5,144 research outputs found
Phenomenological Analysis of the Decay $B^{\pm}\to K^{\pm} p {\bar p}
We propose a parametrization for intepreting some of the presently available
data of the decay, in particular those by LHCb
and Belle collaborations. The model is inspired by the well-known current and
transition contributions, usually assumed in this kind of decay. However, in
the light of considerations about the dominant graphs and about final state
interactions, we modify some parameters of the model, determining them by means
of a best fit to data. We show the results, which we discuss in some detail.
Moreover we give some predictions on other observables relative to the decays.Comment: 19 pages, 5 figures in EPJC 201
An Analytical Solution for Probabilistic Guarantees of Reservation Based Soft Real-Time Systems
We show a methodology for the computation of the probability of deadline miss
for a periodic real-time task scheduled by a resource reservation algorithm. We
propose a modelling technique for the system that reduces the computation of
such a probability to that of the steady state probability of an infinite state
Discrete Time Markov Chain with a periodic structure. This structure is
exploited to develop an efficient numeric solution where different
accuracy/computation time trade-offs can be obtained by operating on the
granularity of the model. More importantly we offer a closed form conservative
bound for the probability of a deadline miss. Our experiments reveal that the
bound remains reasonably close to the experimental probability in one real-time
application of practical interest. When this bound is used for the optimisation
of the overall Quality of Service for a set of tasks sharing the CPU, it
produces a good sub-optimal solution in a small amount of time.Comment: IEEE Transactions on Parallel and Distributed Systems, Volume:27,
Issue: 3, March 201
Bi-Hamiltonian Aspects of a Matrix Harry Dym Hierarchy
We study the Harry Dym hierarchy of nonlinear evolution equations from the
bi-Hamiltonian view point. This is done by using the concept of an S-hierarchy.
It allows us to define a matrix Harry Dym hierarchy of commuting Hamiltonian
flows in two fields that projects onto the scalar Harry Dym hierarchy. We also
show that the conserved densities of the matrix Harry Dym equation can be found
by means of a Riccati-type equation.Comment: Revised version, 22 pages; a section on reciprocal transformations
added. To appear in J. Math. Phys
A Software-based Low-Jitter Servo Clock for Inexpensive Phasor Measurement Units
This paper presents the design and the implementation of a servo-clock (SC)
for low-cost Phasor Measurement Units (PMUs). The SC relies on a classic
Proportional Integral (PI) controller, which has been properly tuned to
minimize the synchronization error due to the local oscillator triggering the
on-board timer. The SC has been implemented into a PMU prototype developed
within the OpenPMU project using a BeagleBone Black (BBB) board. The
distinctive feature of the proposed solution is its ability to track an input
Pulse-Per-Second (PPS) reference with good long-term stability and with no need
for specific on-board synchronization circuitry. Indeed, the SC implementation
relies only on one co-processor for real-time application and requires just an
input PPS signal that could be distributed from a single substation clock
Beyond Zipf's Law: The Lavalette Rank Function and its Properties
Although Zipf's law is widespread in natural and social data, one often
encounters situations where one or both ends of the ranked data deviate from
the power-law function. Previously we proposed the Beta rank function to
improve the fitting of data which does not follow a perfect Zipf's law. Here we
show that when the two parameters in the Beta rank function have the same
value, the Lavalette rank function, the probability density function can be
derived analytically. We also show both computationally and analytically that
Lavalette distribution is approximately equal, though not identical, to the
lognormal distribution. We illustrate the utility of Lavalette rank function in
several datasets. We also address three analysis issues on the statistical
testing of Lavalette fitting function, comparison between Zipf's law and
lognormal distribution through Lavalette function, and comparison between
lognormal distribution and Lavalette distribution.Comment: 15 pages, 4 figure
Once burned, twice shy. The use of compromissory clauses before the International Court of Justice and their declining popularity in new treaties
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