Basin Type Research Articles

An experimental investigation on a portable bubble basin humidification/dehumidification desalination unit utilizing a closed-loop pulsating heat pipe

The present work aims to enhance the performance of a solar energy-driven HDH desalination system. An experimental apparatus consisting of a novel closed-loop pulsating heat pipe (CLPHP) assisted by a bubble basin HDH system was investigated. To evaluate the productivity of the fresh water, tests have been properly designed and conducted in outdoor and indoor modes during June and July of 2020, under local weather conditions of Mashhad, Iran. A closed air-heated configuration is introduced into the HDH desalination system, to recover the condensation latent heat. The air leaving the dehumidifier is pre-heated and pre-humidified using CLPHP before entering the humidifier of the desalination unit. Also, an air injection system is used to enhance the mass and heat transfer rate by generating bubbles. In the experiments, the influence of the operating conditions such as radiation and air mass flow rate on the performance of the desalination unit was investigated. Furthermore, a comparison between the bubble basin and bubble column types was carried out. Based on the results, the bubble basin type presented a higher yield compared to the bubble column type that was obtained as 0.83 and 0.70 (kg/(hr.m2)), respectively. Besides, it was observed that by increasing the radiation and air mass flow rate, productivity is improved. The maximum obtained yield of the proposed system was achieved as 8.7 L/(day.m2).

A Performance study of a single basin double slope solar still with 45˚ of glass-cover slope angle in Indonesia

Solar energy is a clean energy, pollution free and available in abundance that can be used directly for heating. Utilization of solar heat in the supply of clean water through distillation is very suitable for use in remote coastal and swampy areas. In this study the performance test of a single basin type solar distillation system with a double slope cover that has 45˚ slope angle is operated in Cilegon-Indonesia. With rare rainy conditions the average solar distillation efficiency reaches 34.3%. The formation of condensate at night is almost five times greater than during the daytime, because temperature of water in the basin is higher than the inner surface temperature of the glass-cover. Thus the use of material as a thermal energy storage when the intensity of radiation is high and releasing it into the water at night will help a lot to increase condensate production.

Performance enhancement of basin solar still using paraffin wax and floating wicks in the basin

Single effect basin type solar still has been modified to enhance the productivity of still by placing paraffin wax and floating wicks in the basin. The paraffin wax was used to store solar energy during daytime and the same energy was supplied to basin water during night to generate distillate during night. Whereas, the floating wicks were placed in the basin to enhance the evaporation rate of basin water of modified still during day time. Initially, the performance of modified still has been compared with conventional still to find the effect of paraffin wax under the similar weather and operating conditions. The effects of covering basin area of the still with paraffin wax at fixed basin water depth on the distillate output of solar still have been investigated. The modified still performed better, when basin area of the still was partially covered with paraffin wax because of availability of path for heat transfer and energy storage between warm basin water and top surface of wax during night. It has been observed that the cumulative efficiency of still was found to be maximum when 6000 g of paraffin wax was placed in the basin water and solar intensity was 23.5 MJ/m2. The overall distillate of modified still with paraffin wax in the basin was recorded as 3.96 kg/m2 which was 28.14% higher than the conventional still. The overall cumulative efficiency of modified still having paraffin wax in the basin and conventional still was 72.63% and 56.67% respectively when the solar intensity and ambient temperature was 23.5 MJ/m2 and 34.8 °C. When floating wicks were added with paraffin wax it gives the higher overall productivity gain which was 31.36% more that of conventional still. The overall cumulative efficiency of modified and conventional still was 80.69% and 61.42% respectively.

Experimental Analysis and CFD Modeling for Conventional Basin-Type Solar Still

With the rising population, environmental pollution, and social development, potable water is reducing and being contaminated day by day continually. Thus, several researchers have focused their studies on seas and oceans in order to get potable fresh water by desalination of their saltwater. Solar still of basin type is one of the available technologies to purify water because of free solar energy. The computational fluid dynamic CFD model of the solar still can significantly improve means for optimization of the solar still structure because it reduces the need for conducting large amount of experiments. Therefore, the main purpose of this study is presenting a multi-phase, three-dimensional CFD model, which predicts the performance of the solar still without using any experimental measurements, depending on the CFD solar radiation model. Simulated results are compared with experimental values of water and glass cover temperatures and yield of fresh water in climate conditions of Sheben El-Kom, Egypt (latitude 30.5° N and longitude 31.01° E). The simulation results were found to be in acceptable agreement with the experimental measured data. The results indicated that the daily simulated and experimental accumulated productivities of the single-slope solar still were found to be 1.982 and 1.785 L/m2 at a water depth of 2 cm. In addition, the simulated and experimental daily efficiency were around 16.79% and 15.5%, respectively, for the tested water depth.

Coastal environments shape chemical and microbial properties of forest litters in the Circum‐Mediterranean region

AbstractThis study explores how chemical and microbial properties of litters can be affected by coastal environments across the Mediterranean basin. A litterbag experiment including Pinus halepensis Mill. and Pistacia lentiscus L., collected from both inland and coastal areas, was set up in France, Greece and Algeria. Control litterbags were left in their sampling sites and a transfer of litterbags from inland to coastal areas was performed to test whether the effect of the specific constraints of coastal environments varies according to the country and the litter type. After 10 months, litter chemical composition (CP/MAS 13C‐NMR) and microbial activities (cellulase activity, basal respiration, catabolic diversity using Biolog) and community structure (TRFLP) were analysed. Coastal conditions led to various responses: (i) litter aromaticity differed in the coastal zones depending on the country (high in the Greek coastal area, low in the Algerian coastal zone), (ii) fewer functionally diversified microbial communities were found in the Greek coastal area compared to the French and Algerian coasts, (iii) genetic diversity and richness were strongly impacted after transfer to the coastal zone whatever the country. The type of litter shaped microbial communities: (i) at a local scale (i.e., in either coastal or inland areas) catabolic profiles and cellulase activities varied with the plant species, (ii) at a regional scale, the effect of coastal conditions differed with the plant species (basal respiration, Shannon‐Weaver index, catabolic diversity H′, cellulases and catabolic profiles). Thus, litter microbial properties differed in coastal environments across the Mediterranean basin and plant litter type plays a major role in microbial properties at a large spatial scale.Highlights The environmental drivers of litter microbial sensitivity to water potential stress were investigated Litterbag transfers from inland to coastal areas were performed in the Mediterranean. Soil and land system units conform to long‐tail or heavy tail distributions. Microbial diversity of inland litters decreased when exposed to coastal conditions Litter plant species shape microbial functioning even at wide spatial scales. Coastal areas and plant litter drive microbial responses to water potential stress.

Geomorphologic Analysis of Small River Basin within the Framework of Fractal Tree

This paper presents the modified framework of geomorphologic analysis based on the concept of fractal tree. Especially, it is intended to provide hydrologic practitioners with the information on the fractal property of small river basins. To this end, the complete drainage path network is applied to a growth process of a fractal tree for the basin of interest by connecting a channel network to overland drainage pathways. The growth process of a fractal tree would occur only within the limited region possessing channel flow properties in a natural river basin. The exponent of the intra basin type of Hack’s law could show a variable trend in small river basins mainly due to anisotropic property of the catchment planform. The bifurcation process of a drainage path network might be more sensitive to the growth step of the fractal tree than the meandering process of drainage path segment. The fractal dimension from the sinuosity of a channel segment is relatively stable compared to the one from the bifurcation process of the network, so that the geomorphologic features of a small river basin can be characterized by the anisotropic property of catchment planform as well as the bifurcation property of drainage path network with the growth of the fractal tree.

Controls on hydrocarbon accumulation by facies and fluid potential in large-scale lacustrine petroliferous basins in compressional settings: A case study of the Mesozoic Ordos Basin, China

Large-scale lacustrine basins in compressional settings are an important type of petroliferous basin, and the study of the characteristics of hydrocarbon accumulation in such basins is of great significance. This synthesis paper takes the Mesozoic Ordos Basin (central China) as a case study to establish lateral and vertical hydrocarbon accumulation patterns in this basin type, and highlights how facies and fluid potential control hydrocarbon accumulation in such basins. Based on systematic analyses of the Mesozoic source rocks, sedimentary facies, migration and accumulation patterns, and characteristics of the oil reservoirs, the hydrocarbon accumulation characteristics in the Mesozoic Ordos Basin are discussed. The analysis indicates that sedimentary facies controlled the characteristics and distribution of hydrocarbon source rocks and reservoirs, while diagenetic facies controlled the quality and distribution of the reservoirs. Excess pressure and fluid potential controlled hydrocarbon migration directions and paths, whereas facies and potential controlled the locations of oil accumulations and traps. It is concluded that source rocks controlled oil-bearing regions, sedimentary facies controlled oil-bearing plays, and fluid potential controlled the locations of accumulations. For shallow intervals, because fluid migration is mainly controlled by buoyancy, paleotopographic highs played an important role in controlling hydrocarbon accumulations. For deep layers (Chang 7 to Chang 10 members), since buoyancy is less than the capillary pressure, excess pressure caused by the undercompaction of mudstone and hydrocarbon generation at depth provides the driving force for lateral and vertical migration of oil, and becomes the main migration force. The reservoir accumulation characteristics differ laterally between regions of the basin; at the periphery of the basin, reservoir units are stacked in a step-wise manner, whereas at the center of the basin, multiple reservoir intervals are vertically stacked in the form of multistorey accumulations. Vertically, layers with different burial depths have different accumulation characteristics; the paleotopography controlled hydrocarbon accumulation in shallow intervals; instead excess pressure, fluid potential, and paleotopography controlled accumulation in deep intervals. This understanding could be used to inform prospecting in other large-scale lacustrine petroliferous basins in compressional settings such as the Eocene Green River Basin in the U.S.A. and the Middle Triassic Gunnedah Basin in Australia.

Occurrence and flow systems of the anticline-controlled thermal groundwater near Chongqing in eastern Sichuan Basin of China

Abstract A review and assessment of earlier studies shows that the thermal groundwater near Chongqing in the eastern Sichuan Basin of China has a unique occurrence called the ‘basin-anticline outcropping’ type. Its occurrence and emergence are strongly controlled by the nearly north–south trending anticlines. The basin-anticline outcropping type groundwater is similar to that of the basin type but also has the characteristics of the outcropping type because of the anticlines. The natural hot springs in the study area exist mainly in the outcropping areas of the carbonates, in the middle and the plunging ends of the anticlines where the topography was cut by rivers. They can also rise through the overlying sandstones and form up-flow springs. Geothermal wells tapping the carbonate reservoirs on the flanks of the anticlines also produce thermal groundwater. The groundwater flow can be divided into three levels: (1) shallow circulation system with groundwater of HCO3-Ca type and low TDS discharging through normal temperature springs, (2) middle circulation system with groundwater of SO4-Ca type and TDS of 2–3 g/L discharging through hot springs and (3) deep circulation system with groundwater of Cl-Na type and high TDS discharging through hot springs or wells.

GEOCHEMICAL CHARACTERISTICS OF GOLD-BEARING GRANITOIDS AT AYANFURI IN THE KUMASI BASIN, SOUTHWESTERN GHANA: IMPLICATIONS FOR THE OROGENIC RELATED GOLD SYSTEMS

This study investigates auriferous granitoids from the Esuajah and Fobinso pits within the Ayanfuri environment in the Paleoproterozoic Kumasi basin. The aim is to establish the geochemical characteristics of the granitoid gold ores and the possible deposit type which may influence mineral project development. 13 major and 51 trace elements were analyzed using XRF and ICP-MS devices, respectively. The granitoids are mainly classified as granodiorite that crystallized from a calc-alkaline magma series. The Fobinso granodiorite derived from the partial melting of the Birimian metasedimentary rocks, while the Esuajah granitoid derived from igneous rock melts. The granitoid are linked to magma source depleted in mantle material that contains crustal components through subduction processes. Major oxides of the granitoid vary lowly from the average background values derived for basin type granitoid in such terrains. Generally, the granitoid are enriched in Large Ion Lithophile Elements (LILE), while High Field Strength Elements (HFSE) and base metals are within background values when compared to Primitive Mantle (PM) values. Gold mineralisation is associated with Ag, As, Bi, Sb, Te, Pb and S in the peraluminous granitoids. Geochemical characteristics and field observations identify the deposit style as an orogenic related gold deposit type.

Whole genome sequence analysis reveals genetic structure and X-chromosome haplotype structure in indigenous Chinese pigs

Chinese indigenous pigs exhibit considerable phenotypic diversity, but their population structure and the genetic basis of agriculturally important traits need further exploration. Here, we sequenced the whole genomes of 24 individual pigs representing 22 breeds distributed throughout China. For comparison with European and commercial breeds (one pig per breed), we included seven published pig genomes with our new genomes for analyses. Our results showed that breeds grouped together based on morphological classifications are not necessarily more genetically similar to each other than to breeds from other groups. We found that genetic material from European pigs likely introgressed into five Chinese breeds. We have identified two new subpopulations of domestic pigs that encompass morphology-based criteria in China. The Southern Chinese subpopulation comprises the classical South Chinese Type and part of the Central China Type. In contrast, the Northern Chinese subpopulation comprises the North China Type, the Lower Yangtze River Basin Type, the Southwest Type, the Plateau Type, and the remainder of the Central China Type. Eight haplotypes and two recombination sites were identified within a conserved 40.09 Mb linkage-disequilibrium (LD) block on the X chromosome. Potential candidate genes (LEPR, FANCC, COL1A1, and PCCA) influencing body size were identified. Our findings provide insights into the phylogeny of Chinese indigenous pig breeds and benefit gene mining efforts to improve major economic traits.

The Morrison Formation and its bounding strata on the western side of the Blanding basin, San Juan County, Utah

In 2016 and 2017, the Utah Geological Survey partnered with the U.S. Bureau of Land Management to conduct a paleontological inventory of the Morrison Formation south and west of Blanding, Utah, along the eastern margin of the Bears Ears National Monument. The Morrison in this region is critical to understanding Upper Jurassic stratigraphy across the Colorado Plateau because it is the type area for the Bluff Sandstone, Recapture, Westwater Canyon, and Brushy Basin Members of the Morrison Formation, which are the basis for nomenclature in New Mexico and Arizona as well. Researchers have disagreed about nomenclature and correlation of these units, which transition northward in the study area into the Tidwell, Salt Wash, and Brushy Basin Members. Numerous vertebrate localities make inclusion of the Bluff Sandstone and Recapture Members in the Middle Jurassic San Rafael Group, as suggested by some previous workers, unlikely. The Salt Wash Member does not separate the Bluff Sandstone and Recapture Members at Recapture Wash, but sandstone lenses of Salt Wash facies occur higher in northern Recapture exposures. Northward, along the outcrop belt east of Comb Ridge, the Bluff-Recapture interval thins, interlenses, and pinches out into the Tidwell and lower Salt Wash, with the main lower sandstone interval of the Westwater Canyon merging northward into the upper Salt Wash Member.
 The partly covered, 1938 type section of the Brushy Basin Member is identified along Elk Mountain Road at the southern end of Brushy Basin. We describe a detailed, accessible Morrison Formation reference section about 11.2 km (7 mi) to the south along Butler Wash. There, 81.68 m (268 ft) of Brushy Basin Member is well exposed along a road between the top of the Westwater Canyon Member and the base of the Lower Cretaceous Burro Canyon Formation. We informally call the upper sandstone bed(s) of the Westwater Canyon Member that cap mesas and benches in the region “No-Mans Island beds.” Smectitic mudstones between the No-Mans Island beds and the main sandstone body of the Westwater Canyon suggest that the Salt Wash-Brushy Basin contact to the north may be somewhat older than the base of the Brushy Basin Member as originally defined in its type area. Determining whether the No-Mans Island beds pinch out to the north or are removed by erosion below the regional basal Brushy Basin paleosol requires further research. Several significant fossil vertebrate and plant sites have been documented in the Brushy Basin type area. Newly identified volcanic ashes provided zircons for U-Pb ages of 150.67 ± 0.32 Ma from near the top of the Brushy Basin Member and of 153.7 ± 2.1 Ma and 153.8 ± 2.2 Ma for two zircons in lower part of Recapture Member. At the top of the Brushy Basin Member, ferruginous paleosols commonly overlying conglomeratic sandstone are speculated to be of Early Cretaceous age (detrital zircon age pending) and are assigned herein to the Yellow Cat Member of the Burro Canyon Formation. These iron-rich paleosols suggest wetter climatic conditions during the Jurassic-Cretaceous transition in the Blanding basin.

Morpho-lithostructural analysis of Ala River basin for flood risk assessment: geospatial techniques intervention

An integrated approach of morphometric and litho-structural studies for flood risk assessment of Ala River Basin (ARB) in Akure city, southwestern Nigeria aided by geospatial techniques was carried out. The Ala River Basin comprises of four sub-basins covering a total area of 427km2 with fourth stream order of dendritic and sub-trellis drainage patterns. The values obtained for the morphometric features such as Form Factor, Circularity Ratio, Elongation Ratio, Stream Frequency, and Relief Ratio and Compactness Coefficient for ARB revealed an elongated basin type, posing a great flood threat to the urban community. Drainage density for all the sub-basins is very low, typically a coarse type that supports ample time for overland flow. All the lithological units are characteristically impermeable with low lineaments density. Thinness of the soil profile, and frequency of stream flow showed good relation to low infiltration with attendant high runoff leading to flood events in the upstream section. Flood sub-basin wise prioritization was carried out by employing the result obtained from morphometric classification and structural analysis. Different weightages were assigned to the different morphometric and structural parameters for the four sub-basins based on flood potentials. Ala River sub-basins have been classified into three namely; high, moderate and low based on flood potentials. The sub-basin I and II located at the upstream section are highly vulnerable to floods, while sub-basin III and IV located at the downstream section are not presently vulnerable to flooding respectively. The flood water in the flood threatened sub-basins (I and II) can also be harvested through siting and construction of natural groundwater recharge structures such as check dams and contour bunds.

The effect of basin geometry on gravitational vortex hydropower

This study aims to determine the shape of the conical basin that is suitable to be applied to the gravitational vortex hydropower (GVHP) by observing the shifting location of the core of water vortex. Three types of basin that will be observed are: a basin with cylindrical height of 20 mm (type A); a basin with conical height of 20 mm and cone angle of 60° (type B); and a basin with conical diameter of 50 mm, conical height of 20 mm, and cone angle of 45° (type C). There are two methods which were used, the analytical method was used to determine geometric parameters which affect water vortex formation, and then the numerical method was performed using computational fluid dynamics (CFD) with multiphase, transient-SST, and steady-state condition. Highest velocity was achieved with conical basin type B which will form a strong water vortex formation. If the velocity gets higher, the pressure will also drop. Velocity gets higher gradually until it reaches the outlet, which in turn causing pressure to drop gradually as well. This will create pressure differences which will cause a suction effect and form a strong water vortex. Thus, the conical basin (type B) was concluded to be a basin which creates a good water vortex formation.

Exergoeconomic and enviroeconomic analyses of single slope solar desalination unit loaded with/without nanofluid: A comprehensive review

The exergoeconomic and the enviroeconomic analyses of basin type single slope distiller unit based on solar energy can play an important role for mitigating the contemporary problem of acute shortage of drinking water throughout the world particularly developing and under developed countries. The technology of solar distiller unit has been known to humankind since the 16th century; however, it has not been preferred for purifying water on a large scale till date because of low potable water output, high initial investment, and non-availability of a technician at the local level. This technology is simple in nature and has the potential to mitigate the drinking water shortage; however, it has not been fully explored so far. A lot of configurations have been reported by various researchers since the development of solar distiller unit technology. This paper summarizes some of the important contributions reported so far on the basis of exergoeconomic and enviroeconomic parameters of single slope solar desalination units by incorporating the effect of nanofluid. A comparative study has been presented followed by a detailed discussion about exergoeconomic and enviroeconomic parameters of a single slope solar desalination unit loaded with/without nanofluid. It has been observed that the application of water-based nanofluid in the distiller unit results in the enhancement of performance. At last, the future scope has been presented.

Controls of a strike-slip fault system on the tectonic inversion of the Mahu depression at the northwestern margin of the Junggar Basin, NW China

The marginal fault system, which is represented by the Hong–Che (Hongshanzui–Chepaizi), Ke–Bai (Karamay–Baikouquan), and Wu–Xia (Wuerhe–Xiazijie) sub-systems and developed in the northwestern margin of the Junggar Basin, NW China, is a key factor affecting the development characteristics of the Permian–Triassic strata and controlling the hydrocarbon accumulation in the area. In this study, based on the latest two-dimensional and three-dimensional seismic exploration data, regional geological background, and previous research results, the attributes and timing of this structural belt of the NW margin as well as the basin type related to it are clarified. The result shows that the above marginal fault system has dextral strike–slip features and is characterized by a high-angle master fault, branch faults, and short-axis plunging anticlines in an en échelon arrangement. The tectonic deformation is classified into two main periods: late Permian tectonic inversion and late Triassic reactivation. It is found that the late Permian tectonic inversion led to the migration of the depocenter in the Mahu Depression and was induced by the counterclockwise rotation of the Junggar block and West Junggar area relative to the western part of the Chingiz range in the late Paleozoic. The nose structures, fault blocks, and en échelon anticlines derived from the relevant thrust faulting and folding may account for the development of the main structural traps, which play an important role in the hydrocarbon accumulation in the NW margin of the Junggar Basin.

Charcoal characterization and application is solar evaporator for seawater desalination

Solar desalination is the most attractive and simple technique for desalination process but suffers low thermal efficiency. The objective of this research is to study the effect of charcoal in seawater desalination for clean water production. The experiment was conducted in a basin type solar evaporator by using seawater with charcoal to seawater mass ratio variation of 1:50 to 1:500. The investigation was carried out for eight hours in sunny daylight. The water qualities including pH, conductivity, total dissolve solid (TDS), chemical oxygen demand (COD) and turbidity of the seawater and amount of evaporated water were determined. The spent and fresh charcoals were also characterized by using Nitrogen Adsorption (BET), X Ray Detector (XRD) and Scanning Electromagnetic Microscope (SEM). It is found that the addition of charcoal in the water leads to20 % increment of water temperature. Charcoal’s exposed area to the energy source significantly affects the temperature raise. The best charcoal to water mass ratio was achieved at 1:100 to produce 16.8% evaporated water. Charcoal was stable in seawater because minimum changes of pore size and pore volume were observed. In conclusion, charcoal is a potential salt adsorbent and medium for solar thermal energy storage for seawater solar desalination process.

Augmentation of diurnal and nocturnal distillate of solar still having wicks in the basin and integrated with solar pond

In present study, the conventional basin type solar still was modified using solar pond and floating wicks in the basin to increase the yield of the still. Solar pond was used to store the energy absorbed during day time and provide that energy to the basin during night to produce nocturnal distillate. For enhancing the evaporation rate of basin water, floating wicks were used in the modified still. To study the effect of solar pond and floating wicks under similar weather and operating conditions, the performance of both the stills were compared. The effects of using solar pond and floating wicks on the yield output of solar still have been investigated. The modified still performed better when basin was incorporated with wicks and couple with solar pond during night. The wicks helped to enhance the diurnal distillate and solar pond enhanced the night productivity. A distillate of 3864 g and 2288.9 g was obtained for day and night respectively for modified still. While distillate of 2533 g and 1474 g was obtained during day and night respectively for conventional still. The gain in diurnal and nocturnal distillate of modified still over the conventional still was found to be 52% and 55% respectively. It can be observed from the study that solar pond contributed in nocturnal distillate and floating wicks contributed in diurnal distillate. In lieu of this, the overall gain productivity of proposed still was found to be 53.5%.

Geology, alteration system, and uranium metallogenic potential of Pasha-Ladoga Basin, Russia

The Mesoproterozoic Pasha-Ladoga Basin is located at the margin of the Karelian Craton and Svecofennian Belt in northwest Russia. It is the only basin in Russia that is currently recognized to host unconformity-type uranium mineralization (e.g., Karku deposit). Mineralization is associated with the Priozersk Formation which comprises a basal sequence of immature arkosic sandstones and conglomerates interpreted as high-energy braided stream channel and channel bar facies within an alluvial fan depositional environment. Diagenetic and hydrothermal alteration of the Priozersk sandstones is similar to that observed in unconformity-related uranium deposits of the Athabasca Basin (Canada) and includes three main stages: (1) an early diagenetic assemblage comprising illite-smectite (K-rectorite), calcite, minor chlorite, and kaolinite precipitated at 100–150 °C; (2) a peak diagenetic-hydrothermal assemblage composed of kaolinite-dickite, Fe- and Fe-Mg chlorite, calcite, and sulfides formed at 150–250 °C; (3) late diagenetic-hydrothermal event involving fracture-controlled kaolinite and late hematite. Similar to the Athabasca Basin type uranium mineralization, the Karku deposit exhibits anomalous concentrations of LREE, Nb, Pb, and positive correlations between U and Cu, Zn, Ag, and Pb that is a geochemical signature of unconformity-type uranium mineralization. Based on oxygen and hydrogen stable isotope study, it was found that fluids in equilibrium with early and peak diagenetic clays were consistent with oxidized basinal brines and reduced basement fluids. In contrast to the Athabasca Basin, mineralizing fluids at the Karku area were more reduced and potassic. A new geological model for the Karku deposit is proposed based on petrographic observations and sandstones geochemistry. The proposed model envisages the permeable rocks of paleoregolith and the coarse-grained basal part of the Priozersk Formation as the main pathway for migration of uraniferous fluids responsible for the formation of Karku uranium deposit. From the perspective of the geological setting, the Karku deposit differs from deposits of the Athabasca Basin in that it occurs in a rapidly deposited rift-related basin with associated mafic magmatism, the host sandstone sequence is relatively thin (e.g., Priozersk Formation) and exhibits abrupt lateral facies variations, and the widespread presence of early diagenetic interstitial swelling clays. Based on these sedimentological characteristics, it is considered that the Karku deposit setting precludes optimum conditions to create high tonnage high-grade unconformity-type U deposits as found in the Athabasca basin.

Effect of water depth and insulation on the productivity of an acrylic pyramid solar still – An experimental study

Evaporation and condensation rate directly depend on the surface area provided in the solar still. Considering that, pyramid solar still provides greater surface area than basin type still for condensation process and gives out high performance. In this research work, the pyramid solar still is researched by varying the water depth from 1 to 3.5 cm with and without insulation conditions. The performance of the pyramid solar still with insulation is greater than the without insulation. Insulation plays an important role to increase the yield by increasing the water temperature. The yield produced from the pyramid solar still was higher at the lowest water depth of 1 cm for both insulation and un-insulated condition. The freshwater production from the pyramid solar still without insulation is 3.27, 2.93, 2.26, and 1.59 kg/m2 and with insulation is 3.72, 3.40, 2.70, and 2.08 kg/m2 for the water depth of 1, 2, 3, and 3.5 cm, respectively. At 1 cm water depth, the pyramid solar still with and without insulation produced 19.46% and 8.26% higher yield than the single basin type solar still.The daily efficiency of solar still is improved to about 28.5% with insulation whereas, the daily efficiency for solar still without insulation is found as 26.17%.

Energy Dissipation in Solid Roller Bucket and Controlled Stilling Basin for Ogee Stepped Spillway

Hydraulic jump type II stilling basin is generally preferred as an energy dissipator for ogee spillway but it is uneconomical due to longer structure. On the other hand, roller bucket uses relatively shorter structure over a sloping apron or horizontal stilling basin. In this study, an attempt has been made to evaluate the performance of an ogee profile stepped spillway in combination with solid roller bucket and stilling basin type II for energy dissipation. Laboratory experiments are performed on a physical working model of ogee profile stepped spillway at discharge ranging from 0.0032 to 0.0069 m3/s for a head of 1.5m, 4m & 7m and the results compared for energy dissipation (non-dimensional parameter (yc / h) = 0.69). The model results show that stepped spillway model without v-notch achieves 92.40 % energy dissipation. Thus this model is found to be more suitable to acquire the ideal condition of sequent depth and tail water depth in stilling basin for all the discharges.