Fitting functions of Jackson type for three-dimensional data

We study some procedures for the approximation of three-dimensional data on a grid with a hypothesis of periodicity. The first part proposes a generalization of a discrete periodic approximation defined by Dunham Jackson. The functions used have the advantage of owning an analytical explicit expression in terms of the samples (specific values) of the original function or data. In the second part, we describe a continuous approximation function for the same problem, defined through an integral. Some results of the rate of convergence and bounds of the approximation error are presented, with the single hypothesis of Hölder continuity or continuity of the original function

Methodology for the Maintenance Centered on the Reliability on Facilities of Low Accessibility

AbstractThis paper presents the importance of obtaining the application of a maintenance technique that satisfies in a precise way the different needs of the production process, independently of its technical complexity or difficulty of access to the industrial plant facilities. This is the case of the plants with a high automation level or wind farms located in remote places with low accessibility. Besides this, the studied situations have in common the low level of physical operation in its production process

Study of the Indentation Process under Specific Technological Parameters

AbstractThere is a large variety of Compressive Forming Processes with different typologies and characteristics. In this paper, the indentation process is studied from the point of view of manufacturing. The influence of technological parameters such as friction and shape factor on the process has been studied. The aluminum alloy AA 6082 has been employed in this study due to its good mechanical properties, light weight and its capacity of being recycled. The Finite Element Method (FEM) has been used for the analysis. The indentation process has been studied under axisymmetric conditions. The forces to carry out the indentation process and the contact pressures have been obtained. Finally, it is shown that the forces and the contact pressures do not have a high dependency on the friction between the surfaces of the punch and the workpiece. The shape factor has a greater influence on the process, especially the width of the workpiece

Study of the Indentation Process under Specific Technological Parameters

AbstractThere is a large variety of Compressive Forming Processes with different typologies and characteristics. In this paper, the indentation process is studied from the point of view of manufacturing. The influence of technological parameters such as friction and shape factor on the process has been studied. The aluminum alloy AA 6082 has been employed in this study due to its good mechanical properties, light weight and its capacity of being recycled. The Finite Element Method (FEM) has been used for the analysis. The indentation process has been studied under axisymmetric conditions. The forces to carry out the indentation process and the contact pressures have been obtained. Finally, it is shown that the forces and the contact pressures do not have a high dependency on the friction between the surfaces of the punch and the workpiece. The shape factor has a greater influence on the process, especially the width of the workpiece

Fractal approximation of Jackson type for periodic phenomena

The reconstruction of an unknown function providing a set of Lagrange data can be approached by means of fractal interpolation. The power of that methodology allows us to generalize any other interpolant, both smooth and nonsmooth, but the important fact is that this technique provides one of the few methods of nondifferentiable interpolation. In this way, it constitutes a functional model for chaotic processes. This paper studies a generalization of an approximation formula proposed by Dunham Jackson, where a wider range of values of an exponent of the basic trigonometric functions is considered. The trigonometric polynomials are then transformed in close fractal functions that, in general, are not smooth. For suitable election of this parameter, one obtains better conditions of convergence than in the classical case: the hypothesis of continuity alone is enough to ensure the convergence when the sampling frequency is increased. Finally, bounds of discrete fractal Jackson operators and their classical counterparts are proposed

Analysis of Documental Heritage of CETA in Standardization of the Spanish Manufacturing Automotive Industry

AbstractStandardization has taken an active role in the development of several main industrial sectors and the automotive sector has been one of them. Current work shows the collection, analysis, revision and management process developed on CETA (Center of Automotive Technical Study) standards related to the manufacturing automotive sector, an unknown element of Spanish standardization heritage. Also, a comparative evaluation between CETA standards and current UNE standards has been performed. The results show that CETA standards have had a positive influence in the evolution of the automotive sector as well as an important contribution to the contents of the UNE standards

Comparative Analysis of Extrusion Processes by Finite Element Analysis

AbstractExtrusion processes are quite extended in the manufacturing of long products for a wide range of industrial applications. There are different approaches of extrusion processes, depending on either the final shape of the product to obtain or the maximum loading capacity of the equipment to be used. This work presents a comparative study of extrusion processes (solid and cup extrusion), considering both direct and indirect forming conditions and showing the most interesting differences between them. The comparison is realized by Finite Element simulation of the processes, using the code DEFORM F2. The material is a low carbon steel (AISI-1010) and the same extrusion ratio and ram displacement are considered in all cases. By comparing the required forces it can be concluded that required loads are higher in cup extrusion processes than in solid extrusion ones. Regarding the friction load, the maximum contribution due to the die-billet contact in cup extrusion is much higher than in the case of solid extrusion. On the contrary, the maximum friction load contribution due to the container wall is much higher in the case of solid extrusion than in cup extrusion

Highly sensitive SERS quantification of organophosphorous chemical warfare agents: A major step towards the real time sensing in the gas phase

A surface-enhanced Raman scattering (SERS)-based sensor was developed for the label-free real-time gas phase detection of dimethyl methylphosphonate (DMMP); a surrogate molecule of the G-series nerve agents which are of particular concern due to its extreme toxicity, persistence and previous deployment. The SERS platform was designed using simple elements (Au nano-particles) coated with a citrate layer, and a self-assembly procedure that yields near- optimum distances among the nanoparticles. The citrate coating acts as an effective trap of the target molecules on the immediate vicinity of the Au nanoparticle surface under ambient conditions by reversible hydrogen bonding type interactions. For the first time, we have been able to detect sub-ppm concentrations of DMMP in gas phase (130 parts-per-billion), as might be found on potential emergency scenarios. The high sensitivity, simple preparation and reusability of the SERS platforms developed in this work open up the way for immediate detection of chemical warfare agents in realistic scenarios

Oral lichen planus. An evolutive clinical and histological study of 45 patients followed up on for five years

A study is made of 45 patients clinically and histologically diagnosed of oral lichen planus, and followed up on for 5 years. The course of the disease was monitored after three months and one, two and five years. The patients were classified in terms of lesion evolution (healed, improved, stationary or worse). Two evolutive groups were established for statistical purposes: (a) favorable (healed or improved lesions) and unfavorable cases (stationary or worsened oral lesions); and (b) healed and non-healed cases. Statistical correlations were established between these evolutive groups and different clinical and histological parameters, in an attempt to identify parameters of predictive value in the course of the disease. No statistically significant results were obtained, with the exception of inflammatory infiltrate. Thus, the depth of this infiltrate was found to be greater in patients with an unfavorable evolution (p = 0.02) than in those with a favorable course. Likewise, the inflammatory infiltrate was greater in non-healed than in healed cases.Dans ce travail, nous présentons une série de 45 patients, suivis pendant 5 ans, diagnostiqués cliniquement et histologiquement de lichen plan oral. Des contrôles évolutifs réalisés au bout de 3 mois, un an, deux ans et au bout de cinq ans ont classé les patients en fonction de l’évolution qu’ils présentaient en cas qui avaient guéri de leurs lésions, qui s’étaient améliorés, qui continuaient pareil et finalement ceux qui avaient empiré. Vis-à-vis des statistiques 2 groupes évolutifs se sont faits: 1) cas favorables (les guéris et ceux qui s’étaient améliorés), cas défavorables (ceux qui ne présentaient aucun changement ou ceux qui avaient empiré de leurs lésions intraorales) et 2) cas guéris, cas non-guéris. Diverses corrélations statistiques se sont établies entre ces groupes évolutifs et une série de variables cliniques et histologiques pour trouver un paramètre ayant une valeur de prédiction dans l’évolution de la maladie. Nous n’avons trouvé aucune donnée significativement statistique si l’on excepte une infiltration inflammatoire. Ainsi, nous démontrons une plus grande profondité moyenne de celle-ci dans les cas qui présentent une évolution défavorable (p = 0.02) que dans les cas favorables. De la même façon, nous trouvons une plus grande infiltration dans les cas non-guéris que dans les guéris

Improvement of the Ductility of Environmentally Friendly Poly(lactide) Composites with Posidonia oceanica Wastes Plasticized with an Ester of Cinnamic Acid

[EN] New composite materials were developed with poly(lactide) (PLA) and Posidonia oceanica fibers through reactive extrusion in the presence of dicumyl peroxide (DCP) and subsequent injection molding. The effect of different amounts of methyl trans¿cinnamate (MTC) on the mechanical, thermal, thermomechanical, and wettability properties was studied. The results showed that the presence of Posidonia oceanica fibers generated disruptions in the PLA matrix, causing a decrease in the tensile mechanical properties and causing an impact on the strength due to the stress concentration phenomenon. Reactive extrusion with DCP improved the PO/PLA interaction, diminishing the gap between the fibers and the surrounding matrix, as corroborated by field emission scanning electron microscopy (FESEM). It was observed that 20 phr (parts by weight of the MTC, per one hundred parts by weight of the PO/PLA composite) led to a noticeable plasticizing effect, significantly increasing the elongation at break from 7.1% of neat PLA to 31.1%, which means an improvement of 338%. A considerable decrease in the glass transition temperature, from 61.1 °C of neat PLA to 41.6 °C, was also observed. Thermogravimetric analysis (TGA) showed a loss of thermal stability of the plasticized composites, mainly due to the volatility of the cinnamate ester, leading to a decrease in the onset degradation temperature above 10 phr MTC.This research is a part of the grant PID2020-116496RB-C22 and TED2021-131762A-I00 funded by MCIN/AEI/10.13039/501100011033 and the European Union ¿NextGenerationEU¿/PRTR¿. The authors also thank Generalitat Valenciana-GVA, grant number AICO/2021/025 and CIGE/2021/094, for supporting this work.Barandiaran, A.; Lascano-Aimacaña, DS.; Montanes, N.; Balart, R.; Sellés, M.; Moreno-García, V. (2023). Improvement of the Ductility of Environmentally Friendly Poly(lactide) Composites with Posidonia oceanica Wastes Plasticized with an Ester of Cinnamic Acid. Polymers. 15(23). https://doi.org/10.3390/polym15234534152