25,473 research outputs found
From vertex detectors to inner trackers with CMOS pixel sensors
The use of CMOS Pixel Sensors (CPS) for high resolution and low material
vertex detectors has been validated with the 2014 and 2015 physics runs of the
STAR-PXL detector at RHIC/BNL. This opens the door to the use of CPS for inner
tracking devices, with 10-100 times larger sensitive area, which require
therefore a sensor design privileging power saving, response uniformity and
robustness. The 350 nm CMOS technology used for the STAR-PXL sensors was
considered as too poorly suited to upcoming applications like the upgraded
ALICE Inner Tracking System (ITS), which requires sensors with one order of
magnitude improvement on readout speed and improved radiation tolerance. This
triggered the exploration of a deeper sub-micron CMOS technology, Tower-Jazz
180 nm, for the design of a CPS well adapted for the new ALICE-ITS running
conditions. This paper reports the R&D results for the conception of a CPS well
adapted for the ALICE-ITS.Comment: 4 pages, 4 figures, VCI 2016 conference proceeding
Integration of statistics and food process engineering: Assessing the uncertainty of thermal processing and shelf-life estimations
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Angular Inflation from Supergravity
We study supergravity inflationary models where inflation is produced along
the angular direction. For this we express the scalar component of a chiral
superfield in terms of the radial and the angular components. We then express
the supergravity potential in a form particularly simple for calculations
involving polynomial expressions for the superpotential and Kahler potential.
We show for a simple Polonyi model the angular direction may give rise to a
stage of inflation when the radial field is fixed to its minimum. We obtain
analytical expressions for all the relevant inflationary quantities and discuss
the possibility of supersymmetry breaking in the radial direction while
inflating by the angular component.Comment: 7 pages, one figure. Final version. Title changed, two figures
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The uncoupling limit of identical Hopf bifurcations with an application to perceptual bistability
We study the dynamics arising when two identical oscillators are coupled near
a Hopf bifurcation where we assume a parameter uncouples the system
at . Using a normal form for identical systems undergoing
Hopf bifurcation, we explore the dynamical properties. Matching the normal form
coefficients to a coupled Wilson-Cowan oscillator network gives an
understanding of different types of behaviour that arise in a model of
perceptual bistability. Notably, we find bistability between in-phase and
anti-phase solutions that demonstrates the feasibility for synchronisation to
act as the mechanism by which periodic inputs can be segregated (rather than
via strong inhibitory coupling, as in existing models). Using numerical
continuation we confirm our theoretical analysis for small coupling strength
and explore the bifurcation diagrams for large coupling strength, where the
normal form approximation breaks down
Local Unitary Quantum Cellular Automata
In this paper we present a quantization of Cellular Automata. Our formalism
is based on a lattice of qudits, and an update rule consisting of local unitary
operators that commute with their own lattice translations. One purpose of this
model is to act as a theoretical model of quantum computation, similar to the
quantum circuit model. It is also shown to be an appropriate abstraction for
space-homogeneous quantum phenomena, such as quantum lattice gases, spin chains
and others. Some results that show the benefits of basing the model on local
unitary operators are shown: universality, strong connections to the circuit
model, simple implementation on quantum hardware, and a wealth of applications.Comment: To appear in Physical Review
When is Containment Decidable for Probabilistic Automata?
The containment problem for quantitative automata is the natural quantitative generalisation of the classical language inclusion problem for Boolean automata. We study it for probabilistic automata, where it is known to be undecidable in general. We restrict our study to the class of probabilistic automata with bounded ambiguity. There, we show decidability (subject to Schanuel's conjecture) when one of the automata is assumed to be unambiguous while the other one is allowed to be finitely ambiguous. Furthermore, we show that this is close to the most general decidable fragment of this problem by proving that it is already undecidable if one of the automata is allowed to be linearly ambiguous
Vector magnetic hysteresis of hard superconductors
Critical state problems which incorporate more than one component for the
magnetization vector of hard superconductors are investigated. The theory is
based on the minimization of a cost functional
which weighs the changes of the magnetic field vector within the sample. We
show that Bean's simplest prescription of choosing the correct sign for the
critical current density in one dimensional problems is just a particular
case of finding the components of the vector . is
determined by minimizing under the constraint , with a bounded set. Upon the selection of
different sets we discuss existing crossed field measurements and
predict new observable features. It is shown that a complex behavior in the
magnetization curves may be controlled by a single external parameter, i.e.:
the maximum value of the applied magnetic field .Comment: 10 pages, 9 figures, accepted in Phys. Rev.
Transition to Chaotic Phase Synchronization through Random Phase Jumps
Phase synchronization is shown to occur between opposite cells of a ring
consisting of chaotic Lorenz oscillators coupled unidirectionally through
driving. As the coupling strength is diminished, full phase synchronization
cannot be achieved due to random generation of phase jumps. The brownian
dynamics underlying this process is studied in terms of a stochastic diffusion
model of a particle in a one-dimensional medium.Comment: Accepted for publication in IJBC, 10 pages, 5 jpg figure
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