86 research outputs found
Inferring object states and articulation modes from egocentric videos
No full textWe develop algorithms for understanding objects from the point of view of interacting with them. There are two key aspects to obtaining such an understanding. First, objects can occur in different states and we need features that are sensitive to such states. Second, different objects can be articulated in different ways and we need to understand how to correctly infer their modes of articulation. We propose self and weakly supervised techniques to obtain such an understanding of objects purely through observation of how humans interact with the world around them through their hands. Our experiments on the challenging EPIC- KITCHENS dataset show the merits of using human hands as a probe for understanding objects.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2023-05-01The student, Rishabh Goyal, accepted the attached license on 2021-04-27 at 12:26.The student, Rishabh Goyal, submitted this Thesis for approval on 2021-04-27 at 13:39.This Thesis was approved for publication on 2021-04-28 at 09:43.DSpace SAF Submission Ingestion Package generated from Vireo submission #16585 on 2021-09-16 at 17:06:08Made available in DSpace on 2021-09-17T02:34:49Z (GMT). No. of bitstreams: 2
GOYAL-THESIS-2021.pdf: 26378428 bytes, checksum: 5fb34e7c3f1a83a84f3c5ba07fefd80f (MD5)
LICENSE.txt: 4210 bytes, checksum: 37522f5c1ac72c7fb0aa7fa78a307c50 (MD5)
Previous issue date: 2021-04-28Embargo set by: Seth Robbins for item 118591
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
Empirically understanding the global impact of migration to DNS-over-HTTPS
No full textIt has long been established that using DNS-over-UDP poses multiple threats to security and privacy ranging from Man-in-the-Middle-attacks to your ISP keeping a track of what websites you are visiting. To overcome this the industry actors and researchers have come up with DNS-over-Encryption which leverages already established encrypted protocols for DNS. While there have been a number of studies that measure the performance of these new protocols, most of these measurements have been done from developed countries and from university networks with robust Internet infrastructure. We still lack a global overview of how these encrypted DNS protocols perform all around the world and what are the factors which affect their performance other than the size of the network packet. This paper aims at answering these important questions while at the same time reasoning about the DNS-over-HTTPS measurements obtained. We compare the performance of DNS-over-HTTPS with the performance of legacy DNS for countries around the world to understand how the migration to DNS-over-HTTPS affects different countries and if all countries are equally affected.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2023-05-01The student, Rishabh Chhabra, accepted the attached license on 2021-04-21 at 16:15.The student, Rishabh Chhabra, submitted this Thesis for approval on 2021-04-21 at 16:21.This Thesis was approved for publication on 2021-04-27 at 15:31.DSpace SAF Submission Ingestion Package generated from Vireo submission #16478 on 2021-09-16 at 17:04:28Made available in DSpace on 2021-09-17T02:34:42Z (GMT). No. of bitstreams: 2
CHHABRA-THESIS-2021.pdf: 5298598 bytes, checksum: 4c61731c2a6f45c1b616f28c8c0a8ad8 (MD5)
LICENSE.txt: 4212 bytes, checksum: e7f67e30e1a964a13708c065295b64b1 (MD5)
Previous issue date: 2021-04-27Embargo set by: Seth Robbins for item 118562
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
Porous electrodes with directionally aligned macro pores for higher energy density Li ion batteries
No full textHygroscopic growth and cloud condensation nuclei activity of fresh and chemically-aged biomass-pyrolyzed organic aerosol
No full textBiomass burning is one of the prominent contributors of organic aerosols and cloud condensation nuclei (CCN) in the atmosphere. Aerosol-cloud interactions contribute to uncertainties in estimates of climate forcing, not only because of the complexities in their initial size and chemical composition, but also because of transformations (aging) they undergo in the atmosphere upon exposure to reactive species (e.g., NH3 and O3). This study presents results of bench-scale experiments on biomass pyrolysis organic carbon (OC) particles to determine its hygroscopic growth at sub-saturated relative humidities (RH) as well as CCN activity and droplet sizes at super-saturated humidity. This thesis investigates changes in these properties upon controlled, atmospherically-relevant exposures of NH3, O3 and RH. Measurements of hygroscopic growth and CCN activity are analyzed using κ-Köhler theory to calculate representative hygroscopicity parameters, κGF and κCCN, respectively (c.f. Petters and Kreidenweis 2007). Discrepancies as large as factors of three between κGF and κCCN suggest that approximating the surface tension of solution droplets to that of pure water, as assumed in κ- Köhler theory, overestimates the CCN activity of these complex organic particles. A possible evidence of the presence of surfactants is the formation of more than one hygroscopic activation modes in size-resolved CCN activation curves. While no change in κGF is observed after a 9 day- equivalent of atmospheric NH3-aging, a 72% increase in κCCN of OC particles suggests the presence of organic acidic groups in sufficient amount to influence the overall hygroscopic behavior of the particles. Chemical aging with O3 has no measurable impact on the κGF and κCCN of OC particles. My results suggest the possibility that oxidation of gas-phase volatile organic compounds in the aerosol by O3 causes them to condense as films on pre-existing particles. An evidence of such film formation is the reduced diameters of droplets exiting a cloud chamber, wherein the CCN have been exposed to a controlled supersaturation ratio for a fixed amount of time. We find that the possible participation of water taken up during aging at controlled relative humidity conditions does not affect hygroscopicity of OC particles. The results in this thesis are consistent with previously published results of effects of chemical aging with NH3 and O3 on the hygroscopicity of organic particles. Moreover, while previous studies have investigated organic particles of controlled initial composition, the results presented here apply to biomass pyrolysis OC particles. This thesis aids in understanding the important chemical aging mechanisms that organic particles emitted from pyrolysis of biomass could undergo, leading to their possibly increased hygroscopicity in the atmosphere.Submission published under a 24 month embargo labeled 'U of I only', the embargo will last until 2017-08-01The student, Rishabh Urvesh Shah, accepted the attached license on 2015-07-23 at 09:26.The student, Rishabh Urvesh Shah, submitted this Thesis for approval on 2015-07-23 at 09:32.This Thesis was approved for publication on 2015-07-23 at 11:12.DSpace SAF Submission Ingestion Package generated from Vireo submission #7853 on 2015-09-29 at 14:58:23Made available in DSpace on 2015-09-29T20:49:20Z (GMT). No. of bitstreams: 3
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LICENSE.txt: 4216 bytes, checksum: d56b5b188422c963d00d73b0e7e68192 (MD5)
Previous issue date: 2015-07-23Embargo set by: Seth Robbins for item 89410
Lift date: 2017-09-29T20:50:34Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemU of I Only Restriction Lifted for Item 89410 on 2017-09-30T09:15:30Z
Resilient regulation of wireless communication in distributed systems
No full textWith the rapid evolution of technology and the growing use of wireless devices in our daily lives, the need for regulating the interaction between such devices increases as these devices are easily accessible for both legitimate and malicious use. Therefore, in this work we focus on the regulation of wireless communication between the various agents of an open, mobile, heterogeneous distributed system. We first address the problem of under utilization of spectrum by describing a sec- ondary spectrum marketplace model to enable the spectrum consumers to trade exclu- sive access rights to a specific portion of the spectrum (designated by the frequency band, geographic location and time period) in return for fee payment, under the con- straint of obeying the trading rules formulated by the government in a decentralized peer-to-peer fashion. We then outline an architecture in which such exclusive access rights to a portion of the spectrum could be used to regulate radio device transmission to enable proactive enforcement of the spectrum usage policies and to deter unauthorized transmissions. Next, we introduce a model of interaction control for the regulation of wireless communication in ad hoc networks using the concept of Law Governed Interaction (LGI) to regulate the dynamic behavior of interacting wireless agents. Notably, we have implemented the LGI mechanism on the ORBIT testbed and shown its usefulness by prototyping an example based on a team of police officers in an ad hoc mission to control traffic. We have demonstrated that the overhead added due to LGI would not adversely impact performance. Since this implementation allows us to control the application level messaging performed by the wireless nodes, it can be viewed as an initial proof of concept for the architecture outlined in the first part of this work (dealing with the regulation of radio device transmission). Finally, we elaborate on the notion of resiliency in stateful decentralized access control with the goal of making LGI more trustworthy to the failure and compromise of its own enforcement infrastructure, so that it can address the needs of modern wireless distributed systems in a unified manner.Ph. D.Includes bibliographical referencesby Rishabh Dudheri
Sensing share space using Stereo Vision
No full textWith the increasing popularity of active modes (mainly pedestrians and bicycles), the spaces shared amongst these modes are also rising. Such spaces are often referred to as shared spaces and can often be seen in public areas near train stations, shopping streets and educational institutions. Such spaces are said to enhance safety and resolve spatial limitations of the space while the users are seen to exhibit interesting and complex behaviours as they freely interact with different modes approaching from various directions. This creates a need to collect data and understand the behaviour of people within such spaces. Many studies focusing on shared space interactions are limited by the current methods of data collection and data extraction. Other studies on people movement also face similar issues. Current data extraction approaches using cameras include repetitive and labour-intensive tasks which makes them costly and inefficient. Thus, this study focuses on automating the data extraction approach to obtain the ground-plane trajectories of people using the data recorded from a 3D-stereo vision camera. The data processing framework was divided into three main stages, (i) agent detection, (ii) ground-plane representation and (iii) agent tracking. The agent detection uses a neural-network-based detection model to detect people on the visual video which is then paired with the depth data to represent people on the ground plane. Each person is represented as a single point on the ground plane for every frame of the video. These points were then inputted into a tracking model to provides trajectories of people on the ground plane. Overall, this research integrates the recent state-of-the-art technologies into a single framework to automate the data extraction process and tests this framework in a real-world setting (behind the Amsterdam central station’s shared space area). For each stage, the advantages, challenge and recommendation for further improvements have been made. By automating the data processing of real-world datasets (including pedestrians and cyclists), This study reduces the cost and provides an easy way to collect and process data on real-world movements of pedestrians and cyclists. This will encourage urban planners to better understand people’s movement within their spaces and facilitate data-driven design approaches in the future
Aerodynamics of trailer wheels in tandem: Experimental investigation into the effects of wheel rotation, trailer side-skirts, and wheel cavity covers
No full textThe increasing importance of drag reduction in commercial vehicles, traditionally motivated by rising energy costs, and more recently accelerated through policymaking in a bid to reduce emissions, has resulted in the development of increasingly sophisticated add-on aerodynamic devices for the semi-trailer. Of these devices, the greatest uptake amongst trucking fleets has been for devices fitted to the underbody, primarily on account of allowing free movement of freight into and out of the trailer, hence incentivizing a better understanding of the flowfield in this region. The current research addresses the aerodynamics of trailer wheels in tandem, which form a key component of the semi-trailer underbody, by investigating the effects of wheel rotation, trailer side-skirts, and wheel cavity covers on the flowfield and drag. The configurations tested include a short side-skirt terminating before the front edge of the leading wheel, a long side-skirt covering both the wheels, wheel covers without openings (solid disks), and wheel covers with openings varying in coverage area and radial position. Stereoscopic (2D-3C) PIV is applied to examine the flow topology in the near wake and on selected planes besides the wheels. The measured velocity data in the wake is further used to derive the pressure field (by solving the Poisson equation for pressure), which together are then used to calculate the drag using a control volume approach. The uncertainty in the derived pressure field and drag values is determined using linear uncertainty propagation. The largest drag reduction from the baseline case, i.e. without a side-skirt or wheel covers, is seen for the long side-skirt, followed by the short side-skirt with wheel covers, short side-skirt only, and wheel covers only, in that order. The effectiveness of both the long side-skirt and wheel covers is seen to increase with wheel rotation, with an appreciable reduction in drag with the wheel covers fitted only seen for rotating wheels. Investigation of the flowfield in the wake shows significant differences between the stationary and rotating wheel, particularly within the region of the projected wheel profile, and indicates to an earlier separation of flow along the upper surface of the rotating wheel. The effect of the side-skirt on the velocity in the wake is seen primarily in a lower streamwise velocity deficit, narrower wake, and higher horizontal symmetry of the wake for the skirted configuration. Wheel covers show a comparatively limited effect on the velocity field in the wake, showing a marginally wider wake and a slightly higher velocity deficit for the uncovered wheel. On planes beside the wheels, the side-skirt and wheel covers show a greater influence than wheel rotation, considered to be a consequence of a static floor combined with a gap between the wheel and the ground. The non-skirted configurations here exhibit a larger region of separated flow and greater velocity deficit whereas the uncovered wheels show an outflow at the bottom of the wheel cavity and an inflow at the top. Finally, the wheel covers with openings show a behavior between that of a covered and an uncovered wheel, with the inflow/outflow depending significantly on the coverage percentage and radial position.Aerospace Engineerin
An ASIC with Bipolar High-Voltage Transmit Switching for a Single-Cable Intra-Vascular Ultrasound Probe
No full textAn ASIC is presented for intra-vascular ultrasound imaging. Despite being connected via a single coaxial cable, it is able to pass arbitrary high voltage bipolar signals to the transducers for acoustic imaging. The thesis talks about the need to reduce the cable count to one and reviews the existing work in literature. It builds up on an existing single cable design and focuses on the transmit part to make it compatible to a large number of ultrasound imaging modes by allowing it to pass high frequency signals up to 20MHz and bipolar signal voltages up to ±25V . The chip is phantom powered and thus its power supply and signals are transmitted on the same cable. The transmit switch designed for this ASIC is powered by and controlled by an on-chip low voltage supply and circuitry. The prototype ASIC has been designed in TSMC 180nm HV BCD Gen2 technology. This single cable design has 16 elements for transmit and 64 elements in the receive mode and was evaluated using simulations.Electrical Engineerin
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