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Wyświetlanie 1-11 z 11
Tytuł:
An attempt of the application of matching pursuit mp with Gabor dictionary for evaluation of ride comfort disturbance level
Autorzy:
Grzegożek, W.
Szczygieł, J.
Powiązania:
https://bibliotekanauki.pl/articles/242356.pdf
Data publikacji:
2009
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
comfort evaluation
comfort disturbances
matching pursuit
time-frequency dictionaries
Opis:
Ride comfort has always been considered to be essentialfor vehicle development. Nowadays it is one of aspects of wehicle industry that is getting more and more important. Disturbances in vehicle motion, for example drive across an obstacle or drive of a rail vehicle across the transition curve may be the reason for ride comfort disturbances. These excitation values may define the subjective negative comfort assessment by a passenger or a driver. Sudden changes of acceleration with low frequencies are particularly perceptible. That is why the attempts of evaluation of these disturbances are included in standards as PCT and PDE indexes for rail vehicles. In order to designate these indexes filtration of the recorded lateral acceleration runs is done. The values of changes of lateral acceleration, of lateral jerk and roll rate in time intervals are defined. This kind of analysis in which only the amplitudes of values measured were taken into account and in which 2 Hz filter was used may cause discrepancy between subjective assessment and evaluated level of vibration. Wavelet transform that is the tool of time-frequency analysis makes non-stationary signals such as acceleration signals in case of comfort disturbances possible. The problem of evaluation of vibration level that is basedon wavelet transform analysis appears. In order to evaluate this vibration level algorithm of matching pursuit MP may be used to match the mother wavelet to the recorded signal in the best way possible. The article presents an attempt of matching pursuit algorithm with Gabor dictionary for evaluation of the discomfort level that was based on the run recorded in the tram.
Źródło:
Journal of KONES; 2009, 16, 2; 149-158
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An attempt of an employment of a continuous wavelet transform for evaluation of temporary comfort disturbances
Autorzy:
Grzegożek, W.
Szczygieł, J.
Król, S.
Powiązania:
https://bibliotekanauki.pl/articles/244076.pdf
Data publikacji:
2009
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
ride comfort analysis
continuous wavelet transform (CWT)
vibration discomfort
comfort on discrete events
Opis:
This paper focuses on an attempt of an employment of a continuous wavelet transform as a tool of time-frequency analysis to identify and asses the comfort on discrete events. A short review of practical procedures for predicting vibration discomfort defined by ISO 2631-5 and BS 6041, ENV 12299 is enclosed. The results of research of tram temporary comfort disturbances are also described in the paper. The research enclosed the comfort on curve transitions and comfort on discrete events. Research was carried out in the old city centre as in this area there are a lot of curves and large number of excitations can be expected. An exemplary analysis of tram comfort using a continuous wavelet transform is presented. The signals in time intervals in which PCr and PDE indexes that have high values are analyzed. Moreover, the evaluation of comfort disturbances using wavelet transform based on Morlet mother wavelet is done. The continuous wavelet transform that was employed proves high usefulness of this method for assessment of temporary comfort disturbances. The results of Fourier transform of the signals measured are also presented in this article. Traditional methods based on the vibration dose value and frequency weighting methodsfor assessment of these vibrations are less useful in respect to non-stationary character of temporary disturbances.
Źródło:
Journal of KONES; 2009, 16, 1; 165-172
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The vehicle ride comfort increase at the expense of semiactive suspension system
Autorzy:
Podzorov, A.
Prytkov, V.
Cherkashina, E.
Liashenko, M.
Powiązania:
https://bibliotekanauki.pl/articles/244491.pdf
Data publikacji:
2011
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
vehicle
semi-active suspension
ride comfort
shock absorber
pneumatic spring
multidimensional model
Opis:
The problem of control by a semi-active suspension for increase a ride comfort of a vehicle is considered. On an example of multidimensional mathematical model of the bus, an efficiency of a semi-active suspension with controllable shock absorbers and pneumatic springs is analyzed. Results of computer simulation of movement of the bus with a semi-active suspension on road with a stochastic profile are presented. Calculations have been executed in the program of modelling of dynamics of systems solid and elastic bodies - FRUND. As conclusions it is possible to notice that the semiactive suspension with controlled under offered laws elastic and damper elements allows to depress considerably dynamic ability to loading spring vehicle parts, thereby, raising its stroke ride comfort, without deterioration of parameters influencing stability and movement roadability. Results of numerical experiment and offered laws of controlling can form a basis for creation structurally concerning simple semiactive suspension systems a not demanding for work of a significant amount of power. The semiactive suspension with controlled under offered laws elastic and damper elements allows depressing considerably dynamic ability to loading spring vehicle parts, thereby, raising its stroke ride comfort, without deterioration of parameters influencing stability and movement roadability.
Źródło:
Journal of KONES; 2011, 18, 1; 463-470
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal analysis of car air cooler
Autorzy:
Trzebiński, D.
Szczygieł, I.
Powiązania:
https://bibliotekanauki.pl/articles/242031.pdf
Data publikacji:
2011
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
car air conditioning
refrigerant
thermal comfort
thermodynamic cycle
Opis:
People more and more time spend in vehicles (cars, trains, planes, buses or subway). This is the reason why the thermal comfort has more and more paid attention. In one hand people try to make comfort (in each situation) whatever they are at home, office or in car. In the other hand the thermal conditions in the cabin of vehicles directly influences on the driver's and passengers safety. The investigations presented in this paper are the part of larger project, which assumes complex modelling of thermal state of car interior. First part assumes creation of CFD model of car interior. Second part is thermodynamic modelling of air cooling unit in order to estimate the influence of basic cabin parameters on the A/C unit COP, power consumption of the unit and fuel consumption of the vehicle. In the paper thermodynamic analysis of car air cooler is presented. Typical refrigerator cycles are studied: one with uncontrolled orifice and non controlled compressor, second with thermostatic controlled expansion valve and externally controlled compressor. The influence of refrigerant charge and the inlet air temperature on the coefficient of performance, exergy efficiency, heat flux and temperature in evaporator and compressor net power were investigated. The impact of improper refrigerant charge on the performance of A/C systems was also checked.
Źródło:
Journal of KONES; 2011, 18, 2; 439-446
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Solutions in the vehicle suspension
Autorzy:
Niculescu, Adrian Ioan
Jankowski, Antoni
Kowalski, Miroslaw
Sireteanu, Tudor
Powiązania:
https://bibliotekanauki.pl/articles/247026.pdf
Data publikacji:
2019
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
active suspension
semi-active suspension
comfort
stability
clearance
progressive cushions
VZN
Opis:
The paper presents a review of the suspension solutions used on the street vehicle up to the now a days, finalising with presentation of their damping characteristics and with evaluation of their advantages or disadvantages. Long time the suspension systems have been dominated by the classic passive suspensions realized with metallic springs, shock absorbers with constant damping coefficients and anti-roll bars, excepting some luxury and sport cars using semi-active and active suspensions. There are presented some semi-active suspension solutions with continuous or discontinuous damping characteristics adjustment and the evolution of the Citroen and other active suspensions. All of them improve in some matter the performances but all of them have not ability to recuperate energy and has auxiliary energy consumption so last period the electromagnetically shock absorbers are researched, the paper presenting some of them. The paper also presents magneto rheological MR damper, solutions for adjustable passive shock absorbers and solutions for passive shock absorbers with variable damping coefficient with the stroke, e.g. Monroe Sensa Trac, Citroën Solution and VZN solution, with their damping characteristics and performances.
Źródło:
Journal of KONES; 2019, 26, 4; 185-196
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Frequency analysis of vertical vibrations acting on a baby transported in a child car seat
Autorzy:
Więckowski, D.
Powiązania:
https://bibliotekanauki.pl/articles/244973.pdf
Data publikacji:
2013
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
baby in a car seat
vibration impact
ride comfort
human body vibration
Opis:
The biggest dangers that may result from human exposure to vibrations caused by vehicle movement occur in automotive transport [6]. The vibrations experienced during vehicle ride may cause a variety of pathological symptoms arising in people. The adverse health effects may also include reduced motion control, blurred vision, or impairment of the ability of free communication, memory processes, or perception [6]. The paper covers the impact of vertical vibrations on a baby riding in a safety seat in a car, with addressing in particular the dangers caused by mechanical vibrations to children in transport facilities. Two options were considered, with the safety seat being installed on either the front or rear car seat. Experimental road tests were carried out with using a dummy representing the baby. The lack of research work on this issue has been emphasised. For the sake of maximum safety, babies should be transported in safety seats. The type approval tests of child safety seats are chiefly focused on the evaluation of protection from harmful collision effects, according to UN ECE Regulation No. 44 [S13]. Regrettably, they do not include tests to determine the influence of vibrations, especially those occurring during “normal” ride, on the child’s body.
Źródło:
Journal of KONES; 2013, 20, 1; 359-366
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Forecasting of subjective comfort in tram using ordinal logistic regression and manifold learning
Autorzy:
Pietraszek, J.
Grzegożek, W.
Szczygieł, J.
Powiązania:
https://bibliotekanauki.pl/articles/246634.pdf
Data publikacji:
2012
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
rail transport
vibrations
ordinal logistic regression
principal component analysis
manifold learning
Opis:
Comfort in a vehicle has a very important role to play as one of the most important dynamic performance characteristics of rail vehicles. It is the factor of ever-increasing importance, even creating a specialized branch of engineering associated with relation between human limitations and designing of machines: human–factors engineering. The vibration is known to be a major factor that affects and deteriorates ride comfort. For evaluating ride comfort in rail vehicles, there have been developed methods resulting in the creation of many standards and multiple criteria used and even standardized in different countries. One of the authors, J. Szczygieł designed and performed a passive experiment to collect data describing physical conditions of ride and associated subjective assessments of comfort. Panel of fourteen people during the tram ride made synchronous subjective assessments of comfort, assessing it on a discrete ordinal scale of 0 to 5, using electronic panels connected to the computer. At the same time computer through sensors recorded values of acceleration in three perpendicular axes. It made possible to correlate the fuzzy subjective evaluations with objective physical measurements. Because of the discrete type of fuzzy ratings of comfort, natural way of modelling is the ordinal logistic regression. The classic form of the ordinal logistic regression assumes that in the space of explanatory factors there are parallel activation hyper-planes slightly disturbed by unknown or uncontrolled noise factors. In fact, the assumption of linearity is a very strong idealization and leads to considerable misclassifications. The original space of explanatory factors is 11-dimensional with ten continuous dimensions and one discrete. Then the multivariate method, principal component analysis (PCA), was used to identify principal components, which are responsible most to the variability of the studied set. The scree plot was used to identify the number of significant PCA factors. The use of PCA revealed that the area occupied by the data set is approximately 6-dimensional. However, the dimensionality reduction of explanatory variables set did not lead to better forecasting accuracy. A more subtle analysis involving discretization techniques showed that activation hyperplanes are highly curved in the six-dimensional area identified by PCA but their dimensionality is much lower. The details of the procedure are described in the article. The article conclusion is that is necessary to introduce curvilinear coordinate system embedded into the shapes of activation hyper-planes to obtain better classification.
Źródło:
Journal of KONES; 2012, 19, 2; 403-409
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Combined control of hydropneumatic springs of the vehicle
Autorzy:
Liashenko, M.
Podzorov, A.
Shekhovtsov, V.
Prytkov, V.
Cherkashina, E.
Powiązania:
https://bibliotekanauki.pl/articles/247202.pdf
Data publikacji:
2011
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
controlled suspension system
ride comfort
hydropneumatic spring
road tests
spatial mathematical model
vehicle
Opis:
The article is devoted to research of a vehicle ride comfort, equipped the suspension system with combined control of springing and damping elements. The spatial mathematical model of a vehicle which meets the requirements of adequacy to real object was developed. The results of the computer simulation of movement of the vehicle with controllable and passive suspension systems on stochastic microprofile are presented. It can be concluded that the spatial multi-mass model is satisfactory close to a real object and can be used for further calculations. Having analyzed simulation results we can state significant increase of ride comfort of a vehicle equipped with a controlled suspension system. Decrease of vertical acceleration of a cabin in a place where a driver sits amounted to 40% in average that can be considered as a limit value for this type of controlled suspension systems. It can be noted that a suspension system with combined control of springing and damping elements can be considered as rather effective in terms of decreasing load of vehicle spring-mounted parts that along with low power consumption makes it rather competitive. The shown research results and control laws for springing and damping elements can be used as a basis for development of relatively simple controlled suspension systems.
Źródło:
Journal of KONES; 2011, 18, 4; 229-234
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Advantages conferred by shock absorbers with cylindrical actuator application to landing gear
Autorzy:
Niculescu, A. I.
Jankowski, A.
Kowalski, M.
Sireteanu, T.
Powiązania:
https://bibliotekanauki.pl/articles/247256.pdf
Data publikacji:
2016
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
shock absorber
cylindrical actuator
simulation
comfort
load state
vehicle protection
pneumatic spring
Opis:
Shock absorber with cylindrical actuator is a new concept of integrated damper with floating device, in international patent application PCT/EP2016/061515, with wide application in road, rail and aerial vehicles. Comparative to the known solution with rubber sleeves or bellows, the new one is capable to work at more increased pressure being more compact and due to metallic cylinder is more reliable. The other important advantage consists of it applicability at any kind of shock absorber without any special preparation, the solution consisting of replacing the dust shield with a pneumatic cylinder sealed against rod with a gasket and sliding closed in the lower part by sealing element/s fitted in trough/troughs practiced in an annular body fastened against the outer cylinder. For a better behaviour the patent application contains and solutions with double sliding sealing working at high pressure and thus assuring enough floating forces to sustain the vehicle without standard metallic spring so it can be utilized successfully in aerial vehicles landing gear. By using displacement and pressure transducers and equipment of control and command, it becomes an active suspension. The paper presents the double sliding sealing solution and demonstrates, by simulation the advantages confer by this new solution of shock absorber with cylindrical actuator in landing gear. This purpose was realized a virtual suspension model on which simulated hard landing for vehicle load and unload states, for different pneumatic spring preloaded forces.
Źródło:
Journal of KONES; 2016, 23, 1; 255-262
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The research of influence of additional vibration isolators system on dynamics loads of passengers
Badania wpływu zastosowania dodatkowego układu wibroizolacji na obciążenia dynamiczne przewożonych osób
Autorzy:
Borkowski, W.
Hryciów, Z.
Powiązania:
https://bibliotekanauki.pl/articles/243364.pdf
Data publikacji:
2007
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
transport
pojazdy
zawieszenie
drgania
komfort jazdy
vehicles
suspension
vibration
ride comfort
Opis:
In the paper chosen questions relating to improvement of ride comfort of passengers in wheeled vehicles are described. The solution consisting on use additional vibration isolation system with rubber-metal connectors are introduced. The object of researches, researches stand and measuring apparatus are described. The experimental conditions are passed as well as speed of vehicle and applied roadblocks. In the paper the examples results of experimental researches are put as well as for determinist and random excitations. The vertical accelerations of car body with vertical accelerations of additional vibration isolation system are compared. Comparisons are achieved with using standard deviations of runs and RMS of accelerations. In the paper the influence of vibration in vertical and horizontal directions are estimated. Advantages of this type of system are passed as well. Diagram of vehicle with the researches stand, researches stand in vehicle, view of roadblocks, vertical acceleration and displacement of plate towards a car body for 30 km/h, vertical accelerations and RMS of vertical accelerations, transverse accelerations for unpaved road and 20 km/h are presented in the paper.
W pracy opisano wybrane zagadnienia dotyczące poprawy komfortu jazdy osób przewożonych w pojazdach samochodowych. Przedstawiono rozwiązanie polegające na zastosowaniu dodatkowego układu izolacji drgań zbudowane w oparciu o łączniki gumowo-metalowe. Opisano obiekt badań, stanowisko badawcze oraz zastosowaną aparaturę pomiarową. Podano również warunki prowadzenia badań eksperymentalnych, a w tym prędkości jazdy oraz stosowane przeszkody. W pracy zamieszczono przykładowe wyniki badań eksperymentalnych, otrzymanych zarówno dla wymuszeń deterministycznych oraz wymuszeń o charakterze losowym. Porównano przebiegi przyspieszeń pionowych nadwozia pojazdu z przyspieszeniami pionowymi dodatkowego układu wibroizolacji. Porównania dokonano przy wykorzystaniu odchyleń standardowych zarejestrowanych przebiegów oraz wartości skutecznych przyspieszeń. W pracy oceniono również wpływ drgań w kierunku pionowym, wzdłużnym i poprzecznym na komfort jazdy. Podano także korzyści wynikające ze stosowania tego typu układu. Schemat pojazdu ze stanowiskiem badawczym, stanowisko badawcze w pojeździe, widok przeszkody, przyspieszenia pionowe i przemieszczenie płyty względem nadwozia dla 30 km/h, przyspieszenia pionowe dla drogi nieutwardzonej i 20 km/h, wartości skuteczne przyspieszeń pionowych dla drogi nieutwardzonej i prędkości 20km/h, przyspieszenia w kierunku poprzecznym dla drogi nieutwardzonej i prędkości 20km/h są prezentowane w artykule.
Źródło:
Journal of KONES; 2007, 14, 3; 101-108
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Quarter car model to evaluate behaviour under road and body excitation
Autorzy:
Niculescu, A. I.
Jankowski, A.
Kowalski, M.
Sireteanu, T.
Powiązania:
https://bibliotekanauki.pl/articles/246970.pdf
Data publikacji:
2017
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
quarter car model
shock absorber
simulation
comfort
stability
clearance
road profile
external force
model samochodu
amortyzacja
symulacja
komfort
stabilność
luz
profil drogi
siła zewnętrzna
Opis:
The paper presents a quarter car model two degrees of freedom (wheel and body), with vertical guiding system, the model being equipped with suspension stroke limiters and with excitation by wheel and/ or by body. The model reproduces elastic and damping characteristics of wheel and of rebound and compression stopper bumpers, the spring elastic characteristic and the shock absorber damping characteristic on rebound and compression, function piston speed. The road profile is generated with simple or summation of harmonic functions, or by reproducing real roads. The forces acting on full vehicle body e.g. aerodynamic and inertial forces are reproduced in the proposed quarter model by vertical forces reduced to the analysed quarter part. Thus, the model can be used for evaluation the vertical and horizontal stability at acceleration, deceleration, pitch and roll, at aerial forces, the body ground clearance and the comfort. The model can evaluate the influence of the damping and elastic characteristics of suspension and wheel, of the static position, of the vehicle load state, of the road profile and of the external forces, to the vehicle behaviour
Źródło:
Journal of KONES; 2017, 24, 1; 265-273
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-11 z 11

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