Search results for "CONTACT"
showing 10 items of 1003 documents
Nuclear Contact Times in Dissipative Heavy Ion Collsions Measured Via γ-Ray Spectroscopy
1987
Electron spectra have been measured for elastic and dissipative U + Au collisions at 8.6 MeV/u and analysed within a simple schematic model which describes γ-ray emission in the presence of a nuclear contact time and a total kinetic energy loss (TKEL). A nearly linear dependence of the mean nuclear contact time τ and TKEL was found, reaching τ = 1.1 * 10-21 s with a variance σ = ±0.4 * 10-21 s for a TKEL of (400 ± 50) MeV.
El “Aula del Cel”: astronomy approaching high school
2005
The “Aula del Cel” is a project carried out by the Astronomical Obsevatory of the University of Valencia, Spain. It offers high-school teachers a tool for teaching Astronomy to 10 to 17 year-old students. Different programs, experiments, and audiovisual presentations have been prepared by a team formed both by professional astronomers and teachers, and are offered in a format chosen to suit each particular age and curriculum group. Special sessions have been designed for students with special needs (for example blind or autistic children) in close contact with the pedagogical teams responsible for their education. Nearly three thousand students have already visited the “Aula del Cel” over t…
Stability of gyrotron operation in very high-order modes
2012
This study was motivated by the desire to increase the power, which can be delivered by gyrotrons in long pulse and continuous regimes. Since the admissible power level is determined by the density of ohmic losses in resonator walls, to increase the radiated power a gyrotron should operate in higher order modes. Using an existing gyrotron developed for plasma experiments in the International Thermonuclear Experimental Reactor as a base model, the stability of operation of such a gyrotron in modes with larger number of radial variations was studied. It is shown that the power level achievable in such gyrotrons in stable single mode regimes is close to 1.5 MW. The power level 1.7–1.8 MW can b…
Crumpling of a stiff tethered membrane.
2003
first-principles numerical simulation model for crumpling of a stiff tethered membrane is introduced. In our model membranes, wrinkles, ridge formation, ridge collapse, as well as the initiation of stiffness divergence, are observed. The ratio of the amplitude and wave length of the wrinkles, and the scaling exponent of the stiffness divergence, are consistent with both theory and experiment. We observe that close to the stiffness divergence there appears a crossover beyond which the elastic behavior of a tethered membrane becomes similar to that of dry granular media. This suggests that ridge formation in membranes and force-chain network formation in granular packings are different manife…
Electrical Characterization of CdTe pixel detectors with Al Schottky anode
2014
Abstract Pixelated Schottky Al/p-CdTe/Pt detectors are very attractive devices for high-resolution X-ray spectroscopic imaging, even though they suffer from bias-induced time instability (polarization). In this work, we present the results of the electrical characterization of a (4×4) pixelated Schottky Al/p-CdTe/Pt detector. Current–voltage ( I–V ) characteristics and current transients were investigated at different temperatures. The results show deep levels that play a dominant role in the charge transport mechanism. The conduction mechanism is dominated by the space charge limited current (SCLC) both under forward bias and at high reverse bias. Schottky barrier height of the Al/CdTe con…
Feynman-diagramme als vektorsysteme invariantentheoretisch behandelt (compton-streuung, elektron-positron-vernichtung
1985
Employing a special contact transformation devised by S. Lie, which takes spheres into lines, we interpret the Feynman diagrams of photon electron scattering in terms of vector systems. This gives a nice kinematic model of Compton scattering. We further compute in detail the transition probabilities of the Compton scattering process by making use of the calculus of chains of complexes from classical invariant theory rather than applying the usual Dirac-matrix technique. In the final paragraph of this paper an application of our calculations to the treatment of myon decay is indicated.
Solid Contact Potentiometric Sensors Based on a New Class of Ionic Liquids on Thiacalixarene Platform
2018
New solid-contact potentiometric sensors have been developed for hydrogen phosphate recognition on the basis of ionic liquids containing tetrasubstituted derivatives of thiacalix[4]arene in cone and 1,3-alternate conformations with trimethyl- and triethylammonium fragments at the lower rim substituents. The recognition of selected anions including carbonate, hydrogen phosphate, perchlorate, oxalate, picrate, and EDTA was conducted using electrochemical impedance spectroscopy with ferricyanide redox probe. For the potentiometric sensor assembling, the ionic liquids were stabilized by multiwalled carbon nanotubes and carbon black deposited on the glassy carbon electrode. The influence of supp…
On the Conceptual History of the Term Lingua Franca
2015
This paper aims to give an outline of the development of the term “Lingua Franca”. Initially the proper name of an extinct pidgin, to “Lingua Franca”, the term has become a common noun, used with regard to language contact phenomena in general – at first specifically for pidgins and trade languages, but now for all vehicular languages. This broader usage is especially prominent in the field of research known as “English as a lingua franca” (ELF). Using ELF as an example, it is shown that the modern usage is partly inconsistent and can be misleading, as it connects a positive feature of the original Lingua Franca, viz linguistic equality, with a language with native speakers like English, wh…
Efficient and Accurate Consideration of Ohmic Losses in Waveguide Diplexers and Multiplexers
2006
The accurate consideration of all ohmic losses effects in waveguide manifold diplexers and multiplexers is rigorously studied in this paper. For such purposes, a full-wave CAD tool based exclusively on modal methods is originally proposed. Proceeding in this very efficient way, losses are precisely considered in all common components of such complex devices, i.e. planar junctions, uniform lines and multi-port circuits implemented in waveguide technology. For verification purposes, we have successfully compared our results for a magic-T junction and a manifold diplexer with experimental and numerical results.
Ethiopia as a Linguistic Area
2006
The Ethiopian linguistic area is one of the most famous linguistic areas in the world. It is characterized by phonological, grammatical, and lexical features. After summarizing the research done since 1945, this article focuses on the contradictory views concerning the validity of most of the features. For phonological and grammatical features, Ferguson (1976), which is still the most important study, is the starting point of discussion. Lexical features are dealt with only by Hayward (1991, 2000) and there has been therefore little controversy.