adaptive noise smoothing filter for images with signal dependent noise in this paper we consider the restoration of images with signal dependent noise the filter is noise smoothing and adapts to local changes in image statistics based on a nonstationary mean nonstationary variance nmnv image model for images degraded by a class of uncorrelated signal dependent noise without blur the adaptive noise smoothing filter becomes a point processor and is similar to lee s local statistics algorithm 16 the filter is able to adapt itself to the nonstationary local image statistics in the presence of different types of signal dependent noise for multiplicative noise the adaptive noise smoothing filter is a systematic derivation of lee s algorithm with some extensions that allow different estimators for the local image variance the advantage of the derivation is its easy extension to deal with various types of signal dependent noise film grain and poisson signal dependent restoration problems are also considered as examples all the nonstationary image statistical parameters needed for the filter can be estimated from the noisy image and no a priori information about the original image is required

performance advantage of complex lms for controlling narrow band adaptive arrays in narrow band adaptive array applications the mean square convergence of the discrete time real least mean square lms algorithm is slowed by image frequency noises generated in the lms loops the complex lms algorithm proposed by widrow et al is shown to eliminate these noises yielding convergence of the mean squared error mse at slightly over twice the rate this paper includes a comprehensive analysis of the mse of adaptation for lms the analysis is based upon the method developed in the 1968 dissertation by k d senne and it represents the most complete treatment of the subject published to date

geometric algebra and the causal approach to multiparticle quantum mechanics it is argued that geometric algebra in the form of the multiparticle spacetime algebra is well suited to the study of multiparticle quantum theory with advantages over conventional techniques both in ease of calculation and in providing an intuitive geometric understanding of the results this is illustrated by comparing the geometric algebra approach for a system of two spin 1 2 particles with the nonrelativistic approach of holland phys rep 169 294 1988

second order consensus of multi agent systems in the cooperation competition network with switching topologies a time delayed impulsive control approach abstract this paper investigates the consensus problem of second order multi agent systems with switching topologies by designing a time delayed impulsive consensus control scheme all the agents are governed by the same nonlinear intrinsic dynamics in this study agents can cooperate or compete with each other i e the elements in the weight matrix of the coupling graph can be either positive or negative by establishing a comparison system a new comparison principle method is successfully applied to study such consensus problem then several effective sufficient conditions are attained without assuming that the interaction topology is strongly connected or contains a directed spanning tree meanwhile the exponential consensus rate is also obtained finally simulation results are presented to validate the effectiveness of the theoretical analysis

adaptive lms l filters for noise suppression in images several adaptive least mean squares lms l filters both constrained and unconstrained ones are developed for noise suppression in images and compared in this paper first the location invariant lms l filter for a nonconstant signal corrupted by zero mean additive white noise is derived it is demonstrated that the location invariant lms l filter can be described in terms of the generalized linearly constrained adaptive processing structure proposed by griffiths and jim 1982 subsequently the normalized and the signed error lms l filters are studied a modified lms l filter with nonhomogeneous step sizes is also proposed in order to accelerate the rate of convergence of the adaptive l filter finally a signal dependent adaptive filter structure is developed to allow a separate treatment of the pixels that are close to the edges from the pixels that belong to homogeneous image regions

lsb steganographic method based on reversible histogram transformation function for resisting statistical steganalysis statistical steganalysis schemes detect the existence of secret information embedded by steganography the x 2 detection and regular singular rs attack methods are two well known statistical steganalysis schemes used against lsb least significant bit steganography the embedded message length can be estimated accurately by these two steganalysis schemes for secret communication the resistance of steganography against steganalysis is very important for information security to avoid the enemy s attempts the statistical features between stego images and cover images should be as similar as possible for better resistance to steganalysis in this manuscript a reversible histogram transformation function based lsb steganographic method is proposed to resist statistical steganalysis the experimental results show that the proposed method resists not only rs attack but also x 2 detection methods

absolute exponential l1 gain analysis and synthesis of switched nonlinear positive systems with time varying delay this paper investigates absolute exponential stability and stabilization with l1 gain performance of switched nonlinear positive systems with time varying delay nonlinear functions considered in the paper are located in a sector field and the time varying delay is unknown but bounded the notion of absolute exponential l1 stability of switched nonlinear positive systems is first introduced a nonlinear lyapunov krasovskii functional is constructed for the underlying systems by using the lyapunov krasovskii functional a sufficient condition for absolute exponential l1 stability of the systems is established in terms of linear programming then absolute exponential l1 control synthesis of the systems is addressed a feedback control law containing nonlinear functions and a state feedback control law are designed respectively by comparing with existing results it is shown that the present design is less conservative finally an illustrative example is provided to illustrate the effectiveness of the results

finite time stochastic input to state stability of impulsive switched stochastic nonlinear systems this paper mainly tends to investigate the finite time stochastic input to state stability ftsiss problem for a class of impulsive switched stochastic nonlinear systems an efficient lemma is firstly established to construct a generalized class kl function further a set of lyapunov based sufficient conditions are derived to check the finite time stability in probability ftsip and finite time input to state stability ftiss properties of switched stochastic nonlinear systems with or without impulses in particular some useful results in favor of simulations are obtained in terms of average dwell time technique finally a numerical example is provided to illustrate the effectiveness of proposed results

aggregation and stability analysis of nonlinear complex systems the problem of stability of large scale systems in critical cases is investigated new form of aggregation for essentially nonlinear complex systems is suggested with the help of this form the sufficient conditions of asymptotic stability are determined the results obtained are used for the stability analysis of complex systems by the nonlinear approximation and for the investigation of absolute stability conditions for a certain class of nonlinear systems

stability criteria for switched and hybrid systems the study of the stability properties of switched and hybrid systems gives rise to a number of interesting and challenging mathematical problems the objective of this paper is to outline some of these problems to review progress made in solving them in a number of diverse communities and to review some problems that remain open an important contribution of our work is to bring together material from several areas of research and to present results in a unified manner we begin our review by relating the stability problem for switched linear systems and a class of linear differential inclusions closely related to the concept of stability are the notions of exponential growth rates and converse lyapunov theorems both of which are discussed in detail in particular results on common quadratic lyapunov functions and piecewise linear lyapunov functions are presented as they represent constructive methods for proving stability and also represent problems in which significant progress has been made we also comment on the inherent difficulty in determining stability of switched systems in general which is exemplified by np hardness and undecidability results we then proceed by considering the stability of switched systems in which there are constraints on the switching rules through both dwell time requirements and state dependent switching laws also in this case the theory of lyapunov functions and the existence of converse theorems are reviewed we briefly comment on the classical lur e problem and on the theory of stability radii both of which contain many of the features of switched systems and are rich sources of practical results on the topic finally we present a list of questions and open problems which provide motivation for continued research in this area

on signal recovery with adaptive order statistic filters adaptive order statistic filters are used to estimate a constant amplitude signal embedded in noise with unknown statistics iterative algorithms are proposed which adapt the order statistic filter to minimize the mean square estimation error both with and without an unbiasedness constraint for each case the algorithm used is shown to achieve convergence in the mean to the optimal filter properties of the convergence rates are discussed and conditions for convergence in mean square are noted

stability analysis of lur e type switched systems this technical note aims to introduce stability analysis of lur e type switched systems in frequency domain a new state input dependent switching function is proposed and it is the key issue to obtain a stability condition that generalizes the celebrated popov criterion to deal with this class of switched nonlinear systems likewise the case of time invariant systems we propose a frequency domain stability test that is expressed through a convex combination of the subsystems state space matrices this task is not trivial due to the time varying nature of the nonlinear systems under consideration the theory is illustrated by a simple example

vcpss a two in one two decoding options image sharing method combining visual cryptography vc and polynomial style sharing pss approaches this paper presents a novel method to combine two major branches of image sharing vc and pss n transparencies are created for a given gray valued secret image if the decoding computer is temporarily not available at or not connected to the decoding scene we can still physically stack any t received transparencies t n is a threshold value to get a vague black and white view of the secret image immediately on the other hand when the decoding computer is finally available then we can get a much finer gray valued view of the secret image using the information hidden in the transparencies in summary each transparency is a two in one carrier of the information and the decoding has two options

stability analysis of switched systems using variational principles an introduction many natural and artificial systems and processes encompass several modes of operation with a different dynamical behavior in each mode switched systems provide a suitable mathematical model for such processes and their stability analysis is important for both theoretical and practical reasons we review a specific approach for stability analysis based on using variational principles to characterize the most unstable solution of the switched system we also discuss a link between the variational approach and the stability analysis of switched systems using lie algebraic considerations both approaches require the use of sophisticated tools from many different fields of applied mathematics the purpose of this paper is to provide an accessible and self contained review of these topics emphasizing the intuitive and geometric underlying ideas

convergence conditions for some classes of nonlinear systems abstract systems of differential equations with nonlinearities of a sector type and almost periodic perturbations are studied with the aid of the lyapunov direct method conditions are found under which the considered systems admit globally asymptotically stable almost periodic solutions moreover it is shown that the proposed approach permits us to derive new convergence conditions for some models of neural networks and generalized lotka volterra models of population dynamics an example is presented to demonstrate the effectiveness of the obtained results

technical communique on stability of a class of switched nonlinear systems this note is focused on the stability analysis for a class of switched nonlinear systems with disturbance input and delay sufficient conditions in terms of linear inequalities are presented such that the switched system is asymptotically stable for arbitrary switching any admissible sector nonlinearities and disturbances and any constant delay we not only drop a condition of one result given in aleksandrov chen platonov and zhang 2011 but also extend the main result to a more general switched nonlinear system with disturbance input and delay

brief paper on linear co positive lyapunov functions for sets of linear positive systems in this paper we derive necessary and sufficient conditions for the existence of a common linear co positive lyapunov function for a finite set of linear positive systems both the state dependent and arbitrary switching cases are considered our results reveal an interesting characterisation of linear stability for the arbitrary switching case namely the existence of such a linear lyapunov function can be related to the requirement that a number of extreme systems are metzler and hurwitz stable examples are given to illustrate the implications of our results

geometric algebra and information geometry for quantum computational software abstract the art of quantum algorithm design is highly nontrivial grover s search algorithm constitutes a masterpiece of quantum computational software in this article we use methods of geometric algebra ga and information geometry ig to enhance the algebraic efficiency and the geometrical significance of the digital and analog representations of grover s algorithm respectively specifically ga is used to describe the grover iterate and the discretized iterative procedure that exploits quantum interference to amplify the probability amplitude of the target state before measuring the query register the transition from digital to analog descriptions occurs via stone s theorem which relates the unitary grover iterate to a suitable hermitian hamiltonian that controls schrodinger s quantum mechanical evolution of a quantum state towards the target state once the discrete to continuos transition is completed ig is used to interpret grover s iterative procedure as a geodesic path on the manifold of the parametric density operators of pure quantum states constructed from the continuous approximation of the parametric quantum output state in grover s algorithm finally we discuss the dissipationless nature of quantum computing recover the quadratic speedup relation and identify the superfluity of the walsh hadamard operation from an ig perspective with emphasis on statistical mechanical considerations

diagonal lyapunov krasovskii functionals for discrete time positive systems with delay we consider the existence of diagonal lyapunov krasovskii l k functionals for positive discrete time systems subject to time delay in particular we show that the existence of a diagonal functional is necessary and sufficient for delay independent stability of a positive linear time delay system we extend this result and provide conditions for the existence of diagonal l k functionals for classes of nonlinear positive time delay systems which are not necessarily order preserving we also describe sufficient conditions for the existence of common diagonal l k functionals for switched positive systems subject to time delay

a generalization of median filtering using linear combinations of order statistics we consider a class of nonlinear filters whose output is given by a linear combination of the order statistics of the input sequence assuming a constant signal in white noise the coefficients in the linear combination are chosen to minimize the output mse for several noise distributions it is shown that the optimal order statistic filter osf tends toward the median filter as the noise becomes more impulsive the optimal osf is applied to an actual noisy image and is shown to perform well combining properties of both the averaging and median filters a more general design scheme for applications involving nonconstant signals is also given

image hiding scheme with modulus function and dynamic programming strategy on partitioned pixels in this paper we shall propose a novel image hiding scheme our new scheme classifies the host image pixels into two groups of pixels according to the pixel values for each group of pixels the corresponding secret pixel values go through an optimal substitution process and are transformed into other pixel values by following the dynamic programming strategy then we can embed the transformed pixel values in the host pixels by using the modulus functions and obtain the stego image extensive experimental results demonstrate that our new method is capable of offering better stego image quality than a number of well accepted schemes

diagonal riccati stability and applications abstract we consider the question of diagonal riccati stability for a pair of real matrices a b a necessary and sufficient condition for diagonal riccati stability is derived and applications of this to two distinct cases are presented we also describe some motivations for this question arising in the theory of generalised lotka volterra systems

algebraic and dirac hestenes spinors and spinor fields almost all presentations of dirac theory in first or second quantization in physics and mathematics textbooks make use of covariant dirac spinor fields an exception is the presentation of that theory first quantization offered originally by hestenes and now used by many authors there a new concept of spinor field as a sum of nonhomogeneous even multivectors fields is used however a careful analysis detailed below shows that the original hestenes definition cannot be correct since it conflicts with the meaning of the fierz identities in this paper we start a program dedicated to the examination of the mathematical and physical basis for a comprehensive definition of the objects used by hestenes in order to do that we give a preliminary definition of algebraic spinor fields asf and dirac hestenes spinor fields dhsf on minkowski space time as some equivalence classes of pairs u u where u is a spinorial frame field and u is an appropriate sum of multivectors fields to be specified below the necessity of our definitions are shown by a careful analysis of possible formulations of dirac theory and the meaning of the set of fierz identities associated with the bilinear covariants on minkowski space time made with asf or dhsf we believe that the present paper clarifies some misunderstandings past and recent appearing on the literature of the subject it will be followed by a sequel paper where definitive definitions of asf and dhsf are given as appropriate sections of a vector bundle called the left spin clifford bundle the bundle formulation is essential in order to be possible to produce a coherent theory for the covariant derivatives of these fields on arbitrary riemann cartan space times the present paper contains also appendixes a e which exhibits a truly useful collection of results concerning the theory of clifford algebras including many tricks of the trade necessary for the intelligibility of the text

stabilization and robust h control for sector bounded switched nonlinear systems this paper presents stability analysis and robust h control for a particular class of switched systems characterized by nonlinear functions that belong to sector sets with arbitrary boundaries the sector boundaries can have positive and or negative slopes and therefore we cover the most general case in our approach using the special structure of the system but without making additional assumptions e g on the derivative of the nonlinear functions and by proposing new multiple lyapunov function candidates we formulate stability conditions and a control design procedure in the form of matrix inequalities the proposed lyapunov functions are more general than the quadratic functions previously proposed in the literature as they incorporate the nonlinearities of the system and hence lead to less conservative stability conditions the stabilizing switching controllers are designed through a bi level optimization problem that can be efficiently solved using a combination of a convex optimization algorithm and a line search method the proposed optimization problem is achieved using a special loop transformation to normalize the arbitrary sector bounds and by other linear matrix inequalities lmi techniques

secret image sharing based on cellular automata and steganography recently lin and tsai secret image sharing with steganography and authentication the journal of systems and software 73 2004 405 414 and yang et al improvements of image sharing with steganography and authentication the journal of systems and software 80 2007 1070 1076 proposed secret image sharing schemes combining steganography and authentication based on shamir s polynomials the schemes divide a secret image into some shadows which are then embedded in cover images in order to produce stego images for distributing among participants to achieve better authentication ability chang et al sharing secrets in stego images with authentication pattern recognition 41 2008 3130 3137 proposed in 2008 an improved scheme which enhances the visual quality of the stego images as well and the probability of successful verification for a fake stego block is 1 16 in this paper we employ linear cellular automata digital signatures and hash functions to propose a novel t n threshold image sharing scheme with steganographic properties in which a double authentication mechanism is introduced which can detect tampering with probability 255 256 employing cellular automata instead of shamir s polynomials not only improves computational complexity from o nlog 2n to o n but obviates the need to modify pixels of cover images unnecessarily compared to previous methods c lin w tsai secret image sharing with steganography and authentication the journal of systems and software 73 2004 405 414 c yang t chen k yu c wang improvements of image sharing with steganography and authentication the journal of systems and software 80 2007 1070 1076 c chang y hsieh c lin sharing secrets in stego images with authentication pattern recognition 41 2008 3130 3137 we use fewer number of bits in each pixel of cover images for embedding data so that a better visual quality is guaranteed we further present some experimental results

color image steganography scheme using dft spiht codec and modified differential phase shift keying techniques abstract in this research on the basis of the differential phase shift keying dpsk technique which is widely used in digital communication systems to develop a steganography scheme we aim to hide a secret image into a cover image of the same size so that the resultant image has no noticeable degradation in our approach three strategies are used to achieve this goal 1 compress the secret image to reduce the number of secret bits the set partitioning in hierarchical trees spiht codec were used to obtain a high reconstructed image quality and low bit rate image compression 2 a neighbor block signal phase comparison nbspc mechanism is used to offer the location for secret data embedding 3 a fold phase distribution differential phase shift keying fpdpsk mechanism is used to improve the quality of the cover image with our contribution we have developed the fold phase distribution dpsk concept to obtain more than 1 5 db quality improvement and twice the noise margin than the standard dpsk technique on the same test condition

a two codebook combination and three phase block matching based image hiding scheme with high embedding capacity image hiding is a technique that embeds the important images into a cover image such that the important images are imperceptible and can be securely transmitted to the receiver in such research the common goals are to enlarge the embedding capacity as much as possible since the visual quality of the cover image is degraded slightly and to keep high visual quality of the important images when they are extracted from the stego image in this paper we propose an image hiding method based on the two codebook combination the three phase block matching procedure and the modulus substitution the proposed method can achieve these benefits 1 multiple relatively large important images can be embedded into a relatively small cover image 2 the quality of the stego image after embedding the secret data is not distorted significantly 3 the important images have an acceptable visual quality after they are extracted the experimental results also show that the proposed method is more flexible than previous methods

convergence analysis of lms filters with uncorrelated gaussian data statistical analysis of the least mean squares lms adaptive algorithm with uncorrelated gaussian data is presented exact analytical expressions for the steady state mean square error mse and the performance degradation due to weight vector misadjustment are derived necessary and sufficient conditions for the convergence of the algorithm to the optimal wiener solution within a finite variance are derived it is found that the adaptive coefficient which controls the rate of convergence of the algorithm must be restricted to an interval significantly smaller than the domain commonly stated in the literature the outcome of this paper therefore places fundamental limitations on the mse performance and rate of convergence of the lms adaptive scheme

color image steganography scheme using set partitioning in hierarchical trees coding digital fourier transform and adaptive phase modulation in this research of color image hidden scheme we aim to conceal a secret image into the cover image of the same size without noticeable degradation in our approach discrete wavelet transform dwt and set partitioning in hierarchical trees spiht codec are used to obtain a low bit rate and high reconstructed quality image compression in the embedding process an adaptive phase modulation apm mechanism and discrete fourier transform dft were adopted for secret data embedding simultaneously nearest phase modulations npm was used to improve the imperceptibility and decrease degradation of cover image both the chaotic mechanism cm and frequency hopping fh structure were hired to enhance the security of the scheme comparing with other data hiding techniques our proposed method has three advantages a the extracted secret image has high quality reconstruction by using spiht coder b the stego image possesses excellent imperceptibility without noticeable degradation because secret data was concealed in the phase by using apm and npm c have very large embedding capacity it allows the size of secret image to be the same as the cover image

multiple watermarking scheme of the european article number barcode using similar code division multiple access technique abstract the code division multiple access technique is widely used in digital communication systems in this paper a mix codec hamming codec and spread spectrum technique construct a similar code division multiple access scdma structure it is used to configure a multiple watermarking scheme for still images meanwhile another type of multiple watermarking scheme a non code division multiple access ncdma watermarking structure is used to demonstrate that the scdma structure is superior in the embedding process three watermark bit streams are modulated to the bit stream of the scdma code successively the scdma code stream is concealed into three coefficient pairs of each dft block by an adaptive phase shift keying apsk modulation the barcode has several advantages it is not as easily worn down as the magnetic card it has a very low rate of error and it is very cheap and easy to be fabricate therefore we use the barcode pattern to generate the watermarks to enhance the effect of the digital rights management compared to other multiple watermarking schemes our proposed method has two advantages 1 the secret image has very high security by using scdma and apsk as in digital communication and 2 the extracted watermarks have the same quality even under all kinds of attacks which is better than other schemes with different extracted watermark quality

stability of stochastic nonlinear switched systems with average dwell time this paper concerns the stability of nonlinear stochastic switched systems with delay by using the razumikhin method and the average dwell time approach some sufficient criteria of stability are derived it is shown that when the lyapunov like functions are decreasing in all active subsystems the switched system is pth moment exponentially stable moreover it is also shown that under some conditions the system can be pth moment stable and global asymptotically stable where the lyapunov like functions are increasing on some intervals the effectiveness of the proposed results is illustrated by two examples

absolute exponential stability and stabilization of switched nonlinear systems abstract this paper is concerned with the problems of absolute exponential stability and stabilization for a class of switched nonlinear systems whose system matrices are metzler nonlinearity of the systems is constrained in a sector field which is bounded by two odd symmetric piecewise linear functions multiple lyapunov functions are introduced to deal with the stability of such nonlinear systems compared with some existing results obtained by the common lyapunov function approach in the literature the conservatism of our results is reduced all present conditions can be solved by linear programming furthermore the absolute exponential stabilization for the considered systems is designed by the state feedback and average dwell time switching strategy two examples are also given to illustrate the validity of the theoretical findings

solution of the stability problem for a class of generalized volterra prey predator systems where ei pij and qj are real constants ui are real valued continuous functions of t for t 0 and zii dui dt both equations are required for i 1 2 m condition lb is here considered to be a restriction on the vector e ei rather than on the matrix p pii as is more usual the hypothesis 0 0 qi 0 is appropriate in applications but as far as the mathematical development is concerned it could be replaced by qiui 0 0 a discussion of historical background can be found in the papers 4 5 to which the present paper is a sequel suffice it to say here that the chief landmarks are volterra s book 6 la salle s theorem 1 21 and krikorian s analysis of the case n 3 3 references 4 5 provide useful

on the convergence behavior of the lms and the normalized lms algorithms it is shown that the normalized least mean square nlms algorithm is a potentially faster converging algorithm compared to the lms algorithm where the design of the adaptive filter is based on the usually quite limited knowledge of its input signal statistics a very simple model for the input signal vectors that greatly simplifies analysis of the convergence behavior of the lms and nlms algorithms is proposed using this model answers can be obtained to questions for which no answers are currently available using other perhaps more realistic models examples are given to illustrate that even quantitatively the answers obtained can be good approximations it is emphasized that the convergence of the nlms algorithm can be speeded up significantly by employing a time varying step size the optimal step size sequence can be specified a priori for the case of a white input signal with arbitrary distribution

steganography of capacity required using modulo operator for embedding secret image in this paper a novel mechanism using modulus operations to incorporate secret data with image form into a host image is proposed the used modulus is a threshold value that indicates how many bits of the secret image are being incorporated into the host image in our scheme there are two kinds of secret images processed the capacities of these two types are half the size and a quarter the size of the chosen host image respectively as can be seen in the result of our experiment not only can the secret images be totally embedded but the extra information such as the auxiliary table assisting the secret extraction is released as well even then there is still space remaining after the hiding procedure is completed the result is a higher capacity exploration for embedding the secret into a host image upon inspection of the quality of the stego image using the measurement of psnr it is noted that not only does the image display make the grade of the human vision system i e it is imperceptible by human eyes as far as the embedded secret is concerned but also the valued results of psnr remain sufficiently stable for a variety of host image selections therefore our proposal scheme is notably superior to those in the previous literature iee proc vision image signal process 147 1 2000 29 the advantages of this proposed scheme are the higher capacity exploration on secret embedding and better stability on stego image displays

stability analysis for a class of switched nonlinear systems this paper addresses the stability analysis of a class of switched nonlinear systems the switched systems have uncertain nonlinear functions constrained in a sector set which are called admissible sector nonlinearities a sufficient condition in terms of linear inequalities is presented to guarantee the existence of a common lyapunov function and thereby to ensure that the switched system is stable for an arbitrary switching signal and any admissible sector nonlinearities a constructive algorithm based on the modified gaussian elimination procedure is given to find the solutions of the linear inequalities the obtained results are applied to a population model with switchings of parameter values and the conditions of ultimate boundedness of its solutions are investigated another example of an automatic control system is considered to demonstrate the effectiveness of the proposed approaches

sharing secrets in stego images with authentication recently lin and tsai and yang et al proposed secret image sharing schemes with steganography and authentication which divide a secret image into the shadows and embed the produced shadows in the cover images to form the stego images so as to be transmitted to authorized recipients securely in addition these schemes also involve their authentication mechanisms to verify the integrity of the stego images such that the secret image can be restored correctly unfortunately these schemes still have two shortcomings one is that the weak authentication cannot well protect the integrity of the stego images so the secret image cannot be recovered completely the other shortcoming is that the visual quality of the stego images is not good enough to overcome such drawbacks in this paper we propose a novel secret image sharing scheme combining steganography and authentication based on chinese remainder theorem crt the proposed scheme not only improves the authentication ability but also enhances the visual quality of the stego images the experimental results show that the proposed scheme is superior to the previously existing methods

design of stabilizing switching laws for mixed switched affine systems this technical note presents stability analysis and stabilization for a general class of switched systems characterized by nonlinear functions the proposed approach is composed of approximating the switched nonlinear system with a switched affine system that has a mixture of controlled and autonomous switching behavior utilizing a joint polyhedral partitioning approach a stabilizing switching law based on quadratic lyapunov functions and with considering the autonomous switching between polyhedral regions is proposed to ensure the decrease of the overall lyapunov function two approaches are proposed 1 guarantee continuity of the lyapunov function over boundaries of polyhedral regions and 2 relax the continuity requirement by using additional matrix inequalities the second approach is less conservative but with more variables and matrix inequalities than in the first method with fixing one scalar variable the stabilization conditions will have the form of linear matrix inequalities lmis further the sufficient conditions for stabilizing the original switched nonlinear system using the proposed switching schemes are presented finally through two examples the performance of the proposed stabilization methods is demonstrated