• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 69
  • 20
  • 18
  • 14
  • 7
  • 7
  • 5
  • 5
  • 3
  • 3
  • 2
  • 1
  • 1
  • Tagged with
  • 175
  • 23
  • 21
  • 18
  • 17
  • 16
  • 15
  • 15
  • 14
  • 14
  • 13
  • 11
  • 11
  • 11
  • 10
  • 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.
21

Dual control of linear stochastic systems with unknown parameters

Chen, Rong January 1990 (has links)
No description available.
22

Force and impact control for robot manipulators with unknown dynamics and disturbances

Lee, Eunjeong January 1994 (has links)
No description available.
23

A Study of the Effects of Two Reading Environments on L2 Readers’ Strategic Behaviors Toward Unknown Words

Lee, Sang Kyo 09 September 2010 (has links)
No description available.
24

Décision collective optimisée en milieu opérationnel extrême, application aux situations inconnues en vol spatial habité / Optimised collective decision in extreme and operational environment, application to the unknown situations in human space flight

L'Haridon, Damien 02 May 2019 (has links)
Les situations inconnues, i.e. jamais rencontrées ni anticipées, peuvent survenir lors de missions aérospatiales, comme dans le cas de la mission Apollo 13. Ainsi, l’équipage du premier vol habité vers Mars traitera probablement des situations inconnues (Orasanu, 2005) dans cet environnement potentiellement contraint, volatil et extrême tout en étant isolé de l’aide du centre de contrôle sol du fait des délais de communication. Or, un équipage ne peut pas être entrainé à traiter toutes les situations et a fortiori les situations inconnues (Noe, Dachner, Saxton et Keeton, 2011). Le présent travail de recherche est donc centré sur l’amélioration de la performance opérationnelle collective face à une situation inconnue en vol spatial habité vers Mars.La littérature étudiée (McLennan, Holgate, Omodei et Wearing, 2006 ; Noe et al., 2011) indique qu’une équipe partageant des expériences augmente sa compétence. En revanche, soit cette littérature est centrée sur une activité précise, soit elle ne discrimine pas les différents types d’expérience. De plus, la préparation d’une équipe pour réagir à une situation inconnue n’est pas abordée dans cette littérature. Potentiellement influencée par le partage d’expériences au niveau collectif, la métacognition est un levier reconnu d’augmentation de la performance en résolution de problèmes. La métacognition est définie comme la cognition sur la cognition (Flavell, 1979) et est modélisée en différentes étapes de raisonnement lors de résolutions de problèmes. Néanmoins, il n’est pas établi de lien entre d’une part le suivi de ces étapes ou leur mélange entre elles (i.e. la netteté métacognitive) et d’autre part l’amélioration de la performance opérationnelle collective en résolution de problème.Pour répondre à ces problématiques, un protocole spécifique (LETUCA) a été conduit durant vingt mois. Trois équipes stables ont été mises à l’épreuve de douze problèmes conçus pour ce travail ou adaptés de la littérature. La première a partagé un maximum d’expériences, la deuxième était constituée d’équipiers vivant les mêmes expériences, mais majoritairement séparément. La troisième n’a pas vécu d’expérience particulière. Ces trois équipes sont caractérisées selon les qualités des expériences vécues relativement à un entrainement fictif à l’inconnu. Ces qualités sont déterminées par des professionnels pouvant faire face collectivement à des situations inconnues.Les résultats obtenus soutiennent l’existence d’un lien entre le partage d’expériences diversifiées et de qualité et la performance opérationnelle collective en résolution de problèmes inconnus. L’étude de la métacognition permet de préciser ce lien : aucune relation n’est établie entre la performance et le suivi ou non du modèle de métacognition retenu. En revanche, un lien est confirmé entre les hautes valeurs de netteté métacognitive et l’augmentation de la performance opérationnelle. Finalement, l’ensemble des résultats permet de construire un modèle métacognitif collectif empirique en résolution de problème. / Unknown situations, i.e. neither expected nor experienced, may happen during aerospace missions; notably, like in the case of the Apollo 13 mission. Then, the crew of the first manned flight to Mars will probably treat unknown situations (Orasanu, 2005) in this potentially constrained, volatile, and extreme environment whilst being isolated from ground control support due to communication delays. Yet, a crew cannot be trained to treat all situations, including the unknown situations (Noe, Dachner, Saxton et Keeton, 2011). The present research work deals with the improvement of the operational and collective performance while coping with an unknown situation during a manned space flight toward Mars.The studied literature (McLennan, Holgate, Omodei et Wearing, 2006; Noe et al., 2011) indicates that a team sharing experiences increases its skill. However, either this literature is focused on a precise activity or it does not discriminate the different types of experience. Moreover, the training of a team to react to an unknown situation is not discussed in this literature. Potentially influenced by experience sharing at collective level, the metacognition is a recognized lever to improve performance during problem resolutions. Metacognition is defined as cognition about cognition (Flavell, 1979) and is modeled into different reasoning steps during problem resolutions. Nonetheless, no link is established between on one side the follow-up of these steps or their possible mixture (i.e. metacognitive clearness) and, on the other side, the increase of the collective operational performance during problem resolutions.To deal with these problematics, a specific protocol (LETUCA) was build and applied during twenty months. Three stable teams coped with twelve problems designed for this study or adapted from the literature. The first one shared a maximum of experiences; the second one was formed with teammates living the same experiences, but mainly separately from each other. The third team did not live specific experience. These three teams are characterized according to the lived experiences’ qualities relative to a fictive training to the unknown. These qualities are determined by professionals that may face collectively unknown situations.The obtained results support the existence of a relation between the sharing of quality and diversity experiences and the collective operational performance during unknown problem resolutions. The study of metacognition enables to specify this relation: no link is established between the operational performance and the tracking or not of the selected metacognitive model. However, a relation is confirmed between high metacognitive clearness values and the operational performance’s increase. Finally, the results enable the construction of an empirical model of collective metacognition during problem resolution.
25

Health Assessment of Three Dimensional Large Structural Systems Using Limited Uncertain Dynamic Response Information

Das, Ajoy Kumar January 2012 (has links)
A novel system identification (SI)-based structural health assessment (SHA) procedure has been developed integrating several theoretical and implementation aspects. The procedure assesses health of structures using limited noise-contaminated dynamic responses and without using input excitation information. Since most practical structures are three dimensional (3D), the procedure has been developed for general 3D structures, represented by finite elements (FEs). The procedure identifies defects by tracking the changes in the stiffness of the elements in the FE representation. Once a defective element is identified, defect spot can be identified accurately within the defective element. The procedure is denoted as 3D Generalized Iterative Least-Squares Extended Kalman Filter with Unknown Input (3D GILS-EKF-UI) and implemented in two stages. In Stage 1, based on the available responses, substructure(s) are selected and the 3D GILS-UI procedure is used to generate the unknown input excitation, stiffness parameters of the elements in the substructure, and two Rayleigh damping coefficients. Using information from Stage 1, stiffness parameters for the whole structure are identified using EKF with Weighted Global Iteration (EKF-WGI) in Stage 2. The procedure accurately identified defect-free and defective states of various 3D structures using only analytically generated limited responses. To increase the robustness, 3D GILS-EKF-UI has been extended to develop an integrated structural health assessment strategy, denoted as Iterative Least-Squares Extended Kalman Filter with Unknown Input and Advanced Digital Integration Technique (ILS-EKF-UI-ADIT). The procedure has been implemented in three stages. In Stage 1, an advanced digital integration technique (ADIT) is implemented for post-processing of noise-contaminated acceleration time-histories, addressing all major challenges of digital integration. It also overcomes non-convergence issue in Stage 2 that arises due to phase-shift and amplitude errors. In Stage 2, substructure(s) are identified using the least-squares procedure. In Stage 3, stiffness parameters for the whole structure are identified using the EKF-WGI procedure. ILS-EKF-UI-ADIT has been verified in presence of relatively large noise in the acceleration time-histories, measured at small part(s) of defect-free and defective structures, without using excitation information. The SHA procedure is robust and has the potential to be applied for the health assessment, maintenance, retrofitting, and life extension of existing structural systems.
26

Validation of a Gene-Expression Based Assay for BRCA1 Function

Uy, PAOLO MIGUEL 26 September 2013 (has links)
Breast cancer is a disease that afflicts a significant proportion of women globally. 5-10% of breast cancer cases are linked to inherited polymorphisms in critical genes such as BRCA1, a tumour suppressor essential for genomic stability. A dysfunctional BRCA1 gene can increase breast cancer risk by 60-80%. Previous microarray analysis established that differential gene expression in unperturbed Epstein-Barr virus transformed lymphocyte cell lines (EBV-LCL) was able to distinguish BRCA1 mutation carriers from controls with a high degree of accuracy. A 43-gene radiation-independent classifier for BRCA1 status was constructed. We hypothesize that this differential gene expression can be observed in a subset of these genes using quantitative PCR (qPCR) in both EBV-LCL and B-lymphocytes isolated from patients with known BRCA1 mutation carrier status. The 43-gene classifier was analyzed using gene ontology analysis and 4 target genes selected based on predictive value, expression intensity and gene ontology similarity. Genes selected were CXCR3, TBX21, MX2, and IFIT1, with GusB as an endogenous reference gene. EBV-LCL established from known BRCA1 mutation carriers and from BRCA1 wildtype individuals were obtained and RT-qPCR (reverse transcriptase qPCR) performed on isolated RNA. Our results showed significant downregulation of CXCR3 and TBX21 in BRCA1 mutation carriers (p=0.018 and p=0.003, respectively), as expected from previous microarray results. IFIT1, while showing a non-significant upregulation (p=0.183), agreed with the expected trend. MX2 did not show significant differential expression. These results indicate that differential gene expression has the potential to accurately distinguish pathogenic variants, even if it may require EBV immortalization of B-lymphocytes. To determine whether the assay could be extended to fresh blood samples, B-lymphocytes were isolated from patients with known BRCA1 mutation carrier status from North York General Hospital in Toronto, ON. An optimized protocol to enrich the B-lymphocyte population using magnetic separation was developed for this purpose. RT-qPCR using RNA isolated from these lymphocytes showed no significant differential gene expression in CXCR3 and TBX21. However, a low sample size, use of non-sequenced controls and a need for further qPCR optimization may call these results into question. In addition, problems with blood sample transportation from off-site sources resulted in an unacceptable drop in RNA integrity. While this gene expression assay may be limited to screening a small number of blood samples, results indicate that may still have clinical relevance that can be explored. This would necessitate further optimization of the qPCR methodology and resolution of the issues surrounding RNA integrity and sample transport. / Thesis (Master, Pathology & Molecular Medicine) -- Queen's University, 2013-09-26 13:13:50.809
27

Procesní postavení osoby neznámého pobytu ve světle "Nařízení Brusel I" / Procedural position of a person whose domicile is unknown in light of "Brussels I Regulation"

Širůčková, Pavlína January 2015 (has links)
Procedural position of a person whose domicile is unknown in light of "Brussels I Regulation" One of the results of the removal of obstacles that previously used to prevent EU citizens from moving into another member state is, among others, an increase in the number of contracts entered into with nationals from other member states. Connected therewith there has been an increase in the number of cases involving a foreign element taken before courts of the member states. Many of those cases are in fact brought against persons whose domiciles are unknown. To be precise, in practice it is defendants on whom it is not possible to serve the process and at the same time the court has no information regarding their domiciles. Not only is it impossible to find out whether they are in the Czech Republic, but the question is whether they are in the EU at all. In such a case it is necessary to consider whether it is possible to apply the rules of Brussels I Regulation, whose operation is based on the principle of domicile of the sued party, for the determination of jurisdiction in proceedings against such defendants. Besides this basic issue the paper also deals with the assessment of whether it is possible to apply, in the proceedings against a person whose domicile is unknown, domestic institutes which are...
28

Estudo de diferentes estruturas de grupos genéticos aditivos visando ao aumento da eficiência de seleção em bovinos de corte / Study of different additive genetic groups structures in order to increase the efficiency of genetic selection in beef cattle

Oliveira Júnior, Gerson Antônio de 22 February 2013 (has links)
A estratégia de criação de grupos genéticos aditivos é uma técnica que permite que animais de paternidade desconhecida tenham seus valores genéticos preditos de forma mais adequada quando incluídos em programas de melhoramento genético. O modo como esses grupos são formados é ainda arbitrário, o que torna importante o estudo de metodologias de formação de grupos genéticos aditivos (GG) visando a uma estrutura apropriada para as avaliações dos rebanhos em programas de melhoramento genético animal. O objetivo do trabalho foi definir a estrutura de grupo genético adequada às avaliações genéticas, comparando-as em relação às mudanças efetivas na eficiência do processo seletivo dos animais com paternidade desconhecida. As características estudadas foram: peso ao desmame, peso ao sobreano, ganho de peso pós-desmama, perímetro escrotal ao sobreano e escore visual de musculosidade ao sobreano. Três cenários foram simulados a partir de um banco de dados composto apenas por animais com pedigree completo (grupo controle). O primeiro teve 30% dos animais com identificação de pai apagada, o segundo 50% e um terceiro com 70%. As estratégias de formação de GG foram: a fazenda de nascimento do animal com paternidade desconhecida; o ano de nascimento (SAFRA) e a concatenação de ano de nascimento e fazenda de nascimento (FAZSAFRA). Os componentes de variância foram calculados para o banco controle pelo software VCE e os valores genéticos foram preditos pelo software PEST, utilizando duas estruturas de modelo animal que se diferenciaram pela inclusão ou não do efeito fixo de GG. A definição da estrutura de grupo genético aditivo adequado à avaliação genética dos animais foi baseada na eficiência de seleção e na comparação entre os valores genéticos preditos quanto aos seus valores absolutos e quanto à classificação dos animais, sendo que animais do grupo controle foram assumidos como tendo o máximo em resposta à seleção genética. Os resultados demonstraram que os grupos genéticos aditivos proporcionam uma melhora na predição genética dos animais com paternidade desconhecida. As estratégias que proporcionaram valores mais próximos aos do grupo controle foram SAFRA e FAZSAFRA e, mesmo com similaridade de valores, a estratégia SAFRA foi superior na seleção dos melhores animais. / The structure of genetic groups is a technique that allows that animals with unknown paternity be included in breeding programs. The ways these groups are formed are still arbitrary, which makes it important to study formation methodologies of genetic groups aiming an appropriate framework for the evaluation of livestock in animal breeding programs. Therefore, the aim of this study was to define the structure of genetic group suited to genetic evaluations, comparing them regarding changes in the effective efficiency of the process of animals with unknown parentage. The characteristics studied were: weaning weight, post-weaning weight, post-weaning weight gain, scrotal circumference at 18 months of age and visual muscularity score at 18 months of age. Three scenarios were simulated from a database consisting only of complete pedigree animals (control group). The first had 30% of animals with identification of father off, the second with 50% and a third with 70%. The training strategies additive genetic groups were: the farm of birth of the animal with unknown parentage; birth year (SAFRA) and the concatenation of year of birth and birth farm (FAZSAFRA). The variance components were calculated for the data bank control program by VCE and breeding values were predicted using PEST software, with two structures of animal models that differ by the inclusion or not of the fixed effect of additive genetic group. The definition of the structure of genetic group suitable for genetic evaluation of animals was based on the efficiency of selection and comparison of estimated breeding values to the \"control\" breeding values and the classification of animals, while control animals were assumed to have the maximum response to selection whereas the choice of any other group of animals results in a reduction thereof. The results demonstrated that the additives genetic groups provide an improvement in the genetic prediction of animals with unknown paternity. Strategies that provided values closer to those of the control group were SAFRA and FAZSAFRA and even with similarity values, strategy SAFRA was superior in selecting the best animals.
29

Adaptive distributed observers for a class of linear dynamical systems

Heydari, Mahdi 29 April 2015 (has links)
The problem of distributed state estimation over a sensor network in which a set of nodes collaboratively estimates the state of continuous-time linear systems is considered. Distributed estimation strategies improve estimation and robustness of the sensors to environmental obstacles and sensor failures in a sensor network. In particular, this dissertation focuses on the benefits of weight adaptation of the interconnection gains in distributed Kalman filters, distributed unknown input observers, and distributed functional observers. To this end, an adaptation strategy is proposed with the adaptive laws derived via a Lyapunov-redesign approach. The justification for the gain adaptation stems from a desire to adapt the pairwise difference of estimates as a function of their agreement, thereby enforcing an interconnection-dependent gain. In the proposed scheme, an adaptive gain for each pairwise difference of the interconnection terms is used in order to address edge-dependent differences in the estimates. Accounting for node-specific differences, a special case of the scheme is presented where it uses a single adaptive gain in each node estimate and which uniformly penalizes all pairwise differences of estimates in the interconnection term. In the case of distributed Kalman filters, the filter gains can be designed either by standard Kalman or Luenberger observers to construct the adaptive distributed Kalman filter or adaptive distributed Luenberger observer. Stability of the schemes has been shown and it is independent of the graph topology and therefore the schemes are applicable to both directed and undirected graphs. The proposed algorithms offer a significant reduction in communication costs associated with information flow by the nodes compared to other distributed Kalman filters. Finally, numerical studies are presented to illustrate the performance and effectiveness of the proposed adaptive distributed Kalman filters, adaptive distributed unknown input observers, and adaptive distributed functional observers.
30

Identificação e análise da função de transferência do circuito equivalente de um sistema de medição por correntes parasitas

Tondo, Felipe Augusto January 2016 (has links)
Este trabalho apresenta o estudo de um sistema genérico de medição que utiliza o princípio das correntes de Foucault, comumente conhecidas como correntes parasitas. O modelo do sistema é representado como um circuito elétrico equivalente composto por R1 e L1, respectivamente caracterizando a resistência e a indutância do circuito primário, as quais são conhecidas por uma bobina de excitação. Já no secundário, R2 e L2, estão representando a perda ôhmica e a indutância da amostra no qual as correntes parasitas são induzidas, além de outros dois componentes, M indutância mútua dos indutores acoplados e k, coeficiente relacionado ao acoplamento magnético entre os circuitos primário e secundário. A análise tradicionalmente utilizada para este tipo de medição é a avaliação da reflexão da impedância equivalente do circuito secundário representando a amostra no circuito primário. O trabalho analisa as equações de malha do circuito equivalente no domínio da frequência e identifica os parâmetros do modelo. A partir da identificação do sistema realizada com os ensaios experimentais, foi possível descobrir a constante de tempo indutiva τL do sistema. A partir dessa constante, observou-se a variação acentuada da mesma em relação a variação da impedância equivalente. Ainda é apresentada uma estimativa dos valores de R2 e L2 realizada por meio da unificação das informações obtidas com a identificação, aliada com as informações de campo magnético obtidas a partir de um sensor do tipo GMR e pela simulação em um software de elementos finitos COMSOL Multiphysics. / This work presents the study of a generic measurement system that uses the prin- ciple of eddy currents. The system model is represented as an equivalent electric circuit composed of R1 and L1 respectively characterizing the resistance and induc- tance of primary circuit, which are known by an excitation coil. In the secondary, R2 and L2 are representing the ohmic loss and the inductance of the sample in which the eddy currents are induced, in addition two other components, the mutual induc- tance of the coupled inductors and k, coefficient related to the magnetic coupling between the primary and secondary circuits. The analysis traditionally used for this type of measurement is the reflection evaluation of the equivalent impedance of the secondary circuit representing the sample in the primary circuit. The work analyzes the mesh equations of the equivalent circuit in the frequency domain and identifies the parameters of the model. From the identification of the system performed with the experimental tests, it was possible to discover the inductive time constant τL of the system. From this constant, it was observed the sharp variation of the same in relation to the variation of equivalent impedance. An estimate values, R2 and L2 performed by unification of the information obtained with the identification, to- gether with the magnetic field information obtained from a GMR type sensor and by simulation in a finite element software COMSOL Multiphysics.

Page generated in 0.0624 seconds