Engineering Commons^™

Testing Embedded System Applications, Tingting Yu

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

Embedded systems are becoming increasingly ubiquitous, controlling a wide variety of popular and safety-critical devices. Testing is the most commonly used method for validating software systems, and effective testing techniques could be helpful for improving the dependability of these systems. However, there are challenges involved in developing such techniques. Embedded systems consist of layers of software – application layers utilize services provided by underlying system service and hardware support layers. A typical embedded application consists of multiple user tasks. Interactions between application layers and lower layers, and interactions between the various user tasks that are initiated by the application layer, …

A Comprehensive Analysis Of Lte Physical Layer, Fahimeh Rezaei

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

The 3rd Generation Partnership Project (3GPP) introduced Long Term Evolution (LTE) as the 3rd generation of mobile communication standards. LTE Release 8 describes a mobile communication standard which supports up to 300 Mbps of data transmission in downlink using the OFDM scheme as well as up to 75 Mbps throughput for uplink using the SC-FDMA modulation. In this thesis, an in-depth study of LTE performance based on Release 8 is conducted for uplink and downlink under different scenarios. The main objective of this study is to investigate a comprehensive analysis of physical layer throughput of LTE Release8 based on standard …

Cross-Layer Optimized Wireless Multimedia Networking, Dalei Wu

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

Multimedia communications, especially real-time video communications, is expected to be the major application of the next-generation wireless networks. However, bringing delay-sensitive and loss-tolerant multimedia services based on the current wireless Internet is a very challenging task. In this dissertation, we address cross-layer optimized wireless multimedia networking from both theoretical and practical perspectives. In the first part of the dissertation, we propose cross-layer optimization frameworks for real-time video communications over wireless networks, where the expected received video quality is adopted as the objective function. With the user-centric objective function, we first study content-aware video communications in single-hop wireless networks by exploring …

Experimental Evaluation Of Transmission Link Characteristics In Body Area Networks, Apoorva Kiran Pandya

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

Recent advances in digital electronics, embedded systems, and wireless communications have led the way to a new class of distributed Wireless Sensor Networks (WSNs). A Body Area Network (BAN) is a WSN consisting of miniaturized, low-power, autonomous, wireless biosensors, which are seamlessly placed or implanted in the human body to provide an adaptable and smart health care system. The possible applications of BAN are in health care services and medicine, assisting persons with disabilities, and entertainment and sports. The nodes in a BAN generally use IEEE 802.15.4 radios which have low- power consumption and are relatively immune to interference. In …

Managing Large Data Sets Using Support Vector Machines, Ranjini Srinivas

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

Hundreds of Terabytes of CMS (Compact Muon Solenoid) data are being accumulated for storage day by day at the University of Nebraska-Lincoln, which is one of the eight US CMS Tier-2 sites. Managing this data includes retaining useful CMS data sets and clearing storage space for newly arriving data by deleting less useful data sets. This is an important task that is currently being done manually and it requires a large amount of time. The overall objective of this study was to develop a methodology to help identify the data sets to be deleted when there is a requirement for …

Simsight: A Virtual Machine Based Dynamic Call Graph Generator, Xueling Chen

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

One problem with using component-based software development approach is that once software modules are reused over generations of products, they form legacy structures that can be challenging to understand, making validating these systems difficult. Therefore, tools and methodologies that enable engineers to see interactions of these software modules will enhance their ability to make these software systems more dependable. To address this need, we propose SimSight, a framework to capture dynamic call graphs in Simics, a widely adopted commercial full-system simulator. Simics is a software system that simulates complete computer systems. Thus, it performs nearly identical tasks to …

Jvm-Based Techniques For Improving Java Observability, Peng Du

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

Observability measures the support of computer systems to accurately capture, analyze, and present (collectively observe) the internal information about the systems. Observability frameworks play important roles for program understanding, troubleshooting, performance diagnosis, and optimizations. However, traditional solutions are either expensive or coarse-grained, consequently compromising their utility in accommodating today’s increasingly complex software systems. New solutions are emerging for VM-based languages due to the full control language VMs have over program executions. Existing such solutions, nonetheless, still lack flexibility, have high overhead, or provide limited context information for developing powerful dynamic analyses. In this thesis, we present a VM-based infrastructure, called …

A Framework For Automatically Repairing Gui Test Suites, Si Huang

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

Testing is an effective means for assuring the quality of software. In programs with Graphical User Interfaces (GUIs), event sequences serve as test cases for executing system tests. To aid in the test generation process, researchers have developed methods that automatically derive graph models from GUIs, which can then be traversed to create sequences for testing. Recent advances using these graph models incorporate combinatorial interaction testing sampling techniques to generate longer GUI test cases, which exercise more event interactions and have been shown to improve fault detection. However, because the models extracted are only approximations of the actual event interactions, …

A Single Chip Computational Sensor System For Neutron Detection Applications, Nathan R. Schemm, Sina Balkir, Michael Hoffman, Mark Bauer, David Schultz, James C. Petrosky, John W. Mcclory, Marcus Natta, Jennifer I. Brand, Jinke Tang, Wendong Wang

Department of Electrical and Computer Engineering: Faculty Publications

This paper presents the design and test results of a standalone computational radiation sensor system based on a single chip solution. A low-power sensor front end with a charge sensitive amplifier and an event driven analog-to-digital converter is integrated on the same chip as a dedicated microcontroller to process and bin the data from the neutron detector diode heterojunction according to pulse height. This combination effectively implements a single chip multichannel analyzer with the capability to do further processing of the data in software. The design was fabricated in a 0.18 CMOS technology with field tests demonstrating the validity of …

Designing Software Product Lines For Testability, Isis Cabral

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

Software product line (SPL) engineering offers several advantages in the development of families of software products such as reduced costs, high quality and a short time to market. A software product line is a set of software intensive systems, each of which shares a common core set of functionalities, but also differs from the other products through customization tailored to fit the needs of individual groups of customers. The differences between products within the family are well-understood and organized into a feature model that represents the variability of the SPL. Products can then be built by generating and composing features …

Flying Mobile On-Board Ellipsometer, Polarimeter, Reflectometer And The Like Systems, Blaine D. Johs, Ping He, Martin M. Liphardt, Christopher A. Goeden, John A. Woollam, James D. Welch

Department of Electrical and Computer Engineering: Faculty Publications

A substantially self-contained "on-board" material system investigation system for effecting relative translational and rotational motion between a source and detector of electromagnetic radiation and a sample, which system is functionally mounted on a three-dimensional locational system to enable positioning at desired locations on, and distances from, the surface of a sample, including the capability to easily and conveniently effect rotation and/or to change the angle-of-incidence of a beam of electromagnetic radiation onto a sample surface and/or to provide gas flow confined in a mini-chamber near the surface of a sample, at a location at which a beam having UV, VUV, …

Analysis And Transformation Of Pipe-Like Web Mashups For End User Programmers, Kathryn T. Stolee

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

Mashups are becoming increasingly popular as end users are able to easily access, manipulate, and compose data from several web sources. To support end users, communities are forming around mashup development environments that facilitate sharing code and knowledge. We have observed, however, that end user mashups tend to suffer from several deficiencies, such as inoperable components or references to invalid data sources, and that those deficiencies are often propagated through the rampant reuse in these end user communities.

In this work, we identify and specify ten code smells indicative of deficiencies we observed in a sample of 8,051 pipe-like web …

Assembly Of Ordered Carbon Shells On Semconducting Nanomaterals, Eli Anguelova Sutter, Peter Werner Sutter

Department of Electrical and Computer Engineering: Faculty Publications

In some embodiments of the invention, encapsulated semiconducting nanomaterials are described. In certain embodiments the nanostructures described are semiconducting nanomaterials encapsulated with ordered carbon shells. In some aspects a method for producing encapsulated semiconducting nanomaterials is disclosed. In some embodiments applications of encapsulated semiconducting nanomaterials are described.

Rapport: Semantic-Sensitive Namespace Management In Large-Scale File Systems, Yu Hua, Hong Jiang, Yifeng Zhu, Dan Feng

CSE Technical Reports

Explosive growth in volume and complexity of data exacerbates the key challenge to effectively and efficiently manage data in a way that fundamentally improves the ease and efficacy of their use. Existing large-scale file systems rely on hierarchically structured namespace that leads to severe performance bottlenecks and renders it impossible to support real-time queries on multi-dimensional attributes. This paper proposes a novel semantic-sensitive scheme, called Rapport, to provide dynamic and adaptive namespace management and support complex queries. The basic idea is to build files’ namespace by utilizing their semantic correlation and exploiting dynamic evolution of attributes to support namespace management. …

Channel Characterization For Wireless Underground Sensor Networks, Agnelo R. Silva

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

Wireless Underground Sensor Networks (WUSNs) are natural extensions of the established Wireless Sensor Network (WSN) phenomenon and consist of sensors buried underground which communicate through soil. WUSNs have the potential to impact a wide variety of applications including precision agriculture, environmental monitoring, border patrol, and infrastructure monitoring. The main difference between WUSNs and traditional wireless networks is the communication medium. However, a comprehensive wireless underground channel model for WUSNs has not been developed so far. In this thesis, the Soil Subsurface Wireless Communication (SSWC) channel model is developed based on an extensive empirical study in a large agriculture field. The …

Dsfs: Decentralized Security For Large Parallel File Systems, Zhongying Niu, Hong Jiang, Ke Zhou, Dan Feng, Tianming Yang, Dongliang Lei, Anli Chen

CSE Technical Reports

This paper describes DSFS, a decentralized security system for large parallel file system. DSFS stores global access control lists (ACLs) in a centralized decisionmaking server and pushes pre-authorization lists (PALs) into storage devices. Thus DSFS allows users to flexibly set any access control policy for the global ACL or even change the global ACL system without having to upgrade the security code in their storage devices. With pre-authorization lists, DSFS enables a networkattached storage device to immediately authorize I/O, instead of demanding a client to acquire an authorization from a centralized authorization server at a crucial time. The client needs …

Service-Differentiated And Reliable Communication In Event-Based Wireless Sensor Networks, Yuyan Xue

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

Wireless Sensor Networks (WSNs) consist of low-power embedded devices with integrated sensing, computing and wireless communication capabilities. These devices, called sensor nodes or motes, are often battery-powered and deployed in a distributed manner to provide observations on the physical world. Reliably and promptly collecting the sensing data to convey the features of a surveillance area, especially the events of interest, to the sink is one of the most critical requirements of WSN design. However, dynamic wireless channel conditions and the constrained energy resources make it a challenging task to provide the end-to-end performance guarantees in multi-hop WSNs.

The objective of …

Study Of Physical Layer Security In Wireless Communications, Mustafa Duruturk

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

This thesis has investigated security in wireless communications at physical layer. Security is an important issue for wireless communications and poses many challenges. Most security schemes have been applied to the upper layers of communications networks. Since in a typical wireless communication, transmission of data is over the air, third party receiver(s) may have easy access to the transmitted data. This work discusses a new security technique at the physical layer for the MIMO (802.11n) transmitters. For this project, the wireless medium is secured by transmitting a noise signal that is only recoverable by the receiver. This report includes an …

Performance Of Self-Encoded Spread Spectrum Under Worst-Case Jamming, Casey L. Deyle

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

Performance of Self-Encoded Spread Spectrum Under Worst-Case Jamming Casey Deyle, M.S University of Nebraska 2009 Advisor: Lim Nguyen Spread Spectrum Communications uses m-sequences (sometimes referred to as Pseudo Noise or PN sequences) modulated with a data signal to create a transmission signal that takes up more bandwidth than the original information signal. Self-Encoded Spread Spectrum (SESS) uses spreading codes generated by the transmitted signal, eliminating the need to synchronize m-sequences between the transmitter and receiver, thus making the channel more secure. This paper will discuss the performance of SESS system in Additive White Gaussian Noise (AWGN) and Rayleigh fading channels, …

Coset: Cooperative Set Last Level Caches, Dongyuan Zhan, Hong Jiang, Sharad Seth

CSE Technical Reports

The speed gap between processors and DRAM remains a crit-ical performance bottleneck for contemporary computer systems, which necessitates an effective management of last level caches (LLC) to minimize expensive off-chip accesses. However, because all sets in a conventional set-associative cache design are statically assigned an equal number of blocks, the LLC capacity utilization can drastically diminish when the cache actually exhibits non-uniform capacity demands across the sets. To reveal the wide exis-tence of set-level non-uniformity of capacity demand in real appli-cations, this technical report first establishes an accurate metric for measuring individual sets’ capacity demands by developing a group of …

Protein Adsorption On And Swelling Of Polyelectrolyte Brushes: A Simultaneous Ellipsometry-Quartz Crystal Microbalance Study, Eva Bittrich, Keith B. Rodenhausen Jr., Klaus-Jochen Eichhorn, Tino Hofmann, Mathias Schubert, Manfred Stamm, Petra Uhlmann

Department of Electrical and Computer Engineering: Faculty Publications

With a coupled spectroscopic ellipsometry-quartz crystal microbalance with dissipation (QCM-D) experimental setup, quantitative information can be obtained about the amount of buffer components (water molecules and ions) coupled to a poly(acrylic acid) (PAA) brush surface in swelling and protein adsorption processes. PAA Guiselin brushes with more than one anchoring point per single polymer chain were prepared. For the swollen brushes a high amount of buffer was found to be coupled to the brush-solution interface in addition to the content of buffer inside the brush layer. Upon adsorption of bovine serum albumin the further incorporation of buffer molecules into the protein-brush …

Data Compression Concepts And Algorithms And Their Applications To Bioinformatics, Ozkan U. Nalbantoglu, David J. Russell, Khalid Sayood

Department of Electrical and Computer Engineering: Faculty Publications

Data compression at its base is concerned with how information is organized in data. Understanding this organization can lead to efficient ways of representing the information and hence data compression. In this paper we review the ways in which ideas and approaches fundamental to the theory and practice of data compression have been used in the area of bioinformatics. We look at how basic theoretical ideas from data compression, such as the notions of entropy, mutual information, and complexity have been used for analyzing biological sequences in order to discover hidden patterns, infer phylogenetic relationships between organisms and study viral …

Discrete Coordinate Transformation For Designing All-Dielectric Flat Antennas, Wenxuan Tang, Christos Argyropoulos, Efthymios Kallos, Wei Song, Yang Hao

Department of Electrical and Computer Engineering: Faculty Publications

Transformation electromagnetics provides a practical approach to control electromagnetic fields at will. Based on this principle, novel devices such as the invisible cloak have been proposed. Here we examine the extension of this technique as applied to the design of flat devices in antenna systems. A method using discrete coordinate transformation is proposed, which allows the conversion of conventional devices with curved shapes into flat systems, while preserving their non-dispersive, isotropic, broadband, and lossless properties. Two specific design examples, a flat reflector and a flat lens embedded in free space, are presented. To avoid the loss and narrow bandwidth issues …

Clustering Of Protein Families Into Functional Subtypes Using Relative Complexity Measure With Reduced Amino Acid Alphabets, Aydin Albayrak, Hasan H. Otu, Ugur O. Sezerman

Department of Electrical and Computer Engineering: Faculty Publications

Background: Phylogenetic analysis can be used to divide a protein family into subfamilies in the absence of experimental information. Most phylogenetic analysis methods utilize multiple alignment of sequences and are based on an evolutionary model. However, multiple alignment is not an automated procedure and requires human intervention to maintain alignment integrity and to produce phylogenies consistent with the functional splits in underlying sequences. To address this problem, we propose to use the alignment-free Relative Complexity Measure (RCM) combined with reduced amino acid alphabets to cluster protein families into functional subtypes purely on sequence criteria. Comparison with an alignment-based approach was …

Bioinformatic Identification And Characterization Of Human Endothelial Cell-Restricted Genes, Manoj Bhasin, Lei Yuan, Derin B. Keskin, Hasan H. Otu, Towia A. Libermann, Peter Oettgen

Department of Electrical and Computer Engineering: Faculty Publications

Background: In this study, we used a systematic bioinformatics analysis approach to elucidate genes that exhibit an endothelial cell (EC) restricted expression pattern, and began to define their regulation, tissue distribution, and potential biological role.

Results:Using a high throughput microarray platform, a primary set of 1,191 transcripts that are enriched in different primary ECs compared to non-ECs was identified (LCB >3, FDR

Conclusion: The study provides an initial catalogue of EC-restricted genes most of which are ubiquitously expressed in different endothelial cells.

Tob1 Is A Constitutively Expressed Repressor Of Liver Regeneration, Karen J. Ho, Nhue L. Do, Hasan H. Otu, Martin J. Dib, Xianghui Ren, Keiichi Enjyoji, Simon C. Robson, Ernest F. Terwilliger, Seth J. Karp

Department of Electrical and Computer Engineering: Faculty Publications

How proliferative and inhibitory signals integrate to control liver regeneration remains poorly understood. A screen for antiproliferative factors repressed after liver injury identified transducer of ErbB2.1 (Tob1), a member of the PC3/BTG1 family of mito-inhibitory molecules as a target for further evaluation. Tob1 protein decreases after 2/3 hepatectomy in mice secondary to posttranscriptional mechanisms. Deletion of Tob1 increases hepatocyte proliferation and accelerates restoration of liver mass after hepatectomy. Down-regulation of Tob1 is required for normal liver regeneration, and Tob1 controls hepatocyte proliferation in a dose-dependent fashion. Tob1 associates directly with both Caf1 and cyclindependent kinase (Cdk) 1 and …

Iterative Signal Processing In Communications, Christian Schlegel, Peter Hoeher, Owe Axelsson, Lance C. Pérez

Department of Electrical and Computer Engineering: Faculty Publications

Iterative signal processing in communications has experienced an explosive rise in popularity in recent years. The catalytic origins of this paradigm-shifting new philosophy among communications experts can be traced to the invention of turbo coding, and the subsequent rediscovery of low-density parity check (LDPC) coding, both in the field of error control coding. Both systems rely on iterative decoding algorithms to achieve their astounding performance. However, iterative signal processing is not confined to the decoding of error control codes and rather quickly spread to many other possible applications. The purpose of this special issue is to examine the concept of …

The Manifestation Of Stopping Sets And Absorbing Sets As Deviations On The Computation Trees Of Ldpc Codes, Eric T. Psota, Lance C. Perez

Department of Electrical and Computer Engineering: Faculty Publications

The error mechanisms of iterative message-passing decoders for low-density parity-check codes are studied. A tutorial review is given of the various graphical structures, including trapping sets, stopping sets, and absorbing sets that are frequently used to characterize the errors observed in simulations of iterative decoding of low-density parity-check codes. The connections between trapping sets and deviations on computation trees are explored in depth using the notion of problematic trapping sets in order to bridge the experimental and analytic approaches to these error mechanisms. A new iterative algorithm for finding low-weight problematic trapping sets is presented and shown to be capable …

Mimo Self-Encoded Spread Spectrum With Iterative Detection Over Rayleigh Fading Channels, Shichuan Ma, Lim Nguyen, Won Mee Jang, Yaoqing (Lamar) Yang

Department of Electrical and Computer Engineering: Faculty Publications

Self-encoded spread spectrum (SESS) is a novel communication technique that derives its spreading code from the randomness of the source stream rather than using conventional pseudorandom noise (PN) code. In this paper, we propose to incorporate SESS in multiple-input multiple-output (MIMO) systems as a means to combat against fading effects in wireless channels. Orthogonal space-time block-coded MIMO technique is employed to achieve spatial diversity, and the inherent temporal diversity in SESS modulation is exploited with iterative detection. Simulation results demonstrate that MIMO-SESS can effectively mitigate the channel fading effect such that the system can achieve a bit error rate of …

Non-Destructiveapproachto Ellipsometric Monitoring Of A Film Coating On The Inner Surface Of A Tube Shaped Sample, Gregory K. Prilbil, John A. Woollam, Martin M. Liphardt, James D. Welch

Department of Electrical and Computer Engineering: Faculty Publications

Disclosed is the use of a focused electromagnetic beam which is caused to impinge on the top surface of a tube shaped sample, to investigate a film coating on inner surface during fabrication thereof and/or thereafter.