124 research outputs found
Author Correction Large spontaneous exchange bias in a weak ferromagnet Pb 6 Ni 9 (TeO 6 ) 5 (Scientific Reports, (2017), 7, 1, (8300), 10.1038/s41598-017-09056-w)
No full textIn the original version of this Article, Binoy Krishna Hazra and S. Srinath were incorrectly affiliated with ‘Department of Physics, Indian Institute of Technology Tirupati, TIRUPATI, 517506, India’. The correct affiliation is listed below School of Physics, University of Hyderabad, Hyderabad, 500046, India This error has now been corrected in the PDF and HTML versions of the Article, and in the accompanying Supplementary Information file. © 2019, The Author(s)
The role of carbon dioxide during the onset of Antarctic glaciation
No full textEarth’s modern climate, characterized by polar ice sheets and large equator-to-pole temperature gradients, is rooted in environmental changes that promoted Antarctic glaciation ~33.7 million years ago. Onset of Antarctic glaciation reflects a critical tipping point for Earth’s climate and provides a framework for investigating the role of atmospheric carbon dioxide (CO2) during major climatic change. Previously published records of alkenone-based CO2 from high- and low-latitude ocean localities suggested that CO2 increased during glaciation, in contradiction to theory. Here, we further investigate alkenone records and demonstrate that Antarctic and subantarctic data overestimate atmospheric CO2 levels, biasing long-term trends. Our results show that CO2 declined before and during Antarctic glaciation and support a substantial CO2 decrease as the primary agent forcing Antarctic glaciation, consistent with model-derived CO2 thresholds
Experimental characterisation of large scale structures in a high Reynolds number turbulent boundary layer
No full textA very large field of view (4δ x 1δ) with a good spatial resolution owing to the use of four 2k x 2k pixel cameras was conducted in a flat plate boundary layer at two Reynolds numbers (Reθ ≈7,500 and 20,000). Comparing the flow statistics with previously obtained hot-wire data under similar flow conditions show good agreement. The goal of this experiment is to detect and characterise the large scale motions which develop in the log region of a high Reynolds number turbulent boundary layer
Many Worlds on a Frame: Characterizing Online Social Cognition
No full textAbstract :
The theme of the Web Observatory at IIIT Bangalore is "online social cognition." Our research aims to understand how social media activity molds collective worldview that in turn impacts several areas of human activity, like business, politics or even social harmony. We first categorize the web into three broad regions or realms: called the social, trigger, and inert realms respectively. The social realm forms the participatory areas of the web, where opinions are actively exchanged and molded. Trigger realm refers to elements like news websites or blogs, whose publishing events often trigger activity in the social realm. The inert realm refers to static web content, that gets used as a source of latent knowledge in the social interactions.
The social realm itself is modeled as a "marketplace of opinions" -- where different vested interests invest their opinions in order to fetch returns. Opinions that are "compatible" come together to form one or more narratives. In order to characterize this, we first represent an opinion as comprising of two dimensions called: abstraction and expression. Abstraction refers to the opinion-holder's objective perspective on the issue, and expression refers to the communication of the opinion-holder's subjective sentiment about the issue. Cognitive science studies show that abstractions and expressions have vastly different characteristics in they way they diffuse through a population. Hence, the formation of narratives are sometimes catalyzed by abstractions, and sometimes by expressions.
In order to represent narratives and their interplay, that constitutes social cognition, we also propose a hermeneutic framework called "Many Worlds on a Frame" (MWF). The framework models the semantic universe of discourse, as comprising of several semantic "worlds" or "narratives" within each of which , other worlds may participate as entities. Interactions between worlds are either facilitated or hampered by their respective worldviews. The set of all interactions between worlds is called the Frame.
We argue that the "many worlds" representation is more conducive to modeling social cognition, rather than (say) a convergent multi-author knowledge model like a wiki. The MWF implementation does not impose an overarching ontology, at the same time, it is not completely unstructured either. We propose to use a modified form of the NQuad W3C standard for representing knowledge about online social cognition.
About the Speaker :
Srinath Srinivasa heads the Web Science lab and is the Dean (R&D) at IIIT Bangalore, India. Srinath holds a Ph.D (magna cum laude) from the Berlin Brandenburg Graduate School for Distributed Information Systems (GkVI) Germany, an M.S. (by Research) from IIT-Madras and B.E. in Computer Science and Engineering from The National Institute of Engineering (NIE) Mysore. He works in the area of Web Science, understanding the impact of the web on humanity. Technology for educational outreach and social empowerment has been a primary motivation driving his research. He has participated in several initiatives for technology enhanced education including the VTU Edusat program, The National Programme for Technology Enhanced Learning (NPTEL) and an educational outreach program in collaboration with Upgrad. He is a member of various technical and organizational committees for international conferences like International Conference on Weblogs and Social Media (ICWSM), ACM Hypertext, COMAD/CoDS, ODBASE, etc. He is also a life member of the Computer Society of India (CSI). As part of academic community outreach, Srinath has served on the Board of Studies of Goa University and as a member of the Academic Council of the National Institute of Engineering, Mysore. He has served as a technical reviewer for various journals like the VLDB journal, IEEE Transactions on Knowledge and Data Engineering, and IEEE Transactions on Cloud Computing. He is also the recipient of various national and international grants for his research activities
Power Quality Enhancement in Sensitive Local Distribution Grid Using Interval Type-II Fuzzy Logic Controlled DSTATCOM
No full textIn the current scenario, integration of renewables, growth of non-linear industrial and commercial loads results in various power quality issues. Among commercial utilities connected to the grid, hospital-operated loads include sensitive, linear, non-linear, and unbalanced loads. These loads are diverse as well as prioritized, which also causes major power quality issues in the local distribution system. Due to its widespread divergence, it leads to harmonic injection and reactive power imbalance. Distribution Static Compensator (DSTATCOM) is proposed as a solution for harmonic mitigation, load balancing, reactive power imbalances, and neutral current compensation. The present work utilizes Interval Type-2 Fuzzy Logic Controller (IT2FLC) with Recursive Least Square (RLS) filter for generating switching pulses for IGBT switches in the DSTATCOM to improve power quality in the Local Distribution Grid. The proposed approach also shows superior performance over Type 1 fuzzy logic controller and Conventional PI controller in mitigating harmonics. For effective realization, the proposed system is simulated using MATLAB software
Enhanced terrestrial carbon export from East Antarctica during the early Eocene
No full textTerrestrial organic carbon (TerrOC) acts as an important CO2 sink when transported via rivers to the ocean and sequestered in coastal marine sediments. This mechanism might help to modulate atmospheric CO2 levels over short- and long timescales (103 to 106 years), but its importance during past warm climates remains unknown. Here we use terrestrial biomarkers preserved in coastal marine sediment samples from Wilkes Land, East Antarctica (~67°S) to quantify TerrOC burial during the early Eocene (~54.4 to 51.5 Ma). Terrestrial biomarker distributions indicate the delivery of plant-, soil- and peat-derived organic carbon (OC) into the marine realm. Mass accumulation rates of plant- (long-chain n-alkane) and soil-derived (hopane) biomarkers dramatically increase between the earliest Eocene (~54 Ma) and the early Eocene Climatic Optimum (EECO; ~53 Ma). This coincides with increased OC mass accumulation rates and indicates enhanced TerrOC burial during the EECO. Leaf wax δ 2H values indicate that the EECO was characterised by wetter conditions relative to the earliest Eocene, suggesting that hydroclimate exerts a first-order control on TerrOC export. Our results indicate that TerrOC burial in coastal marine sediments UOB Open could have acted as an important negative feedback mechanism during the early Eocene, but also during other warm climate intervals
Modeling Study of Dry Deposition of Ammonia in North Carolina.
No full textProper description of removal processes for ammonia is essential in an air quality modeling system to accurately represent the ammonia and nitrogen budget. This problem is significant in Southeast U.S., both politically and environmentally in North Carolina (NC) due to increased odor, ammonia (NH3), and other emissions from hog and livestock sources. The transport and fate of NH3 are affected by various atmospheric processes and parameters such as meteorological variables, chemical reactions, and dry and wet deposition. Meteorological parameters such as temperature, humidity, and wind fields are very important in any air quality study as they directly affect the transport and chemistry of species of concern such as ozone (O3) and NH3. Input of accurate meteorological variables is vital for accurate simulations of ambient air quality. Dry deposition refers to the downward transport of gaseous and particulate species from the atmosphere onto surfaces in the absence of precipitation/hydrometeors. Direct measurements of individual parameters such as friction velocity, leaf area index, and stomatal resistance that are used in dry deposition calculations are generally lacking. This limits our understanding of the important physical, chemical, and biological processes involved in dry deposition and the evaluation of the accuracy of the model in replicating them.
The objectives of the proposed research are as follows:
Evaluate dry deposition predictions from the MM5⁄CMAQ modeling system
Identify influential parameters for the calculation of dry deposition of ammonia
Improve dry deposition parameterizations in the MM5⁄CMAQ modeling system
The approach undertaken to achieve these objectives is divided into three steps. A box model is first used to conduct sensitivity tests for summer and winter conditions to identify the role played by several parameters in the calculation of dry deposition. Parameters considered are leaf area index (LAI), surface roughness length (SRL), surface relative humidity (RHs), cuticle resistance (rcutmax), and canopy wetness content (CWC). The number of test simulations performed are 3 (site locations) * 10 (RHs) * 11 (CWC) * 5 (LAI) * 5 (SRL) * 2 (rcutmax). Results indicate the importance of proper specification of RHs, LAI, and surface roughness length. Box model results justify the use of a categorization scheme to parameterize CWC, which is currently treated as 0 or 1.
Then, a 3-D meteorological model (i.e., Penn State University /National Center for Atmospheric Research (PSU⁄NCAR) mesoscale model, known as MM5, model (v. 3.7)) is then used to evaluate the impact of grid resolution and nudging on meteorological predictions. Overall, the differences between model results with and without nudging scheme are relatively small (up to 3% in terms of normalized mean biases (NMB)). When the domain was divided into specific regions such as rural, urban, and coastal based on scale of development and location, the differences between the simulations were found to be much higher. Using a finer grid resolution with nudging generally provides the best overall results during summer. Although differences in the overall domain are relatively small (e.g., up to 3% in terms of NMBs), the differences in area-specific analyses may be higher (e.g., up to 30% in NMB for WSP). Based on sensitivity evaluations in the box and meteorological models, the effects of grid resolution, nudging, and changes in dry deposition parameterizations are studied in a 3-D air quality model (i.e., CMAQ).
The chemistry transport model (i.e., U.S. EPA Models-3 Community Multiscale Air Quality (CMAQ) model) is used to analyze the impact of both meteorology and dry deposition parameterization changes (from the box model study) on a 3-D model. Impacts of meteorology and dry deposition on the air quality model are evident. For July, underpredictions in SO42- (NMBs of -17.6%, -31.3%, and -32.1% for the baseline, modified rcutmax, and modified CWC simulations, respectively) and NH4+ (NMBs of -29.7%, -46.3%, and -46.1% for the base, modified rcutmax, and modified CWC simulations, respectively) are greater in both the sensitivity simulations, while NO3- values do not vary significantly (NMBs of -87.5%, -87.4%, -87.6% for the base, modified rcutmax, and modified CWC simulations, respectively). Ammonia deposition velocities and fluxes are compared to observational data obtained from Phillips et al. (2004) for summer (July and August) and winter (December), 2002. The 12-km simulation predicts higher values than the 4-km simulation other than for nighttime winter. In the base case during both summer and winter, NH3 Vd was underestimated during daytime and overestimated at nighttime. With modified maximum cuticle resistance coefficient the deposition velocity increased for day and night. With modified canopy wetness contents, the increase in day and night Vd was slightly lower.
Improved understanding and representation of dry deposition process in the modeling system would aid in maintaining a total-N2 budget and establishing regulatory standards for NH3 emissions for North Carolina
Integrated fish farming
No full textThe basic principle of integrated fish farming is the
effective utilization of the wealth of water as well as land
through adoption of carefully planned production methods with
the least amount of wastage. In this farming system through
an appropriate and balanced combination of dairy, piggery,
poultry, duckery and horticulture with fish farming, it is
possible to obtain high production combined with high profits
through the integrated use of land and water. The fertility
of the water-body is enhanced through the use of organic
manures
Techno-Economic Analysis of Autotrophic Microalgae for Biofuel Production in India
No full textModern society relies on non-renewable sources of energy which is the dominant source of energy, which accounts for nearly 84% of the overall increase in demand between 2005 and 2030 (Khan et al., 2009). The energy requirements are estimated to grow by 55% between 2005 and 2030, according to The International Energy Agency (2011). There is an increased demand for transportation of industrial and agricultural goods in India and more than three-quarters of the petroleum demands are met through imports (Khan et al., 2009). Exhaustion of the global petroleum reserve combined with the growing concern about environmental quality, particularly climate change has increased the search for alternate sources of energy.
With the rapid increases in fossil fuel prices combined with the need for sustainable alternatives has brought microalgae as a source of biofuel back into the research and development (R&D) limelight. Microalgae as a feedstock for biofuel production are attractive as it is a source of clean and renewable energy. Unlike first generation crops, algae do not come into conflict with the food supply. The process of producing biodiesel from carbon neutral biomass can contribute significantly to the development of the rural economy by providing a non-polluting, biodegradable and safe environment (Khan et al., 2009).
However, there are certain technical and economic challenges associated with the microalgae biofuel industry that limits the widespread use of this technology despite several efforts that have been made to solve these problems over the past several decades. For algae biofuels to substitute the fossil fuel industry and ensure sustainable and efficient energy production, distribution and use, a whole new set of technology-related materials and infrastructure needs to be set up to ensure that post-harvest losses are minimized with increased sustainability. The combination of generating energy from wastewater treatment along with a sustainable nutrient cycling addresses the reduction in greenhouse gas emission and the production of biofuels with long term sustainability. Providing long-term targets and supporting policies that stimulate investment in the production of algae biofuels can improve the economic situation. The main focus of this paper is to identify the challenges related to the sustainable production and commercialization of microalgae biofuel
Socio-demographic patterning of physical activity across migrant groups in India: results from the Indian Migration Study.
No full textOBJECTIVE: To investigate the relationship between rural to urban migration and physical activity (PA) in India. METHODS: 6,447 (42% women) participants comprising 2077 rural, 2,094 migrants and 2,276 urban were recruited. Total activity (MET hr/day), activity intensity (min/day), PA Level (PAL) television viewing and sleeping (min/day) were estimated and associations with migrant status examined, adjusting for the sib-pair design, age, site, occupation, education, and socio-economic position (SEP). RESULTS: Total activity was highest in rural men whereas migrant and urban men had broadly similar activity levels (p<0.001). Women showed similar patterns, but slightly lower levels of total activity. Sedentary behaviour and television viewing were lower in rural residents and similar in migrant and urban groups. Sleep duration was highest in the rural group and lowest in urban non-migrants. Migrant men had considerably lower odds of being in the highest quartile of total activity than rural men, a finding that persisted after adjustment for age, SEP and education (OR 0.53, 95% CI 0.37, 0.74). For women, odds ratios attenuated and associations were removed after adjusting for age, SEP and education. CONCLUSION: Our findings suggest that migrants have already acquired PA levels that closely resemble long-term urban residents. Effective public health interventions to increase PA are needed
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