Andrea Corrado, Wilma Polini, Giovanni Moroni and Stefano Petrò
The purpose of this work is to present a variational model able to deal with form tolerances and assembly conditions. The variational model is one of the methods proposed in…
Abstract
Purpose
The purpose of this work is to present a variational model able to deal with form tolerances and assembly conditions. The variational model is one of the methods proposed in literature for tolerance analysis, but it cannot deal with form tolerances and assembly conditions that may influence the functional requirements of mechanical assemblies.
Design/methodology/approach
This work shows how to manage the actual surfaces generated by the manufacturing process and the operating conditions inside the variational model that has been modified to integrate the manufacturing signature left on the surfaces of the parts and the operating conditions that arise during an actual assembly, such as gravity and friction. Moreover, a geometrical model was developed to numerically simulate what happens in a real assembly process and to give a reference value.
Findings
The new variational model was applied to a three-dimensional case study. The obtained results were compared to those of the geometrical model and to those of the variational model to validate the new model and to show the improvements.
Research limitations/implications
The proposed approach may be extended to other models of literature. However, its limitation is that it is able to deal with a sphere–plane contact.
Practical implications
Tolerance analysis is a valid tool to foresee geometric interferences among the components of an assembly before getting the physical assembly. It involves a decrease in the manufacturing costs.
Originality/value
The main contributions of the study are the insertion of a systematic pattern characterizing the features manufactured by a process, assembly operating conditions and development of a geometrical model to reproduce what happens in a real assembly process.
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Luis Lisandro Lopez Taborda, Heriberto Maury and Jovanny Pacheco
There are many investigations in design methodologies, but there are also divergences and convergences as there are so many points of view. This study aims to evaluate to…
Abstract
Purpose
There are many investigations in design methodologies, but there are also divergences and convergences as there are so many points of view. This study aims to evaluate to corroborate and deepen other researchers’ findings, dissipate divergences and provide directing to future work on the subject from a methodological and convergent perspective.
Design/methodology/approach
This study analyzes the previous reviews (about 15 reviews) and based on the consensus and the classifications provided by these authors, a significant sample of research is analyzed in the design for additive manufacturing (DFAM) theme (approximately 80 articles until June of 2017 and approximately 280–300 articles until February of 2019) through descriptive statistics, to corroborate and deepen the findings of other researchers.
Findings
Throughout this work, this paper found statistics indicating that the main areas studied are: multiple objective optimizations, execution of the design, general DFAM and DFAM for functional performance. Among the main conclusions: there is a lack of innovation in the products developed with the methodologies, there is a lack of exhaustivity in the methodologies, there are few efforts to include environmental aspects in the methodologies, many of the methods include economic and cost evaluation, but are not very explicit and broad (sustainability evaluation), it is necessary to consider a greater variety of functions, among other conclusions
Originality/value
The novelty in this study is the methodology. It is very objective, comprehensive and quantitative. The starting point is not the case studies nor the qualitative criteria, but the figures and quantities of methodologies. The main contribution of this review article is to guide future work on the subject from a methodological and convergent perspective and this article provides a broad database with articles containing information on many issues to make decisions: design methodology; optimization; processes, selection of parts and materials; cost and product management; mechanical, electrical and thermal properties; health and environmental impact, etc.
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Political Science in the United States has focused too much on variable-oriented, quantitative methods and thus lost its ability to ask “big questions.” Stein Rokkan (d. 1979) was…
Abstract
Political Science in the United States has focused too much on variable-oriented, quantitative methods and thus lost its ability to ask “big questions.” Stein Rokkan (d. 1979) was an eminent comparativist who asked big questions and provided such qualitative tools as conceptual maps, grids, and clustered comparisons. Ibn Khaldun (d. 1406), arguably the first social scientist, also asked big questions and provided a universal explanation about the dialectical relationship between nomads and sedentary people. This article analyzes to what extent Ibn Khaldun's concepts of asabiyya and sedentary culture help understand the rise and fall of the Muslim civilization. It also explores my alternative, class-based perspective in Islam, Authoritarianism, and Underdevelopment. Moreover, the article explores how Rokkan's analysis of cultural, geographical, economic, and religio-political variations within Western European states can provide insights to the examination of such variations in the Muslim world.
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Antonella Fiorillo, Alfonso Sorrentino, Arianna Scala, Vincenzo Abbate and Giovanni Dell'aversana Orabona
The goal was to improve the quality of the hospitalization process and the management of patients, allowing the reduction of costs and the minimization of the preoperative Length…
Abstract
Purpose
The goal was to improve the quality of the hospitalization process and the management of patients, allowing the reduction of costs and the minimization of the preoperative Length of Hospital Stay (LOS).
Design/methodology/approach
The methodology used to improve the quality of the hospitalization process and patient management was Lean Thinking. Therefore, the Lean tools (Value stream map and Ishikawa diagram) were used to identify waste and inefficiencies, improving the process with the implementation of corrective actions. The data was collected through personal observations, patient interviews, brainstorming and from printed medical records of 151 patients undergoing oral cancer surgery in the period from 2006 to 2018.
Findings
The authors identified, through Value Stream Map, waste and inefficiencies during preoperative activities, consequently influencing preoperative LOS, considered the best performance indicator. The main causes were identified through the Ishikawa diagram, allowing reflection on possible solutions. The main corrective action was the introduction of the pre-hospitalization service. A comparative statistical analysis showed the significance of the solutions implemented. The average preoperative LOS decreased from 4.90 to 3.80 days (−22.40%) with a p-value of 0.001.
Originality/value
The methodology allowed to highlight the improvement of the patient hospitalization process with the introduction of the pre-hospitalization service. Therefore, by adopting the culture of continuous improvement, the flow of hospitalization was redrawn. The benefits of the solutions implemented are addressed to the patient in terms of lower LOS and greater service satisfaction and to the hospital for lower patient management costs and improved process quality. This article will be useful for those who need examples on how to apply Lean tools in healthcare.