To see the other types of publications on this topic, follow the link: Diverse and dynamic environments.
Dissertations / Theses on the topic 'Diverse and dynamic environments'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Diverse and dynamic environments.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Taylor, Brian Kyle. "TRACKING FLUID-BORNE ODORS IN DIVERSE AND DYNAMIC ENVIRONMENTS USING MULTIPLE SENSORY MECHANISMS." Case Western Reserve University School of Graduate Studies / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=case1341601566.
Full text
2
Cavender-Bares, Kent Keller 1966. "Size distributions, population dynamics, and single-cell properties of marine plankton in diverse nutrient environments." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/34338.
Full textAbstract:
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1999.<br>Includes bibliographical references.<br>The goal of this thesis is to study the relationship between the community structure of marine microorganisms and nutrient availability. To this end, size spectra of microbes were studied over a range of nutrient regimes, both natural and manipulated. Three transects in the Atlantic provided a natural range of nutrient environments, especially because they captured seasonal variations. The transects encompassed Sargasso Sea, Gulf Stream, and coastal waters, during winter, spring, and summer. Nutrient regimes ranged from surface waters of the Sargasso Sea during stratified periods (low-nutrient), to deeply mixed waters in all three regions of the transects during winter and spring (high-nutrient). Complementing natural variations in nutrients, two experiments were used to study the effects of enrichment on size structure. An in situ iron-enrichment experiment conducted in the equatorial Pacific (IronEx II) provided a unique opportunity to monitor changes in community structure following increased nutrient availability. In a second experiment in the Sargasso Sea, enrichments with nitrogen and phosphorus were conducted in bottles, because one or both are commonly thought to be limiting in this region. In order to carry out the goal of this thesis, which depended on the use of flow cytometry to characterize bacterio-, pico-, ultra-, and nanophytoplankton, advancements were made in methods for enumerating a wide range of cell sizes and for estimating cell size from forward angle light scatter. In addition, because ambient concentrations of inorganic nitrogen and phosphorus are exceedingly low (<10nM) in the Atlantic, especially during stratified periods, low-level determinations of these nutrients were made to compliment the analyses of community structure. Size structure varied systematically, although not necessarily as a function of nutrient availability. Two parameters were explored: 1) spectral slope, which indicates the relative contribution of large and small cells to total biomass, and 2) spectral shape, or adherence of the spectra to relationships explained by a power law. The relative ranking of the slopes from specific regions of the transects remained constant throughout different seasons. Shapes ranged from discontinuous to those which adhered to a power law. It is hypothesized that only microbial systems with abundant nutrient inputs and, perhaps, reduced grazing pressure, have smooth spectra whose shapes conform to power laws.<br>by Kent Keller Cavender-Bares.<br>Ph.D.
3
Cavaliere, Emily Homann Peter S. "Elwha River sediments : phosphorus dynamics under diverse environmental conditions /." Online version, 2010. http://content.wwu.edu/cdm4/item_viewer.php?CISOROOT=/theses&CISOPTR=344&CISOBOX=1&REC=18.
Full text
4
Osborne, James Alexander. "Supporting visualization users in diverse environments." Thesis, University of Hull, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.431056.
Full text
5
Egel, Eleftheria. "Spiritual leadership : expressions in diverse organizational environments." Thesis, Nice, 2015. http://www.theses.fr/2015NICE0007.
Full textAbstract:
Cette thèse s’appuie sur le cadre théorique du « leadership spiritual » , le Spiritual Leadership Theory (SLT). En s’appuyant sur le SLT nous explorons trois perspectives différentes: laique, religieux et eco-humaniste. Pour le faire, nous mobilisons un modèle de Leadership Spirituel : le Spiritual Leadership Model (SLM). La thèse comporte trois études. La première étude a pour objectif de transposer le modèle SLM à un contexte particulier: l’Islam. La deuxième étude, empirique, étudie le cas d’une entreprise d’Arabie Saoudite. Au travers du modèle théorique développé dans la première étude : l’ ILM. La troisième étude, empirique, explore la présence de spiritualité dans une organisation française exerçant son activité principale dans le commerce équitable<br>The purpose of this dissertation is to link spiritual leadership in three diverse organizational environments-secular, religious (Islam) and eco-humanist (Fair Trade)- through a specific model of spiritual leadership, the Spiritual Leadership Model (SLM).The task is undertaken through three studies. Study 1 proposes a theoretical transposition of the SLM into Islam. The result of this transposition is the creation of an Islamic leadership model, the Islamic Leadership Model (ILM). Study 2 is a qualitative theory testing case study. It tests the ILM in an Islamic organization in Saudi Arabia. Study 3 is a qualitative theory building case study. First, it argues that spirituality can help Fair Trade to avoid dilution of its message and business. Second, this theoretical proposition is explored in a french coffee Fair Trade organization
6
Nebe-v, Caron Gerhard. "Analysis of naturally occurring microbial populations from diverse environments." Thesis, Coventry University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323034.
Full text
7
Kryukova, Erin. "A Comparison of Protostars in Diverse Star-Forming Environments." University of Toledo / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1321652769.
Full text
8
Kotila, Letitia E. "The Development of Father Involvement in Diverse Family Environments." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1429538958.
Full text
9
Toseland, Andrew. "Computational analysis of eukaryotic metatranscriptomes from diverse marine environments." Thesis, University of East Anglia, 2013. https://ueaeprints.uea.ac.uk/48778/.
Full textAbstract:
Phytoplankton are photosynthetic microbes that form the basis of the marine food web and are estimated to produce over half of all oxygen in the Earth's atmosphere. Recent advances in high-throughput DNA sequencing technologies have allowed scientists to sample the set of genes actively transcribed from communities of microbes in-situ. This set of transcripts (the metatranscriptome) provides a snapshot of actively transcribed genes at the time of sampling, and can provide insights into microbial metabolism and their relationship with their environment. In this thesis we present the computational analysis of eukaryotic phytoplankton metatranscriptome data sampled from representative marine environments; the simulation of metatranscriptome data for benchmarking computational tools; and analysis carried out on a newly sequenced eukaryotic phytoplankton genome. Transcripts a�liated with ribosomal proteins and associated with translation dominated in all but the Equatorial Paci�c metatranscriptome sample. Hierarchical clustering of the metatranscriptome samples by taxa produced two groups: the diatom dominated and the alveolate dominated. However, clustering by Gene Ontology terms clustered the samples by environment type (tropical, temperate and polar), producing a gradient of translation-associated transcripts which increased as the in-situ temperature of the samples decreased. A strong i correlation (R = 0:9) was detected between the relative proportion of transcripts associated with temperature and the in-situ temperature. Laboratory experiments on model diatom species under control conditions con�rmed that as the in-situ temperature decreases, these model diatoms produce more transcripts and consequently more ribosomal proteins. A translational e�ciency experiment demonstrated that the rate of translation decreased under low temperatures for a model diatom species. This suggested that the increased production of ribosomes acts as a compensatory mechanism under low temperatures. As more ribosomes require more phosphate-rich rRNAs we hypothesised that this could have an impact on biogeochemical cycles (E.g. the Red�eld ratio of Nitrate (N) to Phosphate (P)). This was modelled by our collaborators from the University of Exeter, who produced a global phytoplankton cell model of resource allocation. They showed how the N:P ratio di�ers across latitudinal temperature zones and predicted the impact of increasing temperature on global N:P.
10
Burke, Peter. "Scheduling in dynamic environments." Thesis, University of Strathclyde, 1989. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21291.
Full textAbstract:
Much of the work in the area of automated scheduling systems is based on the assumption that the intended execution environment is static and deterministic. The work presented in this thesis is motivated by recognition of the fact that most real world scheduling environments are dynamic and stochastic. It views the scheduling task as one of satisfaction rather than optimisation, and maintenance over creation. This thesis reviews existing work in the area and identifies an opportunity to combine recent advances in scheduling technology with the power of distributed processing. Within a suitable problem-solving architecture it is argued that this combination can help to address the fundamental problems of execudonal uncertainty, conflicting objectives and combinatorial complexity. A scheduling system, DAS, which employs such a problem-solving architecture, is presented. It is distributed, asynchronous and hierarchical, and requires careful management of problem-solving effort. DAS adopts an opportunistic approach to problem-solving and the management of problem-solving effort. The mechanisms which manage problem-solving effort within DAS are also presented. In conclusion it is argued that the architecture and mechanisms presented lend themselves very well to the view taken of the scheduling task.
11
Blom, Kristopher James. "Dynamic, interactive virtual environments." Göttingen Sierke, 2009. http://d-nb.info/992932998/04.
Full text
12
Al-Kiswany, Samer. "Embracing diversity : optimizing distributed storage systems for diverse deployment environments." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44735.
Full textAbstract:
Distributed storage system middleware acts as a bridge between the upper layer applications, and the lower layer storage resources available in the deployment platform. Storage systems are expected to efficiently support the applications’ workloads while reducing the cost of the storage platform. In this context, two factors increase the complexity of the design of storage systems: First, the applications’ workloads are diverse among number of axes: read/write access patterns, data compressibility, and security requirements to mention only a few. Second, storage system should provide high performance within a certain dollar budget.
This dissertation addresses two interrelated issues in this design space. First, can the computational power of the commodity massively multicore devices be exploited to accelerate storage system operations without increasing the platform cost? Second, is it possible to build a storage system that can support a diverse set of applications yet can be optimized for each one of them?
This work provides evidence that, for some system designs and workloads, significant performance gains are brought by exploiting massively multicore devices and by optimizing the storage system for a specific application. Further, my work demonstrates that these gains are possible while still supporting the POSIX API and without requiring changes to the application. Finally, while these two issues can be addressed independently, a system that includes solutions to both of them enables significant synergies.
13
Wang, Yongqiang. "Model-based approaches to robust speech recognition in diverse environments." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709461.
Full text
14
Koulouvari, Panagiota. "Organizational learning in dynamic environments." Doctoral thesis, KTH, Numerical Analysis and Computer Science, NADA, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3109.
Full text
15
Linington, Ian. "Quantum optics with dynamic environments." Thesis, University of Sussex, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.442428.
Full text
16
Carvalho, Jonathan Gabriel Oliveira. "Distributed mobility in dynamic environments." Master's thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/12834.
Full textAbstract:
Mestrado em Engenharia Eletrónica e Telecomunicações<br>Conventional networks have implemented a specific hierarchical structure, which in many cases deals with centralized mobility anchoring models to ensure IP session continuity. In this context, mobility management demands the existence of a centralized and static anchor point to allow reachability to mobile nodes connected to distinct networks. However, such centralized element is a single point of failures, introducing longer delays and higher management signalling. It may be more vulnerable to attacks, causing problems in the system. For this reason, mobility management addressed to centralized models is a satisfactory and non-optimal solution when mobile networks become less hierarchical. In order to improve mobility management to meet the requirements in mobile network evolution, there have been proposed solutions to distribute the anchor points closer to the end-user. This way, distributed and dynamic mobility anchoring improves scalability and availability, avoiding single points of failure and bottlenecks, as well as enabling transparent mobility support. In this framework, it is idealized and implemented a set of Vehicular scenarios using two different types of mobility management models, one centralized and another distributed. The results shows that the distributed mobility management protocol provides better results in terms of data loss, average data delay, data cost and signaling cost, when compared with the centralized mobility management protocol.
The rapid growth of mobile nodes has lead to the increase of mobile data traffic consumption, and they are currently equipped with multiple network interfaces, which in many cases use different access technologies simultaneously.
Therefore, session continuity of a certain user's services should be guaranteed independently of the access network technology. Consequently, there is a fundamental change in the network architectures, which is adopting flatten model to cope with users' behaviour and the evolution of the mobile data traffic consumption. Thus, it is specified a distributed mobility management scheme with multihoming support to provide continuity to active sessions when mobile nodes roam between networks/interfaces. This mobility mechanism is evaluated and tested in a real environment, demonstrating
the capability to provide uninterrupted sessions for multihomed scenarios, such as the addition/removal of a link, likewise the capability to improve user experience.<br>As redes de telecomunicações sem fios convencionais têm implementada uma estrutura hierárquica específica que em muitos casos lida com entidades centralizadas para garantirem continuidade de sessão e acessibilidade nas comunicações IP. Neste contexto, a gestão de mobilidade exige que haja uma âncora central e estática para permitir que os nós móveis se encontrem acessíveis quando conectados nas diferentes redes. Porém, este elemento central é suscetível a falhas introduzindo maiores atrasos, exigindo uma maior gestão da sinalização, sendo mais vulnerável a ataques o que pode causar problemas no sistema. Por estas razões, à medida que as redes móveis se tornam cada vez menos hierárquicas, a gestão da mobilidade baseada em modelos centralizados torna-se menos otimizada. Para melhorar a gestão de mobilidade tendo em consideração as exigências evolutivas da rede, têm vindo a ser propostas soluções para distribuir as âncoras, colocando-as mais perto do utilizador final com o objetivo de tornar a rede menos hierárquica, descentralizando o processo de gestão de mobilidade de uma forma dinâmica pelos nós da rede. Desta forma, a mobilidade distribuída em ambientes dinâmicos melhora a escalabilidade, acessibilidade e evita pontos centrais de falhas e engarrafamentos. Neste contexto, são idealizados e implementados três cenários de redes veiculares usando dois modelos de gestão de mobilidade, um centralizado e outro distribuído. Os resultados mostram que o protocolo de gestão de mobilidade distribuído apresenta melhores resultados em termos de perda de pacotes, atraso médio por pacote, custo de dados e custo de sinalização quando comparado com o protocolo de gestão de mobilidade centralizado.
O rápido crescimento de nós móveis tem levado ao aumento do consumo de trafego de dados e, atualmente, estes estão equipados com múltiplas interfaces que, em muitos casos, utilizam diferentes tecnologias de acesso à rede. No entanto, a continuidade de sessão de um determinado serviço deve ser garantido, independentemente da tecnologia de acesso utilizada. Consequentemente, há uma preocupação em transformar a arquitetura da rede em modelos menos hierárquicos para lidar com o comportamento dos utilizadores e com a evolução do consumo de tráfego de dados móveis. Desta forma, é especificado um esquema de gestão de mobilidade distribuída com suporte a múltiplas interfaces para manter continuidade de sessões quando os nós móveis mudam de rede ou interface. Este mecanismo de mobilidade foi avaliado e testado num cenário real, demonstrando a capacidade de manter as sessões ativas em cenários com múltiplas interfaces melhorando
a experiência do utilizador, dando como exemplo cenários de perda de ligação, ligação a outras redes e ligar/desligar uma interface.
17
Schmitt, Anita Maria. "Gifted students in diverse environments an analysis of interactions and perceptions /." [Pensacola, Fla.] : University of West Florida, 2009. http://purl.fcla.edu/fcla/etd/WFE0000160.
Full text
18
Sfarlea, Iulia. "Isolation and characterisation of indigenous actinobacteria from diverse South African environments." Master's thesis, University of Cape Town, 2010. http://hdl.handle.net/11427/16396.
Full textAbstract:
One soil sample and various indigenous plant and seaweed samples were used to isolate actinobacteria, with a particular focus on isolating rarer actinobacteria (non-Streptomyces species). A total of 169 putative actinobacterial strains was isolated, of which 42 were selected, based on their morphology, for further identification using a rapid molecular identification method and/or 16S rRNA gene sequence analysis. This includes seven strains isolated from various plant and seaweed samples. A total of 28 non-Streptomyces species was identified, with 23 being isolated from the soil sample, four isolated as plant endophytes (strains SM3BL 1, YPC1, YPC2 and YPL 1), and one isolated as a seaweed epiphyte (Y2UE1). Two Streptomyces species were isolated as endophytes (with strain SC1 isolated from a seaweed sample, and YMH1 isolated a plant species). Forty-two strains, including all non-Streptomyces species, were screened for their antibacterial activity against Mycobacterium aurum A+. Six strains showing promising antibacterial activity were selected for antibiotic extraction. The strains were also investigated for their antibiotic biosynthetic potential by PCR screening for the genes for ansamycin, glycopeptide and Type II (aromatic) polyketide antibiotics. Amplification of the AHBA synthase gene (ansamycin biosynthesis) was achieved for strains SE22 and YPC1. Strains SE22 and YMH1 were positive for the presence of the KSα-KSβ gene pair, with strain SE22 potentially producing a Type II (aromatic) polyketide. The gene product of isolate YMH1 was identified as a spore pigment gene. Antibiotic extraction was successful for strains SE22 and YM55, with numerous active compounds isolated from strain SE22, and one active compound isolated from strain YM55. Fifteen strains were selected for full characterisation based on their isolation source, their identification to non-Streptomyces genera and/or their antibacterial activity. These included four Micromonospora strains, three Kribbella strains, three Streptomyces strains, one Actinomadura strain, one Kineococcus strain, one Nocardia strain, one Nonomuraea strain and one Verrucosispora strain. Two previously isolated Microbispora strains were also characterised. The 17 strains were subjecte d to 16S rRNA gene sequence analysis to determine their closest phylogenetic relatives. The use of gyrB gene based phylogeny was also investigated for the two Microbispora isolates, resulting in a more stable phylogenetic tree. However, differences observed between the 16S rRNA and gyrB gene tree topologies suggest that horizontal gene transfer has occurred within the genus. The 17 isolates were distinguished from their closest phylogenetic neighbours through morphological and physiological characteristics. It is likely that the majority of the isolates are novel, although 16 isolates will require DNA-DNA hybridisation studies to determine if they are new species. Actinomadura strain YPC2 may be proposed as a novel species without the need for DNA-DNA hybridisation.
19
Cao, Jie. "Stochastic inventory control in dynamic environments." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0011469.
Full text
20
Bennewitz, Maren. "Mobile robot navigation in dynamic environments." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=971778329.
Full text
21
Loyet, Raphaël. "Dynamic sound rendering of complex environments." Phd thesis, Université Claude Bernard - Lyon I, 2012. http://tel.archives-ouvertes.fr/tel-00995328.
Full textAbstract:
De nombreuses études ont été menées lors des vingt dernières années dans le domaine de l'auralisation.Elles consistent à rendre audible les résultats d'une simulation acoustique. Ces études se sont majoritairementfocalisées sur les algorithmes de propagation et la restitution du champ acoustique dans desenvironnements complexes. Actuellement, de nombreux travaux portent sur le rendu sonore en tempsréel.Cette thèse aborde la problématique du rendu sonore dynamique d'environnements complexes selonquatre axes : la propagation des ondes sonores, le traitement du signal, la perception spatiale du son etl'optimisation informatique. Dans le domaine de la propagation, une méthode permettant d'analyser lavariété des algorithmes présents dans la bibliographie est proposée. A partir de cette méthode d'analyse,deux algorithmes dédiés à la restitution en temps réel des champs spéculaires et diffus ont été extraits.Dans le domaine du traitement du signal, la restitution est réalisée à l'aide d'un algorithme optimisé despatialisation binaurale pour les chemins spéculaires les plus significatifs et un algorithme de convolutionsur carte graphique pour la restitution du champ diffus. Les chemins les plus significatifs sont extraitsgrace à un modèle perceptif basé sur le masquage temporel et spatial des contributions spéculaires.Finalement, l'implémentation de ces algorithmes sur des architectures parallèles récentes en prenant encompte les nouvelles architectures multi-coeurs et les nouvelles cartes graphiques est présenté.
22
Morrison, Ronald W. "Designing evolutionary algorithms for dynamic environments /." Berlin ; New York ; Paris : Springer, 2004. http://www.springeronline.com/sgw/cda/frontpage/0,11855,1-102-22-29182350-0,00.html?changeHeader=true.
Full text
23
Lattner, Andreas D. "Temporal pattern mining in dynamic environments /." Berlin : Akad. Verl.-Ges. Aka, 2007. http://deposit.d-nb.de/cgi-bin/dokserv?id=2995598&prov=M&dok_var=1&dok_ext=htm.
Full text
24
Johnson, Luke B. "Decentralized task allocation for dynamic environments." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/71458.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2012.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (p. 93-98).<br>This thesis presents an overview of the design process for creating greedy decentralized task allocation algorithms and outlines the main decisions that progressed the algorithm through three different forms. The first form was called the Sequential Greedy Algorithm (SGA). This algorithm, although fast, relied on a large number of iterations to converge, which slowed convergence in decentralized environments. The second form was called the Consensus Based Bundle Algorithm (CBBA). CBBA required significantly fewer iterations than SGA but it is noted that both still rely on global synchronization mechanisms. These synchronization mechanisms end up being difficult to enforce in decentralized environments. The main result of this thesis is the creation of the Asynchronous Consensus Based Bundle Algorithm (ACBBA). ACBBA broke the global synchronous assumptions of CBBA and SGA to allow each agent more autonomy and thus provided more robustness to the task allocation solutions in these decentralized environments.<br>by Luke B. Johnson.<br>S.M.
25
Szenher, Matthew D. "Visual homing in dynamic indoor environments." Thesis, University of Edinburgh, 2008. http://hdl.handle.net/1842/3193.
Full textAbstract:
Our dissertation concerns robotic navigation in dynamic indoor environments using image-based visual homing. Image-based visual homing infers the direction to a goal location S from the navigator’s current location C using the similarity between panoramic images IS and IC captured at those locations. There are several ways to compute this similarity. One of the contributions of our dissertation is to identify a robust image similarity measure – mutual image information – to use in dynamic indoor environments. We crafted novel methods to speed the computation of mutual image information with both parallel and serial processors and demonstrated that these time-savers had little negative effect on homing success. Image-based visual homing requires a homing agent tomove so as to optimise themutual image information signal. As the mutual information signal is corrupted by sensor noise we turned to the stochastic optimisation literature for appropriate optimisation algorithms. We tested a number of these algorithms in both simulated and real dynamic laboratory environments and found that gradient descent (with gradients computed by one-sided differences) works best.
26
Liu, Yong. "Improving network routing performance in dynamic environments." Texas A&M University, 2006. http://hdl.handle.net/1969.1/4745.
Full textAbstract:
In this dissertation, we study methods for improving the routing performance
of computer communication networks in dynamic environments. The dynamic environments
we considered in this work include both network topology changes and
traffic demand changes.
In the first part, We propose a novel fast rerouting scheme for link state routing
protocols. Link state routing protocols are widely used by todayâÂÂs ISPs on their
backbone networks. The global update based rerouting of link state protocols usually
takes seconds to complete which affects real time applications like Voice over IP.
In our scheme, usually, only routers directly connected to failed links are involved
in rerouting. For other cases, only a small number of neighboring routers are also
involved. Since our scheme calculates rerouting paths in advance, rerouting can be
done faster than previous reactive approaches. The computation complexity of our
scheme is less than previous proactive approaches.
In the second part, we study Multihoming Route Control (MRC) that is a technology
used by multihomed stub networks recently. By selecting ISPs with better
quality, MRC can improve routing performance of stub networks significantly.
We first study the stability issue of distributed MRC and propose two methods
to avoid possible oscillations of traditional MRC. The first MRC method is based on âÂÂoptimal routingâÂÂ. The idea is to let the stub networks belonging to a same
organization coordinate their MRC and thus avoid oscillations. The second method
is based on âÂÂuser-optimal routingâÂÂ. The idea is to allow MRC devices to use multiple
paths for traffic to one destination network and switch traffic between paths smoothly
when path quality or the traffic matrix changes.
A third MRC method we propose is for MRC of traffic consisting of TCP flows
of different sizes on paths with bottlenecks of limited capacity. Based on analysis of
quality characteristics of bottleneck links, we propose a greedy MRC approach that
works in small timescales. Simulation results show that the proposed MRC method
can greatly improve routing performance for the MRC sites as well as the overall
routing performance of all sites in the network.
27
Rajala, Johannes. "Dynamic Controllable Mesh Deformation in Interactive Environments." Thesis, Linköpings universitet, Institutionen för teknik och naturvetenskap, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-95302.
Full textAbstract:
The purpose of this project was to research and develop methods for managing the deformation of complex geometric meshes with specific reference to interactive computer games. Bugbear Entertainment has a proven record of accomplishment in the development of car racing games. The creation and management of deformable meshes in real time is a vital component in such games, since it allows the player to visually experience the effect of a real-life car accident. This thesis is meant for people having basic understanding of computer graphics simulation in general, as well as a basic mathematical background for the matrix algebra.
28
Ferrer, Mínguez Gonzalo. "Social robot navigation in urban dynamic environments." Doctoral thesis, Universitat Politècnica de Catalunya, 2015. http://hdl.handle.net/10803/322549.
Full textAbstract:
Deploying mobile robots in social environments requires novel navigation algorithms which are capable of providing valid solutions in such challenging scenarios. The main objective of the present dissertation is to develop new robot navigation approaches able to solve in an intelligent way the navigation problem in urban settings while considering at the same time the interactions with pedestrians, similar to what people easily do with little attention.
Before studying in depth navigation algorithms, this thesis focuses on prediction algorithms to provide a more detailed model of the scene. Understanding human motion in outdoor and indoor scenarios is an appealing requirement to characterize correctly urban settings. Urban environments consist essentially of static obstacles and people, which are treated as dynamic and highly uncertain obstacles. Accordingly, it is mandatory to calculate people's intentions in order to successfully build a human prediction model that generates the corresponding human trajectories and considers their interactions with the environment, such as other pedestrians, static obstacles or even robots.
It is of great interest that service robots can navigate successfully in typical urban environments, which are dynamic and constrained. In addition, people's behavior should not be conditioned by the presence and the maneuvering of robots. To this end, the robot navigation should seek to minimize its impact on the environment, in our case, on people.
This thesis proposes new robot navigation methods that contemplate the social interactions taking place in the scene.
In order to procure more intelligence to the navigation algorithm, we propose to integrate seamlessly the human motion prediction information into a new robot planning approach.
Real experimentation is essential for the validation of the navigation algorithms. As there are real people involved, we must validate the results in real settings since simulation environments have limitations. In this thesis, we have implemented all the prediction and navigation algorithms in our robotic platform and we have provided plenty of evaluations and testings of our algorithms in real settings.<br>Ubicar robots móviles en entornos sociales requiere novedosos algoritmos de navegación que sean capaces de aportar soluciones válidas en éstos exigentes escenarios. El prinicipal objetivo de la presente disertación es el de desarrollar nuevas soluciones para la navegación de robots que sean capaces de resolver, de una manera más inteligente, los problemas de navegación en emplazamientos urbanos, a la vez que se consideran las interacciones con los transeúntes de manera similar a lo que la gente hace fácilmente prestando poca atención. Antes de estudiar en profundidad los algoritmos de navegación, esta tesis se centra en los algoritmos de predicción para proporcionar un modelo más detallado de la escena. Entender el movimiento humando en entornos exteriores e interiores es un requerimiento deseable para caracterizar correctamente emplazamientos urbanos. Los entornos urbanos están consistituídos por muchos objetos dinámicos y altamente impredecibles, la gente. Por lo tanto, es obligatorio calcular las intenciones de la gente para constriur de manera exitosa un modelo de predicción humano que genere las correspondientes trayectorias humanas y considere sus interacciones con el entorno, como otros peatones, obstáculos estáticos o incluso robots. Es de gran interés que los robots de servicios puedan navegar correctamente en entornos típicamente urbanos, que son dinámicos y acotados, además de que el comportamiento de las personas no debería estar condicionado por la presencia y las maniobras de los robots. Con este fin, la navegación de robots debe buscar minimizar su impacto al entorno, en nuestro caso, a la gente. Esta tesis propone nuevos métodos para la navegación de robots que contemplen las interacciones sociales que suceden en la escena. Para proporcionar una navegación más inteligente, proponemos integrar de manera suave el algoritmo de predicción del movimiento humano con un nuevo enfoque de planificación de trayectorias. La experimentación real es esencial para la validación de los algoritmos de navegación. Ya que hay personas reales implicadas, debemos validar los resultados en emplazamientos reales porque el entorno de simulación tiene limitaciones. En esta tesis hemos implementado todos los algoritmos de predicción y de navegación en la plataforma robótica y hemos proporcionado multitud de evaluaciones y pruebas de nuestros algoritmos en entornos reales.
29
Sheng, Quanzheng Computer Science & Engineering Faculty of Engineering UNSW. "Composite web services provisioning in dynamic environments." Awarded by:University of New South Wales. Computer Science and Engineering, 2006. http://handle.unsw.edu.au/1959.4/23457.
Full textAbstract:
Web services composition is emerging as a promising technology for the effective automation of application-to-application collaborations. The application integration problems have been subject of much research in the past years. However, with growth in importance of business process automation and highly dynamic nature of the Internet, this research has taken on a new significance and importance. Adequate solutions to this problem will be very important to make enterprise systems more flexible, robust and usable in the future. In this dissertation, we present a novel approach for the declarative definition and scalable orchestration of composite Web services in large, autonomous, heterogeneous, and dynamic environments. We first propose a composition model for composing Web services in a personalized and adaptive manner. We model composite Web services based on statecharts. To cater for large amounts of dynamic Web services, we use the concept of service community that groups services together and is responsible for the runtime selection of services against user's preferences. We use the concept of process schema that specific users can adjust with their personal preferences. A set of exception handling policies can be specified to proactively react to runtime exceptions. We then propose a tuple space based service orchestration model for distributed, self-managed composite services execution. We introduce the concept of execution controller that is associated with a service and is responsible for monitoring and controlling service executions. The knowledge required by a controller is statically extracted from the specification of personalized composite services. We also present techniques for robust Web services provisioning. The techniques presented in this dissertation are implemented in Self-Serv, a prototype that provides a set of tools for Web service composition and execution. Finally, we conduct an extensive usability and performance study of the proposed techniques. The experimental results reveal that our system i) provides an efficient support for specifying, deploying, and accessing composite services; ii) is more scalable and outperforms the centralized approach when the exchanged messages become bigger; and iii) is more robust and adaptive in highly dynamic environments.
30
Nicholson, Ann Elizabeth. "Monitoring discrete environments using dynamic belief networks." Thesis, University of Oxford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306008.
Full text
31
Chan, Yip-cheung, and 陳葉祥. "Experimental-theoretical interplay in dynamic geometry environments." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B41633921.
Full text
32
Ruchti, Philipp [Verfasser], and Wolfram [Akademischer Betreuer] Burgard. "Robot localization and mapping in dynamic environments." Freiburg : Universität, 2019. http://d-nb.info/1190560860/34.
Full text
33
Chan, Yip-cheung. "Experimental-theoretical interplay in dynamic geometry environments." Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B41633921.
Full text
34
Hirst, Anthony John. "Adaptive evolution in static and dynamic environments." Thesis, Open University, 1998. http://oro.open.ac.uk/57869/.
Full textAbstract:
This thesis provides a framework for describing a canonical evolutionary system. Populations of individuals are envisaged as traversing a search space structured by genetic and developmental operators under the influence of selection. Selection acts on individuals' phenotypic expressions, guiding the population over an evaluation landscape, which describes an idealised evaluation surface over the phenotypic space. The corresponding valuation landscape describes evaluations over the genotypic space and may be transformed by within generation adaptive (learning) or maladaptive (fault induction) local search. Populations subjected to particular genetic and selection operators are claimed to evolve towards a region of the valuation landscape with a characteristic local ruggedness, as given by the runtime operator correlation coefficient. This corresponds to the view of evolution discovering an evolutionarily stable population, or quasi-species, held in a state of dynamic equilibrium by the operator set and evaluation function. This is demonstrated by genetic algorithm experiments using the NK landscapes and a novel, evolvable evaluation function, The Tower of Babel. In fluctuating environments of varying temporal ruggedness, different operator sets are correspondingly more or less adapted. Quantitative genetics analyses of populations in sinusoidally fluctuating conditions are shown to describe certain well known electronic filters. This observation suggests the notion of Evolutionary Signal Processing. Genetic algorithm experiments in which a population tracks a sinusoidally fluctuating optimum support this view. Using a self-adaptive mutation rate, it is possible to tune the evolutionary filter to the environmental frequency. For a time varying frequency, the mutation rate reacts accordingly. With local search, the valuation landscape is transformed through temporal smoothing. By coevolving modifier genes for individual learning and the rate at which the benefits may be directly transmitted to the next generation, the relative adaptedness of individual learning and cultural inheritance according to the rate of environmental change is demonstrated.
35
HERMANN, RODRIGO DE PROENCA GOMES. "AUTOMATIC CAMERA CONTROL IN VIRTUAL DYNAMIC ENVIRONMENTS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2005. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=7646@1.
Full textAbstract:
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR<br>Com o avanço do poder de processamento gráfico e a
popularização dos
jogos eletrônicos, começam a surgir novas formas de
entretenimento, entre
elas a de espectadores de jogos. Os requisitos para o
posicionamento de
câmera para os espectadores visualizarem os jogos são
diferentes dos aplicados
aos jogadores. Enquanto a câmera para os jogadores deve
atender
a requisitos de jogabilidade, a câmera para os
espectadores deve explorar
diferentes ângulos de visualização a fim de aumentar a
imersão no ambiente
dos jogos e explorar a emoção das cenas. O cinema já
evoluiu toda uma
linguagem cinematográfica que potencializa a interpretação
de cenas. Pesquisas
recentes procuram usar a cinematografia na visualização de
jogos.
O principal desafio na adaptação da cinematografia para os
jogos reside na
existência de um ambiente dinâmico, onde não se pode
prever o andamento
da história. Podemos identificar três módulos para a
adaptação da cinematografia
em jogos: roteirista, responsável por identificar o que
está ocorrendo
na cena; diretor/editor, responsável por definir as
melhores tomadas para
capturar a cena; cinegrafista, responsável por posicionar
a câmera no ambiente
dinâmico para melhor atender às demandas do módulo
diretor/editor.
Este trabalho propõe a implementação de um módulo
cinegrafista. A partir
de requisitos para o posicionamento da câmera oriundos de
um módulo externo,
propõe-se um modelo de câmera que faz o posicionamento
automático
da câmera. Os requisitos de posicionamento são expressos
em um conjunto
de restrições que devem ser atendidas pelo modelo de
câmera. A câmera
usa um modelo físico baseado em um sistema de partículas
regido pelo
método de Verlet, empregando o método de relaxação para a
convergência
do sistema a fim de atender às restrições impostas.
Experimentos computacionais
demonstram a capacidade do módulo proposto de atender a
sofisticadas
regras de posicionamento de câmera, baseando-se em
composições
de restrições simples. Princípios da cinematografia, como
enquadramento,
posicionamento e movimento de câmeras, e respeito à linha
de ação, são
facilmente respeitados pelo módulo proposto.<br>With the evolution in graphics processing power and the
popularization
of electronic games, new forms of entertainment, such as
being a game
spectator. The requirements for positioning the camera for
the spectators
to view the games are different from those applied to
players. The camera
for the players must fulfill playability requirements,
while the camera for
the spectators must explore different viewing angles in
order to increase
the immersion in the game environment and to explore the
thrill of the
scenes. The cinema has evolved a whole cinematographic
language that
optimizes the scene interpretation. Recent research has
been seeking to
apply cinematography to game visualization. The main
challenge in the
adaptation of the cinematographic language for games lies
in the existence of
a dynamic environment in which the story`s progress cannot
be anticipated.
Three modules can be identified to adopt the
cinematographic language in
games: screenwriter, responsible for identifying what is
happening in the
scene; director/editor, responsible for defining the best
takes to capture the
scene; and cinematographer, responsible for positioning
the camera in the
dynamic environment to better comply with the
director/editor`s demands.
The present work proposes the implementation of a
cinematographer module.
Based on camera position requirements obtained from an
external module,
we propose a camera model that automatically positions the
camera.
The positioning requirements are expressed by a set of
constraints that must
be respected by the camera model. The camera uses a
physical model based
on a particle system oriented by Verlet`s method, and
employs the relaxation
method to obtain the system`s convergence in order to
comply with imposed
constraints. Computational experiments have demonstrated
the capacity of
the proposed module to comply with sophisticated camera
positioning rules
based on compositions of simple constraints.
Cinematography principles
such as framing, camera position and movement, and
respecting the line of
action are easily accomplished by the proposed module.
36
Walcott, Aisha 1978. "Long-term robot mapping in dynamic environments." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/66468.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2011.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (p. 139-144).<br>One of the central goals in mobile robotics is to develop a mobile robot that can construct a map of an initially unknown dynamic environment. This is often referred to as the Simultaneous Localization and Mapping (SLAM) problem. A number of approaches to the SLAM problem have been successfully developed and applied, particularly to a mobile robot constructing a map of a 2D static indoor environment. While these methods work well for static environments, they are not robust to dynamic environments which are complex and composed of numerous objects that move at wide-varying time-scales, such as people or office furniture. The problem of maintaining a map of a dynamic environment is important for both real-world applications and for the advancement of robotics. A mobile robot executing extended missions, such as autonomously collecting data underwater for months or years, must be able to reliably know where it is, update its map as the environment changes, and recover from mistakes. From a fundamental perspective, this work is important in order to understand and determine the problems that occur with existing mapping techniques for persistent long-term operation. The primary contribution of the thesis is Dynamic Pose Graph SLAM (DPG-SLAM), a novel algorithm that addresses two core challenges of the long-term mapping problem. The first challenge is to ensure that the robot is able to remain localized in a changing environment over great lengths of time. The second challenge is to be able to maintain an up-to-date map over time in a computationally efficient manner. DPG-SLAM directly addresses both of these issues to enable long-term mobile robot navigation and map maintenance in changing environments. Using Kaess and Dellaert's incremental Smoothing and Mapping (iSAM) as the underlying SLAM state estimation engine, the dynamic pose graph evolves over time as the robot explores new areas and revisits previously mapped areas. The algorithm is demonstrated on two real-world dynamic indoor laser data sets, demonstrating the ability to maintain an efficient, up-to-date map despite long-term environmental changes. Future research issues, such as the integration of adaptive exploration with dynamic map maintenance, are identified.<br>by Aisha Naima Walcott.<br>Ph.D.
37
Mondschein, Susana V. "Optimal sales strategies in stochastic, dynamic environments." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/12733.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1993.<br>Includes bibliographical references (leaves 132-134).<br>by Susana V. Mondschein.<br>Ph.D.
38
Kelley, Ian Robert. "Data management in dynamic distributed computing environments." Thesis, Cardiff University, 2012. http://orca.cf.ac.uk/44477/.
Full textAbstract:
Data management in parallel computing systems is a broad and increasingly important research topic. As network speeds have surged, so too has the movement to transition storage and computation loads to wide-area network resources. The Grid, the Cloud, and Desktop Grids all represent different aspects of this movement towards highly-scalable, distributed, and utility computing. This dissertation contends that a peer-to-peer (P2P) networking paradigm is a natural match for data sharing within and between these heterogeneous network architectures. Peer-to-peer methods such as dynamic discovery, fault-tolerance, scalability, and ad-hoc security infrastructures provide excellent mappings for many of the requirements in today’s distributed computing environment. In recent years, volunteer Desktop Grids have seen a growth in data throughput as application areas expand and new problem sets emerge. These increasing data needs require storage networks that can scale to meet future demand while also facilitating expansion into new data-intensive research areas. Current practices are to mirror data from centralized locations, a technique that is not practical for growing data sets, dynamic projects, or data-intensive applications. The fusion of Desktop and Service Grids provides an ideal use-case to research peer-to-peer data distribution strategies in a hybrid environment. Desktop Grids have a data management gap, while integration with Service Grids raises new challenges with regard to cross-platform design. The work undertaken here is two-fold: first it explores how P2P techniques can be leveraged to meet the data management needs of Desktop Grids, and second, it shows how the same distribution paradigm can provide migration paths for Service Grid data. The result of this research is a Peer-to-Peer Architecture for Data-Intensive Cycle Sharing (ADICS) that is capable not only of distributing volunteer computing data, but also of providing a transitional platform and storage space for migrating Service Grid jobs to Desktop Grid environments.
39
Westerlund, Andreas. "Sensor-Based Trajectory Planning in Dynamic Environments." Thesis, Linköpings universitet, Reglerteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-150040.
Full textAbstract:
Motion planning is central to the efficient operation and autonomy of robots in the industry. Generally, motion planning of industrial robots is treated in a two-step approach. First, a geometric path between the start and goal position is planned where the objective is to achieve as short path as possible together with avoiding obstacles. Alternatively, a pre-defined geometric path is provided by the end user. Second, the velocity profile along the geometric path is calculated accounting for system dynamics together with other constraints. This approach is computationally efficient, but yield sub-optimal solutions as the system dynamics is not considered in the first step when the geometric path is planned. In this thesis, an alternative to the two-step approach is investigated and a trajectory planner is designed and implemented which plans both the geometric path and the velocity profile simultaneously. The motion planning problem is formulated as an optimal control problem, which is solved by a direct collocation method where the trajectory is parametrised by splines, and the spline nodes and knots are used as optimization variables. The implemented trajectory planner is evaluated in simulations, where the planner is applied to a simple planar elbow robot and ABB's SCARA robot IRB 910SC. Trade-off between computation time and optimality is identified and the results indicate that the trajectory planner yields satisfactory solutions. On the other hand, the simulations indicate that it is not possible to apply the proposed method on a real robot in real-time applications without significant modifications in the implementation to decrease the computation time.
40
Saltos, Atiencia Ramiro Javier. "Soft-clustering in static and dynamic environments." Tesis, Universidad de Chile, 2016. http://repositorio.uchile.cl/handle/2250/142058.
Full textAbstract:
Doctor en Sistemas de Ingeniería<br>En la actualidad, el entorno macro y micro económico en el cual op eran las empresas está
cambiando constantemente y a gran velo cidad. Esto se deb e princip almente al auge de las
nuevas tecnologías, la revolución de la información y la gran facilidad con la que ahora p o demos comu nicarnos con cualquier parte d el mundo. Debido a la gran canti dad de información
que está siendo generada segundo tras segundo, junto con la facilidad con la que se puede
acceder a ella, la minería de datos y la investigación de op eracion es se han convertido en
una de las herramientas más imp ortantes para desarrollar sistemas de ap oyo a la toma de
decisiones en to dos los niveles. La imp ortancia del traba jo conjunto de ambas disciplinas
radica en la faci lidad relativa con la que extraen cono cimiento de enormes bases de datos y
la utilizan para optimizar los pro cesos organizacionales relevantes.
En particular, para la min ería de datos, estos hechos h an provo cado qu e las bases de datos
sean dinámicas, es decir, el nà omero de datos disponibles crece cada segundo haciendo que
tiempo de vida útil de los modelos se reduzca, haciendo necesario actualizarlos periódicamente de tal forma que encajen con la realidad actual. Lo anterior demanda el desarrollo de
nuevos algoritmos que sean capaces de manejar este tipo de cambios, lo cual ha ido ganando
importancia en los últimos años.
Adicionalmente, la incertidumbre, ambigüedad e imprecisión presentes en los problemas
de la vida real son factores muy importantes a considerar cuando se desarrollan diferentes
algoritmos de minería de datos. La forma más común de lidiar con la incertidumbre viene
dada por la teoría de probabilidad, sin embargo, la ambigüedad e imprecisión han sido dejadas
de lado hasta la aparición de nuevas formas de tratarlas; dos de las cuales son la teoría de
conjuntos " fuzzy" y "rough."
Con las ideas anteriores en mente, en esta tesis, un algoritmo clásico de clustering basado
en support vectors es estudiado profundamente y extendido a una versión rough-fuzzy con
el fin de darle la habilidad de manejar la ambigüedad e imprecisión presente en el mundo
real. Luego de esto, este novedoso algoritmo de soft-computing es generalizado a una versión
dinámica siendo capaz de procesar bases de datos que reciben nueva información con el paso
del tiempo. Finalmente, utilizando como base estos dos algoritmos, un método de detección
de outliers es propuesto como una de las múltiples posibles aplicaciones que resultan de esta
investigación.
En cada capítulo, los experimentos computacionales, resultados y discusión son provistos
enfatizando la contribución que este trabajo de investigación tiene para la sociedad señalando
los futuros desarrollos y posibles campos de aplicación
41
Zheng, Xijia Ph D. Massachusetts Institute of Technology. "Cognitive optical network architecture in dynamic environments." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/126997.
Full textAbstract:
Thesis: Ph. D. in Computer Science and Engineering, Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, May, 2020<br>Cataloged from the official PDF of thesis.<br>Includes bibliographical references (pages 149-154).<br>Emerging network traffic requires a more agile network management and control system to deal with the dynamic network environments than today's networks use. The bursty and large data transactions introduced by new technological applications can cause both high costs and extreme congestion in networks. The prohibitive cost of massive over-provisioning will manifest as huge congestions during peak demand periods. The network management and control system must be able to sense the traffic changes and reconfigure in a timely manner (in tens of milliseconds instead of minutes or hours) to use network resources efficiently. We propose the use of cognitive techniques for fast and adaptive network management and control of future optical networks. The goal of this work is to provide timely network reconfigurations in response to dynamic traffic environments and prevent congestion from building up.<br>We make a simplified model of the expected traffic arrival rate changes as a multistate Markov process based on the characteristics of the dynamic, bursty, and high granularity traffic. The traffic is categorized into different network traffic environments by the length of the network coherence time, which is the time that the traffic is unvarying. The tunneled network architecture is adopted due to its supremacy in reducing the control complexity when the traffic volume is at least one wavelength. In the long coherence time regime where traffic changes very slowly, the traffic detection performances of two Bayesian estimators and a stopping-trial (sequential) estimator are examined, based on the transient behaviors of networks. The stopping trial estimator has the fastest response time to the changes of traffic arrival statistics. We propose a wavelength reconfiguration algorithm with continuous assessment where the system reconfigures whenever it deems necessary.<br>The reconfiguration can involve addition or subtraction of multiple wavelengths. Using the fastest detection and reconfiguration algorithm can reduce queueing delays during traffic surges without over-provisioning and thus can reduce network capital expenditure and prevent wasting resources on erroneous decisions when surges occur. For traffic with moderate coherence time (where traffic changes at a moderate rate) and the short coherence time (where traffic changes quickly), the stopping-trial estimator still responds to the traffic changes with a short detection time. As long as the inter-arrival times of traffic transactions are independent, the algorithm is still optimum. The algorithm provides no prejudice on the exact network traffic distribution, avoiding having to sense and estimate detailed arrival traffic statistics.<br>To deal with fast-changing traffic, we model the transient convergent behaviors of network traffic drift as a result of traffic transition rate changes and validate the feasibility and utility of the traffic prediction. In a simple example when the network traffic rate changes monotonically in a linear model, the sequential maximum likelihood estimator will capture the traffic trend with a small number of arrivals. The traffic trend prediction can help to provide fast reconfiguration, which is very important for maintaining quality of service during large traffic shifts. We further investigate the design of an efficient rerouting algorithm to maintain users' quality of service when the incremental traffic cannot be accommodated on the primary path. The algorithm includes the fast reconfiguration of wavelengths in the existing lit and spatially routed fibers, and the setting up and lighting of new fibers.<br>Rerouting is necessary to maintain users' quality of service when the queueing delay on the primary path (determined by shortest path routing) exceeds the requirement. Our algorithm triggers reconfiguration when a queueing delay threshold is crossed on the primary path. The triggering by a threshold on the queueing delay is used due to its simplicity, and it is directly measurable by the exact traffic transaction sizes and the queue size, which reflect both the current network traffic environment and the network configurations. A dynamic rerouting algorithm implemented with a shortest path algorithm is proposed to find the secondary paths for rerouting. We make the conjecture that it is desirable that the alternate paths for rerouting have small numbers of hops and are disjoint with other busy paths when the hops on the path are independent. In addition, the conjecture suggests that a good candidate network topology should have high edge-connectivity.<br>Wavelength reservation for rerouted traffic does not maximize wavelength utilization. We make the conjecture that traffic with different sizes should be broken up into multi-classes with dedicated partitioned resources and the queueing delay should be normalized by the transmission time for rerouting triggering to realize better network utilization.<br>by Xijia Zheng.<br>Ph. D. in Computer Science and Engineering<br>Ph.D.inComputerScienceandEngineering Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science
42
Yamauchi, Brian Masao. "Exploration and spatial learning in dynamic environments." Case Western Reserve University School of Graduate Studies / OhioLINK, 1995. http://rave.ohiolink.edu/etdc/view?acc_num=case1058450714.
Full text
43
Wei, Pihui. "Dynamic Bug Detection in TinyOS Operating Environments." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1238166929.
Full text
44
Bonnevie, Rodrigue. "Long-Term Exploration in Unknown Dynamic Environments." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-289219.
Full textAbstract:
In order for autonomous robots to perform tasks and safely navigate environments they need to have a reliable and detailed map. These maps are generally created by the robot itself since maps with the required level of detail rarely exist beforehand. In order to create that map the robot has to explore an unknown environment. Such activity is referred to as autonomous exploration within the field of robotics. Most research done in autonomous exploration assumes a static environment. Since most environments in the real world often changes over time an exploration algorithm that is able to re-explore areas where changes may occur is of interest for autonomous long term missions. This thesis presents a method to predict where changes may occur in the environment using Markov chains and an occupancy grid map. An exploration algorithm is also developed with the aim of keeping an updated map of a changing environment. The exploration algorithm is based on a static exploration algorithm that uses RRT? to sample poses and evaluates these poses based on the length of the path to get there and the information gain at and on the path to the sampled pose. An evaluation of both the mapping and exploration is made respectively. The mapping is evaluated on its ability of suppressing noisy measurements whilst being able to accurately model the dynamics of the map. The exploration algorithm is evaluated in three different environments of increasing complexity. Its ability to seek out areas susceptible of change whilst providing data for the mapping is evaluated in each environment. The results show both a mapping and exploration algorithm who works well but are noise sensitive.<br>För att autonoma robotar ska kunna utföra handlingar och tillförlitligt kunna navigera i sin omvärld så behöver de en pålitlig och detaljerad karta. Dessa kartor är oftast generade av roboten själv då det sällan finns kartor som uppfyller dessa krav. För att skapa dessa kartor så behöver roboten kunna utforska okända miljöer och kartlägga dessa. Detta kallas autonom utforskning inom mobil robotik. Det mesta av forskningen som är gjord inom detta antar att miljön är statisk och inte förändrar sig men eftersom detta sällan är fallet i verkligheten så kan utforskning och återutforskning av dynamiska miljöer vara av intresse, särskilt för robotar som skall vara aktiva i samma miljö under en längre tid. Denna rapport presenterar en metod att förutspå förändringar i en miljö med hjälp av Markovkedjor och occupancy grid kartor samt en utforskningsalgoritm vars mål är att hålla en uppdaterad version av en dynamisk miljö. Utforskningsalgoritmen är baserad på en sådan anpassad för en statisk miljö som använder RRT? för att välja ut positioner och orienteringar för roboten. Dessa evalueras baserat på sträckan för att komma dit och den nya informationen som kan observeras där och på vägen dit. En evaluering av både kartläggning och utforskning är gjord. Kartläggningen är evaluerad på dess förmåga att hantera brus i mätningarna samtidigt som den behåller en bra representation av de dynamiska aspekterna i miljön. Utforskningsalgorithmen är testad i tre olika miljöer av olika komplexitet. Dess förmåga att upptäcka och utforska områden med ökad sannolikhet för förändring och samtidigt förse kartläggningen med data för att modellera miljön och dess dynamik är det som evalueras i experimenten. Resultaten visar att både kartläggning och utforskningsalgoritmen fungerar bra men båda är känsliga för mätbrus.
45
Stanley, Jordan D. "Optimal Seeding Rates for New Hard Red Spring Wheat Cultivars in Diverse Environments." Diss., North Dakota State University, 2019. https://hdl.handle.net/10365/30667.
Full textAbstract:
Seeding rate in hard red spring wheat (HRSW) (Triticum aestivum L.) production impacts input cost and grain yield. Predicting the optimal seeding rate (OSR) for HRSW cultivars can aid growers and eliminate the need for costly seeding rate research. Research was conducted to determine the OSR of newer HRSW cultivars (released in 2013 or later) in diverse environments. Nine cultivars with diverse genetic and phenotypic characteristics were evaluated at four seeding rates in 11 environments throughout the northern Great Plains region in 2017-2018. Results from ANOVA indicated environment and cultivar were more important than seeding rate in determining grain yield. Though there was no environment x seeding rate interaction (P=0.37), OSR varied among cultivar within each environment. Cultivar x environment interactions were further explored with the objective of developing a decision support system (DSS) to aid growers in determining the OSR for the cultivar they select, and for the environment in which it is sown. Data from seeding rate trials conducted in ND and MN from 2013-2015 were also used. A novel method for characterizing cultivar for tillering capacity was developed and proposed as a source for information on tillering to be used in statistical modelling. A 10-fold repeated cross-validation of the seeding rate data was analyzed by 10 statistical learning algorithms to determine a model for predicting OSR of newer cultivars. Models were similar in prediction accuracy (P=0.10). The decision tree model was considered the most reliable as bias was minimized by pruning methods, and model variance was acceptable for OSR predictions (RMSE=1.24). Findings from this model were used to develop the grower DSS for determining OSR dependent on cultivar straw strength, tillering capacity, and yield of the environment. Recommendations for OSR ranged from 3.1 to 4.5 million seeds ha-1. Growers can benefit from using this DSS by sowing at OSR relative to their average yields; especially when seeding new HRSW cultivars.
46
Dabai, Aliyu Ibrahim. "Metagenomic studies on the microbial communities facilitating aromatic hydrocarbons degradation in diverse environments." Thesis, Queen's University Belfast, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.707233.
Full textAbstract:
Metagenomic is a technique that involves the study of environmental DNA and negates the need for cultivation of microorganisms in the laboratory. The techniques have been shown to have tremendous potential for the advancement of knowledge in numerous fields such as microbial ecology, Agriculture, e.t.c. The research question this work seek to address is that ‘can we apply at least one metagenomic approach to demonstrate an improved understanding of the microbiology of a contaminated soil environment. If we can answer this question, then it is possible to develop a rapid approach to confirm whether the soil environment is contaminated, whether aerobic or anaerobic degradation is occurring in the contaminated environment and for crude oil spill characterisation in the Niger Delta. If we combine the information obtained through metagenomic approach with stable isotope probing (Metagenome-SIP), then key anaerobic benzene degrading-bacteria could be identified in the Niger Delta contaminated soil samples. Using the metagenomic-SIP information, we assess whether the same organism degrading benzene under anaerobic condition could degrade a lignin-derived phenolic compound (vanillin). The information will enable us to develop an inexpensive approach for biostimulation approach for the clean-up of the Niger Delta environment using the plant-derived waste material. The key finding of this research work include: the Niger Delta soil samples were contaminated with crude oil, aerobic and anaerobic biodegradation are important in the contaminated site, the contamination is of two class namely one set of soil are newly or freshly contaminated, and the other set is old contaminated site, microbial phyla such as Actinobacteria, Bacteroidetes and Proteobacteria were the most abundant microbial group in the contaminated soils, lllumina data uncovered the diversity of microbial community structure of the contaminated soil environment compared to the amplicon pyrosequencing data, benzene was syntrophically degraded by β-proteobacteria, δ-proteobacteria, and Clostridia while vanillin degradation was by α-Proteobacteria (order Sphingomonadales). These organisms are important in the biodegradation of the benzene and vanillin aromatic compounds, and essential hydrocarbon degradation genes detected the role of these bacteria in the utilization of such compounds. The qPCR gene ratio approach could be used as a diagnostic method for spill characterisation. The knowledge gained from the results will influence any decision towards the clean-up/monitoring of bioremediation strategy to apply on the heavily polluted Niger Delta.
47
Lim, Yusun Lee. "Potential game based cooperative control in dynamic environments." Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39511.
Full textAbstract:
The objectives of this research are to extend cooperative control methods based on potential games to dynamic environments and to develop an experimental test bed to illustrate theoretical results. Cooperative control concerns coordinating a collective performance of multiple autonomous agents. Possible applications include mobile sensor networks, distributed computation, and unmanned vehicle teams. Prior work has explored game theory, specifically the framework of potential games, as an approach to cooperative control, but has been restricted to static environments.
This research shows that potential game based cooperative control also can be applied to dynamic environment problems. The approach is illustrated on three example problems. The first one is a moving target tracking problem using a modified form of the learning algorithm, restrictive log-linear learning. The second example is mobile sensor coverage for an unknown dynamic environment. The last example is multi-agent path optimization using payoff based learning. The performances of the developed systems are studied by simulation. The last part of this thesis develops an experimental moving target tracking system using multiple mobile robots. Finally, the thesis concludes with suggestions for future research directions.
48
Younes, Abdunnaser. "Adapting Evolutionary Approaches for Optimization in Dynamic Environments." Thesis, University of Waterloo, 2006. http://hdl.handle.net/10012/2835.
Full textAbstract:
Many important applications in the real world that can be modelled as combinatorial optimization problems are actually dynamic in nature. However, research on dynamic optimization focuses on continuous optimization problems, and rarely targets combinatorial problems. Moreover, dynamic combinatorial problems, when addressed, are typically tackled within an application context. <br /><br /> In this thesis, dynamic combinatorial problems are addressed collectively by adopting an evolutionary based algorithmic approach. On the plus side, their ability to manipulate several solutions at a time, their robustness and their potential for adaptability make evolutionary algorithms a good choice for solving dynamic problems. However, their tendency to converge prematurely, the difficulty in fine-tuning their search and their lack of diversity in tracking optima that shift in dynamic environments are drawbacks in this regard. <br /><br /> Developing general methodologies to tackle these conflicting issues constitutes the main theme of this thesis. First, definitions and measures of algorithm performance are reviewed. Second, methods of benchmark generation are developed under a generalized framework. Finally, methods to improve the ability of evolutionary algorithms to efficiently track optima shifting due to environmental changes are investigated. These methods include adapting genetic parameters to population diversity and environmental changes, the use of multi-populations as an additional means to control diversity, and the incorporation of local search heuristics to fine-tune the search process efficiently. <br /><br /> The methodologies developed for algorithm enhancement and benchmark generation are used to build and test evolutionary models for dynamic versions of the travelling salesman problem and the flexible manufacturing system. Results of experimentation demonstrate that the methods are effective on both problems and hence have a great potential for other dynamic combinatorial problems as well.
49
Firouzi, Hadi. "Visual non-rigid object tracking in dynamic environments." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44629.
Full textAbstract:
This research presents machine vision techniques to track an object of interest visually in an image sequence in which the target appearance, scale, orientation, shape, and position may significantly change over time. The images are captured using a non-stationary camera in a dynamic environment in a gray-scale format, and the initial location of the target is given.
The contributions of this thesis include the introduction of two robust object tracking techniques and an adaptive similarity measure which can significantly improve the performance of visual tracking.
In the first technique, the target is initially partitioned into several sub-regions, and subsequently each sub-region is represented by two distinct adaptive templates namely immediate and delayed templates. At every tracking step, the translational transformation of each sub-region is preliminarily estimated using the immediate template by a multi-start gradient-based search, and then the delayed template is employed to correct the estimation. After this two-step optimization, the target is tracked by robust fusion of the new sub-region locations. From the experiments, the proposed tracker is more robust against appearance variance and occlusion in comparison with the traditional trackers.
Similarly, in the second technique the target is represented by two heterogeneous Gaussian-based templates which models both short- and long-term changes in the target appearance. The target localization of the latter technique features an interactive multi-start optimization that takes into account generic transformations using a combination of sampling- and gradient-based algorithms in a probabilistic framework.
Unlike the two-step optimization of the first method, the templates are used to find the best location of the target, simultaneously.
This approach further increases both the efficiency and accuracy of the proposed tracker.
Lastly, an adaptive metric to estimate the similarity between the target model and new images is proposed. In this work, a weighted L2-norm is used to calculate the target similarity measure. A histogram-based classifier is learned on-line to categorize the L2-norm error into three classes which subsequently specify a weight to each L2-norm error. The inclusion of the proposed similarity measure can remarkably improve the robustness of visual tracking against severe and long-term occlusion.
50
Fåk, Joel, and Tomas Wilkinson. "Autonomous Mapping and Exploration of Dynamic Indoor Environments." Thesis, Linköpings universitet, Reglerteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-97609.
Full textAbstract:
This thesis describes all the necessary parts needed to build a complete system for autonomous indoor mapping in 3D. The robotic platform used is a two-wheeled Segway, operating in a planar environment. This, together with wheel odometers, an Inertial Measurement Unit (IMU), two Microsoft Kinects and a laptop comprise the backbone of the system, which can be divided into three parts: The localization and mapping part, which fundamentally is a SLAM (simultaneous localization and mapping) algorithm implemented using the registration technique Iterative Closest Point (ICP). Along with the map being in 3D, it also designed to handle the mapping of dynamic scenes, something absent from the standard SLAM design. The planning used by the system is twofold. First, the path planning - finding a path from the current position to a destination - and second, the target planning - determining where to go next given the current state of the map and the robot. The third part of the system is the control and collision systems, which while they have not received much focus, are very necessary for a fully autonomous system. Contributions made by this thesis include: The 3D map framework Octomap is extended to handle the mapping of dynamic scenes; A new method for target planning, based on image processing is presented; A calibration procedure for the robot is derived that gives a full six degree of freedom pose for each Kinect. Results show that our calibration procedure produces an accurate pose for each Kinect, which is crucial for a functioning system. The dynamic mapping is shown to outperform the standard occupancy grid in fundamental situations that arise when mapping dynamic scenes. Additionally, the results indicate that the target planning algorithm provides a fast and easy way to plan new target destinations. Finally, the entire system’s autonomous mapping capabilities are evaluated together, producing promising results. However, it also highlights some problems that limit the system’s performance such as the inaccuracy and short range of the Kinects or noise added and reinforced by the multiple subsystems<br>Detta exjobb beskriver delarna som krävs för att för bygga ett komplett system som autonomt kartlägger inomhusmiljöer i tre dimensioner. Robotplattformen är en Segway, som är kapabel att röra sig i ett plan. Segwayn, tillsammans med en tröghetssensor, två Microsoft Kinects och en bärbar dator utgör grunden till systemet, som kan delas i tre delar: En lokaliserings- och karteringsdel, som i grunden är en SLAM-algoritm (simultan lokalisering och kartläggning) baserad på registreringsmetoden Iterative Closest Point (ICP). Kartan som byggs upp är i tre dimensioner och ska dessutom hantera kartläggningen av dynamiska miljöer, något som orginalforumleringen av SLAM problemet inte klarar av. En automatisk planeringsdel, som består av två delar. Dels ruttplanering som går ut på att hitta en väg från sin nuvarande position till det valda målet och dels målplanering som innebär att välja ett mål att åka till givet den nuvarande kartan och robotens nuvarande position. Systemets tredje del är regler- och kollisionssystemen. Dessa system har inte varit i fokus i detta arbete, men de är ändå högst nödvändiga för att ett autonomt system skall fungera. Detta examensarbete bidrar med följande: Octomap, ett ramverk för kartläggningen i 3D, har utökats för att hantera kartläggningen av dynamiska miljöer; En ny metod för målplanering, baserad på bildbehandling läggs fram; En kalibreringsprocedur för roboten är framtagen som ger den fullständiga posen i förhållande till roboten för varje Kinect. Resultaten visar att vår kalibreringsprocedur ger en nogrann pose for för varje Kinect, vilket är avgörande för att systemet ska fungera. Metoden för kartläggningen av dynamiska miljöer visas prestera bra i grundläggande situationer som uppstår vid kartläggning av dynamiska miljöer. Vidare visas att målplaneringsalgoritmen ger ett snabbt och enkelt sätt att planera mål att åka till. Slutligen utvärderas hela systemets autonoma kartläggningsförmåga, som ger lovande resultat. Dock lyfter resultat även fram problem som begränsar systemets prestanda, till exempel Kinectens onoggranhet och korta räckvidd samt brus som läggs till och förstärks av de olika subsystemen.