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Wyświetlanie 1-15 z 271
Tytuł:
Recent dynamic ocean topography models and their comparison
Autorzy:
Marchenko, A.
Tretyak, K.
Lopyshansky, A.
Pavliv, T.
Powiązania:
https://bibliotekanauki.pl/articles/59880.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Stowarzyszenie Infrastruktura i Ekologia Terenów Wiejskich PAN
Tematy:
ocean topography model
geodesy
oceanography
dynamic model
mean dynamic topography model
hydrological data
Opis:
Regarding the rapidly growing satellite altimetry database and corresponding products worldwide, an investigation of different mean dynamic ocean topography (MDT) models was assessed to be important for further use in geodetic applications. The efficiency and quality of different MDT models are discussed in view of adopted geoids as reference surfaces. The models used are: 1) The ECCO model based on hydrology and altimetry data, 2) The combined MDT Rio-05 constructed in CSL AVISO (2005) from data for the period 1993-1999, 3) The combined MDT CNES-CLS09 model at the grid points 15’x15’ based on altimetry and hydrology data for the period 1993-2007 (CSL AVISO, 2009), 4) The DNSC08MDT solution of mean dynamic topography (Danish National Space Center) obtained from the geometrical differences between the DNSC08 mean sea surface and the EGM2008 geoid model. The concluding results of the investigation are: 1) statistics of all mean dyamic topography models leads to the approximately same standard deviations about 70 cm and range from -2 m to 2 m; 2) all differences among various MDT models give much smaller standard deviations about 6 – 15 cm; 3) all such differences among various MDT give larger mean deviation, which can be explained by different geoid models or reference surfaces adopted for each solution; 4) better agreement provides MDT CNES-CLS09 and DNSC08MDT models. As a result, we prefer MDT CNES-CLS09 and DNSC08MDT solutions since their noise level corresponds to an estimated accuracy of modern satellite altimetry data.
Źródło:
Infrastruktura i Ekologia Terenów Wiejskich; 2010, 11
1732-5587
Pojawia się w:
Infrastruktura i Ekologia Terenów Wiejskich
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Efekt wzrostu awersji do ryzyka na popyt na samoubezpieczenie w modelu dynamicznym
EFFECT OF INCREASE IN RISK AVERSION ON SELF-INSURANCE IN DYNAMIC MODEL
Autorzy:
Piotr, Dudzinski
Powiązania:
https://bibliotekanauki.pl/articles/418966.pdf
Data publikacji:
2012
Wydawca:
Uniwersytet Gdański. Wydział Ekonomiczny
Tematy:
DYNAMIC MODEL
RISK AVERSION
SELF-INSURANCE
Opis:
This work shows that in a two-period framework increase in risk-aversion is not a sufficient condition to invest more in self-insurance, as it is in one-period setting (Dionne and Eeckhoudt). We prove that other factors important for decision-making exist. Relationship between size of loss and future and present income is crucial in this problem. We consider two cases – when an effort to prevent risk precedes its effect and when it is simultaneous. We show that those cases are mathematically and economically different.
Źródło:
Współczesna Gospodarka; 2012, 3, 2; 35-47
2082-677X
Pojawia się w:
Współczesna Gospodarka
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamic model of a crankshaft assembly with two degrees of freedom
Autorzy:
Chmielewski, A.
Bogucki, Ł.
Gumiński, R.
Mączak, J.
Powiązania:
https://bibliotekanauki.pl/articles/244367.pdf
Data publikacji:
2015
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
distributed generation
dynamic model
crankshaft assembly
Opis:
Nowadays, growing attention is directed towards energy efficiency and issues related to respecting energy. An extremely vital role at improving energy efficiency plays the cogeneration technologies. In the 2012/27/UE Directive [1], the gas turbines [2] in combination with heat recovery, combustion engines [3, 4], steam engines [4], fuel cells [5-7], microturbines [8], Rankine organic cycle [9, 10], Stirling engines [11-15], and others, were included among cogeneration technologies, in which electric energy is produced from waste heat in the combined process. In this work, the distributed generation sources have also been addressed. From the perspective of the article herein, the sources equipped with the crankshaft assembly have been particularly emphasised. This mechanism converts chemical energy of, among others, fuel or working element into mechanical energy (the piston reciprocating motion is converted into rotary motion of a crankshaft). In this work, the physical model of the crankshaft assembly has been shown, with two degrees of freedom. On the basis of analysis of the physical model (with the static mass reduction), a single-piston simulation model has been developed of the crankshaft assembly, using the Matlab&Simulink software. On the basis of the analysis of the system, the motion equations have been derived, which served the purpose of building the simulation model. Because of the conducted simulations, the curves of displacement, velocity, and piston acceleration have been presented, and, respectively, the angular displacement, angular velocity, and angular acceleration of the crankshaft. The constructed model should be seen as a part of a multi-piston working mechanism in a, for example, Stirling engine.
Źródło:
Journal of KONES; 2015, 22, 3; 275-282
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
USING GENETIC ALGORITHM IN DYNAMIC MODEL OF SPECULATIVE ATTACK
Autorzy:
Gawrońska-Nowak, Bogna
Grabowski, Wojciech
Powiązania:
https://bibliotekanauki.pl/articles/517176.pdf
Data publikacji:
2016
Wydawca:
Instytut Badań Gospodarczych
Tematy:
currency crisis
dynamic model
genetic algorithms
Opis:
Evolution of speculative attack models shows certain progress in developing the idea of the role of expectations in the crisis mechanism. Obstfeld (1996) defines expectations as fully exogenous. Morris and Shin (1998) treat the expectations as endogenous (with respect to noise), not devoting too much attention to information structure of the foreign exchange market. Dynamic approach proposed by Angeletos, Hellwig and Pavan (2006) offers more sophisticated assumption about learning process. It tries to reflect time-variant and complex nature of information. However, this model ignores many important details like a Central Bank cost function. Genetic algorithm allows to avoid problems connected with incorporating information and expectations into agent decision-making process to an extent. There are some similarities between the evolution in Nature and currency market performance. In our paper an assumption about rational agent behaviour in the efficient market is criticised and we present our version of the dynamic model of a speculative attack, in which we use a genetic algorithm (GA) to define decision-making process of the currency market agents. The results of our simulation seem to be in line with the theory and intuition. An advantage of our model is that it reflects reality in a quite complex way, i.e. level of noise changes in time (decreasing), there are different states of fundamentals (with “more sensitive” upper part of the scale), the number of inflowing agents can be low or high (due to different globalization phases, different capital flow phases, different uncertainty levels).
Źródło:
Equilibrium. Quarterly Journal of Economics and Economic Policy; 2016, 11, 2; 287-306
1689-765X
2353-3293
Pojawia się w:
Equilibrium. Quarterly Journal of Economics and Economic Policy
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamic load analysis of the connecting bolts in a universal joint
Autorzy:
An, Yuchen
Liu, Jing
Li, Zengguang
Powiązania:
https://bibliotekanauki.pl/articles/2087028.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Polskie Naukowo-Techniczne Towarzystwo Eksploatacyjne PAN
Tematy:
dynamic loads
connecting bolts
universal joint
dynamic model
Opis:
Dynamic loads of the connecting bolts in a universal joint can greatly affect the bolt fatigue and fracture, as well as the machinery safety and stability. But few researches focused on those. To obtain the dynamic load characteristics of the connecting bolts in a universal joint, this paper established a flexible dynamic model for the connecting bolts. A multibody dynamic model of a universal joint is developed. The dynamic loads on the connecting bolts of the universal joint are analyzed. The influences of the preloads, speeds and loads are studied. The amplitude and frequency properities are obtained. The effect of the preload is small when the preload is in the range of 80%~120% of the standard value. The load and speed have great influence on the time- and frequency-domain dynamic loads of the bolts. The flexible dynamic model of the connecting bolt is closer to the actual situation than the rigid model since it can consider the preload and deformation of the bolts. This study can provide guidance for the fatigue life prediction of the universal shaft and its bolts.
Źródło:
Eksploatacja i Niezawodność; 2022, 24, 2; 211--225
1507-2711
Pojawia się w:
Eksploatacja i Niezawodność
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical research of toothed gears geometry influence on power transmission system vibroactivity
Autorzy:
Peruń, G.
Kozuba, J.
Powiązania:
https://bibliotekanauki.pl/articles/245090.pdf
Data publikacji:
2017
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
power transmission system
toothed gear
dynamic model
Opis:
The article presents results of numerical studies on the influence of selected factors on the dynamic effects and vibroactivity in power transmission system with toothed gear. Optimization of the constructions of the toothed gears is in many cases only possible by applying the numerical methods. Dynamic models allow determining the influence of a range of factors on the dynamic phenomena occurring during work of toothed gear. The studies were performed with use a custom developed dynamic model of a test stand with the gears operating in the circulating power system. It was assumed, that properly defined and identified model can be used to analyse dynamic phenomena occurring in meshing and bearings of toothed gears and allows optimizing their construction, especially allows minimization their vibroactivity. Numerical calculations were based on two sets of input data. Sets of input data consist information on all parameters included in the model, and which were determined during the identification process carried out in laboratory at two test stands. Selected results of simulations presented in this article prove, that identified dynamic model can be used to analysis of the impact of various constructional, technological and operational factors on the vibroactivity of the toothed gear.
Źródło:
Journal of KONES; 2017, 24, 4; 239-246
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stability control of propeller Autonomous Underwater Vehicle based on combined sections method
Autorzy:
Qi, D.
Feng, J.
Liu, A.
Hu, J.
Xu, H.
Li, Y.
Ashraf, M. A.
Powiązania:
https://bibliotekanauki.pl/articles/259119.pdf
Data publikacji:
2015
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
propeller AUV
dynamic model
stability control
simulation
Opis:
Learning from the motion principle of quadrotor, a symmetric propeller AUV, which has small size and low velocity is designed. Compared with the AUV equipped with rudders, it has better maneuverability and manipulation at low velocity. According to the Newton-Euler method, the 6 DOF kinematic model and dynamic model of the propeller AUV are established. A stability controller that consists of 3 different PID controllers is designed. It makes the depth and attitude angle as trigger conditions, and the relevant controller is chosen in different moving process. The simulation experiments simulate ideal motion state and disturbed motion state, and experiments results show that the stability controller based on combined sections method can make the best of mature technology of PID, and meet the control requirements in different stages. It has a higher respond speed and accuracy, improving the stability of the propeller AUV under the disturbance of complex ocean currents.
Źródło:
Polish Maritime Research; 2015, S 1; 157-162
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical simulation of heat flow processes
Autorzy:
Mielewczyk, A.
Powiązania:
https://bibliotekanauki.pl/articles/259531.pdf
Data publikacji:
2005
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
simulation
dynamic model
heat transfer
Z-transform
Opis:
Numerical simulation methodis basedon mathematical models of physical processes, which describe run of a given process with a various accuracy. This paper presents a method for elaborating the computer simulation models based on differential equations. This makes it possible to obtain a high accuracy of representing dynamic features of a real process. The derived results are given in the form of numerical series. An example of modelling the dynamics of heat transfer through aflat wall is presented in the second part of the paper. Basing on the model one can simulate the process of operation of ship engine as well as such auxiliary devices as a cooler, evaporator, condenser, tank heating system etc.
Źródło:
Polish Maritime Research; 2005, 4; 22-25
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ogólne sformułowanie zadania identyfikacji nieliniowego modelu dynamicznego
General formulation of the task of the nonlinear model identification
Autorzy:
Dąbrowski, Z.
Powiązania:
https://bibliotekanauki.pl/articles/387619.pdf
Data publikacji:
2009
Wydawca:
Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Tematy:
model dynamiczny
pomiary zaburzenia
dynamic model
measurements of disturbances
Opis:
W pracy przedyskutowano tezę, że nieliniowy model dynamiczny może być zidentyfikowany z należytą dokładnością przy wykorzystaniu koherencyjnej techniki pomiaru nieliniowego zaburzenia. W efekcie zaproponowano metodykę postępowania.
In the paper it was considered the thesis that nonlinear dynamic model can be identified with sufficient accuracy using coherence technique of nonlinear disturbance measure. Finally the methodological proposal is given.
Źródło:
Acta Mechanica et Automatica; 2009, 3, 2; 13-18
1898-4088
2300-5319
Pojawia się w:
Acta Mechanica et Automatica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of construction factors on the vibrational activity of the gearing
Wpływ czynników konstrukcyjnych na wibroaktywność przekładni zębatej
Autorzy:
Łazarz, B.
Peruń, G.
Powiązania:
https://bibliotekanauki.pl/articles/375262.pdf
Data publikacji:
2012
Wydawca:
Politechnika Śląska. Wydawnictwo Politechniki Śląskiej
Tematy:
przekładnia zębata
wibroaktywność
model dynamiczny
gearbox
vibroactivity
dynamic model
Opis:
The paper presents the results of numerical and experimental studies on the influence of selected factors on the dynamic effects and vibroactivity of the gearing. The studies were performed using a custom developed dynamic model of a test stand with the gears operating in the circulating power system.
Artykuł przedstawia wyniki badań symulacyjnych oraz laboratoryjnych mających na celu określenie wpływu wybranych czynników konstrukcyjnych na zjawiska dynamiczne i wibroaktywność przekładni zębatej. Badania numeryczne przeprowadzono z użyciem opracowanego modelu dynamicznego stanowiska z przekładniami pracującymi w układzie mocy krążącej.
Źródło:
Transport Problems; 2012, 7, 2; 95-102
1896-0596
2300-861X
Pojawia się w:
Transport Problems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A dynamic perspective on competition between traditional banking and banking fintechs
Konkurencja pomiędzy tradycyjną bankowością a fintechami bankowymi w ujęciu dynamicznym
Autorzy:
Chrzanowski, Marek
Dąbrowski, Ireneusz K.
Powiązania:
https://bibliotekanauki.pl/articles/1788494.pdf
Data publikacji:
2020
Wydawca:
Wydawnictwo Uniwersytetu Ekonomicznego we Wrocławiu
Tematy:
fintech
banking sector
dynamic model
sektor bankowy
model dynamiczny
Opis:
The emergence of innovative financial services is having a huge impact on competition in the banking services market. The aim of the article is to show, from a dynamic perspective, the foundations of a model of competition occurring in the banking world between traditional financial institutions and fintechs. A dynamic two-sector model of competition is proposed with built-in feedback mechanisms in the form of demand side economies of scale. The model shows changes in market shares after a challenger enters a bank’s market with a portfolio of services as substitutes for the bank’s product offer. The traditional and new entities do not adjust the scope of their products over time, instead competing using those already available. The model obtained three economically significant steady states. Further analysis of the time path showed that the sector is heading towards an oligopolistic market structure in which both entities stabilize their market shares. However, in the event of low initial market penetration by traditional banks, a new innovative entity (a challenger bank) will completely dominate the sector, creating a monopolistic market structure.
Silna konkurencja ze strony fintechów ma ogromny wpływ na konkurencję na rynku usług bankowych. Celem artykułu jest wskazanie modelowych podstaw zachodzącej w świecie bankowości gry konkurencyjnej pomiędzy tradycyjnymi instytucjami finansowymi a fintechami w ujęciu dynamicznym. Zaproponowano dynamiczny dwusektorowy model konkurencji z wbudowanymi mechanizmami sprzężeń zwrotnych w postaci popytowych korzyści skali. Model pokazuje zmiany w udziałach w rynku po wejściu na rynek challenger banku z substytucyjnym dla oferty banku portfolio usług. Tradycyjni i nowi gracze nie korygują zakresu swoich ofert w czasie, a do konkurowania jedynie używają już posiadanych w ofercie produktów. W modelu uzyskano trzy sensowne ekonomicznie stany stacjonarne. Dalsza analiza ścieżki czasowej pokazała, że gałąź dąży do oligopolistycznej struktury rynkowej, w której oba podmioty ustabilizują swoje udziały w rynku. W przypadku jednak niskiej początkowej penetracji rynku przez banki tradycyjne nowy innowacyjny podmiot (challenger bank) całkowicie zdominuje gałąź, tworząc monopolistyczną strukturę rynkową.
Źródło:
Prace Naukowe Uniwersytetu Ekonomicznego we Wrocławiu; 2021, 65, 2; 1-14
1899-3192
Pojawia się w:
Prace Naukowe Uniwersytetu Ekonomicznego we Wrocławiu
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The computational research of the dynamic load of the power train sites of the caterpillar tractor
Rasčetnye issledovaniâ dinamičeskoj nagryžennosti učastkov silovoj peredači guseničnogo traktora
Autorzy:
Shehovtsov, V.
Sokolov-Dobrev, N.
Shevtchuk, V. P.
Ljashenko, M. V.
Kalmikov, A.
Powiązania:
https://bibliotekanauki.pl/articles/263705.pdf
Data publikacji:
2013
Wydawca:
Sieć Badawcza Łukasiewicz. Przemysłowy Instytut Motoryzacji
Tematy:
dynamic load
power train
dynamic model
torsional vibration
caterpillar tractor
Opis:
The paper describes the developed dynamic model of the caterpiller’s power transmission. Its advantage is the integrated dimensional model of caterpillar propeller. Animated motion modeling provides the formation and transfer of kinematic and dynamic disturbances from caterpillar chassis, causing the greatest loadings of the power circuit sections. The principle of power transmission mathematical model’s differential equations forming is described. result of the model’s computational research is a set oscillograms of the drive wheel’s torque changing for different operating modes. The values of power transmission masses’ natural frequencies are obtained. The research of the nature of transmission sections’ dynamic loading by torsional vibrations, that arise and spread on the shafting, when the linked track rewinds, is carried out.
Źródło:
Archiwum Motoryzacji; 2013, 2; 79-91, 195-208
1234-754X
2084-476X
Pojawia się w:
Archiwum Motoryzacji
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Decreasing of dynamic loading of tractor’s powertrain by means of change of reactive element torsional stiffness
Autorzy:
Kalmikov, A. V.
Sokolov-Dobrev, N. S.
Shekhovtsov, V. V.
Ljashenko, M. V.
Potapov, P. V.
Powiązania:
https://bibliotekanauki.pl/articles/242814.pdf
Data publikacji:
2015
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
dynamic load
power train
dynamic model
torsional vibration
caterpillar tractor
Opis:
This article describes original method proposed by authors that provides decreasing of dynamic loading of tractor’s powertrain by means of change of reactive element torsional stiffness. In tracked vehicles one of the most loaded elements is final drive unit which loaded by high dynamic modes. In tractor Chetra 6C-315, final drive is epicyclic where stopped element is ring gear. Authors propose using of strictly resilient (5 degrees in forward-backward direction) mount of ring gear instead of stiffening. Design study of installation between hub and gear ring that connects drum and crown gear, of the resilient metal plates pack was performed. This pack is kind of elastic coupling. Resilient packets of coupling sustain loads and smooth over peak dynamic loads and after elastic deformation of these packets rigid coupling between hub and coupling crown is provided at contact surfaces of skewed stops of hub and crown. To analyse efficiency of proposed method of dynamic loadings decreasing of powertrain elements three-dimensional model of powertrain was created in “Universal Mechanism”. In addition, solid model of caterpillar mover was created in the same software for analysis of influence on powertrain loadings of complex of kinematic and dynamic factors influencing forming of torque on driving sprockets. This article presents results of modelling of loading processes in powertrains elements with elastic coupling and without it during longitudinal motion at various speeds and in turns with various radii. Results show that elements dynamic loading at high loading dynamic modes in case of installed coupling is decreased by 20-30%.
Źródło:
Journal of KONES; 2015, 22, 1; 127-134
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The research of the dynamic load of the power train of the caterpillar tractor Chetra 6C-315
Autorzy:
Shekhovtsov, V.
Sokolov-Dobrev, N.
Shevtchuk, V.
Liashenko, E.
Powiązania:
https://bibliotekanauki.pl/articles/244457.pdf
Data publikacji:
2011
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
dynamic load
power train
dynamic model
torsional vibration
caterpillar tractor
Opis:
The paper describes the developed dynamic model of the caterpiller's power transmission. Its advantage is the integrated dimensional model of caterpillar propeller. Animated motion modelling provides the formation and transfer of kinematic and dynamic disturbances from caterpillar chassis, causing the greatest loadings of the power circuit sections. The principle of power transmission mathematical model’s differential equations forming is described. Result of the model's computational research is a set of oscillograms of the drive wheel’s torque changing for different operating modes. The values of power transmission masses' natural frequencies are obtained. The research of the nature of transmission sections' dynamic loading by torsional vibrations, that arise and spread on the shafting, when the linked track rewinds, is carried out. The diagrams show that local maximums of dynamic coefficients characterize the regimes with high hook load. The increase of torques for these sections happens because of approximation of the peculiar frequency of the system and the frequency of one of the harmonic components of stimulating actions. At this peak, value of the oscillation belongs to the masses, the partial frequencies of which are closest to the frequencies to the stimulation actions. Dynamic load of such sections is quite high. The material of these sections often gets fatigue damage, which can lead to breakdown. The analysis of the diagrams, made for basic operation speeds between 1,0 – 5,5 m/sec showed, that maximal peak values of dynamic coefficients appear on sections between 10 and 59 masses in the transmission. Maximal dynamic load of these sections appear at hook load from 0 to 40 kN.
Źródło:
Journal of KONES; 2011, 18, 1; 535-546
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Matematicheskoe modelirovanie sistemy 'mekhanizm podema gruza - gruz - transportnoe sredstvo'
Mathematical modelling systems 'hoisting mechanism - load - vehicle'
Autorzy:
Lovejjkin, V.
Romasevich, J.
Goldun, V.
Powiązania:
https://bibliotekanauki.pl/articles/77320.pdf
Data publikacji:
2014
Wydawca:
Komisja Motoryzacji i Energetyki Rolnictwa
Tematy:
load-lifting crane
modelling
vehicle
dynamic model
equation
Źródło:
Motrol. Motoryzacja i Energetyka Rolnictwa; 2014, 16, 3
1730-8658
Pojawia się w:
Motrol. Motoryzacja i Energetyka Rolnictwa
Dostawca treści:
Biblioteka Nauki
Artykuł
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