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Tytuł:
Perturbation algorithm for a minimax regret minimum spanning tree problem
Autorzy:
Makuchowski, M.
Powiązania:
https://bibliotekanauki.pl/articles/406452.pdf
Data publikacji:
2014
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
discrete optimization
robust optimization
perturbation algorithms
minimax regret
Opis:
The problem of finding a robust spanning tree has been analysed. The problem consists of determining a minimum spanning tree of a graph with uncertain edge costs. We should determine a spanning tree that minimizes the difference in costs between the tree selected and the optimal tree. While doing this, all possible realizations of the edge costs should be taken into account. This issue belongs to the class of NP-hard problems. In this paper, an algorithm based on the cost perturbation method and adapted to the analysed problem has been proposed. The paper also contains the results of numerical experiments testing the effectiveness of the proposed algorithm and compares it with algorithms known in the literature. The research is based on a large number of various test examples taken from the literature.
Źródło:
Operations Research and Decisions; 2014, 24, 1; 37-49
2081-8858
2391-6060
Pojawia się w:
Operations Research and Decisions
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Gold rush optimizer : a new population-based metaheuristic algorithm
Autorzy:
Zolf, Kamran
Powiązania:
https://bibliotekanauki.pl/articles/2204102.pdf
Data publikacji:
2023
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
gold rush optimizer
metaheuristic
global optimization
population-based algorithm
Opis:
Today’s world is characterised by competitive environments, optimal resource utilization, and cost reduction, which has resulted in an increasing role for metaheuristic algorithms in solving complex modern problems. As a result, this paper introduces the gold rush optimizer (GRO), a population-based metaheuristic algorithm that simulates how gold-seekers prospected for gold during the Gold Rush Era using three key concepts of gold prospecting: migration, collaboration, and panning. The GRO algorithm is compared to twelve well-known metaheuristic algorithms on 29 benchmark test cases to assess the proposed approach’s performance. For scientific evaluation, the Friedman and Wilcoxon signed-rank tests are used. In addition to these test cases, the GRO algorithm is evaluated using three real-world engineering problems. The results indicated that the proposed algorithm was more capable than other algorithms in proposing qualitative and competitive solutions.
Źródło:
Operations Research and Decisions; 2023, 33, 1; 113--150
2081-8858
2391-6060
Pojawia się w:
Operations Research and Decisions
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A new and fast approximation algorithm for vertex cover using a maximum independent set (VCUMI)
Autorzy:
Khan, I.
Riaz, N.
Powiązania:
https://bibliotekanauki.pl/articles/406436.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
non-deterministic polynomial
vertex cover
independent set
benchmark
error ratio
Opis:
The importance of non-deterministic polynomial (NP) problems in real world scenarios has compelled researchers to consider simple ways of finding approximate solutions to these problems in polynomial time. Minimum vertex cover is an NP complete problem, where the objective is to cover all the edges in a graph with the minimal number of vertices possible. The maximal independent set and maximal clique problems also belong to the same class. An important property that we have analyzed while considering various approaches to find approximate solutions to the minimum vertex cover problem (MVC) is that solving MVC directly can result in a bigger error ratio. We propose a new approximation algorithm for the minimum vertex cover problem called vertex cover using a maximum independent set (VCUMI). This algorithm works by removing the nodes of a maximum independent set until the graph is an approximate solution of MVC. Based on empirical results, it can be stated that VCUMI outperforms all competing algorithms presented in the literature. Based on all the benchmarks used, VCUMI achieved the worst case error ratio of 1.033, while VSA, MDG and NOVAC-1 gave the worst error ratios of 1.583, 1.107 and 1.04, respectively.
Źródło:
Operations Research and Decisions; 2015, 25, 4; 5-18
2081-8858
2391-6060
Pojawia się w:
Operations Research and Decisions
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Construction of Variable Strength Covering Array for Combinatorial Testing Using a Greedy Approach to Genetic Algorithm
Autorzy:
Bansal, P
Sabharwal, S
Mittal, N
Arora, S
Powiązania:
https://bibliotekanauki.pl/articles/384137.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
combinatorial testing
variable strength covering array
genetic algorithm
greedy approach
Opis:
The limitation of time and budget usually prohibits exhaustive testing of interactions between components in a component based software system. Combinatorial testing is a software testing technique that can be used to detect faults in a component based software system caused by the interactions of components in an effective and efficient way. Most of the research in the field of combinatorial testing till now has focused on the construction of optimal covering array (CA) of fixed strength t which covers all t-way interactions among components. The size of CA increases with the increase in strength of testing t, which further increases the cost of testing. However, not all components require higher strength interaction testing. Hence, in a system with k components a technique is required to construct CA of fixed strength t which covers all t-way interactions among k components and all ti-way (where ti > t) interactions between a subset of k components. This is achieved using the variable strength covering array (VSCA). In this paper we propose a greedy based genetic algorithm (GA) to generate optimal VSCA. Experiments are conducted on several benchmark configurations to evaluate the effectiveness of the proposed approach.
Źródło:
e-Informatica Software Engineering Journal; 2015, 9, 1; 87-105
1897-7979
Pojawia się w:
e-Informatica Software Engineering Journal
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Segmentation algorithm of coal slurry foam with double-point directional extension based on the improved FCM clustering algorithm
Autorzy:
Wu, ZiHao
Huang, XianWu
Shang, HaiLi
Zhao, YuHong
Powiązania:
https://bibliotekanauki.pl/articles/2200332.pdf
Data publikacji:
2023
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
flotation
slime foam segmentation
FCM
clustering algorithm
double-point directional extension
segmentation effect judgment standard
Opis:
In flotation production, the visual surface information of the flotation foam reflects the flotation effects, which are closely related to the flotation conditions and directly reflect the degree of mineralization of the foam layer. In this study, it was proposed a novel and efficient segmentation algorithm to extract the edge information of slime bubbles, as the boundaries are typically blurred and difficult to segment, due to the slime bubbles sticking to each other in the slime flotation foam image. First, the improved clustering algorithm and image morphology operation were used to extract the edges of the foam spots. Second, the image morphological operations were used as a starting point to look around the foam edge points. The pseudo-edge points were then removed using a region and spatial removal algorithm. Finally, the foam edges were extracted using the double-point directed expansion algorithm. A new criterion was proposed for segmentation effect determination based on the particularity of the segmented object. The feasibility and effectiveness of the foam segmentation method were investigated by comparative experiments. The experimental results showed that the proposed algorithm could obtain the foam surface properties more accurately and provide effective guidance for flotation production.
Źródło:
Physicochemical Problems of Mineral Processing; 2023, 59, 1; art. no. 158850
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Assumptions concerning a software supporting the primary intramural teaching subsidy distribution at the Wroclaw University of Science and Technology faculty
Autorzy:
Szczurowski, L.
Rekuć, Witold
Powiązania:
https://bibliotekanauki.pl/articles/406385.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
university budget
decision
financing of teaching
subsidy distribution algorithm
software architecture
budżet uniwersytet
decyzja
finansowanie nauczania
algorytm dystrybucji subwencji
architektura oprogramowania
Opis:
Assumptions concerning a software supporting the primary intramural teaching subsidy distribution at a Wroclaw University of Science and Technology faculty compatible with a distribution algorithm are described. Strategic goal, main problems, roles and operational tasks of this support are identified. Selected business processes and system use cases are analyzed. Concepts as well as introductory system architecture accommodating the necessity of the subsidy distribution algorithm updating are elaborated. Proposals important from the point of view of the dean’s financial assistant preparing analytical data concerning subsidy distribution for the faculty provisional as well as final budged version are formulated.
Źródło:
Operations Research and Decisions; 2019, 29, 2; 89-101
2081-8858
2391-6060
Pojawia się w:
Operations Research and Decisions
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Image encryption combining discrete fractional angular transform with Arnold transform in image bit planes
Autorzy:
Zhou, Z.
Yu, J.
Liao, Q.
Gong, L.
Powiązania:
https://bibliotekanauki.pl/articles/173704.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
Arnold transform
bit plane
discrete fractional angular transform
image encryption algorithm
Opis:
A new image encryption algorithm by using a discrete fractional angular transform and Arnold transform in image bit planes is investigated. In the image encryption algorithm, the original image is encrypted by the Arnold transform in image bit planes firstly, and then the resulting image is encrypted by the discrete fractional angular transform further. The key of the image encryption algorithm includes the parameters of the Arnold transform and the order of the discrete fractional angular transform. It is shown that the proposed image encryption algorithm is of high security and strong enough to counteract some conventional image attack manners.
Źródło:
Optica Applicata; 2018, 48, 2; 225-236
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical analysis of tailing dam with calibration based on genetic algorithm and geotechnical monitoring data
Autorzy:
Grosel, Szczepan
Powiązania:
https://bibliotekanauki.pl/articles/1845160.pdf
Data publikacji:
2021
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
soil parameters
optimization
slope stability
genetic algorithm
observational method
monitoring
Opis:
The article presents a method of calibration of material parameters of a numerical model based on a genetic algorithm, which allows to match the calculation results with measurements from the geotechnical monitoring network. This method can be used for the maintenance of objects managed by the observation method, which requires continuous monitoring and design alterations. The correctness of the calibration method has been verified on the basis of artificially generated data in order to eliminate inaccuracies related to approximations resulting from the numerical model generation. Using the example of the tailing dam model the quality of prediction of the selected measurement points was verified. Moreover, changes of factor of safety values, which is an important indicator for designing this type of construction, were analyzed. It was decided to exploit the case of dam of reservoir, which is under continuous construction, that is dam height is increasing constantly, because in this situation the use of the observation method is relevant.
Źródło:
Studia Geotechnica et Mechanica; 2021, 43, 1; 34-47
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An approximation algorithm for multi-unit auctions: numerical and subject experiments
Autorzy:
Takahashi, S.
Izunaga, Y.
Watanabe, N.
Powiązania:
https://bibliotekanauki.pl/articles/406625.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
multi-unit auctions
approximation algorithm
experiment
algorytm aproksymacyjny
eksperyment
Opis:
In multi-unit auctions for a single item, the Vickrey–Clarke–Groves mechanism (VCG) attains allocative efficiency but suffers from its computational complexity. Takahashi and Shigeno thus proposed a greedy based approximation algorithm (GBA). In a subject experiment there was truly a difference in efficiency rate but no significant difference in seller’s revenue between GBA and VCG. It is not clear in theory whether each bidder will submit his or her true unit valuations in GBA. We show, however, that in a subject experiment there was no significant difference in the number of bids that obey “almost” truth-telling between GBA and VCG. As for individual bidding behavior, GBA and VCG show a sharp contrast when a human bidder competes against machine bidders; underbidding was observed in GBA, while overbidding was observed in VCG. Some results in a numerical experiment are also provided prior to reporting those observations.
Źródło:
Operations Research and Decisions; 2018, 28, 1; 95-115
2081-8858
2391-6060
Pojawia się w:
Operations Research and Decisions
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Robust dual color images watermarking scheme with hyperchaotic encryption based on quaternion DFrAT and genetic algorithm
Autorzy:
Luo, Hui-Xin
Gong, Li-Hua
Chen, Su-Hua
Powiązania:
https://bibliotekanauki.pl/articles/27310094.pdf
Data publikacji:
2023
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
color image watermarking
hyperchaotic encryption
quaternion discrete fractional angular transform
quaternion singular value decomposition
genetic algorithm
Opis:
A robust dual color images watermarking algorithm is designed based on quaternion discrete fractional angular transform (QDFrAT) and genetic algorithm. To guarantee the watermark security, the original color watermark image is encrypted with a 4D hyperchaotic system. A pure quaternion matrix is acquired by performing the discrete wavelet transform (DWT), the block division and the discrete cosine transform on the original color cover image. The quaternion matrix is operated by the QDFrAT to improve the robustness and the security of the watermarking scheme with the optimal transform angle and the fractional order. Then the singular value matrix is obtained by the quaternion singular value decomposition (QSVD) to further enhance the scheme’s stability. The encryption watermark is also processed by DWT and QSVD. Afterward, the singular value matrix of the encryption watermark is embedded into the singular value matrix of the host image by the optimal scaling factor. Moreover, the values to balance imperceptibility and robustness are optimized with a genetic algorithm. It is shown that the proposed color image watermarking scheme performs well in imperceptibility, security, robustness and embedding capacity.
Źródło:
Optica Applicata; 2023, 53, 2; 261--280
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
DE-XRT coal preparation image overlapping and adhesion particle segmentation method
Autorzy:
He, Lei
Wang, Shuang
Guo, Yongcun
Powiązania:
https://bibliotekanauki.pl/articles/2175443.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
overlap
adhesion
image segmentation
watershed algorithm
DE-XRT
coal
gangue
Opis:
Accurate segmentation of dual-energy X-ray transmission (DE-XRT) coal and gangue image regions are a prerequisite for feature extraction, identification, localization, and separation. A watershed algorithm based on multi-grayscale threshold segmentation (MGTS) is proposed to mark the foreground for the adhesion and overlap of coal and gangue. The grayscale images of foreground objects are segmented using multiple grayscale thresholds, and the number of connected domains is recorded each time. As the gray threshold value decreases, overlapping and adhering objects are gradually separated. The binary image segmented at the grayscale threshold with the most significant number of connected domains is used as a marker region. This marker region is used as the seed point of the watershed algorithm to find the dividing line. The experimental results show that the segmentation accuracy is 91.35%, and the segmentation accuracy of overlapping adhesions of 2, 3, and 4 targets is higher than 90%.
Źródło:
Physicochemical Problems of Mineral Processing; 2022, 58, 6; art. no. 155840
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Locating critical circular and unconstrained failure surface in slope stability analysis with tailored genetic algorithm
Autorzy:
Pasik, T.
van der Meij, R.
Powiązania:
https://bibliotekanauki.pl/articles/178579.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
genetic algorithm
Spencers method
slope stability
critical failure surface
uplift phenomenon
Opis:
This article presents an efficient search method for representative circular and unconstrained slip surfaces with the use of the tailored genetic algorithm. Searches for unconstrained slip planes with rigid equilibrium methods are yet uncommon in engineering practice, and little publications regarding truly free slip planes exist. The proposed method presents an effective procedure being the result of the right combination of initial population type, selection, crossover and mutation method. The procedure needs little computational effort to find the optimum, unconstrained slip plane. The methodology described in this paper is implemented using Mathematica. The implementation, along with further explanations, is fully presented so the results can be reproduced. Sample slope stability calculations are performed for four cases, along with a detailed result interpretation. Two cases are compared with analyses described in earlier publications. The remaining two are practical cases of slope stability analyses of dikes in Netherlands. These four cases show the benefits of analyzing slope stability with a rigid equilibrium method combined with a genetic algorithm. The paper concludes by describing possibilities and limitations of using the genetic algorithm in the context of the slope stability problem.
Źródło:
Studia Geotechnica et Mechanica; 2017, 39, 4; 87-98
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An exoskeleton arm optimal configuration determination using inverse kinematics and genetic algorithm
Autorzy:
Głowiński, Sebastian
Błażejewski, Andrzej
Powiązania:
https://bibliotekanauki.pl/articles/306968.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
algorytm genetyczny
kinematyka odwrotna
egzoszkielet
ramię
arm exoskeleton
genetic algorithm
inverse kinematics
Opis:
This paper deals with the kinematic modelling of an arm exoskeleton used for human rehabilitation. The biomechanics of the arm was studied and the 9 Degrees of Freedom model was obtained. The particular (optimal) exoskeleton arm configuration is needed, depending on patient abilities and possibility or other users activity. Methods: The model of upper arm was obtained by using Denavit–Hartenberg notation. The exoskeleton human arm was modelled in MathWorks package. The multicriteria optimization procedure was formulated to plan the motion of trajectory. In order to find the problem solution, an artificial intelligence method was used. Results: The optimal solutions were found applying a genetic algorithm. Two variants of motion with and the visualization of the change of joints angles were shown. By the use of genetic algorithms, movement trajectory with the Pareto-optimum solutions has been presented as well. Creating a utopia point, it was possible to select only one solution from Pareto-optimum results. Conclusions: The obtained results demonstrate the efficiency of the proposed approach that can be utilized to analyse the kinematics and dynamics of exoskeletons using the dedicated design process. Genetic algorithm solution could be implemented to command actuators, especially in the case of multi-criteria problems. Moreover, the effectiveness of this method should be evaluated in the future by real experiments.
Źródło:
Acta of Bioengineering and Biomechanics; 2019, 21, 1; 45-53
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Predykcyjny algorytm sterowania napędem z silnikiem indukcyjnym zasilanym z 4-tranzystorowego falownika napięcia
Predictive control algorithm for induction motor drive fed by 4-switch voltage inverter
Autorzy:
Sobański, P.
Orłowska-Kowalska, T.
Powiązania:
https://bibliotekanauki.pl/articles/1817836.pdf
Data publikacji:
2014
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
napęd elektryczny 0
silnik indukcyjny
falownik napięcia
sterowanie odporne na uszkodzenia
sterowanie predykcyjne
Opis:
In this paper a finite-state predictive torque and flux control of an induction motor drive fed by four-switch voltage inverter has been presented. The proposed method is dedicated to fault-tolerant control systems that are capable to operate under transistor faults of a three phase voltage inverter. Thanks to a weighting factor adaptation of a term related to an error between DC-link voltages in a cost function of the predictive algorithm, a high quality drive performance is achieved. In the article a tuning procedure of a predictive controller has been developed and proved by simulations.
Źródło:
Prace Naukowe Instytutu Maszyn, Napędów i Pomiarów Elektrycznych Politechniki Wrocławskiej. Studia i Materiały; 2014, 70, 34; 59--75
1733-0718
Pojawia się w:
Prace Naukowe Instytutu Maszyn, Napędów i Pomiarów Elektrycznych Politechniki Wrocławskiej. Studia i Materiały
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spectrally tunable light source based on light-emitting diodes for custom lighting solutions
Autorzy:
Burgos-Fernandez, F. J.
Vilaseca, M.
Perales, E.
Herrera-Ramirez, J. A.
Martinez-Verdu, F. M.
Pujol, J.
Powiązania:
https://bibliotekanauki.pl/articles/173803.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
solid state lighting
light-emitting diodes
CIE standard illuminants
minimization algorithm
customized lighting design
radiometry
Opis:
This study describes a novel spectral LED-based tunable light source used for customized lighting solutions, especially for the reconstruction of CIE (Commission Internationale de l'Eclairage) standard illuminants. The light source comprises 31 spectral bands ranging from 400 to 700 nm, an integrating cube and a control board with a 16-bit resolution. A minimization algorithm to calculate the weighting values for each channel was applied to reproduce illuminants with precision. The differences in spectral fitting and colorimetric parameters showed that the reconstructed spectra were comparable to the standard, especially for the D65, D50, A and E illuminants. Accurate results were also obtained for illuminants with narrow peaks such as fluorescents (F2 and F11) and a high-pressure sodium lamp (HP1). In conclusion, the developed spectral LED-based light source and the minimization algorithm are able to reproduce any CIE standard illuminants with a high spectral and colorimetric accuracy able to advance available custom lighting systems useful in the industry and other fields such as museum lighting.
Źródło:
Optica Applicata; 2016, 46, 1; 117-129
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł

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