Universidad Politecnica De Madrid Research Articles

Risk reduction by means of FLEX strategies in pressurized water reactors

One of the key lessons learned from the Fukushima Dai-ichi accident was the importance of the challenge presented by the loss of safety-related systems after a Beyond Design-Basis External Event (BDBEE). In particular, Extended Loss of AC Power (ELAP) or Loss of Ultimate Heat Sink (LUHS) can severely compromise key safety functions associated with core cooling and containment, ultimately leading to reactor core damage. Because of that the so-called Diverse and Flexible Coping Strategies (FLEX) were designed.These aforementioned FLEX strategies are also useful to avoid core damage in sequences due to internal events. Therefore, these FLEX strategies should be incorporated in the Level 1 Probabilistic Safety Assessment (L1PSA) to analyse their impact on core damage frequency (CDF). This work quantifies the impact of FLEX strategies by using a generic model (3 loops, PWR-WEC) developed by the Universidad Politécnica de Madrid (UPM) in collaboration with the Spanish Nuclear Regulatory Body (CSN). As a result, a decrease of the CDF at power for internal events is observed and, therefore, indicates that these FLEX strategies have a positive impact on the plant safety not only for BDBEE but also for other accidental conditions.

A Study on the Distribution of Shear Forces Between Resisting Mechanisms in an RC Element Without Stirrups

This paper explores how the shear force distributes itself among the three main shear resistance mechanisms: shear resistance of the uncracked compressed chord, aggregate interlock, and dowel effect. Today’s dominating shear models, the critical crack theory (Muttoni et al. [1]) and the compression field theory (Collins et al. [2]) maintain that the main shear-resisting mechanism is aggregate interlock, while more recent studies (Marí et al. [3]), maintain that the main resistance mechanism is the shear resistance on the uncracked compression chord.
 In this paper FEM modelling is used to study a test carried out at the Universidad Politécnica de Madrid (UPM) to try to assign the shear force to the different shear mechanisms for different loading steps and elucidate what finally causes the failure of the structure. The results show that as load is increased the relative part of the shear force taken by the uncracked compressed chord increases until finally shear failure is reached when the principal tensile stress in the area located close to the load but towards the support reaches the tensile resistance of concrete, generating a crack that precipitates the failure of the beam.

C‐programming self‐assessment exercises versus final exams: 12 years of experience

AbstractThe new curricula derived from the Bologna process encourage continuous evaluations during the teaching period. This situation causes already depleted teachers to have an additional workload during the course, so the emergence of tools that automatically evaluate this work is necessary. In computer science, the ideal evaluation technique would be to use automatic code evaluators (such as C, Java, C++, etc.). The main objective of this work is to analyze whether the use of C‐coding self‐assessment exercises correlates with an improvement in exam performance. For this purpose, the implementation of self‐assessment exercises on the AulaWeb platform during the last 12 academic years (2010/2011–2021/2022) in a Programming Fundamentals course (Fundamentos de Programación) in an engineering faculty at the Universidad Politécnica de Madrid (UPM) was collected. The main tasks carried out in this research have been: (i) recovery and analysis of the information collected from the AulaWeb platform and (ii) the study of the influence of the self‐assessment exercises on the final grades obtained by the students of the course through correlations. The most important findings are: (a) self‐assessment exercises generate experience and confidence when facing problems (this situation translates into a higher probability of passing the course) and (b) self‐assessment exercises influence the final exams taken at the end of the semester, mainly due to the short time between the end of classes and the exam. Self‐assessment exercises provide valuable information for teachers to monitor the progress of large groups of students during the semester and for students to pass exams.

The UPMQube: An Academic/Educational PocketQube Proposal for the EU2Space Challenge

In the present paper, the UPMQube PocketQube proposal for the EU2Space challenge is described. This proposal has been developed by a group of master’s degree students led by Ph.D. students and professors from the Instituto Universitario de Microgravedad “Ignacio Da Riva” (IDR/UPM) at Universidad Politécnica de Madrid (UPM). PocketQube is a recent new picosatellite concept, which is currently under development. Its reduced size and mass require a significant effort to reduce the characteristic size of the elementary subsystems. One of the subsystems that offers the greatest capacity for improvement is the Attitude Determination and Control Subsystem (ADCS), since most PocketQubes do not usually have one due to lack of space. The most relevant technical aspect of this proposal is the development of a new ADCS which fits the high restrictive size and mass requirements, and it is based on Commercial Off-The-Shelf (COTS) components. This ADCS is composed by: (i) a purely Autonomous Magnetic Controller (AMC) based on magnetorquers and magnetometers on board the spacecraft (S/C platform; (ii) an Attitude Determination System (ADS) based on solar sensors and thermal sensors on board the S/C and an On Ground Attitude Determination Algorithm (for post processing the sensors flight data. The work carried out by Master s degree students is integrated within the academic program of the UPM’s Master in Space Systems as a Case of Study. It also provides an excellent training program for the Ph.D. Assistant Professors included in the proposals Team. The tasks assignments and responsibilities of all members of the Team are fully described in the paper. Additionally, it should be underlined that this proposal is quite well balanced in terms of gender, as 40% of the Team (including the Principal Investigator) are women. This figure is higher than the mean percentage of women present in STEAM Sciences, Technology, Engineering, and Mathematics careers (29% of the workforce, 19% of company board members, 3% industry CEOs). Keywords: UPMQube, PocketQube, MUSE, magnetic ADCS, space engineering challenge

Experimental study on the performance of a hydrofoil using passive water-jet vortex generators

ABSTRACT This paper presents an experimental study of a passive version of the Water-jet vortex generator to reduce the drag force over a NACA 661-012 hydrofoil. The passive blowing used the overpressure zone at the leading edge of the hydrofoil’s lower surface as a source of water jets that create jets on the upper surface of the hydrofoil using the blowing tubes. The experimental tests were carried out in the towing tank in Universidad Politécnica de Madrid (UPM) with a hydrofoil model with a 250-mm long chord at Reynolds numbers of (1.4 105 < Re < 2.8 105). It was found that the passive water-jet vortex-generator reduces the drag force with a slight lift decrease.

Combining technical and business studies at the Universidad Politécnica de Madrid: Analysis of the Double Degree student profile

Double degrees have emerged as an attractive alternative for Spanish university students. The Double Degree in Building and in Business Administration and Management (EDIF-ADE) was a pioneer among the Double Degrees implemented at the Universidad Politécnica de Madrid (UPM) and is currently experiencing a great demand. This study analyses the profile of EDIF-ADE students to understand the keys to this success. Through a survey of first-, second-, third-, and fourth-year students, we examined (1) students’ prior knowledge; (2) motivations and interest areas; (3) educational and occupational expectations; (4) results and knowledge acquired. The results of the study reveal that, although most of the students had no prior knowledge of economics and business, they consider this training as an important element in their future professional development that enhances their employability prospects.

On the satellite attitude determination using simple environmental models and sensor data

Attitude determination represents a fundamental task for most of the spacecrafts. It relies on three basic aspects: 1) sensors selection, 2) relevant environmental conditions estimation, and 3) algorithms that relate the sensor measurements to the expected conditions in the reference frame. Each one has its own impact on the accuracy that the system can achieve. Besides, two factors stand out above the others in terms of accuracy: 1) sensor quality (calibration, range, etc), and 2) precision of the environmental models. The computation of the satellite attitude needs at least two independent measurements (magnetometers, solar sensors...), whit their corresponding simulated measurements in the reference frame. Nevertheless, the number of measurements can be reduced to one if the satellite attitude is constrained. This paper describes a procedure to calculate satellites’ attitude and the main environmental models used (Earth magnetic model, Sun position model, Albedo model), including orbit propagation. This methodology can be extended to measure the performance of a sensor if the satellite attitude can be derived from other measurements and satellite constrains. The methodology is checked with data from the UPMSat-2 mission (launched in September 2020 within the VEGA VV16 mission). This is a 50-kg satellite designed and developed at the Universidad Politécnica de Madrid (UPM).

Design and first simulations of the TASEC-Lab power subsystem

This paper describes the modelling and simulation of the Electrical Power Subsystem (EPS) of the Thermal Analysis Support and Environment Characterization Laboratory (TASEC-Lab). TASEC-Lab is a university experiment on board a sub-orbital platform. It is designed to measure the convection heat transfer in high-altitude balloon missions. The EPS provides, regulates, and distributes electric power to the different systems, parts, and sensors that compose the TASEC-Lab (e.g., On Board Computer (OBC), temperature and pressure sensors, cup anemometer, GPS, heaters... ). It mainly consists of a Li-ion battery and two DC-DC converters, and they have been characterized by conducting laboratory tests and fitting to experimental data. A real power consumption profile of the first TASEC-Lab’s mission (designed by Universidad Politecnica de Madrid) is used as input to simulate the EPS. The mathematical model is validated by comparison with experimental results.

Comparison of FANT results using the ENDF/B-VII.1, JEFF-3.3 and TENDL2017 nuclear data libraries

FANT (Fuente Ampliada de Neutrones Térmicos; in Spanish) is a thermal neutron irradiation facility with an extended and very uniform irradiation area, that has been developed by the Neutron Measurements Laboratory of the Energy Engineering Department at Universidad Politecnica de Madrid (LMN-UPM). This device is a parallelepiped box made of high-density polyethylene (HDPE), moderator material, that uses an A95241m/B49e neutron source of 111 GBq nominal activity for irradiating materials. The facility design was previously optimized, and the neutron spectra were estimated by extensive calculations with the MCNP6.1 code and carrying out experimental measurements (Bedogni et al., 2017). The facility takes advantage of the scattering reactions of neutrons with the HDPE surfaces of the chamber, where the moderation process is effective, achieving relevant thermal neutron fluence rates. The main goal of this work has been to simulate and analyse the FANT system by Monte Carlo methods using the MCNP6.1 code, employing 3 different nuclear data libraries: ENDF/B-VII.1, JEFF-3.3 and TENDL 2017. The transport of thermal neutrons in HDPE, E < 1eV, has been calculated in all the cases taking into account the thermal S (α,β) treatment. The results achieved in this work have been compared with those previously obtained in the former development of FANT, using the MCNP6.1 code with the ENDF/B-VII.1 nuclear data, and experimental measurements. These results have shown that the JEFF-3.3 nuclear data library is the nuclear data library that provides of the best matching between the MCNP computational results, and the experimental data collected at FANT. Hence, the JEFF-3.3 nuclear data library seems to be the most correct library to design and benchmark thermal neutron activation devices.

Design, Ground Testing and On-Orbit Performance of a Sun Sensor Based on COTS Photodiodes for the UPMSat-2 Satellite.

This paper presents the development of the UPMSat-2 sun sensor, from the design to on-orbit operation. It also includes the testing of the instrument, one of the most important tasks that needs to be performed to operate a sensor with precision. The UPMSat-2 solar sensor has been designed, tested, and manufactured at the Universidad Politécnica de Madrid (UPM) using 3D printing and COTS (photodiodes). The work described in this paper was carried out by students and teachers of the Master in Space Systems (Máster Universitario en Sistemas Espaciales—MUSE). The solar sensor is composed of six photodiodes that are divided into two sets; each set is held and oriented on the satellite by its corresponding support printed in Delrin. The paper describes the choice of components, the electrical diagram, and the manufacture of the supports. The methodology followed to obtain the response curve of each photodiode is simple and inexpensive, as it requires a limited number of instruments and tools. The selected irradiance source was a set of red LEDs and halogen instead of an AM0 spectrum irradiance simulator. Some early results from the UPMSat-2 mission have been analyzed in the present paper. Data from magnetometers and the attitude control system have been used to validate the data obtained from the sun sensor. The results indicate a good performance of the sensors during flight, in accordance with the data from the ground tests.

Special Issue: Ensuring Sustainability. New Challenges for Organizational Engineering

This special issue of the Journal of Industrial Engineering and Management is dedicated on the most recent and relevant research, theories and practices in Industrial Engineering and Operations Management presented at the 14th International Conference on Industrial Engineering and Industrial Management and XXIV Congreso de Ingeniería de Organización - CIO 2020.The CIO 2020 was held on 9th and 10th July 2020 in Leganés - Madrid and was organized by the Universidad Politécnica de Madrid (UPM) and Universidad Carlos III de Madrid (UC3M). This conference is promoted by ADINGOR (Asociación para el Desarrollo de la Ingeniería de Organización) and AIM (European Academy for Industrial Management).

Modulation of plant root growth by nitrogen source-defined regulation of polar auxin transport.

Availability of the essential macronutrient nitrogen in soil plays a critical role in plant growth, development, and impacts agricultural productivity. Plants have evolved different strategies for sensing and responding to heterogeneous nitrogen distribution. Modulation of root system architecture, including primary root growth and branching, is among the most essential plant adaptions to ensure adequate nitrogen acquisition. However, the immediate molecular pathways coordinating the adjustment of root growth in response to distinct nitrogen sources, such as nitrate or ammonium, are poorly understood. Here, we show that growth as manifested by cell division and elongation is synchronized by coordinated auxin flux between two adjacent outer tissue layers of the root. This coordination is achieved by nitrate‐dependent dephosphorylation of the PIN2 auxin efflux carrier at a previously uncharacterized phosphorylation site, leading to subsequent PIN2 lateralization and thereby regulating auxin flow between adjacent tissues. A dynamic computer model based on our experimental data successfully recapitulates experimental observations. Our study provides mechanistic insights broadening our understanding of root growth mechanisms in dynamic environments.

Correction to “Evaluation of Presence in Virtual Environments: Haptic Vest and User’s Haptic Skills”

In the above article [1] , the affiliation of all authors should read “Centre for Automation and Robotics (UPM-CSIC), Universidad Politecnica de Madrid, 28006 Madrid, Spain.”

Measuring the Lighting Quality in Academic Institutions: The UPM Faculty of Aerospace Engineering (Spain)

This article analyzes the current status of the lighting quality at the Escuela Técnica Superior de Ingeniería Aeronáutica y del Espacio (ETSIAE), the aerospace engineering faculty at the Universidad Politécnica de Madrid (UPM), and evaluates possible improvement actions based on the use of DIALux® lighting simulation software together with measured data. The results show rather low levels of measured illuminance on classroom desks and blackboards in one of the buildings comprising the faculty. The improvements proposed (a new coat of paint on the walls and replacement of luminaires) were simulated in four individual classrooms representing all rooms in two of the ETSIAE buildings (where the lower illuminance levels were measured). In order to study these improvements, the current situation of the four selected classrooms was simulated using DIALux® and fine-tuning attenuation of the luminaires to take into account their wear and tear. The correlation between the DIALux® simulation and the test results was analyzed with quite good results. The results clearly reveal a need to fully replace the classroom lighting systems in ETSIAE building A (the oldest building, dating back to 1955). According to the results from the selected classrooms, the average lighting over the desks can be greatly improved by using LED technology in order to meet UNE 12464-1 standard (that is, 500 lx, from an initial situation with much lower illuminance values: 129 lx to 295 lx). This article represents an innovative way to perform lighting improvement projects as real measured lighting data is used as initial input for the lighting simulations.

Indoor LOS Propagation Measurements and Modeling at 26, 32, and 39 GHz Millimeter-Wave Frequency Bands

Although the deployment of 5G networks has already started, there are still open questions regarding propagation at millimeter-wave frequency bands. Several propagation campaigns have been carried out at several bands previously identified by regulatory organizations, but due to the wide range of allocated segments of spectrum and the variety of possible propagation scenarios, more measurement campaigns are needed. In this regard, the Universidad Politécnica de Madrid (UPM) has taken millimeter-wave measurements at 26, 32, and 39 GHz bands in an indoor corridor scenario in line-of-sight (LOS) conditions with two antenna configurations (a horn antenna has been used in transmission whereas horn and omnidirectional antennas have been used in reception), and the main results are presented in this paper. The obtained path loss results have been compared with existing millimeter-wave propagation models.

Experimental Determination of the Energetic Performance of a Racing Motorcycle Battery-Pack

This paper presents the evaluation of the energetic performance of the battery-pack from the motorcycle prototype EME 16E. This racing prototype was developed by a student team from the Universidad Politécnica de Madrid (UPM) to participate in the MotoStudent competition during 2015–2016. This study includes the sizing and assembly of the motorcycle’s battery-pack under strict regulations and a limited budget. The prototype was also tested under different performance conditions, such as laboratory tests and racing circuits. Experimental results show that the proposed battery-pack is capable of supplying the energy and power necessary to drive the motorcycle in all cases analyzed.

Modeling and results of the dry cask simulator (DCS) with STAR-CCM+

To understand the behavior of commercial nuclear fuel during its storage phase in spent fuel dry storage casks, simulations are necessary and to validate the simulation models, full-scale experiments are required. Therefore, an experimental facility called the dry cask simulator (DCS) was built in Sandia National Laboratories with the purpose of producing validation-quality data that can be used to test the accuracy of the modeling used to determine cladding temperatures in modern vertical dry casks. The DCS has been created under the framework of the Extended Storage Collaboration Programme (ESCP), coordinated by EPRI.The ultimate goal of the DCS was to study the thermal–hydraulic response of a single boiling water reactor (BWR) fuel assembly under variety of heat loads, internal vessel pressures, and external configurations. In this article, the simulations conducted by ENUSA Industrias Avanzadas S.A., S.M.E and UPM (Universidad Politécnica de Madrid, Spain) using STAR-CCM+ are validated against the experiments conducted at Sandia National Laboratories.In order to validate the simulation models several sensitivity analyses have been performed: a grid convergence index to estimate the discretization error in the simulations, a turbulence model sensitivity for the inner part of the cask, and three different approaches to model the fuel assembly: Case 1 (model with no spacers and no bottom tie plate), Case 2 (model with spacers and no bottom tie plate and Case 3 (model with spacers and bottom tie plate).Additionally, a thermal–hydraulic analysis is also presented, not only to explain the difference between the three ways to model the fuel assembly, but also to obtain a better understanding of the behavior of the dry cask according to pressure and heat output changes.Among the three cases, the simplest model (Case 1) has proven to obtain the most accurate results, being able to predict the temperature distribution in the fuel assembly and the air mass flow compared to the experiment measurements for all four cases of study. Meanwhile, the two other cases have shown that for steady state solutions the spacers and the bottom tie plate are not necessary and can introduce unwanted errors. Nonetheless, all cases have provided insight into the behavior of a dry storage cask system under different conditions showing the different heat transfer mechanisms interactions.

Correction to: From stand-up to start-up: exploring entrepreneurship competences and STEM women’s intention

The author included the name of her University in English “Technical University of Madrid” and it seems that to validate it for her PhD tramitation, it should appear in its original name “Universidad Politecnica de Madrid”. Change applies for all authors.

Opportunities and Challenges of Ambient Radio-Frequency Energy Harvesting

Dr. Xu Zhang is an assistant professor in the Department of Electrical and Computer Engineering at Carnegie Mellon University. He obtained his BS in physics from University of Science and Technology of China and his PhD in electrical engineering from Massachusetts Institute of Technology. He was an Enrico Fermi Fellow at Argonne National Laboratory from 2018 to 2019. His research interests include nanoelectronics, nanophotonics, and emerging materials for energy harvesting, sensing, and communication applications. Dr. Jesus Grajal received his PhD in electrical engineering from Universidad Politecnica de Madrid (UPM) in 1998. Since 2017, he has been a Full Professor with the Signals, Systems, and Radiocommunications Department at UPM. His current research interests include semiconductor device modeling and high-frequency circuit and system design. Dr. Marisa Lopez-Vallejo received a PhD in electronic engineering from Universidad Politecnica de Madrid (UPM) in 1999. She was with Bell Laboratories, Lucent Technologies, Murray Hill, NJ, USA as a Member of the Technical Staff. Since 2016, she has been a Full Professor with the Electronic Engineering Department at UPM. Her major interests are in the area of low power, PVT-aware design, computer-aided diagnostic methods and tools, emerging memories, and application-specific high-performance programmable architectures. Elaine McVay is pursuing a PhD in the Department of Electrical Engineering and Computer Science at MIT. Her research interests include 2D material/thin-film photovoltaics and infrared detectors. Dr. Tomas Palacios is a Professor in the Department of Electrical Engineering and Computer Science at MIT. He received his PhD from the University of California - Santa Barbara in 2006 and his undergraduate degree in Telecommunication Engineering from the Universidad Politecnica de Madrid. His current research focuses on demonstrating new electronic devices and applications for novel semiconductor materials such as graphene and gallium nitride. His work has been recognized with multiple awards, including the Presidential Early Career Award for Scientists and Engineers, the IEEE George Smith Award, and the NSF, ONR, and DARPA Young Faculty Awards, among many others.

Monte Carlo design and experimental characterization of a moderator device to produce a thermal neutron source from a 241Am/9Be source

A moderator device to produce a uniform thermal neutron field has been designed by Monte Carlo methods using the MCNP6.1 code. It uses a 241Am/9Be neutron source of 111 GBq activity and high-density polyethylene (HDPE) moderator. The main tasks developed were to evaluate the geometry of the moderator and to select the neutron source position, in order to optimize the thermal neutrons flux in the irradiation area, and to assess the dose rate. In the system, named FANT (Fuente Ampliada de Neutrones Térmicos), the neutron moderation and backscattering processes are effective to obtain quite uniform thermal fluence rates above 1000 cm−2 s−1 in a cylindrical irradiation chamber of 32 cm diameter and 34 cm length. The device has been built in the neutron measurements hall of the Energy Engineering Department of Universidad Politécnica de Madrid (UPM), performing several measurements to characterize the neutron field and validate the calculations.FANT can be employed hereafter in different applications requiring a neutron field with a substantial thermal component, like testing and calibration of neutron detectors and neutron dosimeters, or the use NAA (Neutron Activation Analysis) methods for detection of trace substances or materials.