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1
Al-Hunaidi, M. O. "Insights on the SASW nondestructive testing method." Canadian Journal of Civil Engineering 20, no. 6 (December 1, 1993): 940–50. http://dx.doi.org/10.1139/l93-126.
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Spectral analysis of surface waves (SASW) is a nondestructive and in-situ method used for determining the thickness and elastic properties of pavement and soil sites using the dispersion characteristics of surface waves. In this paper, computer simulations of actual surface wave field tests are used to clarify errors that may arise in experimental dispersion curves of pavement sites when the usual test and data analysis procedures of the SASW method are followed. Two aspects of these procedures are considered: (i) relative phase angle unwrapping and (ii) source-to-near-receiver distance. The results of these simulations reveal that the currently used procedures may lead to erroneous results for some sites; the simulations offer valuable insights on the underlying causes. An overview of the theoretical aspects and field procedures of the surface wave method is briefly presented. Key words: surface waves, nondestructive testing, pavements, soils, elastic modulus.
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Sawada, Y., LAG Aylmore, and JM Hainsworth. "Development of a soil water dispersion index (SOWADIN) for testing the effectiveness of soil-wetting agents." Soil Research 27, no. 1 (1989): 17. http://dx.doi.org/10.1071/sr9890017.
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Computer-assisted tomography (CAT) applied to gamma-ray attenuation measurements has been used to develop an index termed the soil water dispersion index (SOWADIN), which describes quantitatively the amount and distribution of water in soil columns. The index, which is determined by classifying pixels in a scanned slice into three categories according to their attenuation coefficients, contains two numerical values. The first value corresponds to the water content of the scanned slice and the second value is a measure of the dispersion of the water throughout the slice. Artificially wetted zones were created in soil columns to give one-third of the scanned layer wetted with various patterns of wetted-area distribution. The SOWADIN values obtained accurately reflected the differences in water distribution associated with the different patterns. Application of SOWADIN to columns of a water-repellent sand before and after treatment with a soil-wetting agent clearly illustrates both the increase in water content and improvement in water distribution in the soil column following treatment.
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Emerson, WW. "Structural decline of soils, assessment and prevention." Soil Research 29, no. 6 (1991): 905. http://dx.doi.org/10.1071/sr9910905.
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Two extreme textural types of cultivated surface soils are mainly considered here, non-shrinking red-brown earths and highly shrinking cracking clays. Total porosity is used to assess the structural status of the former. Values are compared with the highest and lowest values found in the field. For the latter, the criterion used is the porosity of dry aggregates or clods. Values here are taken from the literature. To find out why inter-particle bonding in soil aggregates is insufficient to stop structural decline, a scheme has been developed which includes a modified version of Emerson's (1967) classification of soil aggregates. Slaking is carefully assessed. The bulk density of a cube made from soil at 'field capacity' is measured as well as testing another for dispersion. Class 3 is now divided into 3a and 3b, according to the degree of dispersion of remoulded soil in water. Also apart from soils which disperse spontaneously from dry, classes 1 and 2, the dispersion of all soils is assessed after remoulding at 'field capacity'. It has been found that the red-brown earth site which had the best visual structure also had the largest total porosity and aggregates in class 4. At the worst site, aggregates were in class 3a and the porosity had been reduced to that of the soil cube. For cracking clays, porosity is appreciably higher where the aggregates are in class 4 rather than class 3a. Water content/dispersion curves are presented for the clays showing the extent of the increase in OD apparently associated with the presence of carbonate. Dispersion of sheared, class 3a soil immersed in water is only an outward sign of the structural damage caused when the soil is sheared too wet. If the soil is dried instead, porosity is still lost. Mechanisms are suggested by which the structure of class 3a clay soils are improved by adding carbonate. The slumping of red-brown earths and the use of surface dressings of gypsum to prevent severe dispersion after cultivation wet are discussed. The structural stability of aggregates in the other five classes is briefly considered. Classes 1 and 2 require an ameliorant to be added, the rest pose few problems.
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Pahlevi Munirwan, Reza, and Munirwansyah Munirwansyah. "Assessing slope failure of soil erodibility problem by soil dispersive identification." E3S Web of Conferences 340 (2022): 01006. http://dx.doi.org/10.1051/e3sconf/202234001006.
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Dispersive soils are becoming a common building material. Due to their susceptibility to internal erosion and leakage, dispersive soils should only be used in combination with precise engineering measures to avoid catastrophic failures. Dispersive soils stabilization is critical and has been investigated in several studies conducted throughout the world. Erosion is a significant issue in structures built on sloping contours. As was the case with St. 670+250 Lipat Kajang road in Aceh Singkil. Soil erosion happens as a result of water’s dispersion and transport force. Dispersive soil is one of the factors that contribute to an increase in the soil erodibility index. The objective of this research is to develop a method for enhancing the soil’s dispersive qualities. In this investigation, specimens were prepared in three different soil mix plans (10%, 20%, and 30%) and then tested using a pinhole. The quantity of erodibility that happens in Sta. 670 + 250 Lipat Kajang - Aceh Singkil Regency is based on the results of testing the soil's dispersive properties because the soil in this area is highly dispersive.
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Lin, Shibin, and Jeramy C. Ashlock. "Improved seismic profiling by minimally invasive multimodal surface wave method with standard penetration test source (MMSW-SPT)." Geophysical Journal International 208, no. 3 (December 15, 2016): 1308–12. http://dx.doi.org/10.1093/gji/ggw471.
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Abstract Surface waves propagating in layered media inherently possess multimodal dispersion characteristics. However, traditional surface wave testing methods employing measurements at the free surface usually capture only a single apparent dispersion curve, especially when using short geophone arrays common to near surface and geotechnical-scale investigations. Such single-mode or fragmented multimode apparent dispersion curves contain only a fraction of the possible dispersion information, thus limiting the accuracy of inverted profiles. To enable more robust measurement of higher Rayleigh-wave modes, a recently developed hybrid minimally invasive multimodal surface wave method is combined herein with the widely used geotechnical standard penetration test (SPT), which is employed as a practical and ubiquitous downhole source. Upon superimposing surface wave dispersion data for a range of SPT impact depths within the soil, higher modes can be measured more consistently and reliably relative to traditional non-invasive testing methods. As a result, misidentification of multiple dispersion modes can be practically eliminated, significantly improving the accuracy and certainty of inversion results.
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Ellington, A., N. S. Badawy, and G. W. Ganning. "Testing gypsum requirements for dryland cropping on a Red-Brown Earth." Soil Research 35, no. 3 (1997): 591. http://dx.doi.org/10.1071/s96068.
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Gypsum requirements of a Red-Brown Earth used for dryland cropping were determined by 2 methods: those of the State Chemistry Laboratory (SCL) and of the Institute for Sustainable Irrigated Agriculture (ISIA). These are based, respectively, on exchangeable cations of soil by the Tucker method, and on water-soluble cations in a 1:5 water extract of soil. Information was also gained on longevity of gypsum effects on soil. Gypsum was applied to plots at rates 0·5, 1, and 2 times that predicted by ISIA, whereas the SCL method predicted that no gypsum was required. After 2 years, plots were split and the 3 rates of gypsum were either applied to soil previously untreated with gypsum, or re-applied to the soil treated 2 years before. According to the SCL test, the 0–10 cm soil depth of the Red-Brown Earth was not sodic (ESP <6), it was slightly magnesic (EMgP >25), and required no gypsum. However, it was found that gypsum lowered ESP, EMgP, and clay dispersion, with some effects extending into the 10–20 cm soil depth. With the ISIA method, the 0–10 cm soil depth was classed as low-sodic, but potentially dispersive; it required 2·5 t/ha of gypsum if soil was cultivated, but no gypsum if it was direct-drilled or was under pasture. One year after application, only the highest rate of gypsum (5 t/ha) significantly (P < 0·001) raised the electrolyte concentration of the soil suspension, although all rates reduced (P < 0·001) SAR, and the 2 higher rates reduced (P < 0·01) clay dispersion. However, these effects had disappeared after Year 3. There were significant increases in crop yields due to gypsum treatment in Year 1 (0·5–0·9 t/ha, P < 0·01) and Year 2 (0·3 t/ha, P < 0·001), but no response in Year 3. Fungal diseases seemed to reduce wheat responses, and the highest rate of gypsum caused chlorosis of lupins. Judging by crop performance, the ISIA method predicted an optimal rate of gypsum for the 0–10 cm layer of this soil type. The SCL prediction was also only for the 0–10 cm layer, but had it been used for deeper layers in the profile (the original intention for the technique), it would have given a recommendation not very different from the ISIA method.
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Zhang, Kun, Bai-Ru Lu, Yi-Hong Wang, Zhan Qu, and Le Qu. "Study on the Modification Formula of Earth Material Compound with Cement and Gravel by Single Lattice Theory." Advances in Civil Engineering 2020 (December 19, 2020): 1–10. http://dx.doi.org/10.1155/2020/8136570.
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Gravel and cement can effectively improve the low strength of traditional Earth materials. There have been few studies on test methods for raw soil-based composite admixtures. By introducing the theory of single lattice formula testing, the compressive strength of 10 formulas and 60 modified raw soil cubic specimens were tested. The failure process, failure mode, and compressive strength of specimens were studied. The effects of different formulations of raw soil on strength, peak displacement, and dispersion were analyzed. The results showed that cement content had a significant effect on the compressive strength and dispersion of earth material specimens. The optimal modification formula of cement, gravel, and raw soil was determined to be 0.1/0.08/0.82 (mass ratio). At the same time, the applicability of the test method was verified, which can be used as a reference for the experimental study on modification formulations of earth materials.
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Bawadi, Nor Faizah, Nur Jihan Syamimi Jafri, Ahmad Faizal Mansor, and Mohd Asri Ab Rahim. "Relationship between Shear Wave Velocity and SPT-N Value for Residual Soils." MATEC Web of Conferences 203 (2018): 04009. http://dx.doi.org/10.1051/matecconf/201820304009.
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The shear wave velocity (Vs) is an important dynamic parameter in the field of geotechnical engineering. One of the surface wave methods is Spectral Analysis of Surface Wave (SASW) has received attention in obtaining the shear wave velocity (Vs) profile by analysing the dispersion curve. SASW is a non-destructive test, fast and time-effective for field survey. Thus, this paper proposed the application of SASW method to obtain the shear wave velocity (Vs) to represent the soil profile. This paper aims to determine the shear wave velocity (Vs) profile using SASW method, where the testing has been conducted at three site of residual soils located in Damansara, Kuala Lumpur and Nilai area. In this study, it shows that the soil profile obtained from shear wave velocity value is similar pattern with profile that obtained using Standard Penetration Testing (SPT), which conventional used in field. The shear wave velocity are proportionally increase with depth.
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Jalil, Ahmed, Ahmed Benamar, and Mohamed Ebn Touhami. "Investigation of Internal Erosion Susceptibility of Core Soil from Three Dams." Journal of Civil Engineering and Construction 10, no. 2 (May 15, 2021): 59–68. http://dx.doi.org/10.32732/jcec.2021.10.2.59.
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Laboratory tests on internal erosion of cohesionless soils are often performed on cells submitted to a controlled seepage. The cell dimension depends on the grain size of tested soil and must meet the geometric and hydraulic scale requirements as regards to the modeled process. Three specimens collected from different zoned dams in Morocco were characterized for their geotechnical properties and dispersion sensitivity, and then submitted in two different cells to internal erosion (Hole Erosion Test) under controlled seepage. The erosion kinetics was measured, and soil classification was assessed as regards to the useful engineering guidelines. The results showed that specimen dimensions can affect the erosion parameters which are quite different from a cell to another. Even though the derived erosion coefficient values are different from the two testing cells, the classification of the three soils regarding the susceptibility to erosion, using engineering guidelines, indicated that the tested soils fall overall in neighboring erosion classifications. However, the soil involving the lower clay content provided the greatest resistance against internal erosion.
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Weiner, Thorsten, and Markus Thewes. "New testing method for the prediction of the dispersion of soil in slurry shield tunnelling." Geomechanics and Tunnelling 11, no. 5 (October 2018): 471–78. http://dx.doi.org/10.1002/geot.201800043.
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Kunberger, T., and M. A. Gabr. "Laboratory testing and microanalysis of colloidal mobilization from a glacial till." Canadian Geotechnical Journal 48, no. 7 (July 2011): 1116–24. http://dx.doi.org/10.1139/t11-030.
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The effect of the dispersion and piping of clay fines — colloid mobilization — as a means of remediating subsurface contamination was investigated. Prior colloid mobility research has focused on mitigating colloidal movement to reduce contaminant transport or monitoring colloids to determine the extent of mobility and contamination transport. To date, limited work has been performed to evaluate remediation efficiency associated with the removal of clay-sized (colloidal) particles and related sorbed contamination. Laboratory flow-through tests were performed on a glacial till from a radioactive cesium contaminated site. Post-testing analysis comprised mass balance checks, grain-size distribution testing, and microscopic analysis of removed particles. Results showed the potential of initiating and maintaining clay dispersion and piping, thus establishing a means to mobilize colloids and subsequently remove them from the subsurface environment. Beneficial effects of hydraulic gradient and ionic strength manipulations were influenced by soil properties, such as cation exchange capacity, clay content, and average pore diameter. In general, colloid mobilization testing results found that extreme levels of mobilization typically resulted in particle trapping and an overall reduction in colloidal removal, while the effect of more moderate levels was mobilization with increased rates of removal.
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Leibowitz, Caleb, and Anthony J. Weiss. "Underground Cavity Detection through Group Dispersion of a GPR Signal." Remote Sensing 14, no. 19 (September 26, 2022): 4808. http://dx.doi.org/10.3390/rs14194808.
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We present a novel method for underground cavity detection using cross-borehole ground-penetrating radar (GPR). Modeling the soil-cavity system as a filter allows us to estimate the group dispersion of the GPR signal induced by propagation through a cavity. We adopt a hypothesis-testing approach based on the observed group dispersion and propose a method which allows us to detect cavities with high probability. The proposed method is validated on both simulated and real measurements. Geologic clutter that causes conventional methods to fail has negligible impact on the efficacy of the proposed method, and the proposed method may be combined with conventional methods to provide a more robust and effective cavity-detection solution.
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Dourado, Thayse Aparecida, Laura Fernanda Simões da Silva, and Mara de Andrade Marinho. "Performance of a reciprocal shaker in mechanical dispersion of soil samples for particle-size analysis." Revista Brasileira de Ciência do Solo 36, no. 4 (August 2012): 1131–48. http://dx.doi.org/10.1590/s0100-06832012000400008.
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The dispersion of the samples in soil particle-size analysis is a fundamental step, which is commonly achieved with a combination of chemical agents and mechanical agitation. The purpose of this study was to evaluate the efficiency of a low-speed reciprocal shaker for the mechanical dispersion of soil samples of different textural classes. The particle size of 61 soil samples was analyzed in four replications, using the pipette method to determine the clay fraction and sieving to determine coarse, fine and total sand fractions. The silt content was obtained by difference. To evaluate the performance, the results of the reciprocal shaker (RSh) were compared with data of the same soil samples available in reports of the Proficiency testing for Soil Analysis Laboratories of the Agronomic Institute of Campinas (Prolab/IAC). The accuracy was analyzed based on the maximum and minimum values defining the confidence intervals for the particle-size fractions of each soil sample. Graphical indicators were also used for data comparison, based on dispersion and linear adjustment. The descriptive statistics indicated predominantly low variability in more than 90 % of the results for sand, medium-textured and clay samples, and for 68 % of the results for heavy clay samples, indicating satisfactory repeatability of measurements with the RSh. Medium variability was frequently associated with silt, followed by the fine sand fraction. The sensitivity analyses indicated an accuracy of 100 % for the three main separates (total sand, silt and clay), in all 52 samples of the textural classes heavy clay, clay and medium. For the nine sand soil samples, the average accuracy was 85.2 %; highest deviations were observed for the silt fraction. In relation to the linear adjustments, the correlation coefficients of 0.93 (silt) or > 0.93 (total sand and clay), as well as the differences between the angular coefficients and the unit < 0.16, indicated a high correlation between the reference data (Prolab/IAC) and results obtained with the RSh. In conclusion, the mechanical dispersion by the reciprocal shaker of soil samples of different textural classes was satisfactory. The results allowed recommending the use of the equipment at low agitation for particle size- analysis. The advantages of this Brazilian apparatus are its low cost, the possibility to simultaneously analyze a great number of samples using ordinary, easily replaceable glass or plastic bottles.
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Chen, Zhuoshi, Baofeng Jiang, Jingjing Song, and Wentao Wang. "Accurate Sparse Recovery of Rayleigh Wave Characteristics Using Fast Analysis of Wave Speed (FAWS) Algorithm for Soft Soil Layers." Applied Sciences 8, no. 7 (July 23, 2018): 1204. http://dx.doi.org/10.3390/app8071204.
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This paper presents a novel fast analysis of wave speed (FAWS) algorithm from the waveforms recorded by a random-spaced geophone array based on a compressive sensing (CS) platform. Rayleigh-type seismic surface wave testing is excited by a hammer source and conducted to develop the phase velocity characteristics of the subsoil layers in Shenyang Metro line 9. Data are filtered by a bandpass filter bank to pursue the dispersive profiles of phase velocity at various frequencies. The Rayleigh-type surface-wave dispersion curve for the soil layers at each frequency is conducted by the ℓ1-norm minimization algorithm of CS theory. The traditional frequency-wavenumber transform technique and in-site downhole observation are employed as the comparison of the proposed technique. The experimental results indicate the proposed FAWS algorithm has a good agreement with both the results of conventional even-spaced geophone array and the in-site measurements, which provides an effective and efficient way for accurate non-destructive evaluation of the surface wave dispersion curve of the soil.
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Karray, Mourad, and Guy Lefebvre. "Significance and evaluation of Poisson's ratio in Rayleigh wave testing." Canadian Geotechnical Journal 45, no. 5 (May 2008): 624–35. http://dx.doi.org/10.1139/t08-016.
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Important progress has been made in the past 20 years in the use of surface-wave testing in soil characterization. However, the effect of Poisson's ratio on the construction of the theoretical dispersion relationships, associated with the inversion process, has not received enough attention and remains poorly documented. Five ideal profiles with different degrees of variation of shear-wave velocity with depth and three published case records are considered in this paper to study the effect of Poisson's ratio on Rayleigh wave phase velocities. The effect of the variation of Poisson's ratio on the evaluation of shear-wave velocity profiles (Vs) is also examined. Poisson's ratio is generally assumed in surface-wave testing, and therefore the paper also examines the possibility of evaluating its value using a multi-mode inversion process. The results of surface-wave testing obtained at two experimental sites are then used to illustrate the potential of surface-wave testing to evaluate the Poisson's ratio profile in addition to the Vs profile. The impact of Poisson's ratio in Rayleigh wave testing is shown to be significantly more important than previously demonstrated. The error resulting from Poisson's ratio does not depend solely on the magnitude of the inaccuracy. A multi-mode inversion process is shown to be a useful tool to determine the Poisson's ratio profile, leading to a more accurate soil characterization.
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Nevels, James B. "Soil Suction Dispersion and Statistical Analysis with Depth at the Medford Airport." Transportation Research Record: Journal of the Transportation Research Board 1596, no. 1 (January 1997): 76–83. http://dx.doi.org/10.3141/1596-12.
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The use of soil suction measurements has steadily increased in geotechnical practice. A current standard test procedure that describes the use of laboratory filter papers as passive sensors to measure the soil matric and total suction is ASTM D5298-94. The principal objective of the research presented here was to evaluate dispersion of suction measurements with depth using the filter paper method described in the ASTM standard. In a single test boring to a depth of 5.33 m, 35 samples were taken at intervals of 152.4 mm. Each sample was separated into four replicate samples. The matric and total suction of each of the 35 sample intervals were then measured, resulting in a total of 278 suction measurements. To manage this volume of tests, the sample size was split approximately in half, and each portion was separately tested. This approach led to severall insights into the test procedure, such as the effect of delay in transferring the filter paper from the specimen container into the metal container. Sampling and testing are described. The dispersion of both the total and the matric suction measurements was characterized in three ways: the range of measurements in each sample interval, the standard deviation of measurements in each sample interval, and an error function defined as the difference between each measurement and the mean for the sample interval. Each of these statistics was plotted as a histogram. A chi-squared test was applied to measure the goodness-of-fit of a t-distribution fitted to the error as defined by the difference between each measurement and the mean for that sample interval. Results indicate precision for total and matric suction measurements of 0.0540 log kPa within one standard deviation. Analysis does not indicate a substantial difference between the error associated with total suction measurements and that associated with matric suction measurements. A brief description of the conventional geotechnical site characterization is presented for the Medford Airport.
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Wang, Yonghong, Jiamin Jin, Qijun Zhang, Ming Zhang, Xiwei Lin, Xin Wang, and Peiyuan Lin. "Accuracy of Non-Destructive Estimation of Length of Soil Nails." Buildings 13, no. 7 (July 3, 2023): 1699. http://dx.doi.org/10.3390/buildings13071699.
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The effective length of soil nails is one of the critical parameters ensuring the reinforcing effect, and its accurate estimation is of great significance for the safety of the slope and deep foundation pit supporting projects. Traditional quality insurance methods, such as nail pullout tests, suffer from a series of drawbacks including being destructive, high cost, and time-consuming. In contrast, non-destructive testing (NDT) has been increasingly applied in various engineering fields in the past decades given its advantages of not damaging the material and easy operation. However, the current application of NDT in soil nail length measurement is relatively limited, and its accuracy and reliability are yet to be quantitatively evaluated. This paper introduces three methods for estimating soil nail length based on guided wave theory and collects 116 sets of NDT data for nail length. The accuracy of the NDT in soil nail prediction is statistically analyzed using the model bias method. The results show that those methods can accurately predict the nail length with an average error of less than 3% and a low dispersion of 12%. The accuracy of the NDT methods is not affected by the hammer type or estimation method. Furthermore, this paper proposes a model calibration to the original NDT method, which improves the model’s average accuracy by 3% and reduces dispersion by 4% without increasing computational complexity. Finally, the probability distributions of the model biases are characterized. This study can provide practical tools for fast estimation of in situ nail length, which is of high significance to supporting slopes and deep foundation pits.
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Shackelford, Charles D., and Catherine S. Hong. "Comparative analyses of alternative breakthrough curves from cumulative mass column testing of soil–bentonite backfills." Canadian Geotechnical Journal 57, no. 8 (August 2020): 1197–214. http://dx.doi.org/10.1139/cgj-2019-0468.
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The results of eight cumulative mass column tests were analyzed via several different methods to evaluate the dispersion coefficient, D, and the retardation factor, Rd, governing the migration of chloride (Cl−), potassium (K), and zinc (Zn) through soil–bentonite backfills for vertical cutoff walls. Regression of the measured relative (effluent) concentration (RC) breakthrough curves (BTCs) resulted in relatively accurate determinations of Rd, but relatively inaccurate determinations of D for all three solutes. Values of Rd based on dimensionless time, T, corresponding to an RC of 0.5 were underestimated for all three solutes due to the significance of diffusion on solute transport. With a few exceptions, Rd for K and Zn based on analyses of the steady-state portions of measured cumulative mass ratio (CMR) BTCs and T – CMR BTCs were relatively accurate, whereas analysis of measured T – CMR BTCs was more accurate for determining Rd of Cl−. Overall, there is no advantage to analyzing the results of cumulative mass column tests in the form of RC BTCs, whereas the CMR and T – CMR BTCs offer the advantage of determining Rd based on simple linear regressions of the steady-state portions of the BTCs, i.e., provided steady-state solute transport has been established.
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Bortoluzzi, Edson Campanhola, Cristiano Poleto, Álvaro José Baginski, and Vanderlei Rodrigues da Silva. "Aggregation of subtropical soil under liming: a study using laser diffraction." Revista Brasileira de Ciência do Solo 34, no. 3 (June 2010): 725–34. http://dx.doi.org/10.1590/s0100-06832010000300014.
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Laser diffraction (LD) provides detailed analysis of particle size distribution. Its application to testing the stability of soil aggregates can assist studies on the aggregation of soils with contrasting electrochemical properties. The objectives of the present work were: (a) to propose a protocol for using LD to study soil aggregation, (b) to study the aggregation of an Acrisol under the influence of different doses and forms of lime. Samples were collected in 2005 from a Brazilian Acrisol that in 1994 had received 0.0; 2.0; 8.5 and 17.0 Mg ha-1 of lime, left on the soil surface or incorporated. Aggregates from 4.76 to 8.00 mm diameters were studied using the traditional method proposed by Kemper & Chepil (1965), with wet sieving, while aggregates from 1.00 to 2.00 mm were studied using a CILAS® laser diffractometer that distinguishes particles ranging from 0.04 to 2,500.00 μm. LD readings were made after six consecutive pre-treatments, using agitation times, a chemical dispersion agent and ultrasound. Mean Weighted Diameter (MWD) and the Aggregate Stability Index (ASI) calculated, using the traditional method does not discriminate the treatments. However, LD is able to produce detailed data on soil aggregation, resulting in indexes of stability of aggregates that are linearly related to the doses of lime applied (MWD: R² = 0.986 and ASI: R² = 0.876). It may be concluded that electrochemical changes in the Brazilian Acrisol resulting from incorporated lime affect the stability of aggregates, increasing stability with increased doses of lime.
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Cerli, C., L. Celi, K. Kalbitz, G. Guggenberger, and K. Kaiser. "Separation of light and heavy organic matter fractions in soil — Testing for proper density cut-off and dispersion level." Geoderma 170 (January 2012): 403–16. http://dx.doi.org/10.1016/j.geoderma.2011.10.009.
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Brzeziński, Karol, Maciej Maślakowski, and Paweł Liszewski. "Evaluation of the Volume Measurement Optical Method Suitability for Determining the Relative Compaction of Soils." Civil Engineering Journal 4, no. 9 (September 30, 2018): 2052. http://dx.doi.org/10.28991/cej-03091138.
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The goal of this paper is evaluation of the volume measurement optical method suitability for determining relative compaction of soils. The Structure for Motion technique was utilized in order to achieve the goal by making the three-dimensional models (with Bentley ContextCapture software). Created models were used in volume measurement of the pit-holes. The results were compared with the basic methods: the sand cone test and the water method. The laboratory tests were carried out in two stages. In the first stage, the optical method was tested in similar to operating conditions. Ten holes were made in the soil and the volumes were measured with three different methods. The results were compared and submitted for statistical analysis. Statistical analysis showed the potential of optical method. The second laboratory test focused on repeatability and accuracy of measurement. The volume of the vessel imitating a pit-hole was obtained. The results of the second stage showed that the optical method has better accuracy and lower statistical dispersion compared with sand method. On this basis it can be concluded that optical method of volume measurement has great potential in soil compaction testing.
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Al-Hunaidi, M. O. "Difficulties with phase spectrum unwrapping in spectral analysis of surface waves nondestructive testing of pavements." Canadian Geotechnical Journal 29, no. 3 (June 1, 1992): 506–11. http://dx.doi.org/10.1139/t92-055.
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Spectral analysis of surface waves (SASW) is a nondestructive and in situ method for determining the stiffness profiles of soil and pavement sites. This method involves the generation and measurement of surface Rayleigh waves. By exploiting the dispersive characteristic of these waves in layered systems, the SASW method provides information on the variation of stiffness with depth. This paper presents the results of a case study for near-surface profiling of a pavement site using the SASW method. In this study, inconsistencies were observed in the dispersion curve of the site when the usual procedure of unfolding the relative phase spectrum was followed. A correction procedure to eliminate these inconsistencies is suggested and discussed. The thickness and wave velocities of the various layers obtained with the SASW method, after applying the correction procedure, matched closely those determined from cored samples and cross-hole tests. Key words : nondestructive testing, pavement, layered media, Rayleigh wave, spectral analysis, shear wave velocity, wave propagation.
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Yang, Jun, Yi Song, Rui Fu, Changwei Lu, and Hongcheng Liu. "Experimental Study on the Comprehensive Identification and Improvement of Dispersive Soil in Western Jilin Province, China." Geofluids 2021 (September 14, 2021): 1–14. http://dx.doi.org/10.1155/2021/6267212.
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In this study, physical experiments, clay mineral determination, and pH testing were performed to examine the basic properties of soil samples from a soil material yard selected for dam construction at Hua’ao Lake, Qian’an County, Jilin Province, China. The results show that the soil in the study area is cohesive, the mineral content of illite in the illite/montmorillonite mixed layer is approximately 50%, and the pH value of the environment from which the soil samples were taken is 8.43-8.91. These factors enable the soil in this area to be dispersed. The dispersibility of the soil sampled from this area was evaluated by a double hydrometer test, a pinhole test, a fragmentation test, a sodium adsorption ratio test, and determination of the percentage of exchangeable sodium ions. Because these test methods had inconsistent results, the test methods in combination with the typical geomorphic conditions of the sampling points were ultimately used to comprehensively evaluate the soil dispersion. The results demonstrate that the cohesive soil sampled from the soil material yard is dispersible and must be treated with improvement measures before it can be used as a filling material for the dam. To improve the dispersive and transitional soil, 2%, 3%, 4%, 5%, and 6% L1Fa2 (a 1 : 2 ratio of lime and fly ash) and C1L1Fa4 (a 1 : 1 : 4 ratio of cement, lime, and fly ash) were used to perform improvement tests on 10 groups of dispersive soil samples and 10 groups of transitional soil samples. The results reveal that the addition of 4% L1Fa2 best improves the dispersive soil in this area. Therefore, the soil intended for this project should be used as a dam-building material after improvement with the 4% addition of L1Fa2.
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Shrivastava, Rohit Kumar, and Stefan Luding. "Effect of disorder on bulk sound wave speed: a multiscale spectral analysis." Nonlinear Processes in Geophysics 24, no. 3 (August 9, 2017): 435–54. http://dx.doi.org/10.5194/npg-24-435-2017.
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Abstract. Disorder of size (polydispersity) and mass of discrete elements or particles in randomly structured media (e.g., granular matter such as soil) has numerous effects on the materials' sound propagation characteristics. The influence of disorder on energy and momentum transport, the sound wave speed and its low-pass frequency-filtering characteristics is the subject of this study. The goal is understanding the connection between the particle-microscale disorder and dynamics and the system-macroscale wave propagation, which can be applied to nondestructive testing, seismic exploration of buried objects (oil, mineral, etc.) or to study the internal structure of the Earth. To isolate the longitudinal P-wave mode from shear and rotational modes, a one-dimensional system of equally sized elements or particles is used to study the effect of mass disorder alone via (direct and/or ensemble averaged) real time signals, signals in Fourier space, energy and dispersion curves. Increase in mass disorder (where disorder has been defined such that it is independent of the shape of the probability distribution of masses) decreases the sound wave speed along a granular chain. Energies associated with the eigenmodes can be used to obtain better quality dispersion relations for disordered chains; these dispersion relations confirm the decrease in pass frequency and wave speed with increasing disorder acting opposite to the wave acceleration close to the source.
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Youn, Jun-Ung, Yun-Wook Choo, and Dong-Soo Kim. "Measurement of small-strain shear modulus Gmax of dry and saturated sands by bender element, resonant column, and torsional shear tests." Canadian Geotechnical Journal 45, no. 10 (October 2008): 1426–38. http://dx.doi.org/10.1139/t08-069.
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The bender element method is an experimental technique used to determine the small-strain shear modulus (Gmax) of a soil by measuring the velocity of shear wave propagation through a sample. Bender elements have been applied as versatile transducers to measure the Gmax of wet and dry soils in various laboratory apparatuses. However, certain aspects of the bender element method have yet to be clearly specified because of uncertainties in determining travel time. In this paper, the bender element (BE), resonant column (RC), and torsional shear (TS) tests were performed on the same specimens using the modified Stokoe-type RC and TS testing equipment. Two clean sands, Toyoura and silica sands, were tested at various densities and mean effective stresses under dry and saturated conditions. Based on the test results, methods of determining travel time in BE tests were evaluated by comparing the results of RC, TS, and BE tests. Also, methods to evaluate Gmax of saturated sands from the shear-wave velocity (Vs) obtained by RC and BE tests were investigated by comparing the three sets of test results. Biot’s theory on frequency dependence of shear-wave velocity was adopted to consider dispersion of a shear wave in saturated conditions. The results of this study suggest that the total mass density, which is commonly used to convert Gmax from the measured Vs in saturated soils, should not be used to convert Vs to Gmax when the frequency of excitation is 10% greater than the characteristic frequency (fc) of the soil.
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Howie, John A., and Ali Amini. "Numerical simulation of seismic cone signals." Canadian Geotechnical Journal 42, no. 2 (April 1, 2005): 574–86. http://dx.doi.org/10.1139/t04-120.
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Numerical analysis can provide insight into the effect of ground conditions on seismic signals recorded in downhole seismic testing. As part of a study of the interpretation of seismic cone data in complex ground conditions, this paper deals with the cases of wave propagation in (i) homogeneous soil and (ii) soil of increasing stiffness with depth. The main purpose of this study was to assess the validity of the use of the finite difference program FLAC for the simulation of the downhole seismic test. For realistic assumptions of material stiffness and damping, the main characteristics of field seismic cone penetration test (SCPT) seismic data were reproduced in the simulated data. Both displayed the same general shape of signal, number of oscillations, signal attenuation, frequency content, compression wave component (near-field effect), signal widening, and shift of the peak of the frequency spectrum with depth. Damping was shown to cause signal widening and dispersion, and the shear wave velocity, Vs, interpreted from the simulated wave traces varied with the interval method used to determine it. For a case history of field data, it was found that Vs varied by about 3%, depending on the analysis method used. The results show that finite difference modeling of wave propagation can provide useful insights into the factors affecting the interpretation of downhole seismic tests.Key words: seismic cone testing, shear wave velocity, signal widening, near-field effect, numerical simulation, finite difference.
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Zhao, Yanrong, Yufeng Wei, Rong Rong, Xiaosong Dong, Zhihao Zhang, Yong Huang, and Jinguo Wang. "A Novel Slug Heat Test Theoretical and Indoor Model Research for Determining Thermal Property Parameters of Aquifers and Rock-Soil Skeletons." Water 14, no. 19 (September 26, 2022): 3020. http://dx.doi.org/10.3390/w14193020.
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As important parameters for characterizing heat transfer, thermal property parameters of aquifers and rock-soil skeletons have important research significance in the development and utilization of geothermal resources. The slug heat test is inspired by the slug test, and the heat is instantaneously excited in the test well so as to change the temperature of test section in the test well instantaneously. Based on the thermal radial convection-dispersion theory and the principle of heat conservation, the theoretical model of the slug heat test is established, and the model is solved by Laplace transform and inverse transform to obtain multiple sets of standard curves under different conditions. The slug heat tests were conducted in the indoor model, the slug heat test data under different hydrodynamic conditions were fitted with the standard curves and the thermal property parameters, including effective thermal conductivity, stagnant thermal conductivity, thermal mechanical dispersion coefficient, thermal dispersive degree, thermal diffusivity, heat capacity of aquifer, heat capacity and thermal conductivity of rock-soil skeletons, were accurately obtained. The test results are in good agreement with the empirical values. Meanwhile, the effective thermal conductivity of the aquifer also clearly increases with the increase of flow rate. The excitation temperature difference had little effect on the effective thermal conductivity of the aquifer. At the same time, numerical simulation methods are used to establish a numerical model consistent with the indoor test model, and the numerical model is assigned with the thermal property parameters obtained from the indoor slug heat test, and the measured values of temperature changes in the test well during the slug heat test under different hydrodynamic and excitation strength conditions are compared with the simulated values for verification. The research results show that the slug heat test has the characteristics of high applicability, simple operation and rapid testing, and can effectively determine the thermal properties parameters of aquifers and rock-soil skeletons.
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Asuncion, Fei Xyza B., Daniel L. Brabec, Mark E. Casada, Ronaldo G. Maghirang, Frank H. Arthur, James F. Campbell, Kun Yan Zhu, and Daniel E. Martin. "Spray Characterization of Aerosol Delivery Systems for Use in Stored Product Facilities." Transactions of the ASABE 63, no. 6 (2020): 1925–37. http://dx.doi.org/10.13031/trans.14010.
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HighlightsHandheld sprayers generated larger droplets and wider droplet size distributions than compressed gas sprayers.Sprayers with higher pressure and nozzles with wider spray angle produced smaller droplets.Droplet size distribution influenced spray coverage, mass concentration, deposition, and sprayer efficacy.The handheld sprayers had less spray coverage and efficiency than the compressed gas sprayers.The deposition at different locations was influenced by the volume of the space, aerosol dosage, and spray time.Abstract. Aerosol insecticides, including pyrethrins, can be used as methyl bromide replacements to control stored product insects inside flour mills and rice mills. The effectiveness of aerosol application for insect control requires knowing the spray characteristics of the equipment to be used and understanding factors that influence the effectiveness of insecticide application. The objectives of this study, as part of efforts to optimize aerosol applications, were to evaluate the characteristics of six aerosol delivery systems (two handheld sprayers and compressed gas sprayer systems fitted with two types of manifolds and two types of nozzles), estimate the dispersion and deposition of aerosol in a simulated stored product facility, and determine how the dispersion and deposition are affected by the characteristics of the sprayers. Results showed that the spray systems differed significantly in spray characteristics. The compressed gas sprayers generated significantly smaller droplets, more uniform droplet size distribution, and better spray coverage than the handheld sprayers. The ellipsoidal nozzle produced significantly smaller droplets than the circular nozzle. While the type of manifold had no significant effect on deposition, higher aerosol dosage and spray time resulted in significantly higher deposition. Results of this study will be used to improve spray techniques for stored product insect control, to validate computational fluid dynamics modeling of aerosol application, and to improve testing methods in large-scale spray testing inside commercial facilities. Keywords: APS spectrometer, Droplet size distribution, HELOS KR-Vario, Mass deposition, Spray characteristics, Spray nozzles.
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Amiaud, Bernard, Anne Bonis, and Jan-Bernard Bouzillé. "Conditions de germination et rôle des herbivores dans la dispersion et le recrutement d'une espèce clonale : Juncus gerardi Lois." Canadian Journal of Botany 78, no. 11 (November 1, 2000): 1430–39. http://dx.doi.org/10.1139/b00-117.
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The finding of new individuals of a clonal plant, Juncus gerardi, raised the question of modalities for the colonization of new sites by this species. Indeed, the existence of seedlings has not been observed in the field, nor reported in the literature for European marshes. Among the parameters limiting recruitment, we examined the soil seed bank, which appeared extremely small. Many seeds could be found in bovine feces but few were found in equine feces. Futhermore, bovines are not only important for seed dispersion, but also for the improvement of the germinative capacities: the seed germination rate of Juncus gerardi was doubled after digestive transit. Germination testing showed that this species is largely tolerant to salinity (from 0 to 26,4 mS·cm-1). The germination rate was maximal with a thermoperiod of 10-20°C but null for a 0-10°C thermoperiod. Germination was improved by immersion and was light dependent. The critical phase for colonization success in new habitats could be primarily seedling survival. Recruitment success in Juncus gerardi seems to be a rare event, requiring the combination of favorable conditions related to climate and gap openings in swards.Key words: germinative capacities, feces, clonal plant, grazers, endozoochory, pastures.
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Ryden, Nils, and Choon Byong Park. "Fast simulated annealing inversion of surface waves on pavement using phase-velocity spectra." GEOPHYSICS 71, no. 4 (July 2006): R49—R58. http://dx.doi.org/10.1190/1.2204964.
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The conventional inversion of surface waves depends on modal identification of measured dispersion curves, which can be ambiguous. It is possible to avoid mode-number identification and extraction by inverting the complete phase-velocity spectrum obtained from a multichannel record. We use the fast simulated annealing (FSA) global search algorithm to minimize the difference between the measured phase-velocity spectrum and that calculated from a theoretical layer model, including the field setup geometry. Results show that this algorithm can help one avoid getting trapped in local minima while searching for the best-matching layer model. The entire procedure is demonstrated on synthetic and field data for asphalt pavement. The viscoelastic properties of the top asphalt layer are taken into account, and the inverted asphalt stiffness as a function of frequency compares well with laboratory tests on core samples. The thickness and shear-wave velocity of the deeper embedded layers are resolved within 10% deviation from those values measured separately during pavement construction. The proposed method may be equally applicable to normal soil site investigation and in the field of ultrasonic testing of materials.
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Zhang, Zhihong, Shuo Yuan, Qinghui Lai, Guobiao Zuo, and Huseyin Guler. "Bioinspired Imbricated Microthorn Scale Surfaces and their Abrasive Wear Performance." Journal of the ASABE 65, no. 2 (2022): 209–20. http://dx.doi.org/10.13031/ja.14876.
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HighlightsImproving the wear resistance of soil-engaging components is an urgent need for the agricultural machinery industry.Sandfish (Scincus scincus) epidermis with exceptional wear resistance was selected as a bionic prototype.By adopting a bionic engineering approach, a novel bioinspired microthorn scale surface was designed and prepared.Numerical simulations were performed with EDEM to investigate the wear resistance mechanism.Abstract. To solve the problem of abrasive wear failure of the soil-engaging components of agricultural machinery, the imbricated microthorn scale structure of the sandfish (Scincus scincus) epidermis surface was selected as a bionic prototype. By adopting a bionic engineering approach, nine bionic microthorn scale surface specimens with different geometric structure parameters were designed and prepared. Wear resistance tests were performed in a rotating abrasive wear testing system. The results of the wear tests showed that the imbricated microthorn scale structured surfaces had substantially less abrasion loss than a conventional smooth surface. The influence of the geometric structure parameters on the wear performance was also identified. Numerical simulations were performed to explore the wear resistance mechanism of the imbricated microthorn scale structured surfaces. The abrasion of the bionic surfaces mainly occurred at the edge of the microthorn that faced the abrasive particle flow. The trajectory of subsequent abrasive particle flow was modified by the large dispersion of particle flow; hence, the number of particles that impacted the surface decreased. Therefore, the wear resistance performance of the bionic surfaces was enhanced. This bioinspired surface can provide a technical reference to mitigate the abrasive wear failure of the soil-engaging components of agricultural machinery. Keywords: Abrasive wear, Archard wear, Bionic design, Discrete element method, Scale surface.
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Makarov, V. A., O. I. Zhuravleva, and A. V. Shemyakin. "Pneumatic Sucker-Rod Machine for Dispersing Solid Mineral Fertilizers." Agricultural Machinery and Technologies 13, no. 3 (July 22, 2019): 30–33. http://dx.doi.org/10.22314/2073-7599-2019-13-3-30-33.
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In the world practice of introducing solid mineral fertilizers, almost 90 percents of the machines used are equipped fertilizer application is about 10 percents. It has been still confi rmed that their small width of application results in insuffi cient productivity, and in practice they are not used for introducing the main amount of fertilizers in pre-sowing soil preparation. (Research purpose) Designing a pneumatic sucker-rod machine providing for increased uniformity of fertilizer dispersing when introducing the main amount of fertilizers and further dressing vegetative plants. (Materials and methods) The authors obtained relationships allowing to determine rational constructive-and-kinematic parameters of a device for fertilizer metering and distributing through ejectors and dispersing surfaces using the laws and methods of classical mechanics and mathematics. Experimental studies were carried out using a developed and manufactured sample, and testing its operability in fi eld conditions using standard and specifi c techniques. It was determined that the quality of fertilizer dispersing with a pneumatic sucker-rod machine is mainly aff ected by the uniformity of their supply by reel-type units to the air stream and rods with holes, and the pattern of fertilizer distribution to ejectors depending on the distance between them. (Results and discussion) The authors have made patterns of fertilizer transportation and metering with reel-type sowing units and determined the method and pattern of distributing an air-mineral mixture through the rod channels. The authors obtained a mathematical description of the processes of mineral fertilizer application, taking into account the qualitative indicators of their uniform dispersion over the fi eld surface. It was noted that the uneven distribution of fertilizers when the rod length is appropriate corresponds to the design standards. (Conclusions) The authors have revealed that the rate of distribution unevenness of ammonium nitrate amounted to 8 percents. It has been found that even at the machinery designing stage it is possible to evaluate performance indicators in terms of unevenness depending on the metering quality and the distance between sowing ejectors.
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Malhi, Sukhdev S., Jeff J. Schoenau, and Cynthia A. Grant. "A review of sulphur fertilizer management for optimum yield and quality of canola in the Canadian Great Plains." Canadian Journal of Plant Science 85, no. 2 (April 1, 2005): 297–307. http://dx.doi.org/10.4141/p04-140.
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In the Parkland region of the Canadian prairies, Canola (Brassica napus L. or Brassica rapa L.) is an important cash crop. Canola has a high requirement for sulphur (S). However, many soils in this region are deficient or potentially deficient in plant-available S for optimum canola seed yield. Application of sulphate-S at about 15–30 kg S ha-1 is usually sufficient to prevent S deficiency in canola on most of the S-deficient soils. Application of sulphate-S to canola at seeding time gives the highest increase in yield and S uptake. Deficiencies of S in canola plants can be prevented and/or corrected and seed yield improved with the use of sulphate-S fertilizers in the growing season. Application of sulphate-S at bolting can substantially restore seed yield, while an application at early flowering can moderately correct S deficiency damage. Side-banding is the most effective way to apply sulphate-S fertilizers to produce maximum seed yield and to prevent any damage to canola seedlings from seed-row placement. In relatively moist areas, broadcast-incorporation methods can produce seed yield similar to side-banding in most years. Elemental S fertilizers were not effective in increasing seed yield in the year of application, and were generally less effective than sulphate-S fertilizer even after multiyear annual applications, especially when applied in spring. Autumn-applied elemental S was more effective than spring-applied elemental S. Banding delayed availability of elemental S as compared to broadcast application. Use of granular elemental S products is not reliable for optimum seed yield of canola under Canadian prairie conditions on S-deficient soils, particularly in the initial year and with spring application or band placement. Elemental S fertilizers may have a role to maintain or build-up sulphate-S levels in soils marginally low in S where residual benefits are desirable, but management decisions should consider both immediate and long-term effects of S fertilizer on seed yield, seed quality and economics. The findings suggest the need of future research to increase dispersion and distribution of S particles from granules for faster oxidation of elemental S in soil, and to develop elemental S fertilizer products/formulations that can be used on a commercial scale to prevent and/or correct S deficiency in the growing season to optimize seed yield and quality of canola. Research is also required to determine the long-term effects of balanced application of S with other nutrients on soil quality, accumulation and distribution of nitrate-N, sulphate-S and other nutrients in the soil profile, efficiency of nutrient, water and energy use, and crop diseases. More research should be conducted in relation to soil/plant tissue testing issues for optimum seed yield and quality of canola. Key words: Balanced fertilization, canola, elemental S fertilizers, method of application, rate of S, seed quality, seed yield, sulphate-S fertilizers
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Saxton, Keith E. "Agricultural wind erosion and air quality impacts: A comprehensive research program." American Journal of Alternative Agriculture 11, no. 2-3 (September 1996): 64–70. http://dx.doi.org/10.1017/s0889189300006780.
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AbstractWith the passage of the 1990 Clean Air Act came the responsibility to monitor and control particulates in the size range 10 μ and smaller (PM10). Many urban areas, particularly in the western U.S., have experienced concentrations of fugitive dust particulates from upwind sources that exceed the federal health standards. Often a significant amount of this material is generated upwind on agricultural fields, and then is entrained and transported in the regional air mass, thus degrading the air quality in downwind urban regions. Current technology cannot adequately quantify the fugitive dust emitted and transported from agricultural sources, nor specify adequate control methods. A comprehensive research plan recently was developed and initia ted for the Columbia Plateau of eastern Washington State that involves multiple disciplines and several state and federal agencies. This research has several components: characterizing the soil, vegetation and climate in a region of 136,000 km2; developing wind erosion and fugitive dust emission relationships for individual farm fields; developing and applying transport-dispersion-deposition models of the region; selecting and testing farm-level control strategies; and providing public information to both the urban and farm communities for understanding the problem and developing management plans. Simultaneous receptor analyses and public health research combine to make this a comprehensive regional research effort on fugitive dust emissions and impacts.
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Kohn, Jacqueline, Gregory S. Piorkowski, Nicole E. Seitz Vermeer, and Janelle F. Villeneuve. "Assessment of Wood Chips and Agricultural Residues as Denitrifying Bioreactor Feedstocks for Use in the Canadian Prairies." Journal of the ASABE 66, no. 3 (2023): 579–90. http://dx.doi.org/10.13031/ja.15412.
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Highlights Performance of denitrifying bioreactors in Alberta was evaluated. Barley straw was more effective in reducing nitrate compared to wood chips. Hydraulic retention time, feedstock, and season are the primary factors affecting nitrate removal. Abstract. This study evaluated the performance of pilot-scale denitrifying bioreactors (LWD: 6 × 0.6 × 1m) filled with different carbon substrates, including barley straw, hemp straw, and woodchips, for removing dissolved nitrogen from simulated subsurface drainage at two representative geographic locations in Alberta. In this study, the bioreactors were tested under varying hydraulic retention times (4, 8, and 12 h) in the spring, summer, and fall of one year. Tracer studies were conducted to evaluate flow and dispersion characteristics. The mean of nitrate removal efficiency ranged from 19% to 87% during the spring, 44% to 95% during the summer, and 21% to 68% during the fall. We found that barley straw was more effective in reducing nitrate (45% to 95%) compared to wood chips (19% to 54%). This study is the first testing of the effect of different biomass types and hydraulic residence times on bioreactor performance in the Canadian prairies (Alberta) and will allow agricultural producers and regulators to assess the suitability of these systems within the region. Keywords: Bioreactor, Denitrification, Water quality, Wood chips, Agricultural residues, Subsurface Drainage.
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Кулик, М. І., and І. І. Рожко. "Урожайні властивості та посівні якості насіння проса прутоподібного залежно від умов вирощування." Вісник Полтавської державної аграрної академії, no. 2 (June 27, 2018): 78–84. http://dx.doi.org/10.31210/visnyk2018.02.12.
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У статті обґрунтовано необхідність вивчення проса прутоподібного (світчграсу) як енергетичної культури, сировину якої доцільно використовувати для виробництва різних біопалив: рідких, твердих та газоподібних. Матеріалом для дослідження були рослини та насіннєвий матеріал сорту проса прутоподібного іноземної селекції Кейв-ін-рок. Здійснено спробу визначити оптимальні умови (за гідротермічним коефіцієнтом і з урахуванням родючості ґрунтів) для отримання високого врожаю насіння в умовах України та шляхи підвищення його посівних кондицій. За результатами трьохрічних досліджень встановлено вплив погодних умов веґетаційного періоду на продуктивність насіння проса прутоподібного. Експериментальним шляхом визначено лімітуючі фактори та шляхи їх нівелювання для забезпечення гарантованого отримання якісного насіннєвого матеріалу в умовах Лісостепу. Аналіз результатів досліджень дав змогу встановити вплив біометричних (кількісних) показників генеративної частини рослин (довжини та кількості волотей на рослинах, маси 1000 насінин) на насіннєву продуктивність, що обумовлюють і загальний урожай насіння. Визначено вплив крупності насіннєвого матеріалу та терміну зберігання його на лабораторну схожість насіння у взаємозв’язку з особливостями його формування на материнських рослинах за різних умов вирощування.
Necessity of studying switchgrass as an energy crop, raw material of which may be used for producing different types of biofuel such as liquid one, solid and gaseous ones has been substantiated in the article. The foreign experience of obtaining switchgrass seed of high quality has been investigated on the basis of scientific publications. We have established the limiting factors affecting seed yield, sowing characteristics, germination conditions, growth and development of plants in the early periods of vegetation. The attempt of determining optimal conditions (by hydrothermal coefficient and soil fertility) for providing high seed yield in Ukraine as well as ways of increasing seed characteristics has been made.
Many years’ experiments were conducted in the central part of Forest-Steppe of Ukraine on two types of soils: high-productive soil with humus content of more than 4 % and nutrient lean soil with humus content of less than 2 %. Research material was plants and seed of Cave-in-Rock switchgrass variety of foreign selection.
The methods of testing, field and laboratory experiments, scientific recommendations were applied in the experiment. The experimental results were processed by the dispersion analysis and correlative-regression analysis with application of the computer program Statistics.
After three years of investigation, influence of the vegetation period weather conditions on switchgrass seed productivity has been established. The limiting factors and the ways of decreasing their effect in order to provide guaranteed getting of high quality seed material in the conditions of Forest-Steppe of Ukraine have been defined by the experiments. At the same time the effect of soil conditions on the crop seed productivity has been proved. The analysis of the research findings enabled to show influence of biometric (quantitative) characteristics of the generative plant part (length and number of panicles per the plant, mass of 1000 seeds) on seed productivity that affect total seed yield. Besides, influence of seed material size and storage period on laboratory seed germination in the interconnection with seed formation peculiarities on maternal plants in different cultivation conditions has been determined.
The yield of switchgrass seeds depends on weather factors and soil fertility. Also we defined influence of quantitative characteristics in the generative plant part – length and number of panicles per the plant, mass of 1000 seeds on seed yield. Laboratory germination of seeds depends on the storage size and the mass of 1000 seeds.
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Ladak, Sameer, Sheri Molnar, and Samantha Palmer. "Multi-method site characterization to verify the hard rock (Site Class A) assumption at 25 seismograph stations across Eastern Canada." Earthquake Spectra 37, no. 1_suppl (April 9, 2021): 1487–515. http://dx.doi.org/10.1177/87552930211001076.
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Site characterization is a crucial component in assessing seismic hazard, typically involving in situ shear-wave velocity ( VS) depth profiling, and measurement of site amplification including site period. Noninvasive methods are ideal for soil sites and become challenging in terms of field logistics and interpretation in more complex geologic settings including rock sites. Multiple noninvasive active- and passive-seismic techniques are applied at 25 seismograph stations across Eastern Canada. It is typically assumed that these stations are installed on hard rock. We investigate which site characterization methods are suitable at rock sites as well as confirm the hard rock assumption by providing VS profiles. Active-source compression-wave refraction and surface wave array techniques consistently provide velocity measurements at rock sites; passive-source array testing is less consistent but it is our most suitable method in constraining the rock VS. Bayesian inversion of Rayleigh wave dispersion curves provides quantitative uncertainty in the rock VS. We succeed in estimating rock VS at 16 stations, with constrained rock VS estimates at 7 stations that are consistent with previous estimates for Precambrian and Paleozoic rock types. The National Building Code of Canada uses solely the time-averaged shear-wave velocity of the upper 30 m ( VS30) to classify rock sites. We determine a mean VS30 of ∼ 1600 m/s for 16 Eastern Canada stations; the hard rock assumption is correct (>1500 m/s) but not as hard as often assumed (∼2000 m/s). Mean variability in VS30 is ∼400 m/s and can lead to softer rock classifications, in particular, for Paleozoic rock types with lower average rock VS near the hard/soft rock boundary. Microtremor and earthquake horizontal-to-vertical spectral ratios are obtained and provide site period classifications as an alternative to VS30.
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Zhang, Qingzhu, Guobiao Zuo, Qinghui Lai, Jin Tong, and Zhihong Zhang. "EDEM Investigation and Experimental Evaluation of Abrasive Wear Resistance Performance of Bionic Micro-Thorn and Convex Hull Geometrically Coupled Structured Surface." Applied Sciences 11, no. 14 (July 20, 2021): 6655. http://dx.doi.org/10.3390/app11146655.
Full textAbstract:
Procambarus clarkii was found to have excellent anti-wear performance against abrasive materials. To improve the wear resistance performance of the soil-engaging component of agricultural machinery, in this study, the micro-thorn and convex hull coupled geometrical structured surfaces inspired from the cephalothorax exoskeleton of the Procambarus clarkii was selected as the bionic prototype. By adopting bionic engineering techniques, three types of novel geometrical structured surfaces were proposed, which were bionic single, double and triple micro-thorn coupled convex hull surfaces (Bionic Type 2, 3 and 4, respectively). The anti-abrasive wear properties of these proposed geometrical surfaces were compared with a conventional bionic convex hull structured surface (Bionic Type 1) and a surface without any structures (smooth). Abrasive wear tests were conducted by using a rotational abrasive wear testing system. The accumulative test time was 80 h and the total wear distance was 6.09 × 105 m. By adopting the EDEM software (discrete element modeling), the Archard Wear model was selected to simulate the wear behavior of five different surfaces. In addition, the wear mechanisms of different surfaces were investigated. The results showed that the smooth surface suffered the most severe abrasive were, the abrasion loss reached 194.1 mg. The anti-abrasive properties of bionic geometric structured non-smooth surfaces were greatly improved; the reduction in terms of abrasion losses ranged between 20.4% and 94.1%, as compared with the smooth surface. The wear resistance property of micro-thorn and convex hull coupled structured surfaces were greatly improved as compared with convex hull and smooth surface. Bionic Type 3 was found to have the best anti-abrasive wear property: the abrasion loss was 11.5 mg. The wear morphology was observed by a scanning electron microscope. Smooth surface was characterized with wide, large size of grinding debris, while the bionic non-smooth surface featured narrow and small size abrasive dust. The results obtained from EDEM simulation agreed well with those of the aforementioned real scenario tests. It was revealed that the wear areas of the micro-thorn and convex hull coupled structured surface were mainly concentrated on the edge of convex hull and micro-thorn that faced the coming direction of particle flow. The geometric structure of the convex hull had beneficial effects on changing the movement behavior of particles, which means the stream of particle flow could be altered from a sliding to rolling state. Consequently, the ploughing and cutting phenomena of particles that act on the surfaces were greatly mitigated. Moreover, after being coupled with micro-thorns, the anti-abrasive wear preparty of the bionic convex hull geometrical structured surface was further improved. The rebound angle of particle flow that contacted the bionic micro-thorn coupled convex hull structured surface was greater than that of the conventional convex hull surface. Therefore, the dispersion effect of particle flow was further enhanced, since the movement behavior of the subsequent impact particle flow was altered. As a result, the wear of the bionic non-smooth surface was further reduced. This biconically inspired novel micro-thorn and convex hull coupled structured surface could provide theatrical and technical references to enhance the wear resistance performance of the soil-engaging component of agricultural machinery and mitigate the problem of abrasive wear failure.
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Gucunski, N., and V. Krstic. "Backcalculation of Pavement Profiles from Spectral-Analysis-of-Surface-Waves Test by Neural Networks Using Individual Receiver Spacing Approach." Transportation Research Record: Journal of the Transportation Research Board 1526, no. 1 (January 1996): 6–13. http://dx.doi.org/10.1177/0361198196152600102.
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The Spectral-Analysis-of-Surface-Waves (SASW) method is a seismic technique for in situ evaluation of elastic moduli and layer thicknesses for layered systems, such as pavements and soils. The objective of the SASW test is to obtain the experimental dispersion curve and, through an inversion procedure, obtain the profile of an elastic moduli of the layered system. The inversion process in practice uses an average of dispersion curves for different receiver spacings. Results of theoretical studies indicate that differences in dispersion curves for various spacings are a result of interference of a number of body and surface waves. The development and application of neural networks to perform the inversion procedure for SASW testing of asphalt concrete (AC) pavements is presented. The most important feature of the developed network is that training of the network was done by the dispersion curves for individual receiver spacings. The training set consists of dispersion curves for seven receiver spacings and 78 dimensionless frequencies, while output is presented by elastic moduli and layer thicknesses of a four-course AC pavement. The dispersion curves used to train the neural networks are synthetic dispersion curves developed from numerical simulations of the SASW test. The obtained neural network model is compared to the previously developed model for backcalculation of moduli from the SASW test based on the averaged dispersion curve. Although both approaches can accurately define profiles, each has some advantages in evaluation of the thickness of the subbase.
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Mahvelati, Siavash, Joseph Thomas Coe, and Philip Asabere. "Field Investigation on the Effects of Base Plate Material on Experimental Surface Wave Data with MASW." Journal of Environmental and Engineering Geophysics 25, no. 2 (June 2020): 255–74. http://dx.doi.org/10.2113/jeeg18-056.
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Source characteristics significantly affect the signals generated during seismic testing. Proper source selection plays a major role in data quality and can potentially improve investigation outcomes. This is particularly true for surface wave testing where the goal is to establish the frequency variation of phase velocity. Little research has compared the input energy caused by different base plates when impact sources are used. Consequently, data were collected using the Multichannel Analysis of Surface Waves (MASW) method with three base plate configurations (aluminum, aluminum over a rubber mat, and polyethylene) and two different sledgehammers. The variations in signal frequency content and amplitude spectra, energy, and dispersion images were systematically analyzed. There were appreciable differences in the energy introduced by different base plate configurations. Both the aluminum/rubber and the polyethylene base plates led to power spectra increases relative to the aluminum base plate. Subsequently, the aluminum/rubber and polyethylene base plates typically transferred more energy into the subsurface. This was not necessarily the case when the base plates were used on soft surficial soils. The variations in predominant frequency content were also less substantial, though the aluminum/rubber and polyethylene base plates developed slightly lower-frequency content at the expense of higher-frequency components in the dispersion curves. Despite the noticeable differences in energy transfer and frequency content, the base plate materials did not appreciable alter interpretation of the dispersion behavior at the sites given the uncertainty present in the dispersion images. This highlights that the selection of MASW base plate materials can be correspondingly driven by practical considerations such as noise, portability, and durability. Consequently, base plate materials with viscoelastic characteristics are a promising alternative to conventional metallic plates for coupling impact sources in surface wave testing, though care should be exercised when employing them at sites with soft ground conditions.
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Alshehry, Azzh Saad, Humaira Yasmin, Fazal Ghani, Rasool Shah, and Kamsing Nonlaopon. "Comparative Analysis of Advection–Dispersion Equations with Atangana–Baleanu Fractional Derivative." Symmetry 15, no. 4 (March 29, 2023): 819. http://dx.doi.org/10.3390/sym15040819.
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In this study, we solve the fractional advection–dispersion equation (FADE) by applying the Laplace transform decomposition method (LTDM) and the variational iteration transform method (VITM). The Atangana–Baleanu (AB) sense is used to describe the fractional derivative. This equation is utilized to determine solute transport in groundwater and soils. The FADE is converted into a system of non-linear algebraic equations whose solution leads to the approximate solution for this equation using the techniques presented. The proposed approximate method’s convergence is examined. The suggested method’s applicability is demonstrated by testing it on several illustrative examples. The series solutions to the specified issues are obtained, and they contain components that converge more quickly to the precise solutions. The actual and estimated results are demonstrated in graphs and tables to be quite similar, demonstrating the usefulness of the proposed strategy. The innovation of the current work is in the application of an effective method that requires less calculation and achieves a greater level of accuracy. Furthermore, the proposed approaches may be implemented to prove their utility in tackling fractional-order problems in science and engineering.
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Molnar, Sheri, John Onwuemeka, and Sujan Raj Adhikari. "Rapid Post-Earthquake Microtremor Measurements for Site Amplification and Shear Wave Velocity Profiling in Kathmandu, Nepal." Earthquake Spectra 33, no. 1_suppl (December 2017): 55–72. http://dx.doi.org/10.1193/121916eqs245m.
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This paper presents application of microtremor (ambient vibration) and surface wave field techniques for post-earthquake geotechnical reconnaissance purposes in Kathmandu, Nepal. Horizontal-to-vertical spectral ratios (HVSR) are computed from microtremor recordings at 16 individual measurement locations to obtain an estimate of fundamental frequency (site period) of the subsurface soils. A combination of active- and passive-source surface wave array testing was accomplished at five key sites including Kathmandu's Durbar Square and Airport. Joint inversion of each site's higher frequency dispersion and lower frequency HVSR data sets provides an estimate of subsurface material stiffness [i.e., shear wave velocity ( V S) depth profiles]. Direct comparison of our V S profiling at Kathmandu Durbar Square and that accomplished by downhole V S and/or standard penetration testing (SPT) profiling yield similar results. Classification of the five sites based on average V S, site period, and/or basin depth is presented. There is little differentiation in these site classification designations amongst the five sites, which does not capture significant differences in observed earthquake damage.
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Roesch, Michael, Carolin Roesch, and Daniel J. Cziczo. "Dry particle generation with a 3-D printed fluidized bed generator." Atmospheric Measurement Techniques 10, no. 6 (June 2, 2017): 1999–2007. http://dx.doi.org/10.5194/amt-10-1999-2017.
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Abstract. Here we describe the design and testing of PRIZE (PRinted fluidIZed bed gEnerator), a compact fluidized bed aerosol generator manufactured using stereolithography (SLA) printing. Dispersing small quantities of powdered materials – due to either rarity or expense – is challenging due to a lack of small, low-cost dry aerosol generators. With this as motivation, we designed and built a generator that uses a mineral dust or other dry powder sample mixed with bronze beads that sit atop a porous screen. A particle-free airflow is introduced, dispersing the sample as airborne particles. Total particle number concentrations and size distributions were measured during different stages of the assembling process to show that the SLA 3-D printed generator did not generate particles until the mineral dust sample was introduced. Time-series measurements with Arizona Test Dust (ATD) showed stable total particle number concentrations of 10–150 cm−3, depending on the sample mass, from the sub- to super-micrometer size range. Additional tests with collected soil dust samples are also presented. PRIZE is simple to assemble, easy to clean, inexpensive and deployable for laboratory and field studies that require dry particle generation.
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Leclaire, P., J. Aguirre-Puente, and F. Cohen-Ténoudji. "Étude théorique et expérimentale de la propagation acoustique dans les milieux poreux soumis au gel." Canadian Journal of Earth Sciences 33, no. 11 (November 1, 1996): 1511–19. http://dx.doi.org/10.1139/e96-114.
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Seismic waves are of primary concern in research in the field of earth sciences. In this study, we are interested in the elastic wave propagation in frozen soils and rocks. Different theoretical approaches are presented, among which, a formulation based on Biot's theory. The main disadvantage of this model is that more parameters are involved than in the other models and that most of them are semi-empirical. On the other hand, this model describes in a more general and unifying manner the wave propagation in the different types of media encountered. In other respects, one of the interests of this model is its predictive capacity. Indeed, some significant results are predicted such as the presence of attenuation peaks due to the variation in permeability as a function of temperature, as well as the possible propagation of two longitudinal and two transverse waves. The experimental testing has been performed in artificial or real soils. The laboratory results obtained on consolidated samples, such as sintered bronze or overconsolidated clay, or on nonconsolidated samples, such as glass powder or silt, are presented. The experimental results on velocity, attenuation, and dispersion of waves, and on the existence of several longitudinal and transverse waves confirm the theoretical predictions.
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Kamaruddin, Zatil Hafila, Ridhwan Jumaidin, Rushdan Ahmad Ilyas, Mohd Zulkefli Selamat, Roziela Hanim Alamjuri, and Fahmi Asyadi Md Yusof. "Biocomposite of Cassava Starch-Cymbopogan Citratus Fibre: Mechanical, Thermal and Biodegradation Properties." Polymers 14, no. 3 (January 27, 2022): 514. http://dx.doi.org/10.3390/polym14030514.
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Increasing environmental awareness and concern have shifted the focus of research and development towards biodegradable materials development. In the current study, Cymbopogan citratus fibre (CCF) were incorporated into thermoplastic cassava starch (TPCS) with various content of CCF (10, 20, 30, 40, 50, 60 wt.%) via compression moulding. The determination of fundamental characteristics of TPCS/CCF biopolymer composites was conducted to assess their potential as biodegradable reinforcements. Characterization of the samples was conducted via Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM), as well as mechanical, moisture absorption, and soil burial testings. The findings showed that the improved tensile and flexural features of the TPCS composites with CCF incorporation, with 50 wt.% CCF content yielded the maximum modulus and strength. The thermal properties of the biocomposite demonstrated that CCF addition improved the material’s thermal stability, as shown by a higher-onset decomposition temperature and ash content. Meanwhile, the CCF incorporation into TPCS slowed down the biodegradation of the composites. In term of morphological, homogeneous fibres and matrix dispersion with excellent adhesion was observed in morphological analyses using scanning electron microscopy (SEM), which is crucial for the enhancement of the mechanical performance of biocomposites.
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He, H., and K. Senetakis. "The effect of grain size on Gmax of a demolished structural concrete: A study through energy dispersive spectroscopy analysis and dynamic element testing." Soil Dynamics and Earthquake Engineering 89 (October 2016): 208–18. http://dx.doi.org/10.1016/j.soildyn.2016.08.011.
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Peter, Antai Sylvester, Agbor Reagan Bessong, Iwatt Godwin Dickson, and Ubi Stanley Emmanuel. "Heavy Metal Tolerance profile among Bacterial species Isolated from Hydrocarbon polluted sites and their mobile genetic elements." Journal of Experimental Biology and Agricultural Sciences 11, no. 1 (February 28, 2023): 158–70. http://dx.doi.org/10.18006/2023.11(1).158.170.
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This present study evaluated the plasmid incidence in bacteria and their genetic elements in heavy metals tolerant-antibiotics resistant microbes isolated from petroleum hydrocarbon polluted sites. The plasmid isolation was carried out using the fermentas Genejet plasmid miniprep kit (Thermofisher Scientific Inc, USA). Screening for class 1, 2, and 3 integrons, incompatibility group P testing, plasmid replicon typing, plasmid restriction analysis, and other analysis was performed using standard laboratory procedures. Plasmid incidences were higher among multiple heavy metal-tolerant bacterial species from hydrocarbon-polluted sites than those from the pristine site. Further, Class 1 integron incidence was significantly higher among the integrons in heavy metal tolerant bacterial isolates isolated from the polluted ecosystems than those from pristine ecosystems. Plasmid replicon type of bacteria with multiple heavy metal tolerance and antibiotics resistance indexes revealed that IncN plasmid replicon type carrying class 1 integron. This encodes resistance to sulphamethazole/trimethoprim, ampicillin, and tolerance to Cd, Ni, and Cu in Klebsiella pneumoniae isolate from petroleum-polluted soil. This is the first report of IncN plasmid in environmental bacteria in Nigeria, particularly from petroleum polluted environment. The conjugation experiment confirmed the possible transferability of antibiotic resistance determinants among isolates in polluted ecosystems. From the results of this study, it can be concluded that petroleum hydrocarbon pollution vis-a-vis heavy metal selective pressure with the abundance of mobile genetic elements amongst isolates from polluted ecosystems could contribute to the dispersing of antibiotic resistance genes, thus posing a serious public health concern.
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Verma, Shailaja, and Kamlesh Kumar Bhakuni. "Systematic Study of Pteridophytes in Relation to Edaphic Factors from the Ghat Region of Pithoragarh, A Part of The Proposed Pancheshwar Dam in Uttarakhand." Journal of Mountain Research 17, no. 2 (2022). http://dx.doi.org/10.51220/jmr.v17i2.26.
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Pteridophytes are among the earliest terrestrial vascular cryptogams that instead of seeds, proliferate by the dispersion of their spores. Study of systematics includes classification, taxonomy and nomenclature. The Pancheshwar hydropower dam is being built on the Mahakali River at Pancheshwar near the confluence of the Mahakali and the Saryu River, which was the sampling site. To determine the diversity, soil nature, and established relationships between them were the main objectives. The classification and identification of the flora were done by the available literature while soil samples were analyzed in the District Agriculture Department Soil Testing Laboratory and statistical analysis by different softwares. At the species diversity point, there were seven families, 11 genera, and 19 species of pteridophytes recorded in the study area. The frequency, density, abundance, and distribution of each species were calculated, revealing significant variation. Various diversity indexes like dominance (D), Simpson index (1-D), Shannon index (H), evenness (e^H/S), and Margalef species richness were calculated, all of these indicated good diversity in the area. The physical properties of soil (water holding capacity, sand, slit, and clay) and chemical properties (nitrogen, phosphorus, potassium, organic carbon content, and pH) when statistically analysed for regression, correlation and ANOVA, showed that these factors were suitable for growth of plants.
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Jackson, Ian, Ulrich H. Faul, John D. Fitz Gerald, and Ben H. Tan. "Shear wave attenuation and dispersion in melt-bearing olivine polycrystals: 1. Specimen fabrication and mechanical testing." Journal of Geophysical Research: Solid Earth 109, B6 (June 2004). http://dx.doi.org/10.1029/2003jb002406.
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Uriz, Patxi, and Troy A. Morgan. "Risk Assessment of Emergency Diesel Generator Subject to Design-Basis Earthquake Shaking." ASCE-ASME J Risk and Uncert in Engrg Sys Part B Mech Engrg 2, no. 1 (November 20, 2015). http://dx.doi.org/10.1115/1.4031843.
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A monitoring system intended to track vibrations associated with the operation of an emergency diesel generator (EDG) at a nuclear power plant was originally installed to trip generators during potential out-of-balance shaking. Years after original installation, plant engineers raised questions as to whether the monitoring system would have functioned properly in the event of excessive vibrations associated with earthquake ground shaking. As part of the plant’s examination of this issue, analytical models were developed for three vibration transducers via experimental characterization. A suite of ground motion records was selected and scaled such that their mean and dispersion were representative of the design-basis event (DBE) level of intensity at the plant site. The scaled suite of ground motions was used as an input for a three-dimensional (3D) analytical model representing the structure and soil-foundation interface, where the EDGs were installed. The voltage signal from the analytical transducer model provided input to the physical vibration alarm monitor. This monitor filters the vibration transducer signal and generates an output to a time-delay relay that will trip the EDG if the output from the vibration monitor is not reset within 5 s. The analysis and testing completed and described in this paper concluded that a DBE would not have caused the vibration monitoring circuit to spuriously trip the EDGs.