8,081 research outputs found
Power grids vulnerability: a complex network approach
Power grids exhibit patterns of reaction to outages similar to complex
networks. Blackout sequences follow power laws, as complex systems operating
near a critical point. Here, the tolerance of electric power grids to both
accidental and malicious outages is analyzed in the framework of complex
network theory. In particular, the quantity known as efficiency is modified by
introducing a new concept of distance between nodes. As a result, a new
parameter called net-ability is proposed to evaluate the performance of power
grids. A comparison between efficiency and net-ability is provided by
estimating the vulnerability of sample networks, in terms of both the metrics.Comment: 16 pages, 3 figures. Figure 2 and table II modified. Typos corrected.
Version accepted for publication in Chao
Quantifying signals with power-law correlations: A comparative study of detrended fluctuation analysis and detrended moving average techniques
Detrended fluctuation analysis (DFA) and detrended moving average (DMA) are
two scaling analysis methods designed to quantify correlations in noisy
non-stationary signals. We systematically study the performance of different
variants of the DMA method when applied to artificially generated long-range
power-law correlated signals with an {\it a-priori} known scaling exponent
and compare them with the DFA method. We find that the scaling
results obtained from different variants of the DMA method strongly depend on
the type of the moving average filter. Further, we investigate the optimal
scaling regime where the DFA and DMA methods accurately quantify the scaling
exponent , and how this regime depends on the correlations in the
signal. Finally, we develop a three-dimensional representation to determine how
the stability of the scaling curves obtained from the DFA and DMA methods
depends on the scale of analysis, the order of detrending, and the order of the
moving average we use, as well as on the type of correlations in the signal.Comment: 15 pages, 16 figure
In-plane optical spectral weight transfer in optimally doped BiSrCaCuO
We examine the redistribution of the in-plane optical spectral weight in the
normal and superconducting state in tri-layer \bbb (Bi2223) near optimal doping
( = 110 K) on a single crystal via infrared reflectivity and spectroscopic
ellipsometry. We report the temperature dependence of the low-frequency
integrated spectral weight for different values of the cutoff
energy . Two different model-independent analyses consistently show
that for = 1 eV, which is below the charge transfer gap,
increases below , implying the lowering of the kinetic
energy of the holes. This is opposite to the BCS scenario, but it follows the
same trend observed in the bi-layer compound \bb (Bi2212). The size of this
effect is larger in Bi2223 than in Bi2212, approximately scaling with the
critical temperature. In the normal state, the temperature dependence of
is close to up to 300 K
Constraining Scale-Dependent Non-Gaussianity with Future Large-Scale Structure and the CMB
We forecast combined future constraints from the cosmic microwave background
and large-scale structure on the models of primordial non-Gaussianity. We study
the generalized local model of non-Gaussianity, where the parameter f_NL is
promoted to a function of scale, and present the principal component analysis
applicable to an arbitrary form of f_NL(k). We emphasize the complementarity
between the CMB and LSS by using Planck, DES and BigBOSS surveys as examples,
forecast constraints on the power-law f_NL(k) model, and introduce the figure
of merit for measurements of scale-dependent non-Gaussianity.Comment: 28 pages, 8 figures, 2 tables; v2: references update
A bug in the resistance to EGFR inhibitors: is there a role for Mycoplasma and cytidine deaminase in reducing the activity of osimertinib in lung cancer patients?
Thermal gradient-induced forces on geodetic reference masses for LISA
The low frequency sensitivity of space-borne gravitational wave observatories
will depend critically on the geodetic purity of the trajectories of orbiting
test masses. Fluctuations in the temperature difference across the enclosure
surrounding the free-falling test mass can produce noisy forces through several
processes, including the radiometric effect, radiation pressure, and
outgassing. We present here a detailed experimental investigation of thermal
gradient-induced forces for the LISA gravitational wave mission and the LISA
Pathfinder, employing high resolution torsion pendulum measurements of the
torque on a LISA-like test mass suspended inside a prototype of the LISA
gravitational reference sensor that will surround the test mass in orbit. The
measurement campaign, accompanied by numerical simulations of the radiometric
and radiation pressure effects, allows a more accurate and representative
characterization of thermal-gradient forces in the specific geometry and
environment relevant to LISA free-fall. The pressure dependence of the measured
torques allows clear identification of the radiometric effect, in quantitative
agreement with the model developed. In the limit of zero gas pressure, the
measurements are most likely dominated by outgassing, but at a low level that
does not threaten the LISA sensitivity goals.Comment: 21 pages, 16 figures, submitted to Physical Review
Experimental Characterization of a Binary Actuated Parallel Manipulator
This paper describes the BAPAMAN (Binary Actuated Parallel MANipulator) series of parallel manipulators that has been conceived at LARM. Basic common characteristics of BAPAMAN series are described. In particular, it is outlined the use of a reduced number of active degrees of freedom, the use of design solutions with flexural joints and Shape Memory Alloy (SMA) actuators for achieving miniaturization, cost reduction and easy operation features. Given the peculiarities of BAPAMAN architecture, specific experimental tests have been proposed and carried out with the aim to validate the proposed design and to evaluate the practical operation performance and the characteristics of a built prototype, in particular, in terms of operation and workspace characteristics
- …