Wyniki wyszukiwania - Biblioteka Nauki

1

Optimization of overlay computing systems with many – to - many transmissions

100%

Walkowiak K. , Kasprzak A. , Andrusieczko K.

Theoretical and Applied Informatics

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2012

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tom Vol. 24, No. 4

271-291

EN

The problem that this paper investigates, namely, optimization of overlay computing systems, follows naturally from growing need for effective processing and consequently, fast development of various distributed systems. We consider an overlay-based computing system, i.e., a virtual computing system is deployed on the top of an existing physical network (e.g., Internet) providing connectivity between computing nodes. The main motivation behind the overlay concept is simple provision of network functionalities (e.g., diversity, flexibility, manageability) in a relatively cost-effective way as well as regardless of physical and logical structure of underlying networks. The workflow of tasks processed in the computing system assumes that there are many sources of input data and many destinations of output data, i.e., many-to-many transmissions are used in the system. The addressed optimization problem is formulated in the form of an ILP (Integer Linear Programing) model. Since the model is computationally demanding and NPcomplete, besides the branch-and-bound algorithm included in the CPLEX solver, we propose additional cut inequalities. Moreover, we present and test two effective heuristic algorithms: tabu search and greedy. Both methods yield satisfactory results close to optimal.

PL

Zagadnienia dotyczące optymalizacji systemów obliczeń rozproszonych zyskują w ostatnich latach na znaczeniu. Systemy obliczeń rozproszonych rozwijane są w dwóch podstawowych architekturach sieciowych. Po pierwsze, budowane są dedykowane sieci optyczne łączące ośrodki obliczeniowe. Po drugie, wykorzystuje się istniejącą infrastrukturę sieciową (np. Internet) dla budowania systemów pracujących w architekturze nakładkowej (ang. overlay). Ta druga koncepcja zyskuje ostatnio dużą popularność, gdyż umożliwia szybką i tanią realizację systemów obliczeniowych bez potrzeby mocnej współpracy z operatorami sieciowymi. W pracy rozważamy nakładkowy system obliczeniowy umożliwiający transmisje wielu do wielu – dane wejściowe do obliczeń są generowane w wielu źródłach (węzłach sieciowych), następnie po przetworzeniu są przesyłane do wielu odbiorców zainteresowanych wynikami obliczeń. W oparciu o zaproponowaną architekturę systemu, w pracy sformułowano problem optymalizacyjny mający na celu minimalizację kosztów operacyjnych systemu obejmujących koszty obliczeń i koszty przesyłania danych. Model został zapisany jako program całkowitoliczbowy. Z uwagi na fakt, że ten problem należy do klasy problemów NP-zupełnych, zaproponowano dodatkowe odcięcia dla algorytmu podziału i oszacowań oraz dwa efektywne algorytmy heurystyczne. Przeprowadzone eksperymenty obliczeniowe wykazały, że opracowane algorytmy dają wyniki bliskie optymalnym w mniejszym czasie niż algorytm optymalny zawarty w pakiecie CPLEX

2

Concept of using heuristic methods in the optimization of electric power systems

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Gryniewicz-Jaworska M.

ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes

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2016

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tom Vol. 5, No 4

69--72

EN

The dynamic development of information technologies has significantly improved the process of planning and controlling the operation of electrical power systems, nevertheless, we are still looking for methods and solutions which will allow to optimize EPS. The article describes heuristic methods which can be used in electrical power engineering and which will be used to solve OPF (Optimal Power Flow) problems.

3

Effective Design of the Simulated Annealing Algorithm for the Flowshop Problem with Minimum Makespan Criterion

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Hurkała J. , Hurkała A.

Journal of Telecommunications and Information Technology

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2012

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tom nr 2

92-98

EN

In this paper we address the n-job, m-machine flowshop scheduling problem with minimum completion time (makespan) as the performance criterion. We describe an efficient design of the Simulated Annealing algorithm for solving approximately this NP-hard problem. The main difficulty in implementing the algorithm is no apparent analogy for the temperature as a parameter in the flowshop combinatorial problem. Moreover, the quality of solutions is dependent on the choice of cooling scheme, initial temperature, number of iterations, and the temperature decrease rate at each step as the annealing proceeds. We propose how to choose the values of all the aforementioned parameters, as well as the Boltzmann factor for the Metropolis scheme. Three perturbation techniques are tested and their impact on the solutions quality is analyzed. We also compare a heuristic and randomly generated solutions as initial seeds to the annealing optimization process. Computational experiments indicate that the proposed design provides very good results - the quality of solutions of the Simulated Annealing algorithm is favorably compared with two different heuristics.

4

From potatoes to barrows, or there and back again

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Rzepecki S.

Sprawozdania Archeologiczne

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2016

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tom 68

409-419

EN

The dissemination of potato cultivation in the territory of Poland created a necessity for the regular removal of stones from the surface of fields. The structures built with the use of these stones can imitate barrows, for example. This issue was analysed when studying the cemetery of the Pomeranian culture in Nowa Sikorska Huta. The author also addresses the problem in the role that imagination can play when employed for the interpretation of archaeological objects.

5

Multi-objective decision making and search space for the evaluation of production process scheduling

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Witkowski T. , Antczak P. , Antczak A.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2009

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tom Vol. 57, nr 3

195-208

EN

Over the years, various approaches have been proposed in order to solve the multi-objective job-shop scheduling problem -particularly a hard combinatorial optimization problem. The paper presents an evaluation of job shop scheduling problem under multiple objectives (mean flow time, max lateness, mean tardiness, mean weighted tardiness, mean earliness, mean weighted earliness, number of tardy tasks). The formulation of the scheduling problem has been presented as well as the evaluation schedules for various optimality criteria. The paper describes the basic mataheuristics used for optimization schedules and the approaches that use domination method, fuzzy method, and analytic hierarchy process (AHP) for comparing schedules in accordance with multiple objectives. The effectiveness of the algorithms has been tested on several examples and the results have been shown. New search space for evaluation and generation of schedules has been created. The three-dimensional space can be used for the analysis and control of the production processes.

6

On the performance analysis of a heuristic approach dedicated to a multiobjective dynamic routing model

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Craveirinha J. , Martins L. , Climaco J. N. , Jorge L.

Journal of Telecommunications and Information Technology

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2005

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tom nr 3

14-23

EN

In previous works the features and a complete formulation for circuit-switched networks of a multiple objective dynamic routing method (MODR) of periodic state dependent routing type were presented. The aim of the model is to resolve a very complex network bi-objective dynamic routing problem, by recurring to a heuristic for synchronous path selection enabling to obtain a good compromise solution in terms of two network performance measures. In this paper we present a study on the performance of variants of the MODR heuristic of synchronous path selection by using relaxations of the values previously calculated for the two network objective functions. This study permitted the development of an improved version of the initial heuristic. Also a comparison of the analytical values of the network objective functions obtained with selected variants of the initial heuristic with the corresponding results from a known reference method, the real time network routing (RTNR) method, given by a discrete-event simulator for single-service networks, is presented.

7

Dynamika modeli biznesu

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Sus A.

Nauki o Zarządzaniu

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2014

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nr 1(18)

90-99

EN

The article focuses on approximating internal factors of the modern organizations success. Accordingly, the attention has been focused on identifying the key points of concentrating on business models, distinguishing features and their dynamic imperatives as well as the tools which implementation may be helpful in the application of effective business models. The key finding of the considerations is the fact that modern organizations more frequently use solutions in the scope of heuristic methods and techniques for solving problems, including the complications associated with business models functioning.

8

Heuristic methods as a powerful managerial tool for enterprise in times of uncertainty

100%

Mazurkiewicz M.

Kwartalnik Nauk o Przedsiębiorstwie

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2022

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tom 63

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nr 1

57-70

PL

W zarządzaniu przedsiębiorstwem, niepewność należy do atrybutów podejmowanych decyzji menedżerskich. W konkurencyjnych środowiskach, gdzie sukces zależy od wysokiej jakości decyzji, podejmowanie błędnych kroków może doprowadzić do utraty rynku lub nawet przyczynić się do zakończenia działalności. Dlatego tak ważne jest, aby spośród wielu alternatywnych metod wybrać tę, która będzie skuteczna w rozwiązywaniu problemów w prosty i szybki sposób. Heurystyka oferuje rozwiązania, które udowodniają swoją przydatność w niepewnym otoczeniu biznesowym. Celem pracy jest przedstawienie i ocena metod heurystycznych oraz wykazanie ich specyfiki i możliwości zastosowania w naukach o zarządzaniu przedsiębiorstwami w warunkach niepewności. W artykule przybliżono aspekt teoretyczny heurystyk menedżerskich, położono również nacisk na przedstawienie praktycznych przykładów zastosowania heurystyk w przedsiębiorstwach w warunkach niepewności, także w czasie pandemii Covid-19, wyciągnięto wnioski i sformułowano praktyczne rekomendacje.

EN

In managing enterprise, uncertainty belongs to the attributes of the decision making processes. In competitive environments, where success depends on high-quality decisions, taking the wrong steps can lead to loss of market share or even contribute to running out of business. That is why it is important to choose from the many alternatives those methods which will be most effective in solving problems in a simple and quick way, and heuristics offer such a solution, which has proved its usefulness in uncertain business environments. The aim of this study is to present and evaluate heuristic methods and show their specificity and applicability in management science for enterprises in times of uncertainty. In this article, the theoretical aspect of managerial heuristics is presented, and the emphasis is also placed on presenting practical examples of applying heuristics in companies with times of uncertainty, but also in these times of the Covid-19 pandemic. The study also offers conclusions and provides practi al recommendations.

9

Samowiedza heurystyczna wśród ekonomistów

100%

Madej Z.

Ekonomista

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2016

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nr 6

777-798

PL

Celem tego artykułu jest poszukiwanie odpowiedzi na pytanie, jaką samowiedzą heurystyczną dysponują współcześni ekonomiści. Mało wiadomo na ten temat i dlatego autor postanowił go podjąć. Rozważania zostały skoncentrowane na trzech dziedzinach: heurystyce, wiedzy i samowiedzy oraz praktycznych korzyściach płynących z dwóch poprzednich dziedzin. Wyniki poszukiwań pozwalają stwierdzić, że dosłownie pojmowana samowiedza heurystyczna wśród ekonomistów jest raczej skromna. Natomiast wrażliwość heurystyczna, czyli otwartość na nowe wydarzenia, nie budzi zastrzeżeń. Można zatem powiedzieć, że ekonomiści stosują liczne elementy tego, co jest określane pojęciem heurystyki, nie nazywając rzeczy po imieniu. Ich wiedza typu heurystycznego występuje przeważnie jako wiedza niewyrażona, tkwiąca w głowach poszczególnych osób. Jest ona z istoty swojej wiedzą rozproszoną i zindywidualizowaną. Friedrich von Hayek określał taką wiedzę jako tacit knowledge. Nawet w takich warunkach ekonomiści posiadają poważne sukcesy badawcze. Ale są podstawy by sądzić, że uzewnętrznienie heurystycznej tacit knowledge i połączenie jej z istniejącymi zasobami wiedzy wyrażonej w słowach, rysunkach i liczbach może przyczynić się do stworzenia wyodrębnionej heurystyki ekonomicznej i zwiększyć szanse poznawcze całej wiedzy ekonomicznej.

EN

The purpose of this paper is an inquiry on what kind of heuristic self-knowledge is possessed by modern economists. This topic is not very well known, therefore the author decided to tackle it. The study is focused on three fields: heuristics, knowledge and selfknowledge, and practical benefits arising from two former fields. The results of the inquiry indicate that the heuristic self-knowledge among economists, if taken literally, is fairly modest. On the other hand, a heuristic sensibility, or openness to new events and developments, does not raise any objections. It can be thus said that the economists are using multiple elements of what we call heuristics without acknowledging or using that name itself. Their heuristic knowledge most often works as an unexpressed knowledge, rooted in minds of individual persons. It is intrinsically a dispersed, individualized kind of knowledge. Friedrich von Hayek called it tacit knowledge. Even under those circumstances the economists experience significant scientific success. However, there are reasons to believe that externalization of heuristic tacit knowledge, and combining it with existing resources of economic knowledge expressed in words, images and numbers, might contribute to the creation of a separate field of economical heuristics – and expand the cognitive capacity of economic knowledge as a whole.

RU

Автор статьи ищет ответ на вопрос, каково геуристическое самосознание современных экономистов. Этот вопрос мало исследован и поэтому автор решил его рассмотреть. Анализ касался трех областей: геуристики, знания, самосознания и практической пользы, вытекающей из первых двух областей. Исследование позволяет утверждать, что четкое геуристическое самосознание среди экономистов невелико, чего нельзя сказать о геуристической восприимчивости, т.е. готовности принять новые события. Можно утверждать, что экономисты используют многие элементы геуристики, не называя этого термина. Их знания геуристического типа проявляются нечетко, только в головах отдельных людей. Это знание по своей природе рассредоточенное и индивидуализированное. Фридрих фон Хайек называл такое знание tacit knowledge. Экономисты и в этих условиях достигают серьезных научных успехов. Есть основания полагать, что проявление tacit knowledge и соединение его с существующими запасами знаний, выраженных в словах, рисунках и цифрах, может привести к созданию отдельной экономической геуристики и увеличить познавательный потенциал всего экономического знания.

10

A new heuristic algorithm for multicast connections in packet networks

100%

Zwierzykowski P. , Piechowiak M. , Żódź A.

Poznan University of Technology Academic Journals. Electrical Engineering

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2007

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tom No 54

213-220

EN

There have been many heuristic algorithms determining multicast connection trees proposed over the past few years. However, the proposed methods are only approximations of the most favourable solutions and thus, a necessity of finding a better and more suitable algorithm is still topical and up-to-date. The present article aims at presenting the attempts of finding a constrain algorithm that would be more effective than those presented in relevant literature so far.

11

Solving the Rectangular Packing Problem by a New Bottom-Left Placement Method Incorporated with a Multi-Start Local Search

100%

Wetweerapong J. , Remsungnen T.

Foundations of Computing and Decision Sciences

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2010

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tom Vol. 35, No. 2

127-141

EN

This paper presents a new Bottom-Left placement method for the rectangular packing problem. It is a modified version of the Row-Column Search (RCS) placement method for a faster packing. Incorporated with some improvement heuristics and a simple local search (LS), it is found to be quite efficient in solving easy to moderate packing problems. For the difficult packing problems, a multi- start mechanism is added in order to enable the packing process to overcome getting trapped to a local optimal solution. Testing on some well-known packing instances in the literature shows results that are both satisfied and informative.

12

The concept of integrated engineering and business (EB) education system

100%

Charlak M. , Jakubowski M. A.

Advances in Science and Technology. Research Journal

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2013

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tom Vol. 7, nr 20

98--103

EN

In our approach to engineering and business education system an engineer is a man working as creator and user of technical products. We stress that the process of understanding and gaining knowledge of technical reality and creativity of engineers are the essential for EB concept . Next, we describe briefly three perspectives for building the system of innovative product origination as a basis for EB system: 1) designer’s perspective; 2) business perspective. 3) consumer perspective.

13

Heuristics and representational change in two-move matchstick arithmetic tasks

100%

Öllinger M. , Jones G. , Knoblich G.

Advances in Cognitive Psychology

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2006

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tom 2

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nr 4

239-253

EN

Insight problems are problems where the problem solver struggles to find a solution until * aha! * the solution suddenly appears. Two contemporary theories suggest that insight problems are difficult either because problem solvers begin with an incorrect representation of the problem, or that problem solvers apply inappropriate heuristics to the problem. The relative contributions of representational change and inappropriate heuristics on the process of insight problem solving was studied with a task that required the problem solver to move two matchsticks in order to transform an incorrect arithmetic statement into a correct one. Problem solvers (N = 120) worked on two different types of two-move matchstick arithmetic problems that both varied with respect to the effectiveness of heuristics and to the degree of a necessary representational change of the problem representation. A strong influence of representational change on solution rates was found whereas the influence of heuristics had minimal effects on solution rates. That is, the difficulty of insight problems within the two-move matchstick arithmetic domain is governed by the degree of representational change re-quired. A model is presented that details representational change as the necessary condition for ensuring that appropriate heuristics can be applied on the proper problem representation.

14

Heurystyki w prognozowaniu w przedsiębiorstwie

100%

Dittmann I.

Econometrics. Ekonometria. Advances in Applied Data Analytics

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2014

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nr 4(46)

98-107

EN

Forecasts built for the needs of the enterprise may be inaccurate. Actual forecast errors (errors ex post) may be greater than the user-defined acceptable prediction errors. One reason for this may be the impact of psychological factors on the forecaster (eg. emotions) and the application of heuristics (usually unconsciously). The purpose of this article was, first, to draw attention to the issue of the possibility of various kinds of heuristics during the construction of forecasts in the company and second to indicate the possibility of eliminating the adverse effects of heuristics on the course and outcome of the forecasting process.

15

Próba uwzględnienia stochastycznej zmienności danych wejściowych w modelowaniu heurystycznym wirników

100%

Kiciński J. , Pietkiewicz P.

Przegląd Mechaniczny

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2007

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tom nr 11

22-26

PL

Przedstawiono próbę uwzględnienia błędów stochastycznych w analizie stanu maszyny wirnikowej. Opis tego rodzaju błędów i ocena ich wpływu stanowi już element tzw. modelowania heurystycznego, rozumianego jako przeciwieństwo tradycyjnego modelowania algorytmicznego. Badania przeprowadzone zostały z wykorzystaniem zaawansowanego systemu komputerowego MESWIR. Uzyskane wyniki wskazują na mocno zróżnicowany wpływ błędów danych wejściowych na prace przyjętego obiektu.

EN

The trial of consideration of stochastic errors in analysis of rotor machine condition was presented. Description of such kind of errors and evaluation of their impact is an element of heuristic modelling understanding as opposition to traditional algorithmic modelling. Advanced computer system MESWIR was applied. Obtained results indicate that impact of input data errors on work of the object is strongly diversified.

16

Trójetapowa heurystyka znajdowania sekwencji montażowej.

100%

Łebkowski P.

Technologia i Automatyzacja Montażu

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2001

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tom nr 2

10-13

17

Algorytm ewolucyjny szeregowania zadań na jednej maszynie

100%

Stawowy A.

Archiwum Technologii Maszyn i Automatyzacji

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2004

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tom Vol. 24, nr 3 sp

145-152

PL

W artykule zaprezentowano algorytm strategii ewolucyjnej do szeregowania zadań na jednej maszynie przy kryterium minimalizacji ważonej sumy wyprzedzeń i opóźnień. Z problemami takimi można się coraz częściej spotkać w praktyce, gdyż narastająca konkurencja wymusza rygorystyczne dotrzymywanie terminów dostarczania wyrobów klientom. Wyniki badań wykazały, że proponowany algorytm może być wykorzystywany jako efektywne narzędzie planowania operatywnego produkcji, m.in. w zakładach odlewniczych.

EN

This paper focuses on scheduling jobs with varying processing times and distinct due dates on a single machine subject to symmetric earliness and tardiness penalties. The justification for this approach is that in JIT environment, an idea! schedule corresponds to one where all jobs complete precisely at their corresponding due dates. A non-specialized and non-hybridized evolutionary strategy (ES) is proposed for solving this problem. The computational experiment shows that the proposed heuristic perform well and can be used as a planning tool in foundries. Many aspects of the developed ES are quite general and can be adopted to more realistic assumptions.

18

Integrating pivot based search with branch and bound for binary MIPs

100%

Lokketangen A. , Woodruff D.

Control and Cybernetics

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2000

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tom Vol. 29, no 3

741-759

EN

This paper examines integration of a sophisticated, pivot-based tabu search into branch and bound for 0-1 MIPS and global diversification tests using chunking. Issues related to behavior of a tabu search within a branch and bound algorithm are analyzed using computational experiments. Results are presented showing that the inclusion of the local search sometimes results in fewer and nodes and lower CPU times even when used in a callback mode. The main benefit in incorporating a pivot based heuristic is that an integer feasible solution can be found earlier in the branching process. Computational experiments are presented showing that for some instances the overall search time is improved, while for some others the tabu search can find good solutions quickly.

19

Bi-criteria Gateway Placement Problem in Wireless Sensor Networks

100%

Czajko M. M. , Wojciechowski J. M.

International Journal of Electronics and Telecommunications

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2010

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tom Vol. 56, No. 3

215-221

EN

Over the last few years, wireless sensor networks (WSNs) have started to play more and more important role in civil and military applications. A typical sensor network consists of resource-constrained sensing nodes, which monitor environment and send the data to more powerful gateway nodes. The goal of gateway nodes is to aggregate, process and send the data to other gateways or directly to sink nodes. The proper placement of nodes is needed to provide good network operation. Sensing nodes are often placed in a random manner unlike gateways. Gateways, due to their role and cost, are installed rather in a controlled way. In this paper, a bi-criteria gateway placement problem is introduced. The problem is shown to be NP-hard. We formulate it as a linear programming problem, then we develop the Multi-criteria Simulated Allocation (MSAL) heuristic algorithm, for the purpose of cost-effective gateway deployment and power-effective wireless connection management. Finally, we evaluate the efficiency of the algorithm by comparison with the exact method.

20

State Elimination Heuristics for Short Regular Expressions

100%

Han Y.-S.

Fundamenta Informaticae

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2013

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tom Vol. 128, nr 4

445--462

EN

State elimination is an intuitive and easy-to-implement algorithm that computes a regular expression from a finite-state automaton (FA). It is very hard to compute the shortest regular expression for a given FA in general and we cannot avoid the exponential blow-up. This implies that state elimination cannot avoid the exponential blow-up either. Nevertheless, since the size of a regular expression by state elimination depends on the state removal sequence, we can have a shorter regular expression if we choose a better removal sequence for state elimination. This observation motivates us to examine state elimination heuristics based on the structural properties of the input FA and implement state elimination using the heuristics that run in polynomial time. We demonstrate the effectiveness of our algorithm by experiment results.