1,721,724 research outputs found
Path Dependent Battery Degradation Dataset Part 1: Investigation of Path Dependent Degradation in Lithium-Ion Batteries : Degradation Dataset, T. Raj, D. A. Howey
Get PDFModels that predict battery lifetime require knowledge of the causes of degradation and operating conditions that accelerate it. Batteries experience two aging modes: calendar aging at rest and cyclic aging during the passage of current. Existing empirical aging models treat these as independent, but degradation may be sensitive to their order and periodicity – a phenomenon that has been called ‘path dependence’. This long-term dataset was collected to study the influence of path dependence in commercially available lithium-ion 18650 cells with nickel cobalt aluminium oxide (NCA) positive electrodes and graphite negative electrodes. Four groups of 3 cells each were subjected to combined load profiles comprising fixed periods of calendar and cyclic aging applied in various orders. Cells in groups 1 and 2 were exposed to one day of cycling followed by five days of calendar aging at C/2 and C/4 respectively. Cells in groups 3 and 4 were exposed to two days of cycling followed by ten days of calendar aging at C/2 and C/4 respectively. The data collected while the cells were exposed to the combined profiles as well as the reference performance tests and electrochemical impedence spectroscopy data is included in this dataset. Further information is available in the readme.txt file
TRISHNA In-orbit Radiometric Calibration
Get PDFTRISHNA is an Indian-French cooperative mission to be launched in 2025. Its principal focus will be on evapo-transpiration, ecosystem stress, and coastal oceans sea surface temperature. The satellite will host two payloads: one instrument in the VSWIR range – 7 bands from 485 to 1600 nm under ISRO’s responsibility, and one instrument in the TIR range – 4 bands from 8.5 to 11.5 μm. The resolution of both instruments is 57m at nadir and their swath is about 1000 km. TRISHNA’s TIR and VSWIR instruments will be extensively calibrated and characterized in on-ground facilities to ensure that their performance will meet the specifications throughout TRISHNA’s lifetime. Yet, the operation in space after the launch and during several years can lead to different behaviors as the ones expected from ground calibration, justifying a validation and if necessary a calibration of some parameters of the ground processing. The TRISHNA TIR instrument radiometric performances rely on an on-board calibration device (blackbody) and cold space viewing. Some so-called vicarious calibration methods are being developed in the TIR using natural targets in order to validate and monitor the calibration performed using the blackbody, and to potentially be used as a backup in case of hardware failure. These natural targets include the oceans, the Moon, snow deserts in Antarctica or Greenland and instrumented sites. The TRISHNA VSWIR instrument on the other hand will not benefit from an on-board calibration and will exclusively rely on vicarious calibration. CNES has experience in vicarious calibration in the VSWIR and will use some methods which have been already proven for other sensors (Rayleigh scattering, deserts, clouds, Moon and instrumented sites). The presentation will focus on the description of the radiometric calibration strategy and the associated methods
What can you learn from an undergraduate research internship?
No full textIn summer 2016, the Department of Government ran its research internship scheme for undergraduates for the second year. The programme enables BSc students to develop key skills by working with academic faculty on their research. We spoke to BSc student Trishna Kurian and Associate Professor Joachim Wehner about the internship scheme and their work on a project about voting behaviour in South African local elections
Review on Trishna Vegadharana w.s.r. to Badhirya
Get PDFAyurveda is the ancient system of medicine which details about various concepts about maintaining the health of a healthy people and curing the disease of affected. Adhaaraneeya Vega (suppressing natural urges) is such a concept which explained as the common cause for many health related issues. Among them Badhirya (deafness) is explained as a complication of suppression of urge of Thirst (Trishna Vega Dharana). There for this review article attempt to explain Trishnsa Vegadharana with reference to Badhirya
The Link between Udakavaha Srotas and Trishna Roga: A Comprehensive Study
Get PDFAccording to Ayurveda, "Srotas" are passageways that help materials move throughout the body. These passageways are necessary for carrying nutrients, waste products, and other key components that keep physiological functions functioning Udakavaha Srotas specifically manages water transportation and regulation, playing a crucial role in hydration and fluid balance. These channels, rooted in the Talu (hard palate) and Kloma (possibly the right lung), can dysfunction due to dietary, emotional, and lifestyle factors, leading to symptoms like mouth dryness and persistent thirst. This dysfunction is linked to the imbalance of Vata and Pitta Doshas. Trishna Roga, characterized by excessive thirst, is closely associated with Udakavaha Srotas vitiation. The severity of Trishna Roga correlates with the extent of disruption in these water-carrying channels. Understanding Udakavaha Srotas is vital for comprehending the pathogenesis and treatment of Trishna Roga, highlighting the importance of maintaining these channels for overall health and wellness in Ayurvedic practice
Optimizing TRISHNA TIR channels configuration for improved land surface temperature and emissivity measurements
No full textInternational audienceIn preparation of the Thermal infraRed Imaging Satellite for High-resolution Natural resource Assessment (TRISHNA) mission, we conducted a thorough analysis of sensitivity for the Temperature-Emissivity Separation (TES) method to the position of the four TRISHNA spectral channels, notably to find an optimal spectral configuration. To that purpose, we designed a fast-computing end-to-end simulator including several components, which we implemented to simulate both pixel-size TRISHNA measurements and land surface temperature (LST) retrievals. Firstly, simulations were conducted over a wide range of realistic scenarii, notably by including vegetation canopy-scale cavity effect. Secondly, the experimental design included the features of second generation Mercury-Cadmium-Telluride (MCT) cooled detectors with lower instrumental noises and finer channels. Thirdly, as opposed to previous studies that used predefined spectral configurations to determine the most suited one, we conducted an optimization of the spectral configuration by crossing, on a pair basis, several positions of the four TIR channels over a range of wavelengths. Fourthly, we quantified the TES sensitivity to atmospheric perturbations, by comparing LST retrievals with and without atmospheric noise.We observed an overall moderate sensitivity of TES LST retrievals to the spectral channel positions, with a maximum RMSE variation of 0.31 K within the atmospheric spectral windows. Furthermore, the TES method was sensitive to three main parameters, namely the instrumental noise, the atmospheric downwelling irradiance, and the transmittance due to ozone and water vapor, with RMSEs larger than 1 K for specific channel locations. Moreover, by considering possible superimposition of two channels, we noted that the TES method could achieve similar performance by considering three or four channels. Eventually, our study enabled us to recommend a new spectral configuration for the TRISHNA TIR instrument, that is more robust to atmospheric perturbations and to uncertainties on channel positions and bandwidths
Indo-French High-resolution Thermal Infrared Space Mission for Earth Natural Resources Assessment and Monitoring -Concept and Definition of TRISHNA
No full textInternational audienceThe Indian and French Space Agencies, ISRO and CNES, have conceptualized a space-borne Thermal Infrared Reflectance (TIR) mission, TRISHNA (Thermal infRared Imaging Satellite for High-resolution Natural Resource Assessment). The primary design drivers of TRISHNA are the monitoring of (i) terrestrial water stress and use, and of (ii) coastal and continental water. A suit of four TIR bands and six optical bands is planned. The TIR bands will be centred at 8.6μm, 9.1μm, 10.3μm and 11.5μm to provide noon-night global observations at 57m nadir resolution over land and coastal regions. The field of view (FOV) is 34 and the orbit of 761 km altitude was designed to allow 3 sub-cycle acquisitions during the 8-day cycle. The optical bands correspond to blue, green, red, and NIR plus two SWIR bands at 1.38μm and 1.61μm. The green, red, NIR and the 1.61μm SWIR bands will have better radiometry quality than those of AWiFS. ISRO and CNES will develop optical and TIR payloads, respectively. Assessing evapotranspiration and furthermore Gross and Net Primary Productivity (GPP and NPP) will in turn assist in quantifying water use in rainfed and irrigated agriculture, water stress and water use efficiency, with expected applications to agricultural drought and early warning, crop yield prediction, water allocation, implementation of water rights, crop insurance business and agro-advisories to farmers. The other scientific objectives of TRISHNA are also briefly described. TRISHNA instrument will fly aboard a ISRO spacecraft scheduled to be launched from 2024 for a minimum period of 5 years' mission lifetime
Land Surface Temperature Retrieval over Urban areas from simulated TRISHNA data
No full textInternational audienceThe future space joint-mission TRISHNA (Thermal infraRed Imaging Satellite for High-resolution Natural resource Assessment, CNES and ISRO) will allow to retrieve LST at 60 m spatial resolution every 3 days, improving the urban environment monitoring capacities. Two methods can be used to derive LST from remote sensing TIR data, Split-Window (SW) or TES (Temperature Emissivity Separation). Even if proven efficient, the complexity and heterogeneity of urban areas limit the performance of those methods. This paper focuses on the TES algorithm. For TES, errors can be generated by the impact of the surface roughness on the data. In order to investigate the efficiency of the future TRISHNA mission, research was conducted to evaluate the TES algorithm. To do so, the impacts of using a representative material database when using TES were explored and validated based on airborne or satellite data, and the impact of the surface geometry on the TES estimations was evaluated using 3D thermo-radiative model simulations. This study shows that TES can be used for TRISHNA images with a mean difference of 1.6 K between validation measurements and the retrieved LST for both daytime and nighttime images and that neglecting the impact of the surface geometry while performing TES could lead to errors up to 4 degrees C in LST estimations
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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