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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Threat Assessment and Proactive Decision-Making for Crash Avoidance in Autonomous Vehicles

Khattar, Vanshaj 24 May 2021 (has links)
Threat assessment and reliable motion-prediction of surrounding vehicles are some of the major challenges encountered in autonomous vehicles' safe decision-making. Predicting a threat in advance can give an autonomous vehicle enough time to avoid crashes or near crash situations. Most vehicles on roads are human-driven, making it challenging to predict their intentions and movements due to inherent uncertainty in their behaviors. Moreover, different driver behaviors pose different kinds of threats. Various driver behavior predictive models have been proposed in the literature for motion prediction. However, these models cannot be trusted entirely due to the human drivers' highly uncertain nature. This thesis proposes a novel trust-based driver behavior prediction and stochastic reachable set threat assessment methodology for various dangerous situations on the road. This trust-based methodology allows autonomous vehicles to quantify the degree of trust in their predictions to generate the probabilistically safest trajectory. This approach can be instrumental in the near-crash scenarios where no collision-free trajectory exists. Three different driving behaviors are considered: Normal, Aggressive, and Drowsy. Hidden Markov Models are used for driver behavior prediction. A "trust" in the detected driver is established by combining four driving features: Longitudinal acceleration, lateral acceleration, lane deviation, and velocity. A stochastic reachable set-based approach is used to model these three different driving behaviors. Two measures of threat are proposed: Current Threat and Short Term Prediction Threat which quantify present and the future probability of a crash. The proposed threat assessment methodology resulted in a lower rate of false positives and negatives. This probabilistic threat assessment methodology is used to address the second challenge in autonomous vehicle safety: crash avoidance decision-making. This thesis presents a fast, proactive decision-making methodology based on Stochastic Model Predictive Control (SMPC). A proactive decision-making approach exploits the surrounding human-driven vehicles' intent to assess the future threat, which helps generate a safe trajectory in advance, unlike reactive decision-making approaches that do not account for the surrounding vehicles' future intent. The crash avoidance problem is formulated as a chance-constrained optimization problem to account for uncertainty in the surrounding vehicle's motion. These chance-constraints always ensure a minimum probabilistic safety of the autonomous vehicle by keeping the probability of crash below a predefined risk parameter. This thesis proposes a tractable and deterministic reformulation of these chance-constraints using convex hull formulation for a fast real-time implementation. The controller's performance is studied for different risk parameters used in the chance-constraint formulation. Simulation results show that the proposed control methodology can avoid crashes in most hazardous situations on the road. / Master of Science / Unexpected road situations frequently arise on the roads which leads to crashes. In an NHTSA study, it was reported that around 94% of car crashes could be attributed to driver errors and misjudgments. This could be attributed to drinking and driving, fatigue, or reckless driving on the roads. Full self-driving cars can significantly reduce the frequency of such accidents. Testing of self-driving cars has recently begun on certain roads, and it is estimated that one in ten cars will be self-driving by the year 2030. This means that these self-driving cars will need to operate in human-driven environments and interact with human-driven vehicles. Therefore, it is crucial for autonomous vehicles to understand the way humans drive on the road to avoid collisions and interact safely with human-driven vehicles on the road. Detecting a threat in advance and generating a safe trajectory for crash avoidance are some of the major challenges faced by autonomous vehicles. We have proposed a reliable decision-making algorithm for crash avoidance in autonomous vehicles. Our framework addresses two core challenges encountered in crash avoidance decision-making in autonomous vehicles: 1. The outside challenge: Reliable motion prediction of surrounding vehicles to continuously assess the threat to the autonomous vehicle. 2. The inside challenge: Generating a safe trajectory for the autonomous vehicle in case of future predicted threat. The outside challenge is to predict the motion of surrounding vehicles. This requires building a reliable model through which future evolution of their position states can be predicted. Building these models is not trivial, as the surrounding vehicles' motion depends on human driver intentions and behaviors, which are highly uncertain. Various driver behavior predictive models have been proposed in the literature. However, most do not quantify trust in their predictions. We have proposed a trust-based driver behavior prediction method which combines all sensor measurements to output the probability (trust value) of a certain driver being "drowsy", "aggressive", or "normal". This method allows the autonomous vehicle to choose how much to trust a particular prediction. Once a picture is painted of surrounding vehicles, we can generate safe trajectories in advance – the inside challenge. Most existing approaches use stochastic optimal control methods, which are computationally expensive and impractical for fast real-time decision-making in crash scenarios. We have proposed a fast, proactive decision-making algorithm to generate crash avoidance trajectories based on Stochastic Model Predictive Control (SMPC). We reformulate the SMPC probabilistic constraints as deterministic constraints using convex hull formulation, allowing for faster real-time implementation. This deterministic SMPC implementation ensures in real-time that the vehicle maintains a minimum probabilistic safety.
12

A Quantitative Evaluation Framework for Component Security in Distributed Information Systems / Ett kvantitativt utvärderingsramverk för komponenters säkerhet i distribuerade informationssystem

Bond, Anders, Påhlsson, Nils January 2004 (has links)
<p>The Heimdal Framework presented in this thesis is a step towards an unambiguous framework that reveals the objective strength and weaknesses of the security of components. It provides a way to combine different aspects affecting the security of components - such as category requirements, implemented security functionality and the environment in which it operates - in a modular way, making each module replaceable in the event that a more accurate module is developed. </p><p>The environment is assessed and quantified through a methodology presented as a part of the Heimdal Framework. The result of the evaluation is quantitative data, which can be presented with varying degrees of detail, reflecting the needs of the evaluator. </p><p>The framework is flexible and divides the problem space into smaller, more accomplishable subtasks with the means to focus on specific problems, aspects or system scopes. The evaluation method is focusing on technological components and is based on, but not limited to, the Security Functional Requirements (SFR) of the Common Criteria.</p>
13

Ports, Prosperity, and Pests: Assessing the Threat of Aquatic Invasive Species Introduced by Maritime Shipping Activity in Cuba

O'Brien, Charleen 22 November 2016 (has links)
Aquatic invasive species (AIS) are biological pollutants that cause detrimental ecological, economic, and sociological effects on non-native communities. With increasing globalization through maritime trade, coastal ports are vulnerable to AIS introductions transported by commercial vessels. As Cuba’s Port Mariel becomes a competitive transshipment hub within the Caribbean, it is essential to identify the potential threat that AIS may pose with a likely increase in shipping activity. It is equally important to understand the status of established AIS in Cuba and control measures presently being implemented by the country. This information can provide guidance for establishing or improving Cuban AIS preventative and remedial actions. For this study, publically accessible information was used to conduct threat assessments of present and potential AIS in Cuba and to identify feasible international donors of AIS due to trade with Port Mariel. Fifteen species were identified as established Cuban AIS, eight of which were associated with harmful impacts to the environment, economy, and human health. Only one established AIS, Perna viridis (the Asian green mussel), was recorded as having repeated, negative influences in Cuba. Regional trade partners of Port Mariel were identified as the most likely donors of AIS due to ecological similarity and minimal voyage duration between countries. These trade partners also represented the busiest ports and transshipment hubs in the wider Caribbean region and, therefore, could expose Port Mariel to ‘stepping-stone’ invasions. Five species associated with international trade partners were identified as potentially detrimental to Cuba if introduced into Port Mariel. There were no significant differences between the salinity and temperature tolerances of the AIS already established in Cuba and the possible AIS of concern, suggesting that these potential invaders could survive the environmental conditions of Port Mariel and subsequently become established throughout Cuba. The results presented herein are a preliminary assessment of AIS threats in Cuba and emphasize the importance of prioritizing AIS prevention and management. This study also establishes a baseline inventory of potential AIS in Cuba and a methodology that can be followed for future analyses outside of the study region.
14

‘As a journalist I should not be fearful’ : How democracy’s watchdogs use digital tools to mitigate threats

Orebäck, Johan January 2022 (has links)
Journalism is an ever-changing profession that is right now getting increasingly impacted by advancements in technology. These advancements make it easier, faster, and possibly safer to conduct journalism. At the same time, journalists are subjected to threats, and while some level of safety comes with digital advancements, they might also provide opportunities for reaching and threatening journalists that were not possible just a few years ago. This requires journalists to stay up to date on technological advancements in order to mitigate threats.  This thesis is based on interviews with five journalists whose work put them in or near danger and utilizes an inductive approach to iteratively study the data and analyze it using existing frameworks to categorize tactics used by journalists. This study identifies three larger categories of threats that journalists are subjected to, and the measures taken to defend against these threats with a special focus on the digital technologies at their disposal. It finds that the tactics vary depending on the source of the threats and range from being non-violent, to legitimate threats on journalists’ lives. In response, journalists use tactics to remain under the radar of danger, or to find safety using low-tech tools and to even use digital tools as an opportunity to conduct journalism that would otherwise be out of their reach. The study concludes that rather than categorizing journalists, it is better to categorize their actions in order to see them as changeable and possible to be used as reactions to threats.
15

Restoration of the endangered Cumberland elktoe (Alasmidonta atropurpurea) and Cumberland bean (Villosa trabalis) (Bivalvia: Unionidae) in the Big South Fork National River and Recreation Area, Tennessee and Kentucky

Guyot, Jennifer Ann 04 April 2006 (has links)
The Big South Fork National River and Recreation Area (NRRA), located in Tennessee and Kentucky, has prepared a management plan to include restoration of its mussel fauna to historic levels. Restoration activities include propagation of juvenile mussels and relocation of adults to suitable sites in the Big South Fork of the Cumberland River (BSF) and its tributaries. This study was conducted to identify host fish for Cumberland elktoe (Alasmidonta atropurpurea) and Cumberland bean (Villosa trabalis), to determine suitable juvenile culture conditions for Epioblasma brevidens and V. trabalis, and to locate sites important to future mussel restoration efforts in the NRRA. Host fish identifications and propagation techniques were determined for two of the endangered species in the NRRA, Cumberland elktoe (Alasmidonta atropurpurea) and Cumberland bean (Villosa trabalis). Of seven host species tested, banded sculpin (Cottus carolinae) was the most suitable host fish for propagation of A. atropurpurea. Of five host species tested, fantail darters (Etheostoma flabellare) were the most suitable host fish for propagation of V. trabalis. Culture techniques to raise juvenile mussels in captivity were evaluated, using newly metamorphosed juveniles of V. trabalis and E. brevidens in recirculating systems. No differences in juvenile growth or survival were detected among substrates used (fine sediment, coarse sand, and a mixture of the two). Recirculating system design seemed to affect juvenile growth and survival; however, variable condition of juveniles also seemed to affect results, making it difficult to determine effects from trial treatments. Finally, an assessment of potential sites in the NRRA for restoration activities was conducted using spatial analysis in a geographic information system (GIS) and several measures of conservation value. Mussel restoration sites were assessed for potential threats from adjacent land uses that may negatively affect mussels, including coal mines, oil and gas wells, transportation corridors, agriculture and urban development. Sites were also evaluated on their current conservation value to designate which sites are most important to long-term maintenance of mussel fauna. Several sites were identified that contain relatively few land-use threats, and are appropriate for mussel restoration activities, including Big Island, Station Camp Creek, and Parchcorn Creek sites on the mainstem BSF, as well as sites on Clear Fork and North White Oak Creek. Many of these sites also have high conservation values. Other sites had relatively high land-use threats that need to be addressed before restoration activities take place. Such sites include Leatherwood Ford, Rough Shoals Branch, Blue Heron, and Yamacraw on the mainstem BSF. The dominant threat to most sites came from transportation corridors, whereas some sites in southern and eastern portions of the watershed also were threatened by coal mines, and oil and gas wells. / Master of Science
16

A Quantitative Evaluation Framework for Component Security in Distributed Information Systems / Ett kvantitativt utvärderingsramverk för komponenters säkerhet i distribuerade informationssystem

Bond, Anders, Påhlsson, Nils January 2004 (has links)
The Heimdal Framework presented in this thesis is a step towards an unambiguous framework that reveals the objective strength and weaknesses of the security of components. It provides a way to combine different aspects affecting the security of components - such as category requirements, implemented security functionality and the environment in which it operates - in a modular way, making each module replaceable in the event that a more accurate module is developed. The environment is assessed and quantified through a methodology presented as a part of the Heimdal Framework. The result of the evaluation is quantitative data, which can be presented with varying degrees of detail, reflecting the needs of the evaluator. The framework is flexible and divides the problem space into smaller, more accomplishable subtasks with the means to focus on specific problems, aspects or system scopes. The evaluation method is focusing on technological components and is based on, but not limited to, the Security Functional Requirements (SFR) of the Common Criteria.
17

A Modelling Study to Examine Threat Assessment Algorithms Performance in Predicting Cyclist Fall Risk in Safety Critical Bicycle-Automatic Vehicle lnteractions

Reijne, Marco M., Dehkordi, Sepehr G., Glaser, Sebastien, Twisk, Divera, Schwab, A. L. 19 December 2022 (has links)
Falls are responsible for a large proportion of serious injuries and deaths among cyclists [1-4]. A common fall scenario is loss of balance during an emergency braking maneuver to avoid another vehicle [5-7]. Automated Vehicles (AV) have the potential to prevent these critical scenarios between bicycle and cars. However, current Threat Assessment Algorithms (TAA) used by AVs only consider collision avoidance to decide upon safe gaps and decelerations when interacting wih cyclists and do not consider bicycle specific balance-related constraints. To date, no studies have addressed this risk of falls in safety critical scenarios. Yet, given the bicycle dynamics, we hypothesized that the existing TAA may be inaccurate in predicting the threat of cyclist falls and misclassify unsafe interactions. To test this hypothesis, this study developed a simple Newtonian mechanics-based model that calculates the performance of two existing TAAs in four critical scenarios with two road conditions. Tue four scenarios are: (1) a crossing scenario and a bicycle following lead car scenario in which the car either (2) suddenly braked, (3) halted or (4) accelerated from standstill. These scenarios have been identified by bicycle-car conflict studies as common scenarios where the car driver elicits an emergency braking response of the cyclist [8-11] and are illustrated in Figure 1. The two TAAs are Time-to-Collision (TTC) and Headway (H). These TAAs are commonly used by AVs in the four critical scenarios that will be modelled. The two road conditions are a flat dry road and also a downhill wet road, which serves as a worst-case condition for loss of balance during emergency braking [12].
18

Ethical Hacking of an IoT-device: Threat Assessment and Penetration Testing : A Survey on Security of a Smart Refrigerator

Radholm, Fredrik, Abefelt, Niklas January 2020 (has links)
Internet of things (IoT) devices are becoming more prevalent. Due to a rapidly growing market of these appliances, improper security measures lead to an expanding range of attacks. There is a devoir of testing and securing these devices to contribute to a more sustainable society. This thesis has evaluated the security of an IoT-refrigerator by using ethical hacking, where a threat model was produced to identify vulnerabilities. Penetration tests were performed based on the threat model. The results from the penetration tests did not find any exploitable vulnerabilities. The conclusion from evaluating the security of this Samsung refrigerator can say the product is secure and contributes to a connected, secure, and sustainable society. / Internet of Things (IoT) enheter blir mer allmänt förekommande. På grund av en snabbt expanderande marknad av dessa apparater, har bristfälliga säkerhetsåtgärder resulterat till en mängd olika attacker. Det finns ett behov att testa dessa enheter for att bidra till ett mer säkert och hållbart samhälle. Denna avhandling har utvärderat säkerheten av ett IoT-kylskåp genom att producera en hot modell för att identifiera sårbarheter. Penetrationstester har utförts på enheten, baserade på hot modellen. Resultatet av penetrationstesterna hittade inga utnyttjningsbara sårbarheter. Slutsatsen från utvärderingen av säkerheten på Samsung-kylskåpet är att produkten är säker och bidrar till ett uppkopplat, säkert, och hållbart samhälle.
19

Threat Modeling and Penetration Testing of a Yanzi IoT-system : A Survey on the Security of the system’s RF communication

Isabar, Diyala January 2021 (has links)
Internet of Thing (IoT) products have in recent years become increasingly popular with both industries and private consumers, and it has been forecasted that the number of connected devices around the world will be roughly 14 billion in the year 2022. One particular field that the booming of IoT solutions continues to create endless possibilities for is smart offices. Several different devices are connected in an office environment to create a better workplace and enable a better, faster and smarter working approach. However, while there are several advantages with IoTs, they have also introduced new security threats that can not be overlooked. In this thesis, the security of a smart office system designed by Yanzi is examined. The system consists of a gateway, 34 sensors and a cloud service embedded as a SaaS. The security analysis was performed in three steps: planning, penetration testing and reporting. Radio frequency (RF) hacking against the systems RF communication was the main focus of the work. Due to some technical issues, not all selected attacks were possible to perform. Out of three that were possible to perform, one of them revealed a security flaw. Different countermeasures for the found flaw were proposed. / ”Internet av saker” produkter har under de senaste åren blivit alltmer populära bland både industrier och privata konsumenter, och man har prognostiserat att antalet anslutna enheter runt om i världen kommer att vara ungefär 14 miljarder år 2022. Ett särskilt område som ökandet av IoT-lösningar fortsätter att skapa oändliga möjligheter för är smarta kontor. Flera olika enheter är anslutna i en kontorsmiljö för att skapa en bättre arbetsplats och möjliggöra ett bättre, snabbare och smartare arbetssätt. Även om det finns flera fördelar med IoT, har de också infört nya säkerhetshot som inte kan förbises. I denna avhandling undersöks säkerheten för ett smart kontorssystem som designats av Yanzi. Systemet består av en gateway, 34 sensorer och en molntjänst inbäddad som en SaaS. Säkerhetsanalysen utfördes i tre steg: planering, penetrationstestning och rapportering. Radiofrekvenshackning mot systemets radiokommunikation var huvudfokus för arbetet. På grund av vissa tekniska problem var det inte möjligt att utföra alla föreslagna attacker. Av de tre som var möjliga att utföra avslöjade en av dem ett säkerhetsfel. Olika motåtgärder för den funna sårbarheten föreslås.
20

Methods for Co-Orbital Threat Assessment in Space / Metoder för Koorbital Hotbedömning i Rymden

Dahlman, Mathias January 2023 (has links)
This study investigates methods for assessing threats in space. Space services are crucial to both civilian and military capabilities, and a loss of such systems could have severe consequences. Space systems are exposed to various types of threats. To ensure the benefits of space-based applications, protect space assets, improve security, and maintain the space environment, it is crucial to assess threats in space. This thesis focuses on co-orbital antagonistic threats arising from satellites that are capable of performing precision manoeuvres. These satellites could either perform physical attacks or perform operations such as inspection, eavesdropping, or disruption on other satellites. Lambert's problem can be utilised for calculating orbital transfers. By solving the problem iteratively over a range of values of when the transfer is executed and the transfer time, it is possible to detect when a transfer is feasible. This can be used to assess when a satellite can pose a threat to a target. The calculations of orbital transfers are improved by the implementation of a genetic algorithm. The algorithm can solve for both direct transfers to the target and transfers using multiple impulses. Furthermore, a genetic algorithm, called NSGA-II, which can handle multiple objective functions is also analysed. The implemented methods show the potential of being employed to assess threats, especially for direct transfers where a single impulse is executed to transfer to a target. In this case, it is possible to identify threats based on the satellite's $\Delta v$ budget. However, when additional impulses are introduced it becomes more complicated. It is more difficult to estimate when an attack is more likely to commence. The implemented methods show potential, but further research is required in order to develop a robust method to assess co-orbital threats.  The conducted analysis has highlighted a few aspects that are crucial for assessing co-orbital threats. Information about the $\Delta v$ budget of the satellite that potentially could pose a threat must be available. Furthermore, space surveillance and tracking capabilities are essential to detect orbital changes, which can be vital to perform counter-operations in the event of an attack / Denna studie undersöker metoder för hotbedöming i rymden. Rymdtjänster är av avgörande betydelse för både civila och militära förmågor och förlusten av sådana system kan leda till allvarliga konsekvenser. Rymdsystem är utsatta för olika typer av hot. För att säkerställa fördelarna med rymdbaserade tillämpningar, skydda rymdresurser, förbättra säkerheten och bevara rymdmiljön är det viktigt att bedöma hot i rymden. Detta examensarbete fokuserar på hot från precisionsmanövrerande satelliter som antingen kan genomföra fysiska attacker eller utföra operationer såsom inspektion, avlyssning eller störning av en annan satellit. Lamberts problem kan användas för att beräkna banmanövrar. Genom att lösa problemet iterativt över olika värden för när manöverna utförs och flygtiden är det möjligt att fastställa när en manöver är genomförbar. Detta kan användas för att bedöma när en satellit kan utgöra ett hot mot en målsatellit. Beräkningarna av banmanövrar förbättras genom implementeringen av en genetisk algoritm. Algoritmen kan lösa både direkta manövrar till målet och manövrar med flera impulser. Dessutom analyseras en genetisk algoritm, kallad NSGA-II, som kan hantera flera målfunktioner. De implementerade metoderna visar potential för att kunna användas för hotbedömning, särskilt för direkta manövrar där en enda impuls används för att ändra banan till målet. I detta fall är det möjligt att identifiera hot baserat på satellitens $\Delta v$-budget. Däremot blir det mer komplicerat när ytterligare impulser introduceras. Det blir svårare att bedöma när en attack sannolikt inleds. De implementerade metoderna visar potential, men ytterligare forskning krävs för att utveckla en robust metod för att bedöma hot från precisionsmanövrerande satelliter. Den genomförda analysen har framhävt några aspekter som är av avgörande betydelse för att utföra en hotbedömning. Information om satellitens $\Delta v$-budget som potentiellt kan utgöra ett hot måste vara tillgänglig. Dessutom är inmätning och övervakningsförmåga av satelliter avgörande för att upptäcka banförändringar, vilket kan vara kritiskt vid genomförande av motåtgärder i händelse av en attack.

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