24,015 research outputs found
An agent-based architecture for managing the provision of community care - the INCA (Intelligent Community Alarm) experience
Community Care is an area that requires extensive cooperation
between independent agencies, each of which needs to meet its own objectives and targets. None are engaged solely in the delivery of community care, and need to integrate the service with their other responsibilities in a coherent and efficient manner. Agent technology provides the means by which effective cooperation can take place without compromising the essential security of both the client and the
agencies involved as the appropriate set of responses can be generated through negotiation between the parties without the need for access to the main information repositories that would be necessary with conventional collaboration models. The autonomous nature of agents also means that a variety of agents can cooperate
together with various local capabilities, so long as they conform to the relevant messaging requirements. This allows a variety of agents, with capabilities tailored to the carers to which they are attached to be developed so that cost-effective solutions can be provided.
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Joint Beamforming and Power Control in Coordinated Multicell: Max-Min Duality, Effective Network and Large System Transition
This paper studies joint beamforming and power control in a coordinated
multicell downlink system that serves multiple users per cell to maximize the
minimum weighted signal-to-interference-plus-noise ratio. The optimal solution
and distributed algorithm with geometrically fast convergence rate are derived
by employing the nonlinear Perron-Frobenius theory and the multicell network
duality. The iterative algorithm, though operating in a distributed manner,
still requires instantaneous power update within the coordinated cluster
through the backhaul. The backhaul information exchange and message passing may
become prohibitive with increasing number of transmit antennas and increasing
number of users. In order to derive asymptotically optimal solution, random
matrix theory is leveraged to design a distributed algorithm that only requires
statistical information. The advantage of our approach is that there is no
instantaneous power update through backhaul. Moreover, by using nonlinear
Perron-Frobenius theory and random matrix theory, an effective primal network
and an effective dual network are proposed to characterize and interpret the
asymptotic solution.Comment: Some typos in the version publised in the IEEE Transactions on
Wireless Communications are correcte
Gamma-ray bursts: postburst evolution of fireballs
The postburst evolution of fireballs that produce -ray bursts is
studied, assuming the expansion of fireballs to be adiabatic and relativistic.
Numerical results as well as an approximate analytic solution for the evolution
are presented. Due to adoption of a new relation among , and
(see the text), our results differ markedly from the previous studies.
Synchrotron radiation from the shocked interstellar medium is attentively
calculated, using a convenient set of equations. The observed X-ray flux of GRB
afterglows can be reproduced easily. Although the optical afterglows seem much
more complicated, our results can still present a rather satisfactory approach
to observations. It is also found that the expansion will no longer be highly
relativistic about 4 days after the main GRB. We thus suggest that the
marginally relativistic phase of the expansion should be investigated so as to
check the afterglows observed a week or more later.Comment: 17 pages, 4 figures, MNRAS in pres
Testing tripartite Mermin inequalities by spectral joint-measurements of qubits
It is well known that Bell inequality supporting the local realism can be
violated in quantum mechanics. Numerous tests of such a violation have been
demonstrated with bipartite entanglements. Using spectral jointmeasurements of
the qubits, we here propose a scheme to test the tripartite Mermin inequality
(a three-qubit Bell-type inequality) with three qubits dispersively-coupled to
a driven cavity. First, we show how to generate a three-qubit
Greenberger-Horne-Zeilinger (GHZ) state by only one-step quantum operation.
Then, spectral joint-measurements are introduced to directly confirm such a
tripartite entanglement. Assisted by a series of single-qubit operations, these
measurements are further utilized to test the Mermin inequality. The
feasibility of the proposal is robustly demonstrated by the present numerical
experiments.Comment: 7pages,3figure
High efficiency tomographic reconstruction of quantum states by quantum nondemolition measurements
We propose a high efficiency tomographic scheme to reconstruct an unknown
quantum state of the qubits by using a series of quantum nondemolition (QND)
measurements. The proposed QND measurements of the qubits are implemented by
probing the the stationary transmissions of the dispersively-coupled resonator.
It is shown that only one kind of QND measurements is sufficient to determine
all the diagonal elements of the density matrix of the detected quantum state.
The remaining non-diagonal elements of the density matrix can be determined by
other spectral measurements by beforehand transferring them to the diagonal
locations using a series of unitary operations. Compared with the pervious
tomographic reconstructions based on the usual destructively projective (DP)
measurements (wherein one kind of such measurements could only determine one
diagonal element of the density matrix), the present approach exhibits
significantly high efficiency for N-qubit (N > 1). Specifically, our generic
proposal is demonstrated by the experimental circuit-quantumelectrodynamics
(circuit-QED) systems with a few Josephson charge qubits.Comment: 9pages,4figure
Global quantum phase diagram and non-Abelian chiral spin liquid in a spin-3/2 square lattice antiferromagnet
Since strong quantum fluctuations are essential for the emergence of quantum
spin liquids, there have been extensive exploration and identification of spin
liquid candidates in spin- systems, while such activities are rare in
higher spin systems. Here we report an example of non-Abelian chiral spin
liquid emerging in spin- Heisenberg model on a square lattice. By tuning
Heisenberg exchange interaction and scalar chirality interaction, we map out a
quantum phase diagram enclosing three conventional magnetic orders and a chiral
spin liquid based on density matrix renormalization group studies. The nature
of the spin liquid is identified as a long-sought bosonic version of
Read-Rezayi state that supports non-Abelian Fibonacci anyonic statistics,
identified by the ground state entanglement spectrum. Significantly, we
establish that the non-Abelian CSL emerges through the enlarged local degrees
of freedom and enhanced quantum fluctuations near the classical phase
boundaries of competing magnetic orders. Our numerical discovery of an exotic
quantum spin liquid in spin- system suggests a new route for discovering
fractionalized quantum phases in frustrated higher spin magnetic compounds.Comment: LA-UR-22-3320
Modeling the Optical Afterglow of GRB 030329
The best-sampled afterglow light curves are available for GRB 030329. A
distinguishing feature of this event is the obvious rebrightening at around 1.6
days after the burst. Proposed explanations for the rebrightening mainly
include the two-component jet model and the refreshed shock model, although a
sudden density-jump in the circumburst environment is also a potential choice.
Here we re-examine the optical afterglow of GRB 030329 numerically in light of
the three models. In the density-jump model, no obvious rebrightening can be
produced at the jump moment. Additionally, after the density jump, the
predicted flux density decreases rapidly to a level that is significantly below
observations. A simple density-jump model thus can be excluded. In the
two-component jet model, although the observed late afterglow (after 1.6 days)
can potentially be explained as emission from the wide-component, the emergence
of this emission actually is too slow and it does not manifest as a
rebrightening as previously expected. The energy-injection model seems to be
the most preferred choice. By engaging a sequence of energy-injection events,
it provides an acceptable fit to the rebrightening at d, as well as
the whole observed light curve that extends to d. Further studies on
these multiple energy-injection processes may provide a valuable insight into
the nature of the central engines of gamma-ray bursts.Comment: 18 pages, 3 figures; a few references added and minor word changes;
now accepted for publication in Ap
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