760 research outputs found
Reconstructing cosmic growth with kSZ observations in the era of Stage IV experiments
Future ground-based CMB experiments will generate competitive large-scale
structure datasets by precisely characterizing CMB secondary anisotropies over
a large fraction of the sky. We describe a method for constraining the growth
rate of structure to sub-1% precision out to , using a combination
of galaxy cluster peculiar velocities measured using the kinetic
Sunyaev-Zel'dovich (kSZ) effect, and the velocity field reconstructed from
galaxy redshift surveys. We consider only thermal SZ-selected cluster samples,
which will consist of sources for Stage 3 and 4 CMB
experiments respectively. Three different methods for separating the kSZ effect
from the primary CMB are compared, including a novel blind "constrained
realization" method that improves signal-to-noise by a factor of over
a commonly-used aperture photometry technique. Measurements of the integrated
tSZ -parameter are used to break the kSZ velocity-optical depth degeneracy,
and the effects of including CMB polarization and SZ profile uncertainties are
also considered. A combination of future Stage 4 experiments should be able to
measure the product of the growth and expansion rates, , to
better than 1% in bins of out to -- competitive
with contemporary redshift-space distortion constraints from galaxy surveys.Comment: 16 pages, 8 figure
Towards a cosmological neutrino mass detection
Future cosmological measurements should enable the sum of neutrino masses to
be determined indirectly through their effects on the expansion rate of the
Universe and the clustering of matter. We consider prospects for the
gravitationally lensed Cosmic Microwave Background anisotropies and Baryon
Acoustic Oscillations in the galaxy distribution, examining how the projected
uncertainty of meV on the neutrino mass sum (a 4 detection
of the minimal mass) might be reached over the next decade. The current
1 uncertainty of meV (Planck-2015+BAO-15) will be
improved by upcoming 'Stage-3' CMB experiments (S3+BAO-15: 44 meV), then
upcoming BAO measurements (S3+DESI: 22 meV), and planned next-generation 'Stage
4' CMB experiments (S4+DESI: 15-19 meV, depending on angular range). An
improved optical depth measurement is important: the projected neutrino mass
uncertainty increases to meV if S4 is limited to and combined
with current large-scale polarization data. Looking beyond CDM,
including curvature uncertainty increases the forecast mass error by
50% for S4+DESI, and more than doubles the error with a two-parameter dark
energy equation of state. Complementary low-redshift probes including galaxy
lensing will play a role in distinguishing between massive neutrinos and a
departure from a , flat geometry.Comment: Submitted to PRD. 15 pages, 10 figure
Lensing Simulation and Power Spectrum Estimation for High Resolution CMB Polarization Maps
We present efficient algorithms for CMB lensing simulation and power spectrum
es- timation for flat-sky CMB polarization maps. We build a pure B-mode
estimator to remedy E to B leakage due to partial sky coverage. We show that
our estimators are unbiased, and consistent with the projected errors. We
demonstrate our algorithm using simulated observations of small sky patches
with realistic noise and weights for upcoming CMB polarization experiments.Comment: 11 pages, 6 figure
Solving a Continent-Scale Inventory Routing Problem at Renault
This paper is the fruit of a partnership with Renault. Their backward
logistic requires to solve a continent-scale multi-attribute inventory routing
problem (IRP). With an average of 30 commodities, 16 depots, and 600 customers
spread across a continent, our instances are orders of magnitude larger than
those in the literature. Existing algorithms do not scale. We propose a large
neighborhood search (LNS). To make it work, (1) we generalize existing split
delivery vehicle routing problem and IRP neighborhoods to this context, (2) we
turn a state-of-the art matheuristic for medium-scale IRP into a large
neighborhood, and (3) we introduce two novel perturbations: the reinsertion of
a customer and that of a commodity into the IRP solution. We also derive a new
lower bound based on a flow relaxation. In order to stimulate the research on
large-scale IRP, we introduce a library of industrial instances. We benchmark
our algorithms on these instances and make our code open-source. Extensive
numerical experiments highlight the relevance of each component of our LNS
Simultaneous Rheoelectric Measurements of Strongly Conductive Complex Fluids
We introduce an modular fixture designed for stress-controlled rheometers to perform simultaneous rheological and electrical measurements on strongly conductive complex fluids under shear. By means of a nontoxic liquid metal at room temperature, the electrical connection to the rotating shaft is completed with minimal additional mechanical friction, allowing for simultaneous stress measurements at values as low as 1 Pa. Motivated by applications such as flow batteries, we use the capabilities of this design to perform an extensive set of rheoelectric experiments on gels formulated from attractive carbon-black particles, at concentrations ranging from 4 to 15 wtâ%. First, experiments on gels at rest prepared with different shear histories show a robust power-law scaling between the elastic modulus G[superscript '][subscript 0] and the conductivity Ï[subscript 0] of the gelsâi.e., G[superscript '][subscript 0]âŒÏ[superscript α][subscript 0], with α=1.65±0.04, regardless of the gel concentration. Second, we report conductivity measurements performed simultaneously with creep experiments. Changes in conductivity in the early stage of the experiments, also known as the Andrade-creep regime, reveal for the first time that plastic events take place in the bulk, while the shear rate [dot over Îł] decreases as a weak power law of time. The subsequent evolution of the conductivity and the shear rate allows us to propose a local yielding scenario that is in agreement with previous velocimetry measurements. Finally, to establish a set of benchmark data, we determine the constitutive rheological and electrical behavior of carbon-black gels. Corrections first introduced for mechanical measurements regarding shear inhomogeneity and wall slip are carefully extended to electrical measurements to accurately distinguish between bulk and surface contributions to the conductivity. As an illustrative example, we examine the constitutive rheoelectric properties of five different grades of carbon-black gels and we demonstrate the relevance of this rheoelectric apparatus as a versatile characterization tool for strongly conductive complex fluids and their applications.United States. Dept. of Energy. Office of Basic Energy Sciences. Joint Center for Energy Storage ResearchMIT-France Seed FundCentre National de la Recherche Scientifique (France) (PICS-USA Scheme 36939
Cutting Forces in basic and real life wood machining processes review, COST Action E35 2004-2008: Wood machining - Micromechanics and fracture
International audienceThe data available in the literature concerning wood cutting forces permit to build models or to simulate the main wood machining processes (milling, sawing, peeling etc.). This approach contributes to a better understanding of formation of wood surfaces and chips and the data may be helpful to optimize cutting geometry, reduce tool wear, improve tool material, and to size tool-machines. The models may also be useful for industrial application in two ways: (1) providing data to optimise the settings for a given operation (batch approach) and (2) building predictive models that could be the basis of an online control systems for the machining processes (interactive approach). A prerequisite for this is that numerous machining tests on different wood materials are performed based on experiences with different kind of tools and experimental devices. With potential industrial applications in focus, the emphasis of this review was on the wood peeling process, which is a very demanding special case of wood cutting. Though not so many industrial machines are equipped with expensive force sensors, there is a lot of high quality information available about cutting forces which may be useful to improve the scientific or technologic knowledge in wood machining. Alternative parameters, such as vibration or sound measurements, appear to be promising substitutes in the praxis, particularly to feed online control systems of any wood cutting process
Assessing consistency between CMB temperature and polarization measurements, with application to Planck, ACT and SPT
Planck's Cosmic Microwave Background temperature and polarization
observations are the premier dataset for constraining cosmological models.
Cosmic variance limited temperature at large and intermediate scales today
dominates the constraints; polarization provides additional constraining power
and further scrutiny of the models. To complete this picture from Planck,
ground-based experiments, such as the Atacama Cosmology Telescope (ACT) and the
South Pole Telescope (SPT) continue to add temperature and polarization
measurements at small scales, allowing for the extraction of competitive
cosmological constraints from the and power spectra. Matching at the
same time all these stringent probes is a key challenge and validation step for
any cosmological model. In particular, CDM requires a tight
consistency between the temperature and polarization measurements. In this
paper, we present a number of methods to identify and quantify possible
inconsistencies between temperature and polarization, we apply them to the
latest Planck, ACT and SPT data and find no evidence for a deviation from
CDM. Application of these methods will have increased importance for
future, more constraining CMB data.Comment: 13 pages, 11 figure
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