4,715 research outputs found
The "MIND" Scalable PIM Architecture
MIND (Memory, Intelligence, and Network Device) is an advanced parallel computer architecture for high performance computing and scalable embedded processing. It is a
Processor-in-Memory (PIM) architecture integrating both DRAM bit cells and CMOS logic devices on the same silicon die. MIND is multicore with multiple memory/processor nodes on
each chip and supports global shared memory across systems of MIND components. MIND is distinguished from other PIM architectures in that it incorporates mechanisms for efficient support of a global parallel execution model based on the semantics of message-driven multithreaded split-transaction processing. MIND is designed to operate either in conjunction with other conventional microprocessors or in standalone arrays of like devices. It also incorporates mechanisms for fault tolerance, real time execution, and active power management. This paper describes the major elements and operational methods of the MIND
architecture
Fine-To-Coarse Global Registration of RGB-D Scans
RGB-D scanning of indoor environments is important for many applications,
including real estate, interior design, and virtual reality. However, it is
still challenging to register RGB-D images from a hand-held camera over a long
video sequence into a globally consistent 3D model. Current methods often can
lose tracking or drift and thus fail to reconstruct salient structures in large
environments (e.g., parallel walls in different rooms). To address this
problem, we propose a "fine-to-coarse" global registration algorithm that
leverages robust registrations at finer scales to seed detection and
enforcement of new correspondence and structural constraints at coarser scales.
To test global registration algorithms, we provide a benchmark with 10,401
manually-clicked point correspondences in 25 scenes from the SUN3D dataset.
During experiments with this benchmark, we find that our fine-to-coarse
algorithm registers long RGB-D sequences better than previous methods
Analysis of an atomistic model for anti-plane fracture
We develop a model for an anti-plane crack defect posed on a square lattice
under an interatomic pair-potential with nearest-neighbour interactions. In
particular, we establish existence, local uniqueness and stability of solutions
for small loading parameters and further prove qualitatively sharp far-field
decay estimates. The latter requires establishing decay estimates for the
corresponding lattice Green's function, which are of independent interest
The DLR Complex Irradiation Facility (CIF)
The DLR Institute of Space Systems in Bremen has built a new facility to study the behavior of materials under complex irradiation and to estimate their degradation in a space environment. It is named Complex Irradiation Facility (CIF). CIF allows simultaneously irradiating samples with three light sources for the simulation of the spectrum of solar electromagnetic radiation. The light sources are a solar simulator with a Xe-lamp (wavelength range 300-1200nm), a deuterium-UV-source (112-200nm), and an Argon-gas-jet-VUV-simulator. The latter allows irradiating samples with shorter wavelengths below the limitation of any window material. The VUV-simulator has been validated at the PTB (Physikalisch Technische Bundesanstalt) in Berlin by calibration that uses synchrotron radiation in the wavelength range between 40 and 400nm. Beside the different light sources CIF provides also electron and proton sources. Electrons and protons are generated in a low energy range from 1 to 10 keV with currents from 1 to 100 nA and in a higher range from 10 to 100 keV with 0.1 to 100 ”A. Both particle sources can be operated simultaneously. In order to model temperature variations as appear in free space, the sample can be cooled down to liquid Nitrogen and heated up to about 450 K during irradiation.
The complete facility has been manufactured in UHV-technology with metal sealing. It is free of organic compounds to avoid self-contamination. The different pumping systems achieve a final pressure of 1*1010 mbar (empty sample chamber)
Besides the installed radiation sensors that control the stability of the various radiation sources and an attached mass spectrometer for analyzing the outgassing processes in the chamber, the construction of CIF allows adding other in-situ measurement systems to measure parameters that are of the userâs interest. We are currently planning to develop an in-situ measurement system in order to determine changes in the optical properties of the samples caused by irradiation. Within this paper we will show the design of CIF in more detail and discuss the performance of the various radiation sources
Analysis of cell size effects in atomistic crack propagation
We consider crack propagation in a crystalline material in terms of bifurcation analysis. We provide evidence that the stress intensity factor is a natural bifurcation parameter, and that the resulting bifurcation diagram is a periodic "snaking curve". We then prove qualitative properties of the equilibria and convergence rates of finite-cell approximations to the "exact" bifurcation diagram
Is the Two Micron all Sky Survey Clustering Dipole Convergent?
There is a long-standing controversy about the convergence of the dipole moment of the galaxy angular distribution
(the so-called clustering dipole). Is the dipole convergent at all, and if so, what is the scale of the convergence?
We study the growth of the clustering dipole of galaxies as a function of the limiting flux of the sample from the
Two Micron All Sky Survey (2MASS). Contrary to some earlier claims, we find that the dipole does not converge
before the completeness limit of the 2MASS Extended Source Catalog, i.e., up to 13.5 mag in the near-infrared K_s
band (equivalent to an effective distance of 300 Mpc h
^(â1)). We compare the observed growth of the dipole with the theoretically expected, conditional one (i.e., given the velocity of the Local Group relative to the cosmic microwave background), for the ÎCDM power spectrum and cosmological parameters constrained by the Wilkinson Microwave Anisotropy Probe. The observed growth turns out to be within 1Ï confidence level of its theoretical counterpart once the proper observational window of the 2MASS flux-limited catalog is included. For a contrast, if the adopted window is a top hat, then the predicted dipole grows significantly faster and converges (within the errors) to its final value for a distance of about 300 Mpc h
^(â1). By comparing the observational windows, we show that for a given flux limit and a corresponding distance limit, the 2MASS flux-weighted window passes less large-scale signal than the top-hat one. We conclude that the growth of the 2MASS dipole for effective distances greater than 200 Mpc h^(â1) is only apparent. On the other hand, for a distance of 80 Mpc h^(â1) (mean depth of the 2MASS Redshift Survey) and the ÎCDM power spectrum, the true dipole is expected to reach only ~80% of its final value. Eventually, since for the window function of 2MASS the predicted growth is consistent with the observed one, we can compare the
two to evaluate ÎČ âĄ Î©^(0.55)_m /b. The result is ÎČ = 0.38 ± 0.04, which leads to an estimate of the density parameter
Ω_m = 0.20 ± 0.08
Design and performance of a vacuum-UV simulator for material testing under space conditions
This paper describes the construction and performance of a VUV-simulator that
has been designed to study degradation of materials under space conditions. It
is part of the Complex Irradiation Facility at DLR in Bremen, Germany, that has
been built for testing of material under irradiation in the complete UV-range
as well as under proton and electron irradiation. Presently available
UV-sources used for material tests do not allow the irradiation with
wavelengths smaller than about nm where common Deuterium lamps show an
intensity cut-off. The VUV-simulator generates radiation by excitation of a
gas-flow with an electron beam. The intensity of the radiation can be varied by
manipulating the gas-flow and/or the electron beam.
The VUV simulator has been calibrated at three different gas-flow settings in
the range from nm to nm. The calibration has been made by the
Physikalisch-Technische Bundesanstalt (PTB) in Berlin. The measured spectra
show total irradiance intensities from to mW (see Table
4.2) in the VUV-range, i.e. for wavelengths smaller than nm. They exhibit
a large number of spectral lines generated either by the gas-flow constituents
or by metal atoms in the residual gas which come from metals used in the source
construction. In the range from nm to nm where Deuterium lamps are
not usable, acceleration factors of to Solar Constants are reached
depending on the gas-flow setting. The VUV-simulator allows studies of general
degradation effects caused by photoionization and photodissociation as well as
accelerated degradation tests by use of intensities that are significantly
higher compared to that of the Sun at AU
Impact of tunnel barrier strength on magnetoresistance in carbon nanotubes
We investigate magnetoresistance in spin valves involving CoPd-contacted
carbon nanotubes. Both temperature and bias voltage dependence clearly indicate
tunneling magnetoresistance as the origin. We show that this effect is
significantly affected by the tunnel barrier strength, which appears to be one
reason for the variation between devices previously detected in similar
structures. Modeling the data by means of the scattering matrix approach, we
find a non-trivial dependence of the magnetoresistance on the barrier strength.
Furthermore, analysis of the spin precession observed in a nonlocal Hanle
measurement yields a spin lifetime of ns, a value comparable
with those found in silicon- or graphene-based spin valve devices.Comment: 10 pages, 5 figures, 1 tabl
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