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Error Correction And Decodability, Stavros Konstantinidis
Error Correction And Decodability, Stavros Konstantinidis
Digitized Theses
The classical theory of error correcting codes investigates methods for correcting substitution errors in information messages and uses mainly block codes, that is, codes all the words of which have the same length. This thesis introduces a general framework for studying the notions of error correction and decodability for arbitrary channels and for variable length codes.;First, a general definition of channel is given and a large class of channels, the SID channels, is defined for modeling substitutions, insertions, and deletions of symbols in information messages. The algebraic properties of SID channels are investigated which lead to the notion of normal …
Algorithmic Abstraction Via Polymorphism In Object-Oriented Programming Languages, Qingyu Zhuang
Algorithmic Abstraction Via Polymorphism In Object-Oriented Programming Languages, Qingyu Zhuang
Digitized Theses
The abstraction gap between algorithms and functions (procedures) causes numerous duplicate efforts in implementing the same algorithms as well as apparent under-use of many efficient algorithms. A solution to this problem is to realize algorithmic abstraction at the programming language level in addition to data abstraction. For this purpose, a programming language needs to have (1) an adequate type hierarchy for defining the domains of algorithms and (2) proper constructs for writing the sequences of steps of algorithms that are polymorphic to all types of objects in an algorithm domain.;Many object-oriented programming languages use a two-level hierarchy of entities (objects …
Minimal Forward Checking--A Lazy Constraint Satisfaction Search Algorithm: Experimental And Theoretical Results, Michael James Dent
Minimal Forward Checking--A Lazy Constraint Satisfaction Search Algorithm: Experimental And Theoretical Results, Michael James Dent
Digitized Theses
Many problems that occur in Artificial Intelligence and Operations Research can be naturally represented as Constraint Satisfaction Problems (CSPs). One of the most popular backtracking search algorithms used to solve CSPs is called Forward Checking (FC). FC performs a limited amount of lookahead during its search attempting to detect future inconsistencies thereby avoiding inconsistent parts of the search tree. In this thesis we describe a new backtracking search algorithm called Minimal Forward Checking (MFC) which maintains FC's ability to detect inconsistencies but which is lazy in is method of doing so. We prove that MFC is sound and complete. We …
3d Computer Modeling Of Human Mandible Motion With Application To Human Facial Motion, Yuan Wang
3d Computer Modeling Of Human Mandible Motion With Application To Human Facial Motion, Yuan Wang
Digitized Theses
Computer facial modeling and animation has been an interest of computer graphics researchers for many years. This is not only because the face itself is an interesting object, but also because facial animation finds application in many other disciplines (for example, entertainment, medical education, telecommunication, psychology, medicine, and linguistics). Because the mandible motion plays a major role in modeling facial motion, its study is of significance to each of those disciplines as well. In addition, the mandible itself is an object of study in the area of clinical science.;Current facial movement models in computer animation have difficulty dealing with facial …
Synchronization Expressions In Parallel Programming Languages, Lifu Guo
Synchronization Expressions In Parallel Programming Languages, Lifu Guo
Digitized Theses
In this thesis, we first review current trends in the areas related to parallel programming languages. By reviewing data-parallel and control-parallel paradigms, parallelizing compilers and parallel programming languages, we demonstrate the necessity of developing high-level parallel programming languages.;Synchronization is an essential part of parallel processing. However, many synchronization mechanisms currently used in parallel programming languages are at too low a level to be compatible with the other constructs of high-level languages. We propose and develop new constructs for synchronization termed "synchronization expressions". These new constructs relieve programmers of the burden of imposing synchronization, requiring them only to specify the necessary …
A Logic For Object-Oriented Databases, Machmudin Junus
A Logic For Object-Oriented Databases, Machmudin Junus
Digitized Theses
When E. F. Codd {dollar}\lbrack{dollar}Codd70{dollar}\rbrack{dollar} designed relational databases, he made use of mathematical logic concerning Predicate Calculus. However, when object-oriented databases were designed, there was no such support from any established mathematical logic.;In this thesis, we present a logic suitable for reasoning about object-oriented database systems. This logic is the result of the modification of F-logic {dollar}\lbrack{dollar}KifLa89, KifLaWu90{dollar}\rbrack.{dollar} The main difference between our proposed logic and F-logic, is the way our logic treats class objects and instance objects.;Our designed logic has the ability to represent: object identities, attributes, methods, classes, class hierarchies and inheritance. Similar to F-logic, the designed logic …
A Programming Model For Optimism, Crispin Cowan
A Programming Model For Optimism, Crispin Cowan
Digitized Theses
Technological advances are increasing the throughput of most aspects of computing systems. However, latency is being held back by the speed of light, particularly in distributed systems. Optimistic algorithms that "guess" the results of operations and proceed in parallel with confirmation of the guess are an effective way to hide the latency of slow operations with predictable outcomes. Optimism is used in concurrency control and distributed simulation systems, but is not generally used. Optimistic algorithms are difficult to write because of the necessity for checkpointing, rollback, and dependency tracking. This thesis presents a set of primitives called HOPE that simplifies …
Commercial Integrity, Roles And Object-Orientation, Matunda Nyanchama
Commercial Integrity, Roles And Object-Orientation, Matunda Nyanchama
Digitized Theses
This thesis presents a study of realizing commercial security, as defined in the Clark and Wilson Model (CW87), using Object-Oriented (O-O) concepts.;Role-based security is implied in the Clark and Wilson model in which specified operations are grouped to compose roles. This approach to protection is suitable for applications involving large numbers of users with overlapping user requirements and/or where there is a large number of objects. It presents a flexible (hence adaptive) means for enforcing differing ranges of security policies. It enforces the principle of least privilege, hence minimizing the risk of Trojan horse attacks.;Consequently, in part, this work focuses …
Syntax-Directed Interpretation Of Visual Languages, Shane Denis Dunne
Syntax-Directed Interpretation Of Visual Languages, Shane Denis Dunne
Digitized Theses
Recent trends suggest that it will soon be practical to implement graphical user interfaces wherein a large part of the communication between human and computer will take the form of structured graphics, i.e., diagrams, notations, etc., which have come to be called "visual languages" in the literature. This thesis argues that implementation of such interfaces will be greatly facilitated by the development and use of syntax-directed translation methods for visual languages, and the embodiment of such methods in automated tools for application development, as has been done for compilers. An algebraic formalism to express syntax and semantics for visual languages …
Pattern Recognition In The Structure Of Strings Of Characters Using Multivariate Statistical Analysis, Muhammad Syamsun
Pattern Recognition In The Structure Of Strings Of Characters Using Multivariate Statistical Analysis, Muhammad Syamsun
Digitized Theses
Pattern recognition approach is used in this research as an alternative to univariate and rule-based systems for recovering source text encrypted in monoalphabetic and polyalphabetic substitution ciphers. The approach uses a multivariate statistical technique called discriminant analysis to classify encrypted characters as source text symbols. It requires the generation of invariant measurement vectors for all groups of characters from the source and the encrypted text to classify and to identify characters. The measurement vectors consist of the values of variables generated from one-graph and digraph structures of the text.;The research suggests that quadratic discriminant analysis, which requires more time and …
Mobile Robot Perception In Unknown And Unstructured Dynamic Voxel Environments, Yuefeng Zhang
Mobile Robot Perception In Unknown And Unstructured Dynamic Voxel Environments, Yuefeng Zhang
Digitized Theses
The Occupancy Grid Method is a probabilistic spatial modelling technique. In this method, the space to be navigated is subdivided into a grid of cells. Associated with each cell is a probability that indicates the likelihood that that cell is occupied. This method was developed for handling a world where the robot was the only moving object. Thus, it lacks the ability to predict the location of moving objects over time.;In my thesis, an Extended Occupancy Grid Method is presented. The extension handles objects moving at constant velocity. In this method, a four-dimensional location-velocity space is subdivided into cells. Each …
Line Clipping, Line Drawing And Their Amalgamation, Khun Yee Fung
Line Clipping, Line Drawing And Their Amalgamation, Khun Yee Fung
Digitized Theses
Line clipping and drawing are two important processes in the graphics output pipeline. Improving the efficiency of these two processes will improve the overall efficiency of the output pipeline. My thesis is that the efficiency of these two processes can be improved significantly.;Traditionally, line clipping is done in floating point numbers and line drawing in integers. A line is first clipped, probably more than once, and then rasterized. Since line segments must be rasterized at the end, doing clipping and rasterization together improves the overall efficiency, avoids computation in floating point numbers, and eliminates inconsistencies introduced in the line clipping …
Representation And Visualization Of Volume Data, Harvey H. Atkinson
Representation And Visualization Of Volume Data, Harvey H. Atkinson
Digitized Theses
This thesis focuses on the representation and visualization of volume data. The principal datasets used in experimentation were geometrically defined solids, as well as three dimensional arrays of density values obtained from Computed Tomography. Solid structures were, in general, encoded and stored as linear octrees.;An original interpolation method was designed based on the Fourier representation of a three-dimensional array. This method was compared to the most commonly used techniques of linear and tri-linear interpolation. Evaluation of the interpolator was performed by increasing the resolution of three-dimensional arrays of densities that were obtained from Computed Tomography. Bone and soft tissues were …
The Kbo Model: Towards A Unified View Of Data, Behaviors, And Messages In Object-Oriented Database Systems, Li Yu
Digitized Theses
One of the most distinguished features of object-oriented databases (OODBs) is their support for users to populate both data and arbitrary behaviors in the same database. Consequently, the increasingly large population of arbitrary behaviors in OODBs demands a database approach to their management and manipulation. Current OODB models offer no capability of managing arbitrary behaviors as meaningful database objects, and thus fail to meet such a demand.;The goal of this research is to unify data, behaviors, and messages into a uniform notion of objects so that a single database approach can be developed to manage and manipulate such objects. The …
Codes Andn-Ary Relations, Shyr-Shen Yu
Codes Andn-Ary Relations, Shyr-Shen Yu
Digitized Theses
The aim of this thesis is to develop a general mechanism for the construction of codes and to extract general properties of classes of codes. This mechanism makes it unnecessary to study various classes of codes separately--at least to some extent--by different constructions and properties.;To achieve this goal, the mechanism of characterizing classes of languages by binary relations is studied. Some general properties related to binary relations and languages are obtained. Moreover, three new classes of codes, n-shuffle codes, solid codes, and intercodes are constructed. Solid codes and intercodes have the synchronous decoding property which is very useful in the …
Foundations Of Logic Programming With Equality, Kwok Hung Chan
Foundations Of Logic Programming With Equality, Kwok Hung Chan
Digitized Theses
An obstacle to practical logic programming systems with equality is infinite computation. In the dissertation we study three strategies for eliminating infinite searches in Horn clause logic programming systems and develop an extension of Prolog that has the symmetry, transitivity and predicate substitutivity of equality built-in. The three strategies are: (1) Replacing logic programs with infinite search trees by equivalent logic programs with finite search trees; (2) Building into the inference machine the axioms that cause infinite search trees; (3) Detecting and failing searches of infinite branches.;The dissertation consists of two parts. General theories of the three strategies identified above …
Insyps: A Computer-Aided Process Analysis And Design System, Rashpal Singh Ahluwalia
Insyps: A Computer-Aided Process Analysis And Design System, Rashpal Singh Ahluwalia
Digitized Theses
No abstract provided.