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1
Resul, Hulya. "Node replication detection in sensor networks". College Park, Md. : University of Maryland, 2005. http://hdl.handle.net/1903/3253.
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Thesis (M.S.) -- University of Maryland, College Park, 2005.Thesis research directed by: Dept. of Electrical and Computer Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Chen, Wan Qing. "Predictors of Auxillary Lymph Node Involvement in Screen Detected Breast Cancer". Thesis, The University of Sydney, 2004. http://hdl.handle.net/2123/676.
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Background: Axillary lymph node dissection as routine part of breast cancer treatment has been questioned in relation to the balance between benefits and morbidity. The purpose of this study is to determine the association of tumor size, age and histological grade with axillary lymph node metastasis, to determine if some patients could be exempted from axillary dissection. Methods: The data are derived from BreastScreen NSW, the government sponsored population-based breast screening program. In New South Wales (NSW) Australia between 1995 and 2002, 7,221 patients with invasive breast carcinoma were diagnosed and 5,290 patients were eligible for this study. The relationship between incidence of positive axillary lymph nodes and three study factors (tumor size, age and histological grade) was investigated by univariate and multivariate analysis. Logistic regression models were used to predict probability of axillary metastases. Results: The incidence of axillary lymph node metastases was 28.6% (95% CI: 27.4%- 29.8%). Univariate analysis showed that age, tumor size and histological grade were significant predictors of axillary lymph node metastases (p<0.0001). Multivariate analysis identified age, tumor size and histological grade remained as independent predictors (p<0.0001). From multivariate analysis, patients with T1a (Less than or equal to 5mm) and grade I tumors regardless of age had 5.2% (95% CI: 1.2%- 9.3%) frequency of node metastases. Patients 70 years or older with grade I, T1a and T1b (6-10mm) tumors had 4.9% (95% CI: 3.2%- 7.5%) and 6.6% (95% CI: 5.3%-8.3%) predicted frequency of node metastases. Conclusions: Tumor size, age and histological grade are predictors of axillary lymph node metastases. Routine axillary lymph node dissection could be avoided in some patient groups with a low frequency of involved lymph nodes if the benefits are considered to exceed the risks.
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Chen, Wan Qing. "Predictors of Auxillary Lymph Node Involvement in Screen Detected Breast Cancer". University of Sydney. Public Health, 2004. http://hdl.handle.net/2123/676.
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Background: Axillary lymph node dissection as routine part of breast cancer treatment has been questioned in relation to the balance between benefits and morbidity. The purpose of this study is to determine the association of tumor size, age and histological grade with axillary lymph node metastasis, to determine if some patients could be exempted from axillary dissection. Methods: The data are derived from BreastScreen NSW, the government sponsored population-based breast screening program. In New South Wales (NSW) Australia between 1995 and 2002, 7,221 patients with invasive breast carcinoma were diagnosed and 5,290 patients were eligible for this study. The relationship between incidence of positive axillary lymph nodes and three study factors (tumor size, age and histological grade) was investigated by univariate and multivariate analysis. Logistic regression models were used to predict probability of axillary metastases. Results: The incidence of axillary lymph node metastases was 28.6% (95% CI: 27.4%- 29.8%). Univariate analysis showed that age, tumor size and histological grade were significant predictors of axillary lymph node metastases (p<0.0001). Multivariate analysis identified age, tumor size and histological grade remained as independent predictors (p<0.0001). From multivariate analysis, patients with T1a (Less than or equal to 5mm) and grade I tumors regardless of age had 5.2% (95% CI: 1.2%- 9.3%) frequency of node metastases. Patients 70 years or older with grade I, T1a and T1b (6-10mm) tumors had 4.9% (95% CI: 3.2%- 7.5%) and 6.6% (95% CI: 5.3%-8.3%) predicted frequency of node metastases. Conclusions: Tumor size, age and histological grade are predictors of axillary lymph node metastases. Routine axillary lymph node dissection could be avoided in some patient groups with a low frequency of involved lymph nodes if the benefits are considered to exceed the risks.
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Schleip, Christoph. "Climate change detection in natural systems by Bayesian methods". kostenfrei, 2009. http://mediatum2.ub.tum.de/node?id=805580.
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Kotari, Ravi Teja. "Node failure detection and data retrieval in wireless sensor networks". Thesis, California State University, Long Beach, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10108190.
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This project presents a method for detecting node failure in a wireless sensor network. The defective node is identified using round-trip delay measurements. Data transfer from the transmitter section to the receiver section is accomplished via the ZigBee protocol. As soon as a node has been identified as defective, the node is removed from the sensor network. Information about the failed node is provided to users with registered mobile device through the Global System for Mobile (GSM) module. The proposed method has been successfully implemented and tested experimentally on a small sensor network using the LPC2148 ARM7 microcontroller.
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Pettersson, Christopher. "Automatic fault detection and localization in IPnetworks : Active probing from a single node perspective". Thesis, Linköpings universitet, Programvara och system, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-120414.
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Fault management is a continuously demanded function in any kind of network management. Commonly it is carried out by a centralized entity on the network which correlates collected information into likely diagnoses of the current system states. We survey the use of active-on-demand-measurement, often called active probes, together with passive readings from the perspective of one single node. The solution is confined to the node and is isolated from the surrounding environment. The utility for this approach, to fault diagnosis, was found to depend on the environment in which the specific node was located within. Conclusively, the less environment knowledge, the more useful this solution presents. Consequently this approach to fault diagnosis offers limited opportunities in the test environment. However, greater prospects was found for this approach while located in a heterogeneous customer environment.
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Al-Riyami, Ahmed. "Towards an adaptive solution to data privacy protection in hierarchical wireless sensor networks". Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/towards-an-adaptive-solution-to-data-privacy-protection-in-hierarchical-wireless-sensor-networks(a096db2a-251c-4e9e-a4ff-8bfe4c6f1bf4).html.
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Hierarchical Wireless Sensor networks (WSNs) are becoming attractive to many applications due to their energy efficiency and scalability. However, if such networks are deployed in a privacy sensitive application context such as home utility consumption, protecting data privacy becomes an essential requirement. Our threat analysis in such networks has revealed that PPDA (Privacy Preserving Data Aggregation), NIDA (Node ID Anonymity) and ENCD (Early Node Compromise Detection) are three essential properties for protecting data privacy. The scope of this thesis is on protecting data privacy in hierarchical WSNs byaddressing issues in relation to two of the three properties identified, i.e., NIDA and ENCD, effectively and efficiently. The effectiveness property is achieved by considering NIDA and ENCD in an integrated manner, and the efficiency property is achieved by using an adaptive approach to security provisioning. To this end, the thesis has made the following four novel contributions. Firstly, this thesis presents a comprehensive analysis of the threats to data privacy and literature review of the countermeasures proposed to address these threats. The analysis and literature review have led to the identification of two main areas for improvements: (1) to reduce the resources consumed as the result of protecting data privacy, and (2) to address the compatibility issue between NIDA and ENCD.Secondly, a novel Adaptive Pseudonym Length Estimation (AdaptPLE) method has been proposed. The method allows the determination of a minimum acceptable length of the pseudonyms used in NIDA based on a given set of security and application related requirements and constraints. In this way, we can balance the trade-off between an ID anonymity protection level and the costs (i.e., transmission and energy) incurred in achieving the protection level. To demonstrate its effectiveness, we have evaluated the method by applying it to two existing NIDA schemes, the Efficient Anonymous Communication (EAC) scheme and theCryptographic Anonymous Scheme (CAS).Thirdly, a novel Adaptive Early Node Compromise Detection (AdaptENCD) scheme for cluster-based WSNs has been proposed. This scheme allows early detections of compromised nodes more effectively and efficiently than existing proposals. This is achieved by adjusting, at run-time, the transmission rate of heartbeat messages, used to detect nodes' aliveness, in response to the average message loss ratio in a cluster. This adaptive approach allows us to significantly reduce detection errors while keeping the number of transmitted heartbeat messages as low as possible, thus reducing transmission costs. Fourthly, a novel Node ID Anonymity Preserving Scheme (ID-APS) for clusterbased WSNs has been proposed. ID-APS protects nodes ID anonymity while, at the same time, also allowing the global identification of nodes. This later property supports the identification and removal of compromised nodes in the network, which is a significant improvement over the state-of-the-art solution, the CAS scheme. ID-APS supports both NIDA and ENCD by making a hybrid use of dynamic and global identification pseudonyms. More importantly, ID-APS achieves these properties with less overhead costs than CAS. All proposed solutions have been analysed and evaluated comprehensively to prove their effectiveness and efficiency.
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Barrus, Joseph D. "Intrusion detection in real-time in a multi-node, multi-host environment". Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1997. http://handle.dtic.mil/100.2/ADA341406.
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Thesis (M.S. in Software Engineering) Naval Postgraduate School, September 1997."September 1997." Thesis advisor(s): Neil C. Rowe, Ronald Broersma. Includes bibliography references (p. 77). Also available online.
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Khanapure, Vishal. "Memory efficient distributed detection of node replication attacks in wireless sensor networks". [Gainesville, Fla.] : University of Florida, 2009. http://purl.fcla.edu/fcla/etd/UFE0025072.
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Thekedar, Bhushan. "Investigations on the use of breath gas analysis with Proton Transfer Reaction Mass Spectrometry (PTR-MS) for a non-invasive method of early lung cancer detection". kostenfrei, 2009. https://mediatum2.ub.tum.de/node?id=821780.
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Hoblos, Jalaa. "Selfish Node Misbehaving Statistical Detection with Active MAC Layer NAV Attack in Wireless Networks}". [Kent, Ohio] : Kent State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=kent1164119272.
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Kano, Masato. "Detection of Lymph Node Metasatasis of Oesophageal Cancer by RT-nested PCR for SCC antigen mRNA". Kyoto University, 2001. http://hdl.handle.net/2433/150176.
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Jauhar, Ahmad Shujauddin. "A CMA-FRESH Whitening Filter for Blind Interference Rejection". Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/85389.
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The advent of spectrum sharing has increased the need for robust interference rejection methods. The Citizens Broadband Radio Service (CBRS) band is soon to be occupied by LTE waveforms and License Assisted Access (LAA) will have LTE signals coexisting with other signals in the 5 GHz band. In anticipation of this need, we present a method for interference rejection of cyclostationary signals, which can also help avoid interference through better detection of low power co-channel signals. The method proposed in this thesis consists of a frequency-shift (FRESH) filter which acts as a whitening filter, canceling the interference by exploiting its cyclostationarity. It learns the cyclostationary characteristics of the interferer blindly, through a property restoration algorithm which aims to drive the spectrum to white noise. The property restoration algorithm, inspired by the constant modulus algorithm (CMA), is applied to each frequency bin to determine the optimal coefficients for the proposed CMA FRESH whitening filter (CFW). The performance of the CFW in interference rejection is compared to a time-invariant version, and proposed use cases are analyzed. The use cases consist of the rejection of a high powered, wider bandwidth interferer which is masking the signal-of-interest (SOI). The interferer is rejected blindly, with no knowledge of its characteristics. We analyzed signal detection performance in the case that the SOI is another user with much lower power, for multiple types of SOIs ranging from BPSK to OFDM. We also deal with the case that the SOI is to be received and demodulated; we recover it and compare resulting bit error rates to state of the art FRESH filters. The results show significantly better signal detection and recovery.Master of Science
Wireless communication is complicated by the fact that multiple radios may be attempting to transmit at the same frequency, time and location concurrently. This scenario may be a due to malicious intent by certain radios (jamming), or mere confusion due to a lack of knowledge that another radio is transmitting in the same channel. The latter scenario is more common due to congested wireless spectrum, as the number of devices increases exponentially. In either case, interference results. We present a novel interference rejection method in this work, one that is blind to the properties of the interferer and adapts to cancel it. It follows the philosophy of property restoration as extolled by the constant modulus algorithm (CMA) and is a frequency shift (FRESH) filter, hence the name. The process of restoring the wireless spectrum to white noise is what makes it a whitening filter, and is also how it adapts to cancel interference. Such a filter has myriad possible uses, and we examine the use case of rejecting interference to detect or recover the signal-of-interest (SOI) that we are attempting to receive. We present performance results in both cases and compare with conventional time-invariant filters and state of the art FRESH filters.
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Marits, Per. "On CD4+ T Lymphocytes in Solid Tumours". Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8325.
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Zia, Tanveer. "A Security Framework for Wireless Sensor Networks". University of Sydney, 2008. http://hdl.handle.net/2123/2258.
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Doctor of Philosophy (PhD)Sensor networks have great potential to be employed in mission critical situations like battlefields but also in more everyday security and commercial applications such as building and traffic surveillance, habitat monitoring and smart homes etc. However, wireless sensor networks pose unique security challenges. While the deployment of sensor nodes in an unattended environment makes the networks vulnerable to a variety of potential attacks, the inherent power and memory limitations of sensor nodes makes conventional security solutions unfeasible. Though there has been some development in the field of sensor network security, the solutions presented thus far address only some of security problems faced. This research presents a security framework WSNSF (Wireless Sensor Networks Security Framework) to provide a comprehensive security solution against the known attacks in sensor networks. The proposed framework consists of four interacting components: a secure triple-key (STKS) scheme, secure routing algorithms (SRAs), a secure localization technique (SLT) and a malicious node detection mechanism. Singly, each of these components can achieve certain level of security. However, when deployed as a framework, a high degree of security is achievable. WSNSF takes into consideration the communication and computation limitations of sensor networks. While there is always a trade off between security and performance, experimental results prove that the proposed framework can achieve high degree of security with negligible overheads.
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Jafarian, Javad. "Modelling and analysis of wireless MAC protocols with applications to vehicular networks". Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/modelling-and-analysis-of-wireless-mac-protocols-with-applications-to-vehicular-networks(3695e637-12eb-4fde-9c31-08b3b46e8f55).html.
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The popularity of the wireless networks is so great that we will soon reach the point where most of the devices work based on that, but new challenges in wireless channel access will be created with these increasingly widespread wireless communications. Multi-channel CSMA protocols have been designed to enhance the throughput of the next generation wireless networks compared to single-channel protocols. However, their performance analysis still needs careful considerations. In this thesis, a set of techniques are proposed to model and analyse the CSMA protocols in terms of channel sensing and channel access. In that respect, the performance analysis of un-slotted multi-channel CSMA protocols is studied through considering the hidden terminals. In the modelling phase, important parameters such as shadowing and path loss impairments are being considered. Following that, due to the high importance of spectrum sensing in CSMA protocols, the Double-Threshold Energy Detector (DTED) is thoroughly investigated in this thesis. An iterative algorithm is also proposed to determine optimum values of detection parameters in a sensing-throughput problem formulation. Vehicle-to-Roadside (V2R) communication, as a part of Intelligent Transportation System (ITS), over multi-channel wireless networks is also modelled and analysed in this thesis. In this respect, through proposing a novel mathematical model, the connectivity level which an arbitrary vehicle experiences during its packet transmission with a RSU is also investigated.
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Cochran, Travis. "Ultra Low Power Wake-up Receiver with Unique Node Addressing for Wireless Sensor Nodes". Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/76909.
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Power consumption and battery life are of critical importance for medical implant devices. For this reason, devices for Wireless Body Area Network (WBAN) applications must consume very little power. To save power, it is desirable to turn off or put to sleep a device when not in use. However, a transceiver, which is the most power hungry block of a wireless sensor node, needs to listen for the incoming signal continuously. An alternative scheme, is to listen for the incoming signal at a predetermined internal, which saves power at the cost of increased latency. Another and more sophisticated scheme is to provide a wake-up receiver, which listens for the incoming signal continuously, and upon detection of an incoming signal, it wakes the primary transceiver up. A wake-up receiver is typically simple and dissipates little power to make the scheme useful.
This thesis proposes a low-power wake-up receiver, which listens for a wake-up signal, identifies the target node, and wakes up the primary receiver only when that specific node is called upon. When a wake up signal is transmitted to all of the nodes on a network, our wake-up receiver allows all the nodes on a network except the targeted node to remain asleep to save power. Several wake-up receiver topologies have been proposed. This work uses a passive Cockcroft-Walton multiplier circuit as an RF envelope detector followed by a simple detector circuit. A novel serial code detector is then used to decode the pulse width modulated input signal to wake-up the designated node. A passive RF front end and simple decoding circuit reduce power consumption substantially at the cost of low sensitivity. The sensitivity of the wake-up receiver can be improved though the addition of an RF amplifier, but at the cost of increased power consumption.Master of Science
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Sabo, Jozef. "Aplikace metody učení bez učitele na hledání podobných grafů". Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2021. http://www.nusl.cz/ntk/nusl-445517.
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Goal of this master's thesis was in cooperation with the company Avast to design a system, which can extract knowledge from a database of graphs. Graphs, used for data mining, describe behaviour of computer systems and they are anonymously inserted into the company's database from systems of the company's products users. Each graph in the database can be assigned with one of two labels: clean or malware (malicious) graph. The task of the proposed self-learning system is to find clusters of graphs in the graph database, in which the classes of graphs do not mix. Graph clusters with only one class of graphs can be interpreted as different types of clean or malware graphs and they are a useful source of further analysis on the graphs. To evaluate the quality of the clusters, a custom metric, named as monochromaticity, was designed. The metric evaluates the quality of the clusters based on how much clean and malware graphs are mixed in the clusters. The best results of the metric were obtained when vector representations of graphs were created by a deep learning model (variational graph autoencoder with two relation graph convolution operators) and the parameterless method MeanShift was used for clustering over vectors.
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Ru, Jifeng. "Adaptive estimation and detection techniques with applications". ScholarWorks@UNO, 2005. http://louisdl.louislibraries.org/u?/NOD,285.
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Thesis (Ph. D.)--University of New Orleans, 2005.Title from electronic submission form. "A dissertation ... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Engineering and Applied Science"--Dissertation t.p. Vita. Includes bibliographical references.
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Rinne, Vidar. "A Zoomable 3D User Interface using Uniform Grids and Scene Graphs". Thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-13360.
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Zoomable user interfaces (ZUIs) have been studied for a long time and many applications are built upon them. Most applications, however, only use two dimensions to express the content. This report presents a solution using all three dimensions where the base features are built as a framework with uniform grids and scene graphs as primary data structures. The purpose of these data structures is to improve performance while maintaining flexibility when creating and handling three-dimensional objects. A 3D-ZUI is able to represent the view of the world and its objects in a more lifelike manner. It is possible to interact with the objects much in the same way as in real world. By developing a prototype framework as well as some example applications, the usefulness of 3D-ZUIs is illustrated. Since the framework relies on abstraction and object-oriented principles it is easy to maintain and extend it as needed. The currently implemented data structures are well motivated for a large scale 3D-ZUI in terms of accelerated collision detection and picking and they also provide a flexible base when developing applications. It is possible to further improve performance of the framework, for example by supporting different types of culling and levels of detail
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Yang, Ling. "Nodes failure detection in large scale network". Thesis, The University of Sydney, 2005. https://hdl.handle.net/2123/27923.
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It is the age of information technology. Around the world, millions of computers
are being linked together in networks of all sizes, from small local area
networks to giant enterprise wide area networks. This rapid growth means a lot
of opportunity for people working or preparing to work, in the computer
industry.
In today’s world of LANs and WANs, almost all business depends on
internetworking for data communication. From the world wide internet to
private intranet, internetworking technology is present in virtually every aspect
of a business technical operation. And in this age of information technology it is
very important to discover network failure as soon as possible.
in this project, we present a set of methods to detect network nodes failure and
predict network nodes failure with failure reasons. We describe the design and
implementation by using a resource-combined algorithm, Nai've Bayes
Classifier and Bayes Network.
Results show that with the resource-combined algorithm the performance of
actual nodes failure detection can be improved. Results also show that
network nodes failure can be predicted in a fixed time before actual failure with
a high degree of accuracy.
22
Nilsson, Kent. "Detection of wood decay using an electronic nose /". Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1998. http://epsilon.slu.se/avh/1998/91-576-5602-9.gif.
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Kumar, Kavitha. "Intrusion Detection in Mobile Adhoc Networks". Connect to full text in OhioLINK ETD Center, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=toledo1260232844.
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Thesis (M.S.)--University of Toledo, 2009.Typescript. "Submitted to the Graduate Faculty as partial fulfillment of the requirements for the Master of Science Degree in Engineering." "A thesis entitled"--at head of title. Bibliography: leaves 80-84.
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Bhamidipati, Harini. "SINGLE TROJAN INJECTION MODEL GENERATION AND DETECTION". Case Western Reserve University School of Graduate Studies / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=case1253543191.
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Singamsetty, Ratna Sireesha. "Detection of Malicious Nodes in Mobile Ad hoc Networks". University of Toledo / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1321043030.
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Megahed, Mohamed Helmy Mostafa. "SurvSec Security Architecture for Reliable Surveillance WSN Recovery from Base Station Failure". Thèse, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31154.
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Surveillance wireless sensor networks (WSNs) are highly vulnerable to the failure of the base station (BS) because attackers can easily render the network useless for relatively long periods of time by only destroying the BS. The time and effort needed to destroy the BS is much less than that needed to destroy the numerous sensing nodes.
Previous works have tackled BS failure by deploying a mobile BS or by using multiple BSs, which requires extra cost. Moreover, despite using the best electronic countermeasures, intrusion tolerance systems and anti-traffic analysis strategies to protect the BSs, an adversary can still destroy them. The new BS cannot trust the deployed sensor nodes. Also, previous works lack both the procedures to ensure network reliability and security during BS failure such as storing then sending reports concerning security threats against nodes to the new BS and the procedures to verify the trustworthiness of the deployed sensing nodes. Otherwise, a new WSN must be re-deployed which involves a high cost and requires time for the deployment and setup of the new WSN. In this thesis, we address the problem of reliable recovery from a BS failure by proposing a new security architecture called Surveillance Security (SurvSec).
SurvSec continuously monitors the network for security threats and stores data related to node security, detects and authenticates the new BS, and recovers the stored data at the new BS. SurvSec includes encryption for security-related information using an efficient dynamic secret sharing algorithm, where previous work has high computations for dynamic secret sharing. SurvSec includes compromised nodes detection protocol against collaborative work of attackers working at the same time where previous works have been inefficient against collaborative work of attackers working at the same time.
SurvSec includes a key management scheme for homogenous WSN, where previous works assume heterogeneous WSN using High-end Sensor Nodes (HSN) which are the best target for the attackers. SurvSec includes efficient encryption architecture against quantum computers with a low time delay for encryption and decryption, where previous works have had high time delay to encrypt and decrypt large data size, where AES-256 has 14 rounds and high delay. SurvSec consists of five components, which are:
1. A Hierarchical Data Storage and Data Recovery System.
2. Security for the Stored Data using a new dynamic secret sharing algorithm.
3. A Compromised-Nodes Detection Algorithm at the first stage.
4. A Hybrid and Dynamic Key Management scheme for homogenous network.
5. Powerful Encryption Architecture for post-quantum computers with low time delay.
In this thesis, we introduce six new contributions which are the followings:
1. The development of the new security architecture called Surveillance Security (SurvSec) based on distributed Security Managers (SMs) to enable distributed network security and distributed secure storage.
2. The design of a new dynamic secret sharing algorithm to secure the stored data by using distributed users tables.
3. A new algorithm to detect compromised nodes at the first stage, when a group of attackers capture many legitimate nodes after the base station destruction. This algorithm is designed to be resistant against a group of attackers working at the same time to compromise many legitimate nodes during the base station failure.
4. A hybrid and dynamic key management scheme for homogenous network which is called certificates shared verification key management.
5. A new encryption architecture which is called the spread spectrum encryption architecture SSEA to resist quantum-computers attacks.
6. Hardware implementation of reliable network recovery from BS failure.
The description of the new security architecture SurvSec components is done followed by a simulation and analytical study of the proposed solutions to show its performance.
27
Westling, Magnus. "Microbial Processes and Volatile Metabolites in Cheese Detection of Bacteria Using an Electronic Nose". Thesis, Örebro universitet, Institutionen för naturvetenskap och teknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-42412.
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Cheese is a fermented product in which bacteria contribute to different flavours and textures. In order to understand the microbial processes in cheese, it is necessary to not only look at the genomic information in bacteria. The metabolome consists of a complete collection of metabolites in a biological sample. These metabolites are small molecules with a Mr >1.5 kDa, including flavour compounds. During the ripening process of cheese, many microbiological and biochemical changes occur that give cheese a diversity of textures and flavours. Proteins that go through proteolysis and amino acid catabolism are of great importance in the development of flavour in cheese, regardless of variety. Even though techniques for measurements of metabolites have existed for a long time, there are some unique challenges by analysing of several metabolites in parallel in a biological sample that promotes different metabolic pathways. Metabolic fingerprinting is the most common approach used in metabolomics, which is based on statistical analysis that through algorithms presents differences between samples. The electronic nose is able to identify the sum of volatile metabolites in a food, which is unlike the gas chromatograph that identifies individual metabolites. The aim of this review is to evaluate the use of metabolomics of selected Enterobacteriaceae together with electronic nose technology in order to analyse possible patterns of volatile metabolites produced in soft cheese. By this we hope to evaluate potential application of this approach in food quality control and microbial contamination screening. The pilot study was done together with the center for AASS, Örebro University where bacteria were analysed using the electronic nose NST3320. The study showed that it is possible to discriminate between Enterobacteriaceae, Staphylococcus aureus and cheese-associated bacteria, but also between the Enterobacteriaceae species Escherichia coli, Hafnia alvei and Klebsiella neumoniae. It is important to consider the gas sensors gradually lose their ability to detect substances after continual use, in which they need to be replaced with new gas sensors. Further, data processing requires special knowledge and can be hard to handle if the expertise is lacking. We believe that there is evidence that metabolomics together with the electronic nose have future prospects in terms of quality control and microbial contamination screening.
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Barr, Elaine Lewis. "Acoustic sampling considerations for bats in the post-white-nose syndrome landscape". Thesis, Virginia Tech, 2020. http://hdl.handle.net/10919/104232.
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Bat populations across North America are either facing new threats from white-nose syndrome (WNS) and wind energy development or have already experienced precipitous declines. Accordingly, researchers and managers need to know how to best monitor bats to document population and distribution changes, as well as where to look for persisting populations. Landscape-scale WNS impacts to summer bat populations are not well understood, and although acoustic monitoring is commonly used to monitor these populations, there is limited information about differences among acoustic detectors and the implications to managers thereof. My objectives were to model the relationship between WNS impact, influence of available hibernacula, and environmental factors for summer nightly presence of three WNS-affected bats and to compare how multiple models of acoustic detectors perform in terms of detection probability and nightly recorded bat activity. I collected acoustic data from 10 study areas across Virginia, West Virginia, Ohio and Kentucky to describe changes in nightly presence of WNS-affected bat species during summer 2017. During the same period of time, I compared five types of acoustic detectors at Fort Knox, Kentucky. My results show the potential efficacy of using a WNS impact-year metric to predict summer bat presence, and highlight which environmental variables are relevant for large-scale acoustic monitoring. Additionally, my findings suggest that each of the detector types tested would suffice for most research and monitoring activities, but standardization of detector type within the scope of a project or study should be encouraged.Master of Science
Bat populations across North America are either facing new threats from white-nose syndrome (WNS) and wind energy development or have already experienced devastating declines. Accordingly, wildlife biologists need to know how to best monitor bats to document population and distribution changes, as well as where to look for remaining populations. Landscape-scale WNS impacts to summer bat populations are not well understood, and although acoustic technology is commonly used to monitor these populations, there is limited information about differences among acoustic detectors and the implications to managers thereof. My objectives were to model the relationship between WNS impact, influence of available bat hibernation caves, and environmental factors for summer nightly presence of three WNS-affected bats and to compare how multiple models of acoustic detectors perform in terms of detection probability and nightly recorded bat activity. I collected acoustic data from 10 study areas across Virginia, West Virginia, Ohio and Kentucky to describe changes in nightly presence of WNS-affected bat species during summer 2017. During the same period of time, I compared five types of acoustic detectors at Fort Knox, Kentucky. My results show potential viability of a WNS impact-year metric to predict summer bat presence, and highlight which environmental variables are relevant for large-scale acoustic monitoring. Additionally, my findings suggest that each of the detector types tested would suit most research and monitoring activities, but standardization of detector type within the scope of a project or study should be encouraged.
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Liu, Hongxun. "Hardware assisted misbehaving nodes detection in mobile ad hoc networks". Online access for everyone, 2007. http://www.dissertations.wsu.edu/Dissertations/Summer2007/h_liu_072507.pdf.
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Sahbai, Samine [Verfasser]. "Scintigraphic detection of sentinel nodes in endometrial cancer / Samine Sahbai". Tübingen : Universitätsbibliothek Tübingen, 2019. http://d-nb.info/1227963939/34.
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Sharma, Nikita. "Detection of Similarly-structured Anomalous sets of nodes in Graphs". University of Cincinnati / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1627665644265336.
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Martinez, Rebecca L. "Chemosensory Evaluation of Prostate Cancer Cells". Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/46316.
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Prostate cancer is the most commonly diagnosed disease and second most commonly caused death among men in America. Although much controversy surrounds the current methods of detection, PSA test and biopsy, no new methods have been approved as an effective method of detection. Biomarkers and non-invasive means of detection are being investigated everyday in hopes of discovering new information that could be of use in the prostate cancer field.
One such non-invasive technology is the use of an electronic nose. The electronic nose technology has been utilized in the agricultural, food, biomedical, and environmental. The objective of this current study is to determine the effectiveness of the electronic nose to discriminate between prostate cancer cells (DU-145 and PC-3) and non-tumor forming cells from the urinary tract (SVHUC). Specific factors that will be investigated are incubation period and cell population.
For all three cell lines, two cell populations of 75,000 and 150,000 cells were cultured and tested after 2, 8, 12, and 24 hours using a conducting polymer based hand-held electronic nose. Multivariate analysis was performed on the data and determined that the greatest discrimination between incubation periods was between 2 hours of incubation and the remaining periods of 8, 12, and 24 hour periods. This presents the idea that by 8 hours, ample volatiles were produced to be detected by the electronic nose. Additionally, when compared to one another, all three cell lines showed distinct differences. The cell lines most closely related were PC-3 and DU-145, the prostate cancer cell lines. However some variation was seen between these cell lines, which may be attributed to the presence of PSA in PC-3 cells or other factors affecting prostate cancer patients. Finally, PCA plots clearly illustrated that after 2 hours of incubation, sufficient volatiles were produced to allow the electronic nose to clearly discriminate the three cell lines from one another, demonstrating the importance of incubation period on successful discrimination.
Based on the findings that the electronic nose was effective at discriminating the three cell lines, testing was completed to determine if cell population or cell maturity had the greatest effect on discrimination. The cell lines were cultured and tested immediately using an initial cell population of the highest cell population observed after a 72 hour incubation period. The results concluded that when the cell lines were tested immediately after culturing, the Cyranose was able to detect the individual cell lines in culture while also determining a range of detection for each cell line. The range of detection for DU-145 was found to be 26,200 to 262,000 cells based on interclass m-distances of 6.829-9.170 for cell populations lower than 26,200. A range of detection of 51,400 to 514,000 cells was concluded for PC-3 cells based on interclass m-distances of 5.690-7.400 for cell populations lower than 51,400. Finally, the results showed a range of detection of 19,000 to 190,000 cells for SVHUC based on interclass m-distances of 5.520-9.076 for cell populations lower than 19,000. However, when attempting to discriminate the three cell lines against one another immediately after culture, the electronic nose was unable to make clear distinctions between the three cell lines. When testing cancerous and non-cancerous cells, incubation period of the cells should be the only factor considered. It is evident that the cells need time to metabolize and produce volatiles so that the electronic nose can clearly distinguish these cells from one another in culture.Master of Science
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Albert, Keith J. "Microbead array-based artificial nose : explosives detection and simple/complex odor discrimination /". Thesis, Connect to Dissertations & Theses @ Tufts University, 2001.
Znajdź pełny tekst źródłaStreszczenie:
Thesis (Ph.D.)--Tufts University, 2001.Adviser: David R. Walt. Submitted to the Dept. of Chemistry. Includes bibliographical references. Access restricted to members of the Tufts University community. Also available via the World Wide Web;
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Kershri, G. "Novel food applications of electronic nose technology for detection of spoilage fungi". Thesis, Cranfield University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.392743.
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Zaidi, Syed. "Detecting rogue nodes in vehicular ad-hoc networks (DETER)". Thesis, City, University of London, 2016. http://openaccess.city.ac.uk/17029/.
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Vehicular ad hoc Networks (VANETs) are self-organizing networks of vehicles equipped with radios and processors. VANETs are very promising as they can make driving safer by improving road awareness through sharing of information from sensors. Vehicles communicate with each other wirelessly to exchange information and this exchange of information is susceptible to attacks of different kinds. There are some very important issues that need to be resolved before VANETs can be deployed on large scale. Security and privacy issues are undoubtedly the most important factors that need to be resolved. Amongst various problems to be solved in VANETs is the issue of rogue nodes and their impact on the network. This thesis discusses the problems associated with the security and privacy of vehicular networks in the presence of rogue nodes. The rogue nodes can share/inject false data in the network which can cause serious harm. The techniques proposed make VANETs secure and prevent them from the harmful impact of rogue nodes. The proposed work makes the network safer by making it fault tolerant and resilient in the presence of rogue nodes that can be detected and reported. As VANETs are highly dynamic and fast moving so, a data centric scheme is proposed that can determine if a node is rogue or not just by analysing its data. The work then enhances the developed mechanism by applying hypothesis testing and other statistical techniques to detect intrusions in the network by rogue nodes. The technique is simulated using OMNET++, SUMO and VACAMobil and the results obtained have been presented, discussed and compared to previous works. In order to prevent rogue nodes from becoming part of the VANETs this thesis also presents a novel framework for managing the digital identity in the vehicular networks. This framework authenticates the user and the vehicle separately from two authorities and allows him to communicate securely with the infrastructure using IBE (Identity Based Encryption). The proposed technique also preserves the privacy of the user. The proposed scheme allows traceability and revocation so that users can be held accountable and penalised. The results have been compared to previous works of similar nature. The thesis also discusses the Sybil attack and how to detect them using game theory in a VANET environment.
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McDonald, Louise Ann. "A Comparison Of The Detection Of Tumour Cells In Cervical Lymph Nodes Of Patients With Head And Neck Squamous Cell Carcinoma By Testing For Spliced Transcripts Of Cytokeratin 5 Immunohistochemistry Or Light Microscopy; And The Prognostic Effect Compared With That Of Other Factors". Thesis, The University of Sydney, 2002. http://hdl.handle.net/2123/4456.
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Needham, Rachel. "Early detection and differentiation of microbial spoilage of bread using electronic nose technology". Thesis, Cranfield University, 2004. http://hdl.handle.net/1826/786.
Pełny tekst źródłaStreszczenie:
This study investigated the potential for use of electronic noses (e-noses) for early
rapid detection and differentiation of bread spoilage before visible signs of growth
occur. After 24 h incubation at 25°C it was possible to distinguish Penicillium
verrucosum, Aspergillus ochraceus, and Pichia anomala from 3 different species of
filamentous fungi before visible growth was observed on unmodified wheat agar using
a conducting polymer based e-nose (BH114). Discrimination of controls was possible
after 48 h. The BH114 e-nose was able to differentiate between Pseudomonas fragi,
Saccharomyces cerevisiae and P. verrucosum growing on 0.97 aw modified flour-based
media after only 24 h. The BH114 e-nose was able to discriminate between P. fragi
and S. cerevisiae growing in broth cultures and between different aw controls in
exponential growth (13.5 h). Discrimination of Staphylococcus aureus growing in
different aw broths and from uninoculated controls was achieved after 4.5 h.
The BH114 e-nose was also able to detect and differentiate microbial spoilage in situ
using bread analogues. Discrimination was improved using an incubation temperature
of 25°C when compared to 15°C. Discrimination of microbial and physiological
(enzymic) spoilage of bread analogues was possible using e-nose technology, cfu
counts and gas chromatograph-mass spectrometry (GC-MS) using an initial population
of 106 spores/cells ml-1. After 48 h differentiation of the spoilage types and between
some of the microbial spoilage organisms was possible using the e-nose. A significant
increase in populations was noted between 24 and 48 h. There were significant
differences between microbial populations detected after 48 and 72 h. Analysis of
volatile compounds produced, using GC-MS, showed that after 24 h P. anomala was
the only treatment to produce 2-propanol, ethyl acetate, and pentanol. P. anomala also
produced greater amounts of 3-methylbutanol when compared to P. verrucosum, B.
subtilis, lipoxygenase spoilage and controls.
Differentiation between toxigenic and non-toxigenic strains of Aspergillus parasiticus
in vitro was not achieved. However, in vitro on unmodified 2% wheat agar it was
possible to differentiate a non-toxigenic P. verrucosum strain from 4 citrinin producing
strains and controls using the BH114 e-nose. On bread analogues it was possible to discriminate two ochratoxin A (OTA) producing P. verrucosum strains after 24 h using
an initial population of 106 spore ml-1. Increased incubation resulted in only controls
being discriminated. Using a lower initial population of 103 spores ml-1 only controls
were discriminated after 24 h. However, after 48 h an OTA producing strain could also
be differentiated.
The potential for use of e-noses as a tool for screening novel antioxidants was also
investigated. It was possible to differentiate between broth samples with and without
the antioxidants propyl paraben and butylated hydroxyanisole using both the
conductance based e-nose (BH114) and a metal oxide and metal ion based e-nose
(NST3220 lab emission analyser). When samples without antioxidant were removed it
was possible to differentiate treatments containing antioxidant that had been inoculated
with micro-organism and those that had not. The e-noses were also able to
discriminate between sample times. Microbial populations and carbon dioxide levels
increased with incubation time. P. verrucosum and P. anomala populations were
greater in treatments without antioxidant whereas B. subtilis populations were greater
in 0.97 aw treatments containing antioxidant. CO2 production was greater in inoculated
treatments without an antioxidant except at 0.95 aw P. verrucosum produced greater
volumes in the presence of the antioxidant.
Using natural bread cross validation studies of 4 unknown contaminants (P. anomala,
P. verrucosum and B. subtilis and controls) was performed. This showed that using
initial populations of 103 spores/cells ml-1 the BH114 e-nose was able to differentiate
between all the unknown treatments after 48 h and the NST3220 lab emission analyser
after 72 h. CO2 production could be used to detect controls but it was not possible to
differentiate between the micro-organisms.
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Ramzi, Ammari. "DESIGN AND DEVELOPMENT OF A FALL DETECTION DEVICE WITH INFRARED RECEIVING CAPABILITIES". Wright State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=wright1314139225.
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Mishra, Alekha Kumar. "Node replica detection in wireless sensor networks". Thesis, 2014. http://ethesis.nitrkl.ac.in/6562/1/509CS103_thesis.pdf.
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In various applications of wireless sensor network, nodes are mostly deployed unattended and unsupervised in hostile environment. They are exposed to various kinds of security threat, and node replication attack is one among them. In this attack, an adversary captures a legitimate node from the network. Then, she creates a number of clones of the original node, and deploys them back into the network.
The adversary can gain control of various network activities and launch other insider attacks using these replicas. Most of the replica detection schemes reported in the literature are centralized and location dependent. Centralized schemes are vulnerable to a single point of failure. Forwarding location information incurs additional
overhead in location dependent schemes. Most replica detection schemes require exchange of membership information
among nodes. To reduce communication overhead we propose two techniques called transpose bit-pair coding (TBC), and sub-mat coding (SMC) for efficient exchange of group membership information among the nodes in wireless sensor network. These schemes are lossless and do not generate false positive. Next, we propose two replica detection schemes for static wireless sensor networks called zone-based node replica detection (ZBNRD), and node coloring based replica detection (NCBRD). In ZBNRD, nodes are divided into a number of zones. Each zone has a zone-leader, who is responsible for detecting replica. ZBNRD is compared with a few existing schemes such as LSM, P-MPC, SET and RED. It is observed that ZBNRD has higher detec-tion probability and lower communication cost. In NCBRD, each node is assigned with a color (value), which is unique within its neighborhood. A color conflict within the neighborhood of a node is detected as a replica. The performance of NCBRD is compared with LSM, SET, and RED. It is found that NCBRD has higher detection probability than the above schemes and lower communication overhead than LSM and RED. The techniques for replica detection in static wireless sensor networks cannot be applied to mobile wireless sensor networks (MWSN) because of nodes mobility. We propose a technique called energy based replica detection (EBRD) for MWSN. In EBRD, the residual energy of a node is used to detect replicas. Each node in the network monitors and is monitored by a set of nodes. Conflict in the timestamp-residual energy pair of a node is detected as replica. EBRD is compared with two existing schemes EDD, and MTLSD. It is found that EBRD has excellent detection probability in comparison to EDD and MTLSD, and the communication overhead of EBRD is higher than EDD and lower than MTLSD. Simulations were performed using Castalia simulator.
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Li, Wei, i 李威. "A Novel Node Movement Detection Scheme in Wireless Sensor Networks". Thesis, 2010. http://ndltd.ncl.edu.tw/handle/58345508926363398455.
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碩士國立中央大學
資訊工程研究所
98
The location information of sensors is significant in Wireless Sensor Network (WSN). However, after deploying and localizing the sensors, the location of sensors has to maintain constantly. Sensors may be moved from their original location by the depredation of the enemy or natural phenomena, and further, sensors return the inconsistent information with their incorrect location to sink or spread the incorrect location to the network resulted in arising problem with geographic protocol or applications. Consequently, in this paper, we proposed a new light-weight distributed scheme which is utilized the movement before and after with different topology to detect moved nodes. The simulation results show that our scheme can cost a bit of communication overhead and has high detection rate especially with large scale node movement.
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FARUK, SYED MD OMAR. "Variants of the Critical Node/Edge Detection Problem on a tree". Doctoral thesis, 2021. http://hdl.handle.net/11577/3407812.
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chen, stanley, i 陳嘉融. "The Malicious Node Detection and Identification Mechanisms for Wireless Sensor Networks". Thesis, 2006. http://ndltd.ncl.edu.tw/handle/63265720978978639169.
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碩士長庚大學
資訊管理研究所
94
Wireless Sensor Network (WSN) is a new developing type of wireless networks. Comparing with Wireless Local Area Network (WLAN), WSN has more restrictions on hardware specification of sensor node and deployment environment. The application of WSN has been growing in recent years. Many security protocols that designed for this particular network had been developed, simulated, verified and successfully implemented. However, the security challenge and difficulty that WSN has to faced will not be able to be solved completely in a few years. This study will begin with improving the whole of security of WSN to propose a suite of malicious node detection and identification mechanisms for WSN. These mechanisms include key pre-load mechanism, neighbor discovery mechanism, authentication key distribution mechanism and node authentication mechanism. The first three mechanisms may be regard as pre-processing to execute the last mechanism. After pre-processing, node in the network can easily detect whether malicious node in its communication range exists. If malicious node exists, it could be identified simultaneously.
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Yang, Shih-An, i 楊世安. "A Log-Only Node Fault Detection Method in Wireless Sensor Network". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/40470148701113594855.
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Hsieh, Kuan-Yu, i 謝冠宇. "Automatic Mediastinal Lymph Node Computer-aided Detection System in Chest CT". Thesis, 2013. http://ndltd.ncl.edu.tw/handle/28385362800471174861.
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碩士國立臺灣大學
資訊工程學研究所
101
Computed tomography (CT) plays an important role in the assessment of involvement of mediastinal lymph nodes for cancer staging. In the present clinical workflow, the radiologists need to examine all the slice of a CT scan manually for finding the enlarged lymph nodes which are possibly abnormal and this process is time-consuming and error-prone. Hence, in this study, a fully automatic system for detecting enlarged mediastinal lymph node in CT is proposed. First, two blob detectors are utilized for detecting the possible centers of lymph nodes following by a series of candidate reduction steps based on the intensity, size, and anatomical knowledge such as the extractions of mediastinum, airway tree and aortic arch. Second, the watershed transform is performed to segment the detected blobs for obtaining the lymph node candidate regions. Finally, two classifiers trained by the proposed feature sets including statistic, geometry, texture, and histogram in two different reduction phases are utilized for removing false positive detections. 25 contrast enhanced 3-D lung CT volumes are used to evaluate our proposed method. The proposed system achieved the sensitivities of 98.70%, 90.90%, 80.51%, 70.12%, and 61.00% with 22.04, 16.28, 10.56, 7.60, and 4.64 false positives per volume, respectively.
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Eleutério, Ricardo Jorge Neves. "Microwave imaging of the axilla to aid breast cancer diagnosis". Master's thesis, 2014. http://hdl.handle.net/10362/13658.
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Breast cancer is the most common type of cancer among women all over the world.
An important issue that is not commonly addressed in breast cancer imaging literature is the importance of imaging the underarm region—where up to 80% of breast cancer cells can metastasise to. The first axillary lymph nodes to receive drainage from the primary tumour in the breast are called Sentinel Node. If cancer cells are found in the Sentinel Node, there is an increased risk of metastatic breast cancer which makes this evaluation crucial to decide what follow-up exams and therapy to follow. However, non-invasive detection of cancer cells in the lymph nodes is often inconclusive, leading to the surgical
removal of too many nodes which causes adverse side-effects for patients.
Microwave Imaging is one of the most promising non-invasive imaging modalities
for breast cancer early screening and monitoring. This novel study tests the feasibility of imaging the axilla region by means of the simulation of an Ultra-Wideband Microwave Imaging system. Simulations of such system are completed in several 2D underarm models that mimic the axilla. Initial imaging results are obtained by means of processing the simulated backscattered signals by eliminating artefacts caused by the skin and beamforming
the processed signals in order to time-align all the signals recorded at each antenna.
In this dissertation several image formation algorithms are implemented and compared
by visual inspection of the resulting images and through a range of performance metrics, such as Signal-to-Clutter Ratio and FullWidth Half Maximum calculations.
The results in this study showed that Microwave Imaging is a promising technique
that might allow to identify the presence and location of metastasised cancer cells in
axillary lymph nodes, enabling the non-invasive evaluation of breast cancer staging.
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Luke, Geoffrey Patrick. "Functional and molecular photoacoustic imaging for the detection of lymph node metastasis". Thesis, 2013. http://hdl.handle.net/2152/28713.
Pełny tekst źródłaStreszczenie:
Accurate detection of the spread of cancer is critical for planning the best treatment strategy for a patient. Currently, an invasive sentinel lymph node biopsy is commonly used to detect metastases after a primary tumor is detected. This procedure results in patient morbidity, requires weeks of waiting, and is prone to sampling error. This dissertation presents new developments in an emerging biomedical imaging modality – photoacoustic imaging – and their application to improving the detection of metastases in the lymphatic system in a metastatic mouse model of squamous cell carcinoma of the oral cavity. Label-free spectroscopic photoacoustic imaging is demonstrated to detect hypoxia that results from the development of sub-millimeter cancer foci in the lymph node. In order to improve the sensitivity to micrometastases, molecularly-activated plasmonic nanosensers which are targeted to the epidermal growth factor receptor are introduced. The nanosensors are demonstrated to detect metastases consisting of only a few tens of cells. Improvements to spectroscopic photoacoustic imaging are then demonstrated by selecting imaging wavelengths based on the spectral properties of the optical absorbers. Finally, a new contrast agent – silica-coated gold nanoplates – are used to map the sentinel lymph node with high contrast. The final result is a set of tools that can be used to noninvasively detect micrometastases and improve molecular photoacoustic imaging.text
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Li, Zhijun. "Efficient Authentication, Node Clone Detection, and Secure Data Aggregation for Sensor Networks". Thesis, 2010. http://hdl.handle.net/10012/5739.
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Sensor networks are innovative wireless networks consisting of a large number of low-cost, resource-constrained sensor nodes that collect, process, and transmit data in a distributed and collaborative way. There are numerous applications for wireless sensor networks, and security is vital for many of them. However, sensor nodes suffer from many constraints, including low computation capability, small memory, limited energy resources, susceptibility to physical capture, and the lack of infrastructure, all of which impose formidable security challenges and call for innovative approaches. In this thesis, we present our research results on three important aspects of securing sensor networks: lightweight entity authentication, distributed node clone detection, and secure data aggregation.
As the technical core of our lightweight authentication proposals, a special type of circulant matrix named circulant-P2 matrix is introduced. We prove the linear independence of matrix vectors, present efficient algorithms on matrix operations, and explore other important properties. By combining circulant-P2 matrix with the learning parity with noise problem, we develop two one-way authentication protocols: the innovative LCMQ protocol, which is provably secure against all probabilistic polynomial-time attacks and provides remarkable performance on almost all metrics except one mild requirement for the verifier's computational capacity, and the HB$^C$ protocol, which utilizes the conventional HB-like authentication structure to preserve the bit-operation only computation requirement for both participants and consumes less key storage than previous HB-like protocols without sacrificing other performance. Moreover, two enhancement mechanisms are provided to protect the HB-like protocols from known attacks and to improve performance. For both protocols, practical parameters for different security levels are recommended. In addition, we build a framework to extend enhanced HB-like protocols to mutual authentication in a communication-efficient fashion.
Node clone attack, that is, the attempt by adversaries to add one or more nodes to the network by cloning captured nodes, imposes a severe threat to wireless sensor networks. To cope with it, we propose two distributed detection protocols with difference tradeoffs on network conditions and performance. The first one is based on distributed hash table, by which a fully decentralized, key-based caching and checking system is constructed to deterministically catch cloned nodes in general sensor networks. The protocol performance of efficient storage consumption and high security level is theoretically deducted through a probability model, and the resulting equations, with necessary adjustments for real application, are supported by the simulations. The other is the randomly directed exploration protocol, which presents notable communication performance and minimal storage consumption by an elegant probabilistic directed forwarding technique along with random initial direction and border determination. The extensive experimental results uphold the protocol design and show its efficiency on communication overhead and satisfactory detection probability.
Data aggregation is an inherent requirement for many sensor network applications, but designing secure mechanisms for data aggregation is very challenging because the aggregation nature that requires intermediate nodes to process and change messages, and the security objective to prevent malicious manipulation, conflict with each other to a great extent. To fulfill different challenges of secure data aggregation, we present two types of approaches. The first is to provide cryptographic integrity mechanisms for general data aggregation. Based on recent developments of homomorphic primitives, we propose three integrity schemes: a concrete homomorphic MAC construction, homomorphic hash plus aggregate MAC, and homomorphic hash with identity-based aggregate signature, which provide different tradeoffs on security assumption, communication payload, and computation cost. The other is a substantial data aggregation scheme that is suitable for a specific and popular class of aggregation applications, embedded with built-in security techniques that effectively defeat outside and inside attacks. Its foundation is a new data structure---secure Bloom filter, which combines HMAC with Bloom filter. The secure Bloom filter is naturally compatible with aggregation and has reliable security properties. We systematically analyze the scheme's performance and run extensive simulations on different network scenarios for evaluation. The simulation results demonstrate that the scheme presents good performance on security, communication cost, and balance.
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JAINT, BHAVNESH. "STUDY ON EMBEDDED SENSOR NETWORKS". Thesis, 2020. http://dspace.dtu.ac.in:8080/jspui/handle/repository/18112.
Pełny tekst źródłaStreszczenie:
Wireless sensor networks (WSNs) are widely used in a range of applications in the real w
orld. WSNs have demonstrated their applicability in the field of medical, military, and
broad range of surveillance applications and monitoring. This thesis focuses on three
major aspects related to WSN namely Energy efficiency, Security and real time
application of WSN. The contributions are
Energy efficiency in wireless sensor networks (WSN) is important as the sensor nodes
are operated with restricted battery life. The choice of modulation scheme and error
control code play a significant role in energy consumption of WSN. The analysis shows
that the energy consumption in WSN may be reduced by selecting optimal combination
of modulation scheme and error control codes. Our simulation results show that by
using BPSK modulation with Reed Solomon (RS) code saves 48 % energy in WSN at
an internode distance of 60 meters in comparison to other modulation schemes.
In general, wireless sensor networks comprises of large number of sensor nodes. The
communication among them depends on behaviour of each sensor node. Hence for
securing the network, it is necessary to identify malicious nodes. In this thesis we
present various techniques for malicious node detection and prediction.
Home automation is one of the applications of WSN. We present low cost, compact and
flexible ZigBee based home automation for remote control of house hold devices. This
system assures optimal usage of electricity, thereby reducing carbon footprint.
we propose an intelligent auto-dipping system that will be placed on the dashboard of a
vehicle. Once headlight of an oncoming vehicle is detected, the vehicle's high beam will
be automatically dipped, with a dipper flash to signal the approaching vehicle. The
v
system can be most successful when it is mounted in every vehicle. This system can
help to avoid accidents caused by the dazzling created by oncoming high beams. The
proposed system uses a USB web cam and Raspberry Pi for real time processing. The
validation of the system has been done using both simulation and actual hardware.
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Lin, Christy. "Unsupervised random walk node embeddings for network block structure representation". Thesis, 2021. https://hdl.handle.net/2144/43083.
Pełny tekst źródłaStreszczenie:
There has been an explosion of network data in the physical, chemical, biological, computational, and social sciences in the last few decades. Node embeddings, i.e., Euclidean-space representations of nodes in a network, make it possible to apply to network data, tools and algorithms from multivariate statistics and machine learning that were developed for Euclidean-space data. Random walk node embeddings are a class of recently developed node embedding techniques where the vector representations are learned by optimizing objective functions involving skip-bigram statistics computed from random walks on the network. They have been applied to many supervised learning problems such as link prediction and node classification and have demonstrated state-of-the-art performance. Yet, their properties remain poorly understood.
This dissertation studies random walk based node embeddings in an unsupervised setting within the context of capturing hidden block structure in the network, i.e., learning node representations that reflect their patterns of adjacencies to other nodes. This doctoral research (i) Develops VEC, a random walk based unsupervised node embedding algorithm, and a series of relaxations, and experimentally validates their performance for the community detection problem under the Stochastic Block Model (SBM). (ii) Characterizes the ergodic limits of the embedding objectives to create non-randomized versions. (iii) Analyzes the embeddings for expected SBM networks and establishes certain concentration properties of the limiting ergodic objective in the large network asymptotic regime.
Comprehensive experimental results on real world and SBM random networks are presented to illustrate and compare the distributional and block-structure properties of node embeddings generated by VEC and related algorithms. As a step towards theoretical understanding, it is proved that for the variants of VEC with ergodic limits and convex relaxations, the embedding Grammian of the expected network of a two-community SBM has rank at most 2. Further experiments reveal that these extensions yield embeddings whose distribution is Gaussian-like, centered at the node embeddings of the expected network within each community, and concentrate in the linear degree-scaling regime as the number of nodes increases.2023-09-24T00:00:00Z
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Lee, Yi-Chang, i 李宜昌. "A Distributed Protocol for the Detection of Node Replication Attacks in Wireless Sensor Networks". Thesis, 2009. http://ndltd.ncl.edu.tw/handle/13353818875293089256.
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碩士國立中正大學
資訊管理所暨醫療資訊管理所
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The applications for wireless sensor networks (WSNs) were originally motivated by military applications like battlefield surveillance. Today, wireless sensor networks are widely used in civilian application areas, such as home security monitoring, healthcare applications, traffic control. However, a novel attack, named node replication attacks are proved to be a harmful attack. The node replication attack is an attack that the adversary captures a node and replicates the node in a large number of clones. After that, the adversary will insert the replicated nodes in the network. At last the adversary will control the network gradually. A few solutions have recently been proposed. Nevertheless, these solutions are still unable to solve following issues- First, the large memory overhead and high computational complexity are unsuitable for WSNs. The communication cost and probabilities of detection are important issues as well. Further, a detection could be used in mobile sensor networks is more satisfactory. The contributions of this paper include (1) an efficient memory overhead and communication cost of detection protocol is suggested, (2) mobile sensor nodes are concerned in our protocol. It is possible for the sensor nodes to be mobile, not only stationary. (3) The security analysis and simulation experiments are also proposed. The results show that the probability of deletion is high, our protocol is useful.