Ks Values Research Articles

Predictive Analysis for Personalized Machine: Leveraging Patient Data for Enhanced Healthcare

This research explores predictive analysis for personalized machine: leveraging patient data for enhanced healthcare. By leveraging the power of information and analytics, the healthcare industry can be driven towards a more patient-centric, proactive model that enhances outcomes and improve the overall quality of care. The objectives of the study are to: determine the significance and challenges of predictive analytics in healthcare, ascertain the data analytics techniques used in healthcare to enhance patient care, find out how predictive analytics can be applied for enhanced healthcare, and determine the ethical considerations associated with healthcare predictive analytics. This study employs the case study approach and experimental design. The study analyzes case studies of real-time deployment of predictive analytics models in healthcare centers, examines how these models enhance the healthcare delivery in those centers. Experiments were also conducted to understand how predictive analytics works. The C4.5 learning algorithm was employed to predict the presence of chronic kidney disease (CKD) in patients and differentiate between those not affected by the condition. The C4.5 classifier shows reasonable strength, evident in the large number of rightly classified occurrences (396) and a low misclassification of only 4 occurrences. This is further demonstrated by a low error rate of 0.37, as shown in table 5. The prevalence of this algorithm is emphasized by the large value of KS (0.97), indicating the classifier’s ground-breaking accuracy and performance. The performance of C4.5, featured by its minimal execution time and accuracy, puts it as a decent classifier. This characteristic makes it specifically well-suited for application in the healthcare sector, particularly for tasks involving prediction and classification. The application of data analytics methods for predictive analysis holds significant benefits in the health sector, as it gives us the power to predict and address potential threats to human health, covering different age groups, from the young ones to the elderly. This proactive method enables early disease detection, helping in timely interventions and contributing to better decision-making.

Construction of Accounting Fraud and Its Audit Countermeasure Model Based on Computer Technology

A prediction model of financial fraud of listed companies based on machine learning method is proposed to predict financial fraud of listed companies. Using the data set of Chinese listed companies from 2000 to 2020 as observation samples, Benford’s Law, LOF local anomaly method and SMOTE oversample were adopted, grey samples were excluded, and characteristic variables were selected from five aspects: fraud motivation, solvency, profitability, cash flow and operating capacity. The financial fraud identification model Xscore is established based on the XGBoost method. The Xscore model can improve the accuracy of model prediction, and is superior to the Fscore model and Cscore model in accuracy, recall rate, AUC index, KS value, PSI stability, etc. It is more suitable for predicting the financial fraud of listed companies in China. The results of this study are helpful in promoting the research and application of artificial intelligence and machine learning in accounting, and provide references for promoting the disclosure of high-quality financial information by listed companies and maintaining the order of the capital market.

Incorporation of Pd Catalyst into Highly Effective Borophene Nanosheet Co-Catalyst for Electrokinetics and Electrochemical Oxygen Reduction Reactions

AbstractTo improve the performance of the system, it is of great importance to develop efficient catalysts for ethanol (EtOH) electro-oxidation. Pd/B electrocatalyst was synthesized using a sonochemical method. Structural and electrochemical properties of the prepared nanomaterial were investigated using electrochemical and physical techniques such as Raman spectroscopy, electrochemical impedance spectroscopy (EIS), x-ray diffraction (XRD), zetersizer, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM) and energy-dispersive x-ray spectroscopy (EDS) and cyclic voltammetry (CV). FTIR confirmed all the functional groups of carbon black, Pd/C, borophene, and Pd/B, and the crystallinity was investigated using XRD. EIS showed that Pd/B has a faster charge transfer and, through investigation using CV, Pd/B showed a more negative onset potential and higher current (−0.76 V vs. Ag|AgCl; 0.07 mA) than Pd/C (−0.65 V vs. Ag|AgCl; 0.05 mA), indicating a more catalytic behavior and tolerance of Pd/B. The active sites could be attributed to the addition of borophene. During the anodic sweeping direction of Pd/B electrocatalyst, it was observed that the ratio of backward peak current (Ibwd) to forward peak current (Ifwd), (Ibwd/Ifwd) of in a 2 M of NaOH + 2 M of EtOH is almost equal to (Ibwd/Ifwd) 1 which shows excellent tolerance of Pd/B to poisoning by ethanol intermediate species. The electron transfer rate (Ks) values for Pd/B at 0.1 M, 0.5 M, 1 M, 1.5 M, and 2 M were estimated to be 4.50 × 10−13 s−1, 1.08 × 10−12 s−1, 4.28 × 10−13 s−1, 5.25 × 10−14 s−1 and 9.35 × 10-14 s−1. At 2 M there is a faster electron transfer than at other concentrations which is also evidenced by the obtained diffusion values (D) of the system which were found to be 2.92 × 10−7 cm2 s−1, 4.72 × 10−8 cm2 s−1, 4.82 × 10−8 cm2 s−1, 1.22 × 10−7 cm2 s−1, and 9.12 × 10−8 cm2 s−1. The electrochemically active surface area (ECSA) is strongly related to intrinsic activity, Pd/B (1.85 cm2/mg × 10−5 cm2/mg) denotes the highest Pd-O stripping charge than Pd/C (1.13 cm2/mg × 10−5 cm2/mg).

Flow and contaminant transport dynamics in clay-amended barriers through flushing experiments and multi-porosity-based modeling

Clay-amended barriers are widely used to prevent hazardous leachate percolation from landfill to subsurface. The performance of these barriers is mostly evaluated through numerical simulations with limited experimental investigation through leachate flushing experiments. To bridge this gap, contaminant loading and its flushing experiments were carried out to assess the performance of clay-amended composite materials as landfill liners. River sand (Sa), loamy soil (Ns), and alternative waste materials like fly ash (Fa) and flushed silt (Si) were used to prepare the composites. Composites fulfilling the hydraulic conductivity (<10−7 cm/s) and compressive strength (200 kPa) criteria were selected for contaminant loading and its flushing experiments to understand the fate of fluoride ions. The experimentally determined hydraulic conductivity (Ks) values for all the composites were in the order of 10−8 cm/s. The experimental breakthrough curves exhibited skewed shape, long tailing, and dual peaks. Dual porosity and dual permeability with immobile water models were employed to simulate these curves, revealing that preferential flow pathways and random chemical sorption sites significantly affect solute transport in clay-amended barriers. Further, scanning electron microscopy and energy-dispersive X-ray spectroscopy were employed to trace the preferred path of fluoride ions through the barrier. The removal efficiency and temporal moments were used to determine the percentage mass retained, mean arrival time, and spreading within the barrier. The highest solute mass was retained by sand-clay barrier (SaB30) (91%), followed by loam-clay barrier (NsB30) (59%), fly ash-clay barrier (FaB30) (38%), and silt-clay barrier (SiB30) (4%) with the least mass. The lowest mean arrival time was calculated for NsB30 (269 h) and the highest for SaB30 (990 h), with FaB30 (384 h) and SiB30 (512 h) having values in between. This study concludes that validating the design hypothesis of clay-amended barriers through contaminant loading and its flushing studies leads to an effective and sustainable design.

Effect of Humic Amendment on Selected Hydrophysical Properties of Sandy and Clayey Soils

In recent years, products containing humic acids have been increasingly used in agriculture to improve soil parameters. Quantifying their impact on soil quality is, therefore, of key importance. This study seeks to evaluate the impact of the commercial humic acid product (HA) on the hydrophysical parameters of sandy and clayey soils sampled from different sites in Slovakia. Specifically, the study hypothesizes that humic amendment will enhance particle density (ρs), dry bulk density (ρd), porosity (Φ), saturated hydraulic conductivity (Ks), soil water repellency (SWR), and water retention capacity in sandy and clayey soils. The results of the laboratory measurements were analyzed using NCSS statistical software at a statistical significance of p &lt; 0.05. In sandy soil, there was a statistically significant decrease in ρd and Ks and an increase in Φ and a contact angle (CA) after the application of 1 g/100 cm3 HA. At a dose of 6 g/100 cm3 HA, the values of ρs, ρd, and Ks decreased, and the Φ and CA values increased. In clayey soil, the Ks value significantly decreased by −35.5% only after the application of 6 g/100 cm3 HA. The addition of HA increased the full water capacity (FWC) and available water capacity (AWC) of clayey and sandy soils. The positive influence of HA on the studied soil parameters was experimentally confirmed, which can be beneficial, especially for their use in agricultural production.

Evaluation of Sabkha Soil Bearing Capacity by Plate Load Test in Al Muthanna Province

For projects such as airports and road paving, an appropriate foundation must be developed in Sabkha soil, which requires a trustworthy assessment of soil-bearing capacity. When heavy traffic is expected to result in substantial wheel loads throughout pavement construction and maintenance, the plate load test helps solve these issues with subgrade and sub-base layer design. This work aims to investigate and assess the geotechnical behavior regarding soil strata from one area in southern Iraq: Sabkha. Conversely, a comparison is made between subgrade response modulus and soil-bearing capacity determined by field plate load tests and traditional laboratory investigations. The data demonstrated that the values related to Ks in the consolidation test rose as a ratio of pre-consolidation pressure of 45% and dramatically dropped with an increase in applied stress that is vertically applied below pre-consolidation stress. Furthermore, PLT data demonstrated that when pressure was applied, the modulus of the subgrade reaction did not follow a regular pattern. At the beginning of the loaded stage, after the pre-consolidation stress, Ks values at testing points 2 and 3 were high. After that, Ks abruptly decreased, particularly when the applied pressure surpassed the pre-consolidation stress before being constant again. A detailed discussion is given on the effects of stress distribution and test conditions on the elasticity stress curve's shape and the subgrade reaction modulus.

A practical equation for predicting saturated hydraulic conductivity of fine-grained soils

The saturated hydraulic conductivity (ks) of soils plays a crucial role in various agricultural and environmental engineering applications, particularly in relation to pollution prevention and water migration. Firstly, the traditional Kozeny-Carman (KC) equation, which are commonly used to estimate ks, has limitations in predicting ks for different types of fine-grained soils based on the analyses of permeability test data in the literature. Secondly, to tackle this issue, a modified KC equation was proposed by introducing an expression for the shape parameter and establishing a relationship between the tortuosity equation and the plastic limit. Additionally, the validation of the proposed equation was conducted using ks values of 25 fine-grained soils obtained from other sources. Finally, a comparison was made with the four commonly used ks models to evaluate its performance. The results indicate that the proposed equation demonstrates a relatively high coefficient of determination and a low root mean square error. This suggests that the proposed equation has the potential to accurately assess ks for fine-grained soils. The predictions for ks using the modified equation showed good agreement with the experimental data mentioned in the literature.

Effect of operating speed on turbocharger compressor blade wear

ABSTRACT In harsh environments, turbochargers require continuous adjustment of the rotating speed, which can lead to differences in erosive wear on the blades compared to erosive wear under constant speed conditions. In this study, the erosion model expression for an aluminum alloy plate with a fitted Ks value of 20 μm under the erosion of 160 μm SiO2 particles is obtained through erosive wear experiments. Taking a turbocharger compressors as the research object, the influence of four commonly used working speeds on blade wear is analyzed. The results show that when the speed increases from 70,000 rpm to 130,000 rpm, the maximum wear rate concentration values for the main and splitter blades increase by approximately 590% and 310%.

Comparison of Saturated Hydraulic Conductivity under the Reclaimed Conditions of Salt Affected Soil

Solving the soil problems that affect negatively on growth of plants and reduce the soil permeability is necessary for the study site, Thein Gone Village in Yamethin Township, Myanmar. The objectives of this study were; to identify the soil whether it is salt-affected or not and to investigate the proper reclamation method with different rates of amendments by comparing the saturated conductivity (Ks). Both composite (disturbed) and core (undisturbed) soil samplings were collected at three profiles (0 - 60 cm soil depth) during March, 2023. Some soil properties such as texture, bulk density (g cm-3), moisture content (%), ECe (electrical conductivity, saturated extract; mS cm-1), pH (1:5 water), SAR (sodium absorption ratio) and pH and EC of leaching water were also measured. Firstly, the study site was problematic with high pH due to Na+ distribution of underground water although there was some application of gypsum for a decade. Also, low permeability (Ks &lt; 1x10-8 cm s-1) was another problem there. To leach the salt (EC &lt; 1 mS cm-1 in leachate), 1500 cm3 of water was necessary for one core (98.21 cm3 soil volume). It was relatively high amount for using the quality-water. For reclamation methods, gypsum 5 t ha-1, sulphur 1 t ha-1, and cow-dung manure 20 t ha-1 gave the minimum (- log Ks) value among different rates of each amendment. The less the - log Ks, the more permeable the soil becomes. Among different amendments, gypsum 5 t ha-1 showed the fastest saturated hydraulic conductivity. Moreover, it is necessary to drain out the leachate to prevent the formation of saline -sodic soil.

Fabrication of β-cyclodextrin and 2-hydroxypropyl-β-cyclodextrin inclusion complexes of Palbociclib: Physicochemical characterization, solubility enhancement, in -silico studies, in vitro assessment in MDA-MB-231 cell line

Palbociclib (PAL) is an anti-cancer molecule that is highly selective for CDK4/6 inhibition and approved for the management of advanced breast cancer. Due to its down-and-out aqueous solubility and poor oral bioavailability, therapeutic applications have been compromised in the pharmaceutical field. The work aims to explore the physicochemical properties, aqueous solubility, dissolution rate, and in silico analysis of PAL complexed with β-cyclodextrin (β-CD) and 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) and to ascertain the implications of complexation on the in vitro anti-cancer activity of PAL. The two inclusion complexes (ICs) of PAL were prepared by the methodology of freeze-drying and further characterized by FT-IR, DSC, TGA, FESEM, and PXRD. The 1H NMR and 2D NMR revealed that a significant chemical shift was observed for the ICs as well and a correlation was seen between the CH3 of HP-β-CD with protons (ring C & D) of the pyrimidine and pyridine rings respectively. AL type graph was obtained depicting the KS value to be 625.4 M−1 and 3760 M−1 respectively for PAL-β-CD and PAL-HP-β-CD. Also, the aqueous solubility of PAL was improved by 31.05 and 37.99-fold respectively by both the ICs. The stoichiometric ratio of 1:1 was established by Job’s plot. Additionally, the results of in-silico studies were in correlation with the theoretical calculations. Further, it was found that the in vitro cytotoxicity investigation on MDA-MB-231 cells reported IC50 value for PAL-β-CD IC and PAL-HP-β-CD IC a 2.33– and 3.38-fold a lower IC50 value than PAL (IC50 = 9.55 ppm) which indicates higher cellular toxicity for both ICs in comparison to free PAL. Additionally, PAL-β-CD IC (41.99 ± 2.63 %) and PAL-HP-β-CD IC (57.33 ± 1.58 %) showed higher apoptosis than PAL (25.17 ± 1.27 %) also the cellular internalization was seen higher for both the ICs as well as the ROS formation, and MMP depolarization was evidenced.

Identification and analysis of the SAURs in Prunus sibirica

In the present study, we identified the members of the small auxin-up RNA (SAUR) gene family in Prunus sibirica and analyzed their localization, phylogeny, duplication, cis-elements in the promoter, and expression patterns. In total, 57 PsSAURs were identified, which were randomly distributed along eight chromosomes. Among them, eight and ten pairs of segmentally duplicated genes and tandem duplication genes were found in 13 and 21 PsSAURs, respectively. Phylogenetic analysis indicated that the PsSAURs were divided into five groups (Group A–E). Light-responsive, methyl jasmonate, abscisic acid, salicylic acid, and gibberellin, as well as low-temperature responsiveness, and defense and stress responsiveness were identified by analyzing PsSAURs promoter sequences. The collinearity analysis of P. sibirica SAURs and Prunus mume and Prunus persica SAURs family genes detected 35 and 59 pairs of gene pairs, respectively, and the Ks values of all collinearity gene pairs were almost less than 1. Expression pattern analysis showed that PsSAURs had different tissue and stage expression patterns. However, research on SAURs in non-model plants remains limited, and studies on the expression and function of SAURs are lacking. This study pro­vides a foundation for further investigations into the functional analyses of SAURs in P. sibirica.

Features of extrusion of films from blends of LDPE and LLDPE of modern grades

The study of rheological and viscoelastic characteristics of modern grades of LLDPE and their mixtures with LDPE, intended for the production of fi lm products, as well as the evaluation of mechanical characteristics of films made of them have been carried out. As a result of studying the rheological properties of LLDPE and LDPE, it was found that polymer melts show behavior typical of pseudoplastic liquids. The flow index for all grades of LLDPE was 0.78–0.91, which indicates a narrow MWD of polymers; LDPE had a flow index of 0.56–0.57 and a higher activation energy for viscous flow than LLDPE.The viscoelastic properties of the polymers were assessed by the value of swelling coefficient (Ks) at two test temperatures. It is shown that the Ks of LDPE significantly exceeded that of all studied LLDPE grades at the same shear rates or shear stresses. The increase in temperature had an insignificant effect on the Ks value for both LDPE and LLDPE. It has been found that an increase in the content of LDPE in mixtures with LLDPE leads to an increase in Ks.The analysis of tensile properties of films obtained from the original polymers and their blends showed that the character of change in strength and elongation at break depends on the composition and type of LLDPE from different manufacturers. Films based on m-LLDPE of LUCENE brand had the maximum strength properties. The optimal content of LDPE in a mixture with LLDPE depends on the type of LLDPE and is no more than 10–20 wt.%.

Cross-Validation of the Remarkably High Surface Oxygen Exchange Kinetics of PrBa0.5Sr0.5Co1.5Fe0.5O5+δ: A Combined Thin-Film Mass Relaxation and Bulk Electrical Conductivity Relaxation Study.

In this work, we measure the oxygen kinetic properties of double perovskite PrBa0.5Sr0.5Co1.5Fe0.5O5+δ (PBSCF), a material widely used as the air electrode in solid oxide electrochemical cells, by mass relaxation (MR) and electrical conductivity relaxation (ECR) experiments. MR studies are carried out using thin films deposited on a gallium phosphate piezocrystal microbalance, and ECR studies are performed using a bulk bar sample with 97% theoretical density. Measurements are performed at 600 °C over the temperature oxygen partial pressure range from 10-4 to 0.21 atm. Despite the differences in experimental formats and surface microstructural features, the ks values extracted from the two methods are found to be in good agreement with one another. The rate constant is found to increase with oxygen partial pressure with a power law dependence, rising from 1.0 × 10-6 cm/s at 3.2 × 10-4 atm to 1.2 × 10-4 cm/s at 0.24 atm, as averaged over the oxidation and reduction directions. The rates in the oxidation direction are observed to be slightly higher than those in the reduction direction for a given pair of pO2 values, suggesting that the final pO2 value controls the overall relaxation behavior. The power law exponent describing the dependence of ks on pO2 is found to be 0.74 ± 0.01. The ECR study of the bulk sample reveals that even with a diffusion length of 1.8 mm, the relaxation process is largely free of diffusion limitations, indicating that PBSCF has the high bulk transport properties required for a double-phase boundary oxidation/reduction pathway.

Complementation of an Escherichia coli K-12 Mutant Strain Deficient in KDO Synthesis by Forming D-Arabinose 5-Phosphate from Glycolaldehyde with Fructose 6-Phosphate Aldolase (FSA)

KDO (2-keto-3-deoxy-D-manno-octulosonate) is a landmark molecule of the Gram-negative outer membrane. Mutants without KDO formation are known to be barely viable. Arabinose 5-phosphate (A5P) is a precursor of KDO biosynthesis and is normally derived from ribulose 5-phosphate by A5P isomerases, encoded by kdsD and gutQ genes in E. coli K-12. We created a kdsD gutQ-deficient double mutant of strain BW25113 and confirmed that these cells are A5P auxotrophs. Fructose 6-phosphate aldolase (FSA) is known to utilize (among other donors such as dihydroxyacetone or hydroxyacetone) glycolaldehyde (GoA) as a donor compound and to provide A5P in vitro when glyceraldehyde 3-phosphate is the acceptor. We show here that this FSA function in vivo fully reverses the growth defect and the A5P deficiency in kdsD gutQ double mutants. Expression of both plasmid-encoded fsaA, fsaAA129S, or fsaB genes as well as a chromosomally integrated form of fsaAA129S led to maximal OD600 values of &gt;2.2 when GoA was added exogenously (together with glucose as a C source) at a concentration of 100 µM (Ks values in the range of 4–10 µM). Thus, a novel bio-orthogonal bypass to overcome an A5P deficiency was opened. Lower GoA concentrations led to lower growth yields. Interestingly, mutant strains with recombinant fsa genes showed considerable growth yields even without exogenous GoA addition, pointing to yet unknown endogenous GoA sources in E. coli metabolism. This is a further example of the usefulness of FSA in rewiring central metabolic pathways in E. coli.

An Inversion Study of Reservoir Colluvial Landslide Permeability Coefficient by Combining Physical Model and Data-Driven Models

The saturated permeability coefficient (ks) is a key parameter for evaluating the seepage and stability of reservoir colluvial landslides. However, ks values obtained from traditional experimental methods are often characterized by large variations and low representativeness. As a result, there are significant deviations from actual observations when used in seepage field calculations for reservoir landslide analysis. This study proposes an intelligent inversion method that combines a physical model and a data-driven model for reservoir landslide ks based on actual groundwater level (GWL) monitoring data. This method combines Latin Hypercube Sampling (LHS), unsaturated flow finite element (FE) analysis, particle swarm optimization algorithm (PSO), and kernel extreme learning machine model (KELM). Taking the Hongyanzi landslide in Sichuan Province, China, as the research object, the GWL of the landslide under different ks was first obtained by LHS and transient seepage FE analysis. Then, a nonlinear functional relationship between ks and the landslide GWL was fitted based on the PSO-KELM model. Finally, the optimal landslide ks was obtained by minimizing the root-mean-squared error between the predicted and actual GWL using the PSO. A global sensitivity analysis was also conducted on the ks of different rock and soil layers to reveal their control rules on the calculation of landslide GWL. The research results demonstrate the feasibility of the proposed method and provide valuable information for similar landslides in practice.

Saturated hydraulic conductivity and water retention curve of variably weathered tuff breccia bedrock in a headwater catchment

Although recent studies have emphasized the importance of water flow through bedrock to hydrological processes in headwater catchments, information on the hydraulic properties of bedrock, required for physically characterizing water flow processes, is lacking. In this study, the saturated hydraulic conductivity, Ks, and water retention curve of tuff breccia bedrock core were determined in samples collected from boreholes in a headwater catchment in northern Japan. These core-scale properties, together with core shape and in situ Ks values, were used to define two groups of bedrock: CM- and CL-class (weakly to moderately weathered) and D-class (highly weathered). Little change in the volumetric water content θ of CM- and CL-class bedrock was observed in the dry range at a pressure head ψ < –200 cm, but slight changes occurred in the wet range (ψ > –200 cm), resulting in low core-scale Ks values of 10–8–10–7 cm s−1. Core shape and in situ Ks values much larger than the core-scale values suggested that in situ water flow is restricted to fractures, with little contribution of the matrix to total flow. In D-class bedrock, on the other hand, the change in θ with ψ was somewhat larger than in CM- and CL-class bedrock, especially in the wet range, resulting in moderate core-scale Ks values of 10–5 cm s−1. These results indicated that flow in D-class bedrock is better represented by matrix flow than by preferential flow through fractures. The hydraulic properties presented herein provide a basis for analyzing subsurface water flow, including through bedrock layers. Those analyses will provide a better understanding of water flow processes in headwater catchments.

Testing the hydrodynamic behavior of a loam soil by beerkan infiltration runs with six heights of water pouring

Interpreting and simulating rainfall partition into infiltration and surface runoff has to consider that surface soil hydraulic properties, including saturated soil hydraulic conductivity (Ks) and sorptivity (S), could change even at very short temporal scales. Soil deterioration due to water impact can be tested in the field by the multi-height beerkan (MHB) method, that is, by pouring water on the infiltration surface from different heights. Soil hydraulic properties can be estimated coupling the MHB method with the steady version of the Beerkan Estimation of Soil Transfer parameters procedure (BEST-steady). The MHB method with six heights of water pouring (H) in the range 0.03–2 m was applied on a relatively dry loam soil to investigate height of water pouring effects on i) the established infiltration process, and ii) Ks, S, the scale parameter of the water retention curve (hg) and the characteristic microscopic pore radius (λm). Higher heights of water pouring generally induced a slowdown of the infiltration process, smaller S, Ks and λm values and higher |hg| values. The S, Ks, |hg| and λm vs. H relationships were statistically significant but the fitted relationships for S and Ks were stronger than those for |hg| and λm, indicating a different sensitivity of the considered parameters to the height of water pouring. Small or negligible soil deterioration was observed for both small (H ≤ 0.25 m) and large (H ≥ 1.5 m) heights. Between these two extremes, the soil deteriorated as H increased, suggesting that the external solicitations were high enough to overcome the resistance of the porous medium but not so high to determine a complete soil alteration. The tested methodology appears promising to determine the effects of water impact on the soil hydrodynamic behavior and it could be applied to perform a soil hydraulic characterization usable for modelling hydrological processes.

Minimizing sampling induced errors in Ks-measurements of stone bearing soils

Macropores have a great effect upon the overall saturated hydraulic conductivity (Ks) of soil samples. However, when using steel-cylinders for soil sampling, especially in stone-rich sites, soil core samples often bear sampling induced macropores due to improper sampling operation. The minimization of this macropore related bias of stone bearing soils‘ matrix Ks values is of high concern. To quantify the sampling induced error of Ks values of stony soils, Ks values were measured on a series of soil cores (n = 46) collected at 5 Bavarian sites under arable and grassland management. Based on texture-related tabulated Ks values, so-called Ks factors were extrapolated, which are related to the macropore fraction of the soil (RoGeR model). The overall Ks values of the soil cores were reduced by these Ks factors. The resulting matrix-related Ks values of the stone bearing soils were contrasted against the General Effective Medium (GEM) approach. Here, the shape of stones was parameterized as well as the critical stone fraction (fc). When applying sample specific fc values, the correlation between the RoGeR- and the GEM approach resulted in a good agreement (R² = 0.9) with an acceptable root mean square error (RMSE) of 4.6 cm/d. Ks reduction using the RoGeR approach seems to be a viable way to fit measured Ks values of stone bearing soil cores with sampling induced macropores to matrix conditions. Alternatively, GEM provides a way to calculate matrix Ks values of stone bearing soils based on tabulated Ks values and soil particle information.

Soil reuse effects on determination of saturated hydraulic conductivity of different loamy soils

AbstractLaboratory measurement of saturated hydraulic conductivity, Ks, of sieved and packed soil is important for many scientific purposes. A given soil mass can be used once or several times. Little is known of the dependence of the Ks data on the reuse of the same soil mass. For three loamy soils, this investigation tested reuse effects of exactly the same soil mass on determination of Ks with the simplified falling head technique. For a given soil, the Ks values of 15 repacked soil samples were determined by using the same soil for a total of eight times. The means of Ks, initially equal to 45–159 mm/h, depending on the soil, decreased by nearly two or three times with the reuse of the same material, and they settled on values of 23–59 mm/h by the end of the experiment. Low, stable and little variable (coefficients of variation ≤15%) Ks values were obtained after the soil was used three to five times although there was some sign that stabilization of Ks could also require more reuses. The soil became finer with more reuses and the textural characteristics of the undispersed soil explained a large amount of the mean Ks results (coefficient of determination between means of Ks and the mean weight diameter = 0.65–0.76, depending on the soil). Taking into account that the best procedure for determination of Ks of sieved and packed soil samples yields the lowest variability of the individual Ks data, the conclusion was that a soil pre‐treatment including several wetting and drying cycles should be realized to obtain a soil mass usable repeatedly. The history of the used soil mass should be reported in the investigations dealing with sieved and repacked soil samples.

Numerical Study of Effects of Inhomogeneous Roughness on the Ship Friction Resistance

The cleanliness of a ship hull is crucial for energy saving. Biofouling, which can cause microbiological corrosion, can also increase ship resistance. If left unchecked, this can lead to inefficient energy use and increased emissions, contributing to global warming. Ship resistance is a critical factor in ship design, which affects ship powering. The analysis of friction resistance due to biofouling on a ship hull requires an examination of the distribution of roughness height (ks), which is randomly distributed. In this study, an analysis of friction resistance coefficient (CF) due to inhomogeneous roughness is carried out with the help of CFD simulations with a full-scale model at 19 kn and 24 kn. The roughness of three ship segments, namely aft-hull, midship, and fore-hull, varies with ks values of 125 μm (P), 269 μm (Q), and 425 μm (R), respectively, while maintaining the same wetted surface area (S) in each segment. According to the simulation results, the RQP model produces the highest CF of 2.154 x 10-3, while the PQR model produces the smallest CF of 2.119 x 10-3 each at speed 24 knots. The CF contributes an average of 72.2% CT.