On the Feasibility of Low-Cost Wearable Sensors for Multi-Modal Biometric Verification

Biometric systems designed on wearable technology have substantial differences from traditional biometric systems. Due to their wearable nature, they generally capture noisier signals and can only be trained with signals belonging to the device user (biometric verification). In this article, we assess the feasibility of using low-cost wearable sensors—photoplethysmogram (PPG), electrocardiogram (ECG), accelerometer (ACC), and galvanic skin response (GSR)—for biometric verification. We present a prototype, built with low-cost wearable sensors, that was used to capture data from 25 subjects while seated (at resting state), walking, and seated (after a gentle stroll). We used this data to evaluate how the different combinations of signals affected the biometric verification process. Our results showed that the low-cost sensors currently being embedded in many fitness bands and smart-watches can be combined to enable biometric verification. We report and compare the results obtained by all tested configurations. Our best configuration, which uses ECG, PPG and GSR, obtained 0.99 area under the curve and 0.02 equal error rate with only 60 s of training data. We have made our dataset public so that our work can be compared with proposals developed by other researchers.This work was supported by the CAM grant S2013/ICE-3095 (CIBERDINE: Cybersecurity, Data, and Risks) and by the MINECO grant TIN2016-79095-C2-2-R (SMOG-DEV—Security mechanisms for fog computing: advanced security for devices)

A Survey of Wearable Biometric Recognition Systems

The growing popularity of wearable devices is leading to new ways to interact with the environment, with other smart devices, and with other people. Wearables equipped with an array of sensors are able to capture the owner’s physiological and behavioural traits, thus are well suited for biometric authentication to control other devices or access digital services. However, wearable biometrics have substantial differences from traditional biometrics for computer systems, such as fingerprints, eye features, or voice. In this article, we discuss these differences and analyse how researchers are approaching the wearable biometrics field. We review and provide a categorization of wearable sensors useful for capturing biometric signals. We analyse the computational cost of the different signal processing techniques, an important practical factor in constrained devices such as wearables. Finally, we review and classify the most recent proposals in the field of wearable biometrics in terms of the structure of the biometric system proposed, their experimental setup, and their results. We also present a critique of experimental issues such as evaluation and feasibility aspects, and offer some final thoughts on research directions that need attention in future work

Closing the residential energy loop: Grey-water heat recovery system for domestic hot water production based on heat pumps

[EN] Passive houses linked to more efficient heating and cooling technologies have been one of the focus in last years. However, to close the loop of the building sector, there is still one open source: wasted heat from grey water. This paper addresses the potentiality of the wasted heat from grey water as a heat source to produce domestic hot water (DHW) based on a heat pump system (HP). A heat pump optimized for these applications, a heat recovery heat exchanger and two variable volume storage tanks compose the system. The main objective of this work is to determine the potential recovery of the wasted heat in order to minimize the building energy consumption. Design guidelines of the components and the analysis of an optimum operation algorithm of the system have been performed in order to minimize CO2 emissions. In addition, an evaluation of the potential heat recovery of the wasted heat is included. As an example, that methodology has been applied to 20 dwellings. Based on that case, the obtained results demonstrate that by recovering 80% of the available recovery heat, the total demand of DHW is satisfied with high levels of comfort and efficiency.Part of the work presented was carried out by Estefania Hervas Blasco with the financial support of a PhD scholarship from the Spanish government SFPI1500 x074478XV0. The authors would like also to acknowledge the Spanish `Ministerio de Economia Y Competitividad', through the project "Maximizacion de la Eficiencia Y Minimizacion del Impacto Ambiental de Bombas de Calor Para la Descarbonizacion de la Calefaccion/ACS EN Los Edificios de Consumo Casi Nulo" with the reference ENE2017-83665-C2-1-P for the given support.Hervás-Blasco, E.; Navarro-Peris, E.; Corberán, JM. (2020). Closing the residential energy loop: Grey-water heat recovery system for domestic hot water production based on heat pumps. Energy and Buildings. 216:1-15. https://doi.org/10.1016/j.enbuild.2020.109962S115216García-Álvarez, M. 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From tortoises to elephants: the impact of elephants in the broad spectrum diet at Bolomor Cave (MIS 9–5 Spain)

Animal exploitation strategies have occupied a prominent place in the debate about the timing and nature of the modern human behavior. The discussions have basically focused on the ability to make an intensive use of seasonal resources, to hunt large or dangerous animals and to exploit fast-moving small game. Both large-sized herbi- vores and small prey are therefore considered a key variable to assess fundamental aspects of the evolution of subsistence strategies. In this work we present zooarchaeological data from the Middle Pleistocene site of Bolomor Cave (Valencia, Spain, MIS 9–5e), which has been interpreted as a habitat place. Its taxonomic representation extends from very large-sized herbivores (elephants, hippopot- amuses and rhinoceroses) to very small-sized an- imals (lagomorphs, birds and tortoises), or even exotic animals like macaque. Elephant specimens are documented along the stratigraphic sequence from level Ia, IV, V, XII, XIII and XVII. Most of the elephant individuals are immature and partial- ly represented. Nevertheless, the bone fragments recovered coincide with the general anatomical profile of the medium- and large-sized ungulates, which is mainly characterized by stylopodials, zeu- gopodials and mandibles. Evidence of human use of small prey from the earliest phases of site oc- cupation (sublevel XVIIc) is also attested in form of cut marks, intentional bone breakages, human tooth marks and burning patterns. The exploita- tion of small prey, alongside to the very large game identified at the site, indicates a generalist human behavior based on a broad spectrum diet (BSD), which contributes to document the diversity in the lifestyles of the human communities of the Euro- pean Middle Pleistocene.The symposium and the volume "Human-elephant interactions: from past to present" were funded by the Volkswagen Foundation

La dieta cárnica en la Cova del Bolomor (Valencia, España). Una estrategia de diversificación en el Pleistoceno Medio europeo (mis 9-5e).

La diversificación de la subsistencia -su potencial- en periodos anteriores al Paleolítico superior ha configurado durante los últimos 40 años uno de los principales temas de discusión prehistórica en Europa. En medio de este debate, la Cova del Bolomor, con una cronología de entre 350 y 100 mil años antes del presente, surge como una de las evidencias más claras y antiguas del consumo sistemático de pequeños animales (e.g., lagomorfos, aves, tortugas) por homínidos anteriores a Homo sapiens. Los datos de Bolomor plantean la necesidad de reconsiderar aspectos e interrelacionar factores para explicar la diversificación de esta subsistencia en momentos anteriores al Paleolítico superior. En este estudio, presentamos los datos zooarqueológicos procedentes de tres niveles de la secuencia estratigráfica de Bolomor (XVII, XI y IV) con el objetivo de aportar una visión diacrónica de la dieta cárnica en este enclave. Los datos proporcionados por Bolomor permiten plantear que los cambios en la dieta humana no fueron lineales en el tiempo y en el espacio, sino que probablemente estuvieron condicionados por múltiples factores, en los que el patrón ocupacional, la diversidad del comportamiento y de forma significativa, las características medioambientales locales desempeñaron un papel importante

Hindering data theft with encrypted data trees

Data theft is a major threat for modern organizations with potentially large economic consequences. Although these attacks may well originate outside an organization’s information systems, the attacker—or else an insider—must even-tually make contact with the system where the information resides and extract it. In this work, we propose a scheme that hinders unauthorized data extraction by modifying the basic file system primitives used to access files. Intuitively, our proposal emulates the chains used to protect valuable items in certain clothing shopping centers, where shoplifting is prevented by forcing the thief to steal the whole rack of items. We achieve this by encrypting sensitive files using nonces (i.e., pseudorandom numbers used only once) as keys. Such nonces are available, also in encrypted form, in other objects of the file system. The system globally resembles a distributed Merkle hash tree, in such a way that getting access to a file requires previous access to a number of other files. This forces any potential attacker to extract not only the targeted sensitive information, but also all the files chained to it that are necessary to compute the associated key. Further-more, our scheme incorporates a probabilistic rekeying mechanism to limit the damage that might be caused by patient extractors. We report experimental results measuring the time overhead introduced by our proposal and compare it with the effort an attacker would need to successfully extract information from the system. Our results show that the scheme increases substantially the effort required by an insider, while the introduced overhead is feasible for standard computing platforms

Exergy analysis on a heat pump working between a heat sink and a heat source of finite heat capacity rate

[EN] The optimum performance of a pure subcritical refrigeration cycle depends significantly on the temperature lift of the heat source and sink. Therefore, the maximization of the system efficiency has to be linked to them. This paper shows an exergy analysis of each heat pump component (condenser, evaporator, expansion valve and compressor) considering that the heat source and sink are not at constant temperature. The performed study shows the components with more possibilities for improvement. Based on this analysis, the optimization of cycle parameters like subcooling and superheat as a function of the external conditions have been done. In addition, this work has demonstrated that the components having a higher influence in the system irreversibility's depends significantly on the temperature lift of the secondary fluids. Finally, the obtained results show potentials improvements of the efficiency up to 23% if the system is able to operate in the optimal subcooling and superheat.Part of the results of this study were developed in the mainframe of the FP7 European project 'Next Generation of Heat Pumps workingwith natural fluids' (NxtHPG). Part of the work presented was carried by Miquel Pitarch with the financial support of a PhD scholarship from the Universitat Politecnica de Valencia. Part of the work presented was carried by Estefania Hervas-Blasco with the financial support of a Ph.D. scholarship from the Spanish government SFPI1500X074478XV. The authors would like also to acknowledge the Spanish 'MINISTERIO DE ECONOMIA Y COMPETITIVIDAD', through the Project ENE2017-83665-C2-1-P, "Maximizacion de la Eficiencia y Minimizacion del Impacto Ambiental de Bombas de Calor para la descarbonizacion de la calefaccion/ACS en los proximos edificios de consumo energetico casi nulo" for the given support.Pitarch, M.; Hervás-Blasco, E.; Navarro-Peris, E.; Corberán, JM. (2019). Exergy analysis on a heat pump working between a heat sink and a heat source of finite heat capacity rate. International Journal of Refrigeration. 99:337-350. https://doi.org/10.1016/j.ijrefrig.2018.11.044S3373509

The Anthropogenic Use of Firewood During the European Middle Pleistocene: Charcoal Evidence from Levels XIII and XI of Bolomor Cave, Eastern Iberia (230- 160 ka)

Human control of fire is a widely debated issue in the field of Palaeolithic archaeology, since it involved significant technological innovations for human subsistence. Although fire evidence has been the subject of intense debate regarding its natural or anthropogenic nature, most authors agree that combustion structures represent the most direct evidence of human control of fire. Wood charcoal fragments from these contexts represent the fuel remains that result from humans' collection of firewood, which means they can reveal significant behavioural and palaeoenvironmental information relevant to our understanding of Middle Palaeolithic societies. In this work, we present anthracological data derived from combustion structure 2 (level XIII, ca. 230 ka, MIS 7) and combustion structure 4 (level XI, ca. 160 ka, MIS 6) from Bolomor Cave, which are chronologically among the earliest combustion structures found in Europe. The present work discusses how the presence of black pine and / or scots pine in both levels sheds light on the characterisation of the local landscape. Additional analyses focussing on the pre- and post-depositional processes affecting charcoal preservation point to biodegradation patterns. The aim of this work is to provide the first discussion concerning the anthracological data derived from Bolomor Cave in order to contribute to the general debate regarding the use of fire during the European Middle Pleistocene

Mejoras y valoración tras un programa de ejercicio específico para adultos mayores crónicos/paliativos

After analysing the impact of a cognitively oriented multicomponent home-based exercise training program on independence, perceived health status, and lower limb strength in a group of multimorbid and/or palliative older patients (MPO-P), we studied the associations between improvements following training and the participants and health personnel’s opinion of the program. 13 MPO-P, (80.15+4.20 years) completed four months of training progressing in autonomy (from two supervised sessions and one autonomous weekly -60min session-, to two autonomous and one supervised). This was followed by fourautonomous (detraining) weeks with a recommendation to continue the exercises. Volume and intensity were increased by introducing more global exercises, with a greater neuromuscular load and double tasks, and a shorter resting interval. No exercise was repeated during the session (EFAM-UV©). Independence (Barthel) and perceived health (physical SF-36, with no changes in the mental domain), were improved after supervised training, with a tendency to improve in strength (sitting and standing for 30-s) and perceived health (total SF-36). This effect was maintained after the autonomous detraining phase, with a very favourable final perception by both patients and health personnel, as indicated in questionnaires. The gain in independence correlated negatively with the users’perception, but this requirement ensured the improvement. There was no association between perceived health and the evaluation of the program.Tras analizar el impacto de un programa de entrenamiento domiciliario multicomponente, con orientación cognitiva, sobre independencia, percepción subjetiva de salud, y fuerza del miembro inferior en un grupo de adultos mayores crónicos multimórbidos y/o paliativos (MCM-Ps), se estudiaron las asociaciones entre las mejoras obtenidas y la valoración del programa de participantes y personal sanitario. 13 MCM-Ps (80.15+4.20 años) completaron cuatro meses de entrenamiento progresando en autonomía (de dos sesiones supervisadas y una autónoma semanalmente -60 min/sesión-, a dos autónomas y una supervisada). Le siguieron cuatro semanas autónomas (desentrenamiento) con recomendación de ejercicio. El volumen y la intensidad se aumentaron introduciendo más ejercicios integrales, con mayor carga neuromuscular y doble tarea, y menor tiempo de descanso entre ellos, sin repetirlos en la sesión (EFAM-UV©). Independencia (Barthel) y salud percibida (SF-36 físico, sin cambios en dominio mental) mejoraron tras el entrenamiento supervisado, con tendencia a la mejora de fuerza (sentarse y levantarse 30-s) y la salud percibida (SF-36total). El efecto permaneció tras la fase autónoma/desentrenamiento, con una percepción final muy favorable de pacientes y personal sanitario-determinada mediante cuestionarios-. La ganancia en independencia correlacionó negativamente con la valoración del usuario, pero esta exigencia aseguró su mejora. No hubo asociación entre salud percibida y valoración del programa.The study was financed by Vali+D Grant Nº ACIF/2014/137)

Optimal sizing of a heat pump booster for sanitary hot water production to maximize benefit for the substitution of gas boilers

[EN] Heat recovery from water sources such as sewage water or condensation loops at low temperatures (usually between 10 and 30 °C) is becoming very valuable. Heat pumps are a potential technology able to overcome the high water temperature lift of the Sanitary Hot Water (SHW) application (usually from 10 °C to 60 °C with COPs up to 6). This paper presents a model to find the optimal size of a system (heat pump and recovery heat exchanger) based on water sources to produce SHW compared to the conventional production with a gas boiler in order to maximize the benefit. The model includes a thermal and economic analysis for a base case and analyzes the influence of a wide set of parameters which could have a significant influence. Even the uncertainties involved, results point out considerable benefits from this substitution based on the capacity of the system. Thus, demonstrating the importance of the optimal size analysis before an investment is done.Part of the work presented was carried by Estefania Hervas Blasco with the financial support of a PhD scholarship from the Spanish government SFPI1500X074478XV0. Part of the work presented was carried by Miguel Pitarch-Mocholi with the financial support of a PhD scholarship from the Universitat Politecnica de Valencia. The authors would like also to acknowledge the Spanish 'MINISTERIO DE ECONOMIA Y COMPETITIVIDAD', through the project ref-ENE2014-53311-C2-1-P-AR "Aprovechamiento del calor residual a baja temperatura mediante bombas de calor para la produccion de agua caliente" for the given supportHervas-Blasco, E.; Pitarch, M.; Navarro-Peris, E.; Corberán, JM. (2017). Optimal sizing of a heat pump booster for sanitary hot water production to maximize benefit for the substitution of gas boilers. Energy. 127:558-570. https://doi.org/10.1016/j.energy.2017.03.13155857012