136 research outputs found
Flexible Graphite−Poly(Lactic Acid) Composite Films as Large-Area Conductive Electrodes for Energy Applications
No full text<p>Raw data of energy storage part -author Kalyan Ghosh </p>
Group-oriented secret sharing using Shamir's algorithm
No full textIn the current state of highly distributed and hybrid-cloud systems environment, managing and securing enterprise or government systems/data requires effective access control techniques and protocols. Currently, individual and independent logins using single or multi-factor passwords are widely used across the industry, but they are highly vulnerable to hacking, phishing and various password stealth techniques. For securing highly sensitive IT assets, comprehensive data management and governance programs include group-oriented login or authorization procedures, wherein a group of individuals or processes (as opposed to a single individual) provide their credentials/passwords or keys to gain access to the sensitive resource. To implement the group-oriented login, a widely acclaimed cryptographic technique, Secret Sharing, offers an elegant and secure solution. In this technique, the secret (password) is divided into multiple shares in such a way that a threshold number of shares are essential to reconstruct the secret (password). Shamir’s Secret Sharing uses this cryptographic technique, and the Secret Share splitting and reconstruction are based on a polynomial over a finite field. The goal of this thesis is to study and evaluate this technique with reference to threshold based group-login by various examples.M.S.Includes bibliographical referencesby Kalyan Koushik Alapat
Long-term management of rice agroecosystem towards climate change mitigation
No full textThe Intergovernmental Panel on Climate Change recognize to agriculture the responsibility for about 15 % of global anthropogenic greenhouse gas (GHG) emissions, contributing to global warming. The increasing nutrient inputs in industrial agriculture affect the GHG concentration in the atmosphere and varies substantially due to rate and type of fertilizers applied to the crops, making the management more or less sustainable. In this perspective, this study has investigated at small scale the effect of different adjusted agricultural management practices, based on different nutrient dosage, to optimize the effect of rice cropping systems on carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) emissions. Farmyard manure (FYM), rice stubbles and Azolla integrated with chemical fertilizers have been correlated with microbial and enzymatic activities, and with different carbon and nitrogen fractions in acid Inceptisol. Results have revealed that the integrated nutrient management used in rice-rice agroecosystem yielded a peak for CO2 and CH4 emissions, whereas two peaks for N2O emission. This study has shown an increase in greenhouse gas emission intensity (GHGI) and grain yield of rice in the following order: rice stubbles > FYM > Azolla and it has confirmed CH4 emission as the dominant contributor to GHGI from the rice-rice agroecosystem. When analyzed together GHGs emission and soil properties, a positive correlation was found with biological properties as well as with the different carbon and nitrogen fractions in soil. The highest GHGI has been highlighted in the treatment where recommended dose of chemical fertilizers has been combined with rice stubbles, primarily due to the increase in CH4 emissions. In contrast, the lowest GHGI has been exhibited in Azolla treated plot, probably due to the cumulative effects of the photosynthetic rate of Azolla, the release of oxygen from the Azolla roots, and the physical protection capacity of the Azolla cover, which partially avoid the CH4 diffusion from the standing water. The seasonality did not affect the estimated rates of GHGI that have been lower both in case of winter and autumn rice compared to previous studies, probably for dissimilarities in management practices. Further research is required in other cropping sequences for addressing the ecological contribution of smallholder agriculture to help reducing GHG emissions, thus, mitigating global warming with actions at local scale
Author identification system
No full textAbstract: Every one of us has different approach to speak and write, and there exists a long history of linguistic and stylistic analysis into authorship attribution. In last year’s, practical application for author identification have grown in area such as computer forensic(linking intercepted message to each other and to find rebel), criminal law(identifying author of payoff notes and harassing letter), civil law and computer security (tracking author of computer source code). This paper proposes the implementation of author identification system. This proposed system is based upon the principles and concepts of text analysis. For ensuring maximum accuracy in identifying author of the document we will be using TF-IDF algorithm which consists of extraction of features from the text, scoring these features and comparing them with a set of scores stored in the corpus
Kalyan Kumar Sarkar’s Perception on Early India and Cambodia: Unveiling A New Source In The Historiography of India - South-East Asia Interaction
No full textThis article tries to analyze the writings of Kalyan Kumar Sarkar regarding early India's interaction with Cambodia thus intending to highlight over an intriguing aspect of India's historiography. Emerged as a significant part of Indian cultural nationalism, this historiography aims to focus on India's cultural contribution to the neighbouring countries. Books and articles written by the author under discussion, show how they successfully endorsed such a concept of 'Indianization' where India's inclusive impact on Cambodia, like many other South-East Asian countries, led her to form a part of 'Greater India' or extended India. Various scholars have made efforts to discuss the contributions of eminent historians who were part of this academic endeavor. But the discourse also shows active academic participation from scholars whose writings have failed to get the necessary attention from researchers. Study of these sources is important as they provide a comprehensive understanding of the relevant historiography. My article thus attempts to discuss Kalyan Sarkar's writings and examines their limitations and significance- how far they showed biasness towards Indian impact yet acknowledged the local characters. A comprehensive discussion is attempted to understand the author's ability to interpret sources and rational analytical framework present in his writings
Three-dimensional hot electron photovoltaic device with vertically aligned TiO2 nanotubes
No full textTitanium dioxide (TiO2) nanotubes with vertically aligned array structures show substantial advantages in solar cells as an electron transport material that offers a large surface area where charges travel linearly along the nanotubes. Integrating this one-dimensional semiconductor material with plasmonic metals to create a three-dimensional plasmonic nanodiode can influence solar energy conversion by utilizing the generated hot electrons. Here, we devised plasmonic Au/TiO2 and Ag/TiO2 nanodiode architectures composed of TiO2 nanotube arrays for enhanced photon absorption, and for the subsequent generation and capture of hot carriers. The photocurrents and incident photon to current conversion efficiencies (IPCE) were obtained as a function of photon energy for hot electron detection. We observed enhanced photocurrents and IPCE using the Ag/TiO2 nanodiode. The strong plasmonic peaks of the Au and Ag from the IPCE clearly indicate an enhancement of the hot electron flux resulting from the presence of surface plasmons. The calculated electric fields and the corresponding absorbances of the nanodiode using finite-difference time-domain simulation methods are also in good agreement with the experimental results. These results show a unique strategy of combining a hot electron photovoltaic device with a three-dimensional architecture, which has the clear advantages of maximizing light absorption and a metal-semiconductor interface area. © 2018 The Author(s
Air-coupled non-destructive evaluation technology for condition assessment of railroad ties
No full textThis study describes the development of fully air-coupled non-destructive evaluation (NDE) technology for condition assessment of railroad ties. Ultrasonic surface waves are generated in railroad ties using an air-coupled ultrasonic sender. Surface waves are sensed at the receiving end using an array of Micro-Electro Mechanical sensors (MEMs). The resulting wave field is visualized in time-space (t-x domain) and frequency-wavenumber domains (f-k domain) to derive parameters indicative of the extent of damage in crossties. A robust “wave front fitting algorithm” is developed to estimate surface wave speed from a B-scan image generated using multiple time domain signals. Five signal parameters, namely surface wave speed from t-x domain, energy of the wave field in t-x domain, coherent surface wave speed from f-k domain, maximum value in f-k domain, and area under the k-plot at excitation frequency, are investigated for sensitivity to damage in crossties. Crossties with different types of damage; transverse cracking, longitudinal cracking, loss of cross section, and rail seat damage (RSD) are tested in this study. Signal parameters computed from the damaged ties are compared with signal parameters obtained from ties in a good structural condition (crossties without any visible damage) to generate decision spaces. The ability of these decision spaces to distinguish “good” crossties and “damaged” crossties is investigated using two parameters: hit-rate and reliability factor. The decision spaces are ranked based on these values to determine the most reliable decision spaces for predicting the structural state of a crosstie beyond a reasonable confidence level. It is observed that two-dimensional decision spaces performed better than one-dimensional decision spaces in predicting the structural state of a crosstie. The results demonstrate that the 2-D decision space of coherent wave speed from f-k domain vs. maximum value in f-k domain performed the best among all other decision spaces discussed in this study, followed by 2-D decision space of surface wave speed from f-k domain vs. coefficient of variation for surface wave speed from f-k domain, 2-D decision space of surface wave speed from t-x domain vs. energy in t-x domain, and 2-D decision space of surface wave speed from t-x domain vs. maximum value in f-k domain. A prediction scheme is developed for predicting the structural condition of a crosstie based on the location of signal parameters in various 2-D decision spaces.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2019-08-01The student, Sai Kalyan Evani, accepted the attached license on 2017-07-18 at 09:40.The student, Sai Kalyan Evani, submitted this Thesis for approval on 2017-07-18 at 09:57.This Thesis was approved for publication on 2017-07-18 at 11:55.DSpace SAF Submission Ingestion Package generated from Vireo submission #11507 on 2018-03-02 at 13:02:23Made available in DSpace on 2018-03-02T19:59:43Z (GMT). No. of bitstreams: 2
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Previous issue date: 2017-07-18Embargo set by: Seth Robbins for item 105069
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Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 105069
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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 105069 on 2020-03-03T10:15:26Z
Analysis of thermal transport in minichannel heat sinks
No full textMany biological systems providing very high heat and mass transfer rates in organs such as brain, liver, and lungs use microchannels and minichannels. A few years back transport in small channels gained ground due to the high heat transfer rates. Since then a lot of research has been done on heat transfer in microchannels both experimentally and numerically. The analysis done minichannels is mainly experimental and very less literature exists on numerical analysis done on heat transfer in minichannels. Some work that exists, considers short channels with aspect ratios in the range of 0.3 to 0.5. Moreover, the work done prior to this work considered considerably lower imposed heat fluxes. The experimental work done on minichannel heat sinks also considers short sinks with heat flux in the order of 40kW/m2. Hence, in this study the focus is on minichannels with an aspect ratio of the order of 0.01 and with very high heat flux imposed, of the order of 700 kW/m2. The analysis is done for three as well as two-dimensional channels. Three different channels of height 1 mm, 2 mm and 3 mm are analyzed and the results of the analysis are studied. The pressure drop across the heat sink is also reported. The temperature drop across the heat sink is reported and found to be minimum for the channel with height 3 mm for a three-dimensional channel.M.S.Includes bibliographical referencesby Kalyan Inamda
Formation and Transformation of Atmospheric Brown Carbon (BrC)
No full textAtmospheric brown carbon (BrC) aerosol absorbs light in the UV-Vis spectrum and has poorly constrained but potentially large climate forcing impacts. Most current climate models lack detailed chemistry and interlinked properties of atmospheric BrC, that induce large uncertainties in radiative forcing predictions. BrC lifecycle and its atmospheric lifespan have not been fully explored. It is suggested that strongly light absorbing primary BrC (PBrC) may rapidly evolve into weakly light absorbing secondary BrC (SBrC) in the atmosphere, which is considered as bleaching of PBrC. Therefore, formation, transformation and optical properties of PBrC from biomass and fossil-fuel combustion system were investigated in lab and field studies. On the other hand, non-absorbing secondary/primary organic aerosol (SOA/POA) evolve into weakly light absorbing SBrC referred as browning of SOA/POA. The chemical processes underlying SOA aging and the subsequent formation and transformation of SBrC are not well understood. The presence of reactive nitrogen, acidity and water is also thought to further drive the chemistry of SBrC evolution and hence contribute to the global radiative forcing budget. These possibilities, and others, were explored in detail and are presented in this PhD thesis.
Biomass is a major source of PBrC emissions, but also it is an important renewable bioenergy source because of its economic and environmental advantages over fossil fuels. The formation of PBrC and its optical properties in a modern Swedish small-scale biomass burner were explored. The measured parameters include gas and particle concentrations, optical absorption and chemical characteristics of gases and particles. Positive matrix factorization (PMF) was performed to analyze data from a HR-ToF-CIMS equipped with FIGAERO and PASS-3. Results from the factor analysis were linked to the optical properties of the emissions, and lignin and cellulose/hemicellulose pyrolysis products were the most important sources of PBrC under the tested burning conditions.
Further, formation of PBrC and its atmospheric transformation was studied at a remote rural site, the Indo-Gangetic Plains – Centre for Air Research and Education (IGP-CARE) in India,in the Indo Gangetic Plain in India where some of the most severe air pollution episodes occur on Earth. The field measurements of short-lived climate pollutants including BrC, black carbon (BC) and ozone (O3) were conducted over a period of one year. In this study, the elevated concentrations of BrC co-emitted BC were identified, which was mostly PBrC and can largely be attributed to the local biomass burning activities in the neighbouring rural communities. This study's most important finding is that the BrC concentration normalized by BC concentration (BrC/BC ratio) showed a very pronounced diurnal variation throughout the year with distinct morning and evening peaks in general and a minimum at around noon time i.e. boat shape pattern of BrC/BC. The profile of the BrC/BC ratio evolved astonishingly during the day-time. An extremely sharp decline in the BrC/BC ratio at the time of dawn each morning indicates the dominance of photochemical processes in the transformation of PBrC. This is hypothesized to be associated with daytime photochemical bleaching of the PBrC and transforming it into SBrC.
PBrC formation and its optical properties were investigated in three distinct premixed fossil-fuelled i.e. propane, flames. POA containing BrC constituted a high fraction (20–40% by mass) of aerosol mass and was predominantly (i.e., 92–97% by mass) internally mixed with soot particles. In these flames, aerosol mixture containing BrC, POA and BC was found to be highly light absorptive, i.e., an Ångström absorption exponent (AAE) value at 405/781 nm > 1.5. The mass absorption cross-section (MAC - 5 m2g-1) of POA containing BrC at 405 nm under a specific flame i.e. fuel-rich setting, was comparable to MACs of BC particles (8–9 m2 g-1).
SBrC formation, transformation and its optical properties were explored under the influence of reactive nitrogen (NOx, NH3)-, acidity (H2SO4)-, and water-mediated chemistry during the photo-oxidation of toluene and subsequent aging of its SOA. The pattern of toluene SOA formation at [NOx]/[ΔHC] molar ratios 0.15 or below was distinctly different (i.e. constant SOA mass) than that was observed at [NOx]/[ ΔHC] ratios higher than 0.15 (i.e. here, SOA mass decreased). These distinguish between SOA formed under nitrogen-poor (NP) conditions i.e. with low initial NOx concentrations, and nitrogen-rich (NR) SOA formed at higher initial NOx concentrations, which has a higher content of compounds such as organo-nitrates. This distinction is valuable for understanding trends in the formation and properties of SOA containing BrC in the presence of varying concentrations of NOx. Hereafter, NP SOA and NR SOA are referred to SOA formed under nitrogen poor and nitrogen rich conditions, respectively. The light absorption coefficient (Babs) and mass absorption cross-section (MAC) of the SOA increased with [NOx/ΔHC] under both the NP and NR regimes. For NP SOA, the MAC increased with [NOx/ΔHC] independently of the relative humidity (RH). However, the MAC of NR SOA was RH-dependent. Under both NP and NR regimes, NH3 and acidity promoted SOA browning. The highest MAC was observed at the lowest RH (20%) for acidic NR SOA, and it was postulated that the MAC of SOA depends mainly on the pH and the [H+]free/[SOA mass] ratio of the aqueous SOA phase.
In the same preceding experiments, I additionally analyzed data from HR-ToF-CIMS. I found that several m/z (i.e. mass to charge ratio of a chemically ionized molecule detected in mass spectrometry) mimicked the trend of observed bulk Babs – against [NOx/ΔHC] increase, of SOA containing BrC. These m/z hereafter termed BrC molecules containing chromophores. An interesting observation was that the key m/z contributing to the Babs were distinct for each experiment. However, we found m/z 296 as a common dominant BrC chromophore (m/z), under several experimental conditions. The RH played a vital role in determining the BrC composition i.e. m/z distribution. The BrC molecules containing chromophores corresponding to various identified m/z are suggested to be nitro-aromatic compounds (NAC), which are primarily formed via OH oxidation of toluene followed by the nitration processing of the oxidized aromatic ring. The suggested key BrC molecules containing chromophores are the nitro-derivatives of the phenols, catechol, benzoic acid, benzaldehyde and benzonitriles
Silicon nanostructure arrays prepared by single step metal assisted chemical etching from single crystal wafer
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