1,479 research outputs found
An efficient and accurate timing macro-modeling algorithm for large hierarchical designs
No full textEver-increasing circuit design complexity is driving the need for fast and accurate macro-modeling algorithms to accelerate hierarchical timing. We introduce LibAbs, an effective macro-modeling algorithm that efficiently supports high accuracy, high compression rate, and multi-threading. LibAbs applies tree-based graph reduction techniques to reduce the model size with accuracy values comparable to those of the flat model under a multi-threaded environment. LibAbs outperforms existing tools including the top winners from the TAU 2016 macro-modeling contest in terms of model size, accuracy, and runtime on industry benchmarks. The in-context usage of our abstracted model has also demonstrated promising performance for timing-driven optimizations in large hierarchical designs.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2019-08-01The student, Tin-Yin Lai, accepted the attached license on 2017-06-16 at 00:00.The student, Tin-Yin Lai, submitted this Thesis for approval on 2017-06-16 at 16:06.This Thesis was approved for publication on 2017-06-19 at 16:34.DSpace SAF Submission Ingestion Package generated from Vireo submission #11229 on 2017-09-29 at 11:13:45Made available in DSpace on 2017-09-29T16:39:10Z (GMT). No. of bitstreams: 2
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Previous issue date: 2017-06-19Embargo set by: Colleen Fallaw for item 103383
Lift date: 2019-09-29T16:39:52Z
Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemEmbargo set by: Colleen Fallaw for item 103383
Lift date: 2019-09-29T17:52:45Z
Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemLimited Restriction Lifted for Item 103383 on 2019-09-30T09:15:29Z
Access to Pyrrolidine Imino Sugars via Tin(II)-Mediated Aldol Reactions of Bislactim Ethers: Synthesis of 2,5-Dideoxy-2,5-Imino-D-Glucitol
No full textAuthor accepted manuscript[Abstract] 2,5-Dideoxy-2,5-imino-D-glucitol (DGDP) has been synthesized via the tin(II)-mediated anti-selective aldol reaction of bislactim ether 5 and a 3-O-silylated 2,4-ethylidene-D-erythrose derivative 6. In accordance with density functional theory calculations (at the B3LYP/cc-pVDZ-PP level), pericyclic transition structures with a boat-like conformation and a stabilizing hydrogen bond can account for the unexpected stereoselectivity.We gratefully acknowledge Ministerio de Ciencia y Tecnología (BQU2003-00692) and Xunta de Galicia (PGIDIT05BTF10301PR) for financial support. The authors are indebted to Centro de Supercomputación de Galicia for providing computer facilities. O. B. thanks Xunta de Galicia for an “Isidro Parga Pondal” position at Universidade da CoruñaXunta de Galicia; PGIDIT05BTF10301P
A Review of Larry Hamberlin\u27s Tin Pan Opera: Operatic Novelty Songs in the Ragtime Era
No full textIn Tin Pan Opera author Larry Hamberlin explores the influence of opera on American popular musical culture in the early twentieth century and its importance in American culture at the time. The author discusses the power dynamic present between America and Europe, and how the use of opera in American popular culture portrays this dynamic. Through evidence found in popular song, Hamberlin tracks the changing position of opera in American society, consequently also tracking the changing cultural and social dynamics of a nation.
Low cost patterning of thin film
No full textA novel route for the low-cost patterning of electrical thin films has been established. The process has been developed principally for the manufacture of thermocouples using high-speed reel-to-reel industrial techniques, but could be applied to the manufacture of a wide range of electronic devices including radio frequency identification (RFID) antennae, electrical interconnect, and passive electronic components.
The procedure exploits high-volume processes directly to print self-removing masking layers. The process offers substantial advantages over traditional thin-film patterning methods including faster, cheaper production runs. Raw material use and wastage are greatly reduced, affording environmental benefits
Dual-action self-healing protective coatings with photothermal responsive corrosion inhibitor nanocontainers
No full textThis work introduces a novel nanocomposite coating with dual-action self-healing corrosion protection activated by the photothermal response of plasmonic titanium nitride nanoparticles (TiN NPs). TiN@mesoporous SiO2 core–shell nanocontainers were developed as reservoirs for benzotriazole (BTA) corrosion inhibitors and incorporated into the shape memory epoxy coating matrix. Under near-infrared (NIR) light irradiation, the thermogenesis effect of TiN could not only promote the release of corrosion inhibitors from nanocontainers into the crevice, but also trigger the shape memory effect of damaged epoxy to merge the coating scratch. As such, the dual-action self-healing mechanisms combining the formation of an inhibitor-based protective layer and the scratch closure efficiently suppressed the corrosion process at the exposed metal surface. Surface characterization and electrochemical measurement results proved that the nanocomposite coating incorporated with 2 wt% of TiN-BTA@SiO2 exhibited the optimal corrosion protection as well as an excellent self-healing performance that can be initiated within 30 s of NIR illumination. This photo-controlled self-healing approach is potentially useful in designing next-generation self-healing coatings with ultrafast response time and high healing efficiency.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.Team Arjan Mo
Evolution of single particle strengths in tin isotopes and impacts on neutron capture
No full textAtomic nuclei with a few nucleons beyond shell closures are important in understanding the evolution of single-particle structure, which is critical to the benchmarking of nuclear models. With radioactive ion beams, studies near the double closed shell nucleus 132Sn have been made possible. While the single-neutron states in 133Sn with N = 83 and 131Sn with N = 81 have recently been verified to be highly pure, it is important to study further from the N = 82 neutron shell closure. Level energies and spectroscopic information for neutron-rich nuclei also provide important input for the rapid neutron capture r-process nucleosynthesis calculations. Specifically, it is important to know the location and strength of single-neutron states with orbital angular momentum l= 1 when calculating neutron-capture rates. Surman and collaborators have performed sensitivity studies to show that varying neutron-capture rates can significantly alter final r-process abundances. However, there are many nuclei important to the r-process that cannot be studied. Extending studies to more neutron-rich nuclei will help constrain the nuclear shell model in extrapolating to nuclei even further from stability. The (d, p) neutron transfer reaction has been measured in inverse kinematics with radioactive ion beams of 126Sn and 128Sn and a stable beam of 124Sn, all in inverse-kinematics at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory, utilizing the SuperORRUBA (Oak Ridge Rutgers University Barrel Array) of silicon detectors. The present work is combined with previous studies to complete the set of (d, p) studies on even mass tin isotopes from doubly-magic 132Sn to stable 124Sn and the systematics of l = 1 and l = 3 strengths. The results of the (d, p) study are used to map the fragmentation of single-neutron strengths in N ≤ 82 tin isotopes and to calculate the direct-semidirect neutron capture on these even mass tin isotopes that are important for the astrophysical r-process.Ph.D.Includes bibliographical referencesby Brett Montgomery Mannin
Model and Measurements of an Optical Stack for Broadband Visible to Near-Infrared Absorption in TiN MKIDs
No full textTypical materials for optical Microwave Kinetic Inductance Detetectors (MKIDs) are metals with a natural absorption of ∼ 30–50% in the visible and near-infrared. To reach high absorption efficiencies (90–100%) the KID must be embedded in an optical stack. We show an optical stack design for a 60 nm TiN film. The optical stack is modeled as sections of transmission lines, where the parameters for each section are related to the optical properties of each layer. We derive the complex permittivity of the TiN film from a spectral ellipsometry measurement. The designed optical stack is optimised for broadband absorption and consists of, from top (illumination side) to bottom: 85 nm SiO2, 60 nm TiN, 23 nm of SiO2, and a 100 nm thick Al mirror. We show the modeled absorption and reflection of this stack, which has >80% absorption from 400 to 1550 nm and near-unity absorption for 500–800 nm. We measure transmission and reflection of this stack with a commercial spectrophotometer. The results are in good agreement with the model.Tera-Hertz SensingEKL Equipmen
Measuring the viscous flow behaviour of molten metals under shear
No full textThis thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.The flow behaviour of liquid metals (Sn, Pb and Sn-Pb eutectic) under different shearing conditions is investigated. Experiments were performed with two designs of concentric cylinder viscometers: rotating the inner cylinder (Searle) and rotating the outer cylinder (Couette). The latter technique is uncommon and the equipment was optimised with standard oils. The flow behaviour for the metals differs in the two systems. The curves of “apparent” viscosity versus shear rate may be divided into two regimes: I. At lower shear rates (<200 s-1): a reduction of “apparent” viscosity with shear was observed with both viscometers. It is suggested that the high density and high surface tension of the metals and eccentricity between the cylinders at low shear rates, leads to instabilities. Results at low shear rates were therefore discarded and further detailed analysis would be required for a fuller understanding of this behaviour. II. At higher shear rates: a steady, shear-independent behaviour of “apparent” viscosity with shear rate is observed in the Couette system (upto 600 s-1) whereas in the Searle system the “apparent” viscosity increases with shear rate (upto 2600 s-1). From hydrodynamic theory about Newtonian fluids, it is suggested that in the Searle type viscometer, the fluid is unstable and Taylor vortices are expected at low shear rates (~80 s-1). This gives rise to an increase in the “apparent” viscosity with shear rate. Whereas, in the Couette type, the flow is more stable, resulting in a steady “apparent” viscosity. This interpretation is consistent with liquid metals behaving as Newtonian fluids, but further research is required to confirm this. The author suggests further experiments, with the prime one being the investigation of the fluid with counter and co-rotation of the cylinders in order to observe more complex flows. The results are expected to have implications in the modelling of flow for liquid metal processes, especially the initiation of Taylor vortices under the unstable flow conditions produced by rotating the inner cylinder
Safe and Adaptive 3-D Locomotion via Constrained Task-Space Imitation Learning
No full textBipedal locomotion has been widely studied in recent years, where passive safety (i.e., a biped rapidly brakes without falling) is deemed to be a pivotal problem. To realize safe 3-D walking, existing works resort to nonlinear optimization techniques based on simplified dynamics models, requiring hand-tuned reference trajectories. In this article, we propose to integrate safety constraints into constrained task-space imitation learning, endowing a humanoid robot with adaptive walking capability. Specifically, unlike previous work using nonlinear and coupled capturability dynamics, we first linearize the 3-D capture conditions using appropriate extreme values and then seamlessly incorporate them into constrained imitation learning. Furthermore, we propose novel heuristic rules to define control points, enabling adaptive locomotion learning. The resulting framework allows robots to learn locomotion skills from a few demonstrations efficiently and apply the learned skills to unseen 3-D scenarios while satisfying the constraints for passive safety. Unlike deep enforcement learning, our framework avoids the need of a large number of iterations or sim-to-real transfer. By virtue of the task-space adaptability, the proposed imitation learning framework can reuse collected demonstrations in a new robot platform. We validate our method by hardware experiments on Walker2 robot and simulations on COMAN robot
Informal gold mining and mercury pollution in Brazil
No full textThe Amazon region has been responsible for a major share of Brazilian gold production in recent years. The region has witnessed a sizable gold rush comparable only to the California gold rush last century. The gold rush has spawned a powerful informal mining sector and has attracted many people - some who have come to the region in search of wealth and some who were already there but were displaced from other, unsuccessful economicactivities. What these people encounter at the mining sites are dreadful living and working conditions. Gold mining also causes substantial environmental problems, which may persist whether gold deposits do or not. The author discusses the environmental effects of gold mining in the region, focusing on mercury pollution. Mercury, an important input in gold extraction, is being discharged into the atmosphere and the rivers at alarming rates. The environmental costs of the present extraction, is being discharged into the atmosphere and the rivers at alarming rates. The environmental costs of the present extraction technology will be faced primarily by future generations, because of natural chemical processes. Although removing the mercury already discharged from the Amazonian environment may be an enormous task, at least future discharges should be curtailed through the use of appropriate technology, environmental education, and a combination of command and control measures and market-based incentives. The author describes the gold extraction process and the extent of mercury use and contamination. He analyzes key elements of the environmental problem, especially the informal miner and the fish economy. Finally, he suggests a combination of command and control regulations and market-based incentives adapted to the informal gold mining economic environment. He emphasizes the need for an education campaign about the perils of using mercury and the availability of more appropriate, and inexpensive, alternative extraction technologies.Mining&Extractive Industry (Non-Energy),Montreal Protocol,Water and Industry,Coastal and Marine Resources,Primary Metals
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