Walter Holweger, Frank Walther, Jörg Loos, Marcus Wolf, Jürgen Schreiber, Werner Dreher, Norbert Kern and Steffen Lutz
Bearings in field applications with high dynamic loading, e.g. wind energy plants, suffer from sudden failure initiated by subsurface material transformation, known as white…
Abstract
Purpose
Bearings in field applications with high dynamic loading, e.g. wind energy plants, suffer from sudden failure initiated by subsurface material transformation, known as white etching cracks in a typical scale of μm, preferably around the maximum Hertzian stress zone. Despite many investigations in this field no precise knowledge about the root cause of those failures is available, due to the fact that failure under real service conditions of wind energy plants differs from what is known from test rig results in terms of contact loading, lubrication or dynamics. The purpose of this paper is to apply Barkhausen noise measurement to a full bearing test ring running under conditions of elastohydrodynamic lubrication (EHL) with high radial preload.
Design/methodology/approach
Full bearing tests are carried out by use of DGBB (Deep Grove Ball Bearings) with 6206 specification, material set constant as 100Cr6, martensitic hardening, 10‐12 percent maximum retained austenite and radial preload of 3500 MPa. Speed is set 9000 rpm, temperature is self setting at 80°C by test conditions. For tests, synthetic hydrocarbon base oil (Poly‐α‐Olefine) with a 1 percent amount of molydenum‐dithiophosphate (organic chain given as 2‐ethylhexyl) was used.
Findings
Non‐destructive fractal dimension analyses by use of Barkhausen noise measurements is of versatile value in terms of recording bearing manufacturing processes, but can also be part of non‐destructive condition monitoring of bearings in field applications, where predictive reactive maintenance is crucial for availability of the plant.
Research limitations/implications
Barkhausen noise signal recording may also be valuable for case studies related to microstructure changes of steel under operation conditions. Bearings are exposed in plenty of conditions to phenomena such as straying currents, subsequently straying magnetic fields. Hardly anything is known about how microstructure of bearing steel is susceptible to such conditions. This will be part of further studies.
Originality/value
Results given in the paper show that sudden bearing failure, according to formation of subsurface material property changes might be driven by activities of dislocations. Since those activities start with sequences of stress field‐induced formation of domains, later by formation of low‐angle subgrains, and at least phase transformation, recording of the Barkhausen signal would lead to real predictive condition monitoring in applications where a highly dynamic loading of the contact, even with low nominal contact pressure leads to sudden failure induced by white etching.
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Walter Holweger, Marcus Wolf, Frank Walther, Werner Trojahn, Annette Mütze, Jan Kunzmann, Jürgen Schreiber, Joachim Mayer and Manuela Reichelt
The purpose of this paper is to show how controlled exposure of electromagnetic fields toward bearing steel vulnerates the microstructure. The ability of Barkhausen Noise signal…
Abstract
Purpose
The purpose of this paper is to show how controlled exposure of electromagnetic fields toward bearing steel vulnerates the microstructure. The ability of Barkhausen Noise signal processing is used for detecting phenomena such as dislocation and subgrain formation processes as the beginning of later failures.
Design/methodology/approach
A Barkhausen noise signal measurement equipment is used for detecting subsurface distress of 100Cr6 as a function of the applied electromagnetic and mechanical stress. Barkhausen noise signal is mathematically processed by use of fractal dimension analysis.
Findings
The paper cleary reveals significant impact of electromagnetic field in junction with mechanical loading. Electromagnetic impact depends on the magnitude of the field.
Research limitations/implications
Research limitations are given by the fact that in real field applications, e.g. wind power plants, bearings are exposed by multiple influences and the methodology is not applicable to those conditions.
Practical implications
The methodology can be applied to real field applications in condition monitoring systems. Up to now, no reasonable on‐line measurement is in use determining sub surface fatigue phenomena. The paper hence, reveals the possibility to raise condition monitoring into a new perspective.
Originality/value
The use of Barkhausen noise signal processing, as presented here, is original with respect to real field applications, such as wind power plants with a high demand in condition monitoring, especially off‐shore plants.
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In previous years, there has been a peak in deliveries from all sectors. Consequently, the number of transport vehicles on urban roads has also increased. Unsurprisingly, this…
Abstract
Purpose
In previous years, there has been a peak in deliveries from all sectors. Consequently, the number of transport vehicles on urban roads has also increased. Unsurprisingly, this increase leads to many environmental problems, including increased carbon emissions. This paper attempts to examine this issue by addressing the impact of logistics pooling on the reduction of CO2 emissions in last-mile logistics. The aim is to see which of the logistics pooling options can minimize more CO2 emissions and in particular reach the threshold fixed by the Moroccan Agency of Logistics Development which is 30% until 2030.
Design/methodology/approach
The author conducted a simulation study. The sample was chosen from the economic pillar of the Moroccan Kingdom, namely Casablanca.
Findings
The results indicate that two pooling strategies lead to a higher level of environmental performance compared to the objective set up by the Moroccan Agency of Logistics Development (Direct Upstream and Downstream Transport: 44.39%/Multi-pick Upstream Transport and Multi-drop Downstream Transport: 30.93%). However, the first strategy remains the best one, as it not only minimizes emissions but also reflects the practices already implemented by several carriers and logistics service providers.
Practical implications
Successfully implementing these strategies in Casablanca could serve as a model for other cities facing similar challenges, demonstrating the viability and benefits of logistics pooling. Ultimately, the reduction in CO2 emissions aligns with global environmental goals, contributing to the fight against climate change and promoting a healthier urban environment for residents. By leveraging simulation technology, Casablanca can make significant strides toward more sustainable and efficient last-mile logistics, setting a precedent for green urban logistics practices.
Originality/value
Given Morocco’s significant geostrategic position, the urban logistics sector plays a crucial role in the development of Arab countries. The findings of this study can offer valuable insights for policymakers aiming to achieve sustainable economic growth. Additionally, to the author’s knowledge, this is the first study to focus on logistics pooling and carbon emissions in Arab nations. The paper further contributes by highlighting important directions for future research.
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– The purpose of this paper is to posit a methodology for exploring promotional trailers in the public domain and a critical discussion of the findings therein.
Abstract
Purpose
The purpose of this paper is to posit a methodology for exploring promotional trailers in the public domain and a critical discussion of the findings therein.
Design/methodology/approach
The approach utilises third part press as a mechanism to limit videosharing website results and allows for a varied corpus of data.
Findings
The paper posits that the term “trailer” has shifted significantly since its original use in the film industry and now applies to a certain type of experiential promotion.
Originality/value
This is the first time a methodology has been discussed that considers trailers as a shared vernacular term, rather than subject of historical archive.
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Gráinne McMahon, Harriet Rowley, Janet Batsleer and Elaine Morrison
In this chapter, the authors aim to recontextualise the local picture of youth participation in Manchester in a wider European perspective. First, because the research framework…
Abstract
In this chapter, the authors aim to recontextualise the local picture of youth participation in Manchester in a wider European perspective. First, because the research framework was a comparative European research project and, second, because the relevance also of local research depends on the degree to which it provides general insight into a phenomenon. The authors share with the editors and the other authors of this book the aim of questioning dominant understandings that limit youth participation to institutionalised forms and to young people’s involvement in existing practices and processes predefined by others, in most cases adult professionals like educators, youth workers and policy-makers. Based on the identification and discussion of three aspects related to the recognition of young people’s practice as participation in formal, non-formal and informal settings, the current authors want to use their views from the outside to shed light on the tensions and ambivalences of youth participation that do not become obsolete by applying a wider notion of participation.
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Steve McDonald, Amanda K. Damarin, Jenelle Lawhorne and Annika Wilcox
The Internet and social media have fundamentally transformed the ways in which individuals find jobs. Relatively little is known about how demand-side market actors use online…
Abstract
The Internet and social media have fundamentally transformed the ways in which individuals find jobs. Relatively little is known about how demand-side market actors use online information and the implications for social stratification and mobility. This study provides an in-depth exploration of the online recruitment strategies pursued by human resource (HR) professionals. Qualitative interviews with 61 HR recruiters in two southern US metro areas reveal two distinct patterns in how they use Internet resources to fill jobs. For low and general skill work, they post advertisements to online job boards (e.g., Monster and CareerBuilder) with massive audiences of job seekers. By contrast, for high-skill or supervisory positions, they use LinkedIn to target passive candidates – employed individuals who are not looking for work but might be willing to change jobs. Although there are some intermediate practices, the overall picture is one of an increasingly bifurcated “winner-take-all” labor market in which recruiters focus their efforts on poaching specialized superstar talent (“purple squirrels”) from the ranks of the currently employed, while active job seekers are relegated to the hyper-competitive and impersonal “black hole” of the online job boards.
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Hermann Frank, Alexander Kessler, Christine Bachner, Elena Fuetsch and Julia Suess-Reyes
Family firms (FF) reveal a considerable heterogeneity in their innovation behavior. Due to the successful long-term preservation of their innovation capacity via special resources…
Abstract
Purpose
Family firms (FF) reveal a considerable heterogeneity in their innovation behavior. Due to the successful long-term preservation of their innovation capacity via special resources and routines, multi-generational FF are of special interest in terms of learning from good practices. Against this background, the purpose of this paper is to ascertain principles for successful innovation behavior in long-term successful FF and to contribute to bridging the theory-practice gap.
Design/method/approach
Results are generated by analyzing innovation and innovation processes in five cases of long-term successful FF. On the basis of these good practice cases, the “rules of the game” of innovating are re-constructed using fine and system analyses based on narrative interviews with the FF CEOs.
Findings
Intense reflection on the innovation characteristics of the five good practice cases along with a critical examination of the literature on innovation in FF were used to derive practical suggestions for FF in the form of 11 principles for FF taking a proactive interest in innovation.
Practical implications
The 11 generated principles of successfully innovative FF were validated by FF CEOs who confirmed the practical relevance of these principles as valuable guidelines for successful innovation. Owners and managers may reflect on these principles against the background of the innovation behavior of their firms and adapt them to their contextual conditions.
Originality/value
These principles serve as tangible suggestions for developing adequate innovation management strategies for individual FF. Furthermore, two FF CEOs were invited to comment on the viability of principles based on their comprehensive practical experience.
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Maggie Foley, Richard J. Cebula, John Downs and Xiaowei Liu
The purpose of the current study is to identify variables that, when integrated into the random effects parametric survival model, could be used to forecast the failure rate of…
Abstract
Purpose
The purpose of the current study is to identify variables that, when integrated into the random effects parametric survival model, could be used to forecast the failure rate of small banks in the USA. A bank’s income production, efficiency and costs were taken into consideration when choosing the internal components. The breakout of the financial crisis, bank regulations that affect how the banking sector operates and the federal funds rate are the primary external variables.
Design/methodology/approach
This study uses the random effects parametric survival model to investigate the causes of small bank failures in the USA from 1996 to 2019. The study identifies several characteristics that failed banks frequently display. The main indications that may help to identify the elevated risk of small bank failures include the ROA, the cost of funds, the ratio of noninterest income to assets, the ratio of loan and lease losses to assets, noninterest expenses and core capital (leverage) ratio to assets. Economic disruptions, financial market distress and industry-based regulatory redress by the government exacerbate the financial distress borne by small banks.
Findings
The study revealed that a failed bank typically demonstrates a certain number of characteristics. The key factors that might assist identify which bank would be most likely to collapse include the cost of funding earning assets, the yield on earning assets, core Capital (leverage) ratio to assets, loan and lease loss provision to assets, noninterest expense and noninterest income to assets. Additionally, when a financial crisis occurs or the government changes regulations that could raise the cost of compliance for small banks, the likelihood that a bank will fail increases.
Originality/value
Models based on survival theories are more suitable when the authors examine bank failure as a unique event that happens gradually. The authors use a random effects parametric survival model to investigate the internal and external factors that may influence prospective small bank failure. This model has been developed and used in the medicinal research field. The authors do not choose the Cox proportional hazards model because it does not work well with panel data.