12 research outputs found
A Multi-objective Perspective for Operator Scheduling using Fine-grained DVS Architecture
The stringent power budget of fine grained power managed digital integrated
circuits have driven chip designers to optimize power at the cost of area and
delay, which were the traditional cost criteria for circuit optimization. The
emerging scenario motivates us to revisit the classical operator scheduling
problem under the availability of DVFS enabled functional units that can
trade-off cycles with power. We study the design space defined due to this
trade-off and present a branch-and-bound(B/B) algorithm to explore this state
space and report the pareto-optimal front with respect to area and power. The
scheduling also aims at maximum resource sharing and is able to attain
sufficient area and power gains for complex benchmarks when timing constraints
are relaxed by sufficient amount. Experimental results show that the algorithm
that operates without any user constraint(area/power) is able to solve the
problem for most available benchmarks, and the use of power budget or area
budget constraints leads to significant performance gain.Comment: 18 pages, 6 figures, International journal of VLSI design &
Communication Systems (VLSICS
Network-on-Chip
Addresses the Challenges Associated with System-on-Chip Integration Network-on-Chip: The Next Generation of System-on-Chip Integration examines the current issues restricting chip-on-chip communication efficiency, and explores Network-on-chip (NoC), a promising alternative that equips designers with the capability to produce a scalable, reusable, and high-performance communication backbone by allowing for the integration of a large number of cores on a single system-on-chip (SoC). This book provides a basic overview of topics associated with NoC-based design: communication infrastructure design, communication methodology, evaluation framework, and mapping of applications onto NoC. It details the design and evaluation of different proposed NoC structures, low-power techniques, signal integrity and reliability issues, application mapping, testing, and future trends. Utilizing examples of chips that have been implemented in industry and academia, this text presents the full architectural design of components verified through implementation in industrial CAD tools. It describes NoC research and developments, incorporates theoretical proofs strengthening the analysis procedures, and includes algorithms used in NoC design and synthesis. In addition, it considers other upcoming NoC issues, such as low-power NoC design, signal integrity issues, NoC testing, reconfiguration, synthesis, and 3-D NoC design. This text comprises 12 chapters and covers: The evolution of NoC from SoC—its research and developmental challenges NoC protocols, elaborating flow control, available network topologies, routing mechanisms, fault tolerance, quality-of-service support, and the design of network interfaces The router design strategies followed in NoCs The evaluation mechanism of NoC architectures The application mapping strategies followed in NoCs Low-power design techniques specifically followed in NoCs The signal integrity and reliability issues of NoC The details of NoC testing strategies reported so far The problem of synthesizing application-specific NoCs Reconfigurable NoC design issues Direction of future research and development in the field of NoC Network-on-Chip: The Next Generation of System-on-Chip Integration covers the basic topics, technology, and future trends relevant to NoC-based design, and can be used by engineers, students, and researchers and other industry professionals interested in computer architecture, embedded systems, and parallel/distributed systems
Application of novel technologies for the development of next generation MR compatible PET inserts
Multimodal imaging integrating Positron Emission Tomography and Magnetic
Resonance Imaging (PET/MRI) has professed advantages as compared to other available
combinations, allowing both functional and structural information to be acquired with
very high precision and repeatability. However, it has yet to be adopted as the standard
for experimental and clinical applications, due to a variety of reasons mainly related to
system cost and flexibility. A hopeful existing approach of silicon photodetector-based MR
compatible PET inserts comprised by very thin PET devices that can be inserted in the
MRI bore, has been pioneered, without disrupting the market as expected. Technological
solutions that exist and can make this type of inserts lighter, cost-effective and more
adaptable to the application need to be researched further.
In this context, we expand the study of sub-surface laser engraving (SSLE) for
scintillators used for PET. Through acquiring, measuring and calibrating the use of a SSLE
setting we study the effect of different engraving configurations on detection
characteristics of the scintillation light by the photosensors. We demonstrate that apart
from cost-effectiveness and ease of application, SSLE treated scintillators have similar
spatial resolution and superior sensitivity and packing fraction as compared to standard
pixelated arrays, allowing for shorter crystals to be used. Flexibility of design is
benchmarked and adoption of honeycomb architecture due to geometrical advantages is
proposed. Furthermore, a variety of depth-of-interaction (DoI) designs are engraved and
studied, greatly enhancing applicability in small field-of-view tomographs, such as the
intended inserts. To adapt to this need, a novel approach for multi-layer DoI
characterization has been developed and is demonstrated.
Apart from crystal treatment, considerations on signal transmission and processing are
addressed. A double time-over-threshold (ToT) method is proposed, using the statistics of
noise in order to enhance precision. This method is tested and linearity results
demonstrate applicability for multiplexed readout designs. A study on analog optical
wireless communication (aOWC) techniques is also performed and proof of concept
results presented. Finally, a ToT readout firmware architecture, intended for low-cost
FPGAs, has been developed and is described.
By addressing the potential development, applicability and merits of a range of
transdisciplinary solutions, we demonstrate that with these techniques it is possible to
construct lighter, smaller, lower consumption, cost-effective MRI compatible PET inserts.
Those designs can make PET/MRI multimodality the dominant clinical and experimental
imaging approach, enhancing researcher and physician insight to the mysteries of life.La combinación multimodal de TomografÃa por Emisión de Positrones con la Imagen de
Resonancia Magnética (PET/MRI, de sus siglas en inglés) tiene clara ventajas en
comparación con otras técnicas multimodales actualmente disponibles, dada su capacidad
para registrar información funcional e información estructural con mucha precisión y
repetibilidad. Sin embargo, esta técnica no acaba de penetrar en la práctica clÃnica debido
en gran parte a alto coste. Las investigaciones que persiguen mejorar el desarrollo de
insertos de PET basados en fotodetectores de silicio y compatibles con MRI, aunque han
sido intensas y han generado soluciones ingeniosas, todavÃa no han conseguido encontrar
las soluciones que necesita la industria. Sin embargo, existen opciones todavÃa sin explorar
que podrÃan ayudar a evolucionar este tipo de insertos consiguiendo dispositivos más
ligeros, baratos y con mejores prestaciones.
Esta tesis profundiza en el estudio de grabación sub-superficie con láser (SSLE) para el
diseño de los cristales centelladores usados en los sistemas PET. Para ello hemos
caracterizado, medido y calibrado un procedimiento SSLE, y a continuación hemos
estudiado el efecto que tienen sobre las especificaciones del detector las diferentes
configuraciones del grabado. Demostramos que además de la rentabilidad y facilidad de
uso de esta técnica, los centelladores SSLE tienen resolución espacial equivalente y
sensibilidad y fracción de empaquetamiento superiores a las matrices de centelleo
convencionales, lo que posibilita utilizar cristales más cortos para conseguir la misma
sensibilidad. Estos diseños también permiten medir la profundidad de la interacción (DoI),
lo que facilita el uso de estos diseños en tomógrafos de radio pequeño, como pueden ser
los sistemas preclÃnicos, los dedicados (cabeza o mama) o los insertos para MRI.
Además de trabajar en el tratamiento de cristal de centelleo, hemos considerado nuevas
aproximaciones al procesamiento y transmisión de la señal. Proponemos un método
innovador de doble medida de tiempo sobre el umbral (ToT) que integra una evaluación
de la estadÃstica del ruido con el propósito de mejorar la precisión. El método se ha
validado y los resultados demuestran su viabilidad de uso incluso en conjuntos de señales
multiplexadas. Un estudio de las técnicas de comunicación óptica analógica e inalámbrica
(aOWC) ha permitido el desarrollo de una nueva propuesta para comunicar las señales del
detector PET insertado en el gantry a un el procesador de señal externo, técnica que se ha
validado en un demostrador. Finalmente, se ha propuesto y demostrado una nueva
arquitectura de análisis de señal ToT implementada en firmware en FPGAs de bajo coste.
La concepción y desarrollo de estas ideas, asà como la evaluación de los méritos de las
diferentes soluciones propuestas, demuestran que con estas técnicas es posible construir
insertos de PET compatibles con sistemas MRI, que serán más ligeros y compactos, con un
reducido consumo y menor coste. De esta forma se contribuye a que la técnica multimodal
PET/MRI pueda penetrar en la clÃnica, mejorando la comprensión que médicos e
investigadores puedan alcanzar en su estudio de los misterios de la vida.Programa Oficial de Doctorado en IngenierÃa Eléctrica, Electrónica y AutomáticaPresidente: Andrés Santos Lleó.- Secretario: Luis Hernández Corporales.- Vocal: Giancarlo Sportell
High-level synthesis of dataflow programs for heterogeneous platforms:design flow tools and design space exploration
The growing complexity of digital signal processing applications implemented in programmable logic and embedded processors make a compelling case the use of high-level methodologies for their design and implementation. Past research has shown that for complex systems, raising the level of abstraction does not necessarily come at a cost in terms of performance or resource requirements. As a matter of fact, high-level synthesis tools supporting such a high abstraction often rival and on occasion improve low-level design. In spite of these successes, high-level synthesis still relies on programs being written with the target and often the synthesis process, in mind. In other words, imperative languages such as C or C++, most used languages for high-level synthesis, are either modified or a constrained subset is used to make parallelism explicit. In addition, a proper behavioral description that permits the unification for hardware and software design is still an elusive goal for heterogeneous platforms. A promising behavioral description capable of expressing both sequential and parallel application is RVC-CAL. RVC-CAL is a dataflow programming language that permits design abstraction, modularity, and portability. The objective of this thesis is to provide a high-level synthesis solution for RVC-CAL dataflow programs and provide an RVC-CAL design flow for heterogeneous platforms. The main contributions of this thesis are: a high-level synthesis infrastructure that supports the full specification of RVC-CAL, an action selection strategy for supporting parallel read and writes of list of tokens in hardware synthesis, a dynamic fine-grain profiling for synthesized dataflow programs, an iterative design space exploration framework that permits the performance estimation, analysis, and optimization of heterogeneous platforms, and finally a clock gating strategy that reduces the dynamic power consumption. Experimental results on all stages of the provided design flow, demonstrate the capabilities of the tools for high-level synthesis, software hardware Co-Design, design space exploration, and power optimization for reconfigurable hardware. Consequently, this work proves the viability of complex systems design and implementation using dataflow programming, not only for system-level simulation but real heterogeneous implementations
Investigation into yield and reliability enhancement of TSV-based three-dimensional integration circuits
Three dimensional integrated circuits (3D ICs) have been acknowledged as a promising technology to overcome the interconnect delay bottleneck brought by continuous CMOS scaling. Recent research shows that through-silicon-vias (TSVs), which act as vertical links between layers, pose yield and reliability challenges for 3D design. This thesis presents three original contributions.The first contribution presents a grouping-based technique to improve the yield of 3D ICs under manufacturing TSV defects, where regular and redundant TSVs are partitioned into groups. In each group, signals can select good TSVs using rerouting multiplexers avoiding defective TSVs. Grouping ratio (regular to redundant TSVs in one group) has an impact on yield and hardware overhead. Mathematical probabilistic models are presented for yield analysis under the influence of independent and clustering defect distributions. Simulation results using MATLAB show that for a given number of TSVs and TSV failure rate, careful selection of grouping ratio results in achieving 100% yield at minimal hardware cost (number of multiplexers and redundant TSVs) in comparison to a design that does not exploit TSV grouping ratios. The second contribution presents an efficient online fault tolerance technique based on redundant TSVs, to detect TSV manufacturing defects and address thermal-induced reliability issue. The proposed technique accounts for both fault detection and recovery in the presence of three TSV defects: voids, delamination between TSV and landing pad, and TSV short-to-substrate. Simulations using HSPICE and ModelSim are carried out to validate fault detection and recovery. Results show that regular and redundant TSVs can be divided into groups to minimise area overhead without affecting the fault tolerance capability of the technique. Synthesis results using 130-nm design library show that 100% repair capability can be achieved with low area overhead (4% for the best case). The last contribution proposes a technique with joint consideration of temperature mitigation and fault tolerance without introducing additional redundant TSVs. This is achieved by reusing spare TSVs that are frequently deployed for improving yield and reliability in 3D ICs. The proposed technique consists of two steps: TSV determination step, which is for achieving optimal partition between regular and spare TSVs into groups; The second step is TSV placement, where temperature mitigation is targeted while optimizing total wirelength and routing difference. Simulation results show that using the proposed technique, 100% repair capability is achieved across all (five) benchmarks with an average temperature reduction of 75.2? (34.1%) (best case is 99.8? (58.5%)), while increasing wirelength by a small amount
Aeronautical engineering: A continuing bibliography with indexes (supplement 202)
This bibliography lists 447 reports, articles and other documents introduced into the NASA scientific and technical information system in June 1986
Workshop on Microwave Power Transmission and Reception. Workshop Paper Summaries
Microwave systems performance and phase control are discussed. Component design and reliability are highlighted. The power amplifiers, radiating elements, rectennas, and solid state configurations are described. The proper sizing of microwave transmission systems is also discussed
Aeronautical Engineering: A cumulative index to the 1984 issues of the continuing bibliography
This bibliography is a cumulative index to the abstracts contained in NASA SP-7037(171) through NASA SP-7037(182) of Aeronautical Engineering: A Continuing Bibliography. NASA SP-7037 and its supplements have been compiled through the cooperative efforts of the American Institute of Aeronautics and Astronautics (AIAA) and the National Aeronautics and Space Administration (NASA). This cumulative index includes subject, personal author, corporate source, foreign technology, contract, report number, and accession number indexes
Bibliography of Lewis Research Center technical publications announced in 1988
This bibliography contains abstracts of the technical reports that resulted from the scientific and engineering work performed and managed by the Lewis Research Center in 1988. Subject, author, and corporate source indexes are also included. All the publications were announced in the 1988 issues of STAR (Scientific and Technical Aerospace Reports) and/or IAA (International Aerospace Abstracts). Included are research reports, journal articles, conference presentations, patents and patent applications, and theses
Proceedings of the 10th international conference on energy efficiency in motor driven systems (EEMODS' 2017)
The 10th International Conference on Energy Efficiency in Motor Driven Systems (EEMODS'17) was be held in Rome (Italy) on 6-8 September, 2017. The EEMODS conferences have been very successful in attracting distinguished and international presenters and attendees. The wide variety of stakeholders has included professionals involved in manufacturing, marketing, and promotion of energy efficient motors and motor driven systems and representatives from research labs, academia, and public policy.
EEMODS’15 provided a forum to discuss and debate the latest developments in the impacts of electrical motor systems (advanced motors and drives, compressors, pumps, and fans) on energy and the environment, the policies and programmes adopted and planned, and the technical and commercial advances made in the dissemination and penetration of energy-efficient motor systems. In addition EEMODS covered also energy management in organizations, international harmonization of test method and financing of energy efficiency in motor systems. The Book of Proceedings contains the peer reviewed paper that have been presented at the conference.JRC.C.2-Energy Efficiency and Renewable