5,635 research outputs found
A Web-Based Tool to Enhance Teaching/Learning Database Normalization
It has been difficult to motivate students to learn database normalization because students think the subject dry and theoretical. A web-based tool is developed to give students an interactive hands-on experience in database normalization process. The tool is suitable for relational data modeling in systems analysis and design and data management courses. This paper describes the web-based tool and its effectiveness in teaching relational data model. The effectiveness of the tool has been evaluated in surveys. The paper shows that the tool has a positive impact on students’ perception
Ensuring the existence of a BCNF-decomposition that preserves functional dependencies in O (N2) time
A simple condition is presented that ensures that a relation scheme R with a set F of functional dependencies has a Boyce-Codd normal form (BCNF)-decomposition that has the lossless-join property and preserves functional dependencies
Normalizing Database Normalization Definitions In AIS Text Books
Due to the abstract nature of the definitions for normal forms, over the years the interpretations of the definitions published in the textbooks, both MIS and AIS disciplines, have been differentiated and even deviated from its original form. The concept of deviation from the original form is a phenomenon that linguists call “semantic drift.” The most noticeable deviations are on first and second normal forms (i.e., 1NF and 2NF). Their definitions range from “atomic attribute” to “removing repeating group” for 1NF and from “functional dependency” to “removing partial dependency” in addition to being 1NF for 2NF. The purpose of this paper is to compare definitions of first, second, and third normal forms from the textbooks with those of the earlier forms and to identify shortfalls if there are any
Online Data Modeling Tool to Improve Students\u27 Learning of Conceptual Data Modeling
Computer based instruction (CBI) has been used in science, mathematics, and engineering education, and showed positive outcomes. CBI is generally most effective when used as a supplement to traditional teaching. In this research-in-progress paper, the author presents an online data modeling tool as the supplement to data modeling teaching and proposes a research plan to measure students’ perceived effectiveness of the online tool
A Generative Model of Natural Texture Surrogates
Natural images can be viewed as patchworks of different textures, where the
local image statistics is roughly stationary within a small neighborhood but
otherwise varies from region to region. In order to model this variability, we
first applied the parametric texture algorithm of Portilla and Simoncelli to
image patches of 64X64 pixels in a large database of natural images such that
each image patch is then described by 655 texture parameters which specify
certain statistics, such as variances and covariances of wavelet coefficients
or coefficient magnitudes within that patch.
To model the statistics of these texture parameters, we then developed
suitable nonlinear transformations of the parameters that allowed us to fit
their joint statistics with a multivariate Gaussian distribution. We find that
the first 200 principal components contain more than 99% of the variance and
are sufficient to generate textures that are perceptually extremely close to
those generated with all 655 components. We demonstrate the usefulness of the
model in several ways: (1) We sample ensembles of texture patches that can be
directly compared to samples of patches from the natural image database and can
to a high degree reproduce their perceptual appearance. (2) We further
developed an image compression algorithm which generates surprisingly accurate
images at bit rates as low as 0.14 bits/pixel. Finally, (3) We demonstrate how
our approach can be used for an efficient and objective evaluation of samples
generated with probabilistic models of natural images.Comment: 34 pages, 9 figure
- …