Analysis of Joint Source Channel LDPC Coding for Correlated Sources Transmission over Noisy Channels

In this paper, a Joint Source Channel coding scheme based on LDPC codes is investigated. We consider two concatenated LDPC codes, one allows to compress a correlated source and the second to protect it against channel degradations. The original information can be reconstructed at the receiver by a joint decoder, where the source decoder and the channel decoder run in parallel by transferring extrinsic information. We investigate the performance of the JSC LDPC code in terms of Bit-Error Rate (BER) in the case of transmission over an Additive White Gaussian Noise (AWGN) channel, and for different source and channel rate parameters. We emphasize how JSC LDPC presents a performance tradeoff depending on the channel state and on the source correlation. We show that, the JSC LDPC is an efficient solution for a relatively low Signal-to-Noise Ratio (SNR) channel, especially with highly correlated sources. Finally, a source-channel rate optimization has to be applied to guarantee the best JSC LDPC system performance for a given channel

Hydrogen enriched syngas production via gasification of biofuels pellets/powders blended from olive mill solid wastes and pine sawdust under different water steam/nitrogen atmospheres

International audienceIn this paper we focused on the gasification of biomass charcoal using a macro TG under the CO2 gasifier agent mixed with nitrogen at different mass molar fractions; 40%, 70% and 100% respectively. Moreover, the gasification tests were conducted at different isothermal temperatures; 750°C, 800°C, and 900°C respectively. For this purpose, two densified residues were selected; the exhausted olive mill solid wastes (EOMSW) and the pine sawdust (PS). Then, four different samples were prepared from these residues when investigating the impregnated and the non-impregnated samples using the olive mill waste water (OMWW) as by-product for the impregnation process. A comparison between obtained results during this current study and those obtained during our latest study when using steam as gasifier agent was carried out. We observe that the mass loss profiles meet the usual lingo-cellulosic gasification behaviours. Moreover, the increase of the isothermal temperatures or of the CO2 percentage affects positively the conversion, the gasification rate and the char reactivity. It is worth noting that the CO2 agent acts differently by comparison to the steam. Indeed, the gasification process using steam is found to be faster and more reactive

Successful Treatment of a Case of Crescentic Glomerulonephritis in a Patient with Primary Peritoneal Carcinoma: A case report

Crescentic glomerulonephritis (CGN) has been associated with several solid tumor malignancies. Only a few cases of nephropathy have been reported in association with tubo-ovarian/peritoneal malignancies. We describe a case of 55 years old female who developed combined immune complex-mediated glomerulonephritis and pauci-immune necrotizing crescentic vasculitis simultaneously with the diagnosis of tubo-ovarian/peritoneal cancer. The baseline estimated glomerular filtration rate (eGFR) was 13 ml/min. The patient received two doses of Rituximab and three doses of pulse corticosteroids, leading to significant improvement in renal function and the disappearance of her proteinuria. The eGFR improved to >60ml/min, and her proteinuria gradually resolved after 10 weeks of treatment. She was in a position to be given a combination chemotherapy treatment for tubo-ovarian/peritoneal cancer because of normalization of her CA-125 after three months of therapy. Keywords: tubo-ovarian/peritoneal cancer, Glomerulonephritis, Vasculitis, Chemotherapy

Investigation of Dealumination in Phosphate-Based Geopolymer Formation Process: Factor Screening and Optimization

In this study, phosphate-based geopolymers obtained from two aluminosilicate precursors with different mineralogical compositions were investigated. The used experimental methods were X-ray fluorescence, X-ray diffraction, atomic absorption measurements and experimental designs. Nine factors influencing the dealumination process during geopolymer formation were screened based on a Plackett–Burman design. The results show that the control factors are the P/Al molar ratio, curing temperature and curing time. These significant parameters were selected for further optimization using a central composite design. It was found that regardless of the used P/Al molar ratio, curing temperature and curing time increases generate an increase in the response. However, the P/Al molar ratio variation strongly affects Al removal only at low curing temperatures (between 22 and 50 °C) and with short curing times (between 0.2 and 3 h). The curing time parameter is the most significant factor. In addition, the same percentage of liberated Al can be achieved either by increasing the curing temperature in the earliest steps of geopolymer formation or by prolonging the curing time, even at low curing temperatures. Finally, the optimal conditions allowing maximum aluminum release are P/Al molar ratio = 2.0, curing temperature ≈ 70 °C and curing time = 4.76 h

Study of Carbonated Clay-Based Phosphate Geopolymer: Effect of Calcite and Calcination Temperature

This study aims to use natural carbonated Tunisian clay as an aluminosilicate precursor for the elaboration of phosphate-based geopolymers, which yields to the valorization of this common material in Tunisia. In addition, the presence of calcium carbonate in this clay allows the investigation of this associated mineral’s effect on the properties of geopolymeric materials. To achieve these purposes, several experimental techniques were used, namely fluorescence (FX), particle size analysis, thermogravimetric analysis (TGA), differential thermal analysis (DTA), dilatometric analysis, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The mechanical strength and the open porosity of the obtained geopolymeric samples were tested by the compression test and the standard test method for water absorption, respectively. The findings of this work show that the used Tunisian clay can present an attractive aluminosilicate precursor for the synthesis of phosphate-based geopolymers. It also shows that the chosen calcination temperature of the raw clay considerably modifies the reactivity of minerals during geopolymerization and, consequently, strongly affects the properties and structure of the geopolymeric samples. These effects were attributed essentially to the formation of new calcium crystalline phases in the obtained geopolymeric samples. In fact, the anorthite (CaAl2Si2O8) phase appears in all the samples but in greater abundance in those obtained from the clay calcined at 550 °C, and the brushite phase (CaHPO4·2H2O) appears only in the samples obtained from the clay calcined at 950 °C. All these new crystalline phases are strongly dependent on the state of the calcite present in the calcined clay

Investigation of Dealumination in Phosphate-Based Geopolymer Formation Process: Factor Screening and Optimization

In this study, phosphate-based geopolymers obtained from two aluminosilicate precursors with different mineralogical compositions were investigated. The used experimental methods were X-ray fluorescence, X-ray diffraction, atomic absorption measurements and experimental designs. Nine factors influencing the dealumination process during geopolymer formation were screened based on a Plackett–Burman design. The results show that the control factors are the P/Al molar ratio, curing temperature and curing time. These significant parameters were selected for further optimization using a central composite design. It was found that regardless of the used P/Al molar ratio, curing temperature and curing time increases generate an increase in the response. However, the P/Al molar ratio variation strongly affects Al removal only at low curing temperatures (between 22 and 50 °C) and with short curing times (between 0.2 and 3 h). The curing time parameter is the most significant factor. In addition, the same percentage of liberated Al can be achieved either by increasing the curing temperature in the earliest steps of geopolymer formation or by prolonging the curing time, even at low curing temperatures. Finally, the optimal conditions allowing maximum aluminum release are P/Al molar ratio = 2.0, curing temperature ≈ 70 °C and curing time = 4.76 h

Inter-node compression with LDPC joint source–channel coding for highly correlated sources

This paper investigates a new communication system where two nodes want to disseminate highly correlated contents to a single destination and can be applied for densely deployed wireless sensors networks applications. Motivated by their capacity-achieving performance and existing practical implementations, the proposed communication scheme is fully based on Low-Density Parity-Check (LDPC) codes for data compression and channel coding. More specifically, we consider a network of two correlated binary sources with two orthogonal communication phases. Data are encoded at the first source with an LDPC channel code and broadcast in the first phase. Based on the first source received data, the second source computes the correlation vector and applies a Joint Source–Channel (JSC) LDPC code, which output is communicated in the second phase. At the receiver, the whole network is mapped on a joint factor graph over which an iterative message-passing joint decoder is proposed. The aim of the joint decoder is to exploit the residual correlation between the sources for better estimation. Simulation results are investigated and compared to the theoretical limits and to an LDPC-based distributed coding system where no inter-node compression is applied

Efficient Multiple Concatenated Codes With Turbo-Like Decoding for UEP Wireless Transmission of Scalable JPEG 2000 Images

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Graph-based Joint Source Channel LDPC Decoding for Cooperative Communication with Error-corrupted Relay Observations

In this paper, we design a unified framework decoder for relay systems with iterative decoding. In the proposed scheme, the source node needs to transmit a correlated content to a destination with the help of a relay. Then, a distributed Joint Source Channel (JSC) Low-Density-Parity-Check (LDPC) encoding is applied at the source and the relay. The destination receives simultaneously the source compressed data from the source node, and the source/channel encoded data from the relay node. The cooperative network is mapped into a factor graph on which message passing iterative decoding is applied to estimate the source information. The JSC decoder takes into account the source-relay correlation which involves remarkable improvements even if errors occur at the source-relay link. The Bit Error-Rate (BER) system performance are investigated for different scenario, according to the relay position, and it is shown that the performance of the proposed cooperative scheme is typically about 0.5–1.0 dB better than an equivalent rate point-to-point system

LDPC-based Joint Source-Channel-Network Coding for the Multiple Access Relay Channel

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