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Title: A PERFORMANCE COMPARISON OF CLUSTERING ALGORITHMS IN AD HOCNETWORKS.
Creator: Yeung, Chun, Turgut, Damla, University of Central Florida
Abstract / Description: An ad hoc network is comprised of wireless mobile nodes without the need of wired network infrastructure. Due to the limited transmission range of nodes, the exchange of data between them may not be possible using direct communication. Partitioning the network into clusters and electing a clusterhead for each cluster to assist with the resource allocation and data packet transmissions among its members and neighboring clusterheads is one of the most common ways of providing support for the...
Show moreAn ad hoc network is comprised of wireless mobile nodes without the need of wired network infrastructure. Due to the limited transmission range of nodes, the exchange of data between them may not be possible using direct communication. Partitioning the network into clusters and electing a clusterhead for each cluster to assist with the resource allocation and data packet transmissions among its members and neighboring clusterheads is one of the most common ways of providing support for the existing ad hoc routing protocols. This thesis presents the performance comparison of four ad hoc network clustering protocols: Dynamic Mobile Adaptive Clustering (DMAC), Highest-Degree and Lowest-ID algorithms, and Weighted Clustering Algorithm (WCA). Yet Another Extensible Simulation (YAES) was used as the simulator to carry out the simulations.
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Date Issued: 2006
Identifier: CFE0001314, ucf:47022
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001314

Title: ULTRAWIDEBAND INDOOR LOCATION AND TRACKING SYSTEM.
Creator: Chen, Qing, Turgut, Damla, University of Central Florida
Abstract / Description: The objective of this thesis is to demonstrate an indoor intruder location and tracking system with UltraWideBand (UWB) technology and use data compression and Constant False Alarm Rate (CFAR) techniques to improve the performance of the location system. Reliable and accurate indoor positioning requires a local replacement for GPS systems since satellite signals are not available indoors. UWB systems are particularly suitable for indoor location systems due their inherent capabilities such as...
Show moreThe objective of this thesis is to demonstrate an indoor intruder location and tracking system with UltraWideBand (UWB) technology and use data compression and Constant False Alarm Rate (CFAR) techniques to improve the performance of the location system. Reliable and accurate indoor positioning requires a local replacement for GPS systems since satellite signals are not available indoors. UWB systems are particularly suitable for indoor location systems due their inherent capabilities such as low-power, multi-path rejection, and wide bandwidth. In our application, we are using UWB radios as a radar system for tracking targets in indoor locations. We also use Discrete Cosine Transform (DCT) to compress the UWB scan waveforms from the receivers to the main computer to conserve bandwidth. At the main computer, we use Inverse DCT to recover the original signal. The UWB intruder detection system has the indoor tracking accuracy of four inches. There are many military and commercial applications such as tracking firefighters and locating trapped people in earthquake zones, and so on. This thesis demonstrates the capability of a UWB radar system to locate and track an intruder to an accuracy of four inches in an indoor cluttered environment.
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Date Issued: 2006
Identifier: CFE0001233, ucf:46924
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001233

Title: A HYBRID ROUTING PROTOCOL FOR COMMUNICATIONS AMONG NODES WITHHIGH RELATIVE SPEED IN WIRELESS MESH NETWORKS.
Creator: PEPPAS, NIKOLAOS, Turgut, Damla, University of Central Florida
Abstract / Description: Wireless mesh networks (WMN) is a new promising wireless technology which uses already available hardware and software components. This thesis proposes a routing algorithm for military applications. More specifically, a specialized scenario consisting of a network of flying Unmanned Aerial Vehicles (UAVs) executing reconnaissance missions is investigated. The proposed routing algorithm is hybrid in nature and uses both reactive and proactive routing characteristics to transmit information....
Show moreWireless mesh networks (WMN) is a new promising wireless technology which uses already available hardware and software components. This thesis proposes a routing algorithm for military applications. More specifically, a specialized scenario consisting of a network of flying Unmanned Aerial Vehicles (UAVs) executing reconnaissance missions is investigated. The proposed routing algorithm is hybrid in nature and uses both reactive and proactive routing characteristics to transmit information. Through simulations run on a specially built stand alone simulator, based on Java, packet overhead, delivery ratio and latency metrics were monitored with respect to varying number of nodes, node density and mobility. The results showed that the high overhead leads to high delivery ratio while latency tends to increase as the network grows larger. All the metrics revealed sensitivity in high mobility conditions.
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Date Issued: 2007
Identifier: CFE0001607, ucf:47165
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001607

Title: CONGESTION AVOIDANCE AND FAIRNESS IN WIRELESS SENSOR NETWORKS.
Creator: Ahmad, Mohammad, Turgut, Damla, University of Central Florida
Abstract / Description: Sensor network congestion avoidance and control primarily aims to reduce packet drops while maintaining fair bandwidth allocation to existing network flows. The design of a congestion control algorithm suited for all types of applications in sensor networks is a challenging task due to the application-specific nature of these networks. With numerous sensors transmitting data simultaneously to one or more base stations (also called sinks), sensor nodes located near the base station will most...
Show moreSensor network congestion avoidance and control primarily aims to reduce packet drops while maintaining fair bandwidth allocation to existing network flows. The design of a congestion control algorithm suited for all types of applications in sensor networks is a challenging task due to the application-specific nature of these networks. With numerous sensors transmitting data simultaneously to one or more base stations (also called sinks), sensor nodes located near the base station will most likely experience congestion and packet loss. In this thesis, we propose a novel distributed congestion avoidance algorithm which calculates the ratio of the number of downstream and upstream nodes. This ratio value (named Characteristic ratio) is used to take a routing decision and incorporate load balancing while also serving as a pointer to the congestion state of the network. Available queue sizes of the downstream nodes are used to detect incipient congestion. Queue characteristics of candidate downstream nodes are used collectively to implement both congestion avoidance and fairness by adjusting the node's forwarding rate and next hop destination. Such an approach helps to minimize packet drops, improve energy efficiency and load balancing. In cases of severe congestion, the source is signaled to reduce its sending rate and enable the network recovery process. This is essentially a transport layer algorithm and would work best with a multi-path routing protocol and almost any MAC layer standard. We present the design and implementation of the proposed protocol and compare it with the existing avoidance protocols like Global rate control and Lightweight buffering. Our simulation results show a higher packet delivery ratio with greater node buffer utilization for our protocol in comparison with the conventional mechanisms.
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Date Issued: 2007
Identifier: CFE0001755, ucf:47255
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001755

Title: INTRUSION DETECTION IN WIRELESS SENSOR NETWORKS.
Creator: NGUYEN, HONG NHUNG, Turgut, Damla, University of Central Florida
Abstract / Description: There are several applications that use sensor motes and researchers continue to explore additional applications. For this particular application of detecting the movement of humans through the sensor field, a set of Berkley mica2 motes on TinyOS operating system is used. Different sensors such as pressure, light, and so on can be used to identify the presence of an intruder in the field. In our case, the light sensor is chosen for the detection. When an intruder crosses the monitored...
Show moreThere are several applications that use sensor motes and researchers continue to explore additional applications. For this particular application of detecting the movement of humans through the sensor field, a set of Berkley mica2 motes on TinyOS operating system is used. Different sensors such as pressure, light, and so on can be used to identify the presence of an intruder in the field. In our case, the light sensor is chosen for the detection. When an intruder crosses the monitored environment, the system detects the changes of the light values, and any significant change meaning that a change greater than a pre-defined threshold. This indicates the presence of an intruder. An integrated web cam is used to take snapshot of the intruder and transmit the picture through the network to a remote station. The basic motivation of this thesis is that a sensor web system can be used to monitor and detect any intruder in a specific area from a remote location.
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Date Issued: 2006
Identifier: CFE0001027, ucf:46793
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001027

Title: Joint Optimization of Illumination and Communication for a Multi-Element VLC Architecture.
Creator: Ibne Mushfique, Sifat, Yuksel, Murat, Pourmohammadi Fallah, Yaser, Turgut, Damla, University of Central Florida
Abstract / Description: Because of the ever increasing demand wireless data in the modern era, the Radio Frequency (RF) spectrum is becoming more congested. The remaining RF spectrum is being shrunk at a very heavy rate, and spectral management is becoming more difficult. Mobile data is estimated to grow more than 10 times between 2013 and 2019, and due to this explosion in data usage, mobile operators are having serious concerns focusing on public Wireless Fidelity (Wi-Fi) and other alternative technologies....
Show moreBecause of the ever increasing demand wireless data in the modern era, the Radio Frequency (RF) spectrum is becoming more congested. The remaining RF spectrum is being shrunk at a very heavy rate, and spectral management is becoming more difficult. Mobile data is estimated to grow more than 10 times between 2013 and 2019, and due to this explosion in data usage, mobile operators are having serious concerns focusing on public Wireless Fidelity (Wi-Fi) and other alternative technologies. Visible Light Communication (VLC) is a recent promising technology complementary to RF spectrum which operates at the visible light spectrum band (roughly 400 THz to 780 THz) and it has 10,000 times bigger size than radio waves (roughly 3 kHz to 300 GHz). Due to this tremendous potential, VLC has captured a lot of interest recently as there is already an extensive deployment of energy efficient Light Emitting Diodes (LEDs). The advancements in LED technology with fast nanosecond switching times is also very encouraging. In this work, we present hybrid RF/VLC architecture which is capable of providing simultaneous lighting and communication coverage in an indoor setting. The architecture consists of a multi-element hemispherical bulb design, where it is possible to transmit multiple data streams from the multi-element hemispherical bulb using LED modules. We present the detailed components of the architecture and make simulations considering various VLC transmitter configurations. Also, we devise an approach for an efficient bulb design mechanism to maintain both illumination and communication at a satisfactory rate, and analyze it in the case of two users in a room. The approach involves formulating an optimization problem and tackling the problem using a simple partitioning algorithm. The results indicate that good link quality and high spatial reuse can be maintained in a typical indoor communication setting.
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Date Issued: 2018
Identifier: CFE0007016, ucf:52025
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007016

Title: Towards High-Performance Big Data Processing Systems.
Creator: Zhang, Hong, Wang, Liqiang, Turgut, Damla, Wang, Jun, Zhang, Shunpu, University of Central Florida
Abstract / Description: The amount of generated and stored data has been growing rapidly, It is estimated that 2.5 quintillion bytes of data are generated every day, and 90% of the data in the world today has been created in the last two years. How to solve these big data issues has become a hot topic in both industry and academia.Due to the complex of big data platform, we stratify it into four layers: storage layer, resource management layer, computing layer, and methodology layer. This dissertation proposes brand...
Show moreThe amount of generated and stored data has been growing rapidly, It is estimated that 2.5 quintillion bytes of data are generated every day, and 90% of the data in the world today has been created in the last two years. How to solve these big data issues has become a hot topic in both industry and academia.Due to the complex of big data platform, we stratify it into four layers: storage layer, resource management layer, computing layer, and methodology layer. This dissertation proposes brand-new approaches to address the performance of big data platforms like Hadoop and Spark on these four layers.We first present an improved HDFS design called SMARTH, which optimizes the storage layer. It utilizes asynchronous multi-pipeline data transfers instead of a single pipeline stop-and-wait mechanism. SMARTH records the actual transfer speed of data blocks and sends this information to the namenode along with periodic heartbeat messages. The namenode sorts datanodes according to their past performance and tracks this information continuously. When a client initiates an upload request, the namenode will send it a list of ''high performance'' datanodes that it thinks will yield the highest throughput for the client. By choosing higher performance datanodes relative to each client and by taking advantage of the multi-pipeline design, our experiments show that SMARTH significantly improves the performance of data write operations compared to HDFS. Specifically, SMARTH is able to improve the throughput of data transfer by 27-245% in a heterogeneous virtual cluster on Amazon EC2. Secondly, we propose an optimized Hadoop extension called MRapid, which significantly speeds up the execution of short jobs on the resource management layer. It is completely backward compatible to Hadoop, and imposes negligible overhead. Our experiments on Microsoft Azure public cloud show that MRapid can improve performance by up to 88% compared to the original Hadoop.Thirdly, we introduce an efficient 3-level sampling performance model, called Hedgehog, and focus on the relationship between resource and performance. This design is a brand new white-box model for Spark, which is more complex and challenging than Hadoop. In our tool, we employ a Java bytecode manipulation and analysis framework called ASM to reduce the profiling overhead dramatically.Fourthly, on the computing layer, we optimize the current implementation of SGD in Spark's MLlib by reusing data partition for multiple times within a single iteration to find better candidate weights in a more efficient way. Whether using multiple local iterations within each partition is dynamically decided by the 68-95-99.7 rule. We also design a variant of momentum algorithm to optimize step size in every iteration. This method uses a new adaptive rule that decreases the step size whenever neighboring gradients show differing directions of significance. Experiments show that our adaptive algorithm is more efficient and can be 7 times faster compared to the original MLlib's SGD.At last, on the application layer, we present a scalable and distributed geographic information system, called Dart, based on Hadoop and HBase. Dart provides a hybrid table schema to store spatial data in HBase so that the Reduce process can be omitted for operations like calculating the mean center and the median center. It employs reasonable pre-splitting and hash techniques to avoid data imbalance and hot region problems. It also supports massive spatial data analysis like K-Nearest Neighbors (KNN) and Geometric Median Distribution. In our experiments, we evaluate the performance of Dart by processing 160 GB Twitter data on an Amazon EC2 cluster. The experimental results show that Dart is very scalable and efficient.
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Date Issued: 2018
Identifier: CFE0007271, ucf:52208
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007271

Title: UTILIZING EDGE IN IOT AND VIDEO STREAMING APPLICATIONS TO REDUCE BOTTLENECKS IN INTERNET TRAFFIC.
Creator: Akpinar, Kutalmis, Hua, Kien, Zou, Changchun, Turgut, Damla, Wang, Jun, University of Central Florida
Abstract / Description: There is a large increase in the surge of data over Internet due to the increasing demand on multimedia content. It is estimated that 80% of Internet traffic will be video by 2022, according to a recent study. At the same time, IoT devices on Internet will double the human population. While infrastructure standards on IoT are still nonexistent, enterprise solutions tend to encourage cloud-based solutions, causing an additional surge of data over the Internet. This study proposes solutions to...
Show moreThere is a large increase in the surge of data over Internet due to the increasing demand on multimedia content. It is estimated that 80% of Internet traffic will be video by 2022, according to a recent study. At the same time, IoT devices on Internet will double the human population. While infrastructure standards on IoT are still nonexistent, enterprise solutions tend to encourage cloud-based solutions, causing an additional surge of data over the Internet. This study proposes solutions to bring video traffic and IoT computation back to the edges of the network, so that costly Internet infrastructure upgrades are not necessary. An efficient way to prevent the Internet surge over the network for IoT is to push the application specific computation to the edge of the network, close to where the data is generated, so that large data can be eliminated before being delivered to the cloud. In this study, an event query language and processing environment is provided to process events from various devices. The query processing environment brings the application developers, sensor infrastructure providers and end users together. It uses boolean events as the streaming and processing units. This addresses the device heterogeneity and pushes the data-intense tasks to the edge of network.The second focus of the study is Video-on-Demand applications. A characteristic of VoD traffic is its high redundancy. Due to the demand on popular content, the same video traffic flows through Internet Service Provider's network as overlapping but separate streams. In previous studies on redundancy elimination, overlapping streams are merged into each other in link-level by receiving the packet only for the first stream, and re-using it for the subsequent duplicated streams. In this study, we significantly improve these techniques by introducing a merger-aware routing method.Our final focus is increasing utilization of Content Delivery Network (CDN) servers on the edge of network to reduce the long-distance traffic. The proposed system uses Software Defined Networks (SDN) to route adaptive video streaming clients to the best available CDN servers in terms of network availability. While performing the network assistance, the system does not reveal the video request information to the network provider, thus enabling privacy protection for encrypted streams. The request routing is performed in segment level for adaptive streaming. This enables to re-route the client to the best available CDN without an interruption if network conditions change during the stream.
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Date Issued: 2019
Identifier: CFE0007882, ucf:52774
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007882

Title: Decision-making for Vehicle Path Planning.
Creator: Xu, Jun, Turgut, Damla, Zhang, Shaojie, Zhang, Wei, Hasan, Samiul, University of Central Florida
Abstract / Description: This dissertation presents novel algorithms for vehicle path planning in scenarios where the environment changes. In these dynamic scenarios the path of the vehicle needs to adapt to changes in the real world. In these scenarios, higher performance paths can be achieved if we are able to predict the future state of the world, by learning the way it evolves from historical data. We are relying on recent advances in the field of deep learning and reinforcement learning to learn appropriate...
Show moreThis dissertation presents novel algorithms for vehicle path planning in scenarios where the environment changes. In these dynamic scenarios the path of the vehicle needs to adapt to changes in the real world. In these scenarios, higher performance paths can be achieved if we are able to predict the future state of the world, by learning the way it evolves from historical data. We are relying on recent advances in the field of deep learning and reinforcement learning to learn appropriate world models and path planning behaviors.There are many different practical applications that map to this model. In this dissertation we propose algorithms for two applications that are very different in domain but share important formal similarities: the scheduling of taxi services in a large city and tracking wild animals with an unmanned aerial vehicle.The first application models a centralized taxi dispatch center in a big city. It is a multivariate optimization problem for taxi time scheduling and path planning. The first goal here is to balance the taxi service demand and supply ratio in the city. The second goal is to minimize passenger waiting time and taxi idle driving distance. We design different learning models that capture taxi demand and destination distribution patterns from historical taxi data. The predictions are evaluated with real-world taxi trip records. The predicted taxi demand and destination is used to build a taxi dispatch model. The taxi assignment and re-balance is optimized by solving a Mixed Integer Programming (MIP) problem.The second application concerns animal monitoring using an unmanned aerial vehicle (UAV) to search and track wild animals in a large geographic area. We propose two different path planing approaches for the UAV. The first one is based on the UAV controller solving Markov decision process (MDP). The second algorithms relies on the past recorded animal appearances. We designed a learning model that captures animal appearance patterns and predicts the distribution of future animal appearances. We compare the proposed path planning approaches with traditional methods and evaluated them in terms of collected value of information (VoI), message delay and percentage of events collected.
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Date Issued: 2019
Identifier: CFE0007557, ucf:52606
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007557

Title: Two Ramsey-related Problems.
Creator: Zhang, Jingmei, Song, Zixia, Zhao, Yue, Martin, Heath, Turgut, Damla, University of Central Florida
Abstract / Description: Extremal combinatorics is one of the central branches of discrete mathematics and has experienced an impressive growth during the last few decades. It deals with the problem of determining or estimating the maximum or minimum possible size of a combinatorial structure which satisfies certain requirements. In this dissertation, we focus on studying the minimum number of edges of certain co-critical graphs. Given an integer r \geq 1 and graphs G, H_1, . . . , H_r, we write G \rightarrow (H_1, ....
Show moreExtremal combinatorics is one of the central branches of discrete mathematics and has experienced an impressive growth during the last few decades. It deals with the problem of determining or estimating the maximum or minimum possible size of a combinatorial structure which satisfies certain requirements. In this dissertation, we focus on studying the minimum number of edges of certain co-critical graphs. Given an integer r \geq 1 and graphs G, H_1, . . . , H_r, we write G \rightarrow (H_1, . . . , H_r) if every r-coloring of the edges of G contains a monochromatic copy of H_i in color i for some i \in {1, . . . , r}. A graph G is (H_1, . . . , H_r)-co-critical if G \nrightarrow (H_1, . . . , H_r), but G+uv \rightarrow (H_1, . . . , H_r) for every pair of non-adjacent vertices u, v in G. Motivated in part by Hanson and Toft's conjecture from 1987, we study the minimum number of edges over all (K_t,\mathcal{T}_k)-co-critical graphs on n vertices, where \mathcal{T}_k denotes the family of all trees on k vertices. We apply graph bootstrap percolation on a not necessarily K_t-saturated graph to prove that for all t \geq 4 and k \geq max{6, t}, there exists a constant c(t,k) such that, for all n \geq (t-1)(k-1)+1, if G is a (K_t,\mathcal{T}_k)-co-critical graph on n vertices, then e(G) \geq ((4t-9)/2+\lceil k/2 \rceil /2)n-c(t,k). We then show that this is asymptotically best possible for all sufficiently large n when t \in {4, 5} and k \geq 6. The method we developed may shed some light on solving Hanson and Toft's conjecture, which is wide open.We also study Ramsey numbers of even cycles and paths under Gallai colorings, where a Gallai coloring is a coloring of the edges of a complete graph without rainbow triangles, and a Gallai k-coloring is a Gallai coloring that uses at most k colors. Given an integer k \geq 1 and graphs H_1, . . . , H_k, the Gallai-Ramsey number GR(H_1, . . . , H_k) is the least integer n such that every Gallai k-coloring of the complete graph K_n contains a monochromatic copy of H_i in color i for some i \in {1, . . . , k}. We completely determine the exact values of GR(H_1, . . . , H_k) for all k \geq 2 when each H_i is a path or an even cycle on at most 13 vertices.
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Date Issued: 2019
Identifier: CFE0007745, ucf:52404
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007745

Title: Compiler Design of a Policy Specification Language for Conditional Gradual Release.
Creator: Kashyap Harinath, Manasa, Leavens, Gary, Turgut, Damla, Wang, Liqiang, University of Central Florida
Abstract / Description: Securing the confidentiality and integrity of information manipulated by computer software is an old yet increasingly important problem. Current software permission systems present on Android or iOS provide inadequate support for developing applications with secure information flow policies. To be useful, information flow control policies need to specify declassifications and the conditions under which declassification must occur. Having these declassifications scattered all over the program...
Show moreSecuring the confidentiality and integrity of information manipulated by computer software is an old yet increasingly important problem. Current software permission systems present on Android or iOS provide inadequate support for developing applications with secure information flow policies. To be useful, information flow control policies need to specify declassifications and the conditions under which declassification must occur. Having these declassifications scattered all over the program makes policies hard to find, which makes auditing difficult. To overcome these challenges, a policy specification language, 'Evidently' is discussed that allows one to specify information flow control policies separately from the program and which supports conditional gradual releases that can be automatically enforced. I discuss the Evidently grammar and modular semantics in detail. Finally, I discuss the implementational details of Evidently compiler within the Xtext language development environment and the implementation's enforcement of policies.
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Date Issued: 2018
Identifier: CFE0007205, ucf:52274
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007205

Title: Practical Dynamic Transactional Data Structures.
Creator: Laborde, Pierre, Dechev, Damian, Leavens, Gary, Turgut, Damla, Mucciolo, Eduardo, University of Central Florida
Abstract / Description: Multicore programming presents the challenge of synchronizing multiple threads.Traditionally, mutual exclusion locks are used to limit access to a shared resource to a single thread at a time.Whether this lock is applied to an entire data structure, or only a single element, the pitfalls of lock-based programming persist.Deadlock, livelock, starvation, and priority inversion are some of the hazards of lock-based programming that can be avoided by using non-blocking techniques.Non-blocking...
Show moreMulticore programming presents the challenge of synchronizing multiple threads.Traditionally, mutual exclusion locks are used to limit access to a shared resource to a single thread at a time.Whether this lock is applied to an entire data structure, or only a single element, the pitfalls of lock-based programming persist.Deadlock, livelock, starvation, and priority inversion are some of the hazards of lock-based programming that can be avoided by using non-blocking techniques.Non-blocking data structures allow scalable and thread-safe access to shared data by guaranteeing, at least, system-wide progress.In this work, we present the first wait-free hash map which allows a large number of threads to concurrently insert, get, and remove information.Wait-freedom means that all threads make progress in a finite amount of time --- an attribute that can be critical in real-time environments.We only use atomic operations that are provided by the hardware; therefore, our hash map can be utilized by a variety of data-intensive applications including those within the domains of embedded systems and supercomputers.The challenges of providing this guarantee make the design and implementation of wait-free objects difficult.As such, there are few wait-free data structures described in the literature; in particular, there are no wait-free hash maps.It often becomes necessary to sacrifice performance in order to achieve wait-freedom.However, our experimental evaluation shows that our hash map design is, on average, 7 times faster than a traditional blocking design.Our solution outperforms the best available alternative non-blocking designs in a large majority of cases, typically by a factor of 15 or higher.The main drawback of non-blocking data structures is that only one linearizable operation can be executed by each thread, at any one time.To overcome this limitation we present a framework for developing dynamic transactional data containers.Transactional containers are those that execute a sequence of operations atomically and in such a way that concurrent transactions appear to take effect in some sequential order.We take an existing algorithm that transforms non-blocking sets into static transactional versions (LFTT), and we modify it to support maps.We implement a non-blocking transactional hash map using this new approach.We continue to build on LFTT by implementing a lock-free vector using a methodology to allow LFTT to be compatible with non-linked data structures.A static transaction requires all operands and operations to be specified at compile-time, and no code may be executed between transactions.These limitations render static transactions impractical for most use cases.We modify LFTT to support dynamic transactions, and we enhance it with additional features.Dynamic transactions allow operands to be specified at runtime rather than compile-time, and threads can execute code between the data structure operations of a transaction.We build a framework for transforming non-blocking containers into dynamic transactional data structures, called Dynamic Transactional Transformation (DTT), and provide a library of novel transactional containers.Our library provides the wait-free progress guarantee and supports transactions among multiple data structures, whereas previous work on data structure transactions has been limited to operating on a single container.Our approach is 3 times faster than software transactional memory, and its performance matches its lock-free transactional counterpart.
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Date Issued: 2018
Identifier: CFE0007215, ucf:52212
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007215

Title: Specification and Runtime Checking of Timing Constraints in Safety Critical Java.
Creator: Haddad, Ghaith, Leavens, Gary, Turgut, Damla, Boloni, Ladislau, Nazzal, Dima, University of Central Florida
Abstract / Description: The Java platform is becoming a vital tool for developing real-time and safety-critical systems. Design patterns and the availability of Java libraries, both provide solutions to many known problems. Furthermore, the object-oriented nature of Java simplifies modular development of real-time systems. However, limitations of Java as a programming language for real-time systems are a notable obstacle to producing safe real-time systems. These limitations are found in the unpredictable execution...
Show moreThe Java platform is becoming a vital tool for developing real-time and safety-critical systems. Design patterns and the availability of Java libraries, both provide solutions to many known problems. Furthermore, the object-oriented nature of Java simplifies modular development of real-time systems. However, limitations of Java as a programming language for real-time systems are a notable obstacle to producing safe real-time systems. These limitations are found in the unpredictable execution model of the language, due to Java's garbage collector, and the lack of support for non-functional specification and verification tools. In this dissertation I introduce SafeJML, a specification language for support of functional and non-functional specifications, based on an implementation of a safety-critical Java platform and the Java Modeling Language (JML). This dissertation concentrates on techniques that enable specification and dynamic checking of timing constraints for some important Java features, including methods and subtyping. SafeJML and these dynamic checking techniques allow modular specification and checking of safety-critical systems, including those that use object-orientation and design patterns. Such coding techniques could have maintenance benefits for real-time and safety-critical software.
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Date Issued: 2012
Identifier: CFE0004542, ucf:49224
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004542

Title: Modeling Crowd Mobility and Communication in Wireless Networks.
Creator: Solmaz, Gurkan, Turgut, Damla, Bassiouni, Mostafa, Guha, Ratan, Goldiez, Brian, University of Central Florida
Abstract / Description: This dissertation presents contributions to the fields of mobility modeling, wireless sensor networks (WSNs) with mobile sinks, and opportunistic communication in theme parks. The two main directions of our contributions are human mobility models and strategies for the mobile sink positioning and communication in wireless networks.The first direction of the dissertation is related to human mobility modeling. Modeling the movement of human subjects is important to improve the performance of...
Show moreThis dissertation presents contributions to the fields of mobility modeling, wireless sensor networks (WSNs) with mobile sinks, and opportunistic communication in theme parks. The two main directions of our contributions are human mobility models and strategies for the mobile sink positioning and communication in wireless networks.The first direction of the dissertation is related to human mobility modeling. Modeling the movement of human subjects is important to improve the performance of wireless networks with human participants and the validation of such networks through simulations. The movements in areas such as theme parks follow specific patterns that are not taken into consideration by the general purpose mobility models. We develop two types of mobility models of theme park visitors. The first model represents the typical movement of visitors as they are visiting various attractions and landmarks of the park. The second model represents the movement of the visitors as they aim to evacuate the park after a natural or man-made disaster.The second direction focuses on the movement patterns of mobile sinks and their communication in responding to various events and incidents within the theme park. When an event occurs, the system needs to determine which mobile sink will respond to the event and its trajectory. The overall objective is to optimize the event coverage by minimizing the time needed for the chosen mobile sink to reach the incident area. We extend this work by considering the positioning problem of mobile sinks and preservation of the connected topology. We propose a new variant of p-center problem for optimal placement and communication of the mobile sinks. We provide a solution to this problem through collaborative event coverage of the WSNs with mobile sinks. Finally, we develop a network model with opportunistic communication for tracking the evacuation of theme park visitors during disasters. This model involves people with smartphones that store and carry messages. The mobile sinks are responsible for communicating with the smartphones and reaching out to the regions of the emergent events.
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Date Issued: 2015
Identifier: CFE0006005, ucf:51024
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006005

Title: Learning Dynamic Network Models for Complex Social Systems.
Creator: Hajibagheri, Alireza, Sukthankar, Gita, Turgut, Damla, Chatterjee, Mainak, Lakkaraju, Kiran, University of Central Florida
Abstract / Description: Human societies are inherently complex and highly dynamic, resulting in rapidly changing social networks, containing multiple types of dyadic interactions. Analyzing these time-varying multiplex networks with approaches developed for static, single layer networks often produces poor results. To address this problem, our approach is to explicitly learn the dynamics of these complex networks. This dissertation focuses on five problems: 1) learning link formation rates; 2) predicting changes in...
Show moreHuman societies are inherently complex and highly dynamic, resulting in rapidly changing social networks, containing multiple types of dyadic interactions. Analyzing these time-varying multiplex networks with approaches developed for static, single layer networks often produces poor results. To address this problem, our approach is to explicitly learn the dynamics of these complex networks. This dissertation focuses on five problems: 1) learning link formation rates; 2) predicting changes in community membership; 3) using time series to predict changes in network structure; 4) modeling coevolution patterns across network layers and 5) extracting information from negative layers of a multiplex network.To study these problems, we created a rich dataset extracted from observing social interactions in the massively multiplayer online game Travian. Most online social media platforms are optimized to support a limited range of social interactions, primarily focusing on communication and information sharing. In contrast, relations in massively-multiplayer online games (MMOGs) are often formed during the course of gameplay and evolve as the game progresses. To analyze the players' behavior, we constructed multiplex networks with link types for raid, communication, and trading.The contributions of this dissertation include 1) extensive experiments on the dynamics of networks formed from diverse social processes; 2) new game theoretic models for community detection in dynamic networks; 3) supervised and unsupervised methods for link prediction in multiplex coevolving networks for both positive and negative links. We demonstrate that our holistic approach for modeling network dynamics in coevolving, multiplex networks outperforms factored methods that separately consider temporal and cross-layer patterns.
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Date Issued: 2017
Identifier: CFE0006598, ucf:51306
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006598

Title: JML Template Generation.
Creator: Poojari, Kushal Raghav, Leavens, Gary, Turgut, Damla, Dechev, Damian, University of Central Florida
Abstract / Description: The Java Modeling Language (JML) is a behavioral interface specific language designed to specify Java modules (which are Java classes and interfaces). Specifications are used to describe the intended functionality without considering the way it is implemented. In JML, if a user wants to write specifications for a Java file, he or she must undertake several steps. To help automate the process of creating annotations for method specifications, a tool Jmlspec was created. Jmlspec generated a...
Show moreThe Java Modeling Language (JML) is a behavioral interface specific language designed to specify Java modules (which are Java classes and interfaces). Specifications are used to describe the intended functionality without considering the way it is implemented. In JML, if a user wants to write specifications for a Java file, he or she must undertake several steps. To help automate the process of creating annotations for method specifications, a tool Jmlspec was created. Jmlspec generated a file that refines the source file and has empty placeholders in which one can write specifications. Although Jmlspec worked with older versions of Java, it does not work with the current version of Java (Java 8). This thesis describes the implementation of a new version of the Jmlspec tool that is compatible with newest versions of Java. This tool will be more maintainable than the older version of Jmlspec and easier to extend.
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Date Issued: 2017
Identifier: CFE0006641, ucf:51228
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006641

Title: Towards Energy-Efficient and Reliable Computing: From Highly-Scaled CMOS Devices to Resistive Memories.
Creator: Salehi Mobarakeh, Soheil, DeMara, Ronald, Fan, Deliang, Turgut, Damla, University of Central Florida
Abstract / Description: The continuous increase in transistor density based on Moore's Law has led us to highly scaled Complementary Metal-Oxide Semiconductor (CMOS) technologies. These transistor-based process technologies offer improved density as well as a reduction in nominal supply voltage. An analysis regarding different aspects of 45nm and 15nm technologies, such as power consumption and cell area to compare these two technologies is proposed on an IEEE 754 Single Precision Floating-Point Unit implementation....
Show moreThe continuous increase in transistor density based on Moore's Law has led us to highly scaled Complementary Metal-Oxide Semiconductor (CMOS) technologies. These transistor-based process technologies offer improved density as well as a reduction in nominal supply voltage. An analysis regarding different aspects of 45nm and 15nm technologies, such as power consumption and cell area to compare these two technologies is proposed on an IEEE 754 Single Precision Floating-Point Unit implementation. Based on the results, using the 15nm technology offers 4-times less energy and 3-fold smaller footprint. New challenges also arise, such as relative proportion of leakage power in standby mode that can be addressed by post-CMOS technologies. Spin-Transfer Torque Random Access Memory (STT-MRAM) has been explored as a post-CMOS technology for embedded and data storage applications seeking non-volatility, near-zero standby energy, and high density. Towards attaining these objectives for practical implementations, various techniques to mitigate the specific reliability challenges associated with STT-MRAM elements are surveyed, classified, and assessed herein. Cost and suitability metrics assessed include the area of nanomagmetic and CMOS components per bit, access time and complexity, Sense Margin (SM), and energy or power consumption costs versus resiliency benefits. In an attempt to further improve the Process Variation (PV) immunity of the Sense Amplifiers (SAs), a new SA has been introduced called Adaptive Sense Amplifier (ASA). ASA can benefit from low Bit Error Rate (BER) and low Energy Delay Product (EDP) by combining the properties of two of the commonly used SAs, Pre-Charge Sense Amplifier (PCSA) and Separated Pre-Charge Sense Amplifier (SPCSA). ASA can operate in either PCSA or SPCSA mode based on the requirements of the circuit such as energy efficiency or reliability. Then, ASA is utilized to propose a novel approach to actually leverage the PV in Non-Volatile Memory (NVM) arrays using Self-Organized Sub-bank (SOS) design. SOS engages the preferred SA alternative based on the intrinsic as-built behavior of the resistive sensing timing margin to reduce the latency and power consumption while maintaining acceptable access time.
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Date Issued: 2016
Identifier: CFE0006493, ucf:51400
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006493

Title: Learning robotic manipulation from user demonstrations.
Creator: Rahmatizadeh, Rouhollah, Boloni, Ladislau, Turgut, Damla, Jha, Sumit Kumar, University of Central Florida
Abstract / Description: Personal robots that help disabled or elderly people in their activities of daily living need to be able to autonomously perform complex manipulation tasks. Traditional approaches to this problem employ task-specific controllers. However, these must to be designed by expert programmers, are focused on a single task, and will perform the task as programmed, not according to the preferences of the user. In this dissertation, we investigate methods that enable an assistive robot to learn to...
Show morePersonal robots that help disabled or elderly people in their activities of daily living need to be able to autonomously perform complex manipulation tasks. Traditional approaches to this problem employ task-specific controllers. However, these must to be designed by expert programmers, are focused on a single task, and will perform the task as programmed, not according to the preferences of the user. In this dissertation, we investigate methods that enable an assistive robot to learn to execute tasks as demonstrated by the user. First, we describe a learning from demonstration (LfD) method that learns assistive tasks that need to be adapted to the position and orientation of the user's head. Then we discuss a recurrent neural network controller that learns to generate movement trajectories for the end-effector of the robot arm to accomplish a task. The input to this controller is the pose of related objects and the current pose of the end-effector itself. Next, we discuss how to extract user preferences from the demonstration using reinforcement learning. Finally, we extend this controller to one that learns to observe images of the environment and generate joint movements for the robot to accomplish a desired task. We discuss several techniques that improve the performance of the controller and reduce the number of required demonstrations. One of this is multi-task learning: learning multiple tasks simultaneously with the same neural network. Another technique is to make the controller output one joint at a time-step, therefore to condition the prediction of each joint on the previous joints. We evaluate these controllers on a set of manipulation tasks and show that they can learn complex tasks, overcome failure, and attempt a task several times until they succeed.
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Date Issued: 2017
Identifier: CFE0006908, ucf:51686
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006908

Title: TryOpenJML - A Verily based web application for learning about the Java Modeling Language.
Creator: Deshpande, Tushar, Leavens, Gary, Turgut, Damla, Dechev, Damian, University of Central Florida
Abstract / Description: This thesis has a two-fold purpose. On the one hand, the web applications are an important part of life. On a day to day basis, from managing our heath care choices to banking, to connecting to a friend, almost everything is done through a web application. Development of these applications is also a very trend-driven domain. Numerous web frameworks are available today, but almost none has been created taking reliability into consideration. With the combination of application construction...
Show moreThis thesis has a two-fold purpose. On the one hand, the web applications are an important part of life. On a day to day basis, from managing our heath care choices to banking, to connecting to a friend, almost everything is done through a web application. Development of these applications is also a very trend-driven domain. Numerous web frameworks are available today, but almost none has been created taking reliability into consideration. With the combination of application construction recipes and static analysis, the Verily framework was created to build more reliable web applications.On the other hand, the goal of the Java Modeling Language (JML) has to be conveyed to the world. It is a language that can go hand in hand with existing code, having a wide range of tools that help build practical and effective designs. There are many tools available for JML: jmldoc for web pages, jmlunit for unit tests, jmlc for class files, etc. I will be using the tools for Runtime Assertion Checking (RAC) and Extended Static Checking (ESC). These checks warn about the possible runtime exceptions and assertion violations. The benefits of JML assert statements over Java assertions are that they support all JML features.The question that I am concerned with, in this thesis, is how the Verily Framework can contribute to the domain of web application development. Keeping this question in mind, my objective is to create a tutorial which will aid in learning about JML. The tutorial will let the potential users read and write JML specifications and use JML tools, explain basic JML semantics, and let them know where to go for help if they need more details.
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Date Issued: 2016
Identifier: CFE0006293, ucf:51614
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006293

Title: Design of a JMLdoclet for JMLdoc in OpenJML.
Creator: Donthala, Arjun Mitra Reddy, Leavens, Gary, Turgut, Damla, Jha, Sumit Kumar, University of Central Florida
Abstract / Description: The Java Modeling Language (JML) is a behavioral interface specification language designed for specifying Java classes and interfaces. OpenJML is a tool for processing JML specifications of Java programs. To facilitate viewing of these specifications in a user-friendly manner, a tool JMLdoc was created. The JMLdoc tool adds JML specifications to the usual Javadoc documentation. JMLdoc is an enhancement of Javadoc that adds to the Javadoc documentation the JML specifications that are present...
Show moreThe Java Modeling Language (JML) is a behavioral interface specification language designed for specifying Java classes and interfaces. OpenJML is a tool for processing JML specifications of Java programs. To facilitate viewing of these specifications in a user-friendly manner, a tool JMLdoc was created. The JMLdoc tool adds JML specifications to the usual Javadoc documentation. JMLdoc is an enhancement of Javadoc that adds to the Javadoc documentation the JML specifications that are present in the source code. The JMLdoc tool is a drop-in replacement for Javadoc, with additional functionality and additional options. The current design of JMLdoc uses the standard Javadoc's doclet. The current design lacks the provision for doclet extensions, unlike Javadoc. This thesis proposes a new design which is more aligned with the design of Javadoc and its provision for doclet extensions by implementing a JMLdoclet: a new doclet for OpenJML with support for JML elements. The new design makes JMLdoc independent of Javadoc's internals. This way maintenance is reduced as Javadoc evolves. The new design also combines specifications from inheritance and refinements and presents the complete JML specification to the user. This new doclet based design will be more maintainable and easier to extend.
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Date Issued: 2016
Identifier: CFE0006295, ucf:51596
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006295

JML (4)	+ -
Cognitive Radio (2)	+ -
OpenJML (2)	+ -
mobile sink (2)	+ -
multi-agent systems (2)	+ -

optimization (2)	+ -
routing (2)	+ -
simulation (2)	+ -
3D Positioning (1)	+ -
AUV (1)	+ -
Ad hoc Clustering Algortihm (1)	+ -
Adaptive Video Streaming (1)	+ -
Advanced Coding (1)	+ -
Advertising (1)	+ -
Animal tracking (1)	+ -
Argumentation (1)	+ -
Aspect Orientation (1)	+ -
Autonomous (1)	+ -
Bayesian and Machine Learning based Trust Models (1)	+ -
Big Data (1)	+ -
Checking (1)	+ -
Cognitive Radio Networks (1)	+ -
Complex Event Processing (1)	+ -
Conditional Gradual Release (1)	+ -
Content Delivery Networks (1)	+ -
Data analytics (1)	+ -
Datacenters (1)	+ -
Decision making (1)	+ -
Declassification (1)	+ -
Design by Contracts (1)	+ -

Turgut, Damla (42)	+ -
University of Central Florida (42)	+ -
Bassiouni, Mostafa (9)	+ -
Leavens, Gary (9)	+ -
Boloni, Ladislau (7)	+ -

Zou, Changchun (7)	+ -
Guha, Ratan (4)	+ -
Sukthankar, Gita (4)	+ -
Chatterjee, Mainak (3)	+ -
Dechev, Damian (3)	+ -
Garibay, Ivan (3)	+ -
Jha, Sumit (3)	+ -
Jha, Sumit Kumar (3)	+ -
Wang, Chung-Ching (3)	+ -
Wang, Jun (3)	+ -
Yuksel, Murat (3)	+ -
Behal, Aman (2)	+ -
DeMara, Ronald (2)	+ -
Lin, Mingjie (2)	+ -
Martin, Heath (2)	+ -
Pourmohammadi Fallah, Yaser (2)	+ -
Rahmatizadeh, Rouhollah (2)	+ -
Song, Zixia (2)	+ -
Wang, Liqiang (2)	+ -
Wei, Lei (2)	+ -
Wu, Annie (2)	+ -
Zhao, Yue (2)	+ -
Ahmad, Mohammad (1)	+ -
Akbas, Mustafa (1)	+ -
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