Comparison of Non-stationary Sinusoid Estimation Methods Using Reassignment and Derivatives

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Melodic Transcription of Flamenco Singing from Monophonic and Polyphonic Music Recordings

We propose a method for the automatic transcription of flamenco singing from monophonic and polyphonic music recordings. Our transcription system is based on estimating the fundamental frequency (f0) of the singing voice, and follows an iterative strategy for note segmentation and labelling. The generated transcriptions are used in the context of melodic similarity, style classification and pattern detection. In our study, we discuss the difficulties found in transcribing flamenco singing and in evaluating the obtained transcriptions, we analyze the influence of the different steps of the algorithm, and we state the main limitations of our approach and discuss the challenges for future studies

Practical-Oriented Pressure Sensor Placement For Model-Based Leakage Location In Water Distribution Networks

In order to bring remarkable benefits to operation and management of water networks, the analysis of sensed data can be used to locate water leaks using of a model-based methodology. However, the number of sensors installed is usually limited because of budget constraints and hence a strategy for optimizing their number and placement is required. This optimization is tightly coupled to the performance of the real-time model-based leakage diagnosis operation and hence the former should consider the requirements of the latter: (1) high distinguishability among all potential leaks to be detected; and (2) strong robustness in front of model-reality mismatches and other uncertainties. This paper describes a model-based pressure sensor placement optimization technique that focuses on the previous aspects and addresses practicality issues that arise in a real deployment. The technique uses an optimization method based on Genetic Algorithms that, unlike most common approaches in literature, avoids using a binary reasoning process. This increases the information granularity resulting in an improvement of both the leak distinguishability and the method robustness. Moreover, the technique also addresses the practical concerns by deriving an enhanced cost function. Finally, the method is validated in a District Metered Area of the Barcelona water distribution network. Results indicate that a good enough detection accuracy can be achieved with a low number of optimally placed sensors

Anàlisi del comportament a compressió de perfils prims oberts d'acer conformats en fred

Cold-formed thin-walled steel sections are frequently used in pallet rack structures. This type of cross-sections are normally used as a columns and contains perforations uniformly distributed enabling the connection between other structural elements. One of the most typical reasons of failure for pallet-racking systems is the buckling of the uprights. As a consequence, the calculation of ultimate strength under compression is a key factor for a safe structural design. The influence of distortional and local buckling in cold formed thin-walled sections is really important, whereas the influence in hot-rolled sections (IPN, IPE, HEB, etc) is insignificant. The analysis of distortional and local buckling in the upright behaviour is difficult because the classical beam theories cannot handle sectional deformations. As a result, different new methodologies have been developed and finite element analysis has taken an important role. Several recent research activities are focused to study the buckling behaviour of rack sections under pure compression in order to improve the current design codes. Specifically, most of the present research is dealing with the following factors: interaction effects involving the different modes of buckling, initial geometric imperfections in nonlinear finite element analysis, cold-work effects, residual stresses and its influence in the upright ultimate load and the modelling of the perforations. The present doctoral thesis aims to provide new knowledge in some of the previously cited factors. It has been studied the influence of the cold-work effect, residual stresses and the load carrying capacity of cold-formed steel rack columns via nonlinear finite element analysis. Moreover, several experimental tests have been done in order to validate the numerical results. Furthermore, a new software has been developed to calculate the lineal elastic buckling load for any mode of deformation. These values are used for the current design codes and for a new numerical methodology developed. Keywords: Thin-walled section, rack, geometric imperfection, distortional buckling, GBT, residual stresses, cold-work effects, finite element analysisEls perfils prims oberts d'acer conformats en fred són elements estructurals molt utilitzats en les prestatgeries per a emmagatzematge de palets. Aquests perfils són habitualment emprats com a columnes i contenen perforacions uniformement distribuïdes per garantir la connexió entre els diferents elements estructurals. Un dels motius més freqüents de fallida d'aquestes prestatgeries és el col·lapse a compressió dels puntals, i per tant, la determinació de la seva capacitat resistent és un factor clau per assegurar el correcte dimensionament de l'estructura. Els perfils prims conformats en fred, a diferència dels elements estructurals conformats en calent (IPN, IPE, HEB, etc), presenten una sensibilitat molt més elevada als modes de vinclament local i distorsional a causa de les seves característiques geomètriques. La inclusió d'aquests modes complica considerablement el procés de càlcul resistent, ja que les teories clàssiques de barres no tenen en compte les deformacions seccionals. Com a conseqüència, el desenvolupament de nous mètodes i les anàlisis mitjançant elements finits han cobrat una gran importància. Nombroses investigacions actuals tenen com a objectiu l'adquisició de nous coneixements sobre el comportament a compressió dels perfils prims que permetin millorar les normatives de càlcul vigents. Alguns dels aspectes on més s'està aprofundint són: la interacció dels diferents modes de fallida, el tipus d'imperfecció geomètrica a utilitzar en les anàlisis per elements finits, l'efecte de l'enduriment per deformació, l'obtenció de les tensions residuals i la importància d'aquestes en la capacitat resistent del puntal i la caracterització de les perforacions en els diferents mètodes de càlcul. La present tesi doctoral pretén aportar nous coneixements en alguns dels factors prèviament mencionats. S'ha estudiat l'efecte de l'enduriment per deformació, les tensions residuals i la modelització del problema d'estudi mitjançant el mètode dels elements finits verificant els valors obtinguts amb resultats experimentals sempre que hagi estat possible. També s'ha desenvolupat un programa per calcular càrregues elàstiques de vinclament per a qualsevol tipus de mode de fallida, ja que aquesta informació és necessària pels càlculs utilitzant la normativa i també per alguna de les metodologies de càlcul proposades mitjançant la simulació numèrica. Paraules clau: Perfil prim obert, rack, imperfecció geomètrica, vinclament distorsional, GBT, tensions residuals, enduriment per deformació, anàlisi per elements finits

Analysis of printing parameters for metal additive manufactured parts through Direct Ink Writing process

Direct Ink Writing is an Additive Manufacturing process in which a metal ink is continuously extruded to built-up a green metal part. Therefore, a debinding and sintering process is required to obtain the final metal part. This thermal process produces a shrinkage of the green printed part according to several material and printing parameters. In this paper, the influence of printing process planning on the width of printed rods for a copper ink is analyzed by means of a Design of Experiments procedure to optimize the printing and equipment parameters and characterize the shrinkage after the sintering processPeer ReviewedPostprint (published version

Design of Perforated Industrial Storage Rack Columns for Distortional Buckling

The results of an on-going research program to develop a design procedure for perforated industrial storage rack columns are presented. The design procedure includes the effects of distortional buckling. The types of columns studied include those commonly used in Europe and some that are used in the US. The design procedure is being developed based on finite element studies verified by physical testing. The design procedure involves the use of the current US rack column design approach with an extension to distortional buckling with Finite Strip Method (FSM) solutions and Direct Strength Method (DSM) approaches. The approach originally developed for individual columns is being studied for the behavior of such columns in a rack frame

Experimental study of the compression behavior of mask image projection based on stereolithography manufactured parts

The article presents the results of a series of compression tests on samples manufactured by means of the mask image projection based on stereolithography additive manufacturing technique (MIP-SL). Recent studies demonstrate the orthotropic nature of the MIP-SL materials. A research is initiated by the authors to attempt to predict the degree of anisotropy from the manufacturing parameters of the MIP-SL parts. The article focuses mainly on the development of the experimental compression tests of the first stage of the research. Special attention is paid to the four methods used to obtain the stress-strain curve of the material: strain gages, 2D Digital Image Correlation, extensometer measurements and crosshead displacement measurements. The article shows the advantages and limitations of each method. Finally, the anisotropic behaviour is verified and a testing procedure is set to obtain the constitutive parameters of the MIP-SL tested materialsPeer ReviewedPostprint (published version