Production and maintenance planning of deteriorating manufacturing systems taking into account the quality of products

The research work presented in this thesis addresses the integration of quality aspects in the development of stochastic dynamic programming models. The goal is to determine the joint optimal production planning, and several maintenance strategies for an unreliable and deteriorating manufacturing system. In particular, we conjecture that deterioration has a severe influence on various aspects of the machine, thus this leads to divide our research work in three (3) phases. In the first one, we analyze the simultaneous production planning and quality control problem for an unreliable manufacturing system. The machine is subject to deterioration whose effect is observed mainly on the quality throughput. The quality related decisions involves a major overhaul strategy that counters the effect of deterioration. A simulation optimization approach is applied to determine the optimal control policy, providing a better understanding about the influence of quality deterioration on such system. The second phase of the research analyzes the fact where the deterioration of the production system is originated by a combination of several factors. We consider that the system deteriorates by the combined effect of the wear of the machine and imperfect repairs. Multiple operational states are implemented to model variations on the rate of defectives. Furthermore at failure, either a repair or a major overhaul can be conducted; however the machine deteriorates even more following repairs. We use a Semi-arkov decision model, since the rate of defectives is depended of the machine’s history denoted by the number of repairs and the set of multiple operational states. Then the simultaneous production plan, and repair/overhaul switching strategy are determined through numerical methods. The third phase complements the previous models by considering that the deterioration of the production systems has a twofold effect that decreases the quality of the parts produced and also increases the failure intensity. We employ the age of the machine to denote the progressive deterioration. At failure it is conducted a minimal repair that leaves the machine at the same level of deterioration before failure. To counter completely the effect of deterioration it can be performed a major overhaul. Moreover, this phase introduces preventive maintenance strategies to reduce partially the level of deterioration. This set of characteristics yields to formulate a Semi-Markov model that thorough numerical methods, we determine the joint optimal production plan and the overhaul and preventive maintenance strategies. This model clarifies the role of quality aspects on the optimal control policy. In this way our research deepens the effects of quality aspects and deterioration on the optimal control policy, and provides interesting contributions to the domain of stochastic control of manufacturing systems. Additionally, a number of numerical examples are conducted as illustration, and extensive sensitivity analyses are presented with the purpose to confirm the structure and validity of the obtained control policies. The models developed in this thesis provide further insights into the relations between the production policy and quality aspects in the context of deterioration, and also contribute to a better understanding about the behavior of stochastic manufacturing systems

Aerodynamic evaluation with cfd of tip devices in blade for wind turbine

 La región de la punta en las aspa de un rotor eólico se presenta el fenómeno de arrastre inducido, el cual disminuye la eficiencia aerodinámica de la turbina  e incrementa los esfuerzos sobre la estructura. En este trabajo, se analizan computacionalmente (CFD) diferentes dispositivos de punta de aspa, con base en aplicaciones similares como Winglets, Split-Tips, Tip-Tanks, como alternativa de mejora de la aerodinámica. El Reynolds utilizado fue de Re =140000 y modelo RANS de turbulencia K-e, el ángulo de ataque (alfa) fue variado desde -25° hasta 25°. El análisis de los resultados mostró, respecto al aspa con punta base (sin modificación), incremento porcentual del coeficiente de sustentación (CL) así: Split-Tips = 3% Winglet = 4.6%, la punta tipo Tip-Tank no presentó mejora apreciable, La intensidad del vórtice de punta de aspa también mostró relación directa (incremento/disminución) cuando fue comparado con la variación del CD. Palabras clave: CFD, Punta de aspa, Vórtices, Winglets, HAWT

Scale Mixture of Rayleigh Distribution

In this paper, the scale mixture of Rayleigh (SMR) distribution is introduced. It is proven that this new model, initially defined as the quotient of two independent random variables, can be expressed as a scale mixture of a Rayleigh and a particular Generalized Gamma distribution. Closed expressions are obtained for its pdf, cdf, moments, asymmetry and kurtosis coefficients. Its lifetime analysis, properties and Rényi entropy are studied. Inference based on moments and maximum likelihood (ML) is proposed. An Expectation-Maximization (EM) algorithm is implemented to estimate the parameters via ML. This algorithm is also used in a simulation study, which illustrates the good performance of our proposal. Two real datasets are considered in which it is shown that the SMR model provides a good fit and it is more flexible, especially as for kurtosis, than other competitor models, such as the slashed Rayleigh distribution

Influencia de la Educación Física en jugadores de Fútbol Asociación Sub-13 y Sub-15

The present study aims to evaluate the lifestyles of association football players in the under-13 and under-15 categories. The sample consisted of two association football teams’ under-13 (23 players) and under-15 (20 players) from the municipality of Alvarado, Veracruz, Mexico. The results obtained showed that; In food consumption habits, it was identified that 76% of athletes have high consumption of fruits, vegetables and water, while 24% do so poorly, therefore, by category it can be observed that the U-15 obtained higher percentage of healthy food consumption with 82% in contrast to the U-13 with 79%, on the other hand alcohol consumption is in a range of 3% -10% as well as tobacco 4% -10% For this reason, it is concluded that the practice of association football in the under-13 and under-15 categories is a means that allows acquiring healthy lifestyles in the intake of healthy foods, it is also a means to keep adolescents away of drug use.El presente estudio lleva por objetivo evaluar los estilos de vida que llevan los jugadores de fútbol asociación de las categorías sub-13 y sub-15. La muestra fue constituida por dos equipos de fútbol asociación sub-13 (23 jugadores) y sub-15 (20 jugadores) del municipio de Alvarado, Veracruz, México. Los resultados obtenidos arrojaron que; en los hábitos de consumo alimenticio se identificó que el 76% de los deportistas tienen alto consumo de frutas, verduras y agua, mientras que un 24% lo realiza de forma deficiente, por tanto, por categoría se puede observar que la Sub-15 obtuvo mayor porcentaje de consumo de alimentos saludable con el 82% a diferencia de la Sub-13 con un 79%, por otra parte el consumo de alcohol está en un rango del 3%-10% así como el del tabaco 4%-10%.Por tal motivo, se concluye que la práctica del futbol asociación en las categorías sub-13 y sub-15 es un medio que permite adquirir estilos de vida saludable en la ingesta de alimentos saludables, así mismo es un medio para alejar a los adolescentes del consumo de drogas. &nbsp

Application of the SMED methodology through folding references for a bus manufacturing company

Bodywork assembly in bus manufacturing is a task that involves several operations. In Mex- ico, many bus manufacturing companies have non-flexible production lines, which makes model change very problematic. In response to this situation, the SMED methodology was applied to make more flexible production lines in terms of setup reduction for model chang- ing. In this paper, the urban bus assembly line was studied, which is composed of sub-assem- bly stations that subsequently feed the station that assembles the unit, and that joints all the frames of the required model, the aim of the paper is to propose an approach to reduce the production time through the use of folding references. With the application of the SMED, it was observed that the production line improved in the transition from one body structure model to another, obtaining results of 56.2% in the time reduction

Actualización de la gestión catastral y redes hidráulicas en la zona urbana del Municipio de Ciudad Barrios, Departamento de San Miguel

RESUMEN: Se actualizo el registro catastral tributario de la alcaldía de Ciudad Barrios, departamento de San Miguel para que la aplicabilidad de las tasas e impuestos municipales se realice de manera más justa y precisa. La investigación se realizó en cuatro etapas, la primera consistió en delimitar la zona de estudio ya que se llevó a cabo en el casco urbano del municipio conformado por los barrios: El Calvario, El Centro, Roma, Concepción y Colonias: Las Palmeras y Gerardo Barrios respectivamente; en la segunda etapa se realizó una búsqueda exhaustiva de la información actual que posee el departamento de catastro de la municipalidad, obteniendo fichas catastrales obsoletas y planos en físico con medidas erróneas, además, no poseían información acerca del recorrido del tren de aseo ni de planos de redes hidráulicas; la tercer etapa es el trabajo de campo, la cual consistió en medir frentes de cada parcela, ancho de calles e identificar el tipo de capa de rodadura, georreferenciar la red de postes de alumbrado público, recolectar información sobre la cobertura y recorrido del tren de aseo, identificar la ubicación de líneas de tubería, acometida domiciliar, pozos de visita, descarga y válvulas de control, hidrantes, tapones, tanques de suministro, de la red de alcantarillado sanitario y de agua potable respectivamente; en la cuarta etapa con toda la información recolectada se procedió a la actualización de fichas catastrales, elaboración de los planos: general del casco urbano, de la red de agua potable, de la red de alcantarillado sanitario, de la red de postes de alumbrado público y del recorrido del tren de aseo. Con la base de datos de los contribuyentes actualizada en Excel y en planos CAD se realizó la propuesta de implementación de un Sistema de Información Geográfico (SIG) para el manejo y resguardo de toda esta información. ABSTRACT: The tax cadastral registry of the city hall of Ciudad Barrios, department of San Miguel was updated so that the applicability of municipal taxes and fees is carried out more fairly and precisely. The research was carried out in four stages, the first consisted of delimiting the study area since it was carried out in the urban area of ​​the municipality made up of the neighborhoods: El Calvario, El Centro, Roma, Concepción and Colonias: Las Palmeras and Gerardo Neighborhoods respectively; In the second stage, an exhaustive search was carried out on the current information that the municipality's cadastre department has, obtaining obsolete cadastral records and physical plans with erroneous measurements, in addition, they did not have information about the route of the cleaning train or plans of hydraulic networks; The third stage is the field work, which consisted of measuring fronts of each plot, width of streets and identifying the type of tread layer, georeferencing the network of public lighting poles, collecting information on the coverage and route of the train of cleanliness, identify the location of pipe lines, household connection, manholes, discharge and control valves, hydrants, plugs, supply tanks, of the sanitary sewer network and of drinking water respectively; In the fourth stage, with all the information collected, the cadastral records were updated, the plans were prepared: general of the urban area, the drinking water network, the sanitary sewer network, the network of public lighting poles. and the route of the toilet train. With the taxpayers' database updated in Excel and CAD plans, a proposal was made for the implementation of a Geographic Information System (GIS) for the management and protection of all this information

Evaluación del nivel competitivo de un desinfectante de alimentos desarrollado a partir de cálices de flor de Jamaica

The aim of this study is to evaluate the competition of a food disinfectant developed from extracts of hibiscus flower calyxes. As this disinfectant can have a positive impact on preventive healthcare, it is important to identify the factors that influence its positioning in its sector. The competition of this product was assessed in a five-phase methodology: (1) the supply chain was identified; (2) hibiscus flower calyxes and the food disinfectant made with them were described; (3) the competition of the disinfectant was analyzed using Porter’s 5 forces model; (4) its potential market and customers were evaluated; and (5) its competitive position was determined. It was found that the disinfectant under study is made of natural substances, has a high antimicrobial capacity to disinfect food, is safe for human health, has a wider disinfection spectrum than the most popular disinfectants positioned in the market, and follows current trends in society (i.e., choosing to consume products of natural origin). In contrast, the best positioned competitors, which include colloidal silver as an active substance, have solid advantages in the sector: permanence in the market, recognition by consumers, control of marketing channels, points of sale, and support from international companies. These findings can inform guidelines to establish strategies to develop business plans for this innovative, competitive product of natural origin. This disinfectant is in line with current eco-friendly trends and makes contributions to several fields: disease prevention, healthcare, and the socio-economic development of the supply chain of the hibiscus flower in Mexico.Este estudio tuvo como objetivo evaluar el nivel competitivo de un desinfectante de alimentos desarrollado a partir de extractos de cálices de la flor de Jamaica, el cual puede tener un impacto favorable en prevención de la salud, identificando, además, los factores que influyen en su sector para su posicionamiento. Para la evaluación competitiva se planteó una metodología de cinco fases: 1) identificar la cadena de suministro; 2) describir los cálices de la flor de Jamaica y el desinfectante de alimentos; 3) analizar el sector competitivo mediante el modelo de las cinco fuerzas de Porter; 4) evaluar el mercado y el cliente potencial, y; 5) determinar la posición competitiva. Como resultado, se encontró que el desinfectante en estudio procede de sustancias naturales, tiene una alta capacidad antimicrobiana para desinfectar alimentos, es seguro para la salud, tiene un espectro más alto en la desinfección en comparación con los principales desinfectantes posicionados en el mercado y va de acuerdo con la tendencia de la sociedad, que está optando por el consumo de productos de procedencia natural. En contraste, los competidores, posicionados en su mayoría, tienen como sustancia activa la plata coloidal, cuentan con ventajas sólidas en el sector, como permanencia en el mercado, reconocimiento por los consumidores, dominio de los canales de comercialización, puntos de venta y respaldo de empresas transnacionales. Lo encontrado, da la pauta para establecer las bases de las estrategias para el desarrollo de un plan de negocios, porque se tiene un producto innovador y competitivo, de procedencia natural, que va con las tendencias actuales amigables con el medio ambiente, contribuye en la prevención de enfermedades, cuidados de la salud y aporta en el desarrollo socioeconómico de la cadena de suministro de la flor de Jamaica de México

Differences in vocal brain areas and astrocytes between the house wren and the rufous-tailed hummingbird

The house wren shows complex song, and the rufous-tailed hummingbird has a simple song. The location of vocal brain areas supports the song’s complexity; however, these still need to be studied. The astrocytic population in songbirds appears to be associated with change in vocal control nuclei; however, astrocytic distribution and morphology have not been described in these species. Consequently, we compared the distribution and volume of the vocal brain areas: HVC, RA, Area X, and LMAN, cell density, and the morphology of astrocytes in the house wren and the rufous-tailed hummingbird. Individuals of the two species were collected, and their brains were analyzed using serial Nissl- NeuN- and MAP2-stained tissue scanner imaging, followed by 3D reconstructions of the vocal areas; and GFAP and S100β astrocytes were analyzed in both species. We found that vocal areas were located close to the cerebral midline in the house wren and a more lateralized position in the rufous-tailed hummingbird. The LMAN occupied a larger volume in the rufous-tailed hummingbird, while the RA and HVC were larger in the house wren. While Area X showed higher cell density in the house wren than the rufous-tailed hummingbird, the LMAN showed a higher density in the rufous-tailed hummingbird. In the house wren, GFAP astrocytes in the same bregma where the vocal areas were located were observed at the laminar edge of the pallium (LEP) and in the vascular region, as well as in vocal motor relay regions in the pallidum and mesencephalon. In contrast, GFAP astrocytes were found in LEP, but not in the pallidum and mesencephalon in hummingbirds. Finally, when comparing GFAP astrocytes in the LEP region of both species, house wren astrocytes exhibited significantly more complex morphology than those of the rufous-tailed hummingbird. These findings suggest a difference in the location and cellular density of vocal circuits, as well as morphology of GFAP astrocytes between the house wren and the rufous-tailed hummingbird

Statistically coherent calibration of X-Ray Fluorescence Spectrometry for major elements in rocks in minerals.

We applied both the ordinary linear regression (OLR) and the new uncertainty weighted linear regression (UWLR) models for the calibration and comparison of a XRF machine through 59 geochemical reference materials (GRMs) and a procedure blank sample. )e mean concentration and uncertainty data for the GRMs used for the calibrations (Supplementary Materials) (available here) filewere achieved from an up-to-date compilation of chemical data and their processing from well-known discordancy and significance tests. )e drift-corrected XRF intensity and its uncertainty were determined from mostly duplicate pressed powder pellets. )e comparison of the OLR (linear correlation coefficient r∼0.9523–0.9964 and 0.9771–0.9999, respectively, for before and after matrix correction) and UWLR models (r∼0.9772–0.9976 and 0.9970–0.9999, respectively) clearly showed that the latter with generally higher values of r is preferable for routine calibrations of analytical procedures. Both calibrations were successfully applied to rock matrices, and the results were generally consistent with those obtained in other laboratories although the UWLR model showed mostly narrower confidence limits of the mean (slope and intercept) or lower uncertainties than the OLR. Similar sensitivity (∼2.69–46.17 kc·s1·%1 for the OLR and ∼2.78–59.69 kc·s1·%1 for the UWLR) also indicated that the UWLR could advantageously replace the OLR model. Another novel aspect is that the total uncertainty can be reported for individual chemical data. If the analytical instruments were routinely calibrated from the UWLR model, this action would make the science of geochemistry more quantitative than at present

Primer consenso en leucemia linfocítica crónica de la agrupación mexicana para el estudio de la hematología: epidemiología, diagnóstico y tratamiento

La leucemia linfocítica crónica (LLC) es la leucemia crónica menos frecuente en México. En consideración a los avances recientes, a una mejor clasificación pronóstica y a la introducción de nuevas modalidades terapéuticas, la Agrupación Mexicana para el Estudio de la Hematología organizó el primer consenso mexicano en leucemia linfocítica crónica. Este consenso se llevó a cabo en Cancún, Quintana Roo, México, en Septiembre del 2007. Los objetivos de esta reunión fueron actualizar y compartir los conocimientos de la enfermedad entre los especialistas mexicanos, con el fin de mejorar el diagnóstico y el pronóstico de la LLC en México. En el artículo se discute los aspectos clínicos, diagnósticos y terapéuticos de la LLC