293 research outputs found
SCALING UP TASK EXECUTION ON RESOURCE-CONSTRAINED SYSTEMS
The ubiquity of executing machine learning tasks on embedded systems with constrained resources has made efficient execution of neural networks on these systems under the CPU, memory, and energy constraints increasingly important. Different from high-end computing systems where resources are abundant and reliable, resource-constrained systems only have limited computational capability, limited memory, and limited energy supply. This dissertation focuses on how to take full advantage of the limited resources of these systems in order to improve task execution efficiency from different aspects of the execution pipeline. While the existing literature primarily aims at solving the problem by shrinking the model size according to the resource constraints, this dissertation aims to improve the execution efficiency for a given set of tasks from the following two aspects. Firstly, we propose SmartON, which is the first batteryless active event detection system that considers both the event arrival pattern as well as the harvested energy to determine when the system should wake up and what the duty cycle should be. Secondly, we propose Antler, which exploits the affinity between all pairs of tasks in a multitask inference system to construct a compact graph representation of the task set for a given overall size budget. To achieve the aforementioned algorithmic proposals, we propose the following hardware solutions. One is a controllable capacitor array that can expand the system’s energy storage on-the-fly. The other is a FRAM array that can accommodate multiple neural networks running on one system.Doctor of Philosoph
A New Dimension of Cancer Treatment: Analysing and Targeting High-Grade Glioma Invasion Using Three-Dimensional In Vitro Models
High-Grade Gliomas (HGG) are an extremely aggressive form of brain cancer with limited targeted treatments and dire prognosis. Despite global improvements in overall cancer survival, HGG survival rates have stagnated over the last three decades. This can be partly attributed to HGG’s characteristically invasive progression into the brain, where far-invaded cells are often missed by first-line therapies leading to tumour recurrence. The use of anti-invasive agents may limit extensive cell spread and improve efficacy of adjuvant anti-cancer therapies, thus, this study has investigated the novel anti-invasive PTU (p-tolyl-ureidopalmitic acid), an omega-3-derivative with the ability to cross the blood brain barrier. PTU was tested in primary patient-derived HGG cells cultured in 3D models designed to replicate discrete aspects of the 3D in vivo brain microenvironment. Across models, PTU treatment decreased the number of invading HGG cells and mitigated both single and collective invasion phenotypes. Importantly, this data demonstrates that 3D in vitro culture can reliably represent a whole-picture of HGG invasion. Additionally, this study involved the development of a dynamic, temporal reporter of transcriptional co-activators Yes-associated Protein and Transcriptional co-Activator with PDZ-binding motif (YAP/YAZ), which are mediators of a number of malignant processes and regulated by bio-mechanical signalling. This was achieved with an Adeno-associated-virus (AAV)-mediated gene delivery method, which also revealed a number of AAV capsid variants with tropism to primary patient-derived HGG cells. This reporter has potential future uses in revealing YAP/TAZ activity within the 3D biologically-relevant in vitro models. Together, these findings reveal potential successful therapeutic strategies for HGG and provide multiple insights into future research possibilities in the hopes of mitigating the extent of this truly debilitating and devastating disease
Advances in Sensors, Big Data and Machine Learning in Intelligent Animal Farming
Animal production (e.g., milk, meat, and eggs) provides valuable protein production for human beings and animals. However, animal production is facing several challenges worldwide such as environmental impacts and animal welfare/health concerns. In animal farming operations, accurate and efficient monitoring of animal information and behavior can help analyze the health and welfare status of animals and identify sick or abnormal individuals at an early stage to reduce economic losses and protect animal welfare. In recent years, there has been growing interest in animal welfare. At present, sensors, big data, machine learning, and artificial intelligence are used to improve management efficiency, reduce production costs, and enhance animal welfare. Although these technologies still have challenges and limitations, the application and exploration of these technologies in animal farms will greatly promote the intelligent management of farms. Therefore, this Special Issue will collect original papers with novel contributions based on technologies such as sensors, big data, machine learning, and artificial intelligence to study animal behavior monitoring and recognition, environmental monitoring, health evaluation, etc., to promote intelligent and accurate animal farm management
2022 roadmap on neuromorphic computing and engineering
Modern computation based on von Neumann architecture is now a mature cutting-edge science. In the von Neumann architecture, processing and memory units are implemented as separate blocks interchanging data intensively and continuously. This data transfer is responsible for a large part of the power consumption. The next generation computer technology is expected to solve problems at the exascale with 10 calculations each second. Even though these future computers will be incredibly powerful, if they are based on von Neumann type architectures, they will consume between 20 and 30 megawatts of power and will not have intrinsic physically built-in capabilities to learn or deal with complex data as our brain does. These needs can be addressed by neuromorphic computing systems which are inspired by the biological concepts of the human brain. This new generation of computers has the potential to be used for the storage and processing of large amounts of digital information with much lower power consumption than conventional processors. Among their potential future applications, an important niche is moving the control from data centers to edge devices. The aim of this roadmap is to present a snapshot of the present state of neuromorphic technology and provide an opinion on the challenges and opportunities that the future holds in the major areas of neuromorphic technology, namely materials, devices, neuromorphic circuits, neuromorphic algorithms, applications, and ethics. The roadmap is a collection of perspectives where leading researchers in the neuromorphic community provide their own view about the current state and the future challenges for each research area. We hope that this roadmap will be a useful resource by providing a concise yet comprehensive introduction to readers outside this field, for those who are just entering the field, as well as providing future perspectives for those who are well established in the neuromorphic computing community
Contributions to the design of energy harvesting systems for autonomous sensors in low power marine applications
Tesi en modalitat de compendi de publicacionsOceanographic sensor platforms provide biological and meteorological data to help understand changes in marine environment and help to preserve it. Lagrangian drifters are autonomous passive floating platforms used in climate research to obtain surface marine data. They are low-cost, versatile, easy-to-deploy and can cover large extensions of the ocean when deployed in group.
These deployments can last for years, so one of the main design challenges is the autonomy of the drifter. Several energy harvesting (EH) sources are being explored to reduce costs in battery replacement maintenance efforts such as solar panels. Drifters must avoid the impact of the wind because this may compromise proper surface current tracking and therefore, should ideally be mostly submerged. This interferes with the feasibility of solar harvesting, so other EH sources are being explored such as the oscillatory movement of the drifter caused by ocean waves. Wave energy converters (WEC) are the devices that turn this movement into energy.
The motion of the drifter can principally be described by 3 oscillatory degrees of freedom (DoF); surge, heave and pitch. The heave motion includes the buoyancy’s response of the drifter, which can be explained by a mass-spring-damping model. By including the wave’s hydrodynamic load in this model, it is converted into a nonlinear system whose frequency response includes the wave’s frequency and the natural frequencies from the linear system. A smart option to maximize the captured energy is to design the inner WEC with a natural frequency similar to that of the drifter's movement. In this thesis, a 4 DoF model is obtained. This model includes the heave, the surge and the pitch motion of the drifter in addition to the inner pendulum motion relative to the buoy. Simultaneously, different pendulum-type WECs for small-size oceanic drifters are proposed. One of these converters consists of an articulated double-pendulum arm with a proof mass that generates energy through its relative motion with the buoy. Different experimental tests are carried out, with a prototype below 10 cm in diameter and 300 g of total mass, proving the capability of harvesting hundreds of microwatts in standard sea conditions EH sources require an additional power management unit (PMU) to convert their variable output into a constant and clean source to be able to feed the sensor electronics. PMUs should also ensure that the maximum available energy is harvested with a maximum power point tracking (MPPT) algorithm. Some sources, such as WECs, require fast MPPT as its output can show relatively rapid variations. However, increasing the sampling rate may reduce the harvested energy. In this thesis, this trade-off is analyzed using the resistor-based fractional open circuit voltage-MPPT technique, which is appropriate for low-power EH sources. Several experiments carried out in marine environments demonstrate the need for increasing the sampling rate. For this purpose, the use of a commercial PMU IC with additional low-power circuitry is proposed. Three novel circuits with a sampling period of 60 ms are manufactured and experimentally evaluated with a small-scale and low-power WEC. Results show that these
configurations improve the harvested energy by 26% in comparison to slow sampling rate configurations.
Finally, an EH-powered oceanographic monitoring system with a custom wave measuring algorithm is designed. By using the energy collected by a small-size WEC, this system is capable of transmitting up to 22 messages per day containing data on its location and measured wave parameters.Les plataformes d’observació oceanogrà fiques integren sensors que proporcionen dades fÃsiques i biogeoquÃmiques de l’oceà que ajuden a entendre canvis en l’entorn marÃ. Un exemple d’aquestes plataformes són les boies de deriva (drifters), que són dispositius autònoms i passius utilitzats en l’à mbit de la recerca climà tica per obtenir dades in-situ de la superfÃcie marina. Aquests instruments són de baix cost, versà tils, fà cils de desplegar i poden cobrir grans superfÃcies quan s’utilitzen en grup. L’autonomia és un dels principals desafiaments en el disseny de drifters. Per tal d’evitar els costos en la substitució de bateries, s’estudien diferents fonts de captació d’energia com per exemple la solar. Els drifters utilitzats per l’estudi dels corrents marins superficials han d’evitar l’impacte directe del vent ja que afecta al correcte seguiment de les corrents i, per tant, cal que estiguin majorità riament submergides. Això compromet la viabilitat de l’energia solar, fet que requereix l’estudi d’altres fonts de captació com el propi moviment de la boia causat per les onades. Els convertidors d’energia de les onades (WEC, wave energy converters) compleixen aquesta funció. El moviment dels drifters pot explicar-se bà sicament a través de 3 graus de llibertat oscil·latoris: la translació vertical i la horitzontal i el balanceig. La translació vertical inclou la flotabilitat del dispositiu, que es pot descriure mitjançant el model massamolla- amortidor. Incloure la cà rrega hidrodinà mica de l’onada en aquest model el converteix en un sistema no lineal amb una resposta freqüencial que inclou la de l’onada i les naturals del sistema lineal. Una opció per maximitzar l’energia captada és dissenyar el WEC amb una freqüència natural similar a la del moviment de la boia. En aquesta tesis es proposa un model de 4 graus de llibertat per a l’estudi del moviment del drifter. Aquest inclou els 3 graus de llibertat de la boia i el moviment del pèndul relatiu a ella. En paral·lel, es proposen diferents WEC del tipus pendular per drifters de reduïdes dimensions. Un d’aquests WEC consisteix en un doble braç articulat amb massa flotant que genera energia a través del seu moviment relatiu al drifter. S’han dut a terme diferents proves experimentals amb un prototip inferior a 10 cm de dià metre i 300 g de massa, les quals demostren la seva capacitat de captar centenars de microwatts en condicions marines està ndard. Utilitzar fonts de captació d’energia requereix incloure una unitat gestora de potència (PMU, power management unit) per tal de convertir la seva sortida variable en una font constant i neta que alimenti l’electrònica dels sensors. Les PMU també tenen la funció d’assegurar que es recull la mà xima energia mitjançant un algoritme de seguiment del punt de mà xima potència. Els WEC requereixen un seguiment d’aquest punt rà pid perquè la seva sortida consta de variacions relativament rà pides. Tanmateix, augmentar la freqüència de mostreig pot reduir l’energia captada. En aquesta tesi, s'analitza a fons aquesta relació utilitzant la tècnica de seguiment de la tensió en circuit obert fraccionada basada en resistències, que és molt adequada per a fonts de baixa potència. Diversos experiments realitzats en el medi marà mostren la necessitat d'augmentar la freqüència de mostreig, aixà que es proposa l'ús de PMU comercials amb una electrònica addicional de baix consum. S’han fabricat tres circuits diferents amb un perÃode de mostreig de 60 ms i s’han avaluat experimentalment en un WEC de reduïdes dimensions. Els resultats mostren que aquestes configuracions milloren l'energia recollida en un 26% en comparació a PMU amb mostreig més lent. Finalment, s’ha dissenyat un sistema autònom de monitorització marina que inclou un algoritme de mesura d'ones propi. Aquest sistema és capaç de transmetre fins a 22 missatges al diaPostprint (published version
Novel Cardiac Mapping Approaches and Multimodal Techniques to Unravel Multidomain Dynamics of Complex Arrhythmias Towards a Framework for Translational Mechanistic-Based Therapeutic Strategies
[ES] Las arritmias cardÃacas son un problema importante para los sistemas de salud en el mundo desarrollado debido a su alta incidencia y prevalencia a medida que la población envejece. La fibrilación auricular (FA) y la fibrilación ventricular (FV) se encuentran entre las arritmias más complejas observadas en la práctica clÃnica. Las consecuencias clÃnicas de tales alteraciones arrÃtmicas incluyen el desarrollo de eventos cardioembólicos complejos en la FA, y repercusiones dramáticas debido a procesos fibrilatorios sostenidos que amenazan la vida infringiendo daño neurológico tras paro cardÃaco por FV, y que pueden provocar la muerte súbita cardÃaca (MSC). Sin embargo, a pesar de los avances tecnológicos de las últimas décadas, sus mecanismos intrÃnsecos se comprenden de forma incompleta y, hasta la fecha, las estrategias terapéuticas carecen de una base mecanicista suficiente y poseen bajas tasas de éxito.
Entre los mecanismos implicados en la inducción y perpetuación de arritmias cardÃacas, como la FA, se cree que las dinámicas de las fuentes focales y reentrantes de alta frecuencia, en sus diferentes modalidades, son las fuentes primarias que mantienen la arritmia. Sin embargo, se sabe poco sobre los atractores, asà como, de la dinámica espacio-temporal de tales fuentes fibrilatorias primarias, especÃficamente, las fuentes focales o rotacionales dominantes que mantienen la arritmia. Por ello, se ha desarrollado una plataforma computacional, para comprender los factores (activos, pasivos y estructurales) determinantes, y moduladores de dicha dinámica. Esto ha permitido establecer un marco para comprender la compleja dinámica de los rotores con énfasis en sus propiedades deterministas para desarrollar herramientas basadas en los mecanismos para ayuda diagnóstica y terapéutica.
Comprender los procesos fibrilatorios es clave para desarrollar marcadores y herramientas fisiológica- y clÃnicamente relevantes para la ayuda de diagnóstico temprano. EspecÃficamente, las propiedades espectrales y de tiempo-frecuencia de los procesos fibrilatorios han demostrado resaltar el comportamiento determinista principal de los mecanismos intrÃnsecos subyacentes a las arritmias y el impacto de tales eventos arrÃtmicos. Esto es especialmente relevante para determinar el pronóstico temprano de los supervivientes comatosos después de un paro cardÃaco debido a fibrilación ventricular (FV).
Las técnicas de mapeo electrofisiológico, el mapeo eléctrico y óptico cardÃaco, han demostrado ser recursos muy valiosos para dar forma a nuevas hipótesis y desarrollar nuevos enfoques mecanicistas y estrategias terapéuticas mejoradas. Esta tecnologÃa permite además el trabajo multidisciplinar entre clÃnicos y bioingenieros, para el desarrollo y validación de dispositivos y metodologÃas para identificar biomarcadores multi-dominio que permitan rastrear con precisión la dinámica de las arritmias identificando fuentes dominantes y atractores con alta precisión para ser dianas de estrategias terapeúticas innovadoras. Es por ello que uno de los objetivos fundamentales ha sido la implantación y validación de nuevos sistemas de mapeo en distintas configuraciones que sirvan de plataforma de desarrollo de nuevas estrategias terapeúticas. Aunque el mapeo panorámico es el método principal y más completo para rastrear simultáneamente biomarcadores electrofisiológicos, su adopción por la comunidad cientÃfica es limitada principalmente debido al coste elevado de la tecnologÃa. Aprovechando los avances tecnológicos recientes, nos hemos enfocado en desarrollar, y validar, sistemas de mapeo óptico de alta resolución para registro panorámico cardÃaco, utilizando modelos clÃnicamente relevantes para la investigación básica y la bioingenierÃa.[CA] Les arÃtmies cardÃaques són un problema important per als sistemes de salut del món desenvolupat a causa de la seva alta incidència i prevalença a mesura que la població envelleix. La fibril·lació auricular (FA) i la fibril·lació ventricular (FV), es troben entre les arÃtmies més complexes observades a la prà ctica clÃnica. Les conseqüències clÃniques d'aquests trastorns arÃtmics inclouen el desenvolupament d'esdeveniments cardioembòlics complexos en FA i repercussions dramà tiques a causa de processos fibril·latoris sostinguts que posen en perill la vida amb danys neurològics posteriors a la FV, que condueixen a una aturada cardÃaca i a la mort cardÃaca sobtada (SCD). Tanmateix, malgrat els avanços tecnològics de les darreres dècades, els seus mecanismes intrÃnsecs s'entenen de forma incompleta i, fins a la data, les estratègies terapèutiques no tenen una base mecanicista suficient i tenen baixes taxes d'èxit.
La majoria dels avenços en el desenvolupament de biomarcadors òptims i noves estratègies terapèutiques en aquest camp provenen de tècniques valuoses en la investigació de mecanismes d'arÃtmia. Entre els mecanismes implicats en la inducció i perpetuació de les arÃtmies cardÃaques, es creu que les fonts primà ries subjacents a l'arÃtmia són les fonts focals reingressants d'alta freqüència dinà mica i AF, en les seves diferents modalitats. Tot i això, se sap poc sobre els atractors i la dinà mica espaciotemporal d'aquestes fonts primà ries fibril·ladores, especÃficament les fonts rotacionals o focals dominants que mantenen l'arÃtmia. Per tant, s'ha desenvolupat una plataforma computacional per entendre determinants actius, passius, estructurals i moduladors d'aquestes dinà miques. Això va permetre establir un marc per entendre la complexa dinà mica multidomini dels rotors amb ènfasi en les seves propietats deterministes per desenvolupar enfocaments mecanicistes per a l'ajuda i la terà pia diagnòstiques.
La comprensió dels processos fibril·latoris és clau per desenvolupar puntuacions i eines rellevants fisiològicament i clÃnicament per ajudar al diagnòstic precoç. Concretament, les propietats espectrals i de temps-freqüència dels processos fibril·latoris han demostrat destacar un comportament determinista important dels mecanismes intrÃnsecs subjacents a les arÃtmies i l'impacte d'aquests esdeveniments arÃtmics. Mitjançant coneixements previs, processament de senyals, tècniques d'aprenentatge automà tic i anà lisi de dades, es va desenvolupar una puntuació de risc mecanicista a la aturada cardÃaca per FV.
Les tècniques de cartografia òptica cardÃaca i electrofisiològica han demostrat ser recursos inestimables per donar forma a noves hipòtesis i desenvolupar nous enfocaments mecanicistes i estratègies terapèutiques. Aquesta tecnologia ha permès durant molts anys provar noves estratègies terapèutiques farmacològiques o ablatives i desenvolupar mètodes multidominis per fer un seguiment precÃs de la dinà mica d'arrÃmies que identifica fonts i atractors dominants. Tot i que el mapatge panorà mic és el mètode principal per al seguiment simultani de parà metres electrofisiològics, la seva adopció per part de la comunitat multidisciplinà ria d'investigació cardiovascular està limitada principalment pel cost de la tecnologia. Aprofitant els avenços tecnològics recents, ens centrem en el desenvolupament i la validació de sistemes de mapes òptics de baix cost per a imatges panorà miques mitjançant models clÃnicament rellevants per a la investigació bà sica i la bioenginyeria.[EN] Cardiac arrhythmias are a major problem for health systems in the developed world due to their high incidence and prevalence as the population ages. Atrial fibrillation (AF) and ventricular fibrillation (VF), are amongst the most complex arrhythmias seen in the clinical practice. Clinical consequences of such arrhythmic disturbances include developing complex cardio-embolic events in AF, and dramatic repercussions due to sustained life-threatening fibrillatory processes with subsequent neurological damage under VF, leading to cardiac arrest and sudden cardiac death (SCD). However, despite the technological advances in the last decades, their intrinsic mechanisms are incompletely understood, and, to date, therapeutic strategies lack of sufficient mechanistic basis and have low success rates.
Most of the progress for developing optimal biomarkers and novel therapeutic strategies in this field has come from valuable techniques in the research of arrhythmia mechanisms. Amongst the mechanisms involved in the induction and perpetuation of cardiac arrhythmias such AF, dynamic high-frequency re-entrant and focal sources, in its different modalities, are thought to be the primary sources underlying the arrhythmia. However, little is known about the attractors and spatiotemporal dynamics of such fibrillatory primary sources, specifically dominant rotational or focal sources maintaining the arrhythmia. Therefore, a computational platform for understanding active, passive and structural determinants, and modulators of such dynamics was developed. This allowed stablishing a framework for understanding the complex multidomain dynamics of rotors with enphasis in their deterministic properties to develop mechanistic approaches for diagnostic aid and therapy.
Understanding fibrillatory processes is key to develop physiologically and clinically relevant scores and tools for early diagnostic aid. Specifically, spectral and time-frequency properties of fibrillatory processes have shown to highlight major deterministic behaviour of intrinsic mechanisms underlying the arrhythmias and the impact of such arrhythmic events. Using prior knowledge, signal processing, machine learning techniques and data analytics, we aimed at developing a reliable mechanistic risk-score for comatose survivors of cardiac arrest due to VF.
Cardiac optical mapping and electrophysiological mapping techniques have shown to be unvaluable resources to shape new hypotheses and develop novel mechanistic approaches and therapeutic strategies. This technology has allowed for many years testing new pharmacological or ablative therapeutic strategies, and developing multidomain methods to accurately track arrhymia dynamics identigying dominant sources and attractors. Even though, panoramic mapping is the primary method for simultaneously tracking electrophysiological parameters, its adoption by the multidisciplinary cardiovascular research community is limited mainly due to the cost of the technology. Taking advantage of recent technological advances, we focus on developing and validating low-cost optical mapping systems for panoramic imaging using clinically relevant models for basic research and bioengineering.Calvo Saiz, CJ. (2022). Novel Cardiac Mapping Approaches and Multimodal Techniques to Unravel Multidomain Dynamics of Complex Arrhythmias Towards a Framework for Translational Mechanistic-Based Therapeutic Strategies [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/182329TESI
The 2nd International Electronic Conference on Applied Sciences
This book is focused on the works presented at the 2nd International Electronic Conference on Applied Sciences, organized by Applied Sciences from 15 to 31 October 2021 on the MDPI Sciforum platform. Two decades have passed since the start of the 21st century. The development of sciences and technologies is growing ever faster today than in the previous century. The field of science is expanding, and the structure of science is becoming ever richer. Because of this expansion and fine structure growth, researchers may lose themselves in the deep forest of the ever-increasing frontiers and sub-fields being created. This international conference on the Applied Sciences was started to help scientists conduct their own research into the growth of these frontiers by breaking down barriers and connecting the many sub-fields to cut through this vast forest. These functions will allow researchers to see these frontiers and their surrounding (or quite distant) fields and sub-fields, and give them the opportunity to incubate and develop their knowledge even further with the aid of this multi-dimensional network
Cyber Security of Critical Infrastructures
Critical infrastructures are vital assets for public safety, economic welfare, and the national security of countries. The vulnerabilities of critical infrastructures have increased with the widespread use of information technologies. As Critical National Infrastructures are becoming more vulnerable to cyber-attacks, their protection becomes a significant issue for organizations as well as nations. The risks to continued operations, from failing to upgrade aging infrastructure or not meeting mandated regulatory regimes, are considered highly significant, given the demonstrable impact of such circumstances. Due to the rapid increase of sophisticated cyber threats targeting critical infrastructures with significant destructive effects, the cybersecurity of critical infrastructures has become an agenda item for academics, practitioners, and policy makers. A holistic view which covers technical, policy, human, and behavioural aspects is essential to handle cyber security of critical infrastructures effectively. Moreover, the ability to attribute crimes to criminals is a vital element of avoiding impunity in cyberspace. In this book, both research and practical aspects of cyber security considerations in critical infrastructures are presented. Aligned with the interdisciplinary nature of cyber security, authors from academia, government, and industry have contributed 13 chapters. The issues that are discussed and analysed include cybersecurity training, maturity assessment frameworks, malware analysis techniques, ransomware attacks, security solutions for industrial control systems, and privacy preservation methods
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