Engineering Commons^™

Graphene On Pt(111): Growth And Substrate Interaction, Peter Sutter, Jerzy T. Sadowski, Eli Sutter

Department of Electrical and Computer Engineering: Faculty Publications

In situ low-energy electron microscopy (LEEM) of graphene growth combined with measurements of the graphene structure and electronic band structure has been used to study graphene on Pt (111). Growth by carbon segregation produces macroscopic monolayer graphene domains extending continuously across Pt (111) substrate steps and bounded by strongly faceted edges. LEEM during cooling from the growth temperature shows the propagation of wrinkles in the graphene sheet, driven by thermal stress. The lattice mismatch between graphene and Pt (111) is accommodated by moiré structures with a large number of different rotational variants, without a clear preference for a particular interface …

Quality-Driven Cross Layer Design For Multimedia Security Over Resource Constrained Wireless Sensor Networks, Wei Wang

Department of Computer Electronics and Engineering: Dissertations, Theses, and Student Research

The strong need for security guarantee, e.g., integrity and authenticity, as well as privacy and confidentiality in wireless multimedia services has driven the development of an emerging research area in low cost Wireless Multimedia Sensor Networks (WMSNs). Unfortunately, those conventional encryption and authentication techniques cannot be applied directly to WMSNs due to inborn challenges such as extremely limited energy, computing and bandwidth resources. This dissertation provides a quality-driven security design and resource allocation framework for WMSNs. The contribution of this dissertation bridges the inter-disciplinary research gap between high layer multimedia signal processing and low layer computer networking. It formulates the …

Biological Sequence Simulation For Testing Complex Evolutionary Hypotheses: Indel-Seq-Gen Version 2.0, Cory L. Strope

School of Computing: Dissertations, Theses, and Student Research

Reconstructing the evolutionary history of biological sequences will provide a better understanding of mechanisms of sequence divergence and functional evolution. Long-term sequence evolution includes not only substitutions of residues but also more dynamic changes such as insertion, deletion, and long-range rearrangements. Such dynamic changes make reconstructing sequence evolution history difficult and affect the accuracy of molecular evolutionary methods, such as multiple sequence alignments (MSAs) and phylogenetic methods. In order to test the accuracy of these methods, benchmark datasets are required. However, currently available benchmark datasets have limitations in their sizes and evolutionary histories of the included sequences are unknown. These …

Optimal Sensor Placement In Environmental Research: Designing A Sensor Network Under Uncertainty, Aline James, Craig Tweedie, Tanja Magoc, Vladik Kreinovich, Martine Ceberio

Departmental Technical Reports (CS)

One of our main challenges in meteorology and environment research is that in many important remote areas, sensor coverage is sparse, leaving us with numerous blind spots. Placement and maintenance of sensors in these areas are expensive. It is therefore desirable to find out how, within a given budget, we can design a sensor network are important activities was developing reasonable techniques for sensor that would provide us with the largest amount of useful information while minimizing the size of the "blind spot" areas which is not covered by the sensors.

This problem is very difficult even to formulate in …

Symmetries: A General Approach To Integrated Uncertainty Management, Vladik Kreinovich, Hung T. Nguyen, Songsak Sriboonchitta

Departmental Technical Reports (CS)

We propose to use symmetries as a general approach to maintaining different types of uncertainty, and we show how the symmetry approach can help, especially in in economics-related applications.

Discrete Taylor Series As A Simple Way To Predict Properties Of Chemical Substances Like Benzenes And Cubanes, Jaime Nava, Vladik Kreinovich, Guillermo Restrepo, Douglas J. Klein

Departmental Technical Reports (CS)

In many applications, we have numerous molecules that are obtained from a "template" molecule like benzene C6H6 or cubane C8H8 by replacing some of its hydrogen atoms with other atoms or atom groups (called ligands). Depending on how many original atoms are replaced and which ones are replaced, we obtain a large number of different chemical substances. It is desirable to be able, based on the measurements performed on a small number of such substances, to accurately predict the characteristics (such as energy) of all similar substances.

Such predictions are very important, since, e.g. cubanes, while kinetically stable, are highly …

An Efficient Time-Bound Hierarchical Key Assignment Scheme With A New Merge Function: A Performance Study, Rajasree Shyam

Computer Science Graduate Projects and Theses

The advent of digital age has resulted in more television consumers switching to Digital TV with considerable improvement in image quality and ease-of-use. Consumers are able to select and view television programs and channels of choice by using a pay-per-use model or streaming video from their computer terminals. In all these use cases, the media provider requires a means by which they can restrict the consumers from watching selected programs for a pre-approved temporal interval. The consumer needs to be prevented access to certain pay-per-use channels and programs upon expiry of this pre-approved access. This necessitates the media provider to …

Towards Optimal Effort Distribution In Process Design Under Uncertainty, With Application To Education, Olga Kosheleva, Vladik Kreinovich

Departmental Technical Reports (CS)

In most application areas, we need to take care of several (reasonably independent) participants. For example, in controlling economics, we must make sure that all the economic regions prosper. In controlling environment, we want to guarantee that all the geographic regions have healthy environment. In education, we want to make sure that all the students learn all the needed knowledge and skills.

In real life, the amount of resources is limited, so we face the problem of "optimally" distributing these resources between different objects.

What is a reasonable way to formalize "optimally"? For each of the participants, preferences can be …

Checking Design Constraints At Run-Time Using Ocl And Aspectj, Yoonsik Cheon, Carmen Avila, Steve Roach, Cuauhtemoc Munoz

Departmental Technical Reports (CS)

Design decisions and constraints of a software system can be specified precisely using a formal notation such as the Object Constraint Language (OCL). However, they are not executable, and assuring the conformance of an implementation to its design is hard. The inability of expressing design constraints in an implementation and checking them at runtime invites, among others, the problem of design drift and corrosion. We propose runtime checks as a solution to mitigate this problem. The key idea of our approach is to translate design constraints written in a formal notation such as OCL into aspects that, when applied to …

Fuzzy Transforms Of Higher Order Approximate Derivatives: A Theorem, Irina Perfilieva, Vladik Kreinovich

Departmental Technical Reports (CS)

In many practical applications, it is useful to represent a function f(x) by its fuzzy transform, i.e., by the "average" values over different elements of a fuzzy partition A₁(x), ..., _n(x) (for which A_i(x) >= 0 and A₁(x) + ... + A_n(x) = 1). It is known that when we increase the number n of the partition elements A_i(x), the resulting approximation get closer and closer to the original function: for each value x₀, the values F_i corresponding to the function A_i(x) for …

Session Initiation Protocol Server Implementation For Linksys Routers, Matthew Duder

Computer Science and Software Engineering

Session Initiation Protocol (SIP) is a signaling protocol used for network-based media interaction. SIP Servers are required to process and forward requests and responses between end clients. Once connection setup is complete, the end clients utilize some other protocol (such as Real-Time Transport Protocol) to complete their task.

Such a server may be implemented and installed on routers. Unlike the SIP protocol, however, router development currently remains without standards. For this project, Linux-based residential-grade routers had their kernels replaced with an open source version. This allowed for installation of open-source development, such as a SIP server implementation.

This project led …

Redesigning Src2pkg, A Linux Package Creation Toolkit, Timothy Goya

Computer Science and Software Engineering

Package managers ease installation and removal of applications. However, as the name indicates, in order for a package manager to be useful, they need packages created from upstream sources to manage. This is the purpose of src2pkg, a toolkit written in Bash shell script which automates many package creation tasks. src2pkg, however, suffers from major design flaws that cripple its ability to package some exotic upstream sources. src2pkg-ng is a prototype redesign of src2pkg that eliminates these flaws. src2pkg-ng fully supports creating packages for Slackware and Slackware-compatible variants for at least 21 upstream sources with various levels of complexity. Debian …

Tsukahara: A Comprehensive Web Solution Designed To Simplify The Process Of Hosting A Gymnastics Meet., Jonathan Thomassian

Computer Science and Software Engineering

The process of setting up a gymnastics meet is long and complicated. Most meets organized today involve large amounts of paperwork by both organizing gyms and attending gyms. Tsukahara seeks to address this issue by providing a comprehensive web based solution, to make it easy for gyms to both host and attend meets.

A Bandwidth Aware Modification To The Dsr Routing Protocol For Wireless Mesh Networks, Mustafa Ramadhan, Mark Davis

Conference papers

This work proposes a bandwidth aware cross-layer modification to the DSR routing protocol. We include the Access Efficiency Factor (AEF) parameter in addition to the hop-count in the routing discovery mechanism. AEF is a measure to the local availability of bandwidth at a node. Employing the AEF as a metric in the routing discovery mechanism attempts to avoid routing through a congested area in the network. In this modification, we impose a limit on the hop-count in order to control the delay time in the network. The path selection procedure operates by finding a path with the highest minimum AEF …

Structured P2p Technologies For Distributed Command And Control, Daniel R. Karrels, Gilbert L. Peterson, Barry E. Mullins

Faculty Publications

The utility of Peer-to-Peer (P2P) systems extends far beyond traditional file sharing. This paper provides an overview of how P2P systems are capable of providing robust command and control for Distributed Multi-Agent Systems (DMASs). Specifically, this article presents the evolution of P2P architectures to date by discussing supporting technologies and applicability of each generation of P2P systems. It provides a detailed survey of fundamental design approaches found in modern large-scale P2P systems highlighting design considerations for building and deploying scalable P2P applications. The survey includes unstructured P2P systems, content retrieval systems, communications structured P2P systems, flat structured P2P systems and …

Analysis Of Distributed Denial Of Service Attacks And Countermeasures, Sampada Karandikar

All Theses

Network technology has experienced explosive growth in the past two decades. The vast connectivity of networks all over the world poses monumental risks. The generally accepted philosophy in the security world is that no system or network is completely secure [1] which makes network security a critical concern. The work done in this thesis focuses on Distributed Denial of Service Attacks (DDoS) where legitimate users are prevented from accessing network services. Although a lot of research has been done in this field, these attacks remain one of the most common threats affecting network performance.
One defense against DDoS attacks is …

Interactive Perception For Cluttered Environments, Robert Willimon

All Theses

Robotics research tends to focus upon either non-contact sensing or machine manipulation, but not both. This paper explores the benefits of combining the two by addressing the problem of extracting and classifying unknown objects within a cluttered environment, such as found in recycling and service robot applications. In the proposed approach, a pile of objects lies on a flat background, and the goal of the robot is to sift through the pile and classify each object so that it can be studied further. One object should be removed at a time with minimal disturbance to the other objects. We propose …

Anaglym: A Graphics Engine Providing Secure Execution Of Applications, Josh Holtrop

Masters Projects

"The Anaglym graphics engine uses the Lua programming language as the high-level language in which to interpret Anaglym applications. Applications running inside Anaglym are Lua scripts that have a particular environment exposed to them. By default, when Lua is embedded inside a C or C++ host application, no Lua functions are available to the hosted script. Lua functions must be exported by the host environment to be callable by a Lua script."

Grating Lobe Reduction In Aperiodic Linear Arrays Of Physically Large Antennas, William C. Barott, Paul G. Steffes

Publications

We present performance bounds obtained from the optimization of the sidelobe levels of aperiodic linear arrays. The antennas comprising these arrays are large compared to the distance between neighboring antennas, a case not addressed in previously published work. This optimization is performed in pattern-space and is applicable over a wide range of scan angles. We show that grating lobes can be suppressed even when the elemental antennas are several wavelengths in size, provided that the ratio of the antenna size to the average spacing between the antenna center-points does not exceed 80%.

Entropy And Certainty In Lossless Data Compression, James Jay Jacobs

Dissertations

Data compression is the art of using encoding techniques to represent data symbols using less storage space compared to the original data representation. The encoding process builds a relationship between the entropy of the data and the certainty of the system. The theoretical limits of this relationship are defined by the theory of entropy in information that was proposed by Claude Shannon. Lossless data compression is uniquely tied to entropy theory as the data and the system have a static definition. The static nature of the two requires a mechanism to reduce the entropy without the ability to alter either …

Cyber Influence, William Hutchinson

Australian Information Warfare and Security Conference

This paper explores influence in the cyber-world and the ability and effectiveness of influence campaigns in this medium. It examines the possibilities of influence in the online world as examines the potential of mobile technologies in this area. The contentious link between influence and behavioural change is investigated. Counterinfluence in the context of radicalisation is also looked at. Whilst it is inevitable that the digital medium is and will be used for influence campaigns and will be influential regardless if there are concerted ‘campaigns’ or not, it effects in terms of behavioural change are still open to question.

Appraising Critical Infrastructure Systems With Visualisation, Graeme Pye, Matthew Warren

Australian Information Warfare and Security Conference

This paper explores the use of system modelling as an approach for appraising critical infrastructure systems. It reports on focus group findings with relation to the system modelling aspects of a critical infrastructure security analysis and modelling framework. Specifically, this discussion focuses on the interpretations of a focus group in terms of the likely benefits or otherwise of system visualisation. With the group focusing on its perceived value as an educational tool in terms of providing an abstract visualisation representation of a critical infrastructure system incident.

Safeguarding Australia From Cyber-Terrorism:A Proposed Cyber-Terrorism Scada Risk Framework For Industry Adoption, Christopher Beggs, Matthew Warren

Australian Information Warfare and Security Conference

Terrorist groups are currently using information and communication technologies (ICTs) to orchestrate their conventional physical attacks. More recently, terrorists have been developing a new form of capability within the cyber-arena to coordinate cyber-based attacks. This paper identifies that cyber-terrorism capabilities are an integral, imperative, yet under-researched component in establishing, and enhancing cyber-terrorism risk assessment models for SCADA systems. This paper is an extension of work previously published by Beggs and Warren 2008, it presents a high level overview of a cyber-terrorism SCADA risk framework that has been adopted and validated by SCADA industry practitioners. The paper proposes a managerial framework …

Coherent Phrase Model For Efficient Image Near-Duplicate Retrieval, Yiqun Hu, Xiangang Cheng, Liang-Tien Chia, Xing Xie, Deepu Rajan, Ah-Hwee Tan

Research Collection School Of Computing and Information Systems

This paper presents an efficient and effective solution for retrieving image near-duplicate (IND) from image database. We introduce the coherent phrase model which incorporates the coherency of local regions to reduce the quantization error of the bag-of-words (BoW) model. In this model, local regions are characterized by visual phrase of multiple descriptors instead of visual word of single descriptor. We propose two types of visual phrase to encode the coherency in feature and spatial domain, respectively. The proposed model reduces the number of false matches by using this coherency and generates sparse representations of images. Compared to other method, the …

A Neural Network Approach To Border Gateway Protocol Peer Failure Detection And Prediction, Cory B. White

Master's Theses

The size and speed of computer networks continue to expand at a rapid pace, as do the corresponding errors, failures, and faults inherent within such extensive networks. This thesis introduces a novel approach to interface Border Gateway Protocol (BGP) computer networks with neural networks to learn the precursor connectivity patterns that emerge prior to a node failure. Details of the design and construction of a framework that utilizes neural networks to learn and monitor BGP connection states as a means of detecting and predicting BGP peer node failure are presented. Moreover, this framework is used to monitor a BGP network …

A Robust Damage Assessment Model For Corrupted Database Systems, Ge Fu, Hong Zhu, Yingjiu Li

Research Collection School Of Computing and Information Systems

An intrusion tolerant database uses damage assessment techniques to detect damage propagation scales in a corrupted database system. Traditional damage assessment approaches in a intrusion tolerant database system can only locate damages which are caused by reading corrupted data. In fact, there are many other damage spreading patterns that have not been considered in traditional damage assessment model. In this paper, we systematically analyze inter-transaction dependency relationships that have been neglected in the previous research and propose four different dependency relationships between transactions which may cause damage propagation. We extend existing damage assessment model based on the four novel dependency …

Methodology To Derive Resource Aware Context Adaptable Architectures For Field Programmable Gate Arrays, Harikrishna Samala

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The design of a common architecture that can support multiple data-flow patterns (or contexts) embedded in complex control flow structures, in applications like multimedia processing, is particularly challenging when the target platform is a Field Programmable Gate Array (FPGA) with a heterogeneous mixture of device primitives. This thesis presents scheduling and mapping algorithms that use a novel area cost metric to generate resource aware context adaptable architectures. Results of a rigorous analysis of the methodology on multiple test cases are presented. Results are compared against published techniques and show an area savings and execution time savings of 46% each.

Memory Architecture Template For Fast Block Matching Algorithms On Field Programmable Gate Arrays, Shant Chandrakar

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Fast Block Matching (FBM) algorithms for video compression are well suited for acceleration using parallel data-path architectures on Field Programmable Gate Arrays (FPGAs). However, designing an efficient on-chip memory subsystem to provide the required throughput to this parallel data-path architecture is a complex problem. This thesis presents a memory architecture template that can be parameterized for a given FBM algorithm, number of parallel Processing Elements (PEs), and block size. The template can be parameterized with well known exploration techniques to design efficient on-chip memory subsystems. The memory subsystems are derived for two existing FBM algorithms and are implemented on a …

Self-Healing Cellular Automata To Correct Soft Errors In Defective Embedded Program Memories, Varun Voddi

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Static Random Access Memory (SRAM) cells in ultra-low power Integrated Circuits (ICs) based on nanoscale Complementary Metal Oxide Semiconductor (CMOS) devices are likely to be the most vulnerable to large-scale soft errors. Conventional error correction circuits may not be able to handle the distributed nature of such errors and are susceptible to soft errors themselves. In this thesis, a distributed error correction circuit called Self-Healing Cellular Automata (SHCA) that can repair itself is presented. A possible way to deploy a SHCA in a system of SRAM-based embedded program memories (ePM) for one type of chip multi-processors is also discussed. The …

Classification, Clustering And Data-Mining Of Biological Data, Thomas Triplet

School of Computing: Dissertations, Theses, and Student Research

The proliferation of biological databases and the easy access enabled by the Internet is having a beneficial impact on biological sciences and transforming the way research is conducted. There are currently over 1,100 molecular biology databases dispersed throughout the Internet. However, very few of them integrate data from multiple sources. To assist in the functional and evolutionary analysis of the abundant number of novel proteins, we introduce the PROFESS (PROtein Function, Evolution, Structure and Sequence) database that integrates data from various biological sources. PROFESS is freely available at http://cse.unl.edu/~profess/. Our database is designed to be versatile and expandable and …