common fixed point theorems for a family of non self mappings in convex metric spaces abstract in this paper new contraction type non self mappings in a metric space are introduced and conditions guaranteeing the existence of a common fixed point for such non self contractions in a convex metric space are established these results generalize and improve the recent results of imdad and khan m imdad l khan some common fixed point theorems for a family of mappings in metrically convex spaces nonlinear anal theory 67 9 2007 2717 2726 and several others

some common fixed point theorems for mappings and multi valued mappings using certain weak conditions of commutativity we prove some common fixed point theorems in complete metrically convex spaces which in turn generalize results due to assad and kirk itoh khan and several others

common fixed points for multimaps in a metric space on etablit certaines proprietes des fonctions reelles et on les applique pour obtenir des ameliorations aux resultats de papageorgiou sur les points fixes des fonctions multiformes on etend au cas non borne

contractive type non self mappings on metric spaces of hyperbolic type abstract let x d be a metric space of hyperbolic type and k a nonempty closed subset of x in this paper we study a class of mappings from k into x not necessarily self mappings on k which are defined by the contractive condition 2 1 below and a class of pairs of mappings from k into x which satisfy the condition 2 28 below we present fixed point and common fixed point theorems which are generalizations of the corresponding fixed point theorems of ciric l b ciric quasi contraction non self mappings on banach spaces bull acad serbe sci arts 23 1998 25 31 l b ciric j s ume m s khan h k t pathak on some non self mappings math nachr 251 2003 28 33 rhoades b e rhoades a fixed point theorem for some non self mappings math japon 23 1978 457 459 and many other authors some examples are presented to show that our results are genuine generalizations of known results from this area

a tight upper bound of the average absolute error in a constant step size sign algorithm a direct performance index of the adaptive filtering sign algorithm sa is the average absolute error aae at the output of the filter adopting this performance index an easy analysis of sa is achieved under a weak assumption it is proved for both deterministic and random inputs to the filter that the aae has a tight upper bound that exceeds the minimum aae by half the product of the step size and power of the filter input the assumption used is existence of average squared and average absolute values of filter input signals a practical interest of the result is that it provides a formula for the biggest step size as a function of tolerable adaptation noise to desired signal ratio

coupled fixed point theorems for nonlinear contractions in partially ordered metric spaces abstract we introduce the concept of a mixed g monotone mapping and prove coupled coincidence and coupled common fixed point theorems for such nonlinear contractive mappings in partially ordered complete metric spaces presented theorems are generalizations of the recent fixed point theorems due to bhaskar and lakshmikantham t g bhaskar v lakshmikantham fixed point theorems in partially ordered metric spaces and applications nonlinear anal tma 65 2006 1379 1393 and include several recent developments

a common fixed point theorem for compatible quasi contractive self mappings in metric spaces a common fixed point theorem for weakly commuting quasi contractive self mappings with contracting orbital diameters in metric spaces v berinde a common fixed point theorem for quasi contractive type mappings ann univ sci budapest 46 2003 81 90 is extended to the more general class of compatible quasi contractive self mappings our result does extend and generalize numerous related results in literature

some common fixed point theorems for a family of mappings in metrically convex spaces abstract in the present paper some common fixed point theorems for a sequence and a pair of nonself mappings in complete metrically convex metric spaces are proved which generalize such results due to khan et al m s khan h k pathak m d khan some fixed point theorems in metrically convex spaces georgian math j 7 3 2000 523 530 assad n a assad on a fixed point theorem of kannan in banach spaces tamkang j math 7 1976 91 94 chatterjea s k chatterjea fixed point theorems c r acad bulgare sci 25 1972 727 730 and several others some related results are also discussed

comparison of the windkessel model and structured tree model applied to prescribe outflow boundary conditions for a one dimensional arterial tree model one dimensional 1d modeling is a widely adopted approach for studying wave propagation phenomena in the arterial system despite the frequent use of the windkessel wk model to prescribe outflow boundary conditions for 1d arterial tree models it remains unclear to what extent the inherent limitation of the wk model in describing wave propagation in distal vasculatures affect hemodynamic variables simulated at the arterial level in the present study a 1d model of the arterial tree was coupled respectively with a wk boundary model and a structured tree st boundary model yielding two types of arterial tree models the effective resistances compliances and inductances of the wk and st boundary models were matched to facilitate quantitative comparisons obtained results showed that pressure flow waves simulated by the two models were comparable in the aorta whereas their discrepancies increased towards the periphery wave analysis revealed that the differences in reflected waves generated by the boundary models were the major sources of pressure wave discrepancies observed in large arteries additional simulations performed under aging conditions demonstrated that arterial stiffening with age enlarged the discrepancies but with the effects being partly counteracted by physiological aortic dilatation with age these findings suggest that the method adopted for modeling the outflow boundary conditions has considerable influence on the performance of a 1d arterial tree model with the extent of influence varying with the properties of the arterial system

convergence of the sign algorithm for adaptive filtering with correlated data convergence of a decreasing gain sign algorithm sa for adaptive filtering is analyzed the presence of the hard limiter in the algorithm makes a rigorous analysis difficult therefore there are few results available such results normally include restrictive assumptions such as the assumptions that successive observation vectors are independent and the new error signal of the adaptive filter has a time invariant probability density function the former assumption is not valid in the context of adaptive filtering since two successive observation vectors share most of their components while the latter assumption is a restriction on the adaptive weights whose evolution is a priori unknown in lieu of using these assumptions an almost sure convergence of the sa is proved under the assumption that the sequence of observation vectors is m dependent this assumption allows strong correlation between successive observations

rhoades type fixed point theorems for two hybrid pairs of mappings in metrically convex spaces abstract the present paper establishes some common fixed point theorems for two hybrid pairs of nonself mappings defined on a closed subset of a metrically convex metric spaces which generalizes completely or partially some earlier results due to rhoades ciric and ume and many others some related results and an illustrative example are also discussed

some new fixed point theorems of generalized nonlinear contractive multivalued maps in complete metric spaces in this paper we present some new fixed point theorems for generalized nonlinear contractive multivalued maps and these results generalize or improve the corresponding recent fixed point results in the literature

iterative selection methods for the common fixed point problems in a banach space many problems encountered in applied mathematics can be recast as the problem of selecting a particular common fixed point of a countable family of non expansive mappings in banach space in the paper under the hypotheses that e is a reflexive banach space which has a weakly continuous duality mapping j with gauge function several viscosity approximation methods are investigated for finding a common fixed point of non expansive mapping sequences

asymptotic properties of sign algorithms for adaptive filtering this paper develops asymptotic properties of a class of sign error algorithms with expanding truncation bounds for adaptive filtering under merely stationary ergodicity and finite second moments of the reference and output signals and using trajectory subsequence ts method it is proved that the algorithm convergers almost surely then a mean squares estimate is derived for the estimation error and a suitably scaled sequence of the estimation error is shown to converge to a diffusion process the scaling factor together with the stationary covariance gives the rate of convergence result moreover an algorithm under mean squares criterion with expanding truncation bounds is also examined compared with the existing results in the literature sufficient conditions for almost sure convergence are much relaxed a simple example is provided for demonstration purpose

common fixed points of hybrid maps and an application we introduce a new notion that is a generalization of definition 2 1 kamran and cakic 2008 3 using this notion we establish a new result that is coincidence and fixed points for two hybrid pairs of nonself maps satisfying an implicit relation this result generalizes the multivalued version of some known results see imdad and ali 2007 12 and the references therein also the same result generalizes theorem 2 8 liu et al 2005 4 as application we prove a coincidence point theorem for hybrid nonself maps in product spaces

tracking analysis of the sign algorithm in nonstationary environments a tracking analysis of the adaptive filters equipped with the sign algorithm and operating in nonstationary environments is presented under the assumption that the nonstationary can be modeled using a random disturbance it is shown that the long term time average of the mean absolute error is bounded and that there exists an optimal choice of the convergence constant mu which minimizes this quality applying the commonly used independence assumption and under the assumption that the nonstationarity is solely due to the time varying behavior of the optimal coefficients it is shown that the distributions of the successive coefficient misalignment vectors converge to a limiting distribution when the adaptive filter is used in the system identification mode finally under the additional assumption that the signals involved are zero mean and gaussian a set of nonlinear difference equations is derived that characterizes the mean and mean squared behavior of the filter coefficients and the mean squared estimation error during adaptation and tracking results of several experiments that show very good correlation with the theoretical analyses are presented

adaptive nonlinear filters for narrow band interference suppression in spread spectrum cdma systems this paper presents a novel nonlinear filter and parameter estimator for narrow band interference suppression in code division multiple access spread spectrum systems as in the article by rusch and poor 1994 the received sampled signal is modeled as the sum of the spread spectrum signal modeled as a finite state independently identically distributed i i d process here we generalize to a finite state markov chain narrow band interference modeled as a gaussian autoregressive process and observation noise modeled as a zero mean white gaussian process the proposed algorithm combines a recursive hidden markov model hmm estimator kalman filter kf and the recursive expectation maximization algorithm the nonlinear filtering techniques for narrow band interference suppression presented in rusch and poor and our proposed hmm kf algorithm have the same computational cost detailed simulation studies show that the hmm kf algorithm outperforms the filtering techniques in rusch and poor in particular significant improvements in the bit error rate and signal to noise ratio snr enhancement are obtained in low to medium snr furthermore in simulation studies we investigate the effect on the performance of the hmm kf and the approximate conditional mean acm filter in the paper by rusch and poor when the observation noise variance is increased as expected the performance of the hmm kf and acm algorithms worsen with increasing observation noise and number of users however hmm kf significantly outperforms acm in medium to high observation noise

on common fixed point theorems for non self hybrid mappings in convex metric spaces abstract in this paper we introduce the concept of a contractive type non self mappings for a two pair of multi valued and single valued mappings in metric spaces and prove some results on coincidence and common fixed points in complete convex metric spaces our theorems generalize and improve the theorems of imdad and khan m imdad l khan some common fixed point theorems for a family of mappings in metrically convex spaces nonlinear anal theor 67 9 2007 2717 2726 m imdad l khan fixed point theorems for a family of hybrid pairs of mappings in metrically convex spaces fixed point theory appl 2005 3 2005 281 294 and of assad n a assad fixed point theorems for set valued transformations on compact sets boll un math ital 4 1973 1 7 and several others theorems to accomplish that we shall use slightly improved version of methods of proofs usually used in proving fixed point theorems for non self mappings an example is constructed to show that our results are genuine generalizations of the above mentioned results

convergence analysis of self adaptive equalizers a theoretical analysis of self adaptive equalization for data transmission is carried out starting from known convergence results for the corresponding trained adaptive filter the development relies on a suitable ergodicity model for the sequence of observations at the output of the transmission channel thanks to the boundedness of the decision function used for data recovery it can be proved that the algorithm is bounded strong convergence results can be reached when a perfect noiseless equalizer exists the algorithm will converge to it if the eye pattern is initially open otherwise convergence may take place towards certain other stationary points of the algorithm for which domains of attraction have been defined some of them will result in a poor error rate the case of a noisy channel exhibits limit points for the algorithm that differ from those of the classical trained algorithm the stronger the noise the greater the difference is one of the principal results of this study is the proof of the stability of the usual decision feedback algorithms once the learning period is over

mizoguchi takahashi s type fixed point theorem recently eldred a a eldred j anuradha p veeramani on equivalence of generalized multi valued contactions and nadler s fixed point theorem j math anal appl 2007 doi 10 1016 j jmaa 2007 01 087 claimed that nadler s s b nadler jr multivalued contraction mappings pacific j math 30 1969 475 488 fixed point theorem is equivalent to mizoguchi takahashi s n mizoguchi w takahashi fixed point theorems for multivalued mappings on complete metric space j math anal appl 141 1989 177 188 fixed point theorem very recently suzuki t suzuki mizoguchi takahashi s fixed point theorem is a real generalization of nadler s j math anal appl 2007 doi 10 1016 j jmaa 2007 08 022 produced an example to disprove their claim and showed that mizoguchi takahashi s fixed point theorem is a real generalization of nadler s fixed point theorem we refine generalize mizoguchi takahashi s fixed point theorem our result improves a recent result by klim and wadowski d klim d wardowski fixed point theorems for set valued contractions in complete metric spaces j math anal appl 334 1 2007 132 139 and extends hicks and rhoades t l hicks b e rhoades a banach type fixed point theorem math japonica 24 1979 327 330 fixed point theorem to multivalued maps

stochastic approximation with averaging of the iterates optimal asymptotic rate of convergence for general processes consider the stochastic approximation algorithm x n 1 x n a n g x n xi n in an important paper polyak and juditsky siam j control optim 30 1992 pp 838 855 showed that loosely speaking if the coefficients a n go to zero slower than o 1 n then the averaged sequence sum nolimits i 1 n x i n converged to its limit at an optimum rate for any coefficient sequence the conditions were rather special and direct constructions were used here a rather simple proof is given that results of this type are generic to stochastic approximation and essentially hold any time that the classical asymptotic normality of the normalized and centered iterates holds considerable intuitive insight is provided into the procedure simulations have well borne out the importance of the method

blind adaptive multiuser detection the decorrelating detector and the linear minimum mean square error mmse detector are known to be effective strategies to counter the presence of multiuser interference in code division multiple access channels in particular those multiuser detectors provide optimum near far resistance when training data sequences are available the mmse multiuser detector can be implemented adaptively without knowledge of signature waveforms or received amplitudes this paper introduces an adaptive multiuser detector which converges for any initialization to the mmse detector without requiring training sequences this blind multiuser detector requires no more knowledge than does the conventional single user receiver the desired user s signature waveform and its timing the proposed blind multiuser detector is made robust with respect to imprecise knowledge of the received signature waveform of the user of interest

some common fixed point theorems for weakly compatible mappings abstract jungck s g jungck compatible mappings and common fixed points int j math math sci 9 1986 771 779 notion of compatible mappings is further extended and used to prove some common fixed point theorems for weakly compatible non self mappings in complete convex metric spaces we improve on the method of proof used by rhoades b e rhoades a fixed point theorem for non self set valued mappings int j math math sci 20 1997 9 12 and ahmed and rhoades a ahmed b e rhoades some common fixed point theorems for compatible mappings indian j pure appl math 32 2001 1247 1254 and obtain generalization of some known results in particular a theorem by rhoades b e rhoades a fixed point theorem for non self set valued mappings int j math math sci 20 1997 9 12 is generalized and improved

multi valued nonlinear contraction mappings abstract two concepts of nonlinear contractions for multi valued mappings in complete metric spaces are introduced and three fixed point theorems are proved presented theorems are generalizations of very recent fixed point theorems due to klim and wardowski d klim d wardowski fixed point theorems for set valued contractions in complete metric spaces j math anal appl 334 2007 132 139 and feng and liu y feng s liu fixed point theorems for multi valued contractive mappings and multi valued caristi type mappings j math anal appl 317 2006 103 112 as well as a fixed point theorem of mizoguchi and takahashi n mizoguchi w takahash fixed point theorems for multi valued mappings on complete metric spaces j math anal appl 141 1989 177 188 and several others an example is given to show that presented results are genuine generalizations our results are also some contribution to an open problem raised by reich s reich fixed points of contractive functions boll unione mat ital 5 1972 26 42 s reich some fixed point problems atti acad naz lincei 57 1974 194 198 s reich some problems and results in fixed point theory contemp math 21 1983 179 187

iterate averaging sign algorithms for adaptive filtering with applications to blind multiuser detection motivated by the developments on iterate averaging of recursive stochastic approximation algorithms and asymptotic analysis of sign error algorithms for adaptive filtering this work develops two stage sign algorithms for adaptive filtering the proposed algorithms are based on constructions of a sequence of estimates using large step sizes followed by iterate averaging our main effort is devoted to improving the performance of the algorithms by establishing asymptotic normality of a suitably scaled sequence of the estimation errors the asymptotic covariance is calculated and shown to be the smallest possible hence the asymptotic efficiency or asymptotic optimality is obtained then variants of the algorithm including sign regressor procedures and constant step algorithms are studied the minimal window width of averaging is also dealt with finally iterate averaging algorithms for blind multiuser detection in direct sequence code division multiple access ds cdma systems are proposed and developed and numerical examples are examined

asymptotic almost sure efficiency of averaged stochastic algorithms first we define the notion of almost sure efficiency for a decreasing stepsize stochastic algorithm and then we show that the averaging method which gives asymptotically efficient algorithms also gives asymptotically almost surely efficient algorithms moreover we prove that the averaged algorithm also satisfies a law of the iterated logarithm as well as an almost sure central limit theorem

coincidences and fixed points of nonself hybrid contractions ahmad and imdad and ahmed and khan have studied coincidences and fixed points of nonself hybrid contractions on metrically convex spaces however most of their main theorems contain errors and admit counterexamples in this paper we rectify these results and obtain coincidence and fixed point theorems on a more general setting

fixed point theorems for multi valued contractions in complete metric spaces abstract in this paper the concept of a contraction for multi valued mappings in a metric space is introduced and the existence theorems for fixed points of such contractions in a complete metric space are proved presented results generalize and improve the recent results of y feng s liu y feng s liu fixed point theorems for multi valued contractive mappings and multi valued caristi type mappings j math anal appl 317 2006 103 112 d klim d wardowski d klim d wardowski fixed point theorems for set valued contractions in complete metric spaces j math anal appl 334 2007 132 139 and several others the method used in the proofs of our results is new and is simpler than methods used in the corresponding papers two examples are given to show that our results are genuine generalization of the results of feng and liu and klim and wardowski

pulse wave propagation in a model human arterial network assessment of 1 d visco elastic simulations against in vitro measurements a numerical model based on the nonlinear one dimensional 1 d equations of pressure and flow wave propagation in conduit arteries is tested against a well defined experimental 1 1 replica of the human arterial tree the tree consists of 37 silicone branches representing the largest central systemic arteries in the human including the aorta carotid arteries and arteries that perfuse the upper and lower limbs and the main abdominal organs the set up is mounted horizontally and connected to a pulsatile pump delivering a periodic output similar to the aortic flow terminal branches end in simple resistance models consisting of stiff capillary tubes leading to an overflow reservoir that reflects a constant venous pressure the parameters required by the numerical algorithm are directly measured in the in vitro set up and no data fitting is involved comparison of experimental and numerical pressure and flow waveforms shows the ability of the 1 d time domain formulation to capture the main features of pulse wave propagation measured throughout the system test as a consequence of the simple resistive boundary conditions used to reduce the uncertainty of the parameters involved in the simulation the experimental set up generates waveforms at terminal branches with additional non physiological oscillations the frequencies of these oscillations are well captured by the 1 d model even though amplitudes are overestimated adding energy losses in bifurcations and including fluid inertia and compliance to the purely resistive terminal models does not reduce the underdamped effect suggesting that wall visco elasticity might play an important role in the experimental results nevertheless average relative root mean square errors between simulations and experimental waveforms are smaller than 4 for pressure and 19 for the flow at all 70 locations studied

common fixed point theorems for non self mappings in metric spaces of hyperbolic type in this paper the concept of a pair of non linear contraction type mappings in a metric space of hyperbolic type is introduced and the conditions guaranteeing the existence of a common fixed point for such non linear contractions are established presented results generalize and improve some of the known results an example is constructed to show that our theorems are genuine generalizations of the main theorems of assad ciric khan et al rhoades and imdad and kumar one of the possible applications of our results is also presented

equivalent theorems of the convergence between proximal type algorithms abstract the main aim of this work is to give the equivalence of the convergence between proximal type algorithms our convergence analysis covers rockafellar type proximal point algorithm with a weak contraction for finding zeros of accretive operators as well as browder and halpern type iterations and viscosity approximation methods for finding fixed points of nonexpansive type mappings in banach spaces we also provide simple proofs of some results of wong sahu and yao n c wong d r sahu j c yao solving variational inequalities involving nonexpansive type mappings nonlinear anal 69 12 2008 4732 4753

fixed point theorems for generalized contractive multi valued maps in n mizoguchi w takahashi fixed point theorems for multi valued mappings on complete metric spaces j math anal appl 141 1989 177 188 the authors gave a positive answer to the conjecture of s reich concerning the existence of fixed points of multi valued mappings that satisfy certain contractive conditions in this paper we establish some results for multi valued mappings that satisfy a generalized contractive condition in a way that it contains mizoguchi s result as one of its special cases in addition our results not only improve the results of kiran and kamran q kiran t kamran nadler s type principle with high order of convergence nonlinear anal tma 69 2008 4106 4120 and some results of agarwal et al r p agarwal jewgeni dshalalow donal o regan fixed point and homotopy results for generalized contractive maps of reich type appl anal 82 4 2003 329 350 but also provide the high order of convergence of the iterative scheme and error bounds as an application of our results we obtain an existence result for a class of integral inclusions

on equivalence of generalized multi valued contractions and nadler s fixed point theorem we consider two generalizations of nadler s theorem one proved by mizoguchi and takahashi in response to the reich conjecture and another theorem proved by kaneko we show that due to the additional conditions of these theorems the given multi valued map reduces to a multi valued contraction map we prove this result by showing that the orbit of the multi valued map is bounded under the contractive conditions of the two generalizations

common fixed points in best approximation for banach operator pairs with ciric type i contractions abstract the common fixed point theorems similar to those of ciric lj b ciric on a common fixed point theorem of a gregus type publ inst math beograd n s 49 1991 174 178 lj b ciric on diviccaro fisher and sessa open questions arch math brno 29 1993 145 152 lj b ciric on a generalization of gregus fixed point theorem czechoslovak math j 50 2000 449 458 fisher and sessa b fisher s sessa on a fixed point theorem of gregus internat j math math sci 9 1986 23 28 jungck g jungck on a fixed point theorem of fisher and sessa internat j math math sci 13 1990 497 500 and mukherjee and verma r n mukherjee v verma a note on fixed point theorem of gregus math japon 33 1988 745 749 are proved for a banach operator pair as applications common fixed point and approximation results for banach operator pair satisfying ciric type contractive conditions are obtained without the assumption of linearity or affinity of either t or i our results unify and generalize various known results to a more general class of noncommuting mappings

pair of non self mappings and common fixed points we study quasi contraction type non self mappings on takahashi convex metric spaces and common fixed point theorems for a pair of maps results generalizing and unifying fixed point theorems of imdad and kumar das and naik jungck ciric ume khan and pathak and ciric are established

multi valued non self mappings on convex metric spaces abstract in this paper we prove common fixed point theorems for a pair of multi valued non self mappings in metrically convex metric spaces our results generalize and extend both theorems of itoh comment math univ carolin 18 1977 247 and khan pacific j math 95 1981 337 the theorem of assad boll un math ital 4 1973 1 the theorem of rhoades comment math univ carolin 37 1996 401 and the main theorem of assad and kirk pacific j math 43 1972 535

application of 1d blood flow models of the human arterial network to differential pressure predictions a new application of 1d models of the human arterial network is proposed we take advantage of the sensitivity of the models predictions for the pressure profiles within the main aorta to key model parameter values we propose to use the patterns in the predicted differences from a base case as a way to infer to the most probable changes in the parameter values we demonstrate this application using an impedance model that we have recently developed johnson 2010 the input model parameters are all physiologically related such as the geometric dimensions of large arteries various blood properties vessel elasticity etc and can therefore be patient specific as a base case nominal values from the literature are used the necessary information to characterize the smaller arteries arterioles and capillaries is taken from a physical scaling model west 1999 model predictions for the effective impedance of the human arterial system closely agree with experimental data available in the literature the predictions for the pressure wave development along the main arteries are also found in qualitative agreement with previous published results the model has been further validated against our own measured pressure data in the carotid and radial arteries obtained from healthy individuals upon changes in the value of key model parameters we show that the differences seen in the pressure profiles correspond to qualitatively different patterns for different parameters this suggests the possibility of using the model in interpreting multiple pressure data of healthy diseased individuals

convergence theorems for nonexpansive semigroups in cat 0 spaces abstract let c be a convex and compact subset of a cat 0 space x in this paper we consider the following iterative scheme for a one parameter nonexpansive semigroup t t t 0 on c x 1 c x n 1 t t n x n 1 x n where 0 1 and t n 0 and we prove that under certain conditions x n converges to a common fixed point of the semigroup t t t 0

adaptive filtering with binary reinforcement recently there has been increased interest in high speed adaptive filtering where the usual stochastic gradient or least mean square lms algorithm is replaced with the simpler algorithm where adaptation is guided only by the polarity of the error signal in this paper the convergence of this binary reinforcement br algorithm is proved under the usual independence assumption and the surprising observation is made that unlike the lms algorithm convergence occurs for any positive value of the step size parameter while the stochastic gradient algorithm attempts to minimize a mean square error cost function the binary reinforcement algorithm in fact attempts to minimize a mean absolute error cost function it is proved for the binary reinforcement algorithm that the tap weight vector converges in distribution to a random vector that is suitably concentrated about the optimal value based on a least mean absolute error cost function for a sufficiently small step size the expected cost of the asymptotic weight vector can be made as close as desired to thc minimum cost attain ed by the optimum weight vector

splitting methods based on algebraic factorization for fluid structure interaction we discuss in this paper the numerical approximation of fluid structure interaction fsi problems dealing with strong added mass effect we propose new semi implicit algorithms based on inexact block lu factorization of the linear system obtained after the space time discretization and linearization of the fsi problem as a result the fluid velocity is computed separately from the coupled pressure structure velocity system at each iteration reducing the computational cost we investigate explicit implicit decomposition through algebraic splitting techniques originally designed for the fsi problem this approach leads to two different families of methods which extend to fsi the algebraic pressure correction method and the yosida method two schemes that were previously adopted for pure fluid problems furthermore we have considered the inexact factorization of the fluid structure system as a preconditioner the numerical properties of these methods have been tested on a model problem representing a blood vessel system

best simultaneous approximations asymptotically nonexpansive mappings and variational inequalities in banach spaces abstract the existence of common fixed points is established for three mappings where t is either generalized f g nonexpansive or asymptotically f g nonexpansive on a nonempty subset of a banach space as applications the invariant best simultaneous approximation results are proved and the existence of solution of variational inequalities is obtained our results unify and substantially improve several recent results existing in the current literature

some common fixed point theorems for non self hybrid contractions abstract some results on the common fixed point for a pair of multivalued and single valued non self mappings in metrically convex metric spaces are obtained our work extends some of the known results due to assad and kirk hadzic and gajic itoh khan and many others

phase spaces and periodic solutions of set functional dynamic equations with infinite delay abstract very recently a new theory known as set dynamic equations on time scales has been built in this paper a phase space is built for set functional dynamic equations with infinite delay on time scales and sufficient criteria are established for the existence of periodic solutions of such equations which generalize and incorporate as special cases some known results for set differential equations and for set difference equations when the time scale is the real number set or the integer set respectively moreover for differential inclusions and difference inclusions if the variable under consideration is a single valued mapping our results show that one can unify the study of some continuous or discrete problems in the sense of set dynamic equations on general time scales

averaged stochastic gradient algorithms for adaptive blind multiuser detection in ds cdma systems in this paper we present a blind adaptive gradient bag algorithm for code aided suppression of multiple access interference mai and narrow band interference nbi in direct sequence code division multiple access ds cdma systems this bag algorithm is based on the concept of accelerating the convergence of a stochastic gradient algorithm by averaging this ingenious concept of averaging was invented by polyak and juditsky 1992 this paper examines its application to blind multiuser detection and nbi suppression in ds cdma systems we prove that bag has identical convergence and tracking properties to recursive least squares lms but has a computational cost similar to the least mean squares lms algorithm i e an order of magnitude lower computational cost than rls simulations are used to compare our averaged gradient algorithm with the blind lms and lms schemes

iterative construction of fixed points of nonself mappings in banach spaces the purpose of this paper is to study the iterative methods for constructing fixed points of nonself mappings in banach spaces the concept of the class of asymptotically q g weakly contractive nonself mappings is introduced and a new iterative algorithm for finding fixed points of this class of mappings is studied several strong convergence results on this algorithm are established under different conditions

weak convergence and asymptotic properties of adaptive filters with constant gains the basic adaptive filtering algorithm x n 1 epsilon x n epsilon epsilon y n y n x n epsilon psi n is analyzed using the theory of weak convergence apart from some very special cases the analysis is hard when done for each fixed epsilon 0 but the weak convergence techniques are set up to provide much information for small epsilon the relevant facts from the theory are given define x epsilon cdot by x epsilon t x n epsilon on n epsilon n epsilon epsilon then weak distributional convergence of x epsilon cdot and of x epsilon cdot t epsilon is proved under very weak assumptions where t epsilon rightarrow infty as epsilon rightarrow 0 the normalized errors x n epsilon theta sqrt epsilon are analyzed where theta is a stable point for the mean algorithm the asymptotic properties of a projection algorithm are developed where the x n epsilon are truncated at each iteration if they fall outside of a given set

non self mappings satisfying non linear contractive condition with applications abstract the concept of non self mappings satisfying a new non linear contractive type condition is introduced and coincidence and common fixed point theorems in metric spaces of hyperbolic type are proved presented theorems generalize and improve recent theorems of imdad and kumar m imdad s kumar rhoades type fixed point theorems for a pair of nonself mappings comput math appl 46 2003 919 927 and several others theorems one example is constructed to show that our theorems are genuine generalizations of the above mentioned results of imdad and kumar and several others

joint identification of plant rational models and noise distribution functions using binary valued observations system identification of plants with binary valued output observations is of importance in understanding modeling capability and limitations for systems with limited sensor information establishing relationships between communication resource limitations and identification complexity and studying sensor networks this paper resolves two issues arising in such system identification problems first regression structures for identifying a rational model contain non smooth nonlinearities leading to a difficult nonlinear filtering problem by introducing a two step identification procedure that employs periodic signals empirical measures and identifiability features rational models can be identified without resorting to complicated nonlinear searching algorithms second by formulating a joint identification problem we are able to accommodate scenarios in which noise distribution functions are unknown convergence of parameter estimates is established recursive algorithms for joint identification and their key properties are further developed

invariant approximation for cat 0 spaces abstract in this paper for commuting pair consisting of a single valued mapping t and multi valued mapping t which are satisfying suzuki s condition c in a c a t 0 space x we look for a solution to the problem of existence of z k x such that z t z t z where k is a bounded closed convex subset of x our results improve and extend some recent results of shahzad and markin 2008 12

strong diffusion approximations for recursive stochastic algorithms lai and robbins 1978 prove strong diffusion approximations for the robbins monro stochastic approximation algorithm we show that similar strong approximations hold for stochastic algorithms at the level of generality proposed in the monograph of benveniste metivier and priouret 1990 wherein algorithms with generally discontinous right hand sides driven by conditionally markovian data are considered the relevance of our result is demonstrated on an estimation algorithm with a discontinuous right hand side which is used in data communication the technique of adaptive delta modulation used in digital communication is considered

spreading code optimization and adaptation in cdma via discrete stochastic approximation the aim of this paper is to develop discrete stochastic approximation algorithms that adaptively optimize the spreading codes of users in a code division multiple access cdma system employing linear minimum mean square error mmse receivers the proposed algorithms are able to adapt to slowly time varying channel conditions one of the most important properties of the algorithms is their self learning capability they spend most of the computational effort at the global optimizer of the objective function tracking analysis of the adaptive algorithms is presented together with mean square convergence an adaptive step size algorithm is also presented for optimally adjusting the step size based on the observations numerical examples illustrating the performance of the algorithms in multipath fading channels show substantial improvement over heuristic algorithms