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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
411

[en] SCANNING OF GREGORIAN OFF-SET ANTENNAS BY DISPLACEMENT OF FEEDER / [pt] VARREDURA DE ANTENAS GREGORIANAS OFF-SET POR DESLOCAMENTOS DO ALIMENTADOR

HELIO FRANCISCO DA SILVA 03 January 2007 (has links)
[pt] Este trabalho tem por objetivo um estudo da viabilidade de se fazer varreduras com uma antena gregoriana off-set com deslocamentos apenas do alimentador. São localizadas as regiões focais para a antena receptora de modo a posicionar o alimentador de uma maneira simples. Também são apresentados os diagramas de radiação correspondentes a estes deslocamentos calculados segundo a Teoria Escalar da Difração; e as limitações de varreduras para a antena particular que serviu para testar a eficiência do método. / [en] This work is related to the study of the pattern of Gregorian off-set antennas, by displacement of the feeder. The position of the feeder is obtained, in a simple way, by determining the focal regions of the antennas, working in reception. The radiation patterns corresponding to different position of the feeder are also presented. Such patterns are calculated according to the scalar theory of diffraction. The useful range of scanning, for a given antenna, used to check the efficiency of the method, is determined.
412

Compositional synthesis via convex optimization of assume-guarantee contracts

Ghasemi, Kasra 17 January 2023 (has links)
Ensuring constraint satisfaction in large-scale systems with hard constraints is vital in many safety critical systems. The challenge is to design controllers that are efficiently synthesized offline, easily implementable online, and provide formal correctness guarantees. We take a divide and conquer approach to design controllers for reachability and infinite-time/finite-time constraint satisfaction control problems given large-scale interconnected linear systems with polyhedral constraints on states, controls, and disturbances. Such systems are made of small subsystems with coupled dynamics. Our goals are to design controllers that are i) fully compositional and ii) decentralized, such that online implementation requires only local state information. We treat the couplings among the subsystems as additional disturbances and use assume-guarantee (AG) contracts to characterize these disturbance sets. For each subsystem, we design and implement a robust controller locally, subject to its own constraints and contracts. Our main contribution is a method to derive the contracts via a novel parameterization, and a corresponding potential function that characterizes the distance to the correct composition of controllers and contracts, where all contracts are held. We show that the potential function is convex in the contract parameters. This enables the subsystems to negotiate the contracts with the gradient information from the dual of their local synthesis optimization problems in a distributed way, facilitating compositional control synthesis that scales to large systems. We then incorporate Signal Temporal Logic (STL) specifications into our formulation. We develop a decentralized control method for a network of perturbed linear systems with dynamical couplings subject to STL specifications. We first transform the STL requirements into set containment problems, then we develop controllers to solve these problems. The set containment requirements and parameterized contracts are added to the subsystems’ constraints. We introduce a centralized optimization problem to derive the contracts, reachability tubes, and decentralized closed-loop control laws. We show that, when the STL formula is separable with respect to the subsystems, the centralized optimization problem can be solved in a distributed way, which scales to large systems. We present formal theoretical guarantees on robustness of STL satisfaction. We present numerical examples, including scalability studies on systems with tens of thousands of dimensions, and case studies on applying our method to a distributed Model Predictive Control (MPC) problem in a power system. / 2024-01-16T00:00:00Z
413

Особенности проявления «процессуального» эффекта в эксперименте на генерализацию установки : магистерская диссертация / Features manifestations of "procedural" effect in experiments on generalization set

Степанова, А. А., Stepanova, A. A. January 2015 (has links)
Tis work is devoted to the study of subjective factors affecting the dynamics of perceptual activities aimed at the perception of stimuli and their evaluation. As such a subjective factor of the installation concerned, studied in the framework of the installation developed by Uznadze. Our work is a continuation of a series of experimental and theoretical research on quantitative and qualitative analysis of the manifestations of the effect of the set. In tis study we looked at specific factors that may define a generic, holistic nature of the set, characterized by dynamic, the procedural side of the evaluation activities. To do this, we have tried to investigate the phenomenon and the features of display "procedure" effect in experiments on generalization set. / Данная работа посвящена изучению субъективных факторов, влияющих на динамику перцептивной деятельности, направленной на восприятие стимулов и их оценку. В качестве такого субъективного фактора рассматривается установка, изучаемая в рамках теории установки, разработанной Д. Н. Узнадзе. Наша работа является продолжением серии экспериментально-теоретических исследований по количественному и качественному анализу проявления эффекта установки. В работе рассматривались конкретные факторы, которые могут определять обобщенный, целостный характер установки, характеризующей динамическую, процессуальную сторону оценочной деятельности. Для этого мы попытались исследовать феномен и особенности проявления «процессуального» эффекта в эксперименте на генерализацию установки.
414

Acute Responses to Combined Accentuated Eccentric Loading and Rest Redistribution

Chae, Sungwon 01 August 2023 (has links) (PDF)
This dissertation was 2 parts of investigations of various acute responses to high-volume combined accentuated eccentric loading and rest redistribution (AEL + RR). Resistance-trained men (n = 12, 25.6 ± 4.4 years, 1.77 ± 0.06 m, 81.7 ± 11.4 kg) completed a back squat (BS) 1 repetition maximum (1RM) and weight releaser familiarization session. Three BS exercise conditions (sets × repetitions × eccentric/concentric loading) comprised AEL + RR 5: 3 × (5 × 2) × 110/60%, AEL + RR 2: 3 × (2 × 5) × 110/60%, and traditional sets (TS): 3 × (1 × 10) × 60/60% 1RM. The AEL + RR 5 resulted in significantly (p < 0.05) greater concentric peak velocity (PV) (1.18 ± 0.17 m∙s–1) and power (PP) (2,304 ± 499 W) compared to AEL + RR 2 (1.11 ± 0.19 m∙s–1 and 2,148 ± 512 W) and TS (1.10 ± 0.14 m∙s–1 and 2,079 ± 388 W). Furthermore, AEL + RR 5 resulted in significantly greater PV and PP across all 10 repetitions compared to TS. Although AEL + RR 5 resulted in significantly greater concentric mean force (MF) (1,706 ± 224 N) compared with AEL + RR 2 (1,697 ± 209 N) and TS (1,685 ± 211 N), no condition by set or repetition interactions were found. The AEL + RR 5 yielded greater total volume load (sets × repetitions × eccentric + concentric loading) (6630.1 ± 1210.4 kg) compared with AEL + RR 2 (5944.3 ± 1085.2 kg) and TS (5487.0 ± 1001.7 kg). The AEL + RR 5 led to significantly (p < 0.05) greater rating of perceived exertion (RPE) after set 2 and 3 and lower blood lactate (BL) after set 3, 5-, 15-, and 25-minute post-exercise than AEL + RR 2 and TS. There was a main effect of condition for BL between AEL + RR 5 (5.11 ± 2.90 mmol∙L–1), AEL + RR 2 (6.23 ± 3.22 mmol∙L–1), and TS (6.15 ± 3.17 mmol∙L–1). In summary, AEL + RR 5 results in unique acute mechanical, physiological, and perceptual responses in high-volume BS exercise.
415

Gamma-Sets and the (A, B_∞) Selection Principle

Ballone, Frank A. 12 June 2017 (has links)
No description available.
416

Using Weighted Set Cover to Identify Biologically Significant Motifs

Schmidt, Robert J.M. January 2015 (has links)
No description available.
417

Studies on Lowering the Error Floors of Finite Length LDPC codes

Li, Huanlin 26 July 2011 (has links)
No description available.
418

Voluntary provision of public goods : experimental evidence and theoretical analysis

Feng, Colin G. January 1995 (has links)
No description available.
419

Stochastic Invariance and Aperiodic Control for Uncertain Constrained Systems

Gao, Yulong January 2018 (has links)
Uncertainties and constraints are present in most control systems. For example, robot motion planning and building climate regulation can be modeled as uncertain constrained systems. In this thesis, we develop mathematical and computational tools to analyze and synthesize controllers for such systems. As our first contribution, we characterize when a set is a probabilistic controlled invariant set and we develop tools to compute such sets. A probabilistic controlled invariantset is a set within which the controller is able to keep the system state with a certainprobability. It is a natural complement to the existing notion of robust controlled invariantsets. We provide iterative algorithms to compute a probabilistic controlled invariantset within a given set based on stochastic backward reachability. We prove that thesealgorithms are computationally tractable and converge in a finite number of iterations. The computational tools are demonstrated on examples of motion planning, climate regulation, and model predictive control. As our second contribution, we address the control design problem for uncertain constrained systems with aperiodic sensing and actuation. Firstly, we propose a stochastic self-triggered model predictive control algorithm for linear systems subject to exogenous disturbances and probabilistic constraints. We prove that probabilistic constraint satisfaction, recursive feasibility, and closed-loop stability can be guaranteed. The control algorithm is computationally tractable as we are able to reformulate the problem into a quadratic program. Secondly, we develop a robust self-triggered control algorithm for time-varying and uncertain systems with constraints based on reachability analysis. In the particular case when there is no uncertainty, the design leads to a control system requiring minimum number of samples over finite time horizon. Furthermore, when the plant is linear and the constraints are polyhedral, we prove that the previous algorithms can be reformulated as mixed integer linear programs. The method is applied to a motion planning problem with temporal constraints. / <p>QC 20181016</p>
420

A method for temporal fault tree analysis using intuitionistic fuzzy set and expert elicitation

Kabir, Sohag, Goek, T.K., Kumar, M., Yazdi, M., Hossain, F. 04 August 2020 (has links)
Yes / Temporal fault trees (TFTs), an extension of classical Boolean fault trees, can model time-dependent failure behaviour of dynamic systems. The methodologies used for quantitative analysis of TFTs include algebraic solutions, Petri nets (PN), and Bayesian networks (BN). In these approaches, precise failure data of components are usually used to calculate the probability of the top event of a TFT. However, it can be problematic to obtain these precise data due to the imprecise and incomplete information about the components of a system. In this paper, we propose a framework that combines intuitionistic fuzzy set theory and expert elicitation to enable quantitative analysis of TFTs of dynamic systems with uncertain data. Experts&#x2019; opinions are taken into account to compute the failure probability of the basic events of the TFT as intuitionistic fuzzy numbers. Subsequently, for the algebraic approach, the intuitionistic fuzzy operators for the logic gates of TFT are defined to quantify the TFT. On the other hand, for the quantification of TFTs via PN and BN-based approaches, the intuitionistic fuzzy numbers are defuzzified to be used in these approaches. As a result, the framework can be used with all the currently available TFT analysis approaches. The effectiveness of the proposed framework is illustrated via application to a practical system and through a comparison of the results of each approach. / This work was supported in part by the Mobile IOT: Location Aware project (grant no. MMUE/180025) and Indoor Internet of Things (IOT) Tracking Algorithm Development based on Radio Signal Characterisation project (grant no. FRGS/1/2018/TK08/MMU/02/1). This research also received partial support from DEIS H2020 project (grant no. 732242).

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