Search results for "SPEED"
showing 10 items of 876 documents
ECT of ethanol and hexane mixtures in the spinning disk system
2007
The paper presents the research results of electrostatic charging tendency (ECT) of ethanol and hexane mixtures, a liquid of a simple chemical structure and high purity (pro analysis). The research work was carried out in a spinning disk system, where the factors influencing the value of the electrification current registered were the composition of the mixture and the rotational speed of the disk. The research results showed that the biggest ECT changes occur in the range of up to 10% of ethanol content in hexane and the electrification current characteristic has a visible maximum for the mixture, the contents of which constitute 95% of hexane volume and 5% of ethanol by volume. In the nex…
On the improvement of material formability in SPIF operation through tool stirring action
2012
Single-point incremental forming (SPIF) is a quite new sheet-forming process which offers the possibility to deform complex parts without dedicated dies using a single-point tool and a standard three-axis CNC machine. The process mechanics enables higher strains with respect to traditional sheet-forming processes, but particular attention must be given to the maximum forming angle. In this paper, a new approach is proposed to enhance the material formability through a localized sheet heating as a consequence of the friction work caused by elevated tool rotational speeds. AA1050-O, AA1050-H24, and AA6082-T6 were utilized, and the reached temperatures were recorded by thermocouples, fixed to …
In-process tool rotational speed variation with constant heat input in friction stir welding of AZ31 sheets with variable thickness
2017
In the present work, friction stir welding experiments on AZ31 magnesium alloy sheets, characterized by a variable thickness along the welding line, were carried out. The approach adapted during welding consisted in maintaining constant the heat input to the joint. To this purpose, the rotational speed of the pin tool was increased with decreasing thickness and decreased with increasing thickness in order to obtain the same temperatures during welding. The amount by which the rotational speed was changed as a function of the sheet thickness was defined on the basis of the results given by FEM simulations of the FSW process. Finally, the effect of the in-process variation of the tool rotatio…
Outlining the Limits of Friction Stir Consolidation as Used as an Aluminum Alloys Recycling Approach
2021
Friction stir consolidation (FSC) is a solid-state process that recycles metal scraps economically and eco-friendly compared to the conventional melting method. The process parameters especially processing time and rotational speed, have a crucial role in achieving a sound disc during FSC. The current study answers the research question of how far these process parameters can be effective when the mass of chips to be recycled increases. In specific, an experimental setup was analyzed that was previously identified as challenging for recycling 20 g chips of aluminum alloy AA 2024-O. Rotational speed was set doubled, and processing time was increased up to 1.5 times of their initial values. T…
Narrow Band Solid-Liquid Composite Arrangements: Alternative Solutions for Phononic Crystal-Based Liquid Sensors
2019
Periodic elastic composite structures attract great attention. They offer the ability to design artificial properties to advance the control over the propagation of elastic/acoustic waves. In previous work, we drew attention to composite periodic structures comprising liquids. It was shown that the transmission spectrum of the structure, specifically a well-isolated peak, follows the material properties of liquid constituent in a distinct manner. This idea was realized in several liquid sensor concepts that launched the field of phononic crystal liquid sensors. In this work we introduce a novel concept&mdash
3D simulations of wind-jet interaction in massive X-ray binaries
2010
High-mass microquasars may produce jets that will strongly interact with surrounding stellar winds on binary system spatial scales. We study the dynamics of the collision between a mildly relativistic hydrodynamical jet of supersonic nature and the wind of an OB star. We performed numerical 3D simulations of jets that cross the stellar wind with the code Ratpenat. The jet head generates a strong shock in the wind, and strong recollimation shocks occur due to the initial overpressure of the jet with its environment. These shocks can accelerate particles up to TeV energies and produce gamma-rays. The recollimation shock also strengthens jet asymmetric Kelvin-Helmholtz instabilities produced i…
Recent changes in measured wind in the NE Atlantic and variability of correlation with NAO
2010
The paper deals with wind measurements, recorded since the 1950s, at twelve meteorological stations along a transect near the westernmost European border, between 64° and 44° N. Extreme wind speed tends to decrease sharply near the northern boundary (at Reykjavick), near the middle of the study area (at Shannon and Valentia) and near the southern boundary (at Brest and Cap Ferret), to increase at Thorshavn, with less significant trends at the other stations. Average wind speeds confirm the above tendencies, with an additional increasing speed at Lerwick, Kirkwall, Malin Head, Belle-Ile and Cap Ferret. To compare changes in wind activity, the data have been subdivided into three periods: unt…
Collisional effects on spectral line shape from the Doppler to the collisional regime: A rigorous test of a unified model
2000
International audience; The paper presents high resolution Raman investigations of the Q(1) line of H-2 in Ar mixture from low density (Doppler regime) to high density (collisional regime) analyzed with a unique line shape profile. Measurements are performed by stimulated Raman gain spectroscopy between 300 and 1000 K in a wide density range (from 0.2 to 11 amagat). All the observed spectral features are accurately described by a unified model recently proposed by two of the authors. This model accounts for a velocity-memory process, not restricted to the usual hard and soft limits. It also includes correlation between velocity- and phase-changing collisions. An exhaustive analysis of vario…
H-2 vibrational spectral signatures in binary and ternary mixtures: theoretical model, simulation and application to CARS thermometry in high pressur…
2001
International audience; A summary of the main results obtained by the two groups in the field of H-2 vibrational spectral line signatures for various mixtures. in connection with CARS diagnostics of H-2-O-2 combustion systems, is presented. H-2-X Systems may have specific large inhomogeneous spectral features, due to the dependence of the line broadening and line shifting on the (H-2) radiator speed, particularly at high temperature. Thus, careful attention has to be paid to rigorously analyze such features, both from the experimental point of view (Dijon) and from the theoretical one (Besancon). Applications of the present results to high-pressure H-2/air flame thermometry are also briefly…
Defect-controlled hypersound propagation in hybrid superlattices
2013
We employ spontaneous Brillouin light scattering spectroscopy and detailed theoretical calculations to reveal and identify elastic excitations inside the band gap of hypersonic hybrid superlattices. Surface and cavity modes, their strength and anticrossing are unambiguously documented and fully controlled by layer thickness, elasticity, and sequence design. This new soft matter based superlattice platform allows facile engineering of the density of states and opens new pathways to tunable phoxonic crystals.