Experimental Study on the Mechanical Property of Loess Mixed with Bentonite-HDTMA

Malan loess in the middle and lower reaches of the Yellow River after mixed with different bentonite and HDTMA ratios was selected to carry out shear and consolidation tests for discussing the influence of bentonite-HDTMA on the mechanical property of loess lining material in landfills. Studies have shown that, after mixing 6% to 14% bentonite, the cohesive force of modified loess is significantly increased, the friction angle is reduced and remains stable, and the shear strength is improved. The compressibility of materials slightly decreases with the increase of bentonite ratio. The addition of 2%–4% HDTMA weakens the increment for the cohesive force caused by bentonite, but the friction angle is effectively recovered. The compressibility of materials increases with the increase of HDTMA ratio. As the dry density increases, the shear strength of the modified loess increases, and the compressibility coefficient decreases. The mechanical property of loess lining material can be optimized by adding 6%–14% bentonite. The incorporation of 2%–4% HDTMA does not have a significant negative impact on the optimization effect of bentonite. From the perspective of the mechanical property, it is recommended that the dry density of modified loess is 1.70 g/cm3, the bentonite ratio is 10%–14%, and the HDTMA ratio is 2%–4%.

3D Numerical Modelling of the Application of Cemented Paste Backfill on Displacements around Strip Excavations

This article presents laboratory and spatial numerical modeling of cemented paste backfill. The first part of the research concerned laboratory tests of a mixture of sand, water, and variable cement content (5%, 10%, and 15%). The density and curing time of the mixture were determined. Moreover, cylindrical samples with a diameter of 46 mm and a height of 92 mm were constructed, for which compressive and tensile strength were calculated after one, two, three, and four weeks. The second part of the research concerned 3D numerical modeling with the use of RS3 software. For the exploitation field with dimensions of 65 m × 65 m, a strip-mining method was designed. The main objective of the research was to determine the changes in displacements around the haulage room and transportation roadway located in the immediate vicinity of the exploitation field. For the first time in numerical modeling, a two-sided strip method was used for the four stages of mining the ore deposit where the post-mining space was filled with a cemented paste backfill. Based on this research, the compressibility coefficient was determined.

USING THE SeDeM-ODT METHOD FOR THE DEVELOPMENT OF GK-2 TABLETS DISPERSED IN THE ORAL CAVITY

Introduction. The SeDeM-ODT method is a relatively new method based on expert judgment and pie charts, which reflect 15 main parameters of the suitability of a dosage form for direct compression and dispersibility in the oral cavity.The purpose of the research presented in this article is to study the pharmaceutical substance (API) GK-2 (bis- (N-monosuccinyl-L-glutamyl-L-lysine)hexamethyleneamide) using the SeDeM-method, to determine the direction for the correction of technological properties using excipients and to develop using the presented methods of the composition of tablets GK-2, dispersible in the oral cavity.Materials and methods. Preparation of tablets – manual hydraulic press PRG-50; method for determining flowability (GPM.1.4.2.0016.15, GP XIV, volume 2) – bulk density analyzer (ERWEKA SVM 221), GTB flowability tester (ERWEKA, Germany); crushing strength of tablets (GPM.1.4.1.0011.15, GP XIV, volume 2) – strength analyzer TBF 1000 CopleyScientific® (Great Britain); method for determining disintegration (GPM.1.4.2.0013.15, GP XIV edition, volume 2) – PTZ-S disintegration tester (Pharma Test, Germany); weight loss on drying (GPM.1.2.1.0010.15, GP XIV edition, volume 1) – moisture analyzer Sartorius MA-35 (Sartorius AG, Germany); determination of fractional composition – a vibrating sieve with pore sizes: 850, 600, 425, 300 and 250 microns, is used to determine the particle size distribution; tablet abrasion tester (GPM.1.4.2.0004.15, GP XIV edition, volume 2) – tablet abrasion tester PTF 30 ERA (Pharma Test, Germany); Optical microscopy (GPM.1.2.1.0009.15, GP XIV edition, volume I) – microscope Nicon, Eclipse E 200; digital camera Nicon Ds-Ri2. The data were processed using the SeDeM and SeDeM-ODT methods.Results. Model formulations have been developed containing various types of co-process fillers and a sliding excipient, which have been studied using the main pharmaceutical-technological methods and optical microscopy. Based on the data obtained, SeDeM-ODT diagrams were constructed, in which the parameters were converted into “radii”, reflecting the degree of acceptability for each technological characteristic. In addition, the following factors were calculated from the pie charts: volumetric parameter, compressibility coefficient, flowability parameter, stability coefficient, dosage coefficient, dispersibility coefficient, as well as the index of good pressing, the parametric index and the parametric index of the profile.Conclusion. As a result of the data obtained, the most optimal composition was selected that was acceptable for all the factors under consideration and had the highest values of the parametric index.

Thermoelastohydrodynamic Characteristics of Low-Temperature Helium Gas T-Groove Face Seals

Thermoelastohydrodynamic lubrication behaviors of helium gas T-groove face seals are numerically simulated under conditions of low temperature and high pressure, with the consideration of real-gas properties including compressibility coefficient, viscosity, and heat capacity. It is found that helium gas T-groove face seal presents a sharp divergent deformation at low temperature and high pressure, which makes the opening performance weaken and the leakage rate increase. This result is obviously different from the case of high-temperature gas face seals. As the sealing temperature drops from 300 K to 150 K, the leakage rate increases about 17% and the opening force decreases about 15%. Moreover, with the growth of rotational speed, both the outlet film pressure and the sealing performance present a non-monotonic trend. Specifically, while the rotating speed of moving ring raises from 3000 to 30,000 r·min−1, the leakage rate changes more than 30%, and the opening force is reduced about 10%.

Using TeX Markup Language for 3D and 2D Geological Plotting

The paper presents technical application of TeX high-level, descriptive markup language for processing geological dataset from soil laboratory. Geotechnical measurements included equivalent soil cohesion, absolute and absolute deformation index, soil compressibility coefficient by time of immersion depth, exposure time to compressive strength to samples and physical and mechanical properties (humidity, density). Dataset was received from laboratory based experimental tests of the physical and mechanical properties of soils. Data were converted to csv table and processed by LaTeX. Methodology is based on LaTeX packages: {tikz}, {tikz-3dplot}, {tikzpicture}, {pgfplot}, {filecontetns}, {spy} for 3D plotting showing correlation in variables and descriptive statistical analysis based on the data array processing. Results demonstrated LaTeX scripts and graphics: 2D and 3D scatterplots, ternaries, bar charts, boxplots, zooming techniques detailing fragment of the plot, flowchart. Research novelty consists in technical approach of TeX language application for geo- logical data processing and graphical visualization. Engineering graphics by TeX was demonstrated with screenshots of the codes used for plotting.

Technique and results of experimental determination of the compressibility factor of the natural gas

The actual problem of the possibility of using the equations of state for the gas phase of natural gas at temperatures below 250 K is considered. To solve it, the compressibility coefficients of natural gas obtained experimentally with high accuracy are required. The technique was developed and experimental study was carried out of compressibility factor aiming expanding temperature range of the state equations GERG-2004 and AGA8-DC92. The proposed technique is based on the fact that to assess the applicability of the equation of state, it is sufficient to obtain the relative value of the compressibility coefficient and not to determine its absolute value. The technique does not require complex equipment and provides high accuracy. The technique was tested on nitrogen, argon, air and methane. Uncertainty of determination of the compressibility factor is not greater than 0.1 %. For two different compositions of natural gas, obtained experimental data were demonstrated that the equations of state GERG-2004 and AGA8-92DC provide uncertainty of the calculation of the compressibility coefficient within 0.1 % in the temperature range from 220 K to 250 K and pressure below 5 MPa.

Determination of stress-strain properties of thawing soils in oedometer

Article presents relation of thawing coefficient (Ath) and compressibility coefficient during thawing (m) to the sampling depth and physical state of frozen soils in loams, typical for the Arctic region of the European part of Russia. Conclusions are drawn that help to predict thawing deformation of the tested soils according to their physical characteristics.

Comparative study of the effect of rice husk-based powders used as physical conditioners on sludge dewatering

The effects of rice husk flour (RHF), rice husk biochar (RHB), and rice husk-sludge cake biochar (RH-SCB, expresses sludge cake biochar deriving from a sludge that has been previously conditioned with rice husk) used as physical conditioners on sludge dewaterability were compared. The effects of characteristics of physical conditioners on sludge compressibility and zeta potential were analyzed. The optimal rice husk-based powder was RH-SCB, which presented the highest net sludge solid yield (YN, expresses the dry mass flow by filtration) at 20.39 kg/(m2 h) for 70% dry sludge (DS). Characterization analysis indicates that the hardness and surface Fe content of powders which could influence the compressibility coefficient of sludge cake and sludge zeta potential were the major factors influencing sludge dewaterability. The comparison of feasibility and economic analysis showed that adding RH-SCB improves the quality of the sludge filtrate and reduces the pollution potential of conditioned sludge (the ratio of secondary and primary (RSP) of Cu, Zn, Cd reduces from 43.05, 144.00, 7.25 to 7.89, 14.63, 4.27, respectively), and the costs of using RH-SCB were the lowest (at 88.4% lower than that of the raw sludge). Therefore, it is feasible to use RH-SCB to improve sludge dewaterability.

Investigation on the pore characteristics of coal specimens with bursting proneness

To achieve further insight into the pore characteristics, the coal specimens with different bursting proneness before and after uniaxial compression failure are tested and compared in this paper. The data of mercury intrusion test is corrected by that of low-temperature nitrogen adsorption and desorption test (LTNAD). The pore size distribution and pore volume of specimens are obtained. The pore compressibility coefficient is determined based on the fractal dimension of pore. Scanning electron microscope (SEM) and computed tomography (CT) are combined to evaluated the pore connectivity. The value of pore compressibility coefficient of specimens with high bursting proneness is larger than that of medium bursting proneness. It means more compressibility and abrupt failure under stress. The researches of both SEM and CT indicate that the pore connectivity of specimens with medium bursting proneness is better. The results show that great differences exist in the pore characteristics of specimens with high and medium bursting proneness, and uniaxial compression failure exacerbates the complexity of pore characteristics.