Bed Thickness Research Articles

Online sequential, outlier robust, and parallel layer perceptron extreme learning machine models for sediment transport in sewer pipes.

Sediment transport is a noteworthy task in the design and operation of sewer pipes. Decreasing sewer pipe hydraulic capacity and transport of pollution are the main consequences of continuous sedimentation. Among different design approaches, the non-deposition with deposited bed (NDB) method can be used for the design of large sewer pipes; however, existing models are established on limited data ranges and mostly applied conventional regression methods. The current study improves the NDB sediment transport modeling by utilizing wide data ranges, and furthermore, applying robust machine learning techniques. In the present study, the conventional extreme learning machine (ELM) technique and its advanced versions, namely the online sequential-extreme learning machine (OS-ELM), outlier robust-extreme learning machine (OR-ELM), and parallel layer perceptron-extreme learning machine (PLP-ELM) are used for the modeling. In the studies conducted in the literature, sediment deposited bed thickness (ts) or deposited bed width (Wb) was used in the model structure as a deposited sediment variable, and therefore, different parameters in terms of ts and Wb can be incorporated into the model structure. However, an uncertainty arises in the selection of the appropriate parameter among Wb/Y, ts/Y, Wb/D, and ts/D (Y is flow depth and D circular pipe diameter). In order to define the most appropriate parameter to best describe the impact of deposited sediment at the channel bottom in the modeling procedure, four various scenarios using four different parameters that incorporate deposited sediment variables at their structures as Wb/Y, ts/Y, W/D, and ts/D are considered for model development. It is found that models that incorporate sediment bed thickness (ts) provide better results than those whichuse deposited bed width (Wb) in their structures. Among four different scenarios, models that utilized ts/D dimensionless parameter, give superior results in contrast to their alternatives. Based on the outcomes, the OR-ELM approach outperformed ELM, OS-ELM, and PLP-ELM techniques. The results obtained from applied methods are compared to their corresponding models in the literature, indicating the superiority of the OR-ELM model. It is figured out that the thickness of the deposited bed is an effective variable in modeling NDB sediment transport in sewer pipes.

Estimating the skin dose near to the applicator and acute toxicity in breast cancer patients: An intraoperative electron radiotherapy technique.

Intraoperative electron radiation therapy (IOERT) is one of the most recently popular therapeutic methods for breast cancer. This study aimed to measure the skin dose near the applicator during IOERT of breast cancer patients, as well as, the incidence of acute toxicity after surgery. Thirty-six female patients participated in the current study with the prescribed dose of 21 and 12 Gy for IOERT as full and boost, respectively. The skin dose was investigated based on different applicator sizes, tumor bed thicknesses, and monitor units (MUs). The energy was chosen 8 MeV, and EBT3 film was used for the dosimetric process. In addition, the acute toxicity included healing time for the surgical wound, scaling of the skin, itching, necrosis, redness as well as seroma formation for 1 week and 1 month were recorded. The results were compared to those of 22 patients who underwent the surgery without IOERT. The highest skin dose for the patients was obtained 2.09 Gy, which is lower than the threshold dose (6 Gy). Furthermore, the findings showed that the average skin dose was higher in bigger applicator sizes and MU and lower tumor bed thicknesses. The average of wound healing for the patient underwent IOERT and without the use of IOERT (as the control group) was 19.32 and 11.67 days, respectively. One month after surgery, the volume of aspirated seroma was higher in the patients who performed IOERT compared to the control group (250 ml vs. 200 ml). It is notable that there were not observed any redness, itching, scaling, and necrosis in both investigated groups. Owing to the results, the skin dose during IOERT was lower than the recommended level. The dose of IOERT as a full was higher than boost which can be related to the lower number of the patients in full method; however, there was a well-tolerated without severe acute complication, especially seroma formation and wound healing time in both full and boost methods.

Effect of drying method and bad thickness on physical, chemical, and organoleptic quality of dry herbal Moringa (Moringa oleifera) leaves

The purpose of this study was to determine the effect of the drying method and bed thickness on the physical quality test (moisture content, color), chemical (ash content, flavonoids, total phenol, carotenoids, ascorbic acid, or vitamin C and antioxidant activity) and organoleptic test of Moringa leaf tea. The experimental research was a Split Plot Design with dryers as the main plot and bed thickness as a subplot. Analysis of variance (ANOVA) and Duncan's Multiple Range Test (DMRT) at a significant level of 5% was used to analyze the experimental data. The organoleptic scores were analyzed using the Friedman test. The ANOVA results indicated that the drying method significantly affected whereas the bed thickness did not influence the experimental parameters. The best result in terms of herbal moisture content (5.94%) and color was obtained by YSD UNIB 2022 assisted with a fan. The highest ash content was in the range of 7.78 % -7%, total phenol was 50.78 GAE/g, carotenoids content was 17, 57 mg/g, ascorbic acid (vitamin C) was 117, 33%, and the strongest (antioxidant activity) was at an IC50 value of 37.85 ppm. The best (flavonoids) showed a red color on drying YSD UNIB12.

О некоторых закономерностях развития трещиноватости в терригенных породах острова Сахалин

Within complex studies of properties of hydrocarbons source rocks in Sakhalin Island the first preliminary results on the correlations of relations between the fractures distribution and bed thickness were obtained. Numerous measurements of stratification bedding planes, thicknesses of beds and orientations of orthogonal fracturing systems for the Kholmsk formation were performed. The received relations are described by linear approximation and correspond to the global data obtained for similar types of rocks and bed thicknesses.

Response of Shallow Gas‐Charged Holocene Deposits in the Yangtze Delta to Meter‐Scale Erosion Induced by Diminished Sediment Supply: Increasing Greenhouse Gas Emissions

AbstractRiver deltas have long been considered important carbon sinks. However, the presence of shallow gas and the processes of delta erosion caused by diminished sediment supplies could reduce the strength of the carbon sink. In this study, based on historical bathymetric data and a data set obtained from a seismic survey, we investigate the response of gas‐charged deposits in the Yangtze subaqueous delta to seabed erosion. A conservative estimate of the total methane reserves of 0.55–4.35 × 1011 mol was obtained in the delineated gassy area of ∼3,800 km2. The seismic and bathymetric data reveal a prominent erosional belt at water depths ranging from 5 to 20 m and extending from the southwestern to northeastern nearshore areas of the Yangtze subaqueous delta. Erosion is severe in the south and slight in the north due to differences in the hydrodynamic conditions, sediment erodibility, and sensitivity to sediment reduction. Seabed erosion reduces the thickness of the cap bed and the overburden pressure at the gas front, making it easier for gas to seep through the sediment column and bypass the anaerobic oxidation of methane. The good agreement between the elevated methane concentrations and the erosional belts and the spatial coincidence between the shallower gas front and pockmarks indicate that seabed erosion accelerates gas seepage activities. In the context of global deltaic degradation, the increasing greenhouse gas emissions from deltaic deposits are worthy of further attention.

Interpretation of paleoenvironment using benthic foraminifera from Tertiary rocks, northern Sarawak

In this work, we collected and examined three samples from an exposed 50 cm thick fossiliferous bed and prepared thin and polished sections for petrographic analysis. The benthic foraminifera assemblages and other marine fossils are studied to infer the paleo depositional environment. Based on the benthic foraminifera and their common ecological preferences, it is inferred that this layer has deposited between the intertidal and neritic zones, and within the photic zone, they are under oxygenated conditions. In addition, the presence of the glauconite mineral also supported the neritic environment interpretation, suggesting a water depth of less than 300 metres during the deposition, denoting shallow water conditions. Even though the results presented in this paper are at an elementary level, this could serve as additional information to develop a better understanding of the geology on a much larger scale.

The Accuracy of Flap Thickness and Diameter in LASIK Using a Femtosecond Laser.

To evaluate the resultant thickness of the WaveLight FS200 (Alcon Vision, LLC) created LASIK flap compared to intended thickness at the surgical visit, using the WaveLight EX500 (Alcon Vision, LLC) pachymeter and the resultant flap diameter compared to intended diameter. This single arm, prospective, single surgeon study assessed the accuracy of the intended flap thickness and diameter, after successful bilateral LASIK surgery. The WaveLight FS200 femtosecond laser was used to create all flaps with an intended thickness of 120 μm. Flap thickness was calculated by subtracting the stromal bed thickness after flap lift from the preoperative corneal thickness using the WaveLight EX500 on-board optical pachymeter. Flap diameter was determined using digital analysis. A total of 58 subjects (116 eyes) completed the study. The calculated mean flap thickness was 120.6 ± 9.0 μm (range 102 to 143 μm) using the EX500 pre- and post-flap pachymetry measurements. There was no statistically significant difference between the planned and achieved flap thickness (p > 0.05). The mean difference in flap diameter between planned and actual was 0.02 ± 0.05 mm. Corneal thickness measured by Pentacam at up to 2 months preoperatively versus EX500 just prior to surgery was similar, with EX500 measuring 2 μm less on average than the Pentacam. The results suggest that the WaveLight FS200 laser is reliable for LASIK flap thickness and diameter and accurately created flaps at the intended thickness and the intended diameter.

Synergetic carbothermic reduction and selective hydrochlorination of spent Li-ion batteries black mass towards enhanced metal recovery

The vast amount of Lithium-ion batteries (LIBs) reaching their end-of-life calls for effective recycling processes, given the low recycling efficiency in the industry. This paper proposes an innovative sequential carbothermic reduction-selective hydrochlorination process to attain metallization of Ni-Co alloy, selective chlorination of Li, Mn, and Cu, and the formation of Al2O3 to address some of the recycling challenges. The proposed process paves the way for short-range effective separation of the high-value metals in the LIB black mass based on magnetism and water solubility differences. After hydrochlorination at 1000 °C for 30 min with the material bed measuring 9 mm in thickness, Li and Mn water recovery reached 97.28% and 98.13%, respectively. The Ni and Co recoveries into the magnetic fraction reached 93.03% and 91.37%, respectively. Up to 95.28% Al, including graphite, reported to the non-magnetic fraction. Prolonged hydrochlorination time increased the chlorination degree despite negatively affecting the Ni-Co alloy recovering efficiency. Conversely, an increase in the thickness of the material bed had a reverse effect. Step-wise precipitation of the water-soluble product produced high-purity Li2CO3 (≥99.5%) and Mn3O4. Compellingly, graphite with morphology and characteristic diffraction peaks and Raman bands similar to commercial graphite was regenerated by NaOH dissolution of the non-magnetic fraction. These findings demonstrate that a black mass with a complex composition (Li, Ni, Mn, Co, and Al) could be comprehensively recycled using synergetic carbothermic reduction and hydrochlorination. Besides the high recovery rates, the proposed process minimizes recycling process steps and chemical usage, which is of utmost industrial significance.

Porosity Evolution and Microfacies Analysis of the Khurmala Formation (Paleocene-Early Eocene) from Selected Sections in Kurdistan Region, Northern Iraq Revealed by Cathodoluminescence Spectroscopy

The microfacies analysis and porosity evolution of the Khurmala Formation (Paleocene-Early Eocene) were studied in the Gomaspan and Sheraswar sections in the High Folded Zone, northeastern Erbil City, Kurdistan Region (N-Iraq). Lithologically, the Khurmala Formation in the Gomaspan section is about 23.5 m comprised of thick to massive bedded brecciated grey dolomitic limestone in lower and middle parts and interbedding of medium to thick beds of grey dolomitic limestone and yellow calcareous shale in the upper part. The Sheraswar section comprises 18.5 m yellow marl, thick yellowish-grey dolomitic marly limestone in the lower part, and bedded grey limestone interbedded with thin blue marl, shale, and mudstone in the upper part. The petrographic and cathodoluminescence (CL) studies of 20 thin sections of the Khurmala carbonates show that most skeletal grains are shallow marine derivative faunas and non-skeletal grains represent intraclasts, peloids, ooids, and extraclasts (monocrystalline quartz). Five main microfacies were identified in the studied rocks, and they integrated into two facies associations relating to their environmental interpretation: back reef/lagoon and patch reef. A new eight pore types were distinguished in the carbonate rocks of Khurmala Formation: interparticle, intraparticle, growth framework, intercrystalline, moldic, vuggy, fracture, and stylolite porosities. Most of the primary porosity was reduced by compaction and cementation due to effect of intensive diagenesis. Secondary porosity is predominant in both studied sections, the most common being the moldic porosity associated with different microfacies fabrics. CL investigations revealed that dolomitized lime wackestone microfacies has two types of different cementations in the late stages of blocky calcite cement which are discontinuous light to dull orange luminescence without zoning, and pure calcite cement of coarse to very coarse blocky calcite cement with characteristic bright orange luminescence and tight zoning.

The Ediacaran–Cambrian Chapel Island Formation of Newfoundland, Canada: evaluating the impact of outcrop quality on trace-fossil data sets at the Cambrian GSSP and less-explored sections

In 1992, the Chapel Island Formation at Fortune Head was selected as the Cambrian GSSP, which was placed at the first appearance of the ichnotaxon Treptichnus pedum. Although the transition from the Ediacaran to the Cambrian was well studied in Fortune Head and Grand Bank Head, it is also exposed at Lewin’s Cove and Point May. Here, we report new ichnologic and sedimentologic data sets from the four localities. Ichnologic data sets consist of bioturbation intensities, burrow width and depth, ichnotaxonomic composition, and stratigraphic appearances. Sedimentologic data sets include sediment grain size, bed thickness and architecture, sandstone/mudstone ratio, and physical sedimentary structures. In addition, the quality of each outcrop is evaluated (i.e., accessibility, lateral and vertical continuity, stratigraphic completeness, and type of exposure). At the four localities, the base of the Cambrian can be placed at the first appearance of Treptichnus pedum or of vertical trace fossils of the T. pedum Ichno-Assemblage Zone. In addition, Fortune Head, Grand Bank Head, and Lewin’s Cove display increases in ichnodiversity and bioturbation intensities that are concomitant with the first appearance of penetrative trace fossils. Point May stands out as a section with low ichnodiversity and an inconsistent data set on bioturbation intensities. Its limited data set is a consequence of poor bed surface exposures, which impact negatively on the preservation and visibility of horizontal trace fossils. This study demonstrates that evaluation of outcrop quality should be an essential procedure to any research addressing evolutionary trends that took place at this critical time of the history of life.

Reconstructing backwater hydrodynamics from fluvial-deltaic deposits using stratigraphic inversion: An example from the Tullig Sandstone, Western Irish Namurian Basin, County Clare, Ireland

Fluvial-deltaic systems are subject to non-uniform backwater flow where rivers approach receiving basins. This hydrodynamic condition results in sediment aggradation on the channel bed and enhanced downstream fining. In turn, this impacts river channel dynamics, including lateral migration rates and the propensity for avulsion. The imprint of non-uniform flow on stratigraphy has been reported from field, numerical modeling, and experimental studies. This work provides key observations for evaluating the impact of non-uniform flow spanning length scales from those of sediment grains to delta lobes. However, reconstructing paleohydraulic conditions of non-uniform flow from fluvial-deltaic settings remains a challenge. Non-uniform flow is a defining characteristic of fluvial-deltaic environments, but most existing relations linking hydrology and the depositional record rely on the assumption of steady and uniform flow. Herein, we present a novel stratigraphic inversion technique, combining it with morphodynamic modeling and statistical analyses, to evaluate how backwater conditions manifest in the stratigraphy of the Tullig Sandstone, an ancient fluvial-deltaic deposit of the Western Irish Namurian Basin. Our analyses refine estimates of channel properties, including flow depth and bed slope, and are validated by field measurements of sandstone-facies properties, including grain size and stratal architecture. For example, bed sediment fines down-dip, commensurate with increasing cross set and bed thicknesses. These patterns indicate bed aggradation and are consistent with reconstructed morphodynamic conditions. This study pinpoints the extent of non-uniform flow and its influence on fluvial-deltaic stratigraphy and provides a framework for improving reconstruction techniques used to interpret the paleohydrology of ancient fluvial-deltaic systems.

Parameters Selection for the Production of Fully Dense Metals Processed by Selective Laser Melting

Selective laser melting (SLM) presents significant assets for both industrial and academic fields. However, the process parameters selection is yet challenging. It presents tens of parameters to be carefully selected, including laser power and speed, bed thickness, hatching space, and other parameters, for the manufacturing of parts with high density. This paper provides a deeper understanding of the processing parameters’ effect on the evolution of the product’s density. A series of numerical simulations of porosity is achieved on Ansys Additive© software and it shows the evolution of the relative density at different laser powers and scan speeds. Numerical results show that low laser power and accelerated scan lead to the generation of a small melt pool, and consequently low density. In the opposite case, at high power and slow scan, the created melt pool is wide enough to avoid porosity and generate fully dense products. The product density is proportionally related to the melt pool size. Hence, it could be estimated through the correlation with the melt pool width, which enables the perfect selection of the hatching space for the selected set of parameters.

Characteristics and Controlling Factors of Natural Fractures in Continental Tight-Oil Shale Reservoir

Natural fracture growth plays an important role in shale-oil enrichment. Systematically investigating fracture features and their controlling factors in shale-oil reservoirs is essential for accurately predicting fracture distribution. The controlling factors of fracture distribution in the continental shale of the Qingshankou Formation in the Songliao Basin, China, were systematically analyzed based on the quantitative fracture characterization of outcrops and cores. Strata-confined fractures, throughgoing fractures, bedding-parallel fractures, and stylolites can be observed in the Qingshankou shale reservoir in the study area. Fracture distribution is not only controlled by internal factors, e.g., mineral composition, mechanical stratigraphy, and lithofacies, but also by external factors, e.g., faults and abnormally high pressure readings. Mineral composition is the primary factor governing fracture development, and it not only controls fracture abundance, but it also affects fracture filling and effectiveness. Mechanical stratigraphy determines the spatial morphology and developmental pattern of a fracture. Fractures are well-developed in brittle strata, with fracture spacing being proportional to bed thickness. Lithofacies can determine fracture development by controlling the variation of mineral composition, rock structure, bed thickness, etc. Stress concentration is commonly high at fault tips, intersections, and overlaps, where fracture density is high and has good connectivity. The existence of abnormally high pressure reduces effective stress, promoting shear fracture development. Tensile overpressure fractures can also be generated under small levels of differential stress.

Constraining depositional evolution and reservoir compartmentalization in a mixed carbonate-siliciclastic lacustrine system: The Yacoraite formation, Salta Group, NW Argentina

The mixed carbonate-siliciclastic Yacoraite Formation, Salta Group in northern Argentina has been interest of recent studies searching for potential analogues for the South Atlantic pre-sal carbonates. Microbial lacustrine carbonates are important reservoir systems and their characteristics and stratigraphic packaging are a major factor impacting compartmentalization. This study provides sedimentological and facies analyses combined with petrographical, isotope geochemical and petrophysical analyses of lacustrine clastics and carbonates using an example from the Yacoraite Formation (Salta Group) in northern Argentina (Tres Cruces sub-basin).The Yacoraite Formation records the evolution of a lacustrine system responding to basin scale tectonic processes and climatic conditions and is interpreted as a microbially-related mixed carbonate clastic lacustrine system comprising 8 main Facies types, deposited in either a perennial or an ephemeral system. The most dominant architectural elements are: Sandstones with interbedded shales (F1), Shales with interbedded sandstones and siltstones (F2), Thick-bedded oolitic grainstone (F5), Thin-bedded oolitic grainstone-packstone (F6) and Stromatolite boundstone (F8). These facies types allow to differentiate two types of lacustrine environments: Perennial (Stage I) vs Ephemeral (Stage II) intercalated with episodes of continental plains deposition, arranged in three depositional sequences (Yacoraite I, II and III), each recording either transgressive or a regressive-transgressive trend.Carbonate and clastics are arranged in cycles during the Perennial l Stage suggesting that the depositional system responded in patterns attributable to reciprocal sedimentation, whereas, during the Ephemeral Stage 2, spatial coexistence of clastic and carbonate seem to be the case rather that cyclic vertical superposition.Thick-bedded oolitic grainstone and Stromatolites (F5 and F8 respectively) of the perennial lacustrine system show laterally continuous and thick beds with the best reservoir properties. Furthermore, the Sandstones with interbedded shales (F1) are characterized by intermediate values of porosity and permeability, which would not result in permeability barriers. On the other hand, Thin-bedded oolitic grainstone-packstone (F6) of the ephemeral lacustrine system are characterized by a high degree of heterogeneity due to their limited areal distribution and their complex spatial variability with Shales with interbedded sandstones and siltstones (F2).

Negative-Pressure Wound Therapy Induces Lymphangiogenesis in Murine Diabetic Wound Healing.

Decreased lymphangiogenesis contributes to impaired diabetic wound healing. Although negative-pressure wound therapy (NPWT) has been shown to be effective in the treatment of recalcitrant wounds, its impact on lymphangiogenesis remains to be elucidated. In this study, the authors investigate the mechanisms of lymphangiogenesis following NPWT treatment of diabetic murine wound healing. Full-thickness dorsal skin wounds (1 × 1 cm 2 ) were excised on 30 db/db mice. The mice were either treated with occlusive covering (control group, n = 15), or received a 7-day treatment of continuous NPWT at -125 mmHg (NPWT group, n = 15). The wounds were photographed on days 0, 7, 10, 14, 21, and 28. Wound tissue was harvested on days 10, 14, 21, and 28 for quantitative analysis. Functional analysis of lymphatic drainage was performed on days 14 and 28 with Evans blue dye tracing. Lymphatic density and diameter, as visualized through podoplanin probing, was significantly higher in the NPWT group compared to the control group ( P < 0.001). NPWT up-regulated the expression of lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1) at the protein level ( P = 0.04), and significant differences were noted in lymphatic density as assessed by LYVE-1 staining ( P = 0.001). Leukocyte infiltration was significantly higher in the NPWT group ( P = 0.01). A higher speed of wound closure ( P < 0.0001) and greater wound bed thickness ( P < 0.0001) were noted in the NPWT group compared to the control group. NPWT increased the lymphatic vessel density and diameter with LYVE-1 up-regulation. NPWT therefore plays a positive role in lymphangiogenesis in diabetic wound healing. The authors' study investigates the association of NPWT and lymphatics and underlines the importance of a more in-depth investigation of the role of lymphatic vessels in wound healing.

Species composition of shoreline wolf spider communities vary with salinity, but their diets vary with wrack inflow.

Wolf spiders are typically the most common group of arthropod predators on both lake and marine shorelines because of the high prey availability in these habitats. However, shores are also harsh environments due to flooding and, in proximity to marine waters, to toxic salinity levels. Here, we describe the spider community, prey availabilities, and spider diets between shoreline sites with different salinities, albeit with comparatively small differences (5‰ vs. 7‰). Despite the small environmental differences, spider communities between lower and higher saline sites showed an almost complete species turnover. At the same time, differences in prey availability or spider gut contents did not match changes in spider species composition but rather changed with habitat characteristics within a region, where spiders collected at sites with thick wrack beds had a different diet than sites with little wrack. These data suggest that shifts in spider communities are due to habitat characteristics other than prey availabilities, and the most likely candidate restricting species in high salinity would be saline sensitivity. At the same time, species absence from low-saline habitats remains unresolved.

Developing bearing capacity model for geogrid-reinforced stone columns improved soft clay utilizing MARS-EBS hybrid method

Because of the complicated geometry and a lack of knowledge about the parameters that impact it, estimating the ultimate bearing capacity (qrs) of a geogrid-reinforced sandy bed on vertical stone columns in soft clay is challenging. In practical applications, developing an accurate prediction model can be beneficial due to the difficulty and expense of estimating qrs. The objective of this study is to develop a model for predicting the bearing capacity of geogrid-reinforced stone columns using Multivariate Adaptive Regression Splines (MARS) and Escaping Bird Search optimization algorithm (EBS). In order to accomplish this, 219 constructed experimental samples were used. Feature selection based on the Neighborhood Component Analysis (NCA) method showed that due to the strong correlation between undrained shear strength of unreinforced clay (qu) and the ratio of stone columns distance to foundation diameter (s/D) variables, only qu should be included in the modeling. A developed model for estimating the bearing capacity was found to have coefficients of determination (R2) of 0.997 for training, 0.993 for testing, and 0.995 for total data. This study confirms that the undrained shear strength of unreinforced clay (qu) is the most essential input parameter for assessing bearing capacity, while the the ratio of sandy bed thickness to foundation diameter (t/D) is the least essential input parameter. In addition, the parametric analysis shows that increasing all input parameters increases bearing capacity.

Reflection characteristics of thin-beds with aligned fractures

Fractures are ubiquitous in rock and therefore considerably affect the overall mechanical properties of rock. In this study, effective medium theory is used to analyze the reflection characteristics of elastic waves in thin-beds containing aligned fractures. First, elastic parameters are obtained for a single thin bed containing discrete vertical fractures. Then, an exact solution is derived for the reflection coefficient of elastic waves in horizontally transverse isotropic (HTI) thin-beds using the propagation matrix method. Next, the effects of the fracture density and fillings on the reflection pattern are analyzed. Thin-beds without fractures are equivalent to a vertically transverse isotropic (VTI) medium in the long-wavelength limit. The introduction of vertical fractures makes thin-beds equivalent to a single thin bed in an orthorhombic anisotropic (ORT) medium (where the thickness of ORT thin bed is the total thickness of the original thin-beds). The ORT model of fractured thin-beds is presented by the equivalent medium theory. The results obtained using the HTI thin-beds and ORT models are compared, and the influences of the ORT model accuracy and formation parameters (such as thickness-to-wavelength ratio of a single thin bed, total thickness of thin-beds, etc.) on the ORT approximation results are analyzed. The response characteristics of elastic waves in complex thin-beds with fractures determined in this study can give an important guidance to real applications in geophysics and rock mechanics.

Numerical assessment of riverbank filtration using gravel back filter to improve water quality in arid regions

The main challenge of water resource management in high-stress regions, especially in developing countries, is in adopting non-traditional methods to obtain safe drinking water in desired quantities. In Egypt, the riverbank filtration (RBF) system is one of the most common solutions to solve rivers’ water quality issues. Several sites have been investigated, and the system has demonstrated tremendous potential. The drinking water plant in Embaba, Giza, Egypt, is considered in this study to improve the quality of the abstracted water through the vertical well system. The numerical code of MODFLOW and MT3D is used to simulate the impact of using the emplacement of the gravel-pack filter (GPF). Three different scenarios were investigated: the first consists of vertical GPF; the second is horizontal GPF for different geometries, depths, widths or thicknesses, lengths, and permeability of the filter material; and, the third is drilling a pipe filter through the riverbed for different pipe numbers, depths, and the material’s hydraulic conductivity. The results revealed that the riverbank filtration sharing (RBFS) rate was increased by increasing the filter width or thickness at the riverside, the filter pipe numbers, the length of the horizontal filter, and the permeability of filter material. At the same time, the thickness of the river bed decreased by increasing the filter width at the groundwater side. Also, the RBFS was increased by increasing the filter width or the thickness in the two directions and the pipe length. However, it returned to decrease again due to groundwater sharing. Thus, the RBF design should carefully consider the gravel-pack, pipe filter geometry, and permeability impact rate of RBFS.

Terrestrial records of deglaciation events during terminations V and IV in the central Apennines (Italy) and insights on deglacial mechanisms

40Ar/39Ar geochronology constraints to aggradational phases and grain size variations show that the two large gravel beds occurring in the sedimentary filling of the Liri fluvial-lacustrine basin (central Italy) recorded the occurrence of deglaciation events synchronous within uncertainties with global meltwater pulses at ca. 450 and 350 ka. In particular, we find a precise match between the ages of gravel deposition and the occurrence of moderate sea-level rise events which anticipate those more marked during the glacial termination V and IV in the Red Sea relative sea level curve, as already verified by data from the Tiber River catchment basin. Such correspondence suggests that gravel deposition is facilitated by melting of Apennine mountain range glaciers, which provide the water transport energy and a surplus of clastic input to the rivers draining the mountain regions and flowing into the Tyrrhenian Sea. Therefore, the thick gravel beds intercalated in the sedimentary filling of the catchment basins of the major rivers in central Italy may be regarded as an equivalent proxy of large deglaciation events, similar to the ice-rafted debris in northern Atlantic. Consistent with this hypothesis, we also show the close correspondence between the occurrence of particularly mild (warmer) minima of the mean summer insolation at 65° N and these early aggradational phases, as well as with other anomalous early sea-level rises occurring c. 750 ka and 540 ka at the onset of glacial termination VIII and VI, and 40 ka at the onset of the so-called Heinrich events.