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1

Ball, Linden John. "Cognitive processes in engineering design." Thesis, University of Plymouth, 1990. http://hdl.handle.net/10026.1/674.

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The central aim of the current research programme was to gain an understanding of the cognitive processes involved in engineering design. Since little previous empirical research has investigated this domain, two major exploratory studies were undertaken here. Study One monitored seven final-year students tackling extended design projects. Diary and interview data were used to construct detailed design behaviour graphs that decomposed activities into structured representations reflecting the goals and subgoals that were pursued. Study Two involved individual observation (using video) of six professional engineers "thinking-aloud" as they tackled a small-scale design problem in a laboratory setting. A taxonomic scheme was developed to classify all verbal protocol units and other observable behaviours. In interpreting the data extensive use was made of theoretical concepts (e. g. schemas and mental models) deriving from current research on human problem solving and thinking. Evidence indicated that the engineers studied had many similar methods of working which could be described at a high level of abstraction in terms of a common "design schema". A central aspect of this schema was a problem reduction strategy which was used to break down complex design problems into more manageable subproblems. The data additionally revealed certain differences in design strategy between engineers' solution modelling activities and also showed up tendencies toward error and suboptimal performance. In this latter respect a particularly common tendency was for designers to "satisfice", that is to focus exclusively on initial solution concepts rather than comparing alternatives with the aim of optimising choices. The general implications of the present findings are discussed in relation to both the training of design skills and the development of intelligent computer systems to aid or automate the design process. A final, smaller scale of experimental study is also reported which investigated the possibility of improving design processes via subtle interventions aimed at imposing greater structure on design behaviours.
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2

Mazzuto, Giovanni. "Fuzzy Cognitive Maps tools for Industrial Engineering." Doctoral thesis, Università Politecnica delle Marche, 2014. http://hdl.handle.net/11566/242871.

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La tesi "Fuzzy Cognitive Maps tools for Industrial Engineering", riguarda la valutazione dell'applicazione di uno strumento quale la Mappa Cognitiva Fuzzy nell'ambito industriale. Ciò risiede nel fatto che, il suddetto strumento, nato nel settore delle scienze sociale, considera rilevante l'aspetto sociale ed umano associato ad un particolare problema. In tutti i problemi di ottimizzazione di un processo, o di risoluzione di un particolare problema, è possibile scegliere macchine che lavorino di più e meglio, oppure compiere azioni di correzione svariate, ma è necessario considerare che, chi lavora con tali macchine o esegue tali azioni è un individuo, soggetto a paure, insicurezze e stati d'animo differenti. Tutti aspetti che ne possono modificare le azioni comportamentali e di conseguenza anche la produttività. Con le Mappe Cognitive Fuzzy, si vuole quindi far interagire i diversi operatori nel processo decisionale di un'azienda. Punto focale di tale metodo è il lavoro in gruppi di esperti per l'identificazione e risoluzione di un dato quesito. Gruppo di esperti che deve, necessariamente, coprire tutte le aree di competenza associate al problema in questione. Ogni individuo ha modalità di approccio ad un problema in relazioni alle sue mansioni nello stesso. È proprio questa la potenza di tale strumento. La diversa astrazione mentale di un problema, condivisa con il gruppo, permette di evidenziare connessioni causali tra fenomeni, finora sconosciuti o conosciuti da pochi. Nell'elaborato presentato, tale strumento è stato impiegato per la gestione di quattro problemi differenti: Gestione del farmaco, Selezione dei fornitori, Analisi degli infortuni e Analisi criticità. In tutte e quattro le situazioni analizzate, gli esperti hanno individuato alcuni aspetti positivi della tipologia di approccio. Il coinvolgimento di tutti i livelli di operatività nel processo di decision making ha infatti prodotto una maggiore attenzione da parte degli operatori alla vita delle aziende prese in considerazione.
The proposed thesis highlighted the potential of cognitive maps in their explanatory and reflective functions and their value in support of decision making within organizations in a phase of any consolidation of the cognitive distances involved. Intelligent agents use mental models and have various “internal” processes (physical, mental, emotional) as they interact with other agents. Encourage group members to produce their own learning and cognitive maps represent their mental models that can have multiple functions in the formation, whether or not assisted by the network. The considered areas of study are characterized by complexity requiring the investigation of new advanced methods for modelling and development of sophisticated systems. In order to improve the communication between the different actors in relation to the factors, it becomes important to recognize that the mental models that characterize them influence the way they perceive the world and, consequently, the risks. The information collected through this analysis have been used both as a basis for the definition of strategies of risk communication, and as a guide for the negotiation process aimed at reducing existing levels of conflict and, at improving the mitigation measures to be taken. On the basis of the results obtained, it becomes important to encourage administrators to increase the dissemination of information about previous responsibilities relating to risk management, and the future ones relating to possible measures to be undertaken in a specific area. The proposed PhD thesis analyses some cases of study. It has been described the application of the FCM in the suppliers' selection sector, specifically, in the new product development process; in the analysis of injury events on workplace, where the social aspect has a great relevance; it has been analysed in order to define a new ranking method, in an Italian company, for defining a criticality indicator for the equipment and a proper maintenance program and, finally, the FCM has been applied in the Healthcare sector and, specifically, it has been used to define the main causes affecting the drug administration risk.
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3

Cox, David Daniel. "Reverse engineering object recognition." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/42042.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Brain and Cognitive Sciences, 2007.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Page 95 blank.
Includes bibliographical references (p. 83-94).
Any given object in the world can cast an effectively infinite number of different images onto the retina, depending on its position relative to the viewer, the configuration of light sources, and the presence of other objects in the visual field. In spite of this, primates can robustly recognize a multitude of objects in a fraction of a second, with no apparent effort. The computational mechanisms underlying these amazing abilities are poorly understood. This thesis presents a collection of work from human psychophysics, monkey electrophysiology, and computational modelling in an effort to reverse-engineer the key computational components that enable this amazing ability in the primate visual system.
by David Daniel Cox.
Ph.D.
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4

Pallotta, Vincenzo. "Cognitive language engineering towards robust human-computer interaction /." Lausanne, 2002. http://library.epfl.ch/theses/?display=detail&nr=2630.

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5

Tan, Kok Keng. "Cognitive Systems Engineering as an Ontology for Design." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1269531460.

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6

Thoms, Joanne. "Human centric systems engineering." Thesis, University of Bath, 2009. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.501636.

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This thesis is a study into an engineering technology that enables us to investigate the cognitive aspects of systems. Where previous techniques have focused on individual human roles undertaking defined tasks, this work develops engineering technologies to understand the cognitive contribution of the human team participating in the system and how the deployment of machine decision making technologies can influence and change the possible human contribution in that system. This work first develops a framework for understanding an individual’s cognitive focus and then an engineering process that enables us to model the individual human cognitive contribution to the system and by combining these models to create a rich system model. This model can then be used to consider the deployment of advanced machine technologies, to identify new human or machine interaction requirements that are focused on maintaining the effectiveness of the human contribution. It then operationalises and verifies these engineering techniques by applying them to two systems. The first study chosen took an existing system whose effectiveness had been changed by the deployment of machine automation which has known problems; the use of the framework enabled the prediction of these problems and the identification of potential solutions. The second study investigated an existing human system and the potential deployment of machine technology. This study used the framework to create models of the human cognitive focus and joined them together to form a rich system model, into which the deployment of the machine technology was considered. This resulted in the ability to identify the impact of the machine technology across the entire human team, enabling the identification of additional requirements to support the human cognition and to maintain human knowledge.
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7

Cardella, Monica E. "Engineering mathematics : an investigation of students' mathematical thinking from a cognitive engineering perspective /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/10692.

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8

Timmer, Peter Robin. "Expression of operator planning horizons : a cognitive engineering approach." Thesis, University College London (University of London), 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325012.

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9

Dowell, John. "Cognitive engineering and the rationalisation of the flight strip." Thesis, University College London (University of London), 1993. http://discovery.ucl.ac.uk/1350070/.

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10

Pinto, Nicolas. "Forward engineering object recognition : a scalable approach." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/62622.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Brain and Cognitive Sciences, 2011.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (p. 254-302).
The ease with which we recognize visual objects belies the computational difficulty of this feat. Despite the concerted efforts of both biological and computer vision research communities over the last forty years, human-level visual recognition remains an unsolved problem. The impact of a robust yet inexpensive solution would dramatically change computer science and neuroscience, unleashing a host of innovative applications in our modern society. In this thesis, we identify two operational barriers that have obstructed progress towards finding a solution { namely the lack of clear indicators and operational definitions of success, and the currently limited exploration of the staggeringly large hypothesis space of biologically- inspired solutions. To break down these barriers, we first establish new neuroscience-motivated baselines and new suites of fully-controlled benchmarks for object and face recognition. We also compare and contrast a variety of high-level visual systems, both artificial (state-of-the- art computer vision) and biological (humans). Then, we propose a simple high-throughput approach to undertake a systematic exploration of the biologically-inspired model class. By leveraging recent advances in massively parallel computing, we show that it is possible to generate a multitude of candidate models, screen them for desirable properties and discover robust solutions. Finally, we validate the scalability of our approach by showing its potential on large-scale real-world" applications. Taken together, this thesis represents a humble attempt towards an integrated approach to the problem of brain-inspired object recognition { spanning the engineering, specification, evaluation, and application of an interesting set of biologically-inspired ideas, driven and enabled by massively parallel technology. Even relatively early instantiations of this approach yield algorithms that achieve state-of-the-art performance in object recognition tasks and can generalize to other image domains. In addition, it offers insight into which computational ideas may be important for achieving this performance. Such insights can then be "fed back" into the design of new candidate models, constraining the search space and suggesting improvements, further guiding "evolutionary" progress. We hope that our results will point a new way forward, both in the creation of powerful yet simple computer vision systems and in providing insights into the computational underpinnings of biological vision.
by Nicolas Pinto.
Ph.D.
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11

Goodman, Katherine Ann. "The Transformative Experience in Engineering Education." Thesis, University of Colorado at Boulder, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3743651.

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This research evaluates the usefulness of transformative experience (TE) in engineering education. With TE, students 1) apply ideas from coursework to everyday experiences without prompting (motivated use); 2) see everyday situations through the lens of course content (expanded perception); and 3) value course content in new ways because it enriches everyday affective experience (affective value). In a three-part study, we examine how engineering educators can promote student progress toward TE and reliably measure that progress.

For the first study, we select a mechanical engineering technical elective, Flow Visualization, that had evidence of promoting expanded perception of fluid physics. Through student surveys and interviews, we compare this elective to the required Fluid Mechanics course. We found student interest in fluids fell into four categories: complexity, application, ubiquity, and aesthetics. Fluid Mechanics promotes interest from application, while Flow Visualization promotes interest based in ubiquity and aesthetics. Coding for expanded perception, we found it associated with students’ engineering identity, rather than a specific course. In our second study, we replicate atypical teaching methods from Flow Visualization in a new design course: Aesthetics of Design. Coding of surveys and interviews reveals that open-ended assignments and supportive teams lead to increased ownership of projects, which fuels risk-taking, and produces increased confidence as an engineer.

The third study seeks to establish parallels between expanded perception and measurable perceptual expertise. Our visual expertise experiment uses fluid flow images with both novices and experts (students who had passed fluid mechanics). After training, subjects sort images into laminar and turbulent categories. The results demonstrate that novices learned to sort the flow stimuli in ways similar to subjects in prior perceptual expertise studies. In contrast, the experts’ significantly better results suggest they are accessing conceptual fluids knowledge to perform this new, visual task. The ability to map concepts onto visual information is likely a necessary step toward expanded perception.

Our findings suggest that open-ended aesthetic experiences with engineering content unexpectedly support engineering identity development, and that visual tasks could be developed to measure conceptual understanding, promoting expanded perception. Overall, we find TE a productive theoretical framework for engineering education research.

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12

Coelho, Denis. "A growing concept of ergonomics including pleasure. comfort and cognitive engineering: an engineering design perspective." Doctoral thesis, Universidade da Beira Interior, 2002. http://hdl.handle.net/10400.6/660.

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The aim of this dissertation is to study and assess comfort, pleasure and cognitive engineering for relevance in engineering design processes, working towards finding an integrated theoretical structure. From this overall aim, operative aims and research questions were derived and pursued with the support of literature studies and analysis of five empirical studies. The operative aims are: establish the levels of scientific knowledge (in terms of development potential and feasibility); test the levels of development in practice of theoretical structures, data collection methods and representation formats; and, apply activity theory to attempt compatibilizing the three theoretical structures (broken down into subconcepts, operatives and measurable variables). Conclusions and conclusive remarks are delivered, springing from the analyses made. The results of the assessments of model validity and maturity showed that universal design methods in comfort, pleasure and cognitive engineering, for direct application by engineering design, are presently not available, with an exception found for thermal comfort. Predictability concerning seat comfort, cognitive engineering and pleasure with products has not yet been achieved, but it is deemed feasible for some of their sub-areas: modelling physical discomfort in sitting, modelling pleasurable product properties for cultural sub-groups and predicting patterns of the impact of change on joint cognitive systems. Other sub-areas are not considered worthwhile pursuing for attaining engineering systematization, since their predictability is not deemed attainable. This situation hence precludes the development of a complete integrated comfort, pleasure and cognitive engineering design method for unaided application by engineering design. In these areas, design problems are thus better tackled using a combined process of research and design, which recurs to the existing theoretical structures but also to context based research intended to fill in the gaps of theory. A moderate level of compatibility between the theoretical structures of comfort, pleasure and cognitive engineering was attained. While pleasure pursues in practice the goal of adding gains, comfort and cognitive engineering struggle in practice with relieving pain and minimizing loss. The psychological human aspect is common to all three areas, although it is not pursued in practice in comfort, nor does cognitive engineering pursue in practice the psychological aspect of emotions. Partial commonalities were found between comfort and pleasure (in what concerns physical aspects) and between cognitive engineering and pleasure (in what concerns psychological aspects) at the level of subconcepts. A common underlying activity structure of activity-goal-user-artefact was demonstrated for the empirical studies dealing with comfort and cognitive engineering. This showed, for both areas, that deriving measurable variables and identifying operatives could be done from the operation level of activity theory, once the elements relevant to the design problem are classified according to the activity-user-goal-artefact categories. Activity theory also enabled structuring and organizing a common research-design process underlying the conduction of specific design studies in comfort and cognitive engineering. This process is also suggested as applicable for designing Human Factors and Ergonomics quality wherever theory gaps are found.
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13

Grubbs, Michael Edwin. "Further Characterization of High School Pre- and Non-Engineering Students' Cognitive Activity During Engineering Design." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/70926.

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In response to STEM (science, technology, engineering, mathematics) educational reform, pedagogical approaches such as technological/engineering design-based learning (T/E DBL) have received increased emphasis as a means to enrich student learning and develop their higher-order cognitive competencies. Despite students exposure to the T and E of STEM as a means to make connections and improve learning (NAE and NRC, 2009), there still exists minimal evidence such experiences have a positive impact on their cognition and achievement (Honey, Pearson, and Schweingruber, 2014). Additionally, although research has well illustrated the design cognition of professional designers, and even students at the collegiate level, few investigations of high school students' cognitive activity during designing has been undertaken (Crismond and Adams, 2012; Hynes, 2012; Lammi and Becker, 2013). Furthermore, as researchers have begun to address this gap, broad coding schemes have been employed, describing students' cognitive efforts in terms of comprehensive categories such as formulation, analysis, and synthesis. However, as previous research has demonstrated nuances among existing categories (Purcell, Gero, Edwards, and McNeill, 1996), what has yet to be done is describe K-12 students' cognitive behaviors in terms of these underlying mechanisms. The purpose of this study was to characterize students' cognitive processes during engineering design at a more distinct level, which can increase understanding and begin to address the minimal attempts to 'connect research findings on how people design with what teachers need to understand and do to help K-16 students improve their design capability and learn through design activities" (Crismond and Adams, 2012, p. 738). The methodology of this study was informed by procedures of cognitive science and verbal protocol analysis. The primary form of data analyzed was audio and video recordings of the design task. The recorded data, in transcript form, was coded using the Purcell, Gero, Edwards, and McNeill (1996) framework. These coded data were then analyzed using descriptive and inferential statistics. Findings from this study revealed that significant differences existed between high school seniors who took pre-engineering courses, and those who did not when engaged in Consulting Information about the Problem (Cp) and in considering System issues, which examined the problem from the point of view of the user. Additionally, Proposing a Solution (Ps), Postponing a Design Action (Pd), and Looking Back (Lb) approached a value of statistical significance in differences between the groups of participants. Findings also characterized how students exert the most and least amount of their cognitive effort in relation to the Problem Domain: Degree of Abstraction and Strategy Classification coding schemes.
Ph. D.
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14

Dreany, Harry Hayes. "Safety Engineering of Computational Cognitive Architectures within Safety-Critical Systems." Thesis, The George Washington University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10688677.

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This paper presents the integration of an intelligent decision support model (IDSM) with a cognitive architecture that controls an autonomous non-deterministic safety-critical system. The IDSM will integrate multi-criteria, decision-making tools via intelligent technologies such as expert systems, fuzzy logic, machine learning, and genetic algorithms.

Cognitive technology is currently simulated within safety-critical systems to highlight variables of interest, interface with intelligent technologies, and provide an environment that improves the system’s cognitive performance. In this study, the IDSM is being applied to an actual safety-critical system, an unmanned surface vehicle (USV) with embedded artificial intelligence (AI) software. The USV’s safety performance is being researched in a simulated and a real-world, maritime based environment. The objective is to build a dynamically changing model to evaluate a cognitive architecture’s ability to ensure safe performance of an intelligent safety-critical system. The IDSM does this by finding a set of key safety performance parameters that can be critiqued via safety measurements, mechanisms, and methodologies. The uniqueness of this research lies in bounding the decision-making associated with the cognitive architecture’s key safety parameters (KSPs). Other real-time applications (RTAs) that would benefit from advancing cognitive science associated with safety are unmanned platforms, transportation technologies, and service robotics. Results will provide cognitive science researchers with a reference for the safety engineering of artificially intelligent safety-critical systems.

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15

Schmidt, Ludger [Verfasser]. "Ein Cognitive-Engineering-Ansatz zur Unterstützung der Produktentwicklung / Ludger Schmidt." Aachen : Shaker, 2004. http://d-nb.info/1172610339/34.

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16

McMeekin, David Andrew. "A software inspection methodology for cognitive improvement in software engineering." Thesis, Curtin University, 2010. http://hdl.handle.net/20.500.11937/400.

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This thesis examines software inspections application in a non-traditional use through examining the cognitive levels developers demonstrate while carrying out software inspection tasks. These levels are examined in order to assist in increasing developers’ ability to understand, maintain and evolve software systems.The results from several empirical studies carried out are presented. These indicate several important findings: student software developers find structured reading techniques more helpful as an aid than less structured reading techniques, while professional developers find the more structured techniques do not allow their experience to be applied to the problem at hand; there is a correlation between the effectiveness of a software inspection and an inspector’s ability to successfully add new functionality to the inspected software artefact; the cognitive levels that student developers functioned at while carrying out software inspection tasks were at higher orders of thinking when structured inspection techniques were implemented than when unstructured techniques were applied.From the empirical results a mapping has been created of several software inspection techniques to the cognitive process models they support and the cognitive levels, as measured using Bloom’s Taxonomy that they facilitate. This mapping is to understand the impact carrying out a software inspection has upon a developer’s cognitive understanding of the inspected system.The knowledge and understanding of the findings of this research has culminated in the creation of a code reading methodology to increase the cognitive level software developers operate at while reading software code. The reading methodology distinguishes where in undergraduate and software developer training courses different software inspection reading techniques are to be implemented in order to maximise a software developer’s code reading ability dependent upon their experience level.
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17

Mora, Sánchez Aldo. "Cognitive brain-computer interfaces : From feature engineering to neurophenomenological validation." Electronic Thesis or Diss., Sorbonne université, 2018. http://www.theses.fr/2018SORUS217.

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Cette thèse vise à décrire la conception, la mise en œuvre et la validation des interfaces cerveau-machine cognitives (ICMc). Le chapitre 1 introduit les ICMc et la métastabilité cérébrale. Dans le chapitre 2, une fonction cognitive spécifique (la mémoire de travail) est sélectionnée pour construire une ICMc. Dans le chapitre 3, nous explorons l'utilisation des propriétés spatio-temporelles de la dynamique cérébrale pour construire des biomarqueurs pour les ICMc, et nous abordons des questions scientifiques concernant la métastabilité cérébrale induite par la cognition. L’ICMc décrite au chapitre 2 surveille la charge de la mémoire de travail (MT) en temps réel et de façon continue. Les applications peuvent aller de l’apprentissage à la sécurité dans des environnements industriels. À notre connaissance, il s'agit de la première recherche sur les ICMc dans laquelle différents éléments clés sont simultanément inclus: des tests en temps réel, une tâche croisée, un démêlage des facteurs de confusion moteurs et cognitifs, et une validation neurophénoménologique. Dans le chapitre 3, nous développons un cadre empirique pour étudier la structure spatio-temporelle des changements d'états cérébraux issus de la cognition, avec deux objectifs spécifiques. Premièrement, d’identifier et d’utiliser des patrons d’activité cérébrale induits par la cognition comme descripteurs dans les ICMc. Deuxièmement, d’investiguer comment le cerveau s'auto-organise pour permettre à différentes régions de s'engager et de se désengager dans le cadre de la cognition. Nous proposons et validons comme biomarqueurs un ensemble de variables affectées spatialement et temporellement par des états cognitifs
This thesis aims at describing in detail the design, implementation and validation of cognitive brain-computer interfaces (cBCI). Chapter 1 introduces cBCI design and brain metastability. In Chapter 2, a specific cognitive function (Working Memory) is selected for the construction of a cBCI. In Chapter 3, we explore the use of spatio temporal properties of brain dynamics as biomarkers for cBCIs, and we address scientific questions concerning cognition-driven brain metastability. The BCI described in Chapter 2 continuously monitors Working Memory (WM) load in real-time. It relies on spectral properties of EEG as biomarkers. The applications may range from improved learning to security in industrial environments. To our knowledge, this represents the first cBCI research in which different key elements are included simultaneously: real-time tests, a cross-task, disentanglement of motor and cognitive confounders and neurophenomenological validation. In Chapter 3, we develop a data-driven framework for studying the spatio temporal structure of brain state switches under cognition, with two specific objectives. First, to identify and utilise patterns of brain activity elicited by cognition as descriptors in cBCIs. Second, to investigate how the brain self-organizes allowing different regions to engage and disengage in joint activity in a manner driven by cognition. Assuming brain metastability (in the context of statistical physics), we propose a set of local variables that are expected to be spatially and temporarily affected by cognitive states. We correlate these variables with cognitive conditions, such as high-WM load, Alzheimer disease, and positive emotional valence
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18

Mattaparthy, Jaya Vinay. "Cognitive work analysis for design of instructional practice in engineering education." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2008. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.

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19

Balakrishnan, Gautam. "Cognitive radio cooperative spectrum sensing." Thesis, California State University, Long Beach, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10252432.

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The effectiveness of a cognitive radio (CR) system depends mainly on involved spectrum sensing techniques. The main aim of CR is for effective utilization of the spectrum opportunistically by sharing it with secondary users (SUs), when the primary user (PU) is absent. In this project, cooperative spectrum sensing using weights based on the distance measures from the PU and Multitaper Method (MTM) method is briefly explained. The results show that MTM method provides more accurate threshold value compared to other methods for low signal to noise ratios (SNRs), hence improving the spectrum sensing technique. The results also show that MTM method requires a lesser number of Orthogonal Frequency Division Multiplexing (OFDM) sub-blocks compared to Periodogram (PE) for the same performance.

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20

Uden, Lorna. "A courseware engineering methodology for technology-based learning." Thesis, Staffordshire University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310576.

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21

Adams, Robin S. "Cognitive processes in iterative design behavior /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/7631.

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Zayour, Iyad. "Reverse engineering: A cognitive approach, a case study and a tool." Thesis, University of Ottawa (Canada), 2002. http://hdl.handle.net/10393/6075.

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Software maintenance (SM) for large legacy systems is a very inefficient process; on average, 70% of software costs are spent on maintenance [Swanson 89]. The inefficiency of SM has been related to the difficulty comprehending software systems; therefore program comprehension is considered to be a key bottleneck of SM. Reverse engineering tools have been used to alleviate this bottleneck with lower than expected success. We present a cognitively based approach for reverse engineering tool development. We use ideas from cognitive psychology and other disciplines to formulate the approach. We also describe a case study in which we applied the approach in a telecommunication company. The case study resulted in the development of DynaSee, a reverse engineering tool which helps software engineers analyze dynamic program information. DynaSee reads routine call traces, and provides several processing and visualization features that make the use of traces much more useful for software maintenance and program comprehension. Next, we describe and evaluate the various features of DynaSee that compress, abstract and augment traces to make them comprehensible and useful for SM tasks. Finally, based on our experience in developing DynaSee, we generalize the aspects of our findings and techniques that are based on psychology by relating them to the mainstream psychological literature and to other disciplines where similar techniques have been used.
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23

McWhirter, Nathan Daniel. "Teaching Engineering Students About Cognitive Barriers During Design for Sustainable Infrastructure." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/81310.

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Sustainability is a complex socio-technical challenge that requires new ways of thinking. To help meet this challenge, I have created three case-based modules that teach engineering students how to apply sustainability principles and help them recognize potential cognitive traps, or barriers, that may prevent more consideration for sustainability during design. Each of my three case studies is built into a PowerPoint-guided module for undergraduate engineering classes, which may be taught in 1-3 class days. I have implemented each of the three modules in senior-level classes at Virginia Tech, assessed survey data, and scored student assignments. This work and the underlying literature background is reflected in three journal papers, one for each module. My case study modules, along with all associated teaching materials, are shared in the Center for Sustainable Engineering repository for other instructors to adapt and use. Each module includes a case study about an infrastructure project recognized and awarded by the Envision rating system, demonstrating a case of sustainability done well. Adaptable PowerPoint slides are used to teach about the Envision rating system and credits particularly relevant to the project. Active learning assignments allow students to apply the Envision framework and design criteria to complex and ill-structured problems related to the case study. Slides also cover the relation of three selected behavioral decision science concepts to each case study; these include cognitive biases and barriers which tend to inhibit sustainability outcomes, as well as some potential solutions to mitigate or overcome such barriers. Paired with the decision-making framework of Envision, awareness of these transdisciplinary concepts will allow students to more effectively manage the complex decisions found in real-world projects. Results were assessed through a variety of methods to determine the modules' level of effectiveness in accomplishing defined student learning outcomes. Pre-module and post-module student surveys were employed to measure several indicators: changes in self-assessed confidence levels, perceptions of sustainable design (characteristics and barriers), and accuracy of module concept definitions. Each of several active learning assignments was scored on a simple rubric. Concept maps were also tested as further type of assessment, and scored with both traditional and holistic methods. However, fully integrating the concept mapping approach is left to the future work of others. These modules are a significant contribution to engineering education, as they integrate diverse topics and disciplines into a unified and relevant teaching package. Over 350 students have already been reached through the three modules, and sharing the materials in a peer-reviewed repository allows for expansion, adaptation, and capacity building. Each module's content and pedagogy align with ABET accreditation requirements and ASCE's Body of Knowledge, making them relevant tools for equipping the future generation of engineers. Future development of similar case studies can build partnerships between academia and industry, as well as increase cross-disciplinary collaboration. These efforts will both improve undergraduate education and advance the profession.
Master of Science
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24

Scott, David (David Arthur). "Interrogation of CRISPR-Cas targeting specificity for mammalian genome engineering." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/113958.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Brain and Cognitive Sciences, February 2017.
Cataloged from PDF version of thesis. "February 2017."
Includes bibliographical references (pages 134-138).
Class II CRISPR-Cas RNA programmable DNA endonucleases enable high efficiency genome editing across the biological diversity for research, industrial, and biomedical applications. Human genome editing with CRISPR-Cas just recently made its debut in human clinical trials and has immense therapeutic potential to fix disease-causing mutations at the level of DNA. Ensuring the integrity and safety of research, industrial, and biomedical applications of CRISPR-Cas necessitates efficient, versatile, and comprehensive methods to evaluate of the specificity of genome editing. Here, we optimize the efficiency and characterize the targeting specificity of SpCas9 to ensure robust cleavage activity while minimizing off-target activity in human cells. We characterize SpCas9 mismatch tolerance between the guide RNA and target, and provide data-driven design software to guide the selection of high fidelity Cas9 targets. We find that SpCas9 binding activity is not predictive of DNA cleavage, limiting the efficacy of Cas9 ChIP for unbiased evaluation of Cas9 off-target activity. Alternatively, we demonstrate that insert capture - insertion of short DNA fragments at double strand breaks (DSBs) by non-homologous end-joining (NHEJ) - provides unbiased genomewide identification of off-target cleavage by Cas9 as well as relative rates of indel, chromosomal rearrangement, and translocation accompanying NHEJ repair. However, insert capture is largely limited to use in model cell lines and is fundamentally limited in sensitivity due to labeling of low frequency errors in DSB repair. To directly label DSBs from cell culture or tissue samples, we adapted BLESS (direct in situ breaks labeling, enrichment on streptavidin and next-generation sequencing) and BLISS (Breaks Labeling In Situ and Sequencing) for unbiased genome-wide analysis of CRISPR-Cas specificity. Finally, we consider how human genetic variation will affect the targeting specificity of CRISPR-Cas endonucleases for therapeutic applications. Using the ExAC and 1000 Genomes datasets we find that human variation has important implications for Cas enzyme choice as well as target efficacy and safety. From this analysis, we provide a framework for the design of CRISPR-based therapeutics to maximize efficacy and safety across patient populations.
by David Scott.
Ph. D.
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25

Horine, Brent. "Bootstrapping Cognitive Radio Networks." Doctoral diss., University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5306.

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Cognitive radio networks promise more efficient spectrum utilization by leveraging degrees of freedom and distributing data collection. The actual realization of these promises is challenged by distributed control, and incomplete, uncertain and possibly conflicting knowledge bases. We consider two problems in bootstrapping, evolving, and managing cognitive radio networks. The first is Link Rendezvous, or how separate radio nodes initially find each other in a spectrum band with many degrees of freedom, and little shared knowledge. The second is how radio nodes can negotiate for spectrum access with incomplete information. To address the first problem, we present our Frequency Parallel Blind Link Rendezvous algorithm. This approach, designed for recent generations of digital front-ends, implicitly shares vague information about spectrum occupancy early in the process, speeding the progress towards a solution. Furthermore, it operates in the frequency domain, facilitating a parallel channel rendezvous. Finally, it operates without a control channel and can rendezvous anywhere in the operating band. We present simulations and analysis on the false alarm rate for both a feature detector and a cross-correlation detector. We compare our results to the conventional frequency hopping sequence rendezvous techniques. To address the second problem, we model the network as a multi-agent system and negotiate by exchanging proposals, augmented with arguments. These arguments include information about priority status and the existence of other nodes. We show in a variety of network topologies that this process leads to solutions not otherwise apparent to individual nodes, and achieves superior network throughput, request satisfaction, and total number of connections, compared to our baselines. The agents independently formulate proposals based upon communication desires, evaluate these proposals based upon capacity constraints, create arguments in response to proposal rejections, and re-evaluate proposals based upon received arguments. We present our negotiation rules, messages, and protocol and demonstrate how they interoperate in a simulation environment.
Ph.D.
Doctorate
Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering
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26

Miller, Janet E. "Critiquing as a cognitive task analysis methodology /." The Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1486402544588743.

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27

Lieder, Falk. "Beyond Bounded Rationality| Reverse-Engineering and Enhancing Human Intelligence." Thesis, University of California, Berkeley, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10817569.

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Bad decisions can have devastating consequences, and there is a vast body of literature suggesting that human judgment and decision-making are riddled with numerous systematic violations of the rules of logic, probability theory, and expected utility theory. The discovery of these cognitive biases in the 1970s challenged the concept of Homo sapiens as the rational animal and has profoundly shaken the foundations of economics and rational models in the cognitive, neural, and social sciences. Four decades later, these disciplines still lack a rigorous theoretical foundation that can account for people’s cognitive biases. Furthermore, designing effective interventions to remedy cognitive biases and improve human judgment and decision-making is still an art rather than a science. I address these two fundamental problems in the first and the second part of my thesis respectively.

To develop a theoretical framework that can account for cognitive biases, I start from the assumption that human cognition is fundamentally constrained by limited time and the human brain’s finite computational resources. Based on this assumption, I redefine human rationality as reasoning and deciding according to cognitive strategies that make the best possible use of the mind’s limited resources. I draw on the bounded optimality framework developed in the artificial intelligence literature to translate this definition into a mathematically precise theory of bounded rationality called resource-rationality and a new paradigm for cognitive modeling called resource-rational analysis. Applying this methodology allowed me to derive resource-rational models of judgment and decisionmaking that accurately capture a wide range of cognitive biases, including the anchoring bias and the numerous availability biases in memory recall, judgment, and decision-making. By showing that these phenomena and the heuristics that generate them are consistent with the rational use of limited resources, my analysis provides a rational reinterpretation of cognitive biases that were once interpreted as hallmarks of human irrationality. This suggests that it is time to revisit the debate about human rationality with the more realistic normative standard of resource-rationality. To enable a systematic assessment of the extent to which human cognition is resource- rational, I present an automatic method for deriving resource-rational heuristics from a mathematical specification of their function and the mind’s computational constraints. Applying this method to multi-alternative risky-choice led to the discovery of a previously unknown heuristic that people appear to use very frequently. Evaluating human decision-making against resource-rational heuristics suggested that, on average, human decision-making is at most 88% as resource-rational as it could be.

Since people are equipped with multiple heuristics, a complete normative theory of bounded rationality also has to answer the question of when each of these heuristics should be used. I address this question with a rational theory of strategy selection. According to this theory, people gradually learn to select the heuristic with the best possible speed-accuracy trade-off by building a predictive model of its performance. Experiments testing this model confirmed that people gradually learn to make increasingly more rational use of their finite time and bounded cognitive resources through a metacognitive reinforcement learning mechanism.

Overall, these findings suggest that—contrary to the bleak picture painted by previous research on heuristics and biases—human cognition is not fundamentally irrational, and can be understood as making rational use of bounded cognitive resources. By reconciling rationality with cognitive biases and bounded resources, this line of research addresses fundamental problems of previous rational modeling frameworks, such as expected utility theory, logic, and probability theory. Resource-rationality might thus come to replace classical notions of rationality as a theoretical foundation for modeling human judgment and decision-making in economics, psychology, neuroscience, and other cognitive and social sciences.

In the second part of my dissertation, I apply the principle of resource-rationality to develop tools and interventions for improving the human mind. Early interventions educated people about cognitive biases and taught them the normative principles of logic, probability theory, and expected utility theory. The practical benefits of such interventions are limited because the computational demands of applying them to the complex problems people face in everyday life far exceed individuals’ cognitive capacities. Instead, the principle of resource-rationality suggests that people should rely on simple, computationally efficient heuristics that are well adapted to the structure of their environments. Building on this idea, I leverage the automatic strategy discovery method and insights into metacognitive learning from the first part of my dissertation to develop intelligent systems that teach people resource-rational cognitive strategies. I illustrate this approach by developing and evaluating a cognitive tutor that trains people to plan resource-rationally. My results show that practicing with the cognitive tutor improves people’s planning strategies significantly more than does practicing without feedback. (Abstract shortened by ProQuest.)

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28

Tang, Liang. "Performance analyses and design for cognitive radios." Thesis, University of Warwick, 2012. http://wrap.warwick.ac.uk/56288/.

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Cognitive radio has been proposed as a promising solution to the conflict between the spectrum scarcity and spectrum under-utilization. As the demand increases for wireless communication services, cognitive radio technology attracts huge attention from both commercial industries and academic researches. The purpose of this thesis is to provide an analytical evaluation of the cognitive radio system performance while taking into consideration of some realistic conditions. Several problems are investigated in this thesis. First, by adopting a dynamic primary user traffic model with one primary user occupancy status change and exponentially distributed channel holding times, its effect on the cognitive radio system performance is evaluated. In the evaluation, the sensing-throughput tradeoff of the cognitive radio is used as the examination criteria, while energy detection is applied during the spectrum sensing. The thesis then takes the investigation further by establishing a primary user multiple changes traffic model which considers multiple primary user occupancy status changes and any reasonable channel holding time distributions. The effect of the primary user multiple changes traffic on the spectrum sensing performance is investigated while the channel holding times are assumed to be exponential, Gamma, Erlang and log-normal distributed. The analytical evaluation of cognitive radio is also carried out from the secondary user transmission perspective, where the performance of the adaptive modulation in cognitive radio system is investigated. The effect of the cognitive radio distinctive features on the performance of both the adaptive continuous rate scheme and the adaptive discrete rate scheme of the adaptive modulation are examined. The BER performance and the link spectral efficiency performance are derived for both schemes. A novel frame structure where the spectrum sensing is performed by using the recovered received secondary frames is also evaluated in this thesis. A realistic scenario which considers the secondary user signal decoding errors is examined for the novel structure, while an ideal upper bound performance is given when the decoding process is assumed perfect. By extending the system to include multiple consecutive secondary frames, the performance of the novel structure is compared to the performance of the traditional frame structure proposed by the IEEE 802.22 WRAN standard. The effect of the primary user multiple changes traffic is also examined for the novel structure. Several major findings are made from the analytical evaluations presented in this thesis. Through numerical examinations, it was shown that, first, the dynamic primary user traffic degrades the performance of cognitive radio systems. Second, the degree of the performance degradation of the cognitive radio systems is related to the number of primary user status changes and the primary user traffic intensity. Different primary user channel holding times distributions also lead to different sensitivities of the system performance to the primary user traffic. Third, cognitive radio distinctive features degrades the performance of the adaptive modulation. When the novel structure is applied for cognitive radio, a higher secondary achievable throughput can be obtained with a limited saturation threshold.
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29

Azmat, Freeha. "Machine learning and energy efficient cognitive radio." Thesis, University of Warwick, 2016. http://wrap.warwick.ac.uk/85990/.

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With an explosion of wireless mobile devices and services, system designers are facing a challenge of spectrum scarcity and high energy consumption. Cognitive radio (CR) is a promising solution for fulfilling the growing demand of radio spectrum using dynamic spectrum access. It has the ability of sensing, allocating, sharing and adapting to the radio environment. In this thesis, an analytical performance evaluation of the machine learning and energy efficient cognitive radio systems has been investigated while taking some realistic conditions into account. Firstly, bio-inspired techniques, including re y algorithm (FFA), fish school search (FSS) and particle swarm optimization (PSO), have been utilized in this thesis to evaluate the optimal weighting vectors for cooperative spectrum sensing (CSS) and spectrum allocation in the cognitive radio systems. This evaluation is performed for more realistic signals that suffer from the non-linear distortions, caused by the power amplifiers. The thesis then takes the investigation further by analysing the spectrum occupancy in the cognitive radio systems using different machine learning techniques. Four machine learning algorithms, including naive bayesian classifier (NBC), decision trees (DT), support vector machine (SVM) and hidden markov model (HMM) have been studied to find the best technique with the highest classification accuracy (CA). A detailed comparison of the supervised and unsupervised algorithms in terms of the computational time and classification accuracy has been presented. In addition to this, the thesis investigates the energy efficient cognitive radio systems because energy harvesting enables the perpetual operation of the wireless networks without the need of battery change. In particular, energy can be harvested from the radio waves in the radio frequency spectrum. For ensuring reliable performance, energy prediction has been proposed as a key component for optimizing the energy harvesting because it equips the harvesting nodes with adaptation to the energy availability. Two machine learning techniques, linear regression (LR) and decision trees (DT) have been utilized to predict the harvested energy using real-time power measurements in the radio spectrum. Furthermore, the conventional energy harvesting cognitive radios do not assume any energy harvesting capability at the primary users (PUs). However, this is not the case when primary users are wirelessly powered. In this thesis, a novel framework has been proposed where PUs possess the energy harvesting capabilities and can get benefit from the presence of the secondary user (SU) without any predetermined agreement. The performances of the wireless powered PUs and the SU has also been analysed. Numerical results have been presented to show the accuracy of the analysis. First, it has been observed that bio-inspired techniques outperform the conventional algorithms used for collaborative spectrum sensing and allocation. Second, it has been noticed that SVM is the best algorithm among all the supervised and unsupervised classifiers. Based on this, a new SVM algorithm has been proposed by combining SVM with FFA. It has also been observed that SVM+FFA outperform all other machine leaning classifiers Third, it has been noticed in the energy predictive modelling framework that LR outperforms DT by achieving smaller prediction error. It has also been shown that optimal time and frequency attained using energy predictive model can be used for defining the scheduling policies of the harvesting nodes. Last, it has been shown that wirelessly powered PUs having energy harvesting capabilities can attain energy gain from the transmission of SU and SU can attain the throughput gain from the extra transmission time allocated for energy harvesting PUs.
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30

Coral, Melissa Patricia. "Analyzing Cognitive Workload Through Eye-related Measurements: A Meta-Analysis." Wright State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=wright1464209028.

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31

Gellman, Michael. "Packet loss in the cognitive packet network." Honors in the Major Thesis, University of Central Florida, 2001. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/274.

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This item is only available in print in the UCF Libraries. If this is your Honors Thesis, you can help us make it available online for use by researchers around the world by following the instructions on the distribution consent form at http://library.ucf.edu/Systems/DigitalInitiatives/DigitalCollections/InternetDistributionConsentAgreementForm.pdf You may also contact the project coordinator, Kerri Bottorff, at kerri.bottorff@ucf.edu for more information.
Bachelors
Engineering
Computer Science
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32

Mäkeläinen, M. (Marko). "Algorithms for opportunistic load balancing cognitive engine." Master's thesis, University of Oulu, 2013. http://urn.fi/URN:NBN:fi:oulu-201303011071.

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Due to the increasing use of more and more powerful smart devices demands on the scarce radio spectrum are becoming more intense. One way to cope with increasing demands on radio spectrum is to apply innovative and flexible authorization schemes like spectrum sharing. Under the spectrum sharing paradigm, multiple users and/or systems are authorized to utilize the same spectrum band in a defined sharing agreement. A technology that is generally recommended for the implementation of spectrum sharing is called cognitive radio (CR). In this thesis, we design and implement a cognitive engine (CE) that intelligently and dynamically allocates spectrum resources to users. We first consider a scenario where a network has an exclusive access to a spectrum band and the CE accepts or rejects the arrival user requests based on an algorithm that takes into account a user’s priority and its bandwidth demand. We then consider a spectrum sharing scenario where along with the exclusive utilization to its own spectrum band a network also can opportunistically utilize another network’s spectrum band. For this scenario, we design and implement a CE that performs two main tasks: 1) Accepts or rejects arrival user requests based on a priority based algorithm; and 2) it intelligently load balances the user traffic between the two available network resources, while taking into account the primary user activity in the shared spectrum band. We provide a load balancing algorithm and evaluate its performance under different primary and secondary user traffic scenarios. We show that the proposed load balancing algorithm increases average throughput of the network and it also reduces the average number of users rejected by the network
Yhä tehokkaampien älykkäiden langattomien päätelaitteiden nopea lisääntyminen johtaa niukan radiospektrin yhä kiihtyvään käyttöön. Eräs menetelmä radiospektrin lisääntyvän kysynnän tyydyttämiseen on hyödyntää innovatiivista ja joustavaa resurssin käytönjakoa kuten spektrin jakamista. Spektrinjakamismalli mahdollistaa useiden käyttäjien ja/tai järjestelmien yhtäaikaisen käytön samalla taajuuskaistalla hyödyntämällä sovittua käytäntöä resurssien jakamisesta. Radiospektrin jakaminen on tänä päivänä yleisesti suositeltu toteuttamaan hyödyntämällä kognitiivista radioteknologiaa. Tässä työssä suunnittellaan ja toteutetaan kognitiivinen päätöksentekokone, joka jakaa radiospektriresursseja käyttäjille älykkäästi ja dynaamisesti. Kognitiivista päätöksentekokonetta radioresurssien jakamisessa hyödynnetään kahdessa skenaariossa. Ensimmäisessä skenaariossa radioverkolla on yksinomainen pääsy taajuuskaistalle, jonka käyttöä kognitiivinen päätöksentekokone säätelee joko hyväksymällä tai hylkäämällä verkkoon liittyviä käyttäjiä. Kognitiivinen päätöksentekokoneen päätökset perustuu algoritmiin, joka ottaa huomioon käyttäjien määritetyn tärkeyden ja käyttäjän vaatiman kaistanleveyden. Seuraavassa skenaariossa radioverkko voi oman yksinomaisen taajuuskaistan lisäksi hyödyntää opportunisesti toisen radioverkon taajuuskaistaa silloin, kun siellä ei ole liikennettä. Tätä skenaariota varten suunnitteltiin kognitiivinen päätöksentekokone, jolla on kaksi päätehtävää: 1) hyväksyä tai hylätä verkkoon liittyviä käyttäjiä edellämainitun tärkeysperusteisen algoritmin avulla; ja 2) jakaa käyttäjien liikennettä kahden tarjolla olevan verkon välillä samalla ottaen huomioon opportunistisen resurssin pääkäyttäjien liikenteen jaetulla taajuuskaistalla. Tässä työssä esitellään toteutettu kuormantasausalgoritmi, jonka suorituskykyä tarkastellaan erilaisissa pääkäyttäjien ja toissijaisien käyttäjien liikenneskenaarioissa. Simulaatiotulokset osoittavat, että esitellyn kuormanjakoalgoritmin hyödyntäminen kognitiivisessa päätöksentekokoneessa parantaa verkon keskimääräistä siirtonopeutta, sekä vähentää keskimääräistä käyttäjien hylkäysastetta verkossa. Algoritmimme parantaa opportunistisen taajuuskaistan käyttöastetta. Algoritmimme ottaa myös huomioon käyttäjille asetetut prioriteetit ja parantaa korkeampi prioriteettisten käyttäjien asemaa verkossa. Tämä tulee ilmi muun muassa korkeampi prioriteettisten käyttäjien pienemmässä hylkäysasteessa
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33

Khalil, Karim. "Cooperation and Competition in Cognitive Radio Networks." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1398771432.

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34

Liang, Wei. "Cooperative communication for cognitive radio networks." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/382935/.

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A Cooperative Cognitive Radio (CCR) network, which integrates a conventional cooperative system and cognitive radios (CRs) into a holistic system, is a promising paradigm for the next generation mobile communication systems. The spectral efficiency, power efficiency, bandwidth reduction and system complexity in CCR networks are the fundamental parameters of our system design and optimization. In this thesis, we focus our attention on opportunistically exploiting the underutilized spectrum band in the CR network with the aid of cooperative protocols. Furthermore, we invoke channel coding schemes in our CCR system in order to improve the overall system throughput. In our CCR system, the overlay based cooperation scheme of Primary Users (PUs) and Cognitive Users (CUs) is considered, which has the potential of leading to a transmission power reduction and transmission rate improvement for both the PU and the CU. More explicitly, our cooperative protocol allows a group of CUs to serve as Relay Nodes (RNs) for relaying the signal of the PUs’ transmitters to the PUs’ intended destinations. To elaborate further, both one way relaying and two-way relaying schemes are used in our proposed system, so that the bandwidth requirement of the PUs is reduced. Alternatively, the freed bandwidth may be leased to a group of CUs for their secondary communications. Our numerical and simulation results show that the bandwidth reduction attained by the proposed two-way relaying based CR scheme may approach as much as 80% of the PU’s bandwidth. Moreover, an Adaptive Dynamic Network Coding (ADNC) scheme is also conceived for this overlay CCR system, which is designed for supporting communications between multiple PUs and a common Base Station (BS). More particularly, the near-instantaneously Adaptive Turbo Trellis Coded Modulation (ATTCM) is employed for appropriately adjusting both the modulation mode as well as the channel coding rate and the network coding rate, according to the near-instantaneous channel conditions. In order to facilitate the recovery of the source information at the BS, the CUs invoke the ADNC technique, which is assisted by our cooperative protocol operating by exchanging the CCR-based control information between the near-instantaneously ATTCM and network coding codec as well as between the CUs and the BS. Additionally, the network encoder may also be activated in its adaptive mode for supporting the CUs, depending on the Boolean value of the feedback flags generated based on the success/failure of the ATTCMdecoder and of the network decoder, which is evaluated and fed back by the BS. Quantitatively, it was found that the joint holistic design of our ATTCM-ADNC-CCR scheme is either capable of freeing up an approximately 40% of the PU’s bandwidth in comparison to its non-cooperative counterpart, or increasing the attainable throughput by as much as 2 bit/symbol. Furthermore, a Pragmatic Distributed Algorithm (PDA) is proposed for supporting the efficient spectral access of multiple PUs and CUs in CCR networks. The novelty of our PDA is that the Pus negotiate with the CUs concerning the specific amount of relaying and transmission time, and the CU will decide either to accept or to decline this offer. These CUs relay the signal received from the PUs to the PUs’ receiver, but only when both the PUs’ and the CUs’ minimum rate requirements are satisfied. Moreover, we show that the cooperative spectral access based on our PDA reaches an equilibrium, when it is repeated for a sufficiently long duration. These benefits are achieved, because the PUs are motivated to cooperate by the incentive of achieving a higher PU rate, whilst defecting from cooperation can be discouraged with the aid of a limited-duration punishment. Therefore, our proposed PDA outperforms the benchmark, despite its significantly lower overhead and lower complexity. Finally, we present the joint design of coding, modulation, user-cooperation and CR techniques, which may lead to significant mutual benefits for both the PUs and the CUs.
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35

Shiferaw, Anteneh. "Cognitive techniques in smart system technologies." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/42588.

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36

Devapatla, Srikanth B. "Design and evaluation of a corrective measure for students' deficiencies in basic engineering calculus." Ohio : Ohio University, 1988. http://www.ohiolink.edu/etd/view.cgi?ohiou1182783509.

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37

Dadi, Gabriel B. "Applying Cognitive Principles to the Delivery of Engineering Information by Different Mediums." UKnowledge, 2013. http://uknowledge.uky.edu/ce_etds/10.

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Construction project performance and worker productivity are often tied to the availability and effective presentation of information, tools, materials, and equipment. While advancements in technology have improved much of the processes on a construction project, the medium of information dissemination at the construction work face has consistently relied on the use of two dimensional drawings and specifications. Industry initiatives are driving increased collaboration through three dimensional BIM (Building Information Modeling) models. However, the added dimension partially loses its effect when presented on a two dimensional computer monitor. Other computer forms of presentation intended for mobility (PDAs, laptops, and tablets) can be difficult to use in the field due to glare, durability in a harsh working environment, and the required skill level for effective use. Three dimensional (3D) physical printers now provide the capability to develop scaled and color models of a project directly from a BIM model. 3D physical printers represent a potential transformative change of providing engineering information to construction crews, but how to develop 3D models that leverage the cognitive benefits of viewing engineering information in a physical 3D form is unknown. The primary contribution to the overall body of knowledge of this dissertation is to scientifically examine the effect that different engineering information mediums have on an individual’s cognitive ability to effectively and accurately interpret spatial information. First, the author developed a robust scientific experiment for construction practitioners and students to complete. This experiment included outcomes measures on mental workload, cognitive demand, productivity, efficiency, demographics, and preferences. After collecting data, the author analyzed the outcomes through a series of statistical analyses to measure the differences between groups and quantify the affect and relationship among key variables. From the results, there are statistically significant improvements in productivity and efficiency of practitioners and students when using a physical model compared to two dimensional drawings and a three dimensional computer model. In addition, the average cognitive demand for a physical model was lower than the average cognitive demand for two dimensional drawings and three dimensional computer model.
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Zolynski, Gregor [Verfasser]. "Cognitive Maps for Autonomous Machines in Construction and Civil Engineering / Gregor Zolynski." München : Verlag Dr. Hut, 2018. http://d-nb.info/1162768185/34.

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39

Avnet, Mark Sean. "Socio-cognitive analysis of engineering systems design : shared knowledge, process, and product." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/52782.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Engineering Systems Division, 2009.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (p. 213-222).
This research is based on the well-known but seldom stated premise that the design of complex engineered systems is done by people -- each with their own knowledge, thoughts, and views about the system being designed. To understand the implications of this social dimension, the Integrated Concurrent Engineering (ICE) environment, a real-world setting for conceptual space mission design, is examined from technical and social perspectives. An integrated analysis demonstrates a relationship among shared knowledge, process, and product. The design process is analyzed using a parameter-based Design Structure Matrix (DSM). This model, consisting of 682 dependencies among 172 parameters, is partitioned (reordered) to reveal a tightly coupled design process. Further analysis shows that making starting assumptions about design budgets leads to a straightforward process of well-defined and sequentially executed design iterations. To analyze the social aspects, a network-based model of shared knowledge is proposed. By quantifying team members' common views of design drivers, a network of shared mental models is built to reveal the structure of shared knowledge at a snapshot in time. A structural comparison of pre-session and post-session networks is used to compute a metric of change in shared knowledge. Based on survey data from 12 design sessions, a correlation is found between change in shared knowledge and each of several system attributes, including technological maturity, development time, mass, and cost. Integrated analysis of design process and shared knowledge yields three interdisciplinary insights.
(cont.) First, certain features of the system serve a central role both in the design process and in the development of shared knowledge. Second, change in shared knowledge is related to the design product. Finally, change in shared knowledge and team coordination (agreement between expected and reported interactions) are positively correlated. The thesis contributes to the literature on product development, human factors engineering, and organizational and social psychology. It proposes a rigorous means of incorporating the socio cognitive aspects of design into the practice of systems engineering. Finally, the thesis offers a set of recommendations for the formation and management of ICE design facilities and discusses the applicability of the proposed methodology to the full-scale development of complex engineered systems.
by Mark Sean Avnet.
Ph.D.
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40

Foltz, Christian. "Cognitive Engineering zur Analyse und Gestaltung kreativ-informatorischer Arbeit in der Verfahrensentwicklung." Aachen Shaker, 2009. http://d-nb.info/999883844/04.

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41

Valieva, Inna. "Spectrum Sensing for Dynamic Spectrum Access in Cognitive Radio." Licentiate thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-52881.

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Abstract. The number of mobile devices is constantly growing, and the exclusivestatic spectrum allocation approach is leading to the spectrum scarcity problem whensome of the licensed bands are heavily occupied and others are nearly unused.Spectrum sharing and opportunistic spectrum access allow achieving more efficientspectrum utilization. Radio scene analysis is a first step in the cognitive radiooperation required to employ opportunistic spectrum access scenarios such as thedynamic spectrum access or frequency hopping spread spectrum. The objective of thiswork is to develop and virtual prototype the subset of radio scene analysis algorithmsintended to be used for deployment of opportunistic spectrum access in our targetapplication: a cognitive radio network consisting of multiple software-defined radionodes BitSDR. The proposed radio scene analysis algorithms are devoted to solvingtwo radio scene analysis problems: 1. detection of vacant frequency channels toimplement spectrum sharing scenarios; 2. waveform estimation including modulationtype, symbol rate, and central frequency estimation. From the subset of two radioscene analysis problems two hypotheses are formulated: the first is related to thevacant band identification and the second to waveform estimation. Then sevenresearch questions related to the trade-off between the sensing accuracy and real-time operation requirement for the proposed radio scene analysis algorithms, the nature of the noise, and assumptions used to model the radio scene environment such as the AWGN channel. In the scope of this work, Hypothesis 1, dedicated to vacant frequency band detection, has been proven. Research questions related to the selection of the observation bandwidth, vacant channels detection threshold, and the optimal algorithm have been answered. We have proposed, prototyped, and tested a vacant frequency channels detection algorithm based on wavelet transform performing multichannel detection in the wide band of 56 MHz based on the received signal observed during500 microseconds. Detection accuracy of 91 % has been demonstrated. Detection has been modeled as a binary hypothesis testing problem. Also, energy detection and cyclostationary feature extraction algorithms have been prototyped and tested, however, they have shown lower classification accuracy than wavelets. Answering research question 7 revealed the advantage of using wavelets due to the potential of the results of wavelet transform to be applied for solving the waveform estimation problem including symbol rate and modulation type. Test data samples have been generated during the controlled experiment by the hardware signal generator and received by proprietary hardware based on AD9364 Analog Devices transceiver. To test Hypothesis 2 research questions related to the waveform estimation have been elaborated. We could not fully prove Hypothesis 2 in the scope of this work. The algorithm and features that have been chosen for modulation type classification have not met the required classification accuracy to classify between five studied modulation classes 2FSK, BPSK, QPSK, 8PSK, and 16PSK. To capture more of the fine differences between the received signal modulated into different linear modulations it has been suggested to use the spectral features derived from the time-series signal observed during 500 microseconds or less observation time in the scope of the future work. However, the binary classification between 2FSK and BPSKpresented in Paper 1 could be performed based on instantaneous values and SNRinput: ensemble boosted trees and decision trees have shown an average classification accuracy of 86.3 % and 86.0 % respectively and classification speed of 1200000objects per second, what is faster than required 2000 objects per second.3The prototyping and testing of the proposed algorithm for symbol rate estimation based on deep learning have been performed to answer research question 2. Wavelet transform feature extraction has been proposed to be applied as a preprocessing step for deep learning-based estimation of the symbol rate for 2FSK modulated signals. This algorithm has shown an improvement in the accuracy of the symbol rate estimation in comparison with cyclostationary based detection. The validation accuracy of the symbol rate classification has reached 99.7 %. During testing, the highest average classification accuracy of 100 % has been observed for the signals with SNR levels 25-30 dB, while for signals with SNR 20-25 dB it was 96.3 %.
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42

Al-Saadi, Ahmed. "Cognitive network framework for heterogeneous wireless mesh systems." Thesis, Cardiff University, 2016. http://orca.cf.ac.uk/96622/.

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Heterogeneous wireless mesh networks (WMN) provide an opportunity to secure higher network capacity, wider coverage and higher quality of service (QoS). However, heterogeneous systems are complex to configure because of the high diversity of associated devices and resources. This thesis introduces a novel cognitive network framework that allows the integration of WMNs with long-term evolution (LTE) networks so that none of the overlapped frequency bands are used. The framework consists of three novel systems: the QoS metrics management system, the heterogeneous network management system and the routing decision-making system. The novelty of the QoS metrics management system is that it introduces a new routing metric for multi-hop wireless networks by developing a new rate adaptation algorithm. This system directly addresses the interference between neighbouring nodes, which has not been addressed in previous research on rate adaptation for WMN. The results indicated that there was a significant improvement in the system throughput by as much as to 90%. The routing decision-making system introduces two novel methods to select the transmission technology in heterogeneous nodes: the cognitive heterogeneous routing (CHR) system and the semantic reasoning system. The CHR method is used to develop a novel reinforcement learning algorithm to optimise the selection of transmission technology on wireless heterogeneous nodes by learning from previous actions. The semantic reasoning method uses ontologies and fuzzy-based semantic reasoning to facilitate the dynamic addition of new network types to the heterogeneous network. The simulation results showed that the heterogeneous network outperformed the benchmark networks by up to 200% of the network throughput.
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43

Vinter, Ricky Jay. "Evaluating formal specifications : a cognitive approach." Thesis, University of Hertfordshire, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268048.

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44

Alhanai, Tuka(Tuka Waddah Talib Ali Al Hanai). "Detecting cognitive impairment from spoken language." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122724.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2019
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 141-165).
Dementia comes second only to spinal cord injuries in terms of its debilitating effects; from memory-loss to physical disability. The standard approach to evaluate cognitive conditions are neuropsychological exams, which are conducted via in-person interviews to measure memory, thinking, language, and motor skills. Work is on-going to determine biomarkers of cognitive impairment, yet one modality that has been relatively less explored is speech. Speech has the advantage of being easy to record, and contains the majority of information transmitted during neuropsychological exams. To determine the viability of speech-based biomarkers, we utilize data from the Framingham Heart Study, that contains hour-long audio recordings of neuropsychological exams for over 5,000 individuals. The data is representative of a population and the real-world prevalence of cognitive conditions (3-4%). We first explore modeling cognitive impairment from a relatively small set of 92 subjects with complete information on audio, transcripts, and speaker turns. We loosen these constraints by modeling with only a fraction of audio (~2-3 minutes), of which the speaker segments are defined through text-based diarization. We next apply this diarization method to extract audio features from all 7,000+ recordings (most of which have no transcripts), to model cognitive impairment (AUC 0.83, spec. 78%, sens. 79%). Finally, we eliminate the need for feature-engineering by training a neural network to learn higher-order representations from filterbank features (AUC 0.85, spec. 81%, sens. 82%). Our speech models exhibit strong performance and are comparable to the baseline demographic model (AUC 0.85, spec. 93%, sens. 65%). Further analysis shows that our neural network model automatically learns to detect specific speech activity which clusters according to: pause followed by onset of speech, short burst of speech, speech activity in high-frequency spectral energy bands, and silence.
by Tuka Alhanai.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science
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45

Atasoy, Guzide. "Using Cognitive Maps For Modeling Project Success." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608545/index.pdf.

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In order to evaluate a project as successful or not, initially, the questions of &ldquo
what are the factors affecting the success&rdquo
and &ldquo
according to whom and which criteria should the success be measured&rdquo
should be answered. Both the factors and their influences vary depending on a project&rsquo
s specific characteristics, different environmental factors affecting it, and different parties involved. These factors are not independent of each other and the interrelationship between them should be investigated as a whole in order to model the project success. Moreover, parties involved in a project usually have different objectives and the performance indicators used to measure project success differ according to company priorities, preferences and attitudes. Thus, there exists a need to develop a project success model that contains the interrelationships between factors such as risks, decisions, and strategies, project success criteria, objectives and the relations of the factors with the objectives. A cognitive map (CM) is a strong visual tool to reflect the beliefs and knowledge of people about a situation or domain, identifying the causes, effects and the relations between them. This qualitative technique being enhanced by quantifiable properties makes it appropriate to be utilized to model the project success. As a result, the objective of this study is to demonstrate the application of CMs as a powerful tool for modeling project success. It is hypothesized that CMs can be effectively used to model the factors affecting success of a construction project, to reflect the interrelations between project success factors, to demonstrate the different objectives of parties involved in a project and show how the project success can be defined differently, by different parties. This technique is applied to a real construction project realized in Turkey. CMs of two consortium contractors and client organization involved in the project are constructed and the differences between the perceptions of three parties are revealed by content and structural analyses. Finally, the benefits and shortcomings of using CMs for modeling project success are discussed by referring to case study findings.
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46

Periola, Ayodele Abiola. "Efficient spectrum-handoff schemes for cognitive radio networks." Doctoral thesis, University of Cape Town, 2016. http://hdl.handle.net/11427/24443.

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Radio spectrum access is important for terrestrial wireless networks, commercial earth observations and terrestrial radio astronomy observations. The services offered by terrestrial wireless networks, commercial earth observations and terrestrial radio astronomy observations have evolved due to technological advances. They are expected to meet increasing users' demands which will require more spectrum. The increasing demand for high throughput by users necessitates allocating additional spectrum to terrestrial wireless networks. Terrestrial radio astronomy observations s require additional bandwidth to observe more spectral windows. Commercial earth observation requires more spectrum for enhanced transmission of earth observation data. The evolution of terrestrial wireless networks, commercial earth observations and terrestrial radio astronomy observations leads to the emergence of new interference scenarios. For instance, terrestrial wireless networks pose interference risks to mobile ground stations; while inter-satellite links can interfere with terrestrial radio astronomy observations. Terrestrial wireless networks, commercial earth observations and terrestrial radio astronomy observations also require mechanisms that will enhance the performance of their users. This thesis proposes a framework that prevents interference between terrestrial wireless networks, commercial earth observations and terrestrial radio astronomy observations when they co-exist; and enhance the performance of their users. The framework uses the cognitive radio; because it is capable of multi-context operation. In the thesis, two interference avoidance mechanisms are presented. The first mechanism prevents interference between terrestrial radio astronomy observations and inter-satellite links. The second mechanism prevent interference between terrestrial wireless networks and the commercial earth observation ground segment. The first interference reductionmechanism determines the inter-satellite link transmission duration. Analysis shows that interference-free inter-satellite links transmission is achievable during terrestrial radio astronomy observation switching for up to 50.7 seconds. The second mechanism enables the mobile ground station, with a trained neural network, to predict the terrestrial wireless network channel idle state. The prediction of the TWN channel idle state prevents interference between the terrestrial wireless network and the mobile ground station. Simulation shows that incorporating prediction in the mobile ground station enhances uplink throughput by 40.6% and reduces latency by 18.6%. In addition, the thesis also presents mechanisms to enhance the performance of the users in terrestrial wireless network, commercial earth observations and terrestrial radio astronomy observations. The thesis presents mechanisms that enhance user performance in homogeneous and heterogeneous terrestrial wireless networks. Mechanisms that enhance the performance of LTE-Advanced users with learning diversity are also presented. Furthermore, a future commercial earth observation network model that increases the accessible earth climatic data is presented. The performance of terrestrial radio astronomy observation users is enhanced by presenting mechanisms that improve angular resolution, power efficiency and reduce infrastructure costs.
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47

Faizan, Shah Ali. "SDN based security using cognitive algorithm against DDOS." Master's thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/29880.

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The internet and communication industry continue to develop new technologies rapidly, which has caused a boom in smart and networking device manufacturing. With new trends, operators are constantly battling towards deploying multiple systems to cater for the need of all users. The higher bandwidth utilization and flexibility demanded new networking solutions which paved way for Software Defined Network (SDN). SDN is centralized platform which works with other technologies such as Network Function Virtualization (NFV) to offer reliable, flexible and centrally controllable network solutions. It offers remote access control with logical design of the system, security and resource management. Traditional and new developing networks despite their advantages present numerous security challenges. With growing users worldwide, bandwidth related security risks such as Distributed Denial of Service (DDOS) are of grave concern. This encourages towards reliable and rapid response solutions such as Cognitive Algorithms (CA) which can adapt to a threat in real time environment. This dissertation proposes the use of CA to deploy security and mitigation measures against potential DDOS flooding attack to avoid network failure and memory depletion in SDN. The experiment done in proof of concept (PoC) provided proof of greater network resource utilization by limiting the attack while mitigation policies are implemented. It also shows that CA can adapt to growing and evolving network attack strength to counter as much as possible without the intervention of the operator. The work for future solutions based on CA and Artificial Intelligence (AI) for security have been established.
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48

Vakili, Arash. "Adaptive spectrum sensing for cognitive radio networks." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=106425.

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Spectrum sensing is an important functionality of cognitive radio as a means to detect the presence or absence of the primary user (PU) in a certain spectrum band. Energy detection is a widely used spectrum sensing technique based on the assumption that the PU is either present or absent during the whole sensing period. However, this assumption is not realistic in a dynamic environment where the PU could appear or disappear at any time. The performance of the conventional energy detector (ED) actually deteriorates in the scenario where the PU activity status changes during the sensing period.Therefore, it is crucial to design a detector which can adapt to such an environment and reliably detect a change in the PU activity. Several sequential change detection techniques already exist in the literature; however, change detection in a fixed sensing duration has not been given enough attention. In this dissertation, three adaptive EDs are proposed to improve the detection performance in dynamic environments, where there is a single change in the PU activity during a fixed sensing period. In particular, we address the change detection problem using an exponential weighting approach and two theoretical approaches based on the composite hypothesis testing. In the first case, an intuitive idea of exponential weighting of the received energies is applied to design an adaptive ED that aims to satisfy the Neyman-Pearson (NP) criterion. The performance analysis and simulation results prove that the proposed adaptive ED outperforms the conventional ED and also the only existing adaptive ED in the literature that deals with the aforementioned issue. In the second case, two theoretical approaches based on the composite hypothesis testing are used to design two additional adaptive EDs that improve the change detection during the sensing period. The first approach, known as the generalized likelihood ratio test (GLRT), uses the maximum likelihood estimation (MLE) of the unknown change location in a likelihood ratio test. In this case, an iterative method is proposed to reduce the computational complexity of the MLE process. The second approach, referred to as composite-Bayesian, assumes that the unknown change location is a discrete random variable whose probability mass function (PMF) is available. The PU channel access pattern is modelled as a two-state Markov chain to obtain the PMF of the change location and the probability of occurrence of the two hypotheses. The resultant adaptive ED based on the GLRT approach aims to satisfy the NP criterion while the adaptive ED based on the composite-Bayesian approach aims to minimize the probability of error. It is demonstrated through simulations that these two proposed adaptive EDs have superior performance over the conventional ED. Furthermore, the GLRT-based adaptive ED outperforms the first proposed adaptive ED based on the exponential weighting approach.
La détection de spectre est une fonctionnalité importante de la radio cognitive car elle permet de vérifier la présence ou l'absence d'un utilisateur principal (PU) sur une bande de spectre donnée. La détection de l'énergie est une méthode fréquemment utilisée pour y parvenir.Cette dernière s'appuie sur l'hypothèse que le PU est présent ou absent pour la totalité de la période de mesure. Cependant, cette hypothèse n'est pas réaliste pour un environnement dynamique dans lequel le PU peut apparaître ou disparaître à n'importe quel instant. En effet, les performances d'un détecteur d'énergie conventionnel (ED) se détériorent lorsque l'état du PU varie au cours de la période durant laquelle les mesures sont effectuées. C'est donc pour cette raison qu'il est nécessaire de concevoir un détecteurqui s'adapte bien à ce genre d'environnement et qui permet de détecter de manière fiable tout changement dans l'activité du PU. Plusieurs techniques de détection de changements séquentiels existent dans la littérature mais la détection de changement pour une durée fixe n'a pas été explorée suffisamment en détails. Dans le cadre de ce mémoire, trois EDs adaptatifs sont proposés dans le but d'améliorer les performances dans un environnement dynamique au sein duquel il y a un seul changement au niveau de l'activité du PU et ce durant une période de mesure de durée fixe. Pour tenter de résoudre cette problématique, une approche à pondération exponentielle et deux approches théoriques en lien avec le test d'hypothèse composée sont proposées. Dans le premier cas, une approche intuitive exploitant la pondération exponentielle de l'énergie mesurée est utilisée afin de concevoir un ED adaptatif qui satisfait le critère de Neyman-Pearson (NP). L'analyse des performances et des résultats de simulation prouvent que cette stratégie offre de meilleures performances par rapport aux ED conventionnels. Il s'agit également du seul ED adaptatif présent dans la littérature qui tente de résoudre la problématique précédemment mentionnée. Dans le second cas, deux approches théoriques fondées sur le test d'hypothèse composée sont utilisées afin de concevoir deux nouveaux EDs adaptatifs qui améliorent la détection de changements durant la période de mesure. La première approche s'appuie sur le test généralisé de vraisemblance (GLRT) et utilise une estimation de la vraisemblance maximale (MLE) de la position inconnue du changement. Dans ce cas, une méthode itérative est proposée pour réduire la complexité de calcul du processus de MLE. La deuxième approche, dite composée bayésienne, prend pour acquis que la position inconnue du changement est une variable aléatoire discrète dont la loi de probabilité (PMF) est connue. Pour cette dernière approche, les accès au canal sont modélisés par un modèle de Markov à deux états afin d'obtenir la PMF de la position du changement et la probabilité d'occurrence des deux hypothèses. Le ED adaptatif utilisant le GLRT tente de satisfaire le critère de NP tandis que le ED adaptatif utilisant l'approche de la composée bayésienne tente de minimiser la probabilité d'une erreur. Il est démontré à l'aide de simulations que ces deux EDs adaptatifs offrent des performances supérieures à celles du ED conventionnel. En outre, le ED adaptatif utilisant le GLRT surpasse le ED adaptive utilisant l'approche pondération exponentielle.
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49

Jia, Peng. "Spectrum-sensing threshold designs for cognitive radios." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=97121.

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This thesis presents a study of optimal threshold designs for energy-detection based spectrum sensing in a cognitive-radio network with a pair of Primary-User (PU) transmitter-receiver and a pair of Secondary-User (SU) transmitter-receiver uniformly distributed in their corresponding transmission and interference ranges. Both large-scale path-loss and small-scale fading are considered in the wireless channel model. At first, the optimization problems under three criteria: Risk Minimization, Cost Minimization, and Capacity Maximization are formulated for SU with narrowband sensing capability. Derived under Bayesian framework, Risk Minimization threshold aims to minimize the sum of the miss detection and false alarm probabilities while Cost Minimization threshold considers minimizing the losses in PU and SU link rates due to miss detection and false alarm. On the other hand, Capacity Maximization thresholds are derived to achieve the maximum weighted sum of the PU and SU link rates. The performance of the derived optimal sensing thresholds is investigated and compared in terms of the achieved PU, SU link rates, and the sum capacity of the network for different PU transmission activity factors. Advantages of knowledge of PU and SU locations are also evaluated. Illustrative results show that SU opportunistic capacity can be obtained at the costs of some degradation in the PU link rate. In the narrowband sensing case, the Bayesian-based Risk Minimization and Cost Minimization thresholds are found to be more PU-link protective (i.e., introduce less degradation in PU link rate, especially at high PU transmission activity factor) while Capacity Maximization threshold can achieve the highest sum capacity of the network. The optimal threshold designs for narrowband sensing are further examined to include the constraint on guaranteed minimum degradation in the achieved PU rate. Under this constraint, the advantage in protecting the PU link of the Bayesian-based thresholds is no longer useful, and Capacity Maximization threshold is the better choice as it offers higher SU link rate and sum capacity. Furthermore, the study of optimum sensing thresholds for three criteria and without and with constraint is extended to consider the case of SU with wideband sensing capability along with a spectrum access algorithm, aiming at reducing the miss detection probability. Results show that, compared to the narrowband sensing, for all three criteria, the wideband sensing approach offers much better SU and PU link rates over the whole range of PU transmission activity factor and the resulting sum rate increases monotonically with the number of subcarriers. It is also confirmed that, for wideband sensing, Capacity Maximization threshold again outperforms the Bayesian-based thresholds to meet a much more stringent constraint on guaranteed PU rates while providing better SU link rates and sum rates.
Ce mémoire présente une étude de la conception de seuils optimaux pour les méthodes de perception du spectre basées sur le test d'énergie dans un réseau de radio cognitive, dans lequel se trouve une paire émetteur-récepteur pour l'Utilisateur Primaire (PU) et une paire émetteur-récepteur pour l'Utilisateur Secondaire (SU) uniformément distribuées dans leurs plages de transmission et d'interférence respectives. L'affaiblissement de propagation et l'évanouissement à petite échelle sont tous deux considérés dans le modèle du canal sans fil. En premier lieu, les problèmes d'optimisation sont formulés pour le PU avec possibilité de perception du spectre en bande étroite selon trois critères: minimisation du risque, minimisation du coût et maximisation de capacité. Obtenus grâce à un cadre bayésien, le seuil de minimisation du risque cherche à minimiser la somme des probabilités de détection manquée et de fausse alerte tandis que le seuil de minimisation du coût considère les pertes de débit du PU et SU dues à la détection manquée et à la fausse alerte. En revanche, les seuils de maximisation de capacité sont dérivés pour atteindre la somme pondérée maximum de débit du PU et SU. La performance des seuils optimaux dérivés est enquêtée et comparée selon le débit atteint par le PU et SU, ainsi que la somme des débits du réseau pour différents facteurs d'activités de transmission pour le PU. Les avantages apportés par la connaissance de la localisation du SU sont aussi évalués. Les résultats illustratifs démontrent que la capacité opportuniste du SU peut être obtenue au détriment du débit du PU. Dans le cas d'écoute en bande étroite, les seuils bayésiens obtenus avec la minimisation du risque et la minimisation du coût protègent mieux le PU (i.e., introduisent moins de dégradation du débit du PU, en particulier lorsque le facteur d'activité du PU est élevé) tandis que les seuils de maximization de capacité peuvent atteindre la plus haute capacité combinée du réseau. La conception de seuils optimaux pour la perception du spectre en bande étroite est examinée d'avantage pour inclure la contrainte qui garantit la dégradation minimale du débit atteignable du PU. Avec cette contrainte, il n'est plus avantageux de protéger le lien du PU des seuils bayésiens, et le seuil de maximisation de capacité représente un meilleur choix puisqu'il offre un plus haut débit pour le SU ainsi qu'une capacité combinée augmentée. De plus, l'étude des seuils optimaux pour les trois critères, avec et sans contrainte, est étendue pour considérer le cas du SU avec possibilité de perception du spectre en bande large ainsi qu'un algorithme pour accéder au spectre, visant à réduire la probabilité de détection manquée. Les résultats démontrent que, comparée à la perception du spectre en bande étroite, la perception du spectre en bande large offre de meilleurs débits aux SU et PU sur toute la plage de facteurs d'activité du PU et le débit combiné est en augmentation monotonique avec le nombre de sous-porteurs. Il est aussi confirmé que, pour la perception du spectre en bande large, le seuil pour la maximisation de capacité est plus performant que les seuils bayésiens pour permettre une contrainte beaucoup plus stricte sur les débits guarantis au PU tout en fournissant de meilleurs débits au PU et SU.
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50

Lundqvist, Tomas. "Creating Resilience – A Matter of Control or Computation? : Resilience Engineering explored through the lenses of Cognitive Systems Engineering and Distributed Cognition in a patient safety case study." Thesis, Linköpings universitet, Institutionen för datavetenskap, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-102366.

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In recent years, the research approach known as Resilience Engineering (RE) has offered a promising new way of understanding safety-critical organizations, but less in the way of empirical methods for analysis. In this master’s thesis, an extensive comparison was made between RE and two different research approaches on cognitive systems: Distributed Cognition (DC) and Cognitive Systems Engineering (CSE) with the aim of exploring whether these approaches can contribute to the analysis and understanding of resilience. In addition to a theoretical comparison, an ethnographic healthcare case study was conducted, analyzing the patient safety at a pediatric emergency department using the Three-Level Analytical Framework from DC and the Extended Control Model from CSE, then conducting an RE analysis based on the former two analyses. It was found that while the DC and CSE approaches can explain how an organization adapts to current demands, neither approach fully addresses the issue of future demands anticipation, central to the RE perspective. However, the CSE framework lends itself well as an empirical ground providing the entry points for a more thoroughgoing RE analysis, while the inclusion of physical context in a DC analysis offers valuable insights to safety-related issues that would otherwise be left out in the study of resilience.
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