Special Libraries, July 1984

Volume 75, Issue 3https://scholarworks.sjsu.edu/sla_sl_1984/1002/thumbnail.jp

Development of a knowledge-based system for the repair and maintenance of concrete structures

PhD ThesisInformation Technology (IT) can exploit strategic opportunities for new ways of facilitating information and data exchange and the exchange of expert and specialist opinions in any field of engineering. Knowledge-Based Systems are sophisticated computer programs which store expert knowledge on specific subject and are applied to a broad range of engineering problems. Integrated Database applications have facilitated the essential capability of storing data to overcome an increasing information malaise. Integrating these areas of Information Technology (IT) can be used to bring a group of experts in any field of engineering closer together by allowing them to communicate and exchange information and opinions. The central feature of this research study is the integration of these hitherto separate areas of Information Technology (IT). In this thesis an adaptable Graphic User Interface Centred application comprising a Knowledge-Based Expert System (DEMARECEXPERT), a Database Management System (REPCON) and Evaluation program (ECON) alongside visualisation technologies is developed to produce an innovative platform which will facilitate and encourage the development of knowledge in concrete repair. Diagnosis, Evaluation, MAintenance and REpair of Concrete structures (DEMAREQ is a flexible application which can be used in four modes of Education, Diagnostic, Evaluation and Evolution. In the educational mode an inexperienced user can develop a better understanding of the repair of concrete technology by navigating through a database of textual and pictorial data. In the diagnostic mode, pictures and descriptive information taken from the database and performance of the expert system (DEMAREC-EXPERT) are used in a way that makes problem solving and decision making easier. The DEMAREC-EXPERT system is coupled to the REPCON (as an independent database) in order to provide the user with recommendations related to the best course required for maintenance and in the selection of materials and methods for the repair of concrete. In the evaluation mode the conditions observed are described in unambiguous terms that can be used by the user to be able to take engineering and management actions for the repair and maintenance of the structure. In the evolution mode of the application, the nature of distress, repair and maintenance of concrete structures within the extent of the database management system has been assessedT. he new methodology of data/usere valuation could have wider implications in many knowledge rich areas of expertise. The benefit of using REPCON lies in the enhanced levels of confidence which can be attributed to the data and to contribution of that data. Effectively, REPCON is designed to model a true evolution of a field of expertise but allows that expertise to move on in faster and more structured manner. This research has wider implications than within the realm of concrete repair. The methodology described in this thesis is developed to provide tecýnology transfer of information from experts, specialists to other practitioners and vice versa and it provides a common forum for communication and exchange information between them. Indeed, one of the strengths of the system is the way in which it allows the promotion and relegation of knowledge according to the opinion of users of different levels of ability from expert to novice. It creates a flexible environment in which an inexperienced user can develop his knowledge in maintenance and concrete repair structures. It is explained how an expert and a specialist can contribute his experience and knowledge towards improving and evolving the problem solving capability of the application

Relational Extensions : Object-Relational and XML Extensions

Mòdul 2 del llibre Database Architecture. UOC, 20122022/202

Empowering a Relational Database with LSD: Lazy State Determination

Computer systems are a part of today’s most common activities and, more often than not, involve some type of interaction with a database. In this scheme, databases play a big role, where even small operational delays could cost millions to big tech companies. It is then, of utmost importance that such systems are responsive and adapt automatically to different types of workload. To this date, Relational Database Management System remain the most popular database type, which allows the executing of concurrent transactions with Atomicity, Consistency, Isolation and Durability guarantees. Enforcing such properties requires strict control over the execution of transactions. However, maintaining such properties and controlling the transactions’ concurrency may hamper performance of the system, being this specially the case when database contention is high. Motivated by such behavior, we propose the lazy evaluation of database SQL queries — using Futures/Promises and Java Database Connectivity (JDBC) — by empowering a relational database with Lazy State Determination (LSD). This novel Application Programming Interface (API) allows delaying operations to the commit time, which in the end reduces the transaction window where conflicts may occur. We observed that, by introducing our implementation of a JDBC-LSD driver, in high contention scenarios the throughput increased by 50% and latency reduced by 40%.Os sistemas informáticos são parte das atividades mais comuns na atualidade e, na maioria das vezes, envolvem algum tipo de interação com uma base de dados. Neste cenário, as bases de dados têm um grande papel, sendo que pequenos atrasos operacionais podem custar milhões às grandes empresas tecnológicas. Até os dias de hoje, os Sistemas de Gestão de Bases de Dados Relacionais continuam a ser o tipo de bases de dados mais popular, permitindo a execução concorrente de transações garantindo as propriedades de Atomicidade, Consistência, Isolamento e Durabilidade. A aplicação de tais propriedades requer um controlo rigoroso sobre a execução de transações. No entanto, manter tais propriedades e controlar a concorrência das transacções pode diminuir o desempenho do sistema, sendo especialmente o caso em bases onde a contenção é elevada. Assim, propomos o atraso na execução de queries SQL na base de dados através da introdução do protocolo de controlo de concorrência Lazy State Determination (LSD), com a utilização de Futuros/Promessas e Java Database Connectivity (JDBC). Esta nova Interface de Programação de Aplicações (API) permite adiar as operações para o momento do commit, o que acaba por reduzir a janela da transação onde conflitos podem ocorrer. Observamos que, ao utilizar LSD em um cliente JDBC, nós conseguimos aumentar a taxa de execução de transações em 50% e reduzir a latência em 40% num ambiente de contenção elevada