6,555 research outputs found
The improvement of zinc electrodes for electrochemical cells Quarterly report no. 2, Sep. 4 - Dec. 4, 1965
Growth parameters of mossy and crystalline dendrites applied to manufacture and handling of silver-zinc batterie
Improved alkaline electrochemical cell
Addition of lead ions to electrolyte suppresses zinc dendrite formation during charging cycle. A soluble lead salt can be added directly or metallic lead can be incorporated in the zinc electrode and allowed to dissolve into the electrolyte
Scaling Theory of Heat Transport in Quasi-1D Disordered Harmonic Chains
We introduce a variant of the Banded Random Matrix ensemble and show, using
detailed numerical analysis and theoretical arguments, that the phonon heat
current in disordered quasi-one-dimensional lattices obeys a one-parameter
scaling law. The resulting beta-function indicates that an anomalous Fourier
law is applicable in the diffusive regime, while in the localization regime the
heat current decays exponentially with the sample size. Our approach opens a
new way to investigate the effects of Anderson localization in heat conduction,
based on the powerful ideas of scaling theory.Comment: Supplemental Report on calculation of heat current include
First Calorimetric Measurement of OI-line in the Electron Capture Spectrum of Ho
The isotope Ho undergoes an electron capture process with a
recommended value for the energy available to the decay, , of about
2.5 keV. According to the present knowledge, this is the lowest
value for electron capture processes. Because of that, Ho is the best
candidate to perform experiments to investigate the value of the electron
neutrino mass based on the analysis of the calorimetrically measured spectrum.
We present for the first time the calorimetric measurement of the atomic
de-excitation of the Dy daughter atom upon the capture of an electron
from the 5s shell in Ho, OI-line. The measured peak energy is 48 eV.
This measurement was performed using low temperature metallic magnetic
calorimeters with the Ho ion implanted in the absorber.
We demonstrate that the calorimetric spectrum of Ho can be measured
with high precision and that the parameters describing the spectrum can be
learned from the analysis of the data. Finally, we discuss the implications of
this result for the Electron Capture Ho experiment, ECHo, aiming to
reach sub-eV sensitivity on the electron neutrino mass by a high precision and
high statistics calorimetric measurement of the Ho spectrum.Comment: 5 pages, 3 figure
Nonlinear Dynamics of Composite Fermions in Nanostructures
We outline a theory describing the quasi-classical dynamics of composite
fermions in the fractional quantum Hall regime in the potentials of arbitrary
nanostructures. By an appropriate parametrization of time we show that their
trajectories are independent of their mass and dispersion. This allows to study
the dynamics in terms of an effective Hamiltonian although the actual
dispersion is as yet unknown. The applicability of the theory is verified in
the case of antidot arrays where it explains details of magnetoresistance
measurements and thus confirms the existence of these quasiparticles.Comment: submitted to Europhys. Lett., 4 pages, postscrip
Skipping orbits and enhanced resistivity in large-diameter InAs/GaSb antidot lattices
We investigated the magnetotransport properties of high-mobility InAs/GaSb
antidot lattices. In addition to the usual commensurability features at low
magnetic field we found a broad maximum of classical origin around 2.5 T. The
latter can be ascribed to a class of rosetta type orbits encircling a single
antidot. This is shown by both a simple transport calculation based on a
classical Kubo formula and an analysis of the Poincare surface of section at
different magnetic field values. At low temperatures we observe weak
1/B-periodic oscillations superimposed on the classical maximum.Comment: 4 pages, 4 Postscript figures, REVTeX, submitted to Phys Rev
Cryogenic micro-calorimeters for mass spectrometric identification of neutral molecules and molecular fragments
We have systematically investigated the energy resolution of a magnetic
micro-calorimeter (MMC) for atomic and molecular projectiles at impact energies
ranging from to 150 keV. For atoms we obtained absolute energy
resolutions down to eV and relative energy resolutions
down to . We also studied in detail the MMC
energy-response function to molecular projectiles of up to mass 56 u. We have
demonstrated the capability of identifying neutral fragmentation products of
these molecules by calorimetric mass spectrometry. We have modeled the MMC
energy-response function for molecular projectiles and conclude that
backscattering is the dominant source of the energy spread at the impact
energies investigated. We have successfully demonstrated the use of a detector
absorber coating to suppress such spreads. We briefly outline the use of MMC
detectors in experiments on gas-phase collision reactions with neutral
products. Our findings are of general interest for mass spectrometric
techniques, particularly for those desiring to make neutral-particle mass
measurements
The improvement of zinc electrodes for electrochemical cells Quarterly report no. 3, 5 Dec. 1965 - 4 Mar. 1966
Dendrite deposits on zinc electrodes of electrochemical cell and substrate effect
On Approximability of Steiner Tree in -metrics
In the Continuous Steiner Tree problem (CST), we are given as input a set of
points (called terminals) in a metric space and ask for the minimum-cost tree
connecting them. Additional points (called Steiner points) from the metric
space can be introduced as nodes in the solution. In the Discrete Steiner Tree
problem (DST), we are given in addition to the terminals, a set of facilities,
and any solution tree connecting the terminals can only contain the Steiner
points from this set of facilities. Trevisan [SICOMP'00] showed that CST and
DST are APX-hard when the input lies in the -metric (and Hamming
metric). Chleb\'ik and Chleb\'ikov\'a [TCS'08] showed that DST is NP-hard to
approximate to factor of in the graph metric (and
consequently -metric). Prior to this work, it was unclear if CST
and DST are APX-hard in essentially every other popular metric! In this work,
we prove that DST is APX-hard in every -metric. We also prove that CST
is APX-hard in the -metric. Finally, we relate CST and DST,
showing a general reduction from CST to DST in -metrics. As an
immediate consequence, this yields a -approximation polynomial time
algorithm for CST in -metrics.Comment: Abstract shortened due to arxiv's requirement
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