Andreas Maier, Manuel Rühr, Katja Tangermann-Gerk, Marcel Stephan, Stephan Roth and Michael Schmidt
Additive manufacturing (AM) of duplex stainless steels (DSS) is still challenging in terms of simultaneously generating structures with high build quality and adequate functional…
Abstract
Purpose
Additive manufacturing (AM) of duplex stainless steels (DSS) is still challenging in terms of simultaneously generating structures with high build quality and adequate functional properties. This study aims to investigate comprehensive process-material-property relationships resulting from both laser-directed energy deposition (DED-LB/M) and laser powder bed fusion (PBF-LB/M) of DSS 1.4462 in as-built (AB) and subsequent heat-treated (HT) states.
Design/methodology/approach
Cuboid specimens made of DSS 1.4462 were generated using both AM processes. Porosity and microstructure analyses, magnetic-inductive ferrite and Vickers hardness measurements, tensile and Charpy impacts tests, fracture analysis, critical pitting corrosion temperature measurements and Huey tests were performed on specimens in the AB and HT states.
Findings
Correlations between the microstructural aspects and the resulting functional properties (mechanical properties and corrosion resistance) were demonstrated and compared. The mechanical properties of DED-LB/M specimens in both material conditions fulfilled the alloy specifications of 1.4462. Owing to the low ductility and toughness of PBF-LB/M specimens in the AB state, a post-process heat treatment was required to exceed the minimum alloy specification limits. Furthermore, the homogenization heat treatment significantly improved the corrosion resistance of DED- and PBF-processed 1.4462.
Originality/value
This study fulfills the need to investigate the complex relationships between process characteristics and the resulting material properties of additively manufactured DSS.
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Philipp Heinemann, Michael Schmidt, Felix Will, Sascha Kaiser, Christoph Jeßberger and Mirko Hornung
The paper aims to assess the potential of aircraft operation from city centres to achieve shortened travel times and the involved aircraft design process.
Abstract
Purpose
The paper aims to assess the potential of aircraft operation from city centres to achieve shortened travel times and the involved aircraft design process.
Design/methodology/approach
The paper describes the methodical approach and iterative procedure of the design process. An assessment of potential technologies is conducted to provide the required enhancements to fulfil the constraints following an inner-city operation. Operational procedures were analysed to reduce the noise propagation through flight path optimization. Furthermore, a ground-based assisted take-off system was conceived to lower required take-off field length and to prevent engine sizing just for the take-off case. Cabin design optimization for a fast turnaround has been conducted to ensure a wide utilization spectrum. The results prove the feasibility of an aircraft developed for inner city operation.
Findings
A detailed concept for a 60-passenger single aisle aircraft is proposed for an Entry-Into-Service year 2040 with a design range of 1,500 nautical miles for a load factor of 90 per cent. Although the design for Short Take-off and Landing and low noise operation had to be traded partly with cruise efficiency, a noteworthy reduction in fuel burn per passenger and nautical mile could be achieved against current aircraft.
Practical implications
The findings will contribute to the evaluation of the feasibility and impact of the Flightpath 2050 goal of a 4-h door-to-door by providing a feasible but ambitious example. Furthermore, it highlights possible bottlenecks and problems faced when realizing this goal.
Originality/value
The paper draws its value from the consideration of the overall sizing effects at aircraft level and from a holistic view on an inner-city airport/aircraft concept design for a 4-h door-to-door goal.
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Tobias Kolb, Reza Elahi, Jan Seeger, Mathews Soris, Christian Scheitler, Oliver Hentschel, Jan Tremel and Michael Schmidt
The purpose of this paper is to analyse the signal dependency of the camera-based coaxial monitoring system QMMeltpool 3D (Concept Laser GmbH, Lichtenfels, Germany) for laser…
Abstract
Purpose
The purpose of this paper is to analyse the signal dependency of the camera-based coaxial monitoring system QMMeltpool 3D (Concept Laser GmbH, Lichtenfels, Germany) for laser powder bed fusion (LPBF) under the variation of process parameters, position, direction and layer thickness to determine the capability of the system. Because such and similar monitoring systems are designed and presented for quality assurance in series production, it is important to present the dominant signal influences and limitations.
Design/methodology/approach
Hardware of the commercially available coaxial monitoring QMMeltpool 3D is used to investigate the thermal emission of the interaction zone during LPBF. The raw images of the camera are analysed by means of image processing to bypass the software of QMMeltpool 3D and to gain a high level of signal understanding. Laser power, scan speed, laser spot diameter and powder layer thickness were varied for single-melt tracks to determine the influence of a parameter variation on the measured sensory signals. The effects of the scan direction and position were also analysed in detail. The influence of surface roughness on the detected sensory signals was simulated by a machined substrate plate.
Findings
Parameter variations are confirmed to be detectable. Because of strong directional and positional dependencies of the melt-pool monitoring signal a calibration algorithm is necessary. A decreasing signal is detected for increasing layer thickness. Surface roughness is identified as a dominating factor with major influence on the melt-pool monitoring signal exceeding other process flaws.
Research limitations/implications
This work was performed with the hardware of a commercially available QMMeltpool 3D system of an LPBF machine M2 of the company Concept Laser GmbH. The results are relevant for all melt-pool monitoring research activities connected to LPBF, as well as for end users and serial production.
Originality/value
Surface roughness has not yet been revealed as being one of the most important origins for signal deviations in coaxial melt-pool monitoring. To the best of the authors’ knowledge, the direct comparison of influences because of parameters and environment has not been published to this extent. The detection, evaluation and remelting of surface roughness constitute a plausible workflow for closed-loop control in LPBF.
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Mohammad Ravankhah, Michael Schmidt and Thomas Will
The purpose of this paper is to develop an integrated multi-risk identification procedure for World Cultural Heritage (WCH) sites exposed to seismic events, while considering…
Abstract
Purpose
The purpose of this paper is to develop an integrated multi-risk identification procedure for World Cultural Heritage (WCH) sites exposed to seismic events, while considering characteristics of disasters from earthquakes in a multi-hazard context on one side and particular aspects of WCH (e.g. outstanding universal values and associated condition of authenticity and integrity) on the other.
Design/methodology/approach
An interdisciplinary review of current relevant approaches, methods, and practices is conducted through the existing literature of disaster risk management, heritage conservation, and seismology. Furthermore, a document analysis of concrete cases affected by seismic events supports concepts and the procedure.
Findings
This paper results in a methodology of identifying multi-risk of disasters induced by earthquakes. A bow-tie analysis diagram in combination with a risk identification matrix is developed for illustrating a multiple emergency scenario in identifying possible impacts of earthquakes’ primary effects, secondary hazards, and human-threats on tangible and intangible attributes of cultural properties.
Practical implications
The research aims to provide specialists and practitioners from multiple sectors engaged in pre-disaster risk mitigation and preparedness plan for cultural heritage with a practical risk identification tool. The proposed method, in a multiple hazard context, intends to enhance risk assessment procedure for determining more appropriate risk reduction strategies in the decision-making process.
Originality/value
This paper, through emphasising “earthquake disaster risk” rather than “earthquake risk”, illuminates the significance of quake-followed secondary hazards, potential human-induced hazards and human errors in the risk identification process, due to the fact that while a disaster may begin with a quake, its full scope might be triggered by a combination of the mentioned potential threats.
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MICHAEL K. JUDIESCH, FRANK L. SCHMIDT and MICHAEL K. MOUNT
Recently, we (Judiesch, Schmidt, & Mount, 1992) concluded that the Schmidt et al. (1979) SDy estimation procedure results in downwardly biased estimates of utility. This…
Abstract
Recently, we (Judiesch, Schmidt, & Mount, 1992) concluded that the Schmidt et al. (1979) SDy estimation procedure results in downwardly biased estimates of utility. This conclusion led us to propose a modification of the Schmidt et al. method that involves estimating SDy as the product of estimates of the coefficient of variation (SDy/ Y) and an objective estimate of the average value of employee output (Y). The present article reviews the rationale underlying our conclusion that this modification of the Schmidt et al. method of estimating SDy results in more accurate estimates of SDy, and hence, utility.
The purpose of this paper is to propose a low-cost, high return model for implementing a programmatic foresight function that is collaboratively integrated with the organization’s…
Abstract
Purpose
The purpose of this paper is to propose a low-cost, high return model for implementing a programmatic foresight function that is collaboratively integrated with the organization’s existing policy, planning and intelligence (or policy research) functions. Focusing on government agencies, especially those supporting liberal democratic governments, the purpose of the current paper is to propose a new, practical, low-cost and high-return model for implementing a programmatic strategic foresight function that is collaboratively integrated with the organization’s existing policy, planning and intelligence functions. The paper describes the relevant organizational considerations and options for structural adjustments, and suggests how the proposed model can maximize decision-making effectiveness without disrupting pre-existing structures, operations and products. The paper further discusses the necessity and involvement of a central government foresight agency and a non-hierarchical distributed network linking the foresight units.
Design/methodology/approach
Possible solutions are considered with respect to costs of development and implementation, risk (likelihood, consequence and uncertainty) of the new function’s failure, direct negative or positive effect on the performance of existing functions, the level of cross-organizational involvement in or collaboration with the new function, the level of cross-organization tangible benefits and the level of vertical involvement, especially at the executive level.
Findings
With few exceptions, the implementation of foresight by governments has not been at all methodical, but has followed many different paths, where it has occurred at all. The approach proposed in this paper – establishing a central foresight agency, propagating individual agency-based small programmatic foresight units and virtual teams and creating a non-hierarchical distributed network to link all of them – appears to best meet the success criteria set out in the paper.
Research limitations/implications
Governments, especially liberal democratic ones, and their agencies that have previously shied away from methodically implementing strategic foresight or that have attempted to do so without real success now have an approach that is likely to produce the desired results.
Practical implications
The paper creates a sound framework for governments, especially liberal democratic ones, and their agencies to consider and proceed with the implementation of foresight functions and networks to support them.
Originality/value
The proposed approach is entirely new and generally challenges current practices.
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In 2001, the rape of “baby Tshepang” triggered a media frenzy in the small community of Louisvale, located in the Northern Cape of South Africa. The purpose of this chapter is to…
Abstract
Purpose
In 2001, the rape of “baby Tshepang” triggered a media frenzy in the small community of Louisvale, located in the Northern Cape of South Africa. The purpose of this chapter is to explore how gender discrimination and colonial discourse framed the way the rape of Tshepang was reported in print media.
Design/methodlogy/approach
From the newspaper archives of the Cape Town National Library, the University of Cape Town Library as well as newspaper articles found online, this chapter offers a reading of articles printed between 2001 and 2004. Patterns of troping were identified from the articles examined, and a number of themes were selected to be further examined using a gender perspective. Work already done by African feminist scholars on the grammar of rape was applied to deconstruct the ways in which the media presented this specific case. This chapter works with Sara Ahmed’s (2004) thoughts on shame, Linda Alcoff’s (1991) writing on Othering, Helen Moffett (2003a, 2003b, 2003c, 2006) and Jane Bennett’s (1997) work on gender and rape, as well as Achille Mbembe’s (2001) notion of facticity within colonial discourse.
Findings
This chapter argues that the ways in which the media understood this event were through well-worn stereotypes of Africa and women. An overarching theme of shame dominated how journalists represented the event. The label “A Town of Shame” stuck onto Louisvale through the mobilization of colonial and gender discourse. Quickly the town was known for its “barbaric” and “savage” existence; a town with no future and a disgrace to the country. Essentialist thinking about women was used to condemn and blame the mother of Tshepang, concretizing the myth that rape is always the fault of women.
Social Implications
Through relying on palatable stereotypes that create a self and Other, we move further away from engaging in the difficult questions of understanding rape. When rape becomes a spectacle, detached from the greater global socioeconomic realities, we deny our responsibilities of difficult and multilayered engagement.
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Christina Blümel, Marius Sachs, Tobias Laumer, Bettina Winzer, Jochen Schmidt, Michael Schmidt, Wolfgang Peukert and Karl-Ernst Wirth
The purpose of this paper is to demonstrate the processability of cohesive PE-HD particles in laser beam melting processes (LBM) of polymers. Furthermore, we present a…
Abstract
Purpose
The purpose of this paper is to demonstrate the processability of cohesive PE-HD particles in laser beam melting processes (LBM) of polymers. Furthermore, we present a characterization method for polymer particles, which can predict the quality of the powder deposition via LBM processes.
Design/methodology/approach
This study focuses on the application of dry particle coating processes to increase flowability and bulk density of PE-HD particles. Both has been measured and afterwards validated via powder deposition of PE-HD particles in a LBM machine.
Findings
For efficient coating in a dry particle coating process, the PE-HD particles and the attached nanoparticles need to show similar surface chemistry, i.e. both need to behave either hydrophobic or hydrophilic. It is demonstrated that dry particle coating is appropriate to enhance flowability and bulk density of PE-HD particles and hence considerably improves LBM processes and the resulting product quality.
Originality/value
At present, in LBM processes mainly polyamide (PA), 12 particles are used, which are so far quite expensive in comparison to, for example, PE-HD particles. This work provides a unique and versatile method for nanoparticulate surface modification which may be applied to a wide variety of materials. After the coating, the particles are applicable for the LBM process. Our results provide a correlation between flowability and bulk density and the resulting product quality.
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Scott Dacko, Rainer Schmidt, Michael Möhring and Barbara Keller
- Appreciate the scope and pervasiveness of fake reviews in retailing
- Recognise the causes of fake reviews in retailing
- Understand consumer responses to fake reviews in retail
- …
Abstract
Learning Outcomes
Appreciate the scope and pervasiveness of fake reviews in retailing
Recognise the causes of fake reviews in retailing
Understand consumer responses to fake reviews in retail
Understand how retailers can and should manage fake reviews
Understand better the expected future of retail with fake reviews
Appreciate the scope and pervasiveness of fake reviews in retailing
Recognise the causes of fake reviews in retailing
Understand consumer responses to fake reviews in retail
Understand how retailers can and should manage fake reviews
Understand better the expected future of retail with fake reviews
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Contrary to my expectations, the old adage holds true – “absence makes the heart grow fonder” – even in the context of higher education. If someone would have asked me 15 years…
Abstract
Contrary to my expectations, the old adage holds true – “absence makes the heart grow fonder” – even in the context of higher education. If someone would have asked me 15 years ago if I would miss my time at the copy machine in the Marketing Department or in the library or stressing about comprehensive exams or my dissertation, my answer would have been a resounding “NO!” Now that I realize what a luxury it was to be focused exclusively on learning and research without all of the other obligations of tenured faculty life, I remember my days at MSU fondly. I can almost say I even miss the winters! However, since joining North Carolina State University in 1995, the key word in that last sentence is “almost”.