To see the other types of publications on this topic, follow the link: Extended space.
Dissertations / Theses on the topic 'Extended space'
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 'Extended space.'
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
Bandele, Jeremiah Oluwatosin. "Extended free-space optical communications." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/37961/.
Full textAbstract:
This thesis investigates the performance of free-space optical (FSO) communication systems in a turbulent atmosphere employing optical amplifiers (OAs) to extend transmission reach and wavelength-division multiplexing (WDM) to improve capacity. This system performance is considered in the presence of amplified spontaneous emission (ASE) noise, scintillation, beam spreading, atmospheric attenuation and interchannel crosstalk. In this work, the modulation scheme used is the on-off keying non-return-to-zero and the main performance metric employed is the average bit error rate (BER). Various performance evaluation methods are used to estimate system performance. Analysis of single link, cascaded OA and WDM FSO communication systems are given and the implications of using both adaptive (to channel state) and non-adaptive decision threshold schemes are analysed. The benefits of amplifier saturation, for example in the form of effective scintillation reduction when a non-adaptive decision threshold scheme is utilised at the receiver for different atmospheric turbulence regimes, are presented. Monte Carlo simulation techniques are used to model the probability distributions of system parameters such as the optical signal power, amplified spontaneous emission noise, optical signal to noise ratio and the average bit error rate due to scintillation. It is found that the performance of an adaptive decision threshold is superior to a non-adaptive decision threshold for both saturated and fixed gain preamplified receivers and the ability of a saturated gain OA to suppress scintillation is only meaningful for system performance when a non-adaptive decision threshold is used at the receiver. In a saturated gain preamplified system, the optimum non-adaptive decision threshold is investigated. An OA cascade can be successfully used to extend reach in FSO communication systems and specific system implementations are presented. The optimal cascade scheme with a non-adaptive receiver would use frequent low gain saturated amplification although this has a cost implication. Furthermore, a saturated gain amplified WDM FSO system with a non-adaptive decision threshold is superior to a non-amplified WDM FSO system with an adaptive decision threshold.
2
Finke, Axel. "On extended state-space constructions for Monte Carlo methods." Thesis, University of Warwick, 2015. http://wrap.warwick.ac.uk/77119/.
Full textAbstract:
This thesis develops computationally efficient methodology in two areas. Firstly, we consider a particularly challenging class of discretely observed continuous-time point-process models. For these, we analyse and improve an existing filtering algorithm based on sequential Monte Carlo (smc) methods. To estimate the static parameters in such models, we devise novel particle Gibbs samplers. One of these exploits a sophisticated non-entred parametrisation whose benefits in a Markov chain Monte Carlo (mcmc) context have previously been limited by the lack of blockwise updates for the latent point process. We apply this algorithm to a Lévy-driven stochastic volatility model. Secondly, we devise novel Monte Carlo methods – based around pseudo-marginal and conditional smc approaches – for performing optimisation in latent-variable models and more generally. To ease the explanation of the wide range of techniques employed in this work, we describe a generic importance-sampling framework which admits virtually all Monte Carlo methods, including smc and mcmc methods, as special cases. Indeed, hierarchical combinations of different Monte Carlo schemes such as smc within mcmc or smc within smc can be justified as repeated applications of this framework.
3
Luckock, H. C. "Strings, p-branes and Skyrmions in curved space." Thesis, University of Newcastle Upon Tyne, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384005.
Full text
4
Kaidel, Jörg. "Extended semiclassical approximations for systems with mixed phase space dynamics." [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=97013942X.
Full text
5
Gosson, Maurice A. de. "Extended Weyl calculus and application to the phase-space Schrödinger equation." Universität Potsdam, 2005. http://opus.kobv.de/ubp/volltexte/2009/2987/.
Full textAbstract:
We show that the Schr¨odinger equation in phase space proposed by Torres-Vega and Frederick is canonical in the sense that it is a natural consequence of the extendedWeyl calculus obtained by letting the Heisenberg group act on functions (or half-densities) defined on phase space. This allows us, in passing, to solve rigorously the TF equation for all quadratic Hamiltonians.
6
Sambuco, Adam J. "Layered Space: Toward an Architecture of Superimposition." University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1522164995486483.
Full text
7
Evans, Erin Elizabeth. "An extended analytic range corrector method for the space shuttle entry guidance algorithm." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/119296.
Full textAbstract:
Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2018.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 99-101).
Space shuttle entry guidance with an extended analytic range corrector method is presented. The guidance method is a variation of Shuttle entry guidance in which the parameters that define the drag profile are modified using quadratic splines to make the drag profile smooth and easier to customize. In general, in order to account for off-nominal entry conditions and ensure the vehicle flies the correct range to the runway, the nominal reference drag profile is modified on-line utilizing analytic expressions for the derivative of range with respect to the relevant drag profile parameter. This new profile is then used to calculate a reference drag command in the subsequent guidance algorithm cycle. Typical implementations of Shuttle entry guidance modify the drag profile using only one variable to shift the profile by a constant value. This presents problems when the vehicle is highly constrained and can easily violate constraints such as heat load and heat rate constraints due to small drag profile variations. The methods by which the drag profile is updated are changed in order to provide multiple perturbation options. In providing multiple drag profile update parameters, a memoryless range error allocator is implemented with a vector of weights as a design variable. The allocator parameters are designed to take into account heat load while remaining within constraints using a high L/D vertical takeoff horizontal landing reusable launch vehicle simulation. The resulting algorithm seeks to leverage the high-TRL Shuttle entry guidance routine by making minimal modifications to the implementation, while increasing robustness to entry interface dispersions under tight heating constraints. A discussion of the design of the drag profile is included, in which the selection of profile update parameters is explored. Results from optimization of these parameters using a genetic algorithm are presented, as well as Monte Carlo results demonstrating that the allocator can reduce failure rates due to tight drag constraints from 42% to 0%, establishing the impact and success of this analytic range corrector method.
by Erin Elizabeth Evans.
S.M.
8
Hussin, Mohamed Nuri Ahmed. "Diversity gain enhancement for extended orthogonal space-time block coding in wireless communications." Thesis, University of Strathclyde, 2013. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=22706.
Full textAbstract:
Transmit diversity is a powerful technique for enhancing the channel capacity and reliability of multiple-input and multiple-output (MIMO) wireless systems. This thesis considers extended orthogonal space-time block coding (EO-STBC) with beamsteering angles, which have previously been shown to potentially achieve full diversity and array gain with four transmit and one receive antenna. The optimum setting of beamsteering angles applied in the transmitter, which has to be calculated based on channel state information (CSI) at the receiver side, must be quantised and feed back to the transmitter via a reverse feedback link. When operating in a fading scenario, channel coefficients vary smoothly with time. This smooth evolution of channel coefficients motivates the investigation of differential feedback, which can reduce the number of feedback bits, while potentially maintaining near optimum performance. The hypothesis that the smooth evolution of channel coefficients translates into smooth evolution of feedback angles is justified by simulations. The maximum attainable gain under optimum unquantised beamsteering angles is derived, which allows to experimentally assess the effect that quantisation in the feedback channel has on the system performance. In characterising the degradation experienced through time-variation and limited quantised feedback, we demonstrate that the new differential feedback approach offers a practical bandwidth-efficient scheme. Simulation results with Doppler spread conditions confirm that the proposed scheme achieves significant bandwidth savings over previously proposed systems. With a single feedback bit per beamsteering angle the proposed differentially encoded EO-STBC approach can achieve near optimum performance and exceed the performance of non-differential feedback schemes that employ a higher word length. We further propose combining differential encoding with channel estimation that is practically useful because the EO-S. We further propose combining differential encoding with channel estimation that is practically useful because the EO-STBC receiver requires knowledge of the channel coefficients for both detecting the transmitted symbols as well as for computing the optimum angles to be fed back to the transmitter. Channel estimation accompanied by a decision-directed (DD) tracking scheme by means of a Kalman filter has been adopted. The Kalman filter exploits the smooth evolution of the channel coefficients as a motivation for tracking as well as for differential feedback. Further we propose applying an auto-regressive (AR) predictor with order greater than one in the Kalman model. This can be shown to offer advantages in terms of temporal smoothness when addressing channels whose coefficient trajectories evolve smoothly. Simulation results show that the overall EO-STBC system achieves longer tracking periods with suitable bit error (BER) values, and that the performance of the proposed system offers a distinct advantage for lower Doppler spreads with the inclusion of second order AR model instead of the standard first order AR model. The earlier work on EO-STBC systems is for frequency-flat channels. However, in frequency-selective channel a multi-carrier approach can help to split into independent subcarriers. Therefore, the EO-STBC scheme is then applied for a dedicated chirp-based multicarrier based on a fractional Fourier transformer (FrFT) system over doubly dispersive channels, where FrFT-domain is developed to further increase robustness against channel time-variations. Applied in nearstationary channel conditions, the performance of orthogonal frequency division multiplexing (OFDM) receivers that mitigate crosstalk between individual subcarriers are evaluated for open and closed loop schemes. A higher degree of non-stationarity in mobile scenarios will destroy the orthogonality of subcarriers and result in intercarrier interference (ICI) and intersymbol interference (ISI). In this case, minimum mean square error (MMSE) of a reduced system matrix is considered for open loop EO-STBC. The equaliser complexity can be decreased even furtherby using least squares minimum residual (LSMR) iterative algorithm, equalisation are underlined by simulations, demonstrating the overall practical use if the contributions wihtin this thesis towards EO-STBC diversity schemes over both time- and frequency-dispersive channels.
9
Wu, Chenchen. "Dynamic analysis of extended bistable reeled fibre-reinforced composite booms for space applications." Thesis, University of Surrey, 2017. http://epubs.surrey.ac.uk/813977/.
Full textAbstract:
Bistable Reeled Composite (BRC) booms have the potential to be used as lightweight structural elements for a number of space applications. This thesis details an approach for increasing the natural frequency and stiffness of extended BRCs. The motivation for this research is the desire to increase the scalability of a flexible “roll-up” solar array which, in its deployed state, consists of two cantilevered BRCs supporting a flexible Photo Voltaic (PV) cell-covered blanket betwee n them. A parametric study has been presented, which analysed the effects of design parameters on the vibration characteristics of a single boom using a Finite Element (FE) approach. A numerical model was combined with a nonlinear constrained optimisation to maximise the natural frequency of BRC booms with respect to the fibre orientation angles and ply discontinuity locations, under the constraints of the physically achievable braid angles and constant coiled diameters resulting from the deployment mechanism design. The results demonstrate that careful selection of the fibre orientation angles and introducing a step change in the number of plies at strategic positions along the boom length can significantly increase the natural frequency. For instance, the natural frequency of a four-carbon/epoxy-nominalbraid-ply boom (L = 5.1 m, R = 38 mm, and β = 345◦) has been improved by more than 50%. The agreement between the natural frequency values for the complete solar array and the corresponding individual BRC booms indicates that the optimised solutions for a single boom model are applicable to the complete model for the first (cantilever) mode. Experimental verification of the vibration characteristics of optimised BRC booms has also been conducted. Finally, a dynamic stability analysis of the optimised BRC booms under bending has been carried out using FE simulation, to quantify the maximum angular acceleration that they can withstand before failure. The optimised BRC booms exhibit a higher resistance to bending during a spacecraft manoeuvre.
10
Nagai, Toshiki. "Space-time Extended Finite Element Method with Applications to Fluid-structure Interaction Problems." Thesis, University of Colorado at Boulder, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10844711.
Full textAbstract:
This thesis presents a space-time extended finite element method (space-time XFEM) based on the Heaviside enrichment for transient problems with moving interfaces, and its applications to the fluid-structure interaction (FSI) analysis. The Heaviside-enriched XFEM is a promising method to discretize partial differential equations with discontinuities in space. However, significant approximation errors are introduced by time stepping schemes when the interface geometry changes in time. The proposed space-time XFEM applies the finite element discretization and the Heaviside enrichment in both space and time with elements forming a space-time slab. A simple space-time scheme is introduced to integrate the weak form of the governing equations. This scheme considers spatial intersection configuration at multiple temporal integration points. Standard spatial integration techniques can be applied for each spatial configuration. Nitsche's method and the face-oriented ghost-penalty method are extended to the proposed space-time XFEM formulation. The stability, accuracy and flexibility of the space-time XFEM for various interface conditions including moving interfaces are demonstrated with structural and fluid problems. Moreover, the space-time XFEM enables analyzing complex FSI problems using moving interfaces, such as FSI with contact. Two FSI methods using moving interfaces (full-Eulerian FSI and Lagrangian-immersed FSI) are studied. The Lagrangian-immersed FSI method is a mixed formulation of Lagrangian and Eulerian descriptions. As solid and fluid meshes are independently defined, the FSI is computed between non-matching interfaces based on Nitsche's method and projection techniques adopted from computational contact mechanics. The stabilized Lagrange multiplier method is used for contact. Numerical examples of FSI and FSI-contact problems provide insight into the characteristics of the combination of the space-time XFEM and the Lagrangian-immersed FSI method. The proposed combination is a promising method which has the versatility for various multi-physics simulations and the applicability such as optimization.
11
Bonjour, Filipe. "Extended defects in curved spacetimes." Thesis, Durham University, 1999. http://etheses.dur.ac.uk/4966/.
Full textAbstract:
This Thesis is concerned with three particular aspects of extended cosmic strings and domain walls in cosmology: their dynamics, gravitation and interaction with a black hole. In Chapter 3, we study the dynamics of an abelian-Higgs cosmic string. We find its equations of motion from an effective action and compare, for three test trajectories, the resulting motion with that observed in the Nambu-Gotō approximation. We also present a general argument showing that the corrected motion of any string is generically antirigid. We pursue the investigation of the dynamics of topological defects in Chapter 5, where we find (from integrability conditions rather than an effective action) the effective equations governing the motion of a gravitating curved domain wall. In Chapter 4 we investigate the spacetime of a gravitating domain wall in a theory with a general potential V(ɸ). We show that, depending on the gravitational coupling e of the scalar ɸ, all nontrivial solutions fall into two categories interpretable as describing respectively domain wall and false vacuum-de Sitter solutions. Wall solutions cannot exist beyond a value (^4)(_3)ɛmax, and vacuum-de Sitter solutions are unstable to decaying into wall solutions below ɛmax at ɛmax we observe a phase transition between the two types of solution. We finally specialize for the Goldstone and sine-Gordon potentials. In Chapter 6 we consider a Nielsen-Olesen vortex whose axis passes through the centre of an extremal Reissner-Nordstr0m black hole. We examine in particular the existence of piercing and expelled solutions (where the string respectively does and does not penetrate the black hole's horizon) and determine that while thin strings penetrate the horizon — and therefore can be genuinely called hair — thick strings are expelled; the two kinds of solution are separated by a phase transition.
12
Paulus, Audrey S. "Improved target detection through extended-dwell, multichannel radar." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/54279.
Full textAbstract:
The detection of weak, ground-moving targets can be improved through effective utilization of additional target signal energy collected over an extended dwell time. The signal model used in conventional radar processing limits integration of signal energy over an extended dwell. Two solutions that consider the complexity of the extended-dwell signal model and effectively combine signal energy collected over a long dwell are presented. The first solution is a single-channel algorithm that provides an estimate of the optimal detector to maximize output signal-to-interference-plus-noise ratio for the extended dwell time signal. Rather than searching for the optimal detector in an intractably large filter bank that contains all combinations of phase components, the single-channel algorithm projects dictionary entries against the data to estimate the signal’s linear and nonlinear phase components sequentially with small, phase-specific dictionaries in a multistage process. When used as the detector, the signal model formed from the estimated phase components yields near optimal performance for a wide range of target parameters for dwell times up to four seconds. In comparison, conventional radar processing methods are limited to an integration time of approximately 100 milliseconds. The second solution is a multichannel, multistage algorithm based on element-space pre-Doppler space-time-adaptive processing with two modifications that make it suitable for detection of weak targets whose energy is collected over an extended dwell time. The multichannel solution detects targets with lower radial velocities at significantly lower signal-to-noise ratios (SNRs) than conventional radar processing methods. The decrease in required input SNR for the multichannel solution as compared to conventional methods nearly doubles the detection range for a typical target of interest. Future related research includes extension of these concepts to other radar applications and investigation of algorithm performance for the multiple-target scenario.
13
Zhu, Linhong, Dong Guo, Junming Yin, Steeg Greg Ver, and Aram Galstyan. "Scalable temporal latent space inference for link prediction in dynamic social networks (extended abstract)." IEEE, 2017. http://hdl.handle.net/10150/626028.
Full textAbstract:
Understanding and characterizing the processes driving social interactions is one of the fundamental problems in social network research. A particular instance of this problem, known as link prediction, has recently attracted considerable attention in various research communities. Link prediction has many important commercial applications, e.g., recommending friends in an online social network such as Facebook and suggesting interesting pins in a collection sharing network such as Pinterest. This work is focused on the temporal link prediction problem: Given a sequence of graph snapshots G1, · ··, Gt from time 1 to t, how do we predict links in future time t + 1? To perform link prediction in a network, one needs to construct models for link probabilities between pairs of nodes. A temporal latent space model is proposed that is built upon latent homophily assumption and temporal smoothness assumption. First, the proposed modeling allows to naturally incorporate the well-known homophily effect (birds of a feather flock together). Namely, each dimension of the latent space characterizes an unobservable homogeneous attribute, and shared attributes tend to create a link in a network.
14
Surak, Sarah Marie. "Bringing in the Garbage: Opening a Critical Space for Vehicle Disposal Practices." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/77046.
Full textAbstract:
This dissertation examines the relationship among practices and policies of waste/ing and economic structures to make visible the implications of vehicle disposal policies for environmental policy and theory. Consequently, I attempt to build upon the small body of literature that is now critically engaging with waste production and resulting actions/inaction in the form of policies of management. In doing this I use waste as a lens to examine the interrelationships among environmental degradation and economic and political structures. Further, I examine these phenomena in relation to a physical object, the automobile, to add materiality to abstract notions of waste as it relates to both the political and the economic. Through vehicle recycling policies, I analyze how underlying economic structures in contemporary capitalism result in specific responses to the "problems" of waste as well as how the related responses, or "solutions" perpetuate an un-ecological industrial system which severely restricts the possibilities of making substantial change in the production of environmental harms.Ph. D.
15
Sanderud, Audun Rønning. "Task Programming of Redundant Industrial Robots : A Virtually Extended Null Space Formulation Verified Through Obstacle Avoidance." Thesis, Norges Teknisk-Naturvitenskaplige Universitet, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-21081.
Full textAbstract:
Industrial robots are an important part of modern automation and are used in a variety of applications such as handling, welding, painting and assembling. They have normally six degrees of freedom to provide an arbitrary location of the tool inside its working space. However, during the last years, there have been developed industrial robots with more than six axes, thus redundant robots. This gives extra functionality to avoid singular positions, to move around obstacles and to optimize the use of energy during a predefined trajectory, by changing the internal configuration of the robot arm while still maintaining the tool's location. However, programming of redundant robots is complicated and time consuming due to the fact that both the tool location and the internal configuration of the robot arm have to be programmed. Investigations on the use of redundant industrial robots in the industry reveal several advantages including highly increased flexibility and a significant reduction of space need. The flexibility can be attributed through obstacle avoidance, singularity avoidance and energy optimization. For small and medium enterprises (SMEs) and in High-mix Low-volume productions, this gives a great advantage in even more competitive markets.This thesis presents an efficient approach for programming of redundant industrial robots. The system uses proximity sensors mounted on the robot arm to detect obstacles. By analyzing the sensor data, the system can automatically reconfigure the robot's arm to automatically, comply with environmental constraints. Enabling this functionality by an automatic system, simplified the programming of the redundant robot to be similar to a normal six-axes robot. Studies into the subjects that constitute the theoretical basis for the practical implementation and kinematic resolutions have been done. This includes, among others, kinematic analysis, redundancy resolutions, task formulation and methods for obstacle detection. The studies led to a suggestion for an task description scheme based on an extension of Mason's task formulation for force controlled tasks. The formulation augments the robots self-motion ability to be based upon a virtual extension of the robot's Null space. The virtual extension allows the operator to select the priority of the secondary task, subsequently programming the robot as if it were a six-axis robot. The system has been implemented and experimentally verified on a NACHI MR20 seven-axes industrial robot. The implemented system includes Cartesian velocity limiter, Joint space velocity limiter, Task Reconstruction algorithm, Default arm reconfiguration and path correction algorithm. The sensors system is based on ultrasonic and infrared proximity sensors, covering the greater part of the robot arm. The experiments proved convincing performance and robustness of the implemented system. It was shown that the extended null space formulation can redistribute certain axes from the primary task to the secondary task, and thus, provide automatic obstacle avoidance. The obstacle avoidance strategy was shown to be successful, and gave the desired evasive maneuver. Experiments also demonstrated the system’s ability to reconfigure the primary task after deflection caused by the secondary task and the ability to reconfigure the arm to a default configuration when both the task is reconstructed and no obstacles are present.
16
Bhamare, Sagar D. "High Cycle Fatigue Simulation using Extended Space-Time Finite Element Method Coupled with Continuum Damage Mechanics." University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1352490187.
Full text
17
Heiss, Leah Rose Laurel, and leah heiss@rmit edu au. "Empathy and the space between: investigating the role of digitally enhanced apparel in promoting remote empathetic connection." RMIT University. Architecture and Design, 2006. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20070112.101632.
Full textAbstract:
This body of work is the culmination of a two year investigation into the role of electronically enhanced apparel and artefacts in providing empathetic linkage between people who do not share physical space. The research draws from the diverse fields of philosophy, communications theory, neuropsychology, presence technologies and technologically advanced textiles, and proposes that a nexus of these disciplines may provide significant opportunities for enhancing the user interactivity of garments and artefacts. Remote emotional connection is investigated through the creation of sensor embedded garments and artefacts that have been developed in collaboration with a fashion designer and an electronics engineer. The prototypes encourage remote empathetic connection through the real-time transference of heartbeat. The exegesis is structured into five chapters which consider remote presence, flexible consciousness, the architecture of empathy, plasticity in sense perception and the development of prototypes. The project chapter focuses in the development of and testing of a rnage of garments and artefacts thatt conduct presence information between remotely located people. The garments sense, process, transmit and receive the heartbeat signal (ECG). They are enabled with ECG sensors, signal processing equipment, small vibration motors and radio transceivers which allow users to 'feel' the heartbeat of a remote friend/lover/relative as vibration through their garment. The prototypes aim to enrich the remote communications experience through reintroducing an embodied, tactile dimension that is present in face-to-face communication. A range of user testing trials are discussed in the thesis which have been undertaken to assess the impact of the garments at a conscious and a non-conscious level. Conscious experiences were gauged through qualitative testing by way of interviews and unsolicited written reactions. Non-conscious physiological ractions were assessed by recording ECG throughout user-testing periods. This data has been processed by using HRV (heart rate variability) analysis software, running on MatLab.
18
COSTA, LEONARDO HENRIQUE. "MODELING IBNR CLAIMS WITH TAIL EFFECT: EXTENDED CHAIN LADDER, HETEROCEDASTIC LINEAR REGRESSION MODELS AND LINEAR STATE SPACE MODELS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2010. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=15850@1.
Full textAbstract:
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROEste trabalho utiliza três metodologias para modelagem de sinistros IBNR apresentados no formato do triângulo de runoff com cauda, e verifica, por meio de quatro exercícios empíricos com dados reais, se existe uma abordagem estatisticamente mais eficaz. A primeira metodologia se baseia no método do chain ladder clássico, com uma extensão de cálculo de reserva para ano de calendário. A segunda metodologia baseia-se em modelos de regressão linear com heterocedasticidade, sob o arranjo usual do triângulo via duplo-índice. A terceira insere-se no arcabouço dos modelos de espaço de estado lineares e do filtro de Kalman, considerando, desta vez, a ordenação por linhas do triângulo de Atherino et al. (2010). Para todas as abordagens, efetivam-se derivações teóricas e implementações computacionais tanto dos cálculos de reservas IBNR totais e parciais, resultantes dos modelos estimados, quanto dos correspondentes erros médios quadráticos teóricos. Como conclusões desta Dissertação, citam-se: (i) apesar de superiores ao chain ladder, nenhuma das outras duas abordagens se destaca sistematicamente em relação à outra; (ii) a adoção do efeito cauda se mostrou computacional e tecnicamente viável; e (iii) há fatos estilizados nos dados, modelados sob as três abordagens, que possibilitariam a confecção de softwares de estimação de reserva.
This work makes use of three methodologies for modeling IBNR data arranged in the runoff triangle with a tail effect, and evaluates their performances in four empirical examples. The first methodology is the traditional chain ladder, duly extended to calculate a reserve corresponding to the calendar year. The second methodology remains on linear regression models with heteroscedastic errors, under the well-established double index notation of the triangle. The third methodology uses the linear state space modeling and the theory of the Kalman filter, adopting, this time, the row-wise ordering proposed by Atherino et al. (2010). For each approach, theoretical results and numerical implementations are obtained, where both the punctual IBNR reserve estimators and their corresponding theoretical mean square errors are considered. The main conclusions from this Dissertation are: (i) even thought proving to be superior to the chain ladder, none of the remaining two approaches seems to outperform the other; (ii) the adding of a tail effect does not entail major theoretical and/or computational problems; and (iii) the approaches have uncovered stylized facts that would enable the planning of softwares for IBNR reserve estimation.
19
Yamauchi, Atsuo. "On a certain extended Galois action on the space of arithmetic modu-lar forms with respect to a unitary group." 京都大学 (Kyoto University), 2001. http://hdl.handle.net/2433/150809.
Full text
20
Anil, Vijay Sankar. "Mission-based Design Space Exploration and Traffic-in-the-Loop Simulation for a Range-Extended Plug-in Hybrid Delivery Vehicle." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1587663664531601.
Full text
21
Alkanjo, Hasan. "Spectre étendu des opérateurs et applications." Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10271/document.
Full textAbstract:
Cette thèse s'articule autour d'une notion spectrale assez récente, appelée le spectre étendu des opérateurs. Dans la première partie nous fournissons des propriétés générales du spectre étendu d'un opérateur dans certains cas particuliers, tels que le cas de dimension finie et celui des opérateurs inversibles. Nous nous intéressons dans la deuxième partie à l'étude du spectre étendu de l'opérateur shift tronqué Su. En particulier, nous donnons une description complète des vecteurs propres étendus associes à chaque valeur propre étendue de Sb, ou b est un produit de Blaschke quelconque. Dans la troisième partie nous décrirons complètement le spectre étendu et les sous espaces propres étendus d'une classe d'opérateurs très importante : celle des opérateurs normaux. Nous commençons d'abord par la classe des opérateurs qui sont produits d'un opérateur positif par un autoadjoint. Ensuite, nous utilisons le théorème de Fuglede-Putnam pour déduire une description complète des valeurs et des vecteurs propres étendus des opérateurs normaux, en fonction de leur mesure spectrale. Dans la dernière partie, nous appliquons nos résultats des trois premières parties sur des exemples concrets. En particulier, nous traitons= le problème des sous espaces propres étendus des opérateurs définis dans un espace de dimension finie. Ensuite, nous montrons l'existence d'un opérateur compact quasinilpotent dont le spectre étendu est réduit au singleton {1}. Enfin, nous traitons deux opérateurs de Cesaro très importants dans les applicationsThis thesis is based on a relatively new spectral notion, called extended spectrum of operators. In the first part, we provide general properties of extended spectrum of an operator in some special cases, such as the case of finite dimension and the case of invertible operator. We focused in the second part on characterizing the extended spectrum of truncated shift operator Su. In particular, we give a complete description of the extended eigenvectors associated to each extended eigenvalue of Sb, where b is a Blaschke product. In the third part, we describe the extended spectrum and the extended eigenvectors of a very important class of operators , that is the normal operators. We first start by describing these last sets for the product of a positive and a self-adjoint operator which are both injective. After, we use the Fuglede-Putnam theorem to describe the same sets for normal operators, in terms of their spectral measure. In the last part, we apply our results from the last three parts on concrete examples. In particular, we address the problem of extended eigenvectors of operators defined in a finite dimension space. Next, we show the existence of a quasinilpotent compact operator whose extended spectrum is reduced to {1}. Finally, we study two Cesaro operators which are very important in applications
22
Kasradze, Ketevan [Verfasser], Hendrik [Gutachter] Elbern, and Andreas [Gutachter] Wahner. "An extended variational atmospheric chemistry data assimilation system for combined space and air borne trace gas retrievals / Ketevan Kasradze ; Gutachter: Hendrik Elbern, Andreas Wahner." Köln : Universitäts- und Stadtbibliothek Köln, 2016. http://d-nb.info/1117134814/34.
Full text
23
Mannai, Usama N. "Novel transmission schemes for application in two-way cooperative relay wireless communication networks." Thesis, Loughborough University, 2014. https://dspace.lboro.ac.uk/2134/15836.
Full textAbstract:
Recently, cooperative relay networks have emerged as an attractive communications technique that can generate a new form of spatial diversity which is known as cooperative diversity, that can enhance system reliability without sacrificing the scarce bandwidth resource or consuming more transmit power. To achieve cooperative diversity single-antenna terminals in a wireless relay network typically share their antennas to form a virtual antenna array on the basis of their distributed locations. As such, the same diversity gains as in multi-input multi-output systems can be achieved without requiring multiple-antenna terminals. However, there remain technical challenges to maximize the benefit of cooperative communications, e.g. data rate, asynchronous transmission, interference and outage. Therefore, the focus of this thesis is to exploit cooperative relay networks within two-way transmission schemes. Such schemes have the potential to double the data rate as compared to one-way transmission schemes. Firstly, a new approach to two-way cooperative communications via extended distributed orthogonal space-time block coding (E-DOSTBC) based on phase rotation feedback is proposed with four relay nodes. This scheme can achieve full cooperative diversity and full transmission rate in addition to array gain. Then, distributed orthogonal space-time block coding (DOSTBC) is applied within an asynchronous two-way cooperative wireless relay network using two relay nodes. A parallel interference cancelation (PIC) detection scheme with low structural and computational complexity is applied at the terminal nodes in order to overcome the effect of imperfect synchronization among the cooperative relay nodes. Next, a DOSTBC scheme based on cooperative orthogonal frequency division multiplexing (OFDM) type transmission is proposed for flat fading channels which can overcome imperfect synchronization in the network. As such, this technique can effectively cope with the effects of fading and timing errors. Moreover, to increase the end-to-end data rate, a closed-loop EDOSTBC approach using through a three-time slot framework is proposed. A full interference cancelation scheme with OFDM and cyclic prefix type transmission is used in a two-hop cooperative four relay network with asynchronism in the both hops to achieve full data rate and completely cancel the timing error. The topic of outage probability analysis in the context of multi-relay selection for one-way cooperative amplify and forward networks is then considered. Local measurements of the instantaneous channel conditions are used to select the best single and best two relays from a number of available relays. Asymptotical conventional polices are provided to select the best single and two relays from a number of available relays. Finally, the outage probability of a two-way amplify and forward relay network with best and Mth relay selection is analyzed. The relay selection is performed either on the basis of a max-min strategy or one based on maximizing exact end-to-end signal-to-noise ratio. MATLAB and Maple software based simulations are employed throughout the thesis to support the analytical results and assess the performance of new algorithms and methods.
24
Lotito, Matteo. "Geometric classification of 4d rank-1 N=2 superconformal field theories." University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1530880263562131.
Full text
25
Geldenhuys, Ilse. "The management of people, processes and places in the virtual workplace." Thesis, University of Pretoria, 2010. http://hdl.handle.net/2263/25307.
Full textAbstract:
The traditional workplace evolved over time, moving through different waves or phases of change. The phases, although prevalent in different stages in different countries, have been characterised by various technological developments. The virtual workplace evolved as part of the Information Age or Fifth Wave, bringing with it its own unique characteristics and requirements. These unique characteristics, such as the speed at which information is communicated, crossing of time and space boundaries, social networks and requirements, such as sustainable high speed internet connectivity, are evident in the relationship between people, processes and the virtual workplace. This study explored the manner in which virtual workers executed their activities through the use of technology, the type of business processes supporting them and the challenges experienced by them. The proposed framework for the management of people, processes and places in the virtual workplace was subsequently derived. The framework has as aim to represent the relationship between people, processes and places components in the virtual workplace and in doing so providing a management framework supporting the virtual workplace. The people, processes and places components have been incorporated in the management, technology and practice sections of the framework, thereby providing a framework based on the relationship between people, processes and places. This study also developed the Extended Hermeneutic Circle of Learning which was used as guideline for the research conducted as part of this thesis. The deeper understanding created through the use of this research guideline assisted in providing structure to the research, thus enabling the researcher to derive the proposed framework for the management of people, processes and placed in the virtual workplace.Thesis (PhD)--University of Pretoria, 2011.
Informatics
unrestricted
26
Lehrenfeld, Christoph Verfasser], Arnold [Akademischer Betreuer] [Reusken, Marek [Akademischer Betreuer] Behr, and Joachim [Akademischer Betreuer] Schöberl. "On a Space-Time Extended Finite Element Method for the Solution of a Class of Two-Phase Mass Transport Problems / Christoph Lehrenfeld ; Arnold Reusken, Marek Behr, Joachim Schöberl." Aachen : Universitätsbibliothek der RWTH Aachen, 2015. http://d-nb.info/112697157X/34.
Full text
27
Lehrenfeld, Christoph [Verfasser], Arnold [Akademischer Betreuer] Reusken, Marek [Akademischer Betreuer] Behr, and Joachim [Akademischer Betreuer] Schöberl. "On a Space-Time Extended Finite Element Method for the Solution of a Class of Two-Phase Mass Transport Problems / Christoph Lehrenfeld ; Arnold Reusken, Marek Behr, Joachim Schöberl." Aachen : Universitätsbibliothek der RWTH Aachen, 2015. http://nbn-resolving.de/urn:nbn:de:hbz:82-rwth-2015-006739.
Full text
28
Jameel, Syed Mohd Saad. "Turbulence modelling of mixed and natural convection regimes in the context of the underhood-space of automobiles." Thesis, Pau, 2020. http://www.theses.fr/2020PAUU3033.
Full textAbstract:
Le sujet de cette thèse concerne la modélisation de la turbulence des écoulements influencés par la flottabilité, qui émanent de l’interaction de la force gravitationnelle avec une différence de densité. Cette étude est motivée par des problématiques rencontrées par le groupe PSA dans la simulation des écoulements de convection naturelle dans le compartiment moteur des véhicules.L’objectif principal de ce travail est de tester plusieurs modéles pour prendre en compte la flottabilité et de proposer des améliorations efficaces qui pourraient fournir un modèle applicable aux écoulements engendrés par la flottabilité. En outre, ces modifications doivent pouvoir être mises en œuvre dans le code Ansys Fluent pour le calcul des écoulements de convection naturelle dans les problèmes typiques cités ci-dessus. Dans le cadre de cet objectif, nous avons adapté trois modèles à viscosité turbulente aux effets de la flottabilité. La première approche qui offre le meilleur cadre physique implique l’extension des lois de comportement pour le tenseur de Reynolds et le flux thermique turbulent de manière linéaire, pour tenir compte de l’influence anisotrope de la flottabilité.Cette approche, appliquée à trois modèles différents, permet d’améliorer considérablement les résultats en reproduisant l’écoulement moyen et les quantités turbulentes. Dès lors, on se rend compte que cette approche conduit à des améliorations significatives en terme de physique.De plus, on observe que l’utilisation d’une approche simplifée d’hypothèse de diffusion par simple gradient “SGDH” pour modéliser le terme source de flottabilité conduit à une sous-estimation de l’effet de la flottabilité sur la turbulence. En outre, la comparaison avec les données de la simulation numérique directe (DNS) montre que l’hypothèse de diffusion par gradient généralisé “GGDH” donne de meilleures prédictions de l’écoulement moyen et du champ de température. Un autre aspect abordé dans ce travail concerne la sensibilité au modéle du terme de production par flottabilité dans l’equation de ε ou ω. Après une analyse détaillée, on constate que les résultats sont trés sensibles à ce terme et que la valeur optimale du coefficient est liée au choix du modèle de turbulence. Pour éviter cette sensibilité, on utilise une autre expression du terme source pour la modélisation de la flottabilité dans les équations de ε du ω qui tient compte du nombre de Richardson de flux et on observe une amélioration de la prédiction des profils moyens.Trois régimes différents d’écoulements sont étudiés, à savoir les régimes de convection forcée, mixte et naturelle. Parmi ceux-ci, la configuration de canal vertical différentiellement chauffé est considérée pour développer le modèle adapté à la flottabilité. C’est celle qui pose le plus grand défi pour les modèles à viscosité turbulente. Ces études ont abouti à la proposition d’une forme plus physique et simplifiée de modèles adaptés à la flottabilité, qui est considérée comme le meilleur compromis entre la précision physique et la stabilité numérique pour des écoulements induits par la flottabilité.Ces modèles sensiblisés à la flottabilité offrent des perspectives pour étudier d’autres configurations d’écoulements de convection mixte et naturelle et ouvrent la voie à l’utilisation de ces modèles dans les simulations dans le compartiment moteur des véhiculesThe subject of this thesis is the turbulence modeling of buoyancy-driven flows, which emanate through the interaction of the gravitational force with a density difference. The motivation of this investigation comes from the problem faced by the PSA group in simulating natural convection flows in the under hood space of cars.The main goal of the present investigation is to test several models to account for buoyancy and to propose effective improvements which could provide a model applicable to buoyancy-driven flows and in addition to that, can be easily implemented in the software Ansys Fluent for the computation of natural convection flows in the Underhood-space of cars.In the context of this goal, three eddy-viscosity turbulence models are sensitized to the effects of buoyancy. The first approach which offers the better physical framework involves the extension of the constitutive relations for the Reynolds stress and turbulent heat flux in a linear way, to account for the anisotropic influence of buoyancy. This approach is applied to three different models and brings in drastic improvement of the results in reproducing the mean flow and the turbulent quantities and thus it is realized that this approach leads to physically based improvements.Furthermore, it is observed that, using a simple gradient diffusion hypothesis (SGDH) approach to model the buoyancy source terms leads to underestimate the effect of buoyancy on turbulence and the comparison with the DNS data shows that the generalized gradient diffusion hypothesis (GGDH) give improved predictions of the mean flow and temperature field. Another issue addressed in this work involves the sensitiveness to the buoyancy production term in the ε or ω equations and after a detailed analysis, it is realized that the results are very sensitive to this term and the optimal value of the coefficient is linked to the choice of the turbulence model. To avoid this limitation, another expression for the model of the buoyancy source term in the ε or ω equations is applied which considers the flux Richardson number and it is observed that there is an improvement in the prediction of mean flow profiles.Three different regimes of convective flows are studied namely, forced, mixed and natural convection and the more challenging differentially heated vertical channel flow configuration which poses a major challenge to the eddy-viscosity models is considered to develop the buoyancy sensitized model. As an outcome of these studies, the more physical and simplified forms of buoyancy sensitized model are proposed which is considered as the best compromise between the physical accuracy and numerical stability for buoyancy-driven flows.These buoyancy-sensitized models provide an opportunity to investigate other buoyancy-driven flows and paves the way for these models to be applied in the under hood space simulation
29
Paim, Anderson de Campos. "Controle preditivo retroalimentado por estados estimados, aplicado a uma planta laboratorial." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2009. http://hdl.handle.net/10183/21258.
Full textAbstract:
A retroalimentação de controladores preditivos que utilizam modelos em espaço de estado pode ser realizada de duas formas: (a) correção por bias, em que as saídas preditas são corrigidas adicionando-se um valor proporcional a discrepância encontrada entre o valor medido atual e sua respectiva predição e por (b) retroalimentação dos estados, onde se determinam as condições iniciais através da estimação dos estados, e a partir de uma melhor condição inicial se realizam as predições futuras usadas no cálculo das ações de controle. Nesta dissertação estas duas abordagens são comparadas utilizando a Planta Laboratorial de Seis Tanques Esféricos. As técnicas de Filtro de Kalman Estendido (EKF) e Filtro de Kalman Estendido com Restrições (CEKF) foram empregadas para estimar os estados não medidos. Inicialmente foram feitos testes off-line destes algoritmos de estimação. Para estes testes são utilizados uma série de dados da planta laboratorial do estudo de caso, na qual são estudadas as influências de diversos fatores de ajuste que determinam a qualidade final de estimação. Estes ajustes serviram de base para a aplicação destes algoritmos em tempo real, quando então, estimadores de estados estão associados ao sistema de controle do processo baseado em um algoritmo de controle preditivo. Após se ter certificado a qualidade das estimações de estado, partiu-se para sua utilização como uma alternativa de retroalimentação de controladores preditivos. Estes resultados foram comparados com os obtidos através da correção simples por bias. Os resultados experimentais apontam para uma marginal piora devido à retroalimentação por estimadores de estados frente à correção por bias, pelo menos para o caso do controlador preditivo linear utilizado na comparação. Entretanto, espera-se que resultados melhores sejam obtidos no caso de modelos preditivos não-lineares, uma vez que nestes casos o modelo é bem mais sensível à qualidade da condição inicial.The feedback of controllers that use predictive models in state space can be accomplished in two ways: (a) bias correction, where the predicted outputs are corrected by adding a value proportional to the discrepancy found between the current measurement and its respective prediction; and by (b) state feedback, which establishes the initial conditions through the states estimation, and from a better initial condition are carried out the future predictions used in the calculation of control. In this thesis these two approaches are compared using a Laboratorial Plant of Six Spherical Tanks. The techniques of Extended Kalman Filter (EKF) and Constraint Extended Kalman Filter (CEKF) were used to estimate the unmeasured states. Initially, tests were carried out off-line for theses estimation algorithms. For such testing are used a dataset of the plant in case study, in which are studied the influences of several adjustment factors that they determine the final quality of estimation. These adjustments were used of base for the application of these algorithms in real time, when then state estimators are associated with the system of process control based on a predictive control algorithm. After having ascertained the quality of the state estimates, begins its use as an alternative for feedback of predictive controllers. These results were compared with those obtained by the simple correction of bias. The experimental results show a marginal worsening due to feedback from state estimated compared with bias correction, at least for the case of linear predictive controller used in the comparison. However, one expects that better results will be obtained in the case of non-linear predictive models, since in these cases the model is much more sensitive to the quality of the initial condition.
30
Gullström, Charlie. "Presence Design : Mediated Spaces Extending Architecture." Doctoral thesis, KTH, Arkitektur, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-24448.
Full textAbstract:
This thesis is a contribution to design-led research and addresses a readership in the fields of architecture as well as in media and communications. In juxtaposing the tools of the designer (e.g. drafting, prototyping, visual/textual/spatial forms of montage) with those of architectural theory, this thesis seeks to extend the disciplinary boundaries of architecture by observing its assimilation of other media practices. Its primary contribution is to architectural design and theory, and its aims are twofold: Firstly, this thesis applies the concepts of virtual and mediated space to architecture, proposing an extended architectural practice that assimilates the concept of remote presence. Through realized design examples as well as through the history and theory of related concepts, the thesis explores what designing mediated spaces and designing for presence entails for the practicing architect. As a fusion of architecture and media technology, video-mediated spaces facilitate collaborative practices across spatial extensions while simultaneously fostering novel and environmentally sustainable modes of communication. The impact of presence design on workplace design is examined. As an extended practice also calls for an extended discourse, a preliminary conceptual toolbox is proposed. Concepts are adapted from related visual practices and tested on design prototypes, which arise from the author’s extensive experience in designing work and learning spaces. Secondly, this thesis outlines presence design as a transdisciplinary aesthetic practice and discusses the potential contribution of architects to a currently heterogeneous research field, which spans media space research, cognitive science, (tele)presence research, interaction design, ubiquitous computing, second-order cybernetics, and computer-supported collaborative work. In spite of such diversity, design and artistic practices are insufficiently represented in the field. This thesis argues that presence research and its discourse is characterised by sharp disciplinary boundaries and thereby identifies a conceptual gap: presence research typically fails to integrate aesthetic concepts that can be drawn from architecture and related visual practices. It is an important purpose of this thesis to synthesize such concepts into a coherent discourse. Finally, the thesis argues that remote presence through the proposed synthesis of architectural and technical design creates a significantly expanded potential for knowledge sharing across time and space, with potential to expand the practice and theory of architecture itself. The author’s design-led research shows that mediated spaces can provide sufficient audiovisual information about the remote space(s) and other person(s), allowing the subtleties of nonverbal communication to inform the interaction. Further, in designing for presence, certain spatial features have an effect on the user’s ability to experience a mediated spatial extension, which in turn, facilitates mediated presence. These spatial features play an important role in the process through which trust is negotiated, and hence has an impact on knowledge sharing. Mediated presence cannot be ensured by design, but by acknowledging the role of spatial design in mediated spaces, the presence designer can monitor and, in effect, seek to reduce the ‘friction’ that otherwise may inhibit the experience of mediated presence. The notion of ‘friction’ is borrowed from a context of knowledge sharing in collaborative work practices. My expanded use of the term ‘design friction’ is used to identify spatial design features which, unaddressed, may be said to impose friction and thus inhibit and impact negatively on the experience of presence. A conceptual tool-box for presence design is proposed, consisting of the following design concepts: mediated gaze, spatial montage, active spectatorship, mutual gaze, shared mediated space, offscreen space, lateral and peripheral awareness, framing and transparency. With their origins in related visual practices these emerge from the evolution of the concept of presence across a range of visual cultures, illuminating the centrality of presence design in design practice, be it in the construction of virtual pictorial space in Renaissance art or the generative design experiments of prototypical presence designers, such as Cedric Price, Gordon Pask and numerous researchers at MIT Media Lab, Stanford Institute and Xerox PARC.QC 20100909
31
Bezold, Maxwell. "AN ATTITUDE DETERMINATION SYSTEM WITH MEMS GYROSCOPE DRIFT COMPENSATION FOR SMALL SATELLITES." UKnowledge, 2013. http://uknowledge.uky.edu/ece_etds/29.
Full textAbstract:
This thesis presents the design of an attitude determination system for small satellites that automatically corrects for attitude drift. Existing attitude determination systems suffer from attitude drift due to the integration of noisy rate gyro sensors used to measure the change in attitude. This attitude drift leads to a gradual loss in attitude knowledge, as error between the estimated attitude and the actual attitude increases.
In this thesis a Kalman filter is used to complete sensor fusion which combines sensor observations with a projected attitude based on the dynamics of the satellite. The system proposed in this thesis also utilizes a novel sensor called the stellar gyro to correct for the drift. The stellar gyro compares star field images taken at different times to determine orientation, and works in the presence of the sun and during eclipse. This device provides a relative attitude fix that can be used to update the attitude estimate provided by the Kalman filter, effectively compensating for drift. Simulink models are developed of the hardware and algorithms to model the effectiveness of the system. The Simulink models show that the attitude determination system is highly accurate, with steady state errors of less than 1 degree.
32
Palazzo, Mônica Poli. "A experiência de Verô ou janela para Vera(cidade)." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/27/27159/tde-19112010-092109/.
Full textAbstract:
A Experiência de Verô ou Janela para Vera(cidade) aborda a multiplicidade de dimensões espaço-temporais que permeia a vida social a partir do avanço exponencial da tecnologia. A metodologia adotada no trabalho poético, a que este texto corresponde, segue a orientação da pesquisa da sensação, que propõe problematizar a experiência sensorial, considerando-a como fonte de problemas sensíveis. Foi construída uma videoinstalação composta por projeção em vídeo e cenário para funcionar como ambiente propício à experimentação polifônica de sensações oriundas de diversos dispositivos tecnológicos. A convergência dos elementos existentes no ambiente cenográfico está expressa nas janelas/telas que se multiplicam e caracterizam as diversas manifestações em vídeo de acontecimentos sincrônicos e diacrônicos. Janela para Vera(cidade) cria, a partir de operações poéticas audiovisuais, a possibilidade de uma experiência singular do corpo no espaço e no tempo, em que as interpenetrações multidimensionais simultâneas são uma constante.A Experiência de Verô ou Janela para Vera(cidade) addresses the multiple dimensions of space-time that permeates the social life from the exponential advance of technology. The methodology adopted in the poetic work follows the guidance of \"search of sensation,\" which aims to discuss the sensory experience, considering it as a source of sensitive issues. The video installation project consists in a video projection and a scenario. This environment conducts to a polyphonic sensations experiment, which comes from different technological devices. The convergence of elements in the environment is expressed in the scenic windows / screens that multiply and characterize the different kinds of events in video synchronic and diachronic. Experiência de Verô ou Janela para Vera(cidade) creates, from poetic audiovisual operations, the possibility of a singular experience of the body in space and time, where simultaneous multidimensional interrelationships are constant.
33
Hadish, Mulugeta. "Extended Multidimensional Conceptual Spaces in Document Classification." University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1227158181.
Full text
34
Chan, Hon-yin Paul. "An extended living environment for elders." Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B25946468.
Full text
35
Sartor, Fabien. "Modélisation de l'interopérabilité d'objets communicants et de leur coopération : application à la domotique." Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00748676.
Full textAbstract:
Dans le cadre des évolutions du bâtiment, il est de plus en plus nécessaire d'interconnecter des objets communicants. Cette démarche est cependant freinée du fait de l'absence d'un protocole de communication standard. La maison intelligente n'est pas un nouveau concept, et l'automatisation de la maison est devenue un sujet de recherche à la mode ces dernières années. La problématique de cette thèse se focalise sur l'interopérabilité de systèmes communicants. Plus précisément, nous nous intéressons à la manière de créer une coopération entre différents dispositifs d'un environnement, afin de masquer la complexité à l'usager. Dans un premier temps, l'interopérabilité entre ces objets est réalisée par la mise en place d'un écosystème virtuel où les dispositifs peuvent communiquer leurs états ou l'état de l'environnement. C'est l'abstraction des systèmes. Dans ce mémoire, nous abordons comment et pourquoi les systèmes sont nécessairement abstraits lorsque l'on s'intéresse à la prise en compte du contexte de l'installation. L'étude de la prise en compte du contexte à permis de procurer les données scientifiques à l'entreprise Overkiz afin qu'elle puisse réaliser l'abstraction des dispositifs domotiques. Ensuite, la coopération entre les objets communicants est mise en œuvre par un outil mathématique permettant de modéliser le comportement d'un environnement composé d'actionneurs, de capteurs et d'interfaces utilisateurs. Le comportement est formalisé au moyen de la théorie des automates étendus et plus particulièrement par la théorie des systèmes de transitions symboliques à entrées/sorties (IOSTS). Nous synthétisons alors le pilotage par un "contrôleur" du comportement global d'une installation, à partir de règles de contraintes ou de règles d'action.
36
Nash, Evan D. Nash. "Extended Tropicalization of Spherical Varieties." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1523979975350178.
Full text
37
Wells, Grant. "A comparison of multiple techniques for the reconstruction of entry, descent, and landing trajectories and atmospheres." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39611.
Full textAbstract:
The primary importance of trajectory reconstruction is to assess the accuracy of pre-flight predictions of the entry trajectory. While numerous entry systems have flown, often these systems are not adequately instrumented or the flight team not adequately funded to perform the statistical engineering reconstruction required to quantify performance and feed-forward lessons learned into future missions. As such, entry system performance and reliability levels remain unsubstantiated and improvement in aerothermodynamic and flight dynamics modeling remains data poor. The comparison is done in an effort to quantitatively and qualitatively compare Kalman filtering methods of reconstructing trajectories and atmospheric conditions from entry systems flight data. The first Kalman filter used is the extended Kalman filter. Extended Kalman filtering has been used extensively in trajectory reconstruction both for orbiting spacecraft and for planetary probes. The second Kalman filter is the unscented Kalman filter. Additionally, a technique for using collocation to reconstruct trajectories is formulated, and collocation's usefulness for trajectory simulation is demonstrated for entry, descent, and landing trajectories using a method developed here to deterministically find the state variables of the trajectory without nonlinear programming. Such an approach could allow one to utilize the same collocation trajectory design tools for the subsequent reconstruction.
38
Guo, Gaoshan. "Inversion de la forme d'onde complète à source étendue dans le domaine temporel : théorie, algorithme et application." Electronic Thesis or Diss., Université Côte d'Azur, 2024. http://www.theses.fr/2024COAZ5014.
Full textAbstract:
La Full waveform inversion (FWI) est devenue la méthode d'imagerie de référence en exploration géophysique. FWI utilise les formes d'ondes complètes pour imager le sous-sol avec une résolution d'un demi longueur d'onde. Etant donné la dimension de l'espace des données et des modèles, la FWI est implémentée avec des méthodes d'optimisation locale sur un espace de recherche réduit où l'équation d'onde est résolue exactement à chaque itération. Cela requiert des modèles initiaux précis pour que les données simulées prédisent les données enregistrées sans saut de phase. Pour relâcher cette condition, plusieurs variantes de la FWI ont été proposées telles que les approches sur des espaces de recherche étendus. Parmi ces approches, la 'Wavefield Reconstruction Inversion (WRI)' implémente l'équation d'onde comme une contrainte faible pour ajuster les observables avec des champs d'onde calculées avec des sources étendues. Les extensions de sources sont estimées en ajustant au sens des moindres carrés la différence entre les données enregistrées et simulées traitées comme les données diffractées enregistrées. Il en résulte que ces sources volumiques sont calculées par renversement temporel (retro-propagation) des résidus déconvolués par le Hessien dans l'espace des données. Cette approche est nommée 'extended-source' FWI (ES-FWI).Dans cette thèse, je développe un algorithme opérationnel pour la ES-FWI. Le premier problème est le calcul des sources volumiques où la déconvolution des résidus par le Hessien est coûteuse. Des études précédentes approximent ce Hessien avec une matrice diagonale ce qui peut suffire dans des contextes favorables mais sujet à des minimums secondaires dans des milieux complexes. Je propose d'approximer l'inverse du Hessien par des filtres de Wiener/Gabor. Des tests numériques sur le modèle Marmousi II démontrent les améliorations apportées par ces filtres comparativement à l'approximation diagonale. Les champs d'ondes calculés avec l'assimilation des données ont une précision qui diminue loin des points de mesure ce qui peut piéger l'inversion dans des minimums secondaires. Pour améliorer la robustesse de la méthode, j'ai implémenté des opérateurs de pondération dans l'espace des données pour injecter progressivement des donnés plus complexes dans l'inversion et reconstruire le milieu de la surface vers les niveaux profonds. Cette approche de 'layer stripping' est illustrée avec les géomodèles complexes 2004 BP Salt et GO3DOBS.La ES-FWI est une forme généralisée de la FWI où l'inverse du Hessien du problème de source est utilisé comme une matrice de pondération dans l'espace des données. Cela engendre une décomposition du Hessien en un opérateur diagonal dans le domaine des sources et un opérateur par source dans l'espace des données représentant le Hessien du problème de source évoqué ci dessus. Je montre comment ré-utiliser cette décomposition dans la FWI pour développer une approximation du Hessien Gauss-Newton qui puisse être calculée efficacement tout en accélérant la convergence de la FWI. Alternativement, l'approximation proposée peut être utilisée comme préconditioneur pour des algorithmes de quasi-Newton.Finalement, j'étends l'application de la reconstruction des champs d'onde avec assimilation des données au problème de ‘redatuming'. Cette application requiert des champs d'ondes de haute précision si bien que j'implémente la déconvolution des données diffractées avec le solveur itératif MINRES plutôt qu'avec des filtres de Gabor. L'approche consiste simplement à calculer les champs d'onde avec l'assimilation des données et à les échantillonner sur la surface d'acquisition virtuelle. Cette approche est précise lorsqu'on connaît le milieu situé entre les surfaces définies par les acquisitions réelle et virtuelle. Le ‘redatuming' des sources et des capteurs peuvent être couplés. Cette approche est illustrée avec des géomodèles marins et terrestres et avec un jeu de données réels de fond de merFull waveform inversion (FWI) has emerged as the baseline seismic imaging method in exploration geophysics. Given the size of the data and model spaces, FWI relies on iterative local optimization methods and reduced search space where the wave equation is strictly satisfied at each iteration. This framework requires an accurate initial model allowing for the simulated data to match the recorded data with kinematic errors less than half the period to avoid cycle skipping. To mitigate cycle skipping, several variants of FWI have been developed over the last decade such as extended-space FWI where degrees of freedom are added to the forward problem. Among them, the wavefield reconstruction inversion (WRI) implements the wave equation as a soft constraint to match the data by combining a wave-equation relaxation with data assimilation. While WRI has been initially implemented in the frequency domain where the data-assimilated wavefields can be computed with linear algebra methods, the time-domain implementation with explicit time-marching schemes has proven challenging. It was recently recognized that the source extensions generated by the wave-equation relaxation are the least-squares solutions of the scattered-data fitting problem. As such, they are computed by backward modeling of deconvolved FWI data residuals by the data-domain Hessian. This reformulation of the wavefield reconstruction as a scattering source reconstruction has led to the extended-source FWI (ES-FWI).In this thesis, I develop a practical algorithm for ES-FWI. Firstly, I focus on the efficient computation of the source extensions where the deconvolution of the data residuals by the data-domain Hessian is the main computational bottleneck. Previous studies implement the Hessian with a scaled identity matrix, which is acceptable in certain favorable scenarios but prone to failure in complex media. I propose a more accurate approximation of the inverse Hessian with various matching filters such as 1D/2D Wiener and Gabor filters. Numerical tests conducted on the Marmousi II model show the relevance of these approximations. Moreover, the data-assimilated wavefields primarily consist of the ‘migration/demigration' of the recorded data. Accordingly, their accuracy diminishes away from the receivers, which can drive the inversion towards spurious minima in particular when surface multiples are involved in the inversion. To address this issue, I design a weighting operator based on time-offset windowing in the data misfit function to inject progressively more complex data in the inversion and reconstruct the medium from the shallow parts to the deep ones. The application of the BPsalt model illustrates the relevance of this layer-stripping scheme in a very challenging context.ES-FWI can be recast as a generalized FWI, where the data misfit function is weighted by the inverse data-domain Hessian of the source extension problem. This leads to a decomposition of the Gauss-Newton (GN) Hessian into a diagonal source-side Hessian and source-dependent receiver-side data-domain Hessians. I use this decomposition to propose a computationally efficient approximation of the GN Hessian. I approximate the inverse Hessian with 2D Gabor matching filters, which can be readily used as an approximation of the GN Hessian or as a preconditioner for the quasi-Newton method. Numerical tests demonstrate the improved convergence speed of FWI provided by this Hessian.Finally, I extend the application of the data-assimilated wavefield reconstruction towards seismic redatuming, where highly-accurate wavefield reconstruction is necessary. This prompts me to use the iterative solver to perform the deconvolution of the scattered data. Using reciprocity, I can chain source and receiver redatuming. Numerical tests and application to ocean-bottom seismic data validate the effectiveness of the proposed method
39
Chan, Hon-yin Paul, and 陳漢賢. "An extended living environment for elders." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B31984393.
Full text
40
Roch, Douglas Oliver. "Inhabiting extended physical spaces : intersections of spatiality, teacher collegiality and power." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/43900.
Full textAbstract:
This study examined experiences of teachers working in extended physical spaces (those added to an existing school building such as built additions or modular classrooms) in the case of a growing British Columbia elementary school in which there was a perceived lack of physical space. Specifically, I looked at the intersections of spatiality, teacher constructions of collegiality, and power relations with regards to working in extended spaces, and how these concepts affected teacher work lives and professional interactions. In this study, spatiality refers to human constructions of space and place that occur through our social interactions with others within the physical environment, and collegiality is defined as teachers’ involvement with peers on a variety of levels. Through use of a critical symbolic interactionist lens and a conceptualization of power from a feminist empowerment (power-with) model, I sought to understand how these teachers interpreted symbols representing organizational values and norms within the broad school culture, the meanings they derived from the extended physical spaces, and how socio-spatial relations were produced.
Data obtained through observation, document analysis, and interviews suggested teachers derive meaning from extended physical spaces based upon how their workspace allows them to carry out their work role. These spaces were symbolized as being separate from the original building. Generally, teachers believed inhabiting extended physical spaces had the potential to contribute to a lessening quality and quantity of interactions with other teachers, and to make resources less accessible. Teachers constructed six broad categories of collegial interactions which were largely based upon their ability to interact with colleagues through space and took the form of socio-spatial enactments that were reflections of negotiated organizational culture. Findings indicated teachers inhabiting extended physical spaces had the potential to feel tension as they attempted to enact the organizational values that characterized the school while simultaneously experiencing a new spatiality. However, through strategies of empowerment and a distributed-leadership model, teachers and administrators were able to mitigate much of the potential disadvantage that could occur through inhabiting extended spaces, thereby producing new, inclusive spatialities and opportunities for socio-spatial dialogue and community growth.
41
Labsir, Samy. "Méthodes statistiques fondées sur les groupes de Lie pour le suivi d'un amas de débris spatiaux." Thesis, Bordeaux, 2020. http://www.theses.fr/2020BORD0294.
Full textAbstract:
Dans le contexte de la surveillance spatiale, nous nous intéressons à un amas de débris évoluant en orbite autour de la Terre et observé par un capteur radar.Il est alors constaté que l'ensemble des débris se disperse selon une forme bananoïdale due à leur mouvement contraint par les lois de Kepler.Cette répartition est représentative d'échantillons gaussiens concentréssur le groupe de Lie SE(3) et peut être complètement caractérisée par unematrice de covariance inconnue.Nous proposons dans cette thèse une reformulation originale sur groupe de Liedu modèle d'observation de l'amas. Ce dernier est alors modélisé comme une cibleétendue caractérisée par sa forme et et son centroïde. De cette manière, nous reconsidéronsl'estimation de ces derniers comme un problème d'inférence sur variété.La géométrie de l’amas est ainsi intrinsèquement prise en compte. Deux algorithmes sur groupes de Liesont alors proposés afin d'estimer respectivement de manière statique et dynamique les paramètres de l'amas.Dans une première partie du manuscrit, l'enjeu de la surveillance spatiale est souligné et les principales méthodes de pistage de débris sont rappelées.Dans une seconde partie, les fondements des groupes de Lie sontprésentés. La troisième partie est axée sur les contributions de la thèse etpropose un modèle et deux algorithmes d'estimation de la forme et du centroïde d’un amas qui sont ensuite testés sur différents scénarios de simulation.La dernière partie est consacrée à une contribution théorique danslaquelle est mise en place une borne d'erreur d'estimation bayésienne sur groupe de LieIn the context of space surveillance, we are interested in a cluster of debris evolving in orbit around the Earth and observed by a radar sensor.It is then observed that the debris spreads out taking a bananoid shape due to their movement constrained by Kepler's laws.This distribution is representative of concentrated Gaussian samples on the Lie group SE (3) and can be completely characterized by anunknown covariance matrix.We propose in this thesis an original reformulation of the cluster observation model on Lie groups. The latter is then modeled as an extended targetcharacterized by its shape and its centroid. In this way, we reconsiderits estimation as a manifold inference problem.The geometry of the cluster is thus intrinsically taken into account. Two algorithms on Lie groups are then proposed in order to estimate respectively statically and dynamically the parameters of the cluster.In the first part of the manuscript, the issue of space surveillance is underlined and the main methods for tracking debris are recalled.In a second part, the foundations of Lie groups arepresented. The third part focuses on the contributions of the thesis andproposes a model and two algorithms for estimating the shape and centroid of a cluster which are then tested on different simulation scenarios.The last part is devoted to a theoretical contribution inwhich is proposed a bound for Bayesian estimation error on Lie groups
42
SERRELLI, EMANUELE. "Adaptive landscapes: a case study of metaphors, models, and synthesis in evolutionary biology." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2011. http://hdl.handle.net/10281/19338.
Full textAbstract:
This dissertation brings a contribution to the philosophical debate on adaptive landscapes, an influent "model" or "metaphor" in evolutionary biology. Some elements of innovation are: the distinction between native and migrant metaphor; a processual and communicational idea on what the Modern Synthesis was, and on what role a metaphor could have played in it; a view (taken by Richard Lewontin) of the disunity and theoretical structure of population genetics; the distinction between “adaptive surfaces” (mainly metaphors) and “combination spaces”, two terms normally conflated in the word “landscape”; an analysis of what bridges (including heuristics) may be cast between equations of gene frequency and the genotype space that, due to its huge dimensionality, cannot be handled by mathematics; a specified vocabulary to be used to clear the adaptive landscapes debate, accompanied by a plea in favor of a pragmatic approach - for example, the plurality of available notions of model forces us to choose one notion and see where it brings, otherwise we get stuck in confused, endless debates; an updated analytical comment of recent landscapes - Dobzhansky, Simpson, Dawkins but also the proliferation of combination spaces used in evolutionary biology to address a great variety of problems; the vision (got by Sergey Gavrilets) of a patchwork of tools finally making Mendelian population suitable model also for speciation; the exact position of holey landscapes in this patchwork, and the idea that scientists’s questions - like “how possibly” questions - matter in accessing this patchwork and in deciding “what explains” and “what describes” what in the world; the direct response to some mistakes Massimo Pigliucci made, I think, in his assessment of the adaptive landscape; an analysis of the Extended Evolutionary Synthesis project at its present stage, and some reflections on the conditions that will allow such a project to give a fair treatment and a good position to tools from the past, like the adaptive landscapes.
43
Alveteg, Ellen. "Dra stråken till sin spets : En undersökning av extended techniques för viola genom instudering av Viola Spaces av Garth Knox." Thesis, Luleå tekniska universitet, Institutionen för konst, kommunikation och lärande, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-69373.
Full textAbstract:
Efter att ha gått en kurs i fri improvisation där jag fick utforska min violas möjligheter till att producera ljud, väcktes en nyfikenhet hos mig kring utökade speltekniker som kan förekomma i nutida konstmusik, så kallade extended techniques. Jag fick tips om etydsamlingen Viola Spaces av Garth Knox där olika extended techniques presenteras och bestämde mig för att studera in fyra av dem. De etyderna jag valde behandlar olika stråktekniker, nämligen sul ponticello, sul tasto, tremolo och olika sätt att dra stråken på. Under arbetets gång redogör jag för de svårigheter jag stötte på under min inlärningsprocess av etyderna samt hur jag gick till väga för att lösa dem. Arbetet redovisas dels genom videoinspelningar som jag gjorde i samband med mina övningstillfällen och dels genom material från de anteckningar jag förde under processen. Jag tar också upp tolkningsfrågor av notationen och reflekterar kring instruktionerna om hur musiken ska framföras. Arbetet har resulterat i att jag känner mig bättre förberedd på att spela nutida konstmusik än vad jag gjorde tidigare. Jag har också utökat min kunskap om olika stråktekniker.
44
Garcez, de Oliveira Krone Martins Alberto. "Plus loin avec la mission spatiale Gaia grâce à l'analyse des objets étendus." Thesis, Bordeaux 1, 2011. http://www.theses.fr/2011BOR14241/document.
Full textAbstract:
Ce travail a comme objectif principal de vérifier s’il est possible de faire de la science avec les observations d’objets étendus qui seront réalisées par la mission spatiale Gaia. Cette mission, l’un des plus ambitieux projets de l’Astronomie moderne,observera plus d’un milliard d’objets dans tout le ciel avec des précisions inédites, fournissant des données astrométriques, photométriques et spectroscopiques. Naturellement, en fonction de sa priorité astrométrique, Gaia a été optimisé pour l’étude d’objets ponctuels. Néanmoins, diverses sources associées à des émissions étendues seront observées. Ces émissions peuvent avoir une origine intrinsèque, telles que les galaxies, ou extrinsèque, telles que les projections d’objets distincts sur la même ligne de visée, et présenteront probablement de solutions astrométriques moins bonnes.Pour étudier ces émissions, leurs images bidimensionnelles doivent être analysées.Néanmoins, comme Gaia ne produit pas de telles données, nous avons commencé ce travail en vérifiant si à partir de ses observations unidimensionnelles il serait possible de reconstruire des images 2D d’objets dans tout le ciel.Nous avons ainsi estimé la quantité de cas sujets à la présence d’émissions étendues extrinsèques, et nous avons présenté une méthode que nous avons développée pour analyser leurs images reconstruites. Nous avons montré que l’utilisation de cette méthode permettra d’étendre le catalogue final de façon fiable à des millions de sources ponctuelles dont beaucoup dépasseront la magnitude limite de l’instrument.D’un autre coté, dans le cas d’émissions intrinsèques, nous avons premièrement obtenu une estimation supérieure du nombre de cas que Gaia pourra observer. Nous avons alors vérifié qu’après les reconstructions d’images, les codes que nous avons développés permettront de classifier morphologiquement des millions de galaxies dans les types précoce/tardif et elliptique/spirale/irrégulière. Nous avons de plus présenté une méthode que nous avons développée pour réaliser la décomposition bulbe/disque directement à partir des observations unidimensionnelles de Gaia de façon complètement automatique.Finalement nous avons conclu qu’il est possible d’utiliser beaucoup de ces données qui pourraient être ignorées pour faire de la science. Et que le fait de les exploiter permettra aussi bien la détection de millions d’objets qui dépassent la limite de magnitude de Gaia, que de mener des études sur la morphologie de millions de galaxies dont les structures ne peuvent être révélées qu’à partir de l’espace ou au moyen d’optique adaptative, augmentant un peu plus les horizons de cette mission déjà immenseThe main objective of this work is to determine whether it is possible to do science from the observations of extended objects that will be performed by the Gaia space mission. One of the most ambitious projects of modern Astronomy, this mission will observe more than one billion objects through out the sky, thus providing astrometric, photometric and spectroscopic data with unprecedented precision. Naturally, Gaia has been optimized for the study of point-like sources due to its astrometrical priority. Nevertheless, many sources associated with extended emission will be observed. The origins of these extended sources can be either intrinsic, such as galaxies, or extrinsic, such as projections of objects in the same line of sight. In both cases, these sources will have less than optimal astrometric solutions.In order to study those emissions, their two-dimensional images will be analyzed. Nonetheless, since Gaia will not acquire such images, we begin this work by checking whether it will be possible to reconstruct images anywhere in the sky from the satellite’s one-dimensional observations.Consequently, we, on the one hand, estimate the number of cases which will be subjected to the extrinsic extended emissions, present a method which we developed to analyze the reconstructed images by segregating the different sources and show that the adoption of this method will allow extending the catalogue reliably by millions of point sources, many of which are beyond the limiting magnitude of the instrument. On the other hand, regarding intrinsic extended emissions, we first obtain an upper limit estimate for the number of cases which Gaia will be able to observe ; then,we verify that the combination of image reconstructions and the use of the codes introduced here in will allow performing the morphological classification of millions of galaxies in early/late types and elliptical/spiral/irregular classes. Afterward,we present a method which we developed to decompose those galaxies into their bulge/disk components directly from the one-dimensional Gaia data in a completely automatic way. Finally, we conclude that it is possible to harness the data of many of the observations that might other wise be ignored to do science. Saving these data will allow the detection of millions of objects beyond Gaia’s limiting magnitude and the study of the morphology of millions of galaxies whose structures can only be probed from space or through the adoption of adaptive optics, thus somewhat expanding the horizons of this already comprehensive mission
45
Tamagnini, Filippo. "EKF based State Estimation in a CFI Copolymerization Reactor including Polymer Quality Information." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/20235/.
Full textAbstract:
State estimation is an integral part of modern control techniques, as it allows to characterize the state information of complex plants based on a limited number of measurements and the knowledge of the process model. The benefit is twofold: on one hand it has the potential to rationalize the number of measurements required to monitor the plant, thus reducing costs, on the other hand it enables to extract information about variables that have an effect on the system but would otherwise be inaccessible to direct measurement.
The scope of this thesis is to design a state estimator for a tubular copolymerization reactor, with the aim to provide the full state information of the plant and to characterize the quality of the product.
Due to the fact that, with the existing set of measurements, only a small number of state variables can be observed, a new differential pressure sensor is installed in the plant to provide the missing information, and a model for the pressure measurement is developed.
Following, the state estimation problem is approached rigorously and a comprehensive method for analyzing, tuning and implementing the state estimator is assembled from scientific literature, using a variety of tools from graph theory, linear observability theory and matrix algebra. Data reduction and visualization techniques are also employed to make sense of high dimensional information.
The proposed method is then tested in simulations to assess the effect of the tuning parameters and measured set on the estimator performance during initialization and in case of estimation with plant-model mismatch.
Finally, the state estimator is tested with plant data.
46
Narayanan, Shankar. "Gas assisted thin-film evaporation from confined spaces." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42780.
Full textAbstract:
A novel cooling mechanism based on evaporation of thin liquid films is presented for thermal management of confined heat sources, such as microprocessor hotspots. The underlying idea involves utilization of thin nanoporous membranes for maintaining microscopically thin liquid films by capillary action, while providing a pathway for the vapor generated due to evaporation at the liquid-vapor interface. The vapor generated by evaporation is continuously removed by using a dry sweeping gas keeping the membrane outlet dry. This thesis presents a detailed theoretical, computational and experimental investigation of the heat and mass transfer mechanisms that result in dissipating heat.
Performance analysis of this cooling mechanism demonstrates heat fluxes over 600W/cm2 for sufficiently thin membrane and film thicknesses (~1-5µm) and by using air jet impingement for advection of vapor from the membrane surface. Based on the results from this performance analysis, a monolithic micro-fluidic device is designed and fabricated incorporating micro and nanoscale features. This MEMS/NEMS device serves multiple functionalities of hotspot simulation, temperature sensing, and evaporative cooling. Subsequent experimental investigations using this microfluidic device demonstrate heat fluxes in excess of 600W/cm2 at 90 C using water as the evaporating coolant.
In order to further enhance the device performance, a comprehensive theoretical and computational analysis of heat and mass transfer at micro and nanoscales is carried out. Since the coolant is confined using a nanoporous membrane, a detailed study of evaporation inside a nanoscale cylindrical pore is performed. The continuum analysis of water confined within a cylindrical nanopore determines the effect of electrostatic interaction and Van der Waals forces in addition to capillarity on the interfacial transport characteristics during evaporation. The detailed analysis demonstrates that the effective thermal resistance offered by the interface is negligible in comparison to the thermal resistance due to the thin film and vapor advection. In order to determine the factors limiting the performance of the MEMS device on a micro-scale, a device-level detailed computational analysis of heat and mass transfer is carried out, which is supported by experimental investigation. Identifying the contribution of various simultaneously occurring cooling mechanisms at different operating conditions, this analysis proposes utilization of hydrophilic membranes for maintaining very thin liquid films and further enhancement in vapor advection at the membrane outlet to achieve higher heat fluxes.
47
Carroll, James Lamond. "A Bayesian Decision Theoretical Approach to Supervised Learning, Selective Sampling, and Empirical Function Optimization." Diss., CLICK HERE for online access, 2010. http://contentdm.lib.byu.edu/ETD/image/etd3413.pdf.
Full text
48
Kristina, Ćulibrk Medić. "Програмски и социјални аспекти односа објеката културе и отворених простора у Новом Саду." Phd thesis, Univerzitet u Novom Sadu, Fakultet tehničkih nauka u Novom Sadu, 2020. https://www.cris.uns.ac.rs/record.jsf?recordId=114885&source=NDLTD&language=en.
Full textAbstract:
У предметној докторској дисертацији намера је да се сагледају потенцијалии могућности ангажовања отворених простора уз објекте културе НовогСада и да се утврди интензитет утицаја продужене функције објекта нањегово функционисање у програмском и социјалном смислу, као и утицај наурбани квалитет свог окружења. Планирано је истраживање постојећегстања оваквих простора у Новом Саду и дефинисање релевантних фактораза њихово ангажовање, валоризовање, класификовање и формирањетипологија са циљем њихове употребе и примене за даља истраживања итрансформације.U predmetnoj doktorskoj disertaciji namera je da se sagledaju potencijalii mogućnosti angažovanja otvorenih prostora uz objekte kulture NovogSada i da se utvrdi intenzitet uticaja produžene funkcije objekta nanjegovo funkcionisanje u programskom i socijalnom smislu, kao i uticaj naurbani kvalitet svog okruženja. Planirano je istraživanje postojećegstanja ovakvih prostora u Novom Sadu i definisanje relevantnih faktoraza njihovo angažovanje, valorizovanje, klasifikovanje i formiranjetipologija sa ciljem njihove upotrebe i primene za dalja istraživanja itransformacije.
In dissertation the intention is to look at the potentials and possibilities ofengaging open spaces with cultural facilities in Novi Sad and to determinethe intensity of the impact of the extended function of the facility on itsfunctioning in program in social terms, as well as the impact on urban quality.It is planned to research the current state of such spaces in Novi Sad anddefine relevant factors for their engagement, valorization, classification andformation of typologies with the aim of their use and application for furtherresearch and transformation.
49
Reynders, Nadia. "Interface : altering architecture : transforming existing mono-functional buildings in the Pretoria CBD to adapt to changing social spatial conditions. The notion of ‘altering architecture’ aims to manipulate existing boundaries into INTERFACES to affect interior spaces and building skins as well extend into the urban context." Diss., University of Pretoria, 2010. http://hdl.handle.net/2263/30070.
Full textAbstract:
In a globalised world, influenced by social flux brought about by various factors¹, cities’ perimeters are subject to continuous change. More often than not, a city’s perimeter expands in the form of urban sprawl. Energy drains from the centre, leaving in its wake numerous vacant, degraded and underutilised structures. Radical interventions on an urban scale are often proposed to counter this degradation and transformation of such urban areas. These interventions² entail densification of the urban fabric, the insertion of additional structures and the creation of new precincts; a process which occurs over many years. By comparison, well-considered alterations to existing built fabric can be implemented quickly with smaller financial and ecological implications. Such alterations also include the adaptation of interior space to support a change in programme, and the possible improvement of a buildings interface with the street. The aim is to improve local social environments within the urban fabric and stimulate social influx. INTERFACE is about interventions to existing structures within the CBD of Pretoria. These interventions are limited to low-rise buildings (between two and five stories) designed specifically for mono-function. Over time, the programme and user profile of those buildings has changed, while the built fabric stagnated, with no active response to its context. Currently, such buildings do not participate in the creation of a living city – a city where interior spaces are supplemented by well designed outdoor spaces, thereby creating places that support and encourage social interaction. Buildings which have simply been taken over and used ad hoc, have not truly been adapted to their new programmes and as such, full exploitation of the space is not possible. Interior spaces can therefore play a determining role in the social motion³ of the city, but only if they address the transition between interior and exterior space, and the extension of such transition into the subsequent urban fabric. These interior and exterior spaces should be adaptable to current social needs of city dwellers and users in order to be deemed successful. Living cities require buildings to adapt and change in response to ever shifting social conditions in order to satisfy basic human desires and needs. It can thus be deduced that a building programme will more than likely change regularly. INTERFACE therefore focus on the creation of responsive interior space and works from the premise that structure and interior are implicitly linked. This thesis explores ‘permanent’ changes to existing structures; changes that will assist in creating responsive interior environments. Such environments should also accommodate both semi-permanent and temporary alterations, with minimal impact⁴ resulting from the implementation of each new programme. 1 Factors: Include change in political, social and economical circumstances. 2 Interventions: In Pretoria CBD, large interventions are proposed over long periods of time. They include strategies such as the Tshwane City Strategy (twenty year),Tshwane Inner City Development and Regeneration Strategy 2005 (ten year program) and City of Tshwane Integrated Development Plan 2009/2010 (five year). 3 Social motion: Interaction and attraction of civilians in a space 4 Impact: Refer to alterations to the permanent responsive structure as well as financial and ecological implications.Dissertation (MInt(Prof))--University of Pretoria, 2010.
Architecture
unrestricted
50
Kalmykova, Elena. "Dissolving Dualism : A Tripartite Model of Cognition for Religious Truth." Doctoral thesis, Uppsala universitet, Religionsfilosofi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-150622.
Full textAbstract:
This investigation can be described as a long journey to a final destination: a truth in religion. We start by considering dualism of the subjective and the objective, the classical model of cognition that underlies notions of truth. Dualistic notions of cognition lead to serious problems, especially for religious truth. Religions claim to state truths about the nature of the universe and human destiny, but these truths are incompatible. With a dualistic model this problem of diversity of religious truths leads to fundamentalism or relativism. Thus, this research aims to turn to the roots of the cognitive situation and investigate the way we cognize and relate to the world to provide a better model. As we consider the philosophical theories and empirical investigations of cognition, we come to the conclusion that dualism of the subjective and objective is not tenable. As the findings of contemporary mind sciences and phenomenologically oriented research indicate, human cognition is embodied, embedded, enacted, extended, and shaped by language. Thus, I propose to re-conceptualize the cognitive situation to provide a better philosophical account. I put forward a tripartite model of cognition, which unites language, action, and environment. The consequent application of this model to the issues of truth and religion shows that we can avoid the problem of diversity of truth claims. A tripartite model allows us to explain how we can maintain religion as true, despite the diversity of religious truth claims. Additionally, as this model is fundamental, its application leads to various new findings and inferences, which render anew the world and the way humans relate to it. Thus, our journey brings us to new frontiers of investigation.