905 research outputs found
Hypernuclear No-Core Shell Model
We extend the No-Core Shell Model (NCSM) methodology to incorporate
strangeness degrees of freedom and apply it to single- hypernuclei.
After discussing the transformation of the hyperon-nucleon (YN) interaction
into Harmonic-Oscillator (HO) basis and the Similarity Renormalization Group
transformation applied to it to improve model-space convergence, we present two
complementary formulations of the NCSM, one that uses relative Jacobi
coordinates and symmetry-adapted basis states to fully exploit the symmetries
of the hypernuclear Hamiltonian, and one working in a Slater determinant basis
of HO states where antisymmetrization and computation of matrix elements is
simple and to which an importance-truncation scheme can be applied. For the
Jacobi-coordinate formulation, we give an iterative procedure for the
construction of the antisymmetric basis for arbitrary particle number and
present the formulae used to embed two- and three-baryon interactions into the
many-body space. For the Slater-determinant formulation, we discuss the
conversion of the YN interaction matrix elements from relative to
single-particle coordinates, the importance-truncation scheme that tailors the
model space to the description of the low-lying spectrum, and the role of the
redundant center-of-mass degrees of freedom. We conclude with a validation of
both formulations in the four-body system, giving converged ground-state
energies for a chiral Hamiltonian, and present a short survey of the
hyper-helium isotopes.Comment: 17 pages, 8 figures; accepted versio
Derandomized Distributed Multi-resource Allocation with Little Communication Overhead
We study a class of distributed optimization problems for multiple shared
resource allocation in Internet-connected devices. We propose a derandomized
version of an existing stochastic additive-increase and multiplicative-decrease
(AIMD) algorithm. The proposed solution uses one bit feedback signal for each
resource between the system and the Internet-connected devices and does not
require inter-device communication. Additionally, the Internet-connected
devices do not compromise their privacy and the solution does not dependent on
the number of participating devices. In the system, each Internet-connected
device has private cost functions which are strictly convex, twice continuously
differentiable and increasing. We show empirically that the long-term average
allocations of multiple shared resources converge to optimal allocations and
the system achieves minimum social cost. Furthermore, we show that the proposed
derandomized AIMD algorithm converges faster than the stochastic AIMD algorithm
and both the approaches provide approximately same solutions
Alleviating a form of electric vehicle range anxiety through On-Demand vehicle access
On-demand vehicle access is a method that can be used to reduce types of
range anxiety problems related to planned travel for electric vehicle owners.
Using ideas from elementary queueing theory, basic QoS metrics are defined to
dimension a shared fleet to ensure high levels of vehicle access. Using
mobility data from Ireland, it is argued that the potential cost of such a
system is very low
Communication-efficient Distributed Multi-resource Allocation
In several smart city applications, multiple resources must be allocated
among competing agents that are coupled through such shared resources and are
constrained --- either through limitations of communication infrastructure or
privacy considerations. We propose a distributed algorithm to solve such
distributed multi-resource allocation problems with no direct inter-agent
communication. We do so by extending a recently introduced additive-increase
multiplicative-decrease (AIMD) algorithm, which only uses very little
communication between the system and agents. Namely, a control unit broadcasts
a one-bit signal to agents whenever one of the allocated resources exceeds
capacity. Agents then respond to this signal in a probabilistic manner. In the
proposed algorithm, each agent makes decision of its resource demand locally
and an agent is unaware of the resource allocation of other agents. In
empirical results, we observe that the average allocations converge over time
to optimal allocations.Comment: To appear in IEEE International Smart Cities Conference (ISC2 2018),
Kansas City, USA, September, 2018. arXiv admin note: substantial text overlap
with arXiv:1711.0197
On the Design of Campus Parking Systems with QoS guarantees
Parking spaces are resources that can be pooled together and shared,
especially when there are complementary day-time and night-time users. We
answer two design questions. First, given a quality of service requirement, how
many spaces should be set aside as contingency during day-time for night-time
users? Next, how can we replace the first-come-first-served access method by
one that aims at optimal efficiency while keeping user preferences private
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