122 research outputs found
Computer vision for automated surface evaluation of concrete bridge decks
No full textStructural health monitoring of concrete bridges requires accurate and efficient surface crack detection. Early detection of cracks helps prevent further damage. Safety inspection tests are conducted at regular intervals to assess deterioration. Traditional methods involve detection of cracks by human visual inspection. These methods are costly, inefficient and labor intensive, especially for long-span bridges. This thesis presents the use of computer vision and pattern recognition techniques in assessment of cracks on a concrete bridge surface. Bridge deck images are first collected using high-resolution cameras mounted on a robot. Statistical inference algorithms are then implemented to build an automated crack detection system. The proposed machine learning method reduces manual effort and enables automatic labeling over large bridge deck areas to quantify size and location for future reference or comparisons. A panoramic camera is used for the purpose of context localization. Additionally, we demonstrate image-stitching to obtain a coherent spatial mosaic of the bridge deck.M.S.Includes bibliographical referencesby Prateek Prasann
The effect of lime juice on Vibrio parahaemolyticus and Salmonella enterica inactivation during the preparation of raw fish dish ceviche
No full textCeviche is a Peruvian raw fish dish. It is extremely popular in the South American countries and has recently gained prominence in USA. It can be made with many types of seafood but is most commonly in USA with tilapia. The most characteristic feature of ceviche is the use of lime juice for marinating the raw fish. No ingredient of the dish is cooked in the conventional sense of applying heat. There have been confirmed cases of cholera in Peru, New Jersey and Florida, associated with ceviche. Since lime juice is sole means of controlling risk in ceviche recipes across the world, it is important to study its anti-bacterial effects. Even though the literature is very rich in the use of organic acids as anti-bacterial agents, little data exists for their effect in seafood systems. The objective of the study was to study the anti-bacterial effects of lime juice marination in ceviche as it would be prepared in restaurants or homes. Target pathogens were Vibrio parahaemolyticus and Salmonella enetrica. Samples were incubated at room temperature (25°C) and refrigeration temperature (4°C) for time intervals up to 150 minutes. In experiments with Salmonella at room temperature, a mean log reduction of 0.8 was observed while at refrigeration temperature a mean log reduction of 2.1 was observed. Reduction in Vibrio parahaemolyticus could only be estimated based on starting levels and detection limits as the plate counts were always below the detection limit for all the times studied (10-150 minutes), both at room and refrigeration temperatures. In experiments at room temperature, log reductions varied from >4.5 to >5.2 while at refrigeration temperature, log reductions varied from >3.5 to >4.3. In experiments testing the inhibitory effect of lime juice, without the fish matrix, more than 5 log reductions in counts was observed on both bacteria. We conclude that preparing ceviche reduces Vibrio parahaemolyticus risk significantly but is less effective for control of Salmonella enetrica.M.S.Includes bibliographical referencesby Prateek Mathu
Identity and Diaspora : Practices of Migration, Religion, Ethnicity & Culture in South Asia.
No full textBy Prateek Srivastava, International Affairs, Journalism
Advisor: Megan Lamkin
Presentation ID: Room417_2
Abstract: Identity and Diaspora discuss about five different ethnic crisis and violence in Asia. These communities and cases are not only lesser known but also are examples of grave violence, discrimination, and migrations. These cases deal with identity such as race, religion, color and gender and how these identities have triggered certain violence and policies within Asia. The author emphasizes understanding different aspects, like religious and racial animosity, constitutional negligence and strategic violence, ethnic discrimination, among these cases. In five chapters, the author discusses the case of Burmese Indians, Muslims in Sri Lanka, Nepalese in Bhutan, Indophobia, Assam-Bengali crisis. In this accessible and student-friendly book, author Prateek Srivastava focuses on discussing certain aspects of migration and identity crises, which happened on a low scale or were lesser known. The author also discusses the policies followed by these countries/governments and how international communities and policymakers can prepare for any such kind of crisis or event that may happen in future. These cases are described after extensive research and can act as a framework to understand the perspectives of countries, governments, and regimes for any future practice of such kinds
On the use of two-point velocity correlation in wall-pressure models for turbulent flow past a trailing edge under adverse pressure gradient
No full textTwo-point velocity statistics near the trailing edge of a controlled diffusion airfoil are obtained, both experimentally and analytically, by decomposing Poisson's equation for pressure into the mean-shear (MS) and turbulence-turbulence (TT) interaction terms. The study focuses on the modeling of each interaction term, in order to allow for the reconstruction of the wall-pressure spectra from tomographic velocimetry data, without numerically solving for pressure. The two-point correlation of the wall-normal velocity that describes the magnitude of the MS source term is found to be influenced by various competing factors such as blocking, mean-shear, and the adverse mean pressure gradient. The blocking term is found to supersede the other interaction terms close to the wall, making the two-point velocity correlation self-similar. The most dominant TT term that contributes to far-field noise for an observer located perpendicular to the airfoil chord at the mid-span is shown to be the one that quantifies the variation of the wall-normal velocity fluctuations in the longitudinal direction because of the statistical homogeneity of turbulence in planes parallel to the wall. A model to determine the contribution of the TT interaction term is proposed where the fourth-order two-point correlation can be modeled using Lighthill's approximation. However, its contribution toward wall-pressure spectra is found to be substantially lower than the MS term in the present case. 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.Wind Energ
Estimation of the global carbon fluxes due to agricultural management activities using a land surface model (ISAM)
No full textAgricultural activities contribute to global greenhouse gas (GHG) emissions and climate. The worldwide hike in the food demand due to the rapidly growing population over time has intensified agricultural activities, resulting in a significant amount of GHG emissions (e.g., CO2, CH4, and N2O). Previous global studies have focused on non-CO2 emissions (i.e., CH4, N2O) and ignored the CO2 emissions from the agriculture sector. This study uses a land surface model with spatially heterogeneous representations of agricultural land management practices to estimate the carbon dynamics induced by agricultural land management practices (i.e., planting crops, fertilization, irrigation, harvesting, and grazing) and land-use change (i.e., agricultural land expansion). The estimated global net carbon emission from agriculture and its related land-use change is 2.26 Pg C/yr (net source) in ca. 2010. The land management activities released 0.85 Pg C/yr (38%), and the land-use change activities emitted 1.41 Pg C/yr (62%). Cropland and grazing land released about 72% and 28% of the total agriculture emissions. Maize, rice, and wheat are the greatest contributing crops. South America (22%), North America (19%) and, South and Southeast Asia (13%) are the leading emitting regions. By quantifying the carbon emissions induced by different agricultural management practices, this study help in improving the representations of land management practices in the climate models.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2022-12-01The student, Prateek Sharma, accepted the attached license on 2020-12-08 at 15:40.The student, Prateek Sharma, submitted this Thesis for approval on 2020-12-08 at 15:58.This Thesis was approved for publication on 2020-12-09 at 17:00.DSpace SAF Submission Ingestion Package generated from Vireo submission #16090 on 2021-03-04 at 16:33:52Made available in DSpace on 2021-03-05T21:47:35Z (GMT). No. of bitstreams: 2
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Computational analysis of planar wings designed for optimum span-load
No full textA computational analysis of three span-optimized wings was conducted using an open-source CFD tool. Simulations were carried out at Rec = 450; 000 in a semi-spherical domain consisting of unstructured tetrahedra close to the wing surface and pyramids in the farfield region. Simulations were carried out in both steady state and semi-transient states to predict ow transition. A comparative study of different turbulence models revealed k-omega-SST and k - kL-omega to be the most suitable turbulence models for this study. The model accuracy was determined using validations with experimental data from a previous study. The required accuracy was achieved using the most appropriate mesh resolution for all three wing designs and second order discretization schemes. Computational results indicated different drag characteristics between the three span-load optimized wings at the design CL. The Viscous Optimized Wing produced the minimum drag while the Elliptic Wing produced the largest drag at design CL. The Inviscid Optimized Wing had the largest aspect ratio but still produced lesser drag when compared to the Elliptical Wing. Surface ow visualization indicated different ow transition characteristics for the three wings. These differences were attributed to the twist distributions specific to each wing. The Inviscid Optimized wing was observed to have largest laminar boundary-layer region at design angle of attack. Qualitative wake analysis indicated different wake characteristics for each wing, attributed to the different span-loads. The Elliptic Wing had the most aggressive wake roll-up. Much lesser wake roll-up was observed for the Inviscid and Viscous Optimized Wings. The largest wake cross-section was observed for the Elliptic Wing, while the smallest wake cross-section was observed for the Inviscid Optimized Wing.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2018-08-01The student, Prateek Ranjan, accepted the attached license on 2016-07-22 at 11:12.The student, Prateek Ranjan, submitted this Thesis for approval on 2016-07-22 at 11:25.This Thesis was approved for publication on 2016-07-22 at 16:28.DSpace SAF Submission Ingestion Package generated from Vireo submission #10076 on 2016-11-10 at 12:27:41Made available in DSpace on 2016-11-10T18:35:38Z (GMT). No. of bitstreams: 2
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Determining the viability of breathwork and meditation as intervention techniques for stress in the forensic science community
No full textThe aim of this project was to determine the viability of breathwork and meditation as intervention techniques for stress in the forensic science community. Practitioners in the field and students studying forensic science to become future practitioners were included as participants. The General Well-Being Schedule (GWBS) and the Perceived Stress Scale (PSS) were used to assess the psychological changes in stress and stress responses. Salivary cortisol and cortisone measurements provided statistics to analyze hormonal changes in stress. Participants of the study were requested to partake in practicing cyclic physiological sighing and mindfulness meditation for 30 days, depending on their random assignment into these intervention groups. Subjects in the breathwork group were required to practice the method for five minutes every day, and those in the meditation group had to meditate for 15 minutes every day during the study. They provided survey responses and saliva samples before and after the intervention period, and the hypothesis was that these measurements would reflect a reduction in stress levels. To account for external variables such as previous experience with these methods, exercise habits, religious/spiritual influences, frequency of practice, length of practice during each session, and time of day of practice, these were used to create participant subsets that were analyzed for statistically significant changes (p < 0.05). The data showed that all participants who had previously practiced breathwork (p = 0.012) and students who had previously meditated (p = 0.032), regardless of their randomly assigned intervention in this study, had noticed statistically significant changes in their perceptions of stress. The mean difference of scores on the PSS for the two intervention techniques was calculated to be - 2.4 ± 5.0 for breathwork and - 2.5 ± 5.0 for meditation. The GWBS responses and the salivary measurements did not reflect any statistically significant positive changes in the direction of stress reduction. In most cases, there appeared to be an increase in scores and concentrations of the participants. The inference from the statistics analyzed in this study would suggest that practicing these interventions for 30 days only reduced one’s perception and response to stress. The inner well-being and hormonal measurements either stayed the same or increased in some cases, which could be attributed to multiple factors specific to stressors and the nuances of the cortisol-cortisone dynamic in saliva. The data also suggests that breathwork is more efficient in improving perceptions of stress among this population. The positive changes in college students makes a case for integrating these methods as teachings for healthy coping mechanisms of stress in forensic science curricula. Meditation and breathwork have a track record of improving stress levels in most cases. Therefore, future research efforts should look at implementing these interventions in this population for longer intervention periods to assess if their inner well-being and hormonal responses change significantly. Studies should also be performed to understand the enzymatic activity that converts cortisol to cortisone under the variables of stress, breathwork, and meditation
A sweet and sour relationship: Algal-bacterial interactions and the interplay of carbohydrate accumulation and fermentation on biohydrogen production
No full textMechatronic and biomechanical considerations toward the design of an ankle clonus simulator
No full textClonus is a rhythmic, involuntary reflex response often seen in individuals with lesions in their descending motor neurons. These lesions can be the result of spinal cord injury or diseases like multiple sclerosis, Parkinson’s disease and cerebral palsy. During clinical evaluation of an individual suspected of having lesions in their descending motor neurons, an ankle clonus test is often employed. Clinical evaluation of clonus is currently reported using qualitative rating scales and therefore accurate diagnosis is largely dependent on the clinician’s experience. Clinician trainees may not be able to obtain sufficient training time with patients to understand and diagnose clonus effectively. Thus, we, at the Human Dynamics and Controls Lab, designed an electromechanical ankle clonus simulator, based on a series elastic actuator mechanism, that is capable of providing training for administration of an ankle clonus test and therefore substituting the need of human patients. The ankle clonus simulator is intended to accurately mimic the behavior of the ankle joint of a patient demonstrating ankle clonus. However, to obtain confidence in the performance of the ankle clonus simulator, clonus has to be academically explored after which, biomechanical and mechatronic requirements of the simulator must be investigated.
This thesis first presents an overview of ankle clonus and subsequently establishes specific research questions that needed to be answered, based upon which biomechanical targets, anthropomorphic designs, and sensor subassemblies are constructed. Biomechanical models of passive ankle torque to be mimicked by the simulator were developed and preliminary evaluation of sensors designed to be included in the first-generation ankle clonus simulator was conducted. To determine the optimal model for passive joint moment, in both healthy individual case and clonus’s case, two different ankle passive stiffness models, derived from literature, were computed and compared. Double exponential functions were consequently selected as the appropriate models for passive stiffness for healthy and clonus cases. Sensor systems were designed to provide appropriate force readings, joint angle measurements and estimates of clinical learner’s hand position on the foot structure of the simulator. Off-device testing stations/fixtures for these sensors were built to evaluate the selected sensor’s efficacies and also to inform us of the final torque error margins (<5%) and ankle angle margins (<1%) that the clonus simulator would operate in. Overall, enough confidence was established in selected sensors such that an ankle clonus simulator that is manufactured based on the designs presented in this thesis would be able to perform as intended.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2021-12-01The student, Prateek Garag, accepted the attached license on 2019-12-12 at 13:01.The student, Prateek Garag, submitted this Thesis for approval on 2019-12-12 at 13:14.This Thesis was approved for publication on 2019-12-13 at 08:34.DSpace SAF Submission Ingestion Package generated from Vireo submission #14813 on 2020-02-28 at 17:24:31Made available in DSpace on 2020-03-02T22:18:20Z (GMT). No. of bitstreams: 2
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