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Article
Publication date: 8 February 2008

M.A. Delgado, J.M. Franco and E. Kuhn

The aim of this work is to investigate the relationship among rheology, tribology and traditional standardized technological parameters of lithium lubricating greases.

Abstract

Purpose

The aim of this work is to investigate the relationship among rheology, tribology and traditional standardized technological parameters of lithium lubricating greases.

Design/methodology/approach

Lubricating greases having the same composition but differing in processing protocols have been manufactured and characterized in order to isolate the rheological behaviour from the formulation.

Findings

Some successful empirical correlations between rheological (viscous and viscoelastic) and technological standardized parameters, with the friction factor obtained from a ball‐disc tribometer, have been established in order to elucidate the role of the rheological behaviour of lubricating greases on the friction process. In addition to this, an energetic evaluation of the structural degradation of greases during the friction process has been carried out by performing stress‐growth experiments. Thus, the storage energy density, which is related to the grease capacity to accumulate energy in the elastic deformation, and the limiting energy density, which represents the dissipation of energy in the flow process, have been satisfactorily correlated with the friction factor.

Research limitations/implications

The complex rheological behaviour of lubricating greases, the extreme deformations and the high‐shear stresses resulting in a tribological contact imply that it is difficult to develop a model to describe their behaviour in an elastohydrodynamic lubricating contact.

Originality/value

This paper provides a resource of practical data to be applied in tribological systems.

Details

Industrial Lubrication and Tribology, vol. 60 no. 1
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 1 December 2000

Walter Holweger

Lubricants are very complex mixtures of components. To predict their behaviour over a long time it is necessary to make a lot of machinery element tests. This paper tries…

Abstract

Lubricants are very complex mixtures of components. To predict their behaviour over a long time it is necessary to make a lot of machinery element tests. This paper tries to give an insight into how lubricants can be estimated in their structure by IR‐microscopy and how this procedure could lead to a short prediction of their long‐time behaviour in time‐ and cost‐expansive machinery element testing.

Details

Industrial Lubrication and Tribology, vol. 52 no. 6
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 1 February 2004

E. Kuhn and W. Holweger

Greases are non‐Newtonian fluids with a special rheological and tribological behaviour. They have a wide range of applications, for example, ball bearings and gears. This…

Abstract

Greases are non‐Newtonian fluids with a special rheological and tribological behaviour. They have a wide range of applications, for example, ball bearings and gears. This paper reports a study of the reaction of model greases in a tribological contact. The influence of the grease topography has been measured in several tests and the tribological process is modelled. All investigations were done from an energy point of view.

Details

Industrial Lubrication and Tribology, vol. 56 no. 1
Type: Research Article
ISSN: 0036-8792

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Book part
Publication date: 7 January 2019

Stacey Jones Bock, Christy M. Borders, Kristi Probst and Shaqwana Freeman-Green

In 2018, the Centers for Disease Control and Prevention (CDC) released the statistic that 1 out of every 59 children had a diagnosis of autism spectrum disorder (ASD)…

Abstract

In 2018, the Centers for Disease Control and Prevention (CDC) released the statistic that 1 out of every 59 children had a diagnosis of autism spectrum disorder (ASD). Young children with ASD have unique needs specifically related to the characteristics that impact their communication and social emotional and behavioral development. These unique needs require early and intensive intervention to minimize their lifelong impact. It is important to identify and use evidence-based interventions to help parents support their children at home, and as a continuation of the skills they are being taught in other settings. This chapter will address the prevalence of young children with ASD, the impact and need for family involvement in intervention, and service provision and potential interventions.

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Article
Publication date: 27 September 2011

R. Sánchez, M. Fiedler, E. Kuhn and J.M. Franco

The aim of this paper is to characterize some selected formulations based on castor oil and a variety of biogenic thickeners from a tribological point of view and compare…

Abstract

Purpose

The aim of this paper is to characterize some selected formulations based on castor oil and a variety of biogenic thickeners from a tribological point of view and compare them with some traditional lithium greases.

Design/methodology/approach

The evolution of the friction coefficient in several tribological tests performed using several ball‐on‐disc configurations and coupling materials was monitored for the different oleogels proposed as biodegradable lubricating greases. Both a rotational ball‐on‐disc classical tribometer designed at MuT laboratory and a nanotribometer were used in rotational and oscillatory modes.

Findings

Generally, the use of castor oil‐based formulations potentially applicable as biodegradable lubricating greases provides similar or lower values of the friction coefficient than traditional lithium greases, depending on the nature of thickener agent employed and tribological contact. In all cases, biodegradable formulations provide significantly lower values of the friction coefficient in tribological tests performed in the oscillatory mode. Weak oleogels like those thickened with glyceryl and sorbitan monostearates or acylated chitosan, provide the lowest values of the friction coefficient in every type of configuration or frictional test analysed. Biogrease formulations containing cellulose or chitin derivatives as thickener agents generally yield higher values of the friction coefficient, which may be comparable to those obtained with the reference lithium greases depending on the thickener and tribological configuration. In frictional tests performed in the rotational mode, the inclusion of ethyl cellulose in the formulation yields high values of the friction coefficient, which was attributed to the castor oil viscosity modification exerted by this additive. Wear results depend on the balance between the frictional behaviour, especially in the initial transient regime, and oleogel mechanical stability.

Practical implications

This investigation proposes different new alternatives to replace the traditional thickener agent in lubricating greases with others based on renewable resources in order to obtain a completely biodegradable formulation for different industrial applications.

Originality/value

This paper provides a resource of new practical friction coefficient data as well as a comparative analysis of the tribological response of these new formulations based on biogenic thickeners and other traditional lithium greases.

Details

Industrial Lubrication and Tribology, vol. 63 no. 6
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 4 March 2014

Maciej Paszkowski and Sylwia Olsztyńska-Janus

The thixotropy of lubricating grease thickened with lithium 12-hydroxystearate with mineral base oil was investigated. The thixotropy has a significant influence on the…

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Abstract

Purpose

The thixotropy of lubricating grease thickened with lithium 12-hydroxystearate with mineral base oil was investigated. The thixotropy has a significant influence on the flow resistance and pressure drop in the structural components of lubrication systems, which is of major importance as today the latter are being centralized and automated. The paper aims to discuss these issues.

Design/methodology/approach

Rheometer studies on thixotropy were carried out and the grease microstructure was visualized using atomic force microscopy (AFM). Total reflection Fourier transform infrared spectroscopy (ATR-FTIR) was used to study the physicochemical interactions which indicate the disintegration and recovery of the grease microstructure.

Findings

A qualitative assessment of the physicochemical interactions between lithium soap floccules was made and a theory of the self-ordering effect of lithium 12-hydroxystearate associated molecules during shearing and their aggregation and flocculation during relaxation has been proposed.

Originality/value

Because of the complexity of the disintegration and recovery of the lubricating grease thickener microstructure, there is still limited physical understanding of the mechanism of this process. Therefore, the present research was undertaken to identify the phenomena involved.

Details

Industrial Lubrication and Tribology, vol. 66 no. 2
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 27 February 2009

Carroll Estes and Elena Portacolone

The purpose of this article is to explore Maggie Kuhn's theoretical and analytical contributions to social gerontology and more broadly to the advancement of critical and…

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892

Abstract

Purpose

The purpose of this article is to explore Maggie Kuhn's theoretical and analytical contributions to social gerontology and more broadly to the advancement of critical and public sociology.

Design/methodology/approach

This paper is an theoretical exploration of ageing. Maggie Kuhn's and the Gray Panthers theoretical contributions include analyses of, and related to: identity politics, intersectionality, cultural and media studies and the cognitive sciences, the forces and factors in the developing political economy of ageing including critiques of the ageing enterprise and the medical industrial complex, the sociology of knowledge of gerontology and globalization and world imperialism. The concluding section argues that the post‐retirement career of Maggie Kuhn was one of a Public Sociologist.

Findings

Maggie Kuhn fulfils the promise of the Project of Public Sociology, which “is to make visible the invisible, to make the private public, to validate these organic connections as part of our sociological life”. Maggie Kuhn's example moved forward the work of multiple generations of scholars. She lived and produced critical social analyses in pursuit of emancipatory knowledges. Her work is one of the earliest forms, if not the first, of critical pedagogy in gerontology; she promoted and advanced discourses of resistance. Maggie Kuhn was an engaged and outraged, practicing organic intellectual – the epitome of what bell hooks means by “teaching to transgress” and “education as the practice of freedom”. In the 24 years after her involuntary retirement, this was Maggie Kuhn's full‐time transformational agenda.

Originality/value

The paper looks at how the biography of Maggie Kuhn helped to engender the rise of radical social gerontology.

Details

International Journal of Sociology and Social Policy, vol. 29 no. 1/2
Type: Research Article
ISSN: 0144-333X

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Article
Publication date: 1 March 1987

Elias Khalil

This article attempts to tackle a fundamental methodological question in economics. The task is to investigate whether competing traditions in the history of economics are…

Abstract

This article attempts to tackle a fundamental methodological question in economics. The task is to investigate whether competing traditions in the history of economics are commensurable or not, that is, whether there is a firm ground on which a researcher could adjudicate the truth content of a theory. Thomas Kuhn in philosophy and Donald McClosky in economics among others are understood to advance the thesis that theories are incommensurable since there is no empirical ground to resort to in order to resolve disputes among traditions in economics. Karl Popper in philosophy and Mark Blaug in economics among others argue that theories are commensurable since there is a sharp and distinct criterion which could determine the scientific content of a theory. A more sophisticated version of Popper's falsificationism has been advanced in philosophy by Imre Lakatos and has been correspondingly followed in economics by Spiro Latsis, E. Roy Weintraub and others.

Details

International Journal of Social Economics, vol. 14 no. 3/4/5
Type: Research Article
ISSN: 0306-8293

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Article
Publication date: 22 January 2018

Johannes Wollenburg, Alexander Hübner, Heinrich Kuhn and Alexander Trautrims

The advent of grocery sales through online channels necessitates that bricks-and-mortar retailers redefine their logistics networks if they want to compete online. Because…

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7437

Abstract

Purpose

The advent of grocery sales through online channels necessitates that bricks-and-mortar retailers redefine their logistics networks if they want to compete online. Because the general understanding of such bricks-and-clicks logistics systems for grocery is still limited, the purpose of this paper is to analyze the internal logistics networks used to serve customers across channels by means of an exploratory study with retailers from different contexts.

Design/methodology/approach

A total of 12 case companies from six European countries participated in this exploratory study. Face-to-face interviews with managers were the primary source for data collection. The heterogeneity of the sample enabled the authors to build a typology of logistics networks in grocery retailing on multiple channels and to understand the advantages of different warehousing, picking, internal transportation and last-mile delivery systems.

Findings

Bricks-and-mortar grocery retailers are leveraging their existing logistics structures to fulfill online orders. Logistics networks are mostly determined by the question of where to split case packs into customer units. In non-food logistics, channel integration is mostly seen as beneficial, but in grocery retailing, this depends heavily on product, market and retailer specifics. The data from the heterogeneous sample reveal six distinct types for cross-channel order fulfillment.

Practical implications

The qualitative analysis of different design options can serve as a decision support for retailers developing logistics networks to serve customers across channels.

Originality/value

The paper shows the internal and external factors that drive the decision-making for omni-channel (OC) logistics networks for previously store-based grocery retailers. Thereby, it makes a step toward building a contingency and configuration theory of retail networks design. It discusses in particular the differences between grocery and non-food OC retailing, last-mile delivery systems and market characteristics in the decision-making of retail networks design.

Details

International Journal of Physical Distribution & Logistics Management, vol. 48 no. 4
Type: Research Article
ISSN: 0960-0035

Keywords

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Article
Publication date: 1 April 2003

Andrea Wohlfeld Kuhn

The US General Services Administration (GSA) sought to identify innovative and best practices in real property management at the state level, with the intent that sharing…

Abstract

The US General Services Administration (GSA) sought to identify innovative and best practices in real property management at the state level, with the intent that sharing these practices may lead to creative new approaches throughout all levels of government. The resulting study focused on four aspects of real property management and identified the following states as exemplars: (1) Acquisition and construction (Maryland, Minnesota, Utah) (2) Operations and maintenance (Michigan, Missouri, Utah) (3) Web‐enabled software (Texas, Washington) (4) Public‐private partnerships (Arizona, Washington) Many of these best practices have resulted in streamlined operations, cost savings, and innovative solutions to complex problems. They offer new ideas for real property management. In order to perform the study, GSA contracted with George Washington (GW) University. The GSA study team included the following members: Marjorie Lomax, Director of the Evaluation and Outreach Division, Andrea Wohlfeld Kuhn, Project Team Leader, and team members Dennis Goldstein, Sheldon Greenberg,Robert Harding, Jonathan Herz and Rebekah Pearson. The GW team was under the direction of Dr Kathryn Newcomer, PhD, Principal Investigator, with Robin Kane and Howard Smith as Research Associates. The following paper is an excerpt of the study. The entire document can be downloaded at http://www.gsa.gov/statesrpbp

Details

Journal of Facilities Management, vol. 2 no. 2
Type: Research Article
ISSN: 1472-5967

Keywords

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