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Sensible heat storage performances of Hytherm 600 oil and energy-harnessing features of glycol-water mixture under simultaneous charging and discharging conditions
No full textA sensible thermal energy storage (TES) system is studied using Hytherm 600 oil as the storage medium and a 30:70 ethylene glycol–water (EG-W) mixture as the discharging fluid, owing to its extended operating temperature range (−14 °C to 105 °C) at atmospheric pressure. The EG-W mixture alleviates the working limitations of pure water by lowering the freezing point and elevating the boiling point, making it suitable for solar thermal systems in colder climates and for low-temperature industrial heat recovery without pressurized systems. An immersed helical coil-aided cylindrical TES tank is used in the experimental setup. The charging-alone and SCAD modes are investigated for different oil-side charging temperatures (60, 75, 90 °C) and discharging flow rates (0.5, 1.25, and 2 L/min). A three-dimensional numerical model is developed, incorporating temperature-dependent thermophysical properties for both fluids. This helped capture the stratification characteristics and thermocline behaviour accurately. Case C1 (charging temperature of 90 °C; charging and discharging flow rates of 0.5 L/min) exhibited the highest thermal energy accumulation of 38,500.1 kJ within the TES tank due to low energy extraction, while Case C3 (charging temperature of 90 °C; charging flow rate of 1.25 L/min, discharging flow rate of 2 L/min) demonstrated increased heat extraction (890 kJ). Case A2 (charging temperature of 60 °C; charging flow rate of 0.5 L/min; discharging flow rate of 2 L/min) exhibited the highest sustained efficiency of 0.26–0.27 in the later stages of SCAD operation. Entropy generation increased notably during SCAD operations due to enhanced thermal mixing. Case C2 (charging temperature of 90 °C; charging flow rate of 0.5 L/min; discharging flow rate of 1.25 L/min) exhibited the highest cumulative entropy generation of 52.49 kJ/kg·K, and Case A1 (charging temperature of 60 °C, charging and discharging flow rates of 0.5 L/min) showed the lowest entropy generation (37.49 kJ/kg·K). The analyses establish that higher charging temperatures strongly promote stratification, effectively countering the mixing induced by higher discharge rates. These insights establish a crucial foundation for configuring effective TES systems with non-conventional discharging fluids for various low-temperature applications
Causal Discovery and Classification Using Lempel–Ziv Complexity
Get PDFInferring causal relationships in the decision-making processes of machine learning models is essential for advancing explainable artificial intelligence. In this work, we propose a novel causality measure and a distance metric derived from Lempel–Ziv (LZ) complexity. We explore how these measures can be integrated into decision tree classifiers by enabling splits based on features that cause the most changes in the target variable. Specifically, we design (i) a causality-based decision tree, where feature selection is driven by the LZ-based causal score; (ii) a distance-based decision tree, using LZ-based distance measure. We compare these models against traditional decision trees constructed using Gini impurity and Shannon entropy as splitting criteria. While all models show comparable classification performance on standard datasets, the causality-based decision tree significantly outperforms all others on the Coupled Auto Regressive (AR) dataset, which is known to exhibit an underlying causal structure. This result highlights the advantage of incorporating causal information in settings where such a structure exists. Furthermore, based on the features selected in the LZ causality-based tree, we define a causal strength score for each input variable, enabling interpretable insights into the most influential causes of the observed outcomes. This makes our approach a promising step toward interpretable and causally grounded decision-making in AI systems
Predicting stock prices using permutation decision trees and strategic trailing
No full textIn this paper, we explore the application of Permutation Decision Trees (PDT) and strategic trailing for predicting stock market movements and executing profitable trades in the Indian stock market. We focus on high-frequency data using 5-minute candlesticks for the top 50 stocks listed in the NIFTY 50 index and Forex pairs such as XAUUSD and EURUSD. We implement a trading strategy that aims to buy stocks at lower prices and sell them at higher prices, capitalizing on short-term market fluctuations. Due to regulatory constraints in India, short selling is not considered in our strategy. The model incorporates various technical indicators and employs hyperparameters such as the trailing stop-loss value and support thresholds to manage risk effectively. We trained and tested data on a 3 month dataset provided by Yahoo Finance. Our bot based on Permutation Decision Tree achieved a profit of 1.1802% over the testing period, where as a bot based on LSTM gave a return of 0.557% over the testing period and a bot based on RNN gave a return of 0.5896% over the testing period. All of the bots outperform the buy-and-hold strategy, which resulted in a loss of 2.29%
Personalized Theta Transcranial Alternating Current Stimulation and Gamma Transcranial Alternating Current Stimulation Bring Differential Neuromodulatory Effects on the Resting Electroencephalogram: Characterizing the Temporal, Spatial, and Spectral Dimensions of Transcranial Alternating Current Stimulation
No full textCrafting new service workers: skill training, migration and employment in Bengaluru, India
No full textNottusvara: A Pedagogical Tool
No full textNōṭṭusvara are a novel compositional form in Carnatic classical music that emerged in the colonial period in south India, where vernacular lyrics were set to the popular Celtic/Baroque melodies. Muttuswāmi Dīkṣitar is attributed for the creation of the genre of Nōṭṭusvara. The present study questions the very intent of the conception of these specific compositions by Dīkṣitar, and explores beyond the conventional idea of him composing these pieces due to his exposure to the band music in Madras.
Citing personal interviews, indepth archival findings and referencing existing literature, the author provides corroborative evidence to suggest that the objective behind the creation of Nōṭṭusvara perhaps was to aid his brother Bāluswāmi Dīkṣitar, the basics of playing the violin. Once the basics were learnt, the brother could replicate complex Carnatic compositions on the violin. This article explores the possibility that Nōṭṭusvara compositions were a pedagogical tool used for the facilitation of the violin in the Carnatic music milieu
Evaluating the impact of agrometeorological advisory services on crop yields using propensity score matching method in Karnataka's rainfed regions
Get PDFThe impact of Agrometeorological Advisory Services (AAS) on agricultural productivity in four districts in the northern part of the state of Karnataka in India is assessed in this paper. We particularly focus on the role of District Agrometeorological Units (DAMUs) prior to their discontinuation in 2024. The study examines the correlation between access to AAS and crop yields for four major Kharif crops, viz., pigeon pea, pearl millet, maize, and jowar, using the Propensity Score Matching (PSM) method
In search of consensus: Examining Global South perspectives on climate security in UNSC debates
No full textThis article aims to fill a critical gap in literature by examining the evolving perspectives of Global South countries (often framed as a monolithic entity), within the United Nations Security Council (UNSC) debates on climate security from 2007 to 2023. Using discourse analysis, the study traces how internal divergences and convergences among these countries shape their positions on two key questions: the acknowledgment of climate change as a security issue and the endorsement of the UNSC’s role in addressing it. A key finding of this analysis is that while there is a growing consensus within the Global South that climate change poses significant security risks, there remains substantial resistance to UNSC involvement in addressing these risks. The article concludes that the Global South, as a category, may have limited utility in understanding the role of the UNSC in climate security. Instead, smaller, more focused coalitions like Small Island Developing States (SIDS) offer a more coherent and meaningful framework for understanding how states approach climate security
