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Title: Agrupación submuestreada operando en modo fractón utilizando antenas microstrip inspiradas en el fractal de Sierpinski
Authors: Anguera Pros, Jaume; Montesinos, Gemma; Puente Baliarda, Carles; Borja, C.; Soler, Jordi
Abstract: A high-directivity microstrip array using mul-
tilevel elements based on a fractal geometry is theoretically
compared with one using a circular patches. Within the
same electrical area, the same directivity can be obtained.
However, the number of elements for the fractal-based ar-
ray is 2.84 times less, reducing the complexity of the feeding
network and overall array
Title: Comportamiento multifrecuencia en una antena microstrip mediante multiples elementos parásitos
Authors: Font, Gisela; Anguera Pros, Jaume; Puente Baliarda, Carles; Borja, Carmen; Soler, Jordi
Abstract: A multifrequency microstrip patch antenna
comprising a driven patch and a plurality of parasitic el-
ements placed underneath a driven patch is proposed. The
antenna features a multifrequency behavior (5 operating
band) with similar performance.
Title: Antena microstrip dual en frecuencia basada en el triángulo fractal de Sierpinski
Authors: Anguera Pros, Jaume; Martinez, Enrique; Puente Baliarda, Carles; Borja, C.; Soler, Jordi
Abstract: A dual-frequency antenna based on the
Sierpinski fractal with two parasitic patches to enhance the
impedance bandwidth is presented. An electrical circuit
model formed by RLC resonators is proposed to learn
about the antenna physical behavior and to achieve the
dual band operation minimizing a trial-and-error
numerical/ measurement proofs. The antenna has been
designed using a MoM commercial code and has been
experimentally tested, obtaining two bands with a
bandwidth around 7%(SWR<2) and similar radiation
pattern and gain.
Title: A comparative experimental study of gross alpha methods in natural waters
Authors: Montaña Gurrera, Montserrat; Fons, J; Corbacho, J.A.; Camacho García, Antonia; Zapata-García, D; Guillen, J.; Serrano Carreño, M. Isabel; Tent, J; Baeza, A; Llauradó, Montserrat; Vallés, I
Abstract: The aim of the present work was to compare the results obtained with gross alpha methods such as
evaporation, co-precipitation and total evaporation by liquid scintillation counting and to check whether
these results are representative of the real total alpha activity concentration on the sample. The study
was carried out on eight natural waters with very different radioactive characteristics. For all the samples
U), radium (
Th isotopes were also assayed by
using radiochemical separation and alpha spectrometry in order to determine the sum of the activities of
these alpha emitters.
Precision (expressed as relative standard deviation) was below 28% for evaporation and below 18% for
co-precipitation. In the case of total by liquid scintillation counting it was below 10% for samples with
Total Alpha activity above 0.1 Bq/L (this value is about three times the MDA). Furthermore, for most of the
studied waters, the Total Alpha activity and the gross alpha activity determined by the three methods
were comparable. The obtained bias by the evaporation, co-precipitation, and total evaporation by liquid
scintillation counting methods was lower than 40%, 25% and 20%, respectively.
The ANOVA test was applied to
nd out if there was signi
cant variability among the methods. For the
samples with the most common radiochemical characteristics there were no signi
among the three studied methods. However differences were detected for samples with a high saline
content or with a very low activity level.
Title: Estudio del manejo del plomo en establecimientos de tipografía, reconstrucción de baterías y recicladores de chatarra en el Departamento del Quindío, Colombia
Authors: Gomez, Milena E.; Cremades Oliver, Lázaro Vicente
Abstract: En el 2011, existían en el departamento del Quindío aproximadamente
95 establecimientos comerciales, dedicados a tipografías, reciclaje
de chatarra, y reconstrucción de baterías en donde los trabajadores
tenían contacto con metales pesados como el plomo (Pb) sin protección
alguna. De estos 95 establecimientos, participaron en el estudio
el 55% y de estas empresas se encontró que el 80.65% era economía
informal, es decir, independientes, unifamiliares y sin afiliación a la
Seguridad Social Integral (Salud, Pensión y Riesgos laborales). El
riesgo más importante en estos trabajadores es la manipulación consciente
o inconsciente del plomo. El Pb se utiliza en su forma metálica
y en aleaciones, siendo de los pocos metales que es tóxico por sí
mismo. El Pb no tiene una función biológica útil en el hombre, por
lo que es preocupante que se hable de cifras normales de este metal
en la sangre. La exposición no controlada del Pb genera graves daños
a nivel sistémico del organismo, tales como: disminución de la capacidad
física, fatiga, trastornos del sueño, cefalea, dolores de huesos y
músculos, dolores abdominales, disminución del apetito y en casos
muy graves se produce daño en riñones e incluso la muerte.
Title: Computation of azimuthal waves and their stability in thermal convection in rotating spherical shells with application to the study of a double-Hopf bifurcation
Authors: Sánchez Umbría, Juan; García González, Fernando; Net Marcé, Marta
Abstract: A methodology to compute azimuthal waves, appearing in thermal convection of a pure fluid contained in a rotating spherical shell, and to study their stability is presented. It is based on continuation, Newton-Krylov, and Arnoldi methods. An application to the study of a double-Hopf bifurcation of the basic state is shown for Ekman and Prandtl numbers E=10?4 and ?=0.1, respectively, radius ratios ??[0.32,0.35], Rayleigh numbers R?[1.8×105,6×105], and nonslip and perfectly conducting boundary conditions. The knowledge of the bifurcation diagrams, including the unstable solutions, allows one to understand the coexistence of stable thermal Rossby waves of different azimuthal wave numbers at some parameter regions, and the origin of some new intermittent solutions found, as trajectories close to heteroclinic chains. Moreover, the structure of the eigenfunctions at the secondary bifurcations explains the existence of the amplitude and shape modulated waves.
Title: Analysis of the dynamic short-circuit resistance in organic bulk-heterojunction solar cells: relation to the charge carrier collection efficiency
Authors: Voz Sánchez, Cristóbal; Puigdollers i González, Joaquim; Asensi López, José Miguel; Galindo Lorente, Sergi; Cheylan, S.; Pacios, R.; Ortega Villasclaras, Pablo Rafael; Alcubilla González, Ramón
Abstract: This work studies the charge carrier collection efficiency in organic bulk-heterojunction solar cells based on polymer:fullerene blends. An equivalent circuit with a specific recombination term is proposed to describe the behavior of this type of devices. It is experimentally shown that this recombination term determines the slope of the current–voltage characteristic at the short-circuit condition. The variation of this dynamic resistance with the light intensity can be interpreted considering a dominant first-order recombination process. Finally, an analytical model under a constant electric field approximation is presented that can be used to calculate the charge carrier collection efficiency of the device. This model can be also used to estimate an effective mobility–lifetime product, which is characteristic of the quality of the active layer.
Title: Dielectric, thermal, and mechanical properties of acrylonitrile butadiene styrene reinforced with used tires
Authors: Mujal Rosas, Ramón María; Òrrit Prat, Jordi; Ramis Juan, Xavier; Marín Genescá, Marcos; Rahhali, Ahmed
Abstract: Mass production of tires as well as their storage or elimination is
a real environmental problem. Various methods for recycling of tires are currently
used, such as mechanical grinding, which separates vulcanized rubber, steel, and
fibers from tires. Rubber is, then, used in several industrial applications such as
flooring, insulations, and footwear. This paper focuses on a new application for
old used tires (ground tire rubber, GTR). Tire dust and acrylonitrile butadiene styrene (ABS) have been mixed, and the maximum accepted concentration of
GTR can be attained while keeping dielectric, thermal, and mechanical properties
within acceptable limits, and therefore their possible industrial application will be
in manufacturing of, for example, dielectrics for capacitors, low-voltage electric
fences or electrical cable pipes, and trays. Actually, tire dust with particle sizes
<700 ?m has been classified into three different groups depending on the particle
sizes (p < 200, 200< p < 500, and p > 500 ?m). Afterward, ABS has been mixed
with different concentrations of GTR, i.e., 5%, 10%, 20%, 50% and 70%, to
establish its properties through thermal, mechanical, and dielectric tests. Finally,
the fracture surfaces of the composite samples have been evaluated by using
scanning electron microscopy.
Description: Cop. 2012 Wiley Periodicals, Inc. Adv Polym Techn
32: E399–E415, 2013; View this article online at wileyonlinelibrary.com. DOI
Title: Diseño de antenas multibanda para telefonía móvil mediante la manipulación del plano de masa
Authors: Picher, C.; Anguera Pros, Jaume; Cabedo, Arnau; Ribó, Miquel; Pijoan, Joan L.; Puente Baliarda, Carles
Title: Influence of the isothermal cure temperature on the nanostructure and thermal properties of an epoxy layered silicate nanocomposite
Authors: Shiravand, Fatemeh; Hutchinson, John M.; Calventus Solé, Yolanda
Abstract: The cure kinetics of triglycidyl p-amino phenol (TGAP) epoxy resin with a diamine (4,4-diamino diphenyl sulphone [DDS]), reinforced with montmorillonite (MMT), has been studied by differential scanning calorimetry. The isothermal cure reaction consists of two parts: a rapid intra-gallery reaction, attributed to homopolymerization of the TGAP catalyzed by the MMT and the extra-gallery cross-linking reaction of the TGAP with the DDS. Increasing cure temperature promotes the intra-gallery reaction, which should promote an exfoliated nanostructure; this is confirmed by transmission electron microscopy. These results indicate that this system (TGAP/DDS/MMT) is an excellent candidate for achieving exfoliated polymer-layered silicate nanocomposites and identifies a protocol for optimizing the degree of exfoliation.
Title: Intra- and extra-gallery reactions in tri-functional epoxy polymer layered silicate nanocomposites
Authors: Hutchinson, John M.; Shiravand, Fatemeh; Calventus Solé, Yolanda
Abstract: Achieving a high degree of exfoliation in epoxy-based polymer layered silicate (PLS) nanocomposites is crucial to their successful industrial application, but has hitherto proved elusive. In this work, a system is presented which shows significant promise in this respect. The isothermal cure of PLS nanocomposites based upon a tri-functional epoxy resin (TGAP) has been studied by DSC, and displays two exothermic peaks. The first peak, very rapid, relates to a homopolymerization reaction within the intra-gallery regions, while the second peak reflects the bulk crosslinking reaction. The occurrence of the intra-gallery reaction before the bulk reaction enhances the degree of exfoliation in the cured nanocomposite. Furthermore, pre-conditioning the resin/clay mixture before adding the curing agent and effecting the isothermal cure also allows a greater extent of intra-gallery reaction to occur before the extra-gallery epoxy-amine reaction. Consequently, this system results in a high degree of exfoliation, as revealed by transmission electron microscopy.
Title: Tara (Caesalpinia spinosa): the sustainable source of tannins for innovative tanning processes
Authors: Castell, Joan Carles; Sorolla, Silvia; Jorba, Montse; Aribau, Joaquim; Bacardit Dalmases, Anna; Ollé Otero, Lluís
Abstract: This study considers the fruit of the tara tree as a sustainable source for tanning agents and proposes alternatives to the commercial mineral salts and vegetable extracts to comply with environment and social concerns. Tara tannins have been used in retanning formulas in leather processing and its properties are well known. This work aims to optimize formulations using tara as a pre-tanning agent. Combinations with a naphthalene sulphonic syntan are used to obtain an innovative wet-white recipe in which shrinkage temperature, tensile strength, tensile elongation, tear load and lightfastness properties are considered as statistical variables
Title: Doing research in business & management: an essential guide to planning your project
Authors: Berbegal Mirabent, Jasmina
Title: GPON unbundling for multioperator access
Authors: Carmona, David; Prat Gomà, Josep Joan; Tomkos, Ioannis; PILAR, SANCHEZ MARCO
Abstract: This work aims at considering different unbundling options for the Local Loop Unbundling (LLU) in order to provide multi-operator access and consider the economical impact for the FTTH NGA entrants to deploy such alternatives. We show that deploying WDM networks is an efficient strategy to perform LLU while upgrading the GPON network for the new era where high bandwidths are necessary for satisfying customers' demand. In areas with high population density, WDM techniques are the most suitable for entrant operators to access the incumbent's network and provide service.
Title: A lightweight algorithm for traffic filtering over sliding windows
Authors: Sanjuàs Cuxart, Josep; Barlet Ros, Pere; Solé Pareta, Josep; Andriuzzi, Gabriella
Abstract: The problem of testing whether a packet belongs to a set of filtered addresses has been traditionally addressed using Bloom filters. They have a small memory footprint and require few memory accesses per query and insertion, while presenting a small probability of false positive. The problem of automatic eviction of filtered addresses after a pre-configured time window is more challenging, since it requires tracking insertion times for later removal. This has been achieved in the literature by replacing the Bloom filter's vector of bits for a vector of timestamps. This approach precisely expires old items from the filter, but has a large memory footprint. We present a novel Bloom filter based data structure that features approximate information expiration. This small extra source of error allows for a more compact filter representation, thus becoming more suitable to fit in more expensive, faster memory. Additionally, our data structure is more flexible in that it allows for balancing the trade-off between filtering and expiration accuracy. Our experiments show that this method can obtain up to orders of magnitude higher overall accuracy than the time-stamp approach using the same amount of memory.
Title: Development of novel catalytically active polymer-metal-nanocomposites based on activated foams and textile fibers
Authors: Domènech Garcia, Berta; Ziegler, Kharla; Carrillo Navarrete, Fernando; Muñoz Tapia, Maria; Muraviev, Dmitri N.; Macanàs de Benito, Jorge
Abstract: In this paper, we report the intermatrix synthesis of Ag nanoparticles in different polymeric matrices such as polyurethane foams and polyacrylonitrile or polyamide fibers. To apply this technique, the polymer must bear functional groups able to bind and retain the nanoparticle ion precursors while ions should diffuse through the matrix. Taking into account the nature of some of the chosen matrices, it was essential to try to activate the support material to obtain an acceptable value of ion exchange capacity. To evaluate the catalytic activity of the developed nanocomposites, a model catalytic reaction was carried out in batch experiments: the reduction of pnitrophenol by sodium borohydride
Title: The efficiency of tissue P systems with cell separation relies on the environment
Authors: Macias Ramos, Luis F.; Pérez Jiménez, Mario J.; Riscos Nuñez, Agustín; Rius Font, Miquel; Valencia Cabrera, Luis
Abstract: The classical definition of tissue P systems includes a distinguished alphabet with the special assumption that its elements are available in an arbitrarily large amount of copies. These objects are shared in a distinguished place of the system, called the environment. This ability of having infinitely many copies of some objects has been widely exploited in the design of efficient solutions to computationally hard problems by means of tissue P systems.
This paper deals with computational aspects of tissue P systems with cell separation where there is no such environment as described above. The main result is that only tractable problems can be efficiently solved by using this kind of P systems. Bearing in mind that NP–complete problems can be efficiently solved by using tissue P systems without environment and with cell division, we deduce that in the framework of tissue P systems without environment, the kind of rules (separation versus division) provides a new frontier of the tractability of decision problems.
Title: Evaluación formativa usando exámenes no presenciales
Authors: López Álvarez, David; Sánchez Carracedo, Fermín; Cruz Díaz, Josep Llorenç; Fernández Jiménez, Agustín
Abstract: Los exámenes tradicionales están orientados a la evaluación sumativa, no a la formativa, y provocan un aprendizaje superficial, más que un aprendizaje profundo. Su objetivo es evaluar, no facilitar el aprendizaje. Los estudiantes perciben que su futuro a corto plazo depende de su nota en un examen, por lo que orientan su estudio a aprobar dicho examen. En este artículo se exponen las ventajas e inconvenientes de realizar
un examen no presencial, con evaluación sumativa y formativa, que los estudiantes realizan fuera de clase a lo largo de un periodo de tiempo mucho más largo que el de un examen tradicional, lo que les ayuda a conseguir un aprendizaje profundo.
Traditional exams are focused on the summative assessment, not on the formative one. Its aim is to evaluate, not to facilitate learning, so it results in
superficial learning rather than deep learning. Thus, students perceive that their short-term future depends on their note in the exam, so their study is guided to pass the examination. In this paper we propose a take-home exam in which students have more time to solve the questions and are not
restricted by the sources they can consult, thereby providing a highly educational task in which students experience a deep learning process.
Title: Improving the resilience of an IDS against performance throttling attacks
Authors: Sreekar Shenoy, Govind; Tubella Murgadas, Jordi; González Colás, Antonio María
Abstract: Intrusion Detection Systems (IDS) have emerged as one of the most promising ways to secure systems in the network. To be effective against evasion attempts, the IDS must provide tight bounds on performance. Otherwise an adversary can bypass the IDS by carefully crafting and sending packets that throttle it. This can render the IDS ineffective, thus resulting in the network becoming vulnerable. We present a performance throttling attack mounted against the computationally intensive string matching algorithm. This algorithm performs string matching by traversing a finite-state-machine (FSM). We observe that there are some input bytes that sequentially traverse a chain of 30 pointers. This chain of traversal drastically degrades performance,
and we observe a 22X performance drop in comparison to the average case performance. We investigate hardware and software mechanisms to counter this performance degradation. The software mechanism is targeted for commodity general purpose CPUs. While the hardware-based mechanism uses a parallel traversal suitable for network processor architectures. Our results show that our proposed mechanisms significantly
improves (by over 3X magnitude) string matching algorithm’s worst performing cases.
Title: OSS integration issues and community support: an integrator perspective
Authors: Ayala Martínez, Claudia Patricia; Cruzes, Daniela S.; Nguyen, Anh Duc; Conradi, Reidar; Franch Gutiérrez, Javier; Höst, Martin; Babar, Muhammad Ali
Abstract: The reuse and integration of Open Source Software (OSS) components provided by OSS communities is becoming an economical and
strategic need for today’s organizations. The integration of OSS components provides many benefits, but also risks and challenges. One of the most important risks is the lack of effective and timely OSS community support for dealing with possible integration problems. For gaining an understanding of the common problems that organizations face when integrating OSS com
ponents, and the role played by OSS communities, we performed an exploratory study on 25 OSS integration projects from different European organizations. The
results show that the main way of reducing integration problems was the use of OSS components from well-established communities; therefore very few integration problems were identified. In most of the cases these problems were successfully solved with the support from the OSS community and/or colleagues. In addition, contrary to the common belief that understanding code from someone else is a hard and undesirable task, some integrators consider OSS code even more understandable than their own code.