José Carlos Nieto-Borge

University of Alcalá | UAH · Department of Physics and Mathematics

This paper focuses on modeling a disordered system of quantum dots (QDs) by using complex networks with spatial and physical-based constraints. The first constraint is that, although QDs (=nodes) are randomly distributed in a metric space, they have to fulfill the condition that there is a minimum inter-dot distance that cannot be violated (to mini...

This paper focuses on modeling a disorder ensemble of quantum dots (QDs) as a special kind of Random Geometric Graphs (RGG) with weighted links. We compute any link weight as the overlap integral (or electron probability amplitude) between the QDs (=nodes) involved. This naturally leads to a weighted adjacency matrix, a Laplacian matrix, and a time...

This work introduces the deconvolution as a technique to reconstruct missing information in data. While the method was originally developed for ocean waves, it will be useful in a wider range of applications where gaps in data may alter the statistics or spikes have to be eliminated without removing extreme values. For the application to ocean wave...

We investigate how the extreme wave statistics of a combined windsea and swell appears to be different from the extreme wave statistics of the corresponding windsea and swell partitions. We consider the situation of following long-crested windsea and swell in laboratory experiments and in simulations using a high-order spectral method (HOSM). We al...

Wave groups can be detected and studied by using the wave envelope. So far, the method used to compute the wave envelope employs the Riesz transform. However, such a technique always produces symmetric envelopes, which is only realistic in the case of linear waves. In this paper we present a new method to compute the wave envelope providing more re...

Wave groups can be detected and studied by using the wave envelope. So far, the method used to compute the wave envelope employs the Riesz transform. However, such a technique always produces symmetric envelopes, which is only realistic in the case of linear waves. In this paper we present a new method to compute the wave envelope providing more re...

This paper proposes a regression Genetic Fuzzy System (GFS, FRULER) for a problem of sea wave parameters estimation from neighbor buoys, with application on wave energy systems. FRULER is a recently proposed, three-staged algorithm that combines an instance selection method for regression, a multigranularity fuzzy discretization of the input variab...

Location, dispersion, and asymmetry variability of the probability distribution of the maximum wave height from a set of N individual wave heights are examined in terms of the spectral peakedness and the duration of the sea states through the use of robust statistical parameters. The capability of various empirical and theoretical models to reprodu...

Wave statistical properties and occurrence of extreme and rogue waves in crossing sea states are investigated. Compared to previous studies a more extensive set of crossing sea states are investigated, both with respect to spectral shape of the individual wave systems and with respect to the crossing angle and separation in peak frequency of the tw...

This study comprises the analysis and the interpretation of the coherent and the noncoherent parts of a coherent-on-receive microwave radar at grazing incidence conditions. The Doppler measurement is an extension of standard civil marine radar technology. While intensity images require interpretation based on understanding the underlying imaging me...

The properties of directional distributions in ocean wave spectra are studied, with an emphasis on sea states with bimodal directional distributions in the high-frequency tails of single-peaked wave systems. A peak-splitting tendency has been a challenge in the interpretation of results from some data-adaptive estimation methods. After a survey of...

In this work, we describe an approach that allows for optimizing the structure of a smart grid (SG) with renewable energy (RE) generation against abnormal conditions (imbalances between generation and consumption, overloads or failures arising from the inherent SG complexity) by combining the complex network (CN) and evolutionary algorithm (EA) con...

We have employed laboratory and numerical experiments in order to investigate propagation of waves in both long and short-crested wave fields in deep water. For long-crested waves with steepness, ϵ = kcac = 0.1 (a fairly extreme case), reliable prediction can be performed with the modified nonlinear Schrödinger equation up to about 40 characteristi...

Using a nonlinear evolution equation we examine the dependence of the dispersion of directional surface gravity waves on the Benjamin–Feir index (BFI) and crest length. A parameter for describing the deviation between the dispersion of simulated waves and the theoretical linear dispersion relation is proposed. We find that for short crests the magn...

The paper discusses the development of a frequency dependent directional spread from an initial condition of frequency-independence. The study applies basin directional measurements from the Maritime Research Institute Netherlands (MARIN), simulated data from a nonlinear wave equation, and field measurements from the Ekofisk field. The basin experi...

Wind-generated wave energy is a renewable energy source that exhibits a huge potential for sustainable growth. The design and deployment of wave energy converters at a given location require the prediction of the amount of available wave energy flux. This and other wave parameters can be estimated by means of Computational Intelligence techniques (...

Significant wave height (H s) is a basic parameter in wave characterization, important for different problems in marine activities such as the design and management of vessels, marine structures, and wave energy converters. H s is usually estimated using in-situ sensors, mainly buoys, that record time series of wave elevation information. In this p...

Since the 1980s, several methodologies have been developed to measure ocean surface wind, waves, and currents using standard marine radars operating at X-band. Today, marine radars are often used operationally to measure the spectral quantities of ocean surface waves. They also have shown to be very useful to measure surface winds and currents as w...

We discuss the crossing sea state and the probability of rogue waves during the accident of the tanker Prestige on 13 November 2002. We present newly computed hindcast spectra for every hour during that day at nearby locations, showing the development of a bimodal sea state with two wave systems crossing at nearly right angle. We employ four differ...

Wave parameters computed from time series measured by buoys (significant wave height Hs, mean wave period, etc.) play a key role in coastal engineering and in the design and operation of wave energy converters. Storms or navigation accidents can make measuring buoys break down, leading to missing data gaps. In this paper we tackle the problem of lo...

In this paper we propose to apply the Support Vector Regression (SVR) methodology to significant wave height estimation using the shadowing effect, that is visible on the X-band marine radar images of the sea surface due to the presence of high waves. One of the main problems of using sea clutter images is that, for a given sea state conditions, th...

Characteristics of the sea state are generally described by statistical parameters. Even though these parameters are known to be limited in describing the actual wave field, they form the basis for many off-shore decisions and safety regulations. Furthermore it is under discussion how accurate these parameters can be measured and how well they agre...

In this paper, high-resolution wave, current and water depth fields derived by marine X-Band radar are presented for a coastal region of extreme tidal currents in the presence of inhomogeneous bathymetry at the south coast of New Zealand's North Island. The current and water depth information for the presented location covers an area of approximate...

With the recent advancement of spatial measurements of ocean waves, we are clearly facing new challenges regarding how to handle an expanded new data system when it becomes widely available. In this paper we wish to present a preliminary attempt at confronting these prospects. Because the data is still very limited at present and also conceptually...

Linear wave theory is widely used to model for instance response of ocean structures and ships to water surface gravity waves and assumes that the water surface can be modeled as a linear superposition of regular waves satisfying the linear dispersion relation. The linear dispersion relation is often taken for granted for the interpretation of wave...

In this paper, high-resolution wave, current and water depth fields derived by marine X-Band radar are presented for a coastal region of extreme tidal currents in the presence of inhomogeneous bathymetry at the south coast of New Zealand’s North Island. The current and water depth information for the presented location covers an area of approximate...

This work studies wave groupiness properties in the spatiotemporal domain of wind-generated waves. For that purpose, analysis of temporal sequences of X-band radar images of the sea surface acquired at grazing incidence conditions is carrying out. The results presented in this work are based on the estimation of the local and instantaneous envelope...

This work deals with the use of conventionalX-band marine radars to characterize sea state information. Thus, those radar systems are able to scan the sea surface in the spatio-temporal domain by acquiring temporal sequences of radar images of the ocean. The paper describes the different algorithms to obtain the estimation of the wave spectra from...

The linear dispersion relation for water surface waves is often taken for granted for the interpretation of wave measurements. High-resolution spatiotemporal measurements suitable for direct validation of the linear dispersion relation are on the other hand rarely available. While the imaging of the ocean surface with nautical radar does provide th...

Polarimetric calibration is essential in order to achieve an accurate image interpretation and should be the first step to carry out once we get the full polarimetric data. Hence, a polarimetric calibration tool based on the algorithm proposed by Quegan has been developed and analyzed with data coming from TerraSAR-X and INTASAR RIX prototype. The...

The wave and current monitoring system WaMoS II is a remote sensing system based on a nautical X-Band radar generally used for navigation and ship traffic control. It has been used in recent years to monitor sea state information from moored platforms, coastal sites and moving vessels. The nautical radar can scan the sea surface over a large area (...

One of the most relevant parameters to characterize the severity of ocean waves is the significant wave height (H s ). The estimate of H s from remotely sensed data acquired by non-coherent X-band marine radars is a problem not completely solved nowadays. A method commonly used in the literature (standard method) uses the square root of the signal-...

It is well known that ocean gravity waves form wave groups. These groups are observed as sequences of high waves with nearly equal periods, or wavelengths. Wave groups are often responsible for serious damages to marine systems (i.e., ships, off and onshore structures, etc.) when the period of the individual waves in the group are close to the reso...

The linear dispersion relation for water surface waves is often taken for granted for the interpretation of wave measurements. High-resolution spatiotemporal measurements suitable for direct validation of the linear dispersion relation are on the other hand rarely available. While the imaging of the ocean surface with nautical radar does provide t...

For moderate and high speed values of the sea surface current, an aliasing phenomenon, due to an under-sampling in the time-domain, can strongly affect the reconstruction of the sea surface elevation derived from X-band radar images. Here, we propose a de-aliasing strategy that exploits the physical information provided by the dispersion law for gr...

A novel method for detecting ships in marine envi- ronments is presented in this paper. For this purpose, the infor- mation contained in the marine images obtained by a measuring and monitoring marine system is used. The ship detection is done by multilayer perceptrons (MLPs). In the first approach, the MLP processes the information extracted from...

This study presents a novel way for detecting ships in sea clutter. For this purpose, the information contained in the Radar images obtained by an incoherent X-band maritime Radar is used. The ship detection is solved by feedforward artificial neural networks, such as the multilayer perceptrons (MLPs). In a first approach, the MLP processes the inf...

The aim of this work is to present an approach to describe complex sea states including the ones consisting of superpositions of swell and wind sea components, using a marine radar in X-band as a remote sensing technique. In the present article, the inversion method to obtain the spectral representation of the wave fields is described. The method i...

The existence of clutter in maritime radars deteriorates the estimation of some physical parameters of the objects detected over the sea surface. For that reason, maritime radars should incorporate efficient clutter reduction techniques. Due to the intrinsic nonlinear dynamic of sea clutter, nonlinear signal processing is needed, what can be achiev...

Application of mean-shift filtering for speckle noise reduction in SAR images is proposed, as a pre-processing stage in a problem of ship wakes detection. An automatic detection algorithm based on normalized locally Radon transform is used. The algorithm extracts peaks in transform space with a locally adaptive threshold due to variations of sea cl...

This work presents the estimation of wave field properties derived from X-band marine radar measurements taken close to coastal locations, where the wave fields are affected by the finite water depth conditions. The work is focused on the detection of individual waves and their related characteristics, such as the estimation of the local and instan...

This work deals with the question of sea state monitoring using marine X-band radar images and focuses its attention on the problem of sea depth estimation. We present and discuss a technique to estimate bathymetry by exploiting the dispersion relation for surface gravity waves. This estimation technique is based on the correlation between the meas...

The detection of Gaussian signals with an unknown correlation coefficient rho_s is considered. Solutions based on neural networks (NNs) are studied, and a strategy for designing committee machines in a composite hypothesis test is proposed. A single multilayer perceptron (MLP) has been trained with rho_s uniformly varying in [0,...

In radio measurement systems, the backscatter from what is not a target, i.e. the clutter, is usually not desired. So, these systems try to incorporate clutter reduction techniques as efficient as possible. In this way, different signal processing techniques can be used. The case of study presented in this paper shows how to reduce the level of sea...

The presence of sea clutter in marine radar signals is sometimes not desired. So, efficient radar signal processing techniques are needed to reduce it. In this way, nonlinear signal processing techniques based on neural networks (NNs) are used in the proposed clutter reduction system. The developed experiments show promising results characterized b...

This work presents a method to filter sea clutter features for radar images acquired from ordinary marine radar sensors, which are incoherent radars working in X-band and horizontal polarization. The proposed method considers short temporal sequences of consecutive sea clutter images. This method is based on the acquired experience about the spectr...

This work analyses the spectral structure of the sea clutter obtained from temporal sequences of radar images of the sea surface. The images were acquired by ordinary marine radars, which work in X-band and horizontal polarization. The study analyses the different contributions to the sea clutter spectrum due to those phenomena, such as ocean waves...

A multilayer perceptron (MLP) based detector is proposed for approximating the average likelihood ratio (ALR) detector in composite hypothesis-testing problems. The case of detecting colored gaussian targets with Gaussian autocorrelation function (ACF) and unknown one-lag correlation coefficient (rhos), in colored Gaussian interference with Gaussia...

Multilayer perceptron (MLP) based detectors are proposed for detecting Gaussian signals with unknown correlation coefficient (rhos) in additive white Gaussian noise. After proving the low robustness of the likelihood ratio (LR) based detector with respect to rhos, the average likelihood ratio(ALR) based detector assuming a uniform distribution of r...

This work uses ordinary X-band marine radars to extract directional wave spectra and their related sea state parameters, as well as speed and direction of ocean surface currents, including tidal information. The used method analyzes the structure in frequency and wave number vector of the image spectra derived from of temporal sequences of marine r...

This work analyses the structure of the different contributions to the image spectrum derived by the three-dimensional Fourier decomposition of sea clutter time series measured by ordinary X-band marine radars. The goal of this investigation is to derive a method to estimate the significant wave height of the ocean wave fields imaged by the radar....

Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal

This paper presents the remote sensing techniques of measuring sea states, currents and bathymetry by using an X-band nautical radar. It briefly describes the fundamental methods to infer sea state information (e.g. ocean wave and current parameters) from nautical radar imagery. In addition, this work describes in detail the performance of the Wave...

The detection of gaussian signals with unknown correlation coefficient, rho_s, is considered. A strategy for designing mixture of experts in composite hypothesis test is proposed. It is based on designing a single multi-layer perceptron (MLP) trained with rho_s varying uniformly in [0,1] to approximate the average likelihood rat...

The basis functions that are most commonly used in the method of moments (MoM) for the simulation of rough surface scattering have a small support in terms of the wavelength. Complementary, the density of points per wavelength in the surface mesh has to be high enough to guarantee a good accuracy and this implies a computational effort which can of...

The Integral Equation Model (IEM) was developed originally by Fung and Pan (1986). The assumptions inherent to the model were amended in later publications but there were several important points that remained unclear and that propagated across all subsequent versions of the model. One of the authors of this paper proposed an improved IEM, called I...

A neural network (NN) based detector is proposed for approximat- ing the ALR detector in composite hypothesis-testing problems. The case of detecting gaussian targets with gaussian ACF and un- known one-lag correlation coefficient, ρs, in AWGN is considered. After proving the dependence of the simple hypothesis-testing prob- lem LR detector on the...

For more than one decade, the scientific developments carried out with spaceborne synthetic aperture radar (SAR) have demonstrated that SAR is a reliable remote sensing technique to analyze wave fields on the open ocean. In their so-called image mode, these SAR systems, such the Advanced SAR (ASAR) ENVISAT, are able to scan ocean areas of 100 × 100...

This work compares the spectral analysis of ocean wave fields performed from nautical radar and waverider buoy measurements. The data were taken by a radar station located in the northern coast of Spain and by a buoy that was moored close to the area covered by the radar for its calibration. In this area the sea states are mainly dominated by the p...

This work investigates the capabilities of spaceborne SAR to extract information on areas close to coastal locations, where the incoming wave fields show strong spatial inhomogeneities. For this purpose, ERS-2 SAR and ENVISAT ASAR images of the North Sea and the Bay of Biscay are used to study the ocean waves in shallow waters under different clima...

In recent years, new remote sensing techniques have been developed to measure two-dimensional (2-D) sea surface elevation fields. The availability of these data has led to the necessity to extend the classical analysis methods for one-dimensional (1-D) buoy time series to two dimensions. This paper is concerned with the derivation of group paramete...