavior of the strong solutions for a non autonomous non local pde model with delay abstract in this paper we study the asymptotic behavior of the strong solutions of a non autonomous non local pde model with time delay we present the existence and structure of the uniform attractor by constructing the skew product flow of the family of processes generated by the strong solutions in order to obtain the existence of the uniform attractor we prove the family of processes satisfies uniform condition c by using some special technique of phase space decomposition additionally it is shown that all the bounded complete trajectories are globally asymptotic stable under some assumptions as the application of our result we obtain a globally asymptotic stable nontrivial strong periodic solution of a non local pde model