1,326 research outputs found
Development of Urban Electric Bus Drivetrain
The development of the drivetrain for a new series of urban electric buses is presented in the paper. The traction and design properties of several drive variants are compared. The efficiency of the drive was tested using simulation calculations of the vehicle rides based on data from real bus lines in Prague. The results of the design work and simulation calculations are presented in the paper
Fast optical control of spin in semiconductor interfacial structures
We report on a picosecond-fast optical removal of spin polarization from a
self-confined photo-carrier system at an undoped GaAs/AlGaAs interface
possessing superior long-range and high-speed spin transport properties. We
employed a modified resonant spin amplification technique with unequal
intensities of subsequent pump pulses to experimentally distinguish the
evolution of spin populations originating from different excitation laser
pulses. We demonstrate that the density of spins, which is injected into the
system by means of the optical orientation, can be controlled by reducing the
electrostatic confinement of the system using an additional generation of
photocarriers. It is also shown that the disturbed confinement recovers within
hundreds of picoseconds after which spins can be again photo-injected into the
system
ASTRONOMICAL GLASS PLATE NEGATIVES: MONITORING OF EMULSION LAYER DETERIORATION
One of the techniques for making photographic negatives most used in the history of photography were gelatin glass plates. This technique was used not only in the artistic field but also and mainly in the scientific field. The main period when glass plate negatives were used in astronomy was between 1890–1980. There are over 7 million of these negatives all over the word and they carry valuable historical scientific data. However, during the long-term storage of this material, deterioration of the emulsion (picture) layer and/or the support (glass) layer has occurred. In this paper we report on our preliminary results from an analysis of the yellowing of the emulsion layer and of gold micro-spots. Both phenomena worsen the readability of the information in the photograph, and it is necessary to prevent their formation, which is why we need to know as much as possible about their origin
Diaryliodonium Salts in Organic Syntheses: A Useful Compound Class for Novel Arylation Strategies
Combined geophysical (magnetotellurics) and geochemical results for determination of the Lithosphere-Asthenosphere Boundary (LAB) beneath the Nógrád-Gömör Volcanic Field
Determination of the Lithosphere-Asthenosphere Boundary (LAB) beneath the Nógrád-Gömör Volcanic Field by combined geophysical (magnetotellurics) and geochemical methods
Understanding the fundamental role of LAB is substantial for the investigation of the geodynamic evolution of
the Earth. The LAB depths can be estimated by different geophysical methods (seismology, magnetotellurics),
however these depths are controversial. It has been emphasized in the literature that combined geophysical and
geochemical approach may lead to better understanding of these depths.
The magnetotellurics (MT) is very powerful method because it indicates the sudden increase in conductivity at
the LAB. The mantle xenoliths (small fragments of the lithospheric mantle) provide the information to reconstruct
their P-T paths.
In the Carpathian-Pannon region (CPR) five, well-studied occurrences of mantle xenoliths-bearing Plio-Pleistocene
alkali basalts are known, which makes the CPR a very promising area for investigating the inconsistency in the
LAB estimates. As a test area Nógrád-Gömör Volcanic Field (NGVF) has been chosen.
The host basalt erupted at the NGVF collected mantle xenoliths from a small volume of the upper mantle in a
depth of about 40-50 km. The major element geochemistry of the studied xenoliths indicates that most of them
represent common lherzolitic mantle, whereas others show strong wehrlitisation process. This metasomatism
is supposed to be caused by a migrating mafic melt agent, resulting in the transformation of a large portion of
lherzolite to wehrlite beneath the NGVF, possibly just below the crust mantle boundary.
In aim to detect the LAB at the research area and find the correlation with petrologic and geochemical results
we carried out MT deep soundings. The campaign contained 12 long period MT stations with 3-5 km average
spacing along 60 km long profile SSE to NNW direction. This presentation summarizes the preliminary results of
the combined geophysical and geochemical approaches to determine the LAB depths
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