34,017 research outputs found
Semantic Component Composition
Building complex software systems necessitates the use of component-based
architectures. In theory, of the set of components needed for a design, only
some small portion of them are "custom"; the rest are reused or refactored
existing pieces of software. Unfortunately, this is an idealized situation.
Just because two components should work together does not mean that they will
work together.
The "glue" that holds components together is not just technology. The
contracts that bind complex systems together implicitly define more than their
explicit type. These "conceptual contracts" describe essential aspects of
extra-system semantics: e.g., object models, type systems, data representation,
interface action semantics, legal and contractual obligations, and more.
Designers and developers spend inordinate amounts of time technologically
duct-taping systems to fulfill these conceptual contracts because system-wide
semantics have not been rigorously characterized or codified. This paper
describes a formal characterization of the problem and discusses an initial
implementation of the resulting theoretical system.Comment: 9 pages, submitted to GCSE/SAIG '0
Performance Analysis and Enhancement of Multiband OFDM for UWB Communications
In this paper, we analyze the frequency-hopping orthogonal frequency-division
multiplexing (OFDM) system known as Multiband OFDM for high-rate wireless
personal area networks (WPANs) based on ultra-wideband (UWB) transmission.
Besides considering the standard, we also propose and study system performance
enhancements through the application of Turbo and Repeat-Accumulate (RA) codes,
as well as OFDM bit-loading. Our methodology consists of (a) a study of the
channel model developed under IEEE 802.15 for UWB from a frequency-domain
perspective suited for OFDM transmission, (b) development and quantification of
appropriate information-theoretic performance measures, (c) comparison of these
measures with simulation results for the Multiband OFDM standard proposal as
well as our proposed extensions, and (d) the consideration of the influence of
practical, imperfect channel estimation on the performance. We find that the
current Multiband OFDM standard sufficiently exploits the frequency selectivity
of the UWB channel, and that the system performs in the vicinity of the channel
cutoff rate. Turbo codes and a reduced-complexity clustered bit-loading
algorithm improve the system power efficiency by over 6 dB at a data rate of
480 Mbps.Comment: 32 pages, 10 figures, 1 table. Submitted to the IEEE Transactions on
Wireless Communications (Sep. 28, 2005). Minor revisions based on reviewers'
comments (June 23, 2006
Model-driven performance evaluation for service engineering
Service engineering and service-oriented architecture as an
integration and platform technology is a recent approach to software systems integration. Software quality aspects such as performance are of central importance for the integration of heterogeneous, distributed service-based systems. Empirical performance evaluation is a process of
measuring and calculating performance metrics of the implemented software. We present an approach for the empirical, model-based performance evaluation of services and service compositions in the context of model-driven service engineering. Temporal databases theory is utilised
for the empirical performance evaluation of model-driven developed service systems
PULP-HD: Accelerating Brain-Inspired High-Dimensional Computing on a Parallel Ultra-Low Power Platform
Computing with high-dimensional (HD) vectors, also referred to as
, is a brain-inspired alternative to computing with
scalars. Key properties of HD computing include a well-defined set of
arithmetic operations on hypervectors, generality, scalability, robustness,
fast learning, and ubiquitous parallel operations. HD computing is about
manipulating and comparing large patterns-binary hypervectors with 10,000
dimensions-making its efficient realization on minimalistic ultra-low-power
platforms challenging. This paper describes HD computing's acceleration and its
optimization of memory accesses and operations on a silicon prototype of the
PULPv3 4-core platform (1.5mm, 2mW), surpassing the state-of-the-art
classification accuracy (on average 92.4%) with simultaneous 3.7
end-to-end speed-up and 2 energy saving compared to its single-core
execution. We further explore the scalability of our accelerator by increasing
the number of inputs and classification window on a new generation of the PULP
architecture featuring bit-manipulation instruction extensions and larger
number of 8 cores. These together enable a near ideal speed-up of 18.4
compared to the single-core PULPv3
Forum Session at the First International Conference on Service Oriented Computing (ICSOC03)
The First International Conference on Service Oriented Computing (ICSOC) was held in Trento, December 15-18, 2003. The focus of the conference ---Service Oriented Computing (SOC)--- is the new emerging paradigm for distributed computing and e-business processing that has evolved from object-oriented and component computing to enable building agile networks of collaborating business applications distributed within and across organizational boundaries. Of the 181 papers submitted to the ICSOC conference, 10 were selected for the forum session which took place on December the 16th, 2003. The papers were chosen based on their technical quality, originality, relevance to SOC and for their nature of being best suited for a poster presentation or a demonstration. This technical report contains the 10 papers presented during the forum session at the ICSOC conference. In particular, the last two papers in the report ere submitted as industrial papers
Software-Defined Cloud Computing: Architectural Elements and Open Challenges
The variety of existing cloud services creates a challenge for service
providers to enforce reasonable Software Level Agreements (SLA) stating the
Quality of Service (QoS) and penalties in case QoS is not achieved. To avoid
such penalties at the same time that the infrastructure operates with minimum
energy and resource wastage, constant monitoring and adaptation of the
infrastructure is needed. We refer to Software-Defined Cloud Computing, or
simply Software-Defined Clouds (SDC), as an approach for automating the process
of optimal cloud configuration by extending virtualization concept to all
resources in a data center. An SDC enables easy reconfiguration and adaptation
of physical resources in a cloud infrastructure, to better accommodate the
demand on QoS through a software that can describe and manage various aspects
comprising the cloud environment. In this paper, we present an architecture for
SDCs on data centers with emphasis on mobile cloud applications. We present an
evaluation, showcasing the potential of SDC in two use cases-QoS-aware
bandwidth allocation and bandwidth-aware, energy-efficient VM placement-and
discuss the research challenges and opportunities in this emerging area.Comment: Keynote Paper, 3rd International Conference on Advances in Computing,
Communications and Informatics (ICACCI 2014), September 24-27, 2014, Delhi,
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