Nest and Unnest Operators in Nested Relations

By distinguishing nested attributes as Decomposable and Non-Decomposable, it is proved that for all nested relations, unnesting and then renesting on the same attribute yields the original relation subject only to the elimination of duplicate data. Therefore, the statement that was popular in nested relations research: "Unnesting and then nesting on the same attribute of a nested relation does not always yield the original relation" is reconsidered

A TEMPORAL DATABASE MODEL USING NESTED RELATIONS

“Ka ˆ crÒnoj mšn ™sti tÕ di£sthma kaq ' Ö pr£tteta … ti.” ’OlumpiÒdwroj, Commentarii in Ecclesiasten, Vol. 98, p. 508, l. 8 (Migne, Patrologia Graeca) Relaxing the First Normal Form (1NF) assumption of relational databases gives rise to Non-First Normal Form relations or nested relations for short. Nested relations overcome a number of problems that the apparently reasonable restriction of 1NF condition causes. The need to support time in database systems, in order to model temporal events in the real world, has been addressed over the last two decades, reflecting the importance of that for almost every computer system application. This thesis combines the features of previous nested and temporal models to develop a new integrated Temporal Nested Model (TNM). TNM is a temporal, nested, attribute timestamping, heterogeneous databas

Building a Lung and Ovarian Cancer Data Warehouse

Objectives: Despite the collection of vast amounts of data by the healthcare sector, effective decision-making in medical practice is still challenging. Data warehousing technology can be applied for the collection and management of clinical data from various sources to provide meaningful insights for physicians and administrators. Cancer data are extremely complicated and massive; hence, a clinical data warehouse system can provide insights into prevention, diagnosis and treatment processes through the use of online analytical processing tools for the analysis of multi-dimensional data at different granularity levels. Methods: In this study, a clinical data warehouse was developed for lung cancer data, which were kindly provided by the United States National Cancer Institute. Lung and ovarian cancer data were imported in specific formats and cleaned to remove errors and redundancies. SQL server integration services (SSIS) were used for the extract-transform-load (ETL) process. Results: The design of the clinical data warehouse responds efficiently to all types of queries by adopting the fact constellation schema model. Various online analytical processing queries can be expressed using the proposed approach. Conclusions: This model succeeded in responding to complex queries, and the analysis of data is facilitated by using online analytical processing cubes and viewing multilevel data details

Maintaining Dimension's History in Data Warehouses Effectively

A data warehouse is considered a key aspect of success for any decision support system. Research on temporal databases have produced important results in this field, and data warehouses, which store historical data, can clearly benefit from such studies. A slowly changing dimension is a dimension in which any of its attributes in a data warehouse can change infrequently over time. Although different solutions have been proposed, each has its own particular disadvantages. The authors propose the Object-Relational Temporal Data Warehouse (O-RTDW) model for the slowly changing dimensions in this research work. Using this approach, it is possible to keep track of the whole history of an object in a data warehouse efficiently. The proposed model has been implemented on a real data set and tested successfully. Several limitations implied in other solutions, such as redundancy, surrogate keys, incomplete historical data, and creation of additional tables are not present in our solution

Qualitative methods in control of industrial production units

Abstract:- The research in this paper deals with the application of qualitative models and statistical methods in quality control of production procedures of various components of industrial press machines. The qualitative simulation of discrete-event machine systems is often based upon the use of qualitative simulation and discrete-event methods techniques too. In order to describe and analyze machine systems and processes in their most efficient way a combination of both advanced qualitative modelling techniques and numerical methods is used. An object-oriented qualitative modelling and simulation toolbox, called QMTOOL, was extended and applied to real industrial machines and processes. The final analysis of the simulation results is accomplished using statistical and mathematical methods and applications for the evaluation of the final machine components as well as the production procedures. The important role of the qualitative modeling methodologies and the reliability of the statistical functions used are documented with practical case studies carried out in a machines constructions company. The results obtained proved that this qualitative modelling approach provided less complex computational models for describing and simulating such machine components. Key-Words:- Qualitative, modelling, statistical, production

A trajectory data warehouse solution for workforce management decision-making

In modern workforce management, the demand for new ways to maximize worker satisfaction, productivity, and security levels is endless. Workforce movement data such as those source data from an access control system can support this ongoing process with subsequent analysis. In this study, a solution for attaining this goal is proposed, based on the design and implementation of a data mart as part of a dimensional trajectory data warehouse (TDW) that acts as a repository for the management of movement data. A novel methodological approach is proposed for modeling multiple spatial and temporal dimensions in a logical model. The case study presented in this paper for modeling and analyzing workforce movement data is to support human resource management decision-making and the following discussion provides a representative example of the contribution of a TDW in the process of information management and decision support systems. The entire process of exporting, cleaning, consolidating, and transforming data is implemented to achieve an appropriate format for final import. Structured query language (SQL) queries demonstrate the convenience of dimensional design for data analysis, and valuable information can be extracted from the movements of employees on company premises to manage the workforce efficiently and effectively. Visual analytics through data visualization support the analysis and facilitate decision-making and business intelligence

Qualitative Modelling of Manufacturing Machinery

Abstract – The research in this paper deals with the simulation of continuous machine systems that can be described in a discrete manner (discrete-event systems), using qualitative simulation techniques. In order to represent discrete-time descriptions of machine systems and processes in an efficient way, this approach uses a combination of both qualitative modelling techniques and numerical methods. An objectoriented qualitative modelling and simulation toolbox, called QMTOOL, was extended and applied into modelling specific machine processes. Experiments carried out using this qualitative modelling and simulation toolbox, provided performance metrics and assisted the design and real-time control of specific industrial machines and processes. The results obtained have shown that qualitative modelling can provide less complex computational models for describing and simulating discrete-event machine systems, and that these models could be applied in cases where traditional mathematical models are difficult to manage. I

Towards Moving Objects Behavior Analysis: Region Speed Limit Rate Measure

In this paper, a measure is proposed that, based on the trajectories of moving objects, computes the speed limit rate in each of the cells in which a region is segmented (the space where the objects move). The time is also segmented into intervals. In this way, the behavior of moving objects can be analyzed with regard to their speed in a cell for a given time interval. An implementation of the corresponding algorithm for this measure and several experiments were conducted with the trajectories of taxis in Porto (Portugal). The results showed that the speed limit rate measure can be helpful for detecting patterns of movement, e.g., in a day (morning hours vs. night hours) or on different days of the week (weekdays vs. weekends). This measure might also serve as a rough estimate for congestion in a (sub)region. This may be useful for traffic analysis, including traffic prediction