Physical Sciences and Mathematics Commons^™

A Survey On Detection And Defense Of Application Layer Ddos Attacks, Naga Shalini Vadlamani

UNLV Theses, Dissertations, Professional Papers, and Capstones

As the time is passing on, the effect of DDoS attacks on Internet security is growing tremendously. Within a very little span there is a huge increase in the size and frequency of DDoS attacks. With the new technologies and new techniques, the attackers are finding more sophisticated ways to attack the servers. In this situation, it is necessary to come up with various mechanisms to detect and defend these DDoS attacks and protect the servers from the attackers. Many researches have been carried out to detect the DDoS attack traffic in transport layer, which is more vulnerable to DDoS …

Object Detection Using Contrast Enhancement And Dynamic Noise Reduction, Justin Lee Baker

UNLV Theses, Dissertations, Professional Papers, and Capstones

Edge detection is one of the most important steps a computer must perform to gain understanding of an object in a digital image either from disk or from video feed. Edge detection allows for the computer to describe the shape of the objects in an image and create a pixel boundary defining what is considered part of an object, and what is not. Cannys edge detection algorithm is one of the most robust and accurate of these edge detection algorithms. However, as with many algorithms in image processing, there are many cases where the algorithm does not perform as well …

The Effects Of Self-Explanation And Reading Questions And Answers On Learning Computer Programming Language, Nancy Lee

UNLV Theses, Dissertations, Professional Papers, and Capstones

The current study explored the differential effects of two learning strategies, self-explanation and reading questions and answers, on students' test performance in the computer programming language JavaScript. Students' perceptions toward the two strategies as to their effectiveness in learning JavaScript was also explored by examining students' preferred strategy and the reasons for their choice. An online interactive tutorial instruction that implemented worked-examples and multimedia learning principles was developed for this study. A total of 147 high school students (ages ranging from 14 to 17) who were taking a Computer Introduction course participated in this study. The course was offered in …

Nonlinear Adaptive Diffusion Models For Image Denoising, Ajay Kumar Mandava

UNLV Theses, Dissertations, Professional Papers, and Capstones

Most of digital image applications demand on high image quality. Unfortunately, images often are degraded by noise during the formation, transmission, and recording processes. Hence, image denoising is an essential processing step preceding visual and automated analyses. Image denoising methods can reduce image contrast, create block or ring artifacts in the process of denoising. In this dissertation, we develop high performance non-linear diffusion based image denoising methods, capable to preserve edges and maintain high visual quality. This is attained by different approaches: First, a nonlinear diffusion is presented with robust M-estimators as diffusivity functions. Secondly, the knowledge of textons derived …

Application Of Ntru Cryptographic Algorithm For Securing Scada Communication, Amritha Puliadi Premnath

UNLV Theses, Dissertations, Professional Papers, and Capstones

Supervisory Control and Data Acquisition (SCADA) system is a control system which is widely used in Critical Infrastructure System to monitor and control industrial processes autonomously. Most of the SCADA communication protocols are vulnerable to various types of cyber-related attacks. The currently used security standards for SCADA communication specify the use of asymmetric cryptographic algorithms like RSA or ECC for securing SCADA communications. There are certain performance issues with cryptographic solutions of these specifications when applied to SCADA system with real-time constraints and hardware limitations. To overcome this issue, in this thesis we propose the use of a faster and …

Stability Aware Delaunay Refinement, Bishal Acharya

UNLV Theses, Dissertations, Professional Papers, and Capstones

Good quality meshes are extensively used for finding approximate solutions for partial differential equations for fluid flow in two dimensional surfaces. We present an overview of existing algorithms for refinement and generation of triangular meshes. We introduce the concept of node stability in the refinement of Delaunay triangulation. We present two algorithms for generating stable refinement of Delaunay triangulation. We also present an experimental investigation of a triangulation refinement algorithm based on the location of the center of gravity and the location of the center of circumcircle. The results show that the center of gravity based refinement is more effective …

Utilizing Big Data In Identification And Correction Of Ocr Errors, Shivam Agarwal

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this thesis, we report on our experiments for detection and correction of OCR errors with web data. More specifically, we utilize Google search to access the big data resources available to identify possible candidates for correction. We then use a combination of the Longest Common Subsequences (LCS) and Bayesian estimates to automatically pick the proper candidate.

Our experimental results on a small set of historical newspaper data show a recall and precision of 51% and 100%, respectively. The work in this thesis further provides a detailed classification and analysis of all errors. In particular, we point out the shortcomings …

Real Time Pattern Recognition In Digital Video With Applications To Safety In Construction Sites, Dinesh Bajracharya

UNLV Theses, Dissertations, Professional Papers, and Capstones

In construction sites, various guidelines are provided for the correct use of safety equipment. Many fatalities and injuries occur to people because of the lack of exercise of these guidelines and proper monitoring of the violations. In order to improve these standards and amend the cause, a video based monitoring tool will be created for a construction site.

Based on the real time video obtained from cameras on the site, a classification algorithm will be created which has the intelligence to recognize if any safety rules have been violated. A classification vector will be created based on the different classifiers, …

A Digital Image Processing Method For Detecting Pollution In The Atmosphere From Camera Video, Amrita Nikhil Amritphale

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this thesis we examine the use of digital cameras to detect the magnitude of atmospheric pollution present in the atmosphere. Digital cameras are inexpensive and are being used in countless areas, many of which are outdoors and very public. For example, we see digital cameras located at street intersections, city and state parks, and recreation areas. The theory presented in this paper could help agencies to monitor air quality at any of these sites. Our theory is based on certain molecules and particles that are present in clean air absorb, luminesce, refract, reflect, or scatter the red, green, and …

Communication Artifacts And Interaction Evaluation For Requirements Engineering, Miloslava Plachkinova

UNLV Theses, Dissertations, Professional Papers, and Capstones

This paper aims to answer an important question regarding the development of new information systems (IS): "What is the predominant factor for the selection of communication artifacts for requirements engineering (RE)?". Many researchers have focused on the RE and communication as separate disciplines, but little or no research addressed the RE communication issues. These problems are important because they often lead to misunderstanding and misinterpretation of the gathered requirements. We develop expectations about the RE communication process based on prior literature from both disciplines and we test them through several case studies. Our methodology consists of analysis of six case …

Real Time Digital Night Vision Using Nonlinear Contrast Enhancement, Nishikar Sapkota

UNLV Theses, Dissertations, Professional Papers, and Capstones

This thesis describes a nonlinear contrast enhancement technique to implement night vision in digital video. It is based on the global histogram equalization algorithm. First, the effectiveness of global histogram equalization is examined for images taken in low illumination environments in terms of Peak signal to noise ratio (PSNR) and visual inspection of images. Our analysis establishes the existence of an optimum intensity for which histogram equalization yields the best results in terms of output image quality in the context of night vision. Based on this observation, an incremental approach to histogram equalization is developed which gives better results than …

Simulation And Analysis Of Insider Attacks, Christopher Blake Clark

UNLV Theses, Dissertations, Professional Papers, and Capstones

An insider is an individual (usually an employee, contractor, or business partner) that has been trusted with access to an organization's systems and sensitive data for legitimate purposes. A malicious insider abuses this access in a way that negatively impacts the company, such as exposing, modifying, or defacing software and data.

Many algorithms, strategies, and analyses have been developed with the intent of detecting and/or preventing insider attacks. In an academic setting, these tools and approaches show great promise. To be sure of their effectiveness, however, these analyses need to be tested. While real data is available on insider attacks …

The Distributed Application Debugger, Michael Quinn Jones

UNLV Theses, Dissertations, Professional Papers, and Capstones

Developing parallel programs which run on distributed computer clusters introduces additional challenges to those present in traditional sequential programs. Debugging parallel programs requires not only inspecting the sequential code executing on each node but also tracking the flow of messages being passed between them in order to infer where the source of a bug actually lies.

This thesis focuses on a debugging too called The Distributed Application Debugger which targets a popular distributed C programming library called MPI (Message Passing Interface). The tool is composed of multiple components which run together seamlessly to provide its users an effective way to …

Simulated Annealing Approach To Flow Shop Scheduling, Sadhana Yellanki

UNLV Theses, Dissertations, Professional Papers, and Capstones

Flow Shop Scheduling refers to the process of allotting various jobs to the machines given, such that every job starts to process on a machine n only after it has finished processing on machine n-1, with each job having n operations to be performed one per machine. To find a schedule that leads to the optimal utilization of resources, expects the schedule to finish in a minimum span of time, and also satisfy the optimality criterion set for the related scheduling problem is NP-Hard, if n > 2. In this thesis, we have developed an algorithm adopting a heuristic called Simulated …

Scheduling Jobs On Two Uniform Parallel Machines To Minimize The Makespan, Sandhya Kodimala

UNLV Theses, Dissertations, Professional Papers, and Capstones

The problem of scheduling n independent jobs on m uniform parallel machines such that the total completion time is minimized is a NP-Hard problem. We propose several heuristic-based online algorithms for machines with different speeds called Q₂||C_max. To show the efficiency of the proposed online algorithms, we compute the optimal solution for Q₂||C_max using pseudo-polynomial algorithms based on dynamic programming method. The pseudo-polynomial algorithm has time complexity O (n T²) and can be run on reasonable time for small number of jobs and small processing times. This optimal offline algorithm is …

An Online Algorithm For The 2-Server Problem On The Line With Improved Competitiveness, Lucas Adam Bang

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this thesis we present a randomized online algorithm for the 2-server problem on the line, named R-LINE (for Randomized Line). This algorithm achieves the lowest competitive ratio of any known randomized algorithm for the 2-server problem on the line.

The competitiveness of R-LINE is less than 1.901. This result provides a significant improvement over the previous known competitiveness of 155/78 (approximately 1.987), by Bartal, Chrobak, and Larmore, which was the first randomized algorithm for the 2-server problem one the line with competitiveness less than 2. Taking inspiration from this algorithm,we improve this result by utilizing ideas from T-theory, game …