MBE growth and characterization of InGaN-based films and nanocolumns on Silicon substrates and GaN templates

InN layers: MBE growth issues Growth of InN-based thin films: InN/InGaN QWS on GaN Growth of InN-based nanorods ● Self Self-assembled assembled InN InN nanorods nanorods onon different different substrates substrates ● Self-assembled InGaN nanorods ● Broad- Broad-emission emission nanostructures ● Self Self--assembled assembled InGaN InGaN--based based Qdisks Qdisks ● Selective area growth (SAG) of InGaN Qdisks

Service needs forecasting: an approach for the automotive industry using analogies with medical ER management models.

During the past years, the industry has shifted position and moved towards “the luxury universe” whose customers are demanding, treating individuals as unique and valued customer for the business, offering vehicles produced with the state of the art technologies and implementing the highest finishing standards. Due to the competitive level in the market, car makers enable processes which equalizes customer services to E.R. management, being dealt with the maximum urgency that allows the comparison between both, car workshops and emergency rooms, where workshop bays or ramps will be equal to emergency boxes and skilled technicians are equivalent to the health care specialist, who will carry out tests and checks prior to afford any final operation, keeping the “patient” under control before it is back to normal utilization. This paper establishes a valid model for the automotive industry to estimate customer service demand forecasting under variable demand conditions using analogies with patient demand models used for the medical ER.

Intensive use of aluminium in car body construction

The developments in materials over the last decade have been considerable within the automotive industry, being one of the leaders in innovative product applications. Sustainable product development of an automotive structure requires a balanced approach towards technological, economical and ecological aspects. The introduction of new materials and processes is dependent on satisfying different factors. Competitive and legislative pressures, creating the need for change, affect these factors considerably. The process, direction and speed of change are often reactive. Current paper shows the application of aluminium alloys, for the use in the bottom structure of a car to face the problem for the weight of the entire bottom structure under static load conditions, including stiffness, strength and buckling constraints. In addition to minimized mass and materials' price, the assessment of an environmental impact of materials-candidates during the entire life cycle of the structure is considered.

SERVICE NEEDS FORECASTING: An Approach for the Motor Industry Using Analogies with Medical ER Management Models.

During the past years, the industry has shifted position and moved towards “the luxury universe” whose customers are demanding, treating individuals as unique and valued customer for the business, offering vehicles produced with the state of the art technologies and implementing the highest finishing standards. Due to the competitive level in the market, motor makers enable processes which equalizes customer services to E.R. management, being dealt with the maximum urgency that allows the comparison between both, car workshops and emergency rooms, where workshop bays or ramps will be equal to emergency boxes and skilled technicians are equivalent to the health care specialist, who will carry out tests and checks prior to afford any final operation, keeping the “patient” under control before it is back to normal utilization. This paper ratify a valid model for the automotive industry to estimate customer service demand forecasting under variable demand conditions using analogies with patient demand models used for the medical ER

Modelo de estimación de costes para tolerancias de diseño en la ingeniería de los procesos de producción

La disponibilidad los valores coste-tolerancia de un proceso de producción es un aspecto de interés desde el punto de vista de la Ingeniería de Proyectos en general y de la Ingeniería de Procesos de Producción en particular. Tanto en la fase de planificación de un proyecto como en las etapas de diseño de cada uno de los procesos de producción que posibilitarán su ejecución, las especificaciones del producto deben estar contenidas en un intervalo de tolerancia cuyo coste de obtención es tanto mayor cuanto menor es el margen de variación admisible. Por este motivo, el conocimiento del coste asociado a cada tolerancia es una herramienta de gran utilidad para el ingeniero de proyectos. A pesar de su interés, las curvas de coste-tolerancia se manejan con menor profusión de la que sería deseable, dada la gran interdependencia existente entre ellas y la localización espacio-temporal de los recursos a las que se asignan. El presente trabajo propone un método que permite establecer una relación coste-tolerancia a los procesos de producción de la Ingeniería de Proyectos, basada de la variabilidad derivada de los recursos de cada proceso.

Considerations in Determining the Cost of Measurement Uncertainty Associated with Dimensional Tolerances Verification

The verification of compliance with a design specification in manufacturing requires the use of metrological instruments to check if the magnitude associated with the design specification is or not according with tolerance range. Such instrumentation and their use during the measurement process, has associated an uncertainty of measurement whose value must be related to the value of tolerance tested. Most papers dealing jointly tolerance and measurement uncertainties are mainly focused on the establishment of a relationship uncertainty-tolerance without paying much attention to the impact from the standpoint of process cost. This paper analyzes the cost-measurement uncertainty, considering uncertainty as a productive factor in the process outcome. This is done starting from a cost-tolerance model associated with the process. By means of this model the existence of a measurement uncertainty is calculated in quantitative terms of cost and its impact on the process is analyzed.

Characterization of thin film PV modules under standard test conditions: Results of indoor and outdoor measurements and the effects of sunlight exposure

Photovoltaic modules based on thin film technology are gaining importance in the photovoltaic market, and module installers and plant owners have increasingly begun to request methods of performing module quality control. These modules pose additional problems for measuring power under standard test conditions (STC), beyond problems caused by the temperature of the module and the ambient variables. The main difficulty is that the modules’ power rates may vary depending both on the amount of time they have been exposed to the sun during recent hours and on their history of sunlight exposure. In order to assess the current state of the module, it is necessary to know its sunlight exposure history. Thus, an easily accomplishable testing method that ensures the repeatability of the measurements of the power generated is needed. This paper examines different tests performed on commercial thin film PV modules of CIS, a-Si and CdTe technologies in order to find the best way to obtain measurements. A method for obtaining indoor measurements of these technologies that takes into account periods of sunlight exposure is proposed. Special attention is paid to CdTe as a fast growing technology in the market.

Algoritmo Genético aplicado al problema de programación en procesos tecnológicos de maquinado con ambiente Flow Shop

Debido a las limitaciones de las técnicas de optimización convencionales, en el siguiente trabajo se presenta una metaheurística basada en un algoritmo genético (AG), para resolver problemas de programación de tipo flow shop, con el objetivo de minimizar el tiempo de finalización de todos los trabajos, más conocido como makespan. Este problema, considerado de difícil solución, es típico de la optimización combinatoria y se presenta en talleres con tecnología de maquinado, donde existen máquinas-herramientas convencionales y se fabrican diferentes tipos de piezas que tienen en común una misma ruta tecnológica (orden del proceso). La solución propuesta se probó con problemas clásicos publicados por otros autores, obteniéndose resultados satisfactorios en cuanto a la calidad de las soluciones encontradas y el tiempo de cómputo empleado.

Algoritmo genético aplicado a la programación en talleres de maquinado

En este trabajo se utiliza la metaheurística nombrada algoritmo genético, para dos variantes típicas de problemas de planificación presentes en un taller de maquinado de piezas: las variantes flujo general y flujo regular, y se ha seleccionado la minimización del tiempo de finalización de todos los trabajos o camino máximo, como objetivo a optimizar en un plan de trabajo. Este problema es considerado de difícil solución y es típico de la optimización combinatoria. Los resultados demuestran la calidad de las soluciones encontradas en correspondencia con el tiempo de cómputo empleado, al ser comparados con problemas clásicos reportados por otros autores. La representación propuesta de cada cromosoma genera el universo completo de soluciones factibles, donde es posible encontrar valores óptimos globales de solución y cumple con las restricciones del problema.

Pushover analysis for the seismic response prediction of cable-stayed bridges under multi-directional excitation

Cable-stayed bridges represent nowadays key points in transport networks and their seismic behavior needs to be fully understood, even beyond the elastic range of materials. Both nonlinear dynamic (NL-RHA) and static (pushover) procedures are currently available to face this challenge, each with intrinsic advantages and disadvantages, and their applicability in the study of the nonlinear seismic behavior of cable-stayed bridges is discussed here. The seismic response of a large number of finite element models with different span lengths, tower shapes and class of foundation soil is obtained with different procedures and compared. Several features of the original Modal Pushover Analysis (MPA) are modified in light of cable-stayed bridge characteristics, furthermore, an extension of MPA and a new coupled pushover analysis (CNSP) are suggested to estimate the complex inelastic response of such outstanding structures subjected to multi-axial strong ground motions.

Aplicabilidad de las diversas estrategias de análisis sísmico en puentes atirantados en rango elástico

En este trabajo se proponen estrategias de análisis y de modelado optimizadas para abordar el estudio sísmico de puentes atirantados que mantienen sus materiales en rango elástico, ofreciendo al diseñador un rango de errores esperables en cada caso en función del tipo de torre de atirantamiento, luz principal y terreno de cimentación, entre otras características. Para ello, se ha realizado un estudio comparativo de diferentes procedimientos de cálculo dinámico aplicados al análisis sísmico elástico de un gran número de puentes atirantados, y se han relacionado las desviaciones observadas con las simplificaciones introducidas en el planteamiento matemático de los mismos. Entre los métodos considerados se encuentra el cálculo modal espectral, el análisis modal dinámico y la integración directa del sistema acoplado de la dinámica. Además, el efecto del impacto del tablero contra las torres en dirección transversal ha sido analizado por medio de elementos de contacto. Se ha concluido que el cálculo modal espectral ofrece resultados que están del lado de la inseguridad, alrededor de de un 20%, respecto del cálculo modal dinámico de referencia, el cual es el más preciso

Claves para la requerida universalización simbológica de las Cartas Aeronáuticas

The aeronautical charts are a convenient means to provide aeronautical information in a manageable, condensed, and coordinated way. Despite having an extensive regulatory legislation backed by the International Civil Aviation Organization (ICAO), this kind of specialized mapping is defined by a marked symbolical disparity between the different editions published by countries and publishers. This implies not to follow the uniformity and consistency principles that ICAO have identified as essential to help ensure the safety of international civil aviation. Plans for the implementation of a global interoperability of aeronautical information require urgently rethink the way in which, so far, this information has been published and disseminated. A single, transverse, and independent symbolical specification would contribute to the generation of a well defined final-product that provides general purpose aeronautical information for an unequivocal interpretation. The contribution of this article is the verification of the real possibilities for the definition of a general specification that provides the mechanisms for a reliable, indisputable, and legible reading of aeronautical charts under any operational circumstances and conditions. Such conditions must be aligned with the specificities of any country, publishers or crew.

Water harvesting for young trees using Peltier plates powered by photovoltaic solar energy

Young trees transplanted from nursery into open field require a minimum amount of soil moisture to successfully root in their new location, especially in dry-climate areas. One possibility is to obtain the required water from air moisture. This can be achieved by reducing the temperature of a surface below the air dew point temperature, inducing water vapor condensation on the surface. The temperature of a surface can be reduced by applying the thermoelectric effect, with Peltier modules powered by electricity. Here, we present a system that generates electricity with a solar photovoltaic module, stores it in a battery, and finally, it uses the electricity at the moment in which air humidity and temperature are optima to maximize water condensation while minimizing energy consumption. Also, a method to reduce the evaporation of the condensed water is proposed. The objective of the system, rather than irrigating young plants in such a degree as to boost their growth, is to maintain them alive in the dryer periods.

Development of low cost photovoltaic sensor for over-tree radiation assessment

The crop diseases sometimes are related to the irradiance that the crop receives. When an experiment requires the measurement of the irradiance, usually it results in an expensive data acquisition system. If it is necessary to check many test points, the use of traditional sensors will increase the cost of the experiment. By using low cost sensors based in the photovoltaic effect, it is possible to perform a precise test of irradiance with a reduced price. This work presents an experiment performed in Ademuz (Valencia, Spain) during September of 2011 to check the validity of low cost sensors based on solar cells.

Grid-connected roof solar plants in educational institutions for testing and electricity generation: a case in Spain.

The use of photovoltaic experimental plants in engineering educational buildings contributes to an increase in acceptance of this technology by future engineers. There are some photovoltaic (PV) systems in educational buildings in Spain, but they are usually limited to buildings in relation to electrical technologies or research areas. They are not common in other educational or official buildings. This paper presents the project of a grid-connected solar plant with two main objectives. First, different PV module technologies will be compared. Second, an emphasis on agronomical areas in educational settings will be reviewed in an attempt to facilitate student engagement in the use of the power plant. The system is grid-connected in order to pay-back the investment in the plant. In fact the electricity generated by the plant will be used by the installations of the building, as it is the closest consumer. This work intends to approximate photovoltaic technology to university degrees not directly related with it and at the same time research in comparison of systems with different technologies. This is a good example of an solar plant for both optimum production and educational purposes.