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Tytuł:
A Performance Analysis of IEEE 802.11ax Networks
Autorzy:
Natkaniec, Marek
Prasnal, Łukasz
Szymakowski, Michał
Powiązania:
https://bibliotekanauki.pl/articles/227270.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
802.11ax
dense networks
performance analysis
Opis:
The paper is focused on the forthcoming IEEE 802.11ax standard and its influence on Wi-Fi networks performance. The most important features dedicated to improve transmission effectiveness are presented. Furthermore, the simulation results of a new transmission modes are described. The comparison with the legacy IEEE 802.11n/ac standards shows that even partial implementation of a new standard should bring significant throughput improvements.
Źródło:
International Journal of Electronics and Telecommunications; 2020, 66, 1; 225-230
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Probabilistic elements in analysis of performance of multiprocessor systems
Autorzy:
Taborek, K.
Hrynkiewicz, E.
Powiązania:
https://bibliotekanauki.pl/articles/201505.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
arbitration circuit
multiprocessor system
performance analysis
queueing model
arbitraż
system wieloprocesorowy
analiza wydajności
model kolejkowy
Opis:
The paper presents important probabilistic elements that should be taken into consideration in the analysis of performance of classical multiprocessor systems. These elements represent the following quantities: modified arrival rate for processor requests and a few probabilities, which determine the frequency of certain events when a multiprocessor system is working. There are four peculiar events: service of another job, existence of the queue, a processor request while the given task is waiting into the queue and the return of another task into the queue while the given task is waiting in the queue. The first three events happen more often when a system consists of less number of processors, whereas the fourth event happens more often when more processors work in a system. Including (or not) the probabilities of these events to the analysis of performance of multiprocessor systems exerts its much influence on the precision of computations. All the mentioned quantities were described in detail. Formulas for these quantities were derived. Examples of applications of the formulas to the prediction of performance of various multiprocessor systems were presented.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2014, 62, 4; 765-771
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Process of market strategy optimization using distributed computing systems
Autorzy:
Nowicki, W.
Bera, A.
Błaszyński, P.
Powiązania:
https://bibliotekanauki.pl/articles/407280.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
economic systems
financial system
moving average models
optimization problems
performance analysis
prediction methods
prediction problems
project management
work organization
Opis:
If market repeatability is assumed, it is possible with some real probability to deduct short term market changes by making some calculations. The algorithm, based on logical and statistically reasonable scheme to make decisions about opening or closing position on a market, is called an automated strategy. Due to market volatility, all parameters are changing from time to time, so there is need to constantly optimize them. This article describes a team organization process when researching market strategies. Individual team members are merged into small groups, according to their responsibilities. The team members perform data processing tasks through a cascade organization, providing solutions to speed up work related to the use of remote computing resources. They also work out how to store results in a suitable way, according to the type of task, and facilitate the publication of a large amount of results.
Źródło:
Management and Production Engineering Review; 2015, 6, 4; 87-93
2080-8208
2082-1344
Pojawia się w:
Management and Production Engineering Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fire resistance assessment of the long-span steel truss girder
Ocena odporności ogniowej stalowej kratownicy o dużej rozpiętości
Autorzy:
Woźniczka, P.
Powiązania:
https://bibliotekanauki.pl/articles/231439.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
odporność ogniowa
hala wielkokubaturowa
rozpiętość duża
pożar
analiza właściwości
fire resistance
large-space hall
long-span
fire
performance analysis
Opis:
The performance-based analysis of the large-space steel sports hall is presented. Load-bearing structure of the hall consists of spatial long-span truss girders that are made of modern square hollow sections. Both fire development analysis and mechanical response analysis are discussed in detail. Fire Dynamics Simulator and Safir programs are used. Main focus is put on the factors that could affect the final fire resistance of the structure. Uniform and non-uniform heating, different boundary conditions and local imperfections are taken into account. Structures with and without fireproof insulation are considered. Values of the critical temperature, failure modes and fire resistance estimated for various cases are presented. Computer simulations were carried out both for fire growth and decay phase. As a result it is clearly shown that some reductions of the required fireproof insulation are possible. Moreover, the structure without complete traditional fireproof insulation is able to survive not only the direct fire exposure but also the cooling phase.
Aktualne normy europejskie EN 1991-1-2 i EN 1993-1-2 dopuszczają do stosowania różnorodne metody oceny odporności ogniowej, które mogą być wykorzystane zarówno w odniesieniu do pojedynczych elementów jak i całych ustrojów nośnych. Podejście obliczeniowe bazujące na właściwościach danej strefy pożarowej (tzw. performance-based approach) powinno uwzględniać zarówno analizę rozwoju pożaru jak i odpowiedzi mechanicznej konstrukcji. Wykorzystanie tego typu metody może być szczególnie istotne w przypadku obiektów o stosunkowo dużych kubaturach stref pożarowych, takich jak na przykład wielkogabarytowe hale o konstrukcji stalowej. Możliwy jest wówczas nie tylko lepszy wgląd w zachowanie się konstrukcji w warunkach pożaru ale istnieje także możliwość dostosowania izolacji ogniochronnej do rzeczywistego zapotrzebowania. Jednocześnie przeprowadzenie kompletnych symulacji typu "performance-based" jest niezwykle czasochłonne oraz wymaga połączenia wiedzy z zakresu inżynierii pożarowej oraz inżynierii lądowej. Dodatkowo wpływ niektórych czynników (takich jak przykładowo lokalne imperfekcje łukowe) na prognozowaną odporność ogniową nie został do tej pory w pełni rozpoznany. W tej sytuacji w artykule przedstawiono opartą na charakterystyce danej strefy pożarowej analizę odporności ogniowej wielkogabarytowej hali sportowej o konstrukcji stalowej. Rozpatrywana hala charakteryzuje się zarówno znacznymi wymiarami w rzucie (70m x 60m) jak i stosunkowo dużą wysokością (16.5m). Główny ustrój nośny składa się z trójpasowych dźwigarów kratowych o rozpiętości 60m, rozmieszczonych w rozstawie co 6m. Obliczenia rozwoju pożaru wykonano za pomocą programu Fire Dynamics Simulator. Do opracowania analizy odpowiedzi mechanicznej konstrukcji wykorzystano program Safir.
Źródło:
Archives of Civil Engineering; 2020, 66, 2; 63-75
1230-2945
Pojawia się w:
Archives of Civil Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Impact of waste heat recovery systems on energy efficiency improvement of a heavy-duty diesel engine
Autorzy:
Ma, Z.
Chen, H.
Zhang, Y.
Powiązania:
https://bibliotekanauki.pl/articles/240819.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
energy efficiency design index
energy efficiency operational indicator
waste heat recovery system
performance analysis
reduction factor
wskaźnik efektywności energetycznej
wskaźniki eksploatacyjny efektywności energetycznej
system odzysku ciepła odpadowego
analiza wydajności
współczynnik redukcyjny
Opis:
The increase of ship’s energy utilization efficiency and the reduction of greenhouse gas emissions have been high lightened in recent years and have become an increasingly important subject for ship designers and owners. The International Maritime Organization (IMO) is seeking measures to reduce the CO2 emissions from ships, and their proposed energy efficiency design index (EEDI) and energy efficiency operational indicator (EEOI) aim at ensuring that future vessels will be more efficient. Waste heat recovery can be employed not only to improve energy utilization efficiency but also to reduce greenhouse gas emissions. In this paper, a typical conceptual large container ship employing a low speed marine diesel engine as the main propulsion machinery is introduced and three possible types of waste heat recovery systems are designed. To calculate the EEDI and EEOI of the given large container ship, two software packages are developed. From the viewpoint of operation and maintenance, lowering the ship speed and improving container load rate can greatly reduce EEOI and further reduce total fuel consumption. Although the large container ship itself can reach the IMO requirements of EEDI at the first stage with a reduction factor 10% under the reference line value, the proposed waste heat recovery systems can improve the ship EEDI reduction factor to 20% under the reference line value.
Źródło:
Archives of Thermodynamics; 2017, 38, 3; 63-75
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimisation of the performance of a pyrolysis reactor for G50 chips
Autorzy:
Dhaundiyal, Alok
Singh, Suraj
Powiązania:
https://bibliotekanauki.pl/articles/240925.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
biomass
thermal analysis
pyrolysis
gas yield
performance index
Opis:
The aim of any industrial plant, which is dealing in the energy sector, is to maximise the revenue generation at the lowest production cost. It can be carried out either by optimizing the manpower or by improving the performance index of the overall unit. This paper focuses on the optimisation of a biomass power plant which is powered by G50 hardwood chips (Austrian standard for biomass chips). The experiments are conducted at different operating conditions. The overall effect of the enhanced abilities of a reactor on the power generation is examined. The output enthalpy of a generated gas, the gas yield of a reactor and the driving mechanism of the pyrolysis are examined in this analysis. The thermal efficiency of the plant is found to vary from 44 to 47% at 400°C, whereas it is 44 to 48% for running the same unit at 600°C. The transient thermal condition is solved with the help of the lumped capacitance method. The thermal efficiency of the same design, within the constraint limit, is enhanced by 5.5%, whereas the enthalpy of the produced gas is magnified by 49.49% through nonlinear optimisation. The temperature of biomass should be homogenous, and the ramping rate must be very high. The 16% rise in temperature of the reactor is required to reduce the mass yield by 20.17%. The gas yield of the reactor is increased by up to 85%. The thermal assessment indicates that the bed is thermally thin, thus the exterior heat transfer rate is a deciding factor of the pyrolysis in the reactor.
Źródło:
Archives of Thermodynamics; 2020, 41, 1; 245-263
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An Accent-Based Approach to Automatic Rendering of Piano Performance: Preliminary Auditory Evaluation
Autorzy:
Bisesi, E.
Parncutt, R.
Powiązania:
https://bibliotekanauki.pl/articles/177339.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
piano performance
expression
accents
musical analysis
Director Musices
Opis:
We are exploring the relationship between accents and expression in piano performance. Accents are local events that attract a listener’s attention and are either evident from the score (immanent) or added by the performer (performed). Immanent accents are associated with grouping (phrasing), metre, melody and harmony. In piano music, performed accents involve changes in timing, dynamics, articulation, and pedalling; they vary in amplitude, form, and duration. We analyzed the first eight bars of Chopin Prelude op. 28 n. 6. In a separate study, music theorists had marked grouping, melodic and harmonic accents on the score and estimated the importance (salience) of each. Here, we mathematically modeled timing and dynamics in the prelude in two ways using Director Musices (DM) – a software package for automatic rendering of expressive performance. The first rendering focused on phrasing following existing and tested procedures in DM. The second focused on accents – timing and dynamics in the vicinity of the accents identified by the theorists. In an informal listening test, 10 out of 12 participants (5 of 6 musicians and 5 of 6 non-musicians) preferred the accent-based formulation, and several stated that it had more variation of timing and dynamics from one phrase to the next.
Źródło:
Archives of Acoustics; 2011, 36, 2; 283-296
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Indebtedness, Fiscal Discipline and Development Spending – A Non-parametric Approach
Autorzy:
Sinha, Ram Pratap
Powiązania:
https://bibliotekanauki.pl/articles/2075409.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Indian states
fiscal performance
efficiency
data envelopment analysis
bootstrap
Opis:
Indian states exhibit considerable heterogeneity in terms of revenue mobilizing capacities and efforts, development spending and fiscal dependence on the central government. In this context, the paper compares the fiscal performance of major Indian states in terms of two non-parametric performance evaluation models for the period 2009–10 to 2014–15. The study thus uses the conventional two stage framework for efficiency evaluation as well as the two stage conditional performance model. The outcomes enable us to identify front-runners as well as laggards in the area of fiscal management. Further, the study showed that the gross capital formation experienced by the states significantly influences state performance in India. However, the impact of outstanding liabilities on efficiency performance was statistically insignificant
Źródło:
Central European Journal of Economic Modelling and Econometrics; 2021, 2; 147-173
2080-0886
2080-119X
Pojawia się w:
Central European Journal of Economic Modelling and Econometrics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Does lean practices implementation impact on company performance? A meta-analytical research
Autorzy:
Gonçalves, Telma I. G.
Sousa, Paulo S. A.
Moreira, Maria R. A.
Powiązania:
https://bibliotekanauki.pl/articles/407127.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
lean manufacturing
performance evaluation
meta-analysis
manufacturing system
company
Opis:
Studies linking the use of lean practices to company performance have been increasing as markets are becoming more competitive and companies are eager for reducing waste and therefore implementing the Lean Management (LM) philosophy to improve performance. However, results from these studies have found various and different impacts and some light is needed. Extant literature was reviewed and, to achieve the research objective, a metaanalysis of correlations was carried out. The obtained results suggest a positive relationship between some lean practices and performance measures. Furthermore, the presence of moderators influencing the relationship between lean practices and performance outcomes is highlighted in our results. To our best knowledge, this is the first research that proposes a comparison of results from primary studies on Lean implementation, by analysing the linear relationship between lean practices and enterprise performance. It fills this gap and therefore represents an important contribution.
Źródło:
Management and Production Engineering Review; 2019, 10, 4; 11-24
2080-8208
2082-1344
Pojawia się w:
Management and Production Engineering Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A comprehensive review on energy and exergy analysis of solar air heaters
Autorzy:
Ghritlahre, Harish Kumar
Sahu, Piyush Kumar
Powiązania:
https://bibliotekanauki.pl/articles/240351.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
solar energy
energy
exergy analysis
solar air heater
thermal performance
Opis:
For economic growth of nation, the energy plays an important role. The excessive use of fossil fuels results the increase in global warming and depleting the resources. Due to this reason, the renewable energy sources are creating more attraction for researchers. In renewable energy sector, solar energy is the most abundant and clean source of energy. In solar thermal systems, solar air heater (SAH) is the main system which is used for heating of air. As it is simple in construction and cheaper in cost, it is of main interest for the researchers. The concept of first law and second law of thermodynamics is used for the study of the energy and exergy analysis respectively. The energy analysis is of great importance for the study of process effectiveness while the exergetic analysis is another significant concept to examine the actual behavior of process involving various energy losses and internal irreversibility. For efficient utilization of solar energy, the exergy analysis is very important tool for optimal design of solar air heaters. The aim of the present work is to review the works related to energy and exergy analysis of various types of solar air heaters and to find out the research gap for future work.
Źródło:
Archives of Thermodynamics; 2020, 41, 3; 183-222
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Framework to Diagnose the Business and Evaluate Upgrade Plans in SMEs
Autorzy:
Momani, Amer
Al-Hawar, Tarek
Tahat, Sufyan
Powiązania:
https://bibliotekanauki.pl/articles/2023964.pdf
Data publikacji:
2021-09
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
strategic planning
performance management
business upgrade
SWOT analysis
resource allocation
Opis:
Small and medium-sized enterprises (SMEs) are facing barriers to grow due to the lack of structured procedures for upgrading and allocating the limited resources. To overcome these drawbacks and to improve business capabilities, a structured framework to conduct a comprehensive diagnostic and upgrading study is presented in this paper. The proposed framework involves four phases. First, the external and internal strategic factors, which can affect the enterprises’ performance are evaluated using strategic planning and assessment tools. Second, key upgrade performance indicators are developed and evaluated using multi-attribute rating techniques to guide, evaluate, and track progress of upgrading process. Third, a set of upgrade strategies are generated and evaluated using resource allocation model. Finally, a periodic re-evaluation plan is introduced to monitor the implementation progress. The developed framework for performance evaluation and upgrading is suitable to be used as a structured know-how procedure in manufacturing enterprises and can support entrepreneurs in their strategic decisions. To validate the proposed framework, a data set was collected from a local housecore company. As a result, one package of the efficient frontier strategies that represents the best use of resources was proposed for implementation.
Źródło:
Management and Production Engineering Review; 2021, 13, 3; 25-39
2080-8208
2082-1344
Pojawia się w:
Management and Production Engineering Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Measuring agility of indian automotive small & medium sized enterprises (SMEs)
Autorzy:
Tiwari, Rupesh Kumar
Tiwari, Jeetendra Kumar
Powiązania:
https://bibliotekanauki.pl/articles/407171.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
exploratory factor analysis
multiple regression analysis
fuzzy logic
fuzzy integrated index
FII
fuzzy performance index
FPII
fuzzy ranking
Opis:
Indian SMEs are going to play pivotal role in transforming Indian economy and achieving double digit growth rate in near future. Performance of Indian SMEs is vital in making India as a most preferred manufacturing destination worldwide under India’s “Make in India Policy”. Current research was based on Indian automotive SMEs. Indian automotive SMEs must develop significant agile capability in order to remain competitive in highly uncertain global environment. One of the objectives of the research was to find various enablers of agility through literature survey. Thereafter questionnaire administered exploratory factor analysis was performed to extract various factors of agility relevant in Indian automotive SMEs environment. Multiple regression analysis was applied to assess the relative importance of these extracted factors. “Responsiveness” was the most important factor followed by “Ability to reconfigure”, “Ability to collaborate”, and “Competency”. Thereafter fuzzy logic bases algorithm was applied to assess the current level of agility of Indian automotive SMEs. It was found as “Slightly Agile”, which was the deviation from the targeted level of agility. Fuzzy ranking methodology facilitated the identification & criticalities of various barriers to agility, so that necessary measures can be taken to improve the current agility level of Indian automotive SMEs. The current research may helpful in finding; key enablers of agility, assessing the level of agility, and ranking of the various enablers of agility to point out the weak zone of agility so that subsequent corrective action may be taken in any industrial environment similar to India automotive SMEs.
Źródło:
Management and Production Engineering Review; 2019, 10, 1; 58-67
2080-8208
2082-1344
Pojawia się w:
Management and Production Engineering Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evaluation and selection process of suppliers through analytical framework: an emprical evidence of evaluation tool
Autorzy:
Imeri, S.
Shahzad, K.
Takala, J.
Liu, Y
Sillanpää, I.
Ali, T.
Powiązania:
https://bibliotekanauki.pl/articles/407383.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
supplier evaluation
supplier performance management
supplier selection model
principal component analysis
supply chain management
Opis:
The supplier selection process is very important to companies as selecting the right suppliers that fit companies strategy needs brings drastic savings. Therefore, this paper seeks to address the key area of supplies evaluation from the supplier review perspective. The purpose was to identify the most important criteria for suppliers’ evaluation and develop evaluation tool based on surveyed criteria. The research was conducted through structured questionnaire and the sample focused on small to medium sized companies (SMEs) in Greece. In total eighty companies participated in the survey answering the full questionnaire which consisted of questions whether these companies utilize some suppliers’ evaluation criteria and what criteria if any is applied. The main statistical instrument used in the study is Principal Component Analysis (PCA). Thus, the research has shown that the main criteria are: the attitude of the vendor towards the customer, supplier delivery time, product quality and price. Conclusions are made on the suitability and usefulness of suppliers’ evaluation criteria and in way they are applied in enterprises.
Źródło:
Management and Production Engineering Review; 2015, 6, 3; 10-20
2080-8208
2082-1344
Pojawia się w:
Management and Production Engineering Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Determination of carbendazim residues in fruits vegetables and cereals by HPLC with column switching
Autorzy:
Michel, M
Buszewski, B.
Powiązania:
https://bibliotekanauki.pl/articles/66285.pdf
Data publikacji:
2002
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
carbendazim residue
determination
plant protection
food analysis
cereal
vegetable
high performance liquid chromatography
fruit
Opis:
Method for determination of carbendazim residues in fruits, vegetables and cereals was described. The compound was extracted with methanol-hydrochloric acid mixture, and after liquid-liquid partition step with dichloromethane, was determined by high performance liquid chromatography (HPLC) with column switching and ultraviolet (UV) detection. The average recoveries of carbendazim from fortified sample were from 68.7% ± 4.3% to 92.6% ± 4.5%, the coefficients of variation were from 2.9% to 6.3%, and the limits of quantification at λ = 279 nm were from 0.02 mg/kg to 0.2 mg/kg.
Przedstawiono procedurę analityczną oznaczania pozostałości karbendazymu w materiale roślinnym techniką wysokosprawnej chromatografii cieczowej HPLC z wykorzystaniem przełączania kolumn. Procedura ta opracowana została w celu wykorzystania w badaniach monitoringowych płodów rolnych i ogrodniczych traktowanych preparatami zawierającymi substancje czynne z grupy fungicydów benzimidazolowych: benomyl, karbendazym, tiofanat metylu. Średni odzysk karbendazymu z próbek fortyfikowanych mieścił się w granicach od 68,7% ± 4,3% do 92,6% ± 4,5%, współczynnik zmienności wynosił od 2,9% do 6,3%, a granica oznaczalności przy długości fali λ = 279 nm była od 0,02 mg/kg do 0,2 mg/kg.
Źródło:
Journal of Plant Protection Research; 2002, 42, 1
1427-4345
Pojawia się w:
Journal of Plant Protection Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Performance-based analysis of older-type large-space hall in fire
Analiza wielkokubaturowej hali stalowej starszego typu w pożarze
Autorzy:
Woźniczka, P.
Powiązania:
https://bibliotekanauki.pl/articles/231136.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
hala wielkokubaturowa
konstrukcja stalowa
pożar
analiza
właściwości
large-space hall
steel structure
fire
performance
analysis
Opis:
The paper presents the example of performance-based analysis for the existing large-space steel structure raised in 1980s. Hall is used as a paper products warehouse. Advanced mechanical simulations are performed using Safir software. Factors that impact the final fire resistance of the structure are discussed. Local and global imperfections and possible ways of structure modelling are taken into account. For selected cases advanced fire scenario that considers both localised fire and possibility of further ignition of stored goods is prepared using Fire Dynamics Simulation software. The results obtained indicate that added imperfections have little impact on the fire resistance of the structure and older-type steel hall roof without any fire protection could survive 30 minutes of fire. Main failure modes and values of structure's deflections are also presented. Finally, performed simulations show that even for large-space structure the flashover is possible in some special cases.
Ocena odporności pożarowej wielkokubaturowych obiektów o konstrukcji stalowej jest przedmiotem bieżącego zainteresowania wielu badaczy. Jednocześnie zaawansowane metody obliczeniowe pozwalające na określenie nośności konstrukcji w warunkach pożaru charakteryzują się znacznym stopniem komplikacji i są ciągle na etapie rozwoju. W efekcie w analizie pożarowej obiektów wielkokubaturowych często przyjmowane są pewne założenia, które wymagają dalszego wyjaśnienia. Po pierwsze w typowych analizach nośności konstrukcji opartych na charakterystyce danej strefy pożarowej zakłada się zazwyczaj, że pożar lokalny jest ograniczony do pewnej maksymalnej mocy. Przyjmuje się przy tym, że zapłon zgromadzonego w okół początkowego źródła ognia paliwa nie jest możliwy. Po drugie zaawansowane metody oceny odporności pożarowej konstrukcji są zazwyczaj stosowane w odniesieniu do współczesnych obiektów wielkokubaturowych, podczas gdy nie uwzględnia się nadal użytkowanych obiektów starszego typu. Po trzecie w ostatnio publikowanych pracach, pomijając przypadki modelowania wydzielonych elementów, brak jest dostatecznych informacji o lokalnych i globalnych imperfekcjach uwzględnianych w analizach konstrukcji wykorzystujących metodę elementów skończonych. W tej sytuacji w artykule przedstawiono opartą na charakterystyce strefy pożarowej analizę nośności rzeczywistej konstrukcji stalowej wzniesionej w latach osiemdziesiątych XX wieku. Szczególną uwagę zwrócono na: - możliwe sposoby zamodelowania konstrukcji z uwzględnieniem różnych warunków brzegowych, - wpływ lokalnych i globalnych imperfekcji na nośność konstrukcji w warunkach pożaru. Jeżeli było to możliwe wskazano modele zniszczenia danej podkonstrukcji, - oszacowanie odporności pożarowej hali stalowej starszego typu, - zastosowanie modelu bazującego na obliczeniowej mechanice płynów, pozwalającego na jednoczesne uwzględnienie pożaru lokalnego i możliwości dalszego zapłonu zgromadzongo paliwa.
Źródło:
Archives of Civil Engineering; 2019, 65, 1; 17-29
1230-2945
Pojawia się w:
Archives of Civil Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 23

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