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Wyświetlanie 1-10 z 323
Tytuł:
FEM temperature evaluation of model braking test in comparison to selected laboratory test
Autorzy:
Skorupka, Z.
Powiązania:
https://bibliotekanauki.pl/articles/247287.pdf
Data publikacji:
2015
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
transport
air transport
simulation
friction materials
model braking
Opis:
Friction pair tests or model brake tests are one of the trials done in order to evaluate friction pair materials usefulness in full-scale brakes. Such tests are both time consuming and expensive, so most of the manufacturers want to reduce them as much as possible by using numerical simulations for both time and costs savings. It is not possible to eliminate laboratory tests entirely because of the safety regulations requirements. Without regulatory compliance, no brake material can be used in consumer products such as cars or airplanes. Nowadays most of the FEM programs are capable of simulate braking (friction) process in many of its aspects. Accuracy of calculations varies according to complexity of the model and phenomena taken into account. One of the interesting aspects of braking is the friction temperature generation especially due to its destructive impact on the vehicle brakes. Laboratory evaluation of the temperature can be performed in limited spectrum because of inaccessibility of the friction area. FEM calculations can help to determine temperature changes and temperature value during process. It also helps to determine temperature induced damaging conditions for the friction material or the whole brake design. In this paper author compares FEM of friction temperature calculations and laboratory test performed in Landing Gear Laboratory of Institute of Aviation in Warsaw where author works on daily basis. FEM simulation was created in order to resemble mentioned friction material test and to create model of the geometry of the tested material including test stand parts. All of the calculations were performed using COMSOL MULTIPHISICS software.
Źródło:
Journal of KONES; 2015, 22, 3; 213-219
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Neural Network Evaluation of Model-Based Residuals in Fault Detection of Time Delay Systems
Autorzy:
Zitek, P.
Mankova, R.
Hlava, J.
Powiązania:
https://bibliotekanauki.pl/articles/908288.pdf
Data publikacji:
1999
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
wykrywanie błędu
model anizochroniczny
obserwator stanów
sterowanie wewnętrzne
sieć neuronowa
model-based fault detection
anisochronic model
state observer
internal model control
artificial neural networks
Opis:
Model-based fault detection becomes rather questionable if a supervised plant belongs to the class of systems with distributed parameters and significant delays. Two methods of fault detection have been developed for this class of plants, namely a method of functional (anisochronic) state observer and a modified internal model control scheme adopted for that purpose. Both these model schemes are employed to generate residuals, i.e. differences suitable to watch whether a malfunction of the control operation has occurred. Continuous evaluation of residuals is provided by means of a dynamic application of artificial neural networks (ANNs). This evaluation is carried out on the basis of prediction of time series evolution, where the accordance obtained between the prediction and measured outputs is used as a classification criterion. Implementation of both the methods is demonstrated on a laboratory-scale heat transfer set-up, making use of the Real-Time Matlab software.
Źródło:
International Journal of Applied Mathematics and Computer Science; 1999, 9, 3; 599-617
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ocena modelu dyspersji zanieczyszczeń powietrza OSPM: studium przypadku, Polska, Kraków
Evaluation of the OSPM Air Pollutants Dispersion Model: Case Study, Krakow, Poland
Autorzy:
Rzeszutek, M.
Bogacki, M.
Powiązania:
https://bibliotekanauki.pl/articles/1818043.pdf
Data publikacji:
2016
Wydawca:
Politechnika Koszalińska. Wydawnictwo Uczelniane
Tematy:
ocena modelu
OSPM
modelowanie dyspersji atmosferycznej
kanion uliczny
zanieczyszczenie powietrza
evaluation of model
modeling of atmospheric dispersion
street canyon
air pollution
Opis:
The study represents the evaluation of the OSPM model on the basis of the simulation results carried out for the street canyon located in the Zygmunt Krasinski alley in Krakow. Road emission was estimated based on the data from 2012 in regard to the traffic volume and the types of vehicles. Meteorological data were acquired from the station located in the vicinity of the examined canyon. Ambient air quality was determined based on the monitoring data from the urban background station in Krakow. The calculation results were compared with the 1-hour concentration measurements from the traffic station located on the green belt between the two lanes of the analysed canyon. The analysis was restricted to the nitrogen dioxide (NO2) and the PM10 and PM2.5 particulate matter concentrations. Model evaluation was carried out according to the methodology of the air quality models assessment. Values of OSPM model statistical evaluation parameters fall within the range of “good models”, which indicates a very good quality of this model calculation results. A very strong correlation between the results of calculations and the observations was found, particularly for the particulate matter PM10 and PM2.5. Correlation coefficient values for these pollutants are 0.90 and 0.91, respectively. A detailed analysis revealed that the overall quality of the model is better with respect to nitrogen dioxide than for the analysed dust pollutants. However, this model is burdened with a tendency to underestimate 1-hour concentrations of particulate matter, which can be associated with: negligence of the lifting effect of the dust deposited on the road surface, the effect of removing the particulate filters from vehicles and the adequate ambient air quality for the analysed monitoring site. Very good agreement of the simulation results and observations indicates that the OSPM modelling system can be successfully applied to support the air quality management system in Krakow.
Źródło:
Rocznik Ochrona Środowiska; 2016, Tom 18, cz. 2; 351-362
1506-218X
Pojawia się w:
Rocznik Ochrona Środowiska
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An evaluation of turbulence model for vortex breakdown detection over delta wing
Autorzy:
Wibowo, S. B.
Sutrisno, -
Rohmat, T. A.
Powiązania:
https://bibliotekanauki.pl/articles/949942.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
turbulence models
vortex breakdown
delta wing
vortex core
computational fluid dynamics
CFD
roll-up vortex
modele turbulencji
awaria wirowa
skrzydło delta
rdzeń vortex
obliczeniowa mechanika płynów
wir zawijający
Opis:
An important phenomenon of delta wing is the mechanism of vortex core, which indicates the increase in lifting force until the occurrence of the vortex breakdown. The computational fluid dynamics (CFD) is very helpful in visualizing and providing analysis of the detailed data. The use of turbulent models will affect the quality of results in obtaining the vortex breakdown phenomenon. This study used several models of turbulence to capture the occurrence of vortex breakdown and compare it with experiments using water tunnel test facility. The results show that all turbulence models give good results at a low angle of attack (AoA), but at a high AoA the DES model gives the results closest to experimental ones with Cl error value of about 1 %. Taking into account the time required and the acceptable level of accuracy, the use of SST and k-ω models is an alternative option for use in the detection of vortex breakdown.
Źródło:
Archive of Mechanical Engineering; 2018, LXV, 3; 399-415
0004-0738
Pojawia się w:
Archive of Mechanical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evaluation model of the companies operating within logistic network
Autorzy:
Foltin, P.
Gontarczyk, M.
Świderski, A.
Zelkowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/223705.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
logistics companies
logistic network
evaluation model
multi-criteria methods
firmy logistyczne
sieć logistyczna
model oceny
metoda wieloparametrowa
Opis:
In the paper authors presented concept of evaluation of complex systems such as logistic companies which operate in competitive environment. Authors also highlighted the importance of the evaluation problem in operational activity, particularly in the properly prepared procedures to be followed, consisted of several stages adapted to currently conducted research. Properly executed evaluation of companies enables customers to take right decisions on contracting services and stimulate the development of those companies. It should be noted that the proposed algorithmic model of assessment may be particularly useful for assessment of complex logistics systems. Characteristics of the respective phases developed procedure allowed to indicate that it is important to select of appropriate criteria and evaluation methods. It was pointed out that particularly useful for assessing of logistics companies are multi-criteria analysis methods, because they allow to examine objects in a holistic manner, taking into consideration various aspects of activities such organizations. For the practical realization of assessment of logistics companies there was proposed Bellinger method, which contains quite transparent procedures. The results obtained from that method are consistent with those carried out by means of other, more complex multi-criteria methods. Also there was presented the problem of selection of weighted factors for the criteria in the context of their impact on the end result of evaluation. It was pointed out that the choice of an appropriate procedure for determining weights depends on the nature of the evaluated problem and form of criteria.
Źródło:
Archives of Transport; 2015, 36, 4; 21-33
0866-9546
2300-8830
Pojawia się w:
Archives of Transport
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of 3D Scanning Technology for Evaluation of Virtual Model of Gun Geometry
Zastosowanie technologii skanowania trójwymiarowego w procesie odwzorowania geometrii wybranych elementów broni
Autorzy:
Fikus, B.
Paszkowski, R.
Płatek, P.
Powiązania:
https://bibliotekanauki.pl/articles/403540.pdf
Data publikacji:
2018
Wydawca:
Wojskowa Akademia Techniczna im. Jarosława Dąbrowskiego
Tematy:
construction and operation of machines
3D scanning
geometry reconstruction
gun parts geometry
skanowanie 3D
rekonstrukcja geometrii
geometria elementów broni
Opis:
The paper presents the results of reconstruction of selected gun elements with application of 3D scanning technology. Algorithm of under investigation process, the way of preparing object for scanning and measuring process were also presented. This article discusses also data acquisition of clouds of points and methods of some activities with measured geometry data (i.e. solving some imperfections caused by the preparation or by the measurement process). Geometry was remeshed by the creating a new mesh of polygons to unify shapes defined after previous steps. On the basis of cloud of points measurements, the solid geometry of the whole object was prepared. The effect proved satisfactory accuracy of the estimated parts’ characteristics and allowed for recommendation of the mentioned approach in the described process.
W artykule przedstawiono wyniki rekonstrukcji geometrii wybranych elementów pistoletu z zastosowaniem technologii skanowania 3D. Przedstawiono również algorytm rozważanego procesu oraz sposób przygotowania obiektu do skanowania i pomiaru. Omówiono również pozyskiwanie chmur punktów i metodykę opracowania danych z mierzonej geometrii (tj. rozwiązywanie problemów wynikających z obecności nieciągłości chmur spowodowanych przez błędy przygotowania lub proces pomiaru). Uzyskana geometria została zmodyfikowana przez utworzenie nowej siatki wielokątów w celu połączenia kształtów zdefiniowanych w poprzednich krokach. Na podstawie chmury punktów pomiarowych przygotowano geometrię bryłową całego obiektu. Efekt końcowy pozwolił na oszacowanie charakterystyk geometrycznych części z zadowalającą dokładnością i pozwala na rekomendację wspomnianego podejścia w opisywanym procesie.
Źródło:
Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa; 2018, 9, 1 (31); 105-114
2081-5891
Pojawia się w:
Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Towards an Evaluation Model of Trust and Reputation Management Systems
Autorzy:
Janiszewski, M.
Powiązania:
https://bibliotekanauki.pl/articles/226314.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
trust
reputation
attacks
trust and reputation management system
TRM
attacks on trust and reputation management systems
Opis:
The paper presents a set of concepts which can establish a basis for the creation of new evaluation model of trust and reputation management systems (TRM). The presented approach takes into account essential characteristics of such systems to provide an assessment of its robustness. The model also specifies measures of effectiveness of trust and reputation systems. There is still a need to create a comprehensive evaluation model of attacks on trust and reputation management systems and evaluation model of TRM systems itself, which could facilitate establishing a framework to deeply evaluate the security of existing TRM systems. We believe that this paper could be perceived as a small step forward towards this goal.
Źródło:
International Journal of Electronics and Telecommunications; 2017, 63, 4; 411-416
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evaluation of phenomenological model parameters using density dependent laws for prediction of mechanical response of cellular materials
Autorzy:
Butt, H. S. U.
Xue, P.
Hou, B.
Powiązania:
https://bibliotekanauki.pl/articles/200833.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
cellular materials
aluminum foam
phenomenological model
energy absorption
materiały komórkowe
piana aluminiowa
modele fenomenologiczne
absorpcja energii
Opis:
Cellular materials have found wide-spread attention in structural applications involving impact energy absorption. The choice of the most suitable density of a cellular material, for a particular impact application, is based on its mechanical response, which may be obtained through experimental tests and/or models. A current study is focused on prediction of a mechanical response of a wide range of densities of a cellular material using available experimental data of very few densities. Best fitting-parameters of four selected phenomenological models, to fit the available experimental response of three distinct aluminum foam densities, are evaluated. The relationship between the best-fitting parameters and density of the foam is established by using two types of functions. The first function is based on a power law relationship between each parameter and foam density ρ, while the second function assumes each parameter as a linear combination of ρn and ρ, where n is any real number. The former function is found reasonable in the cases of both parameter interpolation and extrapolation while the latter is found reasonable for a parameter interpolation only. The findings of a current study emphasize for a conscious approach during selection of density dependent laws for phenomenological model parameters to avoid any erroneous or misleading design decision.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2015, 63, 1; 181-191
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Applications of monitoring of electric power parameters to performance evaluation of a model vacuum-assisted moulding installation
Autorzy:
Ziółkowski, E.
Brzeziński, M.
Wrona, R.
Smyksy, K.
Zyzak, P.
Powiązania:
https://bibliotekanauki.pl/articles/382938.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
mechanizacja procesów odlewniczych
automatyzacja procesów odlewniczych
pomiar elektroenergetyczny
formowanie podciśnieniowe
mechanisation of foundry processes
automation of foundry processes
electric power measurements
vacuum-assisted moulding processes
Opis:
Vacuum conditions in foundry installations are generated using electric-driven vacuum pumps. The purpose of the experiment is to evaluate the performance of a vacuum-assisted system for compaction of moulding sand basing on registered plots of selected electric power parameters of the power-supplying system of the pumps. Model testing done on an experimental vacuum system installation, power-supplied from a system incorporating the recorders of instantaneous current and voltage values. Following the numerical procedure, the experimental data are analysed to yield mathematical relationships between the variations of the generated vacuum pressure levels and variations of selected electric power parameters. Registered and computed values of selected parameters: instantaneous and RMS voltage and current values, active, reactive and apparent power levels and power coefficient allow for diagnosing the adequacy and reliability of the system operation. According to the authors, the applied monitoring of the power parameters of a vacuum-assisted installation may become an effective and easy practical method of evaluating the performance of such installations, used also in foundry plants.
Źródło:
Archives of Foundry Engineering; 2012, 12, 2; 267-272
1897-3310
2299-2944
Pojawia się w:
Archives of Foundry Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evaluation of vessel simulation model compatibility with its equivalent in reality
Autorzy:
Zwolan, P.
Czaplewski, K.
Powiązania:
https://bibliotekanauki.pl/articles/320468.pdf
Data publikacji:
2013
Wydawca:
Polskie Forum Nawigacyjne
Tematy:
simulation
mathematical modelling
manoeuvrability
Opis:
Complex simulation systems are often used in order to enhance the safety level on newly designed navigation areas and to facilitate their verification process. The application of these systems supersedes older methods based on manoeuvring basins, wherein models minified in particular scales were used. Modern methods are definitely cheaper and require less work. The paper presents the method of assessment of the compatibility of a ship simulation model with its real counterpart. Access to the simulator’s components responsible for creating and editing bodies of water as well as ship models gives the possibility of their verification. Using cutting-edge navigation systems such as inertial systems, weather stations and GPS gives the possibility of obtaining indispensable information about ship’s behaviour under certain hydro-meteorological conditions.
Złożone systemy symulacyjne są często używane dla poprawy poziomu bezpieczeństwa na etapie projektowania nowej infrastruktury nawigacyjnej, jak również dla ułatwienia procesu ich weryfikacji. Stosowanie tych systemów zastępuje starsze metody oparte na pomniejszonych modelach fizycznych i basenach modelowych, w których je testowano. Nowoczesne metody są zdecydowanie tańsze i wymagają mniej pracy. Artykuł przedstawia metodę oszacowania zgodności modelu symulacyjnego statku z jego rzeczywistym odpowiednikiem. Dostęp do komponentów symulatora odpowiedzialnych za tworzenie i modelowanie akwenu oraz modele statku daje możliwość ich sprawdzania. Jest to możliwe dzięki użyciu najnowszych systemów nawigacyjnych, takich jak systemy inercjalne, stacje meteorologiczne i GPS, które umożliwiają otrzymywanie niezbędnej informacji o zachowaniu się statku w konkretnych warunkach hydrometeorologicznych.
Źródło:
Annual of Navigation; 2013, 20; 163-170
1640-8632
Pojawia się w:
Annual of Navigation
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-10 z 323

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