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- Title
- A PERFORMANCE COMPARISON OF CLUSTERING ALGORITHMS IN AD HOCNETWORKS.
- Creator
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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.
Show less - Date Issued
- 2006
- Identifier
- CFE0001314, ucf:47022
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001314
- Title
- Multiple-Case Study and Exploratory Analysis of the Implementation of Value-Added Teacher Performance Assessment on Eighth Grade Student Achievement in Ohio, Pennsylvania, and Tennessee.
- Creator
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Carter, James, Taylor, Rosemarye, Doherty, Walter, Hahs-Vaughn, Debbie, Gordon, William, University of Central Florida
- Abstract / Description
-
The goal of this research was to analyze the academic impact of the implementation of the Value Added Assessment Model. The researcher analyzed the Value Added Assessment Models in the three Value Added Assessment Model states that had implemented the Value Added Assessment Model for more than five years. Additionally, the research was done by analyzing the academic impact as measured by the eighth grade reading NAEP and the eighth grade mathematics NAEP. The researcher paired the three...
Show moreThe goal of this research was to analyze the academic impact of the implementation of the Value Added Assessment Model. The researcher analyzed the Value Added Assessment Models in the three Value Added Assessment Model states that had implemented the Value Added Assessment Model for more than five years. Additionally, the research was done by analyzing the academic impact as measured by the eighth grade reading NAEP and the eighth grade mathematics NAEP. The researcher paired the three states that had implemented Value Added Assessment Model for more than five years, with three demographically matched states that had not implemented Value Added Assessment Model. The states were matched as follows: Ohio (Value Added Assessment Model implementing state) with Michigan (non Value Added Assessment Model state), Pennsylvania (Value Added Assessment Model implementing state) with Virginia (non Value Added Assessment Model state) and Tennessee (Value Added Assessment Model implementing state) with Georgia (non Value Added Assessment Model state). The mean composite scale score in NAEP from the following categories of students were compared and analyzed: 1) All students 2) White students 3) Black students 4) National School Lunch Program Eligible Students 5) National School Lunch Program Ineligible Students 6) Exceptional Education students. The results of the study indicated that the impact of Value Added Assessment Model on academic impact as measured by the eighth grade reading NAEP and the eighth grade mathematics NAEP was negligible.
Show less - Date Issued
- 2014
- Identifier
- CFE0005468, ucf:52862
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005468
- Title
- IS ECONOMIC VALUE ADDED (EVA) THE BEST WAY TO ASSEMBLE A PORTFOLIO?.
- Creator
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Pataky, Tamas, Gilkeson, James, University of Central Florida
- Abstract / Description
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In search of a better investment metric, researchers began to study Economic Value Added, or EVA, which was introduced in 1991 by Stern Stewart & Co in their book, "The Quest for Value" (Turvey, 2000). Stern Stewart & Co devised EVA as a better alternative to evaluate investment projects within the corporate finance field, later to be considered for use as a performance metric for investor use. A wide array of multinational corporations, such as Coca-Cola, Briggs and Stratton, and AT&T...
Show moreIn search of a better investment metric, researchers began to study Economic Value Added, or EVA, which was introduced in 1991 by Stern Stewart & Co in their book, "The Quest for Value" (Turvey, 2000). Stern Stewart & Co devised EVA as a better alternative to evaluate investment projects within the corporate finance field, later to be considered for use as a performance metric for investor use. A wide array of multinational corporations, such as Coca-Cola, Briggs and Stratton, and AT&T adopted the EVA method, which led to EVA's worldwide acclaim. Several points in the study reveal that EVA does not offer less risk, higher returns, and more adaptability for an investor. In fact, EVA underperformed the traditional portfolio performance metrics in key measurements including mean returns, and confidence intervals. EVA is a difficult performance metric to calculate, with several complex components that can be calculated in several different ways such as NOPAT, cost of equity, and cost of debt. Any information that is inaccurate or lacking can significantly impact the outcomes. Traditional performance metrics, on the other hand, such as ROA, ROE, and E/P are simple to calculate with few components, and only one way to calculate them.
Show less - Date Issued
- 2012
- Identifier
- CFH0004289, ucf:44909
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0004289
- Title
- MITIGATING MISBEHAVIOR IN WIRELESS NETWORKS: A GAME THEORETIC APPROACH.
- Creator
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Wang, Wenjing, Chatterjee, Mainak, University of Central Florida
- Abstract / Description
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In a distributed wireless system, multiple network nodes behave cooperatively towards a common goal. Though such assumptions on cooperation are desirable (e.g., controlling the transmit power level, reducing interference for each other, revealing private information, adhering to network policies) for analyzing and modeling, certain nodes belonging to a real-world system have often shown to deviate. These nodes, known as misbehaving nodes, bring more challenges to the design of the wireless...
Show moreIn a distributed wireless system, multiple network nodes behave cooperatively towards a common goal. Though such assumptions on cooperation are desirable (e.g., controlling the transmit power level, reducing interference for each other, revealing private information, adhering to network policies) for analyzing and modeling, certain nodes belonging to a real-world system have often shown to deviate. These nodes, known as misbehaving nodes, bring more challenges to the design of the wireless network because the unreliable channel makes the actions of the nodes hidden from each other. In this dissertation, we analyze two types of misbehavior, namely, selfish noncooperation and malicious attacking. We apply game theoretic techniques to model the interactions among the nodes in the network. First, we consider a homogeneous unreliable channel and analyze the necessary and sufficient conditions to enforce cooperative packet forwarding among a node pair. We formulate an anti-collusion game and derive the conditions that achieve full cooperation when the non-cooperative nodes collude. In addition, we consider multi-hop communication with a heterogeneous channel model. We refine our game model as a hidden action game with imperfect private monitoring. A state machine based strategy is proposed to reach Nash Equilibrium. The strategy attains cooperative packet forwarding with heterogeneous channel and requires only partial and imperfect information. Furthermore, it also enforces cooperation in multi-hop packet forwarding. To tackle the malicious attacks, we use Bayesian game analysis to show the existence of equilibrium in the detection game and argue that it might not be profitable to isolate the malicious nodes upon detection. We propose the concept of "coexistence with malicious nodes" by proving the co-existence equilibrium and derive the conditions that achieve the equilibrium. This research is further accomplished by extensive simulation studies. Simulation results illustrate the properties of the games and the derived equilibria. The results validate our design philosophy and clearly indicate that the proposed game theoretic solutions can be effectively used to enforce cooperation and mitigate attacks.
Show less - Date Issued
- 2010
- Identifier
- CFE0003080, ucf:48294
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003080
- Title
- An analysis of the difference between assessed instructional practices, value-added measures, and learning gains of secondary reading teachers.
- Creator
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Fritz, Ronald, Taylor, Rosemarye, Baldwin, Lee, Doherty, Walter, Kennedy, Mary, University of Central Florida
- Abstract / Description
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The purpose of this study was to analyze the relationship that exists among instructional practice scores, value-added measures, and learning gains for the Large Urban School District (LUSD) among reading teachers in Grades 6-12 for the 2012-2013 school year. In addition, this study was also conducted to address the perceptions of secondary school principals and assistant principals regarding the relationship of the three variables and their relevance in making personnel decisions....
Show moreThe purpose of this study was to analyze the relationship that exists among instructional practice scores, value-added measures, and learning gains for the Large Urban School District (LUSD) among reading teachers in Grades 6-12 for the 2012-2013 school year. In addition, this study was also conducted to address the perceptions of secondary school principals and assistant principals regarding the relationship of the three variables and their relevance in making personnel decisions. Quantitative data were obtained from school district databases for observation scores, value-added measures, and standardized assessment achievement data to determine the relationship among the variables. In addition, a perception survey was completed by secondary school principals and assistant principals. With a sample size of 138, the survey yielded a return rate of 84%. The data were analyzed to determine actual relationships among instructional practice scores, value-added measures, and learning gains, as well as how the participants perceived each variable in isolation. The literature review supported the findings regarding the inflation of observation scores by school administrators. The only significant relationship (.48) existed between value-added measures and learning gains. Likewise, school leaders in the LUSD believed that their observations were important in analyzing the needs of their teachers and should be included in summative evaluations. Learning gains were supported by the participants more than instructional practice scores and value-added measures as evidence of effective instruction. The literature review revealed past program evaluation studies regarding the Florida Comprehensive Achievement Test (FCAT) as a valid measure for assessing grade level benchmarks. The information in this study is valuable and suggests that continued professional learning for school leaders regarding classroom observations to improve inter-rater reliability is needed. Likewise, school leaders would benefit from understanding the relationships that exist among instructional practice scores, value-added measures, and learning gains to drive conversations with teachers regarding rigorous instruction.
Show less - Date Issued
- 2014
- Identifier
- CFE0005494, ucf:50362
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005494
- Title
- VOICE ONSET TIME PRODUCTION IN INDIVIDUALS WTH ALZHEIMER'S DISEASE.
- Creator
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Baker, Julie Baker, Ryalls, Jack, University of Central Florida
- Abstract / Description
-
In the present study, voice onset time (VOT) measurements were compared between a group of individuals with moderate Alzheimer's disease (AD) and a group of healthy age- and gender-matched peers. Participants read a list of consonant-vowel-consonant (CVC) words, which included the six stop consonants. Recordings were gathered and digitized. The VOT measurements were made from oscillographic displays obtained from the Brown Laboratory Interactive Speech System (BLISS) implemented on an IBM...
Show moreIn the present study, voice onset time (VOT) measurements were compared between a group of individuals with moderate Alzheimer's disease (AD) and a group of healthy age- and gender-matched peers. Participants read a list of consonant-vowel-consonant (CVC) words, which included the six stop consonants. Recordings were gathered and digitized. The VOT measurements were made from oscillographic displays obtained from the Brown Laboratory Interactive Speech System (BLISS) implemented on an IBM-compatible computer. VOT measures for the participants' six stop consonant productions were subjected to statistical analysis. The results of the study indicated that differences in VOT values were not statistically significant in the speakers with Alzheimer's disease from the normal control speakers.
Show less - Date Issued
- 2006
- Identifier
- CFE0001269, ucf:46918
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001269
- Title
- COLLABORATION ENFORCEMENT IN MOBILE AD HOC NETWORKS.
- Creator
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Jiang, Ning, Hua, Kien, University of Central Florida
- Abstract / Description
-
Mobile Ad hoc NETworks (MANETs) have attracted great research interest in recent years. Among many issues, lack of motivation for participating nodes to collaborate forms a major obstacle to the adoption of MANETs. Many contemporary collaboration enforcement techniques employ reputation mechanisms for nodes to avoid and penalize malicious participants. Reputation information is propagated among participants and updated based on complicated trust relationships to thwart false accusation of...
Show moreMobile Ad hoc NETworks (MANETs) have attracted great research interest in recent years. Among many issues, lack of motivation for participating nodes to collaborate forms a major obstacle to the adoption of MANETs. Many contemporary collaboration enforcement techniques employ reputation mechanisms for nodes to avoid and penalize malicious participants. Reputation information is propagated among participants and updated based on complicated trust relationships to thwart false accusation of benign nodes. The aforementioned strategy suffers from low scalability and is likely to be exploited by adversaries. To address these problems, we first propose a finite state model. With this technique, no reputation information is propagated in the network and malicious nodes cannot cause false penalty to benign hosts. Misbehaving node detection is performed on-demand; and malicious node punishment and avoidance are accomplished by only maintaining reputation information within neighboring nodes. This scheme, however, requires that each node equip with a tamper-proof hardware. In the second technique, no such restriction applies. Participating nodes classify their one-hop neighbors through direct observation and misbehaving nodes are penalized within their localities. Data packets are dynamically rerouted to circumvent selfish nodes. In both schemes, overall network performance is greatly enhanced. Our approach significantly simplifies the collaboration enforcement process, incurs low overhead, and is robust against various malicious behaviors. Simulation results based on different system configurations indicate that the proposed technique can significantly improve network performance with very low communication cost.
Show less - Date Issued
- 2006
- Identifier
- CFE0001047, ucf:46820
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001047
- Title
- Scalable Network Design and Management with Decentralized Software-defined Networking.
- Creator
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Atwal, Kuldip Singh, Bassiouni, Mostafa, Fu, Xinwen, Zou, Changchun, Deo, Narsingh, University of Central Florida
- Abstract / Description
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Network softwarization is among the most significant innovations of computer networks in the last few decades. The lack of uniform and programmable interfaces for network management led to the design of OpenFlow protocol for the university campuses and enterprise networks. This breakthrough coupled with other similar efforts led to an emergence of two complementary but independent paradigms called software-defined networking (SDN) and network function virtualization (NFV). As of this writing,...
Show moreNetwork softwarization is among the most significant innovations of computer networks in the last few decades. The lack of uniform and programmable interfaces for network management led to the design of OpenFlow protocol for the university campuses and enterprise networks. This breakthrough coupled with other similar efforts led to an emergence of two complementary but independent paradigms called software-defined networking (SDN) and network function virtualization (NFV). As of this writing, these paradigms are becoming the de-facto norms of wired and wireless networks alike. This dissertation mainly addresses the scalability aspect of SDN for multiple network types. Although centralized control and separation of control and data planes play a pivotal role for ease of network management, these concepts bring in many challenges as well. Scalability is among the most crucial challenges due to the unprecedented growth of computer networks in the past few years. Therefore, we strive to grapple with this problem in diverse networking scenarios and propose novel solutions by harnessing capabilities provided by SDN and other related technologies. Specifically, we present the techniques to deploy SDN at the Internet scale and to extend the concepts of softwarization for mobile access networks and vehicular networks. Multiple optimizations are employed to mitigate latency and other overheads that contribute to achieve performance gains. Additionally, by taking care of sparse connectivity and high mobility, the intrinsic constraints of centralization for wireless ad-hoc networks are addressed in a systematic manner. The state-of-the-art virtualization techniques are coupled with cloud computing methods to exploit the potential of softwarization in general and SDN in particular. Finally, by tapping into the capabilities of machine learning techniques, an SDN-based solution is proposed that inches closer towards the longstanding goal of self-driving networks. Extensive experiments performed on a large-scale testbed corroborates effectiveness of our approaches.
Show less - Date Issued
- 2019
- Identifier
- CFE0007600, ucf:52543
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007600
- Title
- A Framework for Measuring the Value-Added of Knowledge Processes with Analysis of Process Interactions and Dynamics.
- Creator
-
Cintron, Jose, Rabelo, Luis, Elshennawy, Ahmad, Thompson, William, Ajayi, Richard, University of Central Florida
- Abstract / Description
-
The most known and widely used methods use cash flows and tangible assets to measure the impact of investments in the organization's outputs. But in the last decade many newer organizations whose outputs are heavily dependent on information technology utilize knowledge as their main asset. These organizations' market values lie on the knowledge of its employees and their technological capabilities. In the current technology-based business landscape the value added by assets utilized for...
Show moreThe most known and widely used methods use cash flows and tangible assets to measure the impact of investments in the organization's outputs. But in the last decade many newer organizations whose outputs are heavily dependent on information technology utilize knowledge as their main asset. These organizations' market values lie on the knowledge of its employees and their technological capabilities. In the current technology-based business landscape the value added by assets utilized for generation of outputs cannot be appropriately measured and managed without considering the role that intangible assets and knowledge play in executing processes. The analysis of processes for comparison and decision making based on intangible value added can be accomplished using the knowledge required to execute processes. The measurement of value added by knowledge can provide a more realistic framework for analysis of processes where traditional cost methods are not appropriate, enabling managers to better allocate and control knowledge-based processes. Further consideration of interactions and complexity between proposed process alternatives can yield answers about where and when investments can improve value-added while dynamically providing higher returns on investment.
Show less - Date Issued
- 2013
- Identifier
- CFE0004983, ucf:49585
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004983
- Title
- A Priori Analysis of Error and Bias in Value-Added Models.
- Creator
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Lavery, Matthew, Hahs-Vaughn, Debbie, Sivo, Stephen, Bai, Haiyan, Amrein-Beardsley, Audrey, University of Central Florida
- Abstract / Description
-
Over the past 20 years, value-added models (VAMs) have become increasingly popular in educational assessment and accountability policies because of the sophisticated statistical controls these models use to purportedly isolate the effect of a single teacher on the learning gains of his or her students. The present research uses a Monte Carlo simulation study design in order to investigate whether VAMs are able to provide accurate estimates of teacher effectiveness when all assumptions are met...
Show moreOver the past 20 years, value-added models (VAMs) have become increasingly popular in educational assessment and accountability policies because of the sophisticated statistical controls these models use to purportedly isolate the effect of a single teacher on the learning gains of his or her students. The present research uses a Monte Carlo simulation study design in order to investigate whether VAMs are able to provide accurate estimates of teacher effectiveness when all assumptions are met and to determine how robust the models are to endogenous peer effects and nonrandom assignment of students to classroom. The researcher generates three years of simulated achievement data for 18,750 students taught by 125 teachers, and analyzes this data with a linear mixed model similar to the SAS(&)#174; EVAAS(&)#174; Multivariate Response Model (MRM; M1), a basic covariate adjustment model (M2), and variations on these models designed to estimate random classroom effects. Findings indicate that the modified EVAAS may be too computationally onerous to be of practical use, and that modified covariate adjustment models do not perform significantly differently than the basic covariate adjustment model. When all assumptions are met, M1 is more accurate than M2, but both models perform reasonably well, misclassifying fewer than 5% of teachers on average. M1 is more robust to endogenous peer effects than M2, however both models misclassified more teachers than when all assumptions are met. M2 is more robust to nonrandom assignment of students than M1. Assigning teachers a balanced schedule of nonrandom classes with low, medium, and high prior achievement seemed to mitigate the problems that nonrandom assignment caused for M1, but made M2 less accurate. Implications for practice and future research are discussed.
Show less - Date Issued
- 2016
- Identifier
- CFE0006344, ucf:51568
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006344
- Title
- A Study of The Marzano Teacher Evaluation Model and Student Achievement at 24 Elementary Schools In A Large Suburban School District In Central Florida.
- Creator
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Flowers, Amy, Murray, Kenneth, Doherty, Walter, Murray, Barbara, Baldwin, Gordon, University of Central Florida
- Abstract / Description
-
The focus of this research was to examine the initial year of implementation of the Marzano Teacher Evaluation Model and iObservation(&)#174; tool (Learning Sciences International, 2012) as it related to student achievement in the School District of Osceola County, Florida and to determine if the Marzano model improved the ability to determine teacher effectiveness with more accuracy than previous models of teacher evaluation used in the school district. Twelve research questions guided this...
Show moreThe focus of this research was to examine the initial year of implementation of the Marzano Teacher Evaluation Model and iObservation(&)#174; tool (Learning Sciences International, 2012) as it related to student achievement in the School District of Osceola County, Florida and to determine if the Marzano model improved the ability to determine teacher effectiveness with more accuracy than previous models of teacher evaluation used in the school district. Twelve research questions guided this study concerning the relationship and predictability between the variables of teacher instructional practice scores, number of observations reported in the iObservation(&)#174; tool, and student achievement in Grades 3-5 using reading and mathematics FCAT 2.0 DSS scores.Linear Regression analysis suggested that for Grade 3 reading and mathematics the instructional practice mean had statistical significance in predicting performance and was a strong predictor of Grade 3 FCAT reading and mathematics performance. Linear Regression analysis suggested that for Grade 3 reading and mathematics the instructional practice mean had statistical significance in predicting performance and was a strong predictor of Grade 3 FCAT reading and mathematics performance. Linear Regression analysis further suggested no statistical significance or predictability for Grades 4, 5 for instructional practice mean and Grades 3,4,5 for observation mean related to FCAT reading and mathematics performance. Caution should be used when attempting to interpret these findings, as this study was based solely on initial year implementation data. Implications for practice are also discussed in this study.
Show less - Date Issued
- 2013
- Identifier
- CFE0004841, ucf:49711
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004841
- Title
- CONNECTIONLESS APPROACH A LOCALIZED SCHEME TO MOBILE AD HOC NETWORKS.
- Creator
-
Ho, Yao, Hua, Kien, University of Central Florida
- Abstract / Description
-
According to a Gartner Group (www.gartner.com) report in September 2008, the worldwide telecommunications market is on pace to reach $2 trillion in 2008. Gartner predicts that by 2012, the ratio of mobile to fixed connections will exceed 4-to-1. The North American mobile data market grew to 141.1 million connections in 2007, with a compound annual growth rate of 41.7 percent. It is believed that a large portion will be ad hoc and multi-hop connections, which will open many opportunities for...
Show moreAccording to a Gartner Group (www.gartner.com) report in September 2008, the worldwide telecommunications market is on pace to reach $2 trillion in 2008. Gartner predicts that by 2012, the ratio of mobile to fixed connections will exceed 4-to-1. The North American mobile data market grew to 141.1 million connections in 2007, with a compound annual growth rate of 41.7 percent. It is believed that a large portion will be ad hoc and multi-hop connections, which will open many opportunities for Mobile Ad hoc NETwork (MANET) applications and Wireless Mesh Network (WMN) applications. A MANET is a self-organizing multi-hop wireless network where all nodes participate in the routing and data forwarding process. Such a network can be easily deployed in situations where no base station is available, and a network must be build spontaneously. In applications such as battlefield communications, national crises, disaster recovery, and sensor deployment, a wired network is not available and ad hoc networks provide the only feasible means of communications and information access. Ad hoc networks have also become commonplace for gaming, conferencing, electronic classrooms, and particularly vehicle-to-vehicle communications. A Wireless mash network (WMN) is collection of mesh clients and mesh nodes (routers), with mesh nodes forming the backbone of the network and providing connection to the Internet and other network. Their rapid deployment and ease of maintenance are suitable for on-demand network such as disaster recovery, homeland security, convention centers, hard-to-wire buildings and unfriendly terrains. One important problem with MANET is the routing protocol that needs to work well not just with a small network, but also sustain efficiency and scalability as the network gets expanded and the application transmits data in greater volume. In such an environment, mobility, channel error, and congestion are the main causes for packet loss. Due to mobility of mobile hosts, addressing frequent and unpredictable topology changes is fundamental to MANET research. Two general approaches have been considered: connection-oriented approach and connectionless-oriented approach. In the former, the emphasis is on how to reconnect quickly with low overhead when a broken link occurs. Examples of this approach includes , , , , , , , , , and . In contrast, connectionless-oriented approach focuses on minimizing the occurrence of broken links. We proposed one such scheme called Connectionless Approach (CLA) and . In CLA, the network area is divided into non-overlapping grid cells, each serving as a virtual router. Any physical router (i.e., mobile host), currently inside a virtual router, can help forward the data packet to the next virtual router along the virtual link. This process is repeated until the packet reaches its final destination. Since a virtual link is based on virtual routers which do not move, it is much more robust than physical links used in the connection-oriented techniques. Simulation results in our previous works and , based on GloMoSim , indicate that CLA performs significantly better than connection-oriented techniques (i.e., AODV, DSR, LAR, GRID, TMNR, and GPSR). The contribution of this work consists of investigating and developing new Connectionless-Oriented Approach for Mobile Ad Hoc Network. Two of the greatest impacts of this research are as follows. First, the new approach is targeted towards robustly support high mobility and large scale environment which has been adapted for vehicle-to-vehicle environment in . Second, the detailed simulations which compare eight representative routing protocols, namely AODV, DSR, LAR, GRID, TMNR, GPSR, CBF, and CLA, under high-mobility environments. As many important emergent applications of the technology involved high-mobility nodes, very little is known about the existing routing methods perform relative to each other in high-mobility environments. The simulation results provide insight into ad hoc routing protocols and offer guidelines for mobile ad hoc network applications. Next, we enhanced and extend the connectionless-oriented approach. The current connectionless-oriented approach, however, may suffer from packet drops since traffic congestion is not considered in the packet forwarding policy. We address this weakness by considering the connectionless-oriented approach with a collision avoidance routing technique. After that, we investigate techniques to enforce collaboration among mobile devices in supporting the virtual router functionality. Many works have been published to combat such problem - misbehaving nodes are detected and a routing algorithm is employed to avoid and penalize misbehaving nodes. These techniques, however, cannot be applied to the connectionless-oriented approach since any node in the general direction towards the destination node can potentially help forward the data packets. To address the security and cooperation issues for connectionless-oriented approach, we introduce a cooperation enforcement technique called 3CE (3-Counter Enforcement). In addition, wireless mesh networks have become increasingly popular in recent years. Wireless mash network (WMNs) are collection of mesh clients and mesh nodes (routers), with mesh nodes forming the backbone of the network and providing connection to the Internet and other network. We propose a paradigm that combines virtual routers and mesh nodes to create a hybrid network call VR-Mesh Network. This hybrid network can reduce number of mesh node needed without decrease the performance of the network.
Show less - Date Issued
- 2009
- Identifier
- CFE0002742, ucf:48146
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002742
- Title
- MODELING, DESIGN AND EVALUATION OF NETWORKING SYSTEMS AND PROTOCOLS THROUGH SIMULATION.
- Creator
-
Lacks, Daniel, Kocak, Taskin, University of Central Florida
- Abstract / Description
-
Computer modeling and simulation is a practical way to design and test a system without actually having to build it. Simulation has many benefits which apply to many different domains: it reduces costs creating different prototypes for mechanical engineers, increases the safety of chemical engineers exposed to dangerous chemicals, speeds up the time to model physical reactions, and trains soldiers to prepare for battle. The motivation behind this work is to build a common software framework...
Show moreComputer modeling and simulation is a practical way to design and test a system without actually having to build it. Simulation has many benefits which apply to many different domains: it reduces costs creating different prototypes for mechanical engineers, increases the safety of chemical engineers exposed to dangerous chemicals, speeds up the time to model physical reactions, and trains soldiers to prepare for battle. The motivation behind this work is to build a common software framework that can be used to create new networking simulators on top of an HLA-based federation for distributed simulation. The goals are to model and simulate networking architectures and protocols by developing a common underlying simulation infrastructure and to reduce the time a developer has to learn the semantics of message passing and time management to free more time for experimentation and data collection and reporting. This is accomplished by evolving the simulation engine through three different applications that model three different types of network protocols. Computer networking is a good candidate for simulation because of the Internet's rapid growth that has spawned off the need for new protocols and algorithms and the desire for a common infrastructure to model these protocols and algorithms. One simulation, the 3DInterconnect simulator, simulates data transmitting through a hardware k-array n-cube network interconnect. Performance results show that k-array n-cube topologies can sustain higher traffic load than the currently used interconnects. The second simulator, Cluster Leader Logic Algorithm Simulator, simulates an ad-hoc wireless routing protocol that uses a data distribution methodology based on the GPS-QHRA routing protocol. CLL algorithm can realize a maximum of 45% power savings and maximum 25% reduced queuing delay compared to GPS-QHRA. The third simulator simulates a grid resource discovery protocol for helping Virtual Organizations to find resource on a grid network to compute or store data on. Results show that worst-case 99.43% of the discovery messages are able to find a resource provider to use for computation. The simulation engine was then built to perform basic HLA operations. Results show successful HLA functions including creating, joining, and resigning from a federation, time management, and event publication and subscription.
Show less - Date Issued
- 2007
- Identifier
- CFE0001887, ucf:47399
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001887
- Title
- AN INTERACTIVE DISTRIBUTED SIMULATION FRAMEWORK WITH APPLICATION TO WIRELESS NETWORKS AND INTRUSION DETECTION.
- Creator
-
Kachirski, Oleg, Guha, Ratan, University of Central Florida
- Abstract / Description
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In this dissertation, we describe the portable, open-source distributed simulation framework (WINDS) targeting simulations of wireless network infrastructures that we have developed. We present the simulation framework which uses modular architecture and apply the framework to studies of mobility pattern effects, routing and intrusion detection mechanisms in simulations of large-scale wireless ad hoc, infrastructure, and totally mobile networks. The distributed simulations within the...
Show moreIn this dissertation, we describe the portable, open-source distributed simulation framework (WINDS) targeting simulations of wireless network infrastructures that we have developed. We present the simulation framework which uses modular architecture and apply the framework to studies of mobility pattern effects, routing and intrusion detection mechanisms in simulations of large-scale wireless ad hoc, infrastructure, and totally mobile networks. The distributed simulations within the framework execute seamlessly and transparently to the user on a symmetric multiprocessor cluster computer or a network of computers with no modifications to the code or user objects. A visual graphical interface precisely depicts simulation object states and interactions throughout the simulation execution, giving the user full control over the simulation in real time. The network configuration is detected by the framework, and communication latency is taken into consideration when dynamically adjusting the simulation clock, allowing the simulation to run on a heterogeneous computing system. The simulation framework is easily extensible to multi-cluster systems and computing grids. An entire simulation system can be constructed in a short time, utilizing user-created and supplied simulation components, including mobile nodes, base stations, routing algorithms, traffic patterns and other objects. These objects are automatically compiled and loaded by the simulation system, and are available for dynamic simulation injection at runtime. Using our distributed simulation framework, we have studied modern intrusion detection systems (IDS) and assessed applicability of existing intrusion detection techniques to wireless networks. We have developed a mobile agent-based IDS targeting mobile wireless networks, and introduced load-balancing optimizations aimed at limited-resource systems to improve intrusion detection performance. Packet-based monitoring agents of our IDS employ a CASE-based reasoner engine that performs fast lookups of network packets in the existing SNORT-based intrusion rule-set. Experiments were performed using the intrusion data from MIT Lincoln Laboratories studies, and executed on a cluster computer utilizing our distributed simulation system.
Show less - Date Issued
- 2005
- Identifier
- CFE0000642, ucf:46545
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000642
- Title
- Health Literacy Intervention to Influence Choices Made by Students in a Title I School Who Receive Free Lunch.
- Creator
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Kent, Melissa, Levin, Judith, Quelly, Susan, Szente, Judit, University of Central Florida
- Abstract / Description
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This study seeks to influence choices made by Kindergarten students in a Title I school who receive free breakfast and lunch through a health literacy intervention with the intent of decreasing daily added sugar consumption. Fruit and milk choices, either with naturally occurring sugar (NOS) or added sugar (AS), were recorded for 70 Kindergarten students among six classes in a Title I school for ten days before a four-week health literacy intervention. Three of the classes were randomly...
Show moreThis study seeks to influence choices made by Kindergarten students in a Title I school who receive free breakfast and lunch through a health literacy intervention with the intent of decreasing daily added sugar consumption. Fruit and milk choices, either with naturally occurring sugar (NOS) or added sugar (AS), were recorded for 70 Kindergarten students among six classes in a Title I school for ten days before a four-week health literacy intervention. Three of the classes were randomly selected to learn about 'sometimes' and 'anytime' choices through the Healthy Habits for Life curriculum delivered by representatives from Nemours Children's Hospital. Following the intervention, milk and fruit choices were recorded for ten more school days to determine differences among the control and intervention groups. Pearson Chi Square test results concluded that the health literacy intervention lead to statistically significant improvements in milk choices for the intervention group, but fruit choices were inconclusive due to inconsistencies in significance. Hierarchical loglinear analyses were run to determine if there was a difference in response to intervention between male and female students, and the results indicated that the effectiveness of the intervention was not moderated by gender. The success of this intervention for milk choices will help students who receive free school breakfast and lunch to decrease their daily consumption of added sugars, and additional research needs to be done to help students make choices that will further decrease their daily added sugar consumption.
Show less - Date Issued
- 2019
- Identifier
- CFE0007662, ucf:52466
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007662
- Title
- Virtual Router Approach for Wireless Ad Hoc Networks.
- Creator
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Ho, Ai, Hua, Kien, Guha, Ratan, Moshell, Jack, Zou, Changchun, Wang, Ching, University of Central Florida
- Abstract / Description
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Wireless networks have become increasingly popular in recent years. There are two variations of mobile wireless networks: infrastructure mobile networks and infrastructureless mobile networks. The latter are also known as mobile ad hoc network (MANET). MANETs have no fixed routers. Instead, mobile nodes function as relay nodes or routers, which discover and maintain communication connections between source nodes and destination nodes for various data transmission sessions. In other words, an...
Show moreWireless networks have become increasingly popular in recent years. There are two variations of mobile wireless networks: infrastructure mobile networks and infrastructureless mobile networks. The latter are also known as mobile ad hoc network (MANET). MANETs have no fixed routers. Instead, mobile nodes function as relay nodes or routers, which discover and maintain communication connections between source nodes and destination nodes for various data transmission sessions. In other words, an MANET is a self-organizing multi-hop wireless network in which all nodes within a given geographical area participate in the routing and data forwarding process. Such networks are scalable and self-healing. They support mobile applications where an infrastructure is either not available (e.g., rescue operations and underground networks) or not desirable (e.g., harsh industrial environments).In many ad hoc networks such as vehicular networks, links among nodes change constantly and rapidly due to high node speed. Maintaining communication links of an established communication path that extends between source and destination nodes is a significant challenge in mobile ad hoc networks due to movement of the mobile nodes. In particular, such communication links are often broken under a high mobility environment. Communication links can also be broken by obstacles such as buildings in a street environment that block radio signal. In a street environment, obstacles and fast moving nodes result in a very short window of communication between nodes on different streets. Although a new communication route can be established when a break in the communication path occurs, repeatedly reestablishing new routes incurs delay and substantial overhead. To address this limitation, we introduce the Virtual Router abstraction in this dissertation. A virtual router is a dynamically-created logical router that is associated with a particular geographical area. Its routing functionality is provided by the physical nodes (i.e., mobile devices) currently within the geographical region served by the virtual router. These physical nodes take turns in forwarding data packets for the virtual router. In this environment, data packets are transmitted from a source node to a destination node over a series of virtual routers. Since virtual routers do not move, this scheme is much less susceptible to node mobility. There can be two virtual router approaches: Static Virtual Router (SVR) and Dynamic Virtual Router (DVR). In SVR, the virtual routers are predetermined and shared by all communication sessions over time. This scheme requires each mobile node to have a map of the virtual routers, and use a global positioning system (GPS) to determine if the node is within the geographical region of a given router. DVR is different from SVR with the following distinctions: (1) virtual routers are dynamically created for each communication sessions as needed, and deprecated after their use; (2) mobile nodes do not need to have a GPS; and (3) mobile nodes do not need to know whereabouts of the virtual routers.In this dissertation, we apply Virtual Router approach to address mobility challenges in routing data. We first propose a data routing protocol that uses SVR to overcome the extreme fast topology change in a street environment. We then propose a routing protocol that does not require node locations by adapting a DVR approach. We also explore how the Virtual Router Approach can reduce the overhead associated with initial route or location requests used by many existing routing protocols to find a destination. An initial request for a destination is expensive because all the nodes need to be reached to locate the destination. We propose two broadcast protocols; one in an open terrain environment and the other in a street environment. Both broadcast protocols apply SVR. We provide simulation results to demonstrate the effectiveness of the proposed protocols in handling high mobility. They show Virtual Router approach can achieve several times better performance than traditional routing and broadcast approach based on physical routers (i.e., relay nodes).
Show less - Date Issued
- 2011
- Identifier
- CFE0004119, ucf:49090
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004119
- Title
- An Investigation of Low Performing Central Florida Teacher Evaluation Feedback and Improvement Plans as Related to Value-Added Model Scores and Instructional Practice Scores.
- Creator
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Butler, Tara, Murray, Barbara, Doherty, Walter, Murray, Kenneth, Baldwin, Lee, Hutchinson, Cynthia, University of Central Florida
- Abstract / Description
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The purpose of this study was to determine if low performing Central Florida teachers, according to Florida VAM scores, had related instructional practice evaluations that were being used to determine placement on improvement plans in the 2013-14 school year. Additionally, the feedback held within the instructional practice evaluations was analyzed to discover the levels of feedback most frequently rendered by administrative evaluators to the lowest performing teachers. Deidentified data from...
Show moreThe purpose of this study was to determine if low performing Central Florida teachers, according to Florida VAM scores, had related instructional practice evaluations that were being used to determine placement on improvement plans in the 2013-14 school year. Additionally, the feedback held within the instructional practice evaluations was analyzed to discover the levels of feedback most frequently rendered by administrative evaluators to the lowest performing teachers. Deidentified data from a population of 528 Central Florida teacher evaluations and improvement plans within the lowest 10% of VAM scores for the 2013-14 school year were gathered from a Florida Department of Education database and public record requests. Data were analyzed to determine if any significant relationship existed between VAM scores and instructional practice scores. A very weak relationship existed between these two variables. Tenured teachers were rated significantly more favorably on summative instructional practice evaluations than nontenured teachers. Within the population, fewer than 1% of low-performing teachers (two total) were prescribed an improvement plan, regardless of tenure or nontenure status. Finally, evaluation feedback was largely low-level without reference to student growth or achievement. Evidence of administrative barriers within the three dimensions of individual conflict avoidance, bureaucratic procedural interferences, and administrative procedural faults were inferred from the literature and subsequent findings. To improve upon the current evaluation system, administrators must be aware of, and well-prepared for the demands of evaluating, remediating, and providing feedback to teaching professionals relative to student achievement and growth in a manner that is simultaneously respectful, candid, fair, timely, and actionable.
Show less - Date Issued
- 2017
- Identifier
- CFE0006937, ucf:51677
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006937
- Title
- Scalable Map Information Dissemination for Connected and Automated Vehicle Systems.
- Creator
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Gani, S M Osman, Pourmohammadi Fallah, Yaser, Vosoughi, Azadeh, Yuksel, Murat, Chatterjee, Mainak, Hasan, Samiul, University of Central Florida
- Abstract / Description
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Situational awareness in connected and automated vehicle (CAV) systems becomes particularly challenging in the presence of non-line of sight objects and/or objects beyond the sensing range of local onboard sensors. Despite the fact that fully autonomous driving requires the use of multiple redundant sensor systems, primarily including camera, radar, and LiDAR, the non-line of sight object detection problem still persists due to the inherent limitations of those sensing techniques. To tackle...
Show moreSituational awareness in connected and automated vehicle (CAV) systems becomes particularly challenging in the presence of non-line of sight objects and/or objects beyond the sensing range of local onboard sensors. Despite the fact that fully autonomous driving requires the use of multiple redundant sensor systems, primarily including camera, radar, and LiDAR, the non-line of sight object detection problem still persists due to the inherent limitations of those sensing techniques. To tackle this challenge, the inter-vehicle communication system is envisioned that allows vehicles to exchange self-status updates aiming to extend their effective field of view and thus compensate for the limitations of the vehicle tracking subsystem that relies substantially on onboard sensing devices. Tracking capability in such systems can be further improved through the cooperative sharing of locally created map data instead of transmitting only self-update messages containing core basic safety message (BSM) data. In the cooperative sharing of safety messages, it is imperative to have a scalable communication protocol to ensure optimal use of the communication channel. This dissertation contributes to the analysis of the scalability issue in vehicle-to-everything (V2X) communication and then addresses the range issue of situational awareness in CAV systems by proposing a content-adaptive V2X communication architecture. To that end, we first analyze the BSM scheduling protocol standardized in the SAE J2945/1 and present large-scale scalability results obtained from a high-fidelity simulation platform to demonstrate the protocol's efficacy to address the scalability issues in V2X communication. By employing a distributed opportunistic approach, the SAE J2945/1 congestion control algorithm keeps the overall offered channel load within an optimal operating range, while meeting the minimum tracking requirements set forth by upper-layer applications. This scheduling protocol allows event-triggered and vehicle-dynamics driven message transmits that further the situational awareness in a cooperative V2X context. Presented validation results of the congestion control algorithm include position tracking errors as the performance measure, with the age of communicated information as the evaluation measure. In addition, we examine the optimality of the default settings of the congestion control parameters. Comprehensive analysis and trade-off study of the control parameters reveal some areas of improvement to further the algorithm's efficacy. Motivated by the effectiveness of channel congestion control mechanism, we further investigate message content and length adaptations, together with transmit rate control. Reasonably, the content of the exchanged information has a significant impact on the map accuracy in cooperative driving systems. We investigate different content control schemes for a communication architecture aimed at map sharing and evaluate their performance in terms of position tracking error. This dissertation determines that message content should be concentrated to mapped objects that are located farther away from the sender to the edge of the local sensor range. This dissertation also finds that optimized combination of message length and transmit rate ensures the optimal channel utilization for cooperative vehicular communication, which in turn improves the situational awareness of the whole system.
Show less - Date Issued
- 2019
- Identifier
- CFE0007634, ucf:52470
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007634