Search

• The computational complexity of the proposed hybrid technique is sub-quadratic. • Minimum spanning tree is used to identify the nearest neighbor of each data points. • The concept of dispersion of data points is used for partitioning the datasets into sub-clusters. • A novel merge index is introduced based on "cohesion" and "intra similarity". • It shows the better performance as compared to popular clustering algorithms. With rapid explosion of information, clustering emerged as an active research area for knowledge discovery. Most of the existing clustering algorithms become ineffective when inappropriate parameters are provided or applied on a dataset which consists of clusters of diverse shapes, sizes, and varying densities. To overcome these issues, many graph based hybrid clustering algorithms have been proposed but these algorithms first generate a complete graph of the dataset which takes O (N 2) time where N is the number of data points which limits their application on large datasets. This paper proposes an algorithm namely a fast hybrid clustering technique based on local nearest neighbor using minimum spanning tree to reduce the computational overhead. In the first step, the algorithm partitions the dataset into large number of sub-clusters based on dispersion of data points to capture the geometry of clusters. After partitioning the dataset, a minimum spanning tree based on the centroids of each of the sub-clusters is constructed to identify the adjacent pairs. A novel merge method is proposed to find the genuine clusters by repeatedly merging the adjacent sub-clusters. The cohesion and intra-similarity are introduced to compute the level of dispersion of data points with respect to the centers of an adjacent pair and average edge weight of a sub-clusters respectively. The algorithm takes O (N 3/2) time which is a N factor improvement over the popular hybrid clustering algorithms. Experimental analyses on both synthetic as well as gene expression datasets demonstrate that the proposed technique shows significant improvement over competing clustering algorithms in terms of execution time and improved cluster quality. Moreover, the proposed algorithm does not require any user defined parameters and it can estimate the number of clusters more accurately. [ABSTRACT FROM AUTHOR]

Studies of behavioral characteristics of fission product aerosols are extremely important in context of suspected environmental release during a severe nuclear reactor accident. Fission product aerosols generated in such a case are expected to travel from coolant systems to the containment and may get released to the environment in the most unlikely scenario of containment breach. Presence of steam also affects their dynamic behaviour and fate. Interaction of aerosol particles with water vapor in subsaturation domain modifies their physical and chemical characteristics. The objective of this study was to examine the hygroscopic nature of nuclear accident relevant cesium bound compounds viz. CsI, CsOH with the use of Hygroscopic Tandem Differential Mobility Analyzer (HTDMA). The growth factors for single component aerosols were obtained for different initial size of particles at different relative humidity levels. Growth factor curves as well as deliquescent parameters for CsI and CsOH particles have been obtained for the first time and have a crucial role towards environmental source term estimations in the event of nuclear accident. Experimental results were also compared with the theories available in literature. • The hygroscopic nature of nuclear reactor accident relevant cesium bound compounds viz. CsI, CsOH has been studied. • First time determination of DRH and ERH of CsI particles. • The experimental results have been compared with the available theoretical models of hygroscopic growth. [ABSTRACT FROM AUTHOR]

Highlights • The major land uses in the Northeast Himalayas are forest and jhum cultivation. • RothC was used to simulate SOC stocks under the baseline and CC conditions. • Simulations indicated that forest could not benefit from CC. • SOC stocks decreased in jhum lands under the baseline and CC. • Jhum cultivation under CC can be extended without large effects on SOC decreases. Abstract Shifting cultivation (jhum) and forest land are the main land uses in North Eastern region of Indian Himalaya, but in the long term this form of agriculture is not acceptable due to the soil degradation following the cutting of forest vegetation, and the consequent biodiversity loss, high erosion rates and nutrient loss through runoff. No information on soil organic carbon (SOC) dynamics and simulation studies are available, so an attempt was done using RothC model. The model was parameterized on measured SOC contents of forest and jhum sites, and average SOC stocks and changes were simulated for a period of 5 years in forest and jhum sites under the baseline and the projected climate change conditions available for Nagaland state (2021–2050). Forest sites under the baseline climate showed a steady-state condition, and simulated SOC decreased by 0.04 t C ha−1 yr−1during 5 years. In addition simulations indicated that forest land use could not benefit from climate change in a 10 years period (SOC changes showed a decreasing trend from 0.36 to 0.06 t C ha−1 yr−1). Jhum sites showed negative changes in SOC stocks both under the baseline (0.40 t C ha−1 yr−1) and the projected climate change conditions (0.50 t C ha−1 yr−1). Indeed, SOC decreases under climate change were inversely related to the duration of the jhum cropping cycle, almost linear in the first five years (from 0.65 to 0.41 t C ha−1 yr−1), and thereafter only slightly decreasing (from 0.39 to 0.32 t C ha−1 yr−1). We can conclude that under climate change conditions the jhum cropping cycle can be extended for a longer period without substantial effects on SOC decreases. [ABSTRACT FROM AUTHOR]

The objective of this work is to study the response of phase calibrated Phase Doppler Particle Analyser (PDPA) in presence of various arrangement schemes of optical materials and thickness of the test section window. The standard "Mono sized droplet generator" (MDG) has been used as a source of mono sized droplets stream. Receiving optics collection angle, Bandpass filter, and Photo-multiplier tube (PMT) voltage has been optimized using a known mono-size droplet stream. The results indicate that maximum perturbation in response occurs in presence of 17.5 mm Plexiglas thickness. The reduction in 97% of data rate is noted in Scheme B, whereas no data has been observed for the case of Scheme D. The maximum data rate reduction of 15.9% is observed in 17.5 mm Plexiglas of Scheme D for aligned PDPA subsystem. The results of the experiment also reveal that when unpolished glass is used instead of Plexiglas, the maximum date rate reduction is 70% for 17.5 mm for Scheme D whereas when subsystems are aligned then maximum loss of data rate is 11.3%, which are significantly higher to losses due to Plexiglas. • Manuscript studies the response of PDPA to optical materials and thickness of test section window. • Photography calibrated MDG has been used in setting parameters of PDPA. • Determination of PDPA response, based on data rate, in presence of different configurations of optical windows thickness and material has been made. [ABSTRACT FROM AUTHOR]

Abstract: Non-catalytic liquefaction of Japanese beech (Fagus crenata) wood in subcritical phenol was investigated using a batch-type reaction vessel. After samples were treated at 160°C/0.9MPa–350°C/4.2MPa for 3–30min, they were fractionated into a phenol-soluble portion and phenol-insoluble residues. These residues were then analyzed for their chemical composition. Based on the obtained data, the kinetics for liquefaction was modeled using first-order reaction rate law. Subsequently, the liquefaction rate constants of the major cell wall components including cellulose, hemicellulose, and lignin were determined. The different kinetic mechanisms were found to exist for lignin and cellulose at two different temperature ranges, lower 160–290°C and higher 310–350°C, whereas for hemicellulose, it was only liquefied in the lower temperature range. Thus, the liquefaction behaviors of these major cell wall components highlighted hemicellulose to be the most susceptible to liquefaction, followed by lignin and cellulose. [Copyright &y& Elsevier]

• Measured SOC stocks in rubber, tea, areca nut, cashew nut and pineapple plantations. • RothC simulation of SOC stocks after conversion from a forest and ACC conditions. • SOC stocks decreased in rubber, areca nut and pineapple (0.65–1.42 Mg C/ha/yr). • Tea and cashew nut (0.23–0.35 Mg C/ha/yr) are the best options to increase SOC stocks. Understanding the impact of land use conversion from forests to plantations on soil organic carbon (SOC) stocks is critical for sustainable land and forest management in Northeast India (NEI). The present study was conducted in West Garo hills district of Meghalaya state in NEI, to evaluate the impact of plantations (rubber, tea, areca nut, cashew nut and pineapple) on SOC stocks in comparison with a natural forest. Soil samples were collected from plantations of different age classes (0–5, 5–10, 10–15, 15–20, 20–25, 25–30, and 30–40 years old) to assess their potential for C storage. RothC model was run at equilibrium on forest land-use, and thereafter was calibrated and validated to model SOC stocks in the plantations over the 40 years chrono-sequence using the baseline average climate data. Results showed that with increase in age of plantations (at 40 years), SOC stocks decreased to 57.4, 50.3 and 44.4 Mg C ha−1 in rubber, areca nut and pineapple plantations at the average rate of 0.41, 0.58 and 0.73 Mg C ha−1 yr−1, respectively. This corresponded to a SOC stock loss of about 22, 32 and 40% compared to the initial SOC stock under forest (73.6 Mg C ha−1). Conversely, SOC stocks in tea and cashew nut plantations increased to 83.4 and 75.4 Mg C ha−1 (at the average rate of 0.24 and 0.05 Mg C ha−1 yr−1), corresponding to a SOC gain of about 13 and 2.5% compared to that under forest over 40 years. The data on abrupt climate change (ACC) scenario by RothC simulations showed that rubber, areca nut, pineapple and forest land uses would lose carbon at the rate of 0.65, 0.65, 1.42 and 0.13 Mg C ha−1 yr−1, respectively. Conversely, tea and cashew nut plantations might gain C at the rate of 0.35 and 0.23 Mg C ha−1 yr−1, respectively, representing a valuableoption for storing C and mitigating and adapting to climate change. Further, protecting and restoring natural forests and/or mixed stands of native tree species might reduce the risks of the loss of biodiversity and be a viable option for sustainable land management in NEI. [ABSTRACT FROM AUTHOR]

Supercapacitor electrodes consist of complex nanoporous structures in carbonaceous and non-carbonaceous materials causing alteration of electric double layer (EDL) structure and response. We develop a modular theory for DC-bias dependent electrochemical impedance spectroscopy (EIS) for EDL in the heterogeneous bimodal porous electrode, viz. arbitrary mesopores with embedded heterogeneous micropores. Theory accounts for the compact- and diffuse-EDL dynamics along with charge transfer kinetics of pseudocapacitance. The influence of applied DC-bias on various phenomenological components is accounted through a heuristic approach. This is achieved by using the potential and concentration dependent diffuse layer thickness for unsymmetrical electrolytes, charge transfer resistance, and electric field dependent dielectric constant. The generic nature of theory is further highlighted by extending it for the composite porous electrode materials. The theoretical response shows that increasing the magnitude of DC-bias enhances the characteristic ion relaxation rates therefore, increases the rate capability of supercapacitors. The electrode morphological parameters, viz. mesopore size, micropore size, micropore length, and the pore surface heterogeneity, can effectively tune the capacitance and charging-discharging rates therefore, influence the performance of supercapacitors. Finally, our theory explains the experimental EIS data for hierarchical sodium gluconate and graphdiyne porous electrodes. Image 1 • EDL-dynamics is analyzed in heterogeneous bimodal porous electrode under DC-bias. • DC-bias effect enhances the EDL-relaxation phenomena in porous electrodes. • Mesopore surface curvature effect on diffuse-EDL relaxation is investigated. • High frequency response depends on mesopore curvature induced diffuse-EDL dynamics. • Phenomenological relaxation times are highlighted in various EIS representations. [ABSTRACT FROM AUTHOR]

This paper discusses the size resolved cloud condensation nuclei (CCN) properties of two cesium bound compounds viz. CsI and CsOH. These properties are important in context of risk analysis and management of probable environmental releases during postulated nuclear reactor accident conditions. If released as fission product aerosols, these particles have potential to act as CCN, when exposed to humid environment. On activation, their evolution-deposition dynamics and consequently fate is expected to be affected in closed and/or open atmosphere. Size resolved CCN efficiency spectra (20–300 nm) are obtained for 0.2–1% supersaturation (SS) for pure CsI and CsOH particles employing a DMT-CCN counter. The essential parameters estimated from these measurements are activation diameter and size-averaged hygroscopicity (κ) at targeted SS levels. Experimental results were also compared with the standard theories available in the literature. Accuracy of the deposition rates for these particles (if released) in reactor component systems estimated by nuclear reactor accident analyses codes will improve when CCN properties are also taken into account. CCN efficiency spectra and activation diameters at specific SS for CsI and CsOH particles are being reported for the first time. Information on these properties strengthen the database which is vital for simulating behavioral characteristics of these particles. This in turn has capability to improve environmental source term estimations in the most unlikely scenario of containment breach during severe reactor accident conditions. • The CCN activity of fission product aerosols (CsI and CsOH) and their effect on size and other properties has been studied. • First time determination of CCN spectra, Activation diameters and Hygroscopicity parameter of CsI and CsOH particles. • The experimental results have been compared with the available theoretical models of CCN properties. [ABSTRACT FROM AUTHOR]

Agricultural and forestry activities can affect soil organic carbon (SOC) levels and CO 2 emissions from terrestrial ecosystems due to land use changes. In Northeast Himalayas, studies on the effects of forest conversion to temporary agricultural lands (jhum) on the loss of SOC and soil quality degradation have received the attention of policy makers and scientific research. Presently, local communities are now oriented towards the settled plantations systems with modern cash crops such as tea and rubber, that could act as potential SOC sinks. However, no information on SOC dynamics and simulation studies after land-use change from temporary agricultural lands (jhum) to settled cultivations and under climate change (CC) conditions are available for the Meghalaya state. Applying the RothC model, we focused on four different scenarios including the conversion from jhum to settled cultivation (rubber plantations and tea gardens), as well as continuous jhum cultivation and jhum to jhum with a period of secondary succession. Simulations under CC conditions indicated that SOC stocks significantly increased by 1.20 t C ha−1 yr−1 in tea gardens compared to rubber and jhum scenarios. Conversely, SOC stocks slightly decreased by 0.07 t C ha−1 yr−1 in rubber plantations, while the regrowth of a natural vegetation cover as secondary succession following the abandonment of the jhum fields, showed a lower SOC decrease (0.18 t C ha−1 yr−1) compared to the continuous jhum cultivation (0.24 t C ha−1 yr−1). Thus, for CC mitigation in a policy perspective, tea gardens could represent the best land use to store increasing amounts of SOC in the long-term perspective and optimize farmers' incomes, while in rubber plantations SOC storage is limited in time. Jhum cultivation can benefit in terms of productivity and profitability by extending the duration of the secondary succession period. Unlabelled Image • We studied jhum cultivations, rubber plantations and tea gardens. • RothC was used to simulate SOC stocks after land use change and CC conditions. • Simulations indicated that in rubber plantations SOC storage is limited in time. • Tea gardens are the best option to increase SOC storage in a long-term perspective. • Jhum cultivation with a secondary succession period can limit SOC decreases. [ABSTRACT FROM AUTHOR]

We developed a phenomenological theory for DC-bias dependent electrochemical impedance response and admittance voltammetry of reversible two-step electron transfer (EE) process at randomly rough and fractal electrodes. The power spectrum of roughness is used to incorporate the statistical information of surface randomness. For the finite fractal model, statistical morphological parameters of roughness, viz., fractal dimension ( D H ), topothesy length ( ℓ τ ) and lower cut-off length (ℓ), significantly influence the admittance response. The magnitude of admittance increases with an increase in the roughness of fractal electrode (e.g. increase in the value of D H or ℓ τ or decrease in ℓ) for both the electron transfer steps. The magnitude of admittance with the variation of DC potential at fixed temporal frequency unravels the multi-electron transfer process. The two step electron transfer process has two characteristic peaks in their plot. The enhanced roughness of electrode increases the height of the admittance peaks and the regions around it (obtained at different fixed frequencies). Our theory is validated with experimental data for the ethyl viologen system at a moderately rough Pt electrode. Finally, our current methodology for admittance voltammetry has the dual advantage of impedance as well as of voltammetry. [ABSTRACT FROM AUTHOR]

Abstract Biomass gasification is a well-studied thermo-chemical conversion route for the generating producer gas, a renewable energy carrier, for thermal and power applications as well as for bio-fuel production. High energy efficiency and clean gaseous fuel with low tar and suspended particulate matters (SPM) contents are some of the major challenges with biomass gasification. Herein, we report non-catalytic high temperature (720–855 °C) gasification of rice husk using fluidized bed gasifier (FBG). Producer gas mainly comprising of CO and H 2 exhibited good higher heating value (HHV) and lower heating value (LHV) of 3.6 and 3.2 MJ/Nm3 respectively. Our experimental observations revealed that 790 °C is the optimum temperature for rice husk gasification with high carbon conversion efficiency (91.6%), thermal efficiency (75%) and high gas yield 2.7 m3/kg. High temperature gasification also resulted into reduced tar + SPM content (0.33 g/Nm3). Rice husk derived producer gas with good heating value and low tar + SPM content can be used as replacement of conventional fossil fuels for thermal applications in many processing industries. Highlights • High temperature gasification (HTG) of rice husk was carried out successfully. • Rice husk gasification, best performed at 790 °C with improved fuel properties. • Producer gas exhibited high heating value (3.6 MJ/Nm3) and good gas yield (2.7 m3/kg). • Higher carbon conversion (92%) and thermal efficiency (75%) was observed. • Tar + SPM in producer gas reduced to 0.33 g/Nm3 under high temperature gasification. [ABSTRACT FROM AUTHOR]

The National Aerosol Facility (NAF) has been built at IIT Kanpur, India for studying the aerosol behavior under simulated severe nuclear reactor accident conditions. Plasma torch aerosol generator (PTAG) has been employed in this facility for generating metal oxide particles with desirable properties. Plasma synthesis closely simulates the particle generation characteristics from degraded core during a postulated severe nuclear reactor accident. This study presents the effect of controlling parameters namely electrical power, carrier gas flow rate and powder feed rate of PTAG on the mass characteristics of synthesized metal oxide particles. The structural and morphological information of the synthesized particles has also been obtained via analysis performed using X-ray diffraction (XRD) method and Transmission electron microscopy (TEM). A set of optimized parameters has been finalized based on the outcome of this study. The study aims to standardize the generator system in order to perform future NAF experiments. [ABSTRACT FROM AUTHOR]

In the event of a nuclear reactor accident, large amount of radioactivity in the form of fission products may get released to the piping assembly of primary heat transport system. These fission products mostly in the form of aerosol particles get deposited on the inner surface of the piping system due to various depositional processes. The removal processes in the complex piping system are controlled to a large extent by the thermal-hydraulic conditions like temperature, pressure and flow rates. These parameters generally vary with time and therefore must be carefully monitored to predict the aerosol behavior in the piping system. Experimental determination of the deposition fraction, interpretation of the role of controlling parameters and development/validation of theoretical models are key areas gaining constant attention among researchers. In the present work, experiments were conducted in a piping assembly consisting of bends and horizontal-vertical orientation at two different carrier gas flow rates. Deposition fractions in the test assembly were estimated and the role of different dynamical processes (thermophoresis, gravitation and bend impaction) was interpreted. The computational fluid dynamics modeling approach is used for theoretical simulation in this work. Aerosol behavior in terms of number concentration, particle size distribution, and particle deposition in the piping system was simulated with the computational fluid dynamics software ANSYS Fluent 16.0 and the results were compared with experimental measurements (wherever applicable). [ABSTRACT FROM AUTHOR]

[Display omitted] • Food waste pretreatment could improve biogas generation. • The parameters and additives determine the digester's efficiency. • The function of the microbial consortium within the digester has been elucidated. • The advantages and designs of various digesters have been explained. In recent years, there has been considerable attention to renewable energy resources for environmental protection to handle and treat food wastes and organic wastes. Anaerobic digestion is a promising option to manage and treat food and organic wastes. Biogas plants will act as energy suppliers and fertilizers to protect our environment. This paper will give an overview of the research achievements and technologies of biogas plants in recent years. This article mainly focuses on characterization, fabrication, and factors that affect biogas production over the years. The major factors like temperature, hydraulic retention time, pH, and organic loading rate will play major roles in production efficiency. Pretreatment technologies and additives inhibition will promote biogas yield., This paper will review different pretreatments and additives followed. There are several microbes found in nature, and these microbes will directly stimulate the action of a particular enzyme to increase efficiency, which can easily reduce the hydraulic retention time. The presence of microbial cultures and bacterial species such as acetomycetes increased methane generation while lowering COD levels. [ABSTRACT FROM AUTHOR]

Studies on severe nuclear reactor accidents consider CsI and CsOH as the two predominant forms of cesium expected to be released following a reactor accident; 137Cs, 134Cs and 131I being their dominant radioactive forms. Recent studies have measured the hygroscopic growth factors (HGF) and activation fractions for laboratory generated CsI and CsOH particles in sub-saturation and super-saturation relative humidity environments. This work measures and compares the HGF of mixed CsI–CsOH particles with those of individual components. The experiments have been performed with hygroscopic tandem differential mobility analyser for varying mass ratios (w/w) of CsI: CsOH and the results have been compared with the theoretical estimates made using Brechtel and Kredneweis (2000) theory in conjugation of ZSR (Zdanovskii–Stokes–Robinson) mixing rule. The study shows different behavioural pattern of hygroscopic growth of mixed particles in comparison to individual components. A clear transitional change in the growth factor patterns was observed for the ratio below 1:1. Additionally, the experiments to study the effect of different dry diameters (50, 100, 150 and 200 nm) for 1:1 ratio revealed that hygroscopic growth was independent of initial dry diameter. Effect of dehydration for 3 mixing ratios viz., 1:02, 1:1 and 1:10 showed continuous pattern indicating the dominance of CsOH. Terminal settling velocities for the mixed and individual particles are compared for highlighting the probable impact on surface deposition flux calculations. The aerosol hygroscopic growth of mixed CsI–CsOH particles has direct implications in improving source term estimates for a severe reactor accident safety analysis. [ABSTRACT FROM AUTHOR]

• Yield trend and soil C status after 32 years of INM in a rice-rice system were studied. • SI, CPI and CMI used for assessing the ability of INM to promote C status in soil. • Azolla contributed maximum to active C pool, whereas rice-stubbles to passive pool. • C sequestration increased in the order FYM < rice-stubbles< Azolla. • Different C fractions in soil were positively and significantly correlated with SYI. Soil carbon (C) is essential in improving the crop productivity and the quality of soils. However, the research reports on enhancing the system productivity and soil C status in the acid Inceptisol of north-eastern region (NER) of India under sustainable integrated nutrient management (INM) are not adequately available. Here, we studied a rice-rice system after 32-year (1987–2020) of continuous INM treatments with farmyard manure (FYM)/ rice stubbles/ Azolla and chemical fertilizer inputs. Yield data were measured yearly to derive the sustainable yield index (SYI) and soil samples were collected during the last three years to assess the different C fractions, C stocks and sequestration and C indexes. The recommended dose of fertilizers (RDF) + rice stubble significantly increased the total yield and the SYI over the unfertilized-control, followed by RDF + FYM and RDF + Azolla. The RDF + Azolla treatment effectively enhanced the very labile and labile C fractions, while RDF + rice stubble contributed to the less labile and non-labile C fractions in soil. The maximum SOC stock was found under RDF + FYM (67.1 Mg ha−1) and RDF + rice stubbles (66.6 Mg ha−1), whereas the lowest in the unfertilized-control (39.1 Mg ha−1). The soil C sequestration followed the same trend ranging between -4.0 and 24.1 Mg ha−1. The water soluble C and microbial biomass C fractions were found to be the most responsive to the different nutrient management practices. The INM treatments showed a higher lability index, C pool index, and C management index. While yield declined in the unfertilized control, the supply of organic and chemical fertilizers sustained rice-rice productivity with an enhancement in soil C status in the long-term. [ABSTRACT FROM AUTHOR]

A Droplet Measurement Technology (DMT) Cloud Condensation Nuclei Counter (CCNC) was deployed to measure cloud condensation nuclei (CCN) for the first time in the pristine Himalayan region at Himalayan Clouds Observatory (HCO), Swami Ram Tirtha (SRT) Campus (30°34′ N, 78°41′ E, 1706 m AMSL), Hemvati Nandan Bahuguna (HNB) Garhwal University, Badshahithaul, Tehri Garhwal, Uttarakhand, India. The CCN concentration (N CCN) was observed at four supersaturation levels (SS: 0.2, 0.5, 0.8, and 1.0%). In this study, we reported CCN concentration at 0.5% SS in different weather conditions from Aug 01, 2018 to Jun 30, 2019. During this observation period, the monthly averaged value of CCN concentration ranged between 1098.3 ± 448.9 cm−3 (mean ± SD) and 3842.9 ± 2512.9 cm−3. It covers a significantly wide range of daily averaged concentrations from the minimum concentration of 43.84 cm−3 (during heavy wet scavenging due to snowfall) to maximum concentration of 17000 cm−3 (during the events of a forest fire) at the observation site. The highest CCN concentration is observed at the time of sunrise (~07:00 a.m.) and after the sunset (~07:00 p.m.) for the diurnal variation of monsoon, post-monsoon, and winter season. Pre-monsoon season shows peak values at 10:00 a.m. and at 07:00 p.m. with higher concentrations at night hours. The possible reasons for maximum concentration in morning and evening time could be upliftment and settlement of CCN because of the convection process, anthropogenic emission, vehicular emission, and biomass burning in the residential area and valley region adjacent to HCO, Badshahithaul. The highest CCN concentration (3842.9 ± 2513 cm−3) values of the whole observation period were observed in May 2019. It was significantly affected by the heavy fire activities over the Uttarakhand and nearby IGP regions. Diurnal variation of CCN concentration during the HFAD shows higher values in the night time differing from the diurnal pattern of CCN for other months of the observation period. The long-range transport of air mass could also contribute to the high CCN concentration values, as found through the five-day air mass backward trajectory analysis. The lowest value of CCN concentration corresponds to the heavy rains and snowfall days, possibly caused by extensive wet scavenging. Cluster analysis of the air mass trajectories used for the allocation and classification of the possible sources of pollutants reaching the observation site. The highest fraction of CCN concentration (more than 2000 cm−3) corresponds to the air mass from the arid and semi-arid regions of Asian countries. Large air mass fraction (~40–60%) with moderate CCN concentration was received from northwestern IGP region and foothills of central Himalaya. • Time series of CCN at four different levels of supersaturation (Superssaturation: 0.2, 0.5, 0.8, and 1.0%), and its role in the macroscopic cloud formation mechanism over the high-altitude region. • Study of seasonal, diurnal, and temporal variation of CCN over the Himalayan regions and comparisons with different altitude sites, geographic and climatic conditions of India. • Observations provided the average CCN concentration 1411.3 ± 1110.1 cm−3, 1645.7 ± 690.62 cm−3, 1712.3 ± 862.8 cm−3, and 2514.7 ± 2166.4 cm−3 for Monsoon, Post- Monsoon, Winter and Pre-monsoon Seasons respectively. • Analysis of local meteorological conditions impact on the formation of high-altitude cloud, and complexity of local weather phenomenon. • Use of transport models to analyze and characterize the possible sources of the pollutant for rural areas with relatively low urbanization and industrialization activities and role transported pollutants from the urban (highly polluted and populated) regions on the modification of local meteorology of the Garhwal Himalayan regions. [ABSTRACT FROM AUTHOR]

• HGF of accumulation mode aerosols at 85% RH reported the first time from India. • Mean HGF_85% 100nm and HGF_85% 150nm were 1.27±0.06 and 1.34±0.07), respectively. • Mean HGF_85% reflected two distinct varitation at LRH≤50% and HRH>50%. • At LRH, HGF_85% correlated linearly (positive) with f44 and effective density. • HGF_85% correlated linearly (inverse) with f44 and effective density at HRH. This study reported results of the wintertime simultaneous measurements of hygroscopic growth factors (HGFs) and particle-phase chemical composition of accumulation mode particles using a self-assembled Hygroscopic Tandem Differential Mobility Analyzer (H-TDMA) and an Aerodyne High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS), respectively at a heavily polluted urban atmosphere of Kanpur, situated in the center of IGP in India. HGFs at 85% relative humidity (RH) and the size-resolved composition of ambient aerosol particles (dry electrical mobility diameters of 100 and 150 nm) were investigated. HGF_85% was found to increase with particle size. The relative mass fraction of organic aerosol (OA) and NH 4 NO 3 are probably the major contributors to the fluctuation of the HGF_85% for both particle sizes. The HGF_85% of accumulation mode particles were observed to increase from the minimum value observed during the morning until its maximum afternoon value. This study reported two maximum (early morning and afternoon time) and two minimum values (morning and evening time) of HGF_85%s. As a consequence, the main reasons for this incremental behavior were, increase in the ratio of inorganic to OA and oxidation level, f44 (m/z44/OA) of the OA within the particle phase. In context to the effect of ambient RH, this study reported two distinct variations of mean HGF_85% as the function of ambient RH. The positive linear relationship at low RH (LRH, RH ≤ 50%) was clearly associated with low OA loading, relatively higher substantial temperature, and wind speed. We also observed increment in f44, and effective density indicating aging of aerosol. However, HGF_85% was found to inversely decline as a function of RH at higher RH (HRH, RH > 50%) conditions, which clearly reflect the more significant contribution of primary OA and lower oxidation level of OA. Our results show the declining trend in size-resolved effective density at HRH conditions, confirming the above conclusions. [ABSTRACT FROM AUTHOR]