Comparative study of indoor propagation model below and above 6 GHz for 5G wireless networks

It has been widely speculated that the performance of the next generation based wireless network should meet a transmission speed on the order of 1000 times more than the current cellular communication systems. The frequency bands above 6 GHz have received significant attention lately as a prospective band for next generation 5G systems. The propagation characteristics for 5G networks need to be fully understood for the 5G system design. This paper presents the channel propagation characteristics for a 5G system in line of sight (LOS) and non-LOS (NLOS) scenarios. The diffraction loss (DL) and frequency drop (FD) are investigated based on collected measurement data. Indoor measurement results obtained using a high-resolution channel sounder equipped with directional horn antennas at 3.5 GHz and 28 GHz as a comparative study of the two bands below and above 6 GHz. The parameters for path loss using different path loss models of single and multi-frequencies have been estimated. The excess delay, root mean square (RMS) delay spread and the power delay profile of received paths are analyzed. The results of the path loss models show that the path loss exponent (PLE) in this indoor environment is less than the free space path loss exponent for LOS scenario at both frequencies. Moreover, the PLE is not frequency dependent. The 3GPP path loss models for single and multi-frequency in LOS scenarios have good performance in terms of PLE that is as reliable as the physically-based models. Based on the proposed models, the diffraction loss at 28 GHz is approximately twice the diffraction loss at 3.5 GHz. The findings of the power delay profile and RMS delay spread indicate that these parameters are comparable for frequency bands below and above 6 GH

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Study of Temperature Fields and Heavy Metal Content in the Ash and Flue Gas Produced by the Combustion of Briquettes Coming from Paper and Cardboard Waste

The present study focused on the combustion of four types of briquettes made from paper and cardboard waste produced in Ouagadougou (Burkina Faso). Rotary and tubular kilns were used to study the combustion. The combustion mean temperatures, nitrogen, phosphorus and potassium (NPK) content in the ash and heavy metals content in the ash and the flue gas were analyzed. The combustion steady phase mean temperatures ranged from 950 °C to 750 °C were obtained according to briquettes type. The temperature favored the transfer of the heavy metal in the flue gas comparatively to the ash mainly for Hg, Cd and Pb. The Pb, Hg and Mn content in flue gas and the ash are higher than their content in the parent wood used for paper production due to the additive during the manufacturing process. The results showed a high content of heavy metal in flue gas produced by combustion of briquette made with office paper and in the ash for the briquette made of corrugated cardboard. Furthermore, the low heavy metal contain in the ash allow their use for soil amendment. However, ash contained a low proportion of NPK (less than 2%) which does not allow their usage as fertilizer alone

Combustion of vegetable oils under optimized conditions of atomization and granulometry in a modified fuel oil burner

The use of vegetable oils in burners represents an attractive alternative to the use of heating fuel oil (HFO) in heat production for domestic heating, small industrial units, drying of various products etc. In this work, a characterization of the combustion of cottonseed oil in a modified burner (type Riello 40N10) was performed to assess its ability to achieve proper combustion of vegetable oils in optimized conditions of atomization and granulometry. The quality of the combustion has been evaluated by the analysis of combustion products (CO, O-2, CO2, NO, NO2, SO2) and organic compounds including PAHs. Results show that the modifications made on the burner type 40N10 can achieve suitable spray conditions and give particle size within the recommended values for burners. In the case of Riello 40N10 burner, a fuel pressure of 28 bars is adequate and the minimum temperature required for oil preheating is 125 degrees C. When these conditions are achieved, cottonseed oil combustion leads to the emission of non-condensable gases and the organic compounds species as well as their concentration close to those of HFO. (C) 2013 Elsevier Ltd. All rights reserved

Experimental study of the co-gasification of wood and polyethylene in a two-stage gasifier

Co‐gasification of wood mixed with 20% (mass fraction) of polyethylene (PE) in a two‐stage NOTAR® fixed‐bed gasifier was studied in the present paper. The ratio of air flow injected in the pyrolyzer and air flow injected in the oxidation zone is called the air ratio (AR). The AR of 0.35, 0.43, and 0.49 were used for test runs. Mass and energy balances were established. The study showed the feasibility of co‐gasification of wood mixed with 20% of PE in the two‐stage gasifier. However, considerable quantity of residues rich in fixed carbon content (17% of the fuel mass and 69% of fixed carbon content) was produced due to a low reactivity of the charcoal obtained after the pyrolysis. AR increasing reduces the gas CO content due to overconsumption of char at the pyrolysis stage. H2 and CH4 highest values are obtained for the intermediate AR = 0.43 which maximized the LHV, energy efficiency, and carbon conversion with respectively 4674 kJ/Nm3, 64.35%, and 74.52%. Low reactivity and carbon content of the pyrolysis char likely lead to lower performance of co‐gasification of PE mixed with wood compared to wood gasification

Spectral Decompositions of Selfadjoint Relations in Pontryagin Spaces and Factorizations of Generalized Nevanlinna Functions

Selfadjoint relations in Pontryagin spaces do not possess a spectral family completely characterizing them in the way that selfadjoint relations in Hilbert spaces do. Here it is shown that a combination of a factorization of generalized Nevanlinna functions with the standard spectral family of selfadjoint relations in Hilbert spaces can function as a spectral family for selfadjoint relations in Pontryagin spaces. By this technique additive decompositions are established for generalized Nevanlinna functions and selfadjoint relations in Pontryagin spaces.© Springer Nature Switzerland AG 2020.fi=vertaisarvioitu|en=peerReviewed