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[EN] Surface electromyography (sEMG) can be used for the evaluation of respiratory muscle activity. Recording sEMG involves the use of surface electrodes in a bipolar configuration. However, electrocardiographic (ECG) interference and electrode orientation represent considerable drawbacks to bipolar acquisition. As an alternative, concentric ring electrodes (CREs) can be used for sEMG acquisition and offer great potential for the evaluation of respiratory muscle activity due to their enhanced spatial resolution and simple placement protocol, which does not depend on muscle fiber orientation. The aim of this work was to analyze the performance of CREs during respiratory sEMG acquisitions. Respiratory muscle sEMG was applied to the diaphragm and sternocleidomastoid muscles using a bipolar and a CRE configuration. Thirty-two subjects underwent four inspiratory load spontaneous breathing tests which was repeated after interchanging the electrode positions. We calculated parameters such as (1) spectral power and (2) median frequency during inspiration, and power ratios of inspiratory sEMG without ECG in relation to (3) basal sEMG without ECG (R-ins/noise), (4) basal sEMG with ECG (R-ins/cardio) and (5) expiratory sEMG without ECG (R-ins/exp). Spectral power, R-ins/noise and R-ins/cardio increased with the inspiratory load. Significantly higher values (p < 0.05) of R-ins/cardio and significantly higher median frequencies were obtained for CREs. R-ins/noise and R-ins/exp were higher for the bipolar configuration only in diaphragm sEMG recordings, whereas no significant differences were found in the sternocleidomastoid recordings. Our results suggest that the evaluation of respiratory muscle activity by means of sEMG can benefit from the remarkably reduced influence of cardiac activity, the enhanced detection of the shift in frequency content and the axial isotropy of CREs which facilitates its placement., This work was supported in part by the CERCA Program/Generalitat de Catalunya, in part by the Secretaria d'Universitats i Recerca de la Generalitat de Catalunya under Grant GRC 2017 SGR 01770, in part by the Spanish Grants RTI2018-098472-B-I00, RTI2018-094449-A-I00-AR (MCIU/AEI/FEDER, UE) and DPI2015-68397-R (MINECO/FEDER), and in part by the Biomedical Research Networking Centre in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN, Instituto de Salud Carlos III/FEDER). The first author was supported by the IFARHU-SENACYT Scholarship Program from the Panama Government under Grant 270-2012-273.

[EN] Organic electrochemical transistors (OECTs) have been recognized as a major emerging technology in the area of flexible electronics in the last decade. Although they have yet to be incorporated in common electronic fabrication technologies, they have considerably advanced as an emerging platform for biosensing applications. The paper provides a comprehensive and critical review of the most important advances in the field of OECT-based biosensors. A brief description of the device physics is given with the most important equations and a comparison has been made with the conventional MOSFET devices and characteristic equations. The use of OECTs as an emerging biosensing platform has been explored and their application as biomolecule, enzyme, bacteria, viruses, cells, nucleotide detectors as well as electrophysiological and wearable sensors has been reported. Furthermore, trends have been extracted and described in the paper in terms of fabrication technologies, electrode materials and most importantly, the semiconducting polymer. Additionally, future perspectives on the development and fabrication technologies of these devices have been further explored., This work was supported in part by the University of Cyprus Internal Funds, Advanced Researchers Article 102, the Research and Innovation Foundation of Cyprus, under Grant POST-DOC/0718/0163 and in part by the Spanish Government/FEDER for Funds (MINECO/FEDER) under Grant RTI2018-100910-BC43.

Contribution: An improved inverted lecturing (IIL) framework based on blending flipped lectures and hands-on experiments provides instructional benefits, compared to traditional teaching (TT) and inverted lecturing (IL), in an introductory course in digital systems. Background: IL has proven more effective than TT in improving student learning in engineering courses, but has mostly been used for theory sessions. The impact of combining inverted lectures and hands-on experiments on student learning has not still been thoroughly assessed in engineering courses. Intended Outcomes: Attendance, marks, and satisfaction should improve for students in IL-based theory lectures, compared with those receiving TT, and should improve still further for students receiving the IIL-based method. Workload both for student and instructor should not increase significantly. Application Design: The three methods were compared in six consecutive offerings of the course. In the first two, TT was used for both theory and laboratory classes; in the next two, IL was used for theory lectures; and in the final two offerings the IIL-based scheme was used. The instructor, intended learning outcomes (ILOs), course syllabus, and student grading scheme were constant over the six semesters. A total of 184 students with similar backgrounds participated. Findings: Students under the IL- and IIL-based frameworks were more engaged than those receiving TT, and were more satisfied with their learning process. The IIL-based learners achieved the deepest conceptual understanding. Finally, the IL- and IIL-based methods did not significantly increase workload for either the students or the instructor.

[EN] Recently, Half-Cycle Nyquist Subcarrier Modulation (HC-SCM) was proposed to achieve high spectral efficiency in intensity-modulator direct-detection optical links. This paper shows that the HC-SCM scheme has a high computational load and proposes the rational Oversampled Subcarrier Modulation (OVS-SCM) as a computational efficient alternative that, furthermore, improves the spectral efficiency. The presented experimental results show that our 256-QAM proposal allows to transmit below the hard-decision forward error correction, with a throughput of 17.8 Gb/s in a 2.5 GHz bandwidth, and a spectral efficiency of 7.2 b/s/Hz, through 20 km of single-mode optical fiber., This work was supported by the Spanish Ministerio de Economia y Competitividad and FEDER under the Grant TEC2015-70858-C2-2-R and Grant RTI2018-101658-B-I00.

[EN] Porous materials have demonstrated to be ideal candidates for the creation of optical sensors with very high sensitivities. This is due both to the possibility of infiltrating the target substances into them and to their notable surfaceto-volume ratio that provides a larger biosensing area. Among porous structures, polymeric nanofibers (NFs) layers fabricated by electrospinning have emerged as a very promising alternative for the creation of low-cost and easy-to-produce high performance optical sensors, for example, based on Fabry-Pérot (FP) interferometers. However, the sensing performance of these polymeric NFs sensors is limited by the low refractive index contrast between the NFs porous structure and the target medium when performing in-liquid sensing experiments, which determines a very low amplitude of the FP interference fringes appearing in the spectrum. This problem has been solved with the deposition of a thin metal layer ( 3 nm) over the NFs sensing layer. We have successfully used these metal-coated FP NFs sensors to perform several real-time and in-flow refractive index sensing experiments. From these sensing experiments, we have also determined that the sponge-like structure of the NFs layer suffers an expansion/compression process that is dependent of the viscosity of the analyzed sample, what thus gives the possibility to perform a simultaneous dual sensing of refractive index and viscosity of a fluid., This work was supported by the Spanish government through the project TEC2015-63838-C3-1-R-OPTONANOSENS and from the Basque government through the KK-2019/00101-mu 4FINDUSTRY.

[EN] Microgrids are moving towards large-scale smart distributed networks which demand an efficient and reliable communication infrastructure to manage, control and monitor energy resources. With regard to this, publisher/subscriber eventbased middleware has become relevant for large-scale distributed time applications because it allows decouple time and space between senders and receivers. Particularly the content publish/subscribe systems over structured peer-to-peer (P2P) networks has emerged to enhance scalability and dynamism of notification middleware systems. However, this type of systems use multicast routing schemes that still generate much network traffic and as a consequence an overload of the communication channel is produced. This results in inefficient network utilization and rapid depletion of network resources leading to unreliable operations, degradation of system performance and even instability of the microgrid. In this paper, a new content-based publish/subscribe notification middleware over structured P2P systems is proposed, such that smart microgrid communication requirements are met. This proposed system organizes the publications and subscriptions in a one dimensional representation using the Hilbert space filling curve. Through this representation, an innovative routing and matching algorithms are developed. Experimental results demonstrate that the proposed publisher/subscribe system significantly enhance efficiency of the system, network performance and the use of computational resources., This work is supported by the Spanish Ministry of Economy and Competitiveness (MINECO) and the European Regional Development Fund (ERDF) under Grant ENE2015- 64087- C2- 2 R. This work is supported by the Spanish Ministry of Economy and Competitiveness (MINECO) under BES- 2013- 064539.

[EN] This paper presents a low-complexity chase (LCC) decoder for Reed-Solomon (RS) codes, which uses a novel method for the selection of test vectors that is based on the analysis of the symbol error probabilities derived from simulations. Our results show that the same performance as the classical LCC is achieved with a lower number of test vectors. For example, the amount of test vectors is reduced by half and by 1/16 for the RS(255,239) and RS(255,129) codes, respectively. We provide an evidence that the proposed method is suitable for RS codes with different rates and Galois fields. In order to demonstrate that the proposed method results in a reduction of the complexity of the decoder, we also present a hardware architecture for an RS(255,239) decoder that uses 16 test vectors. This decoder achieves a coding gain of 0.56 dB at the frame error rate that is equal to 10(-6) compared with hard-decision decoding, which is higher than that of an eta = 5 LCC. The implementation results in ASIC show that a throughput of 3.6 Gb/s can be reached in a 90-nm process and 29.1XORs are required. The implementation results in Virtex-7 FPGA devices show that the decoder reaches 2.5 Gb/s and requires 5085 LUTs., This work was supported by the Spanish Ministerio de Economia y Competitividad and FEDER under Grant TEC2015-70858-C2-2-R. This paper was recommended by Associate Editor M. Boukadoum.

[EN] The use of singlets, cascaded singlets and doublets in coaxial substrate integrated waveguide (SIW) technology is proposed in this paper, with the aim of implementing low-loss filters with very compact size and highly-selective symmetric, asymmetric as well as dual-band responses. Singlets based on coaxial SIW resonator structures with source-load coupling are presented and studied. Then, different filter examples based on N cascaded singlets are designed, fabricated and measured at 7.5 GHz, with up to N transmission zeros (TZs) that can be easily located below and above the passband. Moreover, the application of doublets based on a dual-mode coaxial SIW resonator with source-load coupling for achieving extremely compact dual-band filters is presented, and two examples with different bandwidth configuration for each channel are designed, demonstrating the flexibility of the proposed coaxial SIW structure. The obtained experimental results of the different implemented filters show a good agreement with simulations, thus confirming the interesting potential application of these structures for the design of very compact devices with advanced filtering responses., This work was supported by the Ministerio de Economia, Industria y Competitividad, Spanish Government, under Project TEC2016-75934-C4-3-R.

[EN] This work presents a set of laboratory experiments that can be carried out by students who are taking digital design courses in engineering programs like Electronics, Communications Systems and Mechatronics. The purpose of these labs is to help students develop their skills and confidence designing arithmetic hardware blocks through solving of specific problems. In this aspect, this paper shows a method to be followed in the laboratory to design arithmetic blocks and implement them in microcontrollers and FPGAs. More specifically, the block design of a number's multiplicative inverse (1/root x), its square root (root x) and the square root of its inverse (1/root x) are presented. To complete these exercises, knowledges on Newton-Raphson algorithm, difference equations and digital design are required. Students of our institution completed the lab practices, and after analyzing the results from student surveys and classroom observations, we found out that completing these tasks significantly contributed to the students' training in the hardware design field., Este trabajo fue financiado por el Consejo Nacional de Ciencia y Tecnología (CONACYT) de México, mediante el proyecto de Ciencia Básica número 241272

[EN] Introduction: Spatial and temporal processing of intracardiac electrograms provides relevant information to support the arrhythmia ablation during electrophysio-logical studies. Current cardiac navigation systems (CNS) and electrocardiographic imaging (ECGI) build detailed 3-D electroanatomical maps (EAM), which represent the spatial anatomical distribution of bioelectrical features, such as activation time or voltage. Objective: We present a principled methodology for spectral analysis of both EAM geometry and bioelectrical feature in CNS or ECGI, including their spectral representation, cutoff frequency, or spatial sampling rate (SSR). Methods: Existing manifold harmonic techniques for spectral mesh analysis are adapted to account for a fourth dimension, corresponding to the EAM bioelectrical feature. Appropriate scaling is required to address different magnitudes and units. Results: With our approach, simulated and real EAM showed strong SSR dependence on both the arrhythmia mechanism and the cardiac anatomical shape. For instance, high frequencies increased significantly the SSR because of the "early-meets-late" in flutter EAM, compared with the sinus rhythm. Besides, higher frequency components were obtained for the left atrium (more complex anatomy) than for the right atrium in sinus rhythm. Conclusion: The proposed manifold harmonics methodology opens the field toward new signal processing tools for principled EAM spatiofeature analysis in CNS and ECGI, and to an improved knowledge on arrhythmia mechanisms., This work was partly supported by Spanish Research Projects TEC2013-48439-C4-1-R, TEC2016-75361-R, and TEC2016-75161-C2-1-4.

[EN] For the practical implementation of RF and microwave impedance matching networks, a widely employed solution¿alternative to the use of classical impedance transformers¿is based on tapered lines. This paper shows a simple method to design smooth tapers that take into account the dispersion of the line and the required design bandwidth simultaneously. A planar taper has been designed in microstrip technology with the same length of classical ones but improving their performances. A waveguide prototype has also been designed with similar performance to a commercial one but with one third of its length. Both tapered structures have been obtained through the optimization of very few parameters using the same design strategy. As a result, the reflection coefficient of the tapers can be optimally adapted to a given specific mask using the prescribed value of physical length. Experimental results for both tapers are included for the validation of the proposed topologies and the related design method., This work was supported by MINECO (Spanish Government) through R&D under Project TEC2016-75934-C4-1-R.

[EN] Stochastic low-density parity-check decoders (SLDPCs) have found favor recently both for correcting transmission errors as well as for improving the hardware efficiency. The main drawback of these decoders is that they require hundreds of time periods to decode each frame, but their chip area is smaller than that of their fixed-point counterparts, so they can achieve higher hardware efficiency and may consume less energy. In this paper, we propose a novel extrinsic information transfer chart technique for characterizing the iterative decoding convergence of all the sequences involved in the SLDPC. We have conceived a new model, which takes into consideration not only the sequences exchanged between the decoders but also the sequences generated inside the variable-node decoder (those which are stored in the edge memories). In this way, the model is able to predict the number of decoding iterations required for achieving iterative decoding convergence, as confirmed by own decoder simulations. The proposed technique offers new insights into the operation of SLDPCs, which will facilitate improved designs for the research community., Professor L. Hanzo would like to give thanks to the ERC for the financial support of this Advanced Fellow Grant.

[EN] This letter presents a technique for the introduction of transmission zeros (TZs) using half section matched terminations for implementing high selectivity filters in planar technology. The proposed technique does not require any cross coupling between nonadjacent resonators or multiple signal paths, and it can be easily incorporated on any planar filter using lumped, quasi-lumped, and/or distributed elements depending on the desired response. Two different bandpass filter topologies are employed for applying the proposed technique. Both prototypes are designed, manufactured, and measured. The measured results show that the TZs can be independently located very close to the passband edges, without degrading the original filter response., This work was supported by the Spanish Ministry of Economy, Industry and Competitiveness under Grant TEC2013-48036-C3-3-R and Grant TEC2016-75934-C4-1-R.

Non-binary LDPC codes outperform its binary counterparts in different scenarios. However, they require a considerable increase in complexity, especially in the check-node processor, for high-order Galois fields higher than GF(16). To overcome this drawback, we propose an approximation for the Trellis Min-Max algorithm which allows us to reduce the number of exchanged messages between check node and variable node compared to previous proposals from literature. On the other hand, we reduce the complexity in the check-node processor, keeping the parallel computation of messages. We implemented a layered scheduled decoder, based on this algorithm, in a 90nm CMOS technology for the (837,723) NB-LDPC code over GF(32) and the (1536,1344) over GF(64), achieving an area saving of 16% and 36% for the check-node and 10% and 12% for the whole decoder, respectively. The throughput is 1.07 Gbps and 1.26 Gbps, which outperforms the state-of-the-art of high-rate decoders with high GF order from literature., This work was supported in part by the Spanish Ministerio de Ciencia e Innovacion under Grant TEC2011-27916 and Grant TEC2012-38558-C02-02 and in part by Generalitat Valenciana under Grant GV/2014/011.

[EN] A procedure for improving the stopband response of planar bandpass filters is presented in this letter. The technique is based on the introduction of transmission zeros by using lumpedelement bisected-pi sections at the filter input/output. As an example, a 3¿pole 10% FBW bandpass filter with Chebyshev response centered at 1 GHz, based on strongly loaded combline microstrip resonators has been designed, manufactured and measured. The proposed solution can be used on any planar topology in order to improve the stopband performance with a negligible additional footprint., This work was supported in part by MINECO (Spanish Government) under project TEC2013-48036-C3-3-R and TEC2013-47037-C5-1-R.

[EN] This work presents a Positron Emission Tomography (PET) image analysis tool and its application to the study of rat brain glucose consumption (PETra comes from PET+rat). The described methodology has four steps: a preprocessing of PET images, a coregistration of these images with an atlas, a semiautomatic segmentation of the regions of interest in the rat brain and a 3D reconstruction of these regions to obtain the volumes of interest. Brain glucose uptake was quantified as Standardized Uptake Value (SUV). This tool was applied to nine Wistar rats, young (4-7 months) and old (22-24 months) groups, to study the effect of aging on brain glucose consumption and the difference between sexes. Results showed a lower glucose uptake in old rats than in young rats, regardless gender; while young female rats showed higher glucose consumption than young male rats, whereas these differences disappeared with aging. The developed tool allows the quantification of glucose in rat brain. Results show the accuracy of the tool to define ranges of variation in a population of young and old rats, showing a decrease in glucose consumption in aging.

This letter proposes a new compact filtering building block. It consists of two via holes embedded into a substrate integrated waveguide (SIW) cavity connected to capacitive metal patches at the top layer. This topology provides two coaxial modes performing a doublet filtering configuration. The proposed dualmode SIWcoaxial cavity is studied in detail and guidelines for the filter design are given. As will be shown, the proposed building block presents a high degree of design flexibility, which allows for the design of multiple kind of bandpass filter (BPF) responses, including both narrow- and wide-band BPFs along with transmission zero generation. As a verification, several filters are designed and implemented at 8 GHz., This work has been supported in part by MINECO (Spanish Government) under projects TEC2013-47037-C5-1-R and TEC2013-48036-C3-3-R, and by a "Juan de la Cierva" Research fellowship.

A microgrid can operate in island mode, isolated from the main grid during certain time intervals. When operated in island mode, the electronic converters of the microgrid must keep the voltage and frequency of the microgrid inside the desired range. The converters of a microgrid can be classified into three groups: 1) grid-feeding; 2) grid-supporting; and 3) grid-forming power converters. The grid-forming converters operate as a voltage source, and require an external synchronization signal provided by the microgrid central controller. Both the noise and the delay in the synchronization signals received by the grid-forming converters are critical issues, which deteriorate the quality of the microgrid voltage and may overload those converters. The synchronization signals must be robust and suitable for operating in noisy environments. In this paper, the synchronization signal is frequency-modulated to be transmitted, being robust against noise. The transmission is done through an industrial RS-485 line with a low delay. The demodulation is performed with a low computational load by the control processors of the grid-forming power converters., This work was supported in part by the Spanish Ministry of Economy and Competitiveness under Grant ENE2015-64087-C2-2-R, and in part by the European Regional Development Fund.

The effect on the buried magnetic loop response when vehicles pass over them is determined. A program is designed and used to obtain the magnetic profile of several vehicles when passing over a rectangular loop. The theoretical values are compared with the actual measurements and the accuracy of the model is checked. Besides, a new oscillator circuit, a component of which is the loop, is presented. Induction change is used to cause the oscillation frequency modification of circuit, which in turn is one of the changes used for vehicles detection, identification and classification., This work was supported in part by the City Council of Valencia in Spain and in part by Company ETRA I+D S.A.

A multiple-vote symbol-flipping (MV-SF) decoding algorithm for nonbinary low-density parity-check (NB-LDPC) codes is proposed in this paper. Our algorithm improves the generalized bit-flipping algorithm (GBFDA) by considering the multiplicity of the candidates at the check-node output, to perform a more accurate symbol-flipping decision at the variable node update. The MV-SF algorithm greatly improves the frame error rate performance of GBFDA and approaches the performance of the best state-of-the-art decoders [extended min-sum and min-max (Min-Max)] with lower complexity. For a (N = 837, K = 723) NB-LDPC code over GF(32), the decoder derived from the proposed algorithm can reach a throughput higher than 500 Mb/s and a coding gain of 0.44 dB compared with the most efficient GBFDA architecture with only twice the silicon area. Our architecture has 27% efficiency gain compared with the best Min-Max architecture found in the literature, with a performance loss of just 0.21 dB at frame error rate 10(-4), This work was supported in part by the Spanish Ministerio de Ciencia e Innovacion under Grant TEC2011-27916, in part by the Universitat Politecnica de Valencia under Grant SP20120625, and in part by the Institut Universitaire de France. The work of F. Garcia-Herrero was supported by the Spanish Government, Ministerio de Educacion, under Grant AP2010-5178.

This paper proposes a low-complexity min-sum algorithm for decoding low-density parity-check codes. It is an improved version of the single-minimum algorithm where the two-minimum calculation is replaced by one minimum calculation and a second minimum emulation. In the proposed one, variable correction factors that depend on the iteration number are introduced and the second minimum emulation is simplified, reducing by this way the decoder complexity. This proposal improves the performance of the single-minimum algorithm, approaching to the normalized min-sum performance in the water-fall region. Also, the error-floor region is analyzed for the code of the IEEE 802.3an standard showing that the trapping sets are decoded due to a slow down of the convergence of the algorithm. An error-floor free operation below BER = 10(-15) is shown for this code by means of a field-programmable gate array (FPGA)-based hardware emulator. A layered decoder is implemented in a 90-nm CMOS technology achieving 12.8 Gbps with an area of 3.84 mm(2), This work was supported by the Spanish Ministerio de Economia y Competitividad under Grants TEC2011-27916 and TEC2012-38558-C02-02. This paper was recommended by Associate Editor J. Ma.

A simplified version of the enhanced serial generalized bit-flipping algorithm is proposed in this brief. This new algorithm reduces the quantity of information that is stored with a negligible performance loss of 0.05 dB compared with previous proposals. In addition, the algorithm allows us not only to save memory, but also to reduce the number of arithmetic resources needed. In addition, a new initialization of the algorithm avoids using techniques to control data growth without any performance degradation, reduces routing, increasing the maximum frequency achievable, and saves logic. The decoder derived from the simplified algorithm requires almost half the area of previous architectures, with a throughput of 716 Mbps on a 90-nm CMOS process for the (837, 723) nonbinary code over GF(32) at ten iterations., Manuscript received December 26, 2012; revised May 21, 2013; accepted July 25, 2013. Date of publication August 21, 2013; date of current version May 20, 2014. This work was supported in part by the Spanish Ministerio de Ciencia e Innovacion under Grant TEC2011-27916 and in part by the Universidad Politecnica de Valencia under Grant PAID-06-2012-SP20120625. The work of F. Garcia-Herrero was supported by the Spanish Ministerio de Educacion under Grant AP2010-5178.

In this letter, a new algorithm to decode non-binary LDPC (NB-LDPC) codes is proposed. This algorithm is inspired from very low complexity decoders that have been proposed recently, in which only syndrome computations at the check node update are used, while performing symbol-flipping based update at the variable node. Usually, the low complexity decoders based on symbol flipping suffer from a non-negligible performance degradation compared to soft-decision NB-LDPC decoders. Our improved decoder makes use of a list of syndrome computations instead of a single one based on hard-decision, and builds soft information at the variable node input by assigning votes weighted by different amplitudes. Simulations show that using multiple votes with multiple weights yields better performance, while still maintaining the low complexity feature., This research was supported by the Institut Universitaire de France, the Spanish Ministerio de Ciencia e Innovacion, under Grant No. TEC2011-27916, and the Spanish Ministerio de Educacion (Grant No.AP2010-5178)

Recently there has been a significant proliferation in the use of forecasting techniques, mainly due to the increased availability and power of computation systems and, in particular, to the usage of personal computers. This is also true for power network systems, where energy demand forecasting has been an important field in order to allow generation planning and adaptation. Apart from the quantitative progression, there has also been a change in the type of models proposed and used. In the '70s, the usage of non-linear techniques was generally not popular among scientists and engineers. However, in the last two decades they have become very important techniques in solving complex problems which would be very difficult to tackle otherwise. With the recent emergence of smart grids, new environments have appeared capable of integrating demand, generation, and storage. These employ intelligent and adaptive elements that require more advanced techniques for accurate and precise demand and generation forecasting in order to work optimally. This review discusses the most relevant studies on electric demand prediction over the last 40 years, and presents the different models used as well as the future trends. Additionally, it analyzes the latest studies on demand forecasting in the future environments that emerge from the usage of smart grids.

The design of substrate integrated waveguide (SIW) diplexers, based on combline triplet sections with transmission zeros (TZs) placed below and above the passband, is presented. In order to control the location of the TZs, positive and negative couplings are conveniently provided. A highly compact implementation based on circular substrate integrated coaxial resonators is proposed. An X band diplexer with channel center frequencies at 9.5 and 10.5 GHz and absolute bandwidths of 400 MHz is designed. The structure shows important advantages in terms of size reduction, while keeping good insertion losses as well as high rejection and isolation levels., This work was supported by MINECO (Spanish Government) under projects TEC2103-47037-C5-1-R and TEC2013-48036-C3-3-R.

Grid connected voltage source inverters may be controlled in the stationary reference frame by means of the infinite impulse response (IIR) P+Resonat regulator. This regulator is able to correctly track fixed frequency sinusoidal references, but does not perform well if the frequency of the electric grid voltage is varied. In order to avoid the lack of precision to track variable frequency sinusoidal references, an adaptive IIR filter structure is proposed which offers good tracking properties even if the frequency of the grid voltage varies. This filter adapts its coefficients in real time and is inherently stable no matter the adaptation process, thus overcoming one of the most important drawbacks of the IIR filter structure. Furthermore, this structure is perfectly suited to be programmed in fixed point digital signal processors (DSPs) because of some important numeric properties, i.e., it has a high mapping precision and a low round-off accumulation, and it avoids quantization limit cycle oscillations. The proposed adaptive controller has been tested by means of the TI TMS320F2812 DSP. The obtained experimental results show up that this controller allows the correct tracking of a sinusoidal reference, even if this reference is time variant., This work was supported by the Spanish Ministry of Science and Innovation under Grant ENE2012-37667-C02-01. Paper no. TII-11-622.

This paper presents the analysis, design, and experimentation results of a photovoltaic energy management system with battery backup. The proposed system is capable of both grid-connected and islanded operations. The main advantage of the proposed system is that, in grid-connected mode, the inverter works as a current source in phase with the grid voltage, injecting power to the grid and controlling the dc-link voltage. The dc/dc converter manages the battery charge. In islanded mode, the inverter control is reconfigured to work as a voltage source using droop schemes. The dc/dc converter controls the dc-link voltage to enable the maximum power point tracking reference to be followed. An operation protocol is proposed to ensure the quality of the energy supply and minimize energy loss. A battery bank is connected to the dc link as energy storage for islanded operation mode. The aim of this paper is to show that the proposed system performs correctly, without dangerous transients for the inverter or the loads. Simulation and experimental results on a 3-kW prototype show the feasibility of the proposed control strategy., This work was supported by the Spanish Ministry of Science and Innovation under Grant ENE2009-13998-C02-02. The translation of this paper was funded by the Universitat Politecnica de Valencia, Spain.

Food companies worldwide must constantly engage in product development to stay competitive, cover existing markets, explore new markets, and meet key consumer requirements. This ongoing development places high demands on achieving quality at all levels, particularly in terms of food safety, integrity, quality, nutrition, and other health effects. Food product research is required to convert the initial product idea into a formulation for upscaling production with ensured significant results. Sensory evaluation is an effective component of the whole process. It is especially important in the last step in the development of new products to ensure product acceptance. In that stage, measurements of product aroma play an important role in ensuring that consumer expectations are satisfied. To this end, the electronic nose (e-nose) can be a useful tool to achieve this purpose. The e-nose is a combination of various sensors used to detect gases by generating signals for an analysis system. Our research group has investigated the scent factor in some foodstuff and attempted to develop e-noses based on low-cost technology and compact size. In this paper, we present a summary of our research to date on applications of the e-nose in the food industry.

Early detection of brain metastases increases survival in patients with cancer, since image-guided radiosurgery is the most widely used treatment. As support for the qualitative diagnosis made by radiologists, Computer Assisted Diagnosis provides a quantitative and reproducible analysis. This article reviews the methods for an automatic detection of brain metastases in contrast-enhanced T1-weighted magnetic resonance imaging. Model-based methods detect metastases due to their high degree of similarity with models representing their morphology, mainly templates. On the other hand, methods based on brain symmetry and intensity search intensity differences between both brain hemispheres with respect to the symmetry axis. Model-based methods are more commonly used because they allow the detection of metastases of a wider range of measures.

This paper presents a novel algorithm based on trellis min-max for decoding non-binary low-density parity-check (NB-LDPC) codes. This decoder reduces the number of messages exchanged between check node and variable node processors, which decreases the storage resources and the wiring congestion and, thus, increases the throughput of the decoder. Our frame error rate performance simulations show that the proposed algorithm has a negligible performance loss for high-rate codes with GF(16) and GF(32), and a performance loss smaller than 0.07 dB for high-rate codes over GF(64). In addition, a layered decoder architecture is presented and implemented on a 90-nm CMOS process for the following high-rate NB-LDPC codes: (2304, 2048) over GF(16), (837, 726) over GF(32), and (1536, 1344) over GF(64). In all cases, the achieved throughput is higher than 1 Gb/s., This work was supported in part by the Spanish Ministerio de Ciencia e Innovacion under Grant TEC2011-27916 and Grant TEC2012-38558-C02-02, and in part by Generalitat Valenciana under Grant GV/2014/011.

Automatic ranging and self-positioning is a very desirable property in wireless acoustic sensor networks, where nodes have at least one microphone and one loudspeaker. However, due to environmental noise, interference, and multipath effects, audio-based ranging is a challenging task. This paper presents a fast ranging and positioning strategy that makes use of the correlation properties of pseudonoise sequences for estimating simultaneously relative time-of-arrivals from multiple acoustic nodes. To this end, a proper test signal design adapted to the acoustic node transducers is proposed. In addition, a novel self-interference reduction method and a peak matching algorithm are introduced, allowing for increased accuracy in indoor environments. Synchronization issues are removed by following a BeepBeep strategy, providing range estimates that are converted to absolute node positions by means of multidimensional scaling. The proposed approach is evaluated both with simulated and real experiments under different acoustical conditions. The results using a real network of smartphones and laptops confirm the validity of the proposed approach, reaching an average ranging accuracy below 1 cm., The associate editor coordinating the review of this manuscript and approving it for publication was Prof. Tsung-Hui Chang. This work was supported by the Spanish Ministry of Economy and Competitiveness under Grant TIN2015-70202-P and Grant TEC2012-37945-C02-02, and in part by the FEDER funds.

In this brief, we present a hardware-based Gaussian noise generator (GNG) with low hardware cost, high generation rate, and high Gaussian tail accuracy. The proposed generator is based on a piecewise polynomial approximation of the inverse cumulative distribution function (ICDF). We propose to avoid the area-demanding barrel-shifter of the ICDF approximation by means of creating a new uniform random sequence from the uniform random number generator output. The GNG architecture has been implemented in field-programmable gate array devices, and the implementation results are compared with other published designs, achieving a higher deviation with fewer hardware resources. Our GNG generates 242 Msps of random noise and achieves a tail of 13.1 sigma with 442 slices, two multipliers, and two Block-RAM of a Virtex-II device. The generator output successfully passed commonly used statistical tests. © 2012 IEEE., This work was supported by Fondo Europeo de Desarrollo Regional and the Spanish Ministerio de Ciencia e Innovacion under Grant TEC2008-06787 and Grant TEC2011-27916. This brief was recommended by Associate Editor Y. Ha.

[EN] The use of antiarrhythmic drugs is common to treat heart rhythm disorders. Computational modeling and simulation are promising tools that could be used to investigate the effects of specific drugs on cardiac electrophysiology. In this paper, we study the multiscale effects of dofetilide, a drug that blocks IKr, from cellular to organ level paying special attention to its effect on heart structures, in particular the specialized cardiac conduction system (CCS). We include a model of the CCS in a patient-specific anatomical ventricular model and study the drug effects in simulations with and without a CCS. Results confirmed the expected effects of dofetilide at cellular level, increasing the action potential duration, and at organ level, prolonging the QT segment. Notable differences are shown between models with and without the CCS on action potential duration distributions. These techniques show the importance of heart heterogeneity and the global effects of the interaction of drugs with cardiac structures. © 2006 IEEE., This work was supported in part by the Ministry of Science and Innovation, TEC-2008-02090 (FPI grant BES-2009-016071), in part by the Programa de Apoyo a la Investigacion y Desarrollo (PAID-06-09-2843) de la Universitat Politecnica de Valencia, and in part by the Direccion General de Politica Cientifica de la Generalitat Valenciana (GV/2010/078). Asterisk indicates corresponding author.

This paper presents an adaptive robust predictive current control (RPCC) for grid-connected three-phase inverters that exhibit zero steady-state current error. The error correction is achieved by means of an adaptive strategy that works in parallel with the deadbeat algorithm, therefore preserving the typical fast response of the predictive law. The resulting control adapts to any particular L or LCL filter by estimation of the resistive part of the filter. As a variety of the RPCC class of control, it offers the best tradeoff between robustness and speed. © 2009 IEEE.

This work presents the software implementation of a tissue engineering image analysis tool through the study of several biomaterials by means of different microscopy techniques (optical, scanning electron, and atomic force microscopy). With this tool, different quantitative information has been extracted from the microscopy image analysis of these biomaterials, as the number of objects, their mean size and the area they cover. Morphological characteristics, as the roundness or the porosity have been also obtained. All these quantitative information has permitted an statistical analysis over the obtained results. © 2011 IEEE.

The appearance of model-driven engineering (MDE) has invigorated research on domain-specific languages (DSLs) and automatic code generation. MDE uses models to build software, thereby displacing source code as the development process's main feature. DSLs provide easy, intuitive descriptions of the system using graphic models. In this new context, DSLs facilitate work in the first design stages. In addition, MDE helps reduce DSL development costs. It therefore represents a synergistic union that can significantly improve software development. The Spanish Interministerial Commission of Science and Technology’s MEDWSA (a conceptual and technological framework for the development of reactive software systems) project (TIN2006-15175-C05-02) and the Technical University of Cartagena partially supported this work.

Passive current sharing in multiphase converters, where resistive losses are not dominant, is a quite complex goal. In this paper, an averaged model of an active clamp buck converter was obtained. It has been checked that this topology presents high output impedance. This property is used like a lossless passive equalization. The principle of operation, theoretical analysis, simulation, and experimental results are presented, taken from a three-stage laboratory prototype. This work was supported by the Ministry of Education and Science, Spain, under Research Project COMPAS (Code DPI2007-64135).

User requirements for the performance of GlobaL Navigation Satellite System (GNSS)-based road applications have been significantly increasing in recent years. Safety systems based on vehicle localization, electronic fee-collection systems, and traveler information services are just a few examples of interesting applications requiring onboard equipment (OBE) capable of offering a high available accurate position, even in unfriendly environments with low satellite visibility such as built-up areas or tunnels and at low cost. In addition to that, users and service providers demand from the OBEs not only accurate continuous positioning but integrity information of the reliability of this position as well. Specifically, in life-critical applications, high-integrity monitored positioning is absolutely required. This paper presents a solution based on the fusion of GNSS and inertial sensors (a Global Positioning System/Satellite-Based Augmentation System/Inertial Navigation System integrated system) running an extended Kalman filter combined with an interactive multimodel method (IMM-EKF). The solution developed in this paper supplies continuous positioning in marketable conditions and a meaningful trust level of the given solution. A set of tests performed in controlled and real scenarios proves the suitability of the proposed IMM-EKF implementation as compared with lowcost GNSS-based solutions, dead reckoning systems, single-model EKF, and other filtering approaches of the current literature. This work was supported in part by the Spanish Ministerio de Fomento under Grant FOM/3929/2005 and by the Galileo Joint Undertaking (GJU) under Grant GIROADS 332599. The Associate Editor for this paper was Y. Wang.

In this paper, combline substrate integrated waveguide (SIW) filters using electric and magnetic couplings are thoroughly studied. Thus, a negative coupling scheme consisting on an open-ended coplanar probe is proposed and analyzed in detail. Several in-line 3-pole filters at C-band are designed, manufactured and measured showing how the presented approach can be used for implementing direct couplings while enabling an important size reduction and improved spurious-free band compared to conventional magnetic irises. A fully-packaged quasi-elliptic 4-pole filter is also designed at 5.75 GHz showing how the negative coupling structure can be used for introducing transmission zeros by means of cross-couplings between non-adjacent resonators. Finally, average and peak power handling capabilities of these filters have been also analyzed from a multiphysics point of view. Measured results validate the theoretical predictions confirming that combline SIW filters can handle significant levels of continuous and peak power, providing at the same time easy integration, compact size and advanced filtering responses., This work was supported in part by MINECO (Spanish Government) under projects TEC2013-47037-C5-1-R and TEC2013-48036-C3-3-R. This paper is an expanded version from the IEEE MTT-S International Microwave Symposium, Phoenix, AZ, USA, May 17-22, 2015.

In this brief, a method for compressing the messages between check nodes and variable nodes is proposed. This method is named compressed nonbinary message passing (CNBMP). CNBMP reduces the number of messages exchanged between one check node and the connected variable nodes from d(c) x q to 5 x q, and its application has a high impact on the performance of the decoder: the storage and routing areas are reduced and the throughput is increased. Unlike other methods, CNBMP does not introduce any approximation or modification in the information and the processed operations are exactly the same as those of the original decoders; hence, no performance degradation is introduced. To demonstrate its advantages, an architecture applying this CNBMP to the Trellis Min-Max algorithm was derived showing that most of the storage resources were also reduced from dc x q to 5 x q. This architecture was implemented for a (837 726) nonbinary low-density parity-check code using a 90-nm CMOS technology reaching a throughput of 981 Mb/s with an area of 10.67 mm(2), which is 3.9 more efficient than the best solution found in the literature., This work was supported by the Spanish Ministerio de Ciencia e Innovacion under Grant TEC2011-27916. The work of F. Garcia-Herrero was supported by the Spanish Ministerio de Educacion through Formacion de Profesorado Universitario (FPU) under Grant AP2010-5178.

Due to the growing interest using underwater acoustic networks, there are more and more research papers about underwater communications. These papers are mainly focused on deployments and studies about the constraints of the underwater medium. The underwater acoustic channel is highly variable and the signal transmission can change according to environmental factors such as the temperature, pressure or salinity of the water. For this reason, it is important to know how these devices are developed and the maximum distance and data transfer rates they can achieve. To this end, this paper presents an exhaustive study of existing underwater acoustic modems where their main features are highlighted. We also review the main features of their hardware. All presented proposals in the research literature are compared with commercial underwater acoustic modems. Finally, we analyze different programs and improvements of existing network simulators that are often used to simulate and estimate the behavior of underwater networks., This work was supported by the Ministerio de Ciencia e Innovacion through the Plan Nacional de I+D+i 2008-2011 within the Subprograma de Proyectos de Investigacion Fundamental under Project TEC2011-27516. The associate editor coordinating the review of this paper and approving it for publication was Dr. Lei Shu. (Corresponding author: Jaime Lloret.)

In this paper we propose a method for obtaining an analytic model of the battery State-of-Charge (SoC) in wireless sensor nodes. The objective is to find simple models that can be used to estimate accurately the real battery state and consequently the node lifetime. Running the model in the network nodes, we can provide the motes with the required information to implement applications that can be considered as battery-aware. The proposed methodology reduces the computational complexity of the model avoiding complicated electrochemical simulations and treating the battery as an unknown system with an output that can be predicted using simple mathematical models. At a first stage, during a setup period, the method starts with the measurement of several battery parameters under different environmental and operational conditions. After that, the method uses the previous collected data for building mathematical models, considering the linear regression or the multilayer perceptron as the most appropriated. Finally, the models are validated experimentally with new measures. Results show the suitability of the method that produces accurate and simple models, capable of being implemented even in low-cost and very constrained real motes, This work was supported by the I+D+i Program, Generalitat Valenciana, through the Research and Development under Project GV05/043 and in part by the Vicerrectorado of Investigation, Development and Innovation, Universidad Politecnica de Valencia, under Grant PAID-06-06-002-61.