1,535 research outputs found
The use of alternative data models in data warehousing environments
Data Warehouses are increasing their data volume at an accelerated rate; high disk
space consumption; slow query response time and complex database administration are
common problems in these environments. The lack of a proper data model and an
adequate architecture specifically targeted towards these environments are the root
causes of these problems.
Inefficient management of stored data includes duplicate values at column level and
poor management of data sparsity which derives from a low data density, and affects
the final size of Data Warehouses. It has been demonstrated that the Relational Model
and Relational technology are not the best techniques for managing duplicates and data
sparsity.
The novelty of this research is to compare some data models considering their data
density and their data sparsity management to optimise Data Warehouse environments.
The Binary-Relational, the Associative/Triple Store and the Transrelational models
have been investigated and based on the research results a novel Alternative Data
Warehouse Reference architectural configuration has been defined.
For the Transrelational model, no database implementation existed. Therefore it was
necessary to develop an instantiation of itâs storage mechanism, and as far as could be
determined this is the first public domain instantiation available of the storage
mechanism for the Transrelational model
Design and implementation of an integrated surface texture information system for design, manufacture and measurement
The optimised design and reliable measurement of surface texture are essential to guarantee the functional performance of a geometric product. Current support tools are however often limited in functionality, integrity and efficiency. In this paper, an integrated surface texture information system for design, manufacture and measurement, called âCatSurfâ, has been designed and developed, which aims to facilitate rapid and flexible manufacturing requirements. A category theory based knowledge acquisition and knowledge representation mechanism has been devised to retrieve and organize knowledge from various Geometrical Product Specifications (GPS) documents in surface texture. Two modules (for profile and areal surface texture) each with five components are developed in the CatSurf. It also focuses on integrating the surface texture information into a Computer-aided Technology (CAx) framework. Two test cases demonstrate design process of specifications for the profile and areal surface texture in AutoCAD and SolidWorks environments respectively
The exploration of a category theory-based virtual Geometrical product specification system for design and manufacturing
In order to ensure quality of products and to facilitate global outsourcing, almost all
the so-called âworld-classâ manufacturing companies nowadays are applying various
tools and methods to maintain the consistency of a productâs characteristics
throughout its manufacturing life cycle. Among these, for ensuring the consistency of
the geometric characteristics, a tolerancing language â the Geometrical Product
Specification (GPS) has been widely adopted to precisely transform the functional
requirements from customers into manufactured workpieces expressed as tolerance
notes in technical drawings. Although commonly acknowledged by industrial users as
one of the most successful efforts in integrating existing manufacturing life-cycle
standards, current GPS implementations and software packages suffer from several
drawbacks in their practical use, possibly the most significant, the difficulties in
inferring the data for the âbestâ solutions. The problem stemmed from the foundation
of data structures and knowledge-based system design. This indicates that there need
to be a ânewâ software system to facilitate GPS applications.
The presented thesis introduced an innovative knowledge-based system â the
VirtualGPS â that provides an integrated GPS knowledge platform based on a stable
and efficient database structure with knowledge generation and accessing facilities.
The system focuses on solving the intrinsic product design and production problems
by acting as a virtual domain expert through translating GPS standards and rules into
the forms of computerized expert advices and warnings. Furthermore, this system can
be used as a training tool for young and new engineers to understand the huge amount
of GPS standards in a relative âquickerâ manner.
The thesis started with a detailed discussion of the proposed categorical modelling
mechanism, which has been devised based on the Category Theory. It provided a
unified mechanism for knowledge acquisition and representation, knowledge-based
system design, and database schema modelling. As a core part for assessing this
knowledge-based system, the implementation of the categorical Database
Management System (DBMS) is also presented in this thesis. The focus then moved
on to demonstrate the design and implementation of the proposed VirtualGPS system.
The tests and evaluations of this system were illustrated in Chapter 6. Finally, the
thesis summarized the contributions to knowledge in Chapter 7.
After thoroughly reviewing the project, the conclusions reached construe that the
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entire VirtualGPS system was designed and implemented to conform to Category
Theory and object-oriented programming rules. The initial tests and performance
analyses show that the system facilitates the geometric product manufacturing
operations and benefits the manufacturers and engineers alike from function designs,
to a manufacturing and verification
The advantages and cost effectiveness of database improvement methods
Relational databases have proved inadequate for supporting new classes of
applications, and as a consequence, a number of new approaches have been taken
(Blaha 1998), (Harrington 2000). The most salient alternatives are denormalisation
and conversion to an object-oriented database (Douglas 1997). Denormalisation
can provide better performance but has deficiencies with respect to
data modelling. Object-oriented databases can provide increased performance
efficiency but without the deficiencies in data modelling (Blaha 2000).
Although there have been various benchmark tests reported, none of these
tests have compared normalised, object oriented and de-normalised databases.
This research shows that a non-normalised database for data containing type
code complexity would be normalised in the process of conversion to an objectoriented
database. This helps to correct badly organised data and so gives the
performance benefits of de-normalisation while improving data modelling.
The costs of conversion from relational databases to object oriented databases
were also examined. Costs were based on published benchmark tests, a
benchmark carried out during this study and case studies. The benchmark tests
were based on an engineering database benchmark. Engineering problems such as
computer-aided design and manufacturing have much to gain from conversion to
object-oriented databases. Costs were calculated for coding and development, and
also for operation. It was found that conversion to an object-oriented database was
not usually cost effective as many of the performance benefits could be achieved
by the far cheaper process of de-normalisation, or by using the performance
improving facilities provided by many relational database systems such as
indexing or partitioning or by simply upgrading the system hardware.
It is concluded therefore that while object oriented databases are a better
alternative for databases built from scratch, the conversion of a legacy relational
database to an object oriented database is not necessarily cost effective
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 tecĂœnology 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
Intelligent urban water infrastructure management
Copyright © 2013 Indian Institute of ScienceUrban population growth together with other pressures, such as climate change, create enormous challenges to provision of urban infrastructure services, including gas, electricity, transport, water, etc. Smartgrid technology is viewed as the way forward to ensure that infrastructure networks are fl exible, accessible, reliable and economical. âIntelligent water networksâ take advantage of the latest information and communication technologies to gather and act on information to minimise waste and deliver more sustainable water services. The effective management of water distribution, urban drainage and sewerage infrastructure is likely to require increasingly sophisticated computational techniques to keep pace with the level of data that is collected from measurement instruments in the field. This paper describes two examples of intelligent systems developed to utilise this increasingly available real-time sensed information in the urban water environment. The first deals with the failure-management decision-support system for water distribution networks, NEPTUNE, that takes advantage of intelligent computational methods and tools applied to near real-time logger data providing pressures, flows and tank levels at selected points throughout the system. The second, called RAPIDS, deals with urban drainage systems and the utilisation of rainfall data to predict flooding of urban areas in near real-time. The two systems have the potential to provide early warning and scenario testing for decision makers within reasonable time, this being a key requirement of such systems. Computational methods that require hours or days to run will not be able to keep pace with fast-changing situations such as pipe bursts or manhole flooding and thus the systems developed are able to react in close to real time.Engineering and Physical Sciences Research CouncilUK Water Industry ResearchYorkshire Wate
Review on Main Memory Database
The idea of using Main Memory Database (MMDB) as physical memory is not new but is in existence quite since a decade. MMDB have evolved from a period when they were only used for caching or in high-speed data systems to a time now in twenty first century when they form a established part of the mainstream IT. Early in this century, although larger main memories were affordable but processors were not fast enough for main memory databases to be admired. However, todayâs processors are faster, available in multicore and multiprocessor configurations having 64-bit memory addressability stocked with multiple gigabytes of main memory. Thus, MMDBs definitely call for a solution for meeting the requirements of next generation IT challenges. To aid this swing, database systems are reconsidered to handle implementation issues adjoining the inherent differences between disk and memory storage and gain performance benefits. This paper is a review on Main Memory Databases (MMDB)
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