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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
461

The effect of using a computer-based exploration tool on children's career development learning

Crause, Ewald January 2013 (has links)
Historically the process of career development was thought of as occurring in adolescence and adulthood; however, the renewed emphasis on lifelong career development has led to a greater focus on the career developmental stage of childhood. The present research focused on the development and trialling of a research-based computerised career exploration tool, Growing-up: Children Building Careers™ (GCBC™) that can be used for early intervention in children‘s career development. The integration of developmental considerations within a career developmental context is of paramount importance, considering that child and career developmental theories share certain basic foundational principles such as the dual recognition of identifiable life stages and the resolution or accomplishment of associated tasks. The focus of the research is to provide access to a research-based tool that can assist learners with developing age appropriate career developmental skills. As the overview of education policy and existing programs will show, there are challenges in providing access to and improving the nature, level, and quality of career development services. Gaps in access to career development learning are particularly evident at the elementary education level. Furthermore it is clear that learners need to be at the centre of a radical rethink of careers services within a lifelong learning framework in order to ensure access to navigational tools throughout a lifetime of work and study transitions. Digital environments, such as the GCBC™, are tools that broaden and extend learning possibilities for children and appropriately designed digital environments can provide a vehicle that can take children further than they might travel unassisted. The research is divided into five phases and includes eight to ten year old children as participants. Phase one focused on the program design and pilot study (ensuring content validity and age-appropriate language use), while phases two to five focused on the fieldwork (i.e., pre –test, program exposure, post-test, and focus group discussions). The researcher made use of a mixed research design that combines both quantitative and qualitative research methods. The total sample consisted of 146 children between the ages of eight to ten years old. The control group had 72 children and the experimental group 74 children with a mean age of 8.74 years (SD = 0.63) for the total sample. The quantitative data collection entailed a pre-and post-test design with learners‘ career development measured with the Childhood Career Development Scale (CCDS) and their career awareness with the Revised Career Awareness Survey (RCAS). Qualitative data was collected in the form of two focus group discussions, which included a small sample of children from the experimental group, as well as insights gained from educators following the GCBC™ fieldwork. The quantitative statistical analysis included descriptive and inferential statistics which allowed the researcher to not only describe the research findings, but to confirm the effectiveness of the GCBC™ as an intentional career development learning program. Furthermore, the responses of the children and educators who participated in or witnessed the facilitation of the GCBC™ provided support for the GCBC™ as a meaningful career learning experience which can be successfully implemented in educational settings.
462

ON PERFORMANCE OF DYNAMIC NETWORK ORGANIZATIONS

Shahnewaz, Farhan 01 May 2014 (has links)
In this paper we have introduced a concept of analyzing the performance of dynamic network organization (NO) in response to multiple input objectives of network organization (NO) and input set of unpredictable external environment, and we have correlated plasticity of NO with this performance measure. A three stage conceptual model of the process has been described which comprised of dynamic system of multi-agent network, multiple objectives and input goals of network driver (S n), unpredictable external environment (ϵ). Dynamic system of the network organization takes through its two phase and processes this based on time and system response variables. Processing of input information by the system variables gives a ratio of system response variable and input. Further analysis is based on the value of this performance values. This model suggests a performance measuring technique which takes an input set of objectives from network driver of the NO, a set of input from external environment (ϵ) state and processes this input based on the existing state of the dynamic system in the NO. This process output shows dynamic system performance in dynamic environment and how this performance coefficient correlates with the Plasticity of network organization. We have presented several examples, mathematical models and graph by analyzing true scenarios on UAV patrolling zone.
463

The coevolution of the firm and the supply network : a complex systems perspective

Varga, Liz January 2009 (has links)
A complex adaptive systems approach has been permeating organizational studies and the field of supply network management helping to describe and explain supply network dynamics and emergent inter-firm structures. This has improved our theoretical knowledge of the nature of supply networks transforming raw materials into products, within a constantly changing environment. From the early days of simple structures, describing bi-lateral, local arrangements between firms for the creation of relatively simple products, we are now in an environment of various supply network archetypes, describing different global sourcing regimes of highly integrated, sophisticated products within multi-tier networks. This thesis is a study of the coevolution of the firm and supply network in the commercial aerospace manufacturing sector producing jetliners of 100 or more seats. One of the contributions of this research is to demonstrate how the holistic approach of complexity science can be applied to describe, understand and gain new insight into the coevolution of the firm and the supply network. Based on the findings of multiple interviews and questionnaires in eight global aerospace firms across multiple supply chain tiers, this research finds high-performing clusters of inter-firm characteristics, plus the aspects of structure and integration which deliver the supply network performance. Practitioners can use these specific results to examine their own firms and the new coevolutionary conceptual framework developed in the thesis may aid future research studies of complex adaptive systems in practice. The simple survey design and analysis method used in the final research stage of this research, has the potential for use in other industries, markets and other complex adaptive systems generally to examine performance outcomes and the effects of having or adopting new inter-firm characteristics. Finally, implications for policy include the potential to legitimize supply networks in order to stimulate competition and innovation in the economy.
464

Enhancing network robustness using software-defined networking

Li, Xin January 1900 (has links)
Doctor of Philosophy / Department of Electrical and Computer Engineering / Don M. Gruenbacher / Caterina M. Scoglio / As today's networks are no longer individual networks, networks are less robust towards failures and attacks. For example, computer networks and power networks are interdependent. Computer networks provide smart control for power networks, while power networks provide power supply. Localized network failures and attacks are amplified and exacerbated back and forth between two networks due to their interdependencies. This dissertation focuses on finding solutions to enhance network robustness. Software-defined networking provides a programmable architecture, which can dynamically adapt to any changes and can reduce the complexities of network traffic management. This architecture brings opportunities to enhance network robustness, for example, adapting to network changes, routing traffic bypassing malfunction devices, dropping malicious flows, etc. However, as SDN is rapidly proceeding from vision to reality, the SDN architecture itself might be exposed to some robustness threats. Especially, the SDN control plane is tremendously attractive to attackers, since it is the "brain" of entire networks. Thus, researching on network robustness helps protect network from a destructive disaster. In this dissertation, we first build a novel, realistic interdependent network framework to model cyber-physical networks. We allocate dependency links under a limited budget and evaluate network robustness. We further revise a network flow algorithm and find solutions to obtain a basic robust network structure. Extensive simulations on random networks and real networks show that our deployment method produces topologies that are more robust than the ones obtained by other deployment techniques. Second, we tackle middlebox chain problems using SDN. In computer networks, applications require traffic to sequence through multiple types of middleboxes to accomplish network functionality. Middlebox policies, numerous applications' requirements, and resource allocations complicate network management. Furthermore, middlebox failures can affect network robustness. We formulate a mixed-integer linear programming problem to achieve a network load-balancing objective in the context of middlebox policy chain routing. Our global routing approach manages network resources efficiently by simplifying candidate-path selections, balancing the entire network and using the simulated annealing algorithm. Moreover, in case of middlebox failures, we design a fast rerouting mechanism by exploiting the remaining link and middlebox resources locally. We implement proposed routing approaches on a Mininet testbed and evaluate experiments' scalability, assessing the effectiveness of the approaches. Third, we build an adversary model to describe in detail how to launch distributed denial of service (DDoS) attacks to overwhelm the SDN controller. Then we discuss possible defense mechanisms to protect the controller from DDoS attacks. We implement a successful DDoS attack and our defense mechanism on the Mininet testbed to demonstrate its feasibility in the real world. In summary, we vertically dive into enhancing network robustness by constructing a topological framework, making routing decisions, and protecting the SDN controller.
465

Design and Performance Analysis of Fiber Wireless Networks

January 2015 (has links)
abstract: A Fiber-Wireless (FiWi) network integrates a passive optical network (PON) with wireless mesh networks (WMNs) to provide high speed backhaul via the PON while offering the flexibility and mobility of a WMN. Generally, increasing the size of a WMN leads to higher wireless interference and longer packet delays. The partitioning of a large WMN into several smaller WMN clusters, whereby each cluster is served by an Optical Network Unit (ONU) of the PON, is examined. Existing WMN throughput-delay analysis techniques considering the mean load of the nodes at a given hop distance from a gateway (ONU) are unsuitable for the heterogeneous nodal traffic loads arising from clustering. A simple analytical queuing model that considers the individual node loads to accurately characterize the throughput-delay performance of a clustered FiWi network is introduced. The accuracy of the model is verified through extensive simulations. It is found that with sufficient PON bandwidth, clustering substantially improves the FiWi network throughput-delay performance by employing the model to examine the impact of the number of clusters on the network throughput-delay performance. Different traffic models and network designs are also studied to improve the FiWi network performance. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2015
466

An Evaluation of SDN Based Network Virtualization Techniques

January 2016 (has links)
abstract: With the software-defined networking trend growing, several network virtualization controllers have been developed in recent years. These controllers, also called network hypervisors, attempt to manage physical SDN based networks so that multiple tenants can safely share the same forwarding plane hardware without risk of being affected by or affecting other tenants. However, many areas remain unexplored by current network hypervisor implementations. This thesis presents and evaluates some of the features offered by network hypervisors, such as full header space availability, isolation, and transparent traffic forwarding capabilities for tenants. Flow setup time and throughput are also measured and compared among different network hypervisors. Three different network hypervisors are evaluated: FlowVisor, VeRTIGO and OpenVirteX. These virtualization tools are assessed with experiments conducted on three different testbeds: an emulated Mininet scenario, a physical single-switch testbed, and also a remote GENI testbed. The results indicate that network hypervisors bring SDN flexibility to network virtualization, making it easier for network administrators to define with precision how the network is sliced and divided among tenants. This increased flexibility, however, may come with the cost of decreased performance, and also brings additional risks of interoperability due to a lack of standardization of virtualization methods. / Dissertation/Thesis / Masters Thesis Engineering 2016
467

Threats and Defenses in SDN Control Plane

January 2018 (has links)
abstract: Network Management is a critical process for an enterprise to configure and monitor the network devices using cost effective methods. It is imperative for it to be robust and free from adversarial or accidental security flaws. With the advent of cloud computing and increasing demands for centralized network control, conventional management protocols like Simple Network Management Protocol (SNMP) appear inadequate and newer techniques like Network Management Datastore Architecture (NMDA) design and Network Configuration (NETCONF) have been invented. However, unlike SNMP which underwent improvements concentrating on security, the new data management and storage techniques have not been scrutinized for the inherent security flaws. In this thesis, I identify several vulnerabilities in the widely used critical infrastructures which leverage the NMDA design. Software Defined Networking (SDN), a proponent of NMDA, heavily relies on its datastores to program and manage the network. I base my research on the security challenges put forth by the existing datastore’s design as implemented by the SDN controllers. The vulnerabilities identified in this work have a direct impact on the controllers like OpenDayLight, Open Network Operating System and their proprietary implementations (by CISCO, Ericsson, RedHat, Brocade, Juniper, etc). Using the threat detection methodology, I demonstrate how the NMDA-based implementations are vulnerable to attacks which compromise availability, integrity, and confidentiality of the network. I finally propose defense measures to address the security threats in the existing design and discuss the challenges faced while employing these countermeasures. / Dissertation/Thesis / Masters Thesis Computer Science 2018
468

A communication system for a pluggable game engine

Sjöstrand, Johan January 2007 (has links)
This thesis documents the development of a communication system that is part of a pluggable game engine for a course in advanced game programming. It covers some techniques and problems in network game programming, a description of the developed system and an example of how the system is used in a demo of the game engine.
469

Comparação entre os tratamentos adjuvantes no pterígio primário ressecado: uma network metanálise / Comparison among adjuvant treatments for primary pterygium: a network metanalysis

Ellen Carrara Fonseca 07 April 2017 (has links)
O pterígio é uma degeneração benigna da conjuntiva, que se estende em direção à córnea e acomete principalmente adultos habitantes de regiões intertropicais. A prevalência mundial varia de 0,7 a 31%. A patogênese exata permanece incerta, mas evidências atuais sugerem a participação de fatores genéticos e ambientais, principalmente a exposição crônica à radiação ultravioleta. O tratamento pode ser clínico, com uso de colírios para melhora dos sintomas, ou cirúrgico. Até os anos de 1980, a técnica de ressecção do pterígio com manutenção de área de esclera nua era predominante, porém apresentava taxas muito elevadas de recidiva. Desde então, tem-se procurado técnicas adjuvantes a essa para obtenção de melhores resultados e redução do número de recorrência. O presente estudo busca, por meio de comparações diretas e indiretas da network metanálise, identificar qual, dentre as várias técnicas utilizadas, seria a melhor a ser empregada. Após pesquisa em bases de dados foram selecionados 24 ensaios clínicos randomizados, computando 1815 olhos em 1668 pacientes, sendo possível comparar os seguintes tratamentos adjuvantes à técnica de esclera nua: associação de 5-Fluorouracil (5-FU), Betaterapia, Mitomicina C (MMC) em diferentes concentrações e Ciclosporina, além de transplante de membrana amniótica (TMA) e enxerto conjuntival, também associado ao uso de Bevacizumab, MMC e Ciclosporina. Foi possível realizar comparações diretas entre os seguintes tipos de intervenções: esclera nua versus esclera nua + Ciclosporina gotas 0,05%, enxerto conjuntival versus esclera nua + MMC 0,02% intraoperatória, enxerto conjuntival versus transplante de membrana amniótica, esclera nua versus esclera nua + MMC 0,02% intraoperatória e esclera nua versus enxerto conjuntival, sendo considerados os melhores, respectivamente: esclera nua + Ciclosporina gotas 0,05%, enxerto conjuntival, enxerto conjuntival, esclera nua + MMC 0,02% e enxerto conjuntival. Em relação à network metanálise, o ranqueamento ordenado do melhor para o pior procedimento na redução de recidiva foi o seguinte: enxerto conjuntival + Ciclosporina gotas 0,05%, esclera nua associada à MMC < 0,02%, esclera nua + Betaterapia (dose única de 2500 cGy), enxerto conjuntival + Betaterapia (dose única de 1000 cGy), esclera nua + MMC gotas 0,02%, enxerto conjuntival, esclera nua + MMC > 0,02%, esclera nua + Ciclosporina gotas 0,05%, esclera nua + 5FU intraoperatório 5%, transplante de membrana amniótica, esclera nua + MMC 0,02%, enxerto conjuntival + Bevacizumab gotas 0,05%, esclera nua + Bevacizumab e esclera nua. Em conclusão, diante das inúmeras possibilidades de combinações de tratamento para o pterígio, foi possível se estabelecer, a partir das técnicas comparadas em estudos clínicos publicados e disponibilidade dos recursos em cada serviço, o tratamento com menor recidiva. / Pterygium is a benign conjunctival degeneration towards the cornea which affects mostly adults who live in the intertropical regions. World prevalence is between 0,7 and 31%. The exact pathogenesis remains unclear but it´s known that genetics and environmental factors may predispose to this condition, specially cronic exposure to ultraviolet radiation which can cause oxidative stress and increase growth factors production. Treatment can be simptomatic, with eye drops, or surgery can be performed. Until the 80´s pterygium ressection leaving an area of bare sclera was the main surgic procedure but it led to high rates of recurrency. Since then, adjuvants techniques have been studied in order to improve the results by decreasing recurrency rates. The aim of this paper is to try to identify, among several adjuvant procedures, which would be the best to avoid recurrency. To acomplish that we performed a network metanalisis. After critical search in data bases we selected 24 randomized clinical trials that included 1815 eyes of 1668 patients. We were able to compare the following adjuvant treatments to bare sclera technique: use of 5-Fluorouracil (5-FU), Bethaterapy, Mytomicyn C (MMC) in different concentrations, Cyclosporine, Amniotic Membrane Transplantation (AMT) and Conjunctival Autograft (CAG) alone or associated to Bevacizumab, MMC and Cyclosporine. The following direct comparisons were made: bar esclera versus bar esclera + Ciclosporyne eye drops 0.05%, conjunctival autograft versus bar esclera + intraoperative MMC 0.02%, conjunctival autograft versus amniotic membrane transplantation, bare sclera versus bar esclera + intraoperative MMC 0.02% and conjunctival autograft versus bare sclera with better results, respectivelly, in: bare sclera + Ciclosporyne 0.05% eye drops, conjunctival autograft, conjunctival autograft, bare sclera + MMC 0.02% and conjunctival autograft. Regarding the network metanalysis, the rank from best to worst treatment is: conjunctival autograft + Ciclosporyne eye drops 0.05%, bare sclera + MMC < 0.02%, bare sclera + Betatherapy (2500 cGy single dose), conjunctival autograft + Betatherapy (1000 cGy single dose), bare sclera + MMC 0.02% eye drops, conjunctival autograft, bare sclera + intraoperative MMC > 0.02%, bare sclera + Ciclosporyne eye drops 0.05%, bare sclera + intraoperative 5FU 5%, amniotic membrane transplantation, bare sclera + intraoperative MMC 0.02%, conjunctival autograft + Bevacizumab eye drops 0.05%, bare sclera + Bevacizumab eye drops 0.05% and bare sclera alone. In conclusion, given the numerous possible combinations of treatment for pterygium, it is possible to establish from the techniques compared in published clinical trials and availability of resources in each service, treatment with lower recurrence.
470

Do-it-yourself networks: a novel method of generating weighted networks

Shanafelt, D. W., Salau, K. R., Baggio, J. A. 22 November 2017 (has links)
Network theory is finding applications in the life and social sciences for ecology, epidemiology, finance and social-ecological systems. While there are methods to generate specific types of networks, the broad literature is focused on generating unweighted networks. In this paper, we present a framework for generating weighted networks that satisfy user- defined criteria. Each criterion hierarchically defines a feature of the network and, in doing so, complements existing algorithms in the literature. We use a general example of ecological species dispersal to illustrate the method and provide open- source code for academic purposes.

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