219 research outputs found
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Digital Machines, Space, And Time: Towards A Behavioral Perspective Of Flexible Manufacturing
Recently, the diffusion of digital machines has further enhanced firms’ manufacturing flexibility, but also opened questions on potential challenges and implications in the production process. To respond to these timely issues, we adopt a behavioral perspective and comparatively explore how four different types of digital machines—characterized by increasing degrees of manufacturing flexibility—affect the perception and use of space and time for routines within the production plant. We qualitatively observe and compare 45 digital manufacturing machines, sampled across 14 firms in the British and Italian motorsport industry. A model emerges where four key mechanisms reshape the ‘space-machine’ and ‘time-machine’ routines. Such mechanisms mediate the relationship between manufacturing flexibility and firm performance. Further, we show how increasing digitalization in the manufacturing process enhances the establishment of new routines as flexible machines get introduced in the production. Finally, we discuss the theoretical and practical implications related to fostering a behavioral perspective in innovation and operations management studies
Radial force control of Multi-Sector Permanent Magnet machines considering radial rotor displacement
A mathematical model enabling to predict the electromagnetic x-y forces and torque for a given input current in a Multi-Sector Permanent Magnet Synchronous (MSPMS) machine is presented. The rotor static eccentricity is also accounted and the analytical calculations are validated by means Finite Element Analysis (FEA). Furthermore, a novel force and torque control is proposed based on input current minimization and is applied to suppress the Unbalanced Magnetic Pull (UMP) caused by the rotor eccentricity. The effective operation of the force suppression technique is verified by means of FEA
Impact assessment of design guidelines in the conceptual development of aircraft product architectures
The optimization of the assembly phase, in complex products, is a challenging phase and it need to be handled in the early phase of product development (i.e., conceptual design). Several methods have been developed to assess the assemblability of product at the conceptual design phase, however, the most critical aspect concerns the possibility to derive design guidelines starting from the results of assemblability analysis. In this context, the present work aims at defining a methodology able to retrieve design for assembly and installation guidelines starting from the analysis of a given product architecture at the conceptual design phase (loop-back of the design for assembly method). The developed method makes use of matrices and vectors to provide a list of design actions that affect the product assemblability including a ranking of their impacts on the final design. The methodology was used to retrieve and select design guidelines in the context of aircraft manufacturing. The case study (cabin equipping of commercial aircraft) provides interesting results in the identification and implementation of design guidelines to improve the aircraft architecture at the conceptual level
Conceptual design for assembly in aerospace industry: Sensitivity analysis of mathematical framework and design parameters
One of the most challenging activity in the engineering design process is the definition of a framework (model and parameters) for the characterization of specific processes such as installation and assembly. Aircraft system architectures are complex structures used to understand relation among elements (modules) inside an aircraft and its evaluation is one of the first activity since the conceptual design. The assessment of aircraft architectures, from the assembly perspective, requires parameter identification as well as the definition of the overall analysis framework (i.e., mathematical models, equations). The paper aims at the analysis of a mathematical framework (structure, equations and parameters) developed to assess the fit for assembly performances of aircraft system architectures by the mean of sensitivity analysis (One-Factor-At-Time method). The sensitivity analysis was performed on a complex engineering framework, i.e. the Conceptual Design for Assembly (CDfA) methodology, which is characterized by level, domains and attributes (parameters). A commercial aircraft cabin system was used as a case study to understand the use of different mathematical operators as well as the way to cluster attributes
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Emerging research and future pathways in digital supply chain governance
Over the past 20 years, the management of supply chain (SC) relationships and, particularly,
related governance theories, instruments and mechanisms have received increasing attention
in operations management research (cf. Pilbeam et al., 2012; Bonatto et al., 2020). The
emergence of fragmented and globally dispersed supply chains has laid the foundation for
various forms of interorganizational governance (Gereffi et al., 2005) that utilize contractual
and relational mechanisms to balance interdependencies and individual interests in a way
that allows effective collaboration and control for improved performance (Pilbeam
et al., 2012)
In vivo inhibition of the mitochondrial H+-ATP synthase in neurons promotes metabolic preconditioning
A key transducer in energy conservation and signaling cell death is the mitochondrial H+-ATP synthase. The expression of the ATPase inhibitory factor 1 (IF1) is a strategy used by cancer cells to inhibit the activity of the H+-ATP synthase to generate a ROS signal that switches on cellular programs of survival. We have generated a mouse model expressing a mutant of human IF1 in brain neurons to assess the role of the H+-ATP synthase in cell death in vivo. The expression of hIF1 inhibits the activity of oxidative phosphorylation and mediates the shift of neurons to an enhanced aerobic glycolysis. Metabolic reprogramming induces brain preconditioning affording protection against quinolinic acid-induced excitotoxicity. Mechanistically, preconditioning involves the activation of the Akt/p70S6K and PARP repair pathways and Bcl-xL protection from cell death. Overall, our findings provide the first in vivo evidence highlighting the H +-ATP synthase as a target to prevent neuronal cell deathThis work was supported by grants from the MEC (BFU2010-18903), CIBERER
and by Comunidad de Madrid (S2011/BMD-2402) to JMC; MINECO (PLE2009-0101 and SAF2010-17167), TerCel (RD12/0019/0013), and Neurostem-CM (S2010-BMD-2336) to AMS and ISCIII Grant PI 10/02628 to CN, Spai
Absence of R-Ras1 and R-Ras2 causes mitochondrial alterations that trigger axonal degeneration in a hypomyelinating disease model
Fast synaptic transmission in vertebrates is critically dependent on myelin for insulation and metabolic support. Myelin is produced by oligodendrocytes (OLs) that maintain multilayered membrane compartments that wrap around axonal fibers. Alterations in myelination can therefore lead to severe pathologies such as multiple sclerosis. Given that hypomyelination disorders have complex etiologies, reproducing clinical symptoms of myelin diseases from a neurological perspective in animal models has been difficult. We recently reported that R-Ras1 and/or R-Ras2 mice, which lack GTPases essential for OL survival and differentiation processes, present different degrees of hypomyelination in the central nervous system with a compounded hypomyelination in double knockout (DKO) mice. Here, we discovered that the loss of R-Ras1 and/or R-Ras2 function is associated with aberrant myelinated axons with increased numbers of mitochondria, and a disrupted mitochondrial respiration that leads to increased reactive oxygen species levels. Consequently, aberrant myelinated axons are thinner with cytoskeletal phosphorylation patterns typical of axonal degeneration processes, characteristic of myelin diseases. Although we observed different levels of hypomyelination in a single mutant mouse, the combined loss of function in DKO mice lead to a compromised axonal integrity, triggering the loss of visual function. Our findings demonstrate that the loss of R-Ras function reproduces several characteristics of hypomyelinating diseases, and we therefore propose that R-Ras1 and R-Ras2 neurological models are valuable approaches for the study of these myelin pathologies.Spanish Ministry of Economy and Competitiveness (RTI2018-096303B-C33) to B. C., (RTI2018-096303B-C31) to F. W., and RTI2018-095166B-I00 to C. G. R. and P. L. and Instituto de Salud Carlos III and co-funded by the European
Regional Development Fund (ERDF) within the “Plan Estatal de Investigación Científica y Técnica y de Innovación 2017–2020” (RD16/0008/0020; FIS/PI 18-00754
Dysfunctional oxidative phosphorylation shunts branched-chain amino acid catabolism onto lipogenesis in skeletal muscle
It is controversial whether mitochondrial dysfunction in skeletal
muscle is the cause or consequence of metabolic disorders. Herein,
we demonstrate that in vivo inhibition of mitochondrial ATP
synthase in muscle alters whole-body lipid homeostasis. Mice with
restrained mitochondrial ATP synthase activity presented intrafiber
lipid droplets, dysregulation of acyl-glycerides, and higher visceral
adipose tissue deposits, poising these animals to insulin resistance.
This mitochondrial energy crisis increases lactate production,
prevents fatty acid b-oxidation, and forces the catabolism of
branched-chain amino acids (BCAA) to provide acetyl-CoA for de
novo lipid synthesis. In turn, muscle accumulation of acetyl-CoA
leads to acetylation-dependent inhibition of mitochondrial respiratory complex II enhancing oxidative phosphorylation dysfunction
which results in augmented ROS production. By screening 702
FDA-approved drugs, we identified edaravone as a potent mitochondrial antioxidant and enhancer. Edaravone administration
restored ROS and lipid homeostasis in skeletal muscle and reinstated insulin sensitivity. Our results suggest that muscular mitochondrial perturbations are causative of metabolic disorders and
that edaravone is a potential treatment for these diseasesThis work was ts from Ministerio de Economía, Industria y Competitividad, MINECO, Spain (SAF2016-76028-R and SAF2016-75916-R) and Centro de Investigación Biomédica en Red (CIBER) de Enfermedades Raras, Spain (CB06/07/0017
Direct flux and current vector control for induction motor drives using model predictive control theory
The study presents the direct flux and current vector control of an induction motor (IM) drive, which is a relatively newer and promising control strategy, through the use of model predictive control (MPC) techniques. The results highlight that the fast flux control nature of direct flux control strategy is further enhanced by MPC. Predictive control is applied in two of its variants, namely the finite control set and modulated MPC, and the advantages and limitations of the two are underlined. This work also highlights, through experimental results, the importance of prioritising the flux part of the cost function which is particularly significant in the case of an IM drive. The performance of the MPC-based approach is compared with the proportional-integral controller, which also prioritises the flux control loop, under various operating regions of the drive such as in the flux-weakening regime. Simulations show the performance expected with different control strategies which is then verified through experiments
Ensaio regional de linhagens de arroz irrigado do Programa de Melhoramento Genético da Embrapa no RS - safra 2008/09.
O Ensaio Regional de linhagens de arroz irrigado visa selecionar genótipos que apresentem alta adaptabilidade e estabilidade aos diversos ambientes em que são cultivadas e que expressem elevado rendimento de grãos, associado à características agronômicas, industriais e culinárias adequadas. Este experimento teve como objetivo avaliar linhagens do programa da Embrapa no Ensaio Regional de Rendimento
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