Sergio Gil-Lopez

Tecnalia · ICT Division-ESI; Optimization, Modeling and Analytics (OPTIMA)

Solar energy forecasting represents a key issue in order to efficiently manage the supply-demand balance and promote an effective renewable energy integration. In this regard, an accurate solar energy forecast is of utmoss importance for avoiding large voltage variations into the electricity network and providing the system with mechanisms for mana...

The advent and progressive deployment of the so-called Smart Grid has unleashed a profitable portfolio of new possibilities for an efficient management of the low-voltage distribution network supported by the introduction of information and communication technologies to exploit its digitalization. Among all such possibilities this work focuses on t...

Heating ventilation and air conditioning (HVAC) systems represent an important amount of the total energy use in office buildings, accounting for near 30%. Moreover, in countries affected by extreme climates HVAC systems’ contribution to energy demand increases up to 50%. Therefore, the automation of energy efficient strategies that act on the Buil...

In this paper a modified version of the Harmony Search algorithm is proposed as a novel tool for phase swapping in Low Voltage Distribution Networks where the objective is to determine to which phase each load should be connected in order to reduce the unbalance when all phases are added into the neutral conductor. Unbalanced loads deteriorate powe...

The problem of partitioning a data set into disjoint groups or clusters of related items plays a key role in data analytics, in particular when the information retrieval becomes crucial for further data analysis. In this context, clustering approaches aim at obtaining a good partition of the data based on multiple criteria. One of the most challeng...

The amount of open information available on-line from heterogeneous sources and domains is growing at an extremely fast pace, and constitutes an important knowledge base for the consideration of industries and companies. In this context, two relevant data providers can be highlighted: the “Linked Open Data” (LOD) and “Social Media” (SM) paradigms....

The amount of on-line available open information from heterogeneous sources and domains is growing at an extremely fast pace, and constitutes an important knowledge base for the consideration of industries and companies. In this context, two relevant data providers can be highlighted: the “Linked Open Data” and “SocialMedia” paradigms. The fusion o...

Information about the position of entities is very valuable in many fields. People, animals, robots and sensors are some examples of entities that have been targeted as nodes of interest for localization purposes. Technical advances in ubiquitous computing and wireless communications properties are very valuable means to obtain localization informa...

When seeking near-optimal solutions for complex scheduling problems, meta-heuristics demonstrate good performance with affordable computational effort. This has resulted in a gravitation towards these approaches when researching industrial use-cases such as energy-efficient production planning. However, much of the previous research makes assumptio...

THIS PAPER PRESENTS A NOVEL BIOINSPIRED ALGORITHM TO TACKLE COMPLEX OPTIMIZATION PROBLEMS: the coral reefs optimization (CRO) algorithm. The CRO algorithm artificially simulates a coral reef, where different corals (namely, solutions to the optimization problem considered) grow and reproduce in coral colonies, fighting by choking out other corals f...

During the last years wind energy has experimented a significant growth in comparison with other types of renewable energy sources. Accordingly, the number of wind farms has increased sharply to become one of the most developed worldwide infrastructures. Unfortunately, the high number of constraints and restrictions that must be considered nowadays...

Global phenomena such as the climate warming and the consequently growing scales of wildfires motivate the need for computationally efficient tools and frameworks for assisting brigade commanders in their coordination and management duties. However, the current worldwide economical situation usually imposes severe budgetary constraints that ultimat...

In this paper, we propose a novel autonomous intelligent tool for the optimum design of a wireless relayed communication network deployed over disaster areas. The so-called dynamic relay deployment problem consists of finding the optimum number of deployed relays and their location aimed at simultaneously maximizing the overall number of mobile nod...

This paper thoroughly reviews and analyzes the main characteristics and application portfolio of the so-called Harmony Search algorithm, a meta-heuristic approach that has been shown to achieve excellent results in a wide range of optimization problems. As evidenced by a number of studies, this algorithm features several innovative aspects in its o...

The use of intelligent optimization systems has been a major topic of research in the last few years for improving the existing urban infrastructure, the traffic optimization and the mobility of citizens. These techniques are of great importance in the analysis and optimization of transportation networks, as well as their re-organization to improve...

This research work gravitates on the use of evolutionary meta-heuristics as an efficient computational means to improve the saturation level in car manufac-turing production chains, where material is prepared and buffered in Auto Guided Vehicles (AGVs). A thorough mathematically modelling of the problem is presented, whose complexity motivates the...

This paper proposes the application of a novel meta-heuristic algorithm to the metropolitan wireless local area network deployment problem. In this problem, the coverage level of the deployed network must be maximized while meeting an assigned maximum budget, set beforehand. Specifically, we propose an approach based on the Harmony Search (HS) algo...

In this paper we present the application of a hybrid harmony search (HS) algorithm to the Spread-Spectrum Radar Polyphase (SSRP) codes design. Such a design can be formulated as a non-linear max–min optimization problem, hard to be solved using classical numerical techniques. Soft-computing approaches have then been successfully applied to solve th...

This paper addresses the application of two different grouping-based algorithms to the so-called capacitated P-median problem (CPMP). The CPMP is an NP-complete problem, well-known in the operations research field, arising from a wide spectrum of applications in diverse fields such as telecommunications, manufacturing and industrial engineering. Th...

This extended abstract outlines a novel optimization approach for multi-band linear collaborative spectrum (LCS) sensing based on harmony search heuristics. Besides, the description of a centralized system architecture is also included in this manuscript, which is capable of processing the captured spectrum measurements from several nodes in a LCS...

This paper presents a novel heuristic multi-criteria tool capable of generating open-access wireless network deployments by exploiting the existing broadband infrastructure. Specifically, an external user dynamically selects, by virtue of our proposed scheme, a certain network layout depending on the target percentage of non-covered users and cost...

In this paper we outline a novel global heuristic tool to deal with a combination of the Capacitated P-Median (CPMP) and the Capacitated Minimum Spanning Tree (CMST) problems. This preliminary approach provides an efficient (in terms of power consumption due to emission or signal interferences) traffic-flow design for a setup consisting of a number...

The internationalization of a company is widely understood as the corporative strategy for growing through external markets. It usually embodies a hard process, which affects diverse activities of the value chain and impacts on the organizational structure of the company. There is not a general model for a successful international company, so the s...

In this paper we present a novel grouping harmony search algorithm for the Access Node Location Problem (ANLP) with different types of concentrators. The ANLP is a NP-hard problem where a set of distributed terminals, with distinct rate demands, must be assigned to a variable number of concentrators subject to capacity constraints. We consider the...

This paper gravitates on the spectrum channel allocation problem where each compounding node of a cognitive radio network is assigned a frequency channel for transmission over a given outgoing link, based on optimizing an overall network performance metric dependant on the level of interference among nearby nodes. In this context, genetically inspi...

The availability of accurate location information of constituent nodes becomes essential in many applications of wireless sensor networks. In this context, we focus on anchor-based networks where the position of some few nodes are assumed to be fixed and known a priori, whereas the location of all other nodes is to be estimated based on noisy pairw...

In several wireless sensor network applications the availability of accurate nodes' location information is essential to make collected data meaningful. In this context, estimating the positions of all unknown-located nodes of the network based on noisy distance-related measurements (usually referred to as localization) generally embodies a non-con...

In many applications based on Wireless Sensor Networks (WSNs) with static sensor nodes, the availability of accurate location information of the network nodes may become essential. The node localization problem is to estimate all the unknown node positions, based on noisy pairwise distance measurements of nodes within range of each other. Maximum L...

This paper presents a novel Grouping Harmony Search (GHS) algorithm for the Citywide Ubiquitous WiFi Network Design problem (WIFIDP). The WIFIDP is a NP-hard problem where private customers owning wireless access points connected to Internet share bandwidth with third parties. Aspects such as allocated budget and router capacities (coverage radius,...

This paper presents a novel iterative hybrid algorithm for subcarrier and power allocation in a cognitive orthogonal frequency division multiple access (OFDMA) downlink. In the considered setup a primary base station forwards information to K distant receivers by using a single OFDM waveform, whereas a secondary base station – subject to stringent...

This manuscript proposes a novel iterative approach for the so-called Switch Location Problem (SLP) based on the hybridization of a group-encoded Harmony Search combinatorial heuristic (GHS) with local search and repair methods. Our contribution over other avantgarde techniques lies on the dual application of the GHS operators over both the assignm...

Polyphase codes are widely used in radar systems as a pulse compression approach due to the fact that they produce lower side-lobes in the compressed signal than other methods. Unfortunately, the efficient design of such codes comprises by itself a non-linear n-dimensional NP-hard optimization problem, which has been so far tackled by using evoluti...

This paper presents a novel resource allocation procedure for OFDMA downlinks, which stems from an hy- bridization of the Harmony Search and the Differential Evolution heuristic algorithms. In this setup it is known that optimum subcarrier and power allocation is achieved through 1) assigning each subcarrier to the user with highest channel gain at...

This paper focuses on the data fusion scenario where N nodes sense and transmit the data generated by a source S to a common destination, which estimates the original information from S more accurately than in the case of a single sensor. This work joins the upsurge of research interest in this topic by addressing the setup where the sensed informa...

Tesis en colaboración con el Instituto de Astrofísica de Andalucía, CSIC Tesis Univ. Granada. Departamento de Física Aplicada. Leída el 31 de marzo de 2006

This paper outlines the application of the heuristic Harmony Search (HS) algorithm for efficient spectrum allocation in cognitive radio networks under a minimum Bit Error Rate (BER) criterion. Our proposed algorithm provides a higher degree of diversity in the search process by virtue of its particular improvisation procedure, as opposed to evoluti...

Focusing on efficiently handling traffic signalling for emergency vehicles via minimally-invasive schemes, in this manuscript we propose a novel traffic light preemption algorithm based on processing part of the Cooperative Awareness Messages (CAM) already defined in the so-called European Intelligent Transportation System (ITS) communication archi...

Focusing on CDMA (Code Division Multiple Access) uplink communications, this paper addresses the application of heuristic techniques to the multiple user detection problem when dealing with asynchrony between transmitters and bandwidth-limited PAM (Pulse AmplitudeModulation) signals. In such systems it is known that, even for the simplest case of b...

Recent contributions have shown that, by switching frequency bands at intermediate relay nodes, enhanced diversity can be attained in two-user wireless frequency division relay networks at a minimum computational cost. This paper elaborates on the design of frequency-switching patterns for more involved relay scenarios. We conclude that in general,...

This paper presents the adaptation of a novel heuristic algorithm to the Switch Location Problem (SLP), a NP-hard problem where a set of distributed terminals, with distinct rate demands, is to be assigned to a fixed number of concentrators subject to capacity constraints. Each terminal must be assigned to one and only one concentrator while keepin...

This paper introduces a novel heuristic algorithm for N-user detection in synchronous CDMA multiple access networks. In such systems, the performance of the conventional single-user detection technique (i.e. a rake receiver compounded by a set of matched filters) is clearly bounded by the well-known multiple access interference (MAI). To avoid this...

Focusing on densely deployed wireless sensor networks, this paper presents a novel method for joint source-channel-network coding of distributed correlated sources through multiple access relay channels. In such networks, the role of intermediate sensors as relay nodes permits to achieve enhanced end-to-end error performance and increased spatial d...

We report on the dependance of ozone volume mixing ratio profiles, retrieved from spectra of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS), on different retrieval setups such as different a-priori profiles, regularization strengths and spectral regions used for analysis. MIPAS is a spaceborne limb-viewing Fourier transform i...

MIPAS (Michelson Interferometer for Passive Atmosphere Sounding) is a high spectral resolution interferometer (0.035cm−1 unapodized) covering a very wide spectral range (from 4.16 to 16.4μm) with high sensitivity that was successfully launched on the 1st of March 2002 on the European Envisat satellite. MIPAS has measured spectra of the Earth’s uppe...

Daytime mesospheric limb emission spectra of ozone in the regime are analyzed with respect to vibrational excitation and relaxation processes. The data, which was obtained by the MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) instrument on board ESA's Environmental Satellite, is simulated by means of a non-local thermodynamic equ...

The proper characterization of ozone mid-ir radiances under non-LTE conditions is very important for the retrieval of mesospheric constituents such as ozone or carbon monoxide A recent study of Kaufmann et al 2006 indicated very large Envisat-MIPAS radiances at 4 8 um and suggested significant changes to standard non-LTE models of ozone to fit the...

The MIPAS instrument onboard ESA s Envisat satellite launched in March 2002 and the SABER instrument onboard NASA s TIMED satellite launched in December 2001 provide measurements of the kinetic temperature and a large number of atmospheric species including ozone during day and night Both instruments measure trace gas emissions from the Earth s lim...

In this work, we deal with the retrieval of O3 from the upper atmosphere data from 20 to 100 km using the high spectral resolution measurements of MIPAS in the regions of 14 and 10 μm. Non-LTE modelling of the O3 levels is included. Quality parameters of the retrievals and sensitivity tests for tuning the retrieval processor are presented. Day and...

Ozone volume mixing ratio (VMR) profiles are measured by the Michelson Interferometer for passive atmospheric sounding (MIPAS) on ENVISAT. The data sets produced by the science data processor at Institut für Meteorologie und Klimaforschung (IMK), Germany are compared with those obtained by halogen occultation experiment (HALOE) on UARS and by sub-m...

Vertical profiles of O3 and NO2 abundances from the atmospheric instruments GOMOS (Global Ozone Monitoring by the Occultation of Stars), MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) and SCIAMACHY (Scanning Imaging Spectrometer for Atmospheric Chartography) all on-board the recently launched European Space Agency (ESA) Environme...

With the successful launch of the European Space Agency’s Envisat satellite new possibilities for global night-time measurements of middle atmospheric ozone have emerged. The GOMOS and MIPAS instruments on board Envisat are able to measure ozone in both day and night conditions, which is especially important in the mesosphere where the diurnal vari...

Pronounced upper stratospheric and mesospheric NOx enhancements were measured by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) in the Southern Hemisphere (SH) polar vortex from May to August 2003, reaching average abundances of 60 ppbv at 50–60 km in July. Peak mixing ratios of around 200 ppbv were measured in the polar nigh...

We report on the dependance of ozone volume mixing ratio profiles, retrieved from spectra of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS), on different retrieval setups such as different a-priori profiles, regularization strengths and spectral regions used for analysis. MIPAS is a spaceborne limb-viewing Fourier transform i...

1] Vertical profiles of stratospheric HNO 3 were retrieved from limb emission spectra recorded by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) aboard the Envisat research satellite during the Antarctic winter 2003. A high second maximum of HNO 3 was found around 34 km altitude with abundances up to 14 ppbv HNO 3 during July...

The temperature and ozone volume mixing ratio (VMR) profiles measured by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on ENVISAT are used to study the unusual Antarctic major stratospheric warming of 2002. The observed zonal mean temperatures show rapid poleward increase and remarkable reversal of the latitudinal gradients...

In this article we report the most recent advances of our knowledge of non-LTE atmospheric emissions gained from the MIPAS spectra on the Envisat satellite. These include improvements in our knowledge: of the collisional processes between the CO2 (1001), (0221), and (0201) vibrational levels; of the nascent distribution and collisional relaxation o...

1] Time series of stratospheric ClO and HOCl have been measured with the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on board the Environmental Satellite (ENVISAT) during the solar storm episode in October/November 2003. A remarkable enhancement of ClO mean values (averaged over latitudes poleward from 70°N) was found, reachin...

The large solar storms in October-November 2003 produced enormous solar proton events (SPEs) where high energetic particles reached the Earth and penetrated into the middle atmosphere in the polar regions. At this time, the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) was observing the atmosphere in the 6-68 km altitude range....

The large solar storm in October–November 2003 produced enormous amounts of high-energy protons which reached the Earth and penetrated into the middle atmosphere in the polar regions. At this time, the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on board the Environmental Satellite (ENVISAT) was observing the atmosphere in the...

The Michelson Interferometer for Passive Atmosphere Sounding (MIPAS) on board of ESA's ENVISAT measures the global distribution of infrared emissions by atmospheric gases from 4mum to 15mum. The upper atmosphere measurement mode spans altitudes from 20-100 km and allows for the retrieval of species from the tropopause region up to the lower thermos...

[1] The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) onboard the Envisat satellite provides temperature and various gas profiles from limb-viewing midinfrared emission measurements. The stratospheric temperatures retrieved at the Institut für Meteorologie und Klimaforschung (IMK) for September/October 2002 and October/November...

We present unequivocal evidence for CH4 7.6 mum non-local thermodynamic equilibrium (non-LTE) mesospheric emissions as measured by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) experiment on board the ESA Envisat satellite. We have employed non-LTE radiative transfer models, already used and validated in studies of other atm...

The temperatures retrieved from MIPAS/ENVISAT limb mid-infrared emission and CHAMP GPS radio occultation measurements are compared at. altitudes between 8 - 30 km during the stratospheric major sudden warming in the southern hemisphere winter of 2002. The mean differences between the correlative measurements of the two instruments are less than sim...

This analysis presents comparisons of the atmospheric temperatures retrieved from GPS/SAC-C radio occultation observations using the JPL retrieval software, and from MIPAS/ENVISAT infrared spectrum measurements using the IMK data processor. Both individual profiles and zonal means of the atmospheric temperature at dierent seasons and geo-locations...

The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) is a high-resolution limb sounder on board the European Space Agency ENVISAT satellite, successfully launched on March 1, 2002. MIPAS measures the atmospheric emission in the 4.15-14.6 mu m range with a spectral resolution of 0.05 cm-1 (apodised). The instrument scans the limb op...

The Michelson Interferometer for Passive Atmosphere Sounding (MIPAS) on board of the polar orbiter ENVISAT, launched on March 1st, 2002, detects non-LTE emissions of NO (5.3 μ m) and NO2 (6.2 μ m) with high spectral resolution. The simultaneous detection of both NOx species along with the pole-to-pole coverage of MIPAS data offers an unique opportu...

MIPAS on ENVISAT measures vertical profiles of atmospheric temperature, ozone, and other species with nearly global coverage and high accuracy/precision. The standard observation mode covers the altitude region between 6 and 68 km. The atmospheric state parameters retrieved from MIPAS measurements using the IMK data analysis processor are compared...

European Space Agency's Envisat-1 satellite was launched into a polar orbit on March 1, 2002. Onboard are various instruments measuring the Earth and its atmosphere. MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) is a high-resolution (0.05 cm-1, apodised) mid-IR limb sounder which allows to measure the kinetic temperature and a l...

Retrieval of abundances of atmospheric species from limb infrared emission spectra requires accurate knowledge of the pointing of the instrument in terms of elevation, as well as temperature and pressure profiles. An optimal estimation-based method is presented to infer these quantities from measured spectra. The successful and efficient joint retr...

On March 1, 2002 the space-borne limb viewing mid-infrared high-resolution Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) has been brought on board the ENVISAT satellite into a polar sun-synchroneous orbit. Although the level-1 testing and validation phase has not been finished, ESA has made available datasets of 4 early orbits t...

On 1 March 2002 the Envisat research satellite has been launched successfully into its sun-synchronous orbit. One of its instruments for atmospheric composition sounding is the Michelson Interferometer for Passive Atmospheric Sounding, a limb-scanning mid-infrared Fourier transform spectrometer. Different scientific objectives of data users require...

On 1 March 2002 the Envisat research satellite has been launched successfully into its sun-synchronous orbit. One of its instruments for atmospheric composition sounding is the Michelson Interferometer for Passive Atmospheric Sounding, a limb-scanning mid-infrared Fourier transform spectrometer. Different scientific objectives of data users require...