4,870 research outputs found
Real-time Information, Uncertainty and Quantum Feedback Control
Feedback is the core concept in cybernetics and its effective use has made
great success in but not limited to the fields of engineering, biology, and
computer science. When feedback is used to quantum systems, two major types of
feedback control protocols including coherent feedback control (CFC) and
measurement-based feedback control (MFC) have been developed. In this paper, we
compare the two types of quantum feedback control protocols by focusing on the
real-time information used in the feedback loop and the capability in dealing
with parameter uncertainty. An equivalent relationship is established between
quantum CFC and non-selective quantum MFC in the form of operator-sum
representation. Using several examples of quantum feedback control, we show
that quantum MFC can theoretically achieve better performance than quantum CFC
in stabilizing a quantum state and dealing with Hamiltonian parameter
uncertainty. The results enrich understanding of the relative advantages
between quantum MFC and quantum CFC, and can provide useful information in
choosing suitable feedback protocols for quantum systems.Comment: 24 page
Solving multiple-criteria R&D project selection problems with a data-driven evidential reasoning rule
In this paper, a likelihood based evidence acquisition approach is proposed
to acquire evidence from experts'assessments as recorded in historical
datasets. Then a data-driven evidential reasoning rule based model is
introduced to R&D project selection process by combining multiple pieces of
evidence with different weights and reliabilities. As a result, the total
belief degrees and the overall performance can be generated for ranking and
selecting projects. Finally, a case study on the R&D project selection for the
National Science Foundation of China is conducted to show the effectiveness of
the proposed model. The data-driven evidential reasoning rule based model for
project evaluation and selection (1) utilizes experimental data to represent
experts' assessments by using belief distributions over the set of final
funding outcomes, and through this historic statistics it helps experts and
applicants to understand the funding probability to a given assessment grade,
(2) implies the mapping relationships between the evaluation grades and the
final funding outcomes by using historical data, and (3) provides a way to make
fair decisions by taking experts' reliabilities into account. In the
data-driven evidential reasoning rule based model, experts play different roles
in accordance with their reliabilities which are determined by their previous
review track records, and the selection process is made interpretable and
fairer. The newly proposed model reduces the time-consuming panel review work
for both managers and experts, and significantly improves the efficiency and
quality of project selection process. Although the model is demonstrated for
project selection in the NSFC, it can be generalized to other funding agencies
or industries.Comment: 20 pages, forthcoming in International Journal of Project Management
(2019
Improving Accuracy of Virtual Machine Power Model by Relative-PMC Based Heuristic Scheduling
Conventional utilization-based power model is effective for measuring the power consumption of physical machines. However, in virtualized environments its accuracy cannot be guaranteed because of the recursive resource accessing among multiple virtual machines. In this paper, we present a novel virtual machine scheduling algorithm, which uses Performance-Monitor-Counter as heuristic information to compensate the recursive power consumption. Theoretical analysis indicates that the error of virtual machine power model can be quantitative bounded when using the proposed scheduling algorithm. Extensive experiments based on standard benchmarks show that the error of virtual machine power measurements can be significantly reduced comparing with the classic credit-based scheduling algorithm
Low-mass Active Galactic Nuclei on the Fundamental Plane of Black Hole Activity
It is widely known that in active galactic nuclei (AGNs) and black hole X-ray
binaries (BHXBs), there is a tight correlation among their radio luminosity
(), X-ray luminosity () and BH mass (\mbh), the so-called
`fundamental plane' (FP) of BH activity. Yet the supporting data are very
limited in the \mbh regime between stellar mass (i.e., BHXBs) and
10\,\msun\ (namely, the lower bound of supermassive BHs in common
AGNs). In this work, we developed a new method to measure the 1.4 GHz flux
directly from the images of the VLA FIRST survey, and apply it to the type-1
low-mass AGNs in the \cite{2012ApJ...755..167D} sample. As a result, we
obtained 19 new low-mass AGNs for FP research with both \mbh\ estimates (\mbh
\approx 10^{5.5-6.5}\,\msun), reliable X-ray measurements, and (candidate)
radio detections, tripling the number of such candidate sources in the
literature.Most (if not all) of the low-mass AGNs follow the standard
radio/X-ray correlation and the universal FP relation fitted with the combined
dataset of BHXBs and supermassive AGNs by \citet{2009ApJ...706..404G}; the
consistency in the radio/X-ray correlation slope among those accretion systems
supports the picture that the accretion and ejection (jet) processes are quite
similar in all accretion systems of different \mbh. In view of the FP relation,
we speculate that the radio loudness (i.e., the luminosity ratio
of the jet to the accretion disk) of AGNs depends not only on Eddington ratio,
but probably also on \mbh.Comment: ApJ accepte
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