ARTICLE | doi:10.20944/preprints201807.0184.v1
Subject: Chemistry And Materials Science, Paper, Wood And Textiles Keywords: density; gas permeability; thermal conductivity; densification
Online: 10 July 2018 (14:44:48 CEST)
This study investigated the evolution of density, gas permeability and thermal conductivity of sugar maple wood during the thermo-hygro-mechanical densification process. The results suggested that the oven-dry average density of densified samples was significantly higher than that of the control samples. However, the oven-dry density did not show a linear increase with the decrease of wood samples thickness. The radial intrinsic gas permeability of the control samples was 5 to 40 times higher than that of densified samples, which indicated that the void volume of wood was reduced notably after the densification process. The thermal conductivity increased by 0.5 - 1.5% per percent increase of moisture content for densified samples. The thermal conductivity of densified wood was lower than that of the control samples. The densification time had significant effects on the oven-dry density and gas permeability. Both the densification time and the moisture content had significant effects on thermal conductivity, but their interaction effect was not significant.
ARTICLE | doi:10.20944/preprints202104.0735.v1
Subject: Social Sciences, Anthropology Keywords: China; sustainable urbanization; densification; Suzhou; resettlement communities
Online: 28 April 2021 (09:58:20 CEST)
China is gradually and steadily shifting towards more sustainable development and the local governments are increasingly promoting sustainable spatial planning practices. The article debates the potential contradiction between the goal of a growing urban population and the reduced consumption of land planned by the sustainable development strategy of the city of Suzhou in the Yangtse River Delta region. The article explores the opportunities of densification of the residential urban environment as a possible solution for this contradiction. The article presents some Chinese examples of densification for land use efficiency and identifies in the resettlement communities of Suzhou some of the sites that can be efficiently redeveloped for their obsolescent conditions that do not correspond to the increasingly middle-class status of the residents in the region. The article investigates the different options of densification possible in the resettlement communities in the frame of the policies of urban renewal promoted in China in recent years for improving the urban quality of cities.
ARTICLE | doi:10.20944/preprints201812.0046.v1
Subject: Chemistry And Materials Science, Materials Science And Technology Keywords: online imaging analysis; polycrystalline zirconia; densification kinetics
Online: 4 December 2018 (08:40:33 CET)
Abstract: This work for the first time investigated the densification of multi-doping zirconia ceramic body with organic coating powders for solid electrolyte of solid oxide fuel cells via online imaging technology. The densification results show the initial stage plays a key role in the sintering. It can be found the covered organic PVA (polyvinyl acetate) supplies a potential kinetics to the initial densification during sintering. As a result, a kinetic function of densification in the initial stage was suggested. Furthermore, a novel sintering model with six sub-stages is developed for polycrystalline zirconia ceramics. The findings would be a valuable reference for predicting final temperature of sintering, the equivalent strain during the sintering process, as well as optimizing the densification behavior.
ARTICLE | doi:10.20944/preprints201911.0180.v1
Subject: Engineering, Electrical And Electronic Engineering Keywords: radio virtualization; software-defined radio; network densification; infrastructure sharing; multi-tenancy; cognitive radios
Online: 15 November 2019 (16:44:52 CET)
The next generation of wireless and mobile networks will have to handle a significant increase in traffic load compared to the actual one. This situation calls for novel ways to increase spectral efficiency. Therefore in this paper, we propose a wireless spectrum hypervisor architecture that abstracts a radio frequency (RF) front-end into a configurable number of virtual RF front-ends. The proposed architecture has the ability to enable flexible spectrum access in existing wireless and mobile networks, which is a challenging task due to the limited spectrum programmability, $i.e.$, the capability a system has to change the spectral properties of a given signal to fit an arbitrary frequency allocation. The main goal of the proposed approach is to improve spectral efficiency by efficiently using vacant gaps in congested spectrum-bandwidths or adopting network densification through infrastructure sharing. We demonstrate mathematically how our proposed approach works and present several simulation results proving its functionality and efficiency. Additionally, we designed and implemented an open-source and free proof of concept prototype of the proposed architecture, which can be used by researchers and developers to run experiments or extend the concept to other applications. We present several experimental results used to validate the proposed prototype. We demonstrate that the prototype can easily handle up to 12 concurrent physical layers.
ARTICLE | doi:10.20944/preprints202311.1399.v1
Subject: Chemistry And Materials Science, Materials Science And Technology Keywords: β -Tricalcium phosphate; SiO2 particle dispersed β -TCP composite sintered body; densification; nanoparticle dispersion
Online: 22 November 2023 (14:51:20 CET)
Abstract: Composite sintered bodies comprising silicon dioxide (SiO2) nanoparticles dispersed in β-tricalcium phosphate (β-TCP) were prepared. The addition of nano-sized colloidal SiO2 to the β-TCP produced well-dispersed secondary phase nanoparticles that promoted densification by suppressing grain growth and increasing volume shrinkage of the sintered bodies. The SiO2 was found not to react with the β-TCP at 1120 °C and the substitution of silicon for phosphorous to produce a solid solution did not occur. This lack of a reaction is ascribed to the absence of avail-able calcium ions to compensate for the increase in charge associated with this substitution. The SiO2 nanoparticles were found to be present near the intersections of grain boundaries in the β-TCP. A β-TCP composite sintered body containing 4.0 wt% SiO2 exhibited a bending strength comparable to that of cortical bone and hence could potentially be used as a bone filling material.
ARTICLE | doi:10.20944/preprints202206.0135.v1
Subject: Environmental And Earth Sciences, Geophysics And Geology Keywords: applied geophysics; digital signal processing; enhancement of sharpness of 3D-GPR datasets; 2D Fourier interpolation; GPR data densification
Online: 9 June 2022 (04:30:02 CEST)
INT-FFT algorithm presented in this work uses an interpolation methodology to densify 3D-GPR datasets to sharpen images obtained in GPR surveys obtained in an archaeological context. It allows the reconstruction of missing data from the combined use of mathematical transforms (e.g., the Fourier and Curvelet transform) and predictive filters. This technique makes it possible to calculate the missing signal simply by meeting two requirements: the data in the frequency domain must be limited in a range of values and must be able to be represented by a distribution of Fourier coefficients (verified conditions). The INT-FFT algorithm uses an open-access routine (Suinterp, Seismic Unix) to interpolate the GPR profiles based on seismic trace interpolation. This process uses automatic event identification routines by calculating spatial derivatives to identify discontinuities in space by detecting very subtle changes in the signal, thus allowing for more efficient interpolation without artifacts or signal deterioration. We successfully tested the approach using GPR datasets from the Roman Villa of Horta da Torre (Fronteira, Portugal). The results show an increase in the geometric sharpness of the GPR reflectors and have not produced any numerical artifacts. The tests performed to apply the methodology to GPR-3D data allowed for assessing the interpolation efficiency, the level of recovery of missing data, and the level of information lost when one chooses to increase the distance between profiles in the acquisition stage of the data.