Efficient and Privacy-Preserving Ride Sharing Organization for Transferable and Non-Transferable Services

Ride-sharing allows multiple persons to share their trips together in one vehicle instead of using multiple vehicles. This can reduce the number of vehicles in the street, which consequently can reduce air pollution, traffic congestion and transportation cost. However, a ride-sharing organization requires passengers to report sensitive location information about their trips to a trip organizing server (TOS) which creates a serious privacy issue. In addition, existing ride-sharing schemes are non-flexible, i.e., they require a driver and a rider to have exactly the same trip to share a ride. Moreover, they are non-scalable, i.e., inefficient if applied to large geographic areas. In this paper, we propose two efficient privacy-preserving ride-sharing organization schemes for Non-transferable Ride-sharing Services (NRS) and Transferable Ride-sharing Services (TRS). In the NRS scheme, a rider can share a ride from its source to destination with only one driver whereas, in TRS scheme, a rider can transfer between multiple drivers while en route until he reaches his destination. In both schemes, the ride-sharing area is divided into a number of small geographic areas, called cells, and each cell has a unique identifier. Each driver/rider should encrypt his trip's data and send an encrypted ride-sharing offer/request to the TOS. In NRS scheme, Bloom filters are used to compactly represent the trip information before encryption. Then, the TOS can measure the similarity between the encrypted trips data to organize shared rides without revealing either the users' identities or the location information. In TRS scheme, drivers report their encrypted routes, an then the TOS builds an encrypted directed graph that is passed to a modified version of Dijkstra's shortest path algorithm to search for an optimal path of rides that can achieve a set of preferences defined by the riders

Characterisation and Development of Nanostructured, Ultrahigh Strength, and Ductile Bainitic Steels

The purpose of the present work was to characterise and further develop a novel nanostructured type of bainitic steel. Three chemical compositions were considered with different concentrations of Al and Co. The addition of Al and Co is believed to be necessary to produce the desired nanostructure at very low temperatures within a reasonable transformation time. An overview of the mechanical performance of fully bainitic steels vs other steel systems is presented in Chapter 1. An introduction to metallurgical concepts regarding the design and performance of bainite steels is presented in Chapters 1 and 2. Chapter 2 focuses on the design concepts by which the steel chemical composition was optimised, primarily on the basis of cost and the avoidance of carbide precipitation. Chapter 3 deals with the evolution of the microstructure during uniaxial tension, studied using X-ray diffraction. The effect of tempering deformed and undeformed structures, and heating to high temperatures, have also been investigated. In this context, data on bainite-containing steels in the literature are found to be rather limited. Chapter 4 is a comprehensive assessment of the mechanical behaviour of the steels subjected to a variety of processing routes. It is demonstrated that it is possible to outperform current commercially available steels. The microstructural behaviour of strain-aged and as-transformed steels during uniaxial tension studied using in situ neutron diffraction is described in Chapter 5. The evolution of texture with plastic deformation was confirmed as previously observed using conventional X-ray analysis. Evidence regarding the presence of two populations of carbon-depleted and carbon-rich austenite and their response to strain, grain rotation, anisotropy, stress partitioning between phases and the lack of work-hardening to overcome the onset of necking are presented

A Defense Framework Against Denial-of-Service in Computer Networks

Denial-of-Service (DoS) is a computer security problem that poses a serious challenge totrustworthiness of services deployed over computer networks. The aim of DoS attacks isto make services unavailable to legitimate users, and current network architectures alloweasy-to-launch, hard-to-stop DoS attacks. Particularly challenging are the service-level DoSattacks, whereby the victim service is flooded with legitimate-like requests, and the jammingattack, in which wireless communication is blocked by malicious radio interference. Theseattacks are overwhelming even for massively-resourced services, and effective and efficientdefenses are highly needed. This work contributes a novel defense framework, which I call dodging, against service-level DoS and wireless jamming. Dodging has two components: (1) the careful assignment ofservers to clients to achieve accurate and quick identification of service-level DoS attackersand (2) the continuous and unpredictable-to-attackers reconfiguration of the client-serverassignment and the radio-channel mapping to withstand service-level and jamming DoSattacks. Dodging creates hard-to-evade baits, or traps, and dilutes the attack "fire power".The traps identify the attackers when they violate the mapping function and even when theyattack while correctly following the mapping function. Moreover, dodging keeps attackers"in the dark", trying to follow the unpredictably changing mapping. They may hit a fewtimes but lose "precious" time before they are identified and stopped. Three dodging-based DoS defense algorithms are developed in this work. They are moreresource-efficient than state-of-the-art DoS detection and mitigation techniques. Honeybees combines channel hopping and error-correcting codes to achieve bandwidth-efficientand energy-efficient mitigation of jamming in multi-radio networks. In roaming honeypots, dodging enables the camouflaging of honeypots, or trap machines, as real servers,making it hard for attackers to locate and avoid the traps. Furthermore, shuffling requestsover servers opens up windows of opportunity, during which legitimate requests are serviced.Live baiting, efficiently identifies service-level DoS attackers by employing results fromthe group-testing theory, discovering defective members in a population using the minimumnumber of tests. The cost and benefit of the dodging algorithms are analyzed theoretically,in simulation, and using prototype experiments

Runtime resource management for vision-based applications in mobile robots

Computer-vision (CV) applications are an important part of mobile robot automation, analyzing the perceived raw data from vision sensors and providing a rich amount of information on the surrounding environment. The design of a high-speed and energy-efficient CV application for a resource-constrained mobile robot, while maintaining a certain targeted level of accuracy in computation, is a challenging task. This is because such applications demand a lot of resources, e.g. computing capacity and battery energy, to run seamlessly in real time. Moreover, there is always a trade-off between accuracy, performance and energy consumption, as these factors dynamically affect each other at runtime. In this thesis, we investigate novel runtime resource management approaches to improve performance and energy efficiency of vision-based applications in mobile robots. Due to the dynamic correlation between different management objectives, such as energy consumption and execution time, both environmental and computational observations need to be dynamically updated, and the actuators are manipulated at runtime based on these observations. Algorithmic and computational parameters of a CV application (output accuracy and CPU voltage/frequency) are adjusted by measuring the key factors associated with the intensity of computations and strain on CPUs (environmental complexity and instantaneous power). Furthermore, we show how mechanical characteristics of the robot, i.e. the speed of movement in this thesis, can affect the computational behaviour. Based on this investigation, we add the speed of a robot, as an actuator, to our resource management algorithm besides the considered computational knobs (output accuracy and CPU voltage/frequency). To evaluate the proposed approach, we perform several experiments on an unmanned ground vehicle equipped with an embedded computer board and use RGB and event cameras as the vision sensors for CV applications. The obtained results show that the presented management strategy improves the performance and accuracy of vision-based applications while significantly reducing the energy consumption compared with the state-of-the-art solutions. Moreover, we demonstrate that considering simultaneously both computational and mechanical aspects in management of CV applications running on mobile robots significantly reduces the energy consumption compared with similar methods that consider these two aspects separately, oblivious to each other’s outcome

Enhanced UML Methodology with New Hybrid Diagrams: An ATM Application

Object oriented proved to be the most important software engineering tools. The main reason behind the importance is that, Object Oriented covers the most powerful programming languages such as Java and C++. UML is a modeling language which is a part of object oriented and it was created to provide the software development industry with analysis and design techniques based on some diagrams. The most common UML diagrams in use are Class and Activity diagram. To implement any system using object oriented UML, the programmer needs at least two or three diagrams beside the Use Case diagram in order to understand a full picture of the system. There is no diagram which can show the full picture of the system. In this research, new methodology called “Touch and Go†has been generated by the researchers to implement the system. In this methodology, analysis and design are merged in one stage called Touch. Implementation and testing stage are merged in one stage called Go. The Class and Activity diagram are merged to introduce new integrated diagram called Enhanced Class Activity (ECA) diagram and the normal Activity diagram will be modified and improved as Activity Remarked Class (ARC) diagram. Analytical analysis of the new methodology is implemented in ATM machine system which can be later implemented using Java language or any other Object Oriented language. A powerful system like ATM is chosen to apply the new technique and it has been shown clearly how the methodology is working perfectly with such system. This study helps to reduce the number of diagrams that are being used to implement the system, reducing total time of implementation and making the coding stage easier by using only few numbers of diagrams

Hydraulic fracture design optimization for Nubian sandstone formation in Libya

There is growing interest in developing unconventional oil and gas reserves in Libya, such as the tight portions of the Nubian sandstone. Well-X7 is a development well drilled to a TD of 13,005\u27 penetrating the Upper Nubain Sandstone (UNSS) at 12,122\u27-12,207\u27 and the Lower Nubain Sandstone (LNSS) at 12,524\u27-12,880\u27 KB. Based on open hole logs, the UNSS has 71 ft of net pay and the LNSS was found to have 295 ft of net pay. Openhole logs also showed low permeabilities of 2.5 and 3 md for the UNSS and LNSS, respectively. The well was initially perforated in both zones and tested 385 bopd. Hydraulic fracturing is to be applied to this well in the future. This study evaluated 13 different stimulation treatments for the X-7 well. F300 frac fluid was used with varying proppant type and size, including Ottawa sand, Brady sand and Carbo Lite ceramic. 20-40 Carbo Lite ceramic was used with four different frac fluids, including slickwater. Results for all cases compared IP and 24-month cumulative recovery. Results show that a combination of F300 frac fluid and 20-40 Carbo Lite ceramic proppant give highest production rates. However, cases evaluated had low FCD suggesting conductivity should be increased, and treatment size can be reduced in a final treatment design --Abstract, page iii.