Search results

Filters

  • Journals
  • Keywords
  • Date

Search results

Number of results: 11
items per page: 25 50 75
Sort by:
Download PDF Download RIS Download Bibtex

Abstract

Author explains a necessity of supply optimization to construction sites with small storage areas. This paper takes account of conditions existing in Poland. From among all factors discussed by the author, first of all, we should point at construction works on plots located in densely built-up areas, obtained by demolition of existing buildings, as well as a necessity of plots utilization after demolished buildings that technical conditions do not allow for further exploitation.

Go to article

Authors and Affiliations

K.M. Kaczorek
Download PDF Download RIS Download Bibtex

Abstract

W artykule badana jest ekonomiczna efektywność działań mających na celu weryfikację potencjalnych beneficjentów programów charytatywnych. Taka weryfikacja ma na celu ograniczenie liczby osób otrzymujących pomoc charytatywną, które nie spełniają kryteriów jej przyznania. Jednocześnie, wiąże się ona z kosztami ponoszonymi przez organizatora programu. W artykule zaproponowano model teoretyczny opisujący to zjawisko. Do przeprowadzania analizy modelu wykorzystano metody optymalizacyjne oraz symulacyjne. Wynika z niej, że w zależności od parametrów programu charytatywnego optymalna może być jedna z trzech decyzji: przyznanie pomocy bez wprowadzania weryfikacji, przyznawanie pomocy po uprzedniej weryfikacji lub przeznaczenie środków pomocowych na inny cel. Optymalność rozwiązania zależy od charakterystyk programu, takich jak średnia kwota pomocy, średni koszt weryfikacji oraz odsetek osób potrzebujących spełniających założenia programu. W zależności od tych zmiennych organizacja charytatywna powinna podjąć decyzję o ewentualnym wprowadzeniu weryfikacji.
Go to article

Authors and Affiliations

Jakub Witkowski
Download PDF Download RIS Download Bibtex

Abstract

Przestrzenne konstrukcje prętowe nazywane często strukturami przestrzennymi znalazły szerokie zastosowanie w świecie, szczególnie zaś w przekryciach obiektów o dużych rozpiętościach. Projektowanie obiektów w których znajdują zastosowanie prętowe struktury przestrzenne o skomplikowanej geometrii jej często poprzedzane licznymi badaniami teoretycznymi i modelowymi. Jednym z etapów projektowania, istotnym z punktu widzenia optymalizacji geometrycznej struktury jest wybór odpowiedniej metody wyznaczania jej morfologii. Opisując zjawiska zachodzące w naturze oraz sposób ich adaptacji do procesu projektowania architektoniczno-konstrukcyjnego autor przedstawia wyniki zastosowania metody analogii potencjałów energetycznych. Inspirację opracowania tej metody stanowi prawo Coulomba - przyjmując, że węzły dowolnej siatki przestrzennej są ładunkami elektrycznymi o ściśle określonych wartościach można otrzymać układ geometryczny w którym wszystkie elementy wzajemnie na siebie oddziałują. Ładunki przyjmą pozycje w przestrzenni dla których suma wzajemnych oddziaływań między nimi będzie najmniejsza. Będzie to układ najkorzystniejszy energetycznie. W niniejszej pracy przedstawiono rezultaty optymalizacji wykonanych z pomocą modeli i symulacji cyfrowych opracowanych przez autora, poddanych następnie uproszczonym analizom statycznym. Wyniki pokazano za pomocą zaproponowanych przez autora wskaźników efektywności.
Go to article

Authors and Affiliations

Kajetan Sadowski
Download PDF Download RIS Download Bibtex

Abstract

The aim of the presented paper is to show the results of shape optimization of railway polynomial transition curves (TCs) of 5th, 7th, and 9th degrees through the use of the full vehicle model and new criteria of assessement concerning the jerk value. The search for the proper shape of TCs means that in this work, the evaluation of TC properties is based on select quantities and the generation of such a shape through the use of mathematically understood optimization methods. The studies presented have got a character of the numerical tests. For this work, advanced vehicle models describing dynamical track-vehicle and vehicle-passenger interactions as well as optimization methods were exploited. In the software vehicle model of a 2-axle freight car, the track discrete model, non-linear descriptions of wheel-rail contact are applied. This part of the software, the vehicle simulation software, is combined with a library optimization procedure into the final computer program.

Go to article

Authors and Affiliations

K. Zboiński
P. Woznica
Download PDF Download RIS Download Bibtex

Abstract

W artykule zaprezentowano model pozwalający na ustalenie optymalnej liczby łączonych zamówień pozwalającej na skrócenie średniego czasu kompletacji. Omówione zostały dwa sposoby kompletacji zleceń łączonych: „pobierz i sortuj” oraz „sortuj podczas pobierania”. Analizie poddano magazyny jednoblokowe prostokątne, gdzie towary składowano w sposób całkowicie losowy oraz losowo w oparciu o klasyfikację ABC. Zbadane zostały dwie heurystyki wyznaczania trasy magazyniera: s-shape i return, dla których można wyznaczyć wzory na średnie czasy kompletacji korzystając z własności rozkładów prawdopodobieństwa: dwumianowego i jednostajnego. W badaniach uwzględniono problem występowania zatorów w magazynie i na podstawie rezultatów symulacji zaproponowano postać analityczną funkcji czasu blokowania. Z przeprowadzonej analizy wynika, że korzyści czasowe z każdego kolejnego dołączonego do listy kompletacyjnej zamówienia są coraz mniejsze. Wykorzystywanie klasyfikacji ABC do składowania towarów szybko rotujących może w magazynach o niewielkiej liczbie alejek i przy dużych zleceniach kompletacyjnych spowodować wydłużenie czasu kompletacji
Go to article

Authors and Affiliations

Grzegorz Tarczyński
Download PDF Download RIS Download Bibtex

Abstract

This paper presents a model of scheduling of multi unit construction project based on an NP-hard permutation flow shop problem, in which the considered criterion is the sum of the costs of the works' execution of the project considering the time of the project as a constraint. It is also assumed that each job in the units constituting the project may be realized in up to three different ways with specific time and cost of execution. The optimization task relies on solving the problem with two different decision variables: the order of execution of units (permutation) and a set of ways to carry out the works in units. The task presented in the paper is performed with the use of a created algorithm which searches the space of solutions in which metaheuristic simulated annealing algorithm is used. The paper presents a calculation example showing the applicability of the model in the optimization of sub-contractors' work in the construction project.

Go to article

Authors and Affiliations

M. Podolski
Download PDF Download RIS Download Bibtex

Abstract

In the last decade, Poland has become one of the most active markets for unconventional hydrocarbon deposits exploration. At present, there are twenty concessions for the exploration and/or discovery of reserves, including shale gas. The area covered by exploration concessions constitutes ca. 7.5% of the country’s area. Four main stages can be distinguished In the shale gas development and exploitation project: the selection and preparation of the place of development of the wells, hydraulic drilling and fracturing, exploitation (production) and marketing, exploitation suppression and land reclamation. In the paper, the concept of cost analysis of an investment project related to the exploration and development of a shale gas field/area was presented. The first two stages related to the preparatory work, carried out on the selected site, as well as drilling and hydraulic fracturing were analyzed. For economic reasons, the only rational way to make shale gas reserves available is to use horizontal drilling, either singly or in groups. The number of drilling pads covering the concession area is a fundamental determinant of the development cost of the deposit. In the paper, the results of the cost analysis of various types of reaming method with an area of 25,000,000 m2 were presented. Cost estimates were prepared for two variants: group drilling for three types of drilling pads: with three, five and seven wells and for single wells. The results show that, as the number of horizontal wells increases, the total cost of the development of the deposit is reduced. For tree-wells pad, these costs are 7% lower than in the second variant, for five-well pads they are 11% lower, and for seven-well pads they are 11.5% smaller than in the second variant. Authors, using applied methodology, indicate the direction of further research that will enable the optimization of shale gas drilling operations.

Go to article

Authors and Affiliations

Alicja Byrska-Rąpała
Jerzy Feliks
Marek Karkula
Rafał Wiśniowski
Download PDF Download RIS Download Bibtex

Abstract

The present study has been taken up to emphasize the role of the hybridization process for optimizing a given reinforced concrete (RC) frame. Although various primary techniques have been hybrid in the past with varying degree of success, the effect of hybridization of enhanced versions of standard optimization techniques has found little attention. The focus of the current study is to see if it is possible to maintain and carry the positive effects of enhanced versions of two different techniques while using their hybrid algorithms. For this purpose, enhanced versions of standard particle swarm optimization (PSO) and a standard gravitational search algorithm (GSA), were considered for optimizing an RC frame. The enhanced version of PSO involves its democratization by considering all good and bad experiences of the particles, whereas the enhanced version of the GSA is made self-adaptive by considering a specific range for certain parameters, like the gravitational constant and a set of agents with the best fitness values. The optimization process, being iterative in nature, has been coded in C++. The analysis and design procedure is based on the specifications of Indian codes. Two distinct advantages of enhanced versions of standard PSO and GSA, namely, better capability to escape from local optima and a faster convergence rate, have been tested for the hybrid algorithm. The entire formulation for optimal cost design of a frame includes the cost of beams and columns. The variables of each element of structural frame have been considered as continuous and rounded off appropriately to consider practical limitations. An example has also been considered to emphasize the validity of this optimum design procedure.

Go to article

Authors and Affiliations

Sonia Chutani
Jagbir Singh
Download PDF Download RIS Download Bibtex

Abstract

The aim of this study is to find the cost design of RC tension with varying conditions using the Artificial Neural Network. Design constraints were used to cover all reliable design parameters, such as limiting cross sectional dimensions and; their reinforcement ratio and even the beahviour of optimally designed sections. The design of the RC tension members were made using Indian and European standard specifications which were discussed. The designed tension members according to both codes satisfy the strength and serviceability criteria. While no literature is available on the optimal design of RC tension members, the cross-sectional dimensions of the tension membersfor different grades of concrete and steel, and area of formwork are considered as the variables in the present optimum design model. A design example is explained and the results are presented. It is concluded that the proposed optimum design model yields rational, reliable, and practical designs.

Go to article

Authors and Affiliations

N. Karthiga Shenbagam
N. Arunachalam
Download PDF Download RIS Download Bibtex

Abstract

The study presents the summary of the knowledge of energy-active segments of steel buildings adapted to obtain electrical energy (EE) and thermal energy (TE) from solar radiation, and to transport and store TE. The study shows a general concept of the design of energy-active segments, which are separated from conventional segments in the way that allows the equipment installation and replacement. Exemplary solutions for the design of energy-active segments, optimised with respect to the principle of minimum thermal strain and maximum structural capacity and reliability were given [34]. The following options of the building covers were considered: 1) regular structure, 2) reduced structure, 3) basket structure, 4) structure with a tie, high-pitched to allow snow sliding down the roof to enhance TE and EE obtainment. The essential task described in the study is the optimal adaptation of energy-active segments in large-volume buildings for extraction, transportation and storage of energy from solar radiation.

Go to article

Authors and Affiliations

Z. Kowal
M. Siedlecka
R. Piotrowski
K. Brzezińska
K. Otwinowska
A. Szychowski
Download PDF Download RIS Download Bibtex

Abstract

The economic downturn in Europe and in the world, has affected the traditional branches of industry in a particular way. Development plans of domestic coke plants in terms of main production assets for the next years have been presented. Taking into account the current market situation, the coke plants strategy should aim at risk minimization through application of already known technologies. On the other hand, investments in scope of new and innovative technologies which are connected with a high level of variability, should be seen as an opportunity. Thus, evaluation of investment projects should be done in a different way than so far. The traditional discount analysis, because of its static nature, does not take into account variability and options included in projects with many decision moments - it can prove to be not sufficient. A tool which helps the decision makers in such situations, is the real options analysis. The article presents the findings of the research-development project on coal blend pre-drying implementation, realized by Zdzieszowice Coke Plant and ICHPW in Zabrze. The results achieved so far, as well as the concerns resulting from the project, have been discussed in this article. Further project development plans, aiming at the construction of a semi industrial research installation for analysing the impact of pre-drying on the coke making process have been presented. The article describes premises for the application of real options analysis as a tool to evaluate projects, the results of which are uncertain. The origin and structure of real options as well as the conditions of their application compared to traditional, discount based project evaluation methods, have been presented. The origin and characteristic parameters of real options have been discussed. In the next part, by applying the NPV and real options method, the research-development undertaking of coal blend pre-drying implementation on two coke batteries, has been evaluated. In order to assess the real option's value of the project, which is a classic European call option, the Black-Scholes formula has been used. The achieved results have been compared as well as the flexibility rate of the analyzed research-development project has been defined.

Go to article

Authors and Affiliations

Piotr Żarczyński
Andrzej Strugała
Aleksander Sobolewski
Czesław Sikorski

This page uses 'cookies'. Learn more