An Iterative Optimization Method Using Genetic Algorithms and Gaussian Process Based Regression in Nuclear Reactor Design Applications

The optimization of a complex system involves the determination of optimum values for a set of design parameters. The optimization search happens in order to meet a specific set of objectives concerning the quantities of interest (QOI). Also, the design parameters are a subset of the input parameters and the QOIs are determined from the output parameters. Particularly, when the parameter space is large, optimization necessitates a significant number of executions of the simulator to obtain a desired solution in tolerance limits. When the simulations are expensive in terms of computation time, an emulator based on regression methods is useful for predictions. This work presents a novel methodology that uses an iterative hybrid global optimization method (GOM) using genetic algorithms (GA) and simulated annealing (SA) model coupled (HYBGASA) with a Gaussian process regression method based emulator (GPMEM) to optimize a set of input parameters based on a set of defined objectives in a nuclear reactor power system. Hereafter this iterative hybrid method comprising of HYBGASA and GPMEM would be called as the “IHGOM". In addition to optimization, IHGOM iteratively updates the trial data obtained from the neighborhood of the near optimal solution, used to train the GPMEM in order to reduce regression errors. The objective is to develop, model and analyze IHGOM, and apply it to an optimization problem in the design of a nuclear reactor. Development and analysis of IHGOM and its implementation in a nuclear reactor power system problem is a significant contribution to the optimization and the nuclear engineering communities

The doctoral research abstract. Vol:9 2016 / Institute of Graduate Studies, UiTM

FOREWORD: Seventy three doctoral graduands will be receiving their scroll today signifying their achievements in completing their PhD journey. The novelty of their research is shared with you through The Doctoral Abstracts on this auspicious occasion, UiTM 84th Convocation. We are indeed proud that another 73 scholarly contributions to the world of knowledge and innovation have taken place through their doctoral research ranging from Science and Technology, Business and Administration, and Social Science and Humanities. As we rejoice and celebrate your achievement, we would like to acknowledge dearly departed Dr Halimi Zakaria’s scholarly contribution entitled “Impact of Antecedent Factors on Collaborative Technologies Usage among Academic Researchers in Malaysian Research Universities”. He has left behind his discovery to be used by other researchers in their quest of pursuing research in the same area, a discovery that his family can be proud of. Graduands, earning your PhD is not the end of discovering new ideas, invention or innovation but rather the start of discovering something new. Enjoy every moment of its discovery and embrace that life is full of mystery and treasure that is waiting for you to unfold. As you unfold life’s mystery, remember you have a friend to count on, and that friend is UiTM. Congratulations for completing this academic journey. Keep UiTM close to your heart and be our ambassador wherever you go. / Prof Emeritus Dato’ Dr Hassan Said Vice Chancellor Universiti Teknologi MAR

Heliostat field aiming strategies for solar central receivers

Mención Internacional en el título de doctorLa presente tesis está dedicada al desarrollo de modelos ópticos aplicados a la tecnología de central solar tipo torre. Más concretamente, este trabajo se centra en el modelado de mapas de flujo y estrategias de apuntamiento para sistemas de receptor central. Los códigos resultantes son de utilidad en las fases de diseño y operación de centrales solares de torre. Esta memoria fundamentalmente presenta cuatro modelos computacionales. El primer modelo, sobre el cual se construyen el resto de modelos, calcula la distribución de densidad de flujo incidente en cualquier tipo de receptor central y que es causada por un único heliostato. El procedimiento se basa en la proyección oblicua de la malla de cálculo desde el receptor hasta el plano imagen, en donde se evalúa una función analítica de precisión conocida, e.g. UNIZAR. La proyección oblicua se obtiene mediante un adecuado cambio de sistemas de coordenadas. El método de proyección reproduce notablemente la distorsión presente en la mancha de luz concentrada cuando el ángulo de incidencia con el receptor es elevado. Este modelo básico ha sido validado con medidas de distribución de flujo en un receptor plano y con simulaciones de Monte Carlo de trazado de rayos para un receptor cilíndrico. En comparación con SolTrace, el modelo propuesto requiere un tiempo de computación 50 veces inferior y con un nivel de resolución aún mayor. El segundo modelo determina los errores de canteo en las facetas de heliostatos reales. En base a un algoritmo de optimización determinista, se ha establecido un procedimiento que ajusta los mapas de flujo simulados con las imágenes tomadas en un blanco lambertiano. Se han empleado imágenes experimentales tomadas en la planta THEMIS para encontrar los errores de reglaje en tres heliostatos CETHEL seleccionados. A partir de los resultados del modelo, uno de los heliostatos ha sido satisfactoriamente reajustado, mejorando de forma significativa su calidad óptica y validando la metodología propuesta. El tercer modelo es una ampliación del primero de ellos para superponer los mapas de flujo producidos por cada uno de los heliostatos en un campo completo. Las pérdidas ópticas por sombras y bloqueos se calculan mediante proyección paralela de los heliostatos vecinos. Se ha desarrollado una estrategia de apuntamiento que da lugar a mapas de flujo simétricos respecto de la línea media ecuatorial del receptor y que depende de un solo parámetro: k, factor de apuntamiento. Con k = 3 se obtienen mapas de flujo similares a los de apuntamiento simple al ecuador, mientras que con k = 0 los heliostatos apuntan a los bordes inferior y superior del receptor. Para el caso de estudio basado en Gemasolar, un factor de apuntamiento igual a 2 da lugar a las distribuciones de flujo más uniformes, i.e. perfil plano en la región central, sin menoscabo del factor de intercepción en comparación con el apuntamiento ecuatorial simple. En el cuarto de los modelos se ha implementado una estrategia de apuntamiento óptima para receptores centrales de sales fundidas. Se ha desarrollado un algoritmo que maximiza la potencia térmica instantánea del receptor, al mismo tiempo que se cumplen sus límites de operación. Los límites de corrosión y estrés térmico se traducen en flujos máximos admisibles; AFD, por sus siglas en inglés. En comparación con el apuntamiento simple, habitualmente inviable, la estrategia de apuntamiento optimizado asegura la integridad del receptor, a la vez que las pérdidas por desbordamiento sólo se incrementan en 4 puntos porcentuales. Se ha comprobado que la posición óptima de los apuntamientos en cada panel se encuentra, en promedio, ligeramente desplazada hacia el lado de entrada de las sales. A pesar de los requisitos contradictorios entre paneles adyacentes de receptores multi-panel con flujo de sales en serpentín, el algoritmo consigue un buen ajuste al perfil AFD instantáneo. El código resultante requiere alrededor de 2 minutos de cálculo en una computadora estándar para determinar los apuntamientos óptimos en un campo de 2650 heliostatos.This thesis deals with the development of optical models for solar power tower technology. Specifically, this work is focused on modeling flux mapping and aiming strategies for central receiver systems (CRS). The resulting codes are applicable to CRS design and operation. This dissertation essentially presents four computational models. The first model, on which the rest of the models are built up, computes the flux density distribution incident on any kind of central receiver which is caused by a single heliostat. The procedure relies on the oblique projection of the receiver mesh onto the image plane, where an accurate analytic function, e.g. UNIZAR, is evaluated. Oblique projection is accomplished by transformation of coordinate systems. The 4-step projection method remarkably reproduces the distorted spot found for large incidence angles on the heliostat and the receiver. This basic model was validated against flux measurements on a flat receiver and Monte Carlo Ray Tracing simulations on a cylindrical receiver. Compared to SolTrace, the model takes 50 times less computation time and higher level of resolution. The second model was developed to determine canting errors in the facets of real heliostats. Based on a deterministic optimization algorithm, a procedure was set up to minimize the difference between computed flux maps and captured images on a lambertian target. Experimental images from THEMIS plant were employed to find out canting errors in selected CETHEL heliostats. From results of the model, one of the heliostats was successfully readjusted, significantly improving its optical quality, and validating the proposed methodology. The third model extends the basic model to superpose single heliostat flux maps in a whole field of heliostats. Shading and blocking losses are computed by parallel projection of neighbor heliostats. An aiming strategy, symmetric about the receiver equator, was developed on the basis of only one parameter: k, aiming factor. Nearly single equatorial aiming is achieved with k = 3, while k = 0 results in pointing to either upper or lower receiver edges. For the Gemasolar case study, an aiming factor equal to 2 yielded the most uniform flux maps, i.e. flat profile in the central region, and negligible increase in spillage losses compared to equatorial aiming. An optimal aiming strategy for molten salt receivers was implemented in the fourth model. An algorithm was developed to maximize receiver thermal output, while meeting at the same time corrosion and thermal stress limits; which were translated into allowable flux densities, AFD. Compared to unreliable single aiming, the optimized aiming strategy ensures receiver integrity and spillage losses only increase up to 4 percentage points. It was found that optimal aim points are, on average, slightly shifted towards the panel entrance. Despite the conflicting demand between adjacent panels in multi-panel receivers with serpentine flow pattern, the fit algorithm performs noticeable matching to the AFD profile. The resulting code takes around 2 minutes in a standard PC to compute the optimal aim points for a field made up of 2650 heliostats.Programa Oficial de Doctorado en Ingeniería Mecánica y de Organización IndustrialPresidente: Manuel Jesús Blanco Muriel.- Secretario: Manuel Romero Álvarez.- Vocal: Francisco Javier Collado Giméne

Artificial intelligence and smart vision for building and construction 4.0: Machine and deep learning methods and applications

This article presents a state-of-the-art review of the applications of Artificial Intelligence (AI), Machine Learning (ML), and Deep Learning (DL) in building and construction industry 4.0 in the facets of architectural design and visualization; material design and optimization; structural design and analysis; offsite manufacturing and automation; construction management, progress monitoring, and safety; smart operation, building management and health monitoring; and durability, life cycle analysis, and circular economy. This paper presents a unique perspective on applications of AI/DL/ML in these domains for the complete building lifecycle, from conceptual stage, design stage, construction stage, operational and maintenance stage until the end of life. Furthermore, data collection strategies using smart vision and sensors, data cleaning methods (post-processing), data storage for developing these models are discussed, and the challenges in model development and strategies to overcome these challenges are elaborated. Future trends in these domains and possible research avenues are also presented

STEM Undergraduate Research Symposium 2016 Full Program

Full Program of the 2016 LSSF STEM Undergraduate Research Conference