Wyniki wyszukiwania - Biblioteka Nauki

1

Comparative analysis of time constants in Solid Oxide Fuel Cell processes - selection of key processes for modeling power systems

100%

Milewski J. , Lewandowski J.

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tom Vol. 91, nr 1

1-5

EN

The article presents a comparative analysis of the time constants of the main processes in the SOFC. The analysis was used to determine those processes most relevant to the modeling of an energy system comprising a fuel cell. The hybrid system, in addition to the fuel cell, has other devices (such as compressors, turbines, heat exchangers, etc.) working with it that may limit permissible ranges of parameter changes during transient processes. On the other hand, fuel cells affect other devices making up the system, including by restricting their operation in terms of dynamic responses. Determination of time constants of the main processes in the cell and their analysis and comparison with time constants of other devices will allow selection of the most important processes from modeling point of vies and simplify the dynamic fuel cell model, so the class of fuel cell will match classes of models of other system elements.

2

Understanding the Structural Complexity of Induced Travel Demand in Decision-Making: A System Dynamics Approach

100%

Angarita-Zapata J. S. , Parra-Valencia J. A. , Andrade-Sosa H. H.

Organizacija

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2016

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tom 49

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nr 3

129-143

EN

Background and purpose: Induced travel demand (ITD) is a phenomenon where road construction increases vehicles’ kilometers traveled. It has been approached with econometric models that use elasticities as measure to estimate how much travel demand can be induced by new roads. However, there is a lack of “white-box” models with causal hypotheses that explain the structural complexity underlying this phenomenon. We propose a system dynamics model based on a feedback mechanism to explain structurally ITD. Methodology: A system dynamics methodology was selected to model and simulate ITD. First, a causal loop diagram is proposed to describe the ITD structure in terms of feedback loops. Then a stock-flows diagram is formulated to allow computer simulation. Finally, simulations are run to show the quantitative temporal evolution of the model built. Results: The simulation results show how new roads in the short term induce more kilometers traveled by vehicles already in use; meanwhile, in the medium-term, new traffic is generated. These new car drivers appear when better flow conditions coming from new roads increase attractiveness of car use. More cars added to vehicles already in use produce new traffic congestion, and high travel speeds provided by roads built are absorbed by ITD effects. Conclusion: We concluded that approaching ITD with a systemic perspective allows for identifying leverage points that contribute to design comprehensive policies aimed to cope with ITD. In this sense, the model supports decision- making processes in urban contexts wherein it is still necessary for road construction to guarantee connectivity, such as the case of developing countries.

3

Analysis of nodalization effects on the prediction error of generalized finite element method used for dynamic modeling of hot water storage tank

100%

Wołowicz M. , Kupecki J. , Wawryniuk K. , Milewski J. , Motyliński K.

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4

Metody tworzenia modeli dynamiki mobilnych robotów kołowych

100%

Trojnacki M.

Modelowanie Inżynierskie

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2013

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tom T. 17, nr 48

150--161

PL

W pracy zaprezentowano stosowane w literaturze metody tworzenia modeli dynamiki mobilnych robotów kołowych. Omówiono zalety, wady i ograniczenia poszczególnych metod oraz problemy związane z modelowaniem dynamiki takich układów. Opisano autorską, uniwersalną metodykę tworzenia modelu dynamiki dla mobilnych robotów kołowych opartą na formalizmie Newtona-Eulera. Opracowana metodyka umożliwia kompleksowe podejście do modelowania dynamiki mobilnych robotów kołowych, pozwalając na opracowanie modeli dynamiki dla dowolnej liczby kół stykających się z podłożem i na uwzględnienie w modelu występowania poślizgów kół jezdnych.

EN

In this paper, the methods of development of dynamics models of wheeled mobile robots are presented. Advantages, drawbacks and limitations of particular methods as well as problems associated with modeling of dynamics of such systems are discussed. The original universal methodology of development of the analytical dynamics model of wheeled mobile robots based on Newton-Euler formalism is described. It enables a comprehensive approach to modeling of dynamics of wheeled robots by providing means to develop models for any number of wheels being in contact with the ground and by taking into account the occurrence of wheels’ slips.

5

Dynamiczne modele mikroperiodycznych ośrodków piezoelektrycznych

100%

Woźniak M. , Pauk R.

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tom Vol. 19

301--302

6

Dynamic Modeling of Planetary Vehicle’s Fall on Soft Soil

100%

Shibly H.

Journal of Automation Mobile Robotics and Intelligent Systems

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2016

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tom Vol. 10, No. 3

22--28

EN

The objective of future planetary mission is to explore more new zones on Mars planet. This goal may be achieved by using high speed planetary vehicle, (Rover). The motion of planetary vehicles at high speed and on unknown terrain increases the number of possible risks. One risk is a sudden change of ground level in the vehicle path causes a fall down onto a low ground. This paper presents a study and simulation of the dynamic response of a free fall of a quarter vehicle (rover) model with rigid wheel on a soft soil. A simplification of Bekker’s equation is derived and used in the numerical solution of the two coupled dynamic equations of motion. The Dynamic response of the unsprung mass, rigid wheel, shows a three stages; the sinkage stage, the equilibrium stage, and the pulling out stage from soil. The simulation shows that having rigid body mode helps in pulling out the vehicle wheel from the soil. It shows that the first three stages of the first fall are the most significant ones. They have the largest sinkage, largest impulsive force, and largest amplitude of the system dynamic response during interaction of the rigid wheel and the soft soil following the free fall. The existence of a damping reduces the dynamic response magnitude and prevent the unsprung mass from pulling out the wheel from soil after sinkage.

7

Backstepping sliding mode controller improved with fuzzy logic: Application to the quadrotor helicopter

100%

Zeghlache S. , Saigaa D. , Harrag A. , Kara K. , Bouguerra A.

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tom Vol. 22, no. 3

315-342

EN

n this paper we present a new design method for the fight control of an autonomous quadrotor helicopter based on fuzzy sliding mode control using backstepping approach. Due to the underactuated property of the quadrotor helicopter, the controller can move three positions (x;y; z) of the helicopter and the yaw angle to their desired values and stabilize the pitch and roll angles. A first-order nonlinear sliding surface is obtained using the backstepping technique, on which the developed sliding mode controller is based. Mathematical development for the stability and convergence of the system is presented. The main purpose is to eliminate the chattering phenomenon. Thus we have used a fuzzy logic control to generate the hitting control signal. The performances of the nonlinear control method are evaluated by simulation and the results demonstrate the effectiveness of the proposed control strategy for the quadrotor helicopter in vertical flights.

8

Introduction to dynamic modeling of rack stackers for high-bay warehouse

100%

Hajdu S. , Tiba Z.

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2009

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tom Nr 10

15-23

EN

Results of this paper indicated that there are many ways of modelling the planar vibration of single mast rack stacker machines, which approximate features of a real structure with different accuracy. These models are usable well for control examinations and for linear control design. However, by the determination of the model, besides the accuracy, the model shouldn't be too complicated and calculation demanding.

9

An innovative method for stress analysis of Y25 bogie under oscillating loads due to tank wagon fluid sloshing

88%

Rezvani M. A. , Feizi M. M. , Shadfar M.

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2014

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tom Vol. 52 nr 3

745--755

EN

Freight wagons carry higher axle loads and may travel along tracks of lower quality. This can be interpreted as higher dynamic loading of freight bogies especially for tanker cars that are subjected to sloshing loading. Rail irregularities, particularly during braking and running on curved tracks initiate the fluid sloshing. This article is about introducing an innovative method for analyzing bogie stresses of tanker cars while in travel and under critical circumstances. The effect of the vehicle speed of travel, its liquid filling ratio, track quality and fluid density are also investigated in terms of stress results of bogies.

10

Dynamic modeling of the isoamyl acetate reactive distillation process

88%

Ali S. S. , Hossain S. S. , Asif M.

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2017

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tom Vol. 19, nr 1

59--66

EN

The cost-effectiveness of reactive distillation (RD) processes makes them highly attractive for industrial applications. However, their preliminary design and subsequent scale-up and operation are challenging. Specifically, the response of RD system during fluctuations in process parameters is of paramount importance to ensure the stability of the whole process. As a result of carrying out simulations using Aspen Plus, it is shown that the RD process for isoamyl acetate production was much more economical than conventional reactor distillation configuration under optimized process conditions due to lower utilities consumption, higher conversion and smaller sizes of condenser and reboiler. Rigorous dynamic modeling of RD system was performed to evaluate its sensitivity to disturbances in critical process parameters; the product flow was quite sensitive to disturbances. Even more sensitive was product composition when the disturbance in heat duties of condenser or reboiler led to a temperature decrease. However, positive disturbance in alcohol feed is of particular concern, which clearly made the system unstable.

11

Problems of modelling of ITS services in transportation models

75%

Karoń G. , Mikulski J.

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tom Vol. 11, iss. 3

30--34

EN

Paper presents important issues related to macroscopic/strategic transportation modelling for ITS projects – utility function and perceived travel time for mode choice in macroscopic model.

12

Modelowanie sztywności koła podatnego przekładni falowej

75%

Folęga P. , Wojnar G.

Zeszyty Naukowe. Transport / Politechnika Śląska

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2010

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tom z. 67

39-44

PL

W artykule omówiono niektóre aspekty modelowania dynamicznego przekładni falowej. W szczególności zaproponowano nowy, oryginalny model dynamiczny przekładni falowej w układzie napędowym. W modelu uwzględniono nieliniowe zmiany sztywności i tłumienia.

EN

In the paper some aspects of harmonic drive gear modeling of dynamic are consider. At particular of the propose a new original dynamic model of harmonic drive gear in power trans-mission system. In the model we take into consideration a nonlinear stiffness and damping.

13

Dynamiczne modele dwuparametrowe sprężystego klina

75%

Marzęda J. , Pauk W.

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tom Vol. 19

209--210

14

Badanie numeryczne materiału przeciwwstrząsowego na podstawie próby swobodnego spadku opakowania

75%

Osowski P. , Piątkowski T.

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2016

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tom R. 17, nr 6

1469--1472

PL

Artykuł dotyczy modelowania właściwości dynamicznych elementów przeciwwstrząsowych opakowania w środowisku LS-DYNA. Zaproponowano metodę wyznaczenia charakterystyki dynamicznego ściskania materiału niejednorodnego na podstawie próby swobodnego spadku z zadanej wysokości. Wyniki badań numerycznych i doświadczalnych są zadowalająco zgodne. Zachęcają do dalszego rozwijania metody opisu właściwości dynamicznych materiałów przeciwwstrząsowych, ukierunkowanej na minimalizację nakładu badań doświadczalnych.

EN

The paper concerns the dynamic properties modeling of package cushioning elements in LS-DYNA environment. The method to determine the dynamic compression characteristic of heterogenic material with the use of the free fall test from height was proposed. The numerical results and experimental ones are acceptably congruent. They encourage to further method development to determine the dynamic properties of cushion materials, focused on minimization of experimental research time and cost.

15

Towards energy-aware cyber-physical systems verification and optimization

63%

Soltani R. , Kang E.-Y. , Heredia Mena J. E.

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2021

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tom Vol. 26

205--210

EN

Optimizing CPS behavior in terms of energy consumption can have a significant impact on system reliability. The environment influences the system's behavior, and neglecting the environmental behavior has indirect negative impact on optimizing the system's behavior. In this work, to increase the system's flexibility, the behavior of the environment is modeled dynamically to apply the disorderliness of its behavior. The resulting models are formally verified. By examining the past environmental behavior and predicting its future behavior, energy optimization is done more dynamically. The verification results acquired using a UPPAAL-SMC show that the optimization of system behavior by predicting the environmental behavior has been successful. Our approach is demonstrated using a case study within an I4 setting.

16

Solution of the Kalman filtering problem in control and modeling of a double inverted pendulum with rolling friction

51%

Olejnik P. , Awrejcewicz J. , Niełaczny M.

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2013

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tom R. 17, nr 1

63-70

EN

The problem of control and dynamical modeling of a unicycle-cyclist system treated as a double inverted pendulum with rolling friction and vibrating in the plane that is perpendicular to the direction of movement is studied. The object of analysis consists of two basic parts: the wheel and the double pendulum. The equations of motion have been derived using the Lagrange equation of the second kind. The kinematic excitation has been applied to the cyclist. The aim of control is to maintain the unicyclecyclist system in an unstable equilibrium around given angular position. Control moment of force has been applied to the wheel in a numerical procedure performed in Simulink. Kalman filtering problem has been solved basing on the feedback control system and functions included in Control System Toolbox of MATLAB. The proposed approach could be extended in future to solve some dynamical problem of transverse vibrations.

PL

Praca podejmuje rozwiązanie zagadnienia kontroli i modelowania dynamicznego układu monocykl-rowerzysta rozpatrzonego jako podwójne wahadło odwrócone z tarciem tocznym drgające w płaszczyźnie prostopadłej do kierunku ruchu. Analizowany obiekt składa się z dwóch podstawowych części, tzn. koła i podwójnego wahadła. Równania ruchu układu mechanicznego, w którym wymuszenie kinematyczne przyłożono do masy reprezentującej ciało rowerzysty wyprowadzono stosując równania Lagrange’a drugiego rodzaju. Zadaniem kontroli było utrzymanie modelu układu monocykl-rowerzysta w niestabilnym położeniu równowagi w pobliżu zadanej wartości kąta obrotu. W procedurze numerycznej zrealizowanej w Simulinku moment siły kontroli przyłożono do koła napędzającego układ modelowy. Zagadnienie doboru filtru Kalmana rozwiązano w układzie sterowania ze sprzężeniem zwrotnym przy użyciu wbudowanych funkcji numerycznych wchodzących w skład biblioteki Control System Toolbox pakietu MATLAB. Zaproponowane podejście można rozszerzyć w przyszłości w celu rozwiązania podobnego problemu dynamicznego uwzględniającego drgania poprzeczne.