Browsing by Subject "Object oriented programming"

Now showing 1 - 6 of 6

Open Access
An animation system for fracturing of rigid objects
(Springer, Berlin, Heidelberg, 2005) Küçükyilmaz, Ayşe; Özgüç, Bülent
This paper describes a system for the animation of fracturing brittle objects. The system combines rigid body simulation methods with a constraint-based model to animate fracturing of arbitrary polyhedral shaped objects under impact. The objects are represented as sets of masses, where pairs of adjacent masses are connected via a distance-preserving linear constraint. Lagrange multipliers are used to compute the forces exerted by those constraints, where these forces determine how and where the object will break. However, a problem with existing systems is that the initial body models exhibit well-defined uniformity, which makes the generated animations unrealistic. This work introduces a method for generating more realistic cracks without any performance loss. This method is easy to implement and applicable on different models. © Springer-Verlag Berlin Heidelberg 2005.
Open Access
Incremental materialization of object-oriented views
(Elsevier, 1999) Alhajj, R.; Elnagar, A.
We present an approach to handle incremental materialization of object-oriented views. Queries that define views are implemented as methods that are invoked to compute corresponding views. To avoid computation from scratch each time a view is accessed, we introduce some deferred update algorithms that reflect for a view only related modifications introduced into the database while that view was inactive. A view is updated by considering modifications performed within all classes along the inheritance and class-composition subhierarchies rooted at every class used in deriving that view. To each class, we add a modification list to keep one modification tuple per view dependent on that class. Such a tuple acts as a reference point that marks the start of the next update to the corresponding view. © 1999 Elsevier Science B.V. All rights reserved.
Open Access
An object oriented intelligent tutoring system for teaching set theory
(1991) Cankat, Emel
In this thesis an Intelligent Tutoring System (ITS) to teach set theory is designed and implemented using an object-oriented approach. The program is implemented on an IBM PS/2 and PC compatibles using the Turbo Pascal 5.5 programming language. The implemented system is an ITS that employs the features of set theory such as hierarchical structure, inheritably deductable operation and relations and set concept being the core of the theory to create a tutor that teaches the concept and monitors the user's state of knowledge. The system uses a distributed control strategy that allows four factors, namely student, teacher, student model and nondeterminism to possess the right to direct a session and its contents. Nondeterminism is used to generate the instructional content by randomly selecting different questions and examples each time the progi'am is invoked. Finally, the system ends the tutorial session by giving a final examination to the user and monitoring any misconceived issues in order to repeat the related sections.
Open Access
Object-oriented query language facilitating construction of new objects
(Elsevier, 1993) Alhajj, R.; Arkun, M. E.
In object-oriented database systems, messages can be used to manipulate the database; however, a query language is still a required component of any kind of database system. In the paper, we describe a query language for object-oriented databases where both objects as well as behaviour defined in them are handled. Not only existing objects are manipulated; the introduction of new relationships and new objects constructed out of existing ones is also facilitated. The operations supported in the described query language subsumes those of the relational algebra aiming at a more powerful query language than the relational algebra. Among the additional operators, there is an operator that handles the application of an aggregate function on objects in an operand while still having the result possessing the characteristics of an operand. The result of a query as well as the operands are considered to have a pair of sets, a set of objects and a set of message expressions; where a message expression is a sequence of messages. A message expression handles both stored and derived values and hence provides a full computational power without having an embedded query language with impedance mismatch. Therefore the closure property is maintained by having the result of a query possessing the characteristics of an operand. Furthermore, we define a set of objects and derive a set of message expressions for every class; hence any class can be an operand. Moreover, the result of a query has the characteristics of a class and its superclass/subclass relationships with the operands are established to make it persistent. © 1993.
Open Access
Query model for object-oriented databases
(IEEE, 1993-04) Alhajj, Reda; Arkun, M. Erol
A query language should be a part of any database system. While the relational model has a well defined underlying query model, the object-oriented database systems have been criticized for not having such a query model. One of the most challenging steps in the development of a theory for object-oriented databases is the definition of an object algebra. A formal object-oriented query model is described here in terms of an object algebra, at least as powerful as the relational algebra, by extending the latter in a consistent manner. Both the structure and the behavior of objects are handled. An operand and the output from a query in the object algebra are defined to have a pair of sets, a set of objects and a set of message expressions where a message expression is a valid sequence of messages. Hence the closure property is maintained in a natural way. In addition, it is proved that the output from a query has the characteristics of a class; hence the inheritance (sub/superclass) relationship between the operand(s) and the output from a query is derived. This way, the result of a query can be persistently placed in its proper place in the lattice.
Open Access
Reusability and schema evolution in object - oriented query models
(ASME, New York, NY, United States, 1996) Polat, F.; Alhajj, R.
In this paper, we have benefited from having an object algebra maintaining closure that makes it possible to have the output from a query persistent in the hierarchy. Based on this, it is possible to maximize reusability in object-oriented databases. Furthermore, we show how the object algebra is utilized to handle basic schema evolution functions without requiring any special set of built-in functions to serve the purpose. The invariants and the conflict resolving rules are specified. It is also shown how other schema functions are derivable from the basic ones.