Universitat Politecnica De Catalunya Research Articles

An Experimental and Numerical Study of the Load Distribution Effect on Composite Slab Shear Resistance

The design codes prescribe “a close simulation” of the uniformly distributed loads for bending tests, since, applying an ideal uniform load on the slab surface, is not technically as simple as applying concentrated loads by spreader beams. The 4-point bending test used in both standard methods m-k and PCM to determine the shear resistance of composite slabs is currently the most conventional loading arrangement. This article presents the comparison between the 4-point bending and uniform load results, obtained from both experimental tests and numerical simulations. Two groups of specimens, made with a common trapezoidal steel profile and concrete, including short and long spans, have been tested under the two loading setups. The numerical analysis of these slabs has been carried out through modelling the realistic interaction of steel and concrete. For the 4-point bending simulation, predefined vertical cracks are modelled representing the real crack inducers, whereas, for the uniform load case, the Willam-Warnke model is used. Both the experimental and the numerical results indicated that the 4-point bending test provides higher shear strength than uniform load. The experimental part was conducted by LERMA (Universitat Politecnica de Catalunya – BarcelonaTech) in collaboration with AdMaS-BUT at Brno University of Technology. The 3D FEM of composite slabs has been made through ANSYS software.

On Teaching Digital Control Systems in a Generic Engineering Degree

Abstract In this work, the subject of digital control taught in a generic engineering degree is described. In particular, the contents of the course, the experimental environment and the interactive tools used in teaching are discussed. This work collects the teaching experience obtained during the past twenty years by the teaching team of this subject at the Barcelona School of Industrial Engineering of the Universitat Politecnica de Catalunya.

Calibration of Raman Lidar Water Vapor Mixing Ratio Measurements Using Zenithal Measurements of Diffuse Sunlight and a Radiative Transfer Model

Among the different techniques available for measuring the atmospheric water vapor content, Raman lidars stand out as accurate instruments providing detailed profiles with high temporal and altitude resolution. Their principle is based on obtaining the range-resolved ratio of the lidar signals corresponding to Raman returns from water vapor and nitrogen molecules, which is proportional to the water vapor mixing ratio. To do this, it is necessary to determine a calibration factor, specific of each lidar instrument. A method for obtaining this parameter, based on zenith measurements of diffuse sunlight, on Raman scattering models and on simulations, using a radiative transfer model, to estimate sky radiances at the wavelengths of interest, has been applied to the lidar system of Universitat Politecnica de Catalunya (UPC; Technical University of Catalonia, Barcelona, Spain). A set of calibrations, performed between 2016 and 2017, has permitted assessing the calibration procedure and analyzing the stability of the calibration factor in the UPC instrument. Results show that although the calibration factor can remain stable for long periods of time, it can suffer sudden variations that make indispensable to implement a convenient and reliable procedure to perform regular calibrations. We show that the method, which can be applied to any lidar with water vapor and nitrogen Raman channels, can completely dispense with radiosonde data. The calibration method is validated by comparison with simultaneous radiosonde water vapor measurements. Limitations of radiosondes for validating—and eventually calibrating—water vapor Raman lidars have been revealed.

Impact of Wind-Induced Scatterers Motion on GB-SAR Imaging

Ground-based synthetic aperture radar (GB-SAR) sensors represent a cost-effective solution for change detection and ground displacement assessment of small-scale areas in real-time early warning applications. GB-SAR systems based on stepped linear frequency modulated continuous wave signals have led to several improvements such as a significant reduction of the acquisition time. Nevertheless, the acquisition time is still long enough to force a degradation of the quality of the reconstructed images because of possible short-term variable reflectivity of the scenario. This reduction of the quality may degrade the differential interferometric detection process. In scenarios where interesting targets are surrounded by vegetation, this is normally related to atmospheric conditions, in particular, the wind. The present paper characterizes the effect of the short-term variable reflectivity in the GB-SAR image reconstruction and evaluates its equivalent blurring effect, the decorrelation introduced in the SAR images, and the degradation of the extracted parameters. In order to validate the results, the study assesses different GB-SAR images obtained with the RISKSAR-X sensor, which has been developed by the Universitat Politecnica de Catalunya.

Empirical forecast of quiet time ionospheric Total Electron Content maps over Europe

An accurate forecast of the atmospheric Total Electron Content (TEC) is helpful to investigate space weather influences on the ionosphere and technical applications like satellite-receiver radio links. The purpose of this work is to compare four empirical methods for a 24-h forecast of vertical TEC maps over Europe under geomagnetically quiet conditions.TEC map data are obtained from the Space Weather Application Center Ionosphere (SWACI) and the Universitat Politècnica de Catalunya (UPC). The time-series methods Standard Persistence Model (SPM), a 27 day median model (MediMod) and a Fourier Series Expansion are compared to maps for the entire year of 2015. As a representative of the climatological coefficient models the forecast performance of the Global Neustrelitz TEC model (NTCM-GL) is also investigated. Time periods of magnetic storms, which are identified with the Dst index, are excluded from the validation.By calculating the TEC values with the most recent maps, the time-series methods perform slightly better than the coefficient model NTCM-GL. The benefit of NTCM-GL is its independence on observational TEC data. Amongst the time-series methods mentioned, MediMod delivers the best overall performance regarding accuracy and data gap handling. Quiet-time SWACI maps can be forecasted accurately and in real-time by the MediMod time-series approach.

Comparison of methods for H*(10) calculation from measured LaBr3(Ce) detector spectra

The Universitat Politecnica de Catalunya (UPC) and the Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT) have evaluated methods based on stripping, conversion coefficients and Maximum Likelihood Estimation using Expectation Maximization (ML-EM) in calculating the H*(10) rates from photon pulse-height spectra acquired with a spectrometric LaBr3(Ce)(1.5″ × 1.5″) detector. There is a good agreement between results of the different H*(10) rate calculation methods using the spectra measured at the UPC secondary standard calibration laboratory in Barcelona. From the outdoor study at ESMERALDA station in Madrid, it can be concluded that the analysed methods provide results quite similar to those obtained with the reference RSS ionization chamber. In addition, the spectrometric detectors can also facilitate radionuclide identification.

Initial Evaluation of SAR Capabilities in UAV Multicopter Platforms

Airborne synthetic aperture radar (SAR) sensors have been commonly used during the last decades to monitor different phenomena in medium-scale areas of observation, such as object detection and characterization or topographic mapping. The use of unmanned aerial vehicles (UAVs) is a cost-effective solution that offers higher operational flexibility than airborne systems to monitor these types of scenarios. The Universitat Politecnica de Catalunya has developed the first fully polarimetric SAR system at X-band integrated into a small UAV multicopter platform (UAV MP). The sensor, called AiR-based remote sensing, has been integrated into the platform overcoming restrictions of weight, space, robustness, and power consumption. To demonstrate the validity of the developed system, some measurement campaigns have been conducted in the outskirts of Barcelona, Spain.

How do Machine Learning, Robotic Process Automation, and Blockchains Affect the Human Factor in Business Process Management?

This paper summarizes a panel discussion at the 15th International Conference on Business Process Management. The panel discussed to what extent the emergence of recent technologies including machine learning, robotic process automation, and blockchain will reduce the human factor in business process management. The panel discussion took place on 14 September, 2017, at the Universitat Politecnica de Catalunya in Barcelona, Spain. Jan Mendling served as a chair; Gero Decker, Richard Hull, Hajo Reijers, and Ingo Weber participated as panelists. The discussions emphasized the impact of emerging technologies at the task level and the coordination level. The major challenges that the panel identified relate to employment, technology acceptance, ethics, customer experience, job design, social integration, and regulation.

<uri>Jutge.org</uri>: Characteristics and Experiences

Jutge.org is an open educational online programming judge designed for students and instructors, featuring a repository of problems that is well organized by courses, topics, and difficulty. Internally, Jutge.org uses a secure and efficient architecture and integrates modern verification techniques, formal methods, static code analysis, and data mining. Jutge.org has exhaustively been used during the last decade at the Universitat Politecnica de Catalunya to strengthen the learning-by-doing approach in several courses. This paper presents the main characteristics of Jutge.org and shows its use and impact on a wide range of courses covering basic programming, data structures, algorithms, artificial intelligence, functional programming, and circuit design.

3rd International Conference on Energy Materials and Environment Engineering

PrefaceThe 2017 3rd International Conference on Energy Materials and Environment Engineering (ICEMEE 2017) was successfully held from March 10-12, 2017 in Bangkok, Thailand. The conference addressed recent development in Energy Materials & Environment Engineering and the relevant applications. The technical program consisted of 4 international keynote speakers, 19 invited speakers, 30 oral presentations, and a poster session with more that 70 posters.This volume of IOP Conference Series: Earth and Environmental Science (EES) is a compilation of the accepted papers in ICEMEE2017 and represents important results that were presented in the conference. The electronic submission and handling of the manuscripts via the conference website, including the selection of reviewers and evaluation of manuscripts, were identical to the procedures applied to manuscripts submitted as regular contributions for publication in peer reviewed journals.The organization of this conference and the preparation of proceedings volume would have been impossible without the tremendous efforts and dedication of many individuals. Prof. Sivakumar Manickam oversaw the organization of the Conference. We would like to acknowledge a large team of reviewers for their timely submission of quality reports. Without this support, the conference could not have been successful. We sincerely hope that ICEMEE2017 will serve as an ideal forum for academia, industrial practitioners and government agents.Prof. Sivakumar ManickamUniversity of Nottingham, MalaysiaGeneral Chairman of ICEMEE2017Organizing CommitteesCo-ChairProf. Avi Friedman, McGill University, CanadaProf. SIVAKUMAR MANICKAM, UNIVERSITY OF NOTTINGHAM, MALAYSIAOrganizing CommitteeProf. Dr. Jinlong Zhang, East China University of Science and Technology, ChinaDr. Paolo Beccarelli, The University of Nottingham, UKDr. Azharul karim, Queensland University of Technology, AustraliaA. Prof. Fredy Kurniawan, Institut Teknologi Sepuluh Nopember, INDONESIAA. Prof. Hakan CALISKAN, Usak University, TURKEYProf. Chris Bowen, University of Bath, UKDr. Masa Noguchi, Faculty of Architecture, Building and Planning, AustraliaLecturer. Alper KEREM, Osmaniye Korkut Ata University, TurkeyDr. Xingxing Zhang, University of Nottingham Ningbo, ChinaEr. Uttam Roy, National Institute of Technology Agartala, IndiaDr. Tze Ching Ong, Politeknik Kuching Sarawak, MalaysiaProf. Dr. Jarot S. Suroso, Bina Nusantara University, IndonesiaDr. George Filis, Bournemouth University, UKProf. Dr. Bingqing Wei, University of Delaware, USADr. Nathan Vinod Kumar, National Institute of Oceanography, IndiaDr. Narottam Das, University of Southern Queensland, AustraliaProf. Marcello De Falco, University “Campus Bio-Medico” of Rome, ItalyDr. Lluc Canals Casals, Universitat Politecnica de Catalunya, SpainProf. Alan J Simson, Leeds Beckett University, UKProf. Laurent Ruhlmann, University of Strasbourg, FranceMr. Tochukwu A.S. Ugwoke, Michael Okpara University of Agriculture, NigeriaDr. Ali Mansour LAGOUN, Scientific and Technical Research Center On Physical And Chemical Analyses, CRAPC, Bousmail, AlgeriaAssistant Prof. Abdul Lateef Olanrewaju, Universiti Tunku Abdul Rahman, MalaysiaDr. Diana Iruretagoyena Ferrer, Department of Chemical Engineering, Imperial College London, United KingdomDr. Yanhui Huang, Rensselaer Polytechnic Institute, USAProf. Luigi Fortuna, University of Catania Department of Electrical, ItalyDr. Laura Castro-Santos, Department of Naval and Ocean enxeñaría, SpainDr. Qingbin Song, Macau University of Science and Technology, China

The Influence of ICT on Learning in Graphic Engineering

Abstract As a result of the introduction of the European Higher Education Area, the inclusion of 3D geometric modelling tools of the parametric type in Graphic Engineering requires a new approach to both the theoretical and practical content of the field. This rethinking provides significant improvements in the teaching of spatial geometry, involves new activities both in and outside the classroom, and puts into practice new teaching-learning models. This work addresses the influence on learning of Information and Communications Technology (ICT) in the new study plans for the Graphic Expression engineering degree courses imparted at the Universitat Politecnica de Catalunya·BarcelonaTech, Escola Universitaria d’Enginyeria Tecnica Industrial de Barcelona. The advantages arising from the improvements in model displays and the understanding of problem statements and their solutions mean that time can be saved in theoretical explanations. Theoretical lectures, which have traditionally been regarded as indispensable when teaching systems of representation and methods of two-dimensional drawing, can now be partially replaced by an increasing use of practical sessions in Computer-Aided Design. The results show that the inclusion of ICT leads to a notable improvement in academic results and in student satisfaction with the subject studied.

Heat generation model in the ball-milling process of a tantalum ore

This work focuses on the characterization of heat generation during dry fracture by direct impact of a tantalum ore. Moreover, an attempt was made to quantify the heat energy loss to the environment during the grinding process of a ball mill. The study was carried out using mineral samples from a Spanish mine that were characterized by measuring their density and specific heat. During the experiments, increases of temperature ranging from 5.9 to 7.3 °C after the fracturing process were observed. A numerical model was then applied to calculate temperature distributions through the mill wall. Three possible combinations of heat transfer coefficients were analyzed, from (1) Kapakyulu and Moys, (2) Duda and (3) the heat transfer laboratory of Universitat Politecnica de Catalunya. The models with the coefficients from Kapakyulu and Moys and the heat transfer laboratory of Universitat Politecnica de Catalunya were found to provide results that were in best agreement with the experimental data.

Evaluation of the impact of strategic staff planning in a university using a MILP model

A mathematical model for optimising the strategic staff planning in universities is used to analyse the impact of different personnel and academic policies on the strategic staff plan, considering a preferable staff composition. The personnel policies are evaluated allowing or not the dismissals of permanent workers; the ratio of internal promotion for workers and the personnel budget. The academic policies are tested through the impact of different demand trends. Addressing the specificities of the university, the optimisation model considers not only economic criteria, i.e., personnel costs, but also other factors related to the fulfilment of the required service level and the achievement of a preferable workforce composition. Several computational scenarios are used, based on real data from the Universitat Politecnica de Catalunya (Barcelona, Spain). The results show the adjustment to the preferable workforce composition through the available mechanisms (dismissals, hiring and internal promotions). [Received 12 June 2015; Revised 24 November 2015; Revised 24 July 2016; Accepted 7 December 2016]

Editorial Issue 28.1

This issue contains five papers. In the first paper, Angel Zaldivar Pino, Manuel Gonzalez Bedia, and Francisco J. Seron, from Universidad Zaragoza, Spain, present a simulation framework in which the agents are endowed with a sensing device, an oscillator network as controller, and actuators to interact with the environment. The perception device is designed as an optic array emulating the principles of the animal retina, which assimilates stimuli resembling optic flow to be captured from the environment. The controller modulates informational variables to action variables in a sensory motor flow. Their approach is based on the Kuramoto model that describes mathematically a network of coupled phase oscillators and the use of evolutionary algorithms, which is proved to be capable of synthesizing minimal synchronization strategies based on the dynamical coupling between agents and environment. In the second paper, Congkun Chen, Yun Sheng, Fang Li, Guixu Zhang, from East China Normal University, Shanghai, China, and Hassan Ugail, from University of Bradford, UK, propose an extension of the use of the partial differential equation (PDE) method to head visualization with CT data and show how the two primary medical visualization means, surface reconstruction, and volume rendering can be integrated into one single framework through PDEs. Their scheme first performs head segmentation from CT slices using a variational approach; with the extracted boundary conditions, head surface reconstruction is then executed. Since only a few slices are used, their method can perform head surface reconstruction more efficiently in both computational time and storage cost than the widely used marching cubes algorithm. By elaborately introducing a third parameter ω to the PDE method, a solid head can be created, based on which the head volume is subsequently rendered with 3-D texture mapping. In the third paper, Francis Laclé, Utrecht University, the Netherlands, and Nicolas Pronost, Université Claude Bernard, Lyon, France, focus on combining, by a controllable enhancement process, a functional and biomechanical model of musculotendon units with its high-resolution geometrical counterpart. The method was developed in order to be invariant to spatial and polygonal configurations and to be scalable in both longitudinal and latitudinal directions. Results with 48 musculotendon units for the lower body show a drop of 84% with respect to the number of vertices when compared to the high-resolution model, while maintaining the functional information. A real-time simulation experiment resulted in a runtime of 135 Hz. Sergio Orts-Escolano, from University of Alicante, Spain, Johannes Bastiaan Boom, Xin Xin Ning, Steven McDonagh, Peter Sandilands, and Robert B. Fisher, from University of Edinburgh, UK, propose in the fourth paper, the first hybrid CPU-GPU based method for estimating a point light source position in a scene recorded by an RGB-D camera. The image and depth information from the Kinect is enough to estimate a light position in a scene, which allows for the rendering of synthetic objects into a scene that appear realistic enough for augmented reality purposes. This method does not require a light probe or other physical device. To make this method suitable for augmented reality, the authors developed a hybrid implementation that performs light estimation in less than 1 s. By rendering synthetic objects into the recorded scene, they illustrate that this accuracy is good enough for the rendered objects to look realistic. Finally, Jorge Eduardo Ramirez Flores and Antonio Susin Sanchez, from Universitat Politecnica de Catalunya, Barcelona, Spain, present an approach based on mesh segmentation for skinning and skeleton-driven computer animation. They propose a novel and fast method, based in watershed segmentation to deal with characters in T-Pose and arbitrary poses; they also introduce a simple weight assign algorithm based in the rigid skinning obtained with the segmentation algorithm for the linear blend skinning (LBS) deformation method. They ultimately propose a modified version of the LBS that avoids the loss of volume in twist rotations using the segmentation stage output values.

Perception of the acquisition of generic competences in engineering degrees

The aim of this paper is to analyze what generic competencies at the Universitat Politecnica de Catalunya (UPC BarcelonaTech) are most evaluated by the teaching staff belonging to the first curricular block of industrial engineering degree courses at the Barcelona Escola Universitaria d’Enginyeria Tecnica Industrial, and also to relate these competencies to the assessment tools and the types of session most frequently used in the evaluation of the said competencies. Furthermore, it is intended to determine the level of acquisition of the generic competencies (related to their profession) as perceived by the students themselves during their course of study and their completion of the Final Year Degree Project (Project Trabajo Final de Grado—TFG). To that end, a group of 140 university teachers and a population of 145 students were each the object of an anonymous online survey while they were engaged on the Final Year Degree Project (TFG). The results of this survey show that the competencies most evaluated by the university teaching staff, in order of importance, are as follows: autonomous learning, the effective use of information resources, teamwork, and good oral and written communication, while the most frequently used tools of assessment are the rubrics. Autonomous learning is the generic competence perceived by the students as being the one most acquired during their completion of the TFG.

3Cat-2—An Experimental Nanosatellite for GNSS-R Earth Observation: Mission Concept and Analysis

Global navigation satellite system reflectometry is a multistatic radar using navigation signals as signals of opportunity. It provides wide-swath and improved spatiotemporal sampling over current space-borne missions. The lack of experimental datasets from space covering signals from multiple constellations (GPS, GLONASS, Galileo, and Beidou) at dual-band (L1 and L2) and dual-polarization (right- and left-hand circular polarization), over the ocean, land, and cryosphere remains a bottleneck to further develop these techniques. 3Cat-2 is a 6-unit (3 × 2 elementary blocks of 10 × 10 × 10 cm3) CubeSat mission designed and implemented at the Universitat Politecnica de Catalunya-BarcelonaTech to explore fundamental issues toward an improvement in the understanding of the bistatic scattering properties of different targets. Since geolocalization of the specific reflection points is determined by the geometry only, a moderate pointing accuracy is only required to correct the antenna pattern in scatterometry measurements. This paper describes the mission analysis and the current status of the assembly, integration, and verification activities of both the engineering model and the flight model performed at Universitat Politecnica de Catalunya NanoSatLab premises. 3Cat-2 launch is foreseen for the second quarter of 2016 into a Sun-Synchronous orbit of 510-km height.

From field experiments to salinity products: a tribute to the contributions of Jordi Font to the SMOS mission

This article summarizes some of the activities in which Jordi Font, research professor and head of the Department of Physical and Technological Oceanography, Institut de Ciencies del Mar (CSIC, Spanish National Research Council) in Barcelona, has been involved as co-Principal Investigator for Ocean Salinity of the European Space Agency Soil Moisture and Ocean Salinity (SMOS) Earth Explorer Mission from the perspective of the Remote Sensing Lab at the Universitat Politecnica de Catalunya. We have probably left out some of his many contributions to salinity remote sensing, but we hope that this review will give an idea of the importance of his work. We focus on the following issues: 1) the new accurate measurements of the sea water dielectric constant, 2) the WISE and EuroSTARRS field experiments that helped to define the geophysical model function relating brightness temperature to sea state, 3) the FROG 2003 field experiment that helped to understand the emission of sea foam, 4) GNSS-R techniques for improving sea surface salinity retrieval, 5) instrument characterization campaigns, and 6) the operational implementation of the Processing Centre of Levels 3 and 4 at the SMOS Barcelona Expert Centre.

Experimental data and CFD performance for CO2 cloud dispersion analysis

Dispersion of hazardous gas releases represents a major threat to health and to the environment; therefore, the prediction of the dispersion features raises great interest. In recent years, with the increase in computational capacity, the interest in Computational Fluid Dynamics (CFD) tools to evaluate dispersion analysis has increased. With the growing use of CFD tools to perform dispersion analysis in different scenarios, it is imperative to amplify the availability of experimental data in order to allow validations studies to contribute to understanding the real capacity of CFD tools to properly represent real cases. The second stage of the field tests conducted by a joint venture between the University of São Paulo and the Universitat Politecnica de Catalunya was established to investigate the performance of CFD tools when analyzing cloud dispersion of hazardous substances by means of ad-hoc experimentation. The experiments consisted of CO2 clouds formation and dispersion tracking of releases of up to 0.85 kg s−1 of about 40 s of duration in a 600-m2discharge area. We provide a description of the tests and the main results of the simulation using the FLACS software; the peak concentrations for 51 sensors placed at the dispersion cloud path are provided here and compared with CFD simulations. In general terms, the CFD simulator presented good performance; all the statistical performance measures were well within the acceptable range. However, the simulator performance presented sensitivity to the wind profile, especially when cross wind occurs.

Mathematical modelling in engineering: an alternative way to teach Linear Algebra

ABSTRACTTechnological advances require that basic science courses for engineering, including Linear Algebra, emphasize the development of mathematical strengths associated with modelling and interpretation of results, which are not limited only to calculus abilities. Based on this consideration, we have proposed a project-based learning, giving a dynamic classroom approach in which students modelled real-world problems and turn gain a deeper knowledge of the Linear Algebra subject. Considering that most students are digital natives, we use the e-portfolio as a tool of communication between students and teachers, besides being a good place making the work visible. In this article, we present an overview of the design and implementation of a project-based learning for a Linear Algebra course taught during the 2014–2015 at the ‘ETSEIB'of Universitat Politècnica de Catalunya (UPC).

Pioneer women in engineering studies: what can we learn from their experiences?

ABSTRACTWomen's access to higher education in Spain began in the last third of the nineteenth century. However, the full incorporation of women into technical studies did not occur until a century later. This article presents the results of research into the access of the first women to do technical studies in Catalonia (northeast Spain). Data have been collected from 11 technical schools belonging to the Universitat Politècnica de Catalunya (UPC) with the aim of understanding the dynamics of the incorporation of women into these schools between 1851 (foundation of the first engineering school in Catalonia) and 1980. Interviews were conducted with 21 pioneer women who completed their technical studies. Their experiences show how technical schools had to adapt, both physically and culturally, to female students. Finally, the current status of female engineers in Catalonia is compared with the situation in other Western countries. Similarities are found that show the relevance of gender as a social structuring force.