# Inmaculada García FernandezUniversity of Malaga | UMA · Department of Computers Architecture

Inmaculada García Fernandez

PhD

## About

232

Publications

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2,269

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Introduction

Inmaculada García Fernandez currently works at the Department of Computers Architecture , University of Malaga. Inmaculada does research in Computer Engineering. Their current project is 'High performance computing in Dynamic and Global optimization'.

## Publications

Publications (232)

Stochastic Global Optimization has left us with the challenge to derive theoretical results on the speed of convergence. In this contribution , we formulate this challenge towards the question to look at the algorithm from a Markovian perspective. Several considerations are mentioned for the case of Controlled Random Search (CRS).

Modern computational platforms are characterized by the heterogeneity of their processing elements. Additionally, there are many algorithms which can be structured as a set of procedures or tasks with different computational cost. Balancing the computational load among the available processing elements is one of the main keys for the optimal exploi...

The efficient control of electrical vehicles may contribute to sustainable use of energy. In recent studies, a model has been analyzed and several algorithms based on branch and bound have been presented. In this work, we discuss a reformulated model on the control of an electric vehicle based on the minimization of the energy consumption during an...

Dynamic programming (DP) approaches, in particular value iteration, is often seen as a method to derive optimal policies in inventory management. The challenge in this approach is to deal with an increasing state space when handling realistic problems. As a large part of world food production is thrown out due to its perishable character, a motivat...

As a large part of world food production spoils/expires before consumption, reduction of food waste by optimizing order policies in retail is of importance. We sketch here the computational burden of trying to obtain the optimal order quantities with the process of Value Iteration for a retailer situation with highly perishable products. It appears...

In literature, one can find a branch and bound approach for the control of electric vehicles was published. Using that model, we create a DP implementation to obtain similar results.

Una gran parte de la producción mundial de alimentos se desecha debido a su carácter pere-cedero. Esto hace que exista una gran motivación para investigar las políticas óptimas de pedidos de productos perecederos en el comercio minorista que minimicen las grandes cantidades de alimentos que van a la basura. En este trabajo analizamos los aspectos c...

The offshore wind energy industry is expected to continue its growth tendency in the near future. The European Wind Energy Association expects in its Central Scenario by 2030 a total installed capacity of 66 GW of offshore wind in the UE. Offshore wind farms (OWFs) are large scale infrastructures, requiring maintenance fleets to perform operations...

Branch and bound (BnB) Global Optimization algorithms can be used to find the global optimum (minimum) of a multiextremal function over the unit hypercube and unit simplex with a guaranteed accuracy. Subdivision strategies can take the information of the evaluated points into account leading to irregular shaped subsets. This study focuses on the pa...

This paper analyses and evaluates parallel implementations of an optimization algorithm for perishable inventory control problems. This iterative algorithm has high computational requirements when solving large problems. Therefore, the use of parallel and distributed computing reduces the execution time and improves the quality of the solutions. Th...

In several areas like global optimization using branch-and-bound methods for mixture design, the unit n-simplex is refined by longest edge bisection (LEB). This process provides a binary search tree. For (Formula presented.), simplices appearing during the refinement process can have more than one longest edge (LE). The size of the resulting binary...

In Branch and Bound (BnB) algorithms, the branching rule plays an important rule in order to reduce the number of evaluated sub-problems and points. Recent studies addressed the unit simplex refinement with regular simplices. When the achieved accuracy is related on the distance among sampled points, a common method is to stop the refinement when t...

A natural way to define branching in branch and bound (B&B) for blending problems is bisection. The consequence of using bisection is that partition sets are in general irregular. The question is how to use regular simplices in the refinement of the unit simplex. A regular simplex with fixed orientation can be represented by its center and size, fa...

En el ámbito de la optimización global basada en técnicas de ramificación y acotación, cuando el espacio de búsqueda es un n-símplex regular es habitual utilizar como regla de división la bisección por el lado mayor, debido a que garantiza la convergencia del algoritmo. Cuando la dimensión del n-símplex es mayor de 2 existen varios lados mayores qu...

En este trabajo se analizan y evalúan dos implementaciones de un algoritmo de optimización para un problema de control de inventarios de productos perecederos. Las implementaciones se han llevado a cabo utilizando una arquitectura heterogénea donde cada nodo está compuesto por varios multicores y varias GPUs. Las versiones paralelas que se han desa...

Simplicial partitions to divide a bounded area in branch and bound makes the use of an upper fitting appropriate for finding the bounds on the subsets. Bisecting the longest edge avoiding needle-shaped simplices leads to a choice of which longest edge to bisect in higher dimensions. We investigate the behaviour of the search and the resulting binar...

Simplicial partitions are suitable to divide a bounded area in branch and bound. In the iterative refinement process, a popular strategy is to divide simplices by their longest edge, thus avoiding needle-shaped simplices. A range of possibilities arises in higher dimensions where the number of longest edges in a simplex is greater than one. The beh...

In several areas like Global Optimization using branch-and-bound methods, the unit n-simplex is refined by bisecting the longest edge such that a binary search tree appears. This process generates simplices belonging to different shape classes. Having less simplex shapes facilitates the prediction of the further workload from a node in the binary t...

Optical Diffraction Tomography has been recently introduced in fluid velocimetry to provide three dimensional information of seeding particle locations. In general, image reconstruction methods at visible wavelengths have to account for diffraction. Linear approximation has been used for three-dimensional image reconstruction, but a non-linear and...

Resumen— La división de un símplice regular aparece en varias aplicaciones industriales que usan algoritmos de Optimización Global basados en Ramificación y Acotación. Normalmente la división de un símplice se realiza mediante la bisección del lado mayor, debido a que garantiza la convergencia del algoritmo. El objetivo de este trabajo es determina...

In simplicial based Global Optimization branch-and-bound methods on the unit n-simplex refinement by bisecting the longest edge leads to a binary search tree. Irregular sub-simplices generated in the refinement process may have more than one longest edge for a dimension higher than 3. The question is how to choose the longest edge to be bisected su...

We study the global optimal solution for a planning problem of inventory control of perishable products and non-stationary demand.

Tomography has been recently introduced in fluid velocimetry to provide three dimensional information of the location of particles. In particular, author’s previous works have proven the potential of Optical Diffraction Tomography for biological and microfluidic devices. In general, image reconstruction methods at visible wavelengths have to accoun...

Simplicial subsets are popular in branch-and-bound methods for Global Optimization. Longest Edge Bisection is a convenient way to divide a simplex. When the number of dimensions is greater than two, irregular simplices (not all edges have the same length) may appear with more than one longest edge. In these cases, the first longest edge is usually...

In several areas like Global Optimization using branch-and-bound methods, the unit n-simplex is refined by bisecting the longest edge such that a binary search tree appears. The refinement usually selects the first longest edge and ends when the size of the sub-simplices generated in the refinement is smaller than a given accuracy. Irregular sub-si...

Anomaly detection is an important task for hyperspectral data exploitation. Although many algorithms have been developed for this purpose in recent years, due to the large dimensionality of hyperspectral image data, fast anomaly detection remains a challenging task. In this work, we exploit the computational power of commodity graphics processing u...

In this paper, we perform an experimental study of the interactions between execution time (i.e., performance), power, and energy that occur in modern low-power architectures when executing the RX algorithm for detecting anomalies in hyperspectral images (i.e., signatures which are spectrally different from their surrounding data). We believe this...

Electron tomography enables three-dimensional (3D) visualization and analysis of the subcellular architecture at a resolution of a few nanometres. Segmentation of structural components present in 3D images (tomograms) is often necessary for their interpretation. However, it is severely hampered by a number of factors that are inherent to electron t...

The resolution of the 3D Helmholtz equation is required in the development of models related to a wide range of scientific and technological applications. For solving this equation in complex arithmetic, the biconjugate gradient (BCG) method is one of the most relevant solvers. However, this iterative method has a high computational cost because of...

A naturalway to define branching in Branch-and-Bound for blending problem is to do bisection. The disadvantage of bisectioning is that partition sets are in general irregular. A regular simplex with fixed orientation can be determined by its center and size, allowing storage savings in a Branch-and- Bound algorithm from computational perspective. U...

We are interested in the resolution of the 3D Helmholtz equation for real applications. Solving this problem numerically is a computational challenge due to the large memory requirements of the matrices and vectors involved.For these cases, the massive parallelism of GPU architectures and the high performance at lower energy of the multicores can b...

Branch-and-Bound (B&B) algorithms to solve Global Optimization (GO) may use n-simplicial partition sets. The n-simplex represents an n-dimensional body with n+1 vertices in (n+1)-dimensional space. The aim of this article is to investigate the properties of the binary tree generated by iterative bisection of the longest edge (LE) of the regular n-s...

En el ámbito de la optimización global basada en técnicas de ramificación y acotación, cuando el espacio de búsqueda es un n-simplex regular es habitual utilizar como regla de división la bisección por el lado mayor. Este modo de división evita que los subproblemas generados tengan una forma degenerada o poco redondeada y además da lugar a un
muest...

Blending problems are global optimization problems where the cheapest
product has to be determined. A product is as mixture of raw materials
having quadratic constraints in its design. These problems are characteri-
zed by an initial search space determined by a regular n + 1 dimensional
simplex (n-simplex). Branch and bound algorithms have been us...

In general, solving Global Optimization (GO) problems by Branch-and-Bound (B&B) requires a huge computational capacity. Parallel
execution is used to speed up the computing time. As in this type of algorithms, the foreseen computational workload (number
of nodes in the B&B tree) changes dynamically during the execution, the load balancing and the d...

We describe the minimum volume simplex enclosure problem (MVSEP), which is known to be a global optimization problem, and further investigate its multimodality. The problem is a basis for several (unmixing) methods that estimate so-called endmembers and fractional values in a linear mixing model. We describe one of the estimation methods based on M...

In this work, the problem of a company or chain (the leader) that considers the reaction of a competitor chain (the follower) is studied. In particular, the leader wants to set up a single new facility in a planar market where similar facilities of the follower, and possibly of its own chain, are already present. The follower will react by locating...

Sparse matrix matrix (SpMM) multiplication is involved in a wide range of scientific and technical applications. The computational
requirements for this kind of operation are enormous, especially for large matrices. This paper analyzes and evaluates a method
to efficiently compute the SpMM product in a computing environment that includes graphics p...

In a wide variety of applications from different scientific and engineering fields, the solution of complex and/or nonsymmetric linear systems of equations is required. To solve this kind of linear systems the BiConjugate Gradient method (BCG) is especially relevant. Nevertheless, BCG has a enormous computational cost. GPU computing is useful for a...

Blending algorithms aim for solving the problem of determining the mixture of raw materials in order to obtain a cheap and feasible recipe with the smallest number of raw materials. An algorithm that solves this problem for two products, where available raw material is limited, has two phases. The first phase is a simplicial branch-and-bound algori...

Anomaly detection is an important task for hyperspectral data exploitation. A standard approach for anomaly detection in the literature is the method developed by Reed and Xiaoli, also called RX algorithm. A variation of this algorithm consists of applying the same concept to a local sliding window centered around each image pixel. The computationa...

Three-dimensional (3D) electron microscopy (EM) has become a major player in structural cell biology as it enables the analysis of subcellular architecture at an unprecedented level of detail. Interpretation of the resulting 3D volumes strongly depends on segmentation, which consists in decomposing the volume into their structural components. The c...

A wide range of applications in engineering and
scientific computing are based on the computation of matrices
products, where one of them is sparse. The computational
requirements of these operations are very high when dimensions
of the matrices increase. The goal of this work is the acceleration
of the sparse matrix matrix product (SpMM) on Graphi...

This paper analyses several parallel approaches for the development of a physical model of Non-linear ODT for its application in velocimetry techniques. The main benefits of its application in HPIV are the high accuracy with non-damaging radiation and its imaging capability to recover information from the vessel wall of the flow. Thus ODT-HPIV is s...

Interval Branch-and-Bound (B&B) algorithms are powerful methods which aim for guaranteed solutions of Global Optimisation problems. Lower bounds for a function in a given interval can be obtained directly with Interval Arithmetic. The use of lower bounds based on Taylor forms show a faster convergence to the minimum with decreasing size of the sear...

This work introduces a new generic framework to the analysis of ridges and its application to segmentation of planar structures in bioimaging. Based on a Gaussian model, local information associated to ridges is extracted, which actually characterise them. The theoretical basis of the framework is first presented for the one-dimensional case. Its e...

The mixture design problem for two products concerns finding simultaneously two recipes of a blending problem with linear, quadratic and semi-continuity constraints. A solution of the blending problem minimizes a linear cost objective and an integer valued objective that keeps track of the number of raw materials that are used by the two recipes, i...

This work presents an approach to detection of planar structures in three-dimensional (3D) datasets obtained by different bioimaging modalities. The strategy has already turned out to be effective to segment membranes from 3D volumes in the field of electron tomography, an emerging and powerful technique in structural and cellular biology. This app...

Hyperspectral imaging is an active area of research in Earth and planetary observation. One of the most important techniques
for analyzing hyperspectral images is spectral unmixing, in which mixed pixels (resulting from insufficient spatial resolution
of the imaging sensor) are decomposed into a collection of spectrally pure constituent spectra, c...

In most competitive location models available in the literature, it is assumed that the demand is fixed independently of market conditions. However, demand may vary depending on prices, distances to the facilities, etc., especially when the goods are not essential. Taking variable demand into consideration increases the complexity of the problem an...

Electron tomography is the leading technique for visualizing the cell environment in molecular detail. Interpretation of the three-dimensional (3D) density maps is however hindered by different factors, such as noise and the crowding at the subcellular level. Although several approaches have been proposed to facilitate segmentation of the 3D struct...

Interval Branch-and-Bound (B&B) algorithms are powerful methods which aim for guaranteed solutions of Global Optimization problems. Lower bounds for a function in a given interval can be obtained directly with Interval Arithmetic. The use of lower bounds based on Taylor forms show a faster convergence to the minimum with decreasing size of the sear...

Three-dimensional electron microscopy allows scientists to study biological specimens and to understand how they behave and interact with each other depending on their structural conformation. Electron microscopy projections of the specimens are taken from different angles and are processed to obtain a virtual three-dimensional reconstruction for f...

Remotely sensed hyperspectral sensors provide image data containing rich information in both the spatial and the spectral
domain, and this information can be used to address detection tasks in many applications. One of the most widely used and
successful algorithms for anomaly detection in hyperspectral images is the RX algorithm. Despite its wide...

Several parallel strategies for solving a centroid problem are presented. In the competitive location problem considered in
this paper, the aim is to maximize the profit obtained by a chain (the leader) knowing that a competitor (the follower) will
react by locating another single facility after the leader locates its own facility. A global optimiz...

This work studies how to adapt the number of threads of a parallel Interval Branch and Bound algorithm to the available computational
resources based on its current performance. Basically, a thread can create a new thread that will process part of the ancestor
workload. In this way, load balancing is inherent to the creation of threads. The applica...

In this work, two parallel techniques based on shared memory programming are presented. These models are specially suitable
to be applied over evolutionary algorithms. To study their performance, the algorithm UEGO (Universal Evolutionary Global Optimizer) has been chosen.
Evolutionary algorithm–Shared memory programming–Computational experiment–U...

This work studies the problem of balancing the workload of iterative algorithms on heterogeneous multiprocessors. An approach,
called ADITHE, is proposed and evaluated. Its main features are: (1)using a homogeneous distribution of the workload on the
heterogeneous system, the speed of every node is estimated during the first iterations of the algor...