Water Formation Research Articles

Synchronizing the Western Gotland Basin (Baltic Sea) and Lake Kälksjön (central Sweden) sediment records using common cosmogenic radionuclide production variations

Multi-archive studies of climate events and archive-specific response times require synchronous time scales. Aligning common variations in the cosmogenic radionuclide production rate via curve fitting methods provides a tool for the continuous synchronization of natural environmental archives down to decadal precision. Based on this approach, we synchronize 10Be records from Western Gotland Basin (WGB, Baltic Sea) and Lake Kälksjön (KKJ, central Sweden) sediments to the 14C production time series from the IntCal20 calibration curve during the Mid-Holocene period ~6400 to 5200 a BP. Before the synchronization, we assess and reduce non-production variability in the 10Be records by using 10Be/9Be ratios and removing common variability with the TOC record from KKJ sediments based on regression analysis. The synchronizations to the IntCal20 14C production time scale suggest decadal to multi-decadal refinements of the WGB and KKJ chronologies. These refinements reduce the previously centennial chronological uncertainties of both archives to about ± 20 (WGB) and ±40 (KKJ) years. Combining proxy time series from the synchronized archives enables us to interpret a period of ventilation in the deep central Baltic Sea basins from ~6250 to 6000 a BP as possibly caused by inter-annual cooling reducing vertical water temperature gradients allowing deep water formation during exceptionally cold winters.

Formation mechanism of high-altitude glacial mineral water in the Kunlun Mountains of Tibetan Plateau: Insights from isotopes and hydrochemistry

Study regionThe Kunlun Mountains on Tibetan Plateau Study focusThe Tibetan Plateau, well known as Asian Water Tower, holds immense potential for the formation of glacial mineral water. The present research focuses on the hydrochemical and isotopic signatures and formation pattern of natural glacial mineral water in the alpine region on Tibetan Plateau. New hydrological insights for the regionThe investigated mineral groundwater has outstanding water quality and slightly alkaline nature. It is with fresh hydrochemical facies of HCO3-Na·Ca type with total dissolved solids (TDS) in the range of 384–964 mg/L, and featured by notably rich strontium with the concentrations of 0.67–0.81 mg/L, far exceeding the recommended mineral water minimum threshold of 0.20 mg/L. The mineral groundwater is originated from the glacier meltwater of mountainous area with elevation over 4500 m. It subsequently infiltrates into the bedrock and move within the groundwater system with a residence time of approximately 52 years. Its hydrochemical constituents are naturally governed by water-rock interactions of silicates dissolution, cation exchange, and celestite and strontianite dissolution. A conceptual model is proposed to outline the formation pattern of glacial mineral water in alpine region on Tibetan Plateau. Findings of this study can fill the study gap regarding glacial mineral water on Tibetan Plateau, and further contribute to the future study and development of natural glacial mineral water in alpine regions worldwide.

Effects of cupric ions on the formation of chlorinated disinfection byproducts from nitrophenol compounds during UV/post-chlorination

Cupric ions (Cu2+) are ubiquitous in surface waters and can influence disinfection byproducts (DBPs) formation in water disinfection processes. This work explored the effects of Cu2+ on chlorinated DBPs (Cl-DBPs) formation from six representative nitrophenol compounds (NCs) during UV irradiation followed by a subsequent chlorination (i.e., UV/post-chlorination), and the results showed Cu2+ enhanced chlorinated halonitromethane (Cl-HNMs) formation from five NCs (besides 2-methyl-3-nitrophenol) and dichloroacetonitrile (DCAN) and trichloromethane (TCM) formation from six NCs. Nevertheless, excessive Cu2+ might reduce Cl-DBPs formation. Increasing UV fluences displayed different influences on total Cl-DBPs formation from different NCs, and increasing chlorine dosages and NCs concentrations enhanced that. Moreover, a relatively low pH (5.8) or high pH (7.8) might control the yields of total Cl-DBPs produced from different NCs. Notably, Cu2+ enhanced Cl-DBPs formation from NCs during UV/post-chlorination mainly through the catalytic effect on nitro-benzoquinone production and the conversion of Cl-DBPs from nitro-benzoquinone. Additionally, Cu2+ could increase the toxicity of total Cl-DBPs produced from five NCs besides 2-methyl-3-nitrophenol. Finally, the impacts of Cu2+ on Cl-DBPs formation and toxicity in real waters were quite different from those in simulated waters. This study is conducive to further understanding how Cu2+ affected Cl-DBPs formation and toxicity in chlorine disinfection processes and controlling Cl-DBPs formation in copper containing water.

Multi-proxy paleoenvironmental reconstruction of Robertson Bay, East Antarctica, since the last glacial period

Antarctic fjords and coastal bays are excellent traps for sediment and represent key areas for high-resolution investigation of past environmental conditions. Robertson Bay is an understudied coastal area located at the confluence of the Ross Sea and the Southern Ocean. Recently obtained seafloor morphology data indicate the presence of a cross-shelf elongated valley, composed of three minor basins separated by sills and seabed ridges with an arcuate shape. Several cores were collected within the basins, and investigated using a multiproxy approach including sedimentological, chemical, geochemical, and micropaleontological characterization to reconstruct the paleoenvironmental evolution from the last glacial period to present. The ages of two of these cores are constrained using ramped pyrolysis oxidation radiocarbon dating. Four sedimentary facies were recognised from which we developed a sedimentary model covering the last 21,000 years (21 ka BP). Our record provide evidence for a covering ice shelf cover from 21 to 16.5 ka BP, which gradually receded between 16,5 and 11 ka BP due to the progressive intrusion of modified Circumpolar Deep Water, thereby promoting the formation of Ice Shelf Water and High Salinity Shelf Water. From 11 to 5,8 ka BP, the ice shelf continued shrinking and nutrient-rich of modified Circumpolar Deep Water penetration onto the continental shelf progressively favoured diatom blooms and a general increase in primary productivity until 5.8 ka BP. The Late Holocene is characterised by an alternation of prolonged sea ice cover with stratified water column and strong bottom current with prolonged sea-ice free season with the intrusion of modified Circumpolar Deep Water and very slow energy bottom current.

The Southern Ocean deep mixing band emerges from a competition between winter buoyancy loss and upper stratification strength

Abstract. The Southern Ocean hosts a winter deep mixing band (DMB) near the Antarctic Circumpolar Current's (ACC) northern boundary, playing a pivotal role in Subantarctic Mode Water formation. Here, we investigate what controls the presence and geographical extent of the DMB. Using observational data, we construct seasonal climatologies of surface buoyancy fluxes, Ekman buoyancy transport, and upper stratification. The strength of the upper-ocean stratification is determined using the columnar buoyancy index, defined as the buoyancy input necessary to produce a 250 m deep mixed layer. It is found that the DMB lies precisely where the autumn–winter buoyancy loss exceeds the columnar buoyancy found in late summer. The buoyancy loss decreases towards the south, while in the north the stratification is too strong to produce deep mixed layers. Although this threshold is also crossed in the Agulhas Current and East Australian Current regions, advection of buoyancy is able to stabilise the stratification. The Ekman buoyancy transport has a secondary impact on the DMB extent due to the compensating effects of temperature and salinity transports on buoyancy. Changes in surface temperature drive spatial variations in the thermal expansion coefficient (TEC). These TEC variations are necessary to explain the limited meridional extent of the DMB. We demonstrate this by comparing buoyancy budgets derived using varying TEC values with those derived using a constant TEC value. Reduced TEC in colder waters leads to decreased winter buoyancy loss south of the DMB, yet substantial heat loss persists. Lower TEC values also weaken the effect of temperature stratification, partially compensating for the effect of buoyancy loss damping. TEC modulation impacts both the DMB characteristics and its meridional extent.

Carbon dioxide hydrogenation to methanol by flame-deposited CuO/ZrO2-polymer membrane reactors

Carbon dioxide hydrogenation for methanol synthesis, within the framework of carbon dioxide utilization represents a promising strategy. Nevertheless, high conversion of carbon dioxide into methanol presents significant challenges, primarily arising from thermodynamic constraints and catalyst deactivation due to the formation of water as a by-product. In response to these challenges, this investigation focused on the development of an innovative hybrid catalytic membrane reactor utilizing flexible polymeric membranes with flame-made catalysts. The nanostructured CuO/ZrO2 thin layers were synthesized by flame spray pyrolysis and directly deposited on two polyimide polymers and polybenzimidazole membranes. The CuO/ZrO2-polymer membranes are reduced by H2 at 300 °C resulting in Cu/ZrO2-polymer nanocomposites. This novel hybrid membrane design facilitated the efficient separation of by-product water from the reaction environment, effectively promoting carbon dioxide conversion and ultimately leading to enhanced methanol production rate. At 200 °C and 20 bar, these catalytic membrane reactors demonstrate exceptional performance, achieving 113 % improvement in carbon dioxide conversion and a remarkable 106 % increase in methanol production rate compared to conventional catalytic fixed bed reactors. Overall, the catalytic membrane, synthesized using flame spray pyrolysis, has shown long-term stability and ability to suppress catalyst deactivation caused by water, ensuring sustained catalyst stability throughout the reaction.

Study on the effect of temperature on pressure drop and under-rib convection in PEMFC

ABSTRACT Pressure drop effectively reflects the state of water in PEMFC channels and gas diffusion layers. In order to study the regularities in pressure drop and the characteristics of the under-rib convection in the PEMFC at different temperatures, a three-dimensional multiphase flow model was presented, which considers the formation and transport of water inside the cell, as well as the mechanisms governing the conversion between different states of water (liquid water, water vapor and membrane water). The model was imported into Fluent using user-defined functions to simulate and analyze under-rib convection characteristics within the fuel cell at different temperatures. A fuel cell testing system was established to perform tests on polarization curves and anode pressure drop at different temperatures. The results show that the model agrees well with the experiment data, with a maximum error of 5.34%. The anode pressure drop shows a step-level characteristic with three segments: a normal segment, an increasing segment and a stepped segment. As the temperature increases, both the average anode pressure drop and the velocity vector of reactants gradually increase. Notably, the peak velocity vector is observed in the rib-turning region, where heightened under-rib convection is evident.

Global-scale future climate projections from ACCESS model contributions to CMIP6

This paper describes projected climate evolution and outcomes simulated by the Australian Community Climate and Earth System Simulator (ACCESS) to varying future scenarios, including of socio-ecological and technological development, and land-use and land-cover change. Contributions to the Coupled Model Intercomparison Project Phase 6 (CMIP6) from the climate model version, ACCESS-CM2, and the fully coupled Earth System Model version, ACCESS-ESM1.5, are presented for the near-future (2020–2050), 21st Century (2000–2100) and longer-term (2100–2300). Scenario differentiation in the near future is aided by high-density sampling in large-ensemble ACCESS-ESM1.5, more clearly illustrating projected 2020–2050 global changes in temperature, precipitation and aerosol optical depth. Over the 21st Century, the heightened equilibrium climate sensitivity of ACCESS-CM2 relative to ACCESS-ESM1.5 results in persistently greater surface air temperature increases and larger amplified polar warming, leading to more rapid sea ice decline. Although weakening of the Atlantic meridional overturning circulation (AMOC) occurs in both models, 21st Century recovery under aggressive-mitigation and overshoot scenarios only occurs in ACCESS-ESM1.5; AMOC weakening continues under all scenarios in ACCESS-CM2 through to 2100. Longer-term climate response from simulations extending to 2300 depict opposing hemispheric responses of polar surface air temperatures and sea ice in both models under scenarios based on aggressive mitigation action, leading to a resurgence of surface ocean warming and Antarctic sea ice decline. Under a future scenario where development is driven by continued fossil fuel use, both AMOC and Antarctic Bottom Water Formation continue to weaken across 2200–2300 in both models, reaching such low levels in ACCESS-CM2 that these pivotal components of global meridional overturning circulation could be considered essentially to have ceased.

THE CHEMICAL ORIGIN AND GEOTHERMOMETERY OF HOT SPRINGS WATERS IN THE REGION OF KHENCHELA, ALGERIA

Our study is carried out on the trio of thermomineral waters in the region of Khenchela - Hammam Salhin, Hammam Knif, and Hammam Djaarir - Northeast of Algeria. The purpose of this study is to determine the physicochemical and geothermal origin of the thermal spring (temperature, pH, and electrical conductivity). The temperatures of the thermal water samples which were being studied varied from 38 to 72°C; therefore, this variation has a direct relation to the climatic conditions and/or the combination of the water which is derived from various sources in the formation of the thermal spring. Additionally, the pH value of the spring under study is of a neutral to slightly alkaline quality, while its electric conductivities are high, ranging from 3059 μS/Cm to 5007 μS/Cm. The Piper diagrams presented the domination of sodium chloride (Na-Cl) and sodium sulfate (Na-SO4) facies as two types of water in the hydrochemical facies. These facies indicate the mineral composition of the thermal waters, a product from the reservoir by way of geological formations in the subsurface. This is a plausible reason from the chemical changes observed in the fluids and can well be associated with the high influence of water-rock interaction, that is, the formation of sodium bicarbonate water to sodium-chlorinated water formation, where it is linked with the effects of dissolution and salinity in the formation of saliva found in regions with semi-arid climatic conditions. Evaporation would play a major role in increasing the sodium content, while the IIRG plots closer to the industry "α" standard than the other plots. These are the characteristic features of an evaporation-based system. The crucial parameter C serves as a strong indicator of circulation in carbonate reservoirs subject to evaporation.

From Gel to Crystal: Mechanism of HfO2 and ZrO2 Nanocrystal Synthesis in Benzyl Alcohol.

Nonaqueous sol-gel syntheses have been used to make many types of metal oxide nanocrystals. According to the current paradigm, nonaqueous syntheses have slow kinetics, thus favoring the thermodynamic (crystalline) product. Here we investigate the synthesis of hafnium (and zirconium) oxide nanocrystals from the metal chloride in benzyl alcohol. We follow the transition from precursor to nanocrystal through a combination of rheology, EXAFS, NMR, TEM, and X-ray total scattering (PDF analysis). Upon dissolving the metal chloride precursor, the exchange of chloride ligands for benzylalkoxide liberates HCl. The latter catalyzes the etherification of benzyl alcohol, eliminating water. During the temperature ramp to the reaction temperature (220 °C), sufficient water is produced to turn the reaction mixture into a macroscopic gel. Rheological analysis shows a network consisting of strong interactions with temperature-dependent restructuring. After a few minutes at the reaction temperature, crystalline particles emerge from the gel, and nucleation and growth are complete after 30 min. In contrast, 4 h are required to obtain the highest isolated yield, which we attribute to the slow in situ formation of water (the extraction solvent). We used our mechanistic insights to optimize the synthesis, achieving high isolated yields with a reduced reaction time. Our results oppose the idea that nonaqueous sol-gel syntheses necessarily form crystalline products in one step, without a transient, amorphous gel state.

Unveiling the mechanism of alkali etched CuMn2O4-δ spinel catalysis enhance for acetone catalytic Oxidation: The roles of Metal-Oxygen bond and oxygen defect site

Spinel is a powerful non-precious metal oxide catalyst that can be used to catalyze the combustion of volatile organic pollutants, potentially replacing precious metal catalysts. To enhance the catalytic activity and stability of CuMn2O4, we constructed gradient distribution of oxygen vacancies (Vo) on the CuMn2O4-δ surface utilizing alkali treatment method. Alkali treatment dissolves some of the Cu atoms of the CuMn2O4 catalyst, leading to the transformation of part of the Mn-O-Cu structure into the Mn-O structure, which was results in the lengthening of the Mn-O bond and the production of cation defects. The Mn-O bond breaks, releasing a large amount of reactive oxygen and forming oxygen vacancies. Highly reactive lattice oxygen and cation defects is more likely to participate in oxidation reactions. In the catalytic combustion of acetone, the alkali-treated catalyst showed high activity and stability, and the oxidation rate of acetone at 170 °C was increased by 2.86 times. Particularly, the alkali treatment catalysts can convert acetone that has been adsorbed into acetic acid and formic acid using catalyst lattice oxygen in anoxic environment. In the presence of an oxygen stream, the acetic and formic acids underwent direct oxidation, resulting in the formation of water and carbon dioxide. This work promotes the development of oxygen vacancy engineering on the surface of transition metal oxides and provides a new approach to improve the activity and stability of CuMn2O4 in real environments.

On the Spatio‐Temporal Scales of the Subtropical Mode Water Formation in the South Atlantic

AbstractWe examined the changes in the ocean’s upper layer structure involved in the formation of the subtropical mode water in the South Atlantic. Here we present the results from a survey done in the region of formation between 37°W and 32°W and 34°S and 37°S from July–October 2018, using high‐resolution measurements obtained from an underwater glider. From its records, the mode water development was observed for the first time in the South Atlantic as localized chimney‐like patterns in the temperature, salinity, and potential vorticity (PV) measurements with a horizontal scale of (7 ± 2) km, associated with wintertime oceanic convective processes. Over time, these submesoscale structures tend to expand and dominate the region as a large volume of mode water. These vertical structures present highly homogeneous temperature and salinity values. The observed PV was on the order of 5.0 × 10−11 m−1 s−1, which is one order of magnitude smaller than the pre‐existent mode water at the lower layers; negative values were observed, indicating active convection. A 1‐D vertical model was used to predict the depth of the mixed layer conditioned by the surface fluxes and triggered by its changes in winter to late spring. Comparisons of the sea surface temperature measured from satellite collocated with the glider’s measurements showed a very good agreement. From this analysis, we were able to establish the decorrelation scales that characterize mode water formation. Further inspection of the glider data yielded temporal decorrelation scales indicative of convection modified by planetary rotation.

Processes explaining increased ocean dynamic sea level in the North Sea in CMIP6

Ocean dynamic sea level (ODSL) is expected to be one of the major contributors to sea level rise in the North Sea during the 21st century. This component is defined as the spatial sea level anomaly due to ocean currents, wind stresses and local thermosteric and halosteric effects. Climate models from CMIP5 and CMIP6 show a large spread, as well as an increase between CMIP5 and CMIP6 North Sea ODSL projections. In this study, we apply linear regression models on CMIP5 and CMIP6 data to get a better understanding of the processes that influence ODSL change in the North Sea. We find that neither global surface air temperature nor global mean thermosteric sea level can reproduce ODSL projections based on a linear relation in CMIP6, whereas this was the case for CMIP5. Including the strength of the Atlantic meridional overturning circulation (AMOC) as an additional predictor enables us to reproduce long-term changes in ODSL for both ensembles. The sensitivity to the AMOC increased in CMIP6, which points to a difference in model dynamics between CMIP5 and CMIP6, and a more important role of the deep ocean. To investigate this further, we analyse mixed layer depth data in the North Atlantic. We find that models with a relatively deep mixed layer in the Greenland Sea over the period 1985–2004, project larger rise in ODSL in the North Sea for both CMIP5 and CMIP6. This implies that the location of deep water formation in the North Atlantic potentially influences ODSL in the North Sea. The number of these models increased from CMIP5 to CMIP6, again pointing to a different sensitivity to larger scale processes, potentially explaining the difference between the two ensembles.

MINE WATER MANAGEMENT IN THE COAL MINING PROCESS

The open mining method has the potential for the formation of mine water. Mine water is characterized by a high degree of acidity which affects the life of organisms and the quality of the environment indirectly or directly, therefore it needs to be managed. This study examines mine water management at PT Adaro Indonesia. The methods used in the research were field studies and laboratory experiments. Grab sampling is used to take water samples, with the test parameters being pH, Fe and Mn metals and total suspended solid (TSS). Data analysis was carried out quantitatively and descriptively. The mine water management used is in the form of a settling pond. The settling pond consists of several compartments, namely sedimentation pond, safety pond, treatment pond and mud pond. The quality of mine water management through a series of settling ponds obtained changes in pH to 6.07, Fe metal 0.0465 mg/l, Mn metal 1.3513, and TSS 35 mg/l with an efficiency of more than 50%. The quality of mine water produced after going through management has met the established regulations, namely Decree of the Minister of Environment and Forestry No. 1347/MENLHK/SETJEN/PLA.4/12/2022.

A pilot-scale study and evaluation of the melting process and vitrification characteristics of electroplating sludge by oxygen enrichment melting

Melting/vitrification is an effective method for harmless and rapid disposal of electroplating sludge (EPS) on a large scale. In our work, oxygen enrichment melting was proposed to reduce the high energy consumption during EPS melting. The melting and vitrification process of EPS can be divided into water evaporation, chemical decomposition and formation, crystal phase transition and vitrification. The addition of quartz sand (QS) promotes silicate formation and the crystal phase transition process, resulting the highest value vitrification rate (99.54%) of EPS slag. The results of heavy metal leaching of both water-quenched and air-cooled slags meet the national standard. The increase of oxygen concentration reduces the operation cost by 48.3%. The operation cost continues to reduce when the QS addition is 5%, wherein the lowest operation cost was 217.23 dollars/ton EPS. The emissions of SO2 and NOx with the addition of 5% of QS are the lowest among all experiment conditions. All results indicate that the oxygen enrichment melting technology is a promising method. 5% of QS addition during EPS melting with 90% oxygen concentration is the best operation condition in terms of the vitrification rate, heavy metal solidification and leaching, flue gas emission, and operation cost.

Modification mechanism of calcium lignosulfonate on cementing cement

During the construction of coalbed methane extraction wells, cementing cement sheath is crucial for the stability and sealing of surface wells. One effective method to enhance these properties is the addition of lignosulfonate. However, the mechanism of the effect of calcium lignosulfonate on the whole process of cement hydration is still unclear. In this paper, the water distribution and variation characteristics of calcium lignosulfonate modified cement paste were revealed by low-field nuclear magnetic resonance technology, and the hydration ion experiment of modified cement was carried out to obtain the variation characteristics of hydration ions of modified cementing cement. Finally, the formation mechanism of hydration products was clarified by analyzing the phase change of modified cement stone. The results indicate that the cement paste’s hydration process can be divided into four stages: dissolution, crystallization, acceleration, and decline. During the dissolution stage, calcium lignosulfonate’s air entraining effect maintains the cement paste in a stable suspension state. In the crystallization stage, calcium lignosulfonate’s electro-repulsion delays the formation of hydration products and the hydration process. During the acceleration stage, the addition of calcium lignosulfonate reduces bound water formation in the cement slurry’s flocculation structure, and the released filled water participates more in the hydration reaction, reducing the total relaxation signal’s increasing trend. In the decline stage, the cement paste has solidified, and the system’s water is primarily in the porous medium. The research results have practical guiding significance for the addition of calcium lignosulfonate in cementing operations.

An In Situ TEM Study of the Influence of Water Vapor on Reduction of Nickel Phyllosilicate - Retarded Growth of Metal Nanoparticles at Higher Rates.

Unavoidable water formation during the reduction of solid catalyst precursors has long been known to influence the nanoparticle size and dispersion in the active catalyst. This in situ transmission electron microscopy study provides insight into the influence of water vapor at the nanoscale on the nucleation and growth of the nanoparticles (2-16nm) during the reduction of a nickel phyllosilicate catalyst precursor under H2/Ar gas at 700°C. Water suppresses and delays nucleation, but counterintuitively increases the rate of particle growth. After full reduction is achieved, water vapor significantly enhances Ostwald ripening which in turn increases the likelihood of particle coalescence. This study proposes that water leads to formation of mobile nickel hydroxide species, leading to faster rates of particle growth during and after reduction.

Self-assembled Gd0.1Ce0.9O1.95-BaGd0.8La0.2Co2O6‒δ nanocomposite cathode for efficient protonic ceramic fuel cells

Protonic ceramic fuel cells (PCFCs) are characterized by a low activation energy for proton conduction and a high fuel utilization efficiency at low-to-intermediate temperatures. However, the sluggish oxygen reduction reaction kinetics on the cathodes drastically limit the power output performance of PCFCs. Herein, multiphase Gd0.1Ce0.9O1.95-BaGd0.8La0.2Co2O6‒δ (GDC-BGLC) nanocomposite cathodes are prepared by coupling self-assembly and sintering-free electrode construction methods. The nanocomposite cathode comprises mixed H+/e– conducting BGLC and O2− conducting GDC and BaCoO3 nanoparticles, and these phases are homogeneously mixed with coherent heterointerfaces. The nanocomposite cathode exhibits a significant increase in surface oxygen vacancies and three-phase boundaries, enhanced catalytic activity, and reduced activation energy for the oxygen reduction and water formation reactions. The results imply that the oxygen reduction and water formation reactions on the multiphase GDC-BGLC nanocomposite electrodes are most likely the dissociation, reduction and diffusion of oxygen species, which in turn is affected by the water vapor formed. An anode-supported single cell with the GDC-BGLC cathode exhibits a peak power density of 810 mW cm−2 at 700 °C with excellent operating stability at 650 °C for 110 h. This study provides a new strategy for the preparation of a high-performance and durable nanocomposite cathode for PCFCs.

Pothole Detection Using Machine Learning Models

Potholes are damage caused to the ground by the formation of water and wear and tear over time. According to statistical data, bad road conditions account for about one- third of the total road accidents which has been increasing exponentially. Potholes have become so common that it has become second nature for people to learn how to spot and avoid them, which causes further accidents. The need of the hour is to build a dependable pothole detection system to accurately detect potholes and warn the drivers and government officials in advance. The process to build such a system is divided into two steps i.e. collection of data and pothole identification. The first step is achieved by taking the data from already available data sets on the Internet. The other step includes labeling the potholes in the data set which is usually done manually. This paper focuses mainly on Visual-based techniques to identify the best detection method by comparing popular Machine Learning models and algorithms. The obtained data set is trained using various transfer learning techniques like You Only Look Once (YOLO)[1] and Single Shot Detector (SSD) [1]. Apart from transfer learning, this paper also focuses on some proposed techniques using Convolutional Neural Net- works (CNN) and classification algorithms like Support Vector Machine (SVM)[21] to identify and localize potholes. The actual size of potholes is calculated using morphological operations, which is a just a straightforward technique to analyze figures using set theory. To analyze every model and find the best model, each model is trained on different sizes of data sets and the obtained result is validated and examined by considering different aspects like speed and accuracy in mind.

Ordinary hydrophobicity of mesoporous faujasites boosting the catalytic ketalization of glycerol with acetone

A series of faujasite zeolites were used in the glycerol ketalization reaction with acetone. This zeolitic structure is widely explored in cracking reactions and has known mesoporosity and hydrophobicity, resulting from the treatments conducted to remove aluminum atoms from the framework and produce a stabilized structure containing different Si/Al ratios. Such properties, in combination with the typical acidity of zeolites, are extremely suitable for driving the ketalization reaction, a two-phase reaction that involves bulky compounds (compared to the size of the zeolitic pores) and that is reversible with the formation of water as a byproduct. The presence of mesopores in the zeolites was confirmed from the pore size distribution using nitrogen physisorption isotherms. Hydrophobicity was confirmed indirectly by thermogravimetry, measuring the amount of water adsorbed and the water desorption temperature. The contact angle of zeolites with glycerol showed only a slight increase with the increase in the Si/Al ratio due to a rise in SiOH groups, defects that naturally arose from removing aluminum atoms. Despite the high concentration of structural hydrophilic SiOH groups, the accessibility and hydrophobicity of isolated Brønsted acid sites (up to Si/Al = 250) inside the zeolitic pores were important to guarantee an improved performance in the reaction.