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, …

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, …

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 …

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 …

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 …

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 …

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

Department of Computer Science and Engineering: 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 …

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

Department of Computer Science and Engineering: 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 1100 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 athttp://cse.unl.edu/~profess/. Our database is designed to be versatile and expandable and will not …

Temporal Data Classification Using Linear Classifiers, Peter Revesz, Thomas Triplet

CSE Conference and Workshop Papers

Data classification is usually based on measurements recorded at the same time. This paper considers temporal data classification where the input is a temporal database that describes measurements over a period of time in history while the predicted class is expected to occur in the future. We describe a new temporal classification method that improves the accuracy of standard classification methods. The benefits of the method are tested on weather forecasting using the meteorological database from the Texas Commission on Environmental Quality.

Exploiting Set-Level Non-Uniformity Of Capacity Demand To Enhance Cmp Cooperative Caching, Dongyuan Zhan, Hong Jiang, Sharad C. Seth

CSE Technical Reports

As the Memory Wall remains a bottleneck for Chip Multiprocessors (CMP), the effective management of CMP last level caches becomes of paramount importance in minimizing expensive off-chip memory accesses. For the CMPs with private last level caches, Cooperative Caching (CC) has been proposed to enable capacity sharing among private caches by spilling an evicted block from one cache to another. But this eviction-driven CC does not necessarily promote cache performance since it implicitly favors the applications full of block evictions regardless of their real capacity demand. The recent Dynamic Spill-Receive (DSR) paradigm improves cooperative caching by prioritizing applications with higher …

Design Of An All-Optical Wdm Lightpath Concentrator, Shivashis Saha, Jitender S. Deogun

CSE Technical Reports

A design of a nonblocking, all-optical lightpath concentrator using WOC and WDM crossbar switches is presented. The proposed concentrator is highly scalable, cost-efficient, and can switch signals in both space and wavelength domains without requiring a separate wavelength conversion stage.

Selection Of Switching Sites In All-Optical Nework Topology Design, Shivashis Saha, Eric D. Manley, Jitender S. Deogun

CSE Technical Reports

In this paper, we consider the problem of topology design for optical networks. We investigate the problem of selecting switching sites to minimize total cost of the optical network. The cost of an optical network can be expressed as a sum of three main factors: the site cost, the link cost, and the switch cost. To the best of our knowledge, this problem has not been studied in its general form as investigated in this paper. We present a mixed integer quadratic programming (MIQP) formulation of the problem to find the optimal value of the total network cost. We also …

Deployed Software Analysis, Madeline M. Diep

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

Profiling can offer a valuable characterization of software behavior. The richer the characterization is, the more effective the client analyses are in supporting quality assurance activities. For today's complex software, however, obtaining a rich characterization with the input provided by in-house test suites is becoming more difficult and expensive. Extending the profiling activity to deployed environments can mitigate this shortcoming by exposing more program behavior reflecting real software usage. To make profiling of deployed software plausible, however, we need to take into consideration that there are fundamental differences between the development and the deployed environments. Deployed environments allow for less …

Adaptive Interpolation Algorithms For Temporal-Oriented Datasets, Jun Gao

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

Spatiotemporal datasets can be classified into two categories: temporal-oriented and spatial-oriented datasets depending on whether missing spatiotemporal values are closer to the values of its temporal or spatial neighbors. We present an adaptive spatiotemporal interpolation model that can estimate the missing values in both categories of spatiotemporal datasets. The key parameters of the adaptive spatiotemporal interpolation model can be adjusted based on experience.

Spatiotemporal Databases: Models For Attracting Students To Research, Ágnes Bércesné Novák, Peter Revesz, Zsolt Tuza

CSE Conference and Workshop Papers

In higher education professors often make much effort to introduce their students to research. Unfortunately, the present standard database systems curriculum is composed of well-settled subjects that do not lead to research. The challenge is to bring the research frontier closer to students at beginner level. In this paper we describe how it can be done in the area of spatiotemporal databases. We propose a new database systems curriculum and illustrate its benefits by mentioning several highly succsesful student projects in some recent experimental introductory database systems courses that followed the new curriculum.

Constraint Datalog In Trust Management, Scot Anderson

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

Constraint Datalog holds an increasing role in Trust Management. We discuss several Trust Management systems and give a description of the environment and requirements for Trust Management. Constraint Datalog using addition constraints and approximation theory provides an expressive semantic with which to describe security policies for credentials, delegations and authorizations. Approximation theory allows halting in Constraint Datalog over addition constraints. We use the decision problem of Diophantine equations to show that Constraint Datalog over addition constraints is complete. Combining these two concepts provides an approximately complete, safe language. The problem of constant additions to closed languages provides reasons for using …

User Interface Improvement For Mlpq System, Shasha Wu

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

This thesis describes the experience of migrating the MLPQ constraint database system, a complex standalone Multiple Document Interface (MDI) application, to a server-based remote accessible application. Centralized, standalone MDI application is a common style for personal software products in Windows. For a database management system, server-based, thin-client computing is a more popular infrastructure. Migrating an existing standalone constraint database application to be a web accessible constraint database server is the main goal of this thesis. This migration process provides a method for the constraint database system to collaborate with other specific applications. We rebuild the desktop MLPQ constraint database system …

Cxquery: A Novel Xml Query Language, Peter Revesz, Yi Chen

CSE Conference and Workshop Papers

XML is becoming the data exchange standard on the Internet. Previously proposed XML query languages, such as XQuery, Quilt, YALT, Lorel, and XML-QL, lack schema definition of the query result; therefore, they are limited for defining views, integrating data, updating, and further querying, all of which are often needed in e-Business applications. We propose a novel XML query language called CXQuery, which defines the schema of the query results explicitly and can easily define views, and integrate, update, and query XML data. In addition, CXQuery can express spatial and spatio-temporal queries using a constraint-based querying approach.

Mlpq: A Linear Constraint Database System With Aggregate Operators, Yiming Li

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

In this project report, I will discuss a Multiple Linear Programming Query (MLPQ) system and the theoretical background of this system.The MPLQ system is developed to solve some realistic problems involving both linear programming (UP) techniques and linear constraint databases (LCDBs) theory. The MLPQ system is aimed at providing a mechanism of bridging these two important areas. system basically consists of three parts which are a linear constraint database, an LP solver, and an interface between the LCDB and the LP solver. The LCDB of the MLPQ system contains multiple linear programming problems. The LP solver used in the MPLQ …

Safe Stratified Datalog With Integer Order Programs, Peter Revesz

CSE Conference and Workshop Papers

Guaranteeing termination of programs on all valid inputs is important for database applications. Termination cannot be guaranteed in Stratified Datalog with integer (gap)-order programs on generalized databases because they express any Turing-computable function. This paper introduces a restriction of those programs that can express only computable queries. The restricted language has a high expressive power and a non-elementary data complexity.

Constraint Objects, Divesh Srivastava, Raghu Ramakrishnan, Peter Revesz

CSE Conference and Workshop Papers

We describe the Constraint Object Data Model (CODM), which enhances an object-based data model with existential constraints to naturally represent partially specified information. We present the Constraint Object Query Language (COQL), a declarative, rule-based query language that can be used to infer relationships about and monotonically refine information represented in the CODM. COQL has a model-theoretic and an equivalent fixed-point semantics, based on the notions of constraint entailment and "proofs in all possible worlds." We also provide a novel polynomial-time algorithm for quantifier elimination for set-order constraints, a restricted class of set constraints that uses membership of subset-equal.

A Sign-To-Speech Translation System, Koka Veera Raghava Rao

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

This thesis describes sign-to-speech translation using neural networks. Sign language translation is an interesting but difficult problem for which neural network techniques seem promising because of their ability to adjust to the user's hand movements, which is not possible to do by most other techniques. However, even using neural networks and artificial sign languages, the translation is hard, and the best-known system, that of Fels & Hinton (1993), is capable of translating only 66 root words and 203 words including their conjugations. This research improves their results to 790 root signs and 2718 words including their conjugations while preserving a …

An Exact Analysis For Efficient Computation Of Random-Pattern Testability In Combinational Circuits, Sharad C. Seth, Bhargab B. Bhattacharya, Vishwani Agrawal

CSE Conference and Workshop Papers

Experimental evidence shows that low testability in a typical circuit is much more likely due to poor observability than poor controllability. Thus, from theoretical and practical standpoints, it is important to develop an accurate model for observability computation. One such model, in terms of supergates, is proposed in the first part of this paper thus complimenting our earlier work. It is now possible to obtain exact random-pattern testability for each line in a circuit.

The second part of the paper analyzes the supegate structure of a circuit from a graph theoretic viewpoint. Finding a supergate is related to determining the …