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Title: Development of small biomimetic robotic fish with onboard fine-grained localization
Creator: Shatara, Stephan W.
Date: 2008
Collection: Electronic Theses & Dissertations

Title: Off-network control processing for scalable routing in very large sensor networks
Creator: Wu, Tao
Date: 2008
Collection: Electronic Theses & Dissertations

Title: A progressive reliability framework for wireless sensor networks
Creator: Qaisar, Saad Bin
Date: 2009
Collection: Electronic Theses & Dissertations

Title: Analytical and quantitative characterization of wireless sensor networks
Creator: Ilyas, Muhammad Usman
Date: 2009
Collection: Electronic Theses & Dissertations

Title: Environmental acoustics as an ecological variable to understand the dynamics of ecosystems
Creator: Joo, Wooyeong
Date: 2009
Collection: Electronic Theses & Dissertations

Title: Providing source privacy in wireless sensor networks
Creator: Li, Yun
Date: 2010
Collection: Electronic Theses & Dissertations

Title: Preserving source-location privacy in wireless sensor networks
Creator: Lightfoot, Leron J.
Date: 2010
Collection: Electronic Theses & Dissertations
Description: Wireless sensor networks (WSNs) can provide the world with a technology for real-time event monitoring for both military and civilian applications. One of the primary concerns that hinder the successful deployment of wireless sensor networks is source-location privacy. The privacy of the source location is vital and highly jeopardized by the usage of wireless communications.While message content privacy can be ensured through message encryption, it is much more difficult to adequately address...
Show moreWireless sensor networks (WSNs) can provide the world with a technology for real-time event monitoring for both military and civilian applications. One of the primary concerns that hinder the successful deployment of wireless sensor networks is source-location privacy. The privacy of the source location is vital and highly jeopardized by the usage of wireless communications.While message content privacy can be ensured through message encryption, it is much more difficult to adequately address the source-location privacy. For WSNs, source-location privacy service is further complicated by the fact that sensors consist of low-cost and energy efficient radio devices. Therefore, using computationally intensive cryptographic algorithms (such as public-key cryptosystems) and large scale broadcasting-based protocols are not suitable for WSNs.Many protocols have been proposed to provide source-location privacy but most of them are based on public-key cryptosystems, while others are either energy inefficient or have certain security flaws. In this thesis, after analyzing the security weakness of the existing scheme, we propose three routing-based source-location privacy schemes. The first scheme routes each message to a randomly selected intermediate node before it is transmitted to the SINK node. However, this scheme can only provide local source-location privacy. In the second scheme, a network mixing ring (NMR) is proposed to provide network-level source-location privacy. The third scheme achieve network-level source-location privacy through a technique we call the Sink Toroidal Region (STaR) routing. For each of these routing schemes, both security analysis and simulation results show that the proposed schemes are secure and efficient.
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Title: Mobility and communication in wireless robot and sensor networks
Creator: Pei, Yuanteng
Date: 2011
Collection: Electronic Theses & Dissertations
Description: Mobility is a primary goal of many wireless communication systems. In recent years, mobile multi-hop wireless networks, such as mobile wireless sensor networks and wireless robot networks, have attracted increased attention and have been extensively studied. However, most current research does not consider the interdependence of communication and mobility and much assume an obstacle-free environment in their problem modeling and solving process.In this dissertation, we discuss several...
Show moreMobility is a primary goal of many wireless communication systems. In recent years, mobile multi-hop wireless networks, such as mobile wireless sensor networks and wireless robot networks, have attracted increased attention and have been extensively studied. However, most current research does not consider the interdependence of communication and mobility and much assume an obstacle-free environment in their problem modeling and solving process.In this dissertation, we discuss several research topics relevant to the above two issues of communication and mobility in wireless robot and sensor networks. First, we present multi-robot real-time exploration, which calls for the joint consideration of mobility and communication: it requires video and audio streams of a newly explored area be transmitted to the base station in a timely fashion as robots explore the area. Simulations show that our mobility model has achieved both improved communication quality and enhanced exploration efficiency.Second, we further investigate the above problem with two critical and real-world network conditions: (1) heterogeneous transmission ranges and link capacities, and (2) the impact of interference. The conditions increase the model complexity but significantly influence the actual available bandwidth and the required node size in placement. We jointly consider the relay placement and routing with these two critical conditions.Third, we introduce an online relay deployment paradigm to support remote sensing and control when mobile nodes migrate farther from the base station in a cost-effective system of mobile robots, static sensors and relays. A novel multi-robot real-time search method called STAtic Relay aided Search (STARS) is presented to allow robots to search in a known environment. Its solution is based on our near-optimal solution to a new variation of the multi-traveling salesman problem: precedence constrained two traveling salesman (PC2TSP).Fourth, we propose a heterogenous multi-robot exploration strategy with online relay deployment for an unknown environment called Bandwidth aware Exploration with a Steiner Traveler (BEST). In BEST, a relay-deployment node (RDN) tracks the FNs movement and places relays when necessary to support the video/audio streams aggregation to the base station. This problem inherits characteristics of both the Steiner minimum tree and traveling salesman problems. Extensive simulations show that BEST further enhances the exploration efficiency.While the first four topics deal with communication and mobility issues in powerful but expensive robotic systems, the fifth topic focuses on a special type of low cost, limited capability mobile sensors called hopping sensors, whose unique method of movement makes them suitable for rugged terrains. We present (1) a distributed message forwarding model called Binary Splitting Message Forwarding (BSMF) and (2) a grid based movement model unique to these hopping sensors. Simulation shows that our scheme significantly reduces the communication overhead and achieves relatively constant total energy consumption with varying amount of obstructions.Finally, we discuss the future work directions of this research work. We believe that a heterogeneous mobile platform to support real-time stream transmission by mobile robots, static sensor and communication devices, have great potential in various civilian and military applications, where the communication quality of service is critically important, as well as the mobility efficiency.
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Title: Design and implementation of integrated self-powered sensors, circuits and systems
Creator: Huang, Chenling
Date: 2011
Collection: Electronic Theses & Dissertations
Description: Wireless sensor systems have been widely used for both industrial and civil applications. With the development of circuit design and fabrication technique, sensor nodes now can be implemented with small scale at low cost, which is promising for ubiquitous sensing. However, with more functions integrated, the conflict between power consumption and expected lifetime became critical. Sensor nodes powered with batteries are generally compromised by extra physical size and periodic battery...
Show moreWireless sensor systems have been widely used for both industrial and civil applications. With the development of circuit design and fabrication technique, sensor nodes now can be implemented with small scale at low cost, which is promising for ubiquitous sensing. However, with more functions integrated, the conflict between power consumption and expected lifetime became critical. Sensor nodes powered with batteries are generally compromised by extra physical size and periodic battery replacement. Therefore, energy harvesting techniques are intensively involved in sensor design where environmental signal acts as auxiliary energy source.A typical energy harvesting sensor consists of four parts: energy harvester, energy storage, power management and sensor subsystem. Energy harvester scavenges power from environmental signal which is then transferred into energy storage. Since the output power is usually not in appropriate form, power management is used to provide a usable supply voltage/current for sensor subsystem. The limitation of energy harvesting sensor is determined by the power consumption of sensor subsystem, the efficiency of energy conversion and the available energy level from environment.In this dissertation, a novel solution referred as "self-powered sensor" is proposed to extend the limitation of energy harvesting sensor. The proposed sensor can directly harvest energy from input signal being sensed. Therefore the usage of energy storage and power management is eliminated, which achieves higher energy efficiency.To demonstrate proposed solution, the system and circuit design of a self-powered sensor are presented for long-term ambient vibration monitoring. Constrained by its application, the sensor can only scavenge energy from input strain signal itself, in which scenario all existing energy harvesting techniques fail. The greatest design challenge is to achieve both ultra-low power computation and non-volatile storage. In this dissertation, a novel technique based on floating-gate transistor is presented. By exploiting controllable hot electron injection procedure, specific computation can be performed according to the characteristic of input signal. In addition, floating-gates can also retain computation results with no power consumption.For autonomous sensing, a hybrid energy harvesting topology is proposed on system level. The sensor is designed with two different operation modes. In self-powered sensing mode, it can perform continuous monitoring, computation and data storage which is powered by input strain signal. In data interrogating mode, additional functions such as data sampling and wireless communication can be enabled once a certain reading device is provided.The dissertation is organized as follows. In chapter 1, the history of wireless sensor system is reviewed. The motivation of self-powered sensor and the contributions of this dissertation are presented. Existing energy harvesting techniques are evaluated in chapter 2. In chapter 3, the case of long-term ambient vibration monitoring is studied and the hybrid energy harvesting topology is proposed for self-powered sensor system. In chapter 4, the principle of ultra-low power computation and non-volatile storage is explored based on controllable injection procedure on floating-gate transistor. To verified proposed solution, a sensor prototype was fabricated in 0.5-um standard CMOS process. The details of circuit design and evaluation are presented in chapter 5, including analog signal processor, analog-to-digital converter, radio frequency front-end, digital baseband, etc. Chapter 6 shows an extension of ultrasonic powering and communication system based on preliminary work and chapter 7 draws final remarks.
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Title: Implementation of a high throughput low power MAC protocol in wireless sensor networks
Creator: Liu, Chin-Jung
Date: 2011
Collection: Electronic Theses & Dissertations
Description: This thesis presents the design, implementation, and evaluation of TATD-MAC, a TDMA-based low duty cycle synchronous MAC protocol that improves throughput by increasing channel uti- lization with a traffic-adaptive time slot scheduling method. Conventional time division multiple access (TDMA) introduces significant end-to-end packet delivery delay and its throughput is lim- ited. TATD-MAC achieves higher throughput by improving TDMA with a novel traffic-adaptive mechanism that assigns time...
Show moreThis thesis presents the design, implementation, and evaluation of TATD-MAC, a TDMA-based low duty cycle synchronous MAC protocol that improves throughput by increasing channel uti- lization with a traffic-adaptive time slot scheduling method. Conventional time division multiple access (TDMA) introduces significant end-to-end packet delivery delay and its throughput is lim- ited. TATD-MAC achieves higher throughput by improving TDMA with a novel traffic-adaptive mechanism that assigns time slots only to nodes that are expecting traffic. Our traffic-adaptive mechanism is a two-phase design, which decomposes the DATA period into traffic notification part and data transmission scheduling part. The two-phase design enables TATD-MAC to optimize the control packets and improve their energy efficiencies according to the characteristics of each phase. The source nodes inform all nodes on the routing path that these sources have outgoing traffic by transmitting traffic notification packets in a "pulse" fashion. With traffic notification packets, ev- ery node on the routing path claims time slots in data transmission part. Therefore, TATD-MAC is able to forward a packet over multiple hops in a single cycle and thus reduce the end-to-end delay. The data transmission scheduling mechanism only assigns time slots to nodes with traf- fic through an ordered schedule negotiation scheme. This innovative traffic-adaptive scheduling mechanism assigns time slots based on traffic and totally eliminates the idle listening slots on nodes with no traffic. Moreover, if any other nodes need more time slots, they are able to claim them, which further improves channel utilization and achievable throughput. We implemented a TATD-MAC prototype on Tmote-Sky running TinyOS 2.1.0. Performance evaluation shows that TATD-MAC significantly improves throughput compared to conventional TDMA and achieves the same throughput as TDMA with slot stealing while having 70% less power consumption.
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Title: Exploiting node mobility for energy optimization in wireless sensor networks
Creator: El-Moukaddem, Fatme Mohammad
Date: 2012
Collection: Electronic Theses & Dissertations
Description: Wireless Sensor Networks (WSNs) have become increasingly available for data-intensive applications such as micro-climate monitoring, precision agriculture, and audio/video surveillance. A key challenge faced by data-intensive WSNs is to transmit the sheer amount of data generated within an application's lifetime to the base station despite the fact that sensor nodes have limited power supplies such as batteries or small solar panels. The availability of numerous low-cost robotic units (e.g....
Show moreWireless Sensor Networks (WSNs) have become increasingly available for data-intensive applications such as micro-climate monitoring, precision agriculture, and audio/video surveillance. A key challenge faced by data-intensive WSNs is to transmit the sheer amount of data generated within an application's lifetime to the base station despite the fact that sensor nodes have limited power supplies such as batteries or small solar panels. The availability of numerous low-cost robotic units (e.g. Robomote and Khepera) has made it possible to construct sensor networks consisting of mobile sensor nodes. It has been shown that the controlled mobility offered by mobile sensors can be exploited to improve the energy efficiency of a network.In this thesis, we propose schemes that use mobile sensor nodes to reduce the energy consumption of data-intensive WSNs. Our approaches differ from previous work in two main aspects. First, our approaches do not require complex motion planning of mobile nodes, and hence can be implemented on a number of low-cost mobile sensor platforms. Second, we integrate the energy consumption due to both mobility and wireless communications into a holistic optimization framework.We consider three problems arising from the limited energy in the sensor nodes. In the first problem, the network consists of mostly static nodes and contains only a few mobile nodes. In the second and third problems, we assume essentially that all nodes in the WSN are mobile. We first study a new problem called max-data mobile relay configuration (MMRC) that finds the positions of a set of mobile sensors, referred to as relays, that maximize the total amount of data gathered by the network during its lifetime. We show that the MMRC problem is surprisingly complex even for a trivial network topology due to the joint consideration of the energy consumption of both wireless communication and mechanical locomotion. We present optimal MMRC algorithms and practical distributed implementations for several important network topologies and applications. Second, we consider the problem of minimizing the total energy consumption of a network. We design an iterative algorithm that improves a given configuration by relocating nodes to new positions. We show that this algorithm converges to the optimal configuration for the given transmission routes. Moreover, we propose an efficient distributed implementation that does not require explicit synchronization. Finally, we consider the problem of maximizing the lifetime of the network. We propose an approach that exploits the mobility of the nodes to balance the energy consumption throughout the network. We develop efficient algorithms for single and multiple round approaches. For all three problems, we evaluate the efficiency of our algorithms through simulations. Our simulation results based on realistic energy models obtained from existing mobile and static sensor platforms show that our approaches significantly improve the network's performance and outperform existing approaches.
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Title: Security and privacy in resource constrained wireless networks
Creator: Pongaliur, Kanthakumar Mylsamy
Date: 2012
Collection: Electronic Theses & Dissertations
Description: Wireless networks use radio waves as a communication medium which allows for faster and cheaper deployment. The networks being wireless, are out in the open, which makes them vulnerable to malicious users that can hinder their performance. Of the several types of wireless networks, we focus on security and privacy in wireless sensor networks (WSN) and cognitive radio mobile ad-hoc networks (CR-MANET). The devices in these networks are limited in resources such as energy, low power radio, etc....
Show moreWireless networks use radio waves as a communication medium which allows for faster and cheaper deployment. The networks being wireless, are out in the open, which makes them vulnerable to malicious users that can hinder their performance. Of the several types of wireless networks, we focus on security and privacy in wireless sensor networks (WSN) and cognitive radio mobile ad-hoc networks (CR-MANET). The devices in these networks are limited in resources such as energy, low power radio, etc. CR-MANET devices are mobile, requiring them to run on limited amount of energy supplied by batteries, and conserve energy by reducing communication cost using low power radios. In addition, sensor devices have limited storage and a slower CPU. The purpose of a WSN is to sense and report event occurrences, whereas a CR-MANET provides improved spectrum utilization.We studied three kinds of attacks on WSN. The first type of attack is on the source privacy of sensor nodes. This attack happens because an important characteristic of events detected by sensor devices is bound to the location of event occurrence that can be revealed by compromise of detecting sensor device's source privacy. Thus, protecting privacy of event detecting sensor device is of paramount importance for which we present an encryption based solution to protect source privacy under eavesdropping and node compromise attacks. The second type of attack by the malicious entity can be invasive in nature, which could possibly cause damage to the device, or can be passive as in side channel attacks. A comprehensive study of side channel attacks on WSN is presented, along with a process obfuscation technique. The third type of attack is on the propagation of data packet generated by the sensor device. The detected event data is sent to the base station. If a malicious entity is able to prevent such event reporting packets from reaching the base station and segregate the attack zone, it will be able to carry out its malicious activity without getting caught. To cover such scenarios, a proactive dynamic camouflage event generation solution is presented.CR-MANET devices sense for vacant licensed spectrum and improve its utilization in an opportunistic manner. Accurate licensed spectrum occupancy detection by a CR-MANET device is hampered by signal fading, hidden terminal problems, etc. Spectrum occupancy decision can be improved by cooperative spectrum sensing (CSS). However, CSS is made difficult by the presence of malicious users. The malicious users can have two goals: one is to disrupt the network, another is to manipulate the network for its own personal gains. The malicious users can create havoc in a CR-MANET by falsifying spectrum sensing information leading to interference with the primary user. The devices in a CR-MANET are mobile, which gives an opportunity for the malicious entity to hide behind the changing neighborhood. We present three solutions to overcome the spectrum sensing data falsification attack and incorrect reporting of signal measurement due to byzantine failures. The first is a multi-fusion based distributed spectrum sensing (MFDSS) using reputation propagation. In the second solution, a continuously evolving virtual neighbor cluster of past neighbor devices aid in validating the input gathered from the current neighboring devices (ReNVaS). Third, a recursive partitioning around medoids based clustering is performed to identify a tightly bound set of valid inputs for decision making (TMC). A unified and non-unified decision making strategy is presented using ReNVaS and TMC. MFDSS performs better in a fast changing network while performance of unified fusion is better in a slow mobility network with respect to primary user spectrum occupancy detection accuracy.
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Title: Pulse switching : an ultra-light network paradigm without packet abstraction
Creator: Huo, Qiong
Date: 2013
Collection: Electronic Theses & Dissertations
Description: In this dissertation we develop a novel pulse switching framework for ultra light-weight networking applications involving severely resource-constrained embedded devices. The key idea is to abstract a single pulse, as opposed to multi-bit packets, as the network switching granularity. Pulse switching can be shown to be sufficient for on-off style event monitoring applications for which a monitored parameter can be modeled using just a binary variable. Monitoring such events with conventional...
Show moreIn this dissertation we develop a novel pulse switching framework for ultra light-weight networking applications involving severely resource-constrained embedded devices. The key idea is to abstract a single pulse, as opposed to multi-bit packets, as the network switching granularity. Pulse switching can be shown to be sufficient for on-off style event monitoring applications for which a monitored parameter can be modeled using just a binary variable. Monitoring such events with conventional packet paradigm can be prohibitively inefficient due to the communication, processing, and buffering overheads of the large number of bits within packet data, header, and preambles for synchronization. In the proposed paradigm, an event can be coded as a single pulse, which is then transported multi-hop while preserving sufficient information so that a destination (i.e., sink or actuator nodes) can derive certain spatio-temporal context information about the event in question. The resulting operational lightness, leveraged via zero buffering, no addressing, no packet processing, and an ultra-low communication energy budget makes the framework applicable for embedded devices such as Radio Frequency Identifiers operating with ultra-tight energy budgets, such as from harvested energy.Specific contributions includes: 1) Developing a joint MAC-Routing abstraction for pulse switching, 2) Mapping the proposed pulse switching architecture on Ultra Wideband Band (UWB) impulse radio technology, 3) Developing a hop-angular spatial context abstraction and the related estimation algorithms for event localization, 4) Designing a cellular alternative to the hop-angular abstraction, 5) Designing a peer-to-peer pulse routing protocol, finally 6) System characterization through modeling and large scale simulation.
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Title: Power management and damage assessment techniques for self-powered sensing based on piezoelectric transduction
Creator: Rhimi, Mohamed
Date: 2013
Collection: Electronic Theses & Dissertations
Description: One major obstacle facing health monitoring systems is the ability to accurately predict remaining life after structural state diagnosis. Today, many remaining life prediction models rely on empirical data which limits their applicability. Moreover, the large scatter in material data, i.e., fatigue, combined with archaic instrumentation has hindered the development and validation of improved prediction models. There is a need for long term continuous monitoring techniques capable of rendering...
Show moreOne major obstacle facing health monitoring systems is the ability to accurately predict remaining life after structural state diagnosis. Today, many remaining life prediction models rely on empirical data which limits their applicability. Moreover, the large scatter in material data, i.e., fatigue, combined with archaic instrumentation has hindered the development and validation of improved prediction models. There is a need for long term continuous monitoring techniques capable of rendering a more precise and reliable stream of data that would enhance the modeling proficiencies and would ultimately help reduce maintenance cost, improve the longevity, and enhance the safety of civil infrastructures.Wireless sensors and sensor networks are emerging as sensing paradigms that the structural engineering field has begun to consider as substitutes for traditional tethered monitoring systems. A major consideration in using a dense sensor array for long term monitoring is the problem of providing power to the sensors. Piezoelectric energy powering has the added advantage to act both as the sensor and as the powering means, thereby reducing the power requirement and cost of the sensor system.Improving the piezoelectric power harvesting from civil structures' vibration while obeying environmental effects (temperature variation) is the first objective of this thesis; the application of a variable preloading condition is used as a solution to modify the cantilever piezoelectric harvester's properties. A generalized model that takes into account more than one vibration-mode shape is derived. Measured acceleration recordings from a concrete bridge deck under ambient loading and recordings from extreme events are used to show the gain in harvested energy when the harvester is in preloaded configuration. The effects of temperature variations on the piezoelectric (PZT) harvested energy from civil structures are also studied. A proposed mechanical tuning, based on the application of an axial load using Shape Memory Alloy to compensate the temperature effect, is presented.The work describing a fully deployed long-term piezoelectric based monitoring system with all needed attributes is the second objective of this work. The calibration and installation of the sensor is addressed. Defining the sensor output from real time loading distribution is shown. The evaluation of a full field data from a limited number of distributed sensor is studied. The damage prediction abilities of the long term self powered continuous monitoring system are evaluated. A slightly modified linear damage accumulation approach is then proposed using the damage index founded on continuum mechanics definition. The derivation of the damage index using sensor's output data is detailed with results from a set of laboratory tests, comparing the damage index prediction output from the sensor and values obtained using the complete time history data. Finally, a projection of the remaining life of tested specimens using reliability analysis was computed and it accuracy was evaluated by completing the test until failure and counting the total real observed cycles, showing very promising results for full field deployment and remaining life prediction with a reasonable accuracy.
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Title: Network issues for 3D wireless sensor networks
Creator: Cintrón, Fernando J.
Date: 2013
Collection: Electronic Theses & Dissertations
Description: Wireless sensor networks (WSN) give the opportunity to monitor the environment by performing sensing tasks in places that are difficult to reach or dangerous for humans. Nevertheless, topographical characteristics of such places and the sensor node's limitations introduce new issues in WSN performance. Additionally, in scenarios where sensors are moving or in rugged terrain, there is a high chance for them to be out of communication range, causing network connectivity problems. Hence,...
Show moreWireless sensor networks (WSN) give the opportunity to monitor the environment by performing sensing tasks in places that are difficult to reach or dangerous for humans. Nevertheless, topographical characteristics of such places and the sensor node's limitations introduce new issues in WSN performance. Additionally, in scenarios where sensors are moving or in rugged terrain, there is a high chance for them to be out of communication range, causing network connectivity problems. Hence, solutions have to take into consideration the aspect of the topography consisting of its three dimensional characteristics, namely, type of terrain, terrain unevenness, and obstacles.This dissertation discusses several research topics addressing issues relevant to WSN connectivity and area coverage problems. First, changes in sensor communication range are studied by varying sensors' heights relative to the surface. A novel communication technique that relies on the jumping capabilities of sensors is proposed. While the jumping sensor robots are airborne, the change in elevation enhances their ability for a short time to successfully communicate with other sensors that are out of communication range at the ground level. Field experiments were conducted and results show a considerable improvement in wireless communication ranges.Second, the impact of network connectivity and area coverage in a jumping sensor network is further studied. A Hopping Sensor Network Model is defined to increase sensing area coverage along with the enhancement of network connectivity. A Hopping Sensor Routing Protocol is designed from the model that balances the energy consumption on active jumping sensor nodes. Results from simulations show the increase in area coverage obtained from jumping sensor networks, and the effectiveness of the routing protocol to optimize communication paths while balancing energy depletion in the network.Third, a distributed wireless sensor network organization to establish a functional network, without requiring initial topology information, is presented. Two decentralized algorithms that use the jumping capabilities of sensors are designed for the discovery of isolated sensors. Simulation results show the success of the algorithms to enhance base station reachability. Additionally, cluster to cluster (C-to-C) packet forwarding schemes relying on boundary jumping sensor gateways are defined and analyzed, showing remarkable savings in network energy consumption.Fourth, in order to have a functional network, it is important to address connectivity issues in an application oriented manner. This work presents an efficient node redeployment-decision process to produce a functionally heterogeneous (jumping and non-jumping sensors) WSN with a performance guarantee. Network performance is defined as a network fitness formula considering the network Quality of Connectivity (QoC). Decision making algorithms for node relocation and topology defragmentation are presented, along with a discussion of their performance.Fifth, a multi-step procedure to produce a direction oriented jumping sensor network is presented. A jumping sensor robot approach is introduced for collecting and processing signal strength data into relative geographical orientation information. A directional-orientation decision algorithm is defined to process the orientation information. Furthermore, an error identification and correction procedure is established. This has proven to accurately fix the true orientation of the nodes by using only a pair of location aware beacon nodes.
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Title: Reliable and efficient communications in wireless sensor networks
Creator: Abdelhakim, Mai M.
Date: 2014
Collection: Electronic Theses & Dissertations
Description: Wireless sensor network (WSN) is a key technology for a wide range of military and civilian applications. Limited by the energy resources and processing capabilities of the sensor nodes, reliable and efficient communications in wireless sensor networks are challenging, especially when the sensors are deployed in hostile environments. This research aims to improve the reliability and efficiency of time-critical communications in WSNs, under both benign and hostile environments.We start with...
Show moreWireless sensor network (WSN) is a key technology for a wide range of military and civilian applications. Limited by the energy resources and processing capabilities of the sensor nodes, reliable and efficient communications in wireless sensor networks are challenging, especially when the sensors are deployed in hostile environments. This research aims to improve the reliability and efficiency of time-critical communications in WSNs, under both benign and hostile environments.We start with wireless sensor network with mobile access points (SENMA), where the mobile access points traverse the network to collect information from individual sensors. Due to its routing simplicity and energy efficiency, SENMA has attracted lots of attention from the research community. Here, we study reliable distributed detection in SENMA under Byzantine attacks, where some authenticated sensors are compromised to report fictitious information. The q-out-of-m rule is considered. It is popular in distributed detection and can achieve a good trade-off between the miss detection probability and the false alarm rate. However, a major limitation with this rule is that the optimal scheme parameters can only be obtained through exhaustive search. By exploiting the linear relationship between the scheme parameters and the network size, we propose simple but effective sub-optimal linear approaches. Then, for better flexibility and scalability, we derive a near-optimal closed-form solution based on the central limit theorem. It is proved that the false alarm rate of the q-out-of-m scheme diminishes exponentially as the network size increases, even if the percentage of malicious nodes remains fixed. This implies that large-scale sensor networks are more reliable under malicious attacks. To further improve the performance under time-varying attacks, we propose an effective malicious node detection scheme for adaptive data fusion; the proposed scheme is analyzed using the entropy-based trust model, and has shown to be optimal from the information theory point of view.Next, we observe that: while simplifying the routing process, a major limitation with SENMA is that data transmission is limited by the physical speed of the mobile access points (MAs) and the length of their trajectory, resulting in low throughput and large delay. To solve this problem, we propose a novel mobile access coordinated wireless sensor network (MC-WSN) architecture. The proposed MC-WSN can provide reliable and time-sensitive information exchange through hop number control, which is achieved by active network development and topology design. We discuss the optimal topology design for MC-WSN such that the average number of hops between the source and its nearest sink is minimized, and analyze the performance of MC-WSN in terms of throughput, stability, delay, and energy efficiency by exploiting tools in information theory, queuing theory, and radio energy dissipation model. It is shown that MC-WSN achieves much higher throughput and significantly lower delay and energy consumption than that of SENMA.Finally, motivated by the observation that the number of hops in data transmission has a direct impact on the network performance, we introduce the concept of the N-hop networks. Based on the N-hop concept, we propose a unified framework for wireless networks and discuss general network design criteria. The unified framework reflects the convergence of centralized and ad-hoc networks. It includes all exiting network models as special cases, and makes the analytical characterization of the network performance more tractable. Further study on N-hop networks will be conducted in our future research.
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Title: Assessment of ultrasonic guided wave inspection methods for structural health monitoring
Creator: Dib, Gerges
Date: 2014
Collection: Electronic Theses & Dissertations
Description: Structural health monitoring (SHM) has the potential to significantly increase safety and reduce manufacturing and maintenance costs of industrial structures. The use of piezoelectric material such as Lead-Zirconate-Titanate (PZT) in exciting and sensing ultrasonic guidedwaves for damage detection has become popular since its allows the rapid inspection of large areas in a structure using non-intrusive sensors. Ultrasonic guided waves interact with discontinuities in the structure, giving...
Show moreStructural health monitoring (SHM) has the potential to significantly increase safety and reduce manufacturing and maintenance costs of industrial structures. The use of piezoelectric material such as Lead-Zirconate-Titanate (PZT) in exciting and sensing ultrasonic guidedwaves for damage detection has become popular since its allows the rapid inspection of large areas in a structure using non-intrusive sensors. Ultrasonic guided waves interact with discontinuities in the structure, giving information about the potential presence of a damage, its size and location.The main concerns about using such methods is that PZT sensors and guided waves are affected by environmental conditions. The performance of the PZT sensors, in terms of their ability to detect damage, degrades over time and varies depending on current environmental conditions and surrounding, resulting in inconsistent measurements. This work gives a novel formulation of a model-based probability of detection method, which is able to quantifythe performance of guided wave inspection in a stochastically varying environment. An analytically and experimentally verified finite element model is used to generate data that represent the effects of varying environmental conditions. Then the stochastic approachis used to evaluate the probability of detection of cracks in riveted aluminum plates and delaminations in composite plates. Also, the performance of guided wave imaging algorithms under degrading PZT conditions is examined.Another concern is the ability to transfer data from the PZT sensors, which are per-manently located on the structure, to a computer where the data could be processed in real-time or near real-time. Wireless sensor networks (WSN) use low footprint smart sensor nodes that are permanently mounted on the structure. The sensor nodes have their own power supply and wireless communication devices to communicate with other sensor nodes or a base station. Wireless sensor node for guided waves require an actuation interfacesand high frequency sampling of the guided wave measurements. A proof-of-concept wireless sensor node prototype is developed for the data acquisition and actuation using PZT sensorsand guided waves.
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Title: Cost-aware routing protocols for location-privacy and efficiency in wireless sensor networks
Creator: Lightfoot, Leron J.
Date: 2015
Collection: Electronic Theses & Dissertations
Description: Wireless sensor networks (WSNs) can provide the world with a technology for real-time event monitoring for both military and civilian applications. One of the primary concerns that hinders the successful deployment of wireless sensor networks is how to provide adequate source and destination nodes location privacy. The privacy of the location is vital and highly jeopardized by the usage of wireless communications. While message content privacy can be ensured through message encryption, it is...
Show moreWireless sensor networks (WSNs) can provide the world with a technology for real-time event monitoring for both military and civilian applications. One of the primary concerns that hinders the successful deployment of wireless sensor networks is how to provide adequate source and destination nodes location privacy. The privacy of the location is vital and highly jeopardized by the usage of wireless communications. While message content privacy can be ensured through message encryption, it is much more difficult to adequately address the location privacy issue. For WSNs, location privacy service is further complicated by the fact that sensors consist of low-cost and energy efficient radio devices. Therefore, using computationally intensive cryptographic algorithms (such as public-key cryptosystems) and large scale broadcasting-based protocols are not suitable for WSNs.Many protocols have been proposed to provide location privacy but most of them are based on public-key cryptosystems, while others are either energy inefficient or have certain security flaws. After analyzing the security weaknesses of the existing schemes, we propose several creative and secure energy-aware routing protocols that can address the location privacy issue in WSNs. For source-location privacy, we propose 3 schemes. The first scheme routes each message to a randomly selected intermediate node (RSIN) before it is transmitted to the SINK node. However, this scheme can only provide local source-location privacy. In the second scheme, a network mixing ring (NMR) is proposed to provide network-level source-location privacy. The third scheme achieves network-level source-location privacy through a technique we call the Sink Toroidal Region (STaR) routing. For destination-location privacy, we propose the Bubble routing protocol and a series of R-STaR routing protocols. For each of these routing schemes, both security analysis using quantitative measurements and simulation results show that the proposed protocols are secure and energy-efficient.While providing location privacy is vital, prolonging the lifetime of the network can be a very essential component as well. In this dissertation, we propose a cluster-based energy-aware routing scheme, called Quad-Region Cluster-Head Selection (Q-ReCHS), which will prolong the network lifetime by evenly distributing the energy load among all the nodes. Our extensive simulation results on cluster-based routing demonstrates that our proposed Q-ReCHS scheme can out perform many of the existing schemes.
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Title: Cost-aware secure protocol design and analysis
Creator: Tang, Di
Date: 2015
Collection: Electronic Theses & Dissertations
Description: The recent technological progresses make sensor networks feasible to be widely used in both military and civilian applications. The nature of such networks makes energy consumption, communication delay and security the most essential issues for wireless sensor networks. However, these issues may be conflicting with each other. The existing works generally try to optimize one of these key issues without providing sufficient diversity and flexibility of various other requirements in protocol...
Show moreThe recent technological progresses make sensor networks feasible to be widely used in both military and civilian applications. The nature of such networks makes energy consumption, communication delay and security the most essential issues for wireless sensor networks. However, these issues may be conflicting with each other. The existing works generally try to optimize one of these key issues without providing sufficient diversity and flexibility of various other requirements in protocol design. In this dissertation, we investigate the relationship and design trade-offs among these conflicting issues.To deal with the lifetime optimization and security issues, we propose a novel secure and efficient Cost-Aware SEcure Routing (CASER) protocol to address them through two adjustable parameters: energy balance control (EBC) and security level to enforce energy balance and increase lifetime and determine the probabilistic distribution of random walking that provides routing security. We derive a tight numerical formula to quantitatively estimate the routing efficiency through the number of routing hops for a given routing security level. We also prove that CASER scheme can provide provable security under the quantitative security measurement criteria. Simulation results also show that the proposed CASER scheme can provide an excellent balance between routing efficiency and security while extending the network lifetime.We then discover that the energy consumption is severely disproportional to the uniform energy deployment for the given network topology. To solve this problem, we propose an efficient non-uniform energy deployment strategy to optimize the network lifetime and increase the message delivery ratio under the same energy resource and security requirements. Our theoretical analysis and OPNET simulation results demonstrate that the updated CASER protocol can provide an excellent trade-off between routing efficiency and energy consumption, while significantly extending the lifetime of the sensor networks in all scenarios. For the non-uniform energy deployment, our analysis shows that we can increase the lifetime and the total number of messages that can be delivered by more than four times under the same energy deployment, while achieving a high message delivery ratio and preventing routing traceback attacks.In WSNs, congestion introduces not only buffer overflow, but also communication delay for forwarding messages from the source node to the sink. We propose a novel congestion-aware routing (CAR) scheme to reduce the end-to-end communication delay while increasing network throughput. CAR employs two routing strategies, shortest path routing strategy and congestion-aware strategy, to achieve a trade-off between energy efficiency and communication delay. The OPNET simulation results demonstrate that the proposed routing scheme can reduce the end-to-end communication delay by 50% while increasing the network throughput by more than two times in our settings.People-centric urban sensing is envisioned as a novel urban sensing paradigm. Security, communication delay and delivery ratio are essential design issues in people-centric urban sensing networks. To address these three issues concurrently, we propose a novel delay-aware privacy preserving (DAPP) transmission scheme based on a combination of two-phase forwarding and secret sharing. The two-phase forwarding method detaches connection between the application data server and the source nodes, which renders it infeasible for the application data server to estimate source node identities. The underlying secret sharing scheme and dynamic pseudonym ensure confidentiality of the collected data and anonymity of participating users. DAPP provides a framework to achieve a design trade-off among security, communication delay and delivery ratio. The security analysis demonstrates that DAPP can preserve location privacy while defending against side information attacks. Theoretical analysis and simulation results show that our proposed algorithms can provide a flexible and diverse security design option for routing and data forwarding algorithm design.
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Title: Advanced data analysis framework for damage identification in civil infrastructure based on self-powered sensing
Creator: Alavi, Amir Hossein
Date: 2016
Collection: Electronic Theses & Dissertations
Description: "This interdisciplinary research proposes an advanced data analysis framework for civil infrastructure/structural health monitoring (I/SHM) based on a pioneering self-powered sensing technology. The current work characterizes the performance of a fairly new class of self-powered sensors for specific application problems with complex behavior. The proposed health monitoring systems are established through the integration of statistical, artificial intelligence and finite element methods....
Show more"This interdisciplinary research proposes an advanced data analysis framework for civil infrastructure/structural health monitoring (I/SHM) based on a pioneering self-powered sensing technology. The current work characterizes the performance of a fairly new class of self-powered sensors for specific application problems with complex behavior. The proposed health monitoring systems are established through the integration of statistical, artificial intelligence and finite element methods. Different infrastructure systems with various damage types are analyzed. A new probabilistic artificial intelligence-based damage detection technique is developed that hybridizes genetic programming and logistic regression algorithms. The proposed multi-class classification system assigns probabilities to model scores to detect damage progression. A probabilistic neural network method based on Bayesian theory is further introduced to improve the damage detection accuracy. Data obtained from the finite element simulations and experimental study of hybrid sensor networks is used to calibrate the data interpretation algorithms. The network architecture comprises self-powered sensors that use the electrical energy directly harvested by piezoelectric ceramic Lead Zirconate Titanate (PZT) transducers. The beauty of this so-called self-powered monitoring system is that the operating power for the smart sensors directly comes from the signal being monitored. An advantage of using these sensors is that there is no need to directly measure the absolute value of strain in order to estimate damage. In fact, the proposed self-sustained sensing systems use the sensor output to relate the variation rate of strain distributions to the rate of damage. The proposed data analysis framework consists of multilevel strategies for structural/infrastructure damage identification through: (a) analysis of individual self-powered strain sensors, (b) data fusion in a network of self-powered strain sensors, and (c) data analysis in a hybrid network of self-powered accelerometer and strain sensors. For each of these levels, several damage indicator features are extracted upon the simulation of the compressed data stored in memory chips of the self-powered sensors. A new data fusion concept based on the effect of group of sensors, termed as "group effect", is proposed. The goal is to improve the damage detection performance through spatial measurements over structures. Moreover, combination of the data from a network of accelerometer and strain sensors results in developing an integrated global-local damage detection approach. The investigated cases are crack growth detection in steel plates under a uniaxial tension mode, distortion-induced fatigue cracking in steel bridge girders, continuous health monitoring of pavement systems, failure of simply supported beam under three-point bending, and failure of gusset plate of the I-35W highway bridge in Minneapolis, Minnesota. 3D dynamic finite element models are developed for each of the cases. The experimental studies are carried out on a steel plate subjected to an in-plane tension, a steel plate with bolted connections, and on asphalt concrete specimens in three-point bending mode. PZT-5A ceramic discs and PZT-5H bimorph accelerometers are placed on the surface of the plates to measure the delivered voltage in each damage phase. For the asphalt experiments, a new miniaturized spherical packaging system is designed and tested to protect the PZT ceramic discs embedded inside the specimen. Uncertainty analyses are performed through the contamination of the damage indicator features with different noise levels. The results indicate that the proposed I/SHM systems are efficiently capable of detecting different damage states in spite of high-level noise contamination."--Pages ii-iii.
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