David Fidalgo Sanchez - Academia.edu (original) (raw)
Papers by David Fidalgo Sanchez
Universidad Católica de Avila, 2020
International Journal of Production Management and Engineering, 2022
The concept of Servitization has been constantly developing since its outset, but in the last dec... more The concept of Servitization has been constantly developing since its outset, but in the last decade due to the irruption of Industry 4.0, the complexity of the concept and its typologies of value propositions have evolved considerably, opening up endless opportunities. In this sense, the main objective of this research is to show a summary review of the evolution of Servitization since its beginnings and the new typologies that are emerging due to the digitalization that arises through Industry 4.0. For this purpose, a systematic review of the leading databases in the field of services has been conducted. The results of the literature review show the potential of Servitization and the need to understand each reality in order to adapt to new capabilities that help the companies who become service-oriented benefit from major advantages. Ultimately, it can be concluded that, in the short term, Industry 4.0 and its new business models are the key, however, Servitization will continue t...
In this paper we study a one-dimensional model of ferromagnetic nanowire presenting notches. We p... more In this paper we study a one-dimensional model of ferromagnetic nanowire presenting notches. We prove the existence of stable wall profiles even under a small applied magnetic field with the walls localized in notches. Moreover, in order to illustrate wall depinning by applied magnetic field, we prove the non-existence of stationary wall profiles in the presence of a large applied magnetic field.
2019 ASEE Annual Conference & Exposition Proceedings
He is pursuing his degree in the Engineering Education Systems and Design program, concurrently w... more He is pursuing his degree in the Engineering Education Systems and Design program, concurrently while pursuing a Master's degree in Engineering. Michael graduated with his B.S. in Mechanical engineering from University of Pittsburgh in April of 2018. His research interest lies in diversity, inclusion and K-12 engineering pedagogy.
Proceedings of Technology and Instrumentation in Particle Physics 2014 — PoS(TIPP2014), 2015
Scalable Computing: Practice and Experience, 2018
The aim of this paper is to present a method based on the Isoefficiency for assessing the scalabi... more The aim of this paper is to present a method based on the Isoefficiency for assessing the scalability in big data environments. The programs word count and sort were implemented and compared in Hadoop and Spark. The results confirm that isoefficiency presented a linear growth as the size of the data sets was increased. It was experimentally confronted that the evaluated frameworks are scalable and a model of the form Y (s) = β X(s)$ where β ≈[0.47-0.85] <1 was obtained. The paper discuss how the scalability in big data is governed by a constant of scalability (β).
Proceedings of the 2nd Wseas International Conference on Biomedical Electronics and Biomedical Informatics, 2009
Protein domain boundary prediction has been essential in identifying protein domains. Artificial ... more Protein domain boundary prediction has been essential in identifying protein domains. Artificial Neural Networks have been used in the prediction of protein domains successfully and have been incorporated in software tools that are widely used. We propose a Feed-forward Artificial Neural Network trained using Bayesian methods. The proposed ANN uses protein residue sequences as inputs and a binary output indicating whether a domain boundary is predicted or not. Training and testing was performed with proteins selected from the SCOP and CATH databases. Preliminary results suggest that the proposed neural networks perform comparably or better than existing neural networks that detect domain boundaries which have been embedded in widely used software tools for the prediction of domain boundaries.
Ic Revista Cientifica De Informacion Y Comunicacion, Jan 12, 2015
Communications in Mathematical Sciences, 2015
We study a model of magnetization switching driven by a spin current: the magnetization reversal ... more We study a model of magnetization switching driven by a spin current: the magnetization reversal can be induced without applying an external magnetic field. We first write our one dimensional model in an adimensionalized form, using a small parameter ε. We then explain the various time and space scales involved in the studied phenomena. Taking into account these scales, we first construct an appropriate numerical scheme, that allows us to recover numerically various results of physical experiments. We then perform a formal asymptotic study as ε tends to 0, using a multiscale approach and asymptotic expansions. We thus obtain approximate limit models that we compare with the original model via numerical simulations.
The European Integrated Project eCoMove (EU FP7) aims to develop cooperative mobility systems and... more The European Integrated Project eCoMove (EU FP7) aims to develop cooperative mobility systems and services that reduce fuel consumption and CO 2-emissions with 20%. The innovations that are developed inside the eCoMove project relate to driving behaviour, trip planning and traffic management & control. As one of the first steps the inefficiencies that occur in the current system have been identified. Each of the use cases and resulting components and applications that are developed in the eCoMove project, targets one or more of the above mentioned inefficiencies. In this way the inefficiencies are used to keep a clear focus on the project goal of reducing CO 2-emissions and unnecessary fuel consumption with 20%.
Mathematics in Industry, 2010
This book comes very close to the reviewers' ideal of what a perfect textbook for an 'introductor... more This book comes very close to the reviewers' ideal of what a perfect textbook for an 'introductory course in the mathematical modeling of population growth should be. The three main sections of the book are: I. Deterministic Models: II. Stochastic Models; and III. Case Studies, and the main theme in all of them is the analysis of fluctuations, deterministic or stochastic, from an equilibrium state. The authors introduce a good, comprehensive set of methods by analyzing a variety of models in which the underlying assumptions are carefully discussed (almost scathingly at times). Invariably, the final results are carefully compared with either expenmental data or numerical simulations and the comparison is used to question once again the various assumptions and derivations used in the model. That the above is done so well, with a remarkably clear and well organized style of writing, makes the book quite singular in the near plethora of "modeling" books available today. But the real feature of the book lies in how well the authors blend the modeling procedure and the mathematical techniques nccdcd to study the model without excesses of biological detail or lengthy calculations and theasrem proving. At the same time, they introduce a healthy scepticism by questior?ing at each step the procedures being used, the assumptions being made, and the estimates being obtained. The reader rapidly begins to feel that hc or she is the investigator or a close observer and not just a member of the audience. The five chapters of Part I, Deterministic Models, are a good compendium of models for single species growth with or without age structure, growth of interacting species, and the effects of spatial heterogeneity. The reader is introduced to difference equations, ordinary differential equations with or without delays, and partial differential equations that model populations with age structure as well as those where growth in time is coupled with spatial dispersion. In almost 211 cases. a local linearlization at an equilibrium point or steady state is performed followed by a stability analysis. Quite often the Fourier transform is effectively used, and it is introduced in a very natural way with a minimum of mathematical obfuscation. Th'e two chapters of Part II, Stochastic Models, parallel. in part, the development in Part I. The differential equation for the probability distribution associated with population size in a birth-death process is clearly developed and a wide range of probabilistic concepts (stationarity. conditional probability, expectation. etc.) are lucidly and briefly explained. The heuristic derivation of the diffusion
IEEE Latin America Transactions, 2011
This paper describes the development of an Advanced Speech Communication System for Deaf People a... more This paper describes the development of an Advanced Speech Communication System for Deaf People and its field evaluation in a real application domain: the renewal of Driver's License. The system is composed of two modules. The first one is a Spanish into Spanish Sign Language (LSE: Lengua de Signos Española) translation module made up of a speech recognizer, a natural language translator (for converting a word sequence into a sequence of signs), and a 3D avatar animation module (for playing back the signs). The second module is a Spoken Spanish generator from sign-writing composed of a visual interface (for specifying a sequence of signs), a language translator (for generating the sequence of words in Spanish), and finally, a text to speech converter. For language translation, the system integrates three technologies: an example-based strategy, a rule-based translation method and a statistical translator. This paper also includes a detailed description of the evaluation carried out in the Local Trafile Office in the city of Toledo (Spain) involving real government employees and deaf people. This evaluation includes objective measurements from the system and subjective information from questionnaires. Finally, the paper reports an analysis of the main problems and a discussion about possible solutions.
2011 Visual Communications and Image Processing (VCIP), 2011
We present an innovative system to encode and transmit textured multi-resolution 3D meshes in a p... more We present an innovative system to encode and transmit textured multi-resolution 3D meshes in a progressive way, with no need to send several texture images, one for each mesh LOD (Level Of Detail). All texture LODs are created from the finest one (associated to the finest mesh), but can be reconstructed progressively from the coarsest thanks to refinement images calculated in the encoding process, and transmitted only if needed. This allows us to adjust the LOD/quality of both 3D mesh and texture according to the rendering power of the device that will display them, and to the network capacity. Additionally, we achieve big savings in data transmission by avoiding altogether texture coordinates, which are generated automatically thanks to an unwrapping system agreed upon by both encoder and decoder.
The Astrophysical Journal, 2009
We report the detection of pulsed γ-rays for PSRs J0631+1036, J0659+1414, J0742-2822, J1420-6048,... more We report the detection of pulsed γ-rays for PSRs J0631+1036, J0659+1414, J0742-2822, J1420-6048, J1509-5850, and J1718-3825 using the Large Area Telescope on board the Fermi Gamma-ray Space Telescope (formerly known as GLAST). Although these six pulsars are diverse in terms of their spin parameters, they share an important feature: their γ-ray light curves are (at least given the current count statistics) single peaked. For two pulsars, there are hints for a double-peaked structure in the light curves. The shapes of the observed light curves of this group of pulsars are discussed in the light of models for which the emission originates from high up in the magnetosphere. The observed phases of the γ-ray light curves are, in general, consistent with those predicted by high-altitude models, although we speculate that the γ-ray emission of PSR J0659+1414, possibly featuring the softest spectrum of all Fermi pulsars coupled with a very low efficiency, arises from relatively low down in the magnetosphere. High-quality radio polarization data are available showing that all but one have a high degree of linear polarization. This allows us to place some constraints on the viewing geometry and aids the comparison of the γ-ray light curves with high-energy beam models.
The Astrophysical Journal, 2009
We report on the first simultaneous observations that cover the optical, X-ray, and high energy g... more We report on the first simultaneous observations that cover the optical, X-ray, and high energy gamma-ray bands of the BL Lac object PKS 2155−304. The gamma-ray bands were observed for 11 days, between 25 August and 6 September 2008 (MJD 54704-54715), jointly with the Fermi Gamma-ray Space Telescope and the H.E.S.S. atmospheric Cherenkov array, providing the first simultaneous MeV-TeV spectral energy distribution (SED) with the new generation of γ-ray telescopes. The ATOM telescope and the RXTE and Swift observatories provided optical and X-ray coverage of the low-energy component over the same time period. The object was close to the lowest archival X-ray and Very High Energy (VHE, > 100 GeV) state, whereas the optical flux was much higher. The light curves show relatively little (∼ 30%) variability overall when compared to past flaring episodes, but we find a clear optical/VHE correlation and evidence for a correlation of the X-rays with the high energy spectral index. Contrary to previous observations in the flaring state, we do not find any correlation between the X-ray and VHE components. Although synchrotron self-Compton models are often invoked to explain the SEDs of BL Lac objects, the most common versions of these models are at odds with the correlated variability we find in the various bands for PKS 2155−304.
The Astrophysical Journal, 2010
We present the first catalog of active galactic nuclei (AGN) detected by the LAT, corresponding t... more We present the first catalog of active galactic nuclei (AGN) detected by the LAT, corresponding to 11 months of data collected in scientific operation mode. The First LAT AGN Catalog (1LAC) includes 671 γ-ray sources located at high Galactic latitudes (|b| > 10 •) that are detected with a test statistic (T S) greater than 25 and associated statistically with AGNs. Some LAT sources are associated with multiple AGNs, and consequently, the catalog includes 709 AGNs, comprising 300 BL Lacertae objects (BL Lacs), 296 flat-spectrum radio quasars (FSRQs), 41 AGNs of other types, and 72 AGNs of unknown type. We also classify the blazars based on their spectral energy distributions (SEDs) as archival radio, optical, and X-ray data permit. In addition to the formal 1LAC sample, we provide AGN associations for 51 low-latitude LAT sources and AGN "affiliations" (unquantified counterpart candidates) for 104 highlatitude LAT sources without AGN associations. The overlap of the 1LAC with existing γ-ray AGN catalogs (LBAS, EGRET, AGILE, Swift, INTEGRAL, TeVCat) is briefly discussed. Various properties-such as γ-ray fluxes and photon power law spectral indices, redshifts, γ-ray luminosities, variability, and archival radio luminosities-and their correlations are presented and discussed for the different blazar classes. We compare the 1LAC results with predictions regarding the γ-ray AGN populations, and we comment on the power of the sample to address the question of the blazar sequence.
Universidad Católica de Avila, 2020
International Journal of Production Management and Engineering, 2022
The concept of Servitization has been constantly developing since its outset, but in the last dec... more The concept of Servitization has been constantly developing since its outset, but in the last decade due to the irruption of Industry 4.0, the complexity of the concept and its typologies of value propositions have evolved considerably, opening up endless opportunities. In this sense, the main objective of this research is to show a summary review of the evolution of Servitization since its beginnings and the new typologies that are emerging due to the digitalization that arises through Industry 4.0. For this purpose, a systematic review of the leading databases in the field of services has been conducted. The results of the literature review show the potential of Servitization and the need to understand each reality in order to adapt to new capabilities that help the companies who become service-oriented benefit from major advantages. Ultimately, it can be concluded that, in the short term, Industry 4.0 and its new business models are the key, however, Servitization will continue t...
In this paper we study a one-dimensional model of ferromagnetic nanowire presenting notches. We p... more In this paper we study a one-dimensional model of ferromagnetic nanowire presenting notches. We prove the existence of stable wall profiles even under a small applied magnetic field with the walls localized in notches. Moreover, in order to illustrate wall depinning by applied magnetic field, we prove the non-existence of stationary wall profiles in the presence of a large applied magnetic field.
2019 ASEE Annual Conference & Exposition Proceedings
He is pursuing his degree in the Engineering Education Systems and Design program, concurrently w... more He is pursuing his degree in the Engineering Education Systems and Design program, concurrently while pursuing a Master's degree in Engineering. Michael graduated with his B.S. in Mechanical engineering from University of Pittsburgh in April of 2018. His research interest lies in diversity, inclusion and K-12 engineering pedagogy.
Proceedings of Technology and Instrumentation in Particle Physics 2014 — PoS(TIPP2014), 2015
Scalable Computing: Practice and Experience, 2018
The aim of this paper is to present a method based on the Isoefficiency for assessing the scalabi... more The aim of this paper is to present a method based on the Isoefficiency for assessing the scalability in big data environments. The programs word count and sort were implemented and compared in Hadoop and Spark. The results confirm that isoefficiency presented a linear growth as the size of the data sets was increased. It was experimentally confronted that the evaluated frameworks are scalable and a model of the form Y (s) = β X(s)$ where β ≈[0.47-0.85] <1 was obtained. The paper discuss how the scalability in big data is governed by a constant of scalability (β).
Proceedings of the 2nd Wseas International Conference on Biomedical Electronics and Biomedical Informatics, 2009
Protein domain boundary prediction has been essential in identifying protein domains. Artificial ... more Protein domain boundary prediction has been essential in identifying protein domains. Artificial Neural Networks have been used in the prediction of protein domains successfully and have been incorporated in software tools that are widely used. We propose a Feed-forward Artificial Neural Network trained using Bayesian methods. The proposed ANN uses protein residue sequences as inputs and a binary output indicating whether a domain boundary is predicted or not. Training and testing was performed with proteins selected from the SCOP and CATH databases. Preliminary results suggest that the proposed neural networks perform comparably or better than existing neural networks that detect domain boundaries which have been embedded in widely used software tools for the prediction of domain boundaries.
Ic Revista Cientifica De Informacion Y Comunicacion, Jan 12, 2015
Communications in Mathematical Sciences, 2015
We study a model of magnetization switching driven by a spin current: the magnetization reversal ... more We study a model of magnetization switching driven by a spin current: the magnetization reversal can be induced without applying an external magnetic field. We first write our one dimensional model in an adimensionalized form, using a small parameter ε. We then explain the various time and space scales involved in the studied phenomena. Taking into account these scales, we first construct an appropriate numerical scheme, that allows us to recover numerically various results of physical experiments. We then perform a formal asymptotic study as ε tends to 0, using a multiscale approach and asymptotic expansions. We thus obtain approximate limit models that we compare with the original model via numerical simulations.
The European Integrated Project eCoMove (EU FP7) aims to develop cooperative mobility systems and... more The European Integrated Project eCoMove (EU FP7) aims to develop cooperative mobility systems and services that reduce fuel consumption and CO 2-emissions with 20%. The innovations that are developed inside the eCoMove project relate to driving behaviour, trip planning and traffic management & control. As one of the first steps the inefficiencies that occur in the current system have been identified. Each of the use cases and resulting components and applications that are developed in the eCoMove project, targets one or more of the above mentioned inefficiencies. In this way the inefficiencies are used to keep a clear focus on the project goal of reducing CO 2-emissions and unnecessary fuel consumption with 20%.
Mathematics in Industry, 2010
This book comes very close to the reviewers' ideal of what a perfect textbook for an 'introductor... more This book comes very close to the reviewers' ideal of what a perfect textbook for an 'introductory course in the mathematical modeling of population growth should be. The three main sections of the book are: I. Deterministic Models: II. Stochastic Models; and III. Case Studies, and the main theme in all of them is the analysis of fluctuations, deterministic or stochastic, from an equilibrium state. The authors introduce a good, comprehensive set of methods by analyzing a variety of models in which the underlying assumptions are carefully discussed (almost scathingly at times). Invariably, the final results are carefully compared with either expenmental data or numerical simulations and the comparison is used to question once again the various assumptions and derivations used in the model. That the above is done so well, with a remarkably clear and well organized style of writing, makes the book quite singular in the near plethora of "modeling" books available today. But the real feature of the book lies in how well the authors blend the modeling procedure and the mathematical techniques nccdcd to study the model without excesses of biological detail or lengthy calculations and theasrem proving. At the same time, they introduce a healthy scepticism by questior?ing at each step the procedures being used, the assumptions being made, and the estimates being obtained. The reader rapidly begins to feel that hc or she is the investigator or a close observer and not just a member of the audience. The five chapters of Part I, Deterministic Models, are a good compendium of models for single species growth with or without age structure, growth of interacting species, and the effects of spatial heterogeneity. The reader is introduced to difference equations, ordinary differential equations with or without delays, and partial differential equations that model populations with age structure as well as those where growth in time is coupled with spatial dispersion. In almost 211 cases. a local linearlization at an equilibrium point or steady state is performed followed by a stability analysis. Quite often the Fourier transform is effectively used, and it is introduced in a very natural way with a minimum of mathematical obfuscation. Th'e two chapters of Part II, Stochastic Models, parallel. in part, the development in Part I. The differential equation for the probability distribution associated with population size in a birth-death process is clearly developed and a wide range of probabilistic concepts (stationarity. conditional probability, expectation. etc.) are lucidly and briefly explained. The heuristic derivation of the diffusion
IEEE Latin America Transactions, 2011
This paper describes the development of an Advanced Speech Communication System for Deaf People a... more This paper describes the development of an Advanced Speech Communication System for Deaf People and its field evaluation in a real application domain: the renewal of Driver's License. The system is composed of two modules. The first one is a Spanish into Spanish Sign Language (LSE: Lengua de Signos Española) translation module made up of a speech recognizer, a natural language translator (for converting a word sequence into a sequence of signs), and a 3D avatar animation module (for playing back the signs). The second module is a Spoken Spanish generator from sign-writing composed of a visual interface (for specifying a sequence of signs), a language translator (for generating the sequence of words in Spanish), and finally, a text to speech converter. For language translation, the system integrates three technologies: an example-based strategy, a rule-based translation method and a statistical translator. This paper also includes a detailed description of the evaluation carried out in the Local Trafile Office in the city of Toledo (Spain) involving real government employees and deaf people. This evaluation includes objective measurements from the system and subjective information from questionnaires. Finally, the paper reports an analysis of the main problems and a discussion about possible solutions.
2011 Visual Communications and Image Processing (VCIP), 2011
We present an innovative system to encode and transmit textured multi-resolution 3D meshes in a p... more We present an innovative system to encode and transmit textured multi-resolution 3D meshes in a progressive way, with no need to send several texture images, one for each mesh LOD (Level Of Detail). All texture LODs are created from the finest one (associated to the finest mesh), but can be reconstructed progressively from the coarsest thanks to refinement images calculated in the encoding process, and transmitted only if needed. This allows us to adjust the LOD/quality of both 3D mesh and texture according to the rendering power of the device that will display them, and to the network capacity. Additionally, we achieve big savings in data transmission by avoiding altogether texture coordinates, which are generated automatically thanks to an unwrapping system agreed upon by both encoder and decoder.
The Astrophysical Journal, 2009
We report the detection of pulsed γ-rays for PSRs J0631+1036, J0659+1414, J0742-2822, J1420-6048,... more We report the detection of pulsed γ-rays for PSRs J0631+1036, J0659+1414, J0742-2822, J1420-6048, J1509-5850, and J1718-3825 using the Large Area Telescope on board the Fermi Gamma-ray Space Telescope (formerly known as GLAST). Although these six pulsars are diverse in terms of their spin parameters, they share an important feature: their γ-ray light curves are (at least given the current count statistics) single peaked. For two pulsars, there are hints for a double-peaked structure in the light curves. The shapes of the observed light curves of this group of pulsars are discussed in the light of models for which the emission originates from high up in the magnetosphere. The observed phases of the γ-ray light curves are, in general, consistent with those predicted by high-altitude models, although we speculate that the γ-ray emission of PSR J0659+1414, possibly featuring the softest spectrum of all Fermi pulsars coupled with a very low efficiency, arises from relatively low down in the magnetosphere. High-quality radio polarization data are available showing that all but one have a high degree of linear polarization. This allows us to place some constraints on the viewing geometry and aids the comparison of the γ-ray light curves with high-energy beam models.
The Astrophysical Journal, 2009
We report on the first simultaneous observations that cover the optical, X-ray, and high energy g... more We report on the first simultaneous observations that cover the optical, X-ray, and high energy gamma-ray bands of the BL Lac object PKS 2155−304. The gamma-ray bands were observed for 11 days, between 25 August and 6 September 2008 (MJD 54704-54715), jointly with the Fermi Gamma-ray Space Telescope and the H.E.S.S. atmospheric Cherenkov array, providing the first simultaneous MeV-TeV spectral energy distribution (SED) with the new generation of γ-ray telescopes. The ATOM telescope and the RXTE and Swift observatories provided optical and X-ray coverage of the low-energy component over the same time period. The object was close to the lowest archival X-ray and Very High Energy (VHE, > 100 GeV) state, whereas the optical flux was much higher. The light curves show relatively little (∼ 30%) variability overall when compared to past flaring episodes, but we find a clear optical/VHE correlation and evidence for a correlation of the X-rays with the high energy spectral index. Contrary to previous observations in the flaring state, we do not find any correlation between the X-ray and VHE components. Although synchrotron self-Compton models are often invoked to explain the SEDs of BL Lac objects, the most common versions of these models are at odds with the correlated variability we find in the various bands for PKS 2155−304.
The Astrophysical Journal, 2010
We present the first catalog of active galactic nuclei (AGN) detected by the LAT, corresponding t... more We present the first catalog of active galactic nuclei (AGN) detected by the LAT, corresponding to 11 months of data collected in scientific operation mode. The First LAT AGN Catalog (1LAC) includes 671 γ-ray sources located at high Galactic latitudes (|b| > 10 •) that are detected with a test statistic (T S) greater than 25 and associated statistically with AGNs. Some LAT sources are associated with multiple AGNs, and consequently, the catalog includes 709 AGNs, comprising 300 BL Lacertae objects (BL Lacs), 296 flat-spectrum radio quasars (FSRQs), 41 AGNs of other types, and 72 AGNs of unknown type. We also classify the blazars based on their spectral energy distributions (SEDs) as archival radio, optical, and X-ray data permit. In addition to the formal 1LAC sample, we provide AGN associations for 51 low-latitude LAT sources and AGN "affiliations" (unquantified counterpart candidates) for 104 highlatitude LAT sources without AGN associations. The overlap of the 1LAC with existing γ-ray AGN catalogs (LBAS, EGRET, AGILE, Swift, INTEGRAL, TeVCat) is briefly discussed. Various properties-such as γ-ray fluxes and photon power law spectral indices, redshifts, γ-ray luminosities, variability, and archival radio luminosities-and their correlations are presented and discussed for the different blazar classes. We compare the 1LAC results with predictions regarding the γ-ray AGN populations, and we comment on the power of the sample to address the question of the blazar sequence.