Non-Gaussian colored input signal and censored observation are encountered frequently in many practical applications of adaptive signal processing. Conventional adaptive algorithms will face convergence performance de...
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Non-Gaussian colored input signal and censored observation are encountered frequently in many practical applications of adaptive signal processing. Conventional adaptive algorithms will face convergence performance degradation in such cases. To address the issue, the affine projection algorithm for censored regression (CR-APA) is proposed in this brief. The censored thresholds and the variance of the background noise are regarded as the prior knowledge to compensate for the bias caused by censored observation. By theoretical analysis, the range of the step size is derived to guarantee the stabilization of the CR-APA. Besides, the method of evolving projection order is employed to improve the convergence performance of the CR-APA. Computer simulations in system identification and echo cancellation applications are performed to demonstrate the better convergence performance of the proposed algorithms in censored data processing over competing algorithms, and to verify the improvement of the CR-APA by the method of evolving projection order. The proposed CR-APA and CR-EAPA can be used in engineering applications to make up for the hardware.
Various algorithms have been proposed for determining the routing paths designed to minimize the average overall message time delay in message-switched networks. In this paper we describe the application of the gradie...
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Various algorithms have been proposed for determining the routing paths designed to minimize the average overall message time delay in message-switched networks. In this paper we describe the application of the gradient projection algorithm to this problem. This algorithm is a gradient-type search procedure designed to handle constrained optimization problems, into which category the routing problem falls. Calculations of the computational complexity of this algorithm indicate that it is particularly well-suited to networks with a limited number of commodities or source-destination pairs. The algorithm is applied to a representative group of distributed-type networks, of varying complexity. Execution times for this algorithm are compared with those obtained using the flow deviation routing algorithm. These agree roughly with the results of the computational requirement calculations; i.e., this algorithm generally requires less execution time for networks with a relatively small number of commodities than does the flow deviation method. (The actual running time depends significantly on the choice of the initial flows or routing paths, however.) For those networks in which all network nodes may be expected to communicate with all other nodes, however, the flow deviation method would be expected to be superior.
This paper presents a projection-based approach for solving conic feasibility problems. To find a point in the intersection of a cone and an affine subspace, we simply project a point onto this intersection. This proj...
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This paper presents a projection-based approach for solving conic feasibility problems. To find a point in the intersection of a cone and an affine subspace, we simply project a point onto this intersection. This projection is computed by dual algorithms operating a sequence of projections onto the cone and generalizing the alternating projection method. We release an easy-to-use Matlab package implementing an elementary dual-projection algorithm. Numerical experiments show that, for solving some semidefinite feasibility problems, the package is competitive with sophisticated conic programming software. We also provide a particular treatment for semidefinite feasibility problems modelling polynomial sum-of-squares decomposition problems.
Adaptive deadbeat control is considered for the deterministic linear plant without any persistent excitation assumption imposed. The upper bound on the rate of convergence is provided for the control algorithm that us...
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Adaptive deadbeat control is considered for the deterministic linear plant without any persistent excitation assumption imposed. The upper bound on the rate of convergence is provided for the control algorithm that uses the projection identification algorithm. On the other hand, we show that convergence is delayed if the ''regularized'' identification algorithm is used. It is shown that arbitrarily large delays can precede an overshoot under certain choices of initial conditions. An estimate is also provided for the amplitude of the peak.
We consider the convex feasibility problem, which is to determine a point in the intersection of a finite number of closed convex sets. It was shown in the past literature a so-called generalized acceleration method c...
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We consider the convex feasibility problem, which is to determine a point in the intersection of a finite number of closed convex sets. It was shown in the past literature a so-called generalized acceleration method converges to a feasible point in the intersection of all the sets, assuming the intersection set has a nonempty interior. In this letter, we establish the same convergence result without any assumption on the interior of the feasible set. In particular, we devise a randomized accelerated projection algorithm and prove its linear convergence rate when all the convex sets are half-spaces in a finite-dimensional Euclidean space. Numerical experiments comparing the generalized acceleration method with the classic cyclic projection methods are presented, which justify the fast convergence rate and the out-performance of the proposed algorithm.
The LMS algorithm is widely employed in adaptive systems due to its robustness, simplicity, and reasonable performance. However, it is well known that this algorithm suffers from a slow convergence speed when dealing ...
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The LMS algorithm is widely employed in adaptive systems due to its robustness, simplicity, and reasonable performance. However, it is well known that this algorithm suffers from a slow convergence speed when dealing with colored reference signals. Numerous variants and alternative algorithms have been proposed to address this issue, though all of them entail an increase in computational cost. Among the proposed alternatives, the affine projection algorithm stands out. This algorithm has the peculiarity of starting from $N$ data vectors of the reference signal. It transforms these vectors into as many data vectors suitably normalized in energy and mutually orthogonal. In this work, we propose a version of the LMS algorithm that, similar to the affine projection algorithm, starts from $N$ data vectors of the reference signal but corrects them by using only a scalar factor that functions as a convergence step. Our goal is to align the behavior of this algorithm with the behavior of the affine projection algorithm without significantly increasing the computational cost of the LMS.
The use of cone beam scanners raises the problem of three dimensional reconstruction from divergent projections. After a survey on bidimensional analytical reconstruction methods we examine their application to the 3D...
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The use of cone beam scanners raises the problem of three dimensional reconstruction from divergent projections. After a survey on bidimensional analytical reconstruction methods we examine their application to the 3D problem. Finally, it is shown that the back projection theorem can be generalized to cone beam projections. This allows to state a new inversion formula suitable for both the 4 π parallel and divergent geometries. It leads to the generalization of the "rho-filtered back projection " algorithm which is outlined.
We propose a new projection algorithm for generalized variational inequality with multivalued mapping. Our method is proven to be globally convergent to a solution of the variational inequality problem, provided that ...
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We propose a new projection algorithm for generalized variational inequality with multivalued mapping. Our method is proven to be globally convergent to a solution of the variational inequality problem, provided that the multivalued mapping is continuous and pseudomonotone with nonempty compact convex values. Preliminary computational experience is also reported.
In this paper, we propose a derivative-free algorithm for solving large-scale nonlinear systems of monotone equations. This algorithm incorporates a pivotal step inspired by double projection methods, which is further...
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In this paper, we propose a derivative-free algorithm for solving large-scale nonlinear systems of monotone equations. This algorithm incorporates a pivotal step inspired by double projection methods, which is further refined through an inertial approach to approximate the solution more effectively. The global convergence of the new algorithm is investigated under some mild conditions. The results of some numerical tests, along with their performance profiles, demonstrate the algorithm's efficacy.
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