385 research outputs found
Large and detached eddy simulation of separated flow over 3D hill geometries with surface roughness to mimic flows over complex terrains
No full textWith the push to making wind power a significant contributor to the energy portfolio in the U.S. and Europe, there is considerable effort to deploy the currently available peta-scale computational resources to assess and improve well known simulation techniques, such as the large eddy simulation (LES) and detached eddy simulation (DES) techniques, to model the complex flows in wind farms, taken as a whole, as opposed to individual wind turbines. Simulating turbulent flows in wind farms, consisting of arrays of wind turbines, begins with the modeling and simulation of the atmospheric boundary layer (ABL) over complex terrain that is characterized by regions of separated flow with a high degree of turbulence anisotropy. Over the years there has been considerable work on applying LES and Reynolds Averaged Navier--Stokes (RANS) simulations over terrain geometries, such as the Askervein Hill, to understand turbulence closure models for flow over complex terrain. Such studies, however, have had limited success due to difficulties associated with the closure models in the near wall region of the flow. At the same time, turbulence simulations over \emph{canonical} geometries, such as the periodic and axisymmetric hills, have been shown to compare well with data obtained from laboratory scale experiments, where the inflow turbulence and boundary conditions are better characterized and defined respectively. In an effort to extend these canonical flows to be more representative of flows over complex terrain, this paper aims to present results of large and detached eddy simulations of separated flow over three dimensional hill geometries with roughness parametrization, with the objective of developing better closure models for flow over complex terrain
On defect CFT and path integral methods for entanglement in quantum field theories
No full textIn the first few chapters of the thesis, we will study defect CFT methods based on the replica trick for characterizing quantum information in quantum field theories. We calculate a coefficient that characterizes the strength of the two point function of the displacement operator in the replica twist defect placed in a holographic CFT, which controls the second order shape dependence of Renyi entropy. We introduce defect CFT methods for calculating correlation functions involving the modular Hamiltonian together with probe operators inserted at lightcone separation. We use these methods to further calculate correlation functions involving modular flows of these probe operators. Tomita-Takesaki theory constrains these correlation functions, which when combined with our defect CFT calculations, provides a proof of the Quantum Null Energy Condition.
In the last few chapters of this thesis, we will calculate entanglement measures for states that are defined by a Euclidean path integral together with a source for an operator inserted in the path integral. We provide a purely Lorentzian formula for the modular Hamiltonians for these states for flat entangling cuts which systematizes the task of writing time-ordered expressions for relative entropy of these states with respect to the vacuum to all orders in the source. We further apply this method to calculate a formula for shape deformed modular Hamiltonian for the vacuum state to all orders in the shape deformation. In the case of null shape deformation, we recover the formula for the vacuum modular Hamiltonian for null cuts. We then calculate the shape deformation of relative entropy and provide evidence for the presence of a shock in the stress tensor expectation value when one performs the Connes cocycle flow of the state.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2023-12-01The student, Srivatsan Balakrishnan, accepted the attached license on 2021-07-16 at 15:10.The student, Srivatsan Balakrishnan, submitted this Dissertation for approval on 2021-07-16 at 15:25.This Dissertation was approved for publication on 2021-07-19 at 10:22.DSpace SAF Submission Ingestion Package generated from Vireo submission #16990 on 2022-04-06 at 17:16:09Made available in DSpace on 2022-04-29T21:41:38Z (GMT). No. of bitstreams: 3
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Previous issue date: 2021-07-19Embargo set by: Seth Robbins for item 123298
Lift date: 2024-04-29T21:41:44Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 123298
Lift date: 2024-04-29T21:42:24Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 123298
Lift date: 2024-04-29T21:43:01Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 123298
Lift date: 2024-04-29T21:44:44Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 123298
Lift date: 2024-04-29T21:46:25Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 123298
Lift date: 2024-04-29T21:47:53Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemAuthor requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemU of I Onl
THE SINGAPORE WATER SUPPLY, 1819-1945 : THE EVOLUTION OF A GOVERNMENTAL RESPONSIBILITY
No full textBachelor'sBACHELOR OF ARTS (HONOURS
Maximizing Water--Food--Energy Nexus Synergies at Basin Scale
No full textIn this short paper, we show how solutions for mitigating resource security in one sector can be found in another. We demonstrate—by means of a case study in Burkina Faso and Ghana—how investing in the electricity grid in the south leads to increase food security in the north. A new nexus framework was developed (‘MAXUS’) which was built to understand, simulate and optimize intersectoral (and international) development strategies in the water, food and energy sectors. We believe this new type of geospatial integral resource management, supported by the exponential increase of data availability of the twenty-first century, could finally turn nexus models into decision support tools.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Water Resource
Thiamin diphosphate catalysis in Escherichia coli pyruvate dehydrogenase multi-enzyme complex: activation, covalent electrophilic catalysis, and substrate channeling
No full textSpectroscopic identification and characterization of covalent and non-covalent intermediates on large enzyme complexes is an exciting and challenging area of modern enzymology. While nuclear magnetic resonance (NMR) methods which provide detailed chemical insights have been successfully employed previously, limited examples are available in the literature for large enzyme complexes. Enzymes utilizing cofactors provide promising examples for such studies when synthetic routes to labeled cofactor analogs and protocols for reconstitution of apo-enzymes with such analogs are readily available. Syntheses of key isotope enriched thiamin diphosphate (ThDP) analogs – [C2, C6’ – 13C2] ThDP, [N4’ – 15N]ThDP and [C2 – 13C]ThDP – enabled first detection of (i) various ionization/tautomerization states of ThDP during the catalytic cycle of three ThDP dependent enzymes using cross polarization magic angle spinning (CPMAS) solid state NMR (SSNMR) spectroscopy and (ii) [C2, C6’ – 13C2] ThDP covalent intermediates on the E1 component (E1p) during the catalytic cycle of E. coli pyruvate dehydrogenase multi-enzyme complex (PDHc) by filter experiments including solution 1-D 1H-13C HSQC NMR. Direct evidence was gathered for the 4’-aminopyrimidinium form (APH+) on ThDP molecules bound to (i) S. cerevisiae yeast pyruvate decarboxylase (YPDC) (ii) E1p and (iii) the E1 component of E. coli 2-oxoglutarate dehydrogenase complex (E1o) using 13C and 15N CPMAS SSNMR. The thiazolium C2-H bond was found to be slightly acidic in the cofactor bound to these enzymes. 15N SSNMR experiments confirmed the formation of the 1’,4’-iminopyrimidine tautomer in presence of substrate analogs; a mechanism is proposed for the stabilization of this biologically rare tautomer in enzyme active-sites. Using rapid chemical quench in conjunction with solution NMR, pre-steady state analyses were performed on the native PDHc and PDH complexes reconstituted with E1p active-site loop variants of very low PDHc activity. The C2-α-lactylThDP intermediate could not be detected under any of the conditions used, indicating that its formation is slower than its decarboxylation. The enamine intermediate accumulates at a rate 110 s-1 on E1p and PDHc, while the rates are 100-fold slower for the PDHc variants. 2-acetylThDP could be detected on E1p only during its reaction with pyruvate and the artificial electron acceptor DCPIP. Reductive acetylation of the lipoyl domain in a pre-steady state single turn-over experiment (a model for the E1p-E2p reductive acetyl transfer reaction) was determined by mass spectrometry. Combined, these kinetic results from artificial oxidation reactions suggest the enamine is very well stabilized by E1p and oxidation of the enamine and substrate channeling to E2p are favored by intact PDHc. These studies provide unprecedented insight into the acid-base and covalent electrophilic roles of ThDP in enzyme catalysis and the methods described herein are applicable to all such complexes.Ph.D.Includes bibliographical referencesIncludes vitaby Anand Balakrishna
Classifiers of massive and structured data problems: algorithms and applications
No full textThe last two decades have seen the emergence of vast and unprecedented data repositories. Extraordinary opportunities now present themselves for new data analysis methods that can harness these repositories. As larger and larger amounts of widely varying types of data are constantly being collected and assimilated, the
task of making use of such data opens up interesting and challenging avenues of research.
This thesis deals with specific problems in data mining and machine learning in this setting. In particular we describe algorithms and applications for classification problems where
computational restrictions become limiting (resource bounded algorithms and online/streaming algorithms) as well as models and algorithms for certain problems where the structure of the input is leveraged to provide not only accurate, but also interpretable classifiers.Ph.D.Includes bibliographical references
Recurrence-based models for improving coverage within GPS and satellite-denied mobile sensor networks
No full textThis Thesis was approved for publication on 2021-04-28 at 11:15.DSpace SAF Submission Ingestion Package generated from Vireo submission #16540 on 2021-09-16 at 17:05:08Made available in DSpace on 2021-09-17T02:34:46Z (GMT). No. of bitstreams: 3
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Previous issue date: 2021-04-28Adversarial GPS-denial and coordinate spoofing, as well as satellite jamming, serve as common obstacles to disaster-recovery and military-based teams. While such teams are often supported by UAVs that connect multiple personnel by serving as relay devices, UAV position schemes that rely on centralized controllers are also disrupted by such hurdles, as GPS and satellite-based denial will effect the ability of UAVs to communicate with the controller and drones outside line of sight. In this thesis, we design and implement a drone-relay system that allows drones to cooperatively maximize coverage in a GPS-denied and satellite-denied scenario. Here, we define coverage as the ability of one entity to speak to another entity using a drone network as an intermediate relay system and is measured as the ratio of fulfilled entity-to-entity connections to all possible entity-to-entity connections. We maximize coverage over an extended experiment duration, consisting of 300–1000 timesteps, by devising algorithms that rely on a centralized controller with full knowledge of drone and ground entity position. Particle Swarm Optimization (85% coverage), Reinforcement Learning on a Recurrent Neural Network (75% coverage), and a Time-Series based Inference Optimizer (71% coverage) were amongst the best performing movement algorithms, improving upon movement models in related works by up to 40%. We then design a distributed backend that disperses commands from a centralized controller using a distributed drone-to-drone communication scheme, also collecting observations made by each drone and relaying them to the centralized controller. This backend is additionally integrated with failure recovery and security-based protocols to ensure recovery in drone-downtime and drone-compromised scenarios; both systems feature minimal overhead, allowing drone recovery from downtime in 7% of the simulated episode length and featuring a constant time-addition from encryption that does not increase as drone count increases. Finally, we remove all notions of centrality by designing and implementing a fully decentralized system, where drones operate in squads and house their own models and decision-making protocols. In this system, drone squads are able to share observations of their surroundings with neighboring drone squads to improve predictive performance. This final system complies with GPS and satellite-denial limitations as drones only perform observations in a surrounding vision radius, assuming a camera to be mounted on each drone, and drones can only send messages to neighbors in a transmission radius, avoiding the need of sending satellite-based messages.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2023-05-01The student, Rahul Balakrishnan, accepted the attached license on 2021-04-23 at 19:58.The student, Rahul Balakrishnan, submitted this Thesis for approval on 2021-04-23 at 20:11.Embargo set by: Seth Robbins for item 118580
Lift date: 2023-09-17T02:34:57Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemAuthor requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemU of I Onl
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