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HEURISTIC PRIORITIZATION OF EMERGENCY EVACUATION STAGING TO REDUCE CLEARANCE TIME
Title
HEURISTIC PRIORITIZATION OF EMERGENCY EVACUATION STAGING TO REDUCE CLEARANCE TIME.
Creator
Mitchell, Steven, Radwan, Essam, University of Central Florida
Abstract / Description
A region's evacuation strategy encompasses a variety of areas and needs. Primary among these is the minimization of total evacuation time, represented in models as the clearance time estimate (CTE). A generic testbed simulation network model was developed. An input/output (I/O) analysis was performed to establish a theoretical baseline CTE. Results were compared with simulations; analysis showed that the I/O method underestimated simulated CTE as a function of network size, with a correction...
Show moreA region's evacuation strategy encompasses a variety of areas and needs. Primary among these is the minimization of total evacuation time, represented in models as the clearance time estimate (CTE). A generic testbed simulation network model was developed. An input/output (I/O) analysis was performed to establish a theoretical baseline CTE. Results were compared with simulations; analysis showed that the I/O method underestimated simulated CTE as a function of network size, with a correction factor range of 1.09 to 1.19. A regression model was developed for the generic network. Predictors were total trips, and network size defined as a function of origin-destination distance. Total Trips ranged between 40,000 and 60,000. Holding size constant, R-squared values ranged from 97.1 to 99.3, indicating a high goodness of fit. Holding Total Trips constant, R-squared values ranged from 74.5 to 89.2. Finally, both Total Trips and size were used as predictors; the resulting regression model had an R-squared value of 97.3. This overall model is more useful, since real world situations are not fixed in nature. The overall regression model was compared to a case network. The generic network regression model provided a close CTE approximation; deltas ranged from -4.7% to 8.6%. It was concluded that a generic network can serve as a surrogate for a case network over these ranges. This study developed and evaluated heuristic strategies for evacuation using the generic network. Strategies were compared with a simultaneous departure loading scenario. Six different grouping strategies were evaluated. An initial evaluation was conducted using the generic network, and strategies that showed potential CTE reduction were implemented on the case study network. Analysis indicated that the HF-10 (half-far) grouping for 60k total trips showed potential reduction. A complete simulation was conducted on the case network for all HF scenarios; an ANOVA was run using Dunnett's comparison. Results indicated that the HF grouping with 20% and 30% departure shifts showed potential for CTE reduction. From this it was concluded that the generic network could be used as a testbed for strategies that would show success on a case network.
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Date Issued
2006
Identifier
CFE0001098, ucf:46777
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0001098
Performance Evaluation of Connectivity and Capacity of Dynamic Spectrum Access Networks
Title
Performance Evaluation of Connectivity and Capacity of Dynamic Spectrum Access Networks.
Creator
Al-tameemi, Osama, Chatterjee, Mainak, Bassiouni, Mostafa, Jha, Sumit, Wei, Lei, Choudhury, Sudipto, University of Central Florida
Abstract / Description
Recent measurements on radio spectrum usage have revealed the abundance of under- utilized bands of spectrum that belong to licensed users. This necessitated the paradigm shift from static to dynamic spectrum access (DSA) where secondary networks utilize unused spectrum holes in the licensed bands without causing interference to the licensed user. However, wide scale deployment of these networks have been hindered due to lack of knowledge of expected performance in realistic environments and...
Show moreRecent measurements on radio spectrum usage have revealed the abundance of under- utilized bands of spectrum that belong to licensed users. This necessitated the paradigm shift from static to dynamic spectrum access (DSA) where secondary networks utilize unused spectrum holes in the licensed bands without causing interference to the licensed user. However, wide scale deployment of these networks have been hindered due to lack of knowledge of expected performance in realistic environments and lack of cost-effective solutions for implementing spectrum database systems. In this dissertation, we address some of the fundamental challenges on how to improve the performance of DSA networks in terms of connectivity and capacity. Apart from showing performance gains via simulation experiments, we designed, implemented, and deployed testbeds that achieve economics of scale. We start by introducing network connectivity models and show that the well-established disk model does not hold true for interference-limited networks. Thus, we characterize connectivity based on signal to interference and noise ratio (SINR) and show that not all the deployed secondary nodes necessarily contribute towards the network's connectivity. We identify such nodes and show that even-though a node might be communication-visible it can still be connectivity-invisible. The invisibility of such nodes is modeled using the concept of Poisson thinning. The connectivity-visible nodes are combined with the coverage shrinkage to develop the concept of effective density which is used to characterize the con- nectivity. Further, we propose three techniques for connectivity maximization. We also show how traditional flooding techniques are not applicable under the SINR model and analyze the underlying causes for that. Moreover, we propose a modified version of probabilistic flooding that uses lower message overhead while accounting for the node outreach and in- terference. Next, we analyze the connectivity of multi-channel distributed networks and show how the invisibility that arises among the secondary nodes results in thinning which we characterize as channel abundance. We also capture the thinning that occurs due to the nodes' interference. We study the effects of interference and channel abundance using Poisson thinning on the formation of a communication link between two nodes and also on the overall connectivity of the secondary network. As for the capacity, we derive the bounds on the maximum achievable capacity of a randomly deployed secondary network with finite number of nodes in the presence of primary users since finding the exact capacity involves solving an optimization problem that shows in-scalability both in time and search space dimensionality. We speed up the optimization by reducing the optimizer's search space. Next, we characterize the QoS that secondary users can expect. We do so by using vector quantization to partition the QoS space into finite number of regions each of which is represented by one QoS index. We argue that any operating condition of the system can be mapped to one of the pre-computed QoS indices using a simple look-up in Olog (N) time thus avoiding any cumbersome computation for QoS evaluation. We implement the QoS space on an 8-bit microcontroller and show how the mathematically intensive operations can be computed in a shorter time. To demonstrate that there could be low cost solutions that scale, we present and implement an architecture that enables dynamic spectrum access for any type of network ranging from IoT to cellular. The three main components of this architecture are the RSSI sensing network, the DSA server, and the service engine. We use the concept of modular design in these components which allows transparency between them, scalability, and ease of maintenance and upgrade in a plug-n-play manner, without requiring any changes to the other components. Moreover, we provide a blueprint on how to use off-the-shelf commercially available software configurable RF chips to build low cost spectrum sensors. Using testbed experiments, we demonstrate the efficiency of the proposed architecture by comparing its performance to that of a legacy system. We show the benefits in terms of resilience to jamming, channel relinquishment on primary arrival, and best channel determination and allocation. We also show the performance gains in terms of frame error rater and spectral efficiency.
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Date Issued
2016
Identifier
CFE0006063, ucf:50980
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0006063