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Article
Publication date: 9 January 2017

Catalin Pirvu, Laura Maftei, Constantin Georgescu and Lorena Deleanu

This paper aims to present the influence of glass bead concentration in a matrix of polyamide on wear and several three-dimensional (3D) parameters of the surface texture when the…

96

Abstract

Purpose

This paper aims to present the influence of glass bead concentration in a matrix of polyamide on wear and several three-dimensional (3D) parameters of the surface texture when the composite is sliding on steel in dry contact.

Design/methodology/approach

There were mold disks with the following concentrations in glass beads: 2.5, 5.0, 10, 20, 30 and 50 per cent. The mix of glass beads has diameters in the range of several microns to 50 microns. Tests were done on a pin-on-disk tribotester, in dry regime, for the following parameters: average pressure (1, 2 and 3 MPa) and sliding speed (0.5, 1.0 and 1.5 m/s). Zones of 500 × 500 μm were investigated from worn tracks generated on the composite disks, and the average values of several 3D texture parameters were analyzed.

Findings

The authors plotted maps indicating no correlation between the glass bead concentration and the parameters characterizing the surface quality (amplitude parameters and functional parameters). Composites with concentrations of 10[…]30 per cent glass beads generated worn surfaces with better quality as compared to composites with extreme concentrations: low (2.5 and 5 per cent) and high (50 per cent).

Practical implications

This set of parameters allows for evaluating the influence of regime parameters on the surface quality, by comparing the obtained values before and after sliding, and this evolution of roughness parameters could give recommendations for selecting the friction couple of materials for particular contacts that function with repeated starts and stops.

Originality/value

The results encourage the researchers to use a set of 3D texture parameters instead of “classical” two-dimensional parameters, the arithmetic mean deviation of the profile, Ra, because this set of parameters better evaluate the surface quality, especially for worn surfaces.

Details

Industrial Lubrication and Tribology, vol. 69 no. 1
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 30 December 2021

Lorena Deleanu, Traian Florian Ionescu, George Catalin Cristea, Cornel Camil Suciu and Constantin Georgescu

This paper aims to present an analysis of several 3 D texture parameters for the entire wear scars obtained in severe regime, on a four-ball tester. The aim of this analysis is to…

71

Abstract

Purpose

This paper aims to present an analysis of several 3 D texture parameters for the entire wear scars obtained in severe regime, on a four-ball tester. The aim of this analysis is to correlate the tribological parameter as wear scar diameter to texture parameters.

Design/methodology/approach

Tested lubricants were rapeseed oil, rapeseed oil additivated with 1% Wt nano TiO2 and rapeseed oil additivated with 1%Wt nano ZnO. The severe regime was applied for 1400 rpm and for loads increasing in steps of 50 N, from 500 to 900 N. Several analyzed roughness parameters (height parameters and functional ones) could be related to the evolution of a wear parameter, the wear scar diameter. Comparing the values for neat rapeseed oil and additivated variants, the texture parameters allow for evaluating if the additives protect or not the worn surfaces.

Findings

Measurements pointed out two groups of roughness parameters: one that has an evolution depending on wear scar diameter (WSD) and load (Sa, St, functional parameters) and one including Ssk that has shown no dependence on load and WSD. Also, the functional parameters Spk and Svk follow in a similar manner the wear parameter, WSD, but Sk is the least dependent on load. For the highest load, amplitude parameters such as Sa and St are following the tendency of WSD. Each lubricant has its particular correlation between wear parameters and texture quality, expressed by the help of a set of roughness parameters.

Research limitations/implications

Such studies help tribologists to rank lubricants based on a combined analysis with wear parameters and texture parameters.

Practical implications

The results allow for evaluating new formulated lubricants.

Originality/value

The study on the quality on worn surfaces introduces the original idea of analyzing the entire wear scar surface (approximated by an ellipse with the axes as those experimentally measured) by the help of a set of 3 D roughness parameters.

Details

Industrial Lubrication and Tribology, vol. 74 no. 3
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 10 August 2015

Lorena Deleanu, Constantin Georgescu, Sorin Ciortan and Liviu Catalin Solea

The purpose of this paper is to establish the influence of oil concentration in oil-in-water emulsions on their flammability on hot surfaces and on their viscosity. The interest…

96

Abstract

Purpose

The purpose of this paper is to establish the influence of oil concentration in oil-in-water emulsions on their flammability on hot surfaces and on their viscosity. The interest in fire test systematization is obviously developing due to many grades and applications of fluids and new design solutions asking for higher parameters in exploitation, including pressure and temperature. Higher temperature and pressure have a synergic effect on fire risk; thus, a special attention has to be given to selecting fluids based on fire tests.

Design/methodology/approach

This test simulates a hazardous event when a fluid drops on a hot surface: 10 ml of fluid is dropped during 40-60 seconds on a manifold kept at a constant temperature, from a distance of 300 ± 5 mm above the surface. Tests were done under the procedure of SR EN ISO 20823:2004, with an original equipment. The apparent viscosity of the tested fluids was determined using a rheometer Rheotest 2. The tests were done for the fully mineral oil (Prista MHE-40) and for emulsions with different oil volume in water: 5, 10, 20, 30, 40, 50, 60, 70, 80 and 90 per cent, respectively.

Findings

The mineral oil MHE 40 Prista does not burn repeatedly for manifold temperature lower than 440°C, but it burns at 450°C on the clean surface and at 425°C on dirty surface, as obtained after testing the same oil, but at a temperature for which the oil burns. The emulsions do not burn even at 90 per cent oil in water, but the apparent viscosity of the emulsion is too high and unstable, above 20-30 per cent (volume) oil in water. No evident relationship was found between the apparent viscosity of the emulsions and their behavior on hot surface.

Research limitations/implications

The hydraulic fluids were ranked, taking into account the flammability characteristics determined with the help of this test.

Practical implications

This paper aims to reduce the risk of fire in hazardous environments using fire-resistant fluids.

Social implications

Testing hydraulic fluids under the procedure of SR EN ISO 20823:2004 is required by European and national regulations to avoid large-scale accidents produced by the ignition of hydraulic fluids.

Originality/value

As far as the authors have known, the test procedure was only used for establishing whether a certain fluid passes or does not pass this test. The authors did not find any references for establishing the influence of oil concentration on the flammability characteristics. Also, the equipment has an original design, allowing for a good repeatability and a high protection of the operator.

Details

Industrial Lubrication and Tribology, vol. 67 no. 5
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 9 February 2015

Lorena Deleanu and Constantin Georgescu

The paper aims to present results on the friction and the wear of polytetrafluoroethylene (PTFE) and eight commercially available composites with PTFE matrix, for tests done on…

306

Abstract

Purpose

The paper aims to present results on the friction and the wear of polytetrafluoroethylene (PTFE) and eight commercially available composites with PTFE matrix, for tests done on shoe/roller tribotester with water lubrication in open circuit. There are pointed out particular tribological processes within the superficial layers of the composites with the help of optical microscopy.

Design/methodology/approach

Analysing the tribological behaviour of eight grades of PTFE composites sliding in water on shoe/roller tribotester.

Findings

Good results of wear behaviour under water lubrication for all the composites. PTFE exhibits severe wear under the tested regime.

Originality/value

The research could support PTFE composite application for water lubricated systems.

Details

Industrial Lubrication and Tribology, vol. 67 no. 1
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 8 April 2014

Constantin Georgescu, Lorena Deleanu and Mihail Botan

This research aims to characterize the tribological behavior of polybutylene terephthalate (PBT) and PBT composites with micro glass beads (MGB) on steel, in dry conditions and on…

153

Abstract

Purpose

This research aims to characterize the tribological behavior of polybutylene terephthalate (PBT) and PBT composites with micro glass beads (MGB) on steel, in dry conditions and on a block-on-ring tester, pointing out the influence of sliding distance and speed. The tribology of PBT and its composites is still in an early stage because this thermoplastic polyester requires accurate technological and thermal treatment.

Design/methodology/approach

The composites were produced by ICEFS Savinesti Romania and contain PBT grade Crastin6130NC010 (as supplied by Du Pont), 0.5 […] 1.0 per cent (weight) Relamyd B-2Nf (polyamide grade produced by ICEFS, for a better dispersion of MGB), 1 per cent (weight) black carbon for technological and tribological reasons and different micro glass beads (MGB) concentrations (10.0 and 20.0 per cent weight). Tests were done for different sliding distances (2,500, 5,000 and 7,500 m) and speeds (0.5, 1.0 and 1.5 m/s) and a normal load of 5 N.

Findings

The friction coefficient and the wear parameter (as mass loss of polymeric blocks) pointed out a good tribological behavior for these composites. Scanning electron microscope (SEM) images revealed particular aspects of PBT local transfer on steel. Also, 10 per cent MGB in PBT reduces wear, especially for longer distances (75,000 m) and higher speeds (0.5 and 0.75 m/s); the friction coefficient is only slightly increased up to 0.23, being less influenced by the speed and the sliding distance as compared to neat polymer.

Originality/value

PBT and PBT composites could become challengers for replacing materials in applications similar to tested ones. Even the neat polymer exhibits a good tribological behavior. The composites have a lower sensibility to higher speeds and sliding distances for the applied load.

Details

Industrial Lubrication and Tribology, vol. 66 no. 3
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 1 July 1999

Constantin Virgil Negoita

Provides a personal view of the development of the theories and applications of fuzzy systems which were first introduced in the 1960s. Details the interrelationships between the…

270

Abstract

Provides a personal view of the development of the theories and applications of fuzzy systems which were first introduced in the 1960s. Details the interrelationships between the pioneering proponents of fuzzy theory. Concentrates in part I on the historical beginnings of the field and in part II continues to provide personal insights into contemporary studies.

Details

Kybernetes, vol. 28 no. 5
Type: Research Article
ISSN: 0368-492X

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Article
Publication date: 13 August 2019

Constantin Bratianu and Ruxandra Bejinaru

The purpose of this paper is to examine the knowledge dynamics process based on the energy metaphor and the thermodynamics framework. Knowledge dynamics is analyzed as a…

537

Abstract

Purpose

The purpose of this paper is to examine the knowledge dynamics process based on the energy metaphor and the thermodynamics framework. Knowledge dynamics is analyzed as a transformational process that goes beyond the Newtonian logic used to date.

Design/methodology/approach

The research design is based on metaphorical thinking, critical analysis of the mostly used knowledge metaphors to date, and the logic of thermodynamics, which is the science of energy transformation.

Findings

Knowledge is conceived as a field, composed of three fundamental forms: rational knowledge, emotional knowledge and spiritual knowledge. Each form of knowledge can be transformed into another form, thus generating an iterative and interactive dynamics. The unity of knowledge is supported by the brain’s organic structure.

Practical implications

Understanding knowledge dynamics as a transformational process helps managers in their problem-solving and implementation of strategies in their organizations. Knowledge dynamics is fundamental to the learning and unlearning processes, and for stimulating innovation. Knowledge dynamics, as a transformational process, is influencing both organizational behavior as well as consumers’ behavior.

Originality/value

The present research uses for the first time a thermodynamics approach in understanding and explaining the knowledge dynamics, which is a transformational process of three fundamental forms of knowledge: rational, emotional and spiritual.

Details

Kybernetes, vol. 49 no. 1
Type: Research Article
ISSN: 0368-492X

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Abstract

Details

Knowledge Translation
Type: Book
ISBN: 978-1-80382-889-3

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Article
Publication date: 16 March 2020

Constantin Bratianu, Elena-Mădălina Vătămănescu, Sorin Anagnoste and Gandolfo Dominici

The purpose of this paper is to analyse the influences of different types of knowledge and their inherent dynamics on the effectiveness of the decision-making (DM) process…

640

Abstract

Purpose

The purpose of this paper is to analyse the influences of different types of knowledge and their inherent dynamics on the effectiveness of the decision-making (DM) process. Knowledge dynamics (KD) is envisioned through the lens of the knowledge fields theory while effective DM process is objectivised via organisational appreciation and reward, higher business performance, sustainable partnerships and managerial satisfaction with previous achievements.

Design/methodology/approach

A questionnaire-based survey was conducted with 275 middle managers from companies operating in the business consulting field. The conceptual and structural model was tested using the partial least squares structural equation modelling technique.

Findings

The study advances novel insights into the significant positive influences of various knowledge fields on KD on the DM process within real-life business environments. Even though rational knowledge exerts a noteworthy effect on DM, its influence is exceeded by the KD, which proves that integrating emotional and spiritual knowledge in the decisional equation may become a pivotal input to making good managerial decisions regardless of the level of regulation and standardisation in the field.

Research limitations/implications

The research relied on threefold knowledge fields as predictors for the DM process, thus providing a starting point for the development of more complex models.

Originality/value

The study emerges as a groundbreaking approach via the integration and application of the knowledge fields theory within a more comprehensive and empirical outlook on the DM process. Simultaneously, it places DM beyond the unidimensional outcomes of rationality and intuition by urging its intricate and interactional nature.

Details

Management Decision, vol. 59 no. 2
Type: Research Article
ISSN: 0025-1747

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Article
Publication date: 1 November 1999

Constantin Virgil Negoita

Provides a personal view of the development of the theories and applications of fuzzy systems which were first introduced in the 1960s. Details the interrelationships between the…

207

Abstract

Provides a personal view of the development of the theories and applications of fuzzy systems which were first introduced in the 1960s. Details the interrelationships between the pioneering proponents of fuzzy theory. Concentrates in part I on the historical beginnings of the field and in part II continues to provide personal insights into contemporary studies.

Details

Kybernetes, vol. 28 no. 8
Type: Research Article
ISSN: 0368-492X

Keywords

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