Search results for "Ultra"
showing 10 items of 4451 documents
AN INEXPENSIVE ULTRA-HIGH-SPEED PHOTOGRAPHIC TECHNIQUE
1968
Commercial Ultra-High-Speed Cameras for framing rates over 50,000 f.p.s. are very expensive and yield a small number of frames (8 to 24) per run. The single-flash technique with increasing delays gives photographs at a high framing rate over a comparatively long time and, as described here, requires no special electronic equipment except a good flash unit and a general-purpose oscilloscope.
Stretched fibre based dispersion compensating module for ultra high-speed telecommunication systems
2008
International audience; In this work, the potential efficiency of a low-loss, tunable second-and third-order dispersion compensating module based on a stretched optical fibre for ultra high-speed telecommunication systems is analysed. Experimental results at a repetition rate of 640 GHz show that precise dispersion compensation could be achieved in the range of +0.038 ps/nm by means of an 11.3 cm maximum stretching of a 48 m long dispersion compensating.
Practical design rules for single-channel ultra high-speed dense dispersion management telecommunication systems
2009
International audience; In this work, we establish some efficient and practical design rules for the implementation of single-channel ultra-high speed (>160-Gbit/s) telecommunication systems based on dense dispersion management. Moreover, we analyze some of actual implementation issues such as slope compensation scenario, junction losses, polarization mode dispersion and chromatic dispersion fluctuations.
A new method to "clean up" ultra high-frequency data
2007
In the applied econometrics, the availability of ultra high-frequency databases is having an important impact on the research market microstructure theory. The ultra high-frequency databases contain detailed reports of all the financial market activity information which is available. However, ultra high-frequency databases cannot be directly used. On one hand recording mistakes can be present, on the other hand missing information has to be inferred from the available data. In this paper, we propose a simple method in order to clean up the ultra high-frequency data from possible errors and we examine the method efficacy when we analyze data by using an autoregressive conditional duration (A…
Effect of electron beam irradiation and plastic deformation on molar mass of medical grade ultra-high molecular weight polyethylene
2010
Badano wpływ sterylizacji metodą napromieniania strumieniem elektronów oraz deformacji plastycznej (zgniatania, rys. 1) polietylenu ultrawielkocząsteczkowego (UHMW-PE), stosowanego do wytwarzania panewek endoprotez stawu biodrowego, na masę molową polimeru. Stwierdzono, że sterylizacja wpływa na utleniającą destrukcję makrocząsteczek polimeru, której stopień zależy od użytej dawki promieniowania (zmniejszenie masy molowej masowo średniej). Procesowi temu towarzyszy sieciowanie makrocząsteczek (wzrost udziału frakcji nierozpuszczalnej). Z kolei sama deformacja plastyczna wydaje się nie mieć wyraźnego wpływu na proces degradacji. Tymczasem łączne zastosowanie obydwu czynników zewnętrznych pro…
The Effect of Impact Pressure on Positron Lifetime in Ultra High Molecular Weight Polyethylene (PE-UHMW)Chirulen®1120
2010
The paper presents the results of investigations of the effect of impact pressure (in the range of both elastic and plastic deformations) on the parameters of the positron lifetime spectra in PE-UMHW polymer known under the trade mark Chirulen1120. The changes in the long-living component of the positron lifetime spectrum, connected with the annihilation of o-Ps in the pick-off process, are analyzed in dependence on the impact energy. The impact duration in the Charpy’s tests depending on the impact energy was measured, too. The dependencies of the radius of the volume of empty spaces in which the positronium annihilates, on the impact pressure were determined applying the Eldrup-Tao model.
Immobilization of natural anti-oxidants on carbon nanotubes and aging behavior of ultra-high molecular weight polyethylene-based nanocomposites
2014
The use of natural antioxidants is an attractive way to formulate nanocomposites with extended durability and with potential applications in bio-medical field. In this work, Vitamin E (VE) in the form of α-tocopherol and Quercetin (Q) are physically immobilized on the outer surface of multi-walled carbon nanotubes (CNTs). Afterward, the CNTs-VE and CNTs-Q are used to formulate thermally stable ultra high molecular weight polyethylene based nanocomposites. The obtained results in the study of the thermo-oxidation behavior suggest a beneficial effect of the natural anti-oxidant carbon nanotubes systems. The unexpected excellent thermo-resistance of the nanocomposites seems to be due to a syne…
α-Tocopherol-induced radical scavenging activity in carbon nanotubes for thermo-oxidation resistant ultra-high molecular weight polyethylene-based na…
2014
?-Tocopherol, a natural antioxidant molecule, was physically immobilized on the outer surface of multi-walled carbon nanotubes (CNTs), and the resulting functionalised particles (f-CNTs) were dispersed in ultra-high molecular weight polyethylene aiming at improving its thermo-oxidation resistance. The success of the functionalization was assessed through spectroscopic and thermal analysis, and the influence of the filler on the thermo-oxidative stability of the nanocomposites was investigated through rheological analyses and infrared spectroscopy. We found that the addition of only 1 wt.% of f-CNTs brings about a surprisingly high oxidation resistance, with a five/ten-fold increase of the i…
Synthesis of Ultra-High-Molecular-Weight Polyethylene
1984
The catalytic activity of organometallic Ti-Al complexes with donor ligands in the low-pressure polymerization of ethylene was studied. These complexes were obtained by the reaction of ethylaluminium compounds like AlEt2Cl or Al2Et3Cl3 and titanium compound of the type Ti(OR)nCl4-n (where: R = C2—C10 alkyl, C6H5, C6H4X; X — m-CH3, p-CH3, m-OCH3, p-OCH3, m-Cl, p-Cl, p-Br; n = 1—4). The optimum conditions for the synthesis of these compounds, as well as their physico-chemical properties were studied by means of EPR and polarographic methods. The effect of the type and number of OR ligands in a catalytic system on the yield of polyethylene and on its properties was examined. Ti-Al catalysts wi…
Beurling ultradistributions of Lp-growth
2003
We study the convolutors and the surjective convolution operators acting on spaces of ultradistributions of Lp-growth. In the case p = 2 we obtain complete characterizations. Some results on hypoellipticity are also included. 2003 Elsevier Science (USA). All rights reserved.