Compaction Conditions Research Articles

Educating parents to enhance children’s reasoning abilities: A focus on questioning style

This study investigated whether parents can be educated to alter parent-child interactions and whether this can improve children's reasoning abilities. Parents of four- to eight-year-olds were randomly assigned to a compact psycho-educational program (N = 34) or control condition (N = 36). Parental questioning style was observed during problem-solving interactions at home and children's scientific and social reasoning were assessed using performance-based tasks. Parents in the educational condition asked significantly more open-ended, observational and explanatory questions at post-test than controls did. Asking relatively more open-ended questions at post-test was associated with improved aspects of scientific reasoning in their children. Asking more observational or explanatory questions was not associated with improved reasoning abilities. Educating parents to adaptively modify their parent-child interactions can positively influence their questioning style, which in turn may benefit their child's reasoning abilities.

Soil-Water Charateristics of Tropical Clay Soil under High and Low Suction Conditions

Tropical clay soil was compacted at different moisture conditions (dry, wet and optimum) and compactive efforts (Reduced proctor, Standard proctor, West African standard and Modified proctor). Experimental Soil-Water Characteristics (SWC) of the soil was derived using the pressure plate extractor equipment and SWC Curves (SWCC) plotted as gravimetric water content versus logarithm of matric suction. The Air Entry Values (A.E.V) obtained from experimental work ranged from 21 kPa to 59 kPa and compared favourably well with those estimated from predictive models with values of 23 kPa to 52 kPa. Specimens compacted with greater compactive effort (Modified proctor) and at optimum moisture content produced the largest air entry value of 59 kPa and reduced air voids. Changes observed in the shape of the SWCC were consistent with changes in pore size which occurred by varying compaction conditions. The shape of the soil-water characteristics curve was found to depend on the soil structure, compactive water content and compactive effort and not solely on the percentage of fine particles.

Об интегральных операторах с периодическими ядрами в пространствах суммируемых функций

We consider integral operators with periodic kernels acting from Lp(ℝn) to Lq(ℝn). We obtain sufficient conditions for boundedness of that operators. Moreover we obtain compactness conditions for the product of the integral operator with periodic kernel and the operator of multiplication by an essentially bounded function.

Compactness conditions for a family of measures of Hilbert-valued continuous semi-martingales

Compactness conditions for a family of measures of Hilbert-valued continuous semi-martingales

New iterative schemes for solving variational inequality and fixed points problems involving demicontractive and quasi-nonexpansive mappings in Banach spaces

Abstract In this paper, we suggest and analyze a new iterative method for finding a common element of the set of fixed points of a quasi-nonexpansive mapping and the set of fixed points of a demicontractive mapping which is the unique solution of some variational inequality problems involving accretive operators in a Banach space. We prove the strong convergence of the proposed iterative scheme without imposing any compactness condition on the mapping or the space. Finally, applications of our theorems to some constrained convex minimization problems are given.

Hard alloy production by SHS compaction in an open die

The paper investigates the possibility of carrying out SHS for the Ti (81.5 wt.%) + B (18.5 wt.%) composition in the air followed by pressing combustion products in an open steel die with walls limiting their radial flow under tough heat dissipation conditions without the use of an intermediate loose medium of the heat insulator. Modes of reaction powder mixture preparation for synthesis were optimized. Such process characteristics as bulk density, compaction, elastic aftereffect were determined for initial powders and reaction mixtures, and the strength of compactions was estimated. It is shown that there is a relationship between the strength of charge compacts, combustion rate and changes in their volume after combustion in the air under intensive gas liberation during combustion. The optimal charge compact density was found equal to 0.75 corresponding to the maximum combustion rate without charge emissions with a minimum change in volume. As a result of the optimization, the possibility of effective and safe conduct synthesis process without the use of an intermediate loose medium of the heat insulator is shown. Hard-alloy plates with a diameter of 60 mm and a thickness of 11 mm were obtained in the open steel die under SHS compaction conditions. The structure of the resulting hard alloy is unique with a porosity of less than 0.5 %. It consists of titanium diboride (~60 wt.%) and titanium-based binder phase (~ 40 wt.%). Such a structure obtained as a result of accelerated cooling can be defined as nonequilibrium, since the main phase for the studied composition should be titanium monoboride (TiB) in accordance with the Ti–B state diagram. The microhardness of the fabricated hard alloy is HV = 18000 MPa.

The conditions of bulk clay soil compaction

Testing of bulk clay soil with static cyclic loading was carried out in order to determine the required number of loading-unloading cycles to achieve a standard soil compaction at a given humidity, as well as to assess the content of bound water. Several samples of different moisture content of the dust loam in the compression device were tested by applying pressure in one stage and unloading with the measurement of deformation of the compaction and expansion of the soil sample. The number of cycles of the test soil samples was limited to the stabilization of the values of the coefficient of the elastic deformation work, the same for all samples of different moisture. Here proposed method of selection of the elastically deformable water and water involved in the inelastic deformation as a phase state of aggregation of the soil. Calculations of the volume content of mineral particles in the soil, elastically deformed water and water involved in inelastic deformation of the sample are made through the coefficient of elastic deformation. It is found that with increasing the density of the soil volume content of mineral particles and the elastically deformable water increases and correlates with the dry density of the soil and the volumetric water content involved in the inelastic deformation of the sample virtually unchanged.

Parameters of strength and deformability of ash and slag mixture of Ekibastuz coals

The article assesses the possibility of using ash and slag mixture for the construction of a road bed. To this end, the traditional and modern methods of calculation of road surfaces are analyzed, which allow establishing the parameters of strength and deformability that require experimental determination. Experimental determination of strength and deformability parameters is performed by laboratory tests. For the implementation of tests the authors make samples of ash and slag mixture of different density. During the experiments, the metal stamp is pressed into the model and the experimental dependences of the sediment on the pressure are determined. This makes it possible to calculate the California Bearing Ratio, the deformation modulus, and to establish the pressures at which the mixture of ash and slag operates under compaction or shear conditions. Mathematical models are developed to calculate the parameters of strength and deformability from the value of pressure.

Leray–Schauder Alternatives for Maps Satisfying Countable Compactness Conditions

Abstract In this paper we present Leray–Schauder alternatives for a general class of Mönch type maps.

Fate and transport processes of nitrogen in biosorption activated media for stormwater treatment at varying field conditions of a roadside linear ditch

Roadside drainage networks can result in changes to watershed hydrology and water quality. By acting as hydrological links between urban development, agricultural fields, and natural streams, roadside ditches may be modified by filling in some green sorption media to control nitrogen pollution. Biosorption activated media (BAM), one of the green sorption media, are composed of sand, tire crumb, and clay, which can remove nitrogen from stormwater and groundwater through integrated hydrological, chemophysical, and microbial processes. The fate and transport processes of interest are complicated by internal microbial processes including ammonification, nitrification, denitrification, and dissimilatory nitrate reduction to ammonium (DNRA), each of which is controlled by different microbial species in addition to some varying field conditions. In this study, BAM was tested in a suite of columns to address site-specific physical, chemical and biological concerns driven by in situ traffic compaction, carbon availability, and animal impact (such as gopher turtles, moles, and ants) all of which impose different impacts on nitrogen fate and transport processes that may be signified by changing dissolved organic nitrogen species (DONs). The traffic compaction condition resulted in the most suitable hydraulic retention time in the hydrological process, which is beneficial for the assimilation of DONs in a long-term carbon rich environment due to biofilm expansion. Denitrifiers were the most predominant microbial population and the microbial species of DNRA were the second most predominant one in all three field conditions. However, the relationship of denitrifiers and DNRA in BAM can be shifted from commensalism to competition or even inhibition after carbon addition in microbial ecology.

Urban Improvement of Comprehensive Schools And Out of School Educational Establishments in Ukraine

Renewal of architectural planning in urban and rural areas can contribute to new educational institutions for population according to regulations and standards. The research was conducted to provide recommendations concerning improvement of educational establishments network in conditions of urban compaction, as well as territorial educational districts in urban and rural areas. The calculation method of general and out-of-school educational institutions network of different levels was improved. Various layouts of subject-oriented educational institutions were suggested, taking into account accessibility radius within territorial educational districts.

Equations Controlling Tensile and Compressive Strength Ratio of Sedimentary Soil–Cement Mixtures under Optimal Compaction Conditions

AbstractMethodologies for dosing fine/coarse-grained soils with cement using the porosity/cement ratio (η/Civ) have mainly focused on the nonoptimal compaction conditions to calculate the split ten...

On Expansive Mappings

When finding an original proof to a known result describing expansive mappings on compact metric spaces as surjective isometries, we reveal that relaxing the condition of compactness to total boundedness preserves the isometry property and nearly that of surjectivity. While a counterexample is found showing that the converse to the above descriptions do not hold, we are able to characterize boundedness in terms of specific expansions we call anticontractions.

Investigating the effects of low temperature and compaction on the quality of adult radio-sterilised Aedes albopictus (Diptera: Culicidae) males in view of their optimal transport to the pilot sterile release site in Mauritius

The Sterile Insect Technique (SIT) is currently being investigated against Aedes albopictus Skuse (Diptera: Culicidae) mosquitoes in Panchvati, a village in Mauritius. As an essential step before field releases, this study investigated the effect of temperature (2 h exposure at 5, 10, 15 or 25 °C) and compaction (2000 males per 1062 or 8553 cm3) on the fitness of radio-sterilised Ae. albopictus males with the aim of optimising their transport from the mosquito-production unit to the release site in Panchvati. Temperature and compaction had no significant effect on male survival during the first fifteen days. However, when survival was assessed over twenty-five days, males stored at 25 °C had significantly higher survival rates than males stored at lower temperatures (Kaplan-Meier: P < 0.05). Furthermore, males stored at 5 °C survived significantly longer than those stored at 10 °C or 15 °C (Kaplan-Meier: P < 0.05). Considering the fact that a weekly release of sterile males is planned in Panchvati, the long-term negative effect of low temperatures (5 to 15 °C) on male survival, may have limited relevance in the field. Male storage at 5 °C for 2 h in compacted conditions, were hence further investigated. Compaction significantly impacted male competitiveness, with a mean competitiveness index of 0.2 when sterile males were stored at 2000 males per 1062 cm3. Two thousand males per Bugdorm cage (27,000 cm3), was found to be the optimal density at which sterile Ae. albopictus males could be stored and transported by van to Panchvati, with minimal effects of the latter’s survival and competitiveness.

Investigation of rolling contact between metal and rubber-covered cylinders governing the paper compaction process

With the goal of partial or complete replacement of plastic components with paper-based products, 3D paper structures have seen a growing interest in industrial applications: from packaging to more complex daily life objects. However, the extensibility of paper has become a key issue within this context and is the main factor determining the formability of these products and determining the depth of the achievable shapes. The most effective way to increase paper’s stretch potential is by subjecting the moist paper web to a compaction process, which can be achieved through an extensible unit that is located in the drying section of a paper machine, where the network experiences in-plane compression in the machine direction (MD), under out-of-plane lateral constraints. The objective of this work is to clarify the mechanisms governing the compression process and to evaluate the influence of various parameters on the final material properties to optimize the industrial production of extensible paper. The system operation has been simulated realistically and shows that paper experiences a compressive state passing through the nip, with plastic strains in MD direction being of the same order of the applied speed difference, which was expected experimentally in optimal conditions of compaction. Starting from an initial reference case, a sensitivity study has been performed to identify and address the following factors that may affect the compression state: (a) friction coefficients; (b) indentation level; (c) speed difference; and (d) rubber properties. The analysis of the numerical results gives an insight into the mechanisms governing the compaction operations and allows a better comprehension of the features controlling the process outcome.

An Optimised Compaction Process for Zr-Fumarate (MOF-801)

We reported a systematic approach aimed at identifying the optimal conditions for compaction of MOF-801, a small-pore zirconium-based metal–organic framework (MOF) containing fumaric acid as the linker, that can be easily synthesised in aqueous medium. Pellets of the MOF were prepared by compressing the powder either in neat form or dry-mixed with binders (sucrose, polyvinylalcohol, polyvinylbutyral) under a range of pressures and for different times. The mechanical stability and durability of the pellets was tested by simple drop tests and shake tests, finding that addition of 5% of polyvinylbutyral was enough to produce highly resilient pellets that did not release significant amounts of powder upon cracking. The crystallinity, textural properties and CO2 adsorption performance of the MOF were successively assessed, observing the least change of the original properties in pellets compressed at 146 MPa for 15 s. Compaction at higher pressures impacted the performance more heavily, with no evident benefit from the mechanical point of view, whereas compression time did not have a relevant effect. The cyclic adsorption behaviour was tested, showing that the pellets retained as much as 90% of the CO2 working capacity, while displaying unaffected sorption kinetics, and 74% of the H2O working capacity.

Experimental comparative study on the performance of nano-SiO2 and microsilica in stabilization of clay

Nano- SiO2 and microsilica are two types of additives with the same elemental structure but different particle sizes that are introduced by the researchers for ground improvement. The major difference in the two additive materials is the difference in the specific surface area, which its effect has been evaluated in this study. For this purpose through experimental tests, the effects of each of two additives on the change in geotechnical parameters of clay are compared. The additive percentages of each of the two additives are limited to 6% and the samples have been tested after a 28-day curing time. Variations in the consistency limits, compaction conditions of the samples, as well as undrained shear strength of soil have been measured for each mixture. The results of the unconfined compression test demonstrated that the nano- SiO2 had a more prominent effect in doses lower than 2% on the unconfined compressive strength and modulus of elasticity of the soil. By increasing the amount of nanomaterial, the strength of the samples is closer to that obtained for stabilized specimens with microsilica. In samples containing nanosilica, the increase in strength in percentages of less than 1% of the nano-material had a higher rate, while microsilica followed a relatively stable trend. By adding additives, the maximum dry density dropped up to 5% and shown a higher optimum moisture content. The plasticity changes were somewhat different for both additives. By adding more than 2% of nano- SiO2 , an increase in the liquid limit and the plasticity index of soil were observed, while microsilica slightly reduced these parameters. The X-Ray Diffraction (XRD) showed that no significant chemical reaction was occurred in the soil by additives. Moreover, the examination of Field Emission Scanning Electron Microscopy (FESEM) demonstrated that both materials played a significant role in reducing porosity and creating particle integrity. However, the pattern of filling the pores and enclosing particles by the two materials were different. This difference was particularly influential in terms of water absorption by the sample.

The effects of compaction methods and mix parameters on the properties of roller compacted concrete mixtures

Despite the wide use of RCC, there is no specific compaction methodology developed to simulate the site conditions in the laboratory. Yet, there are few compaction methods that are generally used to produce RCC specimens in the laboratory environment. The most common methods are the vibrating table and the vibrating hammer found in ASTM, and the modified proctor and Superpave gyratory compactor (SGC), which are suggested to be standardized. However, it is not well known how these different compaction techniques can reflect the properties of RCC in situ. In this study, RCC mixtures which consist of two different cement dosages and two types of aggregate gradations were compacted by the four laboratory compaction methods mentioned above, to investigate the effect of laboratory compaction methodology on the physical properties and mechanical performance of RCC. The first three methods are the ones commonly used in the literature, while the fourth method (SGC) is thought to best represent the field compaction conditions with the kneading action. Moreover, regressions models were derived for each of the compressive and splitting tensile strengths based on the mix parameters. The statistical analysis showed that the compressive and splitting tensile strengths were highly affected by the compaction ratio, then by the cement content. The water content seemed to be dependent on the compaction ratio and had a small effect on the strengths. The ideal laboratory compaction methods in terms of strengths and compaction ratio within the acceptable Vebe consistency time were determined as the SGC first and the vibrating hammer second.

Nuclear magnetic resonance simulations of nano-scale cores and microscopic mechanisms of oil shale

The mineral composition and pore structure of organic shale are complex, and studies of the porosity, seepage characteristics, and pore structure by using nuclear magnetic resonance (NMR) can be of great significance for the identification and quantitative evaluation of shale oil reservoirs. In particular, pore-scale NMR numerical simulations and core NMR experimental analyses of organic shale can provide a theoretical basis for NMR log interpretations. An ideal digital core and actual shale digital core were constructed by simulating the deposition process and using computerized tomography (CT) scanning, respectively. Then, one- and two-dimensional NMR numerical simulations were carried out by random-walk method to study the NMR responses of cores under different compaction and water saturation conditions. The microscopic NMR numerical simulations showed that as the degree of compaction increased, the porosity of the cores decreased, amplitudes of the T2 distributions decreased significantly, and T2 distributions moved toward the direction of short relaxation. As the echo spacing decreased, the T2 distributions shifted to the left, smaller pores were measured, and NMR porosities of shale increased; these findings are consistent with those of the rock NMR experiments. In two-dimensional T2–D maps, the signal of the wetting fluid deviated from its free diffusion coefficient line, which was indicative of restricted diffusion in tight rock. The restricted diffusion effect of water was larger than that of oil. These microscopic numerical simulations provide a physical basis for interpreting NMR macroscopic responses, and the simulated NMR responses should be helpful for fluid typing in oil shale.

Texture Development of Clay‐Rich Sediments Across the Costa Rica Subduction Zone

AbstractDuring sedimentation, burial, and deformation at active continental margins, clay‐rich sediments develop crystallographic preferred orientations (textures) due to the progressive alignment of phyllosilicates. Such textures help to interpret sedimentation and compaction conditions as well as tectonic processes at convergent margins. At the Costa Rica Trench, subduction and plate boundary deformation between the downgoing oceanic Cocos Plate and the overriding Caribbean Plate was investigated during Integrated Ocean Drilling Program Expeditions 334 and 344 within the Costa Rica Seismogenesis Project. Samples of varying depths from the Cocos Plate, the frontal prism, and the slope of the Caribbean Plate were analyzed regarding their composition and texture. Composition is quite similar for all sample locations of the hemipelagic section across the trench as determined by X‐ray powder analysis. Texture analysis reveals that phyllosilicates in samples from the incoming plate show in general weaker textures than those from upper and middle slope of the overriding plate. Samples from the frontal accretionary prism, however, mostly correspond to the incoming plate fabric according to their oceanic origin. Texture intensity depends on the internal parameters grain size and shape, porosity, and composition as well as compaction and tectonics. In samples from the continental wedge and the frontal accretionary prism, we are able to distinguish tectonically undisturbed compacted sediments from core sections that suffered faulting and folding due to subduction‐related deformation. This helps to constrain a more detailed image of sedimentary compaction and localized as well as distributed deformation across the active continental margin offshore Costa Rica.