In this paper the application of parametric programming to CNC machining is discussed. As one of the less frequently utilized features of CNC machines, parametric programming has the potential to increase the efficien...
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In this paper the application of parametric programming to CNC machining is discussed. As one of the less frequently utilized features of CNC machines, parametric programming has the potential to increase the efficiency of CNC operations. This feature is particularly beneficial to companies with group technology manufacturing where parts with similar design or operational requirements are processed within a machine cell. Using two case studies, the capabilities of parametric programming for CNC machines are illustrated. (C) 1998 Elsevier Science Ltd. All rights reserved.
This paper proposes a general procedure to construct the membership functions of the performance measures in queueing systems when the interarrival time and service time are fuzzy numbers. The basic idea is to reduce ...
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This paper proposes a general procedure to construct the membership functions of the performance measures in queueing systems when the interarrival time and service time are fuzzy numbers. The basic idea is to reduce a fuzzy queue into a family of crisp queues by applying the alpha-cut approach. A pair of parametric programs is formulated to describe th at family of crisp queues, via which the membership functions of the performance measures are derived. To demonstrate the validity of the proposed procedure, four fuzzy queues, namely, M/F/1, F/M/1, F/F/1, and FM/FM/1, are exemplified. The discussion of this paper is confined to systems with one and two fuzzy variables: nevertheless, the procedure can be extended to systems with more than two fuzzy variables. (C) 1999 Elsevier Science B.V. All rights reserved.
Conducting model selection on data gives rise to selection uncertainty which, when ignored, invalidates subsequent classical inference which assumes that the model is given before the analysis and is in all its aspect...
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Conducting model selection on data gives rise to selection uncertainty which, when ignored, invalidates subsequent classical inference which assumes that the model is given before the analysis and is in all its aspects correctly specified. In selective inference, the randomness induced by selection is dealt with by conditioning confidence intervals and p-values on the subspace of the data which leads to the same model selection as the observed data. The main challenge is the characterization of this selection event. We develop an algorithm for conducting approximate post-selection inference for parameters after model selection events which may not be characterizable as polyhedrons. We apply this on the adaptive lasso, the adaptive elastic net and the group lasso. We conduct experiments on simulated and real data, illustrating that the algorithm can both successfully control the false-positive rate and is computationally efficient.
Fitting a machine learning model often requires presetting parameter values (hyperparameters) that control how an algorithm learns from the data. Selecting an optimal model that minimizes error and generalizes well to...
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Fitting a machine learning model often requires presetting parameter values (hyperparameters) that control how an algorithm learns from the data. Selecting an optimal model that minimizes error and generalizes well to unseen data becomes a problem of tuning or optimizing these hyperparameters. Typical hyperparameter optimization strategies involve discretizing the parameter space and implementing an iterative search procedure to approximate the optimal hyperparameter and model selection through cross-validation. Instead, for machine learning algorithms that are formulated as linear or quadratic programming (LP/QP) models, an exact solution to the hyperparameter optimization problem is obtainable through parametric programming without any approximation. First, the hyperparameter optimization problem is posed more naturally as a bilevel optimization. Second, using parametric programming theory, the bilevel optimization is reformulated into a single level problem. Exact solutions to the hyperparameter optimization problem for LASSO regression and LP L-1-norm support vector machine (SVM) are derived and validated on example data. (C) 2020 Elsevier Ltd. All rights reserved.
The minimum norm Lagrange multiplier, as a type of informative Lagrange multiplier, is proposed to replace the classical shadow price when the later fails to exist. This kind of multiplier expresses the rate of cost i...
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The minimum norm Lagrange multiplier, as a type of informative Lagrange multiplier, is proposed to replace the classical shadow price when the later fails to exist. This kind of multiplier expresses the rate of cost improvement when the right-hand side of the constraints are permitted to slightly violated. However, the minimum norm Lagrange multiplier may fail to be informative in fully parametric optimization problems. In this paper, we extend the classical constraint violation condition to a general formulation, which captures the characteristics of the problem structure of nonlinear parametric programming models. Based on the generalized constraint violation condition, we provide sufficient conditions for the minimum norm Lagrange multiplier to be informative. Furthermore, we propose a kind of penalty function method to derive the informative Lagrange multiplier in fully parametric programming models, which means that the perturbations are not only on the right-hand side of the constraints. Finally, we use examples to support our theoretic results.
In this paper the possibility of the identification of a complete fuzzy decision (not only the maximizing alternative) in fuzzy linear programming by use of the parametric programming technique is presented. Also, it ...
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In this paper the possibility of the identification of a complete fuzzy decision (not only the maximizing alternative) in fuzzy linear programming by use of the parametric programming technique is presented. Also, it is shown that this fact can be useful in the Zimmermann approach to multiple objective linear programming. The presented remarks are illustrated by some numerical examples.
Although work has been carried out on parametric programming on CNC centres, there have been few papers which focus on error compensation. parametric programming for error compensation is presented in this paper on th...
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Although work has been carried out on parametric programming on CNC centres, there have been few papers which focus on error compensation. parametric programming for error compensation is presented in this paper on the basis of a simple model of machining system deflections induced by the radial cutting force in CNC turning operations. The resulting errors are introduced as compensation values to the conventional tool movements along the programmed tool path. This can result in a complex tool path. parametric programming is applied to handle this complexity for error compensation.
This article presents a new framework, based on parametric programming, that unifies the solution of the various flexibility analysis and design optimization problems that arise for linear, convex, and nonconvex, nonl...
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This article presents a new framework, based on parametric programming, that unifies the solution of the various flexibility analysis and design optimization problems that arise for linear, convex, and nonconvex, nonlinear systems with deterministic or stochastic uncertainties. This approach generalizes earlier work by Bansal et al. It allows (1) explicit information to be obtained on the dependence of the flexibility characteristics of a nonlinear system on the values of the uncertain parameters and design variables;(2) the critical uncertain parameter points to be identified a priori so that design optimization problems that do not require iteration between a design step and a flexibility analysis step can be solved;and (3) the nonlinearity to be removed from the optimization subproblems that need to be solved when evaluating the flexibility of systems with stochastic uncertainties.
Data envelopment analysis (DEA) is a methodology for measuring the relative efficiency of decision making units (DMUs) consuming the same types of inputs and producing the same types of outputs. This paper studies the...
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Data envelopment analysis (DEA) is a methodology for measuring the relative efficiency of decision making units (DMUs) consuming the same types of inputs and producing the same types of outputs. This paper studies the DEA models with type-2 data variations. In order to deal with the existed type-2 fuzziness, we propose the mean reduction methods for type-2 fuzzy variables. Based on the mean reductions of the type-2 fuzzy inputs and outputs, we formulate a new class of fuzzy generalized expectation DEA models. When the inputs and outputs are mutually independent type-2 triangular fuzzy variables, we discuss the equivalent parametric forms for the constraints and the generalized expectation objective, where the parameters characterize the degree of uncertainty of the type-2 fuzzy coefficients so that the information cannot be lost via our reduction method. For any given parameters, the proposed model becomes nonlinear programming, which can be solved by standard optimization solvers. To illustrate the modeling idea and the efficiency of the proposed DEA model, we provide one numerical example. (C) 2011 Elsevier Ltd. All rights reserved.
In this paper a method is presented for deriving the explicit robust model-based optimal control law for constrained linear dynamic systems. The controller is derived off-line via parametric programming before any act...
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In this paper a method is presented for deriving the explicit robust model-based optimal control law for constrained linear dynamic systems. The controller is derived off-line via parametric programming before any actual process implementation takes place. The proposed control scheme guarantees feasible operation in the presence of bounded input uncertainties by (i) explicitly incorporating in the controller design stage a set of feasibility constraints and (ii) minimizing the nominal performance, or the expectation of the performance over the uncertainty space. An extension of the method to problems involving target point tracking in the presence of persistent disturbances is also discussed. The general concept is illustrated with two examples. (C) 2003 Elsevier Ltd. All rights reserved.
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