M.M. Maru, R. Serrato‐Castillo and L.R. Padovese
This work aims to compare the vibration behavior of roller and ball bearings operating with clean and quartz‐contaminated lubricants. Wear influence on vibration of both bearing…
Abstract
Purpose
This work aims to compare the vibration behavior of roller and ball bearings operating with clean and quartz‐contaminated lubricants. Wear influence on vibration of both bearing types was also compared.
Design/methodology/approach
Experimental tests were run in clean and contaminated mineral oil. Contaminant quartz particles of 59 μm average size were tested in three concentration levels: 0.05, 0.25 and 0.5 g/l. Radial vibration of the roller bearing was measured by accelerometer and wear was analyzed through microscopy of the surfaces and optical spectrometry of oils.
Findings
Differences in vibration response among both bearing types were observed regarding the root mean square value of vibration data in the high frequency band (600‐10,000 Hz); differences in wear influence on vibration were also identified and correlated to the differences in the tribological features.
Originality/value
This paper presents a methodology for detecting contamination and wear of roller bearings by applying a simple procedure of vibration monitoring and analysis.
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Abstract
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Fernando R. Jiménez, Edward Ramirez and Art Diaz
The purpose of this study is to draw on terror management theory (TMT) to explore the impact of pervasive mortality cues on consumer behaviour as a result of residing in a…
Abstract
Purpose
The purpose of this study is to draw on terror management theory (TMT) to explore the impact of pervasive mortality cues on consumer behaviour as a result of residing in a community ravaged by escalating violence.
Design/methodology/approach
A qualitative analysis of 27 in-depth interviews of consumers living in Ciudad Juárez, Mexico during the height of the Mexican drug war provides insight into their coping strategies and consumption.
Findings
Living under such conditions results in unrelenting mortality salience (MS), as well as the adoption of consumption-related coping strategies that can conflict with cultural worldviews and threaten self-esteem. The normalization of coping strategies severely strains worldviews. Consumers manage their ensuing intrapersonal evaluative tension by developing consumption safe havens and through identity fragmentation. Moreover, permanent proximal defences result from persistent MS.
Research limitations/implications
Although cross-sectional and idiosyncratic to the Mexican culture, the findings broaden TMT by suggesting that consumers facing relentless MS experience altered brand meanings and social interactions, as they were reluctant to acquire prestige brands, while indicating an increase in the value placed on relationships over possessions.
Practical implications
Marketers can help consumers alleviate their death-related anxiety by eliminating telemarketing campaigns, promoting online shopping, using unique customer identification numbers and investing in visible security measures such as gates, security cameras, and guards.
Originality/value
This exploratory study provides a preliminary theoretical framework for consumers’ reactions to persistent MS.
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Daryl Mahon and Martha Griffin
In the previous chapters, I set out a conceptual model of trauma-informed servant leadership and discussed servant leadership supervision for working with burnout, compassion…
Abstract
In the previous chapters, I set out a conceptual model of trauma-informed servant leadership and discussed servant leadership supervision for working with burnout, compassion fatigue and secondary trauma in employees within trauma related health and social care settings. In this chapter, I further extend servant leadership to the peer support principle in trauma-informed approaches (Substance Abuse and Mental Health Services Administration, 2014). The first part of this chapter will examine peer support work (PSW) and report on the outcomes associated with it. Then, servant leadership will be discussed and used to operationalise the principle of peer support as set out in trauma-informed approaches. A servant leadership peer support approach is put forward with a theoretical basis. This theoretical model has been slightly changed from the previous servant leadership approaches discussed, in order to represent the PSW role more accurately. However, as discussed previously, it is not the characteristics of the Servant leadership (SL) model that define the approach, rather the philosophy and desire to serve first. In the last section of this chapter, Martha Griffin brings the characteristics of this model to life using her vast experience and discusses some of the potential challenges faced by peers in training and practice.
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Yewande Adewunmi, Prisca Simbanegavi and Malcolm Weaich
Informal settlements are frequently located in hazardous areas with a high risk of natural disasters. Upgrading informal settlements can be difficult due to the time and expense…
Abstract
Informal settlements are frequently located in hazardous areas with a high risk of natural disasters. Upgrading informal settlements can be difficult due to the time and expense needed to complete the process. This chapter advocates using a management framework of public services in informal settlements. In doing so, it addresses 17 of the 17 UN sustainable development goals (SDGs). The study reviewed the literature to investigate current ways of managing environmental enterprises in informal settlements in South Africa. Thereafter, the challenges of managing public services were explored, and a conceptual framework for managing public services by social enterprises in such communities was developed. The chapter found that environmental enterprises are classified as ‘green spaces’ and infrastructure, water and sanitation services, energy systems, and recycling initiatives. Essential aspects of sustainable community-based facilities management (SCbFM) for managing public services are maintenance, governance, community project management, environment service delivery, service performance, governance, community project management, environment service delivery, service performance, well-being and health and safety, disaster management, and finance. Some of the problems of managing public services in informal settlements include the limited skills of managers, the focus of government on new projects rather than managing existing projects, not choosing the right indicators to measure service performance, and limited guidelines for the health and safety of managers and disaster management. Thus, a new conceptual framework was needed and developed based on the principles of social capital and capability for managing services in informal settlements in South Africa.
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Aparecido Carlos Gonçalves and Linilson Rodrigues Padovese
The purpose of this paper is to provide information on lubricant contamination by biodiesel using vibration and neural network.
Abstract
Purpose
The purpose of this paper is to provide information on lubricant contamination by biodiesel using vibration and neural network.
Design/methodology/approach
The possible contamination of lubricants is verified by analyzing the vibration and neural network of a bench test under determinated conditions.
Findings
Results have shown that classical signal analysis methods could not reveal any correlation between the signal and the presence of contamination, or contamination grade. On other hand, the use of probabilistic neural network (PNN) was very successful in the identification and classification of contamination and its grade.
Research limitations/implications
This study was done for some specific kinds of biodiesel. Other types of biodiesel could be analyzed.
Practical implications
Contamination information is presented in the vibration signal, even if it is not evident by classical vibration analysis. In addition, the use of PNN gives a relatively simple and easy‐to‐use detection tool with good confidence. The training process is fast, and allows implementation of an adaptive training algorithm.
Originality/value
This research could be extended to an internal combustion engine in order to verify a possible contamination by biodiesel.
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Joao Luiz do Vale, Carlos Henrique da Silva and Giuseppe Pintaude
This paper aims to present a proposal for evaluating the coefficient of friction (COF), under a reciprocating test that considers the energy dissipated by the friction force. In…
Abstract
Purpose
This paper aims to present a proposal for evaluating the coefficient of friction (COF), under a reciprocating test that considers the energy dissipated by the friction force. In addition, this new parameter is compared to average COF, which is often used to evaluate COF in reciprocating tests.
Design/methodology/approach
Samples of compacted graphite iron were extracted directly from an internal combustion engine block. The piston ring used was a nitrided martensitic stainless steel with an asymmetrical profile, and the lubricant oil was the SAE 30 CF, controlled at 40°C. Different testing conditions were carried out in a CETR-UMT-Bruker tribometer, varying loads between 25-125 N, frequencies between 1-12.5 Hz and track length between 3-10 mm. Three maps comparing the average COF and the energetic definition were built, allowing to discuss their similarities.
Findings
In general, both parameters had similarities especially for low frequencies and small tracks. However, for test conditions that imposed higher accelerations (i.e. longer track lengths and higher frequencies), the energetic COF (COFe) was lower than the average COF (COFa) and presented better agreement in Stribeck-like curves – independent on the experienced lubrication regime along the stroke. As the COFe can be interpreted as a weighted average of instantaneous COF in relation to in-track displacements, an immediate consequence is that instantaneous COF closest to mid-stroke is considered more significant. Furthermore, perturbations associated with the intrinsic accelerations of the movement test are minimized in the COFe formulation.
Originality/value
The energetic COF parameter (COFe) is presented and compared to the average COF. The new parameter presented less data dispersion and is attractive to evaluate the COF behavior in reciprocating tests, as its formulation minimizes perturbations associated with the intrinsic accelerations of the movement (mainly in the initial and final part of the track where the acceleration has its greatest magnitude).
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2019-0324
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Okka Adiyanto, Pandu Sandi Pratama and Wonsik Choi
This paper aims to examine the friction coefficient and wear rate characteristics of SCM 440 bearing steel used in the cylinder block of a tractor engine with gas lubrication and…
Abstract
Purpose
This paper aims to examine the friction coefficient and wear rate characteristics of SCM 440 bearing steel used in the cylinder block of a tractor engine with gas lubrication and oil lubrication.
Design/methodology/approach
Friction tests were performed using a pin-on-disc tester with loads of 2 to 10 N and sliding velocities of 0.06 to 0.34 m/s. The experiment was done with and without nitrogen, and paraffin oil lubricant was used to prevent wear during process.
Findings
The nondimensional characteristic number from the Stribeck curves indicated that the lubrication regime is hydrodynamic. As the velocity and load increased, the friction coefficient of the SCM 440 increased and greater applied load resulted in a smaller friction coefficient. The range of the friction coefficient was 0.017001 to 0.092904 with paraffin oil lubrication and 0.01614 to 0.4555 with nitrogen lubrication. Nitrogen is effective in reducing the friction coefficient of materials that are in contact and subjected to a load and velocity.
Originality/value
The experiments confirm that nitrogen is effective for reducing the friction coefficient of SCM 440 materials that are in contact with each other and subjected to a load and velocity.
Xiaoyu Yan, Wei Wang, Xiaojun Liu, Jimin Xu, Lihong Zhu and Bingxun Yang
A finite element method (FEM) model of the frictional behavior of two rough surfaces with a group of third-body particles confined by the surface asperities is established. By…
Abstract
Purpose
A finite element method (FEM) model of the frictional behavior of two rough surfaces with a group of third-body particles confined by the surface asperities is established. By monitoring the stress distribution, friction force and the displacement of the surfaces, how the frictional instability is induced by these particles is studied. This modeling job aims to explore the relation between the meso-scale behavior and the macro-scale frictional behavior of these particles.
Design/methodology/approach
By using FEM, a 2D model of two frictional rough surfaces with a group of elastic or elasto-plastic particles confined by surface asperities is established. The Mises stress, macro friction force and displacements of elements are monitored during compressing and shearing steps.
Findings
The macro friction coefficient is more stable under higher pressure and smaller under higher shearing speed. The dilatancy of the interface is caused by the elevation effect of the particles sheared on the peak of the lower surface, particles collision and third body supporting. The combined effect of particles motion and surface–surface contact will induce high-frequency displacements of surface units in restricted direction.
Originality/value
Previous studies about third-body tribology are mainly concentrated on the frictional behavior with large number of particles distributed homogeneously across the interface, but this paper focuses on the behavior of third-body particles confined by surface asperities.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-12-2019-0544/
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The present quantitative-descriptive study aims to measure the level of English language learning autonomy of the pre-service teachers.
Abstract
Purpose
The present quantitative-descriptive study aims to measure the level of English language learning autonomy of the pre-service teachers.
Design/methodology/approach
A short list questionnaire developed by Dixon (2011) was administered to 61 pre-service English teachers enrolled in Western Mindanao State University in order to measure their English language learning autonomy. Differences on the levels of English language learning autonomy across participants’ gender, number of languages spoken and first language were also explored.
Findings
Results revealed that participants are highly autonomous in English language learning. Gender, number of languages spoken and first language were found to have no significant influence on English language learning autonomy.
Research limitations/implications
Results on the level of English language learning autonomy indicate that pre-service teachers are highly autonomous and, therefore, ready for lifelong learning. This implies pedagogical and instructional advantages, as they can learn and explore the language independently.
Practical implications
Since gender, number of languages spoken and first language do not significantly influence the level of English language learning autonomy, it is suggested that English teachers do not need to develop differentiated instructions and activities anymore, which will cater the three profile variables in fostering autonomous learning, as participants already exhibit a level of autonomy in English language learning.
Social implications
This would allow teachers and students to be aware of the importance of autonomy in language learning. Thus, it will prepare them to be independent and lifelong learners, as they engage themselves in the professional world.
Originality/value
As one of the Asia’s developing countries, the Philippines have captured a small number of studies and contributions to autonomous learning in the field of research (Madrunio, Tarrayo, Tupas and Valdez, 2016 as cited in Iñigo, 2018). Specifically, there is no research study conducted that measures “language learning autonomy” in the Philippine’s higher education much to the knowledge of the researcher. Thus, this study will be the first one to determine the level of autonomy of pre-service teachers in English language learning in the Philippine context. Furthermore, the present study also intended to determine significant differences on the level of language learning autonomy of pre-service teachers across genders, number of languages spoken and their first language.