Wyniki wyszukiwania - Biblioteka Nauki

1

Diagnosing a Vehicle's Suspension System on the Basis of the Non-Linear Effects of the Dynamic Response

100%

Dąbrowski Z. , Pankiewicz J.

Machine Dynamics Problems

|

2002

|

tom Vol. 26, No. 2/3

27-41

EN

In the paper the problem of using in the diagnostic task nonlinear effects is considered. The appearance of nonlinear resonances is directly related to the non-linear characteristics of the viscoelastic elements. The passenger car suspension as the object of experiment is used. The impact of the changes of the characteristic of the elastic and damping element of the vehicle's suspension on the dynamics of the chassis is examined.

2

Badania symulacyne wykorzystania symptomów nieliniowych w diagnostyce wibroakustycznej

100%

Dąbrowski Z. , Pankiewicz J.

|

1998

|

tom nr 11-12

29-32

EN

The autors analyse the problem of expansion of defects when the initial state of an object is precisely described by a linear model, white the non-linear effects increase with the process of wear. A method is proposed of solving the diagnostic taks by using as a symptom the vibration apmlitudes of non-harmonic resonances.

3

Komputerowo wspomagane układanie równań ruchu układu punktów materialnych (w środowisku programu Mathematica)

100%

Osiński Z. , Pankiewicz J.

Prace Instytutu Podstaw Budowy Maszyn / Politechnika Warszawska

|

1999

|

tom z. 19

5-11

PL

W pracy przedstawiono propozycję metody komputerowo wspomaganego układania równań ruchu układu punktów materialnych. Punktem wyjścia są równania we współrzędnych uogólnionych, będące równaniami równowagi układu sił działających na układ i sił d'Alemberta (bezwładności) układu. Część czynności wykonywana jest przez użytkownika, a część wykonuje komputer przy wykorzystaniu środowiska programu Mathematica.

EN

The paper presents proposed methods of computer aided designing of equations of motion of the system of material points. The starting point is the equations of generalised co-ordinates which are equations of equilibrium of the forces acting on the system and d'Alembert's forces (inertial forces) on the system. Part of the work is done by the user and part by computer using the Mathematica program.

4

Badania symulacyjne wpływu szumu losowego na czytelność symptomów nieliniowych

100%

Dąbrowski Z. , Pankiewicz J.

Przegląd Mechaniczny

|

2000

|

tom nr 11-12

35-37

EN

Results of examinations of the influence od external interference of a random noise character upon a possibility of using as diagnostic symptoms the elements of selected nonlinear effects. In the author's opinion the degree of nonlinearity of a system changes with the time of the machine operation and some nonlinear elements can be useful symproms in a detailed diagnosis. A computer simulation of the behaviour of a system with a varying characteristic of the elastic part at a random noise interference od a level varying within 30dB proves that distrubances of this type do not preclude a correct diagnosing.

5

Model aided design of tuned rubber TVD

80%

Pankiewicz J. , Chiliński B. , Wądołowski M.

Journal of KONES

|

2016

|

tom Vol. 23, No. 4

367--374

EN

The rotation of a crankshaft in piston combustion engines results from the acting of tangential forces on the crank, whose value changes with the change of the angle of shaft rotation. This results in torsional vibrations. These vibrations become especially dangerous when the frequency of changes of any components of tangential force is near or equal to the natural frequency of the shaft. It leads to resonant amplification of vibration amplitude and to exceeding the limit values of the angle of shaft torsion. Most often in such cases, various types of torsional vibration dampers are used. In automotive industry, these are usually rubber vibration dampers. Typical torsional vibration damper is an example of a resonant damper, which is designed for the most dangerous resonant frequency of the crankshaft related to the first form of vibration for which the torsional vibrations usually have the greatest amplitude. The design of such a damper involves choosing the inertia moment of the flywheel and the parameters of viscous-elastic element. The article describes the model and the simulation research, which allowed for creating the procedure of designing rubber dampers of torsional vibrations. This procedure can help to reduce the costs of operation tests for the design of optimal torsional vibration damper.

6

Zapalenie łożyska u klaczy - przyczyny, rozpoznawanie i leczenie

80%

Szklarz M. , Rokita M. , Pankiewicz J. , Janeczek M.

Magazyn Weterynaryjny

|

2020

|

tom 29

|

nr 09

7

Propozycja modelu gumowego tłumika drgań skrętnych

80%

Deuszkiewicz P. , Pankiewicz J. , Zawisza M.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

|

2015

|

tom z. 106

43

PL

Gumowe tłumiki drgań skrętnych są typowym przykładem tłumików rezonansowych, które „dostraja” się do najbardziej niebezpiecznej częstotliwości rezonansowej (o najwyższej amplitudzie kąta skręcenia). Modele liniowe takich tłumików nie uwzględniają nieliniowych właściwości gumy, co powoduje, że tłumik jest traktowany jak dynamiczny eliminator drgań. W referacie przedstawiono badania symulacyjne modelu tłumika drgań skrętnych uwzględniającego nieliniowe charakterystyki sprężystości i tłumienia. Autorzy wykazali silną zależność parametrów eksploatacyjnych tłumika od charakterystyk użytej do jego budowy gumy.

8

A proposition of a torsional-bending vibrations modelling of combustion engines

80%

Dąbrowski Z. , Chiliński B. , Pankiewicz J.

Journal of KONES

|

2016

|

tom Vol. 23, No. 4

71--77

EN

The article presents the problem of modelling coupled bending-torsional vibrations in crank systems. Because during the design of modern drive systems a growing number of phenomena are taken into account, model description of such vibrations has a practical meaning. Commonly used models of dynamics of systems assume the independence of torsional and bending vibrations, which leads to simultaneous analysis of transverse and angular vibrations. Further analysis is carried out with the use of superposition principle. Such an approach is justified in the case of quite rigid drive shafts, where vibrations are relatively small. Current trends in the design of reducing weight, reduction of toxic emissions and reducing fuel consumption, lead to the situation where shafts in crank systems become less stiff. Therefore, phenomena neglected earlier may have significant meaning. Analysis of couplings of transverse and torsional vibrations is so important that the occurrence of these phenomena usually leads to new critical states, which may be especially dangerous for engine operation. Considerations on the reasons of the occurrence and kinds of vibration couplings were presented in the introduction of the article. Further part of the article proposes the linear-bending model of the crankshaft, where transverse and angular displacements are dependent. It was tantamount to the assumption of linear relation between the vector of generalized co-ordinates and generalized forces occurring in the system. The next chapter presents the system of equations describing the dynamics of the crankshaft together with a discussion of the co-ordinate system used in the considerations. In addition, there were presented the results of numerical simulations in frequency domain confirming the conclusions taken from the analysis. The whole paper is concluded with synthetic conclusions on the formulated system of equations, simulations and the influence of the coupling on the dynamics of the whole crank system.

9

Analysis of bending-torsional vibrations for diagnostics of the crank system

80%

Burdzik R. , Pankiewicz J. , Wądołowski M.

Diagnostyka

|

2016

|

tom Vol. 17, No. 4

79--84

EN

The article presents the model of the crankshaft taking into account the coupling of bending and torsional vibrations. In engineering practice the simplification which is omitting this phenomenon is commonly used. Authors using more complicated model show the influence of bending torsional coupling on the frequency structure of the crank system.At the beginning of the article the problem of vibrations in combustion engine is generally discussed. Then there is presented the analysis of forces distribution in a crank system with the assumption that there is no friction in bearing nodes. Further chapters present two approaches to modeling torsional and bending vibrations in crank systems and indicate the application area of the proposed methodology. In the last but one chapter there were discussed the results of numerical simulations of the proposed model of the crank system. The whole was summarized with synthetic conclusions and plans regarding further research.

PL

Artykuł przedstawia model wału korbowego uwzględniający sprzężenie drgań giętnych i skrętnych. W praktyce inżynierskiej powszechnie stosuje się uproszczenie polegające na pominięciu tego zjawiska. Autorzy wykorzystując bardziej rozbudowany model, pokazują wpływ sprzężenia giętno-skrętnego na strukturę częstotliwościową układu korbowego. Na wstępie artykułu ogólnie omówiono zagadnienie drgań w silnikach spalinowych. Następnie przedstawiono analizę rozkładu sił w układzie korbowym przy założeniu braku tarcia w węzłach łożyskowych. Dalsze rozdziały prezentują dwa podejścia do modelowania drgań skrętnych i giętnych w układach korbowych oraz wskazują na obszar zastosowań proponowanej metodyki. W przedostatnim rozdziałe omówiono wyniki symulacji numerycznych zaproponowanego modelu układu korbowego. Całość podsumowano syntetycznymi wnioskami oraz planami odnośnie dalszych badań.

10

Safety in the railway industry

70%

Burdzik R. , Nowak B. , Rozmus J. , Słowiński P. , Pankiewicz J.

Archives of Transport

|

2017

|

tom Vol. 44, iss. 4

15--24

EN

Safety of the railway transport is extremely important issue, thus it has to be supported by numerous of terms. It is not only the legislation and organization or traffic control but also the proper quality of every devices in the railway infrastructure. The paper deals with safety in the rail industry. Companies and producers of railway equipment have to guarantee the best quality, maintenance and reliability. Safety is also a device directly responsible for protecting e.g. level crossings but also safety in terms of design and construction. Supervision of products is fulfilled in Poland by e.g. the Office of Railway Transport managing the safety and regulation of rail traffic. The paper presents industry security in terms of product as safety in design and production, in construction, in exploitation. Despite such extensive, multisector and multifaceted organizational, legal and technical safety structures in rail transport it is advisable to conduct further research into the analysis of the possibilities for improved safety. Also authors have assumed that for the improving of railway crossing safety level the support system for the traffic detection can be developed. To increase of the complex crossing safety level the support system has to be independent from current usage control devices, as axle counter block. Thus the paper presents concept of application of vibration wave propagation employing as source if information on train or car detection.

11

Nitric oxide mediates the mitogenic effects of insulin and vascular endothelial growth factor but not of leptin in endothelial cells

61%

Jozkowicz A. , Pankiewicz J. , Dulak J. , Partyka L. , Wybranska I. , Huk I. , Dembinska-Kiec A.

Acta Biochimica Polonica

|

1999

|

tom 46

|

nr 3

EN

The regulation of vascular wall homeostasis by nitric oxide (NO) generated by endothelium is being intensively studied. In the present paper, the involvement of NO in the vascular endothelial growth factor (VEGF), insulin or leptin-stimulated proliferation of human endothelial cells (HUVEC) was measured by [3H]thymidine or bromodeoxyuridine incorporation. VEGF and insulin, but not leptin, increased NO generation in HUVEC, as detected with ISO-NO electrode. Proliferation of HUVEC induced by leptin was not changed or was higher in the presence of L-Nω-nitro-L-arginine methyl ester (L-NAME) a nitric oxide synthase (NOS) inhibitor. In contrast, L-NAME blunted the proproliferative effect of VEGF and insulin. Furthermore, we demonstrated that, in human arterial smooth muscle cells (hASMC) transfected with endothelial NOS (eNOS) gene, the generation of biologically active VEGF protein was NO-dependent. Inhibition of NO generation by L-NAME decreased the synthesis of VEGF protein and attenuated HUVEC proliferation induced by conditioned media from transfected hASMC. Endothelium-derived NO seems to participate in VEGF and insulin, but not leptin, mitogenic activity. Additionally, the small amounts of NO released from endothelial cells, as mimicked by eNOS transfection into hASMC, may activate generation of VEGF in sub-endothelial smooth muscle cells, leading to increased synthesis of VEGF protein necessary for turnover and restitution of endothelial cells.