Computer Science

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Application of artificial intelligence for detecting derived viruses.
(2017) Asiru, Omotayo Fausat.; Blackledge, Jonathan Michael.; Dlamini, Moses Thandokuhle.
A lot of new viruses are being created each and every day. However, some of these viruses are not completely new per se. Most of the supposedly ‘new’ viruses are not necessarily created from scratch with completely new (something novel that has never been seen before) mechanisms. For example, some of these viruses just change their forms and come up with new signatures to avoid detection. Hence, such viruses cannot be argued to be new. This research refers to such as derived viruses. Just like new viruses, we argue that derived viruses are hard to detect with current scanning-detection methods. Many virus detection methods exist in the literature, but very few address the detection of derived viruses. Hence, the ultimate research question that this study aims to answer is; how might we improve the detection rate of derived computer viruses? The proposed system integrates a mutation engine together with a neural network to detect derived viruses. Derived viruses come from existing viruses that change their forms. They do so by adding some irrelevant instructions that will not alter the intended purpose of the virus. A mutation engine is used to group existing virus signatures based on their similarities. The engine then creates derivatives of groups of signatures. This is done up until the third generation (of mutations). The existing virus signatures and the created derivatives are both used to train the neural network. The derived signatures that are not used for the training are used to determine the effectiveness of the neural network. Ten experiments were conducted on each of the three derived virus generations. The first generation showed the highest derived virus detection rate compared to the other two generations. The second generation also showed a slightly higher detection rate than the third generation which has the least detection rate. Experimental results show that the proposed model can detect derived viruses with an average accuracy detection rate of 80% (This includes a 91% success rate on first generation, 83% success rate on second generation and 65% success rate on third generation). The results further show that the correlation between the original virus signature and its derivatives decreases with the generations. This means that after many generations of a virus changing form, its variants will no longer look like the original. Instead the variants look like a completely new virus even though the variants and the original virus will always have the same behaviour and operational characteristics with similar effects.
Artificial neural networks for image recognition : a study of feature extraction methods and an implementation for handwritten character recognition.
(1996) Moodley, Deshendran.; Ram, Vevek.; Haines, Linda Margaret.
The use of computers for digital image recognition has become quite widespread. Applications include face recognition, handwriting interpretation and fmgerprint analysis. A feature vector whose dimension is much lower than the original image data is used to represent the image. This removes redundancy from the data and drastically cuts the computational cost of the classification stage. The most important criterion for the extracted features is that they must retain as much of the discriminatory information present in the original data. Feature extraction methods which have been used with neural networks are moment invariants, Zernike moments, Fourier descriptors, Gabor filters and wavelets. These together with the Neocognitron which incorporates feature extraction within a neural network architecture are described and two methods, Zernike moments and the Neocognitron are chosen to illustrate the role of feature extraction in image recognition.
Formalisms for agents reasoning with stochastic actions and perceptions.
(2014) Rens, Gavin Brian.; Meyer, Thomas Andreas.; Lakemeyer, Gerhard.
The thesis reports on the development of a sequence of logics (formal languages based on mathematical logic) to deal with a class of uncertainty that agents may encounter. More accurately, the logics are meant to be used for allowing robots or software agents to reason about the uncertainty they have about the effects of their actions and the noisiness of their observations. The approach is to take the well-established formalism called the partially observable Markov decision process (POMDP) as an underlying formalism and then design a modal logic based on POMDP theory to allow an agent to reason with a knowledge-base (including knowledge about the uncertainties). First, three logics are designed, each one adding one or more important features for reasoning in the class of domains of interest (i.e., domains where stochastic action and sensing are considered). The final logic, called the Stochastic Decision Logic (SDL) combines the three logics into a coherent formalism, adding three important notions for reasoning about stochastic decision-theoretic domains: (i) representation of and reasoning about degrees of belief in a statement, given stochastic knowledge, (ii) representation of and reasoning about the expected future rewards of a sequence of actions and (iii) the progression or update of an agent’s epistemic, stochastic knowledge. For all the logics developed in this thesis, entailment is defined, that is, whether a sentence logically follows from a knowledge-base. Decision procedures for determining entailment are developed, and they are all proved sound, complete and terminating. The decision procedures all employ tableau calculi to deal with the traditional logical aspects, and systems of equations and inequalities to deal with the probabilistic aspects. Besides promoting the compact representation of POMDP models, and the power that logic brings to the automation of reasoning, the Stochastic Decision Logic is novel and significant in that it allows the agent to determine whether or not a set of sentences is entailed by an arbitrarily precise specification of a POMDP model, where this is not possible with standard POMDPs. The research conducted for this thesis has resulted in several publications and has been presented at several workshops, symposia and conferences.
An investigation into the use of genetic programming for the induction of novice procedural programming solution algorithms in intelligent programming tutors.
(2004) Pillay, Nelishia.; Sartori-Angus, Alan G.
Intelligent programming tutors have proven to be an economically viable and effective means of assisting novice programmers overcome learning difficulties. However, the large-scale use of intelligent programming tutors has been impeded by the high developmental costs associated with building intelligent programming tutors. The research presented in this thesis forms part of a larger initiative aimed at reducing these costs by building a generic architecture for the development of intelligent programming tutors. One of the facilities that must be provided by the generic architecture is the automatic generation of solutions to programming problems. The study presented in the thesis examines the use of genetic programming as means of inducing solution algorithms to novice programming problems. The scope of the thesis is limited to novice procedural programming paradigm problems requiring the use of arithmetic, string manipulation, conditional, iterative and recursive programming structures. The methodology employed in the study is proof-by-demonstration. A genetic programming system for the induction of novice procedural solution algorithms was implemented and tested on randomly chosen novice procedural programming problems. The study has identified the standard and advanced genetic programming features needed for the successful generation of novice procedural solution algorithms. The outcomes of this study include the derivation of an internal representation language for representing procedural solution algorithms and a high-level programming problem specification format for describing procedural problems, in the generic architecture. One of the limitations of genetic programming is its susceptibility to converge prematurely to local optima and not find a solution in some cases. The study has identified fitness function biases against certain structural components that are needed to find a solution, as an additional cause of premature convergence in this domain. It presents an iterative structure-based algorithm as a solution to this problem. This thesis has contributed to both the fields of genetic programming and intelligent programming tutors. While genetic programming has been successfully implemented in various domains, it is usually applied to a single problem within that domain. In this study the genetic programming system must be capable of solving a number of different programming problems in different application domains. In addition to this, the study has also identified a means of overcoming premature convergence caused by fitness function biases in a genetic programming system for the induction of novice procedural programming algorithms. Furthermore, although a number of studies have addressed the student modelling and pedagogical aspects of intelligent programming tutors, none have examined the automatic generation of problem solutions as a means of reducing developmental costs. Finally, this study has contributed to the ongoing research being conducted by the artificial intelligence in education community, to test the effectiveness of using machine learning techniques in the development of different aspects of intelligent tutoring systems.

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Browsing Computer Science by Subject "Artificial intelligence."