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Ali, Mahmood, and Kumar Ravula Sai. "Real-Time Support and Energy Efficiency In Wireless Sensor Networks." Thesis, Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-1150.
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Wireless sensors nodes are made up of small electronic devices which are capable of sensing, computing and transmitting data from harsh physical environments like a surveillance field. These sensor nodes majorly depend on batteries for energy, which get depleted at a faster rate because of the computation and communication operations they have to perform. Communication protocols can be designed to make efficient utilization of energy resources of a sensor node and to obtain real time functionality. A set of previously reported routing and MAC (Medium Access Control) layer protocols has abilities to achieve energy efficiency and supports real-time functionality. A detailed study of these protocols has been carried out and comparison tables give an overview of the protocol’s performance on some factors like latency, scalability and energy awareness. Conclusions have been drawn using the comparison table parameters of how the protocol performs when utilized for a surveillance application and what kind of tradeoff they show.
The conclusions and tabular information drawn here are from our theoretical analysis of protocols referred from journals; there is no simulation work done in this thesis.
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Doddapaneni, Krishna. "Energy aware performance evaluation of WSNs." Thesis, Middlesex University, 2014. http://eprints.mdx.ac.uk/17460/.
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Distributed sensor networks have been discussed for more than 30 years, but the vision of Wireless Sensor Networks (WSNs) has been brought into reality only by the rapid advancements in the areas of sensor design, information technologies, and wireless networks that have paved the way for the proliferation of WSNs. The unique characteristics of sensor networks introduce new challenges, amongst which prolonging the sensor lifetime is the most important. Energy-efficient solutions are required for each aspect of WSN design to deliver the potential advantages of the WSN phenomenon, hence in both existing and future solutions for WSNs, energy efficiency is a grand challenge. The main contribution of this thesis is to present an approach considering the collaborative nature of WSNs and its correlation characteristics, providing a tool which considers issues from physical to application layer together as entities to enable the framework which facilitates the performance evaluation of WSNs. The simulation approach considered provides a clear separation of concerns amongst software architecture of the applications, the hardware configuration and the WSN deployment unlike the existing tools for evaluation. The reuse of models across projects and organizations is also promoted while realistic WSN lifetime estimations and performance evaluations are possible in attempts of improving performance and maximizing the lifetime of the network. In this study, simulations are carried out with careful assumptions for various layers taking into account the real time characteristics of WSN. The sensitivity of WSN systems are mainly due to their fragile nature when energy consumption is considered. The case studies presented demonstrate the importance of various parameters considered in this study. Simulation-based studies are presented, taking into account the realistic settings from each layer of the protocol stack. Physical environment is considered as well. The performance of the layered protocol stack in realistic settings reveals several important interactions between different layers. These interactions are especially important for the design of WSNs in terms of maximizing the lifetime of the network.
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Peng, Bo. "Energy-efficient geographic routing in realistic WSNs." Thesis, University of Leeds, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.522967.
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Toussi, Ahora Mehdi. "Energy and QoS aware routing for WSNs." Thesis, Kingston University, 2017. http://eprints.kingston.ac.uk/41130/.
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The advancement of Wireless Sensor Networks (WSNs), necessitate optimisation of their algorithms and their performance. More specifically, network coverage and preservation of nodes energy to increase the network's lifetime are among the core objectives of routing and clustering methods. This thesis constitutes of a literature review of WSNs' routing protocols in a categorised manner followed by proposing an energy efficient and QoS aware paradigm (PUSH) for flat network that outperform other similar paradigms in terms of collective delay and energy dissipation within the network. We have proposed a new clustering model, known as Energy Aware and Address Free Clustering (EAAFC) in which, no global addressing is required. In other words, nodes are assigned with an ID, based on local information. EAAFC clusters nodes with minimum number of cluster heads which in turn results in less in network energy consumption. Cluster heads are then re-elected frequently based on nodes' energy and distribution. EAAFC does not require geographical location of nodes nor time synchronisation. We compare performance results of our proposed clustering model, against two of well received algorithms, namely LEACH and EECF to demonstrate the advantages of EAAFC. In chapters 1 and 2, the major routing protocols have been studied over the years of research and strength and weaknesses of each protocol has been scrutinised. Further, objectives, motivation and methodology of the research are discussed. In chapter 3 and 4 the proposed routing paradigm for flat networks (PUSH) as well as the clustering protocol, EAAFC, and its advantages over other protocols is discussed in depth. Several scenarios based on similar well-known routing protocols have been implemented and tested to use as comparison and to evaluate the performance of paradigm and protocol presented in this thesis. These scenarios have been implemented in the simulator environment. The simulation results confirm the theoretic evaluation and support that PUSH and EAAFC outperforms the other protocols in compared criteria as they can achieve less latency, better coverage, preserve more energy and achieve more equally distributed energy dissipation across the network which result in longer network life time and full functionality.
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Fiedor, Tomáš. "A Decision Procedure for the WSkS Logic." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2014. http://www.nusl.cz/ntk/nusl-236065.
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Různé typy logik se často používají jako prostředky pro formální specifikaci systémů. Slabá monadická logika druhého řádu s k následníky (WSkS) je jednou z nich a byť má poměrně velkou vyjadřovací sílu, stále je rozhodnutelná. Ačkoliv složitost testování splnitelnosti WSkS formule není ani ve třídě ELEMENTARY, tak existují přístupy založené na deterministických automatech, implementované např. v nástroji MONA, které efektně řeší omezenou třídu praktických příkladů, nicméně nefungují pro jiné. Tato práce rozšiřuje třídu prakticky řešitelných příkladů, a to tak, že využívá nedávno vyvinutých technik pro efektní manipulaci s nedeterministickými automaty (jako je například testování universality jazyka pomocí přístupu založeného na antichainech) a navrhuje novou rozhodovací proceduru pro WSkS využívající právě nedeterministické automaty. Procedura je implementována a ve srovnání s nástrojem MONA dosahuje v některých případech řádově lepších výsledků.
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Kamsuvan, Thanisara. "Power management in Wireless Sensor Networks (WSNs)." Thesis, Brunel University, 2016. http://bura.brunel.ac.uk/handle/2438/13499.
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The wireless sensor network (WSN) is increasingly used in many areas nowadays. It can be applied to provide the solutions to environmental problems, help increasing security and safety systems, and make the detection of the problems more efficient, e.g. the earthquake or tidal wave, which will harmful to humans. The WNS is durable and resistant to all types of terrain and climate, but while the WSN system is more and more widespread, one of the obstacles hindering the growth of this technology and the demand for WSN applications is the limited battery lifespan. Consequently, there is a significant requirement for techniques for prolonging the battery’s lifespan. Therefore, one potential solution is to use alternative energy sources combined with the sensor nodes in WSN, specifically energy harvesting from existing environmental sources. This research project reviews the characteristics of each kind of energy harvesting, understanding the various energy sources (solar energy, vibration energy and wind power), including wireless power transfer (WPT) by using electromagnetic (EM) radiation energy transfer or RF radio-frequency emission and magnetic coupled energy transfer. They are adopted for extending node’s life in the WSN, based on published information. Then it compares these diverse alternative energy methods and identifies for the most suitable energy harvesting method for application to wireless sensor nodes in order to prolong the lifespan of the battery. The major findings from the researcher include that wireless power transfer energy harvesting (WPT) using the magnetic field is the most appropriate tool for extending the lifespan of the WSN system. In addition, the author also designed an experiment to test this alternative energy, achieving by modelling the wireless power transfer with four coils. From the experimental results, it can be seen that the WPT technique using energy harvesting with magnetic inductive source can be applied to prolong the lifespan of the WSN system.
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Drira, Wassim. "Secure collection and data management system for WSNs." Phd thesis, Institut National des Télécommunications, 2012. http://tel.archives-ouvertes.fr/tel-00814664.
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Nowadays, each user or organization is already connected to a large number of sensor nodes which generate a substantial amount of data, making their management not an obvious issue. In addition, these data can be confidential. For these reasons, developing a secure system managing the data from heterogeneous sensor nodes is a real need. In the first part, we developed a composite-based middleware for wireless sensor networks to communicate with the physical sensors for storing, processing, indexing, analyzing and generating alerts on those sensors data. Each composite is connected to a physical node or used to aggregate data from different composites. Each physical node communicating with the middleware is setup as a composite. The middleware has been used in the context of the European project Mobesens in order to manage data from a sensor network for monitoring water quality. In the second part of the thesis, we proposed a new hybrid authentication and key establishment scheme between senor nodes (SN), gateways (MN) and the middleware (SS). It is based on two protocols. The first protocol intent is the mutual authentication between SS and MN, on providing an asymmetric pair of keys for MN, and on establishing a pairwise key between them. The second protocol aims at authenticating them, and establishing a group key and pairwise keys between SN and the two others. The middleware has been generalized in the third part in order to provide a private space for multi-organization or -user to manage his sensors data using cloud computing. Next, we expanded the composite with gadgets to share securely sensor data in order to provide a secure social sensor network
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Rukpakavong, Wilawan. "Energy-efficient and lifetime aware routing in WSNs." Thesis, Loughborough University, 2014. https://dspace.lboro.ac.uk/2134/14497.
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Network lifetime is an important performance metric in Wireless Sensor Networks (WSNs). Transmission Power Control (TPC) is a well-established method to minimise energy consumption in transmission in order to extend node lifetime and, consequently, lead to solutions that help extend network lifetime. The accurate lifetime estimation of sensor nodes is useful for routing to make more energy-efficient decisions and prolong lifetime. This research proposes an Energy-Efficient TPC (EETPC) mechanism using the measured Received Signal Strength (RSS) to calculate the ideal transmission power. This includes the investigation of the impact factors on RSS, such as distance, height above ground, multipath environment, the capability of node, noise and interference, and temperature. Furthermore, a Dynamic Node Lifetime Estimation (DNLE) technique for WSNs is also presented, including the impact factors on node lifetime, such as battery type, model, brand, self-discharge, discharge rate, age, charge cycles, and temperature. In addition, an Energy-Efficient and Lifetime Aware Routing (EELAR) algorithm is designed and developed for prolonging network lifetime in multihop WSNs. The proposed routing algorithm includes transmission power and lifetime metrics for path selection in addition to the Expected Transmission Count (ETX) metric. Both simulation and real hardware testbed experiments are used to verify the effectiveness of the proposed schemes. The simulation experiments run on the AVRORA simulator for two hardware platforms: Mica2 and MicaZ. The testbed experiments run on two real hardware platforms: the N740 NanoSensor and Mica2. The corresponding implementations are on two operating systems: Contiki and TinyOS. The proposed TPC mechanism covers those investigated factors and gives an overall performance better than the existing techniques, i.e. it gives lower packet loss and power consumption rates, while delays do not significantly increase. It can be applied for single-hop with multihoming and multihop networks. Using the DNLE technique, node lifetime can be predicted more accurately, which can be applied for both static and dynamic loads. EELAR gives the best performance on packet loss rate, average node lifetime and network lifetime compared to the other algorithms and no significant difference is found between each algorithm with the packet delay.
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Maheshwari, Hemat Kumar. "Optimizing range aware localization in wireless sensor networks (WSNs)." Thesis, University of Leeds, 2011. http://etheses.whiterose.ac.uk/1743/.
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The adoption of wireless sensor networks (WSNs) in numerous emerging applications have prevailed us to realize that smart living is no longer an imagination, it already exists. In emerging applications, localization is an essential function so that all the sensed information can be responded carefully. Among the range free and range aware localization, range aware localization has been the most promising for fine-grained accuracy. Range aware localization has two phases, ranging and localization. Location errors always exist no matter which ranging or localization technique is used. Therefore, there is a need to optimize range aware localization for better performance. Firstly, this thesis investigates the performance of time-of-flight (ToF) and received signal strength (RSS) based ranging using IEEE 802.1.5.4 compliant WSNs nodes in outdoor and indoor for both line-of-sight (LOS) and non-line-of-sight (NLOS) paths. The fundamental Cram´er- Rao lower bound (CRLB) on ToF and RSS ranging performance is compared with the performance limits of IEEE 802.1.5.4 compliant modules. The experimental results for both outdoor and indoor LOS path demonstrated that RSS is a good candidate for range estimation at ranges less than 7m. Further analysis over long range demonstrates that ToF is a good candidate for range estimation at greater than 7m. In addition to the ranging error, another well-known error mechanism is the poor geometric anchors placement, which can significantly degrade localization performance. In the Global Positioning System (GPS) community, geometric dilution of precision (GDOP) is a well-known problem which illustrates the geometric configuration impacting localization accuracy. To analyse the impact of anchor placement on localization, performance of three lateration based approaches is compared in a cooperative fashion. Through results, It is confirmed that lateration based approaches presents a trade-off for complex computation, thus energy consumption and accuracy. It provided the needed motivation to investigate and optimize the anchor placement for better localization accuracy. The impact of anchor placement for quality reliable localization has been limited to 3-4 anchors with respect to a single subject node for 2-D. Therefore, to model reality most clearly, it makes sense to step beyond the easy and secure reach of unrealistic and mostly researched 2-dimensional representations to the pragmatic world in 3-dimensional visualization. In addition, previous work for optimal anchors placement has been limited to only additive noise. To the best of our knowledge, there is no study of optimization of anchor placement with respect to the multiplicative noise. Therefore, the optimal anchor placements are determined for both signal models based on minimum mean CRLB (m-CRLB). It is confirmed that optimal anchor placement for both signal models is different and have a serious impact on localization accuracy. The optimal anchor placement is further verified by developing a new Range Aware Localization System (RALS) using IEEE 802.15.4 compliant devices. In LOS, quality reliable localization performance can be achieved but as propagation criteria change from LOS to NLOS, localization performance also changes. In an indoor environment, localization performance degrades significantly due to multipath components. To overcome, a new 3-D scheme named Range Estimate Threshold (RET) is proposed which exploits field dimensions based on the signal model and optimal anchor placement to define a threshold. Based on the defined threshold, RET mitigates the poor range estimates from Measured Estimation (ME) for better localization accuracy. The ramification of RET on ME is explored through additive, multiplicative and log-normal shadowing models. It is confirmed that localization based on RET compared to ME showed improved accuracy.
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Khemapech, Ittipong. "PoRAP : an energy aware protocol for cyclic monitoring WSNs." Thesis, University of St Andrews, 2011. http://hdl.handle.net/10023/1899.
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This work starts from the proposition that it is beneficial to conserve communication energy in Wireless Sensor Networks (WSNs). For WSNs there is an added incentive for energy-efficient communication. The power supply of a sensor is often finite and small. Replenishing the power may be impractical and is likely to be costly. Wireless Sensor Networks are an important area of research. Data about the physical environment may be collected from hostile or friendly environments. Data is then transmitted to a destination without the need for communication cables. There are power and resource constraints upon WSNs, in addition WSN networks are often application specific. Different applications will often have different requirements. Further, WSNs are a shared medium system. The features of the MAC (Medium Access Control) protocol together with the application behaviour shape the communication states of the node. As each of these states have different power requirements the MAC protocol impacts upon the operation and power consumption efficiency. This work focuses on the development of an energy conservation protocol for WSNs where direct communication between sources and a base station is feasible. Whilst the multi-hop approach has been regarded as the underlying communication paradigm in WSNs, there are some scenarios where direct communication is applicable and a significant amount of communication energy can be saved. The Power & Reliability Aware Protocol has been developed. Its main objectives are to provide efficient data communication by means of energy conservation without sacrificing required reliability. This has been achieved by using direct communication, adaptive power adaptation and intelligent scheduling. The results of simulations illustrate the significance of communication energy and adaptive transmission. The relationship between Received Signal Strength Indicator (RSSI) and Packet Reception Rate (PRR) metrics is established and used to identify when power adaptation is required. The experimental results demonstrate an optimal region where lower power can be used without further reduction in the PRR. Communication delays depend upon the packet size whilst two-way propagation delay is very small. Accurate scheduling is achieved through monitoring the clock drift. A set of experiments were carried out to study benefits of direct vs. multi-hop communication. Significant transmitting current can be conserved if the direct communication is used. PoRAP is compared to Sensor-MAC (S-MAC), Berkeley-MAC (B-MAC) and Carrier Sense Multiple Access (CSMA). Parameter settings used in the Great Duck Island (GDI) a production habitat monitoring WSNs were applied. PoRAP consumes the least amount of energy.
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Katerinchuk, Valeri. "Heuristic multicast routing algorithms in WSNs with incomplete network knowledge." Thesis, King's College London (University of London), 2018. https://kclpure.kcl.ac.uk/portal/en/theses/heuristic-multicast-routing-algorithms-in-wsns-with-incomplete-network-knowledge(91a1331e-b2ef-40ba-91f6-7eb03e6296cb).html.
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Ghaddar, Alia. "Improving the quality of aggregation using data analysis in WSNs." Thesis, Lille 1, 2011. http://www.theses.fr/2011LIL10068/document.
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L'adoption des réseaux de capteurs sans fil (WSNs) dans divers secteurs continuent à croître, comme la médecine, la domotique, le contrôle de processus industriels, la localisation des objets, etc. Cela revient à l'émergence de capteurs de plus en plus petits et de plus en plus intelligents dans notre vie quotidienne. Ces dispositifs interagissent avec l'environnement ou d'autres périphériques, pour analyser les données et produire de l'information. En plus de créer de l'information, ils permettent, une intégration transparente de la technologie virtuelle autour de nous. En effet, ces objets sont de faible puissance et fonctionnent sur batterie. Ils sont souvent utilisé dans des zones géographiques dangereuse et peu accessible, tels que les volcans actifs, les champs de bataille, ou après une catastrophe naturelle etc. Ces zones critiques rendent le remplacement ou la recharge des batteries de chaque capteur difficile voire impossible. Ainsi, leur consommation énergétique devient le principale verrou technologique empêchant leur déploiement à grande échelle. Nous sommes intéressés à partie la plus consommatrice d'énergie dans les réseaux de capteurs: la communication ou l'envoi/la réception de données. Nous proposons des méthodes pour réduire les transmissions des nœuds en réduisant le volume de données à transmettre. Notre travail s'articule autour de trois axes fondamentaux: la prédiction des données, la détection de similarité des données et la détection des comportements anormauxThe promise and application domain of Wireless Sensor Networks (WSNs) continue to grow such as health care, home automation, industry process control, object tracking, etc. This is due to the emergence of embedded, small and intelligent sensor devices in our everyday life. These devices are getting smarter with their capability to interact with the environment or other devices, to analyze data and to make decisions. They have made it possible not only gather data from the environment, but also to bridge the physical and virtual worlds, assist people in their activities, while achieving transparent integration of the wireless technology around us. Along with this promising glory for WSNs, there are however, several challenges facing their deployments and functionality, especially for battery-operated sensor networks. For these networks, the power consumption is the most important challenge. In fact, most of WSNs are composed of low-power, battery-operated sensor nodes that are expected to replace human activities in many critical places, such as disaster relief terrains, active volcanoes, battlefields, difficult terrain border lands, etc. This makes their battery replacement or recharging a non-trivial task. We are concerned with the most energy consuming part of these networks, that is the communication. We propose methods to reduce the cost of transmission in energy-constrained sensor nodes. For this purpose, we observe the way data is collected and processed to save energy during transmission. Our work is build on three basic axis: data estimation, data similarity detection and abnormal behaviors detection
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Wen, Wen. "Energy Efficient Secure Key Management Schemes for WSNs and IoT." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/35257.
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Secret sharing is critical to most applications making use of security and remains one of the most challenging research areas in modern cryptography. In this thesis, we propose a novel efficient multi-secret sharing scheme based on the Chinese remainder theorem (CRT) with two verification methods, while the previous works are mostly based on the Lagrange polynomial.
Key management schemes play an important role in communication security in Wireless Sensor Networks (WSNs). While the previous works mainly targeting on two different types of WSNs: distributed and hieratical, in this thesis, we propose our flexible WSN key management scheme, which is based on (n,t,n) multi-secret sharing technique, to provide a key management solution for heterogeneous architecture. The powerful key managers are responsible for most of the communicational and computational workload. They can provide Peer-to-Peer pair-wise keys for a pair of sensors to establish a secure communication session, and in the same time, they can also form communication clusters as cluster heads according to different application requirements.
Internet of Things (IoT) becomes more and more popular and practical in recent years. Considering the diversity of the devices and the application scenarios, it is extremely hard to couple two devices or sub-networks with different communication and computation resources. In this thesis, we propose novel key agreement schemes based on (n,t,n) multi-secret sharing techniques for IoT in order to achieve light weighted key exchange while using Host Identity Protocol (HIP). We refer the new schemes as HIP-MEXs with different underlying multi-secret sharing techniques. We analyzed the computational and communication costs of the extremely resource constrained device which is referred to as Initiator, and CRT based HIP-MEX successfully outsource the heavy workload to the proxy, which are considered more powerful, when establishing new secret key.
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Altaf, Faisal. "Modeling and Event-Triggered Control ofMultiple 3D Tower Cranes over WSNs." Thesis, KTH, Reglerteknik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-105122.
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Wireless control of 3D tower cranes is a topic of great industrial significance as it offers greater flexibility and lower maintenance cost. But the reduction in shared network resource utilization and the desired level of control performance against packet losses and delays are main concerns. Our first aim is to develop a mathematical model of the 3D tower crane for the control design purpose. The second aim is to design a model-based eventtriggered controller for wireless control of multiple 3D tower cranes to asymptotically track step reference inputs. The controller and cranes are connected in a star topology over simulated wireless sensor network with IEEE 802.15.4 MAC protocol for channel access. The third aim is to numerically evaluate and compare the performance of the event-triggered controller with that of a periodic controller under network induced delays, packet dropouts and with respect to scalability and the effect of MAC protocol on the stability. The dynamic model for the 3D tower crane has been identified through physical modeling followed by lumped parametric estimation. The proposed event-triggered control policy for tracking problem uses the integral control structure for which theoretical results have been derived using Lyapunov input-to-state stability theorem. Under nominal network settings, the event-triggered controller reduces the network resource utilization by 4 times but achieves almost the same control performance as compared to periodic controller executions. The network cost under event-triggered control policy not only depends on the point network induced delay enters into the system, but also increases almost monotonically with it. The event-triggered control policy utilizes the lower communication cost as compared to periodic case only up to certain amount of delay in a loop and hence must only be preferred over periodic case after considering the level and location of delay in the system. Under these conditions, up to 13 crane tasks are schedulable over network under event-triggered control policy using CSMA/CA random access. All the simulations have been done in MATLAB® Simulink using TrueTime toolbox.
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Kumbakonam, Chandrasekar Ramalingam. "PROVIZ: an integrated graphical programming, visualization and scripting framework for WSNs." Thesis, Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47633.
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Wireless Sensor Networks (WSNs) are rapidly gaining popularity in various critical domains like health care, critical infrastructure, and climate monitoring, where application builders have diversified development needs. Independent of the functionalities provided by the WSN applications, many of the developers use visualization, simulation, and programming tools. However, these tools are designed as separate stand-alone applications, which force developers to use multiple tools. This situation often poses confusion and hampers an efficient development experience. To avoid the complexity of using multiple tools, a new, extensible, multi-platform, scalable, and open-source framework called PROVIZ is designed. PROVIZ is an integrated visualization and programming framework with the following features: PROVIZ 1) visualizes sensor nodes and WSN traffic by parsing the data received either from a packet sniffer (e.g., a sensor-based sniffer, or a commercial TI SmartRF 802.15.4 packet sniffer), or from a simulator (e.g., OMNeT); 2) visualizes a heterogeneous WSN consisting of different sensor nodes sending packets with different packet payload formats; and 3) provides a programming framework, which provides a graphical and script-based programming functionality, for developing WSN applications. Also, PROVIZ includes built-in extensible visual demo deployment capabilities that allow users to quickly craft network scenarios and share them with other users. Additionally, a secure and energy efficient wireless code dissemination protocol, named SIMAGE, was developed. SIMAGE is used by PROVIZ to wirelessly reprogram the sensor nodes. SIMAGE uses a link quality cognizant adaptive packet-sizing technique along with energy-efficient encryption protocols for secure and efficient code dissemination. In this thesis, the various features of PROVIZ's visualization and programming framework are explained, the functionality and performance of SIMAGE protocol is described, an example WSN security attack scenario is analyzed, and how PROVIZ can be used as a visual debugging tool to identify the security attack and aid in providing a software fix are discussed.
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Caione, Carlo <1984>. "Ultra-low power WSNs: distributed signal processing and dynamic resource management." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amsdottorato.unibo.it/5397/.
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This thesis presents several data processing and compression techniques capable of addressing the strict requirements of wireless sensor networks. After introducing a general overview of sensor networks, the energy problem is introduced, dividing the different energy reduction approaches according to the different subsystem they try to optimize.
To manage the complexity brought by these techniques, a quick overview of the most common middlewares for WSNs is given, describing in detail SPINE2, a framework for data processing in the node environment.
The focus is then shifted on the in-network aggregation techniques, used to reduce data sent by the network nodes trying to prolong the network lifetime as long as possible. Among the several techniques, the most promising approach is the Compressive Sensing (CS). To investigate this technique, a practical implementation of the algorithm is compared against a simpler aggregation scheme, deriving a mixed algorithm able to successfully reduce the power consumption.
The analysis moves from compression implemented on single nodes to CS for signal ensembles, trying to exploit the correlations among sensors and nodes to improve compression and reconstruction quality.
The two main techniques for signal ensembles, Distributed CS (DCS) and Kronecker CS (KCS), are introduced and compared against a common set of data gathered by real deployments. The best trade-off between reconstruction quality and power consumption is then investigated.
The usage of CS is also addressed when the signal of interest is sampled at a Sub-Nyquist rate, evaluating the reconstruction performance.
Finally the group sparsity CS (GS-CS) is compared to another well-known technique for reconstruction of signals from an highly sub-sampled version. These two frameworks are compared again against a real data-set and an insightful analysis of the trade-off between reconstruction quality and lifetime is given.
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Cano, Bastidas Cristina. "A low power listening with wake up after transmissions MAC protocol for WSNs." Doctoral thesis, Universitat Pompeu Fabra, 2011. http://hdl.handle.net/10803/22717.
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In the last few years Wireless Sensor Networks (WSNs) have become an interesting field of research mainly due to the challenges and constraints of their design and the broad range of potential applications they can provide. One of the most important constraints is the limited energy resources of the sensor nodes that directly influences the design of the Medium Access Control (MAC) layer, as it is the responsible of controlling the transceiver that is the most consuming component of a sensor node. In this thesis the limitations of preamble sampling, one of the most well-known MAC protocols for WSNs, have been studied. Moreover, a new approach, called Low power listening with Wake up after Transmissions MAC (LWT-MAC), has been designed with the goal to overcome preamble sampling limitations while maintaining its reduced energy consumption and simplicity. The performance results obtained have shown that the LWT-MAC protocol is able to significantly improve the performance of WSNs.Les xarxes de sensors sense fils han esdevingut una interessant àrea de recerca degut als reptes que presenta el seu disseny i a la gran quantitat d’aplicacions potencials que poden proporcionar. Un dels principals problemes d’aquestes xarxes és la limitació en els recursos energètics dels nodes sensors, cosa que afecta directament al disseny del nivell Medium Access Control (MAC), degut a què és el responsable de controlar la ràdio, el component de major consum energètic d’un node sensor. En aquesta tesi s’estudien les limitacions d'un dels protocols MAC per xarxes de sensors més conegut: preamble sampling. A més, s’ha dissenyat un nou protocol, anomenat Low power listening with Wake up after Transmissions MAC (LWT-MAC), amb l’objectiu de reduir les limitacions de preamble sampling però mantenint el seu baix consum energètic i la seva simplicitat. Els resultats obtinguts mostren que el protocol LWT-MAC és capaç de millorar de forma significativa el rendiment de la xarxa.
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Mitsui, Shin-ichi, Hiroshi Hasegawa, and Ken-ichi Sato. "Hierarchical Optical Path Cross-Connect Node Architecture Using WSS/WBSS." IEEE, 2008. http://hdl.handle.net/2237/12097.
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Hernandez, Herrera Rosa Idalia. "Étapes précoces de l'infection virale du WSS chez la crevette." Montpellier 2, 2008. http://www.theses.fr/2008MON20012.
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Les crevettes de grande taille de la famille des Penaeidae constituent le premier produit aquacole en valeur commerciale à l'échelle planétaire. Elles sont produites à 99% dans les pays en voie de développement de la ceinture sub-équatoriale. Parmi les causes limitant leur production, le WSS est l'agent pathogène viralayant provoqué le plus des pertes dans le monde. Notre étude a été orientée vers la reconnaissance des premiers stades de l'infection, susceptibles d'être la cible d'une action prophylactique. Nous avons testé l'utilisation d'une lignée cellulaire de poisson SSN-1 afin d'étudier les possibilités d'un développement in vitro. Seules des particules défectives ont été produites confirmant la haute spécificité des infections à virus de crustacés. Les recherches en microscopie électronique ont montré une similarité structurale du WSSV avec les virus (B, B2 et Baculo-B) des crabes. Ceci suggère que ces agents (B2 et WSSV) seraient tout deux de la famille des Nimaviridae et du genre Whispovirus. La comparaison avec le virus B2 permet de comprendre le rôle clef joué par la partie caudale de ces virus dans l'infection par son attachement à la membrane plasmique lors de l'infection chez son hôte spécifiquePenaeid family shrimp constitute the first aquaculture product in the world in terms of commercial value. They are produced in third world countries of the sub-equatorial belt. Among the causes limiting their production, one is the presence of the WSSV (White Spot Syndrome Virus), a pathogenic agent that produces massive mortality. Our aim was to investigate the first stages of the viral infection, in order to be used as target of prophylactic actions. A fish cell line (SSN-1) was used as model to tentatively develop in vitro studies. Only defective particles were produced confirming the high specificity to crustacea of the infection with crustacean virus. Electron microscopy showed structural similarities between the WSSV and B, B2 and Baculo-B viruses of crabs. This suggests B2 may belong also to the family Nimaviridae, genus Whispovirus. This comparison with B2 virus gives the possibility to understand the role played by the tail-like extension of these viruses in the infectious process by attachment to the plasmic membrane at the beginning of the infection in its specific host
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Williams, Matthew. "Marginaliserade aktörers inverkan på reglering och styrning av Internet : World Summit on the Information Society:s bidrag till nätets diskurs." Thesis, Högskolan Väst, Avd för socialpedagogik och sociologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-5157.
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Sedan nätets begynnelse har regleringen och styrningen av Internet präglats av en västcentrisk och teknomeritokratisk diskurs som i mångt och mycket har exkluderat en stor del av världen från att aktivt delta i informationssamhällets utformning. I denna ordning har den amerikanska staten haft en priviligierad ställning genom dess indirekta kontroll över de s.k. strategiska resurserna, dvs. IP-adresser och ‖roten‖ i domännamnsystemet, via kontraktet mellan "Department of Commerce" och organisationen "Internet Corporation for Assigned Names and Numbers" (ICANN). Därtill fanns det en latent konflikt mellan USA och Internetsamfundet, å ena sidan, och Förenta nationerna och dess medlemsstater, å andra sidan, såtillvida att den institutionella utformningen vilade på amerikansk civilrättslig grund och inte mellanstatliga traktat, en av grundvalarna för det geopolitiska systemet. FN anordnade således konferenserna om det globala informationssamhället, "World Summit on the Information Society" (WSIS), i Genève 2003 respektive Tunis 2005 för att lyfta frågorna om en internationellt legitim regim för Internets styrning och den ojämna fördelningen av information- och kommunikationsteknologi (IKT) mellan rika industriländer och fattiga utvecklingsländer. Syftet med denna uppsats är att undersöka om toppmötena om det globala informationssamhället lyckades i uppsåtet att ge marginaliserade aktörer, i första hand FN-systemet och utvecklingsländerna, strukturellt inflytande gällande styrningen av Internet samt tillfört dimensioner av digital solidaritet och internationalisering till den diskurs som historiskt har dominerats av västerlandet, i synnerhet USA. Med utgångspunkt från Michel Foucaults maktbegrepp söks slutdokumenten från WSIS-processen på diskursiva brott som skulle kunna tyda på skiften i maktstrukturerna till de marginaliserade aktörernas fördel. De diskursiva brott som kan tydas i WSIS-dokumenten gäller i första hand begreppet "den digitala klyftan" och medvetandegörandet av bistånds- och utvecklingspolitikens relevans inom "nätets diskurs" (digitalt bistånd). Däremot verkar utestängningsprocedurerna i diskursproduktionen ha lett till att viktiga aspekter om regleringen och styrningen av Internet utlämnats. Följaktligen kan det uttydas att de starka aktörerna har verkat för att den institutionella ordningen gällande Internets styrning inte ska rubbas. I de fall ämnet nämns explicit framgår det tydligt att status quo ska upprätthållas. WSIS-processen lyckades därför inte med ambitionen att öka marginaliserade aktörers inflytande i detta avseende.Since the Net's humble beginning, Internet regulation and governance has been characterized by a West-centric and techno-meritocratic discourse which, in many ways, has led to the exclusion of major parts of the world from active participation in building the Information Society. In the prevailing order the United States has a privileged position through its indirect control over the Internet‘s strategic resources, i.e. IP-addresses and "root" in the Domain Name System, via a contractual arrangement between the "Department of Commerce" and the organization "Internet Corporation for Assigned Names and Numbers" (ICANN). There was furthermore a latent conflict between the United States and Internet community, on the one hand, and the United Nations and its member states, on the other hand, in so far as that the institutional order rested on principles of U.S. civil law instead of international treaties, one of the foundations of the geopolitical system. Hence two conferences in Geneva 2003 and Tunis 2005, as two phases of the "World Summit on the Information Society" (WSIS), were organised by the U.N. to raise topics concerning an internationally legitimate regime for Internet governance and the unequal distribution of information- and communications technology (ICT) between rich industrialized nations and poor developing ones. The aim of this study is to investigate whether WSIS managed in its objective of providing marginalized players, primarily the U.N. system and developing nations, structural influence in Internet governance and adding dimensions of digital solidarity and internationalization to a discourse that historically has been dominated by the West, in particular the U.S. Through the prism of Michel Foucault's concepts of power, the final documents from the WSIS process are scrutinized for discursive shifts that could be indicative of actual changes in power structures to the advantage of marginalized players. Discursive shifts, as those detected in the documents, are primarily related to the notion of the "digital divide" and raising awareness for the need of development and foreign aid policies within the context of the "Discourse of the Net" (ICT for development). On the other hand, it would seem that the procedures of exclusion in the formation of discourse have eliminated important aspects of Internet regulation and governance. Subsequently, it can be inferred that powerful players have worked behind the scenes to maintain the current structures of Internet governance. In those passages, where the subject is explicitly mentioned, there are clear references to maintaining the existing status quo. The WSIS process failed consequently in its ambition to increase the influence of marginalized players in this regard.
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Allen, M. "Acoustic localisation for real-life applications of wireless sensor networks." Thesis, Coventry University, 2009. http://curve.coventry.ac.uk/open/items/859e107f-3ece-f043-75cd-7676dde0f896/1.
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The work described in this thesis is concerned with self-localisation (automated estimation of sensor locations) and source-localisation (location of a target) using Wireless Sensor Networks (WSNs). The motivation for the research in this thesis is the on-line localisation of marmots from their alarm calls. The application requires accurate 3D self-localisation (within a small percentage of sensor spacing) as well as timely operation. Further challenges are added by the high data-rate involved: sensor nodes acquire data at a rate that is greater than the available network bandwidth. This data cannot be streamed over a multi-hop network, implying a need for data reduction through in-network event detection and local data compression or filtering techniques. The research approach adopted in this thesis combined simulation, emulation and real-life experimentation. Real-life deployment and experimentation highlighted problems that could not be predicted in controlled experiments or simulation. Emulation used data gathered from controlled, real-life experimentation to simulate proposed system refinements; this was sufficient to provide a proof-of-concept validation for some of the concepts developed. Simulation allowed the understanding of underlying theoretical behaviour without involving the complex environmental effects caused by real-life experimentation. This thesis details contributions in two distinct aspects of localisation: acoustic ranging and end-toend deployable acoustic source localisation systems. With regard to acoustic ranging and 3D localisation, two WSN platforms were evaluated: one commercially available, but heavily constrained (Mica2) and one custom-built for accurate localisation (Embedded Networked Sensing Box (ENSBox)). A new proof of concept platform for acoustic sensing (based on the Gumstix single-board computer) was developed by the author (including the implementation of a ranging mechanism), based on experiences with the platforms above. Furthermore, the literature was found to lack a specific procedure for evaluation and comparison of self-localisation algorithms from theoretical conception to real-life testing. Therefore, an evaluation cycle for self-localisation algorithms that encompassed simulation, emulation and real-life deployment was developed. With respect to source localisation, a hardware and software platform named VoxNet was designed and implemented.
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Sartelli, M., F. M. Abu-Zidan, L. Ansaloni, M. Bala, M. A. Beltran, W. L. Biffl, F. Catena, et al. "The role of the open abdomen procedure in managing severe abdominal sepsis: WSES position paper." BioMed Central, 2015. http://hdl.handle.net/10150/610338.
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The open abdomen (OA) procedure is a significant surgical advance, as part of damage control techniques in severe abdominal trauma. Its application can be adapted to the advantage of patients with severe abdominal sepsis, however its precise role in these patients is still not clear. In severe abdominal sepsis the OA may allow early identification and draining of any residual infection, control any persistent source of infection, and remove more effectively infected or cytokine-loaded peritoneal fluid, preventing abdominal compartment syndrome and deferring definitive intervention and anastomosis until the patient is appropriately resuscitated and hemodynamically stable and thus better able to heal. However, the OA may require multiple returns to the operating room and may be associated with significant complications, including enteroatmospheric fistulas, loss of abdominal wall domain and large hernias. Surgeons should be aware of the pathophysiology of severe intra-abdominal sepsis and always keep in mind the option of using open abdomen to be able to use it in the right patient at the right time.
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Catalan, Pablo. "Community-based innovation dynamics in the water supply and sanitation (wss)sector." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44790.
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For most of the one billion people living in extreme poverty worldwide, access to an adequate water supply and basic sanitation (WSS) is limited, resulting in substantial health, economic and social burdens. Although the international community has actively explored solutions to this crisis, primarily focusing on bottom-up approaches in which the beneficiaries participate in the design and implementation of their own WSS solutions, significant problems remain. Innovation presents an important source of feasible solutions in this sector for those in need, but insufficient study exists to allow scholars to determine the dynamics that trigger WSS innovation. In light of the recent emphasis on a bottom-up approach to water issues and the dearth of analysis with regard to the role WSS innovation plays in seeking solutions, the present dissertation sets out to explore innovation dynamics in relation to the establishment of rural Water Supply and Sanitation Community-Based (WSS-CB). The answer comes through an application of a qualitative methodology that focuses on the implementation of two publicly-run and sustainability-oriented programs - the Blue Flag Ecological Program (BFEP) and the Sanitarian Quality Seal Program (SQSP) - in three rural communities in Costa Rica. A theoretical model based on the conceptual frameworks of Systems of Innovation (SI), Community Based/Community Management (CB/CM), and the Institutional Analysis Development (IAD) theory is proposed, including two set of hypotheses addressing the contribution of two independent variables, the participation of the community and the capacity of the community, to local sustainability and local learning. The results show that the dynamics relating to leadership and a sense of ownership do, in fact, affect both dependent variables and further identify participation and interaction at decision-making and social venues as innovation drivers.
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Mysore, Sachidananda Vinay. "On Maximizing the Efficiency of Multipurpose WSNs Through Avoidance of Over- or Under-Provisioning of Information." Phd thesis, TU Prints, 2014. http://tuprints.ulb.tu-darmstadt.de/4207/8/Thesis_Ganesha_Vinay_2014.pdf.
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A wireless sensor network (WSN) is a distributed collection of sensor nodes, which are resource constrained and capable of operating with minimal user attendance. The core function of a WSN is to sample physical phenomena and their environment and transport the information of interest, such as current status or events, as required by the application. Furthermore, the operating conditions and/or user requirements of WSNs are often desired to be evolvable, either driven by changes of the monitored phenomena or by the properties of the WSN itself. Consequently, a key objective for setting up/configuring WSNs is to provide the desired information subject to user defined quality requirements (accuracy, reliability, timeliness etc.), while considering their evolvability at the same time.
The current state of the art only addresses the functional blocks of sampling and information transport in isolation. The approaches indeed assume the respective other block to be perfect in maintaining the highest possible information contribution. In addition, some of the approaches just concentrate on a few information attributes such as accuracy and ignore other attributes (e.g., reliability, timeliness, etc.). The existing research targeting these blocks usually tries to enhance the information quality requirements (accuracy, reliability, timeliness etc.), regardless of user requirements and use more resources, leading to faster energy depletion. However, we argue that it is not always necessary to provide the highest possible information quality. In fact, it is essential to avoid under or over provision of information in order to save valuable resources such as energy while just satisfying user evolvable requirements. More precisely, we show the interdependence of the different user requirements and how to co-design them in order to tune the level of provisioning.
To discern the fundamental issues dictating the tunable co-design in WSNs, this thesis models and co-designs the sampling accuracy, information transport reliability and timeliness, and compares existing techniques. We highlight the key problems of existing techniques and provide solutions to achieve desired application requirements without under or over provisioning of information.
Our first research direction is to provide tunable information transport. We show that it is possible to drastically improve efficiency, while satisfying the user evolvable requirements on reliability and timeliness. In this regard, we provide a novel timeliness model and show the tradeoff between the reliability and timeliness. In addition, we show that the reliability and timeliness can work in composition for maximizing efficiency in information transport. Second, we consider the sampling and information transport co-design by just considering the attributes spatial accuracy and transport reliability. We provide a mathematical model in this regard and then show the optimization of sampling and information transport co-design. The approach is based on optimally choosing the number of samples in order to minimize the number of retransmission in the information transport while maintaining the required reliability. Third, we consider representing the physical phenomena accurately and optimize the network performance. Therefore, we jointly model accuracy, reliability and timeliness, and then derive the optimal combination of sampling and information transport. We provide an optimized model to choose the right representative sensor nodes to describe the phenomena and highlight the tunable co-design of sampling and information transport by avoiding over or under provision of information.
Our simulation and experimental results show that the proposed tunable co-design supports evolving user requirements, copes with dynamic network properties and outperforms the state of the art solutions.
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Baptista, Adérito Herculano Sarmento. "Dynamic adaptation of interaction models for stateful web services." Master's thesis, Faculdade de Ciências e Tecnologia, 2011. http://hdl.handle.net/10362/12042.
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Dissertação para obtenção do Grau de Mestre em
Engenharia InformáticaWireless Sensor Networks (WSNs) are accepted as one of the fundamental technologies for current and future science in all domains, where WSNs formed from either static or mobile sensor devices allow a low cost high-resolution sensing of the environment. Such opens the possibility of developing new kinds of crucial applications or providing more accurate data to more traditional ones. For instance, examples may range from large-scale WSNs deployed on oceans contributing to weather prediction simulations; to high number of diverse Sensor devices deployed over a geographical area at different heights from the ground for collecting more accurate data for cyclic wildfire spread simulations; or to networks of mobile phone devices contributing to urban traffic management via Participatory Sensing applications. In order to simplify data access, network parameterisation, and WSNs aggregation, WSNs have been integrated in Web environments, namely through high level standard interfaces like Web services. However, the typical interface access usually supports a restricted number of interaction models and the available mechanisms for their run-time adaptation are still scarce. Nevertheless, applications demand a richer and more flexible control on interface accesses – e.g. such accesses may depend on contextual information and, consequently, may evolve in time. Additionally, Web services have become increasingly popular in the latest years, and their usage led to the need of aggregating and coordinating them and also to represent state in between Web services invocations. Current standard composition languages for Web services (wsbpel,wsci,bpml) deal with the traditional forms of service aggregation and coordination, while WS-Resource framework (wsrf) deals with accessing services pertaining state concerns (relating both executing applications and the runtime environment). Subjacent to the notion of service coordination is the need to capture dependencies among them (through the workflow concept, for instance), reuse common interaction models, e.g. embodied in common behavioural Patterns like Client/Server, Publish/- Subscriber, Stream, and respond to dynamic events in the system (novel user requests, service failures, etc.). Dynamic adaptation, in particular, is a pressing requirement for current service-based systems due to the increasing trend on XaaS ("everything as a service") which promises to reduce costs on application development and infrastructure support, as is already apparent in the Cloud computing domain. Therefore, the self-adaptive (or dynamic/adaptive) systems present themselves as a solution to the above concerns. However, since they comprise a vast area, this thesis only focus on self-adaptive software. Concretely, we propose a novel model for dynamic interactions, in particular with Stateful Web Services, i.e. services interfacing continued activities. The solution consists on a middleware prototype based on pattern abstractions which may be able to provide (novel) richer interaction models and a few structured dynamic adaptation mechanisms, which are captured in the context of a "Session" abstraction. The middleware was implemented and uses a pre-existent framework supporting Web enabled access to WSNs, and some evaluation scenarios were tested in this setting. Namely, this area was chosen as the application domain that contextualizes this work as it contributes to the development of increasingly important applications needing highresolution and low cost sensing of environment. The result is a novel way to specify richer and dynamic modes of accessing and acquiring data generated by WSNs.
Este trabalho foi parcialmente financiado pelo Centro de Informática e Tecnologias da Informação (CITI), e pela Fundação para a Ciência e a Tecnologia (FCT / MCTES) em projectos de investigação
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Etebari, Ali. "Wall shear measurements in arterial flows." Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/27326.
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Cardiovascular disease is responsible for the majority of morbidity and mortality in the United States. Physiologically healthy flow rarely displays turbulent behavior, thereby maintaining normal shear levels. The presence of vortical flow structures, however, alters the hemodynamical characteristics within the system, which has significant effect upon shear stress (SS) and wall shear stress (WSS) levels, as well as particle residence times. The relationship between these hemodynamic parameters and vascular injury response is of great relevance to understanding the cardiovascular disease process.
In this work, new methods and algorithms are developed and presented for resolving, both globally and locally, the spatial and temporal variations of shear stress (SS) and WSS for in vitro models of the human cardiovascular system. Advancements in global measurements are based on improving the accuracy of SS and WSS estimation from time-resolved Digital Particle Image Velocimetry (DPIV) velocity measurements. A new velocity derivative method, the fourth-order noise-optimized compact-Richardson implicit scheme, has been developed, overcoming the obstacle of minimizing both the bias and random error in temporal/spatial derivative estimations. The resulting error is on the same order as the velocity measurement error for global measurements which results in an order of magnitude accuracy improvement. The method has been extended to WSS measurements, and combined with a new method of mirroring/reflecting a flow field over its boundary in order to achieve higher-order estimation. For moving boundaries an edge detection cross-correlation algorithm has been developed and characterized, yielding sub-pixel accuracy in measuring dynamic wall position prior to estimating WSS. An original microelectromechanical system (MEMS) WSS sensor capable of delivering high sensitivity, frequency response and accurate WSS measurements has been developed and characterized in this work.Ph. D.
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Poe, Wint Yi [Verfasser], Jens B. [Akademischer Betreuer] Schmitt, and Lars [Akademischer Betreuer] Wolf. "Design Problems in Large-Scale, Time-Sensitive WSNs / Wint Yi Poe. Betreuer: Jens B. Schmitt ; Lars Wolf." Kaiserslautern : Technische Universität Kaiserslautern, 2013. http://d-nb.info/1042185700/34.
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Sanborn, Mark A. "A Model for Field Deployment of Wireless Sensor Networks (WSNs) within the Domain of Microclimate Habitat Monitoring." NSUWorks, 2011. http://nsuworks.nova.edu/gscis_etd/296.
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Wireless sensor networks (WSNs) represent a class of miniaturized information systems designed to monitor physical environments. These smart monitoring systems form collaborative networks utilizing autonomous sensing, data-collection, and processing to provide real-time analytics of observed environments. As a fundamental research area in pervasive computing and envisioned as large-scale autonomous networks of communicating nodes capable of monitoring conditional metrics over vast geographic areas, WSNs have the potential to provide researchers and conservationists with increased knowledge of the intricacies and interrelationships of disparate environments.
The author addressed the problem of developing a methodology for the design and deployment of WSNs in uncontrolled and harsh outdoor environments. Within the context of a research and conservation field study of flora, the author developed a model for deployment of WSNs within the domain of microclimate habitat monitoring. The goal of this study was to contribute to the body of knowledge in WSN research by developing a model for deployment that was scientifically sound and replicable. To accomplish this goal, the author conducted an investigation of current technologies associated with WSNs, their capabilities, and their applications specific to the stated domain. To validate this model, the author deployed a WSN for monitoring the microclimate habitats of a population of Spiranthes lacera var. gracilis, common name, slender ladies' tresses.
During this field study, the WSN performed according to design and produced sufficient data to provide an accurate representation of the microclimate habitats of the objects of study. As a contribution to the WSN research body of knowledge, the author used an SDLC methodology to provide a pragmatic approach to deployment focused on the elements of nuance specific to WSNs for microclimate habitat monitoring.
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Souza, Oliveira Camila Helena. "Reliability and cost efficiency in coding-based in-network data storage and data retrieval for IoT/WSNs." Thesis, Paris Est, 2015. http://www.theses.fr/2015PESC1134/document.
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Dans cette thèse, nous nous intéressons à cette gestion des données dans les réseaux de capteurs sans fil intégrés dans un contexte IoT. Plus précisément, nous aborderons la problématique du stockage des données au sein même du réseau de capteurs en se posant la question suivante : Comment stocker provisoirement les données dans le réseau de capteurs de sorte que ces données soient facilement accessible par les consommateurs tout en assurant le meilleur compromis entre la fiabilité de livraison des donnés et la préservation des ressources énergétiques des capteurs ?Il s'agit dans un premier temps de proposer un système fiable de stockage de données basé sur la théorie du codage réseau et sur le modèle de communication « Publish/Subscribe ». Le système proposé est adapté à l'architecture des réseaux de capteurs ainsi qu'aux besoins des applications et services IoT localisés. Pour démontrer la validité du système de stockage proposé, des évaluations de performances au travers d'une analyse mathématique et de simulations sont conduites. Celles-ci montrent clairement une augmentation de la fiabilité de la livraison des données aux consommateurs avec un taux de livraison des paquets de 80% en moyenne. Afin d'améliorer encore plus les performances du système de stockage de données, nous proposons, dans un second temps, l'optimisation du système afin que celui-ci puisse réaliser le stockage des données de manière adaptative et autonome, tout en assurant le meilleur compromis entre fiabilité et coût. Ce dernier se traduit par l'impact du système de stockage sur la consommation d'énergie du réseau de capteurs sans fil. À notre connaissance, notre système est le premier à proposer d'assurer la fiabilité du stockage des données en fonction des demandes des services et des conditions du réseau. L'évaluation des performances, par simulation, de notre système de stockage adaptatif et autonome montre que l'optimisation du stockage des données (formulée sous forme d'un processus de décision Markovien (MDP)) selon les conditions de fonctionnement du réseau permet l'accès à 70% de données en plus comparativement au système non-adaptatif proposé précédemment. Ce résultat est obtenu tout en augmentant la durée de vie du réseau de 43%.Après avoir travaillé sur l'aspect quantitatif des performances du réseau à travers une étude sur le compromis coût - consommation énergétique, nous nous intéresserons dans la troisième contribution de cette thèse à l'utilisation de notre système de stockage dans des réseaux de capteurs sans fil disposant de cycles de services (cycle d'endormissement-réveil) variables. Aujourd'hui, les réseaux de capteurs reposant sur le standard 802.15.4 peuvent utiliser des cycles de services variables et avoir recours à l'endormissement des nœuds dans le but d'économiser leur énergie. Dans une première partie de cette contribution, nous avons ainsi proposé une amélioration du mécanisme de gestion du cycle de service (duty cycle) du standard 802.15.4 afin de le rendre dynamique et adaptable au trafic réseau. L'évaluation des performances par simulations de l'amélioration proposée montre que celle-ci aboutit à une économie d'énergie très significative tout en permettant au réseau de capteurs sans fil de remplir sa mission de prise en charge du trafic généré. Dans une seconde partie de cette contribution, nous évaluons les performances de notre système de stockage de données dans le but d'évaluer si un tel mécanisme pourrait cohabiter positivement avec un mécanisme de cycle de service variable (condition d'exploitation réaliste du réseau). L'évaluation des performances montre que l'activation d'un cycle de service variable dans le réseau de capteurs n'apporte aucune amélioration au niveau de la consommation énergétique mais que le compromis optimal entre la fiabilité et la consommation énergétique obtenu par notre système de stockage adaptatif et autonome n'est pas non plus affecté, celui-ci est maintenuWireless Sensor Networks (WSN) are made up of small devices limited in terms of memory, processing and energy capacity. They work interconnected and autonomously in order to monitoring a region or an object of interest. The evolution in the development of devices more powerful (with new capability such as energy harvesting and acting) and less expensive made the WSNs a crucial element in the emergence of Internet of Things (IoT). Nonetheless, assuming the new applications and services offered in the IoT scenario, new issues arise in the data management performed in the WSNs. Indeed, in this new context, WSNs have to deal with a large amount of data, now consumed on-demand, while ensure a good trade-off between its reliability and retrievability, and the energy consumption. In the scope of this thesis, we are interested in the data management in the WSN in the context of IoT realm. Specifically, we approach the problem of in-network data storage by posing the following question: How to store data for a short term in the WSNs so that the data could be easily retrieved by the consumers while ensuring the best trade-off between data reliability and conservation of energy resources? Foremost, we propose a reliable data storage scheme based on coding network, and assuming a communication model defined by the Publish/Subscribe paradigm. We validate the efficiency of our proposal by a theoretical analyses that is corroborate by a simulation evaluation. The results show that our scheme achieves a reliability of 80% in data delivery with the best cost-benefit compared to other data storage scheme. Aiming to further improve the performance of the data storage scheme proposed in our first contribution, we propose its optimization (modeling it as a Markov Decision Process (MDP)) in order to store data with optimal trade-off between reliability and communication overhead (in this context, also seen as energy consumption), and in an autonomously and adaptive way. For the best of our knowledge, our optimized data storage scheme is the only to ensure data reliability while adapt itself according to the service requirements and network condition. In addition, we propose a generalization of the mathematical model used in our first contribution, and a system model that defines the integration of WSNs performing our data storage scheme in the context for which it was envisaged, the IoT realm. Our performance evaluation shows that our optimization allows the consumers to retrieve up to 70% more packets than a scheme without optimization whereas increase the network lifetime of 43%.Finally, after being interested in finding the best trade-off between reliability and cost, we now focus on an auxiliary way to reduce the energy consumption in the sensor nodes. As our third contribution, we propose a study, in two parts, to measure how much a node activity scheduling can save energy. First, we propose an improvement in the duty cycle mechanism defined in the 802.15.4. Then, we propose a duty cycle mechanism introduced into our data storage scheme aiming at saving energy in the storage nodes. The simulation results show that our solution to the duty cycle mechanism in 802.15.4 led in considerable saving in energy costs. However, regarding duty cycle in our data storage scheme, it did not end up in more energy saving. Actually, as our optimized scheme already saves as much resource energy as possible while ensuring high reliability, the duty cycle mechanism can not improve the energy saving without compromise the data reliability. Nonetheless, this result corroborates that our scheme, indeed, performs under the optimal trade-off between reliability and communication overhead (consumption energy)
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Nandiraju, Deepti. "Efficient Traffic Diversion and Load-balancing in Multi-hop Wireless Mesh Networks." University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1258477338.
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Abidoye, Ademola Philip. "Energy optimization for wireless sensor networks using hierarchical routing techniques." University of the Western Cape, 2015. http://hdl.handle.net/11394/7064.
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Philosophiae Doctor - PhDWireless sensor networks (WSNs) have become a popular research area that is widely gaining the attraction from both the research and the practitioner communities due to their wide area of applications. These applications include real-time sensing for audio delivery, imaging, video streaming, and remote monitoring with positive impact in many fields such as precision agriculture, ubiquitous healthcare, environment protection, smart cities and many other fields. While WSNs are aimed to constantly handle more intricate functions such as intelligent computation, automatic transmissions, and in-network processing, such capabilities are constrained by their limited processing capability and memory footprint as well as the need for the sensor batteries to be cautiously consumed in order to extend their lifetime. This thesis revisits the issue of the energy efficiency in sensor networks by proposing a novel clustering approach for routing the sensor readings in wireless sensor networks. The main contribution of this dissertation is to 1) propose corrective measures to the traditional energy model adopted in current sensor networks simulations that erroneously discount both the role played by each node, the sensor node capability and fabric and 2) apply these measures to a novel hierarchical routing architecture aiming at maximizing sensor networks lifetime. We propose three energy models for sensor network: a) a service-aware model that account for the specific role played by each node in a sensor network b) a sensor-aware model and c) load-balancing energy model that accounts for the sensor node fabric and its energy footprint. These two models are complemented by a load balancing model structured to balance energy consumption on the network of cluster heads that forms the backbone for any cluster-based hierarchical sensor network. We present two novel approaches for clustering the nodes of a hierarchical sensor network: a) a distanceaware clustering where nodes are clustered based on their distance and the residual energy and b) a service-aware clustering where the nodes of a sensor network are clustered according to their service offered to the network and their residual energy. These approaches are implemented into a family of routing protocols referred to as EOCIT (Energy Optimization using Clustering Techniques) which combines sensor node energy location and service awareness to achieve good network performance. Finally, building upon the Ant Colony Optimization System (ACS), Multipath Routing protocol based on Ant Colony Optimization approach for Wireless Sensor Networks (MRACO) is proposed as a novel multipath routing protocol that finds energy efficient routing paths for sensor readings dissemination from the cluster heads to the sink/base station of a hierarchical sensor network. Our simulation results reveal the relative efficiency of the newly proposed approaches compared to selected related routing protocols in terms of sensor network lifetime maximization.
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Gómez, Pantoja Carlos. "Servicios de cache distribuidos para motores de búsqueda web." Tesis, u, 2014. http://repositorio.uchile.cl/handle/2250/116993.
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Doctor en Ciencias, Mención ComputaciónLos Motores de Búsqueda Web (WSEs) actuales están formados por cientos de nodos de procesamiento, los cuales están particionados en grupos llamados servicios. Cada servicio lleva a cabo una función específica, entre los que se destacan: (i) Servicio de Front-End; (ii) Servicio de Cache; y (iii) Servicio de Índice. Específicamente, el Servicio de Front-End maneja las consultas de usuario que arriban al WSE, las distribuye entre los otros servicios, espera por los resultados y genera la respuesta final al usuario. La idea clave del Servicio de Cache es reutilizar resultados previamente computados a consultas hechas en el pasado, lo cual reduce la utilización de recursos y las latencias asociadas. Finalmente, el Servicio de Índice utiliza un índice invertido para obtener de manera eficiente los identificadores de documentos que mejor responden la consulta. El presente trabajo de tesis se focaliza en el diseño e implementación de servicios de cache distribuidos eficientes. Varios aspectos del sistema y el tráfico de consultas deben ser considerados en el diseño de servicios de cache eficientes: (i) distribuciones sesgadas de las consultas de usuario; (ii) nodos que entran y salen de los servicios (de una forma planificada o súbitamente); y (iii) la aparición de consultas en ráfaga. Cualquiera de estos tópicos es un problema importante, ya que (i) genera una asignación de carga desbalanceada entre los nodos; el tópico (ii) impacta en el servicio cuando no se utilizan mecanismos de balance de carga dinámicos, empeorando la asignación desbalanceada de carga y perdiendo información importante ante fallas; y finalmente (iii) puede congestionar o dejar fuera de servicio algunos nodos debido al abrupto incremento en el tráfico experimentado, incluso si se tiene un servicio balanceado. Dada la arquitectura que se emplea en este trabajo, el Servicio de Cache es el más expuesto a los problemas mencionados, poniendo en riesgo la tasa de hit de este servicio clave y el tiempo de respuesta del WSE. Este trabajo ataca los problemas mencionados anteriormente proponiendo mejoras arquitecturales, tales como un enfoque de balance de carga dinámico para servicios de cache altamente acoplados (desplegados en clusters) basados en Consistent Hashing, y un esquema para monitoreo y distribución de consultas frecuentes. El mecanismo de balance de carga propuesto es una nueva solución al problema de balance de carga en clusters de computadores que corren aplicaciones manejadas por los datos (data-driven). Además, se estudia cómo predecir la aparición de consultas en ráfaga para tomar acciones correctivas antes de que saturen o colapsen algunos nodos. Finalmente, se adopta la idea de un sistema tolerante a fallas para proteger información valiosa obtenida a través del tiempo. La idea fundamental es replicar algunas entradas de cache entre distintos nodos para que sean usados en caso de fallas.
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Hai-Chau, Le, Hiroshi Hasegawa, and Kenichi Sato. "Hierarchical optical path network design algorithm that can best utilize WSS/WBSS based cross-connects." IEEE, 2009. http://hdl.handle.net/2237/14026.
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Aldana, Gerardo. "Hydraulic behaviour and performance improvement of waste stabilisation ponds (WSPs) using a computational fluid dynamic (CFD) and a physical model." Thesis, University of Surrey, 2004. http://epubs.surrey.ac.uk/843814/.
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A physical model and a computational fluid dynamic (cfd) model (HYDRO-3D) have been developed to simulate the effects of novel maturation pond configurations, inlet and outlet positions, channels and critical environmental factors (wind speed and direction) on the hydraulic efficiency of maturation ponds at a small sewage treatment works in southern England. The ponds form the final, polishing stage of an otherwise conventional percolating filter treatment works. The final effluent of the plant joins a stream that discharges directly to a bathing beach. Thus the overall objective of the project is to maximise the efficiency of pathogen indicator removal and meet European bathing water standards. The specific aim of the study reported here was to calibrate the physical model and to assess its reliability as a tool for assessing and predicting hydraulic performance of ponds. Work focused on the comparison of simulation outputs from the cfd model and full scale system performance in order to increase the reliability of both models as design tools. The full scale ponds under study comprised three parallel, tertiary stage maturation ponds. A Geopacks flow meter was used to calibrate the ratio of water and wind velocities in the full scale pond channels and the model. Additionally floats and novel drogues were used to measure low flow velocities within the physical model. Initial tracer experiments using salt and rhodamine-WT were conducted to define the hydraulic retention time (HRT) of the physical model in still air and with top and bottom inlets and outlets. In the physical model the effect of back-mixing and dead zones can be readily observed and photographed, whereas this is more difficult to display in the outputs of computational models. Potential sources of disagreement are discussed in the thesis, but their concurrence suggests they both have a valuable role to play in the future design of ponds aimed at maximising hydraulic efficiency. The study also confirmed field observations which indicated that wind tends to be damaging rather than beneficial to pond performance.
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Severino, Ricardo Augusto Rodrigues da Silva. "Improving QoS for large-scale WSNs." Tese, 2015. https://repositorio-aberto.up.pt/handle/10216/82612.
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Severino, Ricardo Augusto Rodrigues da Silva. "Improving QoS for large-scale WSNs." Doctoral thesis, 2015. https://repositorio-aberto.up.pt/handle/10216/82612.
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Jian, Hao-Yang, and 簡浩洋. "Outlier-Filtered Time Synchronization Protocol for WSNs." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/14570911320329944366.
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碩士國立交通大學
網路工程研究所
95
Time synchronization is considered an important issue for wireless sensor networks (WSNs) where many applications, such as object tracking and data aggregation, rely on the synchronization of the clock of each node. Some types of attacks, such as insider attack and pulse-delay attack, can be used to decrease the precisions of time synchronization protocols. Recently, many time synchronization protocols were designed with security concern. Some of them cannot defend against these attacks, while others cannot synchronize the relative clock skews and offsets simultaneously or cannot support global time synchronization in multi-hop sensor networks. In this paper, we propose two efficient methods to reduce the overhead for propagating the global time. One uses authenticated multicast by inserting multiple MACs into a message. This method is more efficient than the other, but the amount of receivers must be less than eight. The other uses authenticated broadcast based on uTESLA and it doesn’t limit the amount of receivers. The proposed methods can filter the outliers introduced by attacks and keeps the precision about the order of microsecond.
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Lin, Shaing-Ting, and 林湘婷. "A Grid-based Hole Detection Scheme in WSNs." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/98101972054343951121.
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碩士淡江大學
資訊工程學系碩士在職專班
98
Wireless Sensor Networks (WSNs) can be widely utilized in many applications especially in environmental surveillance. However, there exist some holes within the WSNs caused by some factors such as non-uniform deployment of sensor nodes, the existence of physical obstacle such as mountains and lakes, some sensor nodes deplete their energy, and being destroyed by outside forces. These holes will degrade the performance of wireless sensor networks (WSNs). Hence, how to discover the position of the holes and utilize the information to improve the performance of WSNs is a significant issue. In order to solve this problem, we proposed a grid-based hole detection scheme in WSNs. In grid architecture, we use the grid head to broadcast and forward the hole detection request and respond. And then, sink will calculate the position of the holes for improving the performance of the WSNs.
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Hong, Jialing, and 洪佳鈴. "Using Conjugate Gradient Method for Routing in WSNs." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/91422475397879582875.
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碩士國立中正大學
資訊工程研究所
100
We discuss the routing path from macroscopic view in wireless sensor network, it unlike the previous graphical ways. We consider the whole range with global optimization. The routing problem can be described a partial differential equations (PDEs) by mathematical analysis, then we use finite difference method to find the approximation solution of PDEs, to find the liner equations in the rule. Liner equations can be solved by Gauss-Seidel Iteration and Conjugate gradient method, and we option the routing path for load balance. Conjugate gradient method is one of common iterative solution on linear system; Gauss-Seidel Iteration is also the method for partial differential equations, when we calculate Gauss-Seidel Iteration, it cannot converge in more variable node density. Conjugate gradient method can solve the convergent problems, and the approximate is close to the actual solution; final we explore the impact of density on disposing sensor node.
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Lien, Shin-Lu, and 連新路. "Recovery Mechanism for Diff-based Reprogramming in WSNs." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/43949473085522613666.
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碩士國立暨南國際大學
資訊管理學系
101
Reprogramming remote sensor nodes on wireless sensor networks (WSNs) allows the software on them to be dynamically updated or enhanced for adapting to changed environmental conditions or application requirements. Many researches use diff-based approaches to transmit only the code difference to sensor nodes for updating. When traditional full image replacement reprogramming mechanism fails, sensor nodes can simply perform self-recovery by retrying or reloading the stored full image of the previous version, but failure of diff-based reprogramming may cause extra problems. Because sensor node’s storage is limited, the older version of patch files may be overwritten by the next one. Then after many times of update, reprogramming recovery mechanism will lack the intermediate version of patch files for incremental recovery. To recover from this situation, extra data retransmission is needed and the host machine should issue recovery commands, but both of them will also affect all other normal nodes in WSN. The data retransmission is especially unacceptable in a resource-limited WSN environment. To solve these problems, we have proposed two new diff-based recovery mechanisms named N and N-1 Incremental Recovery to recover sensor nodes from reprogramming failures. We implement the proposed mechanism in TinyOS and choose Two-Stage Diff as our diff-based dynamic update mechanism for updating the software on sensor nodes. Two-Stage Diff mechanism is compatible to Deluge mechanism which is taken as TinyOS’s default remote full image update mechanism. Experiments with the modified TinyOS show that our N and N-1 Incremental Recovery compared with the Deluge default recovery mechanism can greatly reduce the amount of retransmitted data and the processing time can be significantly reduced as well.
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Lin, Chun-Lung, and 林俊隆. "Optimal Rate Allocation with Distortion Guarantee in WSNs." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/61517378329329772566.
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博士國立清華大學
資訊工程學系
98
近年來，失真壓縮技術已被廣泛應用在長期收集大量連續資料的無線感知器網路系統以延長整體系統運作生命期，因為這些系統主要是收集長期的資料趨勢、分析有意義的統計數據、以及找出感興趣的特定資料樣板，所以通常可以允許少許的資料失真以及不需要及時的資料收集。在這些系統中，感知器被佈建來收集大量連續資料，而相鄰感知器的資料經常具備時間、空間的關連性，為了利用這些關聯性減少資料傳輸量，中間節點的感知器可將自己所收集的資料以及從鄰近節點所傳輸過來資料利用失真壓縮技術壓縮。過去的研究多著重在達到高壓縮率、有效省電以及分散式壓縮等議題，然而一個好的壓縮技術，均需輔以一個最佳化傳輸位元率分配的理論基礎，失真壓縮則是可以有效的透過Rate-distortion 的策略大量減少所需傳輸量。這篇論文研究透過rate-distortion最佳化分配，達到感知器系統省電的目的: 如何在滿足使用者對於資料失真度所能接受的需求下，最佳的決定如何分配各個感知器的壓縮位元率。一旦位元率能夠被準確的決定，感知器的資料就能夠很有效率的進行壓縮，達到傳輸最少的資料量，滿足使用者的查詢。本篇論文將rate-distortion 最佳化分配問題數學化，並且提出一個最佳化分配的數學解，為了要適應感知器網路的分散壓縮需求，我也根據數學最佳解提出一個分散式分配的策略，基於所提出的最佳化分配以及分散式分配策略，本篇論文也提出一個heuristic 演算法，從網路連結圖建立有效率的傳輸資料樹結構，更進一步的減少整體網路傳輸資料量。所提的方法均經由實際溫度資料驗證，實驗結果顯示最佳化分配以及分散式分配策略，的確能大量的減少整體網路傳輸資料量(跟均勻分配策略比較)。所提的方 法在下列網路條件下會更有效益: (1) 感知器分布密度高，(2) 感知器分布不均勻以及(3) 感知器所收集的資料變化大。
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Yang, Yuan-Cheng, and 楊源誠. "Data Caching Techniques for Information Storage on WSNs." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/09556319274061208742.
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Hsu, Chia Yu, and 徐嘉佑. "Multimedia Communications with Multi-channel Transceiver in WSNs." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/3v2p25.
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碩士國立臺中教育大學
資訊工程學系
102
Over the past few years, wireless sensor network (WSN) has become the main technology to monitor environmental and physical phenomena. As the technology matures, even in the Zigbee network it is possible to send multimedia streaming data. Therefore, the main purpose of this thesis is to provide real-time services in the Zigbee network. The design and implementation of the thesis will provide real-time multimedia streaming multi-channel transceiver, which combined voice compression technology open source Speex and video compression technology, open source x264 to reduce the amount of multimedia streaming data. Open source x264 this research will make use of multi-hop to extend its communication distance over Zigbee network. Due to the Characteristics of short transmission distance and low transmission rate for WSN. The main purpose of this thesis is to provide the transmission of multimedia data will maintaining multimedia quality of service in WSNs. This thesis deployed a chain topology design to extend the transmission distance and combine multi-radio multi-channel scheduling mechanism with transmission technology to improve the overall network throughput, latency, in order to maintain long-distance transmission of real-time. Finally, carry on multimedia transmission and measurement at different distances, and analyze the effect about Quality of Service with compression technology, Packet loss and delay. Finally the thesis conducted a testbed with different transmission distances and scenario to analyze the quality of multimedia service using purposed multi-radio multi-channel media in WSNs
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Shiu, Jiun-Liang, and 許鈞喨. "Routing Decisions for Hybrid Information Transmission in WSNS." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/69ehyp.
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碩士真理大學
資訊工程學系碩士班
106
The Routing applications is popular In Wireless Sensor Networks (WSNs). Most of previous applications do not recognize the different data. For a practical monitor-ing environment, the monitoring events may be varied, and so do the data sinks. We propose a distributed mechanism to arrange the routing for transmitting the event data to proper sink as soon as possible. The routing decides according to the transmission records as well as the remaining energy of itself and its neighbor. Fur-thermore, the mobile sensors in the environments may move to support monitoring if the event ratio is higher and the remaining energy of sensors is lower. We also simulate proposed mechanism in different environment having different sensors de-ployment. The simulation results show that our mechanism can choose proper rout-ings for monitoring events and extend the monitoring life time efficiently.
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Abreu, Henrique Castro. "Monotorização das condições atmosféricas nas autoestradas utilizando WSNs." Master's thesis, 2014. http://hdl.handle.net/1822/42015.
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Dissertação de mestrado integrado em Engenharia Eletrónica Industrial e ComputadoresAo longo dos anos, condições atmosféricas adversas nas autoestradas provocaram inúmeros acidentes rodoviários responsáveis por danos nas viaturas e infraestruturas civis, e infelizmente, acidentes fatais. Atualmente, apesar do esforço para evitar estas situações através de melhorias na segurança e avisos de condições menos favoráveis o número de acidentes ainda é demasiado elevado. De forma a contribuir para a resolução deste problema, no âmbito do projeto QREN SI I&DT SustIMS, em co-promoção com a empresa Ascendi, é apresentado este sistema, de nome HighWayMon, que tem como objetivo a monitorização de condições atmosféricas nas autoestradas, com o intuito de ser possível prevenir algumas destas situações usando alguns sensores COTS. Para isso foi desenvolvida uma WSN (Wireless Sensor Network) capaz de obter as informações necessárias através de nós sensores, enviado-as para uma estação base responsável por interligar o sistema desenvolvido com outro capaz de processar e armazenar os dados adquiridos. Através da modularidade do hardware e da funcionalidade plug-and-play inserida é possível realizar várias combinações dos nós sensores utilizando o mesmo firmware, permitindo adquirir dados de vários tipos de sensores que utilizem o mesmo tipo de interface. Com o sucesso do projeto espera-se que seja possível usar este sistema para advertir os utilizadores das autoestradas dos perigos que podem encontrar ao longo da via, principalmente nos locais onde é previsto um maior número de acidentes.
Over the years, adverse weather conditions on the highways led to several roads accidents causing huge damages in vehicles, infrastructures and, unfortunately, fatal accidents. Nowadays, despite the effort to overcome this situation by employing security improvements or warning signals, there are still to many accidents. This thesis, under the project QREN SI I&DT SustIMS, with the company Ascendi, presents the HighWayMon system, that aims to provide a solution to the mentioned problems by proposing an autonomous weather monitoring system to report the conditions on the highways in order to be able to prevent accidents using COTS sensors. A Wireless Sensor Network (WSN) is developed to collect the necessary information by the sensor nodes and forward them to a base station responsible for connecting the network to other processing units for further processing. The proposed system is also capable of performing various combination of devices using the same firmware through the developed hardware modularity and Plug-and-Play functionality. This allows the system to acquire only the necessary information from the network. Upon finishing the project, it is expected to reduce the number of the accidents by issuing proper warning alerts to the drivers especially in the zones with the high risk of the accident.
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Alves, João André Varino. "Timelywsn: middleware architecture for probabilistic support in WSNs." Master's thesis, 2013. http://hdl.handle.net/10451/10067.
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Tese de mestrado em Segurança Informática, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2013Recentemente, tem existido muito interesse e investigação no campo das redes de sensores sem fios (WSNs), redes ad-hoc sem fios, compostas por centenas a milhares de nós computacionais, equipados com equipamento sensorial, que medem o estado de entidades físicas. As WSNs podem ser utilizadas em numerosos cenários e aplicações, por exemplo, para a prevenção e deteção de incêndios florestais, monitorização industrial, ou monitorização da saúde de pacientes. Muitas destas aplicações terão requisitos temporais. No entanto, as WSNs apresentam alguns desafios únicos, que tornam o aprovisionamento de garantias tempo-real estritas, um objectivo irrealista. Os sistemas tempo-real são por norma deterministas e previsíveis, enquanto que as WSNs são, por natureza, imprevisíveis. Como alternativa, alguns investigadores têm explorado o aprovisionamento de algum nível de serviço (QoS), como uma alternativa às garantias tempo-real estritas. Esta tese descreve o estudo e definição de uma arquitetura de middleware para o suporte a aplicações com requisitos tempo-real em redes de sensores sem fios, construída sobre os conceitos de garantias probabilistas, monitorização estatística e adaptação aplicacional. São identificados um conjunto de serviços que necessitam de ser implementados como parte deste sistema, bem como a razão dessa necessidade. Para além disso, esta tese apresenta, encaminhamento baseado em estimação probabilística de latências (PLER), um protocolo de encaminhamento para WSNs, que toma vantagem dos serviços do middleware, servindo como prova de conceito.
Recently, there has been a lot of interest and research in the field of wireless sensor networks (WSNs). Wireless ad-hoc networks made of hundreds to thousands of computer nodes equipped with sensory equipment, that measure the state of physical entities. WSNs can be used in numerous scenarios and applications, for instance, in forest fire prevention and detection, industrial monitoring, or patient-health monitoring. Many of these applications will have real-time requirements. However, WSNs present some unique issues, that make the provisioning of hard real-time guarantees an unreasonable objective. Hard real-time systems are deterministic and predictable, while WSNs are, by nature, unpredictable. Alternatively, some researchers have explored the provisioning of some Quality of Service (QoS), as an alternative to hard real-time guarantees. This thesis describes the study and definition of a middleware architecture for the support of applications with real-time requirements in WSNs, built on the concepts of probabilistic QoS guarantees, statistical monitoring, and application adaptation. It identifies a set of underlying services that need to be implemented as part of this framework, explaining why they are needed and what they provide. Furthermore This thesis presents, Probabilistic Latency Estimation based Routing (PLER), a routing protocol for WSNs, that takes advantage of the middleware services, serving as a proof-of-concept application.
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Cheng, Ren-Hau, and 鄭人豪. "Path Guiding Mechanisms for Improving Location Accuracy in WSNs." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/79634877544624121818.
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碩士淡江大學
資訊工程學系碩士班
95
In the most proposed range-free algorithms, nodes estimate their location using the geometric constraints imposed by the location of mobile anchor. However, there is no discussion on how the mobile anchor moves so that all sensor nodes can obtain the maximal location accuracies under the constraints of time for localization or the remaining energy of the robot. This paper assumes that traditional range-free algorithms have been executed for a certain time period and the deployed sensors are with different location accuracies. We propose path guiding mechanisms that sensor nodes cooperatively guide the mobile anchor moving along an efficient path which can maximize the improvement of location accuracies or minimize the accuracy differences for all sensor nodes in a given WSN. Experimental study reveals that the proposed path guiding mechanisms effectively guide the mobile anchor moving along the efficient path and thereby saves time and energy consumptions for improving or balancing the location accuracies of all sensor nodes.
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Ting, Yun-Ju, and 丁運如. "Localization using Mobile Anchors in WSNs with Ring Overlapping." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/95143310919190552349.
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碩士國立臺北教育大學
資訊科學系碩士班
97
In this study, we propose an efficient localization scheme in wireless sensor networks. The proposed scheme is based on ring overlapping and utilizes mobile anchors. In a wireless sensor network, there are some nodes knowing their locations, which are called the reference nodes, and the other nodes without the knowledge of their locations are called the blind nodes. Based on the relative RSSI (Received Signal Strength Indicator) values, we utilize mobile beacons to find out the rings that are centered with a certain reference node and contain the blind node. These rings are called B-Rings. Also, by designing the moving path of the mobile anchors and utilizing the mobile beacons, the scheme for reducing the width of the B-Rings is proposed. Then, by overlapping all the B-Rings, the location of the blind nodes can be efficiently estimated. Furthermore, to save the energy of the mobile anchor, we propose another moving scheme called Energy Saving Scheme (ESS), in which the mobile anchor can reduce the length of its movement trajectory by taking a large pace while moving downward. Experimental results showed that the proposed localization scheme has better accuracy than other existing related approaches.
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Wang, Chau-yan, and 王朝彥. "Detecting Anomalous Behaviors in WSNs with Statistical Learning Model." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/56295014950782203777.
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碩士國立交通大學
資訊科學與工程研究所
95
Conventional anomaly detection schemes for WSNs require special detection nodes to monitor node behaviors. These schemes also need long training time to model sensor node behaviors and construct node profiles. When a node deviates from its node behavior profile, it is considered as anomaly. In this type of schemes, it is common to use a predetermined threshold to differentiate anomalous activities. However, node behavior may vary over time, and therefore a fixed threshold may not be able to accurately differentiate anomalies. In this paper, we propose a threshold estimation method which combines the Grey Prediction Model and Markov Residual Error Model to model normal node behaviors, and can dynamically adjust the threshold to adapt to the changing behavior of WSNs. Our approach can be easily used in a WSN without the need for special detection nodes. As the experimental results showed, our proposed method can detect anomalous WSN behaviors in a more accurate and effective way than conventional schemes.
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Chang, Shu-Yu, and 張書瑜. "RD Guided Adaptive Sampling for Transmission Reduction on WSNs." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/33461813136754887354.
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碩士國立清華大學
資訊工程學系
100
Wireless Sensor Networks (WSNs) have been widely applied to many different areas such as surveillance, healthcare, environmental and utility monitoring, etc. In WSNs, each sensor node has the characteristics of small size, limited power, and connected wirelessly. It is responsible for gathering and delivering sensing data over the network periodically. Thus, the energy consumption problem becomes a challenging issue to prolong the lifetime of WSNs. Several research works utilize data aggregation and/or data compression concept to reduce the quantity of necessary transmission, since it is the primary issue that consumes sensors’ power particularly. However, the implementation of these operations requires high computational power. In this thesis, two approaches adapting to sensing data distribution to largely reduce the amount of required data transmission with limited computation are proposed. They are: Adaptive Sampling with RD Model and Adaptive Sampling in Dynamic Mode. In the first approach, the target distortion is near-optimally distributed (in the rate-distortion sense) to every sensor node corresponding to their relative fluctuation. In the latter one, the possible occurrence of rapid data change in the sensing period is concerned and deliberately manipulated. To combine these two methods, we verify the data trend of each sensor when the prediction function needs to be updated. Then according to the data trend we can decide whether to use Adaptive Sampling with RD Model or Adaptive Sampling in Dynamic Mode. Finally, several real sensed data were gathered and employed to demonstrate the performance of the proposed methods.