6,437 research outputs found
Task complexity analysis and QoS management for mapping dynamic video-processing tasks on a multi-core platform
This paper addresses efficient mapping and reconfiguration of advanced video applications onto a general purpose multi-core platform. By accurately modeling the resource usage for an application, allocation of processing resources on the platform can be based on the actually needed resources instead of a worst-case approach, thereby improving Quality-of-Service (QoS). Here, we exploit a new and strongly upcoming class of dynamic video applications based on image and content analysis for resource management and control. Such applications are characterized by irregular computing behavior and memory usage. It is shown that with linear models and statistical techniques based on the Markov modeling, a rather good accuracy (94–97%) for predicting the resource usage can be obtained. This prediction accuracy is so good that it allows resource prediction at runtime, thereby leading to an actively controlled system management
X-ray CT on the GPU
Nondestructive testing (NDT) is a collection of analysis techniques used by scientists and technologists as a way of analyzing the interior of an object without damaging the object. Since the analysis is done without damaging the object, NDT is an extremely valuable technique used in various industries for troubleshooting and research. CNDE has a long history of working with a variety of industrial sectors which include Aerospace (commercial and military aviation) and Defense Systems (ground vehicles and personnel protection); Energy (nuclear, wind, fossil); Infrastructure and Transportation (bridges, roadways, dams, levees); and Petro-Chemical (offshore, processing, fuel transport piping) to provide cost-effective tools and solutions. X-ray tomography is the procedure of using X-rays for generating tomographic slices of the required object. The object is bombarded with X-rays and the scanned image intensity values are collected on a detector. A significant drawback in X-ray tomography is the amount of data collected. It is generally huge in the order of gigabytes and hence the processing of data presents a big challenge. One way to speed up the processing of data is to run the programs on a cluster. CNDE uses a 64 node Beowulf cluster to do the reconstruction of an image. However with the advent of the GPU (Graphic Processing Unit) we have a far more cost efficient and time efficient hardware to run the reconstruction algorithm. The GPU can be fitted into a single PC, costs 10 times less than the cluster and also has a longer life time. This thesis has two major components to it. One of it is the desvelopment of new preprocessing and post processing techniques (includes filters, hot pixel removal etc.) to improve the quality of the input data and the other is the implementation of these techniques as well as the reconstruction program on the GPU using CUDA. Speedup on the GPU is not just a matter of porting the developed algorithms in parallel onto the hardware like in a cluster. GPU architecture is extremely complex and involves the usage of many different types of memory each with its own advantages and disadvantages and also many other optimization techniques for accessing and processing the data. These new techniques as well as the introduction of GPU are a significant addition to X-ray program here at CNDE
Interactive Visualization of the Largest Radioastronomy Cubes
3D visualization is an important data analysis and knowledge discovery tool,
however, interactive visualization of large 3D astronomical datasets poses a
challenge for many existing data visualization packages. We present a solution
to interactively visualize larger-than-memory 3D astronomical data cubes by
utilizing a heterogeneous cluster of CPUs and GPUs. The system partitions the
data volume into smaller sub-volumes that are distributed over the rendering
workstations. A GPU-based ray casting volume rendering is performed to generate
images for each sub-volume, which are composited to generate the whole volume
output, and returned to the user. Datasets including the HI Parkes All Sky
Survey (HIPASS - 12 GB) southern sky and the Galactic All Sky Survey (GASS - 26
GB) data cubes were used to demonstrate our framework's performance. The
framework can render the GASS data cube with a maximum render time < 0.3 second
with 1024 x 1024 pixels output resolution using 3 rendering workstations and 8
GPUs. Our framework will scale to visualize larger datasets, even of Terabyte
order, if proper hardware infrastructure is available.Comment: 15 pages, 12 figures, Accepted New Astronomy July 201
Novel high performance techniques for high definition computer aided tomography
Mención Internacional en el título de doctorMedical image processing is an interdisciplinary field in which multiple research areas are involved:
image acquisition, scanner design, image reconstruction algorithms, visualization, etc.
X-Ray Computed Tomography (CT) is a medical imaging modality based on the attenuation
suffered by the X-rays as they pass through the body. Intrinsic differences in attenuation properties
of bone, air, and soft tissue result in high-contrast images of anatomical structures. The
main objective of CT is to obtain tomographic images from radiographs acquired using X-Ray
scanners. The process of building a 3D image or volume from the 2D radiographs is known as
reconstruction. One of the latest trends in CT is the reduction of the radiation dose delivered
to patients through the decrease of the amount of acquired data. This reduction results in artefacts
in the final images if conventional reconstruction methods are used, making it advisable to
employ iterative reconstruction algorithms.
There are numerous reconstruction algorithms available, from which we can highlight two
specific types: traditional algorithms, which are fast but do not enable the obtaining of high
quality images in situations of limited data; and iterative algorithms, slower but more reliable
when traditional methods do not reach the quality standard requirements. One of the priorities
of reconstruction is the obtaining of the final images in near real time, in order to reduce the
time spent in diagnosis. To accomplish this objective, new high performance techniques and methods
for accelerating these types of algorithms are needed. This thesis addresses the challenges
of both traditional and iterative reconstruction algorithms, regarding acceleration and image
quality. One common approach for accelerating these algorithms is the usage of shared-memory
and heterogeneous architectures. In this thesis, we propose a novel simulation/reconstruction
framework, namely FUX-Sim. This framework follows the hypothesis that the development of
new flexible X-ray systems can benefit from computer simulations, which may also enable performance
to be checked before expensive real systems are implemented. Its modular design
abstracts the complexities of programming for accelerated devices to facilitate the development
and evaluation of the different configurations and geometries available. In order to obtain near
real execution times, low-level optimizations for the main components of the framework are
provided for Graphics Processing Unit (GPU) architectures.
Other alternative tackled in this thesis is the acceleration of iterative reconstruction algorithms
by using distributed memory architectures. We present a novel architecture that unifies
the two most important computing paradigms for scientific computing nowadays: High Performance
Computing (HPC). The proposed architecture combines Big Data frameworks with the
advantages of accelerated computing.
The proposed methods presented in this thesis provide more flexible scanner configurations
as they offer an accelerated solution. Regarding performance, our approach is as competitive as
the solutions found in the literature. Additionally, we demonstrate that our solution scales with
the size of the problem, enabling the reconstruction of high resolution images.El procesamiento de imágenes médicas es un campo interdisciplinario en el que participan múltiples
áreas de investigación como la adquisición de imágenes, diseño de escáneres, algoritmos de
reconstrucción de imágenes, visualización, etc. La tomografía computarizada (TC) de rayos X es
una modalidad de imágen médica basada en el cálculo de la atenuación sufrida por los rayos X a
medida que pasan por el cuerpo a escanear. Las diferencias intrínsecas en la atenuación de hueso,
aire y tejido blando dan como resultado imágenes de alto contraste de estas estructuras anatómicas.
El objetivo principal de la TC es obtener imágenes tomográficas a partir estas radiografías
obtenidas mediante escáneres de rayos X. El proceso de construir una imagen o volumen en 3D a
partir de las radiografías 2D se conoce como reconstrucción. Una de las últimas tendencias en la
tomografía computarizada es la reducción de la dosis de radiación administrada a los pacientes
a través de la reducción de la cantidad de datos adquiridos. Esta reducción da como resultado
artefactos en las imágenes finales si se utilizan métodos de reconstrucción convencionales, por
lo que es aconsejable emplear algoritmos de reconstrucción iterativos.
Existen numerosos algoritmos de reconstrucción disponibles a partir de los cuales podemos
destacar dos categorías: algoritmos tradicionales, rápidos pero no permiten obtener imágenes de
alta calidad en situaciones en las que los datos son limitados; y algoritmos iterativos, más lentos
pero más estables en situaciones donde los métodos tradicionales no alcanzan los requisitos en
cuanto a la calidad de la imagen. Una de las prioridades de la reconstrucción es la obtención
de las imágenes finales en tiempo casi real, con el fin de reducir el tiempo de diagnóstico. Para
lograr este objetivo, se necesitan nuevas técnicas y métodos de alto rendimiento para acelerar
estos algoritmos.
Esta tesis aborda los desafíos de los algoritmos de reconstrucción tradicionales e iterativos,
con respecto a la aceleración y la calidad de imagen. Un enfoque común para acelerar estos
algoritmos es el uso de arquitecturas de memoria compartida y heterogéneas. En esta tesis,
proponemos un nuevo sistema de simulación/reconstrucción, llamado FUX-Sim. Este sistema se
construye alrededor de la hipótesis de que el desarrollo de nuevos sistemas de rayos X flexibles
puede beneficiarse de las simulaciones por computador, en los que también se puede realizar
un control del rendimiento de los nuevos sistemas a desarrollar antes de su implementación
física. Su diseño modular abstrae las complejidades de la programación para aceleradores con el
objetivo de facilitar el desarrollo y la evaluación de las diferentes configuraciones y geometrías
disponibles. Para obtener ejecuciones en casi tiempo real, se proporcionan optimizaciones de
bajo nivel para los componentes principales del sistema en las arquitecturas GPU.
Otra alternativa abordada en esta tesis es la aceleración de los algoritmos de reconstrucción
iterativa mediante el uso de arquitecturas de memoria distribuidas. Presentamos una arquitectura
novedosa que unifica los dos paradigmas informáticos más importantes en la actualidad:
computación de alto rendimiento (HPC) y Big Data. La arquitectura propuesta combina sistemas
Big Data con las ventajas de los dispositivos aceleradores.
Los métodos propuestos presentados en esta tesis proporcionan configuraciones de escáner
más flexibles y ofrecen una solución acelerada. En cuanto al rendimiento, nuestro enfoque es tan
competitivo como las soluciones encontradas en la literatura. Además, demostramos que nuestra
solución escala con el tamaño del problema, lo que permite la reconstrucción de imágenes de
alta resolución.This work has been mainly funded thanks to a FPU fellowship (FPU14/03875) from the Spanish
Ministry of Education.
It has also been partially supported by other grants:
• DPI2016-79075-R. “Nuevos escenarios de tomografía por rayos X”, from the Spanish Ministry
of Economy and Competitiveness.
• TIN2016-79637-P Towards unification of HPC and Big Data Paradigms from the Spanish
Ministry of Economy and Competitiveness.
• Short-term scientific missions (STSM) grant from NESUS COST Action IC1305.
• TIN2013-41350-P, Scalable Data Management Techniques for High-End Computing Systems
from the Spanish Ministry of Economy and Competitiveness.
• RTC-2014-3028-1 NECRA Nuevos escenarios clinicos con radiología avanzada from the
Spanish Ministry of Economy and Competitiveness.Programa Oficial de Doctorado en Ciencia y Tecnología InformáticaPresidente: José Daniel García Sánchez.- Secretario: Katzlin Olcoz Herrero.- Vocal: Domenico Tali
Advanced photonic and electronic systems - WILGA 2017
WILGA annual symposium on advanced photonic and electronic systems has been organized by young scientist for young scientists since two decades. It traditionally gathers more than 350 young researchers and their tutors. Ph.D students and graduates present their recent achievements during well attended oral sessions. Wilga is a very good digest of Ph.D. works carried out at technical universities in electronics and photonics, as well as information sciences throughout Poland and some neighboring countries. Publishing patronage over Wilga keep Elektronika technical journal by SEP, IJET by PAN and Proceedings of SPIE. The latter world editorial series publishes annually more than 200 papers from Wilga. Wilga 2017 was the XL edition of this meeting. The following topical tracks were distinguished: photonics, electronics, information technologies and system research. The article is a digest of some chosen works presented during Wilga 2017 symposium. WILGA 2017 works were published in Proc. SPIE vol.10445
DEMON: a Proposal for a Satellite-Borne Experiment to study Dark Matter and Dark Energy
We outline a novel satellite mission concept, DEMON, aimed at advancing our
comprehension of both dark matter and dark energy, taking full advantage of two
complementary methods: weak lensing and the statistics of galaxy clusters. We
intend to carry out a 5000 sqdeg combined IR, optical and X-ray survey with
galaxies up to a redshift of z~2 in order to determine the shear correlation
function. We will also find ~100000 galaxy clusters, making it the largest
survey of this type to date. The DEMON spacecraft will comprise one IR/optical
and eight X-ray telescopes, coupled to multiple cameras operating at different
frequency bands. To a great extent, the technology employed has already been
partially tested on ongoing missions, therefore ensuring improved reliability.Comment: 12 pages, 3 figures, accepted for publication in the SPIE conference
proceeding
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