Browsing by Subject "optimization"

Now showing 1 - 20 of 61

Access status: Open Access ,
A Comparison between Integer Order and Non-integer Order Controllers Applied to a Water Levelling System
(Wydawnictwa AGH, 2014) Kania, Bartosz; Dziwiński, Tomasz; Bauer, Waldemar; Zagórowska, Marta; Baranowski, Jerzy
W artykule porównano odpowiedzi układów z dwoma regulatorami: typu PI oraz typu PI niecałkowitego rzędu. W celu syntezy regulatorów, stworzono i opisano model numeryczny, a następnie wykorzystano metodę symulowanego wyżarzania do znalezienia optymalnych parametrów. Tak zaprojektowane regulatory zostały przetestowane na rzeczywistym zbiorniku. W rezultacie okazało się, że zastosowanie regulatora niecałkowitoliczbowego rzędu do układu całkującego nie jest konieczne. Obliczenia były prowadzone w środowisko Matlab/Simulink.
Access status: Open Access ,
A dedicated sensitivity analysis and optimization application for industrial processes
(Wydawnictwa AGH, 2021) Myczkowska, Kamila; Szeliga, Danuta
The paper describes the architecture and the use case of the developed Modelbox system for sensitivity analysis (SA), uncertainty analysis (UA) and the subsequent optimization of industrial processes. The proposed solution addresses the most common practical and technical problems encountered by researchers and engineers when performing sensitivity analysis. It combines the functions from the numerical toolbox with a simulation management system. Maintaining usability and a good user experience while managing complex investigations of time-consuming industrial process simulations is a very important feature of the system. Several improvements were introduced to optimize the computation time of analysis/modelling tasks, including the automatization of distributed calculations, persistent, transparent caching of simulation data and duration estimations from collected statistics. The system has the ability to perform remote, parallel, asynchronous computations of both analytic algorithms and numerical simulations. The system is dynamically scalable horizontally by using serverless computing endpoints and thus it can be easily adapted to the user's current needs in a flexible way. Modelbox provides web-based access to analysis/modelling tasks from sampling, SA/UA, optimization to metamodelling. It is extended with numerous interactive visualization components for effective results control. In addition, to access data from the completed analysis, the system supports convergence tracking for SA estimates and intermediate optimization results. The process of controlled cooling of rails was considered as a case study. The formulated optimization task was to find a combination of process parameters that ensures a minimum volume fraction of bainite along with required interlamellar spacing and optimal homogeneity of hardness. Different sensitivity analysis methods were used to evaluate the significance of all variables with respect to their influence on the model output.
Access status: Open Access ,
A loss function for box-constrained inverses problems
(2008) Yoneda, Kiyoshi
A loss function is proposed for solving box-constrained inverse problems. Given causality mechanisms between inputs and outputs as smooth functions, an inverse problem demands to adjust the input levels to make the output levels as close as possible to the target values; box-constrained refers to the requirement that all outcome levels remain within their respective permissible intervals. A feasible solution is assumed known, which is often the status quo. We propose a loss function which avoids activation of the constraints. A practical advantage of this approach over the usual weighted least squares is that permissible outcome intervals are required in place of target importance weights, facilitating data acquisition. The proposed loss function is smooth and strictly convex with closed-form gradient and Hessian, permitting Newton family algorithms. The author has not been able to locate in the literature the Gibbs distribution corresponding to the loss function. The loss function is closely related to the <i>generalized matching law</i> in psychology.
Access status: Open Access ,
A transfer line balancing problem by heuristic methods: industrial case studies
(2008) Guschinskaya, Olga; Dolgui, Alexandre
The paper deals with the problem of optimal configuration of a type of transfer lines which are equipped with transfer machines. Such machines perform operations with standard modular spindle heads which are activated sequentially. All operations assigned to the same spindle head (block of operations) are executed simultaneously by a set of tools fixed at the spindle head. The quantity of machines and spindle heads used to produce a part with the given productivity rate defines the final cost of the transfer line which must be minimized. To minimize this cost, a combinatorial problem of operations assignment to blocks and machines must be solved. The solution must provide a desired productivity (cycle time), it must also satisfy precedence and compatibility constraints. In this paper, we suggest improved versions of FSIC heuristic algorithm in order to help line designers to solve real-scale industrial problems. Results of computational experiments obtained for industrial cases are presented.
Access status: Open Access ,
A utility function to solve approximate linear equations for decision making
(2013) Yoneda, Kiyoshi; Celaschi, Walter
Suppose there are a number of decision variables linearly related to a set of outcome variables. There are at least as many outcome variables as the number of decision variables since all decisions are outcomes by themselves. The quality of outcome is evaluated by a utility function. Given desired values for all outcome variables, decision making reduces to »solving« the system of linear equations with respect to the decision variables; the solution being defined as decision variable values such that maximize the utility function. This paper proposes a family of additively separable utility functions which can be defined by setting four intuitive parameters for each outcome variable: the desired value of the outcome, the lower and the upper limits of its admissible interval, and its importance weight. The utility function takes a nonnegative value within the admissible domain and negative outside; permits gradient methods for maximization, is designed to have a small dynamic range for numerical computation. Small examples are presented to illustrate the proposed method.
Access status: Restricted ,
Algorytmy genetyczne + struktury danych = programy ewolucyjne
(Wydawnictwa Naukowo-Techniczne, 2003) Michalewicz, Zbigniew
Access status: Open Access ,
An example to illustrate several aspects of optimization theory in Managerial Economics
(Wydawnictwa AGH, 2021) Lahiri, Somdeb
We provide a single example that illustrates all aspects of linear, integer and dynamic programming, including such concepts such as value of perfect and imperfect information. Such problems, though extremely plausible and realistic are hardly ever discussed in managerial economics.
Access status: Open Access ,
An inverse backward problem for degenerate two-dimensional parabolic equation
(Wydawnictwa AGH, 2020) Atifi, Khalid; Essoufi, El-Hassan; Khouiti, Bouchra
This paper deals with the determination of an initial condition in the degenerate two-dimensional parabolic equation $\partial_{t}u-\mathrm{div}\left(a(x,y)I_2\nabla u\right)=f,\quad (x,y)\in\Omega,\; t\in(0,T),$ where $\Omega$ is an open, bounded subset of $\mathbb{R}^2$, $a \in C^1(\bar{\Omega})$ with $a\geqslant 0$ everywhere, and $f\in L^{2}(\Omega \times (0,T))$, with initial and boundary conditions $u(x,y,0)=u_0(x,y), \quad u\mid_{\partial\Omega}=0,$ from final observations. This inverse problem is formulated as a minimization problem using the output least squares approach with the Tikhonov regularization. To show the convergence of the descent method, we prove the Lipschitz continuity of the gradient of the Tikhonov functional. Also we present some numerical experiments to show the performance and stability of the proposed approach.
Access status: Open Access ,
An optimization model for managing compressors in salt cavern gas storage
(2013) Stopa, Jerzy; Mrzygłód, Rafał
The article presents issues related to technical and economic optimization of filling underground gas storage in salt cavern (CUGS) on the example of Mogilno. Operation practice suggests that the first step is to inject the caverns with a high convergence, then with smaller and at the end caverns with the smallest convergence. In the withdraw process, the situation is reversed. On the other hand, the gas injection into the deepest caverns requires more compressor power. Optimization that takes into account only the speed of storage caverns convergence is not ideal. While injecting gas into storage caverns, compressors typically use about 1–3% of the transported gas, depending on the management of compressors operation. Taking into account the amount of gas supplied to the CUGS Mogilno, the cost of fuel gas that is used can be significant. In the liberalized gas market an underground gas storage operator will have to account carefully and buy fuel gas at market prices. These facts raise an important question: how to manage the operation, in a free gas market in the most efficient way which affects the profitability service storage provision in underground gas storage in salt caverns. This paper presents the optimization model, developed by the authors, that minimizes the consumption of fuel gas, while preventing overdependence loss of underground salt caverns volume, during the gas injecting process into storage caverns.
Access status: Restricted ,
Analiza danych w poszukiwaniu zmian cen produktów na portalach aukcyjnych
(Data obrony: 2017-09-18) Kowal, Agnieszka
Wydział Elektrotechniki, Automatyki, Informatyki i Inżynierii Biomedycznej
Access status: Open Access ,
Analiza i ustalenie parametrów eksploatacyjnych dla odwiertów wód mineralnych w zależności od wielkości wykładnika gazowego
(2008) Duliński, Władysław; Ropa, Czesława Ewa
Mineral waters produced by wells are diversified in their mineral composition, energy conditions, water yield and gas exponential. Bearing in mind the management of mineral water and the co-produced carbon dioxide, an example of exploitation from a medium gas exponential well was analyzed in the paper. Values of pressure drop of the fluid running in the near-wellbore area, as well as calculations of pressure drop in the string at varying production rates, are calculated in the paper. The optimum diameters of the string for maintaining self-production are defined.
Access status: Restricted ,
Analiza wydajności i optymalizacja przetwarzania chmur punktów w bazach danych przestrzennych
(Data obrony: 2017-07-10) Chrószcz, Aleksandra
Wydział Geologii, Geofizyki i Ochrony Środowiska
Niniejsza praca rozwija tematykę składowania oraz przetwarzania danych przestrzennych wraz z ich optymalizacją. Głównym celem było wskazanie najefektywniejszego systemu do zarządzania bazami danych, który w najszybszy sposób przetwarza i analizuje dane w formie chmury punktów, a następnie wybór metod optymalizacji. Spośród kilku baz danych (relacyjnych i nierelacyjnych) skupiono się na relacyjnej bazie PostgreSQL. Powodem tego wyboru była szeroka gama dedykowanych narzędzi wspierających pracę z danymi w postaci chmury punktów oraz wydajność bazy w przeprowadzonych testach. Eksperymentalne sprawdzenie bazy nierelacyjnej dowiodło, że zachowuje się ona wydajnie przy niewielu typach dokumentów. Dodatkowo na szybkość wykonywania zapytań miał wpływ rodzaj dysku, gdzie technologia SDD pokazała wyższość nad standardowym dyskiem HDD.
Access status: Open Access ,
Ant algorithm for AP-N aimed at optimization of complex systems
(2010) Mikulik, Jerzy; Zajdel, Mirosław
Assignment Problem (AP), which is well known combinatorial problem, has been studied extensively in the course of many operational and technical researches. It has been shown to be NP-hard for three or more dimensions and a few non-deterministic methods have been proposed to solve it. This paper pays attention on new heuristic search method for the n-dimensional assignment problem, based on swarm intelligence and comparing results with those obtained by other scientists. It indicates possible direction of solutions of problems and presents a way of behaviour using ant algorithm for multidimensional optimization complex systems. Results of researches in the form of computational simulations outcomes are presented.
Access status: Restricted ,
Aplikacja do określania litologii ośrodka na podstawie pomiarów geofizyki wiertniczej przy użyciu metod optymalizacyjnych z ograniczeniami
(Data obrony: 2014-09-11) Barbacki, Jan
Wydział Geologii, Geofizyki i Ochrony Środowiska
Correct determining the lithology of a rock formation is one of the main goals of geophysical interpretation. The application for analysis of borehole geophysical measurements encoded in Log ASCII Standard format files was created. Appropriate choice of geophysical parameters allows to determine the percentage volume of elements in the rock formation, as well as the porosity and the water saturation of the formation. For the precisest solution a conjugate gradient method with Monte Carlo starting points was used.
Access status: Open Access ,
Application for quantifying the lithology of a rock formation using geophysical well logs and constrained optimization methods
(2015) Barbacki, Jan
Correct determining the lithology of a rock formation is one of the main goals of geophysical interpretation. The application for analysis of borehole geophysical measurements encoded in Log ASCII Standard format files was created. Appropriate choice of geophysical parameters allows to determine the percentage volume of elements in the rock formation, as well as the porosity and the water saturation of the formation. For the precisest solution a conjugate gradient method with Monte Carlo starting points was used.
Access status: Open Access ,
Building blocks propagation in quantum-inspired genetic algorithm
(Wydawnictwa AGH, 2010) Nowotniak, Robert; Kucharski, Jacek
This paper presents an analysis of building blocks propagation in Quantum-Inspired Genetic Algorithm, which belongs to a new class of metaheuristics drawing their inspiration from both biological evolution and unitary evolution of quantum systems. The expected number of quantum chromosomes matching a schema has been analyzed and a random variable corresponding to this issue has been introduced. The results have been compared with Simple Genetic Algorithm. Also, it has been presented how selected binary quantum chromosomes cover a domain of one-dimensional fitness function.
Access status: Open Access ,
Computational intelligence based design of biomaterials
(Wydawnictwa AGH, 2022) Vinoth, Arulraj; Datta, Shubhabrata
This paper presents an overview of the applications of computational intelligence techniques, viz. artificial neural networks, fuzzy inference systems, and genetic algorithms, for the design of biomaterials with improved performance. These techniques are basically used for developing data-driven models and for optimization. The paper introduces the domain of biomaterials and how they can be designed using computational intelligence techniques. Then a brief description of the tools is made, followed by the applications of the tools in various domains of biomaterials. The applications range in all classes of materials ranging from alloys to composites. There are examples of applications for the surface treatment of biomaterials, materials for drug delivery systems, materials for scaffolds and even in implant design. It is found the tools can be effectively used for designing new and improved biomaterials.
Access status: Open Access ,
Concept of production facilities layout in company Alumin, s.r.o. Slovakia
(AGH University of Science and Technology Press, 2011) Straka, Martin
The aim of part of the solution layout processing company is an analysis of the existing system of distribution of production equipment company, identification of material flows and showing the possibility of modifying the layout of production facilities in compliance with capacity, safety and quality requirements for production.
Access status: Open Access ,
Conditional mean embedding and optimal feature selection via positive definite kernels
(Wydawnictwa AGH, 2024) Jørgensen, Palle E.T.; Song, Myung-Sin; Tian, James
Motivated by applications, we consider new operator-theoretic approaches to conditional mean embedding (CME). Our present results combine a spectral analysis-based optimization scheme with the use of kernels, stochastic processes, and constructive learning algorithms. For initially given non-linear data, we consider optimization-based feature selections. This entails the use of convex sets of kernels in a construction o foptimal feature selection via regression algorithms from learning models. Thus, with initial inputs of training data (for a suitable learning algorithm), each choice of a kernel $K$ in turn yields a variety of Hilbert spaces and realizations of features. A novel aspect of our work is the inclusion of a secondary optimization process over a specified convex set of positive definite kernels, resulting in the determination of »optimal« feature representations.
Access status: Open Access ,
Deadhead Minimization Problem in Multi-Depot Public Transport System
(Wydawnictwa AGH, 2021) Szczyrbak, Robert
This paper addresses a vehicle scheduling problem in the public transport system of Krakow, Poland. The primary objective is to develop and evaluate a mathematical model for assigning bus schedules to depots in a way that minimizes non-revenue (deadhead) kilometers. The proposed model, referred to as the Deadhead Minimization Problem in Multi-Depot Public Transport System (DMPMDPTS), seeks to reduce the total distance that is traveled by vehicles from their home depots to the starting points of their first scheduled routes and from the final terminals back to their depots. The model assumes fixed-route structures and known deadhead distances between terminals. Real-world data that was based on the Krakow Municipal Transport (KKM) was used to validate and verify the model. The optimization model was implemented in AMPL and solved using the GLPK Integer Optimizer (v4.43). Computational experiments were conducted across multiple cases that differed in their constraints and parameters in order to assess the model’s flexibility and performance. In all of the cases, optimal solutions were obtained in brief computation times. Compared to the existing operational schedules, the model consistently reduced deadhead kilometers. Case 1 achieved improvements without altering the numbers of vehicles per depot, while Case 2 led to further reductions of the costs of redistributing vehicles among depots, resulting in a less-balanced load structure. These findings demonstrated the model’s potential for supporting decision-making in depot allocation within public transport operations.