Search results for "Rubbing"
showing 10 items of 11 documents
Research Regarding the Physical-Mechanical Properties of Knits for Garments – Abrasion Resistance
2017
Abstract During wear, the fabric is subjected to a complex combination of forces acting at various rates, in various intensities, in various directions and for various periods. This is one of the main causes of a fabric and garment becoming unacceptable for further wear. The main goal of this research paper is to improve the physical-mechanical properties of knits for garments by choosing the right fabric structure and raw material. The abrasion resistance is a mechanical deterioration and progressive loss of substance from a fabric, resulting from the fabric rubbing against itself or another surface. Tests was done on weft knitted fabric for garments using cotton, wool and mixed yarns, thr…
Reaction path models of magmatic gas scrubbing
2016
Gas-water-rock reactions taking place within volcano-hosted hydrothermal systems scrub reactive, water-soluble species (sulfur, halogens) from the magmatic gas phase, and as such play a major control on the composition of surface gas manifestations. A number of quantitative models of magmatic gas scrubbing have been proposed in the past, but no systematic comparison of model results with observations from natural systems has been carried out, to date. Here, we present the results of novel numerical simulations, in which we initialized models of hydrothermal gas-water-rock at conditions relevant to Icelandic volcanism. We focus on Iceland as an example of a "wet" volcanic region where scrubb…
CO2 capture from biogas: Absorbent selection
2013
The development of proper biogas upgrading technology offers a viable means to utilize biogas in conventional power systems. In this paper, various molecular and ionic solvent systems were evaluated for CO2 removal from biogas in a loop reactor system. The performance of amine solutions, ionic liquids and their mixtures, amino acid salts and solutions blended with piperazine was compared in terms of their CO2 loading capacity. The experimental results revealed that addition of small amounts of piperazine can increase on average by 30 vol% the efficiency of above-mentioned solutions. The CO2 capturing capacity achieved for the most promising solvents was in the range of 50–60 L CO2/L absorbe…
Rotor whirl damping by dry friction suspension systems
2008
An efficient and automatic attenuation technique for the whirling motion of rotating machinery can be achieved by supporting the journal boxes elastically and providing them with suitable rubbing surfaces subject to dry friction normal to the shaft axis. The critical flexural speeds are easily cut off and the whirl amplitude is minimized throughout the frequency range. Confining the usual operative angular speed of the rotor in the range of adhesive contact between the dry friction surfaces, there is no significant increase of power dissipation or heat production as a whole due to this type of suspension system, whose task is just to suppress the resonant peaks when passing the critical spe…
On damping characteristics of frictional hysteresis in pre-sliding range
2016
Frictional hysteresis at relative motion in the pre-sliding range is considered. This effect is characterized by an elasto-plastic interaction, and that on the micro-scale, between two rubbing surfaces in contact that gives rise to nonlinear friction force. The pre-sliding friction force yields hysteresis in displacement. In this study, the damping characteristics of frictional hysteresis are analyzed. It is worth noting that we exclude the viscous damping mechanisms and focus on the pure hysteresis damping to be accounted in the friction modeling. The general properties of pre-sliding friction hysteresis are demonstrated and then compared with the limit case of discontinuous Coulomb fricti…
Damping of rotor conical whirl by asymmetric dry friction suspension
2009
Abstract A new technique for the rotor whirl damping in rotating machinery, based on the elastic suspension of the journal boxes and the use of dry friction surfaces normal to the shaft axis between their supports and the frame, is here analysed theoretically for several cases of rotor systems characterized by mass and constraint asymmetry, where gyroscopic effects are to be expected and conical whirl motions may grow up. The critical flexural speeds can be easily cut off by an adhesive state of the supports and the whirl amplitude can be minimized as well throughout the remaining sliding range. Confining the operative angular speed of the rotor in the range of adhesive contact between the …
La casa capanna Pitigliani di Giovanni Michelucci nella frazione marittima di Tor San Lorenzo, ad Ardea (Rm). Memorie di una comunità di pescatori, a…
2017
Il testo che qui presento anticipa un mio studio in corso sullo spazio pubblico tra committenza e memoria soggettiva, con particolare attenzione al paesaggio e al suo impatto sull’immaginario. Un tema che si riallaccia ad alcune ricerche da me accese a partire dalla seconda metà del Duemila e confluite, poi, in una serie di pubblicazioni. In particolare, mi riferisco, pur rinviando alle note e alla bibliografia di questo scritto, alla città e all’uso pubblico della storia (2011), agli atelier d’artista (2014), al progetto di museo diffuso all’Eur e nel quadrante sud-ovest della capitale (2015) e, infine, al rapporto tra architettura e committenza nell’Europa contemporanea ( 2016). Argomenti…
Health-Improved Textiles Obtained by Heat Surface Ecodyeing Treatments
2015
The central idea of the present research aims at achieving textile substrates through an efficient inclusion of a wild black cherry extract into the grafting agent-monochlorotriazinyl-β-cyclodextrin (MCT-β-CD). The methodology consists in a permanent/irreversible entrapment onto the fibres surface of the natural extract through inclusion mechanism. Exhaustion and sonication dyeing procedures were used alternatively. The obtained materials were characterized, by FT-IR and BET analysis. The experimental results reveal good adsorptive feature of the samples, due to a higher specific surface created by the inclusion complex (MCT-β-CD-dye pigment). An efficient blocking of the natural dye pigmen…
Biogas Cleaning by Hydrogen Sulfide Scrubbing and Bio-oxidation of Captured Sulfides
2015
Hydrogen sulfide and partially carbon dioxide can be absorbed into alkaline washing liquid with nitrates for upgrading a quality of biogas. Sulfides captured into the washing liquid are consequently biologically oxidized in an anoxic bioreactor by autotrophic denitrifying bacteria. Nitrates in the washing liquid serve as electron acceptors for sulfide bio-oxidation. Washing of hydrogen sulfide from biogas was examined in a lab-scale countercurrent scrubber that was packed with plastic carriers and operated at different biogas and washing liquid flows. The hydrogen sulfide concentration in treated biogas was investigated in the range from 3 to 12.3 g m–3. The influence of the hydrogen sulfid…
First multi-GAS based characterisation of the Boiling Lake volcanic gas (Dominica, Lesser Antilles)
2013
We used a Multi-component Gas Analyser System (Multi-GAS) to measure, for the very first time, the composition (H2O, CO2, H2S, SO2) of the volcanic gas plume issuing from the Boiling Lake, a vigorously degassing, hot (T ~ 80-90°C) volcanic lake in Dominica, West Indies. The Multi-GAS captured in-plume concentrations of H2O, CO2 and H2S were well above those typical of ambient atmosphere, while no volcanic SO2 was detected (<0.05 ppm). These were used to derive the Boiling Lake plume characteristic ratios of CO2/H2S (5.2±0.4) and H2O/CO2 (31.4±6). Assuming that other volcanic gas species (e.g., HCl, CO, H2, N2, etc.) are absent in the plume, we recalculated a (air-free) composition fo…