Advancements in data availability, including high frequency, near real-time multiparameter sensors, laboratory analysis, and in-situ and remote observations, have driven the development of machine ...learning (ML) models for applications such as toxic Harmful Algal Bloom (HABs) monitoring. However, the performance of ML predictions is influenced by both model uncertainties due to inherent model structures and errors associated with input dataset measurements. For example, measurement uncertainty arises from sample collection, sensor drift and laboratory analysis and sample handling errors. While impacts of model uncertainty are commonly addressed using probabilistic approaches, the effect of measurement uncertainty is less studied due to the limited availability of detailed measurement information. This study focuses on assessing the impact of measurement uncertainty on the ML prediction of chlorophyll-a concentration as an index of HABs in a mesotrophic lake. Using randomized subsets of input measured datasets that mimic possible chlorophyll-a concentration distributions, the study built 1000 Random Forest (RF) and Support Vector Regression (SVR) models. An independent measured dataset was used to validate the ensemble models, allowing for model performance evaluation and the creation of prediction intervals to measure the propagated uncertainty. Our findings showed that the model predictions have MAE that ranged between 0.16 μg/l and 5.19 μg/l, and RMSE ranging between 0.20 μg/l and 7.39 μg/l. The highest uncertainty coverage of 0.71 was observed in the RF model without chlorophyll-a sensor values as a predictor. The study found that the training dataset sizes due to the high frequency and manually sampled nature influence how much measurement uncertainty is covered. The results of this study demonstrate how well ML models can capture various HABs patterns when given diverse measurement variables. Our findings will give researchers insightful information on how to lessen the impact of measurement uncertainty when using ML models as decision-support tools for HABs management.
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•ML prediction of HABs is affected by errors in measured water quality datasets.•Chlorophyll-a prediction as index of HABs was assessed using subsets of measured data.•Ensemble RF and SVR models were used to generate chlorophyll-a prediction intervals.•Variation in datasets influences the ability of HABs ML models to reduce measurement uncertainty effect.
In the present study, decomposition mechanism of CeCl
3
·xH
2
O(s) and PrCl
3
·xH
2
O(s) was investigated using thermogravimetry, differential thermal analysis and evolved gas analysis techniques. ...Intermediate products formed in the dehydration of RE (Ce, Pr) Cl
3
·xH
2
O(s) were characterized by X-ray diffraction analyses. Thermodynamic stability of the RECl
3
·xH
2
O(s) and their intermediate products has been determined from the vapor pressure of water measured over the compounds employing dynamic transpiration technique.
The photosensitivity of amorphous chalcogenide thin films brings out light-induced changes in the nonlinear and linear optical parameters upon sub-bandgap and bandgap laser irradiation. The present ...work reports the
laser irradiated changes in the optical properties of As
Se
Sb
thin films. The thermally evaporated film showed an exponential decrease in optical bandgap and increase in Urbach energy. The decay rate of the bandgap was 6.24 min and growth rate of Urbach energy was 6.67 min respectively. The dynamics of photo-induced changes were observed from the changes in linear refractive index and its dependent parameters such as 3
order nonlinear susceptibility, nonlinear refractive index, dispersion and dielectric parameters. The conversion of heteropolar to homopolar bonds induced the photodarkening mechanism that changed the dispersion parameters. The decrease in
and
reduced the oscillator strength along with the zero-frequency dielectric constant. The optical and electrical conductivity changed significantly with time. The changes were saturated with time which brings stability in the film properties that is useful for various optical applications. However, no structural and compositional changes upon laser irradiation were noticed from the X-ray diffraction and EDX studies respectively. The surface homogeneity was checked from the FESEM picture.
•The dextrose added water spray enhances the heat transfer rate significantly.•The highest CHF (1.4 MW/m2) is achieved in case of 0.3 mol/L dextrose added water spray.•Post quenching analysis of the ...hot plate confirms unaltered surface morphology.
In the current work, by decreasing the sensible heat extraction period and enhancing the internal energy of the evaporating droplet; the high mass flux spray cooling is enhanced with the additional advantages such as attainment of unaltered surface morphology and zero deposition of the additives on the evaporating surface. To achieve the above-mentioned requirements, dextrose is used as an additive in water, which decreases coolant temperature due to heat of dissolution. Furthermore, the exothermic reaction between aqueous glucose and oxygen fulfill the latter requirement. In the current work, the heat transfer analysis clearly depicts enhancement with respect to the heat removal rate obtained in case of cooling by pure water. In addition to the above, the post quenching surface analysis of the heat-treated steel plate assures unaltered surface morphology. The comparison of the current quenching process with the cooling processes reported in the literature clearly asserts its suitability for the fast quenching operation.
The electrochemical behavior of CeCl
3
was investigated in two molten chloride mixtures, equimolar LiCl-KCl and NaCl-KCl melts using inert molybdenum and tungsten electrodes in the temperature range ...of 963 to 1053 K. Electrochemical methodologies like cyclic voltammetry and square wave voltammetry were employed to investigate the electrode process. Results showed that reduction of Ce(
iii
) to Ce(0) is quasireversible to irreversible in nature in both of these melts. The diffusion coefficient of Ce(
iii
) was determined in both the systems at four different temperatures and Arrhenius treatment was employed to obtain the activation energy for the diffusion process in the molten salt mixtures. The exchange current density of Ce(
iii
)/Ce(0) was evaluated in both the melts on Mo and W electrodes at four different temperatures from the Tafel plot.
Cyclic voltammetry of Ce(
iii
) in LiCl-KCl molten salt medium and the morphology of Ce metal deposited by electrochemical deposition.
The present manuscript investigated the effect of thermal annealing at 150 °C (below
T
g
) and 250 °C (above
T
g
) on the nonlinear as well as linear optical parameters and structural changes of the ...thermally evaporated As
35
Se
65
thin films. The structural investigation was done by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, whereas the surface morphology was studied by field emission scanning electron microscopy. The optical transmission and reflection spectra over the wavelength range 500–1200 nm were used to calculate the optical parameters. The optical energy gap, Urbach energy, optical density, skin depth, Tauc parameters for the as-deposited and annealed As
35
Se
65
films were estimated and discussed in terms of density of defect states and disorders. The indirect optical energy gap decreased for 150 °C annealed film and abruptly increased for 250 °C annealed film as compared with the as-prepared film. The Swanepoel envelope method, WDD model, and Sellemeire postulates were employed for analysis of refractive index, static refractive index, dispersion energy, oscillator wavelength, oscillator energy, and dielectric constant. The non-linear refractive index and third-order susceptibility were also estimated with the help of empirical relations which showed opposite changes for the two annealing temperatures. The tunable optical properties can be applied for several optoelectronic application.
The present work shows the effect of annealing conditions on the linear and nonlinear optical properties of two-year-old thermally evaporated 800 nm As
Se
Ge
thin films. The aging effect in this film ...is clearly noticeable as compared with the old observation. The two-year-old films were annealed at different temperatures like 373, 413, 453 and 493 K for 1 h. The optical parameters were calculated from the optical transmittance and reflectance spectra measured at normal incidence of light by spectrometer in the 500-1000 nm range. The linear refractive index (
) and extinction coefficient (
) were decreased with annealing temperature. The observation reveals the increase in optical band gap with increase in annealing temperature while the width of the tail in the gap has an opposite behaviour. The oscillator energy, dispersion energy, dielectric constant, the loss factor, and optical conductivity were discussed in detail. The nonlinear refractive index and optical susceptibility were calculated by using Miller's formula which decreased with annealing temperature. The changes in both linear and nonlinear optical parameters with annealing temperature showed that annealing temperature can be considered as a useful factor for controlling the optical properties of As
Se
Ge
chalcogenide films which could be the candidate for numerous photonic applications. The structural study was done by X-ray diffraction and Raman spectroscopy.
Continual, historical, and accurate information about the land use/land cover (LULC) changes of the earth’s surface is extremely important for sustainable management of natural resources. In this ...study, historical topographic sheets, IRS P6 LISS-III, and LANDSAT TM images were used to provide recent and historical LULC conditions of the Eastern Ghats Highlands of east India. The supervised classification results were further improved by employing image enhancement and visual interpretation. Ratio Vegetation Index with fuzzy-based possibilistic c-means classification approach has improved the classification accuracy of the shifting cultivated area. Post-classification comparisons of the classified images indicated that the major change consisted of barren land and forestland changing into agricultural land and scrubland. Between 1931 and 2008, forest cover was decreased from 52.7% to 29.6% of total area. There was an increase in the scrub area from 874 (10.4%) to 1269 km
2
(15.2%), and agricultural land from 978 (11.7%) to 2864 km
2
(34.2%) during the same period. The rate of deforestation was found to be 0.65 km
2
per year for reserve forest and 24.50 km
2
per year for mixed forest. The shifting cultivated area in the district was 308.7 km
2
during 2004, and that has been reduced since then and now is stabilized to 186.4 km
2
area. Among this 186.4 km
2
area, nearly half is covered by abandoned shifting cultivation. The decadal rate of decrease of shifting cultivated area is 0.15% per year. The shifting cultivated areas were mainly distributed at elevations 580–810 and 810–907 m and slopes 20–30 and 30–40%. Southeast and south facing slopes were preferred for shifting cultivation. Based on the identified causes of the change in shifting cultivation, policy recommendations for their better management were made.
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