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Ítem 1) solución del sistema de cimentación para un tanque de almacenamiento elevado sobre suelos arenosos licuables; 2) diseño del soporte de la excavación para el sótano de un edificio mediante la técnica de suelo cosido con pilotes helicoidales; 3) diseño de la excavación de un pozo vertical para derivación de caudales y 4) diseño de un encofrado de tablaestacas para la construcción de una estación de pre-acondicionamiento del sistema de alcantarillado sanitario en una ciudad costera(2022-08) Cabezas Herrera, Óscar José; Monge Sandí, Ana LorenaEl presente proyecto desarrolla la solución, aplicando diferentes teorías y técnicas de análisis de la Ingeniería Geotécnica, para cuatro proyectos de ingeniería que presentan complejidades o problemáticas geotécnicas en función de su entorno y tipo de obra. El primer caso resuelve el sistema de cimentación para un tanque elevado a colocar sobre un terreno arenoso que es susceptible a licuación. La alternativa propuesta se fundamenta en una losa de rígida de cimentación para distribuir de manera uniforme las cargas y brindar adecuada estabilidad ante el volcamiento producido por los sismos. A su vez, la losa se apoya sobre un terreno mejorado con columnas de grava que se diseñan para mitigar el riesgo de licuación, además de incrementar la resistencia y rigidez del terreno. Luego, se estudia el caso del sostenimiento de una excavación temporal para la construcción de 3 niveles de sótano para un edificio a erigir en el centro de San José. La alternativa propuesta se fundamenta en un sistema alternativo de suelo cosido con pilotes helicoidales como elementos de anclaje, en lugar de pernos pasivos convencionales con barras inyectadas con el objetivo de aprovechar las ventajas constructivas y capacidad del primer sistema. El tercer caso contempla el análisis geotécnico y propuesta de sostenimiento para la excavación de un pozo vertical de 8.0 m de diámetro y 55.0 m de profundidad, cuyo objetivo es interconectarse a un túnel hidráulico existente para permitir la distribución de caudales hacia diferentes puntos. Se realiza un análisis y diseño sectorizado en función de la calidad geomecánica de los materiales y el modo de falla predominante asociado a cada tipo de litología. En el último caso, se realiza el diseño geotécnico de un sistema de encofrado de tablaestaca metálicas para el sostenimiento la excavación constructiva de una estructura subterránea que servirá para albergar el tratamiento primario de aguas residuales provenientes del alcantarillado sanitario de una ciudad costera, previo a su disposición en el lecho oceánico. Para cada una de las soluciones se elaboran planos constructivos esquemáticos, especificaciones técnicas de materiales y un presupuesto del costo de las obras.Ítem 2D SLAM Algorithms Characterization, Calibration, and Comparison Considering Pose Error, Map Accuracy, CPU Usage, and Memory Usage(2022) Trejos Vargas, Kevin Francisco; Rincón Riveros, Laura Camila; Bolaños Torres, Miguel Eduardo; Fallas Pizarro, José Ariel; Marín Paniagua, Leonardo JoséThe present work proposes a method to characterize, calibrate, and compare, any 2D SLAM algorithm, providing strong statistical evidence, based on descriptive and inferential statistics to bring confidence levels about overall behavior of the algorithms and their comparisons. This work focuses on characterize, calibrate, and compare Cartographer, Gmapping, HECTOR-SLAM, KARTO-SLAM, and RTAB-Map SLAM algorithms, there were four metrics in place, these are pose error, map accuracy, CPU usage, and memory usage, from these four metrics, to characterize them, Plackett-Burman and factorial experiments were performed, and enhancement after characterization and calibration was granted by using hypothesis tests besides central limit theorem.Ítem A Comparative Study on Denoising Algorithms for Footsteps Sounds as Biometric in Noisy Environments(2022-08-03) Caravaca Mora, Ronald; Brenes Jiménez, Carlos; Coto Jiménez, MarvinBiometrics is the automated identification of a person based on distinctive characteristics, such as fingerprints, face, voice, or the sound of footsteps. This last characteristic has significant challenges considering the background noise present in any real-life application, where microphones would record footsteps sounds and different types of noise. For this reason, it is crucial to consider not only the capacity of classification algorithms for recognizing a person using foostetps sounds, but also at least one stage of denoising algorithms that can reduce the background sounds before the classification. In this paper we study the possibilities of a two-stage approach for this problem: a denoising stage followed by a classification process. The work focuses on discovering the proper strategy for applying combinations of both stages for specific noise types and levels. Results vary according to the type and level of noise, e.g., for White noise at signal-to-noise ratio level, accuracy can increase from 0.96 to 1.00 by applying deep learning based-filters, but the same option does not benefit the cases of signals with low level natural noises, where Wiener filtering can increase accuracy from 0.6 to 0.77 at the highest level of noise. The results represent a baseline for developing real-life implementations of footstep biometrics.Ítem A Comparison between a Relational Database and a Graph Database in the context of a Personalized Cancer Treatment Application(2016) Martínez Porras, Alexandra; Mora Rodríguez, Rodrigo Antonio; Alvarado González, Daniel; López Herrera, Gustavo; Quirós Barrantes, SteveThis paper presents a performance comparison between a relational database (implemented in MySQL) and a graph database (implemented in Neo4j). Unlike traditional benchmarks, this comparison is made in the context of a real health application which was developed in Costa Rica. The comparison encompassed twelve queries and three data size configurations.The results of the comparison indicate that MySQL performs better than Neo4j in most cases, but has a poor performance when data size is large and the queries have multiple join operations.Ítem A comparison of bio-inspired optimization methodologies applied to the tuning of industrial controllers(2016-11-09) Céspedes, Macarena; Contreras, Mónica; Cordero, Joaquín; Montoya, Gustavo; Valverde, Karen; Rojas Fernández, José DavidA comparison of different bio-inspired methods is presented for the problem of tuning the parameters of a PID industrial controller for second order plus time delay plants. The compared algorithms are representative of three different kind of methodologies (evolutionary, swarm-based and ecology-based). Al methods are briefly explained and are fully implemented to solve the control problem at hand. It was found that all methods are well suited to solve the problem, but they differ in its computational cost. However in all cases, the different methodologies tested were able to find similar minimum values for different families of plantsÍtem A DMC implementation for a binary distillation column: a MIMO approach(2022-11) Villalobos Herra, Elena; Chacón Vásquez, MercedesDistillation columns are essential equipment for many industries, they are in charge of separating liquid mixtures based on the volatility differences of their components. Traditional PID control techniques have proven not to be the best fit for operating distillation columns when trying to obtain pure components, since they are a very complex process. In order to test MPC control with distillation columns, a real pilot-scale model is chosen and a multiple-input multiple-output DMC algorithm is developed in MATLAB®. Additionally, a fuzzy logic controller is created based on previous work, in order to compare the distillation column control performance. Simulation results show good performance of the MPC.Ítem A first approach to acoustic characterization of Costa Rican children’s speech(2020-03-27) Coto Jiménez, Marvin; Morales Rodríguez, Maribel; Vargas Díaz, Daniel AlfredoAs human interaction with computers becomes more pervasive, the value of developing automatic speech recognition, text-to-speech synthesis, and related speech technologies become more important for people of all ages, accents, and conditions. One of the groups that represent bigger challenges is children, due to the difficulties in recording enough speech, and the lack of characterization of their speech, which is particular of every language and accent. This paper presents the first approach to acoustic analyses of Costa Rican children aged from six to twelve years. These analyses aimed to achieve a better understanding of the characteristics of speech produced by this group, in terms of providing future development and enhancement of automatic speech recognizers and speaker identification systems. For this purpose, we record the speech consisting of isolated words of three children, and compare the results with three adults, in terms of the vowel’s formants. The formants give information about the vocal track of the speaker, and it is an important method to provide the first analysis of these signals. Results show noticeable differences between the children and adults and may provide useful information about future trends to adapt and develop the current speech technologies for this population.Ítem A Functional Size Measurement Procedure for MVC Applications from Source Code: Design, Automation and Empirical Evaluation(2014-09) Quesada López, Christian UlisesSoftware size has proved to be one of the main effort-and-cost drivers. It is widely accepted that software size is one of the key factors that has the potential to affect the effort and cost of the software projects. Functional size methods are hardly automatable and generally require a lengthy and costly process. FSM methods define generic concepts and measurement rules. The setup of a measurement procedure for each input to the measurement process is hence needed. A measurement procedure is defined as a set of operations described explicitly in order to measure according to a specific measurement method. A size estimation procedure based on the use of software development productivity models allows the management of development costs. Although accurate size estimation and effort prediction are very important for the success of any project, many practitioners have experienced difficulties in applying them. Thus, automated and simplified FSM methods are required. This research aims to proposing a functional size measuring procedure for Model-View-Controller (MVC) applications from source code. The research project includes the design, automation and empirical validation of a functional size measuring procedure, according to the ISO/IEC 20926 FPA CPM method. This proposal describes the research agenda of the PhD project. Research objective, background, relevant, prior work, research methods, threats to validity, current status and future plans are described in details. Since this is an ongoing work, this proposal looks for feedback from the expert community in order to improve its consistency as well as the reliability of the empirical validation.Ítem A genetic algorithm based framework for software effort prediction(2017) Murillo Morera, Juan; Quesada López, Christian Ulises; Castro Herrera, Carlos; Jenkins Coronas, MarceloBackground: Several prediction models have been proposed in the literature using different techniques obtaining different results in different contexts. The need for accurate effort predictions for projects is one of the most critical and complex issues in the software industry. The automated selection and the combination of techniques in alternative ways could improve the overall accuracy of the prediction models. Objectives: In this study, we validate an automated genetic framework, and then conduct a sensitivity analysis across different genetic configurations. Following is the comparison of the framework with a baseline random guessing and an exhaustive framework. Lastly, we investigate the performance results of the best learning schemes. Methods: In total, six hundred learning schemes that include the combination of eight data preprocessors, five attribute selectors and fifteen modeling techniques represent our search space. The genetic framework, through the elitism technique, selects the best learning schemes automatically. The best learning scheme in this context means the combination of data preprocessing + attribute selection + learning algorithm with the highest coefficient correlation possible. The selected learning schemes are applied to eight datasets extracted from the ISBSG R12 Dataset. Results: The genetic framework performs as good as an exhaustive framework. The analysis of the standardized accuracy (SA) measure revealed that all best learning schemes selected by the genetic framework outperforms the baseline random guessing by 45–80%. The sensitivity analysis confirms the stability between different genetic configurations. Conclusions: The genetic framework is stable, performs better than a random guessing approach, and is as good as an exhaustive framework. Our results confirm previous ones in the field, simple regression techniques with transformations could perform as well as nonlinear techniques, and ensembles of learning machines techniques such as SMO, M5P or M5R could optimize effort predictions.Ítem A Gesture-Based Interaction Approach for Manipulating Augmented Objects Using Leap Motion(2015-11) López Herrera, Gustavo; Quesada Quirós, Luis; Guerrero Blanco, Luis AlbertoAmbient Intelligence and Ubiquitous Computing are carrying the world to a reality where almost every object interacts with the environment, either via sensors or actuators, and users must learn how to interact with such systems. This paper presents a gesture-based interaction approach to manipulate such objects. We developed a prototype using a leap motion controller as a hand-tracking device, and a Support Vector Machine as a classifier to distinguish between gestures. Our system was evaluated by 12 users with over 10 commands. We also show a review on gesture-based interaction and compare other proposals with ours.Ítem A mechano-biocatalytic one-pot approach to release sugars from lignocellulosic materials(2020) Zhong, Yuan; Frost, Henry; Bustamante Román, Mauricio; Li, Song; Liu, Yan; Liao, WeiA novel, mechano-biocatalytic one-pot process was developed by this study to efficiently release monosaccharides from lignocellulosic materials in an environmentally-friendly manner. The process synergistically integrates ball milling and enzymatic hydrolysis to complete pretreatment and hydrolysis of lignocellulosic materials in a single step without chemical supplements. High sugar titer and conversion from lignocellulosic materials were simultaneously achieved. Among four studied feedstocks (solid digestate, corn stover, switchgrass, and miscanthus), corn stover demonstrated much better sugar concentration and conversion. Under the preferred reaction condition, the glucose concentration reached 55.20 g/L with a glucose conversion of 88.63%. The corresponding xylose concentration was 20.06 g/L with a xylose conversion of 67.34%. The energy and exergy analyses further indicate that the studied process had better energy and exergy profiles than the conventional combined hydrolysis process. The average energy consumption of the mechano-biocatalytic process for four feedstocks was 1.05 kWh-e/kg dry biomass that was 56% lower than the average energy consumption (2.37 kWh-e/kg dry biomass) of the conventional process. The corresponding average exergy efficiency of the mechano-biocatalytic process was 67% that was much higher than the average efficiency (52%) of the conventional process. These results show that the mechano-biocatalytic one-pot process as an environmentally friendly approach can significantly simplify the pretreatment and hydrolysis and enhance their efficiencies for advanced fuel and chemical production.Ítem A mobile application for improving the delivery process of notifications(2021-01) Ureña Madrigal, Heriberto; López Herrera, Gustavo; Díaz Oreiro, Ignacio; Quesada Quirós, LuisAt present, there are systems in charge of classifying and sending notifications to smart devices at different times. However, there are not many studies that demonstrate the effectiveness of these systems in real world settings. We propose a method that classifies and prioritizes notifications by analyzing only the content of the notification and the sender of the message. We also developed a system implementing this method. User diaries were used to analyze the behavior of the system in real world situations, and the results showed that the implemented system significantly reduces interruptions to users. Additionally, the user experience of the system was evaluated through the standardized questionnaire UEQ (User Experience Questionnaire). The results obtained were positive in most of the scales of this instrument, above the average according to UEQ benchmarks. However, aspects such as stimulation and creativity can be improved in the future to motivate users to use the system.Ítem A mobile application that allows children in the early childhood to program robots(2016) Ramírez Benavides, Kryscia Daviana; López Herrera, Gustavo; Guerrero Blanco, Luis AlbertoChildren born in the Information Age are digital natives; this characteristic should be exploited to improve the learning process through the use of technology. This paper addresses the design, construction, and evaluation process of TITIBOTS, a programming assistance tool for mobile devices that allows children in the early childhood to create programs and execute them using robots. We present the results of using TITIBOTS in different scenarios with children between 4 and 6 years old. The insight obtained in the development and evaluation of the tool could be useful when creating applications for children in the early childhood. The results were promising; children liked the application and were willing to continue using it to program robots to solve specific tasks, developing the skills of the 21st century.Ítem A Model Proposal for Augmented Reality Game Creation to Incentivize Physical Activity(2017) Cicció Cabezas, José Antonio; Quesada Quirós, LuisObesity and a sedentary lifestyle are relevant issues in today’s society. Even though different resources can be used to approach this problem, technology provides endless possibilities to fight against this problem. This article presents the results of a model to create augmented reality games where goals are achieved by doing physical activity (moving between different places). In order to evaluate the model, a prototype was built and presented to 50 participants. The results obtained indicated that an important percentage of the interviewees were attracted to the idea of playing a game to increase their physical activity.Ítem A modeling methodology to evaluate the impact of temperature on Solar Home Systems for rural electrification(2018) Narayan, Nishant; Vega Garita, Víctor; Qin, Zian; Popovic Gerber, Jelena; Bauer, Pavol; Zeman, MiroslavSolar Home Systems (SHS) have recently gained prominence as the most promising solution for increasing energy access in remote, off-grid communities. However, the higher than standard testing conditions (STC) temperatures have a significant impact on the SHS components like PhotoVoltaic (PV) module and battery. A modeling methodology is described in this study for quantifying the temperature impact on SHS. For a particular location with high irradiation and temperatures and a given load profile, an SHS model was simulated, and the temperature-impact was analyzed on the performance and lifetime of the SHS components. Different PV module temperature estimation models were applied, and the corresponding dynamic PV outputs were compared. The nominal operating cell temperature (NOCT) model was found inadequate for estimating PV module temperatures under high irradiance conditions. The PV yield was found to be affected by almost 10% due to thermally induced losses. When different levels of temperature variations were considered, the battery lifetime was seen to be up to 33% less than that at 25°C. The modeling methodology presented in this paper can be used to include the thermal losses in SHS for rural electrification, which can further help accordingly in system sizing.Ítem A novel control strategy for modular multilevel-based drives considering the system operating point(2018-11-01) Espinoza Bolaños, Mauricio; Donoso Urrutia, Felipe Ignacio; Espina González, Enrique; Díaz Díaz, Matías; Cárdenas Dobson, Jesús Roberto Pedro AlejandroModular Multilevel Converters (MMC) are considered an attractive solution for high-power mediumvoltage drives. However, in drive applications, the influence of the loading conditions leads to more complex control systems than the required ones for constant frequency applications. To solve this issue, a novel control methodology for the MMC-based drive is presented in this paper. The proposed scheme defines the best control structure to balance the voltage of the converter capacitors considering the drive operating point (e.g. the loading conditions and the machine frequency). The design of the converter parameters considering the desired behaviour of the converter is also discussed in this paper. Experimental results with an 18-power cells MMC are used to validate the proposed control strategy.Ítem A Novel Control System for Medium-Voltage Hexverter-Based Drives(2020-09-23) Espinoza Bolaños, Mauricio; Donoso M., Felipe; Díaz D., Matías; Urrutia O., Matías; Cárdenas Dobson, RobertoIn this paper, a novel control system for the Hexverter-based drive is proposed and analysed. Unlike previously proposed control schemes, the proposed one does not require the information of the machine variables to regulate the converter floating capacitors, as required in high-performance drive applications. The feasibility of the proposed control system is demonstrated by using simulation results of an Hexverter-based drive driving a medium-voltage machine, including the whole frequency range and high starting torque loads.Ítem A novel distributed secondary control strategy applied to hybrid ac/dc microgrids(2019-11-28) Espina González, Enrique; Cárdenas Dobson, Jesús Roberto Pedro Alejandro; Donoso Urrutia, Felipe Ignacio; Urrutia Ortiz, Matías Alonso; Espinoza Bolaños, MauricioIn this paper, a distributed secondary control strategy for hybrid ac/dc-microgrids is proposed. The control strategy restores the variables modified by the primary control loop, i.e. voltage on the DC-side and voltage amplitude and frequency of the AC-side, to their nominal values while maintaining a good power-sharing capability between AC- and DC-units, A distributed communication network among the generation units is needed for the proper performance of the control strategy, however, a high bandwidth communication network is not needed to ensure a good behaviour of the proposed control scheme. The effectiveness of the control scheme is validated through simulation of a 9.0kW hybrid ac/dc-microgrid.Ítem A novel LVRT control strategy for Modular Multilevel Matrix Converter based high-power Wind Energy Conversion Systems(2015-06-01) Díaz Díaz, Matías; Cárdenas Dobson, Jesús Roberto Pedro Alejandro; Espinoza Bolaños, Mauricio; Mora Castro, Andrés Felipe; Rojas Lobos, Félix EduardoThe trend of multimegawatt wind turbines has positioning multilevel converters as a promising solution for high-power Wind Energy Conversion Systems (WECSs). Furthermore, due to the high penetration of wind energy into the electrical network, some rather strict grid regulations have been development in case of fault into the grid power. Mainly, grid codes set Low Voltage Ride Through (LVRT) requirements for grid connected WECS. In this scenario, this paper presents a novel modelation and control strategy to fulfil Low Voltage Ride Through requirements using a Modular Multilevel Matrix Converter for interfacing a high power wind turbine.Ítem A novel topology and control system for Interconnected Wave Energy converters (IWECS)(2019-11-28) Rodríguez Vindas, Mauricio; Espinoza Bolaños, Mauricio; Cárdenas Dobson, Jesús Roberto Pedro Alejandro; McDonald, Stephen P.; Baker, Nick J.Recently, the extraction of energy from the incoming waves has taken more importance in the energy generation based on renewable resources. However, most of the attention has been directed towards the Power-Take-Off systems more than in the interaction between several generating units. Consequently, in this work, there are presented and carefully analysed a novel topology of Interconnected Wave-Energy Converters (IWECs) and its associated control system. A representative set of data of a real wave frequency and height variation from the South Uist island, in Scotland, and a proof-of-concept simulation show that the energy requirements of the proposed IWEC are lower than those required for individual WECs.