Design of a remote controlled hovercraft

Este informe trata el dise��o, desarrollo y construcci��n de un aerodeslizador de peque��o tama��o, equipado con control remoto que permite al usuario actuar sobre la velocidad y direcci��n del mismo. Este proyecto podr�� ser utilizado en un futuro como base para el desarrollo de aplicaciones m��s complejas. Un aerodeslizador es un medio de transporte cuyo chasis se eleva sobre el suelo por medio de un motor impulsor que hincha una falda colocada en la parte inferior del mismo. Adem��s, uno o m��s motores se colocan en la parte trasera del veh��culo para propulsarlo. El hecho de que el aerodeslizador no este en contacto directo con la tierra, hace que pueda moverse tanto por tierra como sobre el agua o hielo y que sea capaz de superar peque��os obst��culos. Por otra parte, este hecho se convierte a su vez en un problema debido a que su fuerza de rozamiento al desplazarse es muy peque��a, lo que provoca que sea muy dif��cil de frenar, y tienda a girar por s�� mismo debido a la inercia del movimiento y a las fuerzas provocadas por las corrientes de aire debajo del chasis. Sin embargo, para este proyecto no se ha colocado una falda debajo del mismo, debido a que su dise��o es bastante complicado, por lo tanto la fricci��n con el suelo es menor, aumentando los problemas detallados con anterioridad. El proyecto consta de dos partes, mando a distancia y aerodeslizador, que se conectan a trav��s de antenas de radiofrecuencia (RF). El dise��o y desarrollo de cada una ha sido realizado de manera separada exceptuando la parte de las comunicaciones entre ambas. El mando a distancia se divide en tres partes. La primera est�� compuesta por la interfaz de usuario y el circuito que genera las se��ales anal��gicas correspondientes a sus indicaciones. La interfaz de usuario la conforman tres potenci��metros: uno rotatorio y dos deslizantes. El rotatorio se utiliza para controlar la direcci��n de giro del aerodeslizador, mientras que cada uno de los deslizantes se emplea para controlar la fuerza del motor impulsor y del propulsor respectivamente. En los tres casos los potenci��metros se colocan en el circuito de manera que act��an como divisores de tensi��n controlables. La segunda parte se compone de un microcontrolador de la familia PSoC. Esta familia de microcontroladores se caracteriza por tener una gran adaptabilidad a la aplicaci��n en la que se quieran utilizar debido a la posibilidad de elecci��n de los perif��ricos, tanto anal��gicos como digitales, que forman parte del microcontrolador. Para el mando a distancia se configura con tres conversores A/D que se encargan de transformar las se��ales procedentes de los potenci��metros, tres amplificadores programables para trabajar con toda la escala de los conversores, un LCD que se utiliza para depurar el c��digo en C con el que se programa y un m��dulo SPI que es la interfaz que conecta el microcontrolador con la antena. Adem��s, se utilizan cuatro pines externos para elegir el canal de transmisi��n de la antena. La tercera parte es el m��dulo transceptor de radio frecuencia (RF) QFM-TRX1-24G, que en el mando a distancia funciona como transmisor. ��ste utiliza codificaci��n Manchester para asegurar bajas tasas de error. Como alimentaci��n para los circuitos del mando a distancia se utilizan cuatro pilas AA de 1,5 voltios en serie. En el aerodeslizador se pueden distinguir cinco partes. La primera es el m��dulo de comunicaciones, que utiliza el mismo transceptor que en el mando a distancia, pero esta vez funciona como receptor y por lo tanto servir�� como entrada de datos al sistema haciendo llegar las instrucciones del usuario. Este m��dulo se comunica con el siguiente, un microcontrolador de la familia PSoC, a trav��s de una interfaz SPI. En este caso el microcontrolador se configura con: un modulo SPI, un LCD utilizado para depurar el c��digo y tres m��dulos PWM (2 de 8 bits y uno de 16 bits) para controlar los motores y el servo del aerodeslizador. Adem��s, se utilizan cuatro pines externos para seleccionar el canal de recepci��n de datos. La tercera y cuarta parte se pueden considerar conjuntamente. Ambas est��n compuestas por el mismo circuito electr��nico basado en transistores MOSFET. A la puerta de cada uno de los transistores llega una se��al PWM de 100 kilohercios que proviene del microcontrolador, que se encarga de controlar el modo de funcionamiento de los transistores, que llevan acoplado un disipador de calor para evitar que se quemen. A su vez, los transistores hacen funcionar al dos ventiladores, que act��an como motores, el impulsor y el propulsor del aerodeslizador. La quinta y ��ltima parte es un servo est��ndar para modelismo. El servo est�� controlado por una se��al PWM, en la que la longitud del pulso positivo establece la posici��n de la cabeza del servo, girando en uno u otra direcci��n seg��n las instrucciones enviadas desde el mando a distancia por el usuario. Para el aerodeslizador se han utilizado dos fuentes de alimentaci��n diferentes: una compuesta por 4 pilas AA de 1,5 voltios en serie que alimentar��n al microcontrolador y al servo, y 4 bater��as de litio recargables de 3,2 voltios en serie que alimentan el circuito de los motores. La ��ltima parte del proyecto es el montaje y ensamblaje final de los dispositivos. Para el chasis del aerodeslizador se ha utilizado una cubierta rectangular de poli-estireno expandido, habitualmente encontrado en el embalaje de productos fr��giles. Este material es bastante ligero y con una alta resistencia a los golpes, por lo que es ideal para el prop��sito del proyecto. En el chasis se han realizado dos agujeros: uno circular situado en el centro del mismo en el se introduce y se ajusta con pegamento el motor impulsor, y un agujero con la forma del servo, situado en uno del los laterales estrechos del rect��ngulo, en el que se acopla el mismo. El motor propulsor est�� adherido al cabezal giratorio del servo de manera que rota a la vez que ��l, haciendo girar al aerodeslizador. El resto de circuitos electr��nicos y las bater��as se fijan al chasis mediante cinta adhesiva y pegamento procurando en todo momento repartir el peso de manera homog��nea por todo el chasis para aumentar la estabilidad del aerodeslizador. SUMMARY: In this final year project a remote controlled hovercraft was designed using mainly technology that is well known by students in the embedded systems programme. This platform could be used to develop further and more complex projects. The system was developed dividing the work into two parts: remote control and hovercraft. The hardware was of the hovercraft and the remote control was designed separately; however, the software was designed at the same time since it was needed to develop the communication system. The result of the project was a remote control hovercraft which has a user friendly interface. The system was designed based on microprocessor technologies and uses common remote control technologies. The system has been designed with technology commonly used by the students in Metropolia University so that it can be readily understood in order to develop other projects based on this platform.

Proposal for the Conceptual Design of Aeronautical Final Assembly Lines Based on the Industrial Digital Mock-Up Concept

The design of a Final Assembly Line (FAL) is carry out in the product industrialization activity. The phase dealing with the definition of conceptual solutions is characterized by depending heavily on the personnel experience and being time-consuming. To enhance such process, it is proposed a development of a knowledge based software application to assist designers in the definition of scenarios and to generate conceptual FAL alternatives. Both the scenario and the generated FAL solution are part of the industrialization digital mock-up (IDMU). A commercial software application used in the aircraft programmes and supporting the IDMU concepts of: Product, Process and Resource; was selected to implement a software prototype. This communication presents the adopted methodological approach and the architecture of the developed application.

Analysis and design of reconfigurable multimode multiport microstrip antennas for mimo systems and diversity schemes

Las comunicaciones inal��mbricas han transformado profundamente la forma en la que la gente se comunica en el d��a a d��a y es, sin lugar a dudas, una de las tecnolog��as de nuestro tiempo que m��s r��pidamente evoluciona. Este r��pido crecimiento implica retos enormes en la tecnolog��a subyacente, debido y entre otros motivos, a la gran demanda de capacidad de los nuevos servicios inal��mbricos. Los sistemas Multiple Input Multiple Output (MIMO) han despertado mucho inter��s como medio de mejorar el rendimiento global del sistema, satisfaciendo de este modo y en cierta medida los nuevo requisitos exigidos. De hecho, el papel relevante de esta tecnolog��a en los actuales esfuerzos de estandarizaci��n internacionales pone de manifiesto esta utilidad. Los sistemas MIMO sacan provecho de los grados de libertad espaciales, disponibles a trav��s del entorno multitrayecto, para mejorar el rendimiento de la comunicaci��n con una destacable eficiencia espectral. Con el fin de alcanzar esta mejora en el rendimiento, la diversidad espacial y por diagrama han sido empleadas tradicionalmente para reducir la correlaci��n entre los elementos radiantes, ya que una correlaci��n baja es condici��n necesaria, si bien no suficiente, para dicha mejora. Tomando como referencia, o punto de partida, las t��cnicas empleadas para obtener diversidad por diagrama, esta tesis doctoral surge de la b��squeda de la obtenci��n de diversidad por diagrama y/o multiplexaci��n espacial a trav��s del comportamiento multimodal de la antena microstrip, proponiendo para ello un modelo cuasi anal��tico original para el an��lisis y dise��o de antenas microstrip multipuerto, multimodo y reconfigurables. Este novedoso enfoque en este campo, en vez de recurrir a simulaciones de onda completa por medio de herramientas comerciales tal y como se emplea en las publicaciones existentes, reduce significativamente el esfuerzo global de an��lisis y dise��o, en este ��ltimo caso por medio de gu��as de dise��o generales. Con el fin de lograr el objetivo planteado y despu��s de una revisi��n de los principales conceptos de los sistemas MIMO que se emplear��n m��s adelante, se fija la atenci��n en encontrar, implementar y verificar la correcci��n y exactitud de un modelo anal��tico que sirva de base sobre la cual a��adir las mejoras necesarias para obtener las caracter��sticas buscadas del modelo cuasi anal��tico propuesto. Posteriormente y partiendo del modelo anal��tico base seleccionado, se exploran en profundidad y en diferentes entornos multitrayecto, las posibilidades en cuanto a rendimiento se refiere de diversidad por diagrama y multiplexaci��n espacial, proporcionadas por el comportamiento multimodal de las antenas parche microstrip sin cargar. Puesto que cada modo de la cavidad tiene su propia frecuencia de resonancia, es necesario encontrar formas de desplazar la frecuencia de resonancia de cada modo empleado para ubicarlas en la misma banda de frecuencia, manteniendo cada modo al mismo tiempo tan independiente como sea posible. Este objetivo puede lograrse cargando adecuadamente la cavidad con cargas reactivas, o alterando la geometr��a del parche radiante. Por consiguiente, la atenci��n en este punto se fija en el dise��o, implementaci��n y verificaci��n de un modelo cuasi anal��tico para el an��lisis de antenas parche microstrip multipuerto, multimodo y cargadas que permita llevar a cabo la tarea indicada, el cu��l es una de las contribuciones principales de esta tesis doctoral. Finalmente y bas��ndose en el conocimiento adquirido a trav��s del modelo cuasi anal��tico, se proporcionan y aplican gu��as generales para el dise��o de antenas microstrip multipuerto, multimodo y reconfigurables para sistemas MIMO, con el fin de mejorar su diversidad por diagrama y/o su capacidad por medio del comportamiento multimodal de las antenas parche microstrip. Se debe destacar que el trabajo presentado en esta tesis doctoral ha dado lugar a una publicaci��n en una revista t��cnica internacional de un alto factor de impacto. De igual manera, el trabajo tambi��n ha sido presentado en algunas de las m��s importantes conferencias internacionales en el ��mbito de las antenas ABSTRACT Wireless communications have deeply transformed the way people communicate on daily basis and it is undoubtedly one of the most rapidly evolving technologies of our time. This fast growing behaviour involves huge challenges on the bearing technology, due to and among others reasons, the high demanding capacity of new wireless services. MIMO systems have given rise to considerable interest as a means to enhance the overall system performance, thus satisfying somehow the new demanding requirements. Indeed, the significant role of this technology on current international standardization efforts, highlights this usefulness. MIMO systems make profit from the spatial degrees of freedom available through the multipath scenario to improve the communication performance with a remarkable spectral efficiency. In order to achieve this performance improvement, spatial and pattern diversity have been traditionally used to decrease the correlation between antenna elements, as low correlation is a necessary but not sufficient condition. Taking as a reference, or starting point, the techniques used to achieve pattern diversity, this Philosophiae Doctor (Ph.D.) arises from the pursuit of obtaining pattern diversity and/or spatial multiplexing capabilities through the multimode microstrip behaviour, thus proposing a novel quasi analytical model for the analysis and design of reconfigurable multimode multiport microstrip antennas. This innovative approach on this field, instead of resorting to full-wave simulations through commercial tools as done in the available publications, significantly reduces the overall analysis and design effort, in this last case through comprehensive design guidelines. In order to achieve this goal and after a review of the main concepts of MIMO systems which will be followed used, the spotlight is fixed on finding, implementing and verifying the correctness and accuracy of a base quasi analytical model over which add the necessary enhancements to obtain the sought features of the quasi analytical model proposed. Afterwards and starting from the base quasi analytical model selected, the pattern diversity and spatial multiplexing performance capabilities provided by the multimode behaviour of unloaded microstrip patch antennas under different multipath environments are fully explored. As each cavity mode has its own resonant frequency, it is required to find ways to displace the resonant frequency of each used mode to place them at the same frequency band while keeping each mode as independent as possible. This objective can be accomplished with an appropriate loading of the cavity with reactive loads, or through the alteration of the geometry of the radiation patch. Thus, the focus is set at this point on the design, implementation and verification of a quasi analytical model for the analysis of loaded multimode multiport microstrip patch antennas to carry out the aforementioned task, which is one of the main contributions of this Ph.D. Finally and based on the knowledge acquired through the quasi analytical model, comprehensive guidelines to design reconfigurable multimode MIMO microstrip antennas to improve the spatial multiplexing and/or diversity system performance by means of the multimode microstrip patch antenna behaviour are given and applied. It shall be highlighted that the work presented in this Ph.D. has given rise to a publication in an international technical journal of high impact factor. Moreover, the work has also been presented at some of the most important international conferences in antenna area.

Gesti��n intelectual de las pr��cticas comunicativas en arquitectura : S, M, L, XL, el gran evento = The intellectual management of communication practices in architecture : S, M, L, XL, the big event

La tesis doctoral se centra en la posibilidad de entender que la pr��ctica de arquitectura puede encontrar en las pr��cticas comunicativas un apoyo instrumental, que sobrepasa cualquier simplificaci��n cl��sica del uso de los medios como una mera aplicaci��n superficial, post-producida o sencillamente promocional. A partir de esta premisa se exponen casos del ��ltimo cuarto del siglo XX y se detecta que amenazas como el riesgo de la banalizaci��n, la posible saturaci��n de la imagen p��blica o la previsible asociaci��n incorrecta con otros individuos en presentaciones grupales o por tem��ticas, han podido influir en un crecimiento notable de la adquisici��n de control, por parte de los arquitectos, en sus oportunidades medi��ticas. Esto es, como si la arquitectura hubiera empezado a superar y optimizar algo inevitable, que las f��rmulas expositivas y las publicaciones, o m��s bien del exponer(se) y publicar(se), son herramientas disponibles para activar alg��n tipo de gesti��n intelectual de la comunicaci��n e informaci��n circulante sobre si misma. Esta pr��ctica de ���autoedici��n��� se analiza en un periodo concreto de la trayectoria de OMA -Office for Metropolitan Architecture-, estudio considerado pionero en el uso eficiente, oportunista y personalizado de los medios. As��, la segunda parte de la tesis se ocupa del an��lisis de su conocida monograf��a S,M,L,XL (1995), un volumen que cont�� con gran participaci��n por parte de sus protagonistas durante la edici��n, y de cuyo proceso de producci��n apenas se hab��a investigado. Esta publicaci��n se��al�� un punto de inflexi��n en su g��nero alterando todo formato y restricciones anteriores, y se ha convertido en un volumen emblem��tico para la disciplina que ninguna r��plica posterior ha podido superar. Aqu�� se presenta a su vez como el desencadenante de la construcci��n de un ���gran evento��� que concluye en la transformaci��n de la identidad de OMA en 10 a��os, parad��jicamente entre el nacimiento de la Fundaci��n Groszstadt y el arranque de la actividad de AMO, dos entidades paralelas clave anexas a OMA. Este planteamiento deviene de c��mo la investigaci��n desvela que S,M,L,XL es una pieza m��s, central pero no independiente, dentro de una suma de acciones e individuos, as�� como otras publicaciones, exposiciones, eventos y tambi��n art��culos ensayados y proyectos, en particular Bigness, Generic City, Euralille y los concursos de 1989. Son significativos aspectos como la apertura a una autor��a m��ltiple, encabezada por Rem Koolhaas y el dise��ador gr��fico Bruce Mau, acompa��ados en los agradecimientos de la editora Jennifer Sigler y cerca de una centena de nombres, cuyas aportaciones no necesariamente se basan en la construcci��n de fragmentos del libro. La supresi��n de ciertos l��mites permite superar tambi��n las tareas inicialmente relevantes en la edici��n de una publicaci��n. Un objetivo general de la tesis es tambi��n la reflexi��n sobre relaciones anteriormente cuestionadas, como la establecida entre la arquitectura y los mercados o la econom��a. Tomando como punto de partida la idea de ���design intelligence��� sugerida por Michael Speaks (2001), se extrae de sus argumentos que lo esencial es el hallazgo de la singularidad o inteligencia propia de cada estudio de arquitectura o dise��o. Asimismo se explora si en la construcci��n de ese tipo de f��rmulas magistrales se alojaban tambi��n combinaciones de inter��s y productivas entre asuntos como la eficiencia y la creatividad, o la organizaci��n y las ideas. En esta din��mica de relaciones bidireccionales, y en ese presente de exceso de informaci��n, se fundamenta la propuesta de una equivalencia m��s evidenciada entre la ���socializaci��n��� del trabajo del arquitecto, al compartirlo p��blicamente e introducir nuevas conversaciones, y la relaci��n inversa a partir del trabajo sobre la ���socializaci��n��� misma. Como si la consciencia sobre el uso de los medios pudiera ser efectivamente instrumental, y contribuir al desarrollo de la pr��ctica de arquitectura, desde una perspectiva idealmente comprometida e intelectual. ABSTRACT The dissertation argues the possibility to understand that the practice of architecture can find an instrumental support in the practices of communication, overcoming any classical simplification of the use of media, generally reduced to superficial treatments or promotional efforts. Thus some cases of the last decades of the 20th century are presented. Some threats detected, such as the risk of triviality, the saturation of the public image or the foreseeable wrong association among individuals when they are introduced as part of thematic groups, might have encouraged a noticeable increase of command taken by architects when there is chance to intervene in a media environment. In other words, it can be argued that architecture has started to overcome and optimize the inevitable, the fact that exhibition formulas and publications, or simply the practice of (self)exhibition or (self)publication, are tools at our disposal for the activation of any kind of intellectual management of communication and circulating information about itself. This practice of ���self-edition��� is analyzed in a specific timeframe of OMA���s trajectory, an office that is considered as a ground-breaking actor in the efficient and opportunistic use of media. Then the second part of the thesis dissects their monograph S,M,L,XL (1995), a volume in which its main characters were deeply involved in terms of edition and design, a process barely analyzed up to now. This publication marked a turning point in its own genre, disrupting old formats and traditional restrictions. It became such an emblematic volume for the discipline that none of the following attempts of replica has ever been able to improve this precedent. Here, the book is also presented as the element that triggers the construction of a ���big event��� that concludes in the transformation of OMA identity in 10 years. Paradoxically, between the birth of the Groszstadt Foundation and the early steps of AMO, both two entities parallel and connected to OMA. This positions emerge from how the research unveils that S,M,L,XL is one more piece, a key one but not an unrelated element, within a sum of actions and individuals, as well as other publications, exhibitions, articles and projects, in particular Bigness, Generic City, Euralille and the competitions of 1989. Among the remarkable innovations of the monograph, there is an outstanding openness to a regime of multiple authorship, headed by Rem Koolhaas and the graphic designer Bruce Mau, who share the acknowledgements page with the editor, Jennifer Sigler, and almost 100 people, not necessarily responsible for specific fragments of the book. In this respect, the dissolution of certain limits made possible that the expected tasks in the edition of a publication could be trespassed. A general goal of the thesis is also to open a debate on typically questioned relations, particularly between architecture and markets or economy. Using the idea of ���design intelligence���, outlined by Michael Speaks in 2001, the thesis pulls out its essence, basically the interest in detecting the singularity, or particular intelligence of every office of architecture and design. Then it explores if in the construction of this kind of ingenious formulas one could find interesting and useful combinations among issues like efficiency and creativity, or organization and ideas. This dynamic of bidirectional relations, rescued urgently at this present moment of excess of information, is based on the proposal for a more evident equivalence between the ���socialization��� of the work in architecture, anytime it is shared in public, and the opposite concept, the work on the proper act of ���socialization��� itself. As if a new awareness of the capacities of the use of media could turn it into an instrumental force, capable of contributing to the development of the practice of architecture, from an ideally committed and intelectual perspective.

Design of a compact ultra-wideband antenna

A simple method for the design of ultra-wideband antennas in planar format is presented. This method is demonstrated for a high-dielectric-constant substrate material, which allows for a considerable antenna size reduction. Simulations are performed using Ansoft's High-Frequency Structure Simulator (HFSS) for antennas assuming Du-Pont951 (epsilon(r) = 7.8) and RT6010LM (epsilon(r) = 10.2) substrates. For the 1-mm-thick DuPont951, the designed antenna with 22 X 28 nun dimensions features a 10-dB return-loss band width front 2.7 GHz to more than 15 GHz. For the 0.64-mm-thick RT6010LM a 20 X 26 nun antenna exhibits a 10-dB return loss bandwidth from 3.1 to 15 GHz. Both antennas feature nearly omnidirectional properties across the whole 10-dB return-loss bandwidth. The validity of the presented UWB antenna design strategy is confirmed by measurements performed on a prototype developed on RT6010LM substrate. (c) 2006 Wiley Periodicals, Inc.

Design of compact directive ultra wideband antipodal antenna

In this paper, a novel design procedure for designing a compact UWB antipodal Vivaldi antenna is presented. The antenna operates over the UWB frequency, band from 3.1 to more than 10.6 GHz. Its measured far-field radiation is directive and its peak gain is 10.2 dBi in the specified band. The antenna pulse response shows negligible distortion, indicating that it can be useful in a precision ranging and imaging instrumentation. (c) 2006 Wiley Periodicals, Inc.

The design of robust protocols for distributed real-time systems

Modern distributed control systems comprise of a set of processors which are interconnected using a suitable communication network. For use in real-time control environments, such systems must be deterministic and generate specified responses within critical timing constraints. Also, they should be sufficiently robust to survive predictable events such as communication or processor faults. This thesis considers the problem of coordinating and synchronizing a distributed real-time control system under normal and abnormal conditions. Distributed control systems need to periodically coordinate the actions of several autonomous sites. Often the type of coordination required is the all or nothing property of an atomic action. Atomic commit protocols have been used to achieve this atomicity in distributed database systems which are not subject to deadlines. This thesis addresses the problem of applying time constraints to atomic commit protocols so that decisions can be made within a deadline. A modified protocol is proposed which is suitable for real-time applications. The thesis also addresses the problem of ensuring that atomicity is provided even if processor or communication failures occur. Previous work has considered the design of atomic commit protocols for use in non time critical distributed database systems. However, in a distributed real-time control system a fault must not allow stringent timing constraints to be violated. This thesis proposes commit protocols using synchronous communications which can be made resilient to a single processor or communication failure and still satisfy deadlines. Previous formal models used to design commit protocols have had adequate state coverability but have omitted timing properties. They also assumed that sites communicated asynchronously and omitted the communications from the model. Timed Petri nets are used in this thesis to specify and design the proposed protocols which are analysed for consistency and timeliness. Also the communication system is mcxielled within the Petri net specifications so that communication failures can be included in the analysis. Analysis of the Timed Petri net and the associated reachability tree is used to show the proposed protocols always terminate consistently and satisfy timing constraints. Finally the applications of this work are described. Two different types of applications are considered, real-time databases and real-time control systems. It is shown that it may be advantageous to use synchronous communications in distributed database systems, especially if predictable response times are required. Emphasis is given to the application of the developed commit protocols to real-time control systems. Using the same analysis techniques as those used for the design of the protocols it can be shown that the overall system performs as expected both functionally and temporally.

The design of fault tolerant software for loosely coupled distributed systems

Requirements for systems to continue to operate satisfactorily in the presence of faults has led to the development of techniques for the construction of fault tolerant software. This thesis addresses the problem of error detection and recovery in distributed systems which consist of a set of communicating sequential processes. A method is presented for the `a priori' design of conversations for this class of distributed system. Petri nets are used to represent the state and to solve state reachability problems for concurrent systems. The dynamic behaviour of the system can be characterised by a state-change table derived from the state reachability tree. Systematic conversation generation is possible by defining a closed boundary on any branch of the state-change table. By relating the state-change table to process attributes it ensures all necessary processes are included in the conversation. The method also ensures properly nested conversations. An implementation of the conversation scheme using the concurrent language occam is proposed. The structure of the conversation is defined using the special features of occam. The proposed implementation gives a structure which is independent of the application and is independent of the number of processes involved. Finally, the integrity of inter-process communications is investigated. The basic communication primitives used in message passing systems are seen to have deficiencies when applied to systems with safety implications. Using a Petri net model a boundary for a time-out mechanism is proposed which will increase the integrity of a system which involves inter-process communications.

An argument for using participatory approaches for the design of online health interventions targeted at young women

The Internet is becoming an increasingly important portal to health information and means for promoting health in user populations. As the most frequent users of online health information, young women are an important target population for e-health promotion interventions. Health-related websites have traditionally been generic in design, resulting in poor user engagement and affecting limited impacts on health behaviour change. Mounting evidence suggests that the most effective health promotion communication strategies are collaborative in nature, fully engaging target users throughout the development process. Participatory design approaches to interface development enable researchers to better identify the needs and expectations of users, thus increasing user engagement in, and promoting behaviour change via, online health interventions. This article introduces participatory design methods applicable to online health intervention design and presents an argument for the use of such methods in the development of e-Health applications targeted at young women.

Design of Raman-based NOLM for optical 2R regeneration of RZ-DPSK transmission

We present a concept for all-optical differential phase-shift keying (DPSK) signal regeneration, based on a new design of Raman amplified nonlinear loop mirror (RA-NOLM). We demonstrate simultaneous amplitude-shape regeneration and phase noise reduction in high-speed DPSK systems by use of the RA-NOLM combined with spectral filtering.

Design of Raman-based NOLM for optical 2R regeneration of RZ-DPSK transmission

We present a concept for all-optical differential phase-shift keying (DPSK) signal regeneration, based on a new design of Raman amplified nonlinear loop mirror (RA-NOLM). We demonstrate simultaneous amplitude-shape regeneration and phase noise reduction in high-speed DPSK systems by use of the RA-NOLM combined with spectral filtering.

Design of nonlinear regenerative transmission systems with high capacity

We present the design of nonlinear regenerative communication channels that have capacity above the classical Shannon capacity of the linear additive white Gaussian noise channel. The upper bound for regeneration efficiency is found and the asymptotic behavior of the capacity in the saturation regime is derived. �� 2013 IEEE.

Logical simulation of communication subsystem for Universal Serial Bus (USB)

The primary purpose of this thesis was to design a logical simulation of a communication sub block to be used in the effective communication of digital data between the host and the peripheral devices. The module designed is a Serial interface engine in the Universal Serial Bus that effectively controls the flow of data for communication between the host and the peripheral devices with the emphasis on the study of timing and control signals, considering the practical aspects of them. In this study an attempt was made to realize data communication in the hardware using the Verilog Hardware Description language, which is supported by most popular logic synthesis tools. Various techniques like Cyclic Redundancy Checks, bit-stuffing and Non Return to Zero are implemented in the design to provide enhanced performance of the module.