158,159 research outputs found
Schema architecture and their relationships to transaction processing in distributed database systems
We discuss the different types of schema architectures which could be supported by distributed database systems, making a clear distinction between logical, physical, and federated distribution. We elaborate on the additional mapping information required in architecture based on logical distribution in order to support retrieval as well as update operations. We illustrate the problems in schema integration and data integration in multidatabase systems and discuss their impact on query processing. Finally, we discuss different issues relevant to the cooperation (or noncooperation) of local database systems in a heterogeneous multidatabase system and their relationship to the schema architecture and transaction processing
Object-oriented querying of existing relational databases
In this paper, we present algorithms which allow an object-oriented
querying of existing relational databases. Our goal is to provide an improved query
interface for relational systems with better query facilities than SQL. This
seems to be very important since, in real world applications, relational systems
are most commonly used and their dominance will remain in the near future. To
overcome the drawbacks of relational systems, especially the poor query facilities
of SQL, we propose a schema transformation and a query translation algorithm.
The schema transformation algorithm uses additional semantic information to enhance
the relational schema and transform it into a corresponding object-oriented
schema. If the additional semantic information can be deducted from an underlying
entity-relationship design schema, the schema transformation may be done
fully automatically. To query the created object-oriented schema, we use the
Structured Object Query Language (SOQL) which provides declarative query facilities
on objects. SOQL queries using the created object-oriented schema are
much shorter, easier to write and understand and more intuitive than corresponding
S Q L queries leading to an enhanced usability and an improved querying of
the database. The query translation algorithm automatically translates SOQL queries
into equivalent SQL queries for the original relational schema
Modeling of Traceability Information System for Material Flow Control Data.
This paper focuses on data modeling for traceability of material/work flow in information
layer of manufacturing control system. The model is able to trace all associated data throughout the
product manufacturing from order to final product. Dynamic data processing of Quality and Purchase
activities are considered in data modeling as well as Order and Operation base on lots particulars. The
modeling consisted of four steps and integrated as one final model. Entity-Relationships Modeling as
data modeling methodology is proposed. The model is reengineered with Toad Data Modeler software
in physical modeling step. The developed model promises to handle fundamental issues of a
traceability system effectively. It supports for customization and real-time control of material in flow
in all levels of manufacturing processes. Through enhanced visibility and dynamic store/retrieval of
data, all traceability usages and applications is responded. Designed solution is initially applicable as
reference data model in identical lot-base traceability system
Leachate treatment by conventional coagulation, electrocoagulation and two-stage coagulation (conventional coagulation and electrocoagulation)
Leachate is widely explored and investigated due to highly polluted and difficult to treat. Leachate treatment commonly involves advanced, complicated and high cost activities. Conventional coagulation is widely used in the treatment of wastewater but the sludge production becomes the biggest constraint in this treatment. Electrocoagulation is an alternative to conventional method because it has the same application but produce less sludge and requires simple equipment. Thus, combination of conventional coagulation and electrocoagulation can improve the efficiency of coagulation process in leachate treatment. This article is focusing on the efficiency of single and combined treatment as well as the improvement made by combined treatment. Based on review, the percentage reduction of current density and dose of coagulant was perceptible. As much 50% reduction of current density, duration of treatment, and dose of coagulant able to be obtained by using combined treatment. This combined treatment is able to reduce the cost and at the same time reduce the duration of treatment. Hence, the combined treatment offers an alternative technique for landfill leachate treatment on the removal of pollutants
Web GIS-Based Flood Management System for the Architectural Heritage
학위논문 (석사)-- 서울대학교 대학원 : 건축학과, 2015. 2. 이현수.In recent years, flood damage is drastically increasing due to global warming, urbanization, irregular weather condition and so on. Especially, flash flood by torrential rain and locally heavy rainfall damage the architectural heritage before an appropriate measure is taken.
Multilateral efforts are put into solving the issue, however, weakness in effectively responding to the flood risk toward the cultural heritage buildings located all over the nation exists.
To solve the problem, the Cultural Heritage Administration conducted researches from 2009 to 2012. Despite efforts, however, there are difficulties in actively corresponding to the flood disaster due to unclassified research data, low accessibility to the information and so on.
To address these limitations, this research attempts to present an effective flood management system by integrating Web Geographic Information System (Web-GIS) with Relational Database Management System (RDBMS) and using real-time rainfall data.
Compared to the traditional system, suggested Web GIS based flood management system is expected to be more efficient, adaptable and flexible. Ultimately, this research aims to be more supportive tool for flood risk managers decision making.Chapter 1 Introduction 1
1.1 Research Objective 1
1.2 Research Scope and Process 2
Chapter 2 Literature Review 5
2.1 Flood Risk Management for Architectural Heritage 5
2.2 Flash Flood and Response Time 8
2.3 Flood Risk Managers Decision Making 10
2.4 Summary 12
Chapter 3 Database for the System 13
3.1 Database Overview 13
3.2 Data Classification and DB Development 15
3.3 Entity Relationship Diagram Design 18
3.4 Summary 20
Chapter 4 Web Geographic Information System 21
Chapter 5 Flood Management System 23
5.1 System Requirements 23
5.2 System Architecture Design 25
5.3 System Interface and Function 27
5.4 Expression of Real Time Flood Risk 29
5.5 Provision of Reaction Manual 33
5.6 Summary 35
Chapter 6 System Usability Evaluation 36
6.1 Overview 36
6.2 Selection of Subjects 37
6.3 Evaluation Factor 38
6.4 Result and Analysis 39
Chapter 7 Conclusion 42
7.1 Research Results 42
7.2 Contributions 43
7.3 Limitations and Future Researches 44
Reference 45
Abstract (Korean) 50Maste
Recommended from our members
Learning from AI : new trends in database technology
Recently some researchers in the areas of database data modelling and knowledge representations in artificial intelligence have recognized that they share many common goals. In this survey paper we show the relationship between database and artificial intelligence research. We show that there has been a tendency for data models to incorporate more modelling techniques developed for knowledge representations in artificial intelligence as the desire to incorporate more application oriented semantics, user friendliness, and flexibility has increased. Increasing the semantics of the representation is the key to capturing the "reality" of the database environment, increasing user friendliness, and facilitating the support of multiple, possibly conflicting, user views of the information contained in a database
Effect of gap lenghts of sphere-sphere electrodes on air breakdown level under lightning impulse
Impinging jets are a best method of achieving particularly high heat transfer
coefficient and are therefore employed in many engineering applications. In this
study we seek to understand the mechanism of the distributed heat on the curve
surface with the goal of identifying preferred methods to predicting jet performance.
The goals that have been achieved in the numerical results displayed are
determine the influence of impingement jet characteristics on thermal and flow field
on a curve surface, determine the variation of Nusselt numbers (NuD) along the
curve surface in order to understand the heat transfer characteristics and study the
effect of position (in the center, in the mid and in the end) and angle (α=90°, 60° and
30°) of jet impingement on curve surface, different Reynolds numbers (ReD) in
range of (5000, 6000, 7000, 8000 and 9000). The program, which was extracted
results it is (GAMBIT 2.4.6) and (FLUENT 6.3), simulation is (2-D) in submerged
jet flow and the continuity, momentum and energy equations were solved by means
of a finite volume method (FVM).
This study covers the effect of different Reynolds numbers (ReD) on average
Nusselt numbers (Nuavg) and local Nusselt numbers (NuD). From the result, the
average Nusselt numbers (Nuavg) increased with the increase of Reynolds numbers
(ReD) for all cases, in comparison between different positions (center, mid and end),
of nozzle on curve surface at angle (α=90°) the maximum value of average Nusselt
numbers (Nuavg=388.3) is found when the nozzle locate in the end followed by the
mid position and smallest value of average Nusselt numbers (Nuavg=182.25) in the
center of curve surface. In case of slant angle (α=60º) the maximum value of average
Nusselt numbers (Nuavg=387.47) is found when the nozzle locate in the end
followed by the mid position and smallest value of average Nusselt numbers
(Nuavg=308.3) in the center of curve surface
- …