42 research outputs found
Entrainment studies in cloud-like flows using novel scanning tomography technique
No full textClouds are one of the major sources of uncertainty in climate prediction.The present work is to study the dynamics of orographic clouds. We considered a planar turbulent wall jet with off source volumetric heating as an appropriate low order fluid-dynamical model for studying the turbulence and entrainment in orographic-clouds. Entrainment was found to reduce drastically with the off-source volumetric heat addition. We found that the reduction of entrainment started at a bulk-Richardson number which was an order of magnitude smaller than that seen in earlier experiments [1] on free standing cumulus clouds. This is consistent with observations in real orographic clouds which develop as a thin sheet rising along the mountain slope. We have developed a novel scanning tomography technique for getting concentration field in turbulent shear flows. This technique is being applied on cloud-like flow to understand the entrainment characteristics. Detailed results will be presented at the conference
Influence of Sn doping in BaSnxTi1−xO3 ceramics on microstructural and dielectric properties
No full textA study verifying the simulation of market trading with Dynamic Pari-Mutuel mechanism using Python
No full textWagering is common in various arenas that include but not limited to horse racing, casinos, financial markets and stock trading. Several market mechanisms are used in these markets to predict the outcome based on the available information and make an educated decision in an investment involving huge risks. One such market mechanism is the Dynamic Pari-Mutuel market mechanism developed by Pennock.
In this study I describe a python based implementation of the mathematical models used in Dynamic Pari-Mutuel mechanism. The simulation that simulates the market transactions is then validated by verifying if the price generated for each purchase transaction follows a random walk path. This work would be a gate-way leading to opportunities to study various complicated market scenarios by extending the existing capabilities of the simulation.Item withdrawn by Laura Spradlin ([email protected]) on 2014-04-29T20:35:58Z
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Release Date: 2016-05-30 12:09:03 UTC
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Preparation of Protein Hydrolysates from Fish Egg
No full textThis Dissertation / Report is the outcome of investigation carried out by the creator(s) / author(s) at the department/division of Central Food Technological Research Institute (CFTRI), Mysore mentioned below in this page
Studies on gait control using a portable pneumatically powered ankle-foot orthosis (PPAFO) during human walking
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Previous issue date: 2016-02-17Embargo set by: Seth Robbins for item 93071
Lift date: 2018-07-07T20:28:14Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 93071
Lift date: 2018-07-07T20:35:34Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemU of I Only Restriction Lifted for Item 93071 on 2018-07-08T09:15:20Z.A powered ankle-foot orthosis (AFO) can be very useful for people with neuromuscular injury. Control of powered AFOs will be more efficient to provide assistance to individuals with lower limb muscle impairments if we can identify different gait events during walking. A walking or gait cycle can be divided into multiple phases and sub-phases by proper gait event detection, and these phases/sub-phases are associated with one of the three main functional tasks during the gait cycle: loading response, forward propulsion, and limb advancement. The gait cycle of one limb can also be characterized by examining the limb’s behavior over one stride, which can be quantified as 0% to 100% of a gait cycle (GC). One easy approach to identify gait events is by checking whether sensor signals go above/below a predetermined threshold. By estimation of a walker’s instantaneous state, as represented by a specific percentage of the gait cycle (from states 0 to 100, which correlate with 0% to 100% GC), we can efficiently detect the various gait events more accurately. Our Human Dynamics and Controls Laboratory previously developed the portable pneumatically powered ankle-foot orthosis (PPAFO), which was capable of providing torque in both plantarflexion and dorsiflexion directions at the ankle. There were three types of sensor attached with the PPAFO (two force sensitive resistors and an angle sensor). In this dissertation, three aspects of effective control strategies for the PPAFO have been proposed. In the first study, two improved and reliable state estimators (Modified Fractional Time (MFT) and Artificial Neural Network (ANN)) were proposed for identifying when the limb with the PPAFO was at a certain percentage of the gait cycle. A correct estimation of percentage of gait cycle will assist with detecting specific gait events more accurately. The performance of new estimators was compared to a previously developed Fractional Time state estimation technique. To control a powered AFO using these estimators, however, detection of proper actuation timing is necessary. In the second study, a supervised learning algorithm to classify the appropriate start timing for plantarflexor actuation was proposed. Proper actuation timing has only been addressed in the literature in terms of functional efficiency or metabolic cost during walking. In this study, we will explore identifying the plantarflexor actuation timing in terms of biomechanics outcomes of human walking using a machine learning based algorithm. The third study investigated the recognition of different gait modes encountered during walking. The actuation scheme plays a significant role in walking on level ground, stair descent or stair ascent modes. The wrong actuation scheme for a given mode can cause falls or trips. A gait mode recognition technique was developed for detecting these different modes by attaching an inertial measurement unit and using a classifier based on artificial neural networks. This new algorithm improves upon the current one step delay limitation found as a drawback of a previously developed technique. Overall, this dissertation focused on addressing some important issues related to control of powered AFO that ultimately will help to assist people wearing the device in daily life situations during walking. The proposed approaches and algorithms introduced in this dissertation showed very promising results that proved that these methods can successfully improve the control system of powered AFOs.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2018-05-01The student, Mazharul Islam, accepted the attached license on 2016-02-16 at 13:00.The student, Mazharul Islam, submitted this Dissertation for approval on 2016-02-16 at 13:16.This Dissertation was approved for publication on 2016-02-17 at 10:11.DSpace SAF Submission Ingestion Package generated from Vireo submission #9079 on 2016-07-07 at 13:48:1
Bridge Load Testing: State-of-The-Practice
No full textBridge load testing can answer a variety of questions about bridge behavior that cannot be answered otherwise. The current governing codes and guidelines for bridge load testing in the United States are the 1998 NCHRP Manual for Bridge Rating through Load Testing and Chapter 8 of the AASHTO Manual for Bridge Evaluation. Over the last two decades, the practice of load testing has evolved, and its intersections with other fields have expanded. The outcomes of load tests have been used to keep bridges open cost-effectively without unnecessarily restricting legal loads, when theoretical analyses cannot yield insights representative of in-service performance. Load testing data can be further used to develop field-verified finite-element models of tested bridges to understand these structures better. In addition, structural reliability concepts can be used to estimate the probability of failure based on the results of load tests, and noncontact measurement techniques capturing large surfaces of bridges allow for better monitoring of structural responses. Given these developments, a new Transportation Research Board (TRB) Circular, Primer on Bridge Load Testing, has been developed. This document contains new proposals for interpreting the results of diagnostic load tests, loading protocols, and the determination of bridge load ratings based on the results of proof load tests. In addition, included provisions provide an estimation of the resulting reliability index and the remaining service life of a bridge based on load testing results. The benefit of load testing is illustrated based on a cost-benefit analysis. The current state-of-The-practice has demonstrated that load testing is an effective means for answering many important questions regarding bridge behavior that are critical to decisions on bridge maintenance or replacement. Load testing has evolved over its history, and the newly developed TRB Circular reflects this evolution in a practical way. Accepted Author ManuscriptConcrete Structure
Synthesis and structural properties of Ba(1-x)LaxTiO3 perovskite nanoparticles fabricated by solvothermal synthesis route
No full textTopics on option valuation and model calibration
No full textThis dissertation is devoted to high performance numerical methods for option valuation and model
calibration in L´evy process and stochastic volatility models. In the first part, a numerical scheme
for simulating from an analytic characteristic function is developed. Theoretically, error bounds
for bias are explicitly given. Practically, different types of options in commonly used L´evy process
models could be priced through this method fast and accurately. Also, sensitivity analysis could be
conducted through this approach effectively. Numerical results show that the schemes are effective
for both options valuation and sensitivity analysis in L´evy process models. In the second part, a
numerical scheme for Asian option pricing in jump-diffusion models is analyzed. Approximation
errors are shown to decay exponentially. Numerical results show the speed and accuracy of the
scheme. In the third part, for calibration purpose, certain numerical schemes are studied to price
European and American options. For European options, error bounds are explicitly given. For
American contracts, multiple options with different strikes and maturities could be priced simultaneously.
Numerical results show that the combination of the above schemes with state-of-the-art
optimization schemes makes efficient calibration of option pricing models possible.Item withdrawn by Alexis Thompson ([email protected]) on 2013-04-15T21:41:58Z
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CFD Investigation of Human Tidal Breathing through Human Airway Geometry
No full textAbstractThis study compares the effect of the extra-thoracic airways on the flow through the lower airways by carrying out computational fluid dynamics (CFD) simulations of the airflow through the human respiratory tract. In order to facilitate this comparison, two geometries were utilized. The first was a realistic nine-generation lower airway geometry derived from computed tomography (CT) images, while the second included an additional component, i.e., an idealized extra-thoracic airway (ETA) coupled with the same nine-generation CT model. Another aspect of this study focused on the impact of breathing transience on the flow field. Consequently, simulations were carried out for transient breathing in addition to peak inspiration and expiration. Physiologically-appropriate regional ventilation for two different flow rates was induced at the distal boundaries by imposing appropriate lobar specific flow rates. The scope of these simulations was limited to the modeling of tidal breathing at rest. The typical breathing rates for these cases range from 7.5 to 15 breaths per minute with a tidal volume of 0.5 Liter (L). For comparison, the flow rates for constant inspiration/expiration were selected to be identical to the peak flow rates during the transient breathing. Significant differences were observed from comparing the peak inspiration and expiration with transient breathing in the entire airway geometry. Differences were also observed for the lower airway geometry. These differences point to the fact that simulations that utilize constant inspiration or expiration may not be an appropriate approach to gain better insight into the flow patterns present in the human respiratory system. Consequently, particle trajectories derived from these flow fields might be misleading in their applicability to the human respiratory system
An Adaptive Time Reduction Technique for Video Lectures
No full textabstract: Lecture videos are a widely used resource for learning. A simple way to create
videos is to record live lectures, but these videos end up being lengthy, include long
pauses and repetitive words making the viewing experience time consuming. While
pauses are useful in live learning environments where students take notes, I question
the value of pauses in video lectures. Techniques and algorithms that can shorten such
videos can have a huge impact in saving students’ time and reducing storage space.
I study this problem of shortening videos by removing long pauses and adaptively
modifying the playback rate by emphasizing the most important sections of the video
and its effect on the student community. The playback rate is designed in such a
way to play uneventful sections faster and significant sections slower. Important and
unimportant sections of a video are identified using textual analysis. I use an existing
speech-to-text algorithm to extract the transcript and apply latent semantic analysis
and standard information retrieval techniques to identify the relevant segments of
the video. I compute relevance scores of different segments and propose a variable
playback rate for each of these segments. The aim is to reduce the amount of time
students spend on passive learning while watching videos without harming their ability
to follow the lecture. I validate the approach by conducting a user study among
computer science students and measuring their engagement. The results indicate
no significant difference in their engagement when this method is compared to the
original unedited video.Dissertation/ThesisMasters Thesis Computer Science 201
