Discrete manufacturing process design optimization curt be difficult, due to the large number of manufacturing process design sequences and associated input parameter setting combinations that exist. Generalized hill ...
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Discrete manufacturing process design optimization curt be difficult, due to the large number of manufacturing process design sequences and associated input parameter setting combinations that exist. Generalized hill climbing algorithms have been introduced to address such manufacturing design problems. Initial results with generalized hill climbing algorithms required the manufacturing process design sequence to be fixed with the generalized hill climbing algorithm used to identify optimal input parameter settings. This paper introduces a new neighborhood function that allows generalized hill climbing algorithms to be used to also identify the optimal discrete manufacturing process design sequence among a set of valid design sequences. The neighborhood function uses a switch function for all the input parameters, hence allows the generalized hill climbing algorithm to simultaneously optimize over both the design sequences and the inputs parameters. Computational results are reported with art integrated blade rotor discrete manufacturing process design problem under study at the Materials Process Design. Branch of the Air Force Research Laboratory, Wright Patterson Air Force Base (Dayton, Ohio, USA). [S1050-0472(00)01002-3].
In this work, we study the possibility of defending against data-poisoning attacks while training a shallow neural network in a regression setup. We focus on doing supervised learning with realizable labels for a clas...
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In this work, we study the possibility of defending against data-poisoning attacks while training a shallow neural network in a regression setup. We focus on doing supervised learning with realizable labels for a class of depth-2 finite-width neural networks, which includes single-filter convolutional networks. In this class of networks, we attempt to learn the true network weights generating the labels in the presence of a malicious oracle doing stochastic, bounded and additive adversarial distortions on the true labels, during training. For the gradient-free stochastic algorithm that we construct, we prove worstcase near-optimal trade-offs among the magnitude of the adversarial attack, the weight approximation accuracy, and the confidence achieved by the proposed algorithm. As our algorithm uses minibatching, we analyze how the mini-batch size affects convergence. We also show how to utilize the scaling of the outer layer weights to counter data-poisoning attacks on true labels depending on the probability of attack. Lastly, we give experimental evidence demonstrating how our algorithm outperforms stochastic gradient descent under different input data distributions, including instances of heavy-tailed distributions.(c) 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://***/licenses/by/4.0/).
In this paper we prove the large deviation principle for a class of random walks with state-dependent noise. This type of model has important applications in queueing and communication theory and in the area of stocha...
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In this paper we prove the large deviation principle for a class of random walks with state-dependent noise. This type of model has important applications in queueing and communication theory and in the area of stochastic approximation.
In this paper, a novel attempt is made to incorporate the two effective algorithm strate-gies, where BBO has a strong exploration and Salp Swarm Algorithm (SSA) is used for exploitation of the search space. The propos...
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In this paper, a novel attempt is made to incorporate the two effective algorithm strate-gies, where BBO has a strong exploration and Salp Swarm Algorithm (SSA) is used for exploitation of the search space. The proposed algorithm is tested on IEEE CEC 2014 and statistical, conver-gence graphs are given. The proposed algorithm is also applied to 10 real life problems and com-pared with its counterpart algorithm. Results obtained by above experiments have demonstrated the outperformance of the hybrid version of BBO over other algorithms. (c) 2023 THE AUTHORS. Published by Elsevier BV on behalf of Faculty of Engineering, Alexandria University. This is an open access article under the CC BY-NC-ND license (http://***/ licenses/by-nc-nd/4.0/).
This article introduces a new global optimization procedure called LARES. LARES is based on the concept of an artificial chemical process (ACP), a new paradigm which is described in this article. The algorithm's p...
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This article introduces a new global optimization procedure called LARES. LARES is based on the concept of an artificial chemical process (ACP), a new paradigm which is described in this article. The algorithm's performance was studied using a test bed with a wide spectrum of problems including random multi-modal random problem generators, random LSAT problem generators with various degrees of epistasis, and a test bed of real-valued functions with different degrees of multi-modality, discontinuity and flatness. In all cases studied, LARES performed very well in terms of robustness and efficiency.
The paper studies asymptotics of inhomogeneous integral functionals of an ergodic diffusion process under the effect of discretization. Convergence to the corresponding functionals of the invariant distribution is sho...
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The paper studies asymptotics of inhomogeneous integral functionals of an ergodic diffusion process under the effect of discretization. Convergence to the corresponding functionals of the invariant distribution is shown for suitably chosen discretization steps, and the fluctuations are analyzed through central limit theorem and moderate deviation principle. The results will be particularly useful for understanding accuracy of an Euler discretization based numerical scheme for approximating functionals of invariant distribution of an ergodic diffusion. This is an infinite-time horizon problem, and the accuracy of numerical schemes in this context are comparatively much less studied than the ones used for generating approximate trajectories of diffusions over finite time intervals. The potential applications of these results also extend to other areas including mathematical physics, parameter inference of ergodic diffusions and analysis of multiscale dynamical systems with averaging. (C) 2020 Elsevier B.V. All rights reserved.
We illustrate our experience in developing and implementing algorithms for map merging, i.e., the problem of fusing two or more partial maps without common reference frames into one large global map. The partial maps ...
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We illustrate our experience in developing and implementing algorithms for map merging, i.e., the problem of fusing two or more partial maps without common reference frames into one large global map. The partial maps may for example be acquired by multiple robots, or during several runs of a single robot from varying starting positions. Our work deals with low quality maps based on probabilistic grids, motivated by the goal to develop multiple mobile platforms to be used in rescue environments. Several contributions to map merging are presented. First of all, we address map merging using a motion planning algorithm. The merging process can be done by rotating and translating the partial maps until similar regions overlap. Second, a motion planning algorithm is presented which is particular suited for this task. Third, a special metric is presented which guides the motion planning algorithm towards the goal of optimally overlapping partial maps. Results with our approach are presented based on data gathered from real robots developed for the RoboCupRescue real robot league. (c) 2005 Elsevier B.V. All rights reserved.
This paper is a continuation of the first part, where we considered regular arrangements of flexible objects for the unbounded case. The present part deals with a simulated annealing algorithm maximizing the number of...
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This paper is a continuation of the first part, where we considered regular arrangements of flexible objects for the unbounded case. The present part deals with a simulated annealing algorithm maximizing the number of flexible objects in equilibrium placements within rigid boundaries. The forces caused by the boundary are taken into account, i.e., the bounded case of placements is considered. The simulated annealing procedure makes use of the special structure of the underlying configuration space and relationships between deformations of flexible objects and resulting forces. This allows us to obtain tight bounds for the n(3/2).ln(5/2)n and ***(2)n time bounds, respectively, for the computation of equilibrium states by annealing parameters which result in n two different cooling schedules. The deformation/force formula is derived from a physical model of flexible discs and is based on numerical experiments which were performed for different materials and different sizes of objects. The algorithm was first implemented and tested for the unbounded case. The run-time is relatively short, even for large numbers of placed discs. These results are compared to the analytical ones obtained for regular placements in the first part of the paper, and agreement between these two sets of results are observed. Furthermore, several experiments for placements with boundary conditions were carried out and the resulting placements clearly show the effect of the forces from the rigid boundary. The specialized and provably efficient simulated annealing algorithm proposed in this paper is therefore a very effective tool for computing equilibrium states of placements and hence useful for the design of new amorphous polymeric materials and package cushioning systems as mentioned in Part I of this paper.
We study the problem of solving a quadratic system of equations, i.e., recovering a vector signal x is an element of R-n from its magnitude measurements y(i) = ||, i = 1,..., m. We develop a gradient descent algorithm...
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We study the problem of solving a quadratic system of equations, i.e., recovering a vector signal x is an element of R-n from its magnitude measurements y(i) = |< a(i), x(i)>|, i = 1,..., m. We develop a gradient descent algorithm (referred to as RWF for reshaped Wirtinger flow) by minimizing the quadratic loss of the magnitude measurements. Comparing with Wirtinger flow (WF) (Candes et al., 2015), the loss function of RWF is nonconvex and nonsmooth, but better resembles the least-squares loss when the phase information is also available. We show that for random Gaussian measurements, RWF enjoys linear convergence to the true signal as long as the number of measurements is O(n). This improves the sample complexity of WF (O(n log n)), and achieves the same sample complexity as truncated Wirtinger flow (TWF) (Chen and Candes, 2015), but without any sophisticated truncation in the gradient loop. Furthermore, RWF costs less computationally than WF, and runs faster numerically than both WF and TWF. We further develop an incremental (stochastic) version of RWF (IRWF) and connect it with the randomized Kaczmarz method for phase retrieval. We demonstrate that IRWF outperforms existing incremental as well as batch algorithms with experiments.
This paper studies the statistical behavior of an affine combination of the outputs of two least mean-square (LMS) adaptive filters that simultaneously adapt using the same white Gaussian inputs. The purpose of the co...
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This paper studies the statistical behavior of an affine combination of the outputs of two least mean-square (LMS) adaptive filters that simultaneously adapt using the same white Gaussian inputs. The purpose of the combination is to obtain an LMS adaptive filter with fast convergence and small steady-state mean-square deviation (MSD). The linear combination studied is a generalization of the convex combination, in which the combination factor lambda(n) is restricted to the interval (0,1). The viewpoint is taken that each of the two filters produces dependent estimates of the unknown channel. Thus, there exists a sequence of optimal affine combining coefficients which minimizes the mean-square error (MSE). First, the optimal unrealizable affine combiner is studied and provides the best possible performance for this class. Then two new schemes are proposed for practical applications. The mean-square performances are analyzed and validated by Monte Carlo simulations. With proper design, the two practical schemes yield an overall MSD that is usually less than the MSDs of either filter.
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