10 research outputs found

    EFFICIENT RUNTIME SECURITY SYSTEM FOR DECENTRALISED DISTRIBUTED SYSTEMS

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    Distributed systems can be defined as systems that are scattered over geographical distances and provide different activities through communication, processing, data transfer and so on. Thus, increasing the cooperation, efficiency, and reliability to deal with users and data resources jointly. For this reason, distributed systems have been shown to be a promising infrastructure for most applications in the digital world. Despite their advantages, keeping these systems secure, is a complex task because of the unconventional nature of distributed systems which can produce many security problems like phishing, denial of services or eavesdropping. Therefore, adopting security and privacy policies in distributed systems will increase the trustworthiness between the users and these systems. However, adding or updating security is considered one of the most challenging concerns and this relies on various security vulnerabilities which existing in distributed systems. The most significant one is inserting or modifying a new security concern or even removing it according to the security status which may appear at runtime. Moreover, these problems will be exacerbated when the system adopts the multi-hop concept as a way to deal with transmitting and processing information. This can pose many significant security challenges especially if dealing with decentralized distributed systems and the security must be furnished as end-to-end. Unfortunately, existing solutions are insufficient to deal with these problems like CORBA which is considered a one-to-one relationship only, or DSAW which deals with end-to-end security but without taking into account the possibility of changing information sensitivity during runtime. This thesis provides a proposed mechanism for enforcing security policies and dealing with distributed systems’ security weakness in term of the software perspective. The proposed solution utilised Aspect-Oriented Programming (AOP), to address security concerns during compilation and running time. The proposed solution is based on a decentralized distributed system that adopts the multi-hop concept to deal with different requested tasks. The proposed system focused on how to achieve high accuracy, data integrity and high efficiency of the distributed system in real time. This is done through modularising the most efficient security solutions, Access Control and Cryptography, by using Aspect-Oriented Programming language. The experiments’ results show the proposed solution overcomes the shortage of the existing solutions by fully integrating with the decentralized distributed system to achieve dynamic, high cooperation, high performance and end-to-end holistic security

    Neuronal morphologies: the shapes of thoughts

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    The mammalian brain, one of the most fascinating systems in nature, is a complex biological structure that has kept scientists busy for over a century. Many of the brain's mysteries have been unraveled due to the enormous efforts of the scientific community, but yet many questions remain unsolved. The detailed drawings of Ramon y Cajal revealed the hidden structure of the brain, identifying the neurons as its fundamental structural and functional units. Although a significant amount of experimental reconstructions have been gathered over the past years, neuronal morphologies still remain one of the unsolved riddles of the brain. Why is neuronal diversity important for the functionality of the brain and how do neuronal morphologies ''shape'' our thoughts? To address these questions one needs to characterize the various shapes of neuronal morphologies. Traditionally, this task has been performed by using a set of morphological features, such as total length, branch orders and asymmetry. However, these features focus on a specific morphological aspect thereby causing a significant information loss from the original structure. Inspired by algebraic topology, I have conceived a topological descriptor of neuronal trees that couples the topology of a tree with the geometric features of its structure, retaining more details of the original morphology than traditional morphometrics. This descriptor has proved to be very powerful in discriminating several neuronal types into concrete groups based on morphological grounds, and has lead to the discovery of two distinct classes of pyramidal cells in the human cortex. In addition, the Topological Morphology Descriptor is important for the generation of artificial cells whose morphologies remain faithful to the biological ones. Neurons of the same morphological type have similar topological and geometric characteristics, therefore appearing to be highly structured. However, it is still unknown to what extent the complex neuronal morphology is shaped by the genetic information of an organism and to what extent it arises from stochastic processes. To study the impact of randomness and structure of neuronal morphologies on the connectivity of the network they form, I compared the properties of networks that arise from different artificially generated morphologies, ranging from random walks to constrained branching structures, against those of biological networks and computational reconstructions built from biological morphologies. Surprisingly, networks that are generated from almost random morphologies share a lot of common properties with biological networks, such as the spatial clustering of connections and the common neighbor effect, indicating that stochastic processes that take place during development, contribute significantly to the observed neuronal shapes. This thesis resolves a number of the mysteries of neuronal morphologies and questions our beliefs about the role of randomness in the formation of the brain. Thus, it brings us closer to understanding the fundamental differences among morphologies, and how randomness and structure are combined together to generate one of the most complex biological systems

    An Efficient Platform for the Automatic Extraction of Patterns in Native Code

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    Different software tools, such as decompilers, code quality analyzers, recognizers of packed executable files, authorship analyzers, and malware detectors, search for patterns in binary code. The use of machine learning algorithms, trained with programs taken from the huge number of applications in the existing open source code repositories, allows finding patterns not detected with the manual approach. To this end, we have created a versatile platform for the automatic extraction of patterns from native code, capable of processing big binary files. Its implementation has been parallelized, providing important runtime performance benefits for multicore architectures. Compared to the single-processor execution, the average performance improvement obtained with the best configuration is 3.5 factors over the maximum theoretical gain of 4 factors

    Information Fusion Methodology for Enhancing Situation Awareness in Connected Cars Environment

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    This dissertation introduces novel approaches to develop a comprehensive model to address situation awareness in the Internet of Cars, called Attention Assist Framework (AAF). The proposed framework utilizes both Low-Level Data Fusion (LLDF), and High-Level Information Fusion (HLIF) to implement traffic entity, situation, and impact assessment, as well as decision making. The Internet of Cars is the convergence of the Internet of Things and Vehicular Ad-hoc Networks (VANETs). In fact, VANETs are the communication platforms that make possible the implementation of the Internet of Cars, and has become an integral part of this research field due to its major role to improve vehicle and road safety, traffic efficiency, and convenience as well as comfort to both drivers and passengers. Significant amount of VANETs research work has been focused on specific areas such as safety, routing, broadcasting, Quality of Service (QoS), and security. Among them, road safety issues are deemed one of the most challenging problems of VANETs. Specifically, lack of proper situational awareness of drivers has been shown to be the main cause of road accidents which makes it a major factor in road safety. The traffic entity assessment relies on a LLDF framework that is able to incorporate various multi-sensor data fusion approaches with means of communication links in VANETs. This is used to implement a cooperative localization approach through fusing common data fusion methods, such as Extended Kalman Filter (EKF) and Unscented Transform (UT), and vehicle-to-vehicle communication in VANETs. Furthermore, traffic situation assessment is based on a fuzzy extension to the Multi-Entity Bayesian Networks (MEBNs), which exploit the expressiveness of first-order logic for semantic relations, and the strength of the Fuzzy Bayesian Networks in handling uncertainty, while tackling the inherent vagueness in the soft data created by human entities. Finally, the impact assessment and decision making is realized through incorporating notions of game theory into Fuzzy-MEBNs, and introducing Active Fuzzy-MEBN (ATFY-MEBN), which is capable in hypothesizing future situations by assessing the impact of the current situation upon taking the actions indicated by an optimal strategy. In fact, such strategies are achieved through solving the games that are generated through a novel situation-specific normal form games generation algorithm that aims to create games based on the given context. In general, ATFY-MEBN presents the concepts of players and actions, and includes new game components, along with a 2-tier architecture, to efficiently model impact assessment and decision making. To demonstrate the capabilities of the proposed framework, a collision warning system simulator is developed, which evaluates the likelihood of a vehicle being in a near-collision situation using a wide variety of both local and global information sources available in the VANETs environment, and suggests an optimal action by assessing the impact of the current situation through generating and solving situation-specific games. Accordingly, first, the entities that highly influence the safety aspect, as well as both their casual and semantic relationships are identified. Next, an ATFY-MEBN-based model is presented, which allows for modeling these entities along with their relationships in specific contexts, assessing the current states of the situations of interest, predicting their future states, and finally suggesting optimal decision. Therefore, if the likelihood of being in a near-collision situation is determined to be high, and if the relevant situation-specific game is generated, then the impact of deciding on different combinations of actions that the game players take are calculated through a pre-fixed payoff function. Finally, the completed game is solved by finding its dominant strategy, that subsequently, results in proposing the optimal action to the driver. Our experimental results are divided into three main sections, through which we evaluate the capabilities of the traffic entity, situation, and impact assessment methods. Accordingly, the performance of the proposed cooperative localization approach is assessed by comparing its results with the ground truth solution and that of the other localization methods in various driving test cases. Moreover, two distinct single-vehicle and multi-vehicles categories of driving scenarios, as well as a novel hybrid MEBN inference, demonstrate the capabilities of the proposed traffic assessment model to efficiently achieve situation and threat assessment on the road. Finally, the impact assessment and decision making models are evaluated through two different scenarios of driving in highway and intersection that are formed with various number of player vehicles, and their actions

    Lessons in project management

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    The conventional view of project management is challenged by a contemporary construction industry that is rethinking its processes and procedures as it seeks to align itself with clients' business needs. Project managers must update their skills. They require flexible education and training that complements work place experience rather than distracts from professional obligations. Educational technology offers an exciting opportunity to accommodate these, often conflicting, requirements. Computer-aided learning (CAL) is supported by a government keen to promote a Learning Society, the expansion of Higher Education (HE) postgraduate provision and the construction industry's own initiatives to engender a culture of lifelong learning. Enthusiasts argue that CAL provides greater access, enhances quality and overcomes the inherent disadvantages of distance learning. Yet the apparent eagerness to develop innovative CAL applications is not evidenced in an educational survey of built environment postgraduate course provision. On the contrary, only small pockets of CAL activity are available. A new distance learning project management educational software application (DIMEPM) is developed and compared with a traditional multiple media resource and a well-established postgraduate module delivered in part-time mode. The design of DIMEPM draws on the expertise of experienced practitioners in HE and the views of leading academics in the field. Qualitative and quantitative approaches are employed in a longitudinal evaluation that assesses the relative learning gains, student attitude and confidence of HE students. And, in order to gain reaction from industry, DIMEPM is subjected to an illuminative evaluation within a leading engineering and project management consultancy. The research study finds no significant difference in the academic performance of students in the control and experimental groups. However, it is clear that technically orientated tasks lend themselves more readily to CAL than interpersonal skills. Distributed educational packages provide opportunities for enhancing distance learning but alternative pedagogic approaches are needed to encourage web-based dialogue and promote vicarious learning. Practitioners suggest that the distinction between these alternative delivery methods is artificial and that an integrated approach should be explored. Crucially, the research identifies considerable advantage in linking outcomes to delivery mechanisms and advocates the use of an "Associated Delivery" model

    Improvisation of deepwater weight distributed steel catenary riser

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    Master's thesis in Offshore technology : subsea technologyNowadays, oil and gas sources are found in deeper water depths and in more hostile environments. This results in the need for more advance technologies. Riser system is a key element in providing safety. Riser failure results in spillage or pollution and could endanger lives. Hence, it is important to establish a high degree of reliability for riser design. Steel catenary risers (SCRs) have been a preferred riser solution for deep-water field developments due to its simple engineering concept, cost effective, flexibility in using different host platform and flexibility in geographical and environmental conditions. Flexible riser, on the other hand, is limited by technical and economical reasons when it comes to deep water field. Larger diameter is required in deep water to increase collapse resistance due to high hydrostatic pressure. Consequently, increase in cost and limit the option of host platform. Alternatively, Hybrid riser is a robust design for deepwater and harsh environments. It is insensitive to motion induced fatigue. However, hybrid riser is considered to be an expensive solution because it comprises a number of complex components (buoyancy can, riser bundle, flex joint, etc). A number of SCRs have been installed worldwide over the past years and more to come in the future oil and gas explorations. However, there is no SCR that has been installed in deepwater with harsh environments to date. It is mainly because SCRs in harsh environments experience a great challenge due to large motions from host platform such as semi-submersibles and FPSOs. Therefore, significant design effort is required to prove that the SCRs could safely withstand environmental loads in harsh environments and the effects of deep water. The study investigates the feasibility of 10 inch production SCR for Offshore Norway in a 1000m water depth with SCR attached to a semi-submersible vessel. Conventional SCR was analyzed and found difficulty in meeting strength design criteria at the touch down point (TDP) and at the riser hang off location. From previous industry work, the weight variation along the riser length has demonstrated a remarkable improvement to SCR response, particularly at TDP. This study concentrates on fundamental aspects related to improvement from conventional SCR to weight distributed SCR. A number of insightful sensitivity analyses were performed in order to understand the correlation between the peak response and some fundamental parameters such as displacement, velocity and acceleration. Feasibility enhancement of present weight distributed SCR concept was also studied to provide more applicable SCR configuration solution. The study addresses global design considerations including analysis of strength and fatigue. Deepwater SCR Installation scheme was also discussed. The study concludes that there is significant improvement in SCR response from conventional SCR to weight distributed SCR concept. It also proves that even though the design of SCR in harsh environments and deep water is technically challenging, innovative solutions can be developed

    A multiple case study of high school perspectives making music with code in Sonic Pi

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    The purpose of this study was to investigate perceptions of high school students who made music with code in Sonic Pi. This qualitative multiple case study focused on individuals in an extracurricular club at a public charter high school who volunteered to participate on-site and remotely asynchronously via Canvas learning management system. This study was guided by five research questions, including: (1) What musical ideas, if any, do participants report learning or demonstrate through making music with code in Sonic Pi? (2) How does making music with code impact participants’ perceptions of their music making? (3) How does making music with code impact participants’ perceptions of their ability to learn to make music? (4) How does making music with code impact participants’ interest in music courses? (5) How does making music with code impact participants’ interest in computer science courses? Participants completed research study materials, including a series of tutorials for Sonic Pi. Data included answers to questionnaires and surveys, multimedia artifacts including the source code and exported audio of participants’ music making, and interviews of participants that were codified and analyzed in two cycles, utilizing descriptive coding, values coding, and longitudinal coding. Participants’ code and multimedia artifacts revealed a close alignment to the four properties of sound, including: pitch, duration, intensity/amplitude, and timbre. Participants’ artifacts revealed themes and demonstrated ideas extending beyond the four properties, including: form, non-traditional music notation, and randomization. Participants all agreed their coded artifacts are music. Additionally, participants’ varied responses about musicianship and composers suggests that making music is something anyone can engage in, regardless of how one identifies themself. All participants agreed that Sonic Pi is a useful tool for learning and understanding musical concepts and that Western staff notation is not required knowledge for making music. Participants’ interests in music or computer science courses were impacted by their prior experiences in music and/or coding. This study concludes with a discussion of themes based on the findings

    Understanding Acoustics

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    This open access textbook, like Rayleigh’s classic Theory of Sound, focuses on experiments and on approximation techniques rather than mathematical rigor. The second edition has benefited from comments and corrections provided by many acousticians, in particular those who have used the first edition in undergraduate and graduate courses. For example, phasor notation has been added to clearly distinguish complex variables, and there is a new section on radiation from an unbaffled piston. Drawing on over 40 years of teaching experience at UCLA, the Naval Postgraduate School, and Penn State, the author presents a uniform methodology, based on hydrodynamic fundamentals for analysis of lumped-element systems and wave propagation that can accommodate dissipative mechanisms and geometrically-complex media. Five chapters on vibration and elastic waves highlight modern applications, including viscoelasticity and resonance techniques for measurement of elastic moduli, while introducing analytical techniques and approximation strategies that are revisited in nine subsequent chapters describing all aspects of generation, transmission, scattering, and reception of waves in fluids. Problems integrate multiple concepts, and several include experimental data to provide experience in choosing optimal strategies for extraction of experimental results and their uncertainties. Fundamental physical principles that do not ordinarily appear in other acoustics textbooks, like adiabatic invariance, similitude, the Kramers-Kronig relations, and the equipartition theorem, are shown to provide independent tests of results obtained from numerical solutions, commercial software, and simulations. Thanks to the Veneklasen Research Foundation, this popular textbook is now open access, making the e-book available for free download worldwide. Provides graduate-level treatment of acoustics and vibration suitable for use in courses, for self-study, and as a reference Highlights fundamental physical principles that can provide independent tests of the validity of numerical solutions, commercial software, and computer simulations Demonstrates approximation techniques that greatly simplify the mathematics without a substantial decrease in accuracy Incorporates a hydrodynamic approach to the acoustics of sound in fluids that provides a uniform methodology for analysis of lumped-element systems and wave propagation Emphasizes actual applications as examples of topics explained in the text Includes realistic end-of-chapter problems, some including experimental data, as well as a Solutions Manual for instructors. Features “Talk Like an Acoustician“ boxes to highlight key terms introduced in the text
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