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1
Jasron, Jahirwan Ut, Sudjito Soeparmani, Lilis Yuliati e Djarot B. Darmadi. "Comparison of the performance of oscillating water column devices based on arrangements of water columns". Journal of Mechanical Engineering and Sciences 14, n. 3 (28 settembre 2020): 7082–93. http://dx.doi.org/10.15282/jmes.14.3.2020.10.0555.
Testo completoAbstract (sommario):
The hydrodynamic performance of oscillating water column (OWC) depends on the depth of the water, the size of the water column and its arrangement, which affects the oscillation of the water surface in the column. An experimental method was conducted by testing 4 water depths with wave periods of 1-3 s. All data recorded by the sensor is then processed and presented in graphical form. The research focused on analyzing the difference in wave power absorption capabilities of the three geometric types of OWC based on arrangements of water columns. The OWC devices designed as single water column, the double water column in a series arrangement which was perpendicular to the direction of wave propagation, and double water column in which the arrangement of columns was parallel to the direction of wave propagation. This paper discussed several factors affecting the amount of power absorbed by the device. The factors are the ratio of water depth in its relation to wavelength (kh) and the inlet openings ratio (c/h) of the devices. The test results show that if the water depth increases in the range of kh 0.7 to 0.9, then the performance of the double chamber oscillating water column (DCOWC) device is better than the single chamber oscillating water column (SCOWC) device with maximum efficiency for the parallel arrangement 22,4%, series arrangement 20.8% and single column 20.7%. However, when referring to c/h, the maximum energy absorption efficiency for a single column is 27.7%, double column series arrangement is 23.2%, and double column parallel arrangement is 29.5%. Based on the results of the analysis, DCOWC devices in parallel arrangement showed the ability to absorb better wave power in a broader range of wave frequencies. The best wave of power absorption in the three testing models occurred in the wave period T = 1.3 seconds.
2
Igra, D., e K. Takayama. "Experimental Investigation of Two Cylindrical Water Columns Subjected to Planar Shock Wave Loading". Journal of Fluids Engineering 125, n. 2 (1 marzo 2003): 325–31. http://dx.doi.org/10.1115/1.1538628.
Testo completoAbstract (sommario):
Two water columns with identical initial diameters of 4.8 mm were placed 30 mm apart inside a shock tube test section and were loaded by a shock wave of Mach number 1.47 in atmospheric air. The Weber and Reynolds numbers corresponding to these flow conditions are 6900 and 112,000, respectively. Double-exposure holographic interferometry was used to visualize the shock/water columns interaction. The process of the water columns deformation, displacement, and acceleration was well visualized and hence the drag coefficient of shock loaded water columns was evaluated. The front water column behaved virtually the same as a single water column under the same flow conditions. However, the displacement and acceleration of the rear water column was less significant than that of the front one. Hence, its drag coefficient is less. These results show that the front water column has affected the flow field around the rear water column.
3
Durkee, John B. "The Water Column". Metal Finishing 105, n. 9 (settembre 2007): 57–59. http://dx.doi.org/10.1016/s0026-0576(07)80221-2.
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Bauer, Rachel, Paul Pitzel, Emily Johnson e Catherine Johnson. "Water-Cased Kicker Charges for Use in Explosive Demolition". Buildings 13, n. 2 (29 gennaio 2023): 378. http://dx.doi.org/10.3390/buildings13020378.
Testo completoAbstract (sommario):
Demolition projects involving explosives often incorporate cutting charges to sever columns in conjunction with kicker charges that “move” the columns out of alignment. Traditional kicker charges use dynamite secured to the column above a linear-shaped cutting charge. This study investigates the use of water-cased kicker charges for use in explosive demolition. The goal is to reduce the fragmentation of steel members and the quantity of explosive needed due to the increased density, incompressibility, and impedance mismatch water provides. Simulations and experimental tests were utilized to determine what type of charges provide the optimal column movement and water placement. Water charges and traditional charges were placed on hanging steel columns that swung freely from a top pivot and analyzed for the fragmentation and velocity of the column. Tests were recorded with high-speed video to calculate velocity and impulse. Simulations showed the same results as experimental tests, with water-cased charges moving the column faster and with more impulse than traditional charges. Experimental testing showed that water-cased charges moved the column 53% faster than traditional in contact charges while simulations showed that water-cased charges moved the column 43% faster than traditional in contact charges. Simulations showed the water tamped behind the charge increased beam velocity 32% while water in front of the charge reduced pressure 38% through dispersion.
5
Takahashi, Hisayuki, e Masayasu Tanaka. "Statistical Analysis for Comparison of the Results Obtained by Capillary Columns and Packed Columns in the Determination of Water Yield in Smoke Condensates Analyzed in Cigarettes for the 24th Asia Collaborative Study". Beiträge zur Tabakforschung International/Contributions to Tobacco Research 29, n. 2 (25 settembre 2020): 97–118. http://dx.doi.org/10.2478/cttr-2020-0010.
Testo completoAbstract (sommario):
SummaryRecently, capillary columns have been widely used in the methodology for the determination of water yields in smoke condensate, even though ISO 10362-1:1999, “Cigarettes - Determination of water in smoke condensates – Part 1: Gas chromatographic method” specifies a packed gas chromatographic column. As a result of a systematic review in 2015, ISO/TC126 decided to revise the standard to include the use of capillary columns.The goal of this study was to confirm the comparability of water yields obtained from capillary column methodology to those yields from packed columns by the statistical analysis of yield data from the 24th Asia Collaborative Study which included 86 datasets submitted by 64 laboratories. After the exclusion of outliers by Cochran’s and Grubbs’ tests, the datasets were classified by GC column type and then mean water yields, and their repeatability and reproducibility were calculated for each type of column. No significant differences were observed in water yields between capillary and packed columns. Repeatability and reproducibility of water yields using capillary column were comparable to those using packed columns as described in ISO 10362-1:1999. From these results, it was confirmed that the capillary columns are an appropriate alternative to packed columns for the gas chromatographic procedure described in ISO 10362-1:1999.
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Zhang, Zhen Peng, Jin Qiu Shao, Xue Yan Sun e Hui Jun Liu. "Simulation of Soil Water and Salt Transport with Sand Column in Coastal Saline Soil Based on COMSOL". Applied Mechanics and Materials 614 (settembre 2014): 668–71. http://dx.doi.org/10.4028/www.scientific.net/amm.614.668.
Testo completoAbstract (sommario):
In the paper, transport of water and Cl- under leaching was 2D-digitally simulated with COMSOL Multi-physics. In a two-dimensional transient cross-sectional model. COSMOL was used to investigate water and solute transport in the soil column coupled with variable sand column forms, with “a” denoting no sand column, “b” with one vertical middle sand column, “c “ with one long Slanted sand column, “d” with two long Slanted X-shaped sand columns. The parameters of the model were primarily based on the soil physical properties measured at coastal clay loam saline soil in Tianjin. The simulation results showed that, given same initial and same boundary conditions, sand column increased the transport efficiency of water and salt, which depends on the position and angle of sand column accordingly. The slanted columns were overall superior to the vertical ones in transport efficiency. In sum, “d” was the best type, “c” was the second best and “b” was the third, according to the efficiency of salt leaching and the efficiency of the utilization of water resources.
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Maimon, Dan. "Oscillating water column plant". Analele Universităţii "Dunărea de Jos" din Galaţi Fascicula XI Construcţii navale/ Annals of "Dunărea de Jos" of Galati Fascicle XI Shipbuilding 44 (3 dicembre 2021): 47–50. http://dx.doi.org/10.35219/annugalshipbuilding/2021.44.07.
Testo completoAbstract (sommario):
This article is describing the way of construction and operation of an oscillating water column system in order to recover as much as possible from the waves energy. The oscillating water column plant is used for the production of electrical energy by tidal currents, and it is currently the most widespread and economical method for the conversion of wave motion. The environmental impact of these infrastructures remains very low: no emissions of gas or any waste during their operation. In addition, the swell is a formidable source of energy.
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Winton, Michael. "Polar Water Column Stability". Journal of Physical Oceanography 29, n. 6 (giugno 1999): 1368–71. http://dx.doi.org/10.1175/1520-0485(1999)029<1368:pwcs>2.0.co;2.
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Bader, Amjed M., Dhia A. Alazawi, Hussain J. M. Al-Alkawi e Saad T. Faris. "Effect of shot peening on the critical buckling load of stainless steel 304 columns immersed in sea water". Curved and Layered Structures 9, n. 1 (1 gennaio 2022): 442–50. http://dx.doi.org/10.1515/cls-2022-0181.
Testo completoAbstract (sommario):
Abstract A machine part subjected to an axial compressive load is called strut. But, a vertical strut is known as a column. The machine members that must be investigated for the column action are connecting rods, piston rods, screw jack, etc. When a column is subjected to a compressive load and this load is gradually increased, a stage will be reached when the column will be subjected to ultimate load. Beyond this, the column will fail by crushing, and the load will be known as crushing load. When the column is short or intermediate, sometimes this column fails by bending, i.e. buckling. When the column is long, the value of buckling load is low for long columns and is relatively high for intermediate columns. The present investigation focuses on the testing and evaluation of the mechanical end buckling columns (samples) using 304 stainless steel under dry, corrosion, and combined dry with shot peening (SP) process. The buckling behavior of the axial compressive load has been studied experimentally and theoretically using Euler and Rankin theories. The results obtained from the above study manifested that the column, whose slenderness ratio (SR) is more than 120, is denoted as the long column, and the Euler theory can be successfully used. But, when the SR is less than 120, the column is known as an intermediate one. The mechanical and buckling properties exhibited a reduction due to the corrosion media and a reasonable improvement when using SP.
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Raeva, V. M., e O. V. Gromova. "Separation of water – formic acid – acetic acid mixtures in the presence of sulfolane". Fine Chemical Technologies 14, n. 4 (15 settembre 2019): 24–32. http://dx.doi.org/10.32362/2410-6593-2019-14-4-24-32.
Testo completoAbstract (sommario):
In this paper, extractive distillation flowsheets for water–formic acid–acetic acid mixtures were designed. Flowsheets not involving preliminary dehydration were considered, and the relative volatilities of the components in the presence of sulfolane were analyzed. The result of extractive distillation depends on the amount of sulfolane. The structure of the flowsheet is determined by the results of the basic ternary mixture extractive distillation. In three-column flowsheets (schemes I, II), water is isolated in the distillate of the extractive distillation column. In the second column, distillation of the formic acid–acetic acid–sulfolane mixture is carried out, yielding formic acid (90 wt %) and acetic acid (80 wt %). The recycled flow is returned to the first column. Dilution of the formic acid–acetic acid–sulfolane mixture with sulfolane (second column of flowsheet II) allows for acids of higher quality (main substance content equal to or more than 98.5 wt %) to be obtained. Flowsheet III includes four columns and two recycling stages. First, the water–formic acid mixture is isolated in the distillate of the extractive distillation column. Then, water and formic acid are separated in a two-column complex by extractive distillation, also with sulfolane. We were carrying out calculations for column working pressure 101.32 and 13.33 kPa. To prevent thermal decomposition of sulfolane, working pressure for regeneration columns was always 13.33 kPa. The extractive distillation column of the basic three-component mixture is the main factor contributing to the total energy consumption for separation (in all schemes).
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Kh Kurbangaleeva, M. "Improving the Safety of the Rectification Unit for the Production of Alkylphenols". IOP Conference Series: Earth and Environmental Science 988, n. 2 (1 febbraio 2022): 022007. http://dx.doi.org/10.1088/1755-1315/988/2/022007.
Testo completoAbstract (sommario):
Abstract As a result of the study, the analysis of occurrence of fire hazardous situation during the operation of rectification column of production facility of one of the city’s enterprises was carried out. This installation refers to facilities for which additional safety requirements are imposed. The main danger of the operation of rectification columns and their piping used at the installation is thefear of depressurization and theinitiation of gas contamination and fire situation on the site. As theresult of the fire, the rectification column and supporting metal structures can be in flame or be under the influence of thermal radiation from the flame in adjacent column, which can lead to the collapse of structures or to losses of bearing capacity under the influence of high temperatures. Depending on the height of the column, the water supply system can have different ways of distributing water: at small height of the column, manual water nozzles are used with the use of fire hydrants; at considerable height of the columns, stationary water irrigation systems (irrigation rings) are used.
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Jandera, Pavel, e Tomáš Hájek. "A New Definition of the Stationary Phase Volume in Mixed-Mode Chromatographic Columns in Hydrophilic Liquid Chromatography". Molecules 26, n. 16 (9 agosto 2021): 4819. http://dx.doi.org/10.3390/molecules26164819.
Testo completoAbstract (sommario):
Polar columns used in the HILIC (Hydrophilic Interaction Liquid Chromatography) systems take up water from the mixed aqueous–organic mobile phases in excess of the water concentration in the bulk mobile phase. The adsorbed water forms a diffuse layer, which becomes a part of the HILIC stationary phase and plays dominant role in the retention of polar compounds. It is difficult to fix the exact boundary between the diffuse stationary and the bulk mobile phase, hence determining the column hold-up volume is subject to errors. Adopting a convention that presumes that the volume of the adsorbed water can be understood as the column stationary phase volume enables unambiguous determination of the volumes of the stationary and of the mobile phases in the column, which is necessary for obtaining thermodynamically correct chromatographic data in HILIC systems. The volume of the aqueous stationary phase, Vex, can be determined experimentally by frontal analysis combined with Karl Fischer titration method, yielding isotherms of water adsorbed on polar columns, which allow direct prediction of the effects of the composition of aqueous–organic mobile phase on the retention in HILIC systems, and more accurate determination of phase volumes in columns and consistent retention data for any mobile phase composition. The n phase volume ratios of 18 columns calculated according to the new phase convention strongly depend on the type of the polar column. Zwitterionic and TSK gel amide and amine columns show especially strong water adsorption.
13
Riddle, Steven W. "Functional morphology and paleoecological implications of the platycrinitid column (Echinodermata, Crinoidea)". Journal of Paleontology 63, n. 6 (novembre 1989): 889–97. http://dx.doi.org/10.1017/s0022336000036581.
Testo completoAbstract (sommario):
Flume studies conducted on models and specimens of the helically twisted columns from Mississippian platycrinitid crinoids revealed two unique hydrodynamic interactions. Water is deflected up the column from levels near the sediment-water interface where food particles are more abundant. Turbulence, both in the lee and on the upstream side of the column, removes nutrient-poor water and replaces it with nutrient-rich water from near the sediment-water interface. Subsequently, the nutrient-rich water would have been filtered through the feeding apparatus of the crinoid. An upward deflection of as little as 10 percent bottom water would have resulted in a substantial increase in food particle load. Thus, the form of platycrinitid columns gave the crinoid a feeding advantage over otherwise similar crinoids of the same time period. The most diverse and abundant group of Mesozoic–Cenozoic stalked crinoids shows similar column modifications which suggests that the morphology may impart some competitive advantage to the organism.
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Vuković, Gorica, Vojislava Bursić, Nikola Puvača, Tijana Stojanović, Bojan Konstantinović, Aleksandra Petrović e Dušan Marinković. "Solid-phase extraction of neonicotinoids residue from water: comparison between extraction cartridges". Environmental engineering 6, n. 2 (9 dicembre 2019): 84–89. http://dx.doi.org/10.37023/ee.6.2.6.
Testo completoAbstract (sommario):
The Commission Implementing Decision (EU) 2018/840 established the watch list of substances for Union-wide monitoring in the field of water policy pursuant to Directive 2008/105/EC and Commission Implementing Decision (EU) 2015/495. This Decision establishes additional substances and their maximum acceptable method detection limits including neonicotinoids (9-500 ng/L). During the pesticides extraction from water, the solid-phase extraction (SPE) column was used. Bakerbond spe™ SDB-1 SPE and Bond Elut Plexa were evaluated for the SPE of neonicotinoids (imidacloprid, thiamethoxam, acetamiprid, thiacloprid and clothianidin) from water. The comparation of the results of these two types of columns, was performed by spiking water samples at two levels (0.05 and 0.1 μg/L) in three replicates. The Bakerbond™ column quantitatively adsorbed these pesticides, with the obtained recoveries: 36.9 % for imidacloprid, 43.2 % for thiacloprid, 119.3 % for clothianidin, 64.6 % for acetamiprid and 53.6 % for thiamethoxam. Using Bond Elut Plexa the obtained recoveries were 66.9 % for imidacloprid, 72.9% for thiacloprid, 103.4 % for clothianidin, 67.4 % for acetamiprid and 45.2% for thiamethoxam. Both colums have low recovery values for thiametoxam, while the highest values were obtained by Bond Elut Plexa for thiacloprid, imidacloprid and acetamiprid. Great recoveries were achieved for clothianidin using both SPE columns.
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Chen, Chen-Yuan, Ruo-Ling Dong, Hong-Hui Shi e Yi Liu. "Instability and Atomization of Liquid Cylinders after Shock Wave’s Impacting". Applied Sciences 12, n. 24 (8 dicembre 2022): 12597. http://dx.doi.org/10.3390/app122412597.
Testo completoAbstract (sommario):
This paper describes an experimental study on the instability and atomization of liquid cylinders after the impact of shock waves. Single row water column, in-line double rows water columns and alongside triple rows water columns were evaluated in a horizontal shock tube. The diameter of water column and the Mach number in the experiments were 2.0–4.14 mm and 1.10–1.25, respectively. The global instability along the axial direction of water cylinders was focused. Using a high-speed camera, the developments of spike height, bubble depth and turbulent mixing zone, width were measured. Some comparison was also made between the present experimental results and the existing theoretical model.
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Cao, Zhengzheng, Yulou Ren, Qinting Wang, Banghua Yao e Xinchao Zhang. "Evolution Mechanism of Water-Conducting Channel of Collapse Column in Karst Mining Area of Southwest China". Geofluids 2021 (25 febbraio 2021): 1–8. http://dx.doi.org/10.1155/2021/6630462.
Testo completoAbstract (sommario):
There are many karst collapse columns in coal seam roof in the southern coal field in China, which are different from those in coal seam floor in the northern coal field, due to the stratum characteristics. The karst collapse column in coal seam roof tends to reactivate and conduct water and induce the serious water inrush disaster, when the karst collapse column communicates with the overlying aquifer. In order to reveal the evolution mechanism of water-conducting channel of collapse column in karst mining area of southwest China, the aquifers and water inflow rule in 1908 working face in Qianjin coal mine are analyzed. Besides, the particle size distribution and mineral component of collapse column are researched by the X-ray diffraction test and the screening method, which are the basis for researching the water inrush mechanism in karst collapse column. On this basis, the water inrush of roof collapse column under the influence of mining is researched by establishing the numerical calculation model with the UDEC numerical software. The results show that the water flowing into the 1908 working face comes from the Changxing formation aquifer and Yulongshan formation aquifer above the coal seam, and the proportion of coarse particles and fine particles in collapse column is 89.86% and 10.14%, respectively. With the advance of working face, the water-conducting channel connected the working face with the aquifer, or the surface is formed by collapse pits, karst caves, and collapse column. The research results can be treated as an important basis for the water-preserved mining in southern coal field in China.
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Thanh Hai, Pham Thi. "STUDY OF COPPER REMOVAL IN WATER BY ION EXCHANGE MATERIAL". Vietnam Journal of Science and Technology 56, n. 2C (29 agosto 2018): 50–55. http://dx.doi.org/10.15625/2525-2518/56/2c/13029.
Testo completoAbstract (sommario):
In this study, sulfonation of polystyrene waste was investigated of the possibility of the removing Cu (II) ions in solution. Fourier transform infrared (FTIR) of sulfonation polystyrene waste was performed to study the material characteristics and the results showed the presence of sulfonic group bands. The efficiency of Cu (II) ion removal in ion exchange column experiments indicated that the quality of sulfonation of polystyrene waste depended on some factors as the reaction time, height of the column and the velocity of the flow rate. Ion exchange experiments were carried out with the columns of 8 and 6 mm internal diameter, of which 10 cm of column bed height in the 8 mm-diameter column obtained the highest efficiency of 74.13 % at 1 hr reaction time, and flow rate of 1.48 mL per min. The experimental data were consistent with Thomas and Yoon-Nelson kinetic models.
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Kehr, Ján, e Mikuláš Chavko. "Protection, efficiency, and some practical aspects of use of CGC columns in high performance liquid chromatography". Collection of Czechoslovak Chemical Communications 51, n. 10 (1986): 2091–97. http://dx.doi.org/10.1135/cccc19862091.
Testo completoAbstract (sommario):
Some practical adaptations of compact glass cartridge (CGC) columns and design of related components of the high-performance liquid chromatographic system are suggested; included are the design of a Teflon guard column and its filling procedure, an intra-column sample injector for on-column sample delivery or for injection into the precolumn, replacement of a contaminated packing or replenishment of packing at the top of the CGC column, a procedure for shortening the column to a desired length, and the possibility of thermostatting the column by means of a water jacket. These adaptations make it possible to increase the lifetime of the CGC column as much as five times without loss of efficiency, and to use partly damaged or imperfectly packed columns.
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Lacombe, Celine, Suhail Butt, Graeme Mackenzie, Mark Schons e Raphael Bornard. "Correcting for water-column variations". Leading Edge 28, n. 2 (febbraio 2009): 198–201. http://dx.doi.org/10.1190/1.3086058.
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Li, Jiake, Laiyan Li, Wen Dong e Huaien Li. "Purification effects of amended bioretention columns on phosphorus in urban rainfall runoff". Water Science and Technology 78, n. 9 (8 novembre 2018): 1937–45. http://dx.doi.org/10.2166/wst.2018.464.
Testo completoAbstract (sommario):
Abstract In order to develop bioretention fillers with better phosphorus removal capacity, we built 12 bioretention columns with six kinds of modified fillers, and analyzed the operation effects of the columns under different conditions through field tests. Results show that adding water treatment residual has optimal removal rates for total phosphorus (TP) (median = 96.80%) and soluble reactive phosphorus (SRP) (median = 97.13%). The water reduction rates of the columns with improved fillers are 1.23–2.04 times that of the bioretention soil media column. The coconut chaff column has the best water storage capacity (median = 40.54%). Among the external factors affecting column operation, influent concentration of pollutants in urban surface runoff is the biggest influence factor on the removal efficiency of TP. However, there are no significant correlations between the removal efficiency of SRP and rainfall, influent concentration, and discharge ratio. The columns modified with medical stone, vermiculite, peat soil, medical stone + peat soil, green zeolite + peat soil all have good removal for phosphorus pollutant. After entering the columns, the contents of TP and SRP in most columns increased. The recommended fillers and the accumulation performance of phosphorus can help to improve purification effects in bioretention systems.
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Liu, Feifei, Xuesong Mao, Cheng Xu, Yingying Li, Qian Wu e Jianxun Zhang. "“Covering Effects” under Diurnal Temperature Variations in Arid and Semiarid Areas". Advances in Civil Engineering 2020 (21 febbraio 2020): 1–12. http://dx.doi.org/10.1155/2020/7496182.
Testo completoAbstract (sommario):
“Covering effects” dominated by water vapor migration in arid and semiarid areas threaten the stability of engineering entities. To explore the “covering effects” dominated by water vapor migration under the influence of diurnal temperature variations, a series of one-side evaporation experiments were conducted. Characteristics of water vapor migration between the unsaturated loess soil column with and without a lid were compared in detail to illustrate the “covering effects” on water vapor migration, as were the effects of test time. Further, the characteristics of “covering effects” in loess and sand soil columns were compared. The results show that the “covering effects” formed in the loess soil column with a lid by cycling day and night temperature differences led water vapor to accumulate and condense beneath the lid. However, unlike the “covering effects” during freezing conditions that lead to a significant increase in the moisture content in the top layer, in this study, the moisture content in the top layer (0–8 cm) decreased. Although “soil lid” and the “soil covering effects” exist in both loess soil columns with and without lids, the “soil covering effects” for the former are much more obvious, and the moisture content in the upper part of the loess soil column (8–45 cm) shows a significant increase. By cycling day and night temperature differences, the “covering effects” or “soil covering effects” grew as the test time increased. Compared to the loess soil column, the “covering effects” in the sand soil column were extremely weak, and the moisture migration in the sand soil column was dominated by the downward movement liquid water. This paper illustrates the “covering effects” under the influence of diurnal temperature variations and reveals the mechanism of water vapor migration in subgrade soils in arid and semiarid areas.
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Li, Yong Jun, Hao Sun e Xiao Ming Li. "Development Law and Watery Features of Collapse Column in Pansan Mine". Applied Mechanics and Materials 737 (marzo 2015): 817–22. http://dx.doi.org/10.4028/www.scientific.net/amm.737.817.
Testo completoAbstract (sommario):
The collapse column is widely developed and distributed in North China coalfield, has been a threat for coal mine production safety. According to the existing collapse columns in pansan mine, using the combination with geology analyzing and geophysical exploration technology, the cause and development regularity of the collapse columns is discussed in a way of palaeogeographic and palaeoenvironment, the inner filling material features of the collapse columns in the coalfield are introduced, The watery features of collapse columns are studied. The results show that collapse columns have a law of zonation in the horizontal and vertical , and have a certain subsiding distance, collapse column widths ranging periphery have the peripheral edge of the impact zone and transition zone, In the collapse column, the cementation degree is poor at the top, highly compressed at the middle and relatively poor in the bottom. The top and middle sections are less in water bearing, the rich water in the bottom was caused by the vertically leakage recharge from Ordovician limestone in the deep. The research results provide scientific basis for the prevention of collapse column in coal mine.
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Saowapon, Matthew T., e Kevin B. Thurbide. "Adjustable column length using a water stationary phase in supercritical fluid chromatography". Canadian Journal of Chemistry 97, n. 10 (ottobre 2019): 722–27. http://dx.doi.org/10.1139/cjc-2019-0157.
Testo completoAbstract (sommario):
A novel method for adjusting the column length during analysis in capillary supercritical fluid chromatography (SFC) is introduced. The approach is based on using a water stationary phase that can be partially ejected (or replenished) from the column as desired, without physically removing the supporting hardware elements. By flowing cool air through a sleeve surrounding the column in a heated oven, an axial thermal gradient along the length of the column was formed. This established a cooler region where the water stationary phase could be maintained and a hotter region where the coating was removed through dehydration. As such, the effective column length could be easily adjusted by changing the gradient via the air flow rate. Using this prototype arrangement, column lengths could be readily varied between 1.4 and 10 m. System response was also fairly rapid and changes took effect in under 1 min. Once a given length was established, retention times were highly reproducible with a relative standard deviation of 1.8% (n = 3). The method is cheaper and faster than the conventional method of storing numerous columns for manual switching. Further, it avoids the convolution of system pressure and flow rate that accompanies the pressure adjustments normally used to optimize capillary SFC separations. Results indicate that this approach could be a useful alternative for adjusting column length to optimize separation speed and resolution.
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Dhawan, Sahil, Onita D. Basu e Bahman Banihashemi. "Influence of nutrient supplementation on DOC removal in drinking water biofilters". Water Supply 17, n. 2 (17 settembre 2016): 422–32. http://dx.doi.org/10.2166/ws.2016.146.
Testo completoAbstract (sommario):
Analysis of the impacts of nitrogen, phosphorus and potassium supplementation on biofilter performance for organic carbon removal was studied on laboratory-scale biofilter columns. Three dual media biofilter columns were fed with synthetic raw water C:N:P ratios of 546:24:1, 100:10:1, and 25:5:1 (w/w) to simulate nutrient limited and two nutrient supplemented conditions, respectively. Research found that air-scour versus water only backwash improved the nutrient limited dissolved organic carbon (DOC) removal by 8%. In addition, nutrient supplementation and backwash alteration improved DOC removals by 19% for the 25:5:1 column and 14% for the 100:10:1 column. Potassium supplementation with the 25:5:1 C:N:P ratio column had no discernible effect on DOC removal. No correlation with phospholipid (7–474 nmol P/g media) and adenosine triphosphate (ATP) (0.6 × 105–32.74 × 105 pg ATP/g media) values with DOC removal were found. Nutrient availability was found to influence DOC removal, demonstrating its importance when utilizing biofiltration for treatment of source waters.
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Xue, Yang, Huang Jingwu, Wang Hua, Liang Maoliang, Li Wei, Zhou Huaqun e Zuo Yongjiang. "Evaluation on water bursting risk of working faces near collapse column during the mining process". E3S Web of Conferences 198 (2020): 02003. http://dx.doi.org/10.1051/e3sconf/202019802003.
Testo completoAbstract (sommario):
Collapse column water bursting occurs from time to time in the coal mining process of North China Type Coalfield in China, which causes great economic loss and personal injury. Therefore, great attention must be paid to the harm of collapse column. 1301 working face and 1306 working face in the west wing of No.1 Mining District of Zhangji Coal Mine in Shanxian County are close to No.2 collapse column. Water bursting risk evaluation must be carried out before mining two working faces to ensure safety production. On the basis of fully analyzing the geological and hydrogeological conditions of the 3up coal seam in the west wing of No.1 Mining Area, the "Three Zones(caving zone, water conducted fracture zone and sagging zone) Theory of Coal Seam Roof", "Strata Movement Theory" and "Water Bursting Coefficient Theory" were used respectively to calculate and evaluate the water bursting risk of No.2 collapse column during the course of mining the 1301 working face and 1306 working face. The results show that: firstly, in the process of mining the 1301 working face, the maximum height of the water conducted fracture zone at the closest position of 1301 working face to No.2 collapse column would be 60.20 m, the water bursting coefficient on the boundary of water conducted fracture zone would be 0.066~0.072 MPa/m, and the water bursting risk of the No.2 collapse column would be smaller; secondly, in the process of mining the 1306 working face, the maximum height of the water conducted fracture zone at the closest position of 1306 working face to No.2 collapse column would be 60.91 m, the water bursting coefficient on the boundary of water conducted fracture zone would be 0.057~0.089 MPa/m, and the water burst risk of the No.2 collapse column would be small. By August 31, 2020, the 1301 working face had been safely mined more than 200 meters long(exceeding over 120 m of the closest position in 1301 working face to No.2 collapse column), and the water bursting did not happen in the working face. This paper can provide a reference for the water prevention and control of similar collapse columns in coal mines.
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Hildebrant, Benjamin, Arnaud Igor Ndé-Tchoupé, Mesia Lufingo, Tobias Licha e Chicgoua Noubactep. "Steel Wool for Water Treatment: Intrinsic Reactivity and Defluoridation Efficiency". Processes 8, n. 3 (26 febbraio 2020): 265. http://dx.doi.org/10.3390/pr8030265.
Testo completoAbstract (sommario):
Studies were undertaken to characterize the intrinsic reactivity of Fe0-bearing steel wool (Fe0 SW) materials using the ethylenediaminetetraacetate method (EDTA test). A 2 mM Na2-EDTA solution was used in batch and column leaching experiments. A total of 15 Fe0 SW specimens and one granular iron (GI) were tested in batch experiments. Column experiments were performed with four Fe0 SW of the same grade but from various suppliers and the GI. The conventional EDTA test (0.100 g Fe0, 50 mL EDTA, 96 h) protocol was modified in two manners: (i) Decreasing the experimental duration (down to 24 h) and (ii) decreasing the Fe0 mass (down to 0.01 g). Column leaching studies involved glass columns filled to 1/4 with sand, on top of which 0.50 g of Fe0 was placed. Columns were daily gravity fed with EDTA and effluent analyzed for Fe concentration. Selected reactive Fe0 SW specimens were additionally investigated for discoloration efficiency of methylene blue (MB) in shaken batch experiments (75 rpm) for two and eight weeks. The last series of experiments tested six selected Fe0 SW for water defluoridation in Fe0/sand columns. Results showed that (i) the modifications of the conventional EDTA test enabled a better characterization of Fe0 SW; (ii) after 53 leaching events the Fe0 SW showing the best kEDTA value released the lowest amount of iron; (iii) all Fe0 specimens were efficient at discoloring cationic MB after eight weeks; (iv) limited water defluoridation by all six Fe0 SW was documented. Fluoride removal in the column systems appears to be a viable tool to characterize the Fe0 long-term corrosion kinetics. Further research should include correlation of the intrinsic reactivity of SW specimens with their efficiency at removing different contaminants in water.
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Aqel, Ahmad, Soad S. Alzahrani, Asma’a Al-Rifai, Mohammed Alturkey, Kareem Yusuf, Zeid A. ALOthman e Ahmed-Yacine Badjah-Hadj-Ahmed. "Determination of Monoaromatic Hydrocarbons in Water Samples by Nano-Liquid Chromatography using a Composite Carbon Nanotubes- Lauryl Polymethacrylate Capillary Monolithic Column". Current Analytical Chemistry 16, n. 3 (15 maggio 2020): 223–33. http://dx.doi.org/10.2174/1573411014666180619144741.
Testo completoAbstract (sommario):
Background: This work reports a green analytical method for the determination of organic environmental pollutants using nano-liquid chromatography with a self-made column for rapid, sensitive, inexpensive and efficient analysis of BTX pollutants in water. The applications of monolithic nanoscale columns for quantitative analysis of environmental real samples are very limited in the literature. Methods: A capillary column containing a composite of multi-walled carbon nanotubes incorporated into a lauryl methacrylate-co-ethylene dimethacrylate porous monolithic polymer was fabricated for the determination of BTX pollutants in real water samples. Results: Baseline separation was accomplished at 0.4 µL/min flow rate with UV-detection set at 208 nm. Under the optimum conditions, the calibration curves were validated over the range of 1.0-500 µg/L with R2 more than 0.9992. The detection limits of benzene, toluene, o-xylene and m/p-xylene were 0.25, 0.05, 0.075 and 0.05 µg/L, respectively. After a simple extraction process with a theoretical preconcentration factor equal to 200, the recovery values in Milli-Q, tap and sea water samples were found to be ranged from 84.85 to 97.84% with %RSD less than 7.5. Furthermore, we reported a comparison between our prepared composite column with a commercial C18 silica based column which is the most used in such analytical field. Each column demonstrated its advantages from different analytical aspects. Conclusion: The application of monolithic columns and nano-scale LC for routine analysis of environmental samples is very promising as the use of monolithic capillary columns offers several advantages over conventional scale particulate packed columns.
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Abel, Chol D. T., Saroj K. Sharma, Ervin Buçpapaj e Maria D. Kennedy. "Impact of hydraulic loading rate and media type on removal of bulk organic matter and nitrogen from primary effluent in a laboratory-scale soil aquifer treatment system". Water Science and Technology 68, n. 1 (1 luglio 2013): 217–26. http://dx.doi.org/10.2166/wst.2013.242.
Testo completoAbstract (sommario):
The effect of hydraulic loading rate (HLR) and media type on the removal of bulk organic matter and nitrogen from primary effluent during soil aquifer treatment was investigated by conducting laboratory-scale soil column studies. Two soil columns packed with silica sand were operated at HLRs of 0.625 and 1.25 m/d, while a third column was packed with dune filtering material and operated at HLR of 1.25 m/d. Bulk organic matter was effectively removed by 47.5 ± 1.2% and 45.1 ± 1.2% in silica sand columns operated at 0.625 and 1.25 m/d, respectively and 57.3 ± 7.6% in dune filtering material column operated at 1.25 m/d. Ammonium-nitrogen reduction of 74.5 ± 18.0% was achieved at 0.625 m/d compared to 39.1 ± 4.3% at 1.25 m/d in silica sand columns, whereas 49.2 ± 5.2% ammonium-nitrogen reduction was attained at 1.25 m/d in the dune filtering material column. Ammonium-nitrogen reduction in the first 3 m was assumed to be dominated by nitrification process evidenced by corresponding increase in nitrate. Part of the ammonium-nitrogen was adsorbed onto the media, which was observed at higher rates between 3 and 5 m in silica sand column operated at HLR of 0.625 m/d and dune filtering material column operated at 1.25 m/d compared to 1.25 m/d silica.
29
Dong, Yanrong, Junzhen Di, Zhenhua Yang, Yuanling Zhang, Xianjun Wang, Xuying Guo, Zhennan Li e Guoliang Jiang. "Study on the Effectiveness of Sulfate-Reducing Bacteria Combined with Coal Gangue in Repairing Acid Mine Drainage Containing Fe and Mn". Energies 13, n. 4 (23 febbraio 2020): 995. http://dx.doi.org/10.3390/en13040995.
Testo completoAbstract (sommario):
In view of the characteristics of the high content of SO42−, Fe2+ and Mn2+ in acid mine drainage (AMD) and low pH value, based on adsorption and biological methods, coal gangue was combined with sulfate-reducing bacteria (SRB). On this basis, four dynamic columns, including Column 1 (SRB combined with spontaneous combustion gangue from the Gaode coal mine), Column 2 (SRB combined with spontaneous combustion gangue from Haizhou), Column 3 (SRB combined with gangue from Haizhou), and Column 4 (SRB combined with gangue from Shanxi), were constructed. The efficacy of four columns was compared by the inflow of AMD with different pollution load. Results showed that the repair effect of four columns was: Column 3 > Column 2 > Column 1 > Column 4. In the second stage of the experiment, the repair effect of Column 3 was the best. The average effluent pH value and oxidation reduction potential (ORP) value were 9.09 and –262.83 mV, the highest removal percentages of chemical oxygen demand (COD) and SO42− were 84.41% and 72.73%, and the average removal percentages of Fe2+, Mn2+ were 98.70% and 79.97%, respectively. At the end of the experiment, when deionized water was injected, the fixed effect of AMD in the four columns was stable and no secondary release appeared.
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THOMPSON, ERICA L., e HERBERT E. HUPPERT. "Granular column collapses: further experimental results". Journal of Fluid Mechanics 575 (marzo 2007): 177–86. http://dx.doi.org/10.1017/s0022112006004563.
Testo completoAbstract (sommario):
Experimental observations of the collapse of initially static columns of sand in axisymmetric and two-dimensional geometries are presented. The experiments were carried out using cylinders and rectangular tanks 30 to 60 cm tall, and cover aspect ratios between 0.5 and 20, where the aspect ratio is defined as the ratio of the initial height to horizontal extent of the column. The final positions of sand grains from different points initially on the outer surface of the columns are mapped. For all axisymmetric columns the point of maximum runout is found to originate from a point at fractional height 0.74 ± 0.03 of the initial vertical height of the column, independent of the aspect ratio. For two-dimensional columns the corresponding point is 0.65 ± 0.07. Collapses of columns of water-saturated sand into water display a different form of flow, which leads to there being no such well-defined point. In this case, grains from all but the innermost, basal areas of the initial column can end up in the outermost region of the final deposit. For collapses in air and aspect ratios greater than 1, the detail of the initial geometry is relatively insignificant in determining the shape of the final deposit. The results of this and previous studies thus have general applicability, even to situations with less initial symmetry. Movies are available with the online version of the paper.
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Shukla, Shubham, e M. V. Waghmare. "Strengthening of RC Column Using GFRP". International Journal for Research in Applied Science and Engineering Technology 10, n. 3 (31 marzo 2022): 1217–24. http://dx.doi.org/10.22214/ijraset.2022.40866.
Testo completoAbstract (sommario):
Abstract: In construction industry, engineers try to find new, better, economical material. Today there are several new techniques observed in the industry. In recent years, the construction industry has seen an increasing demand to reinstate, rejuvenate, strengthen and upgrade existing concrete structures. This may be attributed to various causes such as environment degradation, design inadequacies, poor construction practices, lack of regular maintenance, revision of codes of practice, increase in loads and seismic conditions etc. One of the technique used is the wrapping of damaged and newly constructed columns with GFRP. As GFRP has the properties like high strength, light weight, resistance towards chemicals and salt water, it can be moulded into complex shapes, requires low maintenance etc. The behaviour of fibre reinforced polymer on different shapes of column has been extensively studied, but much less is known about concrete in FRP confined damaged columns. In this project a total of 21 columns are casted, out of which 3 columns are conventional columns, 9 columns are damaged & 9 are newly constructed columns. The columns are wrapped with single, double and triple layer of GFRP. An average increase of 33.21% is observed in damaged single layer wrapped GFRP column and 51.64% in damaged double layer wrapped GFRP column and 62% in damaged triple layer wrapped GFRP column. Similarly, 46.93% of increase in newly constructed single layer wrapped GFRP column and 72.56% of increase in newly constructed double layer wrapped GFRP column and 90.23% of increase in newly constructed triple layer wrapped GFRP column. Keywords: GFRP, damaged column, newly constructed column.
32
Feng, Feisheng, Suping Peng, Pingjie Fu, Wenfeng Du e Dongjing Xu. "A Study on the Seepage Flow Characteristics and Disaster-Causing Mechanism of Collapse Column". Advances in Civil Engineering 2018 (30 settembre 2018): 1–9. http://dx.doi.org/10.1155/2018/7841649.
Testo completoAbstract (sommario):
Factors such as the hydrogeological conditions, the lithological characteristics of the columns’ components, and the lithological characteristics and stress conditions of the coal seam roof and floor are interrelated and jointly affect column collapse. In this study, the disaster-causing mechanism of column collapse was studied. Based on the system theory, a collapsed column is divided into the column and the surrounding fissure zone as two subsystems for analysis. And, the permeability coefficient of the broken rock under different conditions was measured by a self-designed equipment. The variations of the permeability coefficient for rock samples with different particle diameters, different axial pressures Pa, and different seepage velocities were further studied. Through phenomena analysis and experimental data processing, it was concluded that, under the same pressure state, smaller particle diameter meant smaller permeability coefficient; with the increase of axial pressure, the permeability coefficient decreased; and the larger the water flow velocity was, the smaller the permeability coefficient became. For particle diameter Φ = 2.5–5 mm or larger, the tiny particles formed by randomly washing and breaking in the water flow blocked some of the channels. For particle diameters smaller than Φ = 2.5–5 mm, the smaller permeability coefficient was attributed to the turbulence resulting from non-Darcy flow. The study on the permeability of the fractured rock mass clarified the mechanism of water inrush from the fissure zone of the collapsed column: the collapsed column itself was impermeable, and the permeability of the fissure zone around the collapsed column was related to the lithological characteristics of the rock within the fissure zone and the sequencing of rock strata. When mining coal in areas with collapsed columns, experiments on collapsed columns and fissure zones are prerequisites. This study has a certain referential value for coal mining in this region.
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Martínez-Martín, Francisco J., Víctor Yepes, Fernando González-Vidosa, Antonio Hospitaler e Julián Alcalá. "Optimization Design of RC Elevated Water Tanks under Seismic Loads". Applied Sciences 12, n. 11 (1 giugno 2022): 5635. http://dx.doi.org/10.3390/app12115635.
Testo completoAbstract (sommario):
This paper deals with the seismic column design of 35 elevated RC water storage tanks. Tanks comprise a top conic trunk reservoir, a column with variable hollow square cross-sections, and a shallow foundation on a sand layer. The five-column heights considered are 20, 25, 30, 35, and 40 m. The five tanks are subjected to seven degrees of seismic loading characterized by the reference peak ground acceleration in Eurocode 8. The elevated tanks are designed against the full prescriptions of Eurocode 2, Eurocode 8, and the Spaniard Structural Code of Practice. This includes variable loads for seismicity, wind, snow, etc., together with the action of self-weight and dead loads. The optimization design method considered is a variant of the old bachelor algorithm, an adaptive threshold acceptance method with a neighborhood move based on the mutation operator from genetic algorithms. Column results show the high nonlinearity of the problem since the horizontal seismic forces depend on the rigidity and height of the columns. The main features of the optimized tanks give guidance for the practical design of this kind of elevated RC water tank.
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Lorenz, Christian, Dirk Merten, Götz Haferburg e Georg Büchel. "Laboratory Investigations on the Interactions of Soil, Water and Microorganisms with Manganese". Advanced Materials Research 20-21 (luglio 2007): 311–14. http://dx.doi.org/10.4028/www.scientific.net/amr.20-21.311.
Testo completoAbstract (sommario):
Column experiments were carried out using contaminated geosubstrates and previously isolated Streptomyces strains from the former uranium mining area Ronneburg (Germany) to study transfer processes of heavy metals including radionuclides. Preliminary tests with comparatively low heavy metal and radionuclide contaminated surface material showed strongly elevated Mn concentrations up to 1060 #g/l after passage through inoculated columns. In contrast, the eluates of non inoculated columns showed, after a “first flush”, low Mn concentrations around 30 #g/l. Poisoned control columns showed decreasing concentrations after the “first flush” (maximum Mn release of 540 #g/l). Highest manganese release from the inoculated, non poisoned columns corresponded with strongly decreasing redox potentials (+200 to -270 mV), which probably indicates microbially catalysed manganese release through reductive processes. One of the strains isolated from the column material was identified as a potentially heavy metal resistant strain of Cupriavidus metallidurans. It showed tolerance of up to 30 mM Mn (II), however no aerobic Mn (IV) reduction processes were indicated.
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Alkhorshid, Nima, Gregório Araújo e Ennio Palmeira. "Geosynthetic Encased Column: comparison between numerical and experimental results". Soils and Rocks 44, n. 4 (21 novembre 2021): 1–12. http://dx.doi.org/10.28927/sr.2021.073121.
Testo completoAbstract (sommario):
The use of granular column is one of the ground improvement methods used for soft soils. This method improves the foundation soils mechanical properties by displacing the soft soil with the compacted granular columns. The columns have high permeability that can accelerate the excess pore water pressure produced in soft soils and increase the undrained shear strength. When it comes to very soft soils, the use of granular columns is not of interest since these soils present no significant confinement to the columns. Here comes the encased columns that receive the confinement from the encasement materials. In this study, the influence of the column installation method on the surrounding soil and the encasement effect on the granular column performance were investigated using numerical analyses and experimental tests. The results show that numerical simulations can reasonably predict the behavior of both the encased column and the surrounding soil.
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Jørgensen, P. H. "Examination of the Penetration of Enteric Viruses in Soils under Simulated Conditions in the Laboratory". Water Science and Technology 17, n. 10 (1 ottobre 1985): 197–99. http://dx.doi.org/10.2166/wst.1985.0110.
Testo completoAbstract (sommario):
In two different unsaturated soil columns percolated with artificial rainwater under simulated aerated conditions, transport of coxsackievirus B3 and adenovirus 1 below 3.5 cm under the soil surface could not be demonstrated. The viruses were applied to the columns as seeded sewage sludge. Under saturated conditions transport of water-suspended coxsackievirus B3 was faster in a soil column with sandy loam soil than in a diluvial sand column.
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Yang, Hong, H. Rahardjo, E. C. Leong e D. G. Fredlund. "A study of infiltration on three sand capillary barriers". Canadian Geotechnical Journal 41, n. 4 (1 agosto 2004): 629–43. http://dx.doi.org/10.1139/t04-021.
Testo completoAbstract (sommario):
The capillary barrier effect was investigated by conducting infiltration tests on three soil columns of fine sand over medium sand, medium sand over gravelly sand, and fine sand over gravelly sand. The barrier effect was verified in the underlying layer of coarser material, and the water-entry values of the coarser layers were confirmed to be nearly equal to the residual matric suctions of the soils. The coarser layer of gravelly sand, which had a lower water-entry value, was more effective in forming a barrier than the coarser layer of medium sand, which had a higher water-entry value. When the capillary barrier was comprised of a coarser layer of gravelly sand, there was more water stored in the finer layer at the end of the drying stage than when the capillary barrier was comprised of a coarser layer of medium sand. Non-equilibrium static conditions of pore-water pressure profiles were observed in the three soil columns, and a generalized ultimate pore-water pressure profile of a capillary barrier system was proposed. In addition, the final volumetric water contents versus matric suctions of the soils as measured from the soil columns were reasonably consistent with the soil-water characteristic curves (SWCCs) of the soils, suggesting that the drying SWCC of a soil could also be obtained from the drying process in a soil column (or a capillary open tube). The drying SWCC could be established from measurements in the soil column up to a height corresponding to two times the residual matric suction head of the soil.Key words: capillary barrier, soil column, soil-water characteristic curve, pore-water pressure, water content, matric suction.
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Suh, Jeong-Yul, Paul L. Brown e Gavin F. Birch. "Geochemical factors affecting leachate composition derived from soils in reclaimed lands using laboratory fresh and saline water column experiments". Marine and Freshwater Research 54, n. 7 (2003): 885. http://dx.doi.org/10.1071/mf02118.
Testo completoAbstract (sommario):
The present study compared the geochemistry of saline and freshwater percolating through columns containing soils sampled from reclaimed land adjoining Sydney Harbour, Australia. The investigation assessed the flux of contaminants from the soil and, hence, estimated the affect of reclaimed land (using construction waste or dredged sediment) on the adjoining aquatic environment. Leachate samples were collected weekly for 22 weeks and were monitored for pH, Eh (redox potential), electrical conductivity, dissolved oxygen, major elements and heavy metals. In the early stages of the experiment (until approximately Week 12), the concentrations of the major elements in water percolating from the two columns were similar. Differing pseudo-steady-state conditions were reached in the columns after approximately 14 weeks. Sodium and Cl are weakly sorbed onto surface sites of the material in the saline column. The exchange of Na with other cations results in an increase in the aqueous concentrations of Ca, K and Mg in this column. As the parallel field concentrations are considerably higher than those measured in the column experiments, and are much higher (by orders of magnitude) than those measured in seawater, results of the fresh and saline water column tests strongly indicate that elevated concentrations of trace metals probably enter the estuary by tidal action and during periods of rainfall.
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OBRYK, M. K., P. T. DORAN, J. A. HICKS, C. P. McKAY e J. C. PRISCU. "Modeling the thickness of perennial ice covers on stratified lakes of the Taylor Valley, Antarctica". Journal of Glaciology 62, n. 235 (7 giugno 2016): 825–34. http://dx.doi.org/10.1017/jog.2016.69.
Testo completoAbstract (sommario):
ABSTRACTA 1-D ice cover model was developed to predict and constrain drivers of long-term ice thickness trends in chemically stratified lakes of Taylor Valley, Antarctica. The model is driven by surface radiative heat fluxes and heat fluxes from the underlying water column. The model successfully reproduced 16 a (between 1996 and 2012) of ice thickness changes for the west lobe of Lake Bonney (average ice thickness = 3.53 m) and Lake Fryxell (average ice thickness = 4.22 m). Long-term ice thickness trends require coupling with the thermal structure of the water column. The heat stored within the temperature maximum of lakes exceeding a liquid water column depth of 20 m can either impede or facilitate ice thickness change depending on the predominant climatic trend (cooling or warming). As such, shallow (<20 m deep water columns) perennially ice-covered lakes without deep temperature maxima are more sensitive indicators of climate change. The long-term ice thickness trends are a result of surface energy flux and heat flux from the deep temperature maximum in the water column, the latter of which results from absorbed solar radiation.
40
Ding, Jiann-Yuan, e Shian-Chee Wu. "Transport of organochlorine pesticides in soil columns enhanced by dissolved organic carbon". Water Science and Technology 35, n. 7 (1 aprile 1997): 139–45. http://dx.doi.org/10.2166/wst.1997.0270.
Testo completoAbstract (sommario):
The objective of this study is to quantify the effects of humic acid solution infiltration on the transport of organochlorine pesticides (OCPs) in soil columns using a three-phase transport model. From experimental results, it is found that the dissolved organic carbon enhances the transport of OCPs in the soil columns. In the OCPs-only column, the concentration profiles of OCPs can be simulated well using a two-phase transport model with numerical method or analytical solution. In the OCPs-DOC column, the migrations of aldrin, DDT and its daughter compounds are faster than those in the OCPs-only column. The simulation with the three-phase model is more accurate than that with the two-phase model. In addition, significant decrease of the fluid pore velocities of the OCPs-DOC column was found. When DOC leachate is applied for remediation of soil or groundwater pollution, the decrease of mean pore velocities will be a crucial affecting factor.
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Autrique, R., e E. Rodal. "Laboratory studies of water column separation". IOP Conference Series: Materials Science and Engineering 52, n. 2 (20 dicembre 2013): 022022. http://dx.doi.org/10.1088/1757-899x/52/2/022022.
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Reygondeau, Gabriel, e Grégory Beaugrand. "Water column stability and Calanus finmarchicus". Journal of Plankton Research 33, n. 1 (10 agosto 2010): 119–36. http://dx.doi.org/10.1093/plankt/fbq091.
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Sklavenites, D. "Wave patterns on a water column". American Journal of Physics 65, n. 3 (marzo 1997): 225–30. http://dx.doi.org/10.1119/1.18533.
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Reunanen, Jarmo, Seppo Palosaari, Minoru Miyahara e Morio Okazaki. "Column adsorption in multi-solute water". Chemical Engineering and Processing: Process Intensification 32, n. 5 (ottobre 1993): 291–99. http://dx.doi.org/10.1016/0255-2701(93)85013-6.
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Raeva, V. M., e A. M. Dubrovsky. "Comparison of extractive distillation flowsheets for methanol–tetrahydrofuran–water mixtures". Fine Chemical Technologies 15, n. 3 (7 luglio 2020): 21–30. http://dx.doi.org/10.32362/2410-6593-2020-15-3-21-30.
Testo completoAbstract (sommario):
Objectives. Synthesis and comparative analysis of the extractive distillation flowsheets for aqueous mixtures of solvents utilized in pharmaceutical industries using the example of a methanol−tetrahydrofuran−water system with various compositions. The ternary system contains two minimally boiling azeotropes that exist in a vapor–liquid phase equilibrium. To evaluate the selective effect of glycerol, the phase equilibria of the methanol–tetrahydrofuran–water and methanol–tetrahydrofuran–water–glycerol systems at 101.32 kPa were studied.Methods. The calculations were carried out in the Aspen Plus V.9.0 software package. The vapor–liquid equilibria were simulated using the non-random two-liquid (NRTL) equation with the binary interaction parameters of the software package database. To account for the non-ideal behavior of the vapor phase, the Redlich–Kwong equation of state was used. The calculations of the extractive distillation schemes were carried out at 101.32 kPa.Results. The conceptual flowsheets of extractive distillation are proposed. The flowsheets consist of three (schemes I–III) or four (scheme IV) distillation columns operating at atmospheric pressure. In schemes I and II, the extractive distillation of the mixtures is carried out with tetrahydrofuran isolation occurring in the distillate stream. Further separation in the schemes differs in the order of glycerol isolation: in the third column for scheme I (traditional extractive distillation complex) or in the second column for scheme II (two-column extractive distillation complex + methanol/water separation column). Sсheme III caters to the complete dehydration of the basic ternary mixtures, followed by the extractive distillation of the azeotropic methanol–tetrahydrofuran system, also with glycerol. Sсheme IV includes a preconcentration column (for the partial removal of water) and a traditional extractive distillation complex.Conclusions. According to the criterion of least energy consumption for separation (the total load of the reboilers of distillation columns), sсheme I (a traditional complex of extractive distillation) is recommended. Additionally, the energy expended for the separation of the basic equimolar mixture using glycerol as the extractive agent was compared with that expended using another selective agent: 1,2-ethanediol. Glycerol is an effective extractive agent because it reduces energy consumption, in comparison with 1,2-ethanediol, by more than 5%.
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Nguyen, Huy Van, e Morihiro Maeda. "Removal of phosphorus from water by using volcanic ash soil (VAS): batch and column experiments". Water Science and Technology 74, n. 6 (24 giugno 2016): 1326–34. http://dx.doi.org/10.2166/wst.2016.297.
Testo completoAbstract (sommario):
Using low-cost and naturally available materials is considered an optimal adsorbent for removing phosphorus (P) from water due to its simplicity and economic efficiency. This study examined the removal of P from water using volcanic ash soil (VAS) by batch and column experiments. The maximum adsorption capacity of P was 2.94 mg g−1, estimated from the batch experiment according to a Langmuir isotherm. The column study showed a higher adsorption capacity of 5.57 mg g−1. The breakthrough curve showed that influent water containing 2 mg L−1 P was completely purified by VAS within 1,230 pore volumes (PV). The breakthrough and saturation points of the curves were 3,100 PV and 14,875 PV, respectively. After an adsorption column was loaded with 20,508 PV, a regeneration procedure was developed to determine whether an ion exchange of P with chloride occurred or adsorbed P in the columns could be eluted. Approximately 20% of P was recovered from columns by desorption tests, regardless of NaCl solution or deionized water. Specific surface area and mineral concentrations are both important characteristics that improve the adsorption capacity of VAS. The present study suggests that VAS is a promising adsorbent to remove P in water.
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Amutha, S., D. Arul Prakash, M. Lakshmipathy e G. Senthil Kumaran. "Study on Behaviour of Coconut Shell Aggregate Concrete with Bamboo Reinforcement in Compression Member". International Journal of Engineering Research in Africa 17 (luglio 2015): 14–23. http://dx.doi.org/10.4028/www.scientific.net/jera.17.14.
Testo completoAbstract (sommario):
The use of waste materials is one of the options for sustainable construction. In this paper the coconut shell waste is considered as coarse aggregate (after the same has been crushed) for preparing light weight concrete. The natural material like bamboo which is having considerable tensile strength is considered for reinforcement along with coconut shell concrete. Since the bamboo may absorb moisture from the concrete, to find its effect, the bamboo is treated with water repellent substance like epoxy adhesive is considered. Four types of short columns are tested. Type A Conventional concrete with steel reinforcement, Type B Coconut Shell concrete with steel reinforcement, Type C Coconut Shell concrete with treated bamboo reinforcement, Type D Coconut Shell concrete with untreated bamboo reinforcement. The conclusions drawn from the study are the load carrying capacity of Type B column is 89% of Type A column. For Type D column the ultimate load is 90% of Type C column. For Type C column the ultimate load is 70% of Type A column. For Type D column the ultimate load is 63 % of Type A column. For Type A column the stiffness is higher than the stiffness of Type B, Type C and Type D column. The energy absorption capacity of Type A, Type B columns are higher than that Type C and Type D columns. The epoxy treatment of bamboo has improved the ultimate load capacity by 1.1 times of the Type D column.
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Nitisapto, Mulyono, Azwar Maas, Benito Heru Purwanto e Putu Sudira. "Water Use Efficiency in Vertical Cropping System with Volcanic Ash Media by Using Biochar and Urban Waste Compost Fertilizer as Soil Amendement". Ilmu Pertanian (Agricultural Science) 4, n. 1 (29 maggio 2019): 40. http://dx.doi.org/10.22146/ipas.34304.
Testo completoAbstract (sommario):
Applying volcanic ash as planting media has to cope with several constrains: it quickly became sediment and hardened when exposed to water. One of the efforts to improve its physical condition is by utilizing biochar, which is one of amendment materials that can improve the soil quality. This study used vertical column container made from PVC to enable vertical plant arrangement. Volcanic ash requires additional nutrient intake from organic fertilizer such as urban waste compost. The objective of this study was to identify the proper dose combination of volcanic ash, biochar, urban waste compost fertilizer and column population per m2 to sustain the growth of curly lettuce in vertical cropping system, as well as the water use efficiency. This study was designed by using the Completely Randomized Design (CRD) Factorial with three factors. The first, second and third factors consisted of Biochar M1, M2 and M3 (25; 33; and 50 %), compost fertilizer doses of K1, K2, and K3 (25; 33; and 50 %), and column density of P1, P2 and P3 (4 columns/m2, 3 columns/m2 and 2 columns/m2), respectively. The total combination was 3 x 3 x 3 and each was repeated 3 times. Resulted data of this study consisted of growth and crops and analyzed by using the Analysis of Variance and continued with the HSD Tukey 5% Test (Honest significant deference). The water use efficiency (g/kg) can be formulated as the production of dry material per total water during the cultivation season (g/kg). Results of this study showed the highest fresh consumption result was obtained from treatment M3K3 in 556 g/column (comparison of volcanic ash, charcoal husk and compost = 25 : 25 : 50 %) and the best water-use efficiency was 2.30 g/kg.
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K, C. M., e L. Yang. "Enhanced bioremediation of trichloroethene contaminated by a biobarrier system". Water Science and Technology 42, n. 3-4 (1 agosto 2000): 429–34. http://dx.doi.org/10.2166/wst.2000.0414.
Testo completoAbstract (sommario):
The industrial solvent trichloroethylene (TCE) is among the most ubiquitous chlorinated compounds found in groundwater contamination. The objective of this study was to develop a barrier system, which includes a peat (used as the primary substrates) layer to enhance the aerobic cometabolism of TCE in situ. A laboratory-scale column experiment was conducted to evaluate the feasibility of using this peat biobarrier to remediate aquifers contaminated by TCE. This system was performed using a series of continuous-flow glass columns including a soil column, a peat column, followed by two consecutive soil columns. Activated sludges were inoculated in all three soil columns to provide microbial consortia for TCE cometabolism. Simulated TCE contaminated groundwater with a flow rate of 0.25 L/day was pumped into the system. Effluent samples from each column were analyzed for TCE and its degradation byproducts [cis-dichloroethylene (cis-DCE) and vinyl chloride (VC)]. Average removal efficiency was 96% for TCE over a 60-day operating period. Accumulation of VC was observed due to the depletion of oxygen in the system. Results from this laboratory study reveal that the developed biobarrier treatment scheme would be expected to provide a more cost-effective alternative to remediate chlorinated-solvent contaminated aquifers.
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Conaway, James E., J. B. Audino, E. Bane, S. K. Carrigan, R. Glinsky, S. W. King, M. W. Law et al. "Determination of Methomyl in Insecticidal Formulations by Reversed-Phase Liquid Chromatography: Collaborative Study". Journal of AOAC INTERNATIONAL 79, n. 4 (1 luglio 1996): 941–48. http://dx.doi.org/10.1093/jaoac/79.4.941.
Testo completoAbstract (sommario):
Abstract A reversed-phase liquid chromatographic (LC) method for methomyl was studied. Twelve collaborators analyzed 3 solid and 4 liquid formulations on both a Zorbax octadecylsilane (ODS) column and a similar column of their choice. Methomyl and the internal standard were separated by using a mobile phase consisting of approximately 8% acetonitrile in water, which was monitored at 254 nm. The coefficient of variation on the Zorbax column ranged from 0.70 to 5.23%, while the range on the collaborators' house columns was 1.08 to 6.01%. Results with the Zorbax ODS column fell within the 5% 2-tail limits, and 10 of 11 collaborators' results fell within these limits on house columns. The LC method for determination of methomyl in insecticidal formulations has been adopted first action by AOAC INTERNATIONAL.