PL
 |
EN
Nowa wersja platformy, zawierająca wyłącznie zasoby pełnotekstowe, jest już dostępna.
Przejdź na https://bibliotekanauki.pl
Preferencje help
Polish version English version Język
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 9

Liczba wyników na stronie
first rewind previous Strona / 1 next fast forward last
Wyniki wyszukiwania
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 1 next fast forward last
1
Content available Influence of thermosensitivity of materials on the temperature of a pad/disc system
100%
Grześ P.
Acta Mechanica et Automatica
|
2011
|
tom Vol. 5, no. 4
46-53
EN
A heat generation problem due to friction in a pad/disc brake system is studied. A linear problem is confronted and compared with a non-linear in which thermophysical properties of materials are temperature-dependent. To examine temperature of the pad and the disc during a single and a twofold braking process, axisymmetric FE contact model was used. The obtained results revel insignificant temperature differences at specified axial and radial positions of the components of the friction pair. It was remarked that the level of discrepancies between the constant and the thermosensitive materials correspond with the coefficient of thermal effusivity.
2
Content available Partition of Heat in 2D Finite Element Model of a Disc Brake
100%
Grześ P.
Acta Mechanica et Automatica
|
2011
|
tom Vol. 5, no. 2
35-41
EN
In this paper nine of formulas (theoretical and experimental) for the heat partition ratio were employed to study the temperature distributions of two different geometrical types of the solid disc brake during emergency brake application. A two-dimensional finite element analysis incorporating specific values of the heat partition ratios was carried out. The boundary heat flux uniformly distributed over the circumference of a rubbing path to simulate the heat generated at the pad/disc interface was applied to the model. A number of factors over the heat partition ratio that affects the temperature fields are included and their importance is discussed.
3
Content available Finite element analysis of temperature distribution in axisymmetric model of disc brake
100%
Grześ P.
Acta Mechanica et Automatica
|
2010
|
tom Vol. 4, no. 4
23-28
EN
A transient thermal analysis is developed to examine temperature expansion in the disc and pad volume under simulated operation conditions of single braking process. This complex problem of frictional heating has been studied using finite element method (FEM). The Galerkin algorithm was used to discretize the parabolic heat transfer equation for the disc and pad. FE model of disc/pad system heating with respect to constant thermo-physical properties of materials and coefficient of friction was performed. The frictional heating phenomena with special reference to contact conditions was investigated. An axisymmetric model was used due to the proportional relation between the intensity of heat flux perpendicular to the contact surfaces and the rate of heat transfer. The time related temperature distributions in axial and radial directions are pre- sented. Evolution of the angular velocity and the contact pressure during braking was assumed to be nonlinear. Presented transient finite element analysis facilitates to determine temperature expansion in special conditions of thermal contact in axisymmetric model.
4
Content available Finite element analysis of disc temperature during braking process
100%
Grześ P.
Acta Mechanica et Automatica
|
2009
|
tom Vol. 3, no. 4
36-42
EN
The aim of this paper was to investigate the temperature fields of the solid disc brake during short, emergency braking. The standard Galerkin weighted residual algorithm was used to discretize the parabolic heat transfer equation. The finite element simulation for two-dimensional model was performed due to the heat flux ratio constantly distributed in circumferential direction. Two types of disc brake assembly with appropriate boundary and initial conditions were developed. Results of calculations for the temperature expansion in axial and radial directions are presented. The effect of the angular velocity and the contact pressure evolution on temperature rise of disc brake was investigated. It was found that presented finite element technique for two-dimensional model with particular assumption in operation and boundary conditions validates with so far achievements in this field.
5
Content available Numerical analysis of temperature field in a disc brake at different cover angle of the pad
100%
Grześ P.
|
2014
|
tom Vol. 8, no. 4
185--188
EN
In the paper an influence of the cover angle of the pad on temperature fields of the components of the disc brake is studied. A three-dimensional finite element (FE) model of the pad-disc system was developed at the condition of equal temperatures on the contacting surfaces. Calculations were carried out for a single braking process at constant deceleration assuming that the contact pressure corresponds with the cover angle of the pad so that the moment of friction is equal in each case analysed. Evolutions and distributions of temperature both for the contact surface of the pad and the disc were computed and shown.
6
Content available Convective Cooling of a Disc Brake During Single Braking
63%
Adamowicz A. , Grześ P.
Acta Mechanica et Automatica
|
2012
|
tom Vol. 6, no. 2
5-10
EN
This study is primarily focused on the investigation of an impact of heat transfer coefficient on heat dissipation from the solid disc using the finite element method (FEM). The analysis was carried out within four individual cases of braking of the passenger vehicle simulating mountain descent with different velocities and the following release periods, where the convective terms of cooling were dependent on the angular velocity of the disc. For the purpose of confronting contrasting conditions of the braking action, apart from heating region, the whole surface of the disc was insulated. The process was performed under the operation conditions of a real front disc brake, whose dimensions and thermophysical properties of materials were adopted and applied to the FE model. It was concluded that the influence of cooling of the exposed surfaces of the disc during relatively short braking is insignificant. However the period after brake release results in considerable decrease in temperature of the disc.
7
Stacja do odbioru danych meteorologicznych na potrzeby planowania misji bezzałogowych statków powietrznych
51%
Grześ M. , Grześ P. , Sadowski M.
Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne
|
2016
|
tom nr 6
417--420, CD
PL
Planowanie misji z wykorzystaniem bezzałogowych statków powietrznych wymaga od operatora kompleksowej wiedzy na temat warunków panujących na całej trasie przelotu. Dzięki fuzji danych pochodzących z lokalnej stacji meteorologicznej oraz ze zdjęć odebranych z satelity meteorologicznego możliwy jest optymalny dobór parametrów nawet długoterminowych misji. Referat przedstawia projekt budowy małej, niezależnej stacji do odbioru zdjęć satelitarnych z wykorzystaniem radia programowalnego, komputera jednopłytkowego oraz zasilania z paneli słonecznych.
EN
Mission planning of unmanned aerial vehicles requires complex information about environmental conditions in airway. Thanks to a merging data from local weather station and satellite’s images it is possible to optimize even longterm mission parameters. This paper describes a project of a small, independent ground station for receiving images from weather satellites due to software defined radio, single board computer and solar panel power supply.
8
Content available Picosecond mode-locked tm-doped fibre laser and amplifier system providing over 20 W of average output power at 1994 nm
51%
Grześ P. , Michalska M. , Świderski J.
|
2018
|
tom Vol. 25, nr 4
649--658
EN
A mode-locked Tm3+-doped fibre laser and amplifier operating at a central wavelength of 1994.3 nm is demonstrated. A thulium oscillator is passively mode-locked by a semiconductor saturable absorber mirror to generate an average power of 17 mW at a fundamental repetition rate of 81 MHz in a short linear cavity. This 2-μm laser train is amplified to an average power to 20.26 W by two double-clad thulium-doped all-fibre amplifiers. The pulse energy, duration and peak power is 250 nJ, 23 ps and 9.57 kW, respectively. This represents one of the highest values of average power at ~2-μm-wavelength for picosecond thulium-doped fibre lasers and amplifiers. The performance of the laser system is described in details.
9
Światłowodowy generator promieniowania supercontinuum dużej mocy w zakresie widmowym 1,9-2,65 μm
51%
Michalska M. , Grześ P. , Świderski J.
|
|
tom Vol. 59, nr 3
39--43
PL
W artykule przedstawiono światłowodowy układ laserowy generujący promieniowanie supercontinuum o mocy 8,76 W w zakresie widmowym 1,9-2,65 μm, z czego 2,44 W mocy promieniowania odpowiada falom dłuższym niż 2,4 um. Układ został opracowany na bazie jednostopniowego światłowodowego wzmacniacza tulowego pompowanego ciągiem impulsów o czasie trwania 1 ns powtarzanych z częstotliwością 500 kHz, o długości fali 1,55 μm. Długoterminowy pomiar stabilności generacji promieniowania opracowanego układu wykazał fluktuacje mocy wyjściowej poniżej 3%.
EN
The article presents a fiber supercontinuum generator delivering 8.76 W of average output power in a spectral band of ~1.9-2.65 μm out of which 2.44 W corresponded to wavelengths longer than 2.4 μm. A 1.55 μm pulsed laser system delivering 1 ns pulses at a pulse repetition frequency of 500 kHz was used as a seed source for a one-stage thulium-doped fiber amplifier. A long- term power stability test showed power fluctuations of < 3%.
first rewind previous Strona / 1 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.