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1

Parameter identification of the basset force acting on particles in fluid flow induced by the oscillating wall

Pavlenko Ivan, Liaposhchenko Oleksandr, Pitel Jan, Sklabinskyi Vsevolod

Journal of Applied Mathematics and Computational Mechanics

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2019

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Vol. 18, nr 2

53--63

EN

The article is aimed at the development of the analytical approach for evaluating the parameters of the Basset force acting on a particle in two-dimensional fluid flow induced by the oscillating wall. By applying regression analysis, analytical expressions to determine complementary functions were established for evaluating the Basset force. The obtained dependencies were generalized using the infinite power series. As a result of studying the hydrodynamics of a two-phase flow, analytical dependencies to determine the Basset force were proposed for assessing its impact on particles of the dispersed phase in a plane channel with the oscillating wall. It was discovered that the Basset force affects larger particles. However, in the case of relatively large wavelengths, its averaged value for the vibration period is neglected. Additionally, the value of the Basset force was determined analytically for the case of relatively small wavelengths. Moreover, it was discovered that its impact can be increased by reducing the wavelength of the oscillating wall.

2

The vibration of the friction pads of disc brake in the aspect of changing the coefficient of friction

Sawczuk W.

Pojazdy Szynowe

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2017

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Nr 1

62--68

EN

Attempt to raise train speed involves application of greater braking power i.e. braking systems rapidly absorbing and dispersing stored heat energy. Work instability arises from the occurrence of vibrations on friction element, which affects the lower efficiency of the braking process. In practice, this means that, during braking the vehicles currently alternative at a time of friction resistance may cause uneven braking process. The effects of these changes can manifest in the form of vibrations the high amplitude of the input. The purpose of this article is to present the relationship between the changes in instantaneous coefficient of friction of the disk brake and the changes in instantaneous accelerations of the vibrations of the friction pad during braking.

PL

W pojazdach szynowych ze względu na coraz to większe prędkości jazdy prowadzi się prace nad udoskonalaniem układów hamulcowych tak, aby zatrzymanie pojazdu odbyło się na możliwie najkrótszej drodze hamowania. Niestabilność pracy wynika między innymi z występowania drgań na styku elementów ciernych, co wpływa na obniżenie sprawności procesu hamowania. W praktyce oznacza to, że podczas hamowania pojazdów występujący zmienny w czasie opór tarcia może być powodem nierównomiernego przebiegu procesu hamowania. Skutki tych zmian mogą objawić się w postaci drgań samowzbudnych. Celem artykułu jest przedstawienie związku zmian chwilowego współczynnika tarcia hamulca tarczowego ze zmianami chwilowych przyspieszeń drgań okładziny ciernej w czasie hamowania.

3

Pregnant women when riding in a motor car – selected issues

Więckowski D., Jaśkiewicz M.

Zeszyty Naukowe / Akademia Morska w Szczecinie

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2014

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nr 39 (111)

169--174

EN

The issue of passive safety of pregnant women travelling by car has been discussed. The pregnant woman’s body has been considered as a complex dynamic system subject to various impacts that take place during a car ride. In the field of motorization, much attention is paid (and rightly so) to the issue of safety of pregnant women travelling by car in consideration of road accidents. Motor vehicle accidents are the most important cause of death of pregnant women, according to data published by the National Highway Traffic Safety Administration (NHTSA). In the USA, about 130 000 pregnant women being in the second half of their pregnancy are annually involved in motor vehicle accidents. In this paper, some example solutions have been presented that are to improve the passive safety of riding in a motor car, including those proposed to minimize the injuries that may be sustained in result of an accident. The issue of the possible negative effects of a road accident or collision on a pregnant woman has also been raised. The application of virtual techniques has been discussed and examples of modelling a pregnant woman have been shown. Some research results concerning the deceleration values that might be dangerous for pregnant women have been given, with reference having been made to statistical data on fatal accidents.

4

Metody ograniczania wpływu drgań podłoża na konstrukcje inżynierskie

Targosz J.

TTS Technika Transportu Szynowego

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2013

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R. 20, nr 10

3203--3212

PL

Problem ograniczenia wpływu drgań podłoża na konstrukcje inżynierskie, jest niezwykle złożony, głównie z powodu braku ścisłego opisu matematycznego uwzględniającego niejednorodność gruntu. Powoduje to, że sposób rozchodzenia się fali drganiowej w podłożu od źródła drgań do obiektu inżynierskiego, nie jest w pełni poznany. W pracy przedstawiono metodologię podejścia do analizy propagacji fali drganiowej w gruncie, możliwości ograniczenia wpływu drgań podłoża na konstrukcje inżynierskie oraz stosowane rozwiązania systemów wibroizolacji w kraju i na świecie.

EN

Reducing the impact of ground vibration on engineering structures is extremely complex, mainly because of the heterogeneity of soil which results in the lack of accurate mathematical description of the vibrational waves propagation in the ground from the source of vibration to the object. In the paper a methodology of approach to the analysis of vibration wave propagation in the soil, potential for reducing the impact of ground vibration on structures and engineering solutions of vibration isolation systems in the country and the world are presented.

5

Frequency analysis of vertical vibrations acting on a baby transported in a child car seat

Więckowski D.

Journal of KONES

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2013

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Vol. 20, No. 1

359--366

EN

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.