964 research outputs found
Utilizing Steelmaking By-Products for Pavement Deicing: A Sustainable Waste Management Approach in Circular Economy
No full textSegmentation of lungs from volumetric CT-scan images using prior knowledge (shape and texture)
No full textThis thesis presents a hierarchical segmentation scheme for The segmentation of lungs from volumetric CT images that concerns variational segmentation methods, namely geodesic active surfaces (GAS) and active surfaces without edges (ASWE), a volumetric similarity registration technique, statistical shape modelling using principal component analysis (PCA), and volumetric texture modelling. GAS and ASWE are 3-D extensions of their 2-D version, geodesic active contours (GAC) and active contours without edges (ACWE). The two models are generalized into a unified framework, referred to as integrated active contours (IAS). Numerical implementation methods are derived for 3-D and the experiments are conducted both in 2-D and 3-D on synthetic and CT images. Global and local properties of active contours/surfaces under different parameter settings are presented and several applications of these models are proposed based on experimental results.The similarity registration technique aims tom find an optimal match between shapes with respect to rotation, scale and translation parameters. In this registration method, PCA is initially employed to calculate the principal axes of shapes. These principal axes are used to obtain a coarse match between shapes to be registered. Then geometric moments are exploited to estimate the isotropic scale parameter. The rotation and translation parameters are estimated by phase correlation techniques which take advantage of the fast Fourier transform (FFT). Experimental results demonstrate that the proposed technique, compared with the standard iterative gradient descent method, is fast, robust in the presence of severe noise, and suitable in registering various types of topologically complex volumetric shapes.Shape decomposition using PCA is the current state of the art and is widely drawn on in building deformable shape templates. The major problem to be solved in the modelling is to find proper PCA shape parameters that best approximate a novel shape of the same class. A comparison of popular methods for parameter estimation in the literature is presented and a hybrid coarse-to-fine method based on previous works is proposed.The method achieves satisfactory accuracy over previous works and is validated by a database of lung shapes.A hierarchical shape-based segmentation method that incorporates GAS, ASWE, similarity registration, and statistical shape modelling is proposed to extract lungs from volumetric low-dose CT images. The method is extensively experimented with a large variety of images including synthetic images with noise and occlusions, low-dose CT images with artificial noise and synthetic tumors, and a low-dose CT database. The results indicate that the method is robust against noise and occlusions.Last but not least, a novel volumetric texture modelling technique based on isotropic Gaussian Markov random field (IGMRF) is developed and applied to low-dose CT images of lungs. Based on the proposed texture modelling, a hard classification approach is suggested to provide proper initializations for the shape-based segmentation method and enables the segmentation to achieve a higher degree of automation. The method is evaluated by low-dose CT images with synthetic tumors and the low-dose CT database. The experimental results suggest its suitability for offering proper initializations for shape-based segmentation
High resolution millimeter wave imaging for self-driving cars
No full textRecent years have witnessed much interest in expanding the use of networking signals beyond communication to sensing, localization, robotics, and autonomous systems. This thesis explores how we can leverage recent advances in 5G millimeter wave (mmWave) technology for imaging in self-driving cars. Specifically, the use of mmWave in 5G has led to the creation of compact phased arrays with hundreds of antenna elements that can be electronically steered. Such phased arrays can expand the use of mmWave beyond vehicular communications and simple ranging sensors to a full-fledged imaging system that enables self-driving cars to see through fog, smog, snow, etc.
Unfortunately, using mmWave signals for imaging in self-driving cars is challenging due to the very low resolution, the presence of fake artifacts resulting from multipath reflections and the absence of portions of the car due to specularity. This thesis presents HawkEye, a system that can enable high resolution mmWave imaging in self-driving cars. HawkEye addresses the above challenges by leveraging recent advances in deep learning known as Generative Adversarial Networks (GANs). HawkEye introduces a GAN architecture that is customized to mmWave imaging and builds a system that can significantly enhance the quality of mmWave images for self-driving cars.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2021-12-01The student, Junfeng Guan, accepted the attached license on 2019-12-09 at 12:07.The student, Junfeng Guan, submitted this Thesis for approval on 2019-12-09 at 12:16.This Thesis was approved for publication on 2019-12-09 at 15:49.DSpace SAF Submission Ingestion Package generated from Vireo submission #14758 on 2020-02-28 at 17:23:56Made available in DSpace on 2020-03-02T22:15:15Z (GMT). No. of bitstreams: 2
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Previous issue date: 2019-12-09Embargo set by: Seth Robbins for item 113927
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Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemU of I Only Restriction Lifted for Item 113927 on 2022-03-03T10:15:19Z
Single-chain nanoparticle based catalysts
No full textEnzymes achieve their excellent catalytic properties by surrounding the catalytic sites with a polypeptide scaffold. The three-dimensional structure of the peptide chains creates a local environment that supramolecularly binds substrates to facilitate the catalysis. In this dissertation, synthetic polymers are used to serve a similar role, binding substrates and creating an optimal environment for performing efficient catalysis. Several single-chain nanoparticle (SCNP) catalysts have been developed to perform copper(I)-mediated alkyne–azide cycloaddition (CuAAC), “click” reactions, or the photoreduction of azido groups to amines. The nanoparticles are shown to have significantly higher activity when compared to analogous small molecule catalysts. Structure-activity relationships and reaction mechanisms are studied with SCNPs of different structures. The polymeric scaffolds are found to bind substrates in an enzyme-like manner. The catalysts operate in two modes: an “uptake mode” where small molecule substrates bind inside the polymer pockets and an “attach mode” that involves surface binding of protein substrates. The versatility and high efficiency of the nanoparticles lead to applications in protein and cell surface modification. In addition, another SCNP was shown to co-deliver an exogenous enzyme inside cells. The enzyme and SCNP reside and stay active in the endosomes, in essence engineering the endosome into an artificial organelle. The SCNP-enzyme complex can perform both concurrent and tandem reactions performing organic synthesis intracellularly. The combination of SCNP and enzymatic catalysts provides a versatile tool for intracellular organic synthesis with applications in chemical biology.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2022-05-01The student, Junfeng Chen, accepted the attached license on 2020-04-21 at 15:27.The student, Junfeng Chen, submitted this Dissertation for approval on 2020-04-21 at 15:53.This Dissertation was approved for publication on 2020-04-23 at 10:51.DSpace SAF Submission Ingestion Package generated from Vireo submission #15024 on 2020-08-25 at 17:27:49Made available in DSpace on 2020-08-26T23:54:35Z (GMT). No. of bitstreams: 2
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Sedimentary architecture and evolution of a Quaternary sand-rich submarine fan in the South China Sea
No full textInvestigating the sedimentary architecture and evolution of sand-rich submarine fans is vital for comprehending deep-water sedimentary processes and enhancing the success rate of hydrocarbon resource exploration. Recent drilling activities in the Qiongdongnan Basin, northern South China Sea, have unveiled significant gas hydrate and shallow gas potential. However, exploration in this area faces substantial challenges due to the limited understanding of sandy reservoirs. Leveraging extensive newly acquired extensive 3D seismic data (~9000 km2) and well data, our study reveals five distinct deep-water depositional systems in the Quaternary Ledong Formation, including a submarine fan system, mass transport deposits, deepwater channel-levee systems, slope fans, and hemipelagic sediments. Notably, the targeted sand-rich submarine fan lies within the abyssal plain, situated at a water depth of 1300-1700 m. This fan exhibits a unique tongue-shape configuration and a SW-NE flow direction within the plane and spans an expansive area of ~2800 km2 with maximum length and width reaching 140 km and 35 km, respectively. Vertically, the fan comprises five stages of distributary channel-lobe complexes, progressing from Unit 1 to Unit 5. Their distribution ranges steadily increase from Unit 1 to Unit 3, followed by a rapid decrease from Unit 4 to Unit 5. Our results suggest that the occurrence and evolution of the submarine fan are primarily controlled by sea level fluctuation, confined geomorphology, and sediment supply. Specifically, sea level fluctuation and sediment supply influenced the occurrence of the submarine fan. Concurrently, the confined geomorphology in the abyssal plain provided accumulation space for sediments and shaped the fan into its distinct tongue-like form. In contrast to the deepwater channels within the deepwater channel-levee systems, the distributary turbidite channels within the submarine fan are marked by lower erosion depth with “U” shapes, greater channel width, and higher ratios of width to depth. The comparative analysis identifies turbidite channels as the focal points for offshore gas hydrate and shallow gas exploration in the Qiongdongnan Basin. Furthermore, the temporal evolution of submarine fan offers valuable insights into Quaternary deep-water sedimentary processes and hydrocarbon exploration within shallow strata of marginal ocean basins
Cross fan-shaped roof-cutting blasting technology for preventing rockbursts in gob-side mining roadways
No full textThis study investigated the frequent occurrence of rockbursts in the advanced support areas of gob-side mining roadways. Taking a mine with severe rockburst occurrences as an example, based on an in-depth analysis of the occurrence patterns of 41 rockburst events, an engineering mechanics model of the interaction between the overlying roof of bocal goaf and the lateral goaf was developed. The triggering mechanism was revealed and cross fan-shaped roof-cutting blasting technology for preventing rockburst was proposed. The results showed that lateral support pressure in the gob-side roadways, support pressure in the lateral goaf area, advanced support pressure in the working face, and roadway intersections all have a significant impact on the occurrence of rockbursts. The probability of rockbursts increased with the number of interacting factors, with the combined effect of the overlying thick and hard roof in both the local and the lateral primary goaf as the primary controlling factor. The interaction between these areas formed a right-angle fan-shaped hanging roof structure. The large hanging roof provided static load, which triggered rockbursts, and dynamic load when ultimate collapse occurred, thus acting as the load source for the occurrence of rockbursts. The area influenced by advanced support pressure in the gob-side roadway was identified as the highest-risk zone for rockbursts. Implementing cross fan-shaped roof-cutting blasting technology in this zone effectively shortened the length of the right-angle fan-shaped hanging roof connecting the lateral goaf and the local goaf, thereby reducing the intensity of the dynamic load source. This study provides a novel approach and methodology for preventing and controlling the frequent occurrence of rockbursts during gob-side roadway mining
Improvement of the SiOx Passivation Layer for High-Efficiency Si/PEDOT:PSS Heterojunction Solar Cells
No full textInterfacial properties currently hinder the performance of Si/organic heterojunction solar cells for an alternative to high-efficiency and low-cost photovoltaics. Here, we present a simple and repeatable wet oxidation method for developing the surface passivation layer, SiOx, on the Si surface for the fabrication of high-efficiency Si/poly(3,4-ethylene-dioxythiophene):polystyrenesulfonate (PEDOT:PSS) heterojunction solar cells. The uniform and dense SiOx thin layer introduced by the oxidizing aqueous solution of H2O2 or HNO3 provided the better surface passivation and stronger wettability of the Si surface, compared to those in the native oxide case. These two types of progress helped create a lower defect density at the Si/PEDOT:PSS interface and thus a high-quality p-n junction with a lower interface recombination velocity. As a result, the HNO3-oxidized device displayed better performance with a power conversion efficiency (PCE) of 11%, representing a 28.96% enhancement from the PCE of 8.53% in the native oxide case. The effects on the performance of the Si/PEDOT:PSS hybrid solar cells of the wet oxidation treatment procedure, including the differences in surface roughness and wettability of the Si substrate, the quality and thickness of the SiOx, etc., were explored extensively. Such a simple and controllable oxidizing treatment could be an effective way to promote the interfacial properties that are an important cornerstone for more efficient Si/organic hybrid solar cells
Small-scale farms in the western Brazilian Amazon: can they benefit from carbon trade?
No full textRecently scientists have started to examine how land-uses and land-use technologies can help mitigate carbon emissions. The half million small-scale farmers inhabiting the Amazon frontier sequester large stocks of carbon in their forests and other land uses that they might be persuaded to maintain or even increase through the Clean Development Mechanism (CDM) of the Kyoto Protocol. On average, small-scale farmers in the Pedro Peixoto settlement project of Acre (Western Brazilian Amazon), had a stock of 10,067 tons of above- and below-ground carbon on their farms in 1994, 88 percent of which was stored in their forest reserves. The income and carbon mitigation effects of three types of carbon payments are analyzed in this paper: (1) above- or total-carbon stock payments paid for carbon retained in the forest or stored in all land-uses, (2) above- or total-carbon flow payments paid for carbon stored in all land-uses, and (3) above- or total-carbon net stock payments paid for carbon stored in all land-uses. The main conclusions are that carbon payments can be effective in preserving forest and carbon, but should be based on carbon stocks or net carbon stock rather than carbon flows. Payments tied to forest carbon or carbon in all land-uses provide inexpensive carbon offset potential, and payments based on total instead of above-ground carbon only slightly dilute the forest preservation effect of carbon payments. One-time carbon payments as low as R$15/t of carbon stock would preserve half of the existing forest carbon on these farms. Carbon flow payments, on the other hand, do not provide an adequate economic incentive to slow deforestation because forests are more or less in equilibrium and thus do not sequester additional carbon. If the Kyoto Protocol were amended to allow for conservation of forest carbon, a few potential CDMs could provide inexpensive carbon offsets, alleviate poverty, and preserve biodiversity. Sustainable forest management, for instance, increases both farm income and carbon and forest preservation and could provide inexpensive carbon offsets. Other projects could also provide inexpensive carbon offsets and preserve biodiversity, but would require additional income and technology transfers to compensate farmers for their lost incomes.Land use., Brazil Economic policy.,
Efficient Arithmetic for Embedded Cryptography and Cryptanalysis
No full textPublic Key Cryptography (PKC) is a critical component of todays information infrastructure. The use of PKC covers a wide spectrum of devices ranging from web servers to mobile handsets, from contact smart cards to passive RFID tags. Therefore, PKC implementations tailored to different environments need specific optimizations to meet the requirements for performance, power and security against physical attacks.This thesis focuses on arithmetic and architecture design for PKC. In thefirst part, we analyze the computation structures of RSA, Elliptic CurveCryptography (ECC), Hyperelliptic Curve Cryptography (HECC), Torus-based cryptography and Pairings, and explore various representations, algorithms and architectures for different design targets. In particular, we propose a multi-core Montgomery multiplier, a low-complexity modular multiplication algorithm for pairings, and two novel architectures for low-area implementations of HECC.In the second part, we use efficient arithmetic as the basis for hardware-based cryptanalysis. The security margin of a cryptosystem erodes continuously due to Moores law. We study the power of FPGA clusters to break ECC using the parallelized Pollard rho method and implement this attack on an FPGA where we try to maximize the number of Pollard rho iterations per second. We also give an estimation of the effort to break ECC2-131 and ECC2k-160 with state-of-the-art FPGAs.In the third and final part, we provide a systematic overview of implementation attacks and countermeasures for ECC. By monitoring the timing, power consumption, electromagnetic emission of the device or by inserting faults, adversaries can gain information about internal data or operations and extract the secret key without mathematically breaking the primitives. We provide implementers of ECC with ready-to-use recommendations of which combinations of countermeasures result in a secure implementation.status: Publishe
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