Architecture, design, and modeling of the OPSnet asynchronous optical packet switching node

An all-optical packet-switched network supporting multiple services represents a long-term goal for network operators and service providers alike. The EPSRC-funded OPSnet project partnership addresses this issue from device through to network architecture perspectives with the key objective of the design, development, and demonstration of a fully operational asynchronous optical packet switch (OPS) suitable for 100 Gb/s dense-wavelength-division multiplexing (DWDM) operation. The OPS is built around a novel buffer and control architecture that has been shown to be highly flexible and to offer the promise of fair and consistent packet delivery at high load conditions with full support for quality of service (QoS) based on differentiated services over generalized multiprotocol label switching

A Study of Medium Access Control Protocols for Wireless Body Area Networks

The seamless integration of low-power, miniaturised, invasive/non-invasive lightweight sensor nodes have contributed to the development of a proactive and unobtrusive Wireless Body Area Network (WBAN). A WBAN provides long-term health monitoring of a patient without any constraint on his/her normal dailylife activities. This monitoring requires low-power operation of invasive/non-invasive sensor nodes. In other words, a power-efficient Medium Access Control (MAC) protocol is required to satisfy the stringent WBAN requirements including low-power consumption. In this paper, we first outline the WBAN requirements that are important for the design of a low-power MAC protocol. Then we study low-power MAC protocols proposed/investigated for WBAN with emphasis on their strengths and weaknesses. We also review different power-efficient mechanisms for WBAN. In addition, useful suggestions are given to help the MAC designers to develop a low-power MAC protocol that will satisfy the stringent WBAN requirements.Comment: 13 pages, 8 figures, 7 table

The Grace Programming Language Draft Specification Version 0.3.1261

This is a specification of the Grace Programming Language. This specification is notably incomplete, and everything is subject to change

Quasi Two-Level PWM Operation of an MMC Phase Leg with Reduced Module Capacitance

The modular multilevel converter offers benefits for medium and high voltage power conversion due to indirect series connection of devices. The drawback is a large amount of capacitance that has to be installed in each module, often prohibiting its use in cost sensitive applications. This letter proposes a new operation mode of modular multilevel topologies that allows reducing the capacitance by at least an order of magnitude. To achieve this, the multilevel operation is sacrificed, but many advantages of indirect series connection, such as proper voltage sharing, small voltage steps, limited voltage slopes, modularity, and scalability remain

Managing change in persistent object systems

Persistent object systems are highly-valued technology because they o er an e ec- tive foundation for building very long-lived persistent application systems (PAS). The technology becomes more e ective as it o ers a more consistently integrated computational context. For it to be feasible to design and construct a PAS it must be possible to in- crementally add program and data to the existing collection. For a PAS to endure it must o er exibility: a capacity to evolve and change. This paper examines the capacity of persistent object systems to accommodate incremental construction and change. Established store based technologies can support incremental construction but methodologies are needed to deploy them e ectively. Evolving data description is one motivation for inheritance but inheritance alone is not enough to support change management. The case for supporting incremental change is very persuasive. The challenge is to provide technologies that will facilitate it and methodologies that will organise it. This paper identi es change absorbers as a means of describing how changes should propagate. It is argued that if we systematically develop an adequate reper- toire of change absorbers then they will facilitate much better quality change man- agement

Generic Distribution Support for Programming Systems

This dissertation provides constructive proof, through the implementation of a middleware, that distribution transparency is practical, generic, and extensible. Fault tolerant distributed services can be developed by using the failure detection abilities of the middleware. By generic we mean that the middleware can be used for many different programming languages and paradigms. Distribution for each kind of language entity is done in terms of consistency protocols, which guarantee that the semantics of the entities are preserved in a distributed setting. The middleware allows new consistency protocols to be added easily. The efficiency of the middleware and the ease of integration are shown by coupling the middleware to a programming system, which encompasses the object oriented, the functional, and the concurrent-declarative programming paradigms. Our measurements show that the distribution middleware is competitive with the most popular distributed programming systems (JavaRMI, .NET, IBM CORBA)

Implementation of a Modelica library for simulation of electromechanical actuators for aircraft and helicopters

The goal of the A2015 library presented in this paper is to develop a Modelica based, tool-independent standard for electromechanical actuators (EMA). This will contribute to the establishment of a “common language” throughout the development of EMAs for aircraft and helicopters and through the supply chain. All stages of the design and validation process (conceptual design, specification, development and validation) are covered. The modeling approach addresses specific aspects of the EMA design process not covered by existing tools. The library scope, engineering need and implementation are described. Modeling of selected EMA components is discussed in more detail. An application example of the library is given (linear actuator, A320 aileron