Tree-structure Expectation Propagation for Decoding LDPC codes over Binary Erasure Channels

Expectation Propagation is a generalization to Belief Propagation (BP) in two ways. First, it can be used with any exponential family distribution over the cliques in the graph. Second, it can impose additional constraints on the marginal distributions. We use this second property to impose pair-wise marginal distribution constraints in some check nodes of the LDPC Tanner graph. These additional constraints allow decoding the received codeword when the BP decoder gets stuck. In this paper, we first present the new decoding algorithm, whose complexity is identical to the BP decoder, and we then prove that it is able to decode codewords with a larger fraction of erasures, as the block size tends to infinity. The proposed algorithm can be also understood as a simplification of the Maxwell decoder, but without its computational complexity. We also illustrate that the new algorithm outperforms the BP decoder for finite block-siz

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A 10-way power divider based on a transducer and a radial junction operating in the circular TM01 mode

This work presents a 10-way Ku-band power divider using a mode transducer and a radial junction connected by an overmoded circular waveguide operating in the TM 01 mode. The circular symmetry of this mode has been exploited to obtain a power divider with the rectangular output ports radially distributed along the broad wall of the waveguides in H-plane configuration. This topology provides the same amplitude and phase for all the output ports. At the same time, a compact profile has been obtained, introducing a simple manufacturing for the two components of the divider. The first component is a mode transducer converting the TE 10 mode in the rectangular waveguide to the TM 01 mode in the circular waveguide. It is based on a novel topology providing a very high purity in the mode conversion with an attenuation for the other propagating mode, the TE 11c , higher than 60 dB. The second component is a 10-way radial junction that must work under the excitation of the TM 01 , whose special features, since this mode is not the fundamental one of the circular waveguide, will be highlighted. The final design has been validated with an experimental prototype, proposing a manufacturing based on four simple parts. This has been the key to obtain an experimental prototype with specifications in the state-of-the-art. The measured efficiency is better than 96.5% in a 16.7% relative frequency bandwidth from 11 GHz to 13 GHz, with return losses better than 25 dB in the common port. The measured difference between the signals at the output ports of the prototype is ±0.3 dB for the amplitudes and ±0.45° for the phases. A comparison of the obtained results with another divider based on the TE 01 mode shows the potential of the presented design for becoming an alternative to the more extended TE 01 -based power dividersThis work was supported by the Spanish Government through the Agencia Estatal de Investigacion, Fondo Europeo de Desarrollo Regional (AEI/FEDER, UE), under Grant TEC2016-76070-C3-1/2-R (ADDMATE

Development of a high-performance W-band duplexer for plasma diagnosis using a single band with dual circular polarization

Discrepancia entre la información que aparece en el artículo que indica que el copyright es de Elsevier, y la información que aparece en la página de la revista y en el Copyright Clearance Center que indican © 2019 The Authors. Published by Elsevier B.V., así como que el artículo está publicado en Open Access under a Creative Commons licenceThis work presents the design and experimental validation of a high performance, compact, waveguide duplexer operating from 91.5 to 96.5 GHz for its integration in diverse W-band microwave equipment as in plasma diagnosis applications. It uses a single frequency band, with two signals discriminated by different orthogonal circular polarization, which is generated by means of a septum orthomode transducer (OMT) polarizer. Moreover, this component is optimized loaded with the horn antenna for improving the overall system performance. It is explained how these two components are integrated into a very compact duplexer, designed using efficient numerical algorithms. The manufacturing process by mean of high precision milling, and including electrical discharge machining (EDM) has led to excellent performances. The measured return loss level and isolation are higher than 30 dB, and the insertion loss level is below 0.3 dB. Finally, the key parameter in this device, which reflects the symmetry in the manufacturing process, i.e., the axial ratio, is lower than 0.6 dB for both polarizations, an excellent result showing the potential of the presented designThis work was supported by the Spanish government under grants (ADDMATE) TEC2016-76070-C3-1/2-R (Agencia Estatal de Investigación, Spain, Fondo Europeo de Desarrollo Regional: AEI/FEDER/UE) and the program of Comunidad de Madrid, Spain S2013/ICE-3000 (SPADERADARCM

High-performance 16-way Ku-band radial power combiner based on the TE01-circular waveguide mode

This work presents a 16-way Ku-band radial power combiner for high power and high frequency applications, using the very low loss TE01 circular waveguide mode. The accomplished design shows an excellent performance: the experimental prototype has a return loss better than 30 dB, with a balance for the amplitudes of ( 0.15 dB) and ( 2.5 ) for the phases, in a 16.7% fractional bandwidth (2 GHz centered at 12 GHz). For obtaining these outstanding specifications, required, for instance, in highfrequency amplification or on plasma systems, a rigorous step-by-step procedure is presented. First, a high-purity mode transducer has been designed, from the TE10 mode in the rectangular waveguide to the TE01 mode in the circularwaveguide, with very high attenuation (>50 dB) for the other propagating and evanescent modes in the circularwaveguide. This transducer has been manufactured and measured in a back-to-back configuration, validating the design process. Second, an E-plane 16-way radial power divider has been designed, where the power is coupled from the 16 non-reduced-height radial standardwaveguides into the TE01 circularwaveguide mode, improving the insertion loss response and removing the usual tapered transformers of previous designs limiting the power handling. Finally, both the transducer and the divider have been assembled to make the final radial combiner. The prototype has been carefully manufactured, showing very good agreement between the measurements and the full-wave simulationsThe authors would like to thank INMEPRE S.A., the diligence in the manufacturing process. This work was supported by the Spanish government under Grant (ADDMATE) No. TEC2016-76070-C3-1/2-R (AEI/FEDER/UE) and the program of Comunidad de Madrid S2013/ICE-3000 (SPADERADARCM

Proizvodnja ksilitola iz hidrolizata eukaliptusova drva u jeftinim fermentacijskim podlogama

Several aspects concerning the bioconversion of xylose-containing hydrolysates (obtained from Eucalyptus wood) into xylitol were assessed. Debaryomyces hansenii yeast strains were adapted to fermentation media (obtained either by prehydrolysis or autohydrolysis- posthydrolysis of wood) supplemented with low-cost nutrients. Media containing up to 80 g/L xylose were efficiently fermented when the hydrolysates were detoxified by charcoal adsorption and supplemented with corn steep liquor.Ispitano je nekoliko mogućnosti biokonverzije ksiloze iz hidrolizata, dobivenih iz eukaliptusova drva, u ksilitol. Sojevi Debaryomyces hansenii adaptirani su na fermentacijske podloge (dobivene predhidrolizom ili autohidrolizom-posthidrolizom drva) uz jeftine hranjive dodatke. Fermentacija je bila uspješna u podlozi s 80 g/L ksiloze ako su hidrolizati bili detoksificirani adsorpcijom na aktivnom ugljenu uz dodatak kukuruznog ekstrakta (CSL)

Durability of CFRP-concrete bond in EBR and NSM systems under natural ageing for a period of three years

This work aims at assessing the durability of the CFRP-concrete bond exposed to different outdoor ageing environments for a period of three years.Carbon Fibre Reinforced Polymer (CFRP) composites have been shown to possess desirable properties for strengthening of reinforced concrete (RC) structures. The application of CFRP composites is mainly through Externally Bonded Reinforcement (EBR) or Near Surface-Mounted (NSM) techniques. The main objective of the present work was to provide insights on durability of bond between concrete and CFRP strips installed according to EBR and NSM techniques under the effects of ageing induced by outdoor conditions for a period of three years. Specimens were placed in four different outdoor environments (E3-E6) with ageing mainly induced by freeze-thaw attacks, carbonation, airborne chlorides, and elevated temperatures. Besides, the study included a reference environment (E1: ≈20 C / 55% RH) and another environment (E2: ≈20 C / water immersion). The bond test results for the specimens collected from the aforementioned outdoor environments showed a low degradation of the CFRP-concrete bond after three years.This work was carried out in scope of the project FRPLongDur POCI-01-0145-FEDER-016900 (FCT PTDC/ECM-EST/1282/2014) and Durable-FRP (PTDC/ECI-EGC/4609/2020) funded by national funds through the Foundation for Science and Technology (FCT) and co-financed by the European Fund of the Regional Development (FEDER) through the Operational Program for Competitiveness and Internationalization (POCI) and the Lisbon Regional Operational Program. This work was partly financed by FCT / MCTES through national funds (PIDDAC) under the R&D Unit Institute for Sustainability and Innovation in Structural Engineering (ISISE), under reference UIDB/04029/2020. This work is financed by national funds through FCT under grant agreement [DFA/BD/08403/2021] attributed to the first author

Static circularly symmetric perfect fluid solutions with an exterior BTZ metric

In this work we study static perfect fluid stars in 2+1 dimensions with an exterior BTZ spacetime. We found the general expression for the metric coefficients as a function of the density and pressure of the fluid. We found the conditions to have regularity at the origin throughout the analysis of a set of linearly independent invariants. We also obtain an exact solution of the Einstein equations, with the corresponding equation of state $p=p(\rho)$, which is regular at the origin.Comment: 10 pages, 1 figure, revtex 4. This paper is in honor of Alberto Garcia's sixtieth birthday. Accepted by Gen. Rel. Gra