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Valencia, Spain

The Technical University of Valencia is a Spanish university located in Valencia, with a focus on science and technology. It was founded in 1968 as the Higher Polytechnic School of Valencia and became a university in 1971, but some of its schools are more than 100 years old. Wikipedia.

Bushuev Y.G.,Ivanovo State University of Chemistry and Technology | Sastre G.,Polytechnic University of Valencia
Journal of Physical Chemistry C | Year: 2011

Water in pure silica zeolites (zeosils) may behave as a "bumper" by absorbing mechanical energy of the intruded water, as a "spring" by restoring after extrusion of the energy spent in intrusion, or as "shock absorber" by dissipating the energy. The understanding of how the structure and topology of the zeosils are responsible of such behavior has not yet been fully clarified. Molecular dynamics and molecular mechanics simulations of IFR- and TON-type zeosils have been performed in an attempt to elucidate the energetics of these materials after water intrusion-extrusion. We aim our simulations to capture the experimentally observed "bumper" and "spring" water-zeosil behavior of IFR and TON, respectively. The excess energy with respect to dry zeosil was calculated, and this relates to the energetic response of the zeosil after water intrusion. We found that the excess energy of water-TON is larger than the energy of bulk water at any loading. The small opening of the TON channel prevents the formation of energetically stable bulky water clusters. The water content was shown to be stabilized on a certain loading range in water-IFR. It was shown that any silanol defects in IFR framework channels stabilize systems. Defect positions (silanol groups), which make the water-IFR system energetically stable, are found. Silanol groups increase the hydrophilicity of IFR-type zeosil, initially hydrophobic. There are two factors explaining the bumper behavior (under high pressure, water penetrates into the zeosil channels and remains there even after the pressure is released) of water-IFR systems: channel size and hydrolisis leading to framework breaking under large hydrostatic pressure. Silanol groups in channels are centers of water clusterization. The chemical stability of TON framework and its small channel size explain its spring behavior. © 2011 American Chemical Society. Source

Escriva-Escriva G.,Polytechnic University of Valencia
Energy and Buildings | Year: 2011

Numerous studies have focused on improving energy efficiency in commercial buildings. Engineers and researchers have developed complex methods to improve energy efficiency, but buildings are often managed by non-specialised technicians who need understandable and cost-effective actions to implement in their buildings. This paper presents basic actions on which to base improvements in energy efficiency in commercial buildings in operation. Furthermore, obtained results and details of the implementation of these techniques in various buildings in the Universitat Politcnica de Valncia are presented. © 2011 Elsevier B.V. All rights reserved. Source

Romaguera S.,Polytechnic University of Valencia | Valero O.,University of the Balearic Islands
Mathematical Structures in Computer Science | Year: 2010

We characterise those quasi-metric spaces (X, d) whose poset BX of formal balls satisfies the condition for every (x,r),(y,s) ∈ BX, (x,r) ≪ (y,s) ⇔ d(x,y) < r - s. From this characterisation, we then deduce that a quasi-metric space (X, d) is Smyth-complete if and only if BX is a dcpo satisfying condition (*). We also give characterisations in terms of formal balls for sequentially Yoneda complete quasi-metric spaces and for Yoneda complete T1 quasi-metric spaces. Finally, we discuss several properties of the Heckmann quasi-metric on the formal balls of any quasi-metric space. Copyright © Cambridge University Press 2010. Source

Silvestre-Blanes J.,Polytechnic University of Valencia | Almeida L.,University of Porto | Marau R.,University of Porto | Pedreiras P.,University of Aveiro
IEEE Transactions on Industrial Electronics | Year: 2011

A growing number of industrial applications incorporate multimedia information processing. These multimedia applications are commonly distributed and subject to time constraints that must be met across networks without creating intolerable interference over typical control flows. However, multimedia traffic, in general, and video streaming, in particular, have specific characteristics that conflict with the operational framework of conventional real-time protocols. In particular, video compressors generate highly variable bit-rate streams that mismatch the constant-bit-rate channels typically provided by real-time protocols, severely reducing the efficiency of network utilization. This paper focuses on low-latency multimedia transmission over Ethernet with dynamic quality-of-service (QoS) management. We propose a multidimensional mechanism that controls, in an integrated way, both the compression parameters and the network bandwidth allocated to each stream. The goal is to provide the best possible QoS to each stream, recomputing the compression levels and network bandwidth whenever significant events, such as channel setup/teardown, or structural changes happen. This paper also presents novel QoS metrics based both on the image quality and network parameters. Several experiments with prerecorded video streams illustrate the advantages of the proposed approach and the convenience of the metrics. © 2010 IEEE. Source

Naderi B.,Amirkabir University of Technology | Ruiz R.,Polytechnic University of Valencia
Computers and Operations Research | Year: 2010

This paper studies a new generalization of the regular permutation flowshop scheduling problem (PFSP) referred to as the distributed permutation flowshop scheduling problem or DPFSP. Under this generalization, we assume that there are a total of F identical factories or shops, each one with m machines disposed in series. A set of n available jobs have to be distributed among the F factories and then a processing sequence has to be derived for the jobs assigned to each factory. The optimization criterion is the minimization of the maximum completion time or makespan among the factories. This production setting is necessary in today's decentralized and globalized economy where several production centers might be available for a firm. We characterize the DPFSP and propose six different alternative mixed integer linear programming (MILP) models that are carefully and statistically analyzed for performance. We also propose two simple factory assignment rules together with 14 heuristics based on dispatching rules, effective constructive heuristics and variable neighborhood descent methods. A comprehensive computational and statistical analysis is conducted in order to analyze the performance of the proposed methods. © 2009 Elsevier Ltd. All rights reserved. Source

Pan Q.-K.,Northeastern University China | Pan Q.-K.,Liaocheng University | Ruiz R.,Polytechnic University of Valencia
Computers and Operations Research | Year: 2013

In recent years, a large number of heuristics have been proposed for the minimization of the total or mean flowtime/completion time of the well-known permutation flowshop scheduling problem. Although some literature reviews and comparisons have been made, they do not include the latest available heuristics and results are hard to compare as no common benchmarks and computing platforms have been employed. Furthermore, existing partial comparisons lack the application of powerful statistical tools. The result is that it is not clear which heuristics, especially among the recent ones, are the best. This paper presents a comprehensive review and computational evaluation as well as a statistical assessment of 22 existing heuristics. From the knowledge obtained after such a detailed comparison, five new heuristics are presented. Careful designs of experiments and analyses of variance (ANOVA) techniques are applied to guarantee sound conclusions. The comparison results identify the best existing methods and show that the five newly presented heuristics are competitive or better than the best performing ones in the literature for the permutation flowshop problem with the total completion time criterion. © 2012 Elsevier Ltd. All rights reserved. Source

Contreras F.G.,Polytechnic University of Valencia
International Journal of Advanced Manufacturing Technology | Year: 2012

The tolerance charting method enables the calculation of working tolerances in machining process planning. The method has been used as a basic tool for analysing process plans for many decades. Process capability in tolerance charting is modelled using the tolerances of the working dimensions. The literature shows that machining process capability can be analysed from the point of view of surface position errors. During setups, it is possible to perform decomposition into two surface position tolerances: a datum surface position tolerance and a machining surface position tolerance. This type of analysis has the advantage of producing simplified tolerance chains. This paper provides an adaptation of the tolerance charting technique that uses a capability model based on datum and machining surface position tolerance. The results show an improvement in the working tolerance stackup that reduces the capability required for productive resources. As a result, reductions in manufacturing costs can be achieved. The proposal is valid for manual or computer-assisted techniques. © Springer-Verlag London Limited 2011. Source

Penarrocha I.,Jaume I University | Sanchis R.,Jaume I University | Albertos P.,Polytechnic University of Valencia
Systems and Control Letters | Year: 2012

In this paper, the problem of estimating signals from a dynamic system at regular periods from scarce, delayed and possibly time disordered measurements acquired through a network is addressed. A model based predictor that takes into account the delayed and irregularly gathered measurements from different devices is used. Robustness of the predictor to the time-delays and scarce data availability as well as disturbance and noise attenuation is dealt with via H∞ performance optimization. The result is a time variant estimator gain that depends on the measurement characteristics, but belonging to an offline precalculated finite set, and hence, the online needed computer resources are low. An alternative to reduce the number of gains to be stored has been proposed, based on defining the gain as a function of the sampling parameters. The idea allows reaching a compromise between online computer cost and performance. © 2012 Elsevier B.V. All rights reserved. Source

Merino E.,Polytechnic University of Valencia
Chemical Society Reviews | Year: 2011

Azobenzenes are ubiquitous motifs very important in many areas of science. Azo compounds display crucial properties for important applications, mainly for the chemical industry. Because of their discovery, the main application of aromatic azo compounds has been their use as dyes. These compounds are excellent candidates to function as molecular switches because of their efficient cis-trans isomerization in the presence of appropriate radiation. The classical methods for the synthesis of azo compounds are the azo coupling reaction (coupling of diazonium salts with activated aromatic compounds), the Mills reaction (reaction between aromatic nitroso derivatives and anilines) and the Wallach reaction (transformation of azoxybenzenes into 4-hydroxy substituted azoderivatives in acid media). More recently, other preparative methods have been reported. This critical review covers the various synthetic methods reported on azo compounds with special emphasis on the more recent ones and their mechanistic aspects (170 references). © 2011 The Royal Society of Chemistry. Source

Estevez E.,University of Jaen | Marcos M.,Polytechnic University of Valencia
IEEE Transactions on Industrial Informatics | Year: 2012

Current industrial applications demand the design of more and more complex, safe and trustworthy control systems exhibiting a high degree of flexibility and reutilization. To achieve this, the engineering process should be improved by making the engineering tools involved in the development process to collaborate during the design. This paper presents a model-based approach for designing complex automation applications. The core of the approach is constituted by a set of domain specific models that depend on the application field and whose elements, syntax and semantics are defined from the point of view of the experts that participate in the design of the system. The domain models are defined using engineering tools as the design progresses and they can be used to achieve tool integration through model collaboration. This can be achieved following the Model Driven Engineering approach by means of model transformations. This paper specifically focuses on the first step of this paradigm: the definition of domain languages, in this case for industrial control systems, as well as validation mechanisms of application designs coming from different domain tools. Three well known and widely used industrial standards have been used: Computer Aided Engineering eXchange (CAEX), PLCopen (a representation format for the IEC 61131-3 standard) and MathML (a language for defining mathematical constraints). Using model checking it is possible to assure the correctness of the control system specification and using model transformation it is possible to detect design errors in early stages of the design. © 2011 IEEE. Source

Bengoechea C.,University of Seville | Peinado I.,Polytechnic University of Valencia | McClements D.J.,University of Massachusetts Amherst
Food Hydrocolloids | Year: 2011

Lactoferrin is a globular protein from milk that has considerable potential as a functional ingredient in food, cosmetic and pharmaceutical applications. In this study, we examined the possibility of preparing food-grade bovine lactoferrin (bLf) nanoparticles using a simple thermal processing method. Differential Scanning Calorimetry (DSC), light scattering, and ζ-potential techniques were used to provide information about the conformational changes, aggregation, and electrical charge of bLf in aqueous solutions. DSC studies indicated that the protein had two thermal denaturation temperatures (61 and 93 °C), which were associated with two different lobes of the protein. Protein denaturation was found to be irreversible, which was attributed to the formation of protein nanoparticles, whose size depended on the temperature and duration of the thermal treatment. Higher holding temperatures produced faster protein aggregation and larger protein nanoparticles: 85 > 80 > 75 > 70 °C. The protein nanoparticles produced by thermal treatment were resistant to subsequent changes in pH (from 3 to 11) and to salt addition (0-200 mM NaCl). The lactoferrin nanoparticles produced in this study may be useful as function ingredients in commercial products. © 2010 Elsevier Ltd. Source

Garcia H.,Polytechnic University of Valencia
Chemical Record | Year: 2015

The aim of the present review article is to show the progress achieved in the efficiency of dye-sensitized solar cells (DSSCs) by evolution in the structure and composition of the dye. After an initial brief description of DSSCs and the operating mechanism the major part of the present article is organized according to the type of dye, trying to show the logic in the variation of the dye structure in order to achieve strong binding on the surface of the layer of nanoparticulate TiO2, efficient interfacial electron injection between the excited dye and the semiconductor, and minimization of the unwanted dark current processes. Besides metal complexes, including polypyridyls and nitrogenated macro rings, organic dyes and inorganic light harvesters such as quantum dots and perovskites have also been included in the review. The last section summarizes the current state of the art and provides an overview on future developments in the field. © 2015 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Saiz A.,Polytechnic University of Valencia
Physica A: Statistical Mechanics and its Applications | Year: 2010

In this paper we propose a model based on the Boltzmann distribution as a mechanism for generating power laws, Boltzmann Power Laws (BPL). Some of these power laws are studied and compared to popular power laws such as '1 / f' noise and self-organized criticality (SOC). We will show how, in some cases, these BPLs reproduce behaviors similar to the finite size scaling (FSS) scenario, which is typical of SOC. © 2009 Elsevier B.V. All rights reserved. Source

Andreu-Andres M.A.,Polytechnic University of Valencia | Garcia-Casas M.,IES La Moreria
International Journal of Engineering Education | Year: 2011

After defining the term game and its characteristics, this paper refers to the origins of games, and supports the idea of gaming as one of the techniques included in the simulation and gaming methodology endorsed by associations such as ISAGA, NASAGA, JASAG, ABSEL or SAGSET. Considering gaming as experiential learning this study offers the perceptions of forty seven engineering students in their third year of studies at the Universitat Politècnica de València (Spain) regarding the use of games in different supports as part of their activitiesto gain knowledge insubjects of their degree program throughout a semester, to reinforce previously covered material, and to help learners develop problem-solving skills, communication and teamwork skills. A review of the advantages and drawbacks ofusing games leads usto carry out the statistical analysis of the answerstoa survey concerning the use of gaming as a teaching-learning technique with these engineering students, the students' experience with games in different subjects attended before and during their university studies, and the students' perceptions on using games to learn or just for fun. The study of the relation among the variables analysed allows us to perceive the students' feelings regarding gaming as opposed to more conventional strategies. As a whole, engineering students participating in the experiment back experiential learning and confirm that they learn and have fun when there is gaming in class activities. © 2011 TEMPUS Publications. Source

Martinez A.,Polytechnic University of Valencia
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

Phoxonic crystals are periodic structures affecting simultaneously the propagation of light (photons) and sound (phonons) of similar wavelengths. For instance, by introducing periodicity of the order of the micron on semiconductor membranes, a phoxonic band gap for near infrared light and sound at GHz frequencies appears. The insertion of defects can give rise to the simultaneous localization of photons and phonons in cavities and waveguides. Moreover, new structures can be tailored to enhance the light-sound interaction in such small volumes. In this work, the last advances in phoxonic crystal structures (including the so-called optomechanical cavities) will be reviewed. Techniques to inject light and sound in phoxonic structures will be described. Future possible applications of phoxonic crystals, ranging from ultrasensitive sensing to all-optical information storage, will finally be introduced. © 2013 SPIE. Source

Gutierrez Garcia J.,University of the Basque Country | Romaguera S.,Polytechnic University of Valencia
Fuzzy Sets and Systems | Year: 2011

Answering a recent question posed by Gregori et al. [On a class of completable fuzzy metric spaces, Fuzzy Sets and Systems 161 (2010), 2193-2205] we present two examples of non-strong fuzzy metrics (in the sense of George and Veeramani). © 2010 Elsevier B.V. All rights reserved. Source

Bank B.,Budapest University of Technology and Economics | Ramos G.,Polytechnic University of Valencia
IEEE Signal Processing Letters | Year: 2011

The use of second-order parallel filters with pre-defined pole locations has been recently proposed for equalization and transfer function modeling. This letter presents an improved method for obtaining the pole positions of the parallel filter. The steps of the new method are the following: first, the target frequency response is smoothed to the required resolution. Then, multiple warped IIR filters with different warping parameters are designed to the smoothed target divided into frequency bands. Finally, the united pole set of the warped IIR designs is used for parallel filter design. The method leads to increased accuracy compared to earlier pole positioning techniques, and can also be used for Kautz filter designs. Examples of loudspeaker-room response modeling and equalization are presented. © 2011 IEEE. Source

Silvestre-Blanes J.,Polytechnic University of Valencia
Signal Processing | Year: 2011

The need to obtain objective values of the quality of distorted images with respect to the original is fundamental in multimedia and image processing applications. It is generally required that this value correlates well with the human vision system (HVS). In spite of the properties and the general use of the mean square error (MSE) measurement, this has a poor correlation with HSV, which has led to the development of methods such as structural similarity (SSIM). This metric improves the correlation with respect to the classic MSE and PSNR (peak signal to noise ratio). However, its behavior depends on the values assigned to constants and on the windows size selected. These values are usually assigned arbitrarily and there have been no studies on how they affect the SSIM. In this work, we have analyzed empirically the most appropriate values for the different constants used in the SSIM equations. We have also analyzed the importance of window size in the calculation of MSSIM, and propose a method for determining the window size based on image complexity. Using the values selected and the window size defined, the correlation between SSIM and DMOS (differential mean opinion score) is significantly improved by around 17% with respect to the values commonly used. © 2010 Elsevier B.V. All rights reserved. Source

Moliner M.,Polytechnic University of Valencia
Dalton Transactions | Year: 2014

The former synthesis of TS-1 opened new catalytic opportunities for zeolites, especially for their application as selective redox catalysts in several fine chemistry processes. Interestingly, isolated Ti species in the framework positions of hydrophobic zeolites, such as high silica zeolites, offer unique Lewis acid sites even in the presence of protic polar solvents (such as water). Following this discovery, other transition metals (such as Sn, Zr, V, Nb, among others) have been introduced in the framework positions of different hydrophobic zeolitic structures, allowing their application in new fine chemistry processes as very active and selective redox catalysts. Recently, these hydrophobic metallozeolites have been successfully applied as efficient catalysts for several biomass-transformation processes in bulk water. The acquired knowledge from the former catalytic descriptions in fine chemistry processes using hydrophobic Lewis acid-containing zeolites has been essential for their application in these novel biomass transformations. In the present review, I will describe the recent advances in the synthesis of new transition metal-containing zeolites presenting Lewis acid character, and their unique catalytic applications in both fine chemistry and novel biomass-transformations. © 2014 The Royal Society of Chemistry. Source

D'Este P.,Polytechnic University of Valencia | Perkmann M.,Imperial College London
Journal of Technology Transfer | Year: 2011

The debate on the entrepreneurial university has raised questions about what motivates academic scientists to engage with industry. This paper provides evidence based on survey data for a large sample of UK investigators in the physical and engineering sciences. The results suggest that most academics engage with industry to further their research rather than to commercialize their knowledge. However, there are differences in terms of the channels of engagement. Patenting and spin-off company formation are motivated exclusively by commercialization whilst joint research, contract research and consulting are strongly informed by research-related motives. We conclude that policy should refrain from overly focusing on monetary incentives for industry engagement and consider a broader range of incentives for promoting interaction between academia and industry. © 2010 Springer Science+Business Media, LLC. Source

Pedroche Sanchez F.,Polytechnic University of Valencia
Mathematical and Computer Modelling | Year: 2010

In this paper a new method to classify the users of an SNS (Social Network Site) into groups is shown. The method is based on the PageRank algorithm. Competitivity groups are sets of nodes that compete among each other to gain PageRank via the personalization vector. Specific features of the SNSs (such as number of friends or activity of the users) can modify the ranking inside each Competitivity group. The concept of Leadership Group is also presented. Some numerical examples are shown. These concepts can also be applied to general complex networks. © 2010 Elsevier Ltd. Source

Dhakshinamoorthy A.,Madurai Kamaraj University | Garcia H.,Polytechnic University of Valencia | Garcia H.,King Abdulaziz University
Chemical Society Reviews | Year: 2014

Metal-organic frameworks (MOFs) are finding increasing application as solid catalysts for liquid phase reactions leading to the synthesis of fine chemicals. In the present review we have focused on those reports describing the use of MOFs as catalysts for the synthesis of N-containing heterocycles that is a class of organic compounds with high added value due to their therapeutic use as drugs and their remarkable biological activities. After an introduction describing relevant structural features of MOFs and the nature of their active sites, this manuscript is organized according to the type of N-containing heterocycle synthesized employing MOFs as catalysts including pyrimidines, N-substituted piperidines, quinolines, indoles, N-substituted imidazoles, triazoles and heterocyclic amides. Special attention has been paid to the structural stability of MOFs under the reaction conditions, to the occurrence of metal leaching and reusability. The final section of this review provides some concluding remarks and future prospects for the field, with emphasis on showing the superiority of MOFs with respect to other solid catalysts for this type of liquid phase organic reactions and pointing out that the final goal in this research would be the use of these materials as catalysts in real industrial synthesis. This journal is © the Partner Organisations 2014. Source

Gil-Gomez J.A.,Polytechnic University of Valencia
Journal of neuroengineering and rehabilitation | Year: 2011

Acquired brain injury (ABI) is the main cause of death and disability among young adults. In most cases, survivors can experience balance instability, resulting in functional impairments that are associated with diminished health-related quality of life. Traditional rehabilitation therapy may be tedious. This can reduce motivation and adherence to the treatment and thus provide a limited benefit to patients with balance disorders. We present eBaViR (easy Balance Virtual Rehabilitation), a system based on the Nintendo® Wii Balance Board® (WBB), which has been designed by clinical therapists to improve standing balance in patients with ABI through motivational and adaptative exercises. We hypothesize that eBaViR, is feasible, safe and potentially effective in enhancing standing balance. In this contribution, we present a randomized and controlled single blinded study to assess the influence of a WBB-based virtual rehabilitation system on balance rehabilitation with ABI hemiparetic patients. This study describes the eBaViR system and evaluates its effectiveness considering 20 one-hour-sessions of virtual reality rehabilitation (n = 9) versus standard rehabilitation (n = 8). Effectiveness was evaluated by means of traditional static and dynamic balance scales. The final sample consisted of 11 men and 6 women. Mean ± SD age was 47.3 ± 17.8 and mean ± SD chronicity was 570.9 ± 313.2 days. Patients using eBaViR had a significant improvement in static balance (p = 0.011 in Berg Balance Scale and p = 0.011 in Anterior Reaches Test) compared to patients who underwent traditional therapy. Regarding dynamic balance, the results showed significant improvement over time in all these measures, but no significant group effect or group-by-time interaction was detected for any of them, which suggests that both groups improved in the same way. There were no serious adverse events during treatment in either group. The results suggest that eBaViR represents a safe and effective alternative to traditional treatment to improve static balance in the ABI population. These results have encouraged us to reinforce the virtual treatment with new exercises, so an evolution of the system is currently being developed. Source

Cuenca A.,Polytechnic University of Valencia | Salt J.,University of California at Berkeley
Journal of Process Control | Year: 2012

In this work, a non-uniform multi-rate controller which includes an RST control stage is introduced. Due to several issues, in some systems the use of non-uniform (irregular) multi-rate sampling becomes inevitable. When using a uniform (regular) multi-rate controller in this kind of situations, control performance is usually degraded (if it is compared to that obtained in the nominal, uniform sampling context). Thus, the design of a non-uniform controller proper for this sampling scheme is needed to keep the performance. A sequence of different non-uniform sampling frames can be considered, and different controllers must be designed for each frame using appropriate methods. When switching among these controllers, stability problems can appear. So, the control system stability will be assured in terms of Linear Matrix Inequalities (LMIs). To achieve some advantages at the design step, the discrete-time input-output representation will be used. But, since the classical, uniform z-i delay operator could not be able to represent non-uniform sampling situations, the so-called non-uniform operator will be required. Simulation results illustrate that this control proposal is able to keep control system performance and preserve stability. © 2012 Elsevier Ltd. Source

Mischler S.,Ecole Polytechnique Federale de Lausanne | Munoz A.I.,Polytechnic University of Valencia
Wear | Year: 2013

A good biocompatibility, excellent mechanical properties and high corrosion resistance characterize CoCrMo alloys. Therefore they are widely used for artificial joints in biomedical implants. However, the degradation of the implants during service life leads to the release into the body of toxic ions and wear particles. This continuous degradation is of concern for long-term stability of the implants. Published literature has highlighted the relevance of lubrication as well as metallurgical and contact mechanical factors on the degradation of CoCrMo implant alloys. Recent experimental investigations have proposed tribocorrosion, i.e., the interplay of mechanical wear and corrosion by the body fluids, as one of the crucial degradation mechanism of implants. Tribocorrosion is sub-discipline of tribology and corrosion that recently made significant progresses in mechanistic understanding and modelling. The present work aims at evaluating published results on the degradation of CoCrMo alloys using existing tribocorrosion concepts. Results show that wear accelerated corrosion due to mechanical removal of the passive film during sliding is a major contribution to the overall degradation. Further, a transition from low (10-6N/mm3m) to high (10-4N/mm3m) wear coefficients was found at a threshold electrode potential close to 0.2 VSHE These findings clearly show that electrochemical phenomena play a key role on the tribological behaviour of biomedical CoCrMo alloy implants. © 2012 Elsevier B.V. Source

Jiao L.,University of Agder | Li F.Y.,University of Agder | Pla V.,Polytechnic University of Valencia
IEEE Transactions on Vehicular Technology | Year: 2012

To accommodate spectrum access in multichannel cognitive radio networks (CRNs), the channel-assembling technique, which combines several channels together as one channel, has been proposed in many medium access control (MAC) protocols. However, analytical models for CRNs enabled with this technique have not been thoroughly investigated. In this paper, two representative channel-assembling strategies that consider spectrum adaptation and heterogeneous traffic are proposed, and the performance of these strategies is evaluated based on the proposed continuous-time Markov chain (CTMC) models. Moreover, approximations of these models in the quasistationary regime are analyzed, and closed-form capacity expressions are derived in different conditions. The performance of different strategies, including the strategy without assembling, is compared with one another based on the numerical results obtained from these models and validated by extensive simulations. Furthermore, simulation studies are also performed for other types of traffic distributions to evaluate the validity and the preciseness of the mathematical models. Through both analyses and simulations, we demonstrate that channel assembling represented by the investigated strategies can improve the system performance if a proper strategy is selected with appropriate system parameter configurations. © 2012 IEEE. Source

Perez Y.,Rey Juan Carlos University | Fajardo M.,Rey Juan Carlos University | Corma A.,Polytechnic University of Valencia
Catalysis Communications | Year: 2011

Hydrogenation of phenol to cyclohexanone in aqueous phase, under mild conditions, has been carried out using palladium on different supports such as hydroxyapatite (HA), carbon (C), alumina (γ-Al2O3) and Al2O3-CWE synthesized with high surface area. High activity (100%) and selectivity (98%) to cyclohexanone was obtained using Pd/ Al2O3-CWE catalyst in 50 min under mild reaction conditions. © 2011 Elsevier B.V. All rights reserved. Source

Sanchez-Barrioluengo M.,Polytechnic University of Valencia
Research Policy | Year: 2014

The present paper elaborates a critical reflection on the 'one-size-fits-all' model which conceptualizes universities as centres of excellence in education, research and third mission. It is argued that the shortcomings of this perspective are twofold: first, HEIs are treated as homogeneous institutions with equal capacity to perform and contribute to social engagement; and second, missions are undistinguishable from each other. Both features lead to mischaracterizations concerning the role of universities and their contribution to society. In the view proposed here missions are university strategies linked by complex relationship of compatibility, and the paper puts in perspective the persisting gap concerning the nature of and the relations across them. © 2014 Elsevier B.V. All rights reserved. Source

Vazquez-Gutierrez J.L.,Polytechnic University of Valencia
Food & function | Year: 2013

Onions have antioxidant properties and they are an important source of bioactive compounds such as phenols. The aim of this work was to study the effect of high hydrostatic pressure (HHP) (100-600 MPa/1-3 min/25 °C) on the microstructure and antioxidant properties of onions (cv. Doux) and its relationship with changes in the extractability of potential health-related compounds. Cryo scanning electron microscopy was used to study the microstructure. Vitamin C, total phenolic content and antioxidant activity (DPPH ̇ , ABTS ̇ (+), FRAP) were also analyzed. Tonoplast, plasmalemma and cell walls were affected by the HHP treatment and it favored the diffusion of the cellular content to the intercellular spaces. Vitamin C did not show significant changes, whereas the extracted phenolic content and antioxidant activity increased at pressures of 300 or 600 MPa. Therefore, it could be concluded that HHP produced changes in membrane permeability and disruption of cell walls favoring the release of phenolic compounds from tissue and, in consequence, improving their extractability. Source

Garcia-Breijo E.,Polytechnic University of Valencia
Sensors (Basel, Switzerland) | Year: 2013

In the present study, a portable system based on a microcontroller has been developed to classify different kinds of honeys. In order to do this classification, a Simplified Fuzzy ARTMAP network (SFA) implemented in a microcontroller has been used. Due to memory limits when working with microcontrollers, it is necessary to optimize the use of both program and data memory. Thus, a Graphical User Interface (GUI) for MATLAB® has been developed in order to optimize the necessary parameters to programme the SFA in a microcontroller. The measures have been carried out by potentiometric techniques using a multielectrode made of seven different metals. Next, the neural network has been trained on a PC by means of the GUI in Matlab using the data obtained in the experimental phase. The microcontroller has been programmed with the obtained parameters and then, new samples have been analysed using the portable system in order to test the model. Results are very promising, as an 87.5% recognition rate has been achieved in the training phase, which suggests that this kind of procedures can be successfully used not only for honey classification, but also for many other kinds of food. Source

Pintado-Sierra M.,CSIC - Institute of Materials Science | Pintado-Sierra M.,Institute Quimica Organica General | Rasero-Almansa A.M.,CSIC - Institute of Materials Science | Corma A.,Polytechnic University of Valencia | And 2 more authors.
Journal of Catalysis | Year: 2013

A simple and efficient method for the synthesis of N-alkyl amines via a cascade reaction (hydrogenation + reductive amination) using a new recyclable hybrid catalyst that combines the catalytic power of transition metal complexes with the architecture of metal organic frameworks (MOFs). © 2012 Elsevier Inc. All rights reserved. Source

Cortell R.,Polytechnic University of Valencia
Canadian Journal of Chemical Engineering | Year: 2012

This paper treats about the flow and heat transfer of a viscous incompressible fluid in a porous medium over a permeable stretching surface taking into account thermal radiation and the variation of the thermal conductivity with temperature. Analytical solutions for the stream function are obtained and two cases are studied, namely, (i) prescribed surface temperature (PST case) and (ii) prescribed heat flux (PHF case). The effects of Prandtl number, permeability, suction/blowing, variable thermal conductivity, thermal radiation and surface temperature parameters on heat-transfer characteristics are shown through tables and graphs and discussed. Ce document concerne ĺécoulement et le transfer de chaleur dans le cas d́un fluide visqueux incompressible dans un milieu poreux sur une poreux surface śétendant en tenant compte de la radiation thermique et de la conductivité thermodépendante. Les solutions analytiques pour la fonction de courant sont obtenus et deux conditions à la frontière pour la tempèrature et le flux de chaleur sont apliquées: (i) predicted surface tempèrature (PST) et (ii) le flux de chaleur predicted (PHF). Les effects du nombre de Prandtl, perméabilité, succion/soufflage, conductivité thermodépendante, radiation thermique et de la surface tempèrature sur le transfer de chaleur sont indiqués dans des tableaux et des graphiques, puis sont discutés. © 2011 Canadian Society for Chemical Engineering. Source

Zarzo M.,Polytechnic University of Valencia
Sensors | Year: 2011

Different psychophysical works have reported that, when a wide range of odors is assessed, the hedonic dimension is the most salient. Hence, pleasantness is the most basic attribute of odor perception. Recent studies suggest that the molecular size of a given odorant is positively correlated with its hedonic character. This correlation was confirmed in the present study, but further basic molecular features affecting pleasantness were identified by means of multiple linear regression for the compounds contained in five chemical sets. For three of them, hedonic judgments are available in the literature. For a further two chemical sets, hedonic scores were estimated from odor character descriptions based on numerical profiles. Generally speaking, fairly similar equations were obtained for the prediction of hedonic judgments in the five chemical sets, with R2 values ranging from 0.46 to 0.71. The results suggest that larger molecules containing oxygen are more likely to be perceived as pleasant, while the opposite applies to carboxylic acids and sulfur compounds. © 2011 by the authors; licensee MDPI, Basel, Switzerland. Source

Llopis-Albert C.,Instituto Geologico Y Minero Of Espana Igme | Palacios-Marques D.,Polytechnic University of Valencia | Merigo J.M.,University of Manchester
Journal of Hydrology | Year: 2014

In this paper a methodology for the stochastic management of groundwater quality problems is presented, which can be used to provide agricultural advisory services. A stochastic algorithm to solve the coupled flow and mass transport inverse problem is combined with a stochastic management approach to develop methods for integrating uncertainty; thus obtaining more reliable policies on groundwater nitrate pollution control from agriculture. The stochastic inverse model allows identifying non-Gaussian parameters and reducing uncertainty in heterogeneous aquifers by constraining stochastic simulations to data. The management model determines the spatial and temporal distribution of fertilizer application rates that maximizes net benefits in agriculture constrained by quality requirements in groundwater at various control sites. The quality constraints can be taken, for instance, by those given by water laws such as the EU Water Framework Directive (WFD). Furthermore, the methodology allows providing the trade-off between higher economic returns and reliability in meeting the environmental standards. Therefore, this new technology can help stakeholders in the decision-making process under an uncertainty environment. The methodology has been successfully applied to a 2D synthetic aquifer, where an uncertainty assessment has been carried out by means of Monte Carlo simulation techniques. © 2014 Elsevier B.V. Source

Villaverde G.,CSIC - Institute of Materials Science | Corma A.,Polytechnic University of Valencia | Iglesias M.,CSIC - Institute of Materials Science | Sanchez F.,Instituto Quimica Organica General
ACS Catalysis | Year: 2012

A series of gold complexes were tested as catalysts in the synthesis of propargylamines by the three component coupling reaction of amines, aldehydes, and alkynes. These complexes are efficient catalysts for the three-component coupling reaction (yields up to 97%). In homogeneous solution, the conversions to the respective propargylamine were higher than under heterogeneous conditions. Heterogenized complexes were stable and recoverable for at least six cycles. Ligands, gold(I) or gold(III), homogeneous or heterogenized systems have pronounced effects on the catalytic activity of the corresponding gold complexes. © 2012 American Chemical Society. Source

Belmar O.,University of Murcia | Velasco J.,University of Murcia | Martinez-Capel F.,Polytechnic University of Valencia
Environmental Management | Year: 2011

Hydrological classification constitutes the first step of a new holistic framework for developing regional environmental flow criteria: the "Ecological Limits of Hydrologic Alteration (ELOHA)". The aim of this study was to develop a classification for 390 stream sections of the Segura River Basin based on 73 hydrological indices that characterize their natural flow regimes. The hydrological indices were calculated with 25 years of natural monthly flows (1980/81-2005/06) derived from a rainfall-runoff model developed by the Spanish Ministry of Environment and Public Works. These indices included, at a monthly or annual basis, measures of duration of droughts and central tendency and dispersion of flow magnitude (average, low and high flow conditions). Principal Component Analysis (PCA) indicated high redundancy among most hydrological indices, as well as two gradients: flow magnitude for mainstream rivers and temporal variability for tributary streams. A classification with eight flow-regime classes was chosen as the most easily interpretable in the Segura River Basin, which was supported by ANOSIM analyses. These classes can be simplified in 4 broader groups, with different seasonal discharge pattern: large rivers, perennial stable streams, perennial seasonal streams and intermittent and ephemeral streams. They showed a high degree of spatial cohesion, following a gradient associated with climatic aridity from NW to SE, and were well defined in terms of the fundamental variables in Mediterranean streams: magnitude and temporal variability of flows. Therefore, this classification is a fundamental tool to support water management and planning in the Segura River Basin. Future research will allow us to study the flow alteration-ecological response relationship for each river type, and set the basis to design scientifically credible environmental flows following the ELOHA framework. © 2011 Springer Science+Business Media, LLC. Source

Gil-Ortiz R.,Polytechnic University of Valencia
Pest Management Science | Year: 2012

Background: A new controlled-release pheromone 1,7-dioxaspiro[5,5]undecane dispenser has been developed, which is useful for monitoring the population and controlling Bactrocera oleae (Rossi, 1790) (Diptera: Tephritidae). For this purpose, several kinds of dispensers based on attapulgite were designed and tested in this study. Results: The designed dispensers, together with the commercial-brand olive fruit fly 'Long-Life Lure', which was used as a reference, were evaluated in the field, and in parallel were subjected to an accelerated ageing process in a chamber with a constant temperature and air speed. The residual pheromone content was periodically determined by liquid-gas chromatography in order to obtain the half-life of dispensers and the pheromone release rate. The mesoporous dispenser proved to have the best performance in the field, with a half-life of 5 months and an average emission speed of 0.6 mg day -1, parameters very close to those obtained with the commercial dispenser tested. In addition, to evaluate the effectiveness of the different dispensers in the field, a duplicate comparative study of captures was designed, and a colony monitoring study of the olive fruit fly was performed using various food and sex attractants. Conclusions: Although no significant differences in captures were found between the dispensers tested, the highest number of captures was obtained on average with the mesoporous dispensers demonstrating good pheromone emission characteristics. © 2012 Society of Chemical Industry. Source

Juraske R.,ETH Zurich | Sanjuan N.,Polytechnic University of Valencia
Chemosphere | Year: 2011

The relative impacts of 25 pesticides including acaricides, fungicides, herbicides, insecticides, and post-harvest fungicides, used in the production of oranges in Spain were assessed with current life cycle impact assessment (LCIA) tools. Chemical specific concentrations were combined with pesticide emission data and information on chemical toxicity to assess human toxicity and freshwater ecotoxicity impacts. As a case study, the relative impacts of two orange production systems in the region of Valencia, integrated pest management (IP) and organic production (OP), were assessed. The evaluation of active ingredients showed that on average acaricides have the highest human toxicity impact scores, while for freshwater ecotoxicity insecticides show the highest impact. In both impact categories the lowest impact scores were calculated for herbicides. In the production of 1. kg of orange fruits, where several kinds of pesticides are combined, results show that post-harvest fungicides can contribute more than 95% to the aggregate human toxicity impacts. More than 85% of aquatic ecotoxicity is generated by fungicides applied before harvest. The potential to reduce impacts on freshwater ecosystems is seven orders of magnitude, while impacts on human health can be reduced by two orders of magnitude. Hence, this stresses the importance of a careful pre-selection of active ingredients. In both impact categories, organic production represents the least toxic pest-control method. © 2010 Elsevier Ltd. Source

Blanes S.,Polytechnic University of Valencia | Iserles A.,University of Cambridge
Celestial Mechanics and Dynamical Astronomy | Year: 2012

We consider Sundman and Poincaré transformations for the long-time numerical integration of Hamiltonian systems whose evolution occurs at different time scales. The transformed systems are numerically integrated using explicit symplectic methods. The schemes we consider are explicit symplectic methods with adaptive time steps and they generalise other methods from the literature, while exhibiting a high performance. The Sundman transformation can also be used on non-Hamiltonian systems while the Poincaré transformation can be used, in some cases, with more efficient symplectic integrators. The performance of both transformations with different symplectic methods is analysed on several numerical examples. © 2012 Springer Science+Business Media B.V. Source

Gasulla I.,Stanford University | Gasulla I.,Polytechnic University of Valencia | Kahn J.M.,Stanford University
Journal of Lightwave Technology | Year: 2015

We present an end-to-end performance evaluation of a mode-group-division multiplexing system that uses direct detection instead of coherent detection, avoiding complex digital signal processing. The system transmits four data channels through a step-index fiber supporting six spatial modes comprising four mode groups, considering the twofold degeneracy of the LPlm modes for l ≠ 0. Multiplexing and demultiplexing is performed using two- and three-core fused fiber couplers, each one phase-matched to a group of degenerate modes. These devices are analyzed through a field-based model that describes, for the first time to our knowledge, crosstalk between all the fiber modes. Propagation through the few-mode fiber is modeled considering differential modal attenuation, intermodal dispersion, chromatic dispersion, and both intergroup and intragroup modal coupling. The end-to-end link is described by a concatenation of matrix operators describing the optical field transfer functions for the multiplexer, fiber, and demultiplexer. Error-free transmission of four 32-Gbs OOK-modulated data channels through a 1-km link proves the feasibility of the proposed direct-detection mode-group-division multiplexing approach. © 1983-2012 IEEE. Source

Herrada M.,Polytechnic University of Valencia | Shtern V.,Shtern Research and Consulting
Physics of Fluids | Year: 2015

This numerical study reveals that the thermal convection, induced by the axial gradient of temperature in a rotating pipe, suffers from the shear-layer instability if the Prandtl number, Pr, is small. As Pr increases, this instability is suppressed by the stable density stratification in the field of centrifugal force. In an annular pipe, the thermal instability develops for large Pr if a temperature of walls is prescribed. For a narrow annulus, these features agree with the known results for a planar flow driven by gravity and a horizontal gradient of temperature. It is shown here that the thermal instability does not develop if the walls are adiabatic. The centrifugal and Marangoni convection of a liquid, partially filling the pipe, also suffers from the shear-layer instability for small Pr and has no thermal instability. These features agree with the experiments for the planar flow performed by Kirdyashkin. The obtained results are of fundamental interest and can be relevant for the development of centrifugal heat exchangers. © 2015 AIP Publishing LLC. Source

Rodriguez-Hernandez M.A.,Polytechnic University of Valencia
Biomedical Signal Processing and Control | Year: 2016

Denoising of biomedical signals using wavelet transform is a widely used technique. The use of undecimated wavelet transform (UWT) assures better denoising results but implies a higher complexity than discrete wavelet transform (DWT). Some implementation schemes have been proposed to perform UWT, one of them is Cycle Spinning (CS). CS is performed using the DWT of several circular shifted versions of the signal to analyse. The reduction of the number of shifted versions of the biomedical signal during denoising process used is addressed in the present work. This paper is about a variant of CS with a reduced number of shifts, called Partial Cycle Spinning (PCS), applied to ultrasonic trace denoising. The influence of the choice of PCS shifts in the denoised registers quality is studied. Several shifts selection rules are proposed, compared and evaluated. Denoising results over a set of ultrasonic registers are provided for PCS with different shift selection rules, CS and DWT. The work shows that PCS with the appropriate choice of shifts could be the best option to denoise biomedical ultrasonic traces. © 2015 Elsevier Ltd. All rights reserved. Source

Cortell R.,Polytechnic University of Valencia
Chemical Engineering Research and Design | Year: 2011

This paper presents a study of the flow and heat transfer of an incompressible Ostwald de-Waele power-law fluid past an infinite porous plate, subject to suction at the plate. The power-law index n satisfies 0 < n< 1 (shear-thinning fluid only) provided that there is suction at the plate. Three cases are studied, namely, (i) the plate with constant surface temperature (CST case), (ii) the plate with prescribed surface temperature (PST case), and (iii) the plate with prescribed heat flux (PHF case). The effects of viscous dissipation and thermal radiation are also considered in the energy equation and the variations of dimensionless surface temperature and dimensionless surface temperature gradient with various parameters are graphed and tabulated. © 2010 The Institution of Chemical Engineers. Source

Garrido J.M.,Iberport Consulting S.A. | Medina J.R.,Polytechnic University of Valencia
Coastal Engineering | Year: 2012

A new semi-empirical model is used to estimate the coefficient of reflection for single- and double-perforated chambers in Jarlan-type breakwaters. This semi-empirical model is based on a potential flow theoretical model which was modified with specific, empirical formulas to obtain a much better agreement with the experimental tests. Single-chamber and double-chamber slotted and perforated Jarlan-type breakwaters were tested with 1500 regular wave and 160 random wave runs. Pruned Neural Network models with Evolutionary Strategies were used to identify the nonlinear relationships between the structural and wave attack parameters and the Jarlan-type breakwater reflectivity. This new semi-empirical model is valid for regular and random waves on single-chamber and double-chamber Jarlan-type breakwaters, providing estimations of the coefficient of reflection with a relative mean squared error lower than 10% for all experimental observations used to calibrate the model. © 2011 Elsevier B.V. Source

Zarzo M.,Polytechnic University of Valencia | Marti P.,Universidad Politecnica de Ingenieria
Applied Energy | Year: 2011

Measurements of global terrestrial solar radiation (Rs) are commonly recorded in meteorological stations. Daily variability of Rs has to be taken into account for the design of photovoltaic systems and energy efficient buildings. Principal components analysis (PCA) was applied to Rs data recorded at 30 stations in the Mediterranean coast of Spain. Due to equipment failures and site operation problems, time series of Rs often present data gaps or discontinuities. The PCA approach copes with this problem and allows estimation of present and past values by taking advantage of Rs records from nearby stations. The gap infilling performance of this methodology is compared with neural networks and alternative conventional approaches. Four principal components explain 66% of the data variability with respect to the average trajectory (97% if non-centered values are considered). A new method based on principal components regression was also developed for Rs estimation if previous measurements are not available. By means of multiple linear regression, it was found that the latent variables associated to the four relevant principal components can be fitted according to the latitude, longitude and altitude of the station where data were recorded from. Additional geographical or climatic variables did not increase the predictive goodness-of-fit. The resulting models allow the estimation of daily Rs values at any location in the area under study and present higher accuracy than artificial neural networks and some conventional approaches considered. The proposed methodology for estimating Rs based on geographical parameters would be of interest to design solar energy systems and to select their best location. © 2011 Elsevier Ltd. Source

Marti P.,Universidad Politecnica de Ingenieria | Gasque M.,Polytechnic University of Valencia
Energy Conversion and Management | Year: 2011

The development of new and more precise temperature-based models for solar radiation estimation is decisive, given the immediacy and simplicity associated to their input measurements and the ubiquitous problems derived from equipment failures, maintenance and calibration, and physical and biological constraints. Further, the performance quality of empirical equations is to be questioned in a large variety of climatic contexts. As an alternative to traditional techniques, artificial neural networks (ANNs) are highly appropriate for the modelling of non-linear processes. Nevertheless, temperature-based ANN models do not always provide accurate enough solar radiation estimations as their performance depends considerably on the specific temperature/solar radiation relationships of the studied context. This paper describes a new procedure to improve the performance accuracy of temperature-based ANN models for estimation of total solar radiation on a horizontal surface (Rs) taking advantage of ancillary data records from secondary similar stations, which work as exogenous inputs. The influence on the model performance of the number of considered ancillary stations and the corresponding number of training patterns is also analyzed. Finally, these models are compared with those relying exclusively on local temperature recordings. The proposed models provide performances with lower associated errors than those which do not consider exogenous inputs. The ancillary supply is translated into a decrease around 0.1 of RMSE in the local performance. The consideration of non-measured inputs in the simple local temperature-based models, namely extraterrestrial radiation or day of the year, entails a performance accuracy improvement around 0.1 of RMSE. © 2010 Elsevier Ltd. All rights reserved. Source

Bosca F.,Polytechnic University of Valencia
Journal of Physical Chemistry B | Year: 2012

Interactions between serum albumins (HSA, human, and BSA, bovine) and fluoroquinolones (FQs), such as enoxacin, norfloxacin, ciprofloxacin, and ofloxacin, have been studied using the laser flash photolysis technique. Lifetimes and quantum yields of FQs triplet excited states (3FQs) are not affected by the presence of albumins, however, the quenching of 3FQs by tryptophan and tyrosine and the subsequent generation of FQs radical anions and tyrosyl or tryptophanyl radicals were detected. These results, besides agreeing with association constants (Ka) for FQs binding to albumins lower than 6 × 102 M-1, are highly relevant to understanding the process of photohapten formation, the first event in the onset of photoallergy. The emission of tryptophan within albumin is not affected by the presence of FQs when the inner filter effects (IFE) of these drugs are taken into account, which explains the discrepancies reported in the literature about Ka of FQs with albumins. © 2012 American Chemical Society. Source

Ferriol M.,Polytechnic University of Valencia | Pichot C.,French National Institute for Agricultural Research | Lefevre F.,French National Institute for Agricultural Research
Heredity | Year: 2011

We investigated the variation and short-term evolution of the selfing rate and inbreeding depression (ID) across three generations within a cedar forest that was established from admixture ca 1860. The mean selfing rate was 9.5%, ranging from 0 to 48% among 20 seed trees (estimated from paternally inherited chloroplast DNA). We computed the probability of selfing for each seed and we investigated ID by comparing selfed and outcrossed seeds within progenies, thus avoiding maternal effects. In all progenies, the germination rate was high (88-100%) and seedling mortality was low (0-12%). The germination dynamics differed significantly between selfed and outcrossed seeds within progenies in the founder gene pool but not in the following generations. This transient effect of selfing could be attributed to epistatic interactions in the original admixture. Regarding the seedling growth traits, the ID was low but significant: 8 and 6% for height and diameter growth, respectively. These rates did not vary among generations, suggesting minor gene effects. At this early stage, outcrossed seedlings outcompeted their selfed relatives, but not necessarily other selfed seedlings from other progenies. Thus, purging these slightly deleterious genes may only occur through within-family selection. Processes that maintain a high level of genetic diversity for fitness-related traits among progenies also reduce the efficiency of purging this part of the genetic load. © 2011 Macmillan Publishers Limited All rights reserved. Source

Rodriguez-Fortuno F.J.,University of Pennsylvania | Rodriguez-Fortuno F.J.,Polytechnic University of Valencia | Vakil A.,University of Pennsylvania | Engheta N.,University of Pennsylvania
Physical Review Letters | Year: 2014

The ability to manufacture metamaterials with exotic electromagnetic properties has potential for surprising new applications. Here we report how a specific type of metamaterial - one whose permittivity is near zero - exerts a repulsive force on an electric dipole source, resulting in levitation of the dipole. The phenomenon relies on the expulsion of the time-varying electric field from the metamaterial interior, resembling the perfect diamagnetic expulsion of magnetostatic fields. Leveraging this concept, we study some realistic requirements for the levitation or repulsion of a polarized particle radiating at any frequency, from microwave to optics. © 2014 American Physical Society. Source

Merino E.,Institute Quimica Organica General | Verde-Sesto E.,CSIC - Institute of Polymer Science and Technology | Maya E.M.,CSIC - Institute of Polymer Science and Technology | Iglesias M.,CSIC - Institute of Materials Science | And 2 more authors.
Chemistry of Materials | Year: 2013

We described the use of one porous polymeric aromatic framework (PPAF) with a 9,9′-spiro-bisfluorene unit as a support in heterogeneous catalysis. The material was functionalized with acid and base active sites and used as a bifunctional catalyst in a model cascade reaction. This catalyst was recycled up to eight times with only a small loss of activity. © 2013 American Chemical Society. Source

Igual Munoz A.,Polytechnic University of Valencia | Mischler S.,Ecole Polytechnique Federale de Lausanne
Journal of Materials Science: Materials in Medicine | Year: 2011

The corrosion behaviour and the wear ranking of biomedical high carbon (HC) and low carbon (LC) CoCrMo alloys sliding against an alumina ball in four different simulated body fluids [NaCl and phosphate buffered solutions (PBS) with and without albumin] has been analyzed by tribocorrosion and electrochemical techniques. The effects of alloy and of albumin on corrosion depend on the base electrolyte: differences between LC and HC alloy were only observed in NaCl solutions but not in PBS. Albumin increased significantly corrosion of both alloys in PBS solutions while its effect in NaCl was smaller. The wear ranking of the HC and LC alloys also depends on the environment. In the present study, HC CoCrMo alloy had lower wear resistance in NaCl and PBS + albumin than the LC alloy, while no differences between both alloys were found in the other solutions. This was attributed to surface chemical effects affecting third body behaviour. © Springer Science+Business Media, LLC 2011. Source

Nikolla E.,California Institute of Technology | Roman-Leshkov Y.,Massachusetts Institute of Technology | Moliner M.,Polytechnic University of Valencia | Davis M.E.,California Institute of Technology
ACS Catalysis | Year: 2011

Conversion of carbohydrates to 5-(hydroxymethyl)furfural (HMF) may provide a step forward toward achieving a renewable biomass-based chemicals and fuels platform. Recently, we reported that a tin-containing, high-silica molecular sieve with the zeolite beta topology (Sn-Beta) can efficiently catalyze the isomerization of glucose to fructose in aqueous media at low pH. Herein, we describe the combination of Sn-Beta with acid catalysts in a one vessel, biphasic reactor system to synthesize HMF from carbohydrates such as glucose, cellobiose, and starch with high efficiency. HMF selectivities over 70% were obtained using this "one-pot" biphasic water/tetrahydrofuran (THF) reactor system. The key to successfully achieving the conversions/selectivities reported is that Sn-Beta is able to convert glucose to fructose at pH near 1 and in saturated aqueous salt solutions. © 2011 American Chemical Society. Source

Perez-Lombard L.,Polytechnic University of Valencia | Ortiz J.,Building Research Establishment | Maestre I.R.,University of Cadiz
Applied Energy | Year: 2011

Heating, ventilation and air conditioning (HVAC) systems are the most energy consuming building services representing approximately half of the final energy use in the building sector and between one tenth and one fifth of the energy consumption in developed countries. Despite their significant energy use, there is a lack of a consistent and homogeneous framework to efficiently guide research and energy policies, mainly due to the complexity and variety of HVAC systems but also to insufficient rigour in their energy analysis. This paper reviews energy related aspects of HVAC systems with the aim of establishing a common ground for the analysis of their energy efficiency. The paper focuses on the map of energy flow to deliver thermal comfort: the HVAC energy chain. Our approach deals first with thermal comfort as the final service delivered to building occupants. Secondly, conditioned spaces are examined as the systems where useful heat (or coolth) is degraded to provide comfort. This is followed by the analysis of HVAC systems as complex energy conversion devices where energy carriers are transformed into useful heat and coolth, and finally, the impact of HVAC energy consumption on energy resources is discussed. © 2011 Elsevier Ltd. Source

Darehshoorzadeh A.,Polytechnic University of Catalonia | Cerda-Alabern L.,Polytechnic University of Catalonia | Pla V.,Polytechnic University of Valencia
Computer Networks | Year: 2011

Opportunistic Routing (OR) has been investigated in recent years as a way to increase the performance of multihop wireless networks by exploiting its broadcast nature. In contrast to traditional routing, where traffic is sent along pre-determined paths, in OR an ordered set of candidates is selected for each next-hop. Upon each transmission, the candidates coordinate such that the most priority one receiving the packet actually forwards it. Most of the research in OR has been addressed to investigate candidate selection algorithms. In this paper we propose a discrete time Markov chain to assess the improvement that may be achieved using opportunistic routing. We use our model to compare a selected group of candidate selection algorithms that have been proposed in the literature. Our main conclusion is that optimality is obtained at a high computational cost, with a performance gain very similar to that of much simpler but non-optimal algorithms. Therefore, we conclude that fast and simple OR candidate selection algorithms may be preferable in dynamic networks, where the candidates sets are likely to be updated frequently. © 2011 Elsevier B.V. All rights reserved. Source

Decker H.,Polytechnic University of Valencia | Martinenghi D.,Polytechnic of Milan
IEEE Transactions on Knowledge and Data Engineering | Year: 2011

All methods for efficient integrity checking require all integrity constraints to be totally satisfied, before any update is executed. However, a certain amount of inconsistency is the rule, rather than the exception in databases. In this paper, we close the gap between theory and practice of integrity checking, i.e., between the unrealistic theoretical requirement of total integrity and the practical need for inconsistency tolerance, which we define for integrity checking methods. We show that most of them can still be used to check whether updates preserve integrity, even if the current state is inconsistent. Inconsistency-tolerant integrity checking proves beneficial both for integrity preservation and query answering. Also, we show that it is useful for view updating, repairs, schema evolution, and other applications. © 2006 IEEE. Source

Zarzo M.,Polytechnic University of Valencia
Food Quality and Preference | Year: 2015

Some comprehensive compilations of odor character descriptions are available in the literature, and they contain valuable information to better understand the underlying dimensions of human odor psychophysics. In the present study, principal component analysis was applied to two olfactory databases of perfumery materials publicly available, which are comprised by those odor descriptors most frequently used in perfumery. The projection of descriptors over the two principal axes (two-component solution) led to related plots, which are also similar to the one obtained in a previous study (Zarzo, 2008). Although the descriptive space of odors is highly multidimensional, our results suggest that it is possible to reach a consensus about how to project perfumery scents on a two-dimensional map, and how to interpret the dimensions of that sensory map. One of them discriminates light vs. heavy odors; the orthogonal axis was correlated with hedonic tones, but it is better interpreted as an underlying latent structure that distinguishes feminine vs. masculine cosmetic scents. © 2015 Elsevier Ltd. Source

This protocol describes the aerobic oxidation of aromatic anilines to aromatic azo compounds using gold (Au) nanoparticles supported on TiO(2) as a catalyst. Yields above 98% are achieved under a few bars of oxygen pressure. It should be noted that the use of stoichiometric amounts of environmentally unfriendly reagents, e.g., transition metals and nitrites, commonly used in current syntheses of azo compounds, is avoided using this approach. The protocol is illustrated with the synthesis of parent azobenzene from aniline, and this reaction takes 22 h. Au on TiO(2) can also be used as a hydrogenation catalyst, making it possible to prepare azo compounds directly from nitroaromatics through a two-step (hydrogenation followed by aerobic oxidation), one-pot, one-catalyst reaction. In addition, the catalytic process is efficient for the synthesis of symmetric and a range of asymmetric aromatic azo compounds from the mixtures of two anilines substituted with electron-donor and electron-acceptor substituents. Source

Camacho J.,University of Granada | Ferrer A.,Polytechnic University of Valencia
Journal of Chemometrics | Year: 2012

Cross-validation has become one of the principal methods to adjust the meta-parameters in predictive models. Extensions of the cross-validation idea have been proposed to select the number of components in principal components analysis (PCA). The element-wise k-fold (ekf) cross-validation is among the most used algorithms for principal components analysis cross-validation. This is the method programmed in the PLS_Toolbox, and it has been stated to outperform other methods under most circumstances in a numerical experiment. The ekf algorithm is based on missing data imputation, and it can be programmed using any method for this purpose. In this paper, the ekf algorithm with the simplest missing data imputation method, trimmed score imputation, is analyzed. A theoretical study is driven to identify in which situations the application of ekf is adequate and, more importantly, in which situations it is not. The results presented show that the ekf method may be unable to assess the extent to which a model represents a test set and may lead to discard principal components with important information. On a second paper of this series, other imputation methods are studied within the ekf algorithm. © 2012 John Wiley & Sons, Ltd. Source

Tortajada-Genaro L.A.,Polytechnic University of Valencia
Journal of Chemical Education | Year: 2012

In an undergraduate bioanalytical instrumental lab, students use capillary electrophoresis to quantify l-ascorbic acid (vitamin C) in food samples. The students are tasked to prepare standards, to obtain the calibration curves, and to determine the quantity of l-ascorbic acid in tomato samples (Lycopersicon fruit). A discussion about the function of each component of a capillary electrophoresis instrument, the effect of experimental variables, and the use of different calibration strategies is also given. The experiment has been tested during four courses, showing that lab-activities helped students learn this instrumental technique. © 2012 The American Chemical Society and Division of Chemical Education, Inc. Source

Ortiz-Martinez D.,Polytechnic University of Valencia
Computational Linguistics | Year: 2016

We present online learning techniques for statistical machine translation (SMT). The availability of large training data sets that grow constantly over time is becoming more and more frequent in the field of SMT—for example, in the context of translation agencies or the daily translation of government proceedings. When new knowledge is to be incorporated in the SMT models, the use of batch learning techniques require very time-consuming estimation processes over the whole training set that may take days or weeks to be executed. By means of the application of online learning, new training samples can be processed individually in real time. For this purpose, we define a state-of-the-art SMT model composed of a set of submodels, as well as a set of incremental update rules for each of these submodels. To test our techniques, we have studied two well-known SMT applications that can be used in translation agencies: post-editing and interactive machine translation. In both scenarios, the SMT system collaborates with the user to generate highquality translations. These user-validated translations can be used to extend the SMT models by means of online learning. Empirical results in the two scenarios under consideration show the great impact of frequent updates in the system performance. The time cost of such updates was also measured, comparing the efficiency of a batch learning SMT system with that of an online learning system, showing that online learning is able to work in real time whereas the time cost of batch retraining soon becomes infeasible. Empirical results also showed that the performance of online learning is comparable to that of batch learning. Moreover, the proposed techniques were able to learn from previously estimated models or from scratch. We also propose two new measures to predict the effectiveness of online learning in SMT tasks. The translation system with online learning capabilities presented here is implemented in the open-source Thot toolkit for SMT. © 2016 Association for Computational Linguistics. Source

Shirvani N.,Sharif University of Technology | Ruiz R.,Polytechnic University of Valencia | Shadrokh S.,Sharif University of Technology
International Journal of Production Economics | Year: 2014

This paper deals with a realistic cyclic scheduling problem in the food industry environment in which parallel machines are considered to process perishable jobs with given release dates, due dates and deadlines. Jobs are subject to post-production shelf life limitation and must be delivered to retailers during the corresponding time window bounded by due dates and deadlines. Both early and tardy jobs are penalized by partial weighted earliness/tardiness functions and the overall problem is to provide a cyclic schedule of minimum cost. A mixed integer programming model is proposed and a heuristic solution beside an iterated greedy algorithm is developed to generate good and feasible solutions for the problem. The proposed MIP, heuristic and iterated greedy produce a series of solutions covering a wide range of cases from slow optimal solutions to quick and approximated schedules.© 2014 Published by Elsevier B.V. Source

Borras E.,Instituto Universitario | Tortajada-Genaro L.A.,Polytechnic University of Valencia
International Journal of Environmental Analytical Chemistry | Year: 2012

The determination of multifunctional oxygenated compounds in secondary organic aerosols (SOA) usually requires a derivatisation protocol prior to gas chromatography-mass spectrometry analysis (GC-MS). Our proposed protocol, a combination of O-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine (PFBHA) plus diluted N-methyl-N-trimethyl-silyltrifluoroacetamide (MSTFA) without catalyst, has improved the determination of carbonyls, polyhydroxyl-compounds, hydroxyl- carbonyls, hydroxyl-carboxylic acids and di-carboxylic acids. The optimised derivatisation protocol has been successfully used for blanks, standard mixtures and photo-oxidation products from isoprene and toluene generated in a high-volume simulation chamber (European Photoreactor, EUPHORE). Some previously identified degradation products for isoprene including tetrols such as threitol, erythritol; 2-methyltetrols and 2-methylglyceric acid; and for toluene including nitrophenols, methyl-nitrophenols, benzaldehyde, p-cresol, benzoic acid, glyoxylic acid and methyl-glyoxylic acid, have been identified in our aerosol samples, thus confirming the successful applicability of the proposed derivatisation protocol. Moreover, the reduction of artefacts and enhanced signal-to-noise ratio, have allowed us to extend the number of multifunctional compounds determined. These findings have demonstrated the validity of this analytical strategy, which will contribute to a better understanding of the atmospheric degradation chemistry of biogenic and anthropogenic pollutants. © 2012 Taylor & Francis. Source

del Castillo J.M.,University of Seville | del Castillo J.M.,Polytechnic University of Valencia
Transportmetrica | Year: 2012

Three new models for the flow-density relationship are proposed in this work. The resulting flow-density curves are concave in the whole range of feasible values for the parameters. These models have four parameters, three of them being the jam density, the free-flow speed and the kinematic wave speed. The fourth parameter is a shape parameter. The models allow for a great flexibility for fitting of real traffic flow and density data. A remarkable property of these models is the fact that they yield a bilinear fundamental diagram when the shape parameter tends to infinity. The models have been tested with freeway data and urban data. The results demonstrate that the models achieve an excellent goodness of fit and yield realistic estimates of the parameters. The models proposed in this work are a valuable tool not only for fitting flow-density data but also for its use in traffic flow dynamic models. © 2012 Copyright Taylor and Francis Group, LLC. Source

Barrios M.,University of Tolima | Frances F.,Polytechnic University of Valencia
Hydrological Processes | Year: 2012

Nonlinear dynamics and spatial variability in hydrological systems make the formulation of scaling theories difficult. Therefore, the development of knowledge related to scale effects, scaling techniques, parameterization and linkages of parameters across scales is highly relevant. The main purpose of this work is to analyse the spatial effect of the static storage capacity parameter H u and the saturated hydraulic conductivity parameter k s from microscale (sub-grid level) to mesoscale (grid level) and its implication to the definition of an optimum cell size. These two parameters describe the upper soil water characteristics in the infiltration process conceptualization of the TETIS hydrological model. At microscale, the spatial heterogeneity of H u and k s was obtained generating random parameter fields through probability distribution functions and a spatial dependence model with pre-established correlation lengths. The effective parameters at mesoscale were calculated by solving the inverse problem for each parameter field. Results indicate that the adopted inverse formulation allows transferring the nonlinearity of the system from microscale to the mesoscale via non-stationary effective parameters. Their values at each cell and time step are in the range of zero to the mean value of the parameter at microscale. The stochastic simulations showed that the variance of the estimated effective parameters decreases when the ratio between mesoscale cell size and correlation length at microscale increases. For a ratio greater than 1, we found cell sizes having the characteristics of a representative elementary area (REA); in such case, the microscale variability pattern did not affect the system response at mesoscale. © 2011 John Wiley & Sons, Ltd. Source

Elena S.F.,Institute Biologia Molecular Y Celular Of Plantas | Elena S.F.,Santa Fe Institute | Carrera J.,Institute Biologia Molecular Y Celular Of Plantas | Carrera J.,Polytechnic University of Valencia | Rodrigo G.,Institute Biologia Molecular Y Celular Of Plantas
Current Opinion in Plant Biology | Year: 2011

Omic approaches to the analysis of plant-virus interactions are becoming increasingly popular. These types of data, in combination with models of interaction networks, will aid in revealing not only host components that are important for the virus life cycle, but also general patterns about the way in which different viruses manipulate host regulation of gene expression for their own benefit and possible mechanisms by which viruses evade host defenses. Here, we review studies identifying host genes regulated by viruses and discuss how these genes integrate in host regulatory and interaction networks, with a particular focus on the physical properties of these networks. © 2011 Elsevier Ltd. Source

Fernandez-Llatas C.,Polytechnic University of Valencia
Sensors (Basel, Switzerland) | Year: 2013

The analysis of human behavior patterns is increasingly used for several research fields. The individualized modeling of behavior using classical techniques requires too much time and resources to be effective. A possible solution would be the use of pattern recognition techniques to automatically infer models to allow experts to understand individual behavior. However, traditional pattern recognition algorithms infer models that are not readily understood by human experts. This limits the capacity to benefit from the inferred models. Process mining technologies can infer models as workflows, specifically designed to be understood by experts, enabling them to detect specific behavior patterns in users. In this paper, the eMotiva process mining algorithms are presented. These algorithms filter, infer and visualize workflows. The workflows are inferred from the samples produced by an indoor location system that stores the location of a resident in a nursing home. The visualization tool is able to compare and highlight behavior patterns in order to facilitate expert understanding of human behavior. This tool was tested with nine real users that were monitored for a 25-week period. The results achieved suggest that the behavior of users is continuously evolving and changing and that this change can be measured, allowing for behavioral change detection. Source

Vidal B.,Polytechnic University of Valencia
Optics Communications | Year: 2011

A novel approach to extend the frequency range and improve the resolution of photonic techniques for microwave frequency measurements based on frequency-to-power mapping is demonstrated. The simultaneous use of several amplitude comparison functions allows the extension of the measurement beyond a single monotonic region. Experimental results between 7 and 19 GHz with a resolution better than 100 MHz are presented. © 2011 Elsevier B.V. All rights reserved. Source

Bader P.,Polytechnic University of Valencia | Fischer U.R.,Seoul National University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2013

We consider spherically trapped Bose gases in three dimensions with contact interactions and investigate whether the Bose-Einstein condensate at zero temperature is stable against macroscopic fragmentation into a small number of mutually incoherent pieces. Our results are expressed in terms of a dimensionless interaction measure proportional to the Thomas-Fermi parameter. It is shown that while three-dimensional condensates are inherently much more stable against macroscopic fragmentation than their quasi-one- and quasi-two-dimensional counterparts, they fragment at a sufficiently large value of the dimensionless interaction measure, which we determine both fully numerically and semianalytically from a continuum limit of large particle numbers. © 2013 American Physical Society. Source

Roldan E.M.,Polytechnic University of Valencia
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference | Year: 2011

This study is aimed at characterizing three signal entropy measures, Approximate Entropy (ApEn), Sample Entropy (SampEn) and Multiscale Entropy (MSE) over real EEG signals when a number of samples are randomly lost due to, for example, wireless data transmission. The experimental EEG database comprises two main signal groups: control EEGs and epileptic EEGs. Results show that both SampEn and ApEn enable a clear distinction between control and epileptic signals, but SampEn shows a more robust performance over a wide range of sample loss ratios. MSE exhibits a poor behavior for ratios over a 40% of sample loss. The EEG non-stationary and random trends are kept even when a great number of samples are discarded. This behavior is similar for all the records within the same group. Source

Alberola-Rubio J.,Polytechnic University of Valencia
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference | Year: 2011

Preterm birth is the main cause of the neonatal morbidity. Noninvasive recording of uterine myoelectrical activity (electrohysterogram, EHG) could be an alternative to the monitoring of uterine dynamics which are currently based on tocodynamometers (TOCO). The analysis of uterine electromyogram characteristics could help the early diagnosis of preterm birth. Laplacian recordings of other bioelectrical signals have proved to enhance spatial selectivity and to reduce interferences in comparison to monopolar and bipolar surface recordings. The main objective of this paper is to check the feasibility of the noninvasive recording of uterine myoelectrical activity by means of laplacian techniques. Four bipolar EHG signals, discrete laplacian obtained from five monopolar electrodes and the signals picked up by two active concentric-ringed-electrodes were recorded on 5 women with spontaneous or induced labor. Intrauterine pressure (IUP) and TOCO were also simultaneously recorded. To evaluate the uterine contraction detectability of the different noninvasive methods in comparison to IUP the contractions consistency index (CCI) was calculated. Results show that TOCO is less consistent (83%) than most EHG bipolar recording channels (91%, 83%, 87%, and 76%) to detect the uterine contractions identified in IUP. Moreover laplacian EHG signals picked up by ringed-electrodes proved to be as consistent (91%) as the best bipolar recordings in addition to significantly reduce ECG interference. Source

Fernandez-Llatas C.,Polytechnic University of Valencia
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference | Year: 2011

Nursing homes usually host large accounts of persons with different levels of dementia. Detecting dementia process in early stages may allow the application of mechanisms to reduce or stop the cognitive impairment. Our ultimate objective is to demonstrate that the use of persuasive techniques may serve to motivate these subjects and induct re-learning mechanisms to stop mental impairment. Nevertheless, this requires the study of the behaviour of each patient individually in order to detect conduct disorders in their living ambient. This study presents a behavior pattern detection architecture based on the Ambient Assisted Living paradigm and Workflow Mining technology to enable re-learning mechanisms in dementia processes via providing tools to automate the conduct disorder detection. This architecture fosters the use of Workflows as representation languages to allow health professionals to represent persuasive motivation protocols in the AAL environment to react individually to dementia symptoms detected. Source

Contat-Rodrigo L.,Polytechnic University of Valencia
Polymer Degradation and Stability | Year: 2013

The oxo-degradation process of polypropylene (PP) samples containing different concentrations (4% and 10% w/w) of pro-oxidant/pro-degradant additive Envirocare™ AG1000C was investigated under accelerated test conditions. Samples were initially exposed to UV radiation for 300 h. The tendency to biodegradation in soil medium of these UV-aged samples was then indirectly assessed by an indirect method for a period of 6 months. The entire degradation process of these materials was first examined by monitoring changes in their morphological properties (melting temperature, maximum lamellar thickness and crystallinity) with the ageing time, by Differential Scanning Calorimetry (DSC). Then, changes in the thermal properties (onset temperature and maximum decomposition temperature) of these materials with the ageing time were analysed by Thermogravimetric Analysis (TGA). Furthermore, the kinetics of the thermal decomposition of these PP samples with pro-oxidant/pro-degradant was also studied during the oxo-degradation process, by means of the Chang differential method. During exposure to UV radiation, the more significant changes in the morphological and thermal properties that were detected in PP samples containing pro-oxidant/pro-degradant additive compared to pure PP, clearly suggest a higher level of oxidation in these samples, confirming the effectiveness of this pro-oxidant/pro-degradant additive in promoting the abiotic oxidation of polypropylene during UV-irradiation. Moreover, the level of oxidation observed in UV-aged samples seems to be dependent on the additive load. On the other hand, during incubation in soil medium, changes in the morphological and thermal properties of previously photo-oxidized PP samples with pro-oxidant/pro-degradant were detected that indirectly support a certain progress of oxidation, indicating that previous abiotic oxidation can promote further degradation of the polypropylene matrix by soil microorganisms. In general, both morphological and thermal properties exhibit a non-linear dependency with the incubation time in soil, supporting the idea that biodegradation is a complex process that occurs in different stages. Furthermore, the extent of the changes in these properties during soil incubation was found to be proportional to the pro-oxidant/pro-degradant load and the previous photo-oxidation level. © 2013 Elsevier Ltd. Source

Vidal G.,Polytechnic University of Valencia
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2011

Conjunctive partial deduction is a well-known technique for the partial evaluation of logic programs. The original formulation follows the so called online approach where all termination decisions are taken on-the-fly. In contrast, offline partial evaluators first analyze the source program and produce an annotated version so that the partial evaluation phase should only follow these annotations to ensure the termination of the process. In this work, we introduce a lightweight approach to conjunctive partial deduction that combines some of the advantages of both online and offline styles of partial evaluation. © 2011 Springer-Verlag. Source

The steady, laminar boundary layer flow and heat transfer with radiation effects using the nonlinear Rosseland approximation induced in a quiescent, electrically conducting, visco-elastic fluid by a permeable surface stretched with velocity uw(x)=ax+cx2 in the presence of a transverse magnetic field with heat source/sink are investigated. The problem only admits local-similarity results for a nonlinear stretched boundary surface with constant temperature (i.e., T=Twaty=0 (Tw constant)). Two classes of visco-elastic fluid are considered, namely, the second-grade and Walters' liquid B fluids. A previously developed analytical solution for this flow, first used in Ref. [49], has been extended to analyze radiative nonlinear heat transfer. The effects of a transverse magnetic field, visco-elasticity, internal heat generation/absorption, suction/injection at the sheet, Prandtl number, power-law sheet velocity and thermal radiation onto heat transfer characteristics are widely analyzed. The results for the velocity and temperature field are presented through tables and graphs and discussed. © 2014 Elsevier Ltd. Source

Cortell R.,Polytechnic University of Valencia
Progress in Computational Fluid Dynamics | Year: 2012

A numerical analysis for free convection boundary layers along a permeable vertical flat surface with prescribed power-law temperature distribution T w(x) = T∞ + Ax k at y = 0 embedded in a fluid-saturated porous medium and subjected to an applied lateral mass flux proportional to the x k-1/2 quantity is presented. We provide detailed comparisons by considering both analytical and numerical findings of previous authors, and a very good agreement is encountered. The results obtained elucidate reliability and efficiency of the technique. Copyright © 2012 Inderscience Enterprises Ltd. Source

Estrela T.,Jucar River Basin Authority of Spanish Ministry of Agriculture | Estrela T.,Polytechnic University of Valencia | Vargas E.,Evaluacion de Recursos Naturales S.A. EVREN S.A.
Water Resources Management | Year: 2012

Water is a strategic resource for the economic, social and environmental development. However, water scarcity and droughts are current challenges to this growth, as it is reflected in European Union (EU) water policies, and in national and regional growing initiatives. In addition, these water related issues could worsen by climate change effects, adding pressure to already water stressed areas. This paper presents a general overview of drought management in the European Union, reviews scientific and technical advances, the status of implementation of policy tools and focuses on drought management plans. It analyses the specific case of Spain, a country characterised by presenting a high irregularity in temporal and spatial distribution of water resources and numerous areas affected by water scarcity and droughts. Details are presented on the National Drought Indicator System and drought management plans approved in 2007 in Spain, which represent strategic tools with positive results in drought warning and impact mitigation respectively. © 2012 Springer Science+Business Media B.V. Source

Framinan J.M.,University of Seville | Ruiz R.,Polytechnic University of Valencia
International Journal of Production Research | Year: 2012

It has frequently been stated that there exists a gap between production scheduling theory and practice. In order to put theoretical findings into practice, advances in scheduling models and solution procedures should be embedded into a piece of software - a scheduling system - in companies. This results in a process that entails (1) determining its functional features, and (2) adopting a successful strategy for its development and deployment. In this paper we address the latter question and review the related literature in order to identify descriptions and recommendations of the main aspects to be taken into account when developing such systems. These issues are then discussed and classified, resulting in a set of guidelines that can help practitioners during the process of developing and deploying a scheduling system. In addition, identification of these issues can provide some insights to drive theoretical scheduling research towards those topics more in demand by practitioners, and thus help to close the aforementioned gap. © 2012 Copyright Taylor and Francis Group, LLC. Source

Alkorta I.,Polytechnic University of Valencia | Popelier P.L.A.,Manchester Interdisciplinary Biocentre MIB
Carbohydrate Research | Year: 2011

For the first time the mutarotation mechanism of furanose rings has been investigated, with and without solvent. The transformations from open-chain furanose to d-erythrose and d-threose have been studied at B3LYP/6-311++G(d,p) and G3MP2B3 levels, in vacuum and in solution through continuum solvation models. We studied the catalytic influence of one, two or three water molecules, as well as simplified models of carbohydrates, that is, methanol and 1,2-ethanediol. Water molecules significantly reduce the energy barrier of the hemiacetal formation occurring between the open-chain and furanose configurations. The energy barrier is optimally reduced by two water molecules. Methanol yields a smaller transition state barrier than the one obtained with a single water molecule. In contrast, 1,2-ethanediol does not provide a lower transition state compared to the barrier in the presence of two water molecules. © 2011 Elsevier Ltd. All rights reserved. Source

Chyzhyk D.,Polytechnic University of Valencia
Frontiers in Artificial Intelligence and Applications | Year: 2012

Bootstrapped Dendritic Classifiers (BDC) is an ensemble of weak Dendritic Classifiers trained combining their output by majority voting to obtain improved classification generalization performance. Weak Dendritic Classifiers are trained on bootstrapped samples of the train data setting a limit on the number of dendrites. There is no additional data preprocessing. This paper explores classification performance and the sensitivity to the number of classifiers and the number of dendrites on the classification of Alzheimer's Disease (AD) patients, comparing with previous results obtained on the same feature database, which are obtained from T1-weighted MRI data of healthy controls and AD patients. © 2012 The authors and IOS Press. All rights reserved. Source

Camacho J.,University of Granada | Ferrer A.,Polytechnic University of Valencia
Chemometrics and Intelligent Laboratory Systems | Year: 2014

This is the second paper of a series devoted to provide theoretical and practical results and new algorithms for the selection of the number of Principal Components (PCs) in Principal Component Analysis (PCA) using cross-validation. The study is especially focused on the element-wise k-fold (ekf), which is among the most used algorithms for that purpose. In this paper, a taxonomy of PCA applications is proposed and it is argued that cross-validatory algorithms computing the prediction error in observable variables, like ekf, are only suited for a class of applications. A number of cross-validation methods, several of which are original, are compared in two applications of this class: missing data imputation and compression. The results show that the ekf is especially suited for missing data applications while other traditional cross-validation methods, those by Wold and Eastment and Krzanowski, are not found to provide useful outcomes in any of the two applications. These results are of special value considering that the methods investigated are computed in the main commercial software packets for chemometrics. Finally, the choice of the missing data algorithm within ekf is also investigated. © 2013 Elsevier B.V. Source

Gimenez-Chornet V.,Polytechnic University of Valencia
International Journal of Information Management | Year: 2012

Web 2.0 has had an impact on library web sites making them more interactive with users, giving rise to the term Library 2.0. What is meant by Web 2.0 tools is generally understood but the degree of implementation of these tools in libraries is largely unknown. This study reports on the implementation of these tools in national libraries all over the world in order to give an objective measure of the impact of Web 2.0 on library web sites. © 2011 Elsevier Ltd. All rights reserved. Source

Stratakis M.,University of Crete | Garcia H.,Polytechnic University of Valencia
Chemical Reviews | Year: 2012

Recent achievements in the activation of dihydrogen, epoxides, alcohols, carbonyl compounds, alkynes, hydrosilanes, or boron hydrides, and on CO 2 fixation, C-C crosscoupling reactions, hydrogen transfer catalysis, are presented. Hardacre and co-workers used heterogenized Au nanoparticles supported on silica to achieve good to excellent selectivity in the benzylation of substituted benzenes with benzyl alcohol. Ying and co-workers used successfully a heterogeneous air- and water-stable reusable PbS-supported gold catalyst for the three-component coupling reaction. Keane and co-workers studied in detail the influence of support and particle size on activity and selectivity regarding the hydrogenation of mdinitrobenzene and chloronitrobenzene. Hii and co-workers developed a flow reactor for the highly selective direct alkylation of amines by alcohols using Au/TiO 2 as catalyst, without the requirement for an inert atmosphere or base. Source

Law E.L.-C.,University of Leicester | Abrahao S.,Polytechnic University of Valencia
International Journal of Human Computer Studies | Year: 2014

User Experience (UX) is a maturing research area pertaining to as well as extending beyond the traditional usability. Issues in the realm of usability may be amplified in UX because of its larger scope. Four key non-orthogonal issues are definition, modeling, method selection, and interplay between evaluation and development. Leveraging the legacy of a series of related research activities, this Special Issue (SI) aims to develop a deeper understanding of how evaluation feedback shapes software development, especially when experiential qualities such as fun, trust, esthetic values are concerned. Three articles addressing this specific topic from different perspectives and with different approaches are included in this SI. © 2014 Published by Elsevier Ltd. Source

Nagata Y.,Tokyo Institute of Technology | Soler D.,Polytechnic University of Valencia
Expert Systems with Applications | Year: 2012

The asymmetric traveling salesman problem (ATSP) is one of the most important combinatorial optimization problems. It allows us to solve, either directly or through a transformation, many real-world problems. We present in this paper a new competitive genetic algorithm to solve this problem. This algorithm has been checked on a set of 153 benchmark instances with known optimal solution and it outperforms the results obtained with previous ATSP heuristic methods. © 2012 Elsevier Ltd. All rights reserved. Source

An analysis is presented for the steady non-linear viscous flow of an incompressible viscous fluid over a horizontal surface of variable temperature with a power-law velocity under the influences of suction/blowing, viscous dissipation and thermal radiation. Numerical results are illustrated by means of tables and graphs. The governing partial differential equations are converted into nonlinear ordinary differential equations by a similarity transformation. The effects of the stretching parameter n, suction/blowing parameter b, Prandtl number σ, Eckert number E c(E c *) and radiation parameter N R are discussed. Two cases are studied, namely, (i) Prescribed surface temperature (PST case) and, (ii) Prescribed heat flux at the sheet (PHF case). © 2011 Springer Science+Business Media B.V. Source

Hernandez-Orallo J.,Polytechnic University of Valencia | Dowe D.L.,Monash University
Artificial Intelligence | Year: 2010

In this paper, we develop the idea of a universal anytime intelligence test. The meaning of the terms "universal" and "anytime" is manifold here: the test should be able to measure the intelligence of any biological or artificial system that exists at this time or in the future. It should also be able to evaluate both inept and brilliant systems (any intelligence level) as well as very slow to very fast systems (any time scale). Also, the test may be interrupted at any time, producing an approximation to the intelligence score, in such a way that the more time is left for the test, the better the assessment will be. In order to do this, our test proposal is based on previous works on the measurement of machine intelligence based on Kolmogorov complexity and universal distributions, which were developed in the late 1990s (C-tests and compression-enhanced Turing tests). It is also based on the more recent idea of measuring intelligence through dynamic/interactive tests held against a universal distribution of environments. We discuss some of these tests and highlight their limitations since we want to construct a test that is both general and practical. Consequently, we introduce many new ideas that develop early "compression tests" and the more recent definition of "universal intelligence" in order to design new "universal intelligence tests", where a feasible implementation has been a design requirement. One of these tests is the "anytime intelligence test", which adapts to the examinee's level of intelligence in order to obtain an intelligence score within a limited time. © 2010 Elsevier B.V. Source

Orduna-Malea E.,Polytechnic University of Valencia | Delgado Lopez-Cozar E.,University of Granada
Scientometrics | Year: 2014

In November 2012 the Google Scholar Metrics (GSM) journal rankings were updated, making it possible to compare bibliometric indicators in the ten languages indexed-and their stability-with the April 2012 version. The h-index and h-5 median of 1,000 journals were analysed, comparing their averages, maximum and minimum values and the correlation coefficient within rankings. The bibliometric figures grew significantly. In just seven and a half months the h-index of the journals increased by 15 % and the median h-index by 17 %. This growth was observed for all the bibliometric indicators analysed and for practically every journal. However, we found significant differences in growth rates depending on the language in which the journal is published. Moreover, the journal rankings seem to be stable between April and November, reinforcing the credibility of the data held by Google Scholar and the reliability of the GSM journal rankings, despite the uncontrolled growth of Google Scholar. Based on the findings of this study we suggest, firstly, that Google should upgrade its rankings at least semi-annually and, secondly, that the results should be displayed in each ranking proportionally to the number of journals indexed by language. © 2013 Akadémiai Kiadó, Budapest, Hungary. Source

Bataller R.C.,Polytechnic University of Valencia
Fluid Dynamics and Materials Processing | Year: 2011

We present a numerical study of the flow and heat transfer of an incompressible upper-convected Maxwell (UCM) fluid in the presence of an uniform transverse magnetic field over a porous stretching sheet taking into account suction at the surface as well as viscous dissipation and thermal radiation effects. Selected similarity analyses have been carried out by means of a numerical implementation. The effects on the velocity and temperature fields over the sheet of the parameters like elasticity number, suction velocity, magnetic parameter, radiation parameter, Prandtl number and Eckert number are also analyzed. © 2011 Tech Science Press. Source

Nebot J.P.,Polytechnic University of Valencia
IEEE Transactions on Image Processing | Year: 2014

Angular intraprediction (AIP) is a coding tool that has been incorporated into the video coding standards H.264/AVC (Advanced Audio Coding) and High Efficient Video Coding. In this paper, we study how the efficiency of AIP depends on its prediction parameters. To carry out this paper, we first theoretically analyze the variance of the error incurred when a perfectly directional signal is predicted in a certain direction. The results of this analysis are then used to study the efficiency of AIP when it is applied to a distribution of directions. To facilitate mathematical derivations, we make several assumptions about the signal and the prediction process, and we use some approximations. This allows us to obtain simple expressions for the variance of the AIP prediction error as a function of signal and prediction parameters. Finally, we compare our theoretical results with the results obtained from the prediction of images containing rectilinear edges. This comparison shows that our theoretical expressions follow the main trends of the experimental results except when AIP is performed with a very high accuracy. © 1992-2012 IEEE. Source

Bastidas V.M.,TU Berlin | Perez-Fernandez P.,TU Berlin | Perez-Fernandez P.,Polytechnic University of Valencia | Vogl M.,TU Berlin | Brandes T.,TU Berlin
Physical Review Letters | Year: 2014

We investigate precursors of critical behavior in the quasienergy spectrum due to the dynamical instability in the kicked top. Using a semiclassical approach, we analytically obtain a logarithmic divergence in the density of states, which is analogous to a continuous excited state quantum phase transition in undriven systems. We propose a protocol to observe the cusp behavior of the magnetization close to the critical quasienergy. © 2014 American Physical Society. Source

Viroids belonging to the family Avsunviroidae are the only functional RNAs known to traffic selectively into chloroplasts. Subcellular targeting is a critical step in guaranteeing their access to the machineries involved in their replication. However, the host mechanisms exploited by these non coding pathogenic RNAs to be selectively imported into chloroplasts are poorly understood. Recently, we provide evidence supporting the idea that the Avsunviroidae have evolved to subvert a signaling mechanism between the nucleus and chloroplasts to regulate their differential compartmentalization into the chloroplast of infected cells. Here, we discuss our model and previous observations that provide biological relevance to our hypothesis. Source

Alvarez-Ponce D.,National University of Ireland, Maynooth | Alvarez-Ponce D.,Polytechnic University of Valencia
BMC Evolutionary Biology | Year: 2012

Background: Proteins evolve at disparate rates, as a result of the action of different types and strengths of evolutionary forces. An open question in evolutionary biology is what factors are responsible for this variability. In general, proteins whose function has a great impact on organisms' fitness are expected to evolve under stronger selective pressures. In biosynthetic pathways, upstream genes usually evolve under higher levels of selective constraint than those acting at the downstream part, as a result of their higher hierarchical position. Similar observations have been made in transcriptional regulatory networks, whose upstream elements appear to be more essential and subject to selection. Less well understood is, however, how selective pressures distribute along signal transduction pathways. Results: Here, I combine comparative genomics and directed protein interaction data to study the distribution of evolutionary forces across the human signal transduction network. Surprisingly, no evidence was found for higher levels of selective constraint at the upstream network genes (those occupying more hierarchical positions). On the contrary, purifying selection was found to act more strongly on genes acting at the downstream part of the network, which seems to be due to downstream genes being more highly and broadly expressed, performing certain functions and, in particular, encoding proteins that are more highly connected in the protein-protein interaction network. When the effect of these confounding factors is discounted, upstream and downstream genes evolve at similar rates. The trends found in the overall signaling network are exemplified by analysis of the distribution of purifying selection along the mammalian Ras signaling pathway, showing that upstream and downstream genes evolve at similar rates. Conclusions: These results indicate that the upstream/downstream position of proteins in the signal transduction network has, in general, no direct effect on their rates of evolution, suggesting that upstream and downstream genes are similarly important for the function of the network. This implies that natural selection differently distributes across signal transduction networks and across biosynthetic and transcriptional regulatory networks, which might reflect fundamental differences in their function and organization. © 2012 Alvarez-Ponce; licensee BioMed Central Ltd. Source

Zadok A.,Bar - Ilan University | Antman Y.,Bar - Ilan University | Primerov N.,Ecole Polytechnique Federale de Lausanne | Denisov A.,Ecole Polytechnique Federale de Lausanne | And 3 more authors.
Laser and Photonics Reviews | Year: 2012

Optical sensing offers an attractive solution to the societal concern for prevention of natural and human-generated threats and for efficient use of natural resources. The unprecedented properties of optical fibers make them ideal for implementing a 'nervous system' in structural health monitoring: they are small, low-cost and electrically and chemically inert. In particular, the nonlinear interaction of stimulated Brillouin scattering allows for the distributed measurement of strain and temperature with tens of km range. In this work, a novel, radar-inspired technique for random-access Brillouin scattering-based sensors is shown, making a significant step towards a real optical sensing nerve. The method selectively addresses each fiber segment as a distinct sensing element in a synaptic neuronal system. The measurement principle relies on phase-coding of both the Brillouin pump and signal waves by a high-rate, pseudo-random bit sequence. Temperature measurements with 1 cm resolution are reported. The measurement range is scalable to several km. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Rajabi F.,Payame Noor University | Naserian S.,Payame Noor University | Primo A.,Polytechnic University of Valencia | Luque R.,University of Cordoba, Spain
Advanced Synthesis and Catalysis | Year: 2011

The present manuscript describes a simple, efficient and environmentally friendly room temperature aqueous catalytic approach to the selective preparation of sulfoxides from sulfides utilising low-loaded supported iron oxide nanoparticles and aqueous hydrogen peroxide as oxidant. Materials could be easily recovered from the reaction mixture and reused ten times without any loss in activity and no metal leaching was observed during the reaction. This is thus the first selective aqueous oxidation of sulfides using an iron-based heterogeneous system. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Alfalla-Luque R.,University of Seville | Marin-Garcia J.A.,Polytechnic University of Valencia | Medina-Lopez C.,University of Seville
International Journal of Production Economics | Year: 2015

This paper focuses on the interrelationships among the different dimensions of supply chain integration. Specifically, it examines the relationship between employee commitment and supply chain integration dimensions to explain several performance measures, such as flexibility, delivery, quality, inventory and customer satisfaction. Very little research has been conducted onto this topic, since employee commitment is rarely included as an antecedent of the effect of supply chain integration on performance. Seven research models have been analysed with Structural Equation Models using a multiple-informant international sample of 266 mid-to-large-size manufacturing plants. The findings suggest that the relationship between employee commitment and operational performance is fully mediated by supply chain integration. Employee commitment contributes to improving internal integration, and internal integration affects performance both directly and indirectly. Moreover, obtaining internal integration helps to achieve supplier and customer integration. As a result, companies should strive to achieve both employee commitment and internal integration, as they mutually reinforce each other. Similarly, managers should achieve internal integration before external integration and include external integration at the strategic level in order to reap the greatest advantages from supply chain integration. Meanwhile, managers should promote employee commitment not only for better supply chain success, but also to mitigate the barriers of supply chain management implementation. © 2014 Elsevier B.V. Source

Ganan-Calvo A.M.,Polytechnic University of Valencia | Rebollo-Munoz N.,University of Extremadura | Montanero J.M.,University of Extremadura
New Journal of Physics | Year: 2013

We aim to establish the scaling laws for both the minimum rate of flow attainable in the steady cone-jet mode of electrospray, and the size of the resulting droplets in that limit. Use is made of a small body of literature on Taylor cone-jets reporting precise measurements of the transported electric current and droplet size as a function of the liquid properties and flow rate. The projection of the data onto an appropriate non-dimensional parameter space maps a region bounded by the minimum rate of flow attainable in the steady state. To explain these experimental results, we propose a theoretical model based on the generalized concept of physical symmetry, stemming from the system time invariance (steadiness). A group of symmetries rising at the cone-to-jet geometrical transition determines the scaling for the minimum flow rate and related variables. If the flow rate is decreased below that minimum value, those symmetries break down, which leads to dripping. We find that the system exhibits two instability mechanisms depending on the nature of the forces arising against the flow: one dominated by viscosity and the other by the liquid polarity. In the former case, full charge relaxation is guaranteed down to the minimum flow rate, while in the latter the instability condition becomes equivalent to the symmetry breakdown by charge relaxation or separation. When cone-jets are formed without artificially imposing a flow rate, a microjet is issued quasi-steadily. The flow rate naturally ejected this way coincides with the minimum flow rate studied here. This natural flow rate determines the minimum droplet size that can be steadily produced by any electrohydrodynamic means for a given set of liquid properties. © IOP Publishing and Deutsche Physikalische Gesellschaft. Source

Acedo L.,Polytechnic University of Valencia
Physics Essays | Year: 2013

In this paper, we propose a variable speed of light (VSL) theory in which both the speed of light, c, and the inertial and gravitational masses, m, depend on the age of the universe. From a purely phenomenological standpoint, both c and m are supposed to be approximate linear functions of the form c(t)=c 0(1-β H0 t), m(t)=m0(1+2β H 0 t), where H0 is the Hubble parameter at the present time, c0 and m0 are, respectively, the initial values of the speed of light and the mass of a given particle at that particular instant of time, taken as reference to the present cosmological epoch. Furthermore, β is a constant. In fact, we calculate the perturbations in the orbits of the planets in the solar system. We can deduce that β is of the order of magnitude of the fine-structure constant. This model explains both the anomalous secular increase of the astronomical unit and the recently reported anomalous increase of the Moon's orbital eccentricity. © 2013 Physics Essays Publication. Source

Hernandez-Orallo J.,Polytechnic University of Valencia
Artificial General Intelligence - Proceedings of the Third Conference on Artificial General Intelligence, AGI 2010 | Year: 2010

The measurement of intelligence is usually associated with the performance over a selection of tasks or environments. The most general approach in this line is called Universal Intelligence, which assigns a probability to each possible environment according to several constructs derived from Kolmogorov complexity. In this context, new testing paradigms are being defined in order to devise intelligence tests which are anytime and universal: valid for both artificial intelligent systems and biological systems, of any intelligence degree and of any speed. In this paper, we address one of the pieces in this puzzle: the definition of a general, unbiased, universal class of environments such that they are appropriate for intelligence tests. By appropriate we mean that the environments are discriminative and that they can be feasibly built, in such a way that the environments can be automatically generated and their complexity can be computed. Source

Brughera A.,Boston University | Dunai L.,Polytechnic University of Valencia | Hartmann W.M.,Michigan State University
Journal of the Acoustical Society of America | Year: 2013

The smallest detectable interaural time difference (ITD) for sine tones was measured for four human listeners to determine the dependence on tone frequency. At low frequencies, 250-700 Hz, threshold ITDs were approximately inversely proportional to tone frequency. At mid-frequencies, 700-1000 Hz, threshold ITDs were smallest. At high frequencies, above 1000 Hz, thresholds increased faster than exponentially with increasing frequency becoming unmeasurably high just above 1400 Hz. A model for ITD detection began with a biophysically based computational model for a medial superior olive (MSO) neuron that produced robust ITD responses up to 1000 Hz, and demonstrated a dramatic reduction in ITD-dependence from 1000 to 1500 Hz. Rate-ITD functions from the MSO model became inputs to binaural display models-both place based and rate-difference based. A place-based, centroid model with a rigid internal threshold reproduced almost all features of the human data. A signal-detection version of this model reproduced the high-frequency divergence but badly underestimated low-frequency thresholds. A rate-difference model incorporating fast contralateral inhibition reproduced the major features of the human threshold data except for the divergence. A combined, hybrid model could reproduce all the threshold data. © 2013 Acoustical Society of America. Source

Museros P.,Polytechnic University of Valencia | Moliner E.,Jaume I University | Martinez-Rodrigo M.D.,Jaume I University
Journal of Sound and Vibration | Year: 2013

The advent of high-speed railways has raised many concerns regarding the behaviour of bridges. Particularly, the analysis of the free vibrations generated by each load is of great interest because they can possibly accumulate and create resonance phenomena. Regarding simply supported beams, earlier contributions showed that the free vibrations created by a single moving force are of maximum or zero amplitude (cancellation) for certain speeds. In the present paper new closed-form expressions are given for the cancellation speeds of a generic mode, as well as for the most representative points of maximum amplitude. Similar new results are provided for elastically supported beams as well. A simpler, closed-form approximate expression of the cancellation condition for an elastically supported beam is also derived from the analysis of a single passing load; this approximate formula is in good agreement with the exact results. Knowing a priori the speeds of maximum free vibrations or cancellation is of great interest for experimental tests on bridges, particularly as regards the evaluation of amplitude-dependent magnitudes such as structural damping. Regarding the resonance phenomena, if the resonance speeds coincide with either a maximum free vibration or a cancellation speed, then a maximum resonance or a cancellation of resonance will occur. The most relevant cases thereof have been investigated, and new expressions which allow predicting them for a generic mode are given. Finally, a new approximate formula is proposed for estimating the maximum acceleration of simply supported bridges caused by resonances of the fundamental mode. After extensive numerical testing, the formula has proved to be a useful tool for a first assessment of simply supported bridges according to building codes such as Eurocodes. © 2012 Elsevier Ltd. Source

Vidal B.,Polytechnic University of Valencia
Optics Letters | Year: 2012

A technique for the frequency multiplication of microwave signals based on the combination of two optical nonlinear phenomena in a single nonlinear fiber is investigated. Multiple four-wave mixing is used to generate harmonics on an externally modulated optical carrier while polarization pulling through stimulated Brillouin scattering is used to filter the desired harmonics. Microwave signals in the 60 GHz region are generated showing harmonic frequency multiplication factors of up to 25 with a suppression of undesired harmonics better than 20 dB. © 2012 Optical Society of America. Source

Ardid M.,Polytechnic University of Valencia
Nuclear and Particle Physics Proceedings | Year: 2016

The ANTARES Collaboration is operating the largest water Cherenkov neutrino telescope in the Northern hemisphere, installed in the Mediterranean Sea. One of the objectives of ANTARES is the search for neutrinos produced in self-annihilation of Dark Matter particles. The results on the search for Dark Matter annihilations in the Sun and in the Galactic Centre with the data recorded between 2007 and 2012 are presented. The search on the Sun has resulted in competitive limits on the WIMP-proton cross-section, and they are compared to the ones of other indirect and direct detection experiments as well as to predictions of SUSY models. Results of ANTARES on Dark Matter searches towards the Galactic Centre have concluded with competitive limits on the annihilation cross-sections for high mass WIMPs that disfavours the interpretation of the PAMELA electron/positron excesses (constrained by Fermi-LAT and H.E.S.S.) as a signal from dark matter self-annihilations. © 2015 Elsevier B.V. Source

Sippel P.,University of Augsburg | Denysenko D.,University of Augsburg | Loidl A.,University of Augsburg | Lunkenheimer P.,University of Augsburg | And 2 more authors.
Advanced Functional Materials | Year: 2014

The electronic structures and band gaps of MFU-4-type metal-organic frameworks can be systematically engineered leading to a family of isostructural microporous solids. Electrical properties of the microcrystalline samples are investigated by temperature-dependent broad-band dielectric and optical spectroscopy, which are corroborated by full band structure calculations performed for framework and cluster model compounds at multiple levels of density functional theory. The combined results glean a detailed picture of relative shifts and dispersion of molecular orbitals when going from zero-dimensional clusters to three-dimensional periodic solids, thus allowing to develop guidelines for tailoring the electronic properties of this class of semiconducting microporous solids via a versatile building block approach. Thus, engineering of the band gap in MFU-4 type compounds can be achieved by adjusting the degree of conjugation of the organic ligand or by choosing an appropriate metal whose partially occupied d-orbitals generate bands below the LUMO energy of the ligand which, for example, is accomplished by octahedral Co(II) ions in Co-MFU-4. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Cordero P.,Polytechnic University of Valencia
Journal of Industrial Engineering and Management | Year: 2013

Purpose: This paper examines the current methodologies and approaches developed to estimate carbon footprint in supply chains and the studies existing in the literature review about the application of these methodologies and other new approaches proposed by some authors. Design/methodology/approach: Literature review about methodologies developed by some authors for determining greenhouse gases emissions throughout the supply chain of a given sector or organization. Findings and Originality/value: Due to its usefulness for the design and management of a sustainable supply chain management, methodologies for calculating carbon footprint across the supply chain are recommended by many authors not only to reduce GHG emissions but also to optimize it in a cost-effective manner. Although these approaches are in first stages of development and the literature is scarce, different methodologies for estimating CF emissions which include EIO analysis models and standardized methods and guidance have been developed, some of them applicable to supply chains especially methodologies for calculating CF of a specific economic sector supply chain in a territory or country and for calculating CF of an organization applicable to the estimation of GHG emissions of a specific company supply chain. Source

Arnanz A.,CSIC - Institute of Materials Science | Pintado-Sierra M.,Institute Quimica Organica General | Corma A.,Polytechnic University of Valencia | Iglesias M.,CSIC - Institute of Materials Science | Sanchez F.,Institute Quimica Organica General
Advanced Synthesis and Catalysis | Year: 2012

A bifunctional metal organic framework catalyst containing palladium and copper(II) benzene-1,3,5-tricarboxylate - MOF-Cu(BTC)-[Pd] - has been prepared. This catalyst enables the performance of the tandem Sonogashira/click reaction starting from 2-iodobenzylbromide, sodium azide and alkynes to produce 8H-[1,2,3]triazolo[5,1-a]isoindoles with good yields under mild reaction conditions. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Decker H.,Polytechnic University of Valencia
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2011

Answers to queries in possibly inconsistent databases may not have integrity. We formalize 'has integrity' on the basis of a definition of 'causes'. A cause of an answer is a minimal excerpt of the database that explains why the answer has been given. An answer has integrity if one of its causes does not overlap with any cause of integrity violation. © 2011 Springer-Verlag. Source

Blum C.,Polytechnic University of Catalonia | Miralles C.,Polytechnic University of Valencia
Computers and Operations Research | Year: 2010

Certain types of manufacturing processes can be modelled by assembly line balancing problems. In this work we deal with a specific assembly line balancing problem that is known as the assembly line worker assignment and balancing problem (ALWABP). This problem appears in settings where tasks must be assigned to workers, and workers to work stations. Task processing times are worker specific, and workers might even be incompatible with certain tasks. The ALWABP was introduced to model assembly lines typical for sheltered work centers for the Disabled. In this paper we introduce an algorithm based on beam search for solving the ALWABP with the objective of minimizing the cycle time when given a fixed number of work stations, respectively, workers. This problem version is denoted as ALWABP-2. The experimental results show that our algorithm is currently a state-of-the-art method for the ALWABP-2. In comparison to results from the literature, our algorithm obtains better or equal results in all cases. Moreover, the algorithm is very robust for what concerns the application to problem instances of different characteristics. © 2010 Elsevier Ltd. All rights reserved. Source

Capmany J.,Polytechnic University of Valencia | Li G.,University of Central Florida | Lim C.,University of Melbourne | Yao J.,University of Ottawa
Optics Express | Year: 2013

Microwave Photonics, a symbiotic field of research that brings together the worlds of optics and radio frequency is currently facing several challenges in its transition from a niche to a truly widespread technology essential to support the ever-increasing values for speed, bandwidth, processing capability and dynamic range that will be required in next generation hybrid access networks. We outline these challenges, which are the subject of the contributions to this focus issue. © 2013 Optical Society of America. Source

Decker H.,Polytechnic University of Valencia
Proceedings - 21st International Workshop on Database and Expert Systems Applications, DEXA 2010 | Year: 2010

Methods for query evaluation usually differ from methods for integrity checking, and even more so if they are flexible enough to cope with extant inconsistencies. A recently developed cause-based approach provides a uniform foundation of inconsistency tolerance for query answering and integrity checking. It also provides flexibility to handle different degrees of inconsistency. We improve the cause-based approach by focusing on causes that are basic, i.e., irreducible to other causes. © 2010 IEEE. Source

The laminar boundary layer flow induced in a quiescent visco-elastic fluid by a permeable stretched flat surface with non-linearly (quadratic) velocity and appropriate wall transpiration under the influence of a magnetic field is investigated. It is shown that the problem permits a complete analytic exponentially decaying solution for the set of continuity and momentum equations with both magnetic field and visco-elasticity influences for two classes of visco-elastic fluid, namely, the second grade and Walters' liquid B fluids. The effects on both the skin friction parameter α and velocity profiles of various physical parameters such as visco-elasticity, suction/blowing parameter and magnetic parameter are studied. The results for the velocity field are presented through graphs and discussed in detail. © 2013 Springer Science+Business Media Dordrecht. Source

Moliner M.,Polytechnic University of Valencia
Topics in Catalysis | Year: 2015

Abstract A rationalized design of the organic structure directing agents (OSDAs) allows the preparation of zeolites with specific framework topologies, crystal sizes and/or chemical compositions. In the last years, organic molecules containing aromatic rings in their structures have been described as efficient OSDAs for the synthesis of zeolites with different physico-chemical properties. The unique ability of these aromatic molecules to form rigid and bulky OSDAs by supramolecular self-assembling of two organic molecules, mainly through π-π interactions, has allowed the synthesis of zeolites with large void volumes, controlled chemical distribution and/or high external surface areas. Along the present review, I would like to highlight the recent achievements reported in the literature using aromatic self-assembled bulky dimers as OSDAs for the synthesis of zeolites. © 2015 Springer Science+Business Media New York. Source

Juste B.,Polytechnic University of Valencia
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference | Year: 2011

An accurate knowledge of the spectral distribution emission is essential for precise dose calculations in radiotherapy treatment planning. Reconstruction of photon spectra emitted by medical accelerators from measured depth dose distributions in a water cube is an important tool for commissioning a Monte Carlo treatment planning system. However, the reconstruction problem is an inverse radiation transport function which is poorly conditioned and its solution may become unstable due to small perturbations in the input data. In this paper we present a more stable spectral reconstruction method which can be used to provide an independent confirmation of source models for a given machine without any prior knowledge of the spectral distribution. This technique involves measuring the depth dose curve in a water phantom and applying an unfolding method using Monte Carlo simulated depth dose gradient curves for consecutives mono-energetic beams. We illustrate this theory to calculate a 6 and a 15 MeV photon beam emitted from an Elekta Precise radiotherapy unit using the gradient of depth dose curves in a cube-shaped water tank. Source

Escorihuela J.,Polytechnic University of Valencia | Burguete M.I.,Jaume I University | Luis S.V.,Jaume I University
Chemical Society Reviews | Year: 2013

Achieving dual stereocontrol in asymmetric reactions using a single enantiomer for the building of the chiral catalyst or auxiliary is a very important goal in enantioselective synthesis as it eliminates the need for having available the two enantiomers of the auxiliary or catalyst designed. Recent strategies and advances towards this goal during the last four years will be discussed throughout this review. © 2013 The Royal Society of Chemistry. Source

Reyes A.,Instituto Superior Of Interpretes Y Traductores | Rosso P.,Polytechnic University of Valencia
Knowledge and Information Systems | Year: 2013

It is well known that irony is one of the most subtle devices used to, in a refined way and without a negation marker, deny what is literally said. As such, its automatic detection would represent valuable knowledge regarding tasks as diverse as sentiment analysis, information extraction, or decision making. The research described in this article is focused on identifying key values of components to represent underlying characteristics of this linguistic phenomenon. In the absence of a negation marker, we focus on representing the core of irony by means of three conceptual layers. These layers involve 8 different textual features. By representing four available data sets with these features, we try to find hints about how to deal with this unexplored task from a computational point of view. Our findings are assessed by human annotators in two strata: isolated sentences and entire documents. The results show how complex and subjective the task of automatically detecting irony could be. © 2013 Springer-Verlag London. Source

Dhakshinamoorthy A.,Madurai Kamaraj University | Opanasenko M.,J. Heyrovsky Institute of Physical Chemistry | Cejka J.,J. Heyrovsky Institute of Physical Chemistry | Garcia H.,Polytechnic University of Valencia
Catalysis Science and Technology | Year: 2013

This review focuses on the use of metal organic frameworks (MOFs) as catalysts for the synthesis of fine chemicals. While petrochemistry is characterized by gas phase reactions, in which MOFs cannot compete with robust zeolites, MOFs are better suited for liquid phase reactions performed at moderate temperatures. These are the conditions typically employed for the production of fine chemicals characterized by being more complex and diverse molecules of low volatility, but with high added value. For the preparation of this type of compound, MOFs offer the advantage of wide open porosity in the nanometer scale and a large void volume. In the present review we have summarized the reports that appeared up to early 2013 on the use of MOFs as catalysts in the liquid phase for the production of fine chemicals, primarily classified according to the type of active site and the functional group formed in the reaction. Prospects for future development in this field are provided in the last section. © 2013 The Royal Society of Chemistry. Source

Campos-Rodriguez F.,Hospital Universitario Of Valme | Martinez-Garcia M.A.,Polytechnic University of Valencia | Martinez-Garcia M.A.,CIBER ISCIII | Reyes-Nunez N.,Hospital Universitario Of Valme | And 3 more authors.
American Journal of Respiratory and Critical Care Medicine | Year: 2014

Rationale: It is unknown whether obstructive sleep apnea (OSA) may be a risk factor for incident cardiovascular events in women. Objectives: We sought to investigate whether OSA increases the incidence of a composite of stroke or coronary heart disease (CHD) in women, and the role of continuous positive airway pressure (CPAP) treatment on this association. Methods: This was a prospective, observational study conducted in two Spanish teaching hospitals between 1998 and 2007. Consecutive women referred for suspected OSA and free of previous stroke and CHD were analyzed. Women with an apnea - hypopnea index (AHI) less than 10 comprised the control group, and those with an AHI greater than or equal to 10 were diagnosed with OSA and classi fi ed as CPAP-treated (adherence ≥ 4 h/d) or untreated (adherence < 4 h/d or not prescribed). The follow-up ended in December 2010. Measurements and Main Results: A total of 967 women were studied (median follow-up, 6.8 yr; interquartile range, 5.2-8.2). The untreated OSA group showed a greater incidence rate of the composite outcome than the control group (2.19 vs. 0.54 per 100 person-years; P < 0.0005). Compared with the control group, the fully adjusted hazard ratios for the composite outcome incidence were 2.76 (95% confidence interval [CI], 1.35-5.62) for the untreated OSA group, and 0.91 (95% CI, 0.43-1.95) for the CPAP-treated group.Whenthe type of cardiovascular event was separately assessed, untreated OSA showed a stronger association with incident stroke (adjusted hazard ratio, 6.44; 95% CI, 1.46-28.3) than with CHD (adjusted hazard ratio, 1.77; 95% CI, 0.76-4.09). Conclusions: In women, untreatedOSAis associated with increased incidence of serious cardiovascular outcomes, particularly incident stroke. Adequate CPAP treatment seems to reduce this risk. Copyright © 2014 by the American Thoracic Society. Source

Morlanes N.,Polytechnic University of Valencia
International Journal of Hydrogen Energy | Year: 2013

To improve the understanding of the hydrocarbon steam reforming reaction mechanism and the nature of the active sites, different nickel-based catalysts have been synthesized and studied under several reaction conditions. Catalysts from hydrotalcite precursors show better activity and higher coking resistance than traditionally prepared samples. Furthermore, introducing additives (Ce, Li or Co) in the hydrotalcite structure produces no blockage of the nickel active sites. Different structural and physical-chemical properties have been analyzed by XRD, TPR, BET and elemental analysis. FTIR spectroscopy with CO adsorption reveals interesting catalyst structure-catalytic behavior relationships; oxygen release through the catalyst surface is key parameter to improve steam reforming activity and coking resistance; and, highly unsaturated Ni surface atoms located on the metal-support interphase are relevant structures to the catalysis and most active sites for the steam reforming reaction. Steam reforming reaction proposed sequence involves: 1) hydrocarbon preferably activation on active Ni surface sites and steam preferred activation on basic support surface sites, 2) oxygen spill-over from the support to the metal phase, and 3) reaction between carbon and oxygen species occurring on the metal-support interphase.© 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. Source

Gomez-Barea A.,Polytechnic University of Valencia | Leckner B.,Chalmers University of Technology
Fuel | Year: 2013

A method is presented to predict the conversion of biomass in a fluidized bed gasifier. The model calculates the yields of CO, H2, CO 2, N2, H2O, CH4, tar (represented by one single lump), and char, from fuel properties, reactor geometry and some kinetic data. The equilibrium approach is taken as a frame for the gas-phase calculation, corrected by kinetic models to estimate the deviation of the conversion processes from equilibrium. The yields of char, methane, and other gas species are estimated using devola-tilization data from literature. The secondary conversion of methane and tar, as well as the approach to equilibrium of the water-gas-shift reaction, are taken into account by simple kinetic models. Char conversion is calculated accounting for chemical reaction, attrition and elutriation. The model is compared with measurements from a 100 kWth bubbling fluidized bed gasifier, operating with different gasification agents. A sensitivity analysis is conducted to establish the applicability of the model and to underline its advantages compared to existing quasi-equilibrium models. © 2012 Elsevier Ltd. All rights reserved. Source

Moghaddam B.F.,Islamic Azad University at Parand | Ruiz R.,Polytechnic University of Valencia | Sadjadi S.J.,Iran University of Science and Technology
Computers and Industrial Engineering | Year: 2012

The Vehicle Routing Problem (VRP) has been thoroughly studied in the last decades. However, the main focus has been on the deterministic version where customer demands are fixed and known in advance. Uncertainty in demand has not received enough consideration. When demands are uncertain, several problems arise in the VRP. For example, there might be unmet customers' demands, which eventually lead to profit loss. A reliable plan and set of routes, after solving the VRP, can significantly reduce the unmet demand costs, helping in obtaining customer satisfaction. This paper investigates a variant of an uncertain VRP in which the customers' demands are supposed to be uncertain with unknown distributions. An advanced Particle Swarm Optimization (PSO) algorithm has been proposed to solve such a VRP. A novel decoding scheme has also been developed to increase the PSO efficiency. Comprehensive computational experiments, along with comparisons with other existing algorithms, have been provided to validate the proposed algorithms. Source

Capilla C.,Polytechnic University of Valencia
WIT Transactions on Ecology and the Environment | Year: 2014

This paper presents the application of feed-forward multilayer perceptron networks and multiple regression models, to forecast hourly nitrogen dioxide levels 24 hours in advance. Input data are traffic and meteorological variables, and nitrogen dioxide hourly levels. The introduction of four periodic components (sine and cosine terms for the daily and weekly cycles), and nitrogen oxide hourly levels was analyzed in order to improve the prediction power. The data were measured for three years at two monitoring stations in Valencia (Spain). The model evaluation criteria were the mean absolute error, the root mean square error and the mean absolute percentage error. The multilayer perceptron networks performed better than the regression models in nonlinear relationships like that involving nitrogen oxides, meteorological and traffic variables. Comparisons of the multilayer perceptron-based models proved that the insertion of the four additional seasonal input variables improved the ability of obtaining more accurate predictions, which emphasizes the importance of taking into account the seasonal character of nitrogen dioxide. The advantages of neural networks were that they did not require very exhaustive information about air pollutants, reaction mechanisms, meteorological parameters or traffic flow, and that they had the ability of allowing nonlinear relationships between very different predictor variables in an urban environment. © 2014 WIT Press. Source

Puig-Asensio M.,Autonomous University of Barcelona | Peman J.,Polytechnic University of Valencia | Zaragoza R.,Hospital Universitario Dr Peset | Garnacho-Montero J.,Hospital Universitario Virgen Del Rocio | And 3 more authors.
Critical Care Medicine | Year: 2014

OBJECTIVES: To determine the epidemiology of Candida bloodstream infections, variables influencing mortality, and antifungal resistance rates in ICUs in Spain. DESIGN: Prospective, observational, multicenter population-based study. SETTING: Medical and surgical ICUs in 29 hospitals distributed throughout five metropolitan areas of Spain. PATIENTS: Adult patients (≥ 18 yr) with an episode of Candida bloodstream infection during admission to any surveillance area ICU from May 2010 to April 2011. INTERVENTIONS: Candida isolates were sent to a reference laboratory for species identification by DNA sequencing and susceptibility testing using the methods and breakpoint criteria promulgated by the European Committee on Antimicrobial Susceptibility Testing. Prognostic factors associated with early (0-7 d) and late (8-30 d) mortality were analyzed using logistic regression modeling. MEASUREMENTS AND MAIN RESULTS: We detected 773 cases of candidemia, 752 of which were included in the overall cohort. Among these, 168 (22.3%) occurred in adult ICU patients. The rank order of Candida isolates was as follows: Candida albicans (52%), Candida parapsilosis (23.7%), Candida glabrata (12.7%), Candida tropicalis (5.8%), Candida krusei (4%), and others (1.8%). Overall susceptibility to fluconazole was 79.2%. Cumulative mortality at 7 and 30 days after the first episode of candidemia was 16.5% and 47%, respectively. Multivariate analysis showed that early appropriate antifungal treatment and catheter removal (odds ratio, 0.27; 95% CI, 0.08-0.91), Acute Physiology and Chronic Health Evaluation II score (odds ratio, 1.11; 95% CI, 1.04-1.19), and abdominal source (odds ratio, 8.15; 95% CI, 1.75-37.93) were independently associated with early mortality. Determinants of late mortality were age (odds ratio, 1.04; 95% CI, 1.01-1.07), intubation (odds ratio, 7.24; 95% CI, 2.24-23.40), renal replacement therapy (odds ratio, 6.12; 95% CI, 2.24-16.73), and primary source (odds ratio, 2.51; 95% CI, 1.06-5.95). CONCLUSIONS: Candidemia in ICU patients is caused by non-albicans species in 48% of cases, C. parapsilosis being the most common among these. Overall mortality remains high and mainly related with host factors. Prompt adequate antifungal treatment and catheter removal could be critical to decrease early mortality. © 2014 by the Society of Critical Care Medicine and Lippincott Williams & Wilkins. Source

Perez-Aparicio J.L.,Polytechnic University of Valencia | Ripoll L.,University of Girona
Composite Structures | Year: 2011

An integrated general formulation for the analysis and design of flywheel rotors made out of composite material is developed. To have an accurate estimation of stresses in the rotor, all the effects present in the literature and some new ones have been included: axial length (disks vs. cylinders), acceleration (sudden energy releases), hub stiffness and mass (attachment), non-uniform curing (different temperature inside, outside rotor) and moisture absorption (transient, permanent). Through pertinent transformations, these effects are described by a single differential equation that can be directly integrated, giving closed-form expressions for displacements, stresses and failure factors. The new formulation is applied to the study of a standard rotor of the type commonly analyzed in the literature, uni- and multilayer, made out of glass and carbon fiber/epoxy materials. The results are compared with those corresponding to each of the effects, drawing conclusions and design recommendations. © 2010. Source

Pullini D.,Centro Ricerche Fiat | Busquets-Mataix D.,Polytechnic University of Valencia
ACS Applied Materials and Interfaces | Year: 2011

Co/Cu-multilayer nanowires can be exploited to develop magnetoresistive sensors. One of the easiest methods for their production is filling nanoporous templates by pulsed-electrodeposition (PED) from a single bath. Multiple parameters effecting the growth of these nano-objects must be controlled to tailor their properties. In this study, the deposition efficiency of Co/Cu-multilayer nanowires produced in nanoporous-polymeric membranes is assessed, and the influence of the space confinement produced by the nanopores themselves on the continuous and pulsed-electrodeposition is evaluated. The growth dependence on some of the most significant process parameters has been investigated. It is shown here that, for each species, when depositing Co and Cu separately, a decrease of current efficiency is observed when the charge density is increased and the pore diameter is reduced; on the contrary, in the Co/Cu-PED, changing the degree of polarization for each deposition step of the different metals results in a sensible reduction of this effect. © 2011 American Chemical Society. Source

Orduna-Malea E.,Polytechnic University of Valencia | Regazzi J.J.,Long Island University
Scientometrics | Year: 2014

The main goal of this research is to analyze the web structure and performance of units and services belonging to U.S. academic libraries in order to check their suitability for webometric studies. Our objectives include studying their possible correlation with economic data and assessing their use for complementary evaluation purposes. We conducted a survey of library homepages, institutional repositories, digital collections, and online catalogs (a total of 374 URLs) belonging to the 100 U.S. universities with the highest total expenditures in academic libraries according to data provided by the National Center for Education Statistics. Several data points were taken and analyzed, including web variables (page count, external links, and visits) and economic variables (total expenditures, expenditures on printed and electronic books, and physical visits). The results indicate that the variety of URL syntaxes is wide, diverse and complex, which produces a misrepresentation of academic libraries' web resources and reduces the accuracy of web analysis. On the other hand, institutional and web data indicators are not highly correlated. Better results are obtained by correlating total library expenditures with URL mentions measured by Google (r = 0.546) and visits measured by Compete (r = 0.573), respectively. Because correlation values obtained are not highly significant, we estimate such correlations will increase if users can avoid linkage problems (due to the complexity of URLs) and gain direct access to log files (for more accurate data about visits). © 2013 Akadémiai Kiadó, Budapest, Hungary. Source

Gasulla I.,Stanford University | Capmany J.,Polytechnic University of Valencia
IEEE Photonics Journal | Year: 2012

This is the first time, to our knowledge, that the application of multicore fibers (MCFs) to the field of microwave photonics (MWP) has been proposed. The implementation of sampled optical delay lines for RF signals by means of heterogeneous MCFs is addressed as a generic building block and discussion is then centered on several selected applications including filtering, optical beamforming, and arbitrary waveform generation. © 2012 IEEE. Source

Vorberger J.,University of Warwick | Donko Z.,Hungarian Academy of Sciences | Tkachenko I.M.,Polytechnic University of Valencia | Gericke D.O.,University of Warwick
Physical Review Letters | Year: 2012

The dynamics of the ion structure in warm dense matter is determined by molecular dynamics simulations using an effective ion-ion potential. This potential is obtained from abinitio simulations and has a strong short-range repulsion added to a screened Coulomb potential. Models based on static or dynamic local field corrections are found to be insufficient to describe the data. An extended Mermin approach, a hydrodynamic model, and the method of moments with local constraints are capable of reproducing the numerical results but have rather limited predictive powers as they all need some numerical data as input. The method of moments is found to be the most promising. © 2012 American Physical Society. Source

Gomez-Chacon J.,Polytechnic University of Valencia
Cirugía pediátrica : organo oficial de la Sociedad Española de Cirugía Pediátrica | Year: 2012

The aim of this paper is to describe and evaluate the benefits of epidural anesthesia in major surgery neonatal. We have performed a matched case-control (2:1) study of patients undergoing neonatal major surgery (NMSs) who received intra-and postoperative epidural anesthesia (EA) and controls with conventional general anesthesia. The matching criteria were age, weight and baseline pathology. EA was administered by caudal puncture and epidural catheter placed with ultrasound support. Levobupivacaine was selected as anesthetic drug. The time to extubation, intestinal transit time, type of analgesia and complications were studied. This study is based on 11 cases (2 esophageal atresia, 2 diaphragmatic hernias, 1 necrotizing enterocolitis, 3 intestinal atresia, 2 anorectal malformation and 1 bladder exstrophy) and 22 controls. We observed statistically significant differences in time to extubation (95% CI OR 12 1.99 to 72.35; Chi2 p = 0.004, Mann U Whytney p = 0.013) and intestinal transit time (Mann Whitney U p < 0.001, 100 Or, 95% CI 8.06-1 239; Chi2 p < 0.0001). There were no complications from epidural analgesia. Therefore we believe that the intra-and postoperative EA helps improve postoperative management in neonates and should be preferred in centers where this technique is available. Source

Marti-Vargas J.R.,Polytechnic University of Valencia
Journal of Composites for Construction | Year: 2015

Unreinforced masonry (URM) structures that are in need of repair and rehabilitation constitute a significant portion of building stock worldwide. The successful application of fiber-reinforced polymers (FRP) for repair and retrofitting of reinforced-concrete (RC) structures has opened new avenues for strengthening URM structures with FRP materials. The present study analyzes the behavior of FRPconfined masonry prisms under monotonic axial compression. Masonry comprising of burnt clay bricks and cement-sand mortar (generally adopted in the Indian subcontinent) having Eb=Em ratio less than one is employed in the study. The parameters considered in the study are, (1) masonry bonding pattern, (2) inclination of loading axis to the bed joint, (3) type of FRP (carbon FRP or glass FRP), and (4) grade of FRP fabric. The performance of FRP-confined masonry prisms is compared with unconfined masonry prisms in terms of compressive strength, modulus of elasticity and stress-strain response. The results showed an enhancement in compressive strength, modulus of elasticity, strain at peak stress, and ultimate strain for FRP-confined masonry prisms. The FRP confinement of masonry resulted in reducing the influence of the inclination of the loading axis to the bed joint on the compressive strength and failure pattern. Various analytical models available in the literature for the prediction of compressive strength of FRP-confined masonry are assessed. New coefficients are generated for the analytical model by appending experimental results of the current study with data available in the literature. Source

Piqueras-Fiszman B.,Polytechnic University of Valencia | Piqueras-Fiszman B.,University of Oxford | Spence C.,University of Oxford
Appetite | Year: 2011

We report a study designed to investigate consumers' crossmodal associations between the color of packaging and flavor varieties in crisps (potato chips). This product category was chosen because of the long-established but conflicting color-flavor conventions that exist for the salt and vinegar and cheese and onion flavor varieties in the UK. The use of both implicit and explicit measures of this crossmodal association revealed that consumers responded more slowly, and made more errors, when they had to pair the color and flavor that they implicitly thought of as being "incongruent" with the same response key. Furthermore, clustering consumers by the brand that they normally purchased revealed that the main reason why this pattern of results was observed could be their differing acquaintance with one brand versus another. In addition, when participants tried the two types of crisps from "congruently" and "incongruently" colored packets, some were unable to guess the flavor correctly in the latter case. These strong crossmodal associations did not have a significant effect on participants' hedonic appraisal of the crisps, but did arouse confusion. These results are relevant in terms of R&D, since ascertaining the appropriate color of the packaging across flavor varieties ought normally to help achieve immediate product recognition and consumer satisfaction. © 2011 Elsevier Ltd. Source

Piqueras-Fiszman B.,Polytechnic University of Valencia | Piqueras-Fiszman B.,University of Oxford | Spence C.,University of Oxford
Appetite | Year: 2012

We report a study designed to investigate the influence of the weight of the container on expected satiety prior to tasting the food within and on the perceived density of the food and any feelings of fullness expected to follow consumption (expected satiation). The results demonstrate that the contents of a heavier container are expected to be more satiating than when exactly the same contents are presented in a visually-identical, but physically lighter, container (even before the food has been tasted). In addition, we were able to validate a " weight-density" illusion, since the weight of the container was shown to influence the perceived density of the sample. Put simply, the heavier the container, the denser the food sample was perceived to be. © 2012 Elsevier Ltd. Source

Vidal G.,Polytechnic University of Valencia
Proceedings - 2012 IEEE 12th International Working Conference on Source Code Analysis and Manipulation, SCAM 2012 | Year: 2012

Symbolic execution, originally introduced as a method for program testing and debugging, is usually incomplete because of infinite symbolic execution paths. In this work, we adapt some well-known notions from partial evaluation in order to have a complete symbolic execution scheme which can then be used to check liveness properties like program termination. We also introduce a representation of the symbolic transitions as a term rewrite system so that existing termination provers for these systems can be used to verify the termination of the original program. © 2012 IEEE. Source

Gomez-Barquero D.,Polytechnic University of Valencia | Simeone O.,New Jersey Institute of Technology
IEEE Transactions on Broadcasting | Year: 2015

In this paper, power-based layer-division multiplexing (LDM) is studied as a means to provide unequal error protection in digital terrestrial television (DTT) systems by adopting an information-theoretic approach. LDM can potentially offer fundamental performance gains as compared to traditional time-division multiplexing (TDM) or frequency-division multiplexing due to the reuse by all information layers of all the available time-frequency resources. The main use case of LDM for terrestrial broadcasting is the simultaneous provision of fixed and mobile services in the same channel. Since most DTT networks worldwide are dimensioned for fixed rooftop reception, this paper illustrates the performance comparison between LDM and F/TDM in terms of the capacity-coverage tradeoff of the mobile service for a given reduction of the capacity of the fixed service while keeping the coverage of the fixed service constant. A mathematical formulation, and corresponding numerical results, are provided for different fading channels, including single-input single-output, single-input multiple-output, multiple-input single-output, and multiple-input multiple-output antenna systems, and accounting also for the impact of non-ideal channel coding. © 2015 IEEE. Source

Martin B.R.,University of Sussex | Martin B.R.,University of Cambridge | Nightingale P.,University of Sussex | Yegros-Yegros A.,Polytechnic University of Valencia
Research Policy | Year: 2012

Science and Technology Studies (STS) is one of a number of new research fields to emerge over the last four or five decades. This paper attempts to identify its core academic contributions from the perspective of the authors of chapters in authoritative 'handbooks' and the references they cite. Besides identifying the most prominent publications, institutions and authors, we examine whether the core contributions can be broken down into identifiable clusters. The study also analyses the impact of these contributions by exploring the research fields, journals, and geographical location of the researchers that have cited the STS core contributions in their own work. Together, these analyses reveal a number of phases in the development of STS with periods of convergence and divergence of the field, including the gradual separation of quantitative studies of science and technology from the main body of STS. The paper ends with some conclusions about the evolution of STS, such as the role of 'institution builders' in developing new research fields and the structures required to hold them together. © 2012 Elsevier B.V. Source

Mascardi V.,University of Genoa | Locoro A.,University of Genoa | Rosso P.,Polytechnic University of Valencia
IEEE Transactions on Knowledge and Data Engineering | Year: 2010

Ontology matching is the process of finding correspondences between entities belonging to different ontologies. This paper describes a set of algorithms that exploit upper ontologies as semantic bridges in the ontology matching process and presents a systematic analysis of the relationships among features of matched ontologies (number of simple and composite concepts, stems, concepts at the top level, common English suffixes and prefixes, and ontology depth), matching algorithms, used upper ontologies, and experiment results. This analysis allowed us to state under which circumstances the exploitation of upper ontologies gives significant advantages with respect to traditional approaches that do no use them. We run experiments with SUMO-OWL (a restricted version of SUMO), OpenCyc, and DOLCE. The experiments demonstrate that when our structural matching method via upper ontology uses an upper ontology large enough (OpenCyc, SUMO-OWL), the recall is significantly improved while preserving the precision obtained without upper ontologies. Instead, our nonstructural matching method via OpenCyc and SUMO-OWL improves the precision and maintains the recall. The mixed method that combines the results of structural alignment without using upper ontologies and structural alignment via upper ontologies improves the recall and maintains the F-measure independently of the used upper ontology. © 2006 IEEE. Source

Leon J.,Polytechnic University of Valencia
Sub-cellular biochemistry | Year: 2013

Jasmonates are a family of oxylipins derived from linolenic acid that control plant responses to biotic and abiotic stress factors and also regulate plant growth and development. Jasmonic acid (JA) is synthesized through the octadecanoid pathway that involves the translocation of lipid intermediates from the chloroplast membranes to the cytoplasm and later on into peroxisomes. The peroxisomal steps of the pathway involve the reduction of cis-(+)-12-oxophytodienoic acid (12-OPDA) and dinor-OPDA, which are the final products of the choroplastic phase of the biosynthetic pathway acting on 18:3 and 16:3 fatty acids, respectively. Further shortening of the carbon side-chain by successive rounds of β-oxidation reactions are required to complete JA biosynthesis. After peroxisomal reactions are completed, (+)-7-iso-JA is synthesized and then transported to the cytoplasm where is conjugated to the amino acid isoleucine to form the bioactive form of the hormone (+)-7-iso-JA-Ile (JA-Ile). Further regulatory activity of JA-Ile triggering gene activation in the jasmonate-dependent signaling cascades is exerted through a process mediated by the perception via the E3 ubiquitin ligase COI1 and further ligand-activated interaction with the family of JAZ repressor proteins. Upon interaction, JAZ are ubiquitinated and degraded by the proteasome, thus releasing transcription factors such as MYC2 from repression and allowing the activation of JA-responsive genes. Source

Ferriz-Manas M.,Florida State University | Ferriz-Manas M.,Polytechnic University of Valencia | Schlenoff J.B.,Florida State University
Langmuir | Year: 2014

Zeta potentials of surfaces bearing stable mono- or multilayers of polyelectrolyte were determined using the spinning disk method recently described by Sides et al. (Langmuir 2004, 20, 11493-11498). In this technique, the streaming potential difference between two electrodes, one at the disk surface, is quantitatively related to zeta potential. Variables such as rotation speed, electrolyte concentration, and electrode distance from the disk surface were explored and used to validate the recently-described theory, which emphasizes minimal contribution to net potential from surface conductivity. Layer-by-layer oscillations in sign and magnitude of the zeta potential were observed, in accord with prior work using electrophoretic mobility of multilayer-coated particles and other streaming potential measurements. The open geometry and the excellent mass transport of the spinning disk allowed in-situ observation of surface charge switching during the addition of a layer. As with all zeta potentials, especially those recorded at soft interfaces, translating results to quantitative densities of fixed surface charge is a challenge. © 2014 American Chemical Society. Source

Hernandez-Orallo J.,Polytechnic University of Valencia
Autonomous Agents and Multi-Agent Systems | Year: 2015

This paper presents a way to estimate the difficulty and discriminating power of any task instance. We focus on a very general setting for tasks: interactive (possibly multi-agent) environments where an agent acts upon observations and rewards. Instead of analysing the complexity of the environment, the state space or the actions that are performed by the agent, we analyse the performance of a population of agent policies against the task, leading to a distribution that is examined in terms of policy complexity. This distribution is then sliced by the algorithmic complexity of the policy and analysed through several diagrams and indicators. The notion of environment response curve is also introduced, by inverting the performance results into an ability scale. We apply all these concepts, diagrams and indicators to two illustrative problems: a class of agent-populated elementary cellular automata, showing how the difficulty and discriminating power may vary for several environments, and a multi-agent system, where agents can become predators or preys, and may need to coordinate. Finally, we discuss how these tools can be applied to characterise (interactive) tasks and (multi-agent) environments. These characterisations can then be used to get more insight about agent performance and to facilitate the development of adaptive tests for the evaluation of agent abilities. © 2014, The Author(s). Source

This article collects various options for sustainable reuse of waste in the manufacture of concrete. It details the various options for industrial waste, agricultural waste and construction and demolition waste. The importance of treatments such as milling, air classification and sonication, and preparation of binders in the manufacture of alkali activated systems is emphasized. Source

Acedo L.,Polytechnic University of Valencia
Advances in Space Research | Year: 2013

In the last decade a major debate has emerged on the astrophysics community concerning the anomalous behavior of the astronomical unit, the fundamental scale of distances in the Solar system. Several independent studies have combined radar ranging and optical data from the last four decades to come to the conclusion that the astronomical unit is increasing by several meters per century. It is abundantly clear that General Relativity cannot account for this new effect, although an still undefined angular momentum transfer mechanism could provide the simpler and more conventional explanation. Here we investigate several anomalous post-Newtonian terms containing only the product of the mass and angular momentum of the Sun as well as its Schwarzschild radius in order to determine if they could explain the secular increase of the astronomical unit and the recently reported increase of Lunar's eccentricity. If these anomalies are confirmed, searching for a modification of General Relativity predicting these terms could have far-reaching consequences. © 2013 COSPAR. Published by Elsevier Ltd. All rights reserved. Source

Azagra-Caro J.M.,Polytechnic University of Valencia
Science and Public Policy | Year: 2011

Technology ownership and knowledge transfer aim at the dissemination of public research results, usually in one direction - from the university or public research organisation (PRO) that produced the results. However, the complementarities between these types of instruments are not clear compared to the bidirectional channels of knowledge exchange. We analyse one PRO in Spain, a country that is peculiar in terms of infrequent changes to the legislation on science and patents and a predominance of PRO-owned over PRO-invented patents, similar to the situation in the USA but different from that in most EU member states. Against this background, knowledge transfer (measured through PROinvented patents) increases faster than technology ownership (measured through PRO-owned patents). This situation may be damaging to knowledge exchange (measured through PRO co-owned patents). © Beech Tree Publishing 2011. Source

Rasero-Almansa A.M.,CSIC - Institute of Materials Science | Corma A.,Polytechnic University of Valencia | Iglesias M.,CSIC - Institute of Materials Science | Sanchez F.,Institute Quimica Organica General
ChemCatChem | Year: 2013

We describe the postsynthetic modification of Zr-based metal organic frameworks (MOFs) containing chiral NNN-pincer ligands based on aminopyridineimines, as well as the subsequent formation of (NNN)-M-Zr-MOF complexes (M=Rh, Ir). With these new multifunctional materials, we performed a cascade of condensation reactions followed by hydrogenation of the resulting double bond. If the condensation reaction occurs between an aldehyde and ethyl nitroacetate, (NNN)-M-Zr-MOF complexes catalyze the one-pot synthesis of nitroalkenes, in which ZrIV Lewis sites play a role similar to that of the generally used TiIV in homogeneous catalysis. These multifunctional hybrid catalysts retain their crystalline framework even after the reaction, and they were isolated easily from the reaction mixture through filtration and reused several times without a significant degradation in activity. Moreover, there was no contribution from leached active species and conversion was possible only in the presence of the solid catalyst. Preparation wins half the battle: Multifunctional catalysts based on Zr-based metal organic frameworks containing guest-accessible NNN-pincer groups have been prepared. The combination of acid, basic, and hydrogenation active sites leads to a hybrid material that behaves as a multifunctional Zr-base-transition metal catalyst for one-pot cascade condensation-hydrogenation reactions. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Marti-Vargas J.R.,Polytechnic University of Valencia
Journal of Computing in Civil Engineering | Year: 2015

Researchers discuss the role of geometric design optimization for dynamic response problems of continuous reinforced concrete beams. They have published a paper, which develops a heuristic computer-aided design methodology for conceptual geometric layout optimization of multispan reinforced concrete (RC) beams under any type of dynamic conditions. The proposed method employees an ant colony optimization algorithm, takes the involved cost parameters into account, and can be used for different boundary conditions, support constraints, and loading systems. The performance and robustness of the approach is verified by solving the structural optimization problem for some design examples. Source

Paya-Zaforteza I.,Polytechnic University of Valencia | Garlock M.E.M.,Princeton University
Journal of Constructional Steel Research | Year: 2012

The response of bridges subject to fire is an under researched topic despite the number of bridge failures caused by fire. Since available data shows that steel girder bridges are especially vulnerable to fire, this paper delves into their fire response by analyzing with a 3D numerical model the response of a typical bridge of 12.20 m span length. A parametric study is performed considering: (1) two possibilities for the axial restraint of the bridge deck, (2) four types of structural steel for the girders (carbon steel and stainless steel grades 1.4301, 1.4401, and 1.4462), (3) three different constitutive models for carbon steel, (4) four live loads, and (5) two alternative fire loads (the hydrocarbon fire defined by Eurocode 1 and a fire corresponding to a real fire event). Results show that restraint to deck expansion coming from an adjacent span or abutment should be considered in the numerical model. In addition, times to collapse are very small when the bridge girders are built with carbon steel (between 8.5 and 18 min) but they can almost double if stainless steel is used for the girders. Therefore, stainless steel is a material to consider for steel girder bridges in a high fire risk situation, especially if the bridge is located in a corrosive environment and its aesthetics deserves special attention. The methodology developed in this paper and the results obtained are useful for researchers and practitioners interested in developing and applying a performance-based approach for the design of bridges against fire. © 2012 Elsevier Ltd. All rights reserved. Source

Cagnina L.,National University of San Luis | Errecalde M.,National University of San Luis | Ingaramo D.,National University of San Luis | Rosso P.,Polytechnic University of Valencia
Information Sciences | Year: 2014

Short texts such as evaluations of commercial products, news, FAQ's and scientific abstracts are important resources on the Web due to the constant requirements of people to use this on line information in real life. In this context, the clustering of short texts is a significant analysis task and a discrete Particle Swarm Optimization (PSO) algorithm named CLUDIPSO has recently shown a promising performance in this type of problems. CLUDIPSO obtained high quality results with small corpora although, with larger corpora, a significant deterioration of performance was observed. This article presents CLUDIPSO *, an improved version of CLUDIPSO, which includes a different representation of particles, a more efficient evaluation of the function to be optimized and some modifications in the mutation operator. Experimental results with corpora containing scientific abstracts, news and short legal documents obtained from the Web, show that CLUDIPSO* is an effective clustering method for short-text corpora of small and medium size. © 2013 Elsevier Inc. All rights reserved. Source

Tirado P.,Polytechnic University of Valencia
Iranian Journal of Fuzzy Systems | Year: 2012

In [Fuzzy Sets and Systems 27 (1988) 385-389], M. Grabiec introduced a notion of completeness for fuzzy metric spaces (in the sense of Kramosil and Michalek) that successfully used to obtain a fuzzy version of Banach's contraction principle. According to the classical case, one can expect that a compact fuzzy metric space be complete in Grabiec's sense. We show here that this is not the case, for which we present an example of a compact fuzzy metric space that is not complete in Grabiec's sense. On the other hand, Grabiec used a notion of compactness to obtain a fuzzy version of Edelstein's contraction principle. We present here a generalized version of Grabiec's version of the Edelstein fixed point theorem and different interesting facts on the topology of fuzzy metric spaces. Source

Silva J.,Polytechnic University of Valencia
ACM Computing Surveys | Year: 2012

This article surveys previous work on program slicing-based techniques. For each technique, we describe its features, its main applications, and a common example of slicing using such a technique. After discussing each technique separately, all of them are compared in order to clarify and establish the relations between them. This comparison gives rise to a classification of techniques which can help to guide future research directions in this field. © 2012 ACM. Source

Almenar P.,Vodafone | Jodar L.,Polytechnic University of Valencia
Computers and Mathematics with Applications | Year: 2012

This paper presents an upper bound for the distance between a zero and a critical point of a solution of the second order linear differential equation (p(x)y′)′ +q(x)y(x)=0, with p(x),q(x)>0. It also compares it with previous results. © 2011 Elsevier Ltd. All rights reserved. Source

Corma A.,Polytechnic University of Valencia
Chemistry - A European Journal | Year: 2012

The triflimide iron(III) salt [Fe(NTf 2) 3] promotes the direct hydration of terminal and internal alkynes with very good Markovnikov regioselectivities and high yields. The enhanced carbophilic Lewis acidity of the Fe III cation mediated by the weakly-coordinating triflimide anion is crucial for the catalytic activity. The iron(III) metal salt can be recycled in the form of the OPPh 3/[Fe(NTf 2) 3] system with similar activity and selectivity. However, spectroscopic and kinetic studies show that [Fe(NTf 2) 3] hydrolyzes under the reaction conditions and that catalytically less active BrAønsted species are formed, which points to a Lewis/Brønsted co-catalysis. This triflimide-based catalytic system is regioselective for the hydration of internal aryl-alkynes and opens the door to a new synthetic route to alkyl ketophenones. As a proof of concept, the synthesis of two antipsychotics Haloperidol and Melperone, with general butyrophenone-like structure, is shown. Just add water! The triflimide iron(III) salt [Fe(NTf 2) 3] promotes the direct hydration of terminal and internal alkynes with very good Markovnikov regioselectivities and high yields (see scheme). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Collado-Ruiz D.,Polytechnic University of Valencia | Ostad-Ahmad-Ghorabi H.,Vienna University of Technology
Resources, Conservation and Recycling | Year: 2010

In order for products to be comparable in different life cycle assessments, functional units need to be defined. Nevertheless, their definitions tend to be simplified or ambiguous. There is thus a need to standardize these functional units, to be properly used for environmental comparison of the environmental performance of products. This paper introduces a systematic approach to define standardized functional units: the concept of fuons. Fuons are defined as an abstraction of a product, based on its essential function and representing the whole set of products that share the parameters for this function's flows. The use of fuons, and by these means the correct definition of the functional unit, should then help to retrieve a suitable product family for life cycle comparison, hence a set of products whose LCA shares a common behavior. This will allow comparing the environmental performance of a new product in development with the products in that family. © 2010 Elsevier B.V. All rights reserved. Source

Lazaro M.,Polytechnic University of Valencia
Journal of Sound and Vibration | Year: 2016

The viscous damping model has been widely used to represent dissipative forces in structures under mechanical vibrations. In multiple degree of freedom systems, such behavior is mathematically modeled by a damping matrix, which in general presents non-proportionality, that is, it does not become diagonal in the modal space of the undamped problem. Eigensolutions of non-proportional systems are usually estimated assuming that the modal damping matrix is diagonally dominant (neglecting the off-diagonal terms) or, in the general case, using the state-space approach. In this paper, a new closed-form expression for the complex eigenvalues of non-proportionally damped system is proposed. The approach is derived assuming small damping and involves not only the diagonal terms of the modal damping matrix, but also the off-diagonal terms, which appear under higher order. The validity of the proposed approach is illustrated through a numerical example. © 2015 Elsevier Ltd. All rights reserved. Source

Garcia-Diaz J.C.,Polytechnic University of Valencia
Stochastic Environmental Research and Risk Assessment | Year: 2011

Contaminated water resources have important implications on health and the environment. Nitrate contamination of the groundwater is a serious problem in the European Union. A method based on the statistical process control (SPC) and time series analysis is developed to monitoring and to predict the concentration evolution of nitrate (NO 3 -) in groundwater. In many pumping wells the NO 3 -concentration ([NO 3 -]) increases and approaches or even passes the European Community standard of 50 mg l -1. The objective of this paper is to show the application of statistical process control as a monitoring tool for groundwater pollution from agricultural practices. We propose the autoregressive integrated moving average (ARIMA) model as a management tool to monitoring and reduction of the intrusion of nitrate into the groundwater. This tool should help in setting up useful guidelines for evaluating actual environmental performance against the firm's environmental objectives and targets and regulatory requirements. We concluded that the statistical process control method may be a potentially important way of monitoring groundwater quality that also permits rapid response to serious increases in pollutants concentrations. In doing so, the paper fills an important gap in the water pollution standards and emerging polices (Water Framework directives). © 2010 Springer-Verlag. Source

Wideberg J.,Polytechnic University of Valencia
International Journal of Heavy Vehicle Systems | Year: 2013

Dynamic stability is crucial for vehicle safety, not least for heavy commercial vehicle safety. An articulated vehicle such as a tractor-semitrailer may if not correctly designed, handled or rebuilt fall into instability when driving. This is affected by several factors of which the geometric location of the fifth wheel is one. The effect on stability of the fifth wheel location along the longitudinal axis is therefore analysed using a simplified model and a more detailed MBS model. Results indicate that the tractor-semitrailer becomes unstable if the fifth wheel is located in a too far rearward position. Copyright © 2013 Inderscience Enterprises Ltd. Source

Vennestrom P.N.R.,Research and Development Division | Vennestrom P.N.R.,Polytechnic University of Valencia | Osmundsen C.M.,Research and Development Division | Osmundsen C.M.,Technical University of Denmark | And 2 more authors.
Angewandte Chemie - International Edition | Year: 2011

From petroleum to bioleum: Since biomass is a limited resource, it is necessary to consider its best use. The production of select chemicals from biomass, rather than its use as fuel, could effectively replace the use of petroleum in the chemical industry, but the inherent functionality of biomass must be exploited (see picture). Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Balaguer-Beser A.,Polytechnic University of Valencia
International Journal for Numerical Methods in Engineering | Year: 2011

This paper presents a new point value reconstruction algorithm based on average values or flux values for central Runge-Kutta schemes in the resolution of hyperbolic conservation laws. This reconstruction employs a fourth-order accurate approximation of point values of the solution at the two extrema and at the mid-point of each cell. These point values are modified in order to enforce monotonicity and shape preserving properties. This correction has been applied essentially in the cells close to the maxima and minima of the solution and in these cases, it has been proven that the reconstruction is fourth-order accurate. In the cells with a maximum or minimum of the solution, a correction has also been applied to such point values with the aim of ensuring that the resulting numerical solution has a non-oscillatory behavior. Several standard one- and two-dimensional test cases are used to verify high-order accuracy, non-oscillatory behavior and high-resolution properties for smooth and discontinuous solutions, and also in their componentwise extension to the Euler gas dynamics equations. © 2011 John Wiley & Sons, Ltd. Source

Decker H.,Polytechnic University of Valencia
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2013

The lack of quality of stored data is reflected by violations of integrity constraints. Answers to queries in databases containing bad quality information usually cannot be trusted. Nevertheless, many answers given by such databases may still be useful, as long as they are derived from data the quality of which is sufficiently high. We formalize our intuition of answers that have quality on the basis of 'causes'. A cause of an answer is a minimal excerpt of the database that explains why the answer has been given. Thus, an answer has quality if the overlap of its causes with the causes of integrity violation is empty. Even if that overlap is not empty, but is sufficiently low, an answer may have sufficient quality. The amount of causes in the overlaps of causes of answers and integrity violations can be sized by quality metrics. © 2013 Springer-Verlag Berlin Heidelberg. Source

D'Este P.,Polytechnic University of Valencia | Iammarino S.,The London School of Economics and Political Science
Papers in Regional Science | Year: 2010

This paper focuses on one particular type of linkage between university and business - joint research partnerships - and addresses two specific issues. First, it investigates the extent to which research quality and geographical proximity bear an influence on the frequency of the collaborations between university departments and businesses. Second, it explores the factors affecting the geographical distance of university-business partnerships. Our findings show that both geographical proximity and research quality are positively associated with the frequency of university-industry partnerships; though, results are not homogenous across scientific disciplines. Our results also show that distance between university and business partners exhibit a curvilinear (inverted-U shape) relationship with the research excellence of university departments. © 2010 the author(s). Journal compilation © 2010 RSAI. Source

Alferez G.H.,University of Montemorelos | Pelechano V.,Polytechnic University of Valencia
Proceedings - 15th International Software Product Line Conference, SPLC 2011 | Year: 2011

Web services run in complex environments where it is desirable to be able to count on mechanisms to adapt them according to contextual changes. Manual adaptations are unfeasible in intricate service compositions that are built with highly dynamic Web services. However, the principles of Autonomic Computing could support their self-adaptation. In this paper, we propose a method for designing and implementing context-aware autonomous Web services in system families. It is based on Software Product Line (SPL) engineering to support their systematic reuse in mass production environments. Autonomic behavior is achieved by our Model-based Reconfiguration Engine for Web services (MoRE-WS). MoRE-WS leverages variability models at runtime as easy-to-understand and semantically rich adaptation policies for decision-making while the architecture of a Dynamic SPL (DSPL) allows a flexible service recomposition. A case study illustrates the applicability of our method. © 2011 IEEE. Source

Garcia E.,Polytechnic University of Valencia
Information Systems Development - Business Systems and Services: Modeling and Development | Year: 2011

Regulated Open multi-Agent systems are composed by heterogeneous and autonomous agents which may need to coexist in a complex social and legal frame work that can evolve to address the different and often conflicting objectives of the many stakeholders involved. Of the ways in which agent behaviour can be regulated in a multi-Agent system, contracts seem to be the most appropriate for industrial environments. This paper analyzes the open challenges in the development of these kind of systems. It also proposes an architecture and a designing method which face up to these challenges by means of the integration of open multi-Agent systems, service-oriented architectures, e-contracting and regulation enforcement mechanisms. © Springer Science+Business Media, LLC 2011. Source

Dhakshinamoorthy A.,Madurai Kamaraj University | Asiri A.M.,King Abdulaziz University | Garcia H.,Polytechnic University of Valencia | Garcia H.,King Abdulaziz University
Chemical Communications | Year: 2014

Metal-organic frameworks (MOFs) having a large surface area and porosity as well as a high density of transition metals are increasingly used as heterogeneous catalysts for organic reactions. However, one of the main limitations of various MOFs has been their lack of structural stability that led to an assumption that MOFs are unstable materials, particularly in water or polar solvents. However, since a few years ago the hydrothermal stability of several MOFs such as MIL-101(Cr), MIL-53(Al) and ZIF-8 has been demonstrated and, hence, they can be used as solid catalysts in the aqueous phase. The present review is aimed at showing that there are a sufficiently large number of reports proving that certain MOFs can be used as reusable catalysts in water as the solvent. The use of water as the solvent has considerable advantages from the environmental point of view and affordability. Water can be the solvent of choice for hydrolytic processes, but MOFs have been reported as catalysts in water even for esterifications and C-C couplings. Considering that the synthesis of new MOFs is an active area of research and the flexibility in the selection of transition metals and organic linkers, these materials can be prepared with the required hydrophilicity/hydrophobicity to adapt specifically for catalysis in aqueous phase. This journal is © the Partner Organisations 2014. Source

Peidro D.,Polytechnic University of Valencia | Vasant P.,Petronas University of Technology
Applied Soft Computing Journal | Year: 2011

In this paper, we consider the transportation planning decision (TPD) problem with fuzzy goals, available supply and forecast demand. An interactive method is designed for solving the multi-objective TPD problem where the fuzzy data are represented by modified S-curve membership functions. The proposed method attempts to simultaneously minimize the total production and transportation costs and the total delivery time with reference to budget constraints and available supply, machine capacities at each source, as well as forecast demand and warehouse space constraints at each destination. An interactive fuzzy approach is applied to solve the multi-objective TPD problem and to find a preferred compromise solution. Finally, the performance of S-curve membership functions that represent uncertainty goals and constraints in TPD problems with linear membership functions in an industrial case is compared. © 2010 Elsevier B.V. All rights reserved. Source

Decker H.,Polytechnic University of Valencia
Proceedings - International Conference on Data Engineering | Year: 2011

Database updates may need to tolerate extant integrity violations, but should not cause additional inconsistencies. Causes of constraint violations can be used to prevent an increase of inconsistency while tolerating extant inconsistencies. even if integrity constraints are altered. © 2011 IEEE. Source

Baselga S.,Polytechnic University of Valencia
Journal of Surveying Engineering | Year: 2014

Methods based on integer ambiguity determination, such as the least-squares ambiguity decorrelation adjustment (LAMBDA) method, are currently used for precise global navigation satellite system (GNSS) differential positioning. In the present paper, the author proposes an ambiguity-free method based on a dedicated mixed (stochastic/deterministic) optimization algorithm that, unlike the LAMBDA method, is capable of providing reliable and accurate results using few observation epochs (e.g., 1-cm accuracy with just two epochs), having the additional advantages of insensitivity to cycle slips and impossibility of wrong ambiguity fixation. In addition, it is demonstrated that the application of the linear (deterministic) part of this algorithm yields the correct baseline results much more easily and quickly than methods requiring integer ambiguity determination, provided the initial approximate coordinates are accurate to a few centimeters. However, the use of ambiguity-free methods requires that the integer character of the ambiguities be preserved so that they can be eliminated; therefore no ionosphere-free combination can be computed and the methods are valid only for short baselines (e.g., less than 10 km). © 2014 American Society of Civil Engineers. Source

Bartak R.,Charles University | Salido M.A.,Polytechnic University of Valencia
Constraints | Year: 2011

The areas of planning and scheduling (from the Artificial Intelligence point of view) have seen important advances thanks to application of constraint satisfaction techniques. Currently, many important real-world problems require efficient constraint handling for planning, scheduling and resource allocation to competing goal activities over time in the presence of complex state-dependent constraints. Solutions to these problems require integration of resource allocation and plan synthesis capabilities. Hence to manage such complex problems planning, scheduling and constraint satisfaction must be interrelated. This special issue on Constraint Satisfaction for Planning and Scheduling Problems compiles a selection of papers dealing with various aspects of applying constraint satisfaction techniques in planning and scheduling. The core of submitted papers was formed by the extended versions of papers presented at COPLAS'2009: ICAPS 2009 Workshop on Constraint Satisfaction Techniques for Planning and Scheduling Problems. This issue presents novel advances on planning, scheduling, constraint programming/constraint satisfaction problems (CSPs) and many other common areas that exist among them. On the whole, this issue mainly focus on managing complex problems where planning, scheduling, constraint satisfaction and search must be combined and/or interrelated, which entails an enormous potential for practical applications and future research. © 2011 Springer Science+Business Media, LLC. Source

Ruiz Garcia V.,Polytechnic University of Valencia
Cochrane database of systematic reviews (Online) | Year: 2011

TNF-alpha inhibitors have been shown to reduce the risk of joint damage and improve physical function and quality of life in people with rheumatoid arthritis (RA). This is the first Cochrane review of certolizumab pegol, a new TNF-alpha inhibitor. To assess the effectiveness and safety of certolizumab pegol (CDP870) in patients with RA who have not responded well to conventional disease modifying anti-rheumatic drugs (DMARDs). We searched the Cochrane Central Register of Controlled Trials (The Cochrane Library 2009, Issue 3),  MEDLINE (1966 to November 2009), EMBASE (1966 to November 2009), Scopus (January 2004 to November 2009), TOXLINE (until November 2009), Web of Knowledge (until November 2009); websites of the US Food and Drug Administration (FDA) and European Medicines Evaluation Agency (EMEA) (until November 2009), and reference lists of articles. Randomised controlled trials that compared certolizumab pegol with any other agent including placebo or methotrexate (MTX) in adult RA patients with active rheumatoid arthritis despite current or prior treatment with conventional DMARDs, such as methotrexate (MTX). Two authors independently assessed search results, trial quality and extracted data. Five trials were included. We included in the analysis 2394 people for effectiveness and 2094 people for safety. The duration of follow-up was from 12 to 52 weeks, and the range of doses of certolizumab pegol were from 50 to 400 mg subcutaneously (sc). In three trials the control was placebo plus methotrexate (MTX) and in two trials it was just placebo. Significant improvements were observed at 24 weeks with the approved dose of 200 mg certolizumab pegol: American College of Rheumatology (ACR) 50% improvement: risk ratio (RR) 6.01 (95% CI 3.84 to 9.40) with an absolute benefit of 29% (95% CI 25% to 34%), number needed to treat to benefit (NNTB) of 4 (3 to 5) and the Health Assessment Questionnaire (HAQ) mean difference (MD) - 0.39 (95% CI -0.45 to -0.32) (scale 0 to 3). At 52 weeks the results were quite similar: ACR 50% improvement RR 5.27 (95% CI 3.19 to 8.71), HAQ mean difference (MD) - 0.42 (95% CI -0.52 to -0.32). Serious adverse events were more frequent for certolizumab pegol 200 mg, Peto OR 2.02 (95% CI 1.24 to 3.30). The most common adverse events with certolizumab pegol 200 mg were: upper respiratory tract infections, Peto OR 2.21 (95% CI 1.15 to 4.25); hypertension, Peto OR 2.81 (95% CI 1.38 to 5.75); and nasopharyngitis, Peto OR 2.71 (95% CI 1.30 to 5.66). With an overall high grade of evidence this review revealed an improvement of clinical results (ACR50, 28 joint disease activity score (DAS-28) remission and HAQ scores) with certolizumab pegol. Adverse events were more frequent with certolizumab; there was a statistically significant increase in the number of serious adverse events, infections and hypertension. Source

Altamirano-Fortoul R.,Institute of Agrochemistry and Food Technology | Hernando I.,Polytechnic University of Valencia | Rosell C.M.,Institute of Agrochemistry and Food Technology
Journal of Texture Studies | Year: 2013

The effect of the puncturing settings (crosshead speed and punch cross-section) on the crust mechanical parameters was investigated using breads with two different crust thickness. Results showed that, greater punch cross-section was associated to compression behavior, which reduced the sensibility to detect changes in the crust structure. Moreover, low crosshead speed (0.5mm/s) puncture test provided information about the cellular structure of the crust. The relationship between the puncturing parameters and the water activity and moisture content together with the crust microstructure analysis revealed that for obtaining reliable information about the structural ruptures related to crispiness texture, it is necessary to use low crosshead speeds (0.5mm/s) and low punch cross-section (3mm2). Crust microstructure observations indicate that the crust layers and the size and shape of the air cells are responsible of the puncturing behavior. Practical Applications: Texture of the bread crust is an important parameter used to define the quality of crispy breads and their freshness. Consequently, the extension of crust crispiness is still a priority for the baking industry. Different methods have been proposed for assessing the mechanical properties of the bread crust, although punching is a common feature in all of them. However, there is no information about the incidence of punching settings on the bread crust mechanical parameters. Water activity and moisture content of the crust, besides scanning electron microscopy of the crust section, were used to confirm the reliability of the mechanical parameters. The study allows defining the best conditions to study the crust's mechanical properties providing information about the internal cell structure. Results could be very useful at research level and also for the baking industry when investigating crust freshness. © 2012 Wiley Periodicals, Inc. Source

Blanes S.,Polytechnic University of Valencia
Computer Physics Communications | Year: 2015

We consider the numerical integration of perturbed non-autonomous oscillatory systems using high order methods. The autonomous case has been efficiently integrated using explicit and symplectic Runge-Kutta-Nyström (RKN) methods like extended RKN methods, exponentially fitting RKN methods and splitting methods for perturbed systems. Recently, it has been shown that explicit and symplectic extended RKN methods and exponentially fitting RKN methods are equivalent (Wu et al., 2012) and in this work we show that these methods are also equivalent to splitting methods for perturbed oscillators. We provide a constructive proof which at the same time allows us to build for the first time new explicit and symplectic extended RKN methods for the non-autonomous problem (for multidimensional time dependent frequencies). The new methods obtained, while built from splitting methods, are different in the treatment of the time-dependent terms and can be superior in some cases. We build some new methods and show their performance on numerical examples. © 2015 Elsevier B.V. All rights reserved. Source

Due to the rapid spread of two subspecies of Leptochloa fusca through the Valencia rice-growing region in the east of Spain, a 3-year field study was carried out to establish the frequency, distribution and infestation level of the two subspecies in rice paddies in the area. A total of 3650 fields were visited, of which 1235 were visited in each year of the study period. Leptochloa fusca ssp. uninervia and Leptochloa fusca ssp. fascicularis were found to be widely distributed in the area, increasing from a frequency of 5.3% in 2008 to 20.1% in 2010. Leptochloa fusca ssp. uninervia was the largest contributor to the infestations, but subspecies fascicularis is now on the increase and represents a serious threat to rice crops, as it is found within the rice fields themselves. The irrigation system and the farm machinery used in the rice fields also contribute to the rapid spread of these weeds. Severe infestations have been caused by periodic water shortages, and the fact that new herbicides used to control Echinochloa spp. do not affect Leptochloa subspecies. Spatial differences in the distributions of the two subspecies are attributed to the different water management systems and also to differences in the germination and dormancy of both subspecies. © 2013 European Weed Research Society. Source

Tung M.M.,Polytechnic University of Valencia
EPL | Year: 2012

Transformation acoustics centers on the construction of advanced acoustic devices by combining mathematical transformation techniques with the engineering of acoustic metamaterials. We show how differential-geometric methods together with a variational principle form the basis of a powerful framework to control acoustic waves as desired. This formalism is required to leave the acoustic wave equation invariant under coordinate transformations and is shown to consist of a proposed acoustic Lagrangian function on a smooth spacetime manifold. As an immediate consequence, we can derive the general constitutive relations between the acoustic parameters (bulk modulus and mass-density tensor) of the physical and virtual spaces under consideration. We conclude with a practical application of this theory by presenting acoustic spherical cloaking with time dilation. Copyright © 2012 EPLA. Source

Molina J.-L.,University of Salamanca | Pulido-Velazquez D.,Geological Survey of Spain | Garcia-Arostegui J.L.,Geological Survey of Spain | Pulido-Velazquez M.,Polytechnic University of Valencia
Journal of Hydrology | Year: 2013

Bayesian Networks (BNs) are powerful tools for assessing and predicting consequences of water management scenarios and uncertain drivers like climate change, integrating available scientific knowledge with the interests of the multiple stakeholders. However, among their major limitations, the non-transient treatment of the cause-effect relationship stands out. A Decision Support System (DSS) based on Dynamic Bayesian Networks (DBNs) is proposed here aimed to palliate that limitation through time slicing technique. The DSS comprises several classes (Object-Oriented BN networks), especially designed for future 5. years length time steps (time slices), covering a total control period of 30. years (2070-2100). The DSS has been developed for assessing impacts generated by different Climate Change (CC) scenarios (generated from several Regional Climatic Models (RCMs) under two emission scenarios, A1B and A2) in an aquifer system (Serral-Salinas) affected by intensive groundwater use over the last 30. years. A calibrated continuous water balance model was used to generate hydrological CC scenarios, and then a groundwater flow model (MODFLOW) was employed in order to analyze the aquifer behavior under CC conditions. Results obtained from both models were used as input for the DSS, considering rainfall, aquifer recharge, variation of piezometric levels and temporal evolution of aquifer storage as the main hydrological components of the aquifer system. Results show the evolution of the aquifer storage for each future time step under different climate change conditions and under controlled water management interventions. This type of applications would allow establishing potential adaptation strategies for aquifer systems as the CC comes into effect. © 2012 Elsevier B.V. Source

Navarro J.M.,University of Murcia | Escolano J.,University of Jaen | Lopez J.J.,Polytechnic University of Valencia
Applied Acoustics | Year: 2012

In this paper, the use of finite difference schemes for the acoustic diffusion equation model is introduced. Their features and limitations are analysed to select the adequate scheme based on both the stability conditions and the error order. The air absorption effects on the implementation are also discussed in terms of stability. To investigate the validity of the implementation, a set of simulations was conducted in a cubic room with four different absorption distributions. This evaluation was done by increasing either the spatial or the temporal resolutions of the studied scheme. The predicted values are compared with the statistical theory and geometrical models. The simulations suggested an empirical criterion for predicting the spatial and temporal resolutions that maximise the performance of the finite difference scheme © 2012 Elsevier Ltd. All rights reserved. Source

Hueso A.,Polytechnic University of Valencia | Bell B.,University of Minnesota
Water Policy | Year: 2013

The Total Sanitation Campaign (TSC) was a community-led, people-centred, demand-driven and incentive-based programme ideal to address India's rural sanitation crisis, or so it seemed. But policy failed to translate into practice and outcomes were remarkably poor. In the 2011 census data showed 31% sanitation coverage in 2011 (up from 22% in 2001), far from the 68% reported by the Government. The decade has witnessed progress slowing down and the number of rural households without latrines increasing by 8.3 million. This article draws on evidence from two coordinated studies in four Indian states. It aims to explore the dichotomy of TSC policy and practice, its causes, and the potential of the new sanitation campaign, the Nirmal Bharat Abhiyan (NBA). The study found that TSC implementation was unaligned with the programme's guiding principles. In reality the TSC was government-led, infrastructurecentred, subsidy-based and supply-led, leading to poor outcomes. The reasons behind the theory-practice gap include low political priority; flawed monitoring; distorting accountability and career incentives; technocratic and paternalistic inertia; and corruption. In the new NBA, despite promising changes such as a stronger demand creation focus, key issues hampering implementation remain ignored. It is thus doomed to fail, burdened by known past hurdles. © 2013 IWA Publishing. Source

Bonet J.,Polytechnic University of Valencia | Bonilla A.,University of La Laguna
Complex Analysis and Operator Theory | Year: 2013

Motivated by recent work on the rate of growth of frequently hypercyclic entire functions due to Blasco, Grosse-Erdmann and Bonilla, we investigate conditions to ensure that the differentiation operator is chaotic or frequently hypercyclic on generalized weighted Bergman spaces of entire functions studied by Lusky, whenever the differentiation operator is continuous. As a consequence we partially complete the knowledge of possible rates of growth of frequently hypercyclic entire functions for the differentiation operator. © 2011 Springer Basel AG. Source

Barrera D.,Polytechnic University of Valencia
Sensors (Basel, Switzerland) | Year: 2013

Regenerated Fibre Bragg Gratings have the potential for high-temperature monitoring. In this paper, the inscription of Fibre Bragg Gratings (FBGs) and the later regeneration process to obtain Regenerated Fiber Bragg Gratings (RFBGs) in high-birefringence optical fiber is reported. The obtained RFBGs show two Bragg resonances corresponding to the slow and fast axis that are characterized in temperature terms. As the temperature increases the separation between the two Bragg resonances is reduced, which can be used for low cost interrogation. The proposed interrogation setup is based in the use of optical filters in order to convert the wavelength shift of each of the Bragg resonances into optical power changes. The design of the optical filters is also studied in this article. In first place, the ideal filter is calculated using a recursive method and defining the boundary conditions. This ideal filter linearizes the output of the interrogation setup but is limited by the large wavelength shift of the RFBG with temperature and the maximum attenuation. The response of modal interferometers as optical filters is also analyzed. They can be easily tuned shifting the optical spectrum. The output of the proposed interrogation scheme is simulated in these conditions improving the sensitivity. Source

Salido M.A.,Polytechnic University of Valencia
Journal of Intelligent Manufacturing | Year: 2010

Planning, scheduling and constraint satisfaction are important areas in artificial intelligence (AI). Many real-world problems are known as AI planning and scheduling problems, where resources must be allocated so as to optimize overall performance objectives. Therefore, solving these problems requires an adequate mixture of planning, scheduling and resource allocation to competing goal activities over time in the presence of complex state-dependent constraints. Constraint satisfaction plays also an important role to solve real-life problems, so that integrated techniques that manage planning and scheduling with constraint satisfaction remains necessary. This special issue on Planning, Scheduling and Constraint Satisfaction compiles a selection of papers of CAEPIA'2007 workshop on Planning, Scheduling and Constraint Satisfaction and COPLAS'2007: CP/ICAPS 2007 Joint Workshop on Constraint Satisfaction Techniques for Planning and Scheduling Problems. This issue presents novel advances on planning, scheduling, constraint programming/constraint satisfaction problems (CSPs) and many other common areas that exist among them. On the whole, this issue mainly focus on managing complex problems where planning, scheduling, constraint satisfaction and search must be combined and/or interrelated, which entails an enormous potential for practical applications and future research. Furthermore, this issue also includes a complete survey about constraint satisfaction, planning, scheduling and integration among these areas. © 2008 Springer Science+Business Media, LLC. Source

Consoli D.,University of Manchester | Consoli D.,Polytechnic University of Valencia | Elche-Hortelano D.,University of Castilla - La Mancha
Research Policy | Year: 2010

Knowledge Intensive Business Services (KIBS) are intermediary firms which specialise in knowledge screening, assessment and evaluation, and trade professional consultancy services. The remarkable rise of this broad class of activities is perceived by many as the natural by-product of modern knowledge economies within which increasing specialisation induces the need for professional agents in the markets for external knowledge. This paper addresses critically a conceptual flaw in the specialised literature which portrays KIBS as a homogeneous group of activities. Using official data on occupational information in the United States we observe and analyse high variety across KIBS sectors' occupational structures and skill requirements. Source

Pallares L.,Polytechnic University of Valencia | Hajjar J.F.,University of Illinois at Urbana - Champaign
Journal of Constructional Steel Research | Year: 2010

The formula in the 2005 American Institute of Steel Construction Specification to compute the strength of headed steel stud anchors (shear connectors) in composite steel/concrete structures has been used in the United States since 1993, after being proposed based primarily on the results of push-out tests. In the past several decades, the range of members used in composite structures has increased significantly, as has the number of tests in the literature on the monotonic and cyclic behavior of headed studs in composite construction. This paper reviews 391 monotonic and cyclic tests from the literature on experiments of headed stud anchors and proposes formulas for the limit states of steel failure and concrete failure of headed stud anchors subjected to shear force without the use of a metal deck. Detailing provisions to prevent premature pryout failure are also discussed. This paper also reviews proposals from several authors and provides recommended shear strength values for the seismic behavior of headed studs. The limit state formulas are proposed within the context of the 2005 AISC Specification, and comparisons are made to the provisions in the ACI 318-08 Building Code, the PCI Handbook, 6th Edition, and Eurocode 4. The scope of this research includes composite beam-columns [typically concrete-encased steel shapes (SRCs) or concrete-filled steel tubes (CFTs)], concrete-encased and concrete-filled beams, boundary elements of composite wall systems, composite connections, composite column base conditions, and related forms of composite construction. © 2009 Elsevier Ltd. All rights reserved. Source

George N.V.,Indian Institute of Technology Gandhinagar | Gonzalez A.,Polytechnic University of Valencia
Applied Acoustics | Year: 2014

This paper proposes a nonlinear active noise control (ANC) system based on convex combination of a functional link artificial neural network (FLANN) and a Volterra filter. Simulation study reveals enhanced noise cancelation performance of the proposed ANC system over the ones based on its component filters. © 2013 Elsevier Ltd. All rights reserved. Source

The goal of the study was to compare preductal SpO2 in the first 10 min after birth in preterm infants treated with non-invasive continuous positive airway pressure (CPAP) and air with a published nomogram of preductal SpO2 in preterm infants who received no medical intervention, and to examine gender differences. Prospective observational study. We enrolled infants of ≤32 weeks gestation who were spontaneously breathing with heart rate >100 bpm, and treated with face mask CPAP and air during postnatal stabilisation. SpO2 limits were targeted at ≥75% at 5 min and ≥85% at 10 min and heart rate at >100 bpm. FIO2 was titrated against SpO2. Preductal SpO2, airway pressure and FIO2 were recorded with a data acquisition system from birth until stabilisation. Babies receiving supplemental oxygen (>21%), positive pressure ventilation, were intubated and/or received chest compressions or drugs were excluded. Measurements were obtained in 102 babies with median gestational age of 29 (range: 24-31) weeks. Median SpO2 was significantly higher in the observational group than in the reference range at 3 min (82% (CI 71% to 85%) vs 76% (CI 67% to 83%); p<0.05), at 4 min (87% (CI 81% to 90%) vs 81% (CI 72% to 88%); p<0.05), at 5 min (92% (CI 88% to 95%) vs 86% (CI 80% to 92%); p<0.05), at 6 min (94% (CI 90% to 97%) vs 90% (CI 81% to 95%); p<0.05), at 7 min (95% (CI 92% to 97%) vs 92% (CI 85% to 95%); p<0.05), at 8 min (96% (CI 93% to 98%) vs 92% (CI 87% to 96%); p<0.05) and at 9 min (97% (CI 92% to 99%) vs 93% (CI 87% to 96%); p<0.05). Female babies achieved targeted SpO2 significantly earlier than male babies. Preterm babies receiving CPAP and air and especially female subjects achieve reference oxygen saturation more rapidly than spontaneously breathing preterm babies without respiratory aid. Source

Valcuende M.,Polytechnic University of Valencia | Parra C.,Technical University of Cartagena
Construction and Building Materials | Year: 2010

This experimental work involves a study of the carbonation depth in self-compacting concretes at different ages and also analyses their porous microstructure, since these aspects are directly related to each other. Eight different concretes were used, four self-compacting (SCC) and four normally-vibrated (NVC). The carbonation rate was found to be lower in SCC than NVC, due to the fact that limestone fines produce less porosity and a finer microstructure. The difference between both types of concrete tends to disappear as their fines content becomes similar. It was also observed that, under the test conditions (RH 60.8%), for pore sizes under 0.065 μm CO2 diffusion in the interior of the concrete is not significant. An expression is proposed to estimate carbonation rate in concrete from the volume of pores over 0.065 μm and the threshold diameter. © 2009 Elsevier Ltd. All rights reserved. Source

Pallares L.,Polytechnic University of Valencia | Hajjar J.F.,University of Illinois at Urbana - Champaign
Journal of Constructional Steel Research | Year: 2010

The 2005 AISC Specification for Structural Steel Buildings is the leading specification for composite construction in the US. However, these provisions do not provide a recommendation for computing the strength of headed steel stud anchors (traditionally used as shear connectors) under tension or combined tension and shear. Headed stud anchors are subjected to these types of forces in composite structures such as infill walls, composite coupling beams, the connection region of composite columns, or composite column bases. While the ACI 318-08 Building Code, the PCI Handbook, 6th edition, and CEB Design of Fastenings in Concrete include provisions for such conditions, those provisions are geared for more general anchorage conditions than are typically seen in composite construction. It would thus be beneficial to have design guidance specifically for the case of headed steel stud anchors subjected to tension or combined tension and shear in composite construction, evaluated within the context of the AISC and EC-4 Specifications. In this work, different strength equations to compute the nominal tensile strength of a headed stud are reviewed and compared to experimental results. The resulting recommendations seek to ensure a ductile failure in the steel shank instead of a brittle failure within the concrete. Several criteria are proposed to ensure that ductile failure controls in composite construction, and, different headed stud configurations and detailing reinforcement recommendations are proposed to improve the ductile behavior of headed stud anchors subjected to tension and combined tension and shear. © 2009 Elsevier Ltd. All rights reserved. Source

Vaya I.,French National Center for Scientific Research | Vaya I.,Polytechnic University of Valencia | Gustavsson T.,French National Center for Scientific Research | Douki T.,CEA Grenoble | And 2 more authors.
Journal of the American Chemical Society | Year: 2012

Transfer of the electronic excitation energy in calf thymus DNA is studied by time-resolved fluorescence spectroscopy. The fluorescence anisotropy, after an initial decay starting on the femtosecond time scale, dwindles down to ca. 0.1. The in-plane depolarized fluorescence decays are described by a stretched exponential law. Our observations are consistent with one-dimensional transfer mediated by charge-transfer excited states. © 2012 American Chemical Society. Source

Bataller R.C.,Polytechnic University of Valencia
Fluid Dynamics and Materials Processing | Year: 2010

The present research gathers an accurate numerical study of the laminar flow induced in an incompressible upper-convected Maxwell (UCM) fluid by a linear stretching of a flat, horizontal and porous sheet in the presence of a transverse magnetic field. The governing partial differential equations are converted into an ordinary differential equation by a similarity transformation. The effects on the velocity field over the sheet of the parameters like elasticity number, suction/blowing velocity, and magnetic parameter are also studied. It has also been attempted to show capabilities and wide-range applications of the 4th order Runge-Kutta method in comparison with the homotopy analysis method. Knowing in boundary layer theory that velocity profiles approach the ambient fluid conditions asymptotically, our numerical solutions were carried out under the simultaneous boundary conditions at infinity: f'→0 as η →, ∞ f" → 0 as η → ∞ (f being the non-dimensional stream function). In this manner, a remarkable accuracy for the missed skin friction coefficient f"(0) can be achieved. © 2010 Tech Science Press. Source

Collado-Ruiz D.,Polytechnic University of Valencia | Ostad-Ahmad-Ghorabi H.,Vienna University of Technology
Design Studies | Year: 2010

The positive effect of having environmental information is generally taken for granted in design for sustainability and ecodesign. Research in the field of creativity, however, has shown that the exposure to examples can provoke fixation and reduce the overall creativity of the idea-generation process. Different sorts and levels of information - commonly available for designers - was delivered to 56 people, all of whom were asked to generate different design ideas. Results prove that having detailed information - be it of previous models or of competing products - significantly reduces the creativity of the design ideas. Soft information, on the other hand, does not present this effect. Successful tools in the future must deliver relevant information avoiding this fixation effect. © 2010 Elsevier Ltd. All rights reserved. Source

Blasco T.,Polytechnic University of Valencia
Chemical Society Reviews | Year: 2010

This tutorial review intends to show the possibilities of in situ solid state NMR spectroscopy in the elucidation of reaction mechanisms and the nature of the active sites in heterogeneous catalysis. After a brief overview of the more usual experimental devices used for in situ solid state NMR spectroscopy measurements, some examples of applications taken from the recent literature will be presented. It will be shown that in situ NMR spectroscopy allows: (i) the identification of stable intermediates and transient species using indirect methods, (ii) to prove shape selectivity in zeolites, (iii) the study of reaction kinetics, and (iv) the determination of the nature and the role played by the active sites in a catalytic reaction. The approaches and methodology used to get this information will be illustrated here summarizing the most relevant contributions on the investigation of the mechanisms of a series of reactions of industrial interest: aromatization of alkanes on bifunctional catalysts, carbonylation reaction of methanol with carbon monoxide, ethylbenzene disproportionation, and the Beckmann rearrangement reaction. Special attention is paid to the research carried out on the role played by carbenium ions and alkoxy as intermediate species in the transformation of hydrocarbon molecules on solid acid catalysts. © 2010 The Royal Society of Chemistry. Source

Martinez-Torres M.R.,Escuela Universitaria de Estudios Empresariales | Toral-Marin S.L.,Polytechnic University of Valencia
Expert Systems with Applications | Year: 2010

This paper proposes to identify strategic groups among franchisors from a big set of franchisor variables. Genetic evolutionary computation was used to reduce a set of variables efficiently, and factor analysis was used to make up the strategic groups. Franchise 500 was used as database. The results suggest both that the general map of franchisor has changed since Carney and Gedajlovic's study, and that genetic evolutionary computation is a valid way to extract knowledge from a huge set of data. This paper proposes useful information for those retail firms considering internationalization via franchising. The originality of this paper is in the use of Genetic Algorithm to discriminate the final set of variables to be used for the identification of strategic groups instead of evaluating one by one the adequacy of each variable theoretically. The ability of evolutionary computation to create new knowledge is good to produce new insights into this topic. © 2009 Elsevier Ltd. All rights reserved. Source

Ballester-Beltran J.,Polytechnic University of Valencia
Biointerphases | Year: 2012

Cells behave differently between bidimensional (2D) and tridimensional (3D) environments. While most of the in vitro cultures are 2D, most of the in vivo extracellular matrices are 3D, which encourages the development of more relevant culture conditions, seeking to provide more physiological models for biomedicine (e.g., cancer, drug discovery and tissue engineering) and further insights into any dimension-dependent biological mechanism. In this study, cells were cultured between two protein coated surfaces (sandwich-like culture). Cells used both dorsal and ventral receptors to adhere and spread, undergoing morphological changes with respect to the 2D control. Combinations of fibronectin and bovine serum albumin on the dorsal and ventral sides led to different cell morphologies, which were quantified from bright field images by calculating the spreading area and circularity. Although the mechanism underlying these differences remains to be clarified, excitation of dorsal receptors by anchorage to extracellular proteins plays a key role on cell behavior. This approach--sandwich-like culture--becomes therefore a versatile method to study cell adhesion in well-defined conditions in a quasi 3D environment. Source

Ward F.A.,New Mexico State University | Pulido-Velazquez M.,Polytechnic University of Valencia
Water Resources Management | Year: 2012

Water claims in many of the world's arid basins exceed reliable supplies. Water demands for irrigation, urban use, the environment, and energy continue to grow, while supplies remain constrained by unsustainable use, drought and impacts of climate change. For example, policymakers in North America's Upper Rio Grande Basin face the challenge of designing plans for allocating the basin's water supplies efficiently and fairly to support current uses and current environments. Managers also seek resilient institutions that can ensure adequate supplies for future generations. This paper addresses those challenges by designing and applying an integrated basin-scale framework that accounts for the basin's most important hydrologic, economic, and institutional constraints. Its unique contribution is a quantitative analysis of three policies for addressing long term goals for the basin's reservoirs and aquifers: (1) no sustainability for water stocks, (2) sustaining water stocks, and (3) renewing water stocks. It identifies water use and allocation trajectories over time that result from each of these three plans. Findings show that it is hydrologically and institutionally feasible to manage the basin's water supplies sustainably. The economic cost of protecting the sustainability of the basin's water stocks can be achieved at 6-11 percent of the basin's average annual total economic value of water over a 20 year time horizon. © 2012 Springer Science+Business Media B.V. Source

Garcia-Meca C.,Polytechnic University of Valencia
Modern Physics Letters B | Year: 2013

Over the last decade, negative index media have attracted much attention due to their potential applications, especially the possibility of constructing superlenses. However, achieving high-performance negative-index metamaterials at visible frequencies, where this kind of media could find many applications, still remains a challenge. In this article, we provide a brief overview of the main routes for the implementation of metamaterials with negative index in this band, with a special focus on the so-called fishnet metamaterial. We pay particular attention to a specific fishnet configuration that recently allowed for the experimental demonstration of a low-loss and polarization-insensitive negative-index band in the visible regime. © 2013 World Scientific Publishing Company. Source

Puerto J.,University of Seville | Perea F.,Polytechnic University of Valencia
Computers and Operations Research | Year: 2013

In this paper we show a new method for calculating the nucleolus by solving a unique minimization linear program with O(4n) constraints whose coefficients belong to {-1,0,1}. We discuss the need of having all these constraints and empirically prove that they can be reduced to O( kmax2n), where kmax is a positive integer comparable with the number of players. A computational experience shows the applicability of our method over (pseudo)random transferable utility cooperative games with up to 18 players. © 2013 Elsevier Ltd. Source

Ripoll I.,Polytechnic University of Valencia
IEEE Transactions on Computers | Year: 2013

Task period selection is often used to adjust the workload to the available computational resources. In this paper, we propose a model where each selected period is not restricted to be a natural number, but can be any rational number within a range. Under this generalization, we contribute a period selection algorithm that yields a much smaller hyperperiod than that of previous works: with respect to the largest period, the hyperperiod with integer constraints is exponentially bounded; with rational periods the worst case is only quadratic. By means of an integer approximation at each task activation, we show how our rational period approach can work under system clock granularity; it is thus compatible with scheduling analysis practice and implementation. Our finding has practical applications in several fields of real-time scheduling: lowering complexity in table driven schedulers, reducing search space in model checking analysis, generating synthetic workload for statistical analysis of real-time scheduling algorithms, etc. © 1968-2012 IEEE. Source

Tortajada-Genaro L.A.,Polytechnic University of Valencia
Atmospheric Environment | Year: 2012

The production of condensate compounds from the degradation of benzene by OH radical chemistry was studied. Secondary organic aerosol (SOA) formation was investigated in the EUPHORE (European Photoreactor) simulation chambers. Experiments were performed under different OH-production conditions - addition of H 2O 2, NO or HONO -, in a high-volume reactor, with natural light and in the absence of seed aerosols. The consumption of precursor/reagents, the formation of gas-phase and particulate-phase products and the temporal evolution of aerosol were monitored. Several aerosol physical properties - mass concentration, overall aerosol yield, particle size distribution and density - were determined and found to be clearly dependent on OH radical production and NO x concentrations. Furthermore, the use of one and/or two products gas-particle partitioning absorption models allowed us to determine the aerosol yield curves. The SOA yield ranged from 1.6 to 9.7 %, with higher SOA formation under low-NO x conditions. Chemical characterization of the SOA was carried out, determining multi-oxygenated condensed organic compounds by a method based on the gas chromatography-mass spectrometry technique. Several ring-retaining and ring-cleavage products were identified and quantified. The compounds with the highest percentage contribution to the total aerosol mass were 4-nitrobenzene-1,2-diol, butenedioic acid, succinic acid and trans-trans-muconic. In addition, a multigenerational study was performed comparing with the photo-oxidations of phenol and catechol. The results showed that although the mass concentration of SOA produced was different, the physical and chemical properties were quite similar. Finally, we suggest a general mechanism to describe how changes in benzene degradation pathways - rate of OH generation and concentration of NO x - could justify the variation in SOA production and properties. © 2011 Elsevier Ltd. Source

Lapuente E.,Polytechnic University of Valencia
Desalination | Year: 2012

The cost of desalinated water is likely one of the most relevant indicators to characterize and compare desalination with other technical options to supply water for urban, industrial and agricultural purposes, not to mention the social and environmental aspects associated with each option. A first step toward selecting the most appropriate solution to water shortage is to disclose fully and accurately desalination costs associated with each alternative to both government bodies and general public. This is known in economic terms as the full cost. In principle, costs associated with the production of desalinated water are easy to assess. However, it is difficult to compare costs from different facilities in practical terms due to lack of detailed data as well as the lack of a common method for cost estimation. This study aims to present a clear and easy methodology for estimating seawater desalination costs. As a case study, this methodology was applied to seven large-size desalination plants located in the Segura River Basin (Spain). © 2012 Elsevier B.V. Source

Peman J.,Polytechnic University of Valencia
Expert review of anti-infective therapy | Year: 2012

Invasive fungal infections are associated with high morbidity and mortality in critically ill patients due, in part, to diagnostic difficulties in the early stages. Nonculture-based techniques such as (1,3)-β-d-glucan, galactomannan, mannan and antimannan antibodies, Candida albicans germ tube-specific antibodies or fungal DNA are required for earlier diagnosis, prognostic information and monitoring outcome. A decision-tree algorithm based on the combination of nonculture-based techniques is suggested to optimize the diagnosis and evolution of critically ill patients at risk of invasive mycoses. The use of (1,3)-β-d-glucan and blood cultures twice a week is proposed; if positive, treatment initiation is recommended alongside the performance of the nonculture-based microbiological tool depending on suspected mycoses and the availability of techniques. Source

Coupe P.,CNRS Computer Science Laboratory | Manjon J.V.,Polytechnic University of Valencia | Chamberland M.,Universite de Sherbrooke | Descoteaux M.,Universite de Sherbrooke | Hiba B.,University of Bordeaux Segalen
NeuroImage | Year: 2013

In this paper, a new single image acquisition super-resolution method is proposed to increase image resolution of diffusion weighted (DW) images. Based on a nonlocal patch-based strategy, the proposed method uses a non-diffusion image (b0) to constrain the reconstruction of DW images. An extensive validation is presented with a gold standard built on averaging 10 high-resolution DW acquisitions. A comparison with classical interpolation methods such as trilinear and B-spline demonstrates the competitive results of our proposed approach in terms of improvements on image reconstruction, fractional anisotropy (FA) estimation, generalized FA and angular reconstruction for tensor and high angular resolution diffusion imaging (HARDI) models. Besides, first results of reconstructed ultra high resolution DW images are presented at 0.6×0.6×0.6mm3 and 0.4×0.4×0.4mm3 using our gold standard based on the average of 10 acquisitions, and on a single acquisition. Finally, fiber tracking results show the potential of the proposed super-resolution approach to accurately analyze white matter brain architecture. © 2013 Elsevier Inc. Source

Casares-Giner V.,Polytechnic University of Valencia
Electronics Letters | Year: 2016

Some teletraffic tools used in the evaluation of optical burst switching with burst segmentation (OBS/BS) are dealt. These analytic tools shown are in fact supported by the Molina or blocked call held model. Furthermore, some additional results are also obtained in OBS/BS when the head dropping is implemented as contention resolution scheme. In particular, it is shown that as long as the service discipline is work-conservative, the percentage of bursts that are completely lost is independent of the service discipline and equals to the fraction of information that is cut-off. Source

The parallelization of the finite-difference time-domain (FDTD) method for room acoustic simulation using graphic processing units (GPUs) has been subject of study even prior to the introduction of general-purpose computing environments such as the CUD A architecture. Nowadays CUDA offers enough flexibility and processing power to obtain performance gains higher than 200 times compared to single-threaded CPU codes. In this paper, different aspects related to the implementation of FDTD in CUDA are analyzed; first, how the evolution of the different CUDA architectures affects implementations is inquired, paying special attention to the Kepler architecture, the latest available. Also performance increasing by using the different memory subsystems the GPU offers is discussed. Moreover, the performance in the use of the available computing power in the GPU is also analyzed together with the limiting factors such as memory consumption and computing time that prevent the simulation of large rooms at very high frequencies. Next the hybrid methods that combine FDTD with other less expensive room acoustic methods are commented. Finally the application of GPU for the acceleration of the Diffusion Equation Method for room acoustic simulation is discussed. © 2013 Acoustical Society of America. Source

Baeza L.,Polytechnic University of Valencia | Ouyang H.,University of Liverpool
Journal of Sound and Vibration | Year: 2011

This article presents a technique for modelling the coupled dynamics of a railway vehicle and the track. The method is especially useful for simulating the dynamics of high speed trains running on nonlinear tracks. The main hypothesis is a cyclic system: an infinite track on which there is an infinite set of identical vehicles spaced at a regular interval of distance. Thus the main problems of the finite-length track models (e.g. the waves that reflect at the end of the track and interact with the vehicle; and the time interval of integration must be shorter than the track length divided by the velocity) are avoided. The flexibility of the method can be observed from the case studies presented in the present work: a vehicle passing over a hanging sleeper, and the vehicletrack dynamics for different ballast compaction cases. The results show the influence of the hanging sleeper gap on the wheelrail contact forces, and the bending moment at the sleeper for different ballast compaction cases. © 2010 Elsevier Ltd. Source

Leydesdorff L.,University of Amsterdam | Rafols I.,University of Sussex | Rafols I.,Polytechnic University of Valencia | Chen C.,Drexel University
Journal of the American Society for Information Science and Technology | Year: 2013

Using the option Analyze Results with the Web of Science, one can directly generate overlays onto global journal maps of science. The maps are based on the 10,000+ journals contained in the Journal Citation Reports (JCR) of the Science and Social Sciences Citation Indices (2011). The disciplinary diversity of the retrieval is measured in terms of Rao-Stirling's "quadratic entropy" (Izsák & Papp, 1995). Since this indicator of interdisciplinarity is normalized between 0 and 1, interdisciplinarity can be compared among document sets and across years, cited or citing. The colors used for the overlays are based on Blondel, Guillaume, Lambiotte, and Lefebvre's (2008) community-finding algorithms operating on the relations among journals included in the JCR. The results can be exported from VOSViewer with different options such as proportional labels, heat maps, or cluster density maps. The maps can also be web-started or animated (e.g., using PowerPoint). The "citing" dimension of the aggregated journal-journal citation matrix was found to provide a more comprehensive description than the matrix based on the cited archive. The relations between local and global maps and their different functions in studying the sciences in terms of journal literatures are further discussed: Local and global maps are based on different assumptions and can be expected to serve different purposes for the explanation. © 2013 ASIS&T. Source

Gomez-Barea A.,Polytechnic University of Valencia | Leckner B.,Chalmers University of Technology
Progress in Energy and Combustion Science | Year: 2010

Modeling of biomass gasification in bubbling and circulating fluidized bed (FB) gasifiers is reviewed. Approaches applied for reactor modeling, from black-box models to computational fluid-dynamic models, are described. Special attention is paid to comprehensive fluidization models, where semi-empirical correlations are used to simplify the fluid-dynamics. The conversion of single fuel particles, char, and gas is examined in detail. The most relevant phenomena to be considered in modeling of FB biomass gasifiers are outlined, and the need for further investigation is identified. An updated survey of published mathematical reactor models for biomass and waste gasification in FB is presented. The overall conclusion is that most of the FB biomass gasification models fit reasonably well experiments selected for validation, despite the various formulations and input data. However, there are few measurements available for comparison with detailed model results. Also, validation of models with data from full-scale FB biomass gasification units remains to be done. © 2010 Elsevier Ltd. All rights reserved. Source

Lazaro M.,Polytechnic University of Valencia
Journal of Applied Mechanics, Transactions ASME | Year: 2015

Nonviscously damped vibrating systems are characterized by dissipative mechanisms depending on the time-history of the response velocity, introduced in the physical models using convolution integrals involving hereditary kernel functions. One of the most used damping viscoelastic models is the Biot's model, whose hereditary functions are assumed to be exponential kernels. The free-motion equations of these types of nonviscous systems lead to a nonlinear eigenvalue problem enclosing certain number of the so-called nonviscous modes with nonoscillatory nature. Traditionally, the nonviscous modes (eigenvalues and eigenvectors) for nonproportional systems have been computed using the state-space approach, computationally expensive. In this paper, we address this problem developing a new method, computationally more efficient than that based on the state-space approach. It will be shown that real eigenvalues and eigenvectors of viscoelastically damped system can be obtained from a linear eigenvalue problem with the same size as the physical system. The numerical approach can even be enhanced to solve highly damped problems. The theoretical results are validated using a numerical example. Copyright © 2015 by ASME. Source

Cortell R.,Polytechnic University of Valencia
Mathematical Problems in Engineering | Year: 2012

The steady magnetohydrodynamic (MHD) flow and mass transfer of an incompressible, viscous, and electrically conducting fluid over a permeable flat surface stretched with nonlinear (quadratic) velocity u w (x) = a x + c 0 x 2 and appropriate wall transpiration is investigated. It is shown that the problem permits an analytical solution for the complete set of equations with magnetic field influences when a fictitious presence of a chemical reaction is considered. Velocity and concentration fields are presented through graphs and discussed. The results for both skin friction coefficient f ′′ (0) and mass transfer gradient c ′ (0) agree well with numerical results published in the literature. © 2012 Rafael Cortell. Source

Miralles i Garcia J.L.,Polytechnic University of Valencia
WIT Transactions on Ecology and the Environment | Year: 2011

The last real estate cycle in Spain is a paradigmatic example of non sustainable development. The extraordinary urban development in the 1997-2007 period produced an extraordinary economic growth based on land speculation and housing. The end of the cycle generates a very severe economic crisis, one that is the most serious economic crisis in a long time. This process has economic, social and environmental repercussions; from the economic point of view Spain has a temporally increased its GDP. The real estate activity has generated houses, and land able to be developed, but without use and without a market. From the social point of view, the Spanish people have changed their system of moral value. It takes as an ideal rapid enrichment without effort and without producing useful goods and services, and from the environmental point of view, on building over an extensive area without use. It is an irreversible process of rural land transformation. All land conversion is carried out by urban planning; the landscape changes and "urban sprawl" increases. © 2011 WIT Press. Source

Gonzalez J.A.,Polytechnic University of Valencia | Park K.C.,Korea Advanced Institute of Science and Technology | Park K.C.,University of Colorado at Boulder
International Journal for Numerical Methods in Engineering | Year: 2012

A simple explicit-implicit finite element tearing and interconnecting (FETI) algorithm (AFETI-EI algorithm) is presented for partitioned transient analysis of linear structural systems. The present algorithm employs two decompositions. First, the total system is partitioned via spatial or domain decomposition to obtain the governing equations of motions for each partitioned domain. Second, for each partitioned subsystem, the governing equations are modally decomposed into the rigid-body and deformational equations. The resulting rigid-body equations are integrated by an explicit integrator, for its stability is not affected by step-size restriction on account of zero-frequency contents (ω = 0). The modally decomposed partitioned deformation equations of motion are integrated by an unconditionally stable implicit integration algorithm. It is shown that the present AFETI-EI algorithm exhibits unconditional stability and that the resulting interface problem possesses the same solution matrix profile as the basic FETI static problems. The present simple dynamic algorithm, as expected, falls short of the performance of the FETI-DP but offers a similar performance of implicit two-level FETI-D algorithm with a much cheaper coarse solver; hence, its simplicity may offer relatively easy means for conducting parallel analysis of both static and dynamic problems by employing the same basic scalable FETI solver, especially for research-mode numerical experiments. © 2011 John Wiley & Sons, Ltd. Source

Lindberg D.,Uppsala University | De La Revenga M.F.,Polytechnic University of Valencia | Widersten M.,Uppsala University
Biochemistry | Year: 2010

The underlying enzyme kinetics behind, the regioselective promiscuity shown by epoxide hydrolases toward, certain epoxides has been studied. The effects of temperature and pH on regioselectivity were investigated by analyzing the stereochemistry of hydrolysis products of (1R,2R)-trans-2-methylstyrene oxide between 14-46 °C and pH 6.0-9.0, either catalyzed by the potato epoxide hydrolase StEH1 or in the absence of enzyme. In the enzyme-catalyzed reaction, a switch of preferred, epoxide carbon that is subjected to nucleophilic attack is observed at pH values above 8. The enzyme also displays cooperativity in substrate saturation plots when assayed at temperatures ≤30 °C and at intermediate pH. The cooperativity is lost at higher assay temperatures. Cooperativity can originate from, a kinetic mechanism involving hysteresis and will be dependent on. the relationship between Kcat and the rate of interconversion between two different Michaelis complexes. In the case of the studied reactions, the proposed different Michaelis complexes are enzyme-substrate complexes in which the epoxide substrate is bound in different binding modes, allowing for separate pathways toward product formation. The assumption of separated, but interacting, reaction pathways is supported by that formation of the two product enantiomers also displays distinct pH dependencies of Kcat/ KM The thermodynamic parameters describing the differences in activation enthalpy and entropy suggest that (1) regioselectivity is primarily dictated by differences in activation entropy with positive values of both ΔΔ‡H and ΔΔ ‡ and (2) the hysteretic behavior is linked, to an interconversion between Michaelis complexes with rates increasing with temperature. From the collected data, we propose that hysteresis, regioselectivity, and, when applicable, hysteretic cooperativity are closely linked properties, explained by the kinetic mechanism earlier introduced by our group. © 2010 American Chemical Society. Source

Hazirolan G.,Hacettepe University | Canton E.,Polytechnic University of Valencia | Sahin S.,Hacettepe University | Arikan-Akdagli S.,Hacettepe University
Antimicrobial Agents and Chemotherapy | Year: 2013

Treatment of disseminated Trichosporon infections still remains difficult. Amphotericin B frequently displays inadequate fungicidal activity and echinocandins have no meaningful antifungal effect against this genus. Triazoles are currently the drugs of choice for the treatment of Trichosporon infections. This study evaluates the inhibitory and fungicidal activities of five triazoles against 90 clinical isolates of Trichosporon asahii. MICs (μg/ml) were determined according to Clinical and Laboratory Standards Institute microdilution method M27-A3 at 24 and 48 h using two endpoints, MIC-2 and MIC-0 (the lowest concentrations that inhibited∼50 and 100% of growth, respectively). Minimum fungicidal concentrations (MFCs; μg/ml) were determined by seeding 100 μl of all clear MIC wells (using an inoculum of 104 CFU/ml) onto Sabouraud dextrose agar. Time-kill curves were assayed against four clinical T. asahii isolates and the T. asahii ATCC 201110 strain. The MIC-2 (∼50% reduction in turbidity compared to the growth control well)/MIC-0 (complete inhibition of growth)/MFC values that inhibited 90% of isolates at 48 h were, respectively, 8/32/64 μg/ml for fluconazole, 1/2/8 μg/ml for itraconazole, 0.12/0.5/2 μg/ml for voriconazole, 0.5/2/4 μg/ml for posaconazole, and 0.25/1/4 μg/ml for isavuconazole. The MIC-0 endpoints yielded more consistent MIC results, which remained mostly unchanged when extending the incubation to 48 h (98 to 100% agreement with 24-h values) and are easier to interpret. Based on the time-kill experiments, none of the drugs reached the fungicidal endpoint (99.9% killing), killing activity being shown but at concentrations not reached in serum. Statistical analysis revealed that killing rates are dose and antifungal dependent. The lowest concentration at which killing activity begins was for voriconazole, and the highest was for fluconazole. These results suggest that azoles display fungistatic activity and lack fungicidal effect against T. asahii. By rank order, the most active triazole is voriconazole, followed by itraconazole∼posaconazole∼ isavuconazole>fluconazole. Copyright © 2013, American Society for Microbiology. All Rights Reserved. Source

Puga A.V.,Polytechnic University of Valencia
Coordination Chemistry Reviews | Year: 2016

The application of photocatalysis for the utilisation of sunlight energy is intensely investigated in present times, particularly in prospect of generating solar fuels by hydrogen production or CO2 reduction processes as tools for societies aiming to relief their thirst for fossil resources. From the perspective of sustainability, the rational use of biomass-derived feedstocks for photocatalytic H2 production is a feasible, proven and highly efficient process. In this review, in addition to delving into physico-chemical fundamentals of photocatalytic processes on semiconductors, the research activity on this topic related to the design of revolutionary semiconductor-based materials, generally including metallic nanoparticles or complexes as hydrogen-evolving co-catalysts, is outlined and critically evaluated. Moreover, the use of sunlight and renewable feedstocks for the generation of hydrogen, as a compelling opportunity for the energy sector, is emphasised. Special focus is also set on the valorisation of biorefinery products, agricultural residues and industrial or municipal waste. © 2016 Elsevier B.V. Source

Rasero-Almansa A.M.,CSIC - Institute of Materials Science | Corma A.,Polytechnic University of Valencia | Iglesias M.,CSIC - Institute of Materials Science | Sanchez F.,Institute Quimica Organica General
ChemCatChem | Year: 2014

The direct N-alkylation of amines with alcohols was performed with an Ir-Zr-based metal-organic framework multifunctional heterogeneous catalyst. This system is efficient and environmentally benign for the synthesis of various organic amines in air in the absence of a base. The catalyst was recovered and reused without significant loss of activity, and only water was produced as a byproduct. Better be direct than elusive: The direct N-alkylation of amines with alcohols is performed with an Ir-Zr-based metal-organic framework multifunctional heterogeneous catalyst. This system is efficient and environmentally benign for the synthesis of various organic amines in air in the absence of a base. The catalyst is recovered and reused without significant loss of activity, and only water is produced as a byproduct. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Knapp S.,Natural History Museum in London | Vorontsova M.S.,Herbarium | Prohens J.,Polytechnic University of Valencia
PLoS ONE | Year: 2013

Background: The common or brinjal eggplant (Solanum melongena L.) belongs to the Leptostemonum Clade (the "spiny" solanums) of the species-rich genus Solanum (Solanaceae). Unlike most of the genus, the eggplant and its relatives are from the Old World; most eggplant wild relatives are from Africa. An informal system for naming eggplant wild relatives largely based on crossing and other biosystematics data has been in use for approximately a decade. This system recognises several forms of two broadly conceived species, S. incanum L. and S. melongena. Recent morphological and molecular work has shown that species-level differences exist between these entities, and a new species-level nomenclature has been identified as necessary for plant breeders and for the maintenance of accurately named germplasm. Methodology/Principal Findings: We examined herbarium specimens from throughout the wild species ranges as part of a larger revision of the spiny solanums of Africa. Based on these morphological and molecular studies, we delimited species in the group to which the common eggplant belongs and constructed identification keys for the group. We also examined the monophyly of the group considered as the eggplant relatives by previous authors. Conclusions/Significance: We recognise ten species in this group: S. aureitomentosum Bitter, S. campylacanthum A.Rich., S. cerasiferum Dunal, S. incanum L., S. insanum L., S. lichtensteinii Willd., S. linnaeanum Hepper & P.-M.L.Jaeger, S. melongena L., S. rigidum Lam. and S. umtuma Voronts. & S.Knapp. We review the history of naming and provide keys and character lists for all species. Ploidy level differences have not been investigated in the eggplant wild relatives; we identify this as a priority for improvement of crop wild relative use in breeding. The application of species-level names to these entities will help focus new collecting efforts for brinjal eggplant improvement and help facilitate information exchange. © 2013 Knapp et al. Source

Ostad-Ahmad-Ghorabi H.,Vienna University of Technology | Collado-Ruiz D.,Polytechnic University of Valencia
International Journal of Life Cycle Assessment | Year: 2011

Purpose Information constitutes one of the main barriers for applying life cycle assessment (LCA) due to complexity and need for great amounts of it. However, most of the parameters that determine the data are defined early in the product development process. Knuckle boom cranes constitute a complex product which poses a particularly pressing need for simplification. This paper models the LCA inventory information out of design parameters. The paper also presents a tool implementing this. Materials and methods To develop the parametric model, a three-step approach is followed. In the first step, knuckle boom crane designers of an international manufacturer are asked to point out key design parameters. An LCA is then conducted for a representative crane of the same manufacturer. Interdependencies between design parameters and inventories are analyzed. Design parameters influencing the LCA results are defined as primary parameters. Parameters through which it is possible to calculate the LCA inventory are defined as secondary parameters. The relation between primary and secondary parameters is analyzed. Indicators are developed for comparison, and the validity of this parametric model is checked by analyzing six more cranes, different in size and performance. Results and discussion The parametric model presented in this paper contains 13 primary parameters. Their link to secondary parameters and inventory data is through formulas derived from existing documentation, physical interdependencies, or statistical data. To integrate this model in the design workflow, it is embedded into a software tool. Designers input the primary parameters, and the tool allows visualization and benchmarking of environmental impact results. Three indicators related to weight and environmental performance are defined, as well as the means to benchmark in relative terms. The model diverges in never more than 4% for six additional cranes analyzed. Conclusions Through the parametric model, a rigorous estimation of the environmental profile of a crane can already be assessed in an early point of the product development process. Results can be used to define targets for design decisions based on the best-performing products. Recommendations and perspectives The statistics-based estimations carried out by the tool can be further improved, getting a wider range of cranes involved. Differences between these products can increase the understanding of the effect of technology choices in the final environmental impact of the product. This may become particularly useful in early design decisions. The potentials of this parametric approach can also be extended to other types of products. © Springer-Verlag 2011. Source

Vento M.,Polytechnic University of Valencia | Lista G.,V Buzzi Childrens Hospital ICP
Paediatric Respiratory Reviews | Year: 2015

Premature infants often experience difficulties adapting to postnatal life. The most relevant ones are related to establishing an adult type cardiorespiratory circulation and acquiring hemodynamic stability, aerating the lung and attaining a functional residual capacity, performing an adequate gas exchange and switching to an oxygen enriched metabolism, and keeping an adequate body temperature. In recent years a body of evidence supports a trend towards gentle management in the delivery room aiming to reduce damage especially to the lungs in the so-called first golden minutes. Herewith, we describe and update four of the most relevant interventions performed in the delivery room: delayed cord clamping, non-invasive ventilation, individualized oxygen supplementation, and maintaining an adequate body temperature so as to avoid hyperthermia and/or hypothermia. © 2015 Elsevier Ltd. Source

Darmani A.,Stockholm School of Economics | Darmani A.,Technical University of Madrid | Arvidsson N.,Stockholm School of Economics | Hidalgo A.,Technical University of Madrid | Albors J.,Polytechnic University of Valencia
Renewable and Sustainable Energy Reviews | Year: 2014

At present, governments are embarking on the ambitious undertaking of increasing their countries' market share of renewable energy. Political ambitions, however, are just one of the driving forces for energy companies' to engage in innovative climate projects. Energy companies' perceptions of business opportunities are dependent on a set of factors that influence their innovation ambitions. This research operationalizes previous work on the main drivers of the establishment of Renewable Energy Technologies (RETs), with the aim of presenting an overview of the typical systemic drivers within a technological innovation system (TIS) framework. This leads to the proposal of a comprehensive typology and categorization of drivers of RETs. The typology is validated empirically by analyzing data on the development of four types of RETs (wind, solar, biomass and wave energy) in eight European countries (EU-7 and Ireland). The study's results shed light on the multilateral drivers behind the development of RETs. Furthermore, a cross-case comparative study reveals the differences between drivers of RETs and the patterns of these drivers in different countries. © 2014 Elsevier Ltd. Source

Williams T.A.,Trinity College Dublin | Fares M.A.,Trinity College Dublin | Fares M.A.,Polytechnic University of Valencia
Genome Biology and Evolution | Year: 2010

Molecular chaperones are highly conserved and ubiquitous proteins that help other proteins in the cell to fold. Pioneering work by Rutherford and Lindquist suggested that the chaperone Hsp90 could buffer (i.e., suppress) phenotypic variation in its client proteins and that alternate periods of buffering and expression of these variants might be important in adaptive evolution. More recently, Tokuriki and Tawfik presented an explicit mechanism for chaperone-dependent evolution, in which the Escherichia coli chaperonin GroEL facilitated the folding of clients that had accumulated structurally destabilizing but neofunctionalizing mutations in the protein core. But how important an evolutionary force is chaperonin-mediated buffering in nature? Here, we address this question by modeling the per-residue evolutionary rate of the crystallized E. coli proteome, evaluating the relative contributions of chaperonin buffering, functional importance, and structural features such as residue contact density. Previous findings suggest an interaction between codon bias and GroEL in limiting the effects of misfolding errors. Our results suggest that the buffering of deleterious mutations by GroEL increases the evolutionary rate of client proteins. We then examine the evolutionary fate of GroEL clients in the Mycoplasmas, a group of bacteria containing the only known organisms that lack chaperonins. We show that GroEL was lost once in the common ancestor of a monophyletic subgroup of Mycoplasmas, and we evaluate the effect of this loss on the subsequent evolution of client proteins, providing evidence that client homologs in 11 Mycoplasma species have lost their obligate dependency on GroEL for folding. Our analyses indicate that individual molecules such as chaperonins can have significant effects on proteome evolution through their modulation of protein folding. © The Author(s) 2010. Source

Bishop K.,National Institute of Economic and Social Research | D'Este P.,Polytechnic University of Valencia | Neely A.,University of Cambridge
Research Policy | Year: 2011

This paper examines the various methods through which firms benefit from interactions with universities, arguing that such benefits are instrumental in nurturing the multiple facets of a firm's absorptive capacity. We bring together data collected from a survey of UK firms that collaborated with universities, and firm-level data on past partnerships with universities. The results show that benefits from interactions with universities are multifaceted, including enhancement of the firm's explorative and exploitative capabilities. Results also indicate that firms' R&D commitments, geographical proximity to and research quality of university partners have a distinct impact on the different types of benefits from interactions with universities. We find geographical proximity is crucial for assessing problem-solving as an important benefit, while interactions with top quality universities have a positive influence on the benefits associated with firms' downstream activities. We discuss the implications of these findings for research and policy. © 2010 Elsevier B.V. All rights reserved. Source

Hernandez-Orallo J.,Polytechnic University of Valencia
Pattern Recognition | Year: 2013

Receiver Operating Characteristic (ROC) analysis is one of the most popular tools for the visual assessment and understanding of classifier performance. In this paper we present a new representation of regression models in the so-called regression ROC (RROC) space. The basic idea is to represent over-estimation against under-estimation. The curves are just drawn by adjusting a shift, a constant that is added (or subtracted) to the predictions, and plays a similar role as a threshold in classification. From here, we develop the notions of optimal operating condition, convexity, dominance, and explore several evaluation metrics that can be shown graphically, such as the area over the RROC curve (AOC). In particular, we show a novel and significant result: the AOC is equivalent to the error variance. We illustrate the application of RROC curves to resource estimation, namely the estimation of software project effort. © 2013 Elsevier Ltd. Source

Orduna-Malea E.,Polytechnic University of Valencia
Journal of the American Society for Information Science and Technology | Year: 2013

The aggregation of web performance data (page count and visibility) of internal university units could constitute a more precise indicator than the overall web performance of the universities and, therefore, be of use in the design of university web rankings. In order to test this hypothesis, a longitudinal analysis of the internal units of the Spanish university system was conducted over the course of 2010. For the 13,800 URLs identified, page count and visibility were calculated using the Yahoo! API. The internal values obtained were aggregated by university and compared with the values obtained from the analysis of the universities' general URLs. The results indicate that, although the correlations between general and internal values are high, internal performance is low in comparison to general performance, and that they give rise to different performance rankings. The conclusion is that the aggregation of unit performance is of limited use due to the low levels of internal development of the websites, and so its use is not recommended for the design of rankings. Despite this, the internal analysis enabled the detection of, among other things, a low correlation between page count and visibility due to the widespread use of subdirectories and problems accessing certain content. © 2013 ASIS&T. Source

Odor detection thresholds (ODTs) are used for assessing outdoor and indoor air quality. They are obtained experimentally by olfactometry and psychophysical methods, and large compilations are available in the literature. A non-linear regression equation was fitted to describe the ODT variability of 114 aliphatic compounds based on the alkyl chain length for different homologous series (carboxylic acids, aldehydes, 2-ketones, esters, 1-alcohols, amines, thiols, thioethers and hydrocarbons). The resulting equation reveals an effect of the functional group, molecular size and also an interaction between both factors. Although the mechanistic interpretation of results is uncertain, the relatively high goodness-of-fit (R2 = 0.90) suggests that ODT values of aliphatic compounds can be predicted rather accurately, which is not the case for rigid molecules. This equation may serve as a basis for the development of more complex ODT models taking into account diverse structural features of odorants. The variability of power-law exponents was also investigated for the homologous series. © 2012 by the authors; licensee MDPI, Basel, Switzerland. Source

Decker H.,Polytechnic University of Valencia
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2012

Integrity constraints are a means to model the quality of databases. Measures that size the amount of constraint violations are a means to monitor and maintain the quality of databases. We present and discuss new violation measures that refine and go beyond previous inconsistency measures. They serve to check updates for integrity preservation and to repair violations in an inconsistency-tolerant manner. © 2012 Springer-Verlag. Source

Martinez-Felipe A.,Polytechnic University of Valencia
Liquid Crystals | Year: 2011

Transport phenomena through polymeric composite membranes depend on several complex factors, involving not only their chemical composition but also their microstructure. Due to the combination of mesomorphic and macromolecular behaviour, thermotropic liquid crystal polymers (LCP) may enhance the transport properties in membranes by improving parameters related to the order, orientation, connectivity and distribution of the different domains arising from phase separation. This paper provides an overview of some existing and potential applications of liquid crystals (LC) in polymeric membranes as effective structure-directing templates or as components providing a dynamic response to external stimuli. The first part is a description of the composition and phase behaviour of LCP containing ionic and ionogenic groups, the so-called liquid crystal ionomers (LCI). The second part is focused on the description of LCP and LCI used in transport applications, such as proton-conducting films in fuel cells, ionic polymer transducers and hydrogels. The paper highlights the relationships between the composition and the LC properties of the materials and their potential as membranes for ionic and solvent transport, with particular attention paid to covalently linked materials prepared by copolymerisation, due to their higher versatility and stability. © 2011 Taylor & Francis. Source

Polytechnic University of Valencia and CSIC - Institute of Refrigeration | Date: 2011-03-10

The invention relates to a method for obtaining surfactants from cellulose and hemicellulose, which comprises one reaction in a single reactor (one pot) and which includes at least the following st