24,688 research outputs found
Voltage-Mode Highpass, Bandpass, Lowpass and Notch Biquadratic Filters Using Single DDCC
A new voltage-mode multifunction biquadratic filter using one differential difference current conveyor (DDCC), two grounded capacitors and three resistors is presented. The proposed circuit offers the following attractive advantages: realizing highpass, bandpass, lowpass and notch filter functions, simultaneously, from the same circuit configuration; employing grounded capacitors, which is ideal for integration and simpler circuit configuration
Anapole Dark Matter
We consider dark matter (DM) that interacts with ordinary matter exclusively
through an electromagnetic anapole, which is the only allowed electromagnetic
form factor for Majorana fermions. We show that unlike DM particles with an
electric or magnetic dipole moment, anapole dark matter particles annihilate
exclusively into fermions via purely p-wave interactions, while tree-level
annihilations into photons are forbidden. We calculate the anapole moment
needed to produce a thermal relic abundance in agreement with cosmological
observations, and show that it is consistent with current XENON100 detection
limits on the DM-nucleus cross-section for all masses, while lying just below
the detection threshold for a mass ~ 30-40 GeV.Comment: 7 pages, 5 figures, v3: version to appear in PL
A note on Neuberger's double pass algorithm
We analyze Neuberger's double pass algorithm for the matrix-vector
multiplication R(H).Y (where R(H) is (n-1,n)-th degree rational polynomial of
positive definite operator H), and show that the number of floating point
operations is independent of the degree n, provided that the number of sites is
much larger than the number of iterations in the conjugate gradient. This
implies that the matrix-vector product can be approximated to very high precision with sufficiently large n,
without noticeably extra costs. Further, we show that there exists a threshold
such that the double pass is faster than the single pass for , where for most platforms.Comment: 18 pages, v3: CPU time formulas are obtained, to appear in Physical
Review
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The Approach of Complex Insert Packaging Fabrication in Stereolithography
The approach of complex insert packaging fabrication in stereolithography is studied in the
paper. There are many difficulties being overcome, such as the dispensing shadowing problem
caused by the geometric shape of insert, the polymer feeding problem caused by greater insert
height than the layer thickness, and the positioning problem of insert that leads to instability of
packaging. These drawbacks led to unsatisfactory results of the insert packaging in
stereolithography. In order to solve the problems, a new method of complex inserts
packaging fabrication in stereolithography is proposed in this paper. Based on the geometric
information, function and assembly direction of the inserts, the packaging approach is developed.
The approach proposed in this paper has been verified by experiments. It brings considerable
contributions to the application of insert packaging in stereolithography. It is also favorable to
the improvement of insert packaging efficiency and assembly fabricationMechanical Engineerin
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The effect of surface heterogeneity on cloud absorption estimates
This study presents a systematic and quantitative analysis of the effect of inhomogeneous surface albedo on shortwave cloud absorption estimates. We used 3D radiative transfer modeling over a checkerboard surface albedo to calculate cloud absorption. We have found that accounting for surface heterogeneity enhances cloud absorption. However, the enhancement is not sufficient to explain the reported difference between measured and modeled cloud absorption
TeV scale Dark Matter and electroweak radiative corrections
Recent anomalies in cosmic rays data, namely from the PAMELA collaboration,
can be interpreted in terms of TeV scale decaying/annihilating Dark Matter. We
analyze the impact of radiative corrections coming from the electroweak sector
of the Standard Model on the spectrum of the final products at the interaction
point. As an example, we consider virtual one loop corrections and real gauge
bosons emission in the case of a very heavy vector boson annihilating into
fermions. We show that the effect of electroweak corrections is relevant, but
not as big as sometimes claimed in the literature. At such high scales, one
loop electroweak effects are so big that eventually higher orders/resummations
have to be considered: we advocate for the inclusion of these effects in parton
shower Montecarlos aiming at the description of TeV scale physics.Comment: Comments added, published versio
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