Supercapacitor assisted LDO (SCALDO) techniquean extra low frequency design approach to high efficiency DC-DC converters and how it compares with the classical switched capacitor converters

Supercapacitor assisted low dropout regulators (SCALDO) were proposed as an alternative design approach to DC-DC converters, where the supercapacitor circulation frequency (switching frequency) is in the order of few Hz to few 10s of Hz, with an output stage based on a low dropout regulator stage. For converters such as 12–5V, 5–3.3V and 5–1.5V, the technique provides efficiency improvement factors of 2, 1.33 and 3 respectively, in compared to linear converters with same input-output combinations. In a 5–1.5V SCALDO regulator, using thin profile supercapacitors in the range of fractional farads to few farads, this translates to an approximate end to end efficiency of near 90%. However, there were concerns that this patented technique is merely a variation of well-known switched capacitor (charge pump) converters. This paper is aimed at providing a broad overview of the capability of SCALDO technique with generalized theory, indicating its capabilities and limitations, and comparing the practical performance with a typical switched capacitor converter of similar current capability

A parallel Viterbi decoder for block cyclic and convolution codes

We present a parallel version of Viterbi's decoding procedure, for which we are able to demonstrate that the resultant task graph has restricted complexity in that the number of communications to or from any processor cannot exceed 4 for BCH codes. The resulting algorithm works in lock step making it suitable for implementation on a systolic processor array, which we have implemented on a field programmable gate array and demonstrate the perfect scaling of the algorithm for two exemplar BCH codes. The parallelisation strategy is applicable to all cyclic codes and convolution codes. We also present a novel method for generating the state transition diagrams for these codes

Dynamic integration of context model constraints in web service processes

Autonomic Web service composition has been a challenging topic for some years. The context in which composition takes places determines essential aspects. A context model can provide meaningful composition information for services process composition. An ontology-based approach for context information integration is the basis of a constraint approach to dynamically integrate context validation into service processes. The dynamic integration of context constraints into an orchestrated service process is a necessary direction to achieve autonomic service composition

Context constraint integration and validation in dynamic web service compositions

System architectures that cross organisational boundaries are usually implemented based on Web service technologies due to their inherent interoperability benets. With increasing exibility requirements, such as on-demand service provision, a dynamic approach to service architecture focussing on composition at runtime is needed. The possibility of technical faults, but also violations of functional and semantic constraints require a comprehensive notion of context that captures composition-relevant aspects. Context-aware techniques are consequently required to support constraint validation for dynamic service composition. We present techniques to respond to problems occurring during the execution of dynamically composed Web services implemented in WS-BPEL. A notion of context { covering physical and contractual faults and violations { is used to safeguard composed service executions dynamically. Our aim is to present an architectural framework from an application-oriented perspective, addressing practical considerations of a technical framework

Constraint integration and violation handling for BPEL processes

Autonomic, i.e. dynamic and fault-tolerant Web service composition is a requirement resulting from recent developments such as on-demand services. In the context of planning-based service composition, multi-agent planning and dynamic error handling are still unresolved problems. Recently, business rule and constraint management has been looked at for enterprise SOA to add business flexibility. This paper proposes a constraint integration and violation handling technique for dynamic service composition. Higher degrees of reliability and fault-tolerance, but also performance for autonomously composed WS-BPEL processes are the objectives

Context modeling and constraints binding in web service business processes

Context awareness is a principle used in pervasive services applications to enhance their exibility and adaptability to changing conditions and dynamic environments. Ontologies provide a suitable framework for context modeling and reasoning. We develop a context model for executable business processes { captured as an ontology for the web services domain. A web service description is attached to a service context profile, which is bound to the context ontology. Context instances can be generated dynamically at services runtime and are bound to context constraint services. Constraint services facilitate both setting up constraint properties and constraint checkers, which determine the dynamic validity of context instances. Data collectors focus on capturing context instances. Runtime integration of both constraint services and data collectors permit the business process to achieve dynamic business goals

Distributed aspect-oriented service composition for business compliance governance with public service processes

Service-Oriented Architecture (SOA) offers a technical foundation for Enterprise Application Integration and business collaboration through service-based business components. With increasing process outsourcing and cloud computing, enterprises need process-level integration and collaboration (process-oriented) to quickly launch new business processes for new customers and products. However, business processes that cross organisations’ compliance regulation boundaries are still unaddressed. We introduce a distributed aspect-oriented service composition approach, which enables multiple process clients hot-plugging their business compliance models (business rules, fault handling policy, and execution monitor) to BPEL business processes

Ontology-based composition and matching for dynamic cloud service coordination

Recent cross-organisational software service offerings, such as cloud computing, create higher integration needs. In particular, services are combined through brokers and mediators, solutions to allow individual services to collaborate and their interaction to be coordinated are required. The need to address dynamic management - caused by cloud and on-demand environments - can be addressed through service coordination based on ontology-based composition and matching techniques. Our solution to composition and matching utilises a service coordination space that acts as a passive infrastructure for collaboration where users submit requests that are then selected and taken on by providers. We discuss the information models and the coordination principles of such a collaboration environment in terms of an ontology and its underlying description logics. We provide ontology-based solutions for structural composition of descriptions and matching between requested and provided services