• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 104
  • 23
  • 20
  • 16
  • 10
  • 8
  • 8
  • 5
  • 5
  • 4
  • 1
  • 1
  • 1
  • Tagged with
  • 237
  • 237
  • 75
  • 35
  • 32
  • 30
  • 26
  • 26
  • 24
  • 24
  • 23
  • 22
  • 22
  • 19
  • 19
  • 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.
61

Channel Estimation in Half and Full Duplex Relays

January 2018 (has links)
abstract: Both two-way relays (TWR) and full-duplex (FD) radios are spectrally efficient, and their integration shows great potential to further improve the spectral efficiency, which offers a solution to the fifth generation wireless systems. High quality channel state information (CSI) are the key components for the implementation and the performance of the FD TWR system, making channel estimation in FD TWRs crucial. The impact of channel estimation on spectral efficiency in half-duplex multiple-input-multiple-output (MIMO) TWR systems is investigated. The trade-off between training and data energy is proposed. In the case that two sources are symmetric in power and number of antennas, a closed-form for the optimal ratio of data energy to total energy is derived. It can be shown that the achievable rate is a monotonically increasing function of the data length. The asymmetric case is discussed as well. Efficient and accurate training schemes for FD TWRs are essential for profiting from the inherent spectrally efficient structures of both FD and TWRs. A novel one-block training scheme with a maximum likelihood (ML) estimator is proposed to estimate the channels between the nodes and the residual self-interference (RSI) channel simultaneously. Baseline training schemes are also considered to compare with the one-block scheme. The Cramer-Rao bounds (CRBs) of the training schemes are derived and analyzed by using the asymptotic properties of Toeplitz matrices. The benefit of estimating the RSI channel is shown analytically in terms of Fisher information. To obtain fundamental and analytic results of how the RSI affects the spectral efficiency, one-way FD relay systems are studied. Optimal training design and ML channel estimation are proposed to estimate the RSI channel. The CRBs are derived and analyzed in closed-form so that the optimal training sequence can be found via minimizing the CRB. Extensions of the training scheme to frequency-selective channels and multiple relays are also presented. Simultaneously sensing and transmission in an FD cognitive radio system with MIMO is considered. The trade-off between the transmission rate and the detection accuracy is characterized by the sum-rate of the primary and the secondary users. Different beamforming and combining schemes are proposed and compared. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2018
62

Internet of Things : Quantitative Evaluation on Microsoft Azure IoT Suite

Ding, Yuxia January 2017 (has links)
The Internet of Things (IoT) is rapidly gaining ground in our daily life. There is a trend that the number of devices and data increases rapidly in the future. Meanwhile, IoT platforms are emerging to enable people conveniently deal with the IoT and these huge amount of data and devices. Therefore, the goal in this paper is to perform a quantitative evaluation on Microsoft Azure, one of the IoT platform, about its advantages and disadvantages under press to determine if Azure IoT is fit for future IoT. In order to reach this goal, Azure IoT Hub is used as a bridge to connect and manage lots of IoT devices which send and receive huge amount of data. .NET is used to simulate devices and connect them to the IoT Hub. The two-way communication from sensor to cloud and from cloud to actuator is implemented through MQTT protocol. This paper makes measurements on three metrics including response time from sensor sending messages to actuator receiving messages, scalability and cost and analyzes them in detail. Besides, the analysis is also made in a specific scenario which has high demand on sensor update to see how Azure IoT performs. Finally, conclusion is made on Microsoft Azure IoT's advantages and disadvantages under stress.
63

Essays on international portfolio choices and capital flows

Zhang, Ning January 2016 (has links)
The goal of this thesis is to study the international portfolio choices of countries in an asymmetric world. In practice, this corresponds to the salient facts of country portfolios and the underlying structural asymmetries between developing and developed countries in a financially integrated world. In the three main chapters of the thesis, frameworks are developed to advance our understanding of the way various country asymmetries contribute to the emergence of these persistent phenomena in international capital markets. The first essay studies the question of why developing countries experience net equity inflows and bond outflows while developed countries experience net equity outflows and bond inflows, the so-called ‘two-way capital flows'. The analysis is based on an open-economy New Keynesian model of endogenous country portfolios with representative agents in each country. The model is so general that it allows one to perform an assessment of the roles of a long list of country asymmetries in determining the pattern of two-way capital flows. While steady-state net country portfolios are zero in the first essay, the second and third essays consider the situations where this is not true. The second essay presents an OLG model of an endowment economy with a country asymmetry in households' patience. Global imbalances in net positions emerge. Gross portfolio positions are obtained as the sum of standard self-hedging and, moreover, the hedging due to external imbalances. The valuation effects of external adjustments between creditor and debtor countries are rationalized. By introducing non-tradable risks, the third essay models a production OLG economy with a country asymmetry in wealth division. Global imbalances in net positions again arise. Gross portfolio positions are composed of self-hedging, hedging of non-tradable income and hedging of external interest payments, which accounts for the reality of asymmetric asset home bias, i.e. although assets are locally biased everywhere, the pattern is more pronounced in creditor countries.
64

A interatividade no Programa Ensino Médio Presencial com Mediação Tecnológica

Arcanjo, Joel Rodrigues 21 December 2015 (has links)
Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-04-06T14:28:31Z No. of bitstreams: 1 joelrodriguesarcanjo.pdf: 1334975 bytes, checksum: 4b7b272e7e29152843a068f4ddd0335d (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-04-07T16:08:40Z (GMT) No. of bitstreams: 1 joelrodriguesarcanjo.pdf: 1334975 bytes, checksum: 4b7b272e7e29152843a068f4ddd0335d (MD5) / Made available in DSpace on 2017-04-07T16:08:40Z (GMT). No. of bitstreams: 1 joelrodriguesarcanjo.pdf: 1334975 bytes, checksum: 4b7b272e7e29152843a068f4ddd0335d (MD5) Previous issue date: 2015-12-21 / A presente dissertação, desenvolvida no âmbito do Programa de Pós-Graduação Profissional em Gestão e Avaliação da Educação Pública do Centro de Políticas Públicas e Avaliação da Educação da Universidade Federal de Juiz de Fora, aborda o caso de gestão referente à prática da Interatividade Bidirecional no Projeto Ensino Médio Presencial com Mediação Tecnológica no município de Tonantins/AM. A pesquisa traz a seguinte questão norteadora: por que a interatividade entre o Professor Ministrante e os alunos, no momento em que as aulas são transmitidas, não acontece como prevê a Proposta Pedagógica do PEMPMT, ou seja, de modo dialógico, em que se atendam as demandas de cada estudante? Com a finalidade de analisar essa questão, a pesquisa empreendida pautou-se em uma metodologia de base qualitativa, com a utilização da análise documental e questionários como instrumentos de construção de dados. A análise documental procedeu-se nas Orientações Didáticas e nas Cartelas das Aulas. Já o questionário foi proposto aos alunos de duas turmas de 3ª serie do Ensino Médio do PEMPMT na Escola Estadual São Francisco, bem como a dois professores presenciais e a 24 professores ministrantes das já referidas turmas. A realização desta pesquisa teve como referencial teórico as reflexões de autores como Arantes (2010), Belloni (2012), Costa (2015), Dias (2010), Freire (1987), Lévy (2001), Malhotra (2012), Moore (2013), Moran (2007), Peña (2012), Peters (2001), Primo (2011), Valente (2003), Vigotsky (1991) e Zuin (2010). Os resultados apontaram para duas problemáticas principais: I) a necessidade de melhoria do uso das ferramentas de interatividade para que assim, haja uma interação eficaz entre os partícipes do processo educativo; II) a necessidade de formação específica para atuar como professor dessa modalidade de ensino. A partir dessas constatações, como proposições que podem empoderar os atores educativos do PEMPMT para que se tenha um diálogo efetivo, buscando desenvolver as ações de construção do conhecimento, mediado pelas TIC, e uma educação com qualidade, são expostas em seguida: I) reformulação da Proposta Pedagógica do PEMPMT, para que se possam utilizar as ferramentas de interatividade bidirecional, como o fórum e a wiki, utilizando os 20% das aulas assíncronas do curso; II) realização de um Curso de Formação Específica acerca das técnicas e dos procedimentos que facilitem a mediação pedagógica do conhecimento para os professores presenciais de Tonantins/AM. Dessa forma, tanto a reorganização da estrutura do curso quanto o uso qualitativo das ferramentas de interatividade e a formação específica para atuar nesse modelo educativo são fundamentais para uma melhoria da Interatividade Bidirecional do Projeto Ensino Mediado por Tecnologia em Tonantins e, por conseguinte, no Amazonas. / This thesis, developed under the Post Professional Graduate Program in Management and Public Education Evaluation Center for Public Policy and Evaluation eEducation the Federal University of Juiz de Fora, deals with the case management refers to the practice of Interaction Bidirectional in High School Project Classroom with Technology Mediation in the municipality of Tonantins - AM. The research brings the following guiding question: Why is the interaction between Professor Lecturer and students, at the time the lessons are transmitted is not the case as provided by the Pedagogical the PEMPMT, ie dialogical way in which they meet demands of each student? In order to examine this question, the research undertaken was based on a qualitative basis methodology, with the use of document analysis and questionnaires as data building instruments. The documentary analysis was carried out in didactic Guidelines and Bingo Tickets of classes. Since the questionnaire was offered to the students of two classes of 3rd series of the East PEMPMT Education, State School in San Francisco; two classroom teachers and ministering to twenty-four teachers of the aforementioned classes. This research had as theoretical reflections of authors such as Arantes (2010), Belloni (2012), Costa (2015), Dias (2010), Freire (1987), Levy (2001), Malhotra (2012), Moore ( 2013), Moran (2007), Peña (2012), Peters (2001), Cousin (2011), Valente (2003), Vygotsky (1991) and Zuin (2010). The results pointed to two main issues: i) the need to improve the use of interactive tools so that, there is an effective interaction between the participants in the educational process; III) the need for specific training to act as teacher of this type of education. From these findings, as a proposition that can empower the educational actors PEMPMT order to have an effective dialogue, seeking to develop the actions of construction of knowledge, mediated by ICT and quality in education are set out below: I) Recast Proposal pedagogic PEMPMT, so you can use the tools of two-way interactivity as the forum and the wiki, using 20% of asynchronous classes of the course; II) Development of a specific training course about the techniques and procedures that facilitate the mediation of knowledge to the classroom teacher Tonantins - AM. Thus, both the reorganization of the structure of the course as the qualitative use of interactive tools and specific training to work in this educational model, are key to improving the two-way interactivity of Mediated Education Project for Technology in Tonantins and therefore in Amazons.
65

Customer engagement : A study of consumers interaction with fashion brands on social media

Bylund, Isabelle, Lindgren, Susanne January 2017 (has links)
Social media is widely expanded worldwide with increasing number of users in social networks. Social media allows the consumers to connect directly with companies, which has led to a shift from traditional one-way communication to a two-way communication between both consumer to company and consumer to consumer. A successful two-way communication on social media engages both the consumers and the company. The rise of social media has quickly changed the marketing approach, as it creates new opportunities for the consumer to connect and communicate in a greater rich. In a two-way communication, the communication needs to create engagement from the consumers even though the consumer may not want to engage, contributing to a challenge for companies to communicate to customers in order for them to engage. It could be argued that companies should in some way get their customers to be more engaged even though the engagement can generate several outcomes in this complex communication approach. Furthermore, customer engagement could have an impact on the purchase intention for the consumer. Therefore, the aim of this thesis is to investigate motives that create customer engagement with fashion brands on social media and the relation between customer engagement motives and purchase intention with a fashion brand. According to previous research, personal interest, entertainment, rewards and information acquisition and sharing are the most encouraging motives for customer engagement. Due to that fact, these motives were in focus in the study and the motives were also put in relation to their effect on purchase intention. The research was conducted by a quantitative study through a survey, in order to gather an overviewing perspective in customer engagement on social media towards fashion brands. The sample size reached a valid number of 109 respondents. The findings of this thesis give the impression that overall customer engagement is still low even for the investigated motives. This indicates that the respondents do not usually take part of the two-way dialog. The reliability seems to lie with other consumers rather than fashion brands on social media when searching for information. In addition, information acquisition was ranked as the most encouraging motive while personal interest is the motive that most encourage to purchase intention.
66

Tests of additivity in mixed and fixed effect two-way ANOVA models with single sub-class numbers

Rasch, Dieter, Rusch, Thomas, Simeckova, Marie, Kubinger, Klaus D., Moder, Karl, Simecek, Petr January 2009 (has links) (PDF)
In variety testing as well as in psychological assessment, the situation occurs that in a two-way ANOVA-type model with only one replication per cell, analysis is done under the assumption of no interaction between the two factors. Tests for this situation are known only for fixed factors and normally distributed outcomes. In the following we will present five additivity tests and apply them to fixed and mixed models and to quantitative as well as to Bernoulli distributed data. We consider their performance via simulation studies with respect to the type-I-risk and power. Furthermore, two new approaches will be presented, one being a modification of Tukey's test and the other being a new experimental design to test for interactions.
67

Investigating Transparency in Government of Canada Citizen-focused Communications

Ghergari, Kori January 2012 (has links)
Government of Canada communications professionals work in an increasingly challenging environment, characterized by an intrusive 24/7 media cycle, a frenetic pace of evolving communication technologies, layered accountability requirements, political tension, and waning public trust. Scholars call on professional communicators to help rebuild public trust, which is intrinsic to a healthy democratic government. The Three-dimensional Model for Transparency in Government Communication developed by Fairbanks, Plowman and Rawlins (2007) serves as the theoretical framework for investigating the Government of Canada’s approach to transparent citizen-focused communications from the perspective of communications professionals. The model’s adaptability to the Government of Canada context is tested through 23 qualitative semi-structured interviews with Government of Canada senior communications advisors, managers and executives. The data is analysed using constant comparative thematic analysis. The findings demonstrate that Government of Canada communicators strongly value transparency. Furthermore, the key components of the transparency model – communications practices, organizational support and provision of resources – encapsulate the factors that influence the practice of transparent citizen-focused communications by the Government of Canada. The study concludes by offering recommendations for future research and practical applications.
68

Beyond Transition: Understanding Workplace Integration of Internationally Educated Nurses - A Qualitative Case Study

Ramji, Zubeida January 2016 (has links)
Internationally Educated Nurses (IENs) have been proposed as one solution to dealing with the nursing shortage in Canada. In addition to helping sustain the profession, IENs are reflective of the diverse patient populations in Canada. Investments will ensure healthy workplaces for and retention of IENs. There has been a growing interest about IENs’ experiences with migration and navigating through the regulatory process, but research on their post-transition experience is lacking. Workplace integration for IENs is not well understood and the role of the employer has received limited focus. Guided by critical social theory, an instrumental qualitative case study approach was used to examine a single organization, St. Michael’s Hospital, Toronto, with a history of supporting IENs. A purposeful sample of twenty-eight participants included diverse IENs who were post-transition, and stakeholders from various vantage points. Four forms of data collection were used: semi-structured interviews; socio-demographic survey; review of documents and focus groups. Thematic analysis was carried out to form a within subcase analysis first, followed by an across subcase analysis. The major themes are: (a) when “integrated”, an IEN is (i) being a “Canadian nurse with international experience”; (ii) progressing on the leadership journey; and (iii) persevering in overcoming challenges; (b) organizational factors that influence workplace integration of IEN are (i) workforce diversity; (ii) leadership commitment to equity; (iii) policies promoting equity principles; (iv) engagement with the broader community; and (v) avoiding common pitfalls. This research offers a definition and conceptual framework where workplace integration of IENs is a “two-way” process within an inclusive and valuing context, producing changes both at the IEN as well as organizational levels.
69

Cross-layer design for multi-hop two-way relay network

Zhang, Haoyuan 28 June 2017 (has links)
Physical layer network coding (PNC) was proposed under the two-way relay hannel (TWRC) scenario, where two sources exchange information aided by a relay. PNC allows the two sources to transmit to the relay simultaneously, where superimposed signals at the relay can be mapped to network-coded symbols and then be broadcast to both sources instead of being treated as interference. Concurrent transmissions using PNC achieve a higher spectrum efficiency compared to time division and network coding solutions. Existing research mainly focused on the symmetric PNC designs, where the same channel coding and modulation configurations are applied by both sources. When the channel conditions of the two source-relay links are asymmetric or unequal amount of data are exchanged, heterogeneous modulation PNC designs are necessary. In additional, the design and optimization of multi-hop PNC, where multiple relays forming a multi-hop path between the two sources, remains an open issue. The above issues motivate the study of this dissertation. This dissertation investigates the design of heterogeneous modulation physical layer network coding (HePNC), the integration of channel error control coding into HePNC, the combination of HePNC with hierarchical modulation, and the design and generalization of multi-hop PNC. The contributions of this dissertation are four-fold. First, under the asymmetric TWRC scenario, where the channel conditions of the two source-relay links are asymmetric, we designed a HePNC protocol, including the optimization of the adaptive mapping functions and the bit-symbol labeling, to minimize the end-to-end BER. In addition, we developed an analytical framework to derive the BER of HePNC. HePNC can substantially enhance the throughput compared to the existing symmetric PNC under the asymmetric TWRC scenario. Second, we investigated channel coded HePNC and integrated the channel error control coding into HePNC in a link-to-link coding, where the relay tries to decode the superimposed codewords in the multi-access stage. A full-state sum-product decoding algorithm is proposed at the relay based on the repeat-accumulate codes to guarantee reliable end-to-end communication. Third, we proposed hierarchical modulation PNC (H-PNC) under asymmetric TWRC, where additional data exchange between the relay and the source with the relatively better channel condition is achieved in addition to that between the two end sources, benefiting from superimposing the additional data flow on the PNC transmission. When the relay also has the data exchange requirement with the source with a better source-relay channel, H-PNC outperforms HePNC and PNC in terms of the system sum throughput. Fourth, we designed and generalized multi-hop PNC, where multiple relays located in a linear topology are scheduled to support the data exchange between two end sources. The impact of error propagation and mutual interference among the nodes are addressed and optimized. The proposed designs outperform the existing ones in terms of end-to-end BER and end-to-end throughout. / Graduate
70

The Effects of Bilingual Education on Reading Test Scores: Can Dual-immersion Support Literacy for All Students?

Ridley, Natalie D. 05 1900 (has links)
Dual-immersion is a bilingual education method offered that places English as a first language (EFL) and English language learner (ELL) students in the same classroom to learn two languages at the same time. This study examines whether second language acquisition through dual-immersion supports literacy for both ELL and EFLS children over time. Students' scores on standardized tests (ITBS, TAKS, Logramos, Stanford 9, and Aprenda) were studied to assess the impact, if any, of dual-immersion instruction vs. regular/bilingual education on reading development. Scores from 2000 through 2004 were gathered and analyzed for students enrolled in a dual-immersion class which started in kindergarten in 2000. These scores were compared to scores of students enrolled in regular and bilingual education classrooms for the same amount of time at the same school to examine whether there was an effect for students in the dual-immersion class. It was found that no significant difference existed between the groups. All groups were performing at a passing level on the standardized tests. The dual-immersion class was performing as well as the regular education class on standardized tests in both English and Spanish.

Page generated in 0.0455 seconds