Juan Daniel Trejos, Luis Arturo Reyes, Carlos Garza, Patricia Zambrano and Omar Lopez-Botello
An experimental and numerical study of thermal profiles of 316 L stainless steel during selective laser melting (SLM) was developed. This study aims to present a novel approach to…
Abstract
Purpose
An experimental and numerical study of thermal profiles of 316 L stainless steel during selective laser melting (SLM) was developed. This study aims to present a novel approach to determine the significance and contribution of thermal numerical modeling enhancement factors of SLM.
Design/methodology/approach
Surface and volumetric heat models were proposed to compare the laser interaction with the powder bed and substrate, considering the powder size, absorptance and propagation of the laser energy through the effective depth of the metal layer. The approach consists in evaluating the contribution of the thermal conductivity anisotropic enhancement factors to establish the factors that minimized the error of the predicted results vs the experimental data.
Findings
The level of confidence of the carried-out analysis is of 97.8% for the width of the melt pool and of 99.8% for the depth of the melt pool. The enhancement factors of the y and z spatial coordinates influence the most in the predicted melt pool geometry.
Research limitations/implications
Nevertheless, the methodology presented in this study is not limited to 316 L stainless steel and can be applied to any metallic material used for SLM processes.
Practical implications
This study is focused on 316 L stainless steel, which is commonly used in SLM and is considered a durable material for high-temperature, high-corrosion and high-stress situations.
Social implications
The additive manufacturing (AM) technology is a relatively new technology becoming global. The AM technology may have health benefits when compared to the conventional industrial processes, as the workers avoid extended periods of exposure present in conventional manufacturing.
Originality/value
This study presents a novel approach to determine the significance and contribution of thermal numerical modeling enhancement factors of SLM. It was found that the volumetric heat model and anisotropic enhancement thermal approaches used in the present research, had a good agreement with experimental results.
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Sultan AlRedha, Anton Shterenlikht, Mahmoud Mostafavi, Derreck Van Gelderen, Omar Eduardo Lopez-Botello, Luis Arturo Reyes, Patricia Zambrano and Carlos Garza
A key challenge found in additive manufacturing is the difficulty to produce components with replicable microstructure and mechanical performance in distinct orientations. This…
Abstract
Purpose
A key challenge found in additive manufacturing is the difficulty to produce components with replicable microstructure and mechanical performance in distinct orientations. This study aims to investigate the influence of build orientation on the fracture toughness of additively manufactured AlSi10Mg specimens.
Design/methodology/approach
The AlSi10Mg specimens were manufactured using the selective laser melting (SLM) technology. The fracture toughness was experimentally determined (under ASTM E399-09) using C(T) specimens manufactured in different orientations. The microstructure of the specimens was examined using metallography to determine the effects of grain orientation on fracture toughness.
Findings
The fracture toughness magnitude of manufactured specimens ranged between 36 and 50 MPam, which closely matched conventional bulk material and literature values regarding AlSi10Mg components. The C(T) specimens printed in the T-L orientation yielded the highest fracture toughness. The grain orientation and fracture toughness values confirm the anisotropic nature of SLM parts where the T-L-oriented specimen obtained the highest KIC value. A clear interaction between the melt pool boundaries and micro-slipping during the loading application was observed.
Originality/value
The novelty of this paper consists in elucidating the relationship between grain orientation and fracture toughness of additively manufactured AlSi10Mg specimens because of the anisotropy generated by the different melting pool boundaries and orientations in SLM. The findings show that melt pool boundaries can behave as easier pathways for cracks to propagate and subsequently reduce the fracture toughness of specimens with cracks perpendicular to the build direction.
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José Cabral Miramontes, Gabriela Karina Pedraza Basulto, Citlalli Gaona Tiburcio, Patricia Del Carmen Zambrano Robledo, Carlos Agustín Poblano Salas and Facundo Almeraya Calderón
The thermal spraying technique of High-Velocity Oxygen Fuel (HVOF) coating was used to deposit coatings of an alloy composed of Ni-based substrates on stainless steel AISI 304…
Abstract
Purpose
The thermal spraying technique of High-Velocity Oxygen Fuel (HVOF) coating was used to deposit coatings of an alloy composed of Ni-based substrates on stainless steel AISI 304. The aim of this study was to determine the mechanical properties such as hardness and bond strength that these coatings have when the spray distance is varied, as well as the microstructure and phases formed during the thermal spray process.
Design/methodology/approach
The coatings were applied by HVOF and characterized by scanning electron microscopy, image analysis, X-ray diffraction, microhardness and bond strength to analyze the mechanical properties.
Findings
The microstructure of the coatings showed low porosity, oxide content and interface contamination in the substrate–coating interface, without the presence of unmolten particles. The microhardness values reached 600 HV for the three spray distances used and the bond strength values reached over 55 MPa.
Practical implications
The use of coatings on aircraft components is growing dramatically owing to the high costs of advanced materials and the growing lifecycle requirements for high-performance systems, which are taken into account because of the variety of coatings and complexity of environmental factors.
Originality/value
The originality of this study lies in the development of new coating materials for the manufacture and protection of various turbine components. The value is based on the development of materials and processes to be used to manufacture them.
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Francisco Villarreal-Valderrama, Carlos Santana Delgado, Patricia Del Carmen Zambrano-Robledo and Luis Amezquita-Brooks
Reducing fuel consumption of unmanned aerial vehicles (UAVs) during transient operation is a cornerstone to achieve environment-friendly operations. The purpose of this paper is…
Abstract
Purpose
Reducing fuel consumption of unmanned aerial vehicles (UAVs) during transient operation is a cornerstone to achieve environment-friendly operations. The purpose of this paper is to develop a control scheme that improves the fuel economy of a turbojet in its full operating envelope.
Design/methodology/approach
A novel direct-thrust linear quadratic integral (LQI) approach, comprised by an optimal observer/controller satisfying specified performance parameters, is presented. The thrust estimator, based in a Wiener model, is validated with the experimental data of a micro-turbojet. Model uncertainty is characterized by analyzing variations between the identified model and measured data. The resulting uncertainty range is used to verify closed-loop stability with the circle criterion. The proposed controller provides stable responses with the specified performance in the whole operating range, even with after considering plant nonlinearities. Finally, the direct-thrust LQI is compared with a standard thrust controller to assess fuel economy and performance.
Findings
The direct-thrust LQI approach reduced the fuel consumption by 2.1090% in the most realistic scenario. The controllers were also evaluated using the environmental effect parameter (EEP) and transient-thrust-specific fuel consumption (T-TSFC). These novel metrics are proposed to evaluate the environmental impact during transient-thrust operations. The direct-thrust LQI approach has a more efficient fuel consumption according to these metrics. The results also show that isolating the thrust dynamics within the feedback loop has an important impact in fuel economy. Controllers were also evaluated using the EEP and T-TSFC. These novel metrics are proposed to evaluate the environmental impact during transient-thrust operations. The direct-thrust LQI approach has a more efficient fuel consumption according to these metrics. The results also show that isolating the thrust dynamics within the feedback loop has an important impact in fuel economy.
Originality/value
This study shows the design of an effective direct-thrust control approach that minimizes fuel consumption, ensures stable responses for the full operation range, allows isolating the thrust dynamics when designing the controller and is compatible with classical robustness and performance metrics. Finally, the study shows that a simple controller can reduce the fuel consumption of the turbojet during transient operation in scenarios that approximate realistic operating conditions.
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José Francisco Villarreal Valderrama, Luis Takano, Eduardo Liceaga-Castro, Diana Hernandez-Alcantara, Patricia Del Carmen Zambrano-Robledo and Luis Amezquita-Brooks
Aircraft pitch control is fundamental for the performance of micro aerial vehicles (MAVs). The purpose of this paper is to establish a simple experimental procedure to calibrate…
Abstract
Purpose
Aircraft pitch control is fundamental for the performance of micro aerial vehicles (MAVs). The purpose of this paper is to establish a simple experimental procedure to calibrate pitch instrumentation and classical control algorithms. This includes developing an efficient pitch angle observer with optimal estimation and evaluating controllers under uncertainty and external disturbances.
Design/methodology/approach
A wind tunnel test bench is designed to simulate fixed-wing aircraft dynamics. Key elements of the instrumentation commonly found in MAVs are characterized in a gyroscopic test bench. A data fusion algorithm is calibrated to match the gyroscopic test bench measurements and is then integrated into the autopilot platform. The elevator-angle to pitch-angle dynamic model is obtained experimentally. Two different control algorithms, based on model-free and model-based approaches, are designed. These controllers are analyzed in terms of parametric uncertainties due to wind speed variations and external perturbation because of sudden weight distribution changes. A series of experimental tests is performed in wind-tunnel facilities to highlight the main features of each control approach.
Findings
With regard to the instrumentation algorithms, a simple experimental methodology for the design of optimal pitch angle observer is presented and validated experimentally. In the context of the platform design and identification, the similitude among the theoretical and experimental responses shows that the platform is suitable for typical pitch control assessment. The wind tunnel experiments show that a fixed linear controller, designed using classical frequency domain concepts, is able to provide adequate responses in scenarios that approximate the operation of MAVs.
Research limitations/implications
The aircraft orientation observer can be used for both pitch and roll angles. However, for simultaneousyaw angle estimation the proposed design method requires further research. The model analysis considers a wind speed range of 6-18 m/s, with a nominal operation of 12 m/s. The maximum experimentally tested reference for the pitch angle controller was 20°. Further operating conditions may require more complex control approaches (e.g. scheduling, non-linear, etc.). However, this operating range is enough for typical MAV missions.
Originality/value
The study shows the design of an effective pitch angle observer, based on a simple experimental approach, which achieved locally optimum estimates at the test conditions. Additionally, the instrumentation and design of a test bench for typical pitch control assessment in wind tunnel facilities is presented. Finally, the study presents the development of a simple controller that provides adequate responses in scenarios that approximate the operation of MAVs, including perturbations that resemble package delivery and parametric uncertainty due to wind speed variations.
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Dolores Rando Cueto, Carmen Jambrino-Maldonado, Gloria Jiménez-Marín and Patricia P. Iglesias-Sánchez
Organizational happiness has received exponential attention in recent years. To offer an over-view for future research gap, this article produces a comprehensive review by…
Abstract
Purpose
Organizational happiness has received exponential attention in recent years. To offer an over-view for future research gap, this article produces a comprehensive review by combining bibliometric analysis and interviews to key authors in the field. The main objective of this paper is to show the state of research regarding the environment in the management of happiness in organizations: the evolution of scientific activity, current trends in authorship, topics and future setting research agenda.
Design/methodology/approach
The methodological process focuses on a mixed method. A systematic review of the relevant literature; bibliometric analysis and network mapping in the Web of Science and Scopus data-bases; bibliometric network analysis of authorship, citation and co-occurrence of key words in scientific publications.
Findings
The results reveal that happiness management is gaining importance and, moreover, more than half of the publications about happiness management are related to the environment in which the organizations are immersed. Therefore, the study provides some research directions and insists on role of environment to better understand the theoretical and practical perspectives. Likewise, bibliometric analysis and interviews allow to measure quality, impact, productivity and scientific evolution which are increasingly valued in order to identify the main concepts and topics that are considered key, drivers of research and those gaps that should be addressed in future research work for the conceptual framework of happiness management in organizations.
Originality/value
Conclusions are drawn that promoting corporate social responsibility strategies, aimed at fostering sustainability and care for the environment result in the well-being of organizations and the performance of their workers are highlighted.
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In the twenty-first century, the family has been turning towards a greater plurality of training paths, situations, family and parental arrangements. However, despite changes in…
Abstract
In the twenty-first century, the family has been turning towards a greater plurality of training paths, situations, family and parental arrangements. However, despite changes in legislation, values, representations and practices, the word family remains inexorably associated with the heterosexual bi-parental model. This paper aims to contribute to the knowledge of the family dynamics of non-heterosexual people, mainly concerning the process of transition to parenting, in relation to family changes in Portuguese society. To do so this study aims to analyze four in-depth interviews1 with young adults, women and men who have a homoconjugality relationship and a project of parenting in mind.
Based on a qualitative methodology the study intends to discuss issues related to the challenge of heteronormativity, equality within the couple, projects and gender representations of parenthood and in particular what it means for the men and women interviewed, to be a father and to be a mother in a same sex couple and how they project themselves as fathers and mothers.
The study discusses all these issues always in relation to the biographical trajectories, the history and life as a couple and the structural and individual resources, such as school and professional qualifications. It also analyzes the main difficulties experienced in revealing their sexuality to the significant others and the difficulties / strategies they anticipate in relation to the parenting project.
The authors conclude that female interviewees show greater independence of a male figure in relation to their parental projects and anticipate less difficulty in their parental skills compared with the gay man interviewed.
To analyze the dynamics of parenting in same-sex couples, this study also points out to the need to construct a model of analysis capable of articulating structural factors, such as job insecurity and heteronormativity, biographies and individual resources and profiles of conjugal interactions.
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Patricia Picazo, Sergio Moreno-Gil and Dogan Gursoy
Examination of the image projected through photographs used in marketing materials can enable managers to identify opportunities for creating differentiated positioning in the…
Abstract
Purpose
Examination of the image projected through photographs used in marketing materials can enable managers to identify opportunities for creating differentiated positioning in the marketplace. However, the impact of image projected through photographs has not received much attention in academic literature. This paper aims to establish a methodology using dynamic indices that allow a systematic comparative evaluation of the image projected through photographs used in marketing materials of lodging properties located in competing destinations. It also provides an empirical examination of the type of image projected through photographs of lodging properties in those destinations.
Design/methodology/approach
Analysis was conducted using a content analysis methodology. A total of 17,187 photographs of 5,820 lodging properties located in 15 different tourism destinations over a period of eight years were examined.
Findings
Results revealed that the proposed methodology based on dynamic comparative indices is appropriate for determining the projected image of lodging properties. The dynamic indices, which categorise photographs in three main categories: subject (people), activities (actions carried out) and contextualisation (location), allowed a systematic evaluation of the image projected of lodging properties in competing destinations. Results of the empirical analysis indicated important differences in the image projected through photographs among lodging properties located in 15 destinations.
Practical implications
This study provides the industry and destination marketing organisations (DMOs) with a useful and simple tool for comparatively evaluating the image projected by tourism accommodations. The methodology proposed enables managers to identify the current image and the changes in the image of their lodging properties, their destinations and those of their main competitors over the years, thus providing opportunities for development of more effective differentiation and positioning strategies in their respective target markets.
Originality/value
The proposed tool provides a methodology that can be used to categorise and evaluate the image represented on the photographs used in marketing materials to ensure the projection of the intended image. Furthermore, the proposed methodological tool enables managers to monitor the image projected through photographs used in competitors’ marketing materials and identify changes in their image projected over time.
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Laura Alicia Valdiviezo, Rukmini Becerra Lubies and Dayna Andrea Moya Sepulveda
The creation of intercultural education in the Quechua and Mapuche contexts, in Peru and Chile respectively, marks a milestone in the institutionalisation of equity-oriented state…
Abstract
The creation of intercultural education in the Quechua and Mapuche contexts, in Peru and Chile respectively, marks a milestone in the institutionalisation of equity-oriented state policies that deserves attention given the serious inequalities that still persist in these societies. In this chapter, we analyse ethnographic studies of intercultural knowledge and practices inside and outside the classroom and interpret them as catalysts for equity in education. The findings of the analysis point to the centrality of Indigenous actors as transformative agents inside and outside the classroom and the urgency of restructuring not only education but also society towards equity.
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Nceba Ndzwayiba and Lieketseng Ned
The purpose of this research is to investigate the process of development and implementation of strategies to promote diversity and inclusion of persons with disabilities in the…
Abstract
Purpose
The purpose of this research is to investigate the process of development and implementation of strategies to promote diversity and inclusion of persons with disabilities in the workplace within Netcare (the largest private hospital group) in South Africa.
Methodology/approach
A single case study methodology is used to document best practices developed at Netcare for the integration of persons with disabilities in the workplace.
Findings
The case study demonstrates that integrating people with disabilities in the workplace is a complex process that requires bringing together disability theory/model and organizational change models. Disability integration within Netcare is an ongoing process with positive gains and gaps that can be leveraged to improve the process. Nonetheless, significant improvements in the number of persons with disability integrated at work as well as a good retention rate in the skills development program have been realized.
Practical implications
The documentation of practice based initiatives such as those developed by Netcare is useful for future cross-organizational and cross-context comparative studies. This will ultimately redirect policy and research agendas from the deficit analysis approach towards a more positive inquiry based upon practical and workable solutions.
Social implications
The treatment of disability as a silo identity does not provide full appreciation of the multiple intersecting identities that interlock to position some persons with disabilities in positions of privilege and marginalization simultaneously.
Originality/value
This chapter reveals the importance of situating disability mainstreaming within a broader organizational transformation strategy. Legislating social and organizational transformation issues is necessary but insufficient to produce the desired social change. This research highlights the value of inculcating transformative leadership culture and building leadership accountability to realize the desired social and organizational change.