Search results for "Thermal"
showing 10 items of 3576 documents
Scientific and technological approaches for sintering and joining of metallic materials by SPS
2013
The flash sintering technique (commonly known as spark plasma sintering, SPS) generates a craze worldwide. This process allows a powder densification from speeds generally 10 to 100 times higher than those of the traditional sintering techniques. In addition, this allows the synthesis of innovative and original dense materials, with a controlled microstructure, complex shapes and, sometimes large sizes. However, the control of scaling and microstructure homogeneity of parts obtained by such a process requires a perfect knowledge of technical equipment including flash sintering to reduce thermal gradients. Modeling is a valuable aid to achieve the improvement of its control. Another potentia…
Correlation of epoxy material properties with the toughening effect of fullerene-like WS2 nanoparticles
2016
Abstract This work deals with the toughening effect of inorganic, fullerene-like WS2 (IF-WS2) nanoparticles (NPs) on epoxy. It has been hypothesized that this toughening effect depends on the epoxy’s cross-link density, its molecular defect fraction or its reference fracture toughness K Ic . Seven different epoxy systems were filled with 0.5% laboratory-made IF-WS2 NPs by mass and investigated in order to analyze which material properties are determining the toughening effect. These NPs were similar to commercially available IF-WS2 NPs, but their agglomerates could not be broken up as successfully and they yielded less toughening effect. The cross-link density of the epoxies measured via dy…
A novel class of interpenetrated 3-D network of a dimeric cupric-tetracarboxylate unit
2002
The hydrothermal reaction of Cu(II), fumaric acid and 4,4′-bipyridine (bpy) in equimolar amounts at 160 °C resulted in a new type of two-fold interpenetrating 3-D coordination network composed of tetracarboxylate dicopper(II) units bridged by bipyridine spacers.
Diffuse soil gas emissions of gaseous elemental mercury (GEM) from hydrothermal-volcanic systems: An innovative approach by using the static closed-c…
2016
This study was aimed to test a new methodological approach to carry out measurements of gaseous elemental mercury (GEM) diffusively emitted from soils in hydrothermal-volcanic environments. This method was based on the use of a static closed-chamber (SCC) in combination with a Lumex® RA-915M analyzer that provides GEM measurements in a wide range of concentrations (from 2 to 50,000 ng m-3). Gas samples were collected at fixed time intervals from the SCC positioned on the ground (time-series samples). The Lumex® inlet port was equipped with a three-way Teflon valve allowing the free entrance of air through a carbon trap, in order to: (i) prevent disturbance to the Lumex® operative flow rate …
Positronium as a probe in natural polymers: decomposition in starch
2009
Ortho-positronium (o-Ps) is used as a probe in positron annihilation lifetime spectroscopy (PALS) experiments, to characterise the behaviour of free volumes in natural starch samples, as a function of temperature (T). Up to about 540 K, the o-Ps intensity, I(3), remains constant at 26.2% while its lifetime, tau(3), is found to increase linearly. Both parameters undergo a decrease above this T, due to the onset of decomposition, which results in a shrinking of the sample pellets. The results indicate that the glass transition temperature should be above 501 K. Data from thermal gravimetry analysis (TGA) measurements are well described by supposing a first order process for the survival proba…
''Isokinetic intervention in microtraumatic shoulder instability: an update''
2012
Gremeaux, V. | Croisier, J. L. | Forthomme, B.; International audience; ''Aim. Aim of the present study was to carry out a critical analysis of the use of isokinetic dynamometers for evaluation and rehabilitation in microtraumatic shoulder instability. Methods. A non-systematic literature review was conducted on Medline using the following key words: "isokinetics", "shoulder instability", "evaluation", "rehabilitation". We also analyzed the related articles, and compiled a database of expert opinion. Results. Despite a lack of consensus on testing modalities, lateral and medial rotator muscle strength can be safely and reliably assessed on isokinetic devices in subjects presenting with micr…
Impact of gadolinium on the structure and magnetic properties of nanocrystalline powders of iron oxides produced by the extraction-pyrolytic method
2020
The work has been done in frame of the TransFerr project. It has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No. 778070. This research was also supported by Latvian Research Council project lzp-2018/1-0214. A.I.P. appreciates support from the Estonian Research Council grant (PUT PRG619).
Steady State Performance of Spark Ignition Engine with Exhaust Energy Recovery
2020
As is known, internal combustion engines based on Otto or Diesel cycles cannot complete the expansion process of the gas inside the cylinder, thus losing a relevant energy content, in the order of 30% of total. The residual energy of the unexpanded gas has been partially exploited through the use of an exhaust gas turbine for turbocharging the internal combustion engine; further attempts have been made with several compound solutions, with an electric generator connected to the turbocharger allowing to convert into electrical energy the quota power produced by the turbine which is not used by the compressor, or with a second turbine downstream the first to increase the exhaust gas energy re…
Photothermoelastic analysis of thermal stresses in discs with eccentric holes
1970
The paper deals with thermal stresses that arise in discs with eccentric holes, such as are employed in the rotors of multi-stage gas turbines. The stress distribution was analysed by the photothermoelastic method. CR 39 sheets were used as the material and dry ice as the refrigerant. The effect of several geometric parameters on stress distribution, especially the influence of adjacent holes, was investigated by testing 32 configurations of discs. Curves that allow the determination of the peak stresses and optimum spacing of holes are given.