16,411 research outputs found
Cryogenic magnetometer research at Twente University of Technology
In 1982 we started the project âCryogenic Magnetometersâ with the aim to develop SQUID-magnetometers appropriate to a large variety of applications. The first system we developed is a SQUID-magnetometer with an open-ended horizontal access at room temperature. The measuring space inside the pick-up coils is easy accessible and the magnetization (remanent or induced) can be measured of materials in a static position or transported through the access.\ud
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Further, systems have been developed with the pick-up coil set outside the cryostat, in order to arrive at a flexible system with which the object under investigation can be approached as close as possible. Another part of the project is the optimization of magnetometers with respect to the cryogenic system in order to develop cryogenic magnetometer systems with a very long time between helium refills. The present status of these three research subjects is briefly described
Nylon-6/rubber blends: 6. Notched tensile impact testing of nylon-6(ethylene-propylene rubber) blends
The deformation and fracture behaviour of nylon-6/EPR (ethylene-propylene rubber) blends is studied as a function of strain rate and rubber content. Therefore, tensile experiments are conducted on notched specimens over a broad range of draw speeds (including strain rates as encountered in normal tensile tests and in impact tests). The blends with a high rubber content show super-tough behaviour at low and high speeds. In the intermediate-speed regime the fracture energy reaches a minimum (with a level comparable with that of unmodified nylon). The blends with a low rubber content show a transition from tough to brittle behaviour with increasing strain rate. The sudden rise in fracture energy with rising strain rate is believed to be caused by a transition from isothermal to adiabatic deformation. In the adiabatic regime the rise in temperature is high enough to melt the material around the crack tip. This thermal blunting mechanism causes crack propagation to be stable at high strain rates. This mechanism is affirmed by scanning electron microscope studies of the deformation zone
Three-dimensional fast electron transport for ignition-scale inertial fusion capsules
Three-dimensional hybrid PIC simulations are presented to study electron
energy transport and deposition in a full-scale fast ignition configuration.
Multi-prong core heating close to ignition is found when a few GA, few PW beam
is injected. Resistive beam filamentation in the corona seeds the 3D current
pattern that penetrates the core. Ohmic heating is important in the low-density
corona, while classical Coulomb deposition heats the core. Here highest energy
densities (few Tbar at 10 keV) are observed at densities above 200 g/cc. Energy
coupling to the core ranges from 20 to 30%; it is enhanced by beam collimation
and decreases when raising the beam particle energy from 1.5 to 5.5 MeV.Comment: 5 pages, 5 figure
Dirichlet-to-Neumann maps on bounded Lipschitz domains
The Dirichlet-to-Neumann map associated to an elliptic partial differential
equation becomes multivalued when the underlying Dirichlet problem is not
uniquely solvable. The main objective of this paper is to present a systematic
study of the Dirichlet-to-Neumann map and its inverse, the Neumann-to-Dirichlet
map, in the framework of linear relations in Hilbert spaces. Our treatment is
inspired by abstract methods from extension theory of symmetric operators,
utilizes the general theory of linear relations and makes use of some deep
results on the regularity of the solutions of boundary value problems on
bounded Lipschitz domains
Consistent operator semigroups and their interpolation
Under a mild regularity condition we prove that the generator of the
interpolation of two C0-semigroups is the interpolation of the two generators
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