Rozprawy doktorskie: „Protection and Control (WAMPAC)”

1

Neophytou, Andonis. "Computer security : data control and protection". Virtual Press, 1992. http://liblink.bsu.edu/uhtbin/catkey/834504.

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Computer security is a crucial area for any organization based on electronic devices that process data. The security of the devices themselves and the data they process are the backbone of the organization. Until today there have been no completely secure systems or procedures until and a lot of research is being done in this area. It impossible for a machine or a mechanical procedure to "guess" all possible events and lead to conclusive, cohesive and comprehensive secure systems, because of: 1) the human factor, and 2) acts of nature (fire, flood etc). However, proper managerial control can alleviate the extent of the damage caused by those factors.The purpose of this study is to examine the different frameworks of computer security. Emphasis is given to data/database security and the various kinds of attacks on the data. Controls over these attacks and preventative measures will be discussed, and high level language programs will demonstrate the protection issues. The Oracle, SOL query language will be used to demonstrate these controls and prevention measures. In addition the FORTRAN high level language will be used in conjunction with SOL (Only the FORTRAN and COBOL compilers are available for embedded SOL). The C language will be used to show attacks on password files and also as an encryption/decryption program.This study was based mainly on research. An investigation of literature spanning the past decade, was examined to produce the ideas and methods of prevention and control discussed in the study.
Department of Computer Science

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2

Wang, Sheng. "Control and protection of HVDC grids". Thesis, Cardiff University, 2016. http://orca.cf.ac.uk/99015/.

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The decarbonisation of Europe’s energy sector is a key driver for the development of integrated HVDC networks or DC grids. A multi-terminal HVDC grid will enable a more reliable power transfer from offshore wind farms and will facilitate the cross-border exchange of energy between different countries. However, the widespread deployment of DC grids is prevented by technical challenges, including the control and protection of DC grids. In order to close the gap, this thesis aims to contribute to three aspects (1): developing a control method for DC grids operation; (2): developing a method for optimising wind power delivery using DC grids; (3): developing a protection method for fast DC fault current interruption. The control of a DC grid demands the regulation of DC voltage and hence keeps the power into and out from the DC grid balanced. It is also important to keep the accuracy of regulating the converter DC current. In this thesis, the Autonomous Converter Control (ACC) is developed to meet this requirement. With this method, alternative droop control characteristics can be used for individual converters to share the responsibility of regulation of DC voltage while precisely controlling the converter DC current. The control algorithms of alterative droop characteristics are developed and interactions of different control characteristics are analysed. Furthermore, the potential risk of having multiple cross-over in control characteristics is uncovered. The method for designing droop characteristics is provided to avoid the multiple cross-over. The ACC is demonstrated on different simulation platforms including the PSCAD/EMTDC and a real-time hardware 4-terminal HVDC test rig. It is found that the proper use of alternative droop characteristics can achieve better current control performance. The adverse impact of having multiple cross-over in control characteristics is also studied using both simulation platforms. The effect of the control of both converters and DC power flow controllers (DC-PFCs) on DC power flow in steady state is also investigated. A method for re-dispatching control orders to optimise the wind power delivery is developed. Case studies are undertaken and it is found that both the DC line power loss and wind power curtailment can be reduced by redispatching the control orders of converters and DC-PFCs. The protection of a DC grid demands a very fast speed for fault current interruption. Conventional methods proposed for HVDC grid protection take delays of several milliseconds to discriminate a faulted circuit to healthy circuits and then allow the DC circuit breakers (DC-CBs) to open at the faulted circuits. The fault current will keep rising during Control and Protection of HVDC Grids iv the delayed time caused by fault discrimination. The Open Grid protection method is thus developed to interrupt fault current before fault discrimination. With this method, multiple DC-CBs open to interrupt the fault current based on local measurements of voltage (and current) and the DC-CBs on healthy circuits will reclose to achieve discrimination afterwards. This will reduce the delay for fault current interruption and hence the fault current can be interrupted with a much smaller magnitude. The developed Open Grid method is tested via simulation models developed in PSCAD/EMTDC. The results show that the Open Grid can detect very quickly and discriminate various faults under different fault conditions in a meshed HVDC grid.

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Jutla, Dawn N. "Multiview model for protection and access control". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ31529.pdf.

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4

Backman, A. (Aleksi). "A brief tour on control-flow protection". Bachelor's thesis, University of Oulu, 2019. http://jultika.oulu.fi/Record/nbnfioulu-201904241518.

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Abstract. The purpose of this work is to give an overview on the topic under discussion, control-flow protection. An effort is made for the result to be more accessible by providing sufficient background in beginning and related material in the end. Most of the work was done by searching, consuming and referring to relevant research material. Additionally a control-flow integrity feature of Clang compiler is tried out and the results reported. Control-flow protection can be attacked in various ways on multiple levels and this makes it challeging to implement a trustworthy protection. For this reason it is important to understand the topic both in depth and breadth.

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5

AL-Shareefi, Hussein. "Neutral network corrosion control by impressed cathodic protection". Thesis, Högskolan Dalarna, Maskinteknik, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:du-4258.

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Bishay-Girges, Nagui William. "Seismic protection of structures using passive control system". Thesis, University of Canterbury. Civil Engineering, 2004. http://hdl.handle.net/10092/7509.

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There is a relationship between inelastic deformation and energy dissipation in structures that are subjected to earthquake ground motions. Thus, if seismic energy dissipation can be achieved by means of a separate non-load bearing supplementary damping system, the load bearing structure can remain elastic with continuing serviceability following the design level earthquake. This research was carried out to investigate the advantages of using added damping in structures. The control system consists of passive friction dampers called ring spring dampers installed in the ground floor of the structure using a tendon to transmit the forces to the other parts of the structure. The ring springs dampers are friction devices consisting of inner and outer ring elements assembled to form a spring stack. External load applied to the spring produces sliding action across mating ring interfaces. The damping forces generated by the dampers and transferred in the supplemental system to the structure by the tendon and horizontal links oppose the internal loads. A four storey-two bay steel frame structure was used in the study. Experimental and analytical studies to investigate the effectiveness of a supplemental control system are presented. The model was subjected to a series of earthquake simulations on the shaking table in the Structural Laboratory of the Civil Engineering Department, at the University of Canterbury. The earthquake simulation tests have been performed on the structure both with and without the supplemental control system. The earthquake simulations were a series of gradually increasing intensity replications of two commonly used earthquake records. This thesis includes detailed description of the structural model, the supplemental control system, the ring springs dampers and the data obtained during the testing. Analyses were then carried out on a twelve storey framed structure to investigate the possible tendon arrangements and the size and type of dampers required to control the response of a real building. Guidelines for determining the appropriateness of including a supplemental damping system have been investigated. The main features of the supplemental control system adopted in this research are: • It is a passive control system with extreme reliability and having no dependence on external power sources to effect the control action. These power sources may not be available during a major earthquake. • Ring springs are steel friction devices capable of absorbing large amounts of input energy. No liquid leakage can occur and minimal maintenance is required for the ring spring dampers. • With a damper-tendon system, the distribution of the dampers throughout the structure is not so critical. Only one or two dampers are used to produce the damping forces needed, and forces are then transferred to the rest of the building by the tendon system. • It is a relatively inexpensive control system with a long useful life.

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Stedall, Bruce David. "The hierarchical control and protection of power systems". Thesis, University of Bath, 1994. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.760655.

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Li, Xinyao. "Enhanced control and protection for inverter dominated microgrids". Thesis, University of Strathclyde, 2014. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=23510.

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Implementation of distributed energy resources (DER) has the potential to lower the carbon oxygen emissions, reduce the power distribution losses and improve the overall system operation. Despite the numerous advantages brought by these small-scale DERs, effective protection and control of such systems are still unsolved challenges. The distribution system is increasingly being confronted with congestion and voltage problems, which limits further penetration of DERs. Numerous studies have been conducted to analyse these challenges and provide recommendations or guidance for protection and control in the past few years. There is also a lot of effort to develop an advanced regime for integration of large amounts of DERs, such as the "microgrid". Microgrids are designed to provide control and protection of a cluster of DERs, storage units and loads in a way that can coordinate with the conventional utility grid operation with little conflict. As flexible as it is, a microgrid is connec ted to the utility grid behaving as a controllable entity in normal operation, and can be disconnected from the grid to present itself as a power island in emergency, e.g. system black-out. Since most of the DERs are interfaced with inverters, this thesis is dedicated to provide in-depth investigation of protection and control within inverter dominated microgrids. The thesis provides two main valuable contributions. Firstly, an enhanced control scheme for a microgrid consisting of multi inverter interfaced generators (IIG) is developed and compared to the conventional droop based decentralized control. The proposed control scheme is particularly designed for systems with IIGs interconnected via relatively long cable lengths (several kilo metres). It also allows switchless mode transition between islanded operation and grid-connected operation, which reduces the transient voltage and current oscillations, and enhances the transient behaviour of the IIGs. Compared to the conventional droop based decentralized control, the proposed control scheme has better operational stability and is immune to different lengths and R/X ratios of connecting cables. The proposed control also brings better voltage regulation and has a larger power output capacity. Secondly, a new travelling wave based protection scheme is developed which involves modification of an application friendly signal processing technique - Mathematical Morphology. The impact of distance to fault, fault inception angle and fault impedance is analysed and quantified. The thesis proposes a systematic protection solution which is proved to be immune to the changes of system topology, modes of operation and load conditions.

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9

Thompson, Adam Craig. "The Future of Substations: Centralized Protection and Control". Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/73177.

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Modern power substations continue to use hardware that is dated and resistant to modernization. This document discusses the basics of substations, identifies their weaknesses, and suggests a method of improvement. This suggestion implements a centralized protection and control system to make the overall system more robust and flexible to the ever changing power system landscape.
Master of Science

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10

Unnikrishnan, Suraj. "Adaptive Envelope Protection Methods for Aircraft". Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/11478.

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Carefree handling refers to the ability of a pilot to operate an aircraft without the need to continuously monitor aircraft operating limits. At the heart of all carefree handling or maneuvering systems, also referred to as envelope protection systems, are algorithms and methods for predicting future limit violations. Recently, envelope protection methods that have gained more acceptance, translate limit proximity information to its equivalent in the control channel. Envelope protection algorithms either use very small prediction horizon or are static methods with no capability to adapt to changes in system configurations. Adaptive approaches maximizing prediction horizon such as dynamic trim, are only applicable to steady-state-response critical limit parameters. In this thesis, a new adaptive envelope protection method is developed that is applicable to steady-state and transient response critical limit parameters. The approach is based upon devising the most aggressive optimal control profile to the limit boundary and using it to compute control limits. Pilot-in-the-loop evaluations of the proposed approach are conducted at the Georgia Tech Carefree Maneuver lab for transient longitudinal hub moment limit protection. Carefree maneuvering is the dual of carefree handling in the realm of autonomous Uninhabited Aerial Vehicles (UAVs). Designing a flight control system to fully and effectively utilize the operational flight envelope is very difficult. With the increasing role and demands for extreme maneuverability there is a need for developing envelope protection methods for autonomous UAVs. In this thesis, a full-authority automatic envelope protection method is proposed for limit protection in UAVs. The approach uses adaptive estimate of limit parameter dynamics and finite-time horizon predictions to detect impending limit boundary violations. Limit violations are prevented by treating the limit boundary as an obstacle and by correcting nominal control/command inputs to track a limit parameter safe-response profile near the limit boundary. The method is evaluated using software-in-the-loop and flight evaluations on the Georgia Tech unmanned rotorcraft platform- GTMax. The thesis also develops and evaluates an extension for calculating control margins based on restricting limit parameter response aggressiveness near the limit boundary.

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11

Salomonsson, Daniel. "Modeling, Control and Protection of Low-Voltage DC Microgrids". Doctoral thesis, Stockholm : Elektriska energisystem, Electric Power Systems, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4666.

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Sweeney, Latanya. "Computational disclosure control : a primer on data privacy protection". Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/8589.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2001.
Includes bibliographical references (leaves 213-216) and index.
Today's globally networked society places great demand on the dissemination and sharing of person specific data for many new and exciting uses. When these data are linked together, they provide an electronic shadow of a person or organization that is as identifying and personal as a fingerprint even when the information contains no explicit identifiers, such as name and phone number. Other distinctive data, such as birth date and ZIP code, often combine uniquely and can be linked to publicly available information to re-identify individuals. Producing anonymous data that remains specific enough to be useful is often a very difficult task and practice today tends to either incorrectly believe confidentiality is maintained when it is not or produces data that are practically useless. The goal of the work presented in this book is to explore computational techniques for releasing useful information in such a way that the identity of any individual or entity contained in data cannot be recognized while the data remain practically useful. I begin by demonstrating ways to learn information about entities from publicly available information. I then provide a formal framework for reasoning about disclosure control and the ability to infer the identities of entities contained within the data. I formally define and present null-map, k-map and wrong-map as models of protection. Each model provides protection by ensuring that released information maps to no, k or incorrect entities, respectively. The book ends by examining four computational systems that attempt to maintain privacy while releasing electronic information. These systems are: (1) my Scrub System, which locates personally-identifying information in letters between doctors and notes written by clinicians; (2) my Datafly II System, which generalizes and suppresses values in field-structured data sets; (3) Statistics Netherlands' pt-Argus System, which is becoming a European standard for producing public-use data; and, (4) my k-Similar algorithm, which finds optimal solutions such that data are minimally distorted while still providing adequate protection. By introducing anonymity and quality metrics, I show that Datafly II can overprotect data, Scrub and p-Argus can fail to provide adequate protection, but k-similar finds optimal results.
by Latanya Sweeney.
Ph.D.

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13

bin, Mohd Ariff Mohd. "Adaptive protection and control for wide-area blackout prevention". Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/24488.

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Technical analyses of several recent power blackouts revealed that a group of generators going out-of-step with the rest of the power system is often a precursor of a complete system collapse. Out-of-step protection is designed to assess the stability of the evolving swing after a disturbance and take control action accordingly. However, the settings of out-of-step relays are found to be unsatisfactory due to the fact that the electromechanical swings that occurred during relay commissioning are different in practice. These concerns motivated the development of a novel approach to recalculate the out-of-step protection settings to suit the prevalent operating condition. With phasor measurement unit (PMU) technology, it is possible to adjust the setting of out-of-step relay in real-time. The setting of out-of-step relay is primarily determined by three dynamic parameters: direct axis transient reactance, quadrature axis speed voltage and generator inertia. In a complex power network, these parameters are the dynamic parameters of an equivalent model of a coherent group of generators. Hence, it is essential to identify the coherent group of generators and estimate the dynamic model parameters of each generator in the system first in order to form the dynamic model equivalent in the system. The work presented in this thesis develops a measurement-based technique to identify the coherent areas of power system network by analysing the measured data obtained from the system. The method is based on multivariate analysis of the signals, using independent component analysis (ICA). Also, a technique for estimating the dynamic model parameters of the generators in the system has been developed. The dynamic model parameters of synchronous generators are estimated by processing the PMU measurements using unscented Kalman filter (UKF).

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Scordino, Monica. "Food control: quality assurance and protection against adulteration techniques". Doctoral thesis, Università di Catania, 2012. http://hdl.handle.net/10761/1154.

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The quality assessment of agro-food typical of the member states is one of the primary objectives of economic policy and agriculture in the EU. The check on overall quality, according to the specifications and typical products, however, is subject to information gaps that are subject to continuous development of methods of analysis. This has resulted in multiple attempts at adulteration and counterfeiting, which allowed the use of poor quality products and / or different geographical origin and / or non-typical tree species, with consequences for consumers, local producers on "honest" on the preservation of local ecotypes. In this context, this research is a meaningful goal to promote local quality products and protection from the illegal adulteration techniques, providing analytical parameter control from the local reference for the consumer protection. This PhD research was conducted almost entirely in agreement with the laboratory of Catania of Central Inspectorate Department of Protection and Prevention of Fraud quality of food products (ICQRF), considering its growing interest in organic production controls, as well as typical products of denomination of protected and controlled origin, determined by the new supervisory functions assigned to it by the rules mentioned above. In this context, this research has the meaningful objective of health-promoting typical quality products and protection against illegal adulteration techniques, providing analytical control parameter for the protection of the consumer. The work has developed on several fronts, deepening different research topics as individual cases of study: - Characterization of Sicilian peach cultivars with different ripening stages. - Evaluation of bioactive compounds of chinotto extract used in the preparation of commercial soft drinks. - Development of an analytical method for evaluating the adulteration of saffron with the less valuable spices. - Detection of illegal use of short-chain aliphatic amines in the wax coating for fruit for consumption. - Characterization of dansyl-biogenic amines by HPLC-UV-ESI/MS. The analytical results of this PhD thesis have been the subject of communications from different conferences have produced many scientific papers and are currently applied at the ICQRF Laboratory of Catania in food official controls.

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Rosky, Jeffrey W. "Examining the relationship between risk, protection, self-control and resilience". Pullman, Wash. : Washington State University, 2010. http://www.dissertations.wsu.edu/Dissertations/Spring2010/j_rosky_121409.pdf.

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Kumbale, Murali. "Bulk transmission system reliability analysis of protection and control groups". Thesis, Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/13840.

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Oleiwi, H. M. "Using cathodic protection to control corrosion of reinforced concrete structures". Thesis, University of Salford, 2018. http://usir.salford.ac.uk/47895/.

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Cathodic protection (CP) has been increasingly used on reinforced concrete structures to protect steel reinforcement from corrosion. However, due to the complexity of environmental conditions, the specifications in national and international standards are still open to discussion in engineering practices for their accurate suitability. To some extent, the design aspects are still based on practical experience. It implies a great deal of estimations and assumptions. The research conducted in the thesis aims to address some of these challenges. To obtain reliable experimental results, the present study at first investigated the influence of experimental methods on the measurement of concrete electrical resistivity. It studied the effect of alternative current (AC) frequency, electrode materials and electrode configuration. Based on the results, an optimised method was decided for all the series of the experimental tests in this study. The CP study consists of two major works. The first one was to investigate the chloride contaminated concrete exposed to atmospheric condition. Impressed constant current method was adopted for the operation of CP. A series of electrical and electrochemical measurements were conducted for concrete resistivity, corrosion potential, corrosion rate, degree of polarization, instant-off potential and four-hour potential decay. An evaluation on the current adopted criterion in standards has been carried out on the experimental results. The second work was to investigate the corrosion of rebar in concrete specimens submerged (fully and partially) in salty water. For such more corrosive environment, a comparison between the impressed CP operation using constant current and that using constant potential has been conducted. The experiments evaluated the effects of the two major environmental factors, i.e. water and chloride contents, on reinforced concrete durability. The work provided a deep understanding on the electrochemical behaviour of the reinforced concrete system and effectiveness of CP implementation under severe conditions. The research work has an important contribution to fundamental science of corrosion and reinforced concrete deterioration, and the technology and practical application of CP for reinforced concrete structures. The main results of this work indicate the important influence of the frequency and electrode configuration on the electrical resistance measurement. For the reliability of electrical resistivity measurement, a high frequency of 10,000 Hz and an internal carbon fibre electrode method are recommended. Regarding the CP for the chloride contaminated reinforced concrete exposed to the atmosphere, it is suggested that adopting an instant-off potential of -500 mV with respect to Ag/AgCl/0.5KCl reference electrode can provide sufficient protection for the reinforced concrete of up to 0.59 % total chloride by weight of concrete, or concrete resistivity is greater than 6.7 kΩ.cm. Furthermore, it was found that the 100 mV depolarization criterion for the evaluation of CP performance gives an overestimated protection. A depolarization of 50 mV is therefore proposed. In terms of the submerged specimens, the results showed that the water content and chloride content should be explicitly related to the corrosion state rather than through a single parameter of the concrete resistivity for the complicated situations because the water content will affect the oxygen transportation in concrete, and the oxygen availability at the rebar surface will play an important role in the corrosion process, and this is unassessable by concrete resistivity. Moreover, 4 or 24 hours for the 100 mV depolarisation criterion in standards is not applicable for CP assessment where concrete structures are fully submerged due to the low availability of oxygen. On the other hand, the depolarization criterion can be used if the specimens are partially submerged, but different parameters affect the depolarization value such as the magnitude of the applied protection current or potential, chloride concentration, oxygen availability and time of depolarization.

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Huang, Chiung-Yi. "The application of phasor measurements for adaptive protection and control". Thesis, Virginia Tech, 1991. http://hdl.handle.net/10919/42131.

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This thesis describes an adaptive protection scheme that performs the collection of the voltage and current phasors during post-fault period, tracking the power swing phenomena, identifying the onset of instability, and then issuing a stabilizing command. In this work, the protection system is to maintain the reliability! ensure the secure operation, and prevent total collapse of the power system. The work is based upon methods of clustering for meter placement in a bulk power system, and selecting the pilot points for installing the phasor measurement units (PMU) to measure the bus voltage phasors and associated branch current phasors. According to the network law, fast calculation of state estimation can be made from these measurements. Because the on-line assessment of transient stability has to provide a quick and approximate result, the direct method which determines stability without explicit integration techniques is applicable in this study. The results of the system stability prediction in real-time by digital computer simulation under stable and unstable operating conditions are presented.
Master of Science

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19

Miller, Kathryn M. "A test of protection-motivation theory for promoting injury control". Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-07112009-040238/.

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Breedlove, Joseph Toth. "Environmental Protection Agency enforcement and facility pollution control device selection /". Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3008288.

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Jeram, Geoffrey James Joseph. "Open Platform for Limit Protection with Carefree Maneuver Applications". Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4933.

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This Open Platform for Limit Protection guides the open design of maneuver limit protection systems in general, and manned, rotorcraft, aerospace applications in particular. The platform uses three stages of limit protection modules: limit cue creation, limit cue arbitration, and control system interface. A common set of limit cue modules provides commands that can include constraints, alerts, transfer functions, and friction. An arbitration module selects the best limit protection cues and distributes them to the most appropriate control path interface. This platform adopts a holistic approach to limit protection whereby it considers all potential interface points, including the pilots visual, aural, and tactile displays; and automatic command restraint shaping for autonomous limit protection. For each functional module, this thesis guides the control system designer through the design choices and information interfaces among the modules. Limit cue module design choices include type of prediction, prediction mechanism, method of critical control calculation, and type of limit cue. Special consideration is given to the nature of the limit, particularly the level of knowledge about it, and the ramifications for limit protection design, especially with respect to intelligent control methods such as fuzzy inference systems and neural networks. The Open Platform for Limit Protection reduces the effort required for initial limit protection design by defining a practical structure that still allows considerable design freedom. The platform reduces lifecycle effort through its open engineering systems approach of decoupled, modular design and standardized information interfaces. Using the Open Platform for Limit Protection, a carefree maneuver system is designed that addresses: main rotor blade stall as a steady-state limit; hub moment as a transient structural limit; and pilot induced oscillation as a controllability limit. The limit cue modules in this system make use of static neural networks, adaptive neural networks, and fuzzy inference systems to predict these limits. Visual (heads up display) and tactile (force-feedback) limit cues are employed. The carefree maneuver system is demonstrated in manned simulation using a General Helicopter (GENHEL) math model of the UH-60 Black Hawk, a projected, 53 degree field of view for the pilot, and a two-axis, active sidestick for cyclic control.

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Van, Egteren Henry John Bernard. "The control of non-localized externalities with asymmetric information". Thesis, University of British Columbia, 1989. http://hdl.handle.net/2429/31372.

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This thesis presents a model in which there is a single agent and two principals. The agent is a monopoly firm, while the two principals are regulators who may cooperate when selecting their optimal policies or act as rivals. The specific regulatory problem in which all are involved is the control of acid rain. An environmental regulator chooses a design standard and a public utility regulator chooses a two-part pricing scheme. These choices are made within an environment of limited and asymmetric information. Specifically, we assume the firm knows more about its fixed abatement costs than does either regulator. The firm is able to act strategically when revealing this information. Within the context of this regulation problem, we characterize the equilibrium solutions when the regulators cooperate and when they act as rivals. The non-cooperative game endows the environmental regulator with the status of leader. We also give characterizations for two different kinds of rivalry, extreme rivalry and mild rivalry. In addition, this thesis presents some different results on the bunching properties of these models.
Arts, Faculty of
Vancouver School of Economics
Graduate

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Hunt, Richard K. "Hidden Failure in Protective Relays: Supervision and Control". Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/36571.

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This thesis performs simulations of a relay supervisory system (RSS) that works passively in conjunction with the existing protective relaying system at a substation. During normal system operating conditions, the RSS supervises the relay system to prevent trips due to hidden failures. During wide area network disturbances, it adapts the relay system to increase security of the power system. The RSS works passively in the sense that it waits for events to occur in the existing relay system before taking any action. The simulation performed includes a model of the RSS, along with simplified models of existing relays, performed in Matlab. A power system model in EMTP provides inputs to the RSS model. Multiple faults are applied to the EMTP model, and the RSS is tested under each fault condition, and with a variety of relay hidden failures. For all tests performed, the simulation of the RSS successfully prevents relay hidden failure from removing circuit elements inadvertently, while allowing correct relay operations to remove circuit elements.
Master of Science

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24

Zhang, Pinjia. "Active thermal protection for induction motors fed by motor control devices". Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34811.

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Induction motors are widely used in industrial processes. The malfunction of a motor may not only lead to high repair costs, but also cause immense financial losses due to unexpected process downtime. Since thermal overload is one of the major root causes of stator winding insulation failure, an accurate and reliable monitoring of the stator winding temperature is crucial to increase the mean time to catastrophic motor breakdown, and to reduce the extraordinary financial losses due to unexpected process downtime. To provide a reliable thermal protection for induction motors fed by motor control devices, a dc signal-injection method is proposed for in-service induction motors fed by soft-starter and variable-frequency drives. The stator winding temperature can be monitored based on the estimated stator winding resistance using the dc model of induction motors. In addition, a cooling capability monitoring technique is proposed to monitor the cooling capability of induction motors and to warn the user for proactive inspection and maintenance in the case of cooling capability deterioration. The proposed cooling capability monitoring technique, combined with the proposed stator winding temperature monitoring technique, can provide a complete thermal protection for in-service induction motors fed by motor control devices. Aside from online thermal protection during a motor's normal operation, the thermal protection of de-energized motors is also essential to prolong a motor's lifetime. Moisture condensation is one of the major causes to motor degradation especially in high-humidity environments. To prevent moisture condensation, a non-intrusive motor heating technique is proposed by injecting currents into the motor stator winding using soft-starters. A motor's temperature can be kept above the ambient temperature due to the heat dissipation, so that the moisture condensation can be avoided. To sum up, active stator winding temperature estimation techniques for induction motors under both operating and de-energization conditions are proposed in this dissertation for both thermal protection and optimizing the operation of a motor system. The importance of these proposed techniques lies in their non-intrusive nature: only the existing hardware in a motor control device is required for implementation; a motor's normal operation is not interrupted.

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Voskuijl, Mark. "Rotorcraft flight control for improved handling, loads reduction and envelope protection". Thesis, University of Liverpool, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.485872.

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The advent of fly-by-wire control systems has made it possible to design elaborate automatic flight control systems that can provide a whole range of functions from basic stabilisation to advanced envelope protection systems and autopilots. The research presented in this thesis is focused on the design of novel control systems for rotorcraft with the aim to improve handling' qualities, provide structural load alleviation and to provide envelope protection. The application of the control theory used for the design is considered to be novel. Methods used include nonlinear control and H:o control. Seven control laws are designed for three different rotorcraft types. They are designed first of all for the Bell 412 Advanced Systems Research Aircraft, a fly-by-wire research helicopter of the National Research Council in Canada. This aircraft is equipped with a full-authority simplex control architecture with single nonredundant set of fly-by-wire actuators, sensors and flight control computer and software. Inherent to the design philosophy of the Advanced Systems Research Aircraft's simplex architecture is a reliance on automated safety monitoring systems and a safety pilot to guard against system failure or operational flight envelope exceedance. Novel control laws can actually be flight tested on this aircraft. A highfidelity nonlinear simulation model of this aircraft was developed in the project for control law design. The other two aircraft for which control laws are designed are the XV-I5 tilt-rotor and the FLIGHTLAB Generic Rotorcraft, a nonlinear simulation model representative of the UH-60 Black Hawk. Nonlinear simulation models of the latter two were available at the start of the project. One of the key outcomes presented in this thesis is the design and flight test of a nonlinear control law for the Bell 412. The attitude quickness could be specified within a nonlinear element. High bandwidths were achieved in flight, which correlated very closely to the simulationbased predictions. Also, describing function analysis was successfully applied to analyse the stability of the control law. Other important results are the presentation of a new design method for structural load alleviation control laws, in combination with a newly proposed structural load severity scale that can be used for the analysis of these types of control laws. Flight envelope protection was investigated as well. A heave axis control law providing mast torque envelope protection was designed for the Bell 412. The design method used was the Boo loop shaping procedure in combination with a nonlinear outer loop. Stability problems with the inner loop were encountered during the first flight test with this control law. The control law was therefore automatically disengaged by the safety systems of the Advanced Systems. Research Aircraft. Piloted simulation suggested that the structure of the control law is useful, provided the inner loop tracks torque. Finally, a complete flight control system was built with additional outer loops in order to take on a challenging problem: the automatic landing of a helicopter on a ship using ''t-theory'. The variable 't is commonly used in optical flow theory ofvisual perception. It is essentially the time to contact given a certain speed and distance. Theory suggests that pilots use this variable for manual flight control. The height rate reference signal generated by the automatic landing system was based on the variable 't during the final landing phase (from hover above the deck until touch down). A successful automatic .landing was simulated in zero wind conditions. The height control in the final phase of the automatic landing seemed natural, as if a human pilot performed it. The 't-based height control loop is essentially a proportional controller with a time dependent proportional gain. This application of't-theory in control is considered to be novel. Keywords: Flight control, Flight test, Hoo control, Nonlinear control, Rotorcraft Modelling and Simulation, Envelope protection, Structural Load Alleviation, Handling Qualities, Shipboard landing, Bell 412 ASRA, FGR, XV-15.

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PALHARES, DIOGO FARIA DOMINGUES. "LEGAL PROTECTION TO MINORITY SHAREHOLDERS AND THE SIZE OF CONTROL BLOCKS". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2008. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=12281@1.

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Qual é o efeito de um mercado de controle corporativo mais ativo sobre a estrutura de propriedade das firmas? Nós mostramos que, em economias com severas imperfeições no mercado de crédito, empreendedores ilíquidos elevam seus blocos de controle para que, numa disputa pelo controle, os limitados recursos que dispõem sejam suficientes para derrotar as tentativas de aquisições. À medida que a restrição financeira do empreendedor se afrouxa, a ameaça de aquisições perde força e o tamanho do bloco de controle se reduz. O modelo prevê que o tamanho dos blocos de controle em carveouts deve ser menos sensível ao nível de atividade do mercado de controle do que aquele em aberturas de capital de firmas independentes.
What is the effect of greater activity in the market for corporate control on firms´ ownership structure ? We show that, in economies with malfunctioning credit markets, illiquid entrepreneurs increase their blocks´ size, so that in a context for control, their limited resources suffices to defeat takeover attempts. As entrepreneur´s financial restriction is softened, the threat of takeovers dwindles and the size of the controlling blocks falls. The model predicts that sales of shares in carve-outs should be less sensitive to the level of activity in the market for control than thos in IPOs of independent firms.

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Minh, Hyunsik Eugene. "Communication options for protection and control device in Smart Grid applications". Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82401.

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Thesis (M.B.A.)--Massachusetts Institute of Technology, Sloan School of Management; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science; in conjunction with the Leaders for Global Operations Program at MIT, 2013.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 74-75).
Increasing use of electricity, interest in renewable energy sources, and need for a more reliable power grid system are some of the many drivers for the concept of the Smart Grid technology. In order to achieve these goals, one of the critical elements is communication between systems or between the system and human beings. With the decreasing cost of various communication technologies, especially wireless devices and utilities, researchers are increasingly interested in implementing complex two-way communication infrastructures to enhance the quality of the grid. The protection and control relay at the distribution level is one of the key component in enhancing the efficiency, security and reliability of power grid. At present, it may be premature to apply wireless devices to power electronics and to distribution automation, especially for protection and control relays in the distribution level. While fiber technology is still very attractive for protection and control applications in general, wireless technology can bring improvements in user experience applications in the future. The ABB medium voltage group needs to overcome challenges that arise from conservative industry structure, increasing complexity and cost of the product, and needs for higher reliability and security. However, with collaborative efforts among different product groups, the medium voltage group will successfully develop next generation distribution feeder relay.
by Hyunsik Eugene Minh.
S.M.
M.B.A.

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Kotze, Charl. "Biological control of the grapevine trunk disease pathogens : pruning wound protection". Thesis, Stellenbosch : Stellenbosch University, 2008. http://hdl.handle.net/10019.1/2117.

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Thesis (MScAgric (Plant Pathology))--Stellenbosch University, 2008.
In recent years, several studies have conclusively shown that numerous pathogens, including several species in the Botryosphaeriaceae, Phomopsis, Phaeoacremonium, as well as Phaeomoniella chlamydospora and Eutypa lata, contribute to premature decline and dieback of grapevines. These pathogens have the ability to infect grapevines through pruning wounds, which leads to a wide range of symptoms developing that includes stunted growth, cankers and several types of wood necrosis. Pruning wounds stay susceptible for 2 to 16 weeks after pruning and sustained levels of pruning wound protection is therefore required. The aims of this study were to (i) evaluate the ability of several biological agents to protect pruning wounds, (ii) characterise unknown Trichoderma strains and identify their modes of action and (iii) determine the optimal time of season for biological agent application. Several biological agents were initially evaluated in a laboratory for their antagonism against trunk disease pathogens. The best performing control agents were tested in a field trial conducted on Merlot and Chenin blanc vines in the Stellenbosch region. Spurs were pruned to three buds and the fresh pruning wounds were treated with benomyl as a control treatment, Trichoderma-based commercial products, Vinevax® and Eco77®, Bacillus subtilis, and Trichoderma isolates, USPP-T1 and -T2. Seven days after treatment the pruning wounds were spray inoculated with spore suspensions of four Botryosphaeriaceae spp. (Neofusicoccum australe, N. parvum, Diplodia seriata and Lasiodiplodia theobromae), Eutypa lata, Phaeomoniella chlamydospora and Phomopsis viticola. After a period of 8 months the treatments were evaluated by isolations onto potato dextrose agar. Trichodermabased products and isolates in most cases showed equal or better efficacy than benomyl, especially USPP-T1 and -T2. Moreover, these isolates demonstrated a very good ability to colonise the wound tissue. The two uncharacterised Trichoderma isolates (USPP-T1 and USPP-T2), which were shown to be highly antagonistic toward the grapevine trunk disease pathogens, were identified by means of DNA comparison, and their ability to inhibit the mycelium growth of the trunk disease pathogens by means of volatile and non-volatile metabolite production studied. The two gene areas that were used include the internal transcribed spacers (ITS 1 and 2) and the 5.8S ribosomal RNA gene and the translation elongation factor 1 (EF). The ITS and EF sequences were aligned to published Trichoderma sequences and the percentage similarity determined and the two Trichoderma isolates were identified as Trichoderma atroviride. The volatile production of T. atroviride isolates was determined by placing an inverted Petri dish with Trichoderma on top of a dish with a pathogen isolate and then sealed with parafilm. Trichoderma isolates were grown for 2 days on PDA where after they were inverted over PDA plates containing mycelial plugs. The inhibition ranged from 23.6% for L. theobromae to 72.4% for P. viticola. Inhibition by non-volatile products was less than for the volatile inhibition. Inhibition ranged from 7.5% for N. parvum to 20.6% for L. theobromae. In the non-volatile inhibition USPP-T1 caused significantly more mycelial inhibition than USPP-T2. The timing of pruning wound treatment and subsequent penetration and colonisation of the wound site was also determined. One-year-old canes of the Shiraz and Chenin blanc cultivars were grown in a hydroponic system, pruned and spray treated with a spore suspension of Trichoderma atroviride (USPP-T1) as well as a fluorescent pigment. On intervals 1, 3, 5 and 7 days after treatment, the distal nodes were removed and dissected longitudinally. From the one half, isolations were made at various distances from the pruning surface, while the other half was observed under ultra-violet light to determine the depth of fluorescent pigment penetration. Shortly after spray-inoculation of a fresh pruning wound, Trichoderma was isolated only from the wound surface and shallow depths into the wound (2 to 5 mm). One week after inoculation, Trichoderma was isolated at 10 mm depths, and after 2 weeks, at 15 mm depths. Fluorescent pigment particles were observed to a mean depth of 6 mm, which suggests that initial isolation of Trichoderma at these depths was resultant of the physical deposition of conidia deeper into the pruning wound tissue, whereas the isolation of Trichoderma from deeper depths might be attributed to colonisation of grapevine tissue. In a vineyard trial, fluorescent pigment was spray-applied to pruning wounds of Shiraz and Chenin blanc grapevines during July and September at intervals 0, 1, 3, 7 and 14 days after pruning. One week after treatment, the distal nodes were removed and dissected longitudinally. Each half was observed under UV light and the pigment penetration measured. For Chenin blanc and Shiraz, July pruning wounds showed significant deeper penetration of the pigment than pruning wounds treated in September. Moreover, pruning wounds made in September showed pigment particles in longitudinal sections up to 1 day after pruning, whereas wounds made in July showed pigment particles up to 3 days in the xylem vessels. These findings suggest that the best time for application of a biological control agent should be within the first 24 hours after pruning.

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Adewole, Adeyemi Charles. "Voltage stability assessment and wide area protection/control using synchrophasor measurements". Thesis, Cape Peninsula University of Technology, 2016. http://hdl.handle.net/20.500.11838/2380.

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Thesis (DTech (Electrical Engineering))--Cape Peninsula University of Technology, 2016.
Electric power systems are being operated closer to their designed stability limits due to the constraints caused by the continuous increase in system loading, and the lack of new power stations and transmission network infrastructure to support this increase in system loading. This coupled with the practice of long distance bulk power transmission and cascading contingencies, makes system instability and consequently blackouts inevitable. In such scenarios, system instabilities like voltage instability becomes a serious threat to the secure operation of the power system, and voltage collapse (system-wide blackouts) are prone to occur. This is often compounded by the unavailability of real-time system measurements for situational awareness from the existing Supervisory Control and Data Acquisition (SCADA)/Energy Management System (EMS) platforms which are usually based on unsynchronized SCADA measurements with a slow reporting rate of 1 measurement every 2-10 seconds. This Doctoral thesis proposes non-iterative algorithms and methods of solution based on the IEEE C37.118 synchrophasor measurements from Phasor Measurement Units (PMUs) with a high reporting rate of up to 200 measurements every second (200 fps) for voltage stability assessment and automated wide area Centralised Protection/Control (CPC) against catastrophic voltage instabilities/blackouts in power systems. Extended formulations are proposed for the Optimal Placement of PMUs (OPP) in power systems with respect to voltage stability assessment. The impact of zero injection buses, critical buses, and PMU redundancy is considered in the formulation of the OPP problem solution. The extended formulations made use of Binary Integer programming (BIP) and Modal Participation Factors (MPFs) derived from the eigenvalues of the power flow Jacobian.

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Barik, Tapas Kumar. "Modern Adaptive Protection and Control Techniques for Enhancing Distribution Grid Resiliency". Diss., Virginia Tech, 2021. http://hdl.handle.net/10919/103644.

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Power distribution systems have underwent a lot of significant changes in the last two decades. Wide-scale integration of Distributed Energy Resources (DERs) have made the distribution grid more resilient to abnormal conditions and severe weather induced outages. These DERs enhance the reliability of the system to bounce back from an abnormal situation rather quickly. However, the conventional notion of a radial system with unidirectional power flow does not hold true due to the addition of these DERs. Bidirectional power flow has challenged the conventional protection schemes in place. The most notable effects on the protection schemes can be seen in the field of islanding or Loss of Mains(LOM) detection and general fault identification and isolation. Adaptive protection schemes are needed to properly resolve these issues. Although, previous works in this field have dealt with this situation, a more comprehensive approach needs to be taken considering multiple topologies for developing adaptive protection schemes. The most common protective devices widely deployed in the distribution system such as overcurrent relays, reverse power relays at Point of Common Coupling(PCC), fuses, reclosers and feeder breakers need to studied in implementing these schemes. The work presented in this dissertation deals with simulation based and analytical approaches to tackle the issues of islanding and adaptive protection schemes. First we propose a multiprinciple passive islanding detection technique which relies on local PCC measurements, thus reducing the need of additional infrastructure and still ensuring limited Non Detection Zone (NDZ). The next step to islanding detection would be to sustain a islanded distribution system in order to reduce the restoration time and still supply power to critical loads. Such an approach to maintain generator load balance upon islanding detection is studied next by appropriate shedding of non-critical and low priority critical loads based upon voltage sensitivity analysis. Thereafter, adaptive protection schemes considering limited communication dependency is studied with properly assigning relay settings in directional overcurrent relays (DOCRs), which are one of the most widely deployed protective devices in distribution systems by catering to multiple topologies and contingencies. A simulation based technique is discussed first and then an analytical approach to solve the conventional optimal relay coordination problem using Mixed Integer Linear Programming (MILP) with the usage of multiple setting groups is studied. All these approaches make the distribution more robust and resilient to system faults and ensure proper fault identification and isolation, ensuring overall safety of system.
Doctor of Philosophy
With widespread integration of inverter-based distributed energy resources (DERs) in the distribution grid, the conventional protection and control schemes no longer hold valid. The necessity of an adaptive protection scheme increases as the DER penetration in the system increases. Apart from this, changes in system topology and variability in DER generation, also change the fault current availability in the system in real-time. Hence, the protection schemes should be able to adapt to these variations and modify their settings for proper selectivity and sensitivity towards faults in the system, especially in systems with high penetration of DERs. These protection schemes need to be modified in order to properly identify and isolate faults in the network as well as correctly identify Loss of Mains (LOM) or islanding phenomenon. Special attention is needed to plan the next course of action after the islanding occurrence. Additionally, the protective devices in distribution system should be utilized to their maximum capability to create an adaptive and smart protection system. This document elaborately explains the research work pertaining to these areas.

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Hessler, Sven. "Protection of data networks by enforcing congestion control on UDP flows /". Berlin : dissertation.de, 2008. http://d-nb.info/992351677/04.

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ROSA, Marco. "Data-at-Rest Protection and Efficient Access Control in the Cloud". Doctoral thesis, Università degli studi di Bergamo, 2020. http://hdl.handle.net/10446/181509.

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PECORELLI, MARICA LEONARDA. "Semi-Active Structural Control for the Seismic Protection of Cultural Heritage". Doctoral thesis, Politecnico di Torino, 2016. http://hdl.handle.net/11583/2649090.

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A number of natural hazards, such as earthquakes, flood, landslides, wildfires and cyclones can threaten the integrity of the Cultural Heritage with potentially devastating effects. The reduction of the seismic vulnerability of the cultural legacy constitutes a question of utmost importance especially in countries where vast Cultural Heritage combines with a medium/high seismic risk, such in Italy. From the second half of the 20th century the scientific community conceived a series of resolutions and recommendations to the aim of mitigating the seismic vulnerability of the Cultural Heritage. For many years most efforts focused on the protection of historical buildings. Only recently non-structural objects with recognised historical, artistic or expressive significance started to gain prominence in earthquake engineering studies. The damage suffered by these artworks can either derive from their direct exposure to earthquakes (inherent vulnerability) or it can be a consequence of the vulnerability of their container (indirect vulnerability). Within this framework the present thesis investigates the markedly non-linear seismic dynamic behaviour of art objects in 2D and proposes a novel strategy to reduce the inherent vulnerability to overturning. This novel mitigation strategy uses a bang-bang control to regulate the adjustable stiffness of a semi-active anchorage. More specifically, feedback and feedback-feedforward strategies are proposed and investigated in order to set in real-time the stiffness of the anchorage. Numerical simulations under different excitation conditions were conducted to evaluate and compare the effectiveness of the proposed control algorithms. The simulations also assess the robustness of the algorithms with respect to noises and timing issues. Art objects controlled by the proposed control strategies present a higher stability and a lower vulnerability compared to uncontrolled art objects. The topics summarised above are developed in the thesis in the following order. Chapter 1 introduces the reader to the seismic protection of art objects. The sources of both inherent and indirect vulnerability are described together with current methodologies for their evaluation. Chapter 2 presents an extensive review on the rocking motion of rigid bodies starting from the rocking model proposed by Housner in 1963. Chapter 3 reports on the seismic retrofitting strategies currently in use to reduce the overturning vulnerability of art objects. Limitations of the existing strategies are also pointed out. Chapter 4 describes a novel semi-active control system that reduces the inherent vulnerability of art objects to overturning. This chapter also describes the analytical model and the Matlab® code of the rocking motion, the two control strategies investigated to stabilize art objects and two performance indices to evaluate the benefit of the proposed control are defined. Possible solutions are examined for the practical realization of anchorages with adjustable stiffness. Chapter 5 investigates numerically the performances afforded by the two control strategies described in Chapter 4. In particular, the efficacy of the proposed control is validated with respect to synthetic ground motions. Chapter 6 extends the validation of the proposed control to real seismic accelerograms. To this aim, 100 registrations with diverse spectral characteristics were selected. Chapter 7 comments on the main results of the thesis, draws conclusions and presents some directions for future research.

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Hedefine, Eeva Kaarina. "Personal Privacy Protection within Pervasive RFID Environments". Fogler Library, University of Maine, 2006. http://www.library.umaine.edu/theses/pdf/HedefineEK2006.pdf.

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Wikman-Svahn, Per. "Ethical aspects of radiation protection". Licentiate thesis, Stockholm : Kungliga Tekniska högskolan, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3946.

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Todd, Katherine. "Health Protection in NSW". Master's thesis, Canberra, ACT : The Australian National University, 2017. http://hdl.handle.net/1885/147911.

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Health protection involves the prevention and control of threats to health from both communicable diseases and the environment. I conducted a variety of projects across the breadth of Health Protection within NSW Health between March 2016 and October 2017 to fulfil the requirements of the Masters of Philosophy in Applied Epidemiology (MAE). My first placement was within the Enteric and Zoonotic Diseases division of the Communicable Disease Branch. A large outbreak of Salmonella Saintpaul occurred in Australia between December 2015 and June 2016 with a total of 547 confirmed and probable cases notified. When I commenced in March 2016 this outbreak had been underway since December 2015 with no clear vehicle of infection identified. I conducted a case-control study including 72 confirmed cases and 144 controls from SA and NSW which identified that Mung bean sprout consumption was reported by 40.6% (28/69) of cases and 4.3% (6/140) of controls (OR 14.6, 95% CI 5.9-39.4). This outbreak led to a recall of mung bean sprouts from an implicated sprouter in South Australia and public messaging about the safe preparation and consumption of bean sprouts. In July 2016 six states and territories of Australia were affected by a large outbreak of Salmonella Hvittingfoss with 144 confirmed and suspected cases notified. I led a coordinated multi-jurisdictional investigation to identify the source of infection and control the outbreak, including conducting a case-control study. The epidemiological, microbiological and environmental investigation implicated consumption of rockmelon (OR 7.2, 95%CI 1.87-27.93) from a single producer as a significant risk for infection. The producer initiated a voluntary recall of the product. My second placement was in the Environmental Health Branch of Health Protection. I completed a review of the epidemiology of notifications in NSW to provide a snapshot of elevated blood lead levels in NSW and to inform an evaluation of the NSW elevated blood lead surveillance system. There were 9,486 notifications of elevated blood lead from 1997–2016, with an average annual notification rate of 6.9 per 100,000. I analysed notification data for by age, sex, geographic area, exposure and occupation and compared notification rates over time and between geographic regions. I identified several limitations with the dataset that made it difficult to analyse notification rates, particularly by risk and exposure history and by blood lead level, and made recommendations to improve the data collection system. I also collected qualitative data about the function of the blood lead surveillance system by conducting face-to-face interviews with key stakeholders throughout NSW. Key areas for improvement in the system included changes to the way data is entered into the surveillance system, greater guidance for public health units on following up notifications, a review of the information collected on exposure, and guidance regarding liaising with occupational health regulatory agencies to ensure follow-up of occupational notifications. Through completing these projects, I made valuable contributions to protecting the health of NSW residents.

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Khan, Sheroz. "Coordinated protection and control in power systems : an expert system approach to interlocking management". Thesis, University of Strathclyde, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338913.

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Chambers, C. "Industrial strength techniques for the development of PLC-based safety-related control and protection systems". Thesis, University of Sheffield, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327619.

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Hastings, John Charles. "A communications framework with applications in wide-area monitoring, protection and control". Thesis, Queen's University Belfast, 2017. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.726840.

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The electrical utility, which has traditionally been a centralised predictable system, is now changing to becoming a decentralised, more dynamic system with increasing distributed generation and changeable load patterns; not to mention widespread EV on the horizon. With these changes, there is an increased desire for WAMPAC to aid in managing this complex dynamic system, particularly at the distribution and prosumer level - where this framework is aimed. This thesis presents a novel communications framework to support these next-generation smart grid applications. Taking Synchrophasor data as a case-study due to its potential uses for both real- and non-real-time applications, issues are identified with existing protocols used to represent and deliver this data. From these issues, requirements are identified for data transport next generation applications. Reliability, extensibility and security are identified as key components for WAMPAC systems. These requirements act as a metric to help decide between various technologies for message formatting, and transport - which is essentially the core of WAMPAC communications. Upon investigation of the current state of the art in communications systems data representation and data transport mechanisms are selected. Namely, JSON/Protobuf for extensible message formatting, and MQTT publish/subscribe protocol as a secure, reliable and scalable delivery mechanism. The latter part of the thesis describes the implementation and testing stages that solidify the suitability of JSON and MQTT for WAMPAC communications. There is no literature to date that presents such an approach to the challenges of next-generation smart grid communications. Many of the key ideas and concepts presented in this thesis have been accepted in peer reviewed publications.

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Liu, Tong. "Protection control unit for the multi-view on-the-fly memory model". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0002/MQ31614.pdf.

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Aljadid, Abdolmonem Ibrahim. "Control and protection analysis for power distribution in a distributed generation system". Thesis, Cape Peninsula University of Technology, 2016. http://hdl.handle.net/20.500.11838/2192.

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Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology.
Distributed Generation systems based on renewable energy sources, such as wind or solar are mostly intermittent sources, due to their dependency on the weather, whereas those based on other primary energy sources are non-intermittent. All of them are specially designed to be integrated into distribution systems, in order to improve the power demand of consumers. In the last few decades of the twentieth century, several different factors have played a key role in increasing interest in systems. Distributed Generation (DG) is gaining more and more attention worldwide as an alternative to large-scale central generating stations. The aim of this research project is to investigate the contribution of distributed generation in fault current level in a power distribution system. The simulation results indicate that DG can have a positive or negative impact, on the fault current level in distribution network systems. The DG location and size affect the fault level. The second aim of this research was to suggest a model-based method for design, and implementation of a protection scheme for power distribution systems, by establish algorithms in a hardware environment. The overcurrent relay was chosen for the model development because it is considered a simple and popular protection scheme, and it is a common scheme in relaying applications. The proposed relay model was tested for fault conditions applied on a simple power system in different scenarios. The overcurrent relay model was implemented in MATLAB/Simulink, by using MATLAB programming languages and the SimPowerSystem (SPS) Tool. MATLAB/SIMULINK software is applicable to the modelling of generation, transmission, distribution and industrial grids, and the analysis of the interactions of these grids. This software provides a library of standard electrical components or models such as transformers, machines, and transmission lines. Therefore, the modelling and simulations are executed using MATLAB/Simulink version 2014b

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Burrow, Ryan David. "Enhancing Input/Output Correctness, Protection, Performance, and Scalability for Process Control Platforms". Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/89903.

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Most modern control systems use digital controllers to ensure safe operation. We modify the traditional digital control system architecture to integrate a new component known as a trusted input/output processor (TIOP). TIOP interface to the inputs (sensors) and outputs (actuators) of the system through existing communication protocols. The TIOP also interface to the application processor (AP) through a simple message passing protocol. This removes any direct input/output (I/O) interaction from taking place in the AP. By isolating this interaction from the AP, system resilience against malware is increased by enabling the ability to insert run-time monitors to ensure correct operation within provided safe limits. These run-time monitors can be located in either the TIOP(s) or in independent hardware. Furthermore, monitors have the ability to override commands from the AP should those commands seek to violate the safety requirements of the system. By isolating I/O interaction, formal methods can be applied to verify TIOP functionality, ensuring correct adherence to the rules of operation. Additionally, removing sequential I/O interaction in the AP allows multiple I/O operations to run concurrently. This reduces I/O latency which is desirable in many control systems with large numbers of sensors and actuators. Finally, by utilizing a hierarchical arrangement of TIOP, scalable growth is efficiently supported. We demonstrate this on a Xilinx Zynq-7000 programmable system-on-chip device.
Master of Science
Complex modern systems, from unmanned aircraft system to industrial plants are almost always controlled digitally. These digital control systems (DCSes) need to be verified for correctness since failures can have disastrous consequences. However, proving that a DCS will always act correctly can be infeasible if the system is too complex. In addition, with the growth of inter-connectivity of systems through the internet, malicious actors have more access than ever to attempt to cause these systems to deviate from their proper operation. This thesis seeks to solve these problems by introducing a new architecture for DCSes that uses isolated components that can be verified for correctness. In addition, safety monitors are implemented as a part of the architecture to prevent unsafe operation.

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Sun, Keyao. "Protection, Control, and Auxiliary Power of Medium-Voltage High-Frequency SiC Devices". Diss., Virginia Tech, 2021. http://hdl.handle.net/10919/103743.

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Due to the superior characteristics compared to its silicon (Si) counterpart, the wide bandgap (WBG) semiconductor enables next-generation power electronics systems with higher efficiency and higher power density. With higher blocking voltage available, WBG devices, especially the silicon carbide (SiC) metal-oxide-semiconductor field-effect transistor (MOSFET), have been widely explored in various medium-voltage (MV) applications in both industry and academia. However, due to the high di/dt and high dv/dt during the switching transient, potential overcurrent, overvoltage, and gate failure can greatly reduce the reliability of implementing SiC MOSFETs in an MV system. By utilizing the parasitic inductance between the Kelvin- and the power-source terminal, a short-circuit (SC) and overload (OL) dual-protection scheme is proposed for overcurrent protection. A full design procedure and reliability analysis are given for SC circuit design. A novel OL circuit is proposed to protect OL faults at the gate-driver level. The protection procedure can detect an SC fault within 50 nanoseconds and protect the device within 1.1 microsecond. The proposed method is a simple and effective solution for the potential overcurrent problem of the SiC MOSFET. For SiC MOSFETs in series-connection, the unbalanced voltages can result in system failure due to device breakdown or unbalanced thermal stresses. By injecting current during the turn-off transient, an active dv/dt control method is used for voltage balancing. A 6 kV phase-leg using eight 1.7 kV SiC MOSFETs in series-connection has been tested with voltage balanced accurately. Modeling of the stacked SiC MOSFET with active dv/dt control is also done to summarize the design methodology for an effective and stable system. This method provides a low-loss and compact solution for overvoltage problems when MV SiC MOSFETs are connected in series. Furthermore, a scalable auxiliary power network is proposed to prevent gate failure caused by unstable gate voltage or EMI interference. The two-stage auxiliary power network (APN) architecture includes a wireless power transfer (WPT) converter supplied by a grounded low voltage dc bus, a high step-down-ratio (HSD) converter powered from dc-link capacitors, and a battery-based mini-UPS backup power supply. The auxiliary-power-only pre-charge and discharge circuits are also designed for a 6 kV power electronics building block (PEBB). The proposed architecture provides a general solution of a scalable and reliable auxiliary power network for the SiC-MOSFET-based MV converter. For the WPT converter, a multi-objective optimization on efficiency, EMI mitigation, and high voltage insulation capability have been proposed. Specifically, a series-series-CL topology is proposed for the WPT converter. With the optimization and new topology, a 120 W, 48 V to 48 V WPT converter has been tested to be a reliable part of the auxiliary power network. For the HSD converter, a novel unidirectional voltage-balancing circuit is proposed and connected in an interleaved manner, which provides a fully modular and scalable solution. A ``linear regulator + buck" solution is proposed to be an integrated on-board auxiliary power supply. A 6 kV to 45 V, 100 W converter prototype is built and tested to be another critical part of the auxiliary power network.
Doctor of Philosophy
The wide bandgap semiconductor enables next-generation power electronics systems with higher efficiency and higher power density which will reduce the space, weight, and cost for power supply and conversion systems, especially for renewable energy. However, by pushing the system voltage level higher to medium-voltage of tens of kilovolts, although the system has higher efficiency and simpler control, the reliability drops. This dissertation, therefore, focusing on solving the possible overcurrent, overvoltage, and gate failure issues of the power electronics system that is caused by the high voltage and high electromagnetic interference environment. By utilizing the inductance of the device, a dual-protection method is proposed to prevent the overcurrent problem. The overcurrent fault can be detected within tens of nanoseconds so that the device will not be destroyed because of the huge fault current. When multiple devices are connected in series to hold higher voltage, the voltage sharing between different devices becomes another issue. The proposed modeling and control method for series-connected devices can balance the shared voltage, and make the control system stable so that no overvoltage problem will happen due to the non-evenly distributed voltages. Besides the possible overcurrent and overvoltage problems, losing control of the devices due to the unreliable auxiliary power supply is another issue. This dissertation proposed a scalable auxiliary power network with high efficiency, high immunity to electromagnetic interference, and high reliability. In this network, a wireless power transfer converter is designed to provide enough insulation and isolation capability, while a switched capacitor converter is designed to transfer voltage from several kilovolts to tens of volts. With the proposed overcurrent protection method, voltage sharing control, and reliable auxiliary power network, systems utilizing medium-voltage wide-bandgap semiconductor will have higher reliability to be implemented for different applications.

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44

Scalavino, Enrico. "A data protection architecture for derived data control in partially disconnected networks". Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/10203.

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Every organisation needs to exchange and disseminate data constantly amongst its employees, members, customers and partners. Disseminated data is often sensitive or confidential and access to it should be restricted to authorised recipients. Several enterprise rights management (ERM) systems and data protection solutions have been proposed by both academia and industry to enable usage control on disseminated data, i.e. to allow data originators to retain control over whom accesses their information, under which circumstances, and how it is used. This is often obtained by means of cryptographic techniques and thus by disseminating encrypted data that only trustworthy recipients can decrypt. Most of these solutions assume data recipients are connected to the network and able to contact remote policy evaluation authorities that can evaluate usage control policies and issue decryption keys. This assumption oversimplifies the problem by neglecting situations where connectivity is not available, as often happens in crisis management scenarios. In such situations, recipients may not be able to access the information they have received. Also, while using data, recipients and their applications can create new derived information, either by aggregating data from several sources or transforming the original data’s content or format. Existing solutions mostly neglect this problem and do not allow originators to retain control over this derived data despite the fact that it may be more sensitive or valuable than the data originally disseminated. In this thesis we propose an ERM architecture that caters for both derived data control and usage control in partially disconnected networks. We propose the use of a novel policy lattice model based on information flow and mandatory access control. Sets of policies controlling the usage of data can be specified and ordered in a lattice according to the level of protection they provide. At the same time, their association with specific data objects is mandated by rules (content verification procedures) defined in a data sharing agreement (DSA) stipulated amongst the organisations sharing information. When data is transformed, the new policies associated with it are automatically determined depending on the transformation used and the policies currently associated with the input data. The solution we propose takes into account transformations that can both increase or reduce the sensitivity of information, thus giving originators a flexible means to control their data and its derivations. When data must be disseminated in disconnected environments, the movement of users and the ad hoc connections they establish can be exploited to distribute information. To allow users to decrypt disseminated data without contacting remote evaluation authorities, we integrate our architecture with a mechanism for authority devolution, so that users moving in the disconnected area can be granted the right to evaluate policies and issue decryption keys. This allows recipients to contact any nearby user that is also a policy evaluation authority to obtain decryption keys. The mechanism has been shown to be efficient so that timely access to data is possible despite the lack of connectivity. Prototypes of the proposed solutions that protect XML documents have been developed. A realistic crisis management scenario has been used to show both the flexibility of the presented approach for derived data control and the efficiency of the authority devolution solution when handling data dissemination in simulated partially disconnected networks. While existing systems do not offer any means to control derived data and only offer partial solutions to the problem of lack of connectivity (e.g. by caching decryption keys), we have defined a set of solutions that help data originators faced with the shortcomings of current proposals to control their data in innovative, problem-oriented ways.

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Cox, Donald Patrick. "THE APPLICATION OF AUTONOMIC COMPUTING FOR THE PROTECTION OF INDUSTRIAL CONTROL SYSTEMS". Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/202691.

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Critical infrastructures are defined as the basic facilities, services and utilities needed to support the functioning of society. For over three-thousand years, civil engineers have built these infrastructures to ensure that needed services and products are available to make mankind more comfortable, secure and productive. Modern infrastructure control systems are vulnerable to disruption from natural disaster, accident, negligent operation and intentional cyber assaults from malicious agents. Many critical processes within our infrastructures are continuous (e.g., electric power, etc.) and cannot be interrupted without consequence to industry and the public. Failure to protect the critical infrastructure from cyber assaults will result in physical, economic and social impacts, extending from the local to the national level. Cyber weapons have shown that harm to infrastructures can occur before system operators have time to determine the source.We present the thesis that infrastructure control systems can employ autonomic computing technology to detect anomalies and mitigate process disruption. Specifically we focus on: 1) autonomic computing algorithms that can be integrated into control systems and networks to detect and respond to anomalies; 2) autonomic technology capable of detecting and blocking infrastructure controller commands, that if executed, would result in process disruption; 3) design and construction of a prototype Autonomic Critical Infrastructure Protection appliance (ACIP) for integration and testing of autonomic algorithms; and 4) the design and construction of a test bed capable of modeling critical infrastructures and related control systems and processes for the purpose of testing and demonstrating new autonomic technologies.We report on the development of a new, multi-dimension ontology that organizes cyber assault methodologies correlated with perpetrator motivation and goals. Using this ontology, we create a theoretical framework to identify the integration points for protective technology within infrastructure control systems. We have created a unique modeling and simulation test bed for critical infrastructure systems and processes, and a prototype autonomic computing appliance. Through this work, we have developed an expanded understanding of autonomic computing theory and its application to controls systems. We also, through experimentation, prove the thesis and establish a roadmap for future research.

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CASTELLI, FILIPPO. "Foul-control paints behavior near anodes of Impressed Current Cathodic Protection systems". Doctoral thesis, Università degli studi di Genova, 2023. https://hdl.handle.net/11567/1104637.

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It is known by foul control paint and Impressed Current Cathodic Protection system producers that paints can fail in proximity of the anodes. This failure is well known in industrial field, but does not represent a structural problem. As a matter of fact, paint recovery is performed within routinary docking operations. Within this framework, it is interesting to evaluate the behavior of new generation biocide-free foul control paints under a chemical stress resembling that near ICCP anodes, where seawater turns acidic and chlorinated. Data in this area have not been already studied nor published. The values of free chlorine and pH produced at anodes, to which paints are exposed, were obtained experimentally. Two biocide free paints, a foul release (FR) and an amphiphilic self-polishing (SP), were chosen for testing on these conditions. Paints were exposed to a 3x3 matrix of 'pH/free-Cl' different conditions. After 3 months of immersion in the selected environments, a physical-chemical characterization was performed through: visual inspection, detachment area analysis, thickness variation, contact angle variation, profilometry and IR. Laboratory and field tests were finally performed to evaluate the foul-control properties after treatments. Results showed that the degradation is mainly induced by free chlorine oxidation, and acidity strengthens the chemical attack. Both paints in the harshest condition were disbonded. Foul release paint seems generally more stable but detaches easily from the primer, while the amphiphilic SP is apparently less prone to detachment from the primer, but exhibits modification of its physical properties. Foul-control properties did not show a substantial drop after the conditioning treatment, but the tests reported detachment of both paints in conditions in which it was not previously observed.

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Ceccato, Silvia. "Security in Global Navigation Satellite Systems: authentication, integrity protection and access control". Doctoral thesis, Università degli studi di Padova, 2019. http://hdl.handle.net/11577/3425426.

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In the last decades the use of Global Navigation Satellite System (GNSS) positioning has spread through numerous commercial applications and permeated our daily life. Matching this growing interest for precise positioning worldwide, new systems have been designed and deployed, such as Galileo, the European GNSS. As these systems are relied upon in an ever growing number of safety critical applications, it is vital to devise protections and countermeasures against any threats that may target GNSS modules to harm underlying service. The potential economical advantage that derives from disrupting or manipulating the service is indeed an incentive for malicious users to devise smarter and more sophisticated threats. This thesis tackles the evolution of attacks and corresponding security measures in GNSS, investigating state-of-the-art approaches from both the attacker’s and the system’s point of view. The work focuses on various security targets, such as authentication, integrity protection and access control, exploring threats and solutions at both signal and data level. Securing GNSS from malicious entities indeed requires protecting all of its components: the navigation message, the signal-in-space and the computed Position, Velocity and Time (PVT). All three domains are investigated with the aim of assessing the vulnerability of the system to state-of-the-art threats and providing guidelines for the addition of future security features.

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48

Lewis, Karen Jane. "Biological control mechanisms of the mycoparasite Pythium oligandrum Drechsler". Thesis, University of Sheffield, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243848.

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Koski, A. (Anna). "Applicability of crude tall oil for wood protection". Doctoral thesis, University of Oulu, 2008. http://urn.fi/urn:isbn:9789514287237.

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Abstract Moisture content control is a very effective way of protecting timber. Treatments with environment-friendly, biodegradable tall oil are known to reduce the capillary water uptake of pine sapwood greatly, but despite the good results achieved there have been two problems that limit the use of tall oil for wood protection, the large amount of oil needed and the tendency for the oil to exude from the wood. This work was undertaken in order to obtain an understanding of the mechanism of wood protection by means of crude tall oil (CTO) and to find technical solutions to the main problems limiting its use for industrial wood protection. It is shown that the emulsion technique is one way of solving the first problem, as it provides high water-repellent efficiency at considerably lower oil retention levels. The fact that water is used as a thinner in this technique instead of the commonly used organic solvents is beneficial from environmental, economic and safety points of view. It is also shown that although the drying properties of CTO are inadequate for use as such in wood preservation, its oxidation and polymerization can be accelerated considerably by means of iron catalysts, which prevent the oil from exuding out of the wood. This also increases the water repellent efficiency of CTO treatment. Most impregnation oils do not dry when applied in large quantities, because they hinder the diffusion of air through the wood, which supplies the necessary oxygen. Limiting of the oil uptake by the means of the emulsion technique disturbs the airflow to a lesser extent, and thus enhances the drying process. Hence, both the emulsion technique and the use of an iron catalyst improve both the water-repellent efficiency of tall oil treatment and the rate of drying of the oil, thus solving the two main problems related to wood impregnation with tall oil in one single-stage treatment which can be used in existing wood preservation plants. This is advantageous from both an industrial and an economic point of view.

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Ukeh, Donald A. "The identification and use of semiochemicals for the control of the maize weevil, Sitophilus zeamais (Motschulsky) in Nigeria". Thesis, Available from the University of Aberdeen Library and Historic Collections Digital Resources, 2008. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&pid=25167.

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Rozprawy doktorskie na temat „Protection and Control (WAMPAC)”

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