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

most probable dynamics of the tumor growth model with immune surveillance under cross correlated noises abstract the noise is inherent and indispensable in the tumor growth system therefore the behavior of the tumor system will display randomness different from the traditional analysis method such as the mean value variance etc the literature presents another deterministic tool i e the most probable trajectories which are defined by computing the spatial maximizers of the probability density function here we will investigate the tumor cell growth system with immune surveillance under correlated white noises from a deterministic point of view then the most probable extinction time is defined by the time when the most probable trajectories first escape to the extinction state from the tumor state afterward the probability ratio of extinction state versus tumor state characterizes treatment effects from the numerical simulation we derive that for the increasing cross correlation intensity of noises the most probable extinction time is enhanced and the therapeutic effect is weaken and conversely for the intensity of multiplicative noise in contrast there exists a critical intensity of additive noise at which the most probable extinction time is the smallest meanwhile treatment effects would be improved with the shrinking intensity of additive noise

euclidean reconstruction from contour matches this paper presents a method that recovers an euclidean structure from contour matching results if three or more views are available structure reconstruction without camera calibration is possible this is the first attempt at structure reconstruction from contour matches though there are works on structure reconstruction from point matches we also propose a new method that integrates more than one reconstructed 3d structure whose coordinates are represented by different camera projection matrices so that the structures are uniformly represented by the projection matrix of the first camera

permanence and positive periodic solution for the single species nonautonomous delay diffusive models abstract single species nonautonomous delay diffusion models with nonlinear growth rates are investigated some sufficient conditions are determined that guarantee the permanence of the species and the existence of a positive periodic solution which is global attractively

nonautonomous impulsive systems with unbounded nonlinear terms in fenner and pinto 1999 23 proved that if the linear impulsive system satisfies the is condition see definition 2 1 with bounded nonlinear term f t x then the perturbed nonlinear impulsive system has a unique bounded solution see theorem a the method used to prove theorem a cannot be applied to the unbounded case in this paper we prove that if f t x e t m then the perturbed nonlinear impulsive system has a unique solution

on bendixson s criterion abstract for autonomous differential equations in r n criteria are developed which preclude the existence of invariant closed curves such as periodic or homoclinic trajectories the technique is based on the study of functionals on 2 surfaces results generalize to higher dimensions a criterion of bendixson for the nonexistence of nonconstant periodic solutions in the case n 2 as an example an application to the lorenz system in r 3 is given

a deterministic and stochastic model for the system dynamics of tumor immune responses to chemotherapy abstract modern medical studies show that chemotherapy can help most cancer patients especially for those diagnosed early to stabilize their disease conditions from months to years which means the population of tumor cells remained nearly unchanged in quite a long time after fighting against immune system and drugs in order to better understand the dynamics of tumor immune responses under chemotherapy deterministic and stochastic differential equation models are constructed to characterize the dynamical change of tumor cells and immune cells in this paper the basic dynamical properties such as boundedness existence and stability of equilibrium points are investigated in the deterministic model extended stochastic models include stochastic differential equations sdes model and continuous time markov chain ctmc model which accounts for the variability in cellular reproduction growth and death interspecific competitions and immune response to chemotherapy the ctmc model is harnessed to estimate the extinction probability of tumor cells numerical simulations are performed which confirms the obtained theoretical results

modeling the dynamics of stage structure predator prey system with monod haldane type response function a stage structure predator prey model is proposed and analyzed in this paper in which predators are divided into juvenile and mature predators using monod haldane type response function the dynamical behavior of this system both analytically and numerically is investigated from the view point of stability and bifurcation we investigate global stability around the interior equilibrium point e by constructing suitable lyapunov function our model simulation indicates that the conversion of prey population to juvenile predators can destabilize the model system which lead to limit cycle oscillations we also investigate that the rate of juvenile predators becoming mature predators play an important role to destabilize the model system for the stable coexistence of both the populations we carried out extensive numerical simulations of the model to confirm the analytical findings

dynamics of predator prey system with fading memory abstract a predator prey model with fading memory for general holling type functional response is proposed the fading memory term is used with the hypothesis that the predator s growth rate at present depends on the recent past quantities of prey the effects of predator harvesting is also considered in the model the model is analysed theoretically as well as numerically two parameter bifurcation analysis are done and the existence of hopf point bifurcation is identified both supercritical and subcritical hopf bifurcations are obtained with the variation of system parameters maximum sustainable yield with respect to harvesting effort is also determined it is to be observed that the system dynamics is very rich in presence of fading memory the obtained results may be useful in the field of agriculture and fishery

synchronization transitions on scale free neuronal networks due to finite information transmission delays we investigate front propagation and synchronization transitions in dependence on the information transmission delay and coupling strength over scale free neuronal networks with different average degrees and scaling exponents as the underlying model of neuronal dynamics we use the efficient rulkov map with additive noise we show that increasing the coupling strength enhances synchronization monotonously whereas delay plays a more subtle role in particular we found that depending on the inherent oscillation frequency of individual neurons regions of irregular and regular propagating excitatory fronts appear intermittently as the delay increases these delay induced synchronization transitions manifest as well expressed minima in the measure for spatial synchrony appearing at every multiple of the oscillation frequency larger coupling strengths or average degrees can broaden the region of regular propagating fronts by a given information transmission delay and further improve synchronization these results are robust against variations in system size intensity of additive noise and the scaling exponent of the underlying scale free topology we argue that fine tuned information transmission delays are vital for assuring optimally synchronized excitatory fronts on complex neuronal networks and indeed they should be seen as important as the coupling strength or the overall density of interneuronal connections we finally discuss some biological implications of the presented results

structure from motion using line correspondences a theory is presented for the computation of three dimensional motion and structure from dynamic imagery using only line correspondences the traditional approach of corresponding microfeatures interesting points highlights corners high curvature points etc is reviewed and its shortcomings are discussed then a theory is presented that describes a closed form solution to the motion and structure determination problem from line correspondences in three views the theory is compared with previous ones that are based on nonlinear equations and iterative methods

spatiotemporal motion boundary detection and motion boundary velocity estimation for tracking moving objects with a moving camera a level sets pdes approach with concurrent camera motion compensation the purpose of this study is to investigate a method of tracking moving objects with a moving camera this method estimates simultaneously the motion induced by camera movement the problem is formulated as a bayesian motion based partitioning problem in the spatiotemporal domain of the image sequence an energy functional is derived from the bayesian formulation the euler lagrange descent equations determine simultaneously an estimate of the image motion field induced by camera motion and an estimate of the spatiotemporal motion boundary surface the euler lagrange equation corresponding to the surface is expressed as a level set partial differential equation for topology independence and numerically stable implementation the method can be initialized simply and can track multiple objects with nonsimultaneous motions velocities on motion boundaries can be estimated from geometrical properties of the motion boundary several examples of experimental verification are given using synthetic and real image sequences

can fractional calculus help improve tumor growth models abstract ode based population models remain viable tools to investigate tumor growth and support clinical evidence by following a fractional approach this study derives analytical solutions for five of these models whose parameters are best fitted against extant clinical data in terms of tumor growth prediction results show that fractional models not only have better performance which is mostly wanted for decision making in oncology but also reveal interesting characteristics to be further explored

periodic oscillations in age structured ratio dependent predator prey model with michaelis menten type functional response abstract a novel michaelis menten type ratio dependent predator prey model with predator age structure is investigated the predator fertility function is considered to be the piecewise function related to predator maturation period our methods rely upon integrated semigroup theory and hopf bifurcation theory for semilinear equations with non dense domain by local analysis and bifurcation analysis of the model a non trivial periodic oscillation phenomenon through hopf bifurcation appears when parameter passes through some critical values numerical simulations and sensitivity analysis on several important parameters are also performed to illustrate the conclusions

an investigation on monod haldane immune response based tumor effector interleukin 2 interactions with treatments abstract in this article a mathematical model with time delay describing tumor immune interaction with monod haldane kinetic response is proposed to reveal the dynamics of related inter cellular phenomena positivity of the solutions boundedness and uniform persistence of the system are determined to ensure the well posedness of the system the local stability of equilibria is studied as well as the length of the delay to preserve the stability is estimated for providing the mechanism of action to control the oscillation in tumor growth transcritical bifurcation using sotomayer s theorem and hopf bifurcation are investigated analytically and numerically global stability is examined before the commencement of sustained oscillations using a suitable lyapunov function to observe the influence of tumor growth due to uncertainty in input parameters latin hypercube sampling based uncertainty analysis is performed followed by sensitivity analysis computer simulation results are illustrated to elucidate the change of dynamical behavior due to the change of system parameters

hopf bifurcations in 3d competitive system with mixing exponential and rational growth rates abstract this paper investigates a three dimensional mixing competitive system with one exponential growth rate and two rational growth rates whose nullclines are linearly determined in total 33 stable nullcline classes exist hopf bifurcations are studied in classes 26 31 we provide examples to prove the existence of at least two limit cycles in each of the classes 27 31

uniqueness and estimation of three dimensional motion parameters of rigid objects with curved surfaces two main results are established in this paper first we show that seven point correspondences are sufficient to uniquely determine from two perspective views the three dimensional motion parameters within a scale factor for the translations of a rigid object with curved surfaces the seven points should not be traversed by two planes with one plane containing the origin nor by a cone containing the origin second a set of essential parameters are introduced which uniquely determine the motion parameters up to a scale factor for the translations and can be estimated by solving a set of linear equations which are derived from the correspondences of eight image points the actual motion parameters can subsequently be determined by computing the singular value decomposition svd of a 3 3 matrix containing the essential parameters

on the autocorrelation of finite length sequences lt is well known that all autocorrelation sequences are positive semi definite the correlation sequence is further constrained when as is often the case it is obtained from correlating a finite length data sequence with itself in this paper we study the effect of the data sequence length on the attainable correlations we derive a formula for the sequence length needed to match an autocorrelation value at a given lag the formula indicates that inordinately long sequences are needed to obtain a normalized autocorrelation coefficient near unity we conclude that all zero moving average models may be ill suited for highly correlated signals the formula for the single lag case is then used to obtain a bound on the sequence length needed to match a set of autocorrelations simultaneously

a stochastic sis epidemic model incorporating media coverage in a two patch setting in this paper we investigate the stochastic disease dynamics of an sis epidemic model on two patches incorporating media coverage we give the global existence and positivity of the solutions and the sufficient conditions for almost surely exponentially stability of the disease free equilibrium which means that the disease will be stochastic extinction furthermore we perform some numerical simulations to validate the analytical finding

estimation of motion from sequential images using integral constraints abstract a novel method for estimating nonuniform motion from sequential images is presented which is based on integral brightness constancy constraints the equations which transform arbitrary integrals between sequential images are expressed as a function of the displacement field and intensity changes the apparent displacement field is then computed by iterative projections onto the solution space of each linearized transformation equation some properties of this technique are demonstrated on a synthetic image pair realistic motion estimation is also demonstrated using sequential tagged cine magnetic resonance images

the combined effects of optimal control in cancer remission we investigate a mathematical model depicting the nonlinear dynamics of immunogenic tumors as envisioned by kuznetsov et al 1 to understand the dynamics under what circumstances the cancer cells can be eliminated we implement the theory of optimal control we design two types of external treatment strategies one is adoptive cellular immunotherapy and another is interleukin 2 our aim is to establish the treatment regimens that maximize the effector cell count and minimize the tumor cell burden and the deleterious effects of the total amount of drugs we derive the existence of an optimal control by using the boundedness of solutions we characterize the optimality system in which the state system is coupled with co states the uniqueness of an optimal control of our problem is also analyzed finally we demonstrate the numerical illustrations that the optimal regimens reduce the tumor burden under different scenarios

on the dynamics of predator prey models with the beddington deangelis functional response abstract the dynamics of predator prey models with the beddington deangelis functional response are analyzed primarily from the viewpoint of permanence uniform persistence the beddington deangelis functional response is similar to the holling type 2 functional response but contains an extra term describing mutual interference by predators both spatially homogeneous models based on ordinary differential equations and reaction diffusion models are considered criteria for permanence and for predator extinction are derived for systems without diffusion or with no flux boundary conditions criteria are derived for the existence of a globally stable coexistence equilibrium or alternatively for the existence of periodic orbits

a robust technique for matching two uncalibrated images through the recovery of the unknown epipolar geometry abstract this paper proposes a robust approach to image matching by exploiting the only available geometric constraint namely the epipolar constraint the images are uncalibrated namely the motion between them and the camera parameters are not known thus the images can be taken by different cameras or a single camera at different time instants if we make an exhaustive search for the epipolar geometry the complexity is prohibitively high the idea underlying our approach is to use classical techniques correlation and relaxation methods in our particular implementation to find an initial set of matches and then use a robust technique the least median of squares lmeds to discard false matches in this set the epipolar geometry can then be accurately estimated using a meaningful image criterion more matches are eventually found as in stereo matching by using the recovered epipolar geometry a large number of experiments have been carried out and very good results have been obtained regarding the relaxation technique we define a new measure of matching support which allows a higher tolerance to deformation with respect to rigid transformations in the image plane and a smaller contribution for distant matches than for nearby ones a new strategy for updating matches is developed which only selects those matches having both high matching support and low matching ambiguity the update strategy is different from the classical winner take all which is easily stuck at a local minimum and also from loser take nothing which is usually very slow the proposed algorithm has been widely tested and works remarkably well in a scene with many repetitive patterns

a highly robust estimator through partially likelihood function modeling and its application in computer vision the authors present a highly robust estimator known as the model fitting mf estimator for general regression they explain that high robustness becomes possible through partially but completely modeling the unknown log likelihood function the partial modeling takes place by taking the bayesian statistical decision rule and a number of important heuristics into consideration while maximizing the log likelihood function applications include the automatic selection of multiple thresholds single rigid motion estimation or multiple rigid motion segmentation and estimation from two perspective views it is believed that the proposed mf estimator will aid in solving many robust estimation problems that demand an estimator that is either highly robust or capable of handling contaminated gaussian mixture models

mathematical modeling of tumor immune competitive system considering the role of time delay abstract in this paper we consider a three dimensional nonlinear delay differential system tumor cells cytotoxic t lymphocytes t helper cells with single interaction delay we perform linear stability of the equilibria and the existence of hopf bifurcation in which the discrete time delay is used as a bifurcation parameter we estimate the length of delay to preserve the stability of period 1 limit cycle we also investigate the direction period and the stability of bifurcated periodic solutions by applying normal form method and center manifold theory we observe that the discrete time delay plays an important role in stability switching numerical simulations are presented to illustrate the rich dynamical behavior of the model with different values for the time delay including the existence of periodic oscillations which demonstrate the phenomena of long term tumor relapse

minimal wave speed for a class of non cooperative reaction diffusion systems of three equations abstract in this paper we study the traveling wave solutions and minimal wave speed for a class of non cooperative reaction diffusion systems consisting of three equations based on the eigenvalues a pair of upper lower solutions connecting only the invasion free equilibrium are constructed and the schauder s fixed point theorem is applied to show the existence of traveling semi fronts for an auxiliary system then the existence of traveling semi fronts of original system is obtained by limit arguments the traveling semi fronts are proved to connect another equilibrium if natural birth and death rates are not considered and to be persistent if these rates are incorporated then non existence of bounded traveling semi fronts is obtained by two sided laplace transform then the above results are applied to some disease transmission models and a predator prey model

on matching correlation sequences by parametric spectral models the correlation matching property of all pole models does not extend readily to pole zero models it is proved that if the number of poles in a pole zero model is strictly less than the number of given correlations a pole zero model that matches the given correlations may not exist irrespective of the number of zeros in the model it is also shown that if one adds a set of cepstral constraints a maximum entropy pole zero model that matches the correlation and cepstral constraints may not exist it is concluded that pole zero modeling minimizing some error criterion might be preferable to exact constraint matching

detecting and controlling unstable periodic orbits that are not part of a chaotic attractor a method for controlling unstable periodic orbits upos that have not been controllable before is presented the method is based on detecting upos that are situated outside the skeleton of a chaotic attractor the main idea is to exploit flexible parts of the attractor which under weak external perturbations allow variable excursions of the trajectory away from its originally determined path after the perturbation the trajectory of the autonomous system seeks its path back to the chaotic attractor and reveals additional upos that are otherwise not used by the system it is shown that these upos can be controlled as easily as the upos that form the basic chaotic attractor the effectiveness of the proposed method is demonstrated on two different chaotic systems with very distinct response abilities to external perturbations additionally some applications of the method in the fields of laser technology information encoding and biomedical engineering are discussed

stability and bifurcation analysis of delay induced tumor immune interaction model a modified mathematical model of kuznetsov et al 1994 representing tumor immune interaction with discrete time delay is proposed in this paper by choosing the discrete time delay as the bifurcation parameter we establish the sufficient condition for local stability of interior steady state hopf bifurcation occurs when the time delay passes a critical value the estimation of the length of delay to preserve stability has been derived moreover based on the normal form theory and center manifold theorem we establish explicit expressions to determine the direction of hopf bifurcation and the stability of bifurcating periodic solutions numerical simulations are obtained to validate our analytical findings by varying the system parameter a two parameters bifurcation diagrams are also shown by varying the system parameters which bring out the rich biological dynamics of the system

uniform persistence in functional differential equations abstract in this paper we investigate the question of uniform persistence for retarded functional differential equations by utilizing liapunov like functions razumikhin techniques and differential inequalities we are able to establish criteria for uniform persistence analogous to those obtained by others for ordinary differential equations difference equations and reaction diffusion equations we apply these criteria to some well known biological models with delay our results indicate that the conditions which guarantee the existence of an interior equilibrium are enough to ensure uniform persistence moreover these conditions are equivalent to uniform persistence for the cases without delay as well

scene matching using f histogram based features with possibilistic c means optimization this paper outlines further advances from initial findings previously reported in o sjahputera j m keller possibilistic c means in scene matching fourth internat conf of the european society for fuzzy logic and technology eusflat 2005 pp 669 675 we propose a scene matching approach based on spatial relationships among objects in the images to determine if two images acquired under different viewing conditions capture the same scene this is a difficult problem in computer vision our approach produces a mapping of objects from one view to the other and recovers the viewing transformation parameters the core of the system relies on capturing spatial relationship information through force histograms as affine invariant image descriptors object mapping across images is performed by finding the best correspondence map fmap between force histograms in the two images the major problem is that the number of potential fmaps is large even for modest numbers of scene objects hence search optimization is required the correct fmap contains histogram correspondences represented by similar feature vectors therefore dense regions in the feature space are suspected to contain these vectors possibilistic c means pcm clustering is used to find these dense regions the centroids of these dense regions are used to generate the fmaps previously the fmap was generated using a nearest neighbor like approach in this study we propose an improved version of this method by incorporating fuzzy memberships into the fmap building process here the fitness of fmap candidates are assessed with respect to all histogram correspondences already in fmap not just from an initial seed point alone the best fmap is selected and translated into a mapping scheme that connects the objects in the two images

hopf bifurcation in differential equations with delay for tumor immune system competition model this paper deals with the qualitative analysis of the solutions to a model that refers to the competition between the immune system and an aggressive host such as a tumor the model which describes this competition is governed by a system of differential equations with one delay it is shown that the dynamics depends crucially on the time delay parameter by using the time delay as a parameter of bifurcation the analysis is focused on the hopf bifurcation problem to predict the occurrence of a limit cycle bifurcating from the nontrivial steady state the obtained results depict the oscillations given by simulations see m galach int j appl math comput sci 13 2003 pp 395 406 which are observed in reality see d kirschner and j c panetta j math biol 37 1998 pp 235 252 it is suggested to examine by laboratory experiments how to employ these results for control of tumor growth

in defense of the eight point algorithm the fundamental matrix is a basic tool in the analysis of scenes taken with two uncalibrated cameras and the eight point algorithm is a frequently cited method for computing the fundamental matrix from a set of eight or more point matches it has the advantage of simplicity of implementation the prevailing view is however that it is extremely susceptible to noise and hence virtually useless for most purposes this paper challenges that view by showing that by preceding the algorithm with a very simple normalization translation and scaling of the coordinates of the matched points results are obtained comparable with the best iterative algorithms this improved performance is justified by theory and verified by extensive experiments on real images

contour motion estimation from image sequences using curvature information this paper presents a novel method of velocity field estimation for the points on moving contours in a 2 d image sequence the method determines the corresponding point in a next image frame by considering the curvature change of a given point on the contour in traditional methods there are errors in optical flow estimation for the points which have low curvature variations since those methods compute solutions by approximating normal optical flow the proposed method computes optical flow vectors of contour points minimizing the curvature changes as a first step snakes are used to locate smooth curves in 2 d imagery thereafter the extracted curves are tracked continuously each point on a contour has a unique corresponding point on the contour in the next frame whenever the curvature distribution of the contour varies smoothly the experimental results showed that the proposed method computes accurate optical flow vectors for various moving contours

image registration by matching relational structures abstract we present a method of image registration where we use relational structures as representations of images and we register two images by finding a match between the two relational structures it is better than traditional cross correlation like techniques in several aspects it is insensitive to scaling rotation gray level modification and small relative motion between the two images the matching process makes use of star structures which have several advantages over conventional node structures

dynamic behavior of a beddington deangelis type stage structured predator prey model abstract this paper deals with a robust stage structured predator prey model with beddington deangelis type functional response the proposed mathematical model consists of a system of three nonlinear ordinary differential equations to stimulate the interactions between prey population juvenile predators and adult predator population the positivity boundedness and the conditions for uniform persistence have been derived the dynamical behavior of the system both analytically and numerically investigated from the point of view of local stability persistence and global stability the global stability of the system has been derived by using the theory of competitive systems stability of periodic orbits and compound matrices for the interior equilibrium point depending on the conversion rate of the prey population to juvenile predator the model exhibits hopf bifurcation the model admit periodic solutions which is produced from the stage structure of the predator populations numerical simulations have been accomplished to validate our analytical findings

a stage structured predator prey model of beddington deangelis type we formulate and study a robust stage structured predator prey model of beddington deangelis type functional response the time delay is the time taken from birth to maturity the beddington deangelis functional response is similar to the holling type 2 functional response but contains an extra term describing mutual interference by predators first we show that the predator coexists with prey permanently if and only if the predator s recruitment rate at the peak of prey abundance is larger than its death rate second we show that if the system is permanent then a sufficiently large degree of the predator interference can not only stabilize the system but also guarantee the stability of the system against the increase of the carrying capacity of prey and the increase of birth rate of the adult predator third we show both analytically and numerically that stability switches of interior equilibrium may occur as maturation time delay increases stability may change from stable to unstable to finally stable implying that a large delay can be stabilizing

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

implicit explicit time discretization coupled with finite element methods for delayed predator prey competition reaction diffusion system the main purpose of this paper is to develop the two step implicit explicit imex time discretization coupled with finite element methods for solving delayed predator prey competition reaction diffusion system finite element methods are used to discretize the space variables both imex two step one leg methods and imex linear two step methods are considered in time discretization where the nonlinear reaction part is discretized explicitly and the diffusion part is discretized implicitly the l 2 norm error estimates with handling the breaking points are derived these methods only require solving two independent linear systems with the same coefficient matrix at different time and avoid solving large scale systems of nonlinear algebraic equations thus the resulting schemes are efficient some numerical experiments are presented to confirm the theoretical results

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

optimize design of adaptive synchronization controllers and parameter observers in different hyperchaotic systems based on the lyapunov stability and adaptive synchronization theory optimization design of adaptive controllers and parameter observers with controllable gain coefficient are investigated in detail the linear errors of corresponding variables and parameters are used to construct different appropriate positive lyapunov functions v and the parameter observers and adaptive controllers are approached analytically by simplifying the differential inequality dv dt 0 particularly an optional gain coefficient is selected in the parameter observers and positive lyapunov function which decides the transient period to identify the unknown parameters and reach synchronization the scheme is used to study the synchronization of two non identical hyperchaotic rossler systems the theoretical and numerical results confirm that the four unknown parameters in the drive system are estimated exactly and the two hyperchaotic systems reach complete synchronization when the controllers and parameter observers work on the driven system to confirm the model independence of this scheme an alternative hyperchaotic system is investigated whereby the results confirm that the five unknown parameters are identified rapidly and exactly and that the two hyperchaotic systems reach complete synchronization as well

contour matching using epipolar geometry matching features computed in images is an important process in multiview image analysis when the motion between two images is large the matching problem becomes very difficult in this paper we propose a contour matching algorithm based on geometric constraints with the assumption that the contours are obtained from images taken from a moving camera with static scenes we apply the epipolar constraint between two sets of contours and compute the corresponding points on the contours from the initial epipolar constraints obtained from corner point matching candidate contours are selected according to the epipolar geometry contour end point constraints and contour distance measures in order to reduce the possibility of false matches the number of match points on a contour is also used as a selection measure the initial epipolar constraint is refined from the matched sets of contours the algorithm can be applied to a pair or two pairs of images all of the processes are fully automatic and successfully implemented and tested with various real images

a remark on the ode with two discrete delays abstract the aim of this paper is to outline a formal framework for the analytical analysis of the hopf bifurcations in the delay differential equations with two independent time delays some results for the differential difference equations with two delays when the both of the coefficients of linearized equation are negative were obtained in x li s ruan j wei stability and bifurcation in delay differential equations with two delays j math anal appl 236 1999 254 280 in the paper we present some remarks on the case studied in x li s ruan j wei stability and bifurcation in delay differential equations with two delays j math anal appl 236 1999 254 280 and also two other cases namely when the coefficients of linearized equation have different signs and when coefficients are both positive

the impact of the media awareness and optimal strategy on the prevalence of tuberculosis abstract in this present study we propose and analyze a mathematical model of tuberculosis tb transmission considering social awareness effects during an epidemic possible equilibrium points of the model are investigated and their stability criterion is discussed basic reproduction number r0 of the model is obtained through the next generation matrix method it has been shown that the infection free equilibrium is locally stable when r0 1 the global asymptotic stability of the endemic equilibrium p is verified by constructing a suitable lyapunov function the possibility of two endemic equilibria when r0 r 0 1 also verified using center manifold theory the media awareness parameters influence the occurrence of backward bifurcation an optimal control problem is framed considering a media intervention parameter u t as a control variable the existence and characterization of the optimal solution to the problem solved analytically optimal media control strategy with accessible media intervention cost gradually reduce the prevalence of the disease in addition to our analytical results several numerical simulations are also performed to make the analysis more significant a short discussion on the media guided transmission characteristic of the disease obtained from our investigation is conducted at last

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

dynamical analysis of an age structured tuberculosis mathematical model with ltbi detectivity abstract the age dependent heterogeneity observed in tuberculosis tb epidemiology includes susceptibility infectiousness contact preferences of an individual also the chance of finding a direct route to infectious pulmonary tb ptb of certain vulnerable risk group and the diagnosis effort to detect latent tb individual ltbi are critical factors in tb epidemiology the current investigation proposes a mathematical model based on a set of coupled partial differential equations pde to encounter these vital characteristics of tb transmission the analytical study mainly encompasses well posedness of the pde system the asymptotic behaviour of the model around the disease free equilibrium point p 0 and existence criterion of endemic equilibrium point p a threshold quantity r 0 called basic reproductive number provides the average size of infected population due to a single infectious individual introduced in the naive community the current expression of r 0 offers a notable refinement in basic reproduction number compared to previous estimations also theoretically we observe detectivity of ltbi cases can both increase and decrease the size of r 0 depending upon a parametric condition

persistence in dynamical systems soit un espace metrique localement compact de metrique d et soit e un sous ensemble clos de a frontiere e et interieur e on suppose que l on a un flot continu 7b f defini sur e tel que e est invariant par 7b f on considere la notion de persistance et on donne un critere de persistance

global dynamics of a predator prey model with stage structure for the predator the global properties of a predator prey model with nonlinear functional response and stage structure for the predator are studied using lyapunov functions and lasalle s invariance principle it is found that under hypotheses which ensure the uniform persistence of the system and the existence of a unique positive steady state a feasible a priori lower bound condition on the abundance of the prey population ensures the global asymptotic stability of the positive steady state a condition which leads to the extinction of the predators is indicated we also obtain results on the existence and stability of periodic solutions in particular when 4 2 fails to hold and the unique positive steady state e becomes unstable the coexistence of prey and predator populations is ensured for initial populations not on the one dimensional stable manifold of e albeit with fluctuating population sizes

robust regression methods for computer vision a review regression analysis fitting a model to noisy data is a basic technique in computer vision robust regression methods that remain reliable in the presence of various types of noise are therefore of considerable importance we review several robust estimation techniques and describe in detail the least median of squares lmeds method the method yields the correct result even when half of the data is severely corrupted its efficiency in the presence of gaussian noise can be improved by complementing it with a weighted least squares based procedure the high time complexity of the lmeds algorithm can be reduced by a monte carlo type speed up technique we discuss the relationship of lmeds with the ransac paradigm and its limitations in the presence of noise corrupting all the data and we compare its performance with the class of robust m estimators references to published applications of robust techniques in computer vision are also given

correlation matching by finite length sequences the problem of matching a finite length data sequence to a set of not necessarily uniformly spaced correlation lags is considered a characterization of the set of correlations that can be derived from sequences of a given length is presented using this characterization an algorithm called the expanding hull algorithm is presented for determining the minimum sequence length and a sequence of this length which matches a given set of correlation values is obtained this sequence has a z transform which is the lowest order correlation matching moving average model the sequence also generates the minimum length correlation extension the expanding hull algorithm also provides a method for extendibility testing of missing lag and multidimensional correlation sequences numerical examples are provided

synchronization transition in degenerate optical parametric oscillators induced by nonlinear coupling in this paper the synchronization of certain degenerate optical parametric oscillators is investigated in detail complete and or partial synchronization can be reached when linear controller constructed by the real part or imaginary part of the subharmonic mode is imposed on the chaotic degenerate optical parametric oscillators with appropriate coupling intensity the lyapunov exponents under different coupling coefficients are calculated to find the critical condition for complete synchronization transition from complete synchronization to partial synchronization is observed when nonlinear coupling is introduced into the two chaotic oscillators it is found that synchronization of chaotic oscillators keeps robust when the intensity of the nonlinear coupling is less than the intensity of the linear coupling the complete synchronization state is destructed and transient period for partial synchronization is in certain delay when the intensity of the nonlinear coupling is beyond the intensity of the linear coupling

spatiotemporal patterns in the belousov zhabotinskii reaction systems with atangana baleanu fractional order derivative abstract in this paper a robust numerical simulation technique based on the fractional adams bashforth and the fourier spectral methods are formulated to explore some spatiotemporal patterns in a range of belousov zhabotinskii reaction systems the standard integer order time derivative is replaced with the atangana baleanu fractional order derivative in the sense of caputo details of existence and stability of positive solution are given numerical experiments are carried out at some instances of fractional power to demonstrate the suitability of the methods and to explore the dynamic richness in some chemical species when modelled with non integer order derivatives

a two stage cross correlation approach to template matching two stage template matching with sum of absolute differences as the similarity measure has been developed by vanderburg and rosenfeld 1 2 this correspondence shows the development of two stage template matching with cross correlation as the similarity measure the threshold value of the first stage is derived analytically and its validity is verified experimentally considerable speed up over the one stage process can be obtained by introducing only a small false dismissal probability