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Wireless Sensor Network for Monitoring of Historic Structures under RehabilitationSamuels, Julie Marie 2010 December 1900 (has links)
The use of a wireless sensor network (WSN) to monitor an historic structure under rehabilitation is the focus of this research. To thoroughly investigate the issue, two main objectives are addressed: the development of a reliable WSN tailored for use in historic structures, and the implementation of the monitoring system in the field to test the feasibility of the WSN and its applicability for structural health monitoring (SHM).
Three field studies are undertaken in this research. The Frankford Church, an historic wooden church which required foundation replacement, is the first field study. Sensors monitor tilt of the church’s walls throughout construction. During the construction process, the entire floor of the church is removed and the tree stump foundations are replaced by concrete masonry unit (CMU) blocks and steel pedestals. The tilt in the walls is correlated to the construction process. St. Paul Lutheran, an historic masonry church with timber-framed roof, constitutes the second field study. In this structure, the foundations along the exterior walls are underpinned and the floors are removed and replaced with a floating concrete slab. Detected movements are also correlated to the construction efforts. The Johanniskirche, an historic masonry church with moisture problems, is the final field study case. Real-time and past measured WSN climate data is used to determine the most appropriate solution for the humid climate and resulting condensation problems in this structure. From these results, a moisture migration risk analysis protocol is created for use with a WSN to address condensation issues.
The results of the tilt monitoring indicate that the approach is realistic to monitor tilt in the walls of historic structures. For future research, it is recommended to implement motes with higher tilt sensitivity. Also, further development of energy saving algorithms and energy harvesting methods will improve the WSN’s performance.
Climate monitoring results show it is feasible to monitor climate conditions of historic structures. The moisture migration protocol provides a basis for further improvement. Implementation of this tool will help predict condensation events and prevent future damage to the historic structure.
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Duality and Genetic Algorithms for the Worst-Case-Coverage Deployment Problem in Wireless Sensor NetworksPeng, Yi-yang 21 July 2005 (has links)
In this thesis, we propose and evaluate algorithms for solving the worst-case-coverage deployment problem in ad-hoc wireless sensor networks. The worst-case-coverage deployment problem is to deploy additional sensors in the wireless sensor field to optimize the worst-case coverage. We derive a duality theorem that reveals the close relation between the maximum breach path and the minimum Delaunay cut. The duality theorem is similar to the well-known max-flow-min-cut theorem in the field of network optimization. The major difference lies in the fact that the object function we study in this paper is nonlinear rather than linear. Based on the duality theorem, we propose an efficient dual algorithm to solve the worst-case-coverage deployment problem. In addition, we propose a genetic algorithm for deploying a number of additional sensors simultaneously. We use analytical proofs and simulation results to justify the usage of the proposed approaches.
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The Baseband Signal Processing and Circuit Design for 2.45GHz Mode of the IEEE802.15.4 Low Rate-Wireless Personal Area Network (LR-WPAN)Liu, Tung-yu 11 August 2005 (has links)
The baseband part of IEEE 802.15.4 operated in 2.45 GHz mode is designed and implemented in this essay. First, the features of IEEE 802.15.4 WPAN(Wireless Personal Area Network), PHY layer and MAC Layer are introduced. Then the algorithm and VHDL of the baseband part of transceiver are designed and verified by FPGA board and logical analyzer.
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Connectivity improvement scheme in wireless sensor networkChen, Chi-chang 17 July 2007 (has links)
Under the current environment of Wireless Senor Networks (WSN), security is always one of the topics that everyone discussed about. Because of the limitations of WSN¡¦s unique resource, this results in the security of WSN needs to especially consider the calculating ability, memory capacity, characteristics of wireless communication, limited battery power supply, etc. Random key pre-distribution (RKP) is the one of the key distribution that is developed for the sake of safe communication of WSN, the characteristic of RKP is that there must have at least one common pre-distributed key in the two independent nodes in order to compose a pair-wise key, so that the safe communication can be carried out. However, if the nodes are distributed in the loose environment, the numbers of neighbors would be lower due to the decrease of average node degree. Then the connectivity of the entire network would decrease because it is not easy for the RKP to establish the pair-wise key. This paper would set the improvement of the entire network¡¦s connectivity under the loose environment as the starting point to extend the RKP-DE that only considers one-hop neighbor information, and reverse the flow path of RKP-DE and propose RKP- DEinverse from the viewpoint of two-hop neighbor information. Then RKP-DE and RKP- DEinverse are merged and become a new method ¡V RKP- DEtwo_hop, so as to try to prove that we can raise the connectivity of the whole network effectively.
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The Improved Broadcast Authentication Schemes in Wireless Sensor NetworksYang, Li-Wei 15 July 2008 (has links)
In the environment of wireless sensor network, while one node want to send a message to another node, the most natural way is used broadcasting to distribute the message to the whole network. In the other words, as long as one node sends messages to the other node, its neighbor nodes can also listen to these messages, and then receive them. The advantage of broadcast networks is that can efficiently distribute data to multiple receivers. However, it has some drawbacks. A sensor network may be deployed in hostile environment where there are malicious attacks. The malicious attacker can send false messages to his neighbor nodes, and then rely on these neighbor nodes to distribute over the network. So if there are not any schemes of the security authentication in the message when a node wants to use broadcast, everyone can impersonate the sender and broadcast false messages. We call this a packet injection attack. So security is a main challenge in broadcast network. In order to authenticate a broadcast message¡Ait would conform to two conditions. First, insure that the data is transmitted from the claimed source. Second, the messages are not be modified en route. TESLA has been proposed to provide such services for sensor networks¡Ait mainly use time synchronization and delay disclosure key to protect encryption key¡CHowever, this scheme still has some drawbacks, so we propose some schemes to modify TESLA in this paper, and we will show these schemes can achieve better performance than previous ones.
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MCCA: The Novel Ways for Multiple Cluster Collision Avoidance in TDMA Cluster-based Wireless Sensor NetworksTsai, Ping-cheng 24 July 2008 (has links)
Wireless sensor networks typically consist of a significant number of low-cost sensor nodes which can collaborate among each other to execute a wide range of applications, such as environmental and health monitoring, intrusion detection, etc. Basically, sensor nodes are mainly battery-powered and have a limited amount of energy to spend, thereby they are not likely to be recharged or replenished after being deployed in an inaccessible sensed environment. As a result, in the past decade, power saving has become a critical issue for the design of a media access control (MAC) protocol in wireless sensor networks. By incorporating power-saving mechanism into MAC, we expect to maximize the lifetime of a sensor network. Intuitively, a large amount of research tends to make use of the TDMA protocol because it has inherently more favorable characteristics when compared to the CSMA protocol, that is, sensor nodes only need to wake up to transmit or receive data at its allocated time slots, and other time slots they can go into sleep mode. By doing so, it can reduce power consumption. However, in this master thesis, we found that there exists a rather acute problem, called the Multiple-Cluster Collision (MCC) problem, in the TDMA cluster-based protocol that will degrade the system performance drastically. Therefore, in this thesis, we propose the approach, called Multiple Cluster Collision Problem (MCCP), to perfectly eliminate the MCC problem by sensor nodes. Finally, we will compare our approach with SRSA, proposed by Tao WU et al., to show that the performance of our approach outperforms SRSA in terms of collision reduction, throughput and so on.
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Lifetime Maximization Schemes with Optimal Power Control for Multimedia Traffic in Wireless Sensor NetworksLu, Y-Jen 23 June 2009 (has links)
Power saving for extending session lifetime is an important research subject in wireless sensor networks (WSNs). Recognizing the fact that Quality of Service can be deteriorated by insufficient transmit power, this work studies how to minimize power consumption while achieve a satisfactory QoS of data streams in WSNs. A cross-layer routing scheme is proposed to maximize session lifetime by adjusting individual transmit power on intermediate nodes. The thesis is divided into two major parts for analyzing our proposition. In the first part, we propose an efficient routing scheme with optimal power management and on-demand quality control for WSNs. When source node issues a QoS provision for route discovery, an adjustment of transmit power is computed for each pass-by node by taking into its individual wireless link account. Then, an optimal route associated with lowest power consumption and consistent QoS can be selected among all of the candidate routes. In the second part, by following the definition of QoS criterion in the first part, we further consider the problem of how to balance the needs on constraining end-to-end quality and prolonging lifetime in an established route. The problem can be interpreted as a non-linear optimization paradigm, which is then shown to be a max-min composite formulation. To solve the problem, we propose two methods, (1) route-associated power management (RAPM), and (2) link-associated power management (LAPM). Considering computation-restricted sensor nodes, the RAPM scheme is two-fold simplification; not only it can reduce power computation, but it also quickly determines the longest lifetime and proper transmit power for nodes. On the other hand, if computational cost is not a major concern in a sink node, the LAPM algorithm is more suitable than RAPM to solve the lifetime maximization problem, in terms of accuracy. Finally, we analyze the performance of these two methods. The results demonstrate that the LAPM scheme is very comparable to a heuristic approach.
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A Heuristic Algorithm for Maximizing Lifetime in Sensor NetworkWu, De-kai 15 July 2009 (has links)
Wireless sensor network has applications in environmental surveillance,
healthcare, and military operations. Because the energy of sensor nodes is
limited and nodes are unable to supply energy in real time, the purpose of
many researches is to prolong lifetime of sensor network. Lifetime is times
that the sink can collect data from all sensor nodes. When a user proposes
a query, then the sink gathers data from all sensor nodes.
The problem defined in the previous research is given a sensor network
and residual energy of each node, and the energy consumption of transmitting
a unit message between two nodes. Then this problem is to find a directed
tree that maximize minimum residual energy. In this thesis, we define a new
problem that given a sensor network and residual energy of each node, and the
energy consumption of transmitting a unit message between two nodes. Then
our problem is to find a path of each node, which maximize minimum residual
energy. We prove this problem is NP-complete. We propose a heuristic
algorithm and a similar heuristic algorithm for this problem.
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The Path Adjustment of Load-balance Directed Diffusion in Wireless Sensor NetworksChen, Tsung-han 24 July 2009 (has links)
none
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Wind energy harvesting for bridge health monitoringMcEvoy, Travis Kyle 11 July 2011 (has links)
The work discussed in this thesis provides a review of pertinent literature, a design methodology, analytical model, concept generation and development, and conclusions about energy harvesting to provide long-term power for bridge health monitoring. The methodology gives structure for acquiring information and parameters to create effective energy harvesters. The methodology is used to create a wind energy harvester to provide long-term power to a wireless communication network. An analytical model is developed so the system can be scaled for different aspects of the network. A proof of concept is constructed to test the methodology's effectiveness, and validate the feasibility and analytical model. / text
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