Current Issue : April - June Volume : 2020 Issue Number : 2 Articles : 5 Articles
This paper demonstrates the outcomes of a feasibility study of a microwave imaging\nprocedure based on the Huygens principle for bone lesion detection. This study has been performed\nusing a dedicated phantom and validated through measurements in the frequency range of\n1â??3 GHz using one receiving and one transmitting antenna in free space. Specifically, a multilayered\nbone phantom, which is comprised of cortical bone and bone marrow layers, was fabricated.\nThe identification of the lesionâ??s presence in different bone layers was performed on images that were\nderived after processing through Huygensâ?? principle, the S21 signals measured inside an anechoic\nchamber in multi-bistatic fashion. The quantification of the obtained images was carried out by\nintroducing parameters such as the resolution and signal-to-clutter ratio (SCR). The impact of different\nfrequencies and bandwidths (in the 1â??3 GHz range) in lesion detection was investigated. The findings\nshowed that the frequency range of 1.5â??2.5 GHz offered the best resolution (1.1 cm) and SCR (2.22 on\na linear scale). Subtraction between S21 obtained using two slightly displaced transmitting positions\nwas employed to remove the artefacts; the best artefact removal was obtained when the spatial\ndisplacement was approximately of the same magnitude as the dimension of the lesion....
Because the textile industry wastewater is polluted with azo dyes, and in order\nto improve a process of wastewater remediation, the synthesized sample was\nevaluated in the photocatalysis of methylene blue and compared with commercial\nBi2O3 and anatase TiO2. Structures of bismuth oxide carbonate\n(Bi2O2CO3) were successfully synthesized using a solution at 0.03 M concentration\nof sodium bismuthate as precursor and ethylene glycol as dissolvent\nby solvothermal microwave-assisted approach. The semiconductor catalyst\nsamples were characterized by X-ray diffraction (XDR), scanning electron\nmicroscope (SEM) and Brunauer-Emmett-Teller analysis (BET). The application\nof the synthesized sample as catalyst, obtained a 68% of degradation.\nThis result is better than the commercial Bi2O3 and close to the anatase TiO2\ndegradation. This sample shows a variation in the formula (with the presence\nof carbonates) but also shows an acceptable degradation percentage according\nto TiO2 results, making Bi2O2CO3 a possible substitute of TiO2....
Compromising the performance and overhead is a crucial factor in designing cognitive\nradio networks (CRNs). One way to achieve this goal is to combine different fusion rules for a CRN\nwith multiple clusters of cognitive radios (CRs). This paper proposes a new adaptive combination\nalgorithm to balance between detection performance of a CRN and its reporting overhead through\ncombining different fusion rules over the CRN. Initially, the paper describes how to combine hard\ndecision, i.e., one-bit, and soften-hard decision, i.e., two-bit, fusion rules over a CRN with multiple\nclusters of CRs using different strategies. Simple combination and modified combination strategies,\nto consider a trade off between performance improvement and incurred reporting overhead, are\nconsidered. The paper adopts different threshold strategies to implement the proposed combinations.\nMoreover, the proposed algorithms are examined under the Rayleigh fading channel model and\nsimulated to investigate their detection performance and to compare their detection performance\nwith existing works. The simulation results show that the adaptive threshold strategy outperforms\nthe two proposed fixed threshold strategies and conventional fusion schemes....
The extraction of feather keratin biopolymer structures was studied using chicken feathers as a biomass material by the cold acid\nhydrolysis reaction; the recrystallization stage was performed using microwave or ultrasound irradiation, and conduction heating\nwas used as a reference. The microwave or ultrasound irradiation modified the texture and the morphology of the obtained\nmaterials, and they can be controlled depending on the time exposure and the power of the irradiation; this has high relevance in\nthe design of new materials to obtain nanostructures depending on the specific application. It was found that the microwave\nirradiation promotes the growth of the beta sheet over the alpha helix, and in the case of ultrasound irradiation, the growth is\nreversed being similar to the conduction heating; the porosity properties remain invariant, modifying the particle sizes depending\non the exposure time and power of irradiation. Therefore, the feather keratin biopolymer, when modified by microwaves and\nultrasound in the recrystallization stage, is a fibrous protein that has good mechanical, structural, morphological, and thermal\nproperties with potential applications such as development of biocompatible materials with cellular interaction and in catalysis as\ncatalytic and enzymatic support to mention just a few....
In this paper, a novel method for improving the estimation accuracy of the root mean\nsquare (RMS) delay spread from the magnitude of the Channel Transfer Function (CTF) is presented.\nWe utilize the level crossing rate metric in the frequency domain, which is based on scalar power\nmeasurement. The Savitzkyâ??Golay (S-G) filtering method is used to improve the fidelity of the\nchannel delay spread estimator. The presented concept is simple to implement and inexpensive. The\nproposed method is tested on the CTF magnitude data measured in the mmWave frequency band\nat low Signal-to-Noise Ratio (SNR)....
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