Software Defined Applications in Cellular and Optical Networks

abstract: Small wireless cells have the potential to overcome bottlenecks in wireless access through the sharing of spectrum resources. A novel access backhaul network architecture based on a Smart Gateway (Sm-GW) between the small cell base stations, e.g., LTE eNBs, and the conventional backhaul gateways, e.g., LTE Servicing/Packet Gateways (S/P-GWs) has been introduced to address the bottleneck. The Sm-GW flexibly schedules uplink transmissions for the eNBs. Based on software defined networking (SDN) a management mechanism that allows multiple operator to flexibly inter-operate via multiple Sm-GWs with a multitude of small cells has been proposed. This dissertation also comprehensively survey the studies that examine the SDN paradigm in optical networks. Along with the PHY functional split improvements, the performance of Distributed Converged Cable Access Platform (DCCAP) in the cable architectures especially for the Remote-PHY and Remote-MACPHY nodes has been evaluated. In the PHY functional split, in addition to the re-use of infrastructure with a common FFT module for multiple technologies, a novel cross functional split interaction to cache the repetitive QAM symbols across time at the remote node to reduce the transmission rate requirement of the fronthaul link has been proposed.Dissertation/ThesisDoctoral Dissertation Electrical Engineering 201

Brain Training and Meditation’s Effects on Memory in Subjects with Vascular Cognitive Impairment

Vascular Dementia (VaD) is an important public health concern, which causes significant morbidity and mortality amongst populations around the world. With the increases in average age of individuals and prevalence of cardiovascular risk factors, the incidence of vascular cognitive impairment (VCI) and VaD are on the rise. Most of this increase will come from cerebral small vessel disease (CSVD) as treatment for large vessel disease improves. Yet, very few interventions are recommended for CSVD beyond control of risk factors. In this thesis, we propose a non-pharmacological intervention, which we believe may address executive dysfunction in VCI due to CSVD. CSVD impairs functional frontal-subcortical connectivity and results in cognitive and functional impairments. Given the plasticity in these circuits, despite old age, cognitive training may be a good candidate for improving cognition in CSVD. However, previous studies have suffered from heterogeneity of pathologies in VCI by including both large and small vessel disease. Furthermore, they have often not considered the effects of anxiety and depression, which we aim to exclude from the study. Finally, these studies do not use validated composite scores as a primary endpoint and currently do not use any biomarkers to follow the progress of subjects. In this study, we aim to partially address these shortcomings and offer a more rigorous approach to cognitive training

QUANTIFYING CONSEQUENCES OF EXTERNALLY INDUCED FAILURES PROPAGATED THROUGH SYSTEMS DURING FUNCTIONAL SYSTEM DESIGN

Assessment of failure propagation and potential within complex systems is a field open for continued exploration in the arena of systems engineering. Risk assessment and failure modeling processes such as PRA, FTA, and FMEA/FMECA are more widely understood and utilized in industry, yet are not designed to fully address and objectively quantify the impact on systems when exposed to intentionally malicious attacks, particularly in early design stages where changes to system architectures are best effected. Further, current methods do not identify and standardize attack modes that are likely to affect systems during their life cycle. This work first defines “attacks” and discusses their difference from “failures.” The work then develops and discusses a hierarchical taxonomy of attack classes and mechanisms likely to affect a wide array of systems. Finally, it presents the Failure Path Length Method (FPLM) to quantify consequence on systems due to attacks on system functions by applying characteristics of those classified attacks to the functional architecture of a system. The author then implements the FPLM on a common EPS to verify applicability to realistic systems and objectively determine the consequence of an attack. The differences in consequence drive mitigating changes to the architecture of the EPS and validate the significant decision-making power provided to system designers by the proposed method during functional analysis and design.Lieutenant, United States NavyApproved for public release. Distribution is unlimited

Advances in the therapy of Alzheimer's disease: Targeting amyloid beta and tau and perspectives for the future

Worldwide multidisciplinary translational research has led to a growing knowledge of the genetics and molecular pathogenesis of Alzheimer's disease (AD) indicating that pathophysiological brain alterations occur decades before clinical signs and symptoms of cognitive decline can be diagnosed. Consequently, therapeutic concepts and targets have been increasingly focused on early-stage illness before the onset of dementia; and distinct classes of compounds are now being tested in clinical trials. At present, there is a growing consensus that therapeutic progress in AD delaying disease progression would significantly decrease the expanding global burden. The evolving hypothesis- and evidence-based generation of new diagnostic research criteria for early-stage AD has positively impacted the development of clinical trial designs and the characterization of earlier and more specific target populations for trials in prodromal as well as in pre- and asymptomatic at-risk stages of AD

Multi-Domain Surety Modeling and Analysis for High Assurance Systems

Engineering systems are becoming increasingly complex as state of the art technologies am incorporated into designs. Surety modeling and analysis is an emerging science that permits an engineer to qualitatively and quantitatively predict and assess the completeness and predictability of a design. Surety is a term often used in the Department of Defense (DoD) and Department of Energy (DOE) communities, which refers to the integration of safety, security, reliability and performance aspects of design. Current risk assessment technologies for analyzing complex systems fail to adequately describe the problem, thus making assessment fragmented and non-integrated. To address this problem, we have developed a methodology and extensible software tool set to address model integration and complexity for high consequence systems. The MultiGraph Architecture (MGA) facilitates multi-domain, model-integrated modeling and analyses of complex, high-assurance systems. The MGA modeling environment allows the engineer to customize the modeling environment to match a design paradigm representative of the actual design. Previous modeling tools have a point-defined model space that forms the modeler to work in less than optimal environments. Current approaches for the problem to be bounded and constrained by requirements of the modeling tool and not the actual design problem. In some small cases, this is only maximally adequate MM facilitates the implementation of a surety methodology, which is used to represent high assurance systems with respect to safety and reliability. Formal mathematical models am used to correctly describe design safety and reliability functionality and behavioral fictional and behavioral representations of the design w then analyzed using commercial-off-the-shelf tools

The Future Role of Strategic Landpower

Recent Russian aggression in Ukraine has reenergized military strategists and senior leaders to evaluate the role of strategic Landpower. American leadership in the European theater has mobilized allies and partners to reconsider force postures for responding to possible aggression against NATO members. Although Russian revisionist activity remains a threat in Europe, the challenges in the Pacific for strategic Landpower must also be considered. At the same time, the homeland, the Arctic, climate change, and the results of new and emerging technology also challenge the application of strategic Landpower. This publication serves as part of an enduring effort to evaluate strategic Landpower’s role, authorities, and resources for accomplishing the national strategic goals the Joint Force may face in the next conflict. This study considers multinational partners, allies, and senior leaders that can contribute to overcoming these enduring challenges. The insights derived from this study, which can be applied to both the European and Indo-Pacific theaters, should help leaders to consider these challenges, which may last a generation. Deterrence demands credible strategic response options integrated across warfighting functions. This valuable edition will continue the dialogue about addressing these issues as well as other emerging ones.https://press.armywarcollege.edu/monographs/1959/thumbnail.jp

Three-Dimensional Boundary Element Analysis of DElaminated Composite Structures with Attached Piezoelectric Patch

Sommario Gli elevati valori di resistenza e rigidezza specifica unitamente alla possibilità di gestire i percorsi di carico rendono tali materiali particolarmente indicati nella progettazione delle strutture aeronautiche. Il crescente interesse nell'uso dei materiali compositi trova anche la sua ragion d'essere nell'opportunità di realizzare pannelli di grandi dimensioni con un minor numero di giunzioni rivettate, il che implica una semplificazione del componente da realizzare e da luogo ad una riduzione sia dei tempi che dei costi di manifattura ed ispezione. Indipendentemente dai vantaggi visti, grande attenzione va posta nell'uso di tali materiali in strutture molto caricate, specialmente in presenza di discontinuità geometriche, quali fori o cutout, poichè in prossimità di tali discontinuità il materiale composito tende a delaminare. Il comportamento dei materiali compositi risulta quindi molto complesso specialmente in presenza di danneggiamenti, per tale motivo risulta necessario stabilire delle strategie di modellazione numerica per caratterizzare la risposta strutturale in prossimità delle suddette discontinuità. Va infatti evidenziato che il comportamento a frattura per le delaminazioni, diversamente da quanto avviene per cricche in mezzi omogenei, è caratterizzato usualmente da una compresenza dei tre modi elementari di frattura e che, inoltre, i campi di tensione e deformazione al fronte di delaminazione sono caratterizzati da un andamento oscillatorio, oltre che singolare, che si esplica, matematicamente, in una rappresentazione complessa sia dei campi di tensione e deformazione che dei fattori d'intensificazione delle tensioni (SIFs). La rappresentazione in termini di funzioni complesse dei campi al fronte di cricca è in realtà un artefatto matematico introdotto dall'ipotesi di meccanica della frattura elastico lineare. Ciò causa anche delle difficoltà nel calcolare in modo univoco gli angoli di fase tra i modi di frattura, poichè tutte le possibili definizioni degli angoli di fase, basati cioè sui rapporti tra componenti di tensione, di campo di spostamenti o dei SIFs, producono risultati non-convergenti e che dipendono dall'entità della discontinuità elastica all'interfaccia. In questa tesi si è sviluppato un approccio agli elementi al contorno per l'analisi 3D di cricche all'interfaccia tra mezzi anisotropi ricorrendo alla implementazione multi-dominio delle equazioni BEM per modellare sia solidi non omogenei come i laminati sia le superfici di frattura all'interfaccia tra le lamine. Per caratterizzare il comportamento a frattura delle delaminazioni si è implementato un metodo basato sull'integrale di chiusura della cricca, così da sfruttare direttamente la rappresentazione al contorno dei campi tensione e spostamento in prossimità del fronte di cricca. La caratterizzazione a frattura di una cricca all'interfaccia tra materiali diversi è ottenuta intermini di rateo di rilascio energetico totale G ed in termini degli angoli di fase e che caratterizzano il mix tra i modi di frattura e taglio e di apertura. In particolare, ipotizzando che l'influenza della discontinuità elastica all'interfaccia possa essere ritenuta trascurabile quando introdotta solo da una diversa orientazione delle fibre delle lamine contenenti la delaminazione, gli angoli di fase sono definiti come la tangente inversa della radice dei rapporti tra le componenti di rateo di rilascio energetico GII e GIII rispetto a quella associata al modo di apertura GI. L'analisi di una double cantilever beam (DCB) per varie lunghezze di delaminazione e diversi materiali ortotropi è presentata per validare l'approccio BEM e le ipotesi proposte e mostrare la versatilità degli strumenti numerici proposti studiando l'influenza della sequenza di laminazione sulla distribuzione tridimensionale dei parametri di frattura. Infine, dopo aver derivato un modello per sensori piezoelettrici prismatici, si studia una configurazione drop-ply, rappresentativa di una analisi Global/Local di delaminazione tra skin e stiffener, con un array di sensori incollati alla flangia dell'irrigidimento. L'obiettivo è quello di investigare la sensibilità del sensore piezoelettrico alla delaminazione e quindi la sua efficacia in un sistema aeronautico di monitoraggio della salute strutturale. L'obiettivo di questa tesi è quindi dare una approfondita conoscenza sull'efficacia di un nuovo strumento di analisi numerica di strutture aeronautiche in composito in presenza di delaminazioni. La ricerca bibliografica ha inoltre evidenziato come lo studio numerico dei problemi di frattura all'interfaccia tra materiali anisotropi sia condotto esclusivamente per mezzo del metodo degli elementi finiti, mentre il metodo degli elementi al contorno è usato solo per problemi piani e in ambito 3D solo per cricche all'interfaccia tra materiali isotropi o trasversalmente isotropi. Quindi, il presente lavoro è anche sviluppato per 'colmare la lacuna' nell'ambito della ricerca BEM sulla caratterizzazione 3D di cricche all'interfaccia tra materiali anisotropi. Inoltre, l'uso dell'integrale di chiusura di Irwin unitamente ad una soluzione agli elementi al contorno permette di modellare i problemi di frattura in mezzi omogenei usando semplicemente elementi al contorno regolari, poichè il prodotto tra tensioni e spostamenti risulta finito anche al fronte di cricca. Quanto detto, unitamente all'ipotesi che il carattere oscillatorio dei campi di tensione e spostamento al fronte di cricca possa ritenersi trascurabile quando la discontinuità elastica è solo dovuta al diverso orientamento delle fibre suggerisce la possibilità di usare elementi regolari anche per modellare le delaminazioni. Ulteriore obiettivo del lavoro è quindi quello di verificare l'attendibilità dei risultati forniti usando il BEM 3D ad elementi regolari congiuntamente all'integrale di Irwin per il calcolo dei parametri di frattura per delaminazioni in strutture composite Abstract The high stiffness-to-weight and strength-to-weight ratios of composite materials as well as the path-loads management capability make these materials very suitable in the framework of aerospace structures. The increasing interest in using composite materials also finds its rationale on the advantages derived in manufacturing large size panels with less riveted joints, which leads to a reduction of the overall structural complexity and of the manufacturing and inspection times and costs. However, despite the aforementioned advantages, extreme caution must be taken in employing composite materials in highly loaded structures, especially if cutouts, holes or other geometric discontinuities are present, because these sites are prone to delamination onset and show high notch sensitivity. The behavior of such materials appears very complex, particularly in presence of damage, and therefore accurate and efficient numerical modeling strategies are needed to catch their structural response close to the discontinuities. It is to be stressed, in fact, that unlike fracture problems in homogeneous material, delamination cracks in laminate composites usually involve all three modes of fracture, and the crack tip stress and strain fields also exhibits oscillatory singular behavior which leads to complex stress and displacement fields representation as well as to complex valued stress intensity factors (SIFs). The complex nature of the stress and displacement fields close to the crack front is a mathematical artifact introduced by the linear elastic fracture mechanics theory. Moreover, it gives rise to the problem of the fracture mode phase angles Psi and Phi estimation, since the stresses, displacements and SIFs components based definition of the mode-mix generally lead to non-converging results depending on the entity of the bi-material interface discontinuity. This thesis deals with the modeling of three-dimensional fracture between two anisotropic layers using the boundary element method. The multi-domain technique is implemented to model the layered configuration and cracks occurring at the bi-material interface. For the purpose of characterizing the fracture behavior of the delamination, the crack closure integral is implemented, taking full advantage of the boundary element representation of the stress and displacement fields close to the crack front. The fracture mechanics behavior of bi-material cracks is characterized in terms of the total Strain Energy Release Rate G and the phase angles and , which provide information about the mix between the opening and the sliding and tearing modes of fracture, respectively. The mode mix phase angles are computed as the inverse tangent of the square root of the energy release rates opening GI and shearing, GII and GIII, components ratio, because the effect of the material discontinuity at the interface is considered negligible when it is only due to fibers orientation mismatch. A double cantilever beam (DCB) specimen is then modeled and studied for various orthotropic material and delamination length in order to validate the proposed approach and to investigate the influence of interface lay-up on the three-dimensional distribution of the fracture mechanic parameters. Last, a piezoelectric patch sensor bonded on a drop-ply configuration, which is representative of a skin-stiffener debonding in a Global/Local fashion, is analyzed. The study has the aim of assessing the piezoelectric device sensitiveness to delamination and its effectiveness for a typical aeronautical structural health monitoring system implementation. The main objective of this thesis is to develop a new effective numerical tool for obtaining a deeper insight in the fracture behavior of delaminated aircraft composite structures. Moreover numerical studies in the framework of interface crack between dissimilar anisotropic materials have been mostly addressed by using the finite element method. Contributions to this research using the boundary element method remains rare, particularly in the area of three-dimensional problem simulation. The BEM has been used to model 2D interface crack problems between distinct anisotropic material, whereas 3D BEM has been used to analyze interface crack by distinct isotropic materials or transversely isotropic materials. Thus, the present work is also developed to 'fill the gap' in the BEM research area on the subject of three-dimensional characterization of interface crack between distinct anisotropic materials. It is proved that the use of the Irwin's Crack Closure Integral in conjunction with the BEM solutions allows to model the crack front in a homogeneous medium simply by means of regular elements, since the product of stress and displacements represents energy which is finite everywhere in the body including the region next to the crack front. Moreover, the oscillatory behavior characterizing stress and displacements fields near the front of an interface crack can be assumed to be negligible when interface material mismatch is introduced by ply orientation only. Hence, another objective of the work is to validate as effective the proposed regular 3D Crack Closure BEM to compute fracture parameters for a delamination occurring in laminated composite structures