On the Analysis of the Contact Conditions in Temporomandibular Joint Prostheses

Temporomandibular joint replacement (TMJR) is a complex surgical procedure in which the artificial joints available must assure the anatomical reconstruction and guarantee a good range of the natural temporomandibular joint (TMJ) movements. With this aim, different types of TMJ prostheses, including the stock prosthetic system and custom-made prostheses, are being currently implanted. Although temporomandibular joint replacements (TMJRs) are expected to accomplish their function during a number of years, they might actually fail and need to be replaced. This paper analyzes different design factors affecting the contact stress distributions within the TMJ prosthesis interface, which are consequently involved in their deterioration and final failure of the prosthetic device. With this purpose, a numerical model based on finite elements has been carried out in order to evaluate the stress states attained in different prosthesis configurations corresponding to general types of TMJ prostheses. On the other hand, the actual degradation of resected implants has been evaluated via optical microscopy. The linkage between the numerical simulations performed and experimental evidence allowed the authors to establish the different wear and damage mechanisms involved in the failure of stock TMJ prostheses. Indeed, the results obtained show that the contact stresses at the interface between the mandible and the glenoid fossa components play a key role in the failure process of the TMJR devices

On the study of the single-stage hole-flanging process by SPIF

Recent studies show the capability of single-point incremental forming to perform successfully hole-flanging operations using multi-stage strategies. The aim of this work is to investigate the ability of the SPIF process to perform hole-flanges in a single stage, contributing to a better understanding of the formability of the sheet in this demanding situation. To this end, a series of experimental tests in AA7075-O metal sheets are performed in order to evaluate the limiting forming ratio. The physical mechanisms controlling sheet failure during the process are analyzed and discussed. In the test conditions studied this failure is postponed necking followed by ductile fracture in the wall of the flange.Ministerio de Economía y Competitividad DPI2012-3291

Preliminary investigation on homogenization of the thickness distribution in hole-flanging by SPIF

A drawback of the hole-flanging process by single-stage SPIF is the non-uniform thickness obtained along the flange. Multi-stage strategies have been used to improve it, however they increase notably the manufacturing time. This work presents a preliminary study of the tool paths for a hole-flanging process by SPIF in two stages. An intermediate geometry of the piece is proposed from the analysis of the thickness distribution observed in previous single-stage process. A simple optimization procedure is used to automate the intermediate part design, the NC code generation for the tool path and the validation of the optimal forming strategy by means of FEA

Experimental study of impact on SMC composites used in the automotive industry

The signal from a piezoelectric sensor received by a data acquisition system was used to record the temporal evolution of the force transmitted by an impactor on specimens of an SMC composite. A high-speed motion analyser recorded the sequence of images of the impact and fracture of the material. The subsequent processing of this sequence using an image analysis programme provided data for the calculation of various energy magnitudes. The behaviour under impact of this material was then characterised on the basis of these energy magnitudes and the temporal evolution of the force.Spain’s Ministerio de Educación y Ciencia project DPI2002-0284

Propuesta de Diseño de Software para la Facturación Electrónica con el ERP Odoo

Trabajo Final de Graduación (Licenciatura en Administración de Tecnología de Información) Instituto Tecnológico de Costa Rica, Área Académica de Administración de Tecnologías de Información, 2017.El presente proyecto se basa en una propuesta de diseño de software para la facturación electrónica utilizando el sistema Odoo, según las obligaciones y requisitos de la resolución DGT-R-48-2016 conocida como comprobantes electrónicos en la versión 4.2, la cual rige a partir de octubre 2017. Inicialmente, se determinó los antecedentes en Costa Rica, tomando como insumo publicaciones y resoluciones, así como una investigación de campo por medio de entrevistas realizadas a gerentes generales y financieros del país. Posteriormente se continuó con el proceso siguiendo las actividades recomendadas de la ISO/IEC 12207:2008 para el ciclo de vida del desarrollo del software. Se realizó una identificación de los requerimientos, se elaboró un conjunto de casos de uso, se diseñó un diagrama de clases y se desarrolló una propuesta de pruebas. Luego se realizó un prototipo usando la herramienta llamada Odoo Studio, en donde se construyó una propuesta de solución del trabajo para el sistema de planificación de recursos empresariales. Finalmente, se elaboró un plan de implementación del proyecto, el cual puede ser adaptado a otros negocios que tengan la necesidad de cumplir con la legislación correspondiente de comprobantes electrónicos.The main objective of this investigation is to define a software design proposal for electronic invoicing using the software known as Odoo, according to the obligations and requirements of the resolution DGT-R-48-2016, known as the electronic billing in its 4.2 version, that reigns from October 2017. First, the records in Costa Rica were determined, taking as entries articles, laws and resolutions, as well as a field investigation through interviews with general and financial managers of the country. Subsequently, the process was continued following the recommended activities of ISO/IEC 12207:2008 for the software development life cycle. Where an identification of the requirements was made, a set of use cases was elaborated, a class diagram was designed, and a test proposal was developed. Then a prototype was made using the tool called Odoo Studio, where a work solution proposal for the enterprise resource planning system was built. Finally, a design implementation plan was developed, that can be adapted to other businesses that have the need to satisfy the electronic invoicing legislation

A Market-Based Analysis on the Main Characteristics of Gearboxes Used in Onshore Wind Turbines

Even though wind energy is one of the most mature renewable technologies, it is in continuous development not only because of the trend towards larger wind turbines but also because of the development of new technological solutions. The gearbox is one of the components of the drive train in which the industry is concentrating more effort on research and development. Larger rotor blades lead to more demanding requirements for this component as a consequence of a higher mechanical torque and multiplication ratio (due to lower rotational speed of blades while the rotational speed on the generator side remains at similar values). In addition, operating conditions become increasingly demanding in terms of reliability, performance, and compactness. This paper analyses the different gearbox arrangements that are implemented by manufacturers of onshore wind turbines, as well as their market penetration (including different aspects that affect the design of the gearbox, such as drive train configuration and turbine size). The analysis carried out shows a clear convergence towards gearboxes with three stages. However, there is a noticeable diversity in the types of gears used, depending to a large extent on the preferences of each manufacturer but also on the nominal power of the wind turbine and drive train configuration

Recent Approaches for the Determination of Forming Limits by Necking and Fracture in Sheet Metal Forming

Forming limit diagrams (FLD’s) are used to evaluate the workability of metal sheets. FLD’s provide the failure locus at which plastic instability occurs and localized necking develops (commonly designated as the forming limit curve - FLC), and the failure loci at the onset of fracture by tension (FFL) or by in-plane shear (SFFL). The interest of metal formers in controlling localized necking is understandable because the consequence of plastic instability is an undesirable surface blemish in components. However, because under certain loading conditions fracture can precede necking in sheet metal forming processes, there is a growing interest in characterizing the forming limits by necking and fracture in the FLD’s. This paper gathers together a number of recently developed methodologies for detecting the onset of local necking and fracture by in-plane tension or in-plane shear, and discusses their applicability to determine experimentally the FLC’s, FFL’s and SFFL’s.Ministerio de Economía y Competitividad DPI2012-3291

Numerical explicit analysis of hole flanging by single-stage incremental forming

The use of Single-Point Incremental Forming (SPIF) technology in hole flanging operations using multi-stages strategies have been widely studied in the last few years. However, these strategies are very time-consuming, limiting its industrial application.In a very recent work of the authors, the capability of SPIF process to successfully perform hole-flanges using a single-stage strategy has been experimentally investigated. The aim of the present work is to develop a numerical model of this process to beable to predict the sheet failure as a function of the size of the pre-cut hole. The numerical results are compared and discussed in the light of experimental tests over AA7075-O metal sheets with 1.6mm thickness.Ministerio de Economía y Competitividad DPI2015-64047-

El riesgo laboral que existe en el departamento de Servicios Generales del Hospital Escuela Cesar Amador Molina, Matagalpa, durante el segundo semestre del año 2013

En esta investigación se analizó el Riesgo Laboral en el departamento de Servicios Generales del Hospital Escuela Cesar Amador Molina (HECAM) de Matagalpa, de conformidad con la ley 618 (ley general de higiene y seguridad del trabajo) en el segundo semestre del año 2013. Las variables evaluadas fueron el riesgo, higiene y seguridad laboral, así como las condiciones de trabajo proporcionadas a los trabajadores del departamento de servicios generales; fue mediante la utilización de instrumentos como la encuesta, entrevista y observación que se logró contrastar la información de esta investigación con lo que realmente se aplica hoy en día en el departamento de servicios generales del HECAM. Mediante esta labor investigativa se realizó una valoración y análisis de las condiciones de trabajo en las que se desempeñan los trabajadores, se obtuvo como resultado que se ven afectados por condiciones de trabajo como la inadecuada e ineficiente iluminación, el cambio en los niveles de temperatura, pisos resbaladizos, poca y discontinua capacitación en cuanto a riesgo, también el no uso de equipos de protección, siendo estos los de mayor relevancia. Afectaciones que en su gran mayoría se deben a que el HECAM no cuenta con un plan de higiene y seguridad del trabajo que regule estas condiciones, de igual manera que regule el cumplimiento de los trabajadores a las normas de higiene y seguridad del trabajo establecidas en la ley 618 (ley general de higiene y seguridad del trabajo) así como a las normas hospitalaria

A comprehensive analysis of gene expression profiles in distal parts of the mouse renal tubule

The distal parts of the renal tubule play a critical role in maintaining homeostasis of extracellular fluids. In this review, we present an in-depth analysis of microarray-based gene expression profiles available for microdissected mouse distal nephron segments, i.e., the distal convoluted tubule (DCT) and the connecting tubule (CNT), and for the cortical portion of the collecting duct (CCD; Zuber et al., Proc Natl Acad Sci USA 106:16523-16528, 2009). Classification of expressed transcripts in 14 major functional gene categories demonstrated that all principal proteins involved in maintaining the salt and water balance are represented by highly abundant transcripts. However, a significant number of transcripts belonging, for instance, to categories of G-protein-coupled receptors or serine/threonine kinases exhibit high expression levels but remain unassigned to a specific renal function. We also established a list of genes differentially expressed between the DCT/CNT and the CCD. This list is enriched by genes related to segment-specific transport functions and by transcription factors directing the development of the distal nephron or collecting ducts. Collectively, this in silico analysis provides comprehensive information about relative abundance and tissue specificity of the DCT/CNT and the CCD expressed transcripts and identifies new candidate genes for renal homeostasi