• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 8730
  • 2930
  • 1104
  • 1047
  • 1016
  • 682
  • 315
  • 302
  • 277
  • 266
  • 135
  • 128
  • 79
  • 78
  • 75
  • Tagged with
  • 20065
  • 3906
  • 2815
  • 2572
  • 2430
  • 2343
  • 1929
  • 1828
  • 1554
  • 1521
  • 1510
  • 1510
  • 1497
  • 1443
  • 1395
  • 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.
581

Performance Evaluation of Opportunistic Routing Protocols for Multi-hop Wireless Networks

Guercin, Sergio Rolando 15 March 2019 (has links)
Nowadays, Opportunistic Routing (OR) is widely considered to be the most important paradigm for Multi-hop wireless networks (MWNs). It exploits the broadcast nature of wireless medium to propagate information from one point to another within the network. In OR scheme, when a node has new information to share, it rst needs to set its forwarding list which include the IDs and/or any relevant information to its best suited neighboring nodes. This operation is supported by the use of appropriate metrics. Then, it executes a coordination algorithm allowing transmission reliability and high throughput among the next-hop forwarders. In this paper, we provide a comprehensive guide to understand the characteristics and challenges faced in the area of opportunistic routing protocols in MWNs. Moreover, since the planet we live on is largely covered by water, OR protocols have gained much attention during the last decade in real-time aquatic applications, such as oil/chemical spill monitoring, ocean resource management, anti-submarine missions and so on. One of the major problems in Underwater Wireless Sensor Network (UWSNs) is determining an e cient and reliable routing methodology between the source node and the destination node. Therefore, designing e cient and robust routing protocols for UWSNs became an attractive topic for researchers. This paper seeks to address in detail the key factors of underwater sensor network. Furthermore, it calls into question 5 state-of-the-art routing protocols proposed for UWSN: The Depth-Based Routing protocol (DBR), the Energy-E cient Depth-Based Routing protocol (EEDBR), the Hydraulic-pressure-based anycast routing protocol (Hydrocast), the Geographic and opportunistic routing protocol with Depth Adjustment for mobile underwater sensor networks (GEDAR), and the Void- Aware Pressure Routing for underwater sensor networks (VAPR). Finally, it covers the performance of those protocol through the use of the R programming language.
582

Foraging tactics and social networks in wild jackdaws

Kings, Michael January 2018 (has links)
Individual variation in asocial and social behavioural traits can affect patterns of social association. Resultant individual-level variation in sociality can be quantified using social network analysis. Social network analysis has recently been applied to the study of the evolution and development of social behaviour. Though captive systems have provided useful contributions to this endeavour, investigating the factors shaping social structure in wild populations affords superior ecological relevance. The characterisation of the social structure of wild animals has been greatly aided by improvements in automated data collection methods, particularly the miniaturisation of Radio-Frequency Identification (RFID) technology for the purposes of studying the social foraging behaviour of wild birds. In this thesis, I use RFID methods to examine the factors influencing between-individual variation in foraging routines (Chapter Two) and social network position (Chapter Three) in wild populations of a colonial corvid species, the jackdaw (Corvus monedula). I then relate social network position to reproductive success (Chapter Three) and investigate the developmental plasticity of jackdaw social behaviour by determining the effect of early life conditions on social network position (Chapter Four). Finally, I describe the fine-scale temporal dynamics of social foraging, the nature of accompaniment during paired foraging and the foraging benefits of social support (Chapter Five).
583

TITLE : NETWORK ORCHESTTRATION FOR ENVIRONMENAL SUSTAINBILITY; A CASE OF PUBLIC TRANSPORT SERVICES. / NETWORK ORCHESTTRATION FOR ENVIRONMENAL SUSTAINBILITY; A CASE OF PUBLIC TRANSPORT SERVICES.

Usama, Muhammad, Khan, Zohaib January 2013 (has links)
the hub firms which happen to be the central leading body carrying out responsibilities as a hub firm. The network orchestration comprises three vital orchestration processes Knowledge Mobility, Innovation Appropability and Network Stability which help the network orchestrator to communicate with multiple actors in the network. The research work is based on reflection and analysis of performance of hub firm in perspective of network orchestration and innovation project directed towards betterment of public transportation department. With respect to the domain of study there have been thorough perusal and analysis of several academic articles and resources which have hitherto been contributed for the subject in question. Methodology consists of in depth interview of the researchers of Victoria institute which are currently working on ISET program (Innovation for sustainable everyday travel). Our findings seek to answer the main question, that how a hub firm tackles with its emerging challenges to leverage network innovation, in shape of evidences from Viktoria Institute of research and development. Analysis of data is carried out through strategic management tool and descriptive approach. With all due efforts, the work has been afforded with validity and authenticity employing all the requisite elements as per social research is concerned. Discussion follows the analysis and results have been illustrated accordingly.
584

Time-varying network optimization problems. / CUHK electronic theses & dissertations collection

January 1999 (has links)
Dan Sha. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (p. 193-206). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.
585

Application of multi-resolution partitioning of interaction networks to the study of complex disease

Luecken, Malte January 2016 (has links)
Large-scale gene expression studies are widely used to identify genes that are differentially expressed between phenotypes relevant to disease. Often thousands of differentially expressed genes (DEGs) are found using this type of analysis, which complicates the interpretation of the data. In this project we treat DEGs as windows into the biological processes that underlie disease. In order to find these processes, we put DEGs into the context in which they perform their functions - through the interactions of their protein products. Protein-protein interactions can provide biological context to DEGs in the form of functional modules. These modules are groups of proteins that together perform cellular functions. In this thesis we have refined a functional module detection process that consists of two steps. Firstly, community detection methods are applied to protein interaction networks (PINs) to detect groups of interacting proteins, and secondly, the biological coherence of the proteins grouped together is evaluated to select communities that represent potential functional modules. Two features that are central to this work are the detection of modules at different scales of network organization, and CommWalker, a module evaluation method that we developed which is able to detect signals of poorly-studied functions. By integrating these methods into our functional module detection process, we were able to obtain a good coverage of potential functional modules. Testing for enrichment of DEGs on these functional modules can uncover biological processes that are involved in the contrasted phenotypes and merit further investigation. We have applied our pipeline to find differentially regulated functions between hypoxic and normoxic breast cancer cell lines, and between M1 and M2 macrophages. Our results generate biological hypotheses of cellular functions that are differentially regulated in the investigated phenotypes, and proteins that are involved in these functions. We were able to validate several proteins in enriched modules which did not correspond to DEGs that were input into the pipeline, which suggests our methodology can reveal new biological insight.
586

Using pathway networks to model context dependent cellular function

Stoney, Ruth January 2018 (has links)
Molecular networks are commonly used to explore cellular organisation and disease mechanisms. Function is studied using molecular interaction networks, such as protein-protein networks. Although much biological insight has been gained using these models of molecular function, they are hindered by their reliance on available experimental data and an inability to capture the complexity of biological processes. Functional modules can be identified based on molecular network topology, making it essential that the edges accurately depict molecular interactions. However, these networks struggle to depict the temporal nature of interactions, giving the impression that all interactions are constant. This misrepresentation can result in functionally heterogeneous clusters. The notoriously inaccurate nature of experimental protein interaction data, along with variable conformity among network clusters and functional modules further impedes functional module extraction. Representation of genes by single nodes artificially merges the functions of pleiotropic genes, distorting the arrangement of function within molecular networks. This thesis therefore explores a more suitable model for representing function. Pathways are composed of sets of proteins that are known to interact within a particular cellular context, corresponding to a discernible biological function. Their representation of context dependent cellular activity makes them ideal for use as nodes within a new pathway level model. Using combinatorial algorithms a reduced redundancy pathway set was produced to represent global cellular systems. Enrichment analysis provides reliable functional annotations for each pathway node, attributing independent functions to pleiotropic genes. Edges are based on functional semantic similarity, generating a network representation of functional organisation. Both yeast and human biological systems are presented as functionally connected pathway networks. Pathway annotation and experimentation with semantic similarity measures provides insight into the cross-talk between biological processes. Pathway functional modules elucidate the intracellular implementation of processes. Disease modules highlight the effects of functional perturbations and disease mechanisms. The pathway model provides a complementary, high-level functional model that begins to bridge the gap between molecular data and phenotype. The utilisation of pathway data provides a large, well-validated data source, avoiding the inaccuracies inherent with molecular data. Pathway models better represent components of biological complexity such as pleiotropy and linear implementation of functions.
587

Design and performance analysis of MAC protocol for wireless LAN.

January 2005 (has links)
Liu Haiping. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 78-82). / Abstracts in English and Chinese. / Acknowledgments --- p.i / Abstract --- p.ii / Table of Contents --- p.vi / List of Figures --- p.vii / List of Tables --- p.ix / Chapter Chapter I --- Introduction to Wireless LAN --- p.1 / Chapter 1.1 --- Wireless LAN Netwrok Architecture --- p.2 / Chapter 1.2 --- IEEE 802.11 protocol family --- p.4 / Chapter 1.3 --- The Major factors influencing the System Performance --- p.7 / Chapter 1.4 --- Research Objectives --- p.13 / Chapter 1.5 --- Overview --- p.13 / Chapter Chapter II --- The Major Deficiency of DCF and Motivation --- p.14 / Chapter 2.1 --- DCF --- p.15 / Chapter 2.2 --- The Major Deficiencies in the DCF --- p.20 / Chapter 2.3 --- Improvement directions --- p.24 / Chapter Chapter III --- Proposed MAC Protocol --- p.27 / Chapter 3.1 --- The Design Idea --- p.28 / Chapter 3.2 --- The Number of Active Nodes --- p.30 / Chapter 3.3 --- Optimizaition Method for CW --- p.32 / Chapter 3.4 --- CW and Counter value Updating --- p.35 / Chapter 3.5 --- Procedure Flow and Simulation Results --- p.37 / Chapter Chapter IV --- Advanced Proposed Protocol with QoS issues --- p.44 / Chapter 4.1 --- "QoS requirement, EDCF solution and others' work" --- p.45 / Chapter 4.2 --- Frame structure changes in the Advanced Proposed MAC Protocol --- p.47 / Chapter 4.3 --- Recursivley Balance Optimization Method for CW --- p.48 / Chapter 4.4 --- Decision Algorithm --- p.54 / Chapter 4.5 --- Model Validation and Simulation Results --- p.66 / Chapter Chapter V --- Further Discussion about CW design --- p.70 / Chapter 5.1 --- Influence of the ranges of CW --- p.71 / Chapter 5.2 --- Proposal for adjusting CW --- p.73 / Chapter Chapter VI --- Conclusion --- p.75 / Bibliography --- p.78
588

An algebraic approach of optical performance monitoring in all-optical networks.

January 2005 (has links)
Ho Siu Ting. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 84-87). / Abstracts in English and Chinese. / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Drivers for performance monitoring --- p.1 / Chapter 1.2 --- Migration of performance monitoring --- p.1 / Chapter 1.3 --- OPM categories --- p.3 / Chapter 1.4 --- Review on OSNR monitoring --- p.6 / Chapter 1.4.1 --- Polarization approach --- p.6 / Chapter 1.4.1.1 --- Polarization extinction --- p.6 / Chapter 1.4.1.2 --- Degree-of-polarization (DOP) analysis --- p.7 / Chapter 1.4.2 --- Interferometric approach --- p.7 / Chapter 1.4.3 --- RF spectral analysis approach --- p.8 / Chapter 1.5 --- Review on PMD monitoring --- p.8 / Chapter 1.5.1 --- DOP approach --- p.8 / Chapter 1.5.2 --- RF spectral analysis approach --- p.9 / Chapter 1.5.3 --- Arrival time measurement approach --- p.9 / Chapter 1.6 --- Objective of the thesis --- p.9 / Chapter 1.7 --- Linear expressions of optical impairments --- p.10 / Chapter Chapter 2 --- Monitoring of Linearly Accumulated Impairments in Unidirectional Links and Nodes --- p.12 / Chapter 2.1 --- Introduction --- p.12 / Chapter 2.2 --- Problem formulation --- p.12 / Chapter 2.3 --- Probing scheme --- p.19 / Chapter 2.3.1 --- Two-link-connected networks --- p.19 / Chapter 2.3.1.1 --- Ring network --- p.20 / Chapter 2.3.1.2 --- General two-link-connected network --- p.25 / Chapter 2.3.2 --- Tree networks --- p.28 / Chapter 2.3.3 --- Networks with bridges --- p.33 / Chapter 2.3.4 --- Illustrative example --- p.36 / Chapter 2.4 --- Single-fault localization --- p.42 / Chapter 2.5 --- Conclusion --- p.43 / Chapter Chapter 3 --- Monitoring of Linearly Accumulated Impairments in Directional Links --- p.45 / Chapter 3.1 --- Introduction --- p.45 / Chapter 3.2 --- Problem formulation --- p.45 / Chapter 3.3 --- Feasibility analysis --- p.48 / Chapter 3.4 --- Probing scheme --- p.50 / Chapter 3.4.1 --- Two-link-connected networks --- p.50 / Chapter 3.4.1.1 --- Probing scheme with only one monitoring module --- p.50 / Chapter 3.4.1.2 --- Optimal location --- p.51 / Chapter 3.4.2 --- Tree networks --- p.56 / Chapter 3.4.3 --- Networks with bridges --- p.57 / Chapter 3.4.4 --- Illustrative example --- p.58 / Chapter 3.5 --- Reliability and fault localization --- p.64 / Chapter 3.5.1 --- Fth-order probing scheme --- p.64 / Chapter 3.5.2 --- Locations of monitoring modules for Fth-order probing scheme --- p.67 / Chapter 3.5.3 --- Fault localization in Fth-ordcr probing scheme --- p.68 / Chapter 3.6 --- Conclusion --- p.69 / Chapter Chapter 4 --- Other Models --- p.70 / Chapter 4.1 --- Introduction --- p.70 / Chapter 4.2 --- Models --- p.70 / Chapter 4.3 --- Probing scheme for El --- p.71 / Chapter 4.4 --- "Necessary locations of monitoring modules for EN2, EN3 and EN4" --- p.72 / Chapter 4.5 --- Conclusion --- p.79 / Chapter Chapter 5 --- Summary and Future Works --- p.81 / Chapter 5.1 --- Summary of the thesis --- p.81 / Chapter 5.2 --- Future works --- p.83 / Bibliography --- p.84 / Appendix - List of publications --- p.88
589

Autonomous smart antenna systems for future mobile devices

Zhou, Wei January 2015 (has links)
Along with the current trend of wireless technology innovation, wideband, compact size, low-profile, lightweight and multiple functional antenna and array designs are becoming more attractive in many applications. Conventional wireless systems utilise omni-directional or sectored antenna systems. The disadvantage of such antenna systems is that the electromagnetic energy, required by a particular user located in a certain direction, is radiated unnecessarily in every direction within the entire cell, hence causing interference to other users in the system. In order to limit this source of interference and direct the energy to the desired user, smart antenna systems have been investigated and developed. This thesis presents the design, simulation, fabrication and full implementation of a novel smart antenna system for future mobile applications. The design and characterisation of a novel antenna structure and four-element liner array geometry for smart antenna systems are proposed in the first stage of this study. Firstly, a miniaturised microstrip-fed planar monopole antenna with Archimedean spiral slots to cover WiFi/Bluetooth and LTE mobile applications has been demonstrated. The fundamental structure of the proposed antenna element is a circular patch, which operates in high frequency range, for the purpose of miniaturising the circuit dimension. In order to achieve a multi-band performance, Archimedean spiral slots, acting as resonance paths, have been etched on the circular patch antenna. Different shapes of Archimedean spiral slots have been investigated and compared. The miniaturised and optimised antenna achieves a bandwidth of 2.2GHz to 2.9GHz covering WiFi/Bluetooth (2.45GHz) and LTE (2.6GHz) mobile standards. Then a four-element linear antenna array geometry utilising the planar monopole elements with Archimedean spiral slots has been described. All the relevant parameters have been studied and evaluated. Different phase shifts are excited for the array elements, and the main beam scanning range has been simulated and analysed. The second stage of the study presents several feeding network structures, which control the amplitude and phase excitations of the smart antenna elements. Research begins with the basic Wilkinson power divider configuration. Then this thesis presents a compact feeding network for circular antenna array, reconfigurable feeding networks for tuning the operating frequency and polarisations, a feeding network on high resistivity silicon (HRS), and an ultrawide-band (UWB) feeding network covering from 0.5GHz to 10GHz. The UWB feeding network is used to establish the smart antenna array system. Different topologies of phase shifters are discussed in the third stage, including ferrite phase shifters and planar phase shifters using switched delay line and loaded transmission line technologies. Diodes, FETs, MMIC and MEMS are integrated into different configurations. Based on the comparison, a low loss and high accurate Hittite MMIC analogue phase shifter has been selected and fully evaluated for this implementation. For the purpose of impedance matching and field matching, compact and ultra wideband CPW-to-Microstrip transitions are utilised between the phase shifters, feeding network and antenna elements. Finally, the fully integrated smart antenna array achieves a 10dB reflection coefficient from 2.25GHz to 2.8GHz, which covers WiFi/Bluetooth (2.45GHz) and LTE (2.6GHz) mobile applications. By appropriately controlling the voltage on the phase shifters, the main beam of the antenna array is steered ±50° and ±52°, for 2.45GHz and 2.6GHz, respectively. Furthermore, the smart antenna array demonstrates a gain of 8.5dBi with 40° 3dB bandwidth in broadside direction, and has more than 10dB side lobe level suppression across the scan. The final stage of the study investigates hardware and software automatic control systems for the smart antenna array. Two microcontrollers PIC18F4550 and LPC1768 are utilised to build the control PCBs. Using the graphical user interfaces provided in this thesis, it is able to configure the beam steering of the smart antenna array, which allows the user to analyse and optimise the signal strength of the received WiFi signals around the mobile device. The design strategies proposed in this thesis contribute to the realisation of adaptable and autonomous smart phone systems.
590

Predictive computational modelling of the c-myc gene regulatory network for combinatorial treatments of breast cancer

Clarke, Matthew Alan January 2018 (has links)
As cancer tumours develop, competition between cells will favour those with some mutations over others, creating a dynamic heterogeneous system made up of different cell populations, called sub-clones. This heterogeneity poses a challenge for treatment, as this variety serves to ensure there is almost always a portion of the cells which are resistant to any one targeted therapy. This can be avoided by combining therapies, but finding viable combinations experimentally is expensive and time-consuming. However, there is also cooperation between sub-clones, and being able to better model and predict these dynamics could allow this interdependence to be exploited. In order to investigate how best to tackle tumour heterogeneity, while avoiding acquired resistance, I have developed the first comprehensive computational model of the gene regulatory network in breast cancer focused on the c-myc oncogene and the differences between sub-clones. I model the system as a discrete, qualitative network, which can reproduce the conditions in heterogeneous tumours, as well as predict the effect of perturbations mimicking mutations or application of therapy. Together with experimental collaborators, I apply my computational model to an in vivo mouse model of MMTV-Wnt1 driven breast cancer, which has high and low c-myc expressing sub-clones. I show that the computational model is able to reproduce the behaviour of this system, and predict how best to target either one sub-clone individually or the tumour as a whole. I show how combination therapies offer more paths to attack the tumour, and how two drugs can work synergistically. For example, I predict how Mek inhibition will preferentially affect one sub-clone, but the addition of COX2 inhibition improves effectiveness across the tumour as a whole. In this thesis, I show how a computational network model can predict treatments in breast cancer, and assess the effects on different clones of different treatment combinations. This model can be easily extended with new data, as well as adapted to different types of cancer. This therefore represents a novel method to find viable combination therapies computationally and speed up the development of new cancer treatments.

Page generated in 0.0402 seconds