84 research outputs found
Mineralogy-based global anthropogenic combustion-iron emission inventory
No full textTotal and soluble iron modulate ocean biogeochemistry and global nitrogen and carbon cycle in over 40% of global ocean. The understanding of the current and future changes in oceanic productivity can be improved by understanding and constraining the atmospheric inputs of iron. Models generally agree with observations for total and soluble atmospheric iron concentrations over oceans except in the iron limited Southern Ocean where they underestimate by two to five orders of magnitudes. Anthropogenic combustion-iron emissions are thought to be the missing link in some of the ocean regions and are currently underestimated in inventories along with a poor fuel-based solubility representation approach in contrast to dust-iron emissions which are better constrained and have mineralogy-based solubility approach. Here we show that anthropogenic combustion-iron emissions can be about 1 Tg Fe/yr in the fine fraction, 10 times higher than all previous inventories. A large part of the difference is attributed to metal smelting which was not accounted for in previous inventories. Anthropogenic combustion-iron contributes 30-50% of the total and soluble iron to the iron limited North and Equatorial Pacific Ocean and less than 10% to the Southern Ocean. Modeled estimates agree with observations everywhere except in the Southern Ocean where the underestimation persists even with the realistic maximum anthropogenic emissions. For the first time, we represent anthropogenic combustion-iron as a function of its mineral components and transition from a fuel-specific solubility to a mineralogy-based solubility approach. We find that increasing complexity in representing anthropogenic combustion-iron solubility does not necessarily improve model-observation comparison.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2021-08-01The student, Sagar Rathod, accepted the attached license on 2019-07-17 at 17:21.The student, Sagar Rathod, submitted this Thesis for approval on 2019-07-17 at 17:32.This Thesis was approved for publication on 2019-07-18 at 11:29.DSpace SAF Submission Ingestion Package generated from Vireo submission #14360 on 2019-11-26 at 14:04:22Made available in DSpace on 2019-11-26T20:59:50Z (GMT). No. of bitstreams: 2
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Previous issue date: 2019-07-18Embargo set by: Seth Robbins for item 113105
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Understanding the origins of stickiness in wheat flour tortillas and devising strategies to reduce it
No full textThis thesis aimed to determine the factors which affect stickiness in wheat flour tortilla products based on a phase/state-change approach and measurement of water activity and surface properties. Strategies were considered to reduce stickiness of flour tortillas by adding GRAS ingredients and modifying processing conditions.
Commercial wheat tortillas with a wide range of stickiness were selected and equilibrated to different water activity levels (0.12-0.97). Moisture sorption isotherms were developed. Differential scanning calorimetry and mechanical spectroscopy were used to characterize the phase behavior and freezable water, wide-angle x-ray scattering to understand the effect of crystallinity, contact angle measurements to determine the surface hydrophobicity. An objective instrumental test technique was developed using a texture analyzer to quantify the stickiness in tortilla samples. X-ray microtomography was used to measure tortilla cellularity. Tortillas were prepared with Xanthan gum, carboxymethylcellulose, glycerol and propylene glycol. To understand the effect of processing conditions on stickiness, tortillas were prepared using different combinations of dough resting times, baking temperatures and cooling times after baking.
Sticky tortilla showed lower glass transition temperature compared to non-sticky tortillas but both were in rubbery state at room temperature. Higher product Aw resulted in increase in surface energy which in turn caused an increase in instrumental stickiness scores as hypothesized. The polar component of surface energy was found to have a good correlation with stickiness. The sticky tortillas showed low crystallinity as compared to non-sticky tortillas. Tortillas containing 0.5 % gums and 4 % glycerol showed increased water retention, decreased water activity, reduction in surface free energy and lower freezable water. Addition of glycerol reduced the water activity from 0.94 to 0.91. Tortillas baked at 450° F were stickier than tortillas baked at 350°. Rupture force to extend tortillas increases with increase in storage time and temperature. Storage of tortillas at lower temperatures retains freshness as was shown by reduced rupture force values.M.S.Includes bibliographical references (p. 134-136)
Budhan Stories S1E6: Children Speak about Corona
No full textEpisode 6 of Season 1 contains Chharanagar children's expression about how they are pursuing Corona in their own way. What is the impact of lockdown, school close down, staying at home, over use of phone, online education etc. Directed (Author) by: Budhan Theatre Team. Participants: Dakxin Chhara, Atish Indrekar, Ruchika Kodekar, Chetna Rathod, Kushal Batunge, Keyur Bajrange, Anish Garange, Siddharth Garange, Alice Tilche, Akshay Khanna, Yashodara Udupa, Chharanagar Children, Sargam Rathod, Shubham Bajrange, Supplementary materials include poster and subtitles.</p
Exploring Author Profiling for Fake News Detection
No full textThe proliferation of online media allows for the rapid dissemination of unmoderated news, unfortunately including fake news. The extensive spread of fake news poses a potent threat to both individuals and society. This paper focuses on designing author profiles to detect authors who are primarily engaged in publishing fake news articles. We build on the hypothesis that authors who write fake news repeatedly write only fake news articles, at least in short-term periods. Fake news authors have a distinct writing style compared to real news authors, who naturally want to maintain trustworthiness. We explore the potential to detect fake news authors by designing authors’ profiles based on writing style, sentiment, and co-authorship patterns. We evaluate our approach using a publicly available dataset with over 5000 authors and 20000 articles. For our evaluation, we build and compare different classes of supervised machine learning models. We find that the K-NN model performed the best, and it could detect authors who are prone to writing fake news with an 83% true positive rate with only a 5% false positive rate.</div
Isothermal Flow Field Characterization of a Full-Scale Sector Combustor At Elevated Pressures
No full textAn experimental investigation in a sector (20 degree) of full-scale annular gas turbine combustor is performed. The distinctive feature of the experimental setup is that it preserves the geometrical details of an annular combustor that includes the casing, dome and combustor liner. The combustor design features a series of primary and secondary dilution holes with multiple film cooling strips on the outer and inner liner. In the present study, the combustor is operated at inlet Mach numbers of 0.02 - 0.3 at operating absolute pressures of 1 - 5 bar. Static pressure measurements are performed at multiple locations in the rig to characterize the pressure drop across the combustor. Two-dimensional particle image velocimetry (PIV) is performed to measure the velocity fields of the primary and exit zones of the combustor simultaneously. The results show the presence of a central recirculation zone (CRZ), high-velocity annular jets, and a pair of dilution jets in the primary zone of the combustor. The steady-state flow structures are invariant of inlet Mach number and pressures. The relationship between the relative pressure drop across the combustor and the combustor inlet condition is obtained. Mass flow rate and momentum flux are calculated for the flow through the swirl cup, central recirculation zone, the primary dilution jets, and the exit zone. The paper shows how the flow structures in a realistic combustor change with variations in global combustor parameters.The authors thank the Gas Turbine Research Establishment (GTRE) and Centre of Propulsion Technology (CoPT) for financial support of the research. The authors thank GTRE for its support in rig development and manufacturing. Author Darshan Rathod thanks the Prime Minister Research Fellowship (PMRF) for providing the research opportunity and scholarship. The measurements were performed using the facility of the National Center for Combustion Research and Development (NCCRD), ICER, IISc, Bangalore. The authors extend their thanks to Mr. Harsha Rajshekar and Ms. Samprada Kumbhare for their assistance in the experiment
Budhan Stories S2E10: Chhara Rap Song
No full textEpisode 10 of Season 2 was Chhara rap song where many Chhara people participated and displayed the bright side and dark side of Chhara people in Chharanagar. Created (Author) by: Keyur Bajrange. Participants: Budhan Theatre, Dakxin Chhara, Atish Indrekar, Ruchika Kodekar, Chetna Rathod, Kushal Batunge, Keyur Bajrange, Anish Garange, Siddharth Garange, Alice Tilche, Akshay Khanna, Yashodara Udupa, Chhara, Chharanagar, people of Chharanagar, Mohan Bajrange, Sulochanaben, Jonita Garange, Rajesh Bajrange.Supplementary materials include: short clips, poster and subtitles. </p
Verification of the non-local avalanche current model in mextram for advanced SiGe HBTs
No full textTo realize optimum performance, SiGe HBTs are typically designed with heavily doped implanted collectors. For practical circuits operating at either high collector current density (Jc) or high collector-base voltage (Vcb) avalanche multiplication is an important effects that must be accurately measured and modeled. For example in digital applications, the avalanche multiplication factor (M-1) determines the breakdown voltage, which in turn determines the maximum power supply for stable logic operation. In critical RF circuits such as power amplifiers (PA) and low noise amplifiers (LNA), the base-collector junction avalanche multiplication degrades the linearity of the circuit because of the resulting strong non-linear feedback from the output (collector) to input (base) is particularly the case for state-of-art high-performance transistors featuring high collector doping. Therefore the accuracy of avalanche multiplication models in different operational conditions is critical to devices design of high linearity LNA and PA circuits. In this thesis, the temperature dependence of the avalanche current in Mextram compact model is addressed through extensive DC measurements over temperature on advanced industrial SiGe HBTs, it was discovered that the current local-electric field based avalanche current model in the Mextram model is incapable of describing the avalanche current as a function of device temperature.This setback is the key motivation behind the work in this thesis. By employing the simplified energy-balance equation, the impact ionization rate was expressed in terms of the carrier (electron for NPN HBT) energy or temperature (Te). Here a triangular shaped electric field distribution corresponding to the normal forward operation regime was assumed. Taking the integral of the electron temperature dependent ionization rate over the epilayer yielded the non-local multiplication factor. The product of the multiplication factor with epilayer current gives the non-local avalanche current, which takes non-local avalanche effects into account. The compact formulation of this non-local avalanche current model was derived and implemented at Delft University of Technology in the in-house version of Mextram compact model. An extended experimental verification of the new compact model for the non-local avalanche current implemented in Mextram was carried out for different advanced SiGe HBT technologies; and the results are presented in this thesis. Verification results showed that the non-local avalanche current model can accurately describe the avalanche current as a function of temperature for different SiGe HBTs (both NPN and PNP). These results implies that the observed setback in Mextram model with respect to the temperature dependence of the avalanche current can be fully addressed by taking non-local avalanche effects into account.MSc MicroelectronicsMicroelectronics & Computer EngineeringElectrical Engineering, Mathematics and Computer Scienc
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