1,721,087 research outputs found
Erratum to: “A sustainable EOQ model: Theoretical formulation and applications” [Int. J. Prod. Econ. 149 2014 145–153] (International Journal of Production Economics (2014) 149 (145–153), (S092552731300296X), (10.1016/j.ijpe.2013.06.026))
No full textIn this erratum, we correct a typo in the formulations, due to the omission of one parameter, that appears in our paper “A sustainable EOQ model: Theoretical formulation and applications” (Battini, D., Persona, A., Sgarbossa, F., 2014). Erratum In the paper (Battini, D., Persona, A., Sgarbossa, F., 2014), equation (6) presents one typo, since the parameter b (space occupied by a product unit [m3/unit]) is omitted. The correct equation (6) and related equations (10)–(12) are as follows: [Formula presented] [Formula presented] [Formula presented] [Formula presented] This typo about the parameter b is also in equation, based on the same approach of equations (6) and (10). The correct equation (18) and related equations (19)–(21) will be: [Formula presented] [Formula presented] [Formula presented]. Finally, we would like to take this opportunity also to inform the reader that there are other small typos, due to the copy and paste of values formatting table 4 of Battini et al. (2014). These typos are not related to the previous omission of the parameter b. The correct value of the C(EOQ) in Case 2 is 417,336.47 instead of 419,719.47, the correct value of C(S-EOQ) is 418,990.90 instead of 421,367.07 and the internal transportation cost is 7530.59 instead of 9910.59. As a consequence, also Fig. 5 at Battini et al. (2014), representing these values, will be slightly different. Acknowledgements We would like to thank Leopoldo Eduardo Cárdenas-Barrón and Alfonso Angel Medina-Santana from Tecnológico de Monterrey, Mexico. Their valuable attention in reading and checking the paper helped us in correcting this typo. Reference Battini, D., Persona, A., & Sgarbossa, F. (2014). A sustainable EOQ model: Theoretical formulation and applications. International Journal of Production Economics, 149, 145-153
FEM Simulation of Subintimal Angioplasty for the Treatment of Chronic Total Occlusions
Full text linkSub-intimal angioplasty is a highly challenging technique for percutaneous treatment of chronic total occlusion (CTO) in blood vessels and the development of predictive tools for preliminary evaluation of potential outcomes and risks could be very useful for clinicians. While Finite Element (FE) simulation is a well established approach to investigate partial occlusions, its extension to CTO has not been investigated yet, because of several additional issues that have to be addressed.
In this work, we discuss the implementation of a FE model to simulate the main steps of the procedure, i.e. sub-intimal insertion of an initially folded balloon in a false lumen, inflation from eccentric position, deflation and extraction. The model includes key morphological features of the CTO and possibility to vary spatial distribution of material properties to account for different constituents and degree of calcification. Both homogeneous and heterogeneous CTO configurations were analysed, comparing arterial stress state, plaque compression and post-procedural recoil. For a peak inflation pressure of 12 bar, the degree of lumen restoration was in the range 65-80%, depending on plaque heterogeneity. After balloon extraction, homogeneous highly calcified plaques exhibited substantial recovery of original shape. For homogeneous and heterogeneous CTO values of peak von Mises stress in the arterial wall were of the same order of magnitude (range 1-1.1 MPa) but at different locations. Results compared favourably with data reported in literature for post-procedural lumen restoration and arterial stress data, confirming potential usefulness of the approach
A Model for the Assessment of Wheel–Rail Contact in the Presence of Solid Contaminants
No full textAn analytical model for the assessment of a contact in the presence of a solid contaminant is presented, mainly aimed at studying the damage to railway wheels and rails operating in third-bodycontaminated environments. The model, developed under 2D plane strain idealization, includes multiple evenly spaced rigid cylindrical contaminant bodies entrapped between two elastic cylinders. It allows a very fast calculation of the pressure distribution on the surfaces in contact and it can be used for evaluating the stress field in the subsurface region, at both the small scale of the contact between the main body and the contaminant body and the full scale of the contact between the two main bodies. The model was validated by comparison with finite element (FE) analyses, showing its accuracy. Some examples of application showed the model’s ability to predict the limit of the influence of the solid contaminant bodies and the depth where cyclic plasticity phenomena occur in wheel–rail contacts
A Multi-Criteria Decision-Making Model Based on Fuzzy Logic and AHP for the Selection of Digital Technologies
Full text linkThe presence of Industry 4.0 national plans and the ever-increasing international competition are forcing companies to embark on digitalization projects of their industrial plants. Time and money, however, are a constraint and, in addition to that, there is a considerable lack of works in the academic literature with regards to specific models for the selection of digital technologies. Starting from our methodological framework, we developed a multi-criteria decision-making model for the digitalization of industrial plants. The model is based on both Fuzzy Logic and AHP and is combined with an existing hierarchical classification of digital technologies in an attempt to highlight the advantage of adopting similar and easily interconnectable technologies. Finally, the model is applied to a simple case study to test its validity. © 2022 Elsevier B.V.. All rights reserved
Effects of fiber layout on strength and failure of 3D printed notched composites
Full text linkThis study investigates the effect of printing strategies on the strength of additively manufactured notched fiber
reinforced composite specimens. Specimens with varying notch geometries (two radii and two opening angles)
and fiber layouts (unreinforced, unidirectional, quasi-isotropic and concentric) were 3D printed and tested under
tension. Digital image correlation provided surface strain field data. Results showed that fiber deposition patterns
significantly impact notch sensitivity, failure loads and mechanisms, with notch geometry being of secondary
importance. The unidirectional layout achieved the highest strength but with progressive failure, while quasiisotropic
specimens failed abruptly from the notch. The concentric layout shielded the notch region but
induced premature failure away from the notch due to transverse stress. Stress concentration factor approaches,
which work well for conventional laminates, have limitations for 3D printed composites due to local differences
and complex interactions. Optimizing fiber deposition, instead of geometry, emerges as a promising design route.
Combining unidirectional and contouring algorithms may improve performance. However, further studies utilizing
multiscale modelling and local failure analyses are needed to fully understand failure mechanisms and
guide optimal notch designs for 3D printed composites. With improved understanding and design methods, 3D
printing promises to unlock new possibilities for structurally efficient notched composite parts
Finite element modelling of 3D printed continuous carbon fiber composites: Embedded elements technique and experimental validation
Full text linkIncreasing supply chain resilience through efficient redundancy allocation: A risk-averse mathematical model
Full text linkThe COVID-19 pandemic has created significant uncertainty in all areas of life, including supply chains (SCs). This paper presents a new risk-averse mixed-integer nonlinear problem mathematical model for the design and planning of a two -echelon resilient SC network. Disruption events, which can partially or completely reduce the available capacity, are included in the model. The model's objective is to minimise the total costs by determining the optimal facility location and capacity, allocation flows and resilience actions for hedging against disruption risk. A solution procedure is tested through computational experiments, and managerial insights were formed based on a numerical example for several disruption configurations, with a specific case of long-term crises similar to the COVID-19 pandemic. The results showed that recovery activities are the most efficient actions to take for a short-term disruption event. Besides, proactive resilience investment in a protection system and flexibility enhancement allows the SC to handle the disruption period with a limited increase in network building costs and overcapacity. Copyright (C) 2021 The Authors
Efficient resilience portfolio design in the supply chain with consideration of preparedness and recovery investments
No full textSupply chain (SC) resilience is imperative to cope with disruptions using some preparedness and recov ery capabilities such as network redundancy (e.g., backup suppliers) and process flexibility (e.g., capacity agility). These capabilities frame an SC resilience portfolio. Both designing a resilient portfolio and recov ering in case of a real disruption require investments. This paper presents a new mathematical model for designing an efficient resilience portfolio in a multi-echelon SC. Through computational and compar ative analyses using a real-life case-study, we demonstrate that our model allows increasing resilience at minimal costs by determining an optimal combination of preparedness and recovery investments. Inter estingly, the optimal solutions (i.e., efficient resilient SC designs) increase SC efficiency even in business as-usual scenarios. This result contributes to the literature on transforming resilience from an expensive spend to a value-creation asset. We illustrate our approach using a real-life industrial example that al lows for the identification of important relations between disruption duration/magnitude and efficiency of preparedness and recovery strategies. Based on computational, comparative, and case-study analyses, we deduce and generalize managerial implications at the network, supplier, and manufacturer levels. We
take an extra step by extrapolating our major findings and generalized managerial implications toward the COVID-19 pandemic setting. The outcome of our research can be instructive for SC managers when deciding on investments in resilient redundancy allocation as a part of preparedness strategy and efficient recovery deployment
Part-feeding Models and Techniques in an Automotive Environment: A Literature Review and Future Research Agenda
No full textA Framework for Technology Selection and Impact Evaluation of Digitalisation in the Industrial Sector
No full textThe wide global competition that manufacturing companies are subjected to is forcing them to invest in the application of digital technologies. Moreover, government initiatives such as Plattform Industrie 4.0 or Made in China 2025 represent another external push for the implementation of the digital transformation in the industrial and manufacturing sector. However, evidence from literature and surveys show that there is still a lack of clarity regarding the economic benefit of digitalisation as well as a lack of guidelines that indicate which industrial process is worth digitalising and with which technology. To address this issue, this work develops a methodological framework that aims to provide guidance in the choice of new digital technologies. The framework is divided into four levels and follows a top-down recursive approach, moving from the strategic level to the digital technology level. Enriched with a mathematical formulation, the framework allows various different multi-criteria decision-making methods to be applied
- …
