La forma urbana de la periferia y los conjuntos de vivienda pública [VP]. Madrid 1940 – 2010: de la comparsa al hito en la VP madrileña

Peer Reviewe

Shortest path computing in directed graphs with weighted edges mapped on random networks of memristors

Electronic version of an article published as [Fernandez, Carlos, Ioannis Vourkas, and Antonio Rubio. "Shortest Path Computing in Directed Graphs with Weighted Edges Mapped on Random Networks of Memristors." Parallel Processing Letters 30.01 (2020): 2050002] [https://doi.org/10.1142/S0129626420500024] © [copyright World Scientific Publishing Company] [https://www.worldscientific.com/worldscinet/ppl]To accelerate the execution of advanced computing tasks, in-memory computing with resistive memory provides a promising solution. In this context, networks of memristors could be used as parallel computing medium for the solution of complex optimization problems. Lately, the solution of the shortest-path problem (SPP) in a two-dimensional memristive grid has been given wide consideration. Some still open problems in such computing approach concern the time required for the grid to reach to a steady state, and the time required to read the result, stored in the state of a subset of memristors that represent the solution. This paper presents a circuit simulation-based performance assessment of memristor networks as SPP solvers. A previous methodology was extended to support weighted directed graphs. We tried memristor device models with fundamentally different switching behavior to check their suitability for such applications and the impact on the timely detection of the solution. Furthermore, the requirement of binary vs. analog operation of memristors was evaluated. Finally, the memristor network-based computing approach was compared to known algorithmic solutions to the SPP over a large set of random graphs of different sizes and topologies. Our results contribute to the proper development of bio-inspired memristor network-based SPP solvers.This work was supported by the Chilean research grants CONICYT REDES ETAPA INICIAL Convocatoria 2017 No. REDI170604, CONICYT BASAL FB0008, and by the Spanish MINECO and ERDF (TEC2016-75151-C3-2-R).Peer ReviewedPostprint (author's final draft

La forma urbana de la periferia y los conjuntos de vivienda pública [VP]. Madrid 1940 – 2010: de la comparsa al hito en la VP madrileña

Peer Reviewe

Detecting false testimonies in reputation systems using self-organizing maps

It has been demonstrated that rating trust and reputation of individual nodes is an effective approach in distributed environments in order to improve security, support decision-making and promote node collaboration. Nevertheless, these systems are vulnerable to deliberate false or unfair testimonies. In one scenario, the attackers collude to give negative feedback on the victim in order to lower or destroy its reputation. This attack is known as bad mouthing attack. In another scenario, a number of entities agree to give positive feedback on an entity (often with adversarial intentions). This attack is known as ballot stuffing. Both attack types can significantly deteriorate the performances of the network. The existing solutions for coping with these attacks are mainly concentrated on prevention techniques. In this work, we propose a solution that detects and isolates the abovementioned attackers, impeding them in this way to further spread their malicious activity. The approach is based on detecting outliers using clustering, in this case self-organizing maps. An important advantage of this approach is that we have no restrictions on training data, and thus there is no need for any data pre-processing. Testing results demonstrate the capability of the approach in detecting both bad mouthing and ballot stuffing attack in various scenarios

Determinación del coeficiente de rozamiento grano-pared en silos de pared corrugada mediante el método de los elementos discretos

El comportamiento de los materiales granulares almacenados en silos se ve afectado por varios parámetros, tanto aquellos característicos del material como de la geometría del silo. La determinación del coeficiente de rozamiento pared-partícula es uno de los parámetros de mayor importancia, siendo habituales en su determinación el uso de ensayos de corte directo. En el presente trabajo se estudia dicho coeficiente para el supuesto de una pared corrugada, el cual, teóricamente, debe representar a un valor efectivo que depende tanto del coeficiente de rozamiento grano-pared (para el caso de una pared lisa) y el ángulo de rozamiento interno del material. La determinación del rozamiento efectivo se ha realizado a través de la simulación por elementos discretos de un ensayo de corte sobre una pared corrugada. Los valores obtenidos han sido comparados con las prescripciones expuestas en la normativa vigente. La potencialidad del método de los elementos discretos permite el estudio de diversas configuraciones geométricas de la pared corrugada de los silos sin necesidad de realizar ensayos de laboratorio. Esto permitirá, en trabajos sucesivos, investigar la influencia de muy diversos factores en el valor del rozamiento efectivo grano-pared en este tipo de paredes. The mechanical behaviour of granular materials stored in silos is affected by numerous parameters, some of them being related to the characteristic of the stored materials and others to the geometry of the silo. The determination of the particle-wall friction coefficient (or wall friction) is of great importance and direct shear tests are usually conducted in order to obtain its value. In this work this variable is analysed for the case of a corrugated wall. This value is expected to be an effective value between the particle-wall friction coefficient (obtained for a flat wall) and the internal friction coefficient of the material under study. The effective wall friction determination has been carried out by using a discrete element model to simulate a direct shear test on a corrugated wall. The values obtained have been compared with prescriptions given in the current standards. The potential of the discrete element method allows different geometries of the silo corrugated wall to be considered without the necessity of developing laboratory tests. In future works it will allow the influence of numerous parameters on the effective wall friction in corrugated walls to be studied

AMISEC: Leveraging Redundancy and Adaptability to Secure AmI Applications

Security in Ambient Intelligence (AmI) poses too many challenges due to the inherently insecure nature of wireless sensor nodes. However, there are two characteristics of these environments that can be used effectively to prevent, detect, and confine attacks: redundancy and continuous adaptation. In this article we propose a global strategy and a system architecture to cope with security issues in AmI applications at different levels. Unlike in previous approaches, we assume an individual wireless node is vulnerable. We present an agent-based architecture with supporting services that is proven to be adequate to detect and confine common attacks. Decisions at different levels are supported by a trust-based framework with good and bad reputation feedback while maintaining resistance to bad-mouthing attacks. We also propose a set of services that can be used to handle identification, authentication, and authorization in intelligent ambients. The resulting approach takes into account practical issues, such as resource limitation, bandwidth optimization, and scalability

Do Economic Crises Always Undermine Trust in Others? The Case of Generalized, Interpersonal, and In-Group Trust

After the global economic collapse triggered by the Great Recession, there has been an increased interest in the potential psychological implications of periods of economic decline. Recent evidence suggests that negative personal experiences linked to the economic crisis may lead to diminished generalized trust (i.e., the belief that most of the people of the society are honest and can be trusted). Adding to the growing literature on the psychological consequences of the economic crisis, we propose that the perceived personal impact of the economic crisis not only would undermine generalized trust but also may lead to increased interpersonal trust (i.e., directed to specific and close people) and depersonalized in-group trust [i.e., directed to individuals who, while strangers, belong to the same group (e.g., social class)]. Across three studies (N = 1379), we tested these central hypotheses and ascertained whether the perceived personal impact of the crisis would predict these types of trust (assessed using questionnaire and behavioral measures) independent of individuals’ socioeconomic status. Non-experimental data from Study 1 revealed that a higher perceived personal impact of the crisis is related to lower levels of generalized trust and higher levels of interpersonal trust. These effects were independent of participants’ socioeconomic status. Non-experimental data from Study 2 replicated the findings obtained in Study 1 and also showed a positive association between the perceived personal impact of the crisis and depersonalized in-group trust.This research was supported by the Spanish Ministry of Economy and Competitiveness [Ref. PSI2014-59659-R and Ref. PSI- 2017-83966-R (MINECO/AEI/FEDER/UE)] and by a Grant (FPU13/02478) from the FPU Program of the Spanish Ministry of Education, Culture, and Sport

A support vector machine as an estimator of mountain papaya ripeness using resonant frequency or frequency centroid

Mountain papaya fruits (Vasconcella pubescens) were tested for firmness with a nondestructive acoustic method for 14 days after harvest. The response of each fruit was analyzed with the Fourier transform to obtain a firmness index (FI) based on the second resonant frequency and with the Short Time Fourier Transform (STFT) to obtain a spectrogram frequency centroid (FC) index. The indexes were processed with a support vector machine (SVM) learning procedure in which days since harvest was taken as the basic truth of ripeness which the measured indexes attempt to estimate. The analysis of the results demonstrate that different groupings of the days into classes to be estimated give widely varying recognition rates and that the best rates are obtained when the classes are delimited using prior knowledge.IFIP International Conference on Artificial Intelligence in Theory and Practice - Industrial Applications of AIRed de Universidades con Carreras en Informática (RedUNCI

Alterations in Energy Partitioning and Methane Emissions in Murciano-Granadina Goats Fed Orange Leaves and Rice Straw as a Replacement for Beet Pulp and Barley Straw

[EN] Reducing methane emissions in ruminants with the recycling of agro-industrial by-products is of great importance today. Pruning waste from citrus trees is currently burned or incorporated into soil. Regarding rice straw, this waste is traditionally eliminated through controlled burning, releasing into the atmosphere large amounts of greenhouse gases as well. The aim of this study was to convert this recovered waste into a new animal feed capable of reducing methane emissions in ruminants. The interest in use waste by-products for ruminant nutrition is increasing. Therefore, we replace the beet pulp and cereal straw from dry-non-pregnant goats' diet with orange leaves and rice straw with the objective of studying their effect upon intake, digestibility, energy efficiency, carbon and nitrogen balance, and methane emissions. Considering the huge quantities of crops by-products and pruning waste such as rice straw and citrus leaves produced annually worldwide, and their potential pollution capacity, recycling as feed for livestock is an alternative. The objective was to study these by-products effect on energy balance and methane emissions in 10 Murciano-Granadina goats at maintenance. The control diet (CTR) included barley straw and beet pulp while the experimental diet (ORG) consisted of rice straw and orange leaves. Differences were found for energy intake (248 kJ/kg of BW0.75 greater for CTR than ORG). The intake of metabolizable energy was 199 kJ/kg of BW0.75 lower in ORG than CTR, and the energy efficiency was higher with CTR (0.61) than ORG (0.48). Protein retained in the body was 9 g/goat greater with CTR than ORG, and fat retention in the body was approximately 108 g/goat greater with CTR than ORG. Despite more unfavorable energy balance in response to feeding ORG than CTR, the retention of body energy was always positive. Reductions in CH4 emissions were detected when goats were fed ORG diet (from 22.3 to 20.0 g/d). Overall results suggested that feeding orange leaves and rice straw was effective in reducing CH4 emissions without adversely affecting energy balance.This study was supported by LIFE Project, Spain (ref. LIFE2016/CCM/ES/000088 LOW CARBON FEED).Romero Rueda, T.; Palomares Carrasco, JL.; Moya, V.; Loor, JJ.; Fernández Martínez, CJ. (2021). Alterations in Energy Partitioning and Methane Emissions in Murciano-Granadina Goats Fed Orange Leaves and Rice Straw as a Replacement for Beet Pulp and Barley Straw. Animals. 11(1):1-14. https://doi.org/10.3390/ani11010038S11411