energy decay for timoshenko systems of memory type abstract linear systems of timoshenko type equations for beams including a memory term are studied the exponential decay is proved for exponential kernels while polynomial kernels are shown to lead to a polynomial decay the optimality of the results is also investigated

retinal artery vein classification via topology estimation we propose a novel graph theoretic framework for distinguishing arteries from veins in a fundus image we make use of the underlying vessel topology to better classify small and midsized vessels we extend our previously proposed tree topology estimation framework by incorporating expert domain specific features to construct a simple yet powerful global likelihood model we efficiently maximize this model by iteratively exploring the space of possible solutions consistent with the projected vessels we tested our method on four retinal datasets and achieved classification accuracies of 91 0 93 5 91 7 and 90 9 outperforming existing methods our results show the effectiveness of our approach which is capable of analyzing the entire vasculature including peripheral vessels in wide field of view fundus photographs this topology based method is a potentially important tool for diagnosing diseases with retinal vascular manifestation

boundary control of the timoshenko beam it is shown that the timoshenko beam can be uniformly stabilized by means of a boundary control a numerical study on the spectrum is also presented

the stability number of the timoshenko system with second sound abstract in this work we consider the timoshenko beam model with second sound we introduce a new number 0 that characterizes the exponential decay we prove that the corresponding semigroup associated to the system is exponentially stable if and only if 0 0 otherwise there is a lack of exponential stability in this case we prove that the semigroup decays as t 1 2 moreover we show that the rate is optimal

on timoshenko type systems with type iii thermoelasticity asymptotic behavior abstract in this study we consider a thermoelastic beam system where the oscillations are defined by the timoshenko model and heat conduction is given by the green and naghdi theories we provide an explicit characterization of the decay rate which can be exponential or polynomial depending on the relationship between the coefficients of the wave propagation speed

stabilisation of a thermo elastic system under nonuniformly bounded disturbances in the boundary input abstractwe consider the exponential stabilisation for a thermo elastic system of type ii with nonuniformly bounded external disturbances in the boundary control we begin with finding feedback controls for the system without disturbances by lyapunov function approach then based on the resulting feedback control we give new dynamic feedback control laws that make the system exponentially stable by tracking disturbances exponentially through a time varying high gain observer we apply the linear operator semi group theory to prove the well posedness of the resulting closed system finally we prove that the solution of the closed loop system can approach zero polynomially or exponentially by the lyapunov function approach

zero inflated poisson regression with an application to defects in manufacturing zero inflated poisson zip regression is a model for count data with excess zeros it assumes that with probability p the only possible observation is 0 and with probability 1 p a poisson random variable is observed for example when manufacturing equipment is properly aligned defects may be nearly impossible but when it is misaligned defects may occur according to a poisson distribution both the probability p of the perfect zero defect state and the mean number of defects in the imperfect state may depend on covariates sometimes p and are unrelated other times p is a simple function of such as p l 1 t for an unknown constant t in either case zip regression models are easy to fit the maximum likelihood estimates mle s are approximately normal in large samples and confidence intervals can be constructed by inverting likelihood ratio tests or using the approximate normality of the mle s simulations suggest that the confidence intervals based on likelihood ratio test

mildly dissipative nonlinear timoshenko systems global existence and exponential stability we consider nonlinear systems of timoshenko type in a one dimensional bounded domain the system has a dissipative mechanism being present only in the equation for the rotation angle it is a damping effect through heat conduction the global existence of small smooth solutions as well as the exponential stability are investigated

boundary stabilization of solutions of a nonlinear system of timoshenko type in this paper we are concerned with a multidimensional timoshenko system subjected to boundary conditions of memory type we establish general rate decay results the usual exponential and polynomial decay rates are only special cases

growth and uniqueness in thermoelasticity a uniqueness theorem is proved for two theories of thermoelasticity capable of admitting finite speed thermal waves the theories having been proposed by green naghdi uniqueness is proved under

decay rates for 1 d mixed type ii and type iii thermoelastic system with localized viscous damping abstract this work is devoted to discussing that how the locations of the thermal and viscous damping affect the stability of the 1 d elastic systems the spatial domain of the 1 d thermoelastic system under consideration can be divided into three sub intervals that is the thermoelastic region of type ii the one of type ii with viscous damping and the one of type iii the following two kinds of energy decay rates for the system are obtained 1 if the thermoelastic region of type iii includes one exterior point of the spatial domain of the system the energy of the system decays exponentially 2 if not that is the thermoelastic region of type iii is strictly inside the spatial domain the system always lacks of exponential decay however the optimal polynomial decay rate is further estimated for this system with smooth initial states finally some numerical simulations are presented to verify the stability results obtained in this work

a re examination of the basic postulates of thermomechanics this paper is mainly concerned with a re examination of the basic postulates and the consequent procedure for the construction of the constitutive equations of material behaviour in thermomechanics however the implication of the basic postulates and the significance of the related procedure for the development of the constitutive equations is also illustrated in some detail in the context of flow of heat in a rigid solid with particular reference to the propagation of thermal waves at finite speed more specifically after briefly examining the nature of the basic equations of motion for a system of particles within the scope of the classical newtonian mechanics the basic postulates of the purely mechanical theory for a continuum including its specialization for a rigid body is re examined this includes some differences from the usual procedure on the subject next thermal variables are introduced and after observing a useful analogy between the thermal and mechanical variables a discussion of a theory of heat or a purely thermal theory is provided which differs from the usual development in the classical thermodynamics a detailed application of the latter development is then made to the problem of heat flow in a stationary rigid solid using several different and well motivated constitutive equations special cases of these include linearized theories of the classical heat flow by conduction and of heat flow transmitted as thermal waves the remainder of the paper is concerned with thermal mechanical theory of deformable media along with discussions of a number of related issues on the subject

global existence asymptotic behavior and uniform attractors for a non autonomous timoshenko system of thermoelasticity of type iii with a time varying delay abstract in this paper we first establish the global existence by using the variable norm technique of kato and semigroup method second under suitable assumptions on the data we obtain the asymptotic behavior of the solution last we prove the existence of a uniform attractor by using the method of uniform contractive functions

convergence and structural stability in thermoelasticity we analyze the equations of thermoelasticity in a linear approximation first we prove that the solution depends continuously on changes in two thermal constants next we investigate how the solution of thermoelasticity of type iii converges to the solution of the usual thermoelasticity and to the solution of thermoelasticity without energy dissipation consequently we can also obtain an estimate of the approximation when we compare the classical thermoelasticity with thermoelasticity without energy dissipation last section investigates the structural stability in the class of thermoelasticity without energy dissipation

timoshenko systems with indefinite damping abstract we consider the timoshenko system in a bounded domain 0 l r 1 the system has an indefinite damping mechanism i e with a damping function a a x possibly changing sign present only in the equation for the rotation angle we shall prove that the system is still exponentially stable under the same conditions as in the positive constant damping case and provided a 0 l a x d x 0 and a a l 2 for small enough the decay rate will be described explicitly in the arguments we shall also give a new proof of exponential stability for the constant case a a moreover we give a precise description of the decay rate and demonstrate that the system has the spectrum determined growth sdg property i e the type of the induced semigroup coincides with the spectral bound for its generator

tree topology estimation tree like structures are fundamental in nature and it is often useful to reconstruct the topology of a tree what connects to what from a two dimensional image of it however the projected branches often cross in the image the tree projects to a planar graph and the inverse problem of reconstructing the topology of the tree from that of the graph is ill posed we regularize this problem with a generative parametric tree growth model under this model reconstruction is possible in linear time if one knows the direction of each edge in the graph which edge endpoint is closer to the root of the tree but becomes np hard if the directions are not known for the latter case we present a heuristic search algorithm to estimate the most likely topology of a rooted three dimensional tree from a single two dimensional image experimental results on retinal vessel plant root and synthetic tree data sets show that our methodology is both accurate and efficient

decay rate estimates for the quasi linear timoshenko system with nonlinear control and damping terms in this work we consider a class of quasi linear timoshenko systems with nonlinear control and damping terms we investigate the stabilization of weak solutions to the initial boundary value problem and obtain explicit decay rate estimation depending on control and damping terms

stabilization of the nonuniform timoshenko beam in this paper we consider a timoshenko beam with variable physical parameters we prove that the model can be stabilize by one control force for both internal and boundary cases

general energy decay in a timoshenko type system of thermoelasticity of type iii with a viscoelastic damping in this paper we consider a one dimensional linear thermoelastic system of timoshenko type where the heat conduction is given by green and naghdi theories we prove a general decay result from which the exponential and polynomial decays are only special cases

energy decay in a timoshenko type system of thermoelasticity of type iii in this paper we consider a one dimensional linear thermoelastic system of timoshenko type where the heat conduction is given by green and naghdi theories we prove the exponential stability by using the energy method

tubular structure segmentation based on minimal path method and anisotropic enhancement we present a new interactive method for tubular structure extraction the main application and motivation for this work is vessel tracking in 2d and 3d images the basic tools are minimal paths solved using the fast marching algorithm this allows interactive tools for the physician by clicking on a small number of points in order to obtain a minimal path between two points or a set of paths in the case of a tree structure our method is based on a variant of the minimal path method that models the vessel as a centerline and surface this is done by adding one dimension for the local radius around the centerline the crucial step of our method is the definition of the local metrics to minimize we have chosen to exploit the tubular structure of the vessels one wants to extract to built an anisotropic metric the designed metric is well oriented along the direction of the vessel admits higher velocity on the centerline and provides a good estimate of the vessel radius based on the optimally oriented flux this measure is required to be robust against the disturbance introduced by noise or adjacent structures with intensity similar to the target vessel we obtain promising results on noisy synthetic and real 2d and 3d images and we present a clinical validation

global existence asymptotic stability and uniform attractors for non autonomous thermoelastic systems with constant time delay in this paper we first consider a non autonomous thermoelastic system with a boundary delay and obtain the asymptotic behavior then using the contractive function method and multiplier techniques we establish the asymptotic behavior and the existence of a uniform attractor of the system with a boundary time delay the main advantage of this method is that we only need to verify compactness condition with the type of energy estimates same as those for establishing the absorbing set moreover we investigate an alternative result of solutions to semilinear thermoelastic systems by virtue of the semigroup method

pointwise a posteriori error control for discontinuous galerkin methods for elliptic problems an a posteriori error bound for the maximum pointwise error for the interior penalty discontinuous galerkin method for a standard elliptic model problem on polyhedral domains is presented the computational domain is not required to be lipschitz thus allowing for domains with cracks and other irregular polyhedral domains the proof is based on the direct use of green s functions and varies substantially from the approach used in previous proofs of similar l infty estimates for continuous finite element methods in the literature numerical experiments indicating the good behavior of the resulting a posteriori bounds within an adaptive algorithm are also presented