1,697 research outputs found
Laser ion acceleration using a solid target coupled with a low density layer
We investigate by particle-in-cell simulations in two and three dimensions
the laser-plasma interaction and the proton acceleration in multilayer targets
where a low density "near-critical" layer of a few micron thickness is added on
the illuminated side of a thin, high density layer. This target design can be
obtained by depositing a "foam" layer on a thin metallic foil. The presence of
the near-critical plasma strongly increases both the conversion efficiency and
the energy of electrons and leads to enhanced acceleration of proton from a
rear side layer via the Target Normal Sheath Acceleration mechanism. The
electrons of the foam are strongly accelerated in the forward direction and
propagate on the rear side of the target building up a high electric field with
a relatively flat longitudinal profile. In these conditions the maximum proton
energy is up to three times higher than in the case of the bare solid target.Comment: 9 pages, 11 figures. Submitted to Physical Review
Tilting vehicle and control system thereof
The patent is relative to architecture and control laws of a steer and tilt by-wire system for tilting vehicles. It is constituted by steer and tilting actuators which are driven by an electronic control unit to minimize the load transfer during cornering. With respect to traditional steer by wire systems, a mechanical link between the steer command and the wheels is maintained: this is a mechanical backup in case of electromechanical faults of the system
THERMODYNAMIC ORC CYCLE DESIGN OPTIMIZATION FOR MEDIUM-LOW TEMPERATURE ENERGY SOURCES
In the large spectrum of organic fluids suitable for Rankine cycles, a fluid that is already wellknown
and available on industrial scale but currently excluded from this kind of application
has been selected.
This choice is due to the remarkable characteristics of the fluid, such as its high molecular
weight, good thermal stability, non-flammability, and atoxicity.
Compared to those fluids nowadays common in the ORC market, its thermodynamic
properties and fluid dynamic behavior lead to a peculiar configuration of the cycle:
• Supercritical cycle, when heat input is at medium-high temperature;
• Massive regeneration, to obtain higher efficiency;
• Low specific work of the turbine;
• Relatively high volumetric expansion ratio and relatively low absolute inlet volumetric
flow;
Accordingly, an innovative cycle design has been developed, including a once-through
Hairpin primary heat exchanger and a multi-stage radial outflow expander.
This last innovative component has been designed to get the best performance with the chosen
fluid:
• The high inlet/outlet volumetric flow ratio is well combined with the change in cross
section across the radius;
• Compared to an axial turbine, the lower inlet volumetric flow is compensated by
higher blades at the first stage. It is feasible thanks to the change in section available
along the radius, so that there is no need for partial admission;
• The prismatic blade leads to constant velocity diagrams across the blade span;
• It minimizes tip leakages and disk friction losses, due to the single disk / multi-stage
configuration;
• The intrinsical limit of a radial outflow expander to develop high enthalpy drop is not
relevant for this cycle, presenting itself a very low enthalpy drop. Moreover the tip
speed is limited by the low speed of sound and consequently this kind of expander
suits well with this cycle arrangement.
The results of this study, conducted through thermodynamic simulations, CFD, stress analysis
and economic optimization show an ORC system that reaches high efficiencies, comparable
to those typical of existing system
Pressure-induced Jahn-Teller switch in the homoleptic hybrid perovskite [(CH3)(2)NH2]Cu(HCOO)(3): orbital reordering by unconventional degrees of freedom
Through in situ, high-pressure X-ray diffraction experiments we have shown that the homoleptic perovskite-like coordination polymer [(CH3)2NH2]Cu(HCOO)3 undergoes a pressure-induced orbital reordering phase transition above 5.20 GPa. This transition is distinct from previously reported Jahn–Teller switching in coordination polymers, which required at least two different ligands that crystallize in a reverse spectrochemical series. We show that the orbital reordering phase transition in [(CH3)2NH2]Cu(HCOO)3 is instead primarily driven by unconventional octahedral tilts and shifts in the framework, and/or a reconfiguration of A-site cation ordering. These structural instabilities are unique to the coordination polymer perovskites, and may form the basis for undiscovered orbital reorientation phenomena in this broad family of materials
A Generalized Benders Decomposition based algorithm for an inventory location problem with stochastic inventory capacity constraints
Tilting vehicle and control system thereof
The patent is relative to architecture and control laws of a steer and tilt by-wire system for tilting vehicles. It is constituted by steer and tilting actuators which are driven by an electronic control unit to minimize the load transfer during cornering. With respect to traditional steer by wire systems, a mechanical link between the steer command and the wheels is maintained: this is a mechanical backup in case of electromechanical faults of the syste
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