Computer 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 …