Дисертації з теми "Data dynamics"
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1
Bone, Jeffrey. "Instantaneous dynamics of functional data." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/59491.
Повний текст джерелаАнотація:
Time dynamic systems can be used in many applications to data modeling. In the case of longitudinal data, the dynamics of the underlying differential equation can often be inferred under minimal assumptions via smoothing based procedures. This is in contrast to the common technique of assuming a prespecified differential equation, and estimating it's parameters. In many cases, one wants to learn the dynamics of a differential equation that incorporates more than just one stochastic process. In the following, we propose extensions to existing two-step smoothing methods that allow for the presence of additional functional data arising from a second stochastic process. We further introduce model comparison techniques to assess the hypothesis that there is a significant change in fit provided by this additional process. These techniques are applied to the instantaneous dynamics of mouse growth data and allow us to make comparisons between mice who have been assigned different genetic and physical conditions. Finally, to study the statistical properties of our proposed techniques, we carry out a simulation study based on the mouse growth data. Supplementary material : http://hdl.handle.net/2429/59574Science, Faculty of
Statistics, Department of
Graduate
2
Brown, Hannah Marie. "Data Driven Modeling of Dynamics." The Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu1618835986278106.
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3
Ibeh, Neke. "Inferring Viral Dynamics from Sequence Data." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/35317.
Повний текст джерелаАнотація:
One of the primary objectives of infectious disease research is uncovering the direct
link that exists between viral population dynamics and molecular evolution. For
RNA viruses in particular, evolution occurs at such a rapid pace that epidemiological
processes become ingrained into gene sequences. Conceptually, this link is easy to
make: as RNA viruses spread throughout a population, they evolve with each new
host infection. However, developing a quantitative understanding of this connection
is difficult. Thus, the emerging discipline of phylodynamics is centered on reconciling
epidemiology and phylogenetics using genetic analysis. Here, we present two research studies that draw on phylodynamic principles in order to characterize the progression and evolution of the Ebola virus and the human immunodefficiency virus (HIV). In the first study, the interplay between selection and epistasis in the Ebola virus genome is elucidated through the ancestral reconstruction of a critical region in the Ebola virus glycoprotein. Hence, we provide a novel mechanistic account of the structural changes that led up to the 2014 Ebola virus outbreak. The second study applies an approximate Bayesian computation (ABC) approach to the inference of epidemiological parameters. First, we demonstrate the accuracy of this approach with simulated data. Then, we infer the dynamics of the Swiss HIV-1 epidemic, illustrating the applicability of this statistical method to the public health sector. Altogether, this
thesis unravels some of the complex dynamics that shape epidemic progression, and
provides potential avenues for facilitating viral surveillance efforts.
4
Wang, Yi. "Integrating data mining and system dynamics." Thesis, Cardiff University, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.606794.
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5
Marzi, Tommaso. "Dynamical models for pedestrian dynamics using data from pedestrian flow sensors." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/21219/.
Повний текст джерелаАнотація:
The purpose of this thesis is to give a contribution in a wider project regarding the development of new tools for the governance of tourist flows in Venice. Because of the virus COVID-19, this topic has increased in interest, since it can be used both to look for possible solutions to make public places safer and to study the spread of the virus itself.
Once the testing of the sensors that provide the data on mobility is carried out, a macroscopic approach to the pedestrian dynamics based on the Fundamental Diagram is proposed: scenarios with different geometries as streets, crossroads or bridges are compared, focusing in particular on representative parameters of the model.
In the last part, a microscopic approach to pedestrian mobility is presented: a simulation model is calibrated on the basis of the available data, in order to define whether it can actually reproduce the behaviour of a crowd.
6
Ruiter, Julia. "Practical Chaos: Using Dynamical Systems to Encrypt Audio and Visual Data." Scholarship @ Claremont, 2019. https://scholarship.claremont.edu/scripps_theses/1389.
Повний текст джерелаАнотація:
Although dynamical systems have a multitude of classical uses in physics and applied mathematics, new research in theoretical computer science shows that dynamical systems can also be used as a highly secure method of encrypting data. Properties of Lorenz and similar systems of equations yield chaotic outputs that are good at masking the underlying data both physically and mathematically. This paper aims to show how Lorenz systems may be used to encrypt text and image data, as well as provide a framework for how physical mechanisms may be built using these properties to transmit encrypted wave signals.
7
Ross, Natalie. "The dynamics of point-vortex data assimilation." Connect to online resource, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3303865.
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8
Peng, Zhenmin. "Interactive visualization of computational fluid dynamics data." Thesis, Swansea University, 2011. https://cronfa.swan.ac.uk/Record/cronfa42757.
Повний текст джерелаАнотація:
This thesis describes a literature study and a practical research in the area of flow visualization, with special emphasis on the interactive visualization of Computational Fluid Dynamics (CFD) datasets. Given the four main categories of flow visualization methodology; direct, geometric, texture-based and feature-based flow visualization, the research focus of our thesis is on the direct, geometric and feature-based techniques. And the feature-based flow visualization is highlighted in this thesis. After we present an overview of the state-of-the-art of the recent developments in the flow visualization in higher spatial dimensions (2.5D, 3D and 4D), we propose a fast, simple, and interactive glyph placement algorithm for investigating and visualizing boundary flow data based on unstructured, adaptive resolution boundary meshes from CFD dataset. Afterward, we propose a novel, automatic mesh-driven vector field clustering algorithm which couples the properties of the vector field and resolution of underlying mesh into a unified distance measure for producing high-level, intuitive and suggestive visualization of large, unstructured, adaptive resolution boundary CFD meshes based vector fields. Next we present a novel application with multiple-coordinated views for interactive information-assisted visualization of multidimensional marine turbine CFD data. Information visualization techniques are combined with user interaction to exploit our cognitive ability for intuitive extraction of flow features from CFD datasets. Later, we discuss the design and implementation of each visualization technique used in our interactive flow visualization framework, such as glyphs, streamlines, parallel coordinate plots, etc. In this thesis, we focus on the interactive visualization of the real-world CFD datasets, and present a number of new methods or algorithms to address several related challenges in flow visualization. We strongly believe that the user interaction is a crucial part of an effective data analysis and visualization of large and complex datasets such as CFD datasets we use in this thesis. In order to demonstrate the use of the proposed techniques in this thesis, CFD domain experts reviews are also provided.
9
Dunton, Alec. "Topological Data Analysis for Systems of Coupled Oscillators." Scholarship @ Claremont, 2016. http://scholarship.claremont.edu/hmc_theses/79.
Повний текст джерелаАнотація:
Coupled oscillators, such as groups of fireflies or clusters of neurons, are found throughout nature and are frequently modeled in the applied mathematics literature. Earlier work by Kuramoto, Strogatz, and others has led to a deep understanding of the emergent behavior of systems of such oscillators using traditional dynamical systems methods. In this project we outline the application of techniques from topological data analysis to understanding the dynamics of systems of coupled oscillators. This includes the examination of partitions, partial synchronization, and attractors. By looking for clustering in a data space consisting of the phase change of oscillators over a set of time delays we hope to reconstruct attractors and identify members of these clusters.
10
Torn, Ryan. "Using ensemble data assimilation for predictability and dynamics /." Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/10037.
Повний текст джерела
11
Lundvall, Johan. "Data Assimilation in Fluid Dynamics using Adjoint Optimization." Doctoral thesis, Linköping : Matematiska institutionen, Linköpings universitet, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-9684.
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12
Visser, Wilhelmina Josefine. "Updating structural dynamics models using frequency response data." Thesis, Imperial College London, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262548.
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13
Pokern, Yvo. "Fitting stochastic differential equations to molecular dynamics data." Thesis, University of Warwick, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.439586.
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14
Mirhi, Mohamad H. (Mohamad Hussein). "Design of interactive maps for ocean dynamics data." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/121860.
Повний текст джерелаАнотація:
Thesis: M. Eng., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2019Cataloged from PDF version of thesis.
Includes bibliographical references.
Comprehensive spatiotemporal modeling and forecasting systems for ocean dynamics necessitate robust and efficient data delivery and visualization techniques. The multi-disciplinary simulation, estimation, and assimilation systems group at MIT (MSEAS) focuses on capturing and predicting diverse ocean dynamics, including physics, acoustics, and biology on varied scales, thereby developing new methods for multi-resolution ocean prediction and analysis, including data generation and assimilation. The group has primarily used non-interactive ocean plots to visualize its simulated and measured data. Although these maps and sections allow for analysis of ocean physics and the underlying numerical schemes, more interactive maps provide more user control over depicted data, allowing easier study and pattern identification on multiple scales. Integrating static and geospatial data in dynamic visualization creates a heightened viewpoint for analysis, enhances ocean monitoring and prediction, and contributes to building scientific knowledge. This thesis focuses on explaining the motivation behind and the methodologies applied in designing these interactive maps.
by Mohamad Mirhi.
M. Eng.
M.Eng. Massachusetts Institute of Technology, Department of Mechanical Engineering
15
Drobek, Marc. "Data-driven system dynamics modelling : model formulation and KPI prediction in data-rich environments." Thesis, Queen's University Belfast, 2017. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.725834.
Повний текст джерелаАнотація:
System Dynamics (SD) is a key methodology for analysing complex, highly non-linear feedback systems. The SD modelling procedure is traditionally based on domain expert knowledge, manual modelling tasks and a parameter estimation and equation formulation process. These tasks are, however, heavily manual and complex since the required information was not expected to be available from written and numerical data sources. In recent years, we have seen an explosion in monitored and tracked system data that became known as the Big Data paradigm shift. This change has not yet found its way into the SD domain. Within this thesis, a novel data-driven SD modelling methodology for data-rich environments is proposed to address this paradigm shift. The research work carried out in this thesis exptores the potential of utilising massively available data sources for the SD modelling process. Based on these data sources, a modelling methodology (Fexda) is presented that supports the SD modeller in a systematic fashion whilst preserving the key principles of SD modelling. Unlike the traditional SD modelling, Fexda as a data-driven approach is highly sensitive to changes in the given data, which enables a continuous evolution ana optimisation of the computed SD models ana their parameters and equations. These contributions are based on advances in other domains, such as econometric modelling, data mining and machine learning, which are incorporated in a novel way for Fexda. A detailed evaluation of the proposed Fexda methodology is further provided against a business use-case scenario to demonstrate technical feasibility of the approach and to provide comparative results with traditional approaches. The evaluation clearly shows that Fexda can be employed to produce reliable and accurate SD models and provide insightful simulation results. The proposed Fexda methodology is the ground work towards data-driven SD modelling. A range of potential future research directions are proposed to further strengthen Fexda. The thesis concludes by presenting a revised version of the traditional information sources model that caters the reality of the Big Data paradigm shift.
16
Gerdom, Christopher Martin. "Nanosatellite Launch Data-Logger (Sync)." DigitalCommons@CalPoly, 2018. https://digitalcommons.calpoly.edu/theses/1966.
Повний текст джерелаАнотація:
CubeSat designers are increasingly looking to incorporate delicate structures and optics into their payloads. These delicate payloads, however, may not survive the required absolute-worst-case launch vibration testing needed for flight certification. To help address this problem, and to better match testing conditions to real-world launch environments, this thesis introduces Sync, a compact 1/4U CubeSat payload designed to collect data on the vibrations and thermal environments CubeSats experience inside a deployer on the way to orbit. This data can be used to better understand the launch environment for different vehicles, and help develop new, more realistic testing guidelines that could enable more delicate payloads to be launched.
17
Nienhaus, Marc, Bruce Gooch, and Jürgen Döllner. "Visualizing movement dynamics in virtual urban environments." Universität Potsdam, 2006. http://opus.kobv.de/ubp/volltexte/2009/3306/.
Повний текст джерелаАнотація:
Dynamics in urban environments encompasses complex processes and phenomena such as related to movement (e.g.,traffic, people) and development (e.g., construction, settlement).
This paper presents novel methods for creating human-centric illustrative maps for visualizing the movement dynamics in virtual 3D environments. The methods allow a viewer to gain rapid insight into traffic density and flow. The illustrative maps represent vehicle behavior as light threads. Light threads are a familiar visual metaphor caused by moving light sources producing streaks in a long-exposure photograph. A vehicle’s front and rear lights produce light threads that convey its direction of motion as well as its velocity and acceleration. The accumulation of light threads allows a viewer to quickly perceive traffic flow and density. The light-thread technique is a key
element to effective visualization systems for analytic reasoning, exploration, and monitoring of geospatial processes.
18
Fuller, Janice L. "Holocene forest dynamics in southern Ontario, Canada." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319318.
Повний текст джерела
19
Bertani, Federico. "Reconstruction of vehicle dynamics from inertial and GNSS data." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/16105/.
Повний текст джерелаАнотація:
The increasingly massive collection of data from various types of sensors installed on vehicles allows the study and reconstruction of their dynamics in real time, as well as their archiving for subsequent analysis.
This Thesis describes the design of a numerical algorithm and its implementation in a program that uses data from inertial and geo-positioning sensors, with applications in industrial contexts and automotive research. The result was made usable through the development of a Python add-on for the Blender graphics program, able to generate a three-dimensional view of the dynamics that can be used by experts and others.
Throughout the Thesis, particular attention was paid to the complex nature of the data processed, introducing adequate systems for filtering, interpolation, integration and analysis, aimed at reducing errors and simultaneously optimizing performances.
20
Chen, Chao. "Understanding social and community dynamics from taxi GPS data." Phd thesis, Institut National des Télécommunications, 2014. http://tel.archives-ouvertes.fr/tel-01048662.
Повний текст джерелаАнотація:
Taxis equipped with GPS sensors are an important sensory device for examining people's movements and activities. They are not constrained to a pre-defined schedule/route. Big taxi GPS data recording the spatio-temporal traces left by taxis provides rich and detailed glimpse into the motivations, behaviours, and resulting dynamics of a city's mobile population through the road network. In this dissertation, we aim to uncover the "hidden facets" regarding social and community dynamics encoded in the taxi GPS data to better understand how urban population behaves and the resulting dynamics in the city. As some "hidden facets" are with regard to similar aspect of social and community dynamics, we further formally define three categories for study (i.e. social dynamics, traffic dynamics, and operational dynamics), and explore them to fill the wide gaps between the raw taxi GPS data and innovative applications and smart urban services. Specifically, 1. To enable applications of real-time taxi fraud alerts, we propose iBOAT algorithm which is capable of detecting anomalous trajectories "on-the-fly" and identifying which parts of the trajectory are responsible for its anomalousness, by comparing them against historically trajectories having the same origin and destination. 2. To introduce cost-effective and environment-friendly transport services to citizens, we propose B-Planner which is a two-phase approach, to plan bi-directional night bus routes leveraging big taxi GPS data. 3. To offer a personalized, interactive, and traffic-aware trip route planning system to users, we propose TripPlanner system which contains both offline and online procedures, leveraging a combination of Location-based Social Network (i.e. LBSN) and taxi GPS data sets. Finally, some promising research directions for future work are pointed out, which mainly attempt to fuse taxi GPS data with other data sets to provide smarter and personalized urban services for citizens
21
Li, Mengyao. "P53 dynamics: single-cell imaging data analysis and modeling." HKBU Institutional Repository, 2014. https://repository.hkbu.edu.hk/etd_oa/59.
Повний текст джерелаАнотація:
The p53 protein plays a central role in controlling the fate of cancer cells. At moderate levels of DNA damage, the concentration of the phosphorylated form of p53 undergoes temporal oscillation with a period of a few hours. In Dr. Shi’s lab, single-cell measurements were carried out using the p53-YFP fusion proteins and time-lapse fluorescence microscopy. We report here a detailed study of the image data. From the time series of the p53 concentration in individual cells, we deduce the amplitude and period of the oscillation. The pulse-to-pulse and cell-to-cell variability of the oscillation is characterized. We then carry out a computational study of a mathematical model that involves a negative feedback loop between p53 and Mdm2 proteins. We have determined the phase diagram of the model, and studied the sensitivity of the properties of the oscillating state against the model parameters. Although only p53 concentration is measured in the experiment, we show that careful analysis of the pulse shape can nevertheless yield valuable information on the underlying molecular processes, and shed light on the possible origin of the observed cellto- cell variations.
22
Aksoy, Altug. "Mesoscale ensemble-based data assimilation and parameter estimation." Texas A&M University, 2005. http://hdl.handle.net/1969.1/2523.
Повний текст джерелаАнотація:
The performance of the ensemble Kalman filter (EnKF) in forced, dissipative
flow under imperfect model conditions is investigated through simultaneous state and
parameter estimation where the source of model error is the uncertainty in the model
parameters. Two numerical models with increasing complexity are used with simulated
observations.
For lower complexity, a two-dimensional, nonlinear, hydrostatic, non-rotating,
and incompressible sea breeze model is developed with buoyancy and vorticity as the
prognostic variables. Model resolution is 4 km horizontally and 50 m vertically. The
ensemble size is set at 40. Forcing is maintained through an explicit heating function
with additive stochastic noise. Simulated buoyancy observations on land surface with
40-km spacing are assimilated every 3 hours. Up to six model parameters are
successfully subjected to estimation attempts in various experiments. The overall EnKF
performance in terms of the error statistics is found to be superior to the worst-case scenario (when there is parameter error but no parameter estimation is performed) with
an average error reduction in buoyancy and vorticity of 40% and 46%, respectively, for
the simultaneous estimation of six parameters.
The model chosen to represent the complexity of operational weather forecasting
is the Pennsylvania State University-National Center for Atmospheric Research MM5
model with a 36-km horizontal resolution and 43 vertical layers. The ensemble size for
all experiments is chosen as 40 and a 41st member is generated as the truth with the
same ensemble statistics. Assimilations are performed with a 12-hour interval with
simulated sounding and surface observations of horizontal winds and temperature. Only
single-parameter experiments are performed focusing on a constant inserted into the
code as the multiplier of the vertical eddy mixing coefficient. Estimation experiments
produce very encouraging results and the mean estimated parameter value nicely
converges to the true value exhibiting a satisfactory level of variability.
23
Pascual, Blanca. "Uncertainty quantification for complex structures : statics and dynamics." Thesis, Swansea University, 2012. https://cronfa.swan.ac.uk/Record/cronfa42987.
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24
Simonotto, Jennifer Delight. "Analysis of spatiotemporal cardiac excitation data and stimulated Brillouin scattering data using nonlinear dynamics principles." Thesis, Heriot-Watt University, 2005. http://hdl.handle.net/10399/236.
Повний текст джерела
25
Münkemüller, Tamara. "Density regulation: linking theory and applications to understand population - to community -level dynamics and responses to environmental change /." Leipzig : UFZ, 2008. http://www.ufz.de/data/ufzdiss_09_20089156.pdf.
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26
Zhang, Wenbing. "A method and program for quantitative description of fracture data and fracture data extrapolation from scanline or wellbore data /." May be available electronically:, 2001. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
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27
Tsui, Alban Pui Man. "Smooth data modelling and stimulus-response via stabilisation of neural chaos." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325403.
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28
Ogunbadewa, Ebenezer Yemi. "Evaluating medium resolution satellite data for monitoring seasonal vegetation dynamics." Thesis, University of Salford, 2009. http://usir.salford.ac.uk/26845/.
Повний текст джерелаАнотація:
Quantitative monitoring of vegetation change over time is essential in understanding the environmental processes of which are important in climate change and global warming models, because vegetation change is an indicator of environmental variability. However, obtaining such information has been a challenge especially for vegetation phenology due to the lack of appropriate methods for quantitative assessment. There is therefore a need to derive methods to quantitatively characterize vegetation dynamics in order to monitor the effect of climate change on the biosphere and as inputs to global change models. The aim of this research was to test the relationships between ground-based measurement of leaf area index (LAI) and vegetation indices (VI) derived from satellite remote sensing instruments to quantitatively monitor vegetation dynamics in a broadleaf and coniferous forest in the UK. This research has four key hypotheses. First, phenological changes (which is the timing of recurring biological events in plants) in broadleaf and coniferous forest canopies may be characterized using ground-based measurement of LAI, because LAI is good proxy for vegetation phenology. Second, cloud cover frequency in the UK leads to a requirement for higher temporal resolution remote sensing data to monitor changes in vegetation phenology. Third, data from the Disaster Monitoring Constellation (DMC) satellites provides a sufficiently high temporal resolution for monitoring vegetation phenology in the UK. Fourth, vegetation indices derived from atmospherically corrected DMC data may be used to monitor vegetation phenology in the UK. Analysis of Advanced Very High Resolution Radiometer (AVHRR) and Moderate Resolution Imaging Spectroradiometer (MODIS) cloud mask showed that the average of number of cloud free days at the UK test sites in the year 2005 was five days per month with a minimum of one cloud free day per month implying that high temporal resolution satellites like the DMC will be appropriate for monitoring vegetation change. Nine DMC satellite images were acquired over 2005/2006 for the study sites plus one coincident Landsat ETM+ in 2005. Four vegetation indices (VI) were derived from the satellite data sets and were related to LAI/PAI. PAI is the plant area index defined as the total surface area of both photosynthetic and nonphotosynthetic part of plant per unit ground area. A regression model was used to predict LAI/PAI and the root mean square error (RMSE) was determined for both sites. The RMSE of the observed and predicted LAI values show that the levels of errors at Risley Moss were 0.51 for LAI, 0.52 for overstorey PAI and 0.8 for total canopy while PAI was 1.1 for Charter's Moss. Therefore, the DMC and one Landsat ETM+ data set related to LAI/PAI can adequately retrieve biophysical parameter in the deciduous woodland. However, in the coniferous canopy the numbers of observations was fewer and the measurement errors larger leading to a requirement for more data in order to establish statistically significant and ecologically useful relationships. Improvements in the accuracy of ground-based LAI/PAI measurements, radiometric and atmospheric correction of satellite data are expected to increase the accuracy of such LAI/PAI estimates in future.
29
Arthur, Daniel J. W. "Diffusion modelling and industry dynamics in mobile telecoms data services." Thesis, University of Surrey, 2008. http://epubs.surrey.ac.uk/843191/.
Повний текст джерелаАнотація:
The market growth of content and data services in the mobile telecoms industry entails the development of complex industry networks or 'ecosystems'. This research stems from the emerging Location-Based Services (LBS) sector, which has suffered the slow-start dynamics that often belie optimistic forecasts of new technologies. An exploratory and generic industry-level model is developed using the system dynamics simulation modelling approach to explain the start-up problem. This serves as a dynamic theory for the emerging LBS industry market where service diffusion is based on the growth of the installed base of an embedded product. Supply-demand interactions occur through complementary bandwagon effects in which benefits accrue from services that complement the main product. Econometric estimation is compared with system dynamics calibration to test a range of diffusion models on historic data, revealing some evidence of bandwagon effects. The model is proposed as a generic structure for market growth in mobile data services in general and as a tentative theory to explain the phenomenon of technology 'hype' cycles. The model leads to broad policy proposals on how to alleviate the start-up problem. Launching products without attending to service quality can mean that consumers become disillusioned whereas ensuring a high quality user experience requires a collaborative and long-term view of ecosystem development. This implies that major players such as handset manufacturers or mobile operators must play a central co-ordinating role. Validation of exploratory models of emerging markets is based more in terms of plausibility and usefulness, given the lack of historic data. A validation framework in the three dimensions of model content, process and outcome provides a holistic and semi-quantitative profile of the utility of generic models. A validation profile is proposed that can be used in a formative role to clarify model purpose and aid planning in model-based interventions.
30
Bourhis, Pierre. "On the dynamics of active documents for distributed data management." Phd thesis, Université Paris Sud - Paris XI, 2011. http://tel.archives-ouvertes.fr/tel-00598299.
Повний текст джерелаАнотація:
One of the major issues faced by Web applications is the management of evolving of data. In this thesis, we consider this problem and in particular the evolution of active documents. Active documents is a formalism describing the evolution of XML documents by activating Web services calls included in the document. It has already been used in the context of the management of distributed data \cite{axml}. The main contributions of this thesis are theoretical studies motivated by two systems for managing respectively stream applications and workflow applications. In a first contribution, we study the problem of view maintenance over active documents. The results served as the basis for an implementation of stream processors based on active documents called Axlog widgets. In a second one, we see active documents as the core of data centric workflows and consider various ways of expressing constraints on the evolution of documents. The implementation, called Axart, validated the approach of a data centric workflow system based on active documents. The hidden Web (also known as deep or invisible Web), that is, the partof the Web not directly accessible through hyperlinks, but through HTMLforms or Web services, is of great value, but difficult to exploit. Wediscuss a process for the fully automatic discovery, syntacticand semantic analysis, and querying of hidden-Web services. We proposefirst a general architecture that relies on a semi-structured warehouseof imprecise (probabilistic) content. We provide a detailed complexityanalysis of the underlying probabilistic tree model. We describe how wecan use a combination of heuristics and probing to understand thestructure of an HTML form. We present an original use of a supervisedmachine-learning method, namely conditional random fields,in an unsupervised manner, on an automatic, imperfect, andimprecise, annotation based on domain knowledge, in order to extractrelevant information from HTML result pages. So as to obtainsemantic relations between inputs and outputs of a hidden-Web service, weinvestigate the complexity of deriving a schema mapping between databaseinstances, solely relying on the presence of constants in the twoinstances. We finally describe a model for the semantic representationand intensional indexing of hidden-Web sources, and discuss how toprocess a user's high-level query using such descriptions.
31
Imamovic, Nedzad. "Validation of large structural dynamics models using modal data test." Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299781.
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Needham, Jessica. "Harnessing demographic data for cross-scale analysis of forest dynamics." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:156850fa-3148-45a6-b2f8-ada9dd3f6a7f.
Повний текст джерелаАнотація:
Forests are a critical biome but are under threat from unprecedented global change. The need to understand forest dynamics across spatial, temporal and biological scales has never been greater. Critical to this will be understanding how the demographic rates of individuals translate into patterns of species diversity, biomass and carbon turnover at much larger scales. In this thesis, I present a modelling framework focussed on demography. In Chapter 2, I introduce methods for translating forest inventory data into population models that account for the size-dependency of vital rates and persistent differences in individual performance. Outbreaks of forest pest and pathogens are increasing in frequency and severity, with consequences for biodiversity and forest structure. In Chapter 3, I explore the impact of ash dieback on the community dynamics of a British woodland, describing a spatially explicit individual based model that captures the effect of an opening of the canopy on local competitive interactions. Chapter 4 introduces methods to infer the impact of historical deer herbivory on the juvenile survival of forest trees. The approach is generalisable and could be applied to any forest in which patterns of regeneration and community structure have been impacted by periodic disturbance (e.g. forest fires). Finding meaningful ways of incorporating species diversity into global vegetation models is increasingly recognised as a research priority. In Chapter 5, I explore the diversity of demographic rates in a tropical forest community and identify groups of species with similar life history strategies. I discuss the potential of integrating demographic and physiological traits as a way to aggregate species for inclusion in global models. In summary, translating measurements of individuals into population dynamics provides opportunities to both explore small-scale community responses to disturbance events, and to feed into much larger scale vegetation models.
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Felisa, Giada <1983>. "Dynamics of coastal aquifers: data-driven forecasting and risk analysis." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amsdottorato.unibo.it/7177/.
Повний текст джерелаАнотація:
This work is focused on the study of saltwater intrusion in coastal aquifers, and in particular on the realization of conceptual schemes to evaluate the risk associated with it.
Saltwater intrusion depends on different natural and anthropic factors, both presenting a strong aleatory behaviour, that should be considered for an optimal management of the territory and water resources. Given the uncertainty of problem parameters, the risk associated with salinization needs to be cast in a probabilistic framework. On the basis of a widely adopted sharp interface formulation, key hydrogeological problem parameters are modeled as random variables, and global sensitivity analysis is used to determine their influence on the position of saltwater interface. The analyses presented in this work rely on an efficient model reduction technique, based on Polynomial Chaos Expansion, able to combine the best description of the model without great computational burden.
When the assumptions of classical analytical models are not respected, and this occurs several times in the applications to real cases of study, as in the area analyzed in the present work, one can adopt data-driven techniques, based on the analysis of the data characterizing the system under study. It follows that a model can be defined on the basis of connections between the system state variables, with only a limited number of assumptions about the "physical" behaviour of the system.
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Sadun, Raffaella. "Productivity dynamics of the UK economy : a micro data perspective." Thesis, London School of Economics and Political Science (University of London), 2008. http://etheses.lse.ac.uk/2171/.
Повний текст джерелаАнотація:
This dissertation analyzes two factors which may lie behind the recent productivity surge in the US, the lack of productivity growth in Europe and, ultimately, the persistence of significative differences in the levels of productivity across the two macro areas. First, we analyse the role played by Information Technologies (IT). Second, we study the impact of specific regulatory policies, focusing on the consequences of regulations which constrain the entry of large and peripheral retail stores ("big-boxes"). These issues are explored in the context of the UK economy, whose recent economic performance is consistent with the overall European picture of sluggish productivity growth (Basu et al., 2003). Furthermore, the questions are approached from a micro data perspective, using a series of novel establishment and firm-level datasets drawn from Census data sources. In the first two essays I focus on the role played by Information Technologies (IT), which appear to have played a substantial role in driving the recent productivity surge of the US economy. Chapter I sets out a theoretical and empirical context in which to study the impact of IT on productivity. Chapter II discusses the effects of IT on a large panel of firms active in the UK economy, observed between 1995 and 2003. A key finding of the study is the apparent ability of US multinationals to obtain higher productivity than non-US multinationals (and domestic UK establishments) from their IT capital. Chapter III, IV and V are dedicated to the study of the retail industry, which accounts for a large part of the European productivity gap vis a vis the US over the past decade. In particular, we study the effect of entry regulations against large retail stores ("big-boxes"). In Chapter III, it is shown that the recent introduction of entry regulations against large stores in the UK has paradoxically increased the competition faced by mom and pops retailers. Chapter IV show evidence that entry regulations have also significantly lowered the productivity of UK retail chains, forcing them to operate at a lower scale of retail activity. This result is set in an international context in Chapter V, where the market structure and the productivity dynamics of the UK retail industry with that of the US and Japan are compared using novel Census data sources.
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Markovic, Bratislav. "Data driven estimation of cabin dynamics in heavy-duty vehicles." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-276946.
Повний текст джерелаАнотація:
With increasing demand for autonomous systems and self-driving heavy-dutyvehicles there is an even more increasing demand for safety. In order to achievedesired safety level on the public roads, engineers have to tackle many technicalissues, like decision making, object detection and perception. In order to detect anobject or to have an understanding of its surroundings, autonomous heavy-dutyvehicles are equipped with different types of sensors. These sensors are placed ondifferent parts of the autonomous truck. The fact that some parts of the truckare highly dynamical introduces additional disturbances to the signals comingfrom onboard sensors. One of the most dynamic parts of every truck is its cabin.Moving cabin may induce additional disturbances into data coming from sensorsattached to it. This corrupted data may lead the autonomous trucks to make wrongdecisions. In the worst case, such decisions may be fatal.This thesis uses a data driven modeling approach for creating a mathematicaldescription of cabin movements based on data from onboard sensors. For thatpurpose, tools from system identification field are used. The resulting modelsare aimed to be used for implementation of real-time estimation algorithm forthe cabin dynamics, which in turn can be used for real-time compensation of thedisturbances.Ee ökad efterfrågan efter autonoma fordon sätter ännu högre krav på säkerhet.Eftersom mäniskors säkerhet alltid prioriteras högst så måste ingenjörer runtom i världen att se till att framtida självkörande lastbilar inte bara är heltautonoma utan framför allt säkra. För att uppnå önskad säkerhetsnivå på deallmänna vägarna måste ingenjörerna ta itu med många tekniska problem, somexempelvis beslutsfattande, objektdetektering och perception. För att upptäckaett föremål eller att förstå sin omgivning är autonoma lastbilar numera utrustademed olika typer av sensorer. Dessa sensorer är monterade på olika delar av denautonoma lastbilen. Det faktum att vissa delar av en lastbil är mycket dynamiskaintroducerar ytterligare störningar i signler som kommer från de sensorer somfinns monterade på fordonet. En av de mest dynamiska delarna av varje lastbilär hytten. Hyttens rörelser kan orsaka ytterligare störningar i data som kommerfrån sensorer som är anslutna till den. Den felaktiga informationen kan ledatill att det autonoma fordonet fattar felaktiga beslut, som i värsta skulle kunnaorsaka dödsfall. Detta examensarbete använder sig av datadriven modelleringför att beskriva det matematiska förhållandet mellan hytt och chassi baserat pådata som kommer från de sensorer som finns monterade på fordonet. För attdetta ändamål skulle kunna uppnås används systemidentifieringsteknik. Bådegrey-box och black-box systemidentifieringsmetod användas och jämföras för attkunna erhålla ett resultat som visar vilken av de två teknikerna är bäst lämpad fördetta ändamål.
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Blank, Clas. "Automatic vs. Manual Data Labeling : A System Dynamics Modeling Approach." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-279572.
Повний текст джерелаАнотація:
Labeled data, which is a collection of data samples that have been tagged with one or more labels, play an important role many software organizations in today's market. It can help in solving automation problems, training and validating machine learning models, or analysing data. Many organizations therefore set up their own labeled data gathering system which supplies them with the data they require. Labeling data can either be done by humans or be done via some automated process. However, labeling datasets comes with costs to these organizations. This study will examine what this labeled data gathering system could look like and determine which components that play a crucial role when determining how costly an automatic approach is compared to a manual approach using the company Klarna's label acquisition system as a case study. Two models are presented where one describes a system that solely uses humans for data annotation, while the other model describes a system where labeling is done via an automatic process. These models are used to compare costs to an organization taking those approaches. Important findings include the identification of important components that affects which approach would be more economically efficient to an organization under certain circumstances. Some of these important components are the label decay rate, automatic and manual expected accuracy, and number of data points that require labeling.Annoterad data, vilket är en kollektion utav datapunkter som har blivit annoterade med en eller flera taggar, spelar en viktig roll för många mjukvaruföretag i dagens marknad. Det kan hjälpa till att lösa automatiseringsingsproblem, träna och validera maskininlärningsmodeller, eller analysera data. Många organisationer sätter därför upp sina egna dataannoteringssystem som kan leverera den annoterade data som behövs inom organisationen. Annotering kan göras av människor, men kan också göras via en automatiserad process. Emellertid kommer annotering utav data med kostnader för organisationen. Denna studie undersöker hur ett sådant dataannoteringssystem kan se ut och analyserar vilka komponenter som spelar en betydande roll när kostnader mellan ett automatiserat system och ett manuellt system ska jämföras. Klarnas dataannoteringssystem kommer att användas som en case-studie. Två modeller presenteras varav den ena beskriver ett system där enbart manuellt annoteringsarbete utförs, och den andra beskriver ett system där annotering utav data utförs via en automatisk process. Några viktiga resultat av denna studie är identifikationen utav betydelsefulla parametrar i modellerna när det kommer till att jämföra den ekonomiska effektiviteten mellan de två olika dataannoteringsstrategierna. Exempel på dessa komponenter är annoteringens förfalltakt, den förväntade manuella/automatiska pricksäkerheten, och mängden data som behöver annoteras.
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Beaumont, Robin Nicholas. "Dynamics of stratospheric sudden warming events : data analysis and modelling." Thesis, University of Exeter, 2014. http://hdl.handle.net/10871/15956.
Повний текст джерелаАнотація:
The polar vortex is a large scale cyclone located in the middle atmosphere near to the planet’s geographic poles. These vortices form during the hemispheric winter and break down in the spring of the following year. They may also break down in mid winter, causing a sudden stratospheric warming event (SSW). The vortex is thought to be preconditioned leading up to these warming events, resulting in the breakdown of the vortex. Integral diagnostics are used to investigate the stripping of air from the vortex as part of this preconditioning. Contour diagnostics of mass and circulation are calculated using ERA-40 reanalysis data for the stratosphere. The edge of the vortex is easily identifiable in these diagnostics as a high gradient of Ertel’s potential vorticity (PV), and the warming events are also clearly visible. From these the amount of air removed from the vortex is determined from the balance equation of the mass integral. These terms show that there are significant amounts of air removed from the vortex, with several stripping events identifiable in them through the winter, especially in those during which a major sudden warming event occurred. These stripping events can be seen in corresponding PV maps, where tongues of PV can be seen to be stripped from the vortex and mixed into the surrounding surf zone of turbulent air. From the integral diagnostics a Lagrangian measure of the meridional circulation in the stratosphere is also calculated. In the final part of the thesis a shallow water model is used to investigate a quantitative link between forcing and the amount of stripping of the vortex. It is found that when the forcing is large enough there is significant stripping of mass from the vortex. This does not lead to SSWs in all cases, and the total amount of stripping is not found to be proportional to the maximum amplitude of the forcing.
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Radou, Gaël. "Helicase functional dynamics from low-resolution experimental data and simulation." Thesis, University of Leeds, 2015. http://etheses.whiterose.ac.uk/11694/.
Повний текст джерелаАнотація:
The biological function of large macromolecular assemblies depends on their structure and their dynamics over a broad range of timescales; for this reason its investigation poses significant challenges to conventional experimental techniques. A promising experimental technique is hydrogen-deuterium exchange detected by mass spectrometry (HDX-MS). I begin by presenting a new computational method for quantitative interpretation of deuterium exchange kinetics. The method is tested on a hexameric viral helicase φ12 P4 that pumps RNA into a virus capsid at the expense of ATP hydrolysis. Molecular dynamics simulations predict accurately the exchange kinetics of most peptide fragments and provide a residue-level interpretation of the low-resolution experimental results. This approach is also a powerful tool to probe mechanisms that cannot be observed by X-ray crystallography, or that occur over timescales longer than those that can be realistically simulated, such as the opening of the hexameric ring. Once validated, the method is applied on a homologous system, the packaging motor φ8 P4, for which RNA loading and translocation mechanisms remain elusive. Quantitative interpretation of HDX-MS data, as well as Förster resonance energy transfer (FRET) and computational observations, suggest that the C-terminal domain of the motor plays a crucial role. A new translocation model of φ8 P4 is proposed, for which the affinity between the motor and RNA is modulated by the C-termini. In the final result chapter, the amount of the structural information carried by HDX-MS data is quantitatively analysed. The impact of the averaging of the exchange over peptide fragments on the information content is investigated. The complementarity of data obtained from HDX-MS and data obtained from other techniques (such as NMR, FRET or SAXS) is also examined.
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Gámez, López Antonio Juan. "Application of nonlinear dimensionality reduction to climate data for prediction." Phd thesis, Universität Potsdam, 2006. http://opus.kobv.de/ubp/volltexte/2006/1095/.
Повний текст джерелаАнотація:
This Thesis was devoted to the study of the coupled system composed by El Niño/Southern Oscillation and the Annual Cycle. More precisely, the work was focused on two main problems:
1. How to separate both oscillations into an affordable model for understanding the behaviour of the whole system.
2. How to model the system in order to achieve a better understanding of the interaction, as well as to predict future states of the system.
We focused our efforts in the Sea Surface Temperature equations, considering that atmospheric effects were secondary to the ocean dynamics. The results found may be summarised as follows:
1. Linear methods are not suitable for characterising the dimensionality of the sea surface temperature in the tropical Pacific Ocean. Therefore they do not help to separate the oscillations by themselves. Instead, nonlinear methods of dimensionality reduction are proven to be better in defining a lower limit for the dimensionality of the system as well as in explaining the statistical results in a more physical way [1]. In particular, Isomap, a nonlinear modification of Multidimensional Scaling methods, provides a physically appealing method of decomposing the data, as it substitutes the euclidean distances in the manifold by an approximation of the geodesic distances. We expect that this method could be successfully applied to other oscillatory extended systems and, in particular, to meteorological systems.
2. A three dimensional dynamical system could be modeled, using a backfitting algorithm, for describing the dynamics of the sea surface temperature in the tropical Pacific Ocean. We observed that, although there were few data points available, we could predict future behaviours of the coupled ENSO-Annual Cycle system with an accuracy of less than six months, although the constructed system presented several drawbacks: few data points to input in the backfitting algorithm, untrained model, lack of forcing with external data and simplification using a close system. Anyway, ensemble prediction techniques showed that the prediction skills of the three dimensional time series were as good as those found in much more complex models. This suggests that the climatological system in the tropics is mainly explained by ocean dynamics, while the atmosphere plays a secondary role in the physics of the process. Relevant predictions for short lead times can be made using a low dimensional system, despite its simplicity. The analysis of the SST data suggests that nonlinear interaction between the oscillations is small, and that noise plays a secondary role in the fundamental dynamics of the oscillations [2].
A global view of the work shows a general procedure to face modeling of climatological systems. First, we should find a suitable method of either linear or nonlinear dimensionality reduction. Then, low dimensional time series could be extracted out of the method applied. Finally, a low dimensional model could be found using a backfitting algorithm in order to predict future states of the system.Das Ziel dieser Arbeit ist es das Verhalten der Temperatur des Meers im tropischen Pazifischen Ozean vorherzusagen. In diesem Gebiet der Welt finden zwei wichtige Phänomene gleichzeitig statt: der jährliche Zyklus und El Niño. Der jährliche Zyklus kann als Oszillation physikalischer Variablen (z.B. Temperatur, Windgeschwindigkeit, Höhe des Meeresspiegels), welche eine Periode von einem Jahr zeigen, definiert werden. Das bedeutet, dass das Verhalten des Meers und der Atmosphäre alle zwölf Monate ähnlich sind (alle Sommer sind ähnlicher jedes Jahr als Sommer und Winter des selben Jahres). El Niño ist eine irreguläre Oszillation weil sie abwechselnd hohe und tiefe Werte erreicht, aber nicht zu einer festen Zeit, wie der jährliche Zyklus. Stattdessen, kann el Niño in einem Jahr hohe Werte erreichen und dann vier, fünf oder gar sieben Jahre benötigen, um wieder aufzutreten. Es ist dabei zu beachten, dass zwei Phänomene, die im selben Raum stattfinden, sich gegenseitig beeinflussen. Dennoch weiß man sehr wenig darüber, wie genau el Niño den jährlichen Zyklus beeinflusst, und umgekehrt. Das Ziel dieser Arbeit ist es, erstens, sich auf die Temperatur des Meers zu fokussieren, um das gesamte System zu analysieren; zweitens, alle Temperaturzeitreihen im tropischen Pazifischen Ozean auf die geringst mögliche Anzahl zu reduzieren, um das System einerseits zu vereinfachen, ohne aber andererseits wesentliche Information zu verlieren. Dieses Vorgehen ähnelt der Analyse einer langen schwingenden Feder, die sich leicht um die Ruhelage bewegt. Obwohl die Feder lang ist, können wir näherungsweise die ganze Feder zeichnen wenn wir die höchsten Punkte zur einen bestimmten Zeitpunkt kennen. Daher, brauchen wir nur einige Punkte der Feder um ihren Zustand zu charakterisieren. Das Hauptproblem in unserem Fall ist die Mindestanzahl von Punkten zu finden, die ausreicht, um beide Phänomene zu beschreiben. Man hat gefunden, dass diese Anzahl drei ist. Nach diesem Teil, war das Ziel vorherzusagen, wie die Temperaturen sich in der Zeit entwickeln werden, wenn man die aktuellen und vergangenen Temperaturen kennt. Man hat beobachtet, dass eine genaue Vorhersage bis zu sechs oder weniger Monate gemacht werden kann, und dass die Temperatur für ein Jahr nicht vorhersagbar ist. Ein wichtiges Resultat ist, dass die Vorhersagen auf kurzen Zeitskalen genauso gut sind, wie die Vorhersagen, welche andere Autoren mit deutlich komplizierteren Methoden erhalten haben. Deswegen ist meine Aussage, dass das gesamte System von jährlichem Zyklus und El Niño mittels einfacherer Methoden als der heute angewandten vorhergesagt werden kann.
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Restrepo, Juan M., and Shankar Venkataramani. "Stochastic longshore current dynamics." ELSEVIER SCI LTD, 2016. http://hdl.handle.net/10150/621938.
Повний текст джерелаАнотація:
We develop a stochastic parametrization, based on a 'simple' deterministic model for the dynamics of steady longshore currents, that produces ensembles that are statistically consistent with field observations of these currents. Unlike deterministic models, stochastic parameterization incorporates randomness and hence can only match the observations in a statistical sense. Unlike statistical emulators, in which the model is tuned to the statistical structure of the observation, stochastic parametrization are not directly tuned to match the statistics of the observations. Rather, stochastic parameterization combines deterministic, i.e physics based models with stochastic models for the "missing physics" to create hybrid models, that are stochastic, but yet can be used for making predictions, especially in the context of data assimilation. We introduce a novel measure of the utility of stochastic models of complex processes, that we call consistency of sensitivity. A model with poor consistency of sensitivity requires a great deal of tuning of parameters and has a very narrow range of realistic parameters leading to outcomes consistent with a reasonable spectrum of physical outcomes. We apply this metric to our stochastic parametrization and show that, the loss of certainty inherent in model due to its stochastic nature is offset by the model's resulting consistency of sensitivity. In particular, the stochastic model still retains the forward sensitivity of the deterministic model and hence respects important structural/physical constraints, yet has a broader range of parameters capable of producing outcomes consistent with the field data used in evaluating the model. This leads to an expanded range of model applicability. We show, in the context of data assimilation, the stochastic parametrization of longshore currents achieves good results in capturing the statistics of observation that were not used in tuning the model.
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Lines, Emily. "Forest dynamics at regional scales : predictive models constrained with inventory data." Thesis, University of Cambridge, 2012. https://www.repository.cam.ac.uk/handle/1810/243636.
Повний текст джерелаАнотація:
Forest ecosystems store more carbon than the atmosphere and harbour the majority of the world's biodiversity, yet their response to changing climate is uncertain. Forest simulation models make landscape-level predictions of forest dynamics by scaling from key tree-level processes, but models typically have no climate dependency. In this thesis I demonstrate how large-scale national inventories combined with improvements in computational methods mean that models that incorporate the climate dependency of demographic processes may be parameterised at regional scales. In Chapter One I outline historical approaches to modelling forest dynamics and present a discussion of competing methods of parameterisation and model selection. In Chapter Two I present a model of individual tree mortality in the eastern United States which incorporates species, climatic and competitive effects parameterised using Markov Chain Monte Carlo methods. The remainder of the thesis concentrates on modelling Spanish forest dynamics, so in Chapter Three I present a brief introduction to Spanish forest ecology. In Chapter Four I examine how aboveground allometry - the scaling of tree height and crown shape - varies with climate and competition in Spain for 26 species. Hierarchical modelling suggests that scaling theories based on wood properties do not explain differences between species, but climatic factors, and in particular hydraulic limitations, do. In Chapter Five I parameterise a model of recruitment in Spanish forests using Approximate Bayesian Computation, a novel computational method which allows parameterisation of individual-based models without individual-based data, and demonstrate that it produces ecologically reasonable results. Chapter Six presents a forest dynamics model parameterised for the major native species in Spain and tests whether it is able to reproduce observed species-climate distributions. Finally, in Chapter Seven I discuss the main findings of the thesis and avenues for extending this research.
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Lindholm, Brian Eric. "Reconciliation of a Rayleigh-Ritz beam model with experimental data." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06102009-063201/.
Повний текст джерела
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Kjellin, Andreas. "Visualizing Dynamics –The Perception of Spatiotemporal Data in 2D and 3D." Doctoral thesis, Uppsala University, Department of Information Science, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-9142.
Повний текст джерелаАнотація:
In many command and control situations the understanding of dynamic events is crucial. With today’s development of hard- and software architecture, we have the possibility to visualize data in two-dimensional (2D) and three-dimensional (3D) images. The aim of this thesis is therefore to investigate different approaches to visualizing dynamic events. The visualization techniques investigated include 2D animation and time representations as markings on a 2D map. In 3D the visualization technique investigated is the “space time-cube” A further aim is to study whether the Cue Probability Learning (CPL) paradigm can be used to evaluate visualizations.
By mapping time onto a spatial dimension, in the 2D visualization as lines with different densities and in 3D as height over the map, a simultaneous visualization of space and time is possible. The findings are that this mapping of time onto space is beneficial to users as compared with animations, but the two mapping techniques are not interchangeable. If a task requires judgments of metric spatial properties, a 2D visualization is more beneficial; however, if the task only requires judgments of more qualitative aspects, a 3D visualization is more beneficial.
When we look at a 3D visualization, we utilize different sources of depth information. These sources are always present and each defines either a 3D scene or a projection surface. By using these different sources of depth information wisely, a visualization can be created that efficiently shows relevant information to a user while requiring a minimal amount of specialized hardware.
Finally, the CPL paradigm seems to be a worthwhile option as an experimental paradigm in visualization experiments. One of the advantages of CPL is that novice users can be trained to be task experts in a controlled and time-efficient way.
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Alava, Mónica Hernández. "Growth dynamics : an empirical investigation of output growth using international data." Thesis, University of Leicester, 2002. http://hdl.handle.net/2381/30140.
Повний текст джерелаАнотація:
The rates of growth of output per head vary across countries. Despite the fact that these differences are of a small order of magnitude, they would translate into large differences in the average living standards of the countries if they were to persist over the years. It is therefore very important to understand the process of long run growth and as a consequence many recent studies concentrate on the issue of cross country convergence. The aim of this thesis is to investigate the process of growth across countries and the possibility of inter-relationships of these processes across countries. To this avail, an empirical analysis of per capita output across countries out first using the exact continuous time version of two neoclassical growth models, the Solow growth model and The Ramsey-Cass-Koopmans model. Results show that when these models are estimated consistently countries do not seem to be converging in the sense typically used in the literature. The rest of the thesis aims to investigate in more detail the processes by which growth in different countries might be related. Based on extensions of another neoclassical model, the Overlapping Generations model, and using a nonlinear switching regime model for estimation, two empirical analyses are carried out. The first one examines the role of balance of payments constraints in cross country growth determination. The second studies the extent of technology spillovers across countries and their effect on the process of growth. On one hand, results reveal little evidence of current account deficits constraining growth in the long run in the G7 countries although there is ample evidence of an influence in the short run dynamics of growth. On the other hand, spillovers of technology across the G7 countries are found to be of importance in the process of growth.
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Malmberg, Mats. "Sensor Fusion of GPS andAccelerometer Data for Estimation of Vehicle Dynamics." Thesis, KTH, Optimeringslära och systemteori, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-143801.
Повний текст джерелаАнотація:
Connected vehicles is a growing market. There are currently several such services available, but many of them are constrained in the sense that they are bound to recently produced cars and either expensive or strongly limited in the services that they provide. In this master thesis we investigate the possibility to implement a generic platform that is of low cost and simple to install in any vehicle, but that still has the ability to provide a wide range of services. It is proposed that a crucial step in such a system is to reconstruct the vehicle’s kinematics, as this enables the possibility to developed a wide range of services by feature extraction and interpret the result from a dynamics perspective. A mathematical model that describes how the kinematics can be reconstructed is proposed, and a filter that performs such reconstruction is implemented. Based on this reconstruction, two filters that interpret the output are implemented as a proof of concept for the proposed mathematical model. The complete implemented filter solution is tested on measurement data from actual driving scenarios and it is seen that we can identify when the vehicle makes a hard turn, and find where the surrounding road conditions are poor.Uppkopplade fordon är en växande marknad. I dagsläget finns flera sådana tjänster, men ofta är dessa begränsade i den meningen att de antingen endast finns tillgängliga för nyproducerade fordon eller bara erbjuder ett smalt utbud av tjänster. I detta examensarbete undersöker vi möjligheten att utveckla en generisk plattform för uppkopplade fordon som är billig och enkel att installera, men som också kan erbjuda ett stort urval av tjänster. Det föreslås att ett viktigt steg i en sådan lösning är att rekonstruera fordonets kinematik, då detta möjliggör utvecklandet av ett brett urval av tjänster genom att identifiera karakteristiska egenskaper i kinematiken, samt göra tolkningar utifrån dynamikbetraktelser. En matematisk modell för att beskriva hur kinematiken kan rekonstrueras från givna indata presenteras, och ett filter som utför denna rekonstruktion implementeras. Ytterligare två filter implementeras för att påvisa att den rekonstruerade kinematiken samt den föreslagna matematiska modellen kan användas till att identifiera olika scenarion ur verkligheten. Den kompletta filterlösningen testas på mätdata från faktiska körningar och vi ser att vi kan identifiera när fordonet gör skarpa svängar, samt när vägförhållandena är dåliga.
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Germann, Wade Anthony. "Data integration to explore the dynamics of conflict a preliminary study." Thesis, Monterey, California. Naval Postgraduate School, 2008. http://hdl.handle.net/10945/3848.
Повний текст джерелаАнотація:
This thesis is an exploration of the concepts of data integration with respect to military operations. It is an attempt to establish practices that analysts and operators can use to integrate many types of data from disparate sources. The project focuses on two software platforms: Palantir Technologies and Google Earth. These specific programs are utilized because they provide off-the-shelf products that are easy to use, require little training, and are compatible with each other. Using these software packages, we attempt to integrate data with geospatial, temporal and relational data in order to gain greater understanding and insight into complex problems.
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Ratcliffe, Maxim Julian. "Identification and application of measured frequency domain data for structural dynamics." Thesis, University of Bristol, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389376.
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Lee, Hao-Chih. "Data-Driven Modeling of Morphological Dynamics and Intracellular Transport of Organelles." Research Showcase @ CMU, 2015. http://repository.cmu.edu/dissertations/647.
Повний текст джерелаАнотація:
Data-driven modeling is essential to understanding complex cellular processes. In this thesis, we present a series of studies of analyzing morphological dynamics and intracellular transport of organelles using techniques of mathematical modeling, image processing and machine learning. We first characterized the morphology of organelles, focusing specifically on mitochondria. We developed a morphological data processing pipeline. Using this pipeline, we discovered a bi-modal distribution of mitochondrial sizes, with a stable mean value in each mode. We then developed a data-driven model to investigate how fusion / fission of mitochondria modulates their sizes. For further analysis of morphology of mitochondria as well as other cellular components, we developed a general purpose machine learning algorithm, which we refer to as shape component analysis (SCA). We used it for dimension reduction and classification of mitochondrial morphology and protein geometry. In addition to studying the morphological dynamics of cellular organelles using data-driven modeling, we investigated the intracellular transport of organelles. We first proposed a probabilistic model for studying the relation between mitochondrial size and the velocity of their active transport. The proposed model not only explained the relation between mitochondrial size and velocity observed in experiments under normal conditions but also suggested a novel relation under changed conditions. Further analysis of the proposed model also suggested a way to evaluate the binding/unbinding rates of motors carrying the mitochondria. We further studied the global organization of organelle transport. We proposed an image processing framework to characterize the spatiotemporal dynamics of intracellular transport in terms of the spatial localization of stationary organelles and the spatiotemporal patterns of organelle movement, respectively. We used this framework to analyze time-lapse images of Lamp1 transport and found different global transport patterns. Overall, our studies produced both computational modeling methods and specific biological results for quantitative and systems-level understanding the complex behavior of intracellular organelles.
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Defforge, Cécile. "Data assimilation for micrometeorological applications with the fluid dynamics model Code_Saturne." Thesis, Paris Est, 2019. http://www.theses.fr/2019PESC1008.
Повний текст джерелаАнотація:
La qualité de l’air est un enjeu sanitaire et environnemental majeur. Par ailleurs, l'estimation précise des potentiels éoliens est la source d’importantes retombées économiques et environnementales. Pour étudier ces deux sujets, il est nécessaire de reconstituer précisément les champs de vent locaux grâce à des modèles numériques de micrométéorologie. Ces simulations sont extrêmement sensibles aux conditions météorologiques aux limites du domaine d’étude. Jusqu’à présent, les conditions aux limites (CL) étaient estimées à partir de simulations à plus grande échelle, qui fournissent des informations peu adaptées à l’utilisation à l'échelle locale car imprécises, voire incomplètes. Par conséquent, la méconnaissance des CL représente une source majeure d’erreur et d’incertitude dans les études micrométéorologiques.Les sites susceptibles d’accueillir un parc éolien et les environnements bâtis (quartiers urbains ou sites industriels) peuvent être équipés d’instruments de mesures météorologiques ou de concentration de polluants. Les observations qu’ils fournissent constituent une seconde source d’information, jusqu’à ce jour peu exploitée pour les études micrométéorologiques. En effet, les mesures in situ sont perturbées par la géométrie complexe des sites étudiés. Afin d'améliorer la précision des CL et donc des simulations atmosphériques à l'échelle locale, des méthodes d'assimilation de données (AD) adaptées à cette problématique pourraient permettre de mettre à profit les observations disponibles.Jusqu’à présent, les méthodes d’AD ont été principalement développées pour la météorologie à grande échelle et ont donc surtout été utilisées pour corriger les conditions initiales (CI). Afin d'élargir le champ d'application de l’AD à la micrométéorologie, il faut adapter les méthodes existantes pour qu'elles permettent de corriger les CL plutôt que les CI.Deux méthodes d’AD semblent compatibles avec les modèles de mécanique des fluides (CFD) utilisés pour la micrométéorologie en géométrie complexe : l’algorithme de nudging direct et rétrograde (BFN) et le lisseur de Kalman d’ensemble itératif (IEnKS). Nous avons adapté ces deux méthodes d’un point de vue théorique pour inclure les CL dans les variables de contrôle. Les performances des versions adaptées du BFN et de l'IEnKS ont tout d'abord été étudiées avec un modèle simplifié d’écoulement atmosphérique à deux couches en 1D, basé sur les équations de Saint-Venant. Le BFN et l’IEnKS ont ensuite été testés en 2D puis 3D avec le module atmosphérique du modèle open-source de CFD Code_Saturne.Le premier cas d’étude avec Code_Saturne correspond à une application réelle d’estimation de potentiel éolien dans une région montagneuse au relief très accidenté où trois mâts de mesure fournissent des observations de vent. Le second cas correspond à une étude de dispersion de polluants en milieu urbain, basé sur les mesures de vent et de concentration provenant de la campagne « Mock Urban Setting Test » aux États-Unis. Dans ce second cas, la turbulence est également incluse dans les CL. Dans les deux études, une partie des observations est utilisée pour l’assimilation et le reste pour la validation des résultats.Les expériences menées sur le premier cas ont révélé que les modèles de CFD présentent des non-linéarités trop fortes (recirculations derrière les obstacles) pour l’algorithme de BFN, fondé sur une hypothèse de linéarité. L'étude de cette méthode n'a donc pas été poursuivie. En revanche, les deux études ont montré la capacité de l'IEnKS à réduire l'erreur et l'incertitude sur les CL grâce à l'assimilation d'une petite dizaine d'observations, en un nombre raisonnable de calculs. Par suite, les champs de vent simulés sont également plus proches des observations de validation et les intervalles de confiance sont réduits. Finalement, l'IEnKS permet d'estimer le potentiel éolien, dans un cas, et les concentrations en polluant, dans l'autre, avec beaucoup plus de précision et d'exactitudeAir quality is a major health and environmental issue worldwide. Similarly, the accuracy of wind resource assessment triggers significant economic and environmental repercussions. In order to study these two topics, it is necessary to accurately determine local wind fields using numerical models of micrometeorology. Such simulations are extremely sensitive to meteorological conditions at the domain borders. Up to present, the boundary conditions (BC) were estimated based on the results of larger scale simulations, which provide information that is not accurate enough, or even incomplete, for local scale purposes. As a matter of fact, the lack of knowledge about the BC represents a major source of error and uncertainty for micrometeorological studies.The potential sites for wind farm installation as well as built environments (urban areas or industrial sites) can be equipped with instruments measuring meteorological variables or pollutant concentration. The observations provided by these instruments represent a second source of information, insufficiently exploited for micrometeorological studies. Indeed, the in situ measurements are perturbed by the complex geometrical features on sites and might be difficult to exploit. In order to improve the exactitude and the accuracy of the BC, and consequently of the locale-scale atmospheric simulations, data assimilation (DA) methods, suited to this micrometeorological problem, could be applied to take benefit from these available observations.So far, DA methods have been mainly developed for large-scale meteorology and employed to correct the initial conditions (IC). In order to broaden the application scope of DA to micrometeorology, existing DA methods must be adapted to be able to correct the BC instead of IC.Two of the existing DA methods seem compatible with computational fluid dynamics (CFD) models used for micrometeorology over complex geometries: the back and forth nudging (BFN) algorithm and the iterative ensemble Kalman smoother (IEnKS). We have adapted these two methods, from a theoretical perspective, so as to include the BC in the control variables. The performances of the adapted versions of the BFN algorithm and the IEnKS have first been assessed with a simplified, 1D model of atmospheric flow with two layers, based on the shallow-water equations. The BFN algorithm and the IEnKS have then been tested in 2D and 3D with the atmospheric module of the open-source CFD model Code_Saturne.The first study case with Code_Saturne corresponds to a real application of wind resource assessment in a mountainous region with steep topography where three meteorological masts have been installed during a few months and provide in situ wind observations. The second case is a study of pollutant dispersion in an urban area, based on the measurements of wind and pollutant concentration coming from the “Mock Urban Setting Test” field campaign carried out in the USA. In this second case, the turbulence is also included in the BC and thus in the control variables. For both studies, some observations are assimilated and the remaining ones are used to validate the results.The experiences performed for the wind resource assessment study have revealed that the CFD models present too strong nonlinearities (flow recirculation after obstacles) for the BFN algorithm, which is based on a linearity assumption. However, both cases have shown the ability of the IEnKS to reduce the error and the uncertainty of the BC by assimilating a few observations, in operationally affordable conditions. Consequently, the simulated wind fields with Code_Saturne are also closer to the validation observations and the confidence intervals are reduced. Eventually, the IEnKS allows, in one case to estimate the wind potential, and in the other case to build the pollution maps, with much more exactitude and accuracy
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Hartunian, Eric Germann Wade Anthony. "Data integration to explore the dynamics of conflict a preliminary study /." Monterey, Calif. : Naval Postgraduate School, 2008. http://edocs.nps.edu/npspubs/scholarly/theses/2008/Dec/08Dec%5FHartunian.pdf.
Повний текст джерелаАнотація:
Thesis (M.S. in Defense Analysis)--Naval Postgraduate School, December 2008.Thesis Advisor(s): Roberts, Nancy C. "December 2008." Description based on title screen as viewed on January 29, 2009. Includes bibliographical references (p. 77-81). Also available in print.