316 research outputs found
Optimizing the Access to Healthcare Services in Dense Refugee Hosting Urban Areas: A Case for Istanbul
With over 3.5 million refugees, Turkey continues to host the world's largest
refugee population. This introduced several challenges in many areas including
access to healthcare system. Refugees have legal rights to free healthcare
services in Turkey's public hospitals. With the aim of increasing healthcare
access for refugees, we looked at where the lack of infrastructure is felt the
most. Our study attempts to address these problems by assessing whether Migrant
Health Centers' locations are optimal. The aim of this study is to improve
refugees' access to healthcare services in Istanbul by improving the locations
of health facilities available to them. We used call data records provided by
Turk Telekom.Comment: version to submit for D4R competitio
HSTR-Net: Reference Based Video Super-resolution for Aerial Surveillance with Dual Cameras
Aerial surveillance requires high spatio-temporal resolution (HSTR) video for
more accurate detection and tracking of objects. This is especially true for
wide-area surveillance (WAS), where the surveyed region is large and the
objects of interest are small. This paper proposes a dual camera system for the
generation of HSTR video using reference-based super-resolution (RefSR). One
camera captures high spatial resolution low frame rate (HSLF) video while the
other captures low spatial resolution high frame rate (LSHF) video
simultaneously for the same scene. A novel deep learning architecture is
proposed to fuse HSLF and LSHF video feeds and synthesize HSTR video frames at
the output. The proposed model combines optical flow estimation and
(channel-wise and spatial) attention mechanisms to capture the fine motion and
intricate dependencies between frames of the two video feeds. Simulations show
that the proposed model provides significant improvement over existing
reference-based SR techniques in terms of PSNR and SSIM metrics. The method
also exhibits sufficient frames per second (FPS) for WAS when deployed on a
power-constrained drone equipped with dual cameras.Comment: 15 pages, 8 figures, 8 table
Generalized Sliced Wasserstein Distances
The Wasserstein distance and its variations, e.g., the sliced-Wasserstein
(SW) distance, have recently drawn attention from the machine learning
community. The SW distance, specifically, was shown to have similar properties
to the Wasserstein distance, while being much simpler to compute, and is
therefore used in various applications including generative modeling and
general supervised/unsupervised learning. In this paper, we first clarify the
mathematical connection between the SW distance and the Radon transform. We
then utilize the generalized Radon transform to define a new family of
distances for probability measures, which we call generalized
sliced-Wasserstein (GSW) distances. We also show that, similar to the SW
distance, the GSW distance can be extended to a maximum GSW (max-GSW) distance.
We then provide the conditions under which GSW and max-GSW distances are indeed
distances. Finally, we compare the numerical performance of the proposed
distances on several generative modeling tasks, including SW flows and SW
auto-encoders
Coupling Memory and Computation for Locality Management
We articulate the need for managing (data) locality automatically rather than leaving it to the programmer, especially in parallel programming systems. To this end, we propose techniques for coupling tightly the computation (including the thread scheduler) and the memory manager so that data and computation can be positioned closely in hardware. Such tight coupling of computation and memory management is in sharp contrast with the prevailing practice of considering each in isolation. For example, memory-management techniques usually abstract the computation as an unknown "mutator", which is treated as a "black box". As an example of the approach, in this paper we consider a specific class of parallel computations, nested-parallel computations. Such computations dynamically create a nesting of parallel tasks. We propose a method for organizing memory as a tree of heaps reflecting the structure of the nesting. More specifically, our approach creates a heap for a task if it is separately scheduled on a processor. This allows us to couple garbage collection with the structure of the computation and the way in which it is dynamically scheduled on the processors. This coupling enables taking advantage of locality in the program by mapping it to the locality of the hardware. For example for improved locality a heap can be garbage collected immediately after its task finishes when the heap contents is likely in cache
The role of phase compatibility in martensite
Shape memory alloys inherit their macroscopic properties from their mesoscale
microstructure originated from the martensitic phase transformation. In a cubic
to orthorhombic transition, a single variant of marten- site can have a
compatible (exact) interface with the austenite for some special lattice
parameters in contrast to conventional austenite/twinned martensite interface
with a transition layer. Experimentally, the phase compat- ibility results in a
dramatic drop in thermal hysteresis and gives rise to very stable functional
properties over cycling. Here, we investigate the microstructures observed in
Ti50Ni50-xPdx alloys that undergo a cubic to orthorhombic martensitic
transformation using a three dimensional phase field approach. We will show
that the simulation results are in very good agreement with transmission
electron microscopy observations. However, the understanding of the drop in
thermal hysteresis requires the coupling of phase transformation with plastic
activity. We will discuss this point within the framework of thermoelasticity,
which is a generic feature of the martensitic transformation.Comment: Accepted for publication in in Journal of Applied Physic
High temperature thermoelectric properties of Zn-doped Eu_5In_2Sb_6
The complex bonding environment of many ternary Zintl phases, which often results in low thermal conductivity, makes them strong contenders as thermoelectric materials. Here, we extend the investigation of A_5In_2Sb_6 Zintl compounds with the Ca_5Ga_2As_6 crystal structure to the only known rare-earth analogue: Eu_5In_2Sb_6. Zn-doped samples with compositions of Eu_5In_(2−x)ZnxSb_6 (x = 0, 0.025, 0.05, 0.1, 0.2) were synthesized via ball milling followed by hot pressing. Eu_5In_2Sb_6 showed significant improvements in air stability relative to its alkaline earth metal analogues. Eu5In2Sb6 exhibits semiconducting behavior with possible two band behavior suggested by increasing band mass as a function of Zn content, and two distinct transitions observed in optical absorption measurements (at 0.15 and 0.27 eV). The p-type Hall mobility of Eu_5In_2Sb_6 was found to be much larger than that of the alkaline earth containing A_5In_2Sb_6 phases (A = Sr, Ca) consistent with the reduced hole effective mass (1.1 me). Zn doping was successful in optimizing the carrier concentration, leading to a zT of up to 0.4 at ∼660 K, which is comparable to that of Zn-doped Sr_5In_2Sb_6
Hydrogen gas sensing using aluminum doped ZnO metasurface
Hydrogen sensing is crucial in a wide variety of areas, such as industrial,
environmental, energy and biomedical applications. However, engineering a
practical, reliable, fast, sensitive and cost-effective hydrogen sensor, is a
persistent challenge. Here we demonstrate hydrogen sensing using aluminum-doped
zinc oxide (AZO) metasurfaces based on optical read-out. The proposed sensing
system consists of highly ordered AZO nanotubes (hollow pillars) standing on a
SiO2 layer deposited on a Si wafer. Upon exposure to hydrogen gas, the AZO
nanotube system shows a wavelength shift in the minimum reflectance by 13 nm
within 10 minutes for a hydrogen concentration of 4%. These AZO nanotubes can
also sense the presence of a low concentration (0.7 %) of hydrogen gas within
10 minutes. Its rapid response time even for low concentration, the possibility
of large sensing area fabrication with good precision, and high sensitivity at
room temperature make these highly ordered nanotube structures a promising
miniaturized H2 gas sensor.Comment: 15 pages, 6 figure
CO in Protostars (COPS): -SPIRE Spectroscopy of Embedded Protostars
We present full spectral scans from 200-670m of 26 Class 0+I
protostellar sources, obtained with -SPIRE, as part of the
"COPS-SPIRE" Open Time program, complementary to the DIGIT and WISH Key
programs. Based on our nearly continuous, line-free spectra from 200-670
m, the calculated bolometric luminosities () increase by 50%
on average, and the bolometric temperatures () decrease by 10% on
average, in comparison with the measurements without Herschel. Fifteen
protostars have the same Class using and /. We identify rotational transitions of CO lines from J=4-3 to J=13-12,
along with emission lines of CO, HCO, HO, and [CI]. The ratios
of CO to CO indicate that CO emission remains optically
thick for < 13. We fit up to four components of temperature from
the rotational diagram with flexible break points to separate the components.
The distribution of rotational temperatures shows a primary population around
100 K with a secondary population at 350 K. We quantify the correlations
of each line pair found in our dataset, and find the strength of correlation of
CO lines decreases as the difference between -level between two CO lines
increases. The multiple origins of CO emission previously revealed by
velocity-resolved profiles are consistent with this smooth distribution if each
physical component contributes to a wide range of CO lines with significant
overlap in the CO ladder. We investigate the spatial extent of CO emission and
find that the morphology is more centrally peaked and less bipolar at high-
lines. We find the CO emission observed with SPIRE related to outflows, which
consists two components, the entrained gas and shocked gas, as revealed by our
rotational diagram analysis as well as the studies with velocity-resolved CO
emission.Comment: 50 pages, 18 figures, accepted to ApJS. Revised for Table 6 and
Figure
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