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.

FREADMAN, AnneThe Livres-Souvenirs of Colette Genre and the Telling of Time Oxford: Legenda, August 2012200 pp., £40.00, ISBN: 978-1-906540-93-7

Full text: The title of the book gives us a major clue on the innovative approach developed by Anne Freadman in her analysis of a particular Colette corpus, the one devoted to auto-biographical writing: Les Vrilles de la vigne, Mes apprentissages, La Maison de Claudine, Sido ,L’E ́toile Vesper and Le Fanal bleu. Freadman follows the powerful lure of Rimbaldianvieilles vieilleries and its echoes with Colette’s fondness for collecting objects, people and memories. To this must be added a technical aspect, that of the study of the genre of Colette’s writing. Freadman argues that, by largely avoiding the autobiographical form, the writer achieves a new way of ‘telling time’, collecting anecdotes and detail taken from the quotidian and setting them within an all-encompassing preoccupation with time. This provides the second part of the title.The sonata form directs the sequence of the book, orchestrated into five parts,from ‘exposition’ to ‘first subject’ to‘bridge’ to ‘second subject’ to ‘recapitulation’. This has the advantage of enabling Freadman to move and progress between distinct themes—autobiography first,then alternative forms—with grace,whilst preserving within her own writing what she sees as the essence of Colette’s relationship to time in her ‘Livres-Souvenirs’, the telling of time. This‘telling of time’ is itself therefore cleverly subjected to the time constraints and freedoms of musical composition. Freadman’s ‘Exposition’ takes us through a discussion of the autobiographical genre, analysing the texts against anumber of theorists, from Lejeune to Benjamin and Ricoeur, before launching into ‘Colette and Autobiography’. It argues pertinently that Colette did not write a ‘sustained’ autobiography, even inthe most autobiographical of her writings, Mes apprentissages. Measured against Goodwin’s three sources for autobiography, confession, apologia and memoirs, Colette’s autobiographical writings appear to be at odds with all of them. Freadman then goes on in Part II of her argument, to persuasively uncover a project that rejects self-scrutiny and with no autobiographical strategy. In ‘Collecting Time’, despite claims of continuity, narrative logic and causality areabandoned in favour of a collection offragments, family stories that are built up generation after generation into familylegends. A close and fruitful analysis of Sidoleads us to a study of ‘The Art of Ending’, concentrating on L’E ́toile Vesperandle Fanal Bleu. The closing chapter gives a fascinating reading of La Naissance du jouras an exemplar of the way in which the two subjects developed in Freadman’s volume are cast together:Colette’s own working through the autobiographical genre, and her refusal to write memoirs, in favour of collecting memories, and the strategies she uses for her purpose. In ‘Recapitulation’, her concluding chapter, Freadman adroitlyen capsulates her analysis in a fetching title: ‘Fables of Time’. Indeed, the wholepremise of her book is to move away from autobiographical genre, having acknowledged the links and debt the corpus owes to it, and into a study of the multiple and fruitful ways in which Colette tells time.The rich and varied readings of thematerial, competently informed by theoretical input, together with acute sensitivity to the corpus, mark out this study as incontournable for Colette scholars.

The effects of varying forms and degrees of government intervention upon the effective competitiveness of UK small businesses

This doctoral thesis responds to the need for greater understanding of small businesses and their inherent unique problem-types. Integral to the investigation is the theme that for governments to effectively influence small business, a sound understanding of the factors they are seeking to influence is essential. Moreover, the study, in its recognition of the many shortcomings in management research and, in particular that the research methods and approaches adopted often fail to give adequate understanding of issues under study, attempts to develop an innovative and creative research approach. The aim thus being to produce, not only advances in small business management knowledge from the standpoints of government policy makers and `lq recipient small business, but also insights into future potential research method for the continued development of that knowledge. The origins of the methodology lay in the non-acceptance of traditional philosophical positions in epistemology and ontology, with a philosophical standpoint of internal realism underpinning the research. Internal realism presents the basis for the potential co-existence of qualitative and quantitative research strategy and underlines the crucial contributory role of research method in provision of ultimate factual status of the assertions of research findings. The concept of epistemological bootstrapping is thus used to develop a `lq partial research framework to foothold case study research, thereby avoiding limitations of objectivism and brute inductivism. The major insights and issues highlighted by the `lq bootstrap, guide the researcher around the participant case studies. A novel attempt at contextualist (linked multi-level and processual) analysis was attempted in the major in-depth case study, with two further cases playing a support role and contributing to a balanced emphasis of empirical research within the context of time constraints inherent within part-time research.

An evaluation of pharmacy education and pre-registration training

This thesis covers two major aspects of pharmacy education; undergraduate education and pre-registration training. A cohort of pharmacy graduates were surveyed over a period of four years, on issues related to undergraduate education, pre-registration training and continuing education. These graduates were the first-ever to sit the pre-registration examination. In addition, the opinions of pre-registration tutors were obtained on pre-registration training, during the year that competence-based assessment was introduced. It was concluded that although the undergraduate course provided a broad base of knowledge suitable for graduates in all branches of pharmacy, several issues were identified which would require attention in future developments of the course. These were: 1. the strong support for the expansion of clinical, social and practice-based teaching. 2. the strong support to retain the scientific content to the same extent as in the three-year course. 3. a greater use of problem-based learning methods. The graduates supported the provision of a pre-registration continuing education course to help prepare for the examination and in areas inadequately covered in the undergraduate course. There was also support for the introduction of some form of split branch training. There was no strong evidence to suggest that the training had been an application of undergraduate education. In general, competence-based training was well regarded by tutors as an appropriate and effective method of skill assessment. However, community tutors felt it was difficult to carry out effectively due to day-to-day time constraints. The assistant tutors in hospital pharmacy were found to have a very important role in provision of training, and should be adequately trained and supported. The study recommends the introduction of uniform training and a quality assurance mechanism for all tutors and assistants undertaking this role.

Classification and contextual enhancement of remotely sensed data

The aims of the project were twofold: 1) To investigate classification procedures for remotely sensed digital data, in order to develop modifications to existing algorithms and propose novel classification procedures; and 2) To investigate and develop algorithms for contextual enhancement of classified imagery in order to increase classification accuracy. The following classifiers were examined: box, decision tree, minimum distance, maximum likelihood. In addition to these the following algorithms were developed during the course of the research: deviant distance, look up table and an automated decision tree classifier using expert systems technology. Clustering techniques for unsupervised classification were also investigated. Contextual enhancements investigated were: mode filters, small area replacement and Wharton's CONAN algorithm. Additionally methods for noise and edge based declassification and contextual reclassification, non-probabilitic relaxation and relaxation based on Markov chain theory were developed. The advantages of per-field classifiers and Geographical Information Systems were investigated. The conclusions presented suggest suitable combinations of classifier and contextual enhancement, given user accuracy requirements and time constraints. These were then tested for validity using a different data set. A brief examination of the utility of the recommended contextual algorithms for reducing the effects of data noise was also carried out.