Angle Values Research Articles

Influence of Heat Treatment on Properties and Microstructure of EN AW-6082 Aluminium Alloy Drawpieces After Single-Point Incremental Sheet Forming

An EN AW-6082 aluminium alloy is one of the 6000 series aluminium alloys with the highest strength properties. Due to its favourable strength-to-density ratio, it is used, among others, in the automotive and aviation applications. It is also characterised by good formability, especially in the annealed condition. This article presents the results of investigations on the possibility of forming a 2 mm thick EN AW-6082 alloy sheet using the incremental sheet-forming process depending on the material condition (O, W, T4, T6). The microstructure of the material after heat treatment and the mechanical properties of the workpiece material in as-received state, as well as after forming, were examined. Additionally, for selected cases, additional heat treatment of the drawpieces was performed to improve their mechanical strength. The values of the limit-forming angle were determined for the materials tested. The values of this angle varied from 69° for the annealed sheet to 61° for the material in the T6 condition. The highest yield stress (YS) and ultimate tensile strength (UTS) were found for sheets (YS = 305 MPs and UTS = 324 MPa) and the artificially aged drawpieces (YS = 333 MPa and UTS = 390 MPa). Additional ageing after incremental sheet forming resulted in an increase in strength properties compared to drawpieces without additional heat treatment only in the case of drawpieces made of sheet metal after the solutionising and in T4 condition.

RNA-TorsionBERT: leveraging language models for RNA 3D torsion angles prediction.

Predicting the 3D structure of RNA is an ongoing challenge that has yet to be completely addressed despite continuous advancements. RNA 3D structures rely on distances between residues and base interactions but also backbone torsional angles. Knowing the torsional angles for each residue could help reconstruct its global folding, which is what we tackle in this work. This paper presents a novel approach for directly predicting RNA torsional angles from raw sequence data. Our method draws inspiration from the successful application of language models in various domains and adapts them to RNA. We have developed a language-based model, RNA-TorsionBERT, incorporating better sequential interactions for predicting RNA torsional and pseudo-torsional angles from the sequence only. Through extensive benchmarking, we demonstrate that our method improves the prediction of torsional angles compared to state-of-the-art methods. In addition, by using our predictive model, we have inferred a torsion angle-dependent scoring function, called TB-MCQ, that replaces the true reference angles by our model prediction. We show that it accurately evaluates the quality of near-native predicted structures, in terms of RNA backbone torsion angle values. Our work demonstrates promising results, suggesting the potential utility of language models in advancing RNA 3D structure prediction. Source code is freely available on the EvryRNA platform: https://evryrna.ibisc.univ-evry.fr/evryrna/RNA-TorsionBERT. Supplementary data are available from the website.

THERMOHYDRAULIC PERFORMANCE ANALYSIS OF ABSORBER TUBE WITH COILED WIRE TURBULATORS IN SMALL APERTURE PARABOLIC TROUGH COLLECTOR

Three-dimensional (3D) simulation using computational fluid dynamics (CFD) has been performed to investigate the impact of a coiled wire turbulator (CWT) on heat transfer and fluid flow in the absorber tube of a small aperture parabolic trough collector (PTC) under a turbulent flow regime. The PTC was modeled with a projected aperture area of 0.64 m<sup>2</sup> and an optimized value of rim angle 90 degrees using the ray tracing tool SolTrace based on an optimum value of average heat flux (8.58 kW/m<sup>2</sup>), and this optimum average heat flux was used as one of the boundary conditions in CFD simulation. The CFD-simulated findings for the smooth absorber tube of the PTC model are compared with the Dittus-Boelter equation for heat transfer and the Filonenko equation for friction factor. The simulated result showed an average deviation of 2.54% and 14.68% in the Nusselt number and friction factor, respectively. The effect of a wall-detached type of CWT (D<sub>m</sub> = 10 mm) on thermohydraulic performance with coil pitch ratios (P/d<sub>h</sub>) of 1, 1.5, and 2 and height ratios (e/d<sub>h</sub>) of 0.053, 0.063, and 0.074 is considered for the analysis in the Reynolds number (Re) range of 4000-12000. The optimal value of thermohydraulic performance (η<sub>thp</sub>) is obtained 1.56 for P/d<sub>h</sub> = 2, e/d<sub>h</sub> = 0.053, and Re = 4000, corresponding to which enhancement ratio of Nusselt number (Nu<sub>r</sub>/Nu<sub>s</sub>) and friction factor (f<sub>r</sub>/f<sub>s</sub>) are 2.28 and 3.14, respectively.

INVESTIGATION OF THE PROCESS OF FLAX PULLING BY DEVICES WITH TRANSVERSE STREAMS

Background: Mechanized harvesting of crops is carried out by the most efficient flax milling machines with transverse band-disc streams. At the same time, the analysis of the works showed that they did not analyze the action of the inertia forces of plants when moving in curved pulling streams, their effect on the quality of the technological process was not established, the condition for pulling all plants from the soil without their excessive flattening was not determined, which reduces their effectiveness. Aims: theoretical and experimental study of the process of pulling flax plants with devices with transverse ribbon-disc streams. Materials and methods: Experimental studies were carried out according to well-known and developed methods, with an assessment of flax products according to GOST standards. The influence of the centrifugal forces of inertia of plants on the bending of the plant ribbon, stretching of its upper part and loss of seed crowns, and the condition of pulling all plants, taking into account the maximum strength of the resistance of plants to tearing, were determined. Standard equipment and developed installations were used. Results: Dependences were obtained for determining the inertia forces of plants in the zones of pulling pulleys and deflecting rollers, and bending moments created by the inertia forces of plants and acting on plants, as well as the speed of the pulling belt, to prevent greater inertia forces of plants, negatively affecting the quality of work, and the condition of pulling all plants from the soil with taking into account the maximum strength of the resistance to stretching. The limit value of the bending angle of the plant ribbon, which should not exceed 20 °, has been experimentally established. Conclusions: When designing flax milling machines with belt-disc streams to reduce the forces of inertia, it is necessary that the elements of adjacent milling sections have the same size and shape as possible, which will reduce the forces of inertia of plants, eliminate peak pressures in the stream, increase the durability of the belt, reduce losses of flax products.

Evolution of Multifunctional Cotton Fabric as the Flame Retardant/Crease Proof/Microbial Resistant Blended With Green Synthesised TiO2 Nanoparticles Coatings

ABSTRACTIn this work, green synthesised TiO2 nanoparticles' coating was used to improve the fire safety and antibacterial property of 100% cotton fabric. In the first stage, Aloe vera extract was prepared, and subsequently used in the synthesis of TiO2 nanoparticles. The average size of these as‐synthesised TiO2 nanoparticles was confirmed to be 16 nm using DLS (dynamic light scattering). Further, XRD (X‐ray diffraction) patterns confirmed the successful synthesis of nanoparticles. The vibrational photon of TiO2 was represented by peaks in the FTIR (Fourier transform infrared spectroscopy) spectrum between 450 and 800 cm−1. Subsequently, in an attempt to establish the flame retardant/crease proof/microbial resistant properties of the as‐synthesised TiO2 nanoparticles, the TiO2 NPs coated cotton fabric was used for the investigations. Based on the investigations, the bending length (measure of fabric stiffness) value of the coated fabric (%) increased from 2.4 cm (uncoated fabric) to 3.71 cm (at 20% TiO2 coating). Also, the crease recovery angle value increased from 71.8 (uncoated fabric) to 98.6 (20% TiO2 coating), respectively. A vertical flammability test revealed that the burning time decreased from 13.31 s (0%) to 10.84 s (20%), confirming a fire‐retardant trait of green synthesised TiO2 nanoparticle coated fabric. Additionally, the disc diffusion method confirmed that the treated coated fabrics exhibit antibacterial properties against both gram‐positive and gram‐negative bacterial cultures: Escherichia coli and Staphylococcus aureus. This study provides an environmentally benign route for producing versatile cotton fabric blended with bioinspired TiO2 NPs possessing improved flame resistance as well as antibacterial attributes.

DISSIPATION OF WAVE ENERGY AND MITIGATION OF WAVE FORCE BY MULTIPLE FLEXIBLE POROUS PLATES

Abstract The hydroelastic interaction between water waves and multiple submerged porous elastic plates of arbitrary lengths in deep water is examined using the Galerkin approximation technique. We observe the influence of flexible porous plates of arbitrary lengths by analysing the reflection coefficient, dissipated energy and wave forces acting on the plates. Results are presented for various values of angle of incidence, separation lengths of plates, porosity levels, submergence depth and flexural rigidity. The convergence and accuracy of the method are verified by comparing the results with existing literature. The significant impact of flexural rigidity in the presence of porosity on wave reflection, dissipated energy and wave forces is demonstrated. Moreover, a notable reduction in wave load is observed with an increase in the number of plates.

NUMERICAL MODELING OF RETAINING STRUCTURES MADE OF BLOCKS WITH SOIL INFILL

The relevance of the study is driven by the expanding use of numerical models in the design practice of retaining structures and the need for their verification. A promising design solution for retaining walls is a stepped structure, sequentially constructed from hollow-body box type blocks infilled with crushed stone. This solution has several features that require the adaptation of existing calculation methods. A numerical model of a retaining structure made of thin-walled blocks infilled with soil has been developed based on the analysis of the interaction between the structure's components under load, taking into account the work of the foundation and surrounding soil. The SiO2D finite element modeling computer software was used as a modeling tool. The calculation results for the proposed numerical models are compared with corresponding results for analytical solutions. The parameter values of the main physico-mechanical properties of the numerical models were determined as a result of field and laboratory tests in accordance with standard methodologies considering the scale of the tests. The features of the design solution and construction technology of retaining structures made of thin-walled reinforced concrete blocks infilled with crushed stone were examined. Numerical models of retaining structures made of soil-infilled blocks were constructed using the domestic software package SiO2D. Laboratory and field tests established the parameters of the numerical model of the retaining structure. The research demonstrates high values of the structural cohesion («interlocking») parameter c (up to 60 kPa), alongside a high internal friction angle value φ (up to 60°), ensuring high shear stability of the infilled blocks. The study, using numerical models, proposes a calculation basis for retaining structures made of soil-infilled blocks forming a stepped construction, where the blocks are not rigidly connected but are held in their design position by the internal resistance forces of the soil against shear.

Effect of Zycotherm Nano-Based Warm Mix Additive on the Properties of Asphalt Binders in the UAE

Warm-Mix Asphalt (WMA) additives are used to improve the performance and workability of the asphalt binders. This study used a nano-based saline, Zycotherm, to reduce the viscosity and improve the high-temperature performance of the asphalt binders. To investigate the impact of Zycotherm, penetration, softening point, viscosity and Dynamic Shear Rheometer (DSR) rutting parameter tests were carried out. Based on the results, the Zycotherm-modified asphalt binder with a percentage of 3% lowered the penetration by around 40% and the softening point by 4%, while increased the viscosity by 10% when compared to the control asphalt binder. Rheological testing showed a decrease in the complex shear modulus value and a decrease in the phase angle by around 24% for the Zycotherm modified asphalt binder, which means that the rutting resistance decreases by 13%. Zycotherm modified asphalt binder with a percentage of 1.5% showed nearly similar results as the 3% in terms of lowering the penetration by 20% and softening point by 2% while increased the viscosity even more than the 3% Zycotherm by an overall percentage increase of 11% when compared to the control asphalt binder. For the Rheological testing, the Zycotherm modified asphalt binder with a percentage of 1.5% also showed a 12% decrease in phase angle and complex shear modulus values.

Determining articulation parameters using the Avantis 3D software, considering the individual hinge axis position

BACKGROUND: Axiography (condylography) is used to assess the temporomandibular joints (TMJ) function and obtain individual articulator settings. Creating a virtual patient with TMJ dysfunction and determining its individual articulation parameters considerably simplify the procedure and accelerate the diagnosis for further rehabilitation. AIM: To assess the potential of a virtual articulation system using the Avantis 3D software for determining angular parameters of mandibular movement, considering the individual hinge axis position. MATERIALS AND METHODS: The clinical phase of the study included 25 volunteers aged 18–30 years, without complaints of TMJ dysfunction, previous orthodontic treatment, and malocclusion. All volunteers underwent electronic condylography (axiography) using the CADIAX Diagnostic device; the movement of mandible heads during protrusion and mediotrusion was analyzed. The individual values of sagittal condylar inclination (SCI) and Bennett angle on the left and right were obtained. The individual hinge axis was determined, and special radiopaque markers were placed on the skin in the projection of its rotation. Additional markers were placed on the lower edge of the left orbital cavity. Using these markers, cone beam computed tomography (CBCT) was performed in all volunteers, with a 17.5×20.0 matrix size, to create a 3D project, compare CBCT findings with virtual dental models, and generate a reference plane. Virtual occlusion measurements were obtained in terminal positions (protrusion and laterotrusion) using the Trios 3 Basic Pod intraoral scanner. The Avantis 3D software was then used to create 3D scenes based on the obtained measurements and CBCT of the skull. The mean length of each path registered for virtual articulator settings in the Avantis 3D software was approximately 3 mm. The interarticular distance used for the analysis was recalculated using the Avantis 3D software to be equal to the standard intercondylar distance of the articulator, which is 110 mm. Individual SCI and Bennett angle values were obtained for all study subjects. The experimental phase involved phantom models installed in a fully adjustable articulator Reference SL. CBCT was performed with an installed articulator and a maxillary cast, in a zero position, with closed center locks, which was matched to the maxilla present in the CT scan, and a 3D scene was created to measure SCI and Bennett angle values. After detecting the articulator’s hinge axis, electronic measurements of movement were taken, with a predefined SCI of 20–60° (increment 5°) and Bennett angle increments of 6, 12, and 20°. The results were assessed for a path of 3 mm. RESULTS: The mean difference between the compared determination methods of angular parameters obtained during the experimental phase of the study was 3.20±7.22° for the left SCI; 2.09±9.75° for the right SCI; 5.50±11.26° for the left Bennett angle, and 6.40±6.29° for the right Bennett angle. The mean difference between the compared determination methods of angular parameters obtained during the clinical phase of the study was 11.80±6.86° for the left SCI; 12.10±6.08° for the right SCI; 13.0±9.89° for the left Bennett angle, and 10.70±11.48° for the right Bennett angle. CONCLUSION: Both approaches for determining angular parameters can be recommended for use in real-world dental practice. When sophisticated, expensive equipment is not available, a virtual articulation system in the Avantis 3D software can be used as a more simple and affordable technique of measuring angular parameters.

Synthesis of Gamma Irradiated Cobalt Oxide Nanoparticles for Visible Light- Induced Photocatalytic Degradation of Methylene Blue Dye

This research focuses on synthesizing and characterizing cobalt oxide (Co3O4) nanoparticles using an ionizing radiation technique. The precursor cobalt (III) hydroxide, Co(OH)3 was chemically synthesized from cobalt (II) nitrate hexahydrate, [Co(NO3)2·6H2O] as a solution precipitation technique in an alkali medium. The Co(OH)3 precursor was then exposed to a 60Co gamma radiation source at a dose of 30 kGy with a dose rate of 10 kGy/hr to obtain Co3O4 nanoparticles. The synthesized Co3O4 nanoparticles were subjected to various characterization techniques. Fourier-Transform Infrared (FT-IR) spectroscopic analysis of raw Co(NO3)2·6H2O, Co(OH)3 precursor, and Co3O4 nanoparticles revealed distinctive absorption peaks for the Co3O4 nanoparticles. X-ray diffraction analysis exhibited different characteristic diffraction angles (2θ) values, lattice spacing, and crystal size for the Co3O4 nanoparticles. SEM images of raw Co(NO3)2·6H2O, Co(OH)3 precursor, and Co3O4 nanoparticles displayed distinguishable surface morphologies. Additionally, the thermogravimetric analysis provided insight into the decomposition behaviour of the Co(OH)3 precursor. The characterization data indicated that the ionizing radiation-synthesized Co3O4 nanoparticles possessed similar properties to those synthesized using conventional methods. Furthermore, the ionizing radiationsynthesized Co3O4 nanoparticles demonstrated an efficient photo-catalytic effect in the degradation of methylene blue (MB) dye. Therefore, this study shows the successful synthesis and characterization of Co3O4 nanoparticles using an ionizing radiation technique, highlighting their potential application in photo-catalysis for the degradation of MB dye. J. of Sci. and Tech. Res. 6(1): 175-185, 2024

Research on Phase Angle Correction Control Strategy for Grid-Forming Cluster in Distributed Energy Resources

The active power-phase angle droop control avoids the frequency deviation problem caused by taking the frequency as the droop variable. However, the active power output of distributed generations (DGs) can only be allocated by adjusting the droop coefficient, and the reference value of active power output cannot be set arbitrarily. In this paper, a phase angle correction module attached to the active power-phase angle droop control is proposed. This correction module is based on the real-time data of the voltage and phase angle of the node at the generation end and the transmission end of the grid, and directly changes the phase angle reference value of the active power-phase angle droop control output. The correction can make the phase angle reference value reach the phase angle value corresponding to the active power reference value without changing the actual characteristics of the droop control, so as to adjust the active power output of the converter to reach the active power reference value. Finally, the feasibility of the correction method in different cases is verified by Matlab 23.2.0.2365128 (R2023b)/Simulink simulation.

SHEAR STRENGTH PARAMETERS AND DEFORMABILITY PROPERTIES OF SILICATE-BASED RESIN ADDED SAND-TYPE SOIL SPECIMENS

In this study, the shear strength, uniaxial compressive strength (UCS) values and deformability properties of silicate-based polymer resin added silty sand type soil specimens were examined through a series of experimental studies. Although the UCS and shear strength values increased, minor decreases in the internal friction angle values were measured as the resin ratio increased. It was determined that the main reason of improvement in the strength values due to the increase in resin content is the increase in cohesion values. It was found that the UCS values calculated according to the cohesion and internal friction angle parameters of the Mohr&Coulomb failure criterion (UCSc) were 2.6-3.0 times lower than the values obtained from the direct UCS experiment. According to this finding, it was concluded that the Mohr&Coulomb failure criterion is not properly usable to represent the mechanical behaviors of resin added sands. As another outcome, the ratio between UCS/UCSc slightly decreased with an increase in the resin amount. In other words, it has been determined that the Mohr&Coulomb failure criterion gives a bit more inaccurate results for the specimens with low binder contents. With the increase in the resin content ratio, significant increases were obtained in both elastic modulus and ductility properties of the samples. It has been evaluated that the silicate-based polymer resin binder is advantageous to provide significant increases in the toughness and energy absorption capacity of soils.

Incidence, risk factors, and prognostic consequences of femoroacetabular cup impingement following hip resurfacing arthroplasty.

Hip resurfacing arthroplasty (HRA) is recommended for younger patients seeking higher levels of activity. However, femoroacetabular cup impingement (FACI) between the femoral neck and acetabular prosthesis remains a concern. This study aimed to determine the incidence, risk factors, and prognostic consequences of FACI after HRA. This study included 242 HRAs performed at a single institution. Three types of implants with different cup articular arc angle (CAAA) values were used. FACI was defined as indentation or spur formation at the femoral neck corresponding to the ridge of the acetabular cup. Multivariate regression analyses were conducted to identify risk factors for FACI. Clinical outcomes were compared between groups with and without impingement. The mean follow-up duration was 12 years (range, 2‒19). FACI was identified in 87 out of 242 HRAs (36%). Multivariate regression analysis showed that FACI was associated with the use of implants with a greater CAAA (P < 0.001). At the latest evaluation, the mean Harris Hip Score (94 vs. 93; P = 0.405) and the incidence of groin pain (16.1% vs. 14.8%; P = 0.795) were similar between the groups with and without FACI. Implant survivorship free of any revision was 94.5% in the FACI group and 89.8% in the non-FACI group at 12 years (log-rank, P = 0.165). This study identified that the incidence of FACI after HRA was 36%. Implants with greater CAAA were associated with a higher risk of impingement. However, radiographic FACI was not associated with adverse clinical outcomes of HRA after a mean follow-up of 12 years.

Impact Load Resistance of Steel after Heat Treatment and Quenching with Distilled Water

Given that low carbon steels have favourable mechanical properties, they are widely used in power plant components, oil and gas pipelines, and armor structures. However, the relationship between a steel's structure and mechanical properties can occasionally be negatively impacted by the existence of ferrite and pearlite phases in its microstructure. One of the most crucial aspects of engineering metallurgy is the heat treatment of steels, which improves a variety of mechanical and physical characteristics that are useful in many structural applications. The heating and cooling of an alloy or metal while it is solid in order to refine its grain size and other properties and create the necessary microstructures is known as heat treatment. This paper will use distilled water as a cooling medium at various temperatures to perform repeated heat treatments. Comparing the impact load resistance of the original and treated specimens is the goal, as is the impact of multiple heat treatments and the use of distilled water as a medium for cooling at different temperatures. The findings of an Excel program study show that the heat-treated samples had a greater impact resistance value than the untreated ones. The strong martensitic network alloys created by heat treatment procedures are the main factor contributing to the increase in impact load resistance. The average pendulum angle values of the six heat-treated compounds were found to have a higher elevation angle than the average values of the original group. There was the least amount of decrease from the average value of the second group, which was 0.93 %. The average toughness values of the six heat-treated groups increased in comparison to the original group&amp;#39;s average values, with the second group experiencing the largest percentage increase (11.96%). Based on the difference in coolant temperatures, the group that was cooled in distilled water at zero temperature had the best toughness value.

ON IDENTIFICATION OF PARAMETERS OF A NONLINEAR CONSOLIDATION MODEL OF SANDY SOIL

Previously, the authors of this article formulated a physically and geometrically nonlinear formulation of the problem of porous fluid-saturated medium deformation during fluid filtration (consolidation problem) in terms of the rate of solid phase displacement and the change in pore pressure in differential and variational forms. The developed consolidation model takes into account changes in the porosity and permeability of the medium during deformation. Deformation-type constitutive relations are used in the model. The developed consolidation model can be used to simulate non-stationary processes in the soil, for example, the formation of ruts and unevenness of dirt roads, as well as to calculate the uneven settlement of engineering structures. This work is devoted to the experimental determination of the deformation and strength properties of water-saturated sandy soils, which is the next stage in the consolidation process simulation. The results of the experimental determination of the bulk and shear properties of sandy soil using the ASIS automated complex (OOO NPP “Geotek”) are presented. The studies were carried out on three quartz sands of various grain sizes. To determine the volumetric moduli of dry and water-saturated sandy soils, compression tests were carried out under a continuously growing vertical load at a constant strain rate. The experiments were carried out for various strain rates in the range from 3·10–6 to 3·10–3 s–1. According to the experimental results, the bulk properties do not depend on the strain rate in the specified range. Deformation and strength shear characteristics of sandy soils were determined by the method of multiplanar shear, approximating a simple shear. The tests were carried out under a kinematically applied shear load with a given constant strain rate according to the scheme of consolidated-drained shear. The dependences of the deformation and strength properties of coarse and fine quartz sands on the shear strain rate in the range from 2·10–4 tо 4·10–3 s–1 were studied. Increasing, decreasing and nonmonotonic dependences of the internal friction angle on the shear strain rate were obtained for dry and water-saturated sands of various grain sizes. For water-saturated sands, the maximum spread in the values of the internal friction angle for different strain rates does not exceed 7 %. A technique has been developed for recalculating the obtained properties and experimental dependences into the parameters of the proposed sandy soil consolidation model.

DEFORMATION OF A THIN FILM AFTER CONTACT LOSS WITH A CYLINDRICAL BASE, WITH ACCOUNTING FOR THE INFLUENCE OF ITS CURVATURE, COMPLIANCE, AND ACTION OF TRANSVERSE FORCES; DELAMINATION LOCATED IN THE CIRCUMFERENTIAL DIRECTION

Delamination of a coating from a cylindrical substrate under compressive stresses is considered. The solution of the problem was obtained within the theory of cylindrical shells. The Mushtari-Donnell-Vlasov equations were used as the equilibrium equations, and the conditions of the generalized elastic clamped type were used as the boundary conditions. Expressions are obtained for the coating displacement components and the energy release rate during delamination along the rectilinear and curvilinear delamination boundaries. The profiles of the exfoliated section of the coating were obtained. The role of the substrate compliance and its curvature on the values of the energy release rate and the angle of rotation at the clamping point, as well as in the change in the shape of the coating profile, is revealed. It is shown that with an increase in the compliance of the substrate, as well as the value of (positive) curvature, the value of the energy release rate and the value of the normal component of the displacement of the coating increase significantly. It has been found that at sufficiently large values of the substrate curvature, a corrugation effect occurs in the profile of the delaminated section of the coating, which results in the local extrema in the graph of the dependence of the energy release rate on the delamination length. This effect was not observed in the delamination located in the longitudinal direction [1]. It is also shown that for sufficiently compliant substrates there is a certain critical delamination width, for which it becomes energetically more favorable for delamination to develop in the circumferential direction than in the axial one. As the positive curvature and compliance of the substrate increase, the value of the critical width decreases. An alternative criterion for the critical delamination width is also considered, which consists in studying the value of the angle of rotation at the embedding point, which corresponds to the overlap of the coating and substrate surfaces at an angle value of zero.

Influence of sodium chloride on corrosion resistance of ever silver vessels in the presence of curd rice

The present work is undertaken to investigate the corrosion resistance of ever silver in the presence of water, water+curd system, water+curd+rice system, water+curd+rice+Salt system. The corrosion resistance has been evaluated by AC impedance spectra . AC impedance spectra have been employed to investigate the corrosion resistance of ever silver electrode when it is immersed in various test solutions like water, curd, curd rice recipe, curd rice recipe with salt (sodium chloride 500 ppm). The corrosion resistance of ever silver electrode when it is immersed in various test solutions like water, water+curd, water+curd+rice and water+curd+rice+salt have been evaluated by AC impedance spectroscopy. If a protective film is formed, the charge transfer resistance increases, impedance value increases, phase angle value increases and double layer capacitance (Cdl) value decreases. When Ever silver electrode is immersed in water + curd rice system + 500ppmsodium chloride system, the corrosion resistance of ever silver electrode decreases. This is due to the presence of chloride ion introduced into the curd rice system. It implies that when curd rice is packed in vessels made of ever silver, we should avoid adding salt to the curd rice. It is better to keep the salt and curd rice separately. It is to be noted that this corrosion resistance is better than the corrosion resistance in water alone. The corrosion resistance decreases in the following order: Water + Curd + Rice system &gt; Water + Curd + Rice + Salt system (sodium chloride 500ppm) &gt; Water+ Curd system &gt; Water

Study on the Influence of Surfactant Solution on the Wetting and Chemical Structure Characteristics of Coal at Different Temperatures.

To reduce the production of dust in the coal mine production process, the surface tension and contact angle of the solution at different temperatures were measured, and the temperature range of the surfactant to achieve the best wetting effect during the coal seam water injection was determined. The results show that the surface tension and contact angle of sodium dodecyl sulfate (SDS) and sodium dodecylbenzenesulfonate (SDBS) and of SDS and polysorbate 80 (Tween80) decrease rapidly at first and then increase slowly with the increase of temperature, the minimum surface tension values were 26.293 and 27.726 mN/m, and the minimum values of contact angles were 89.35 and 65.1°, respectively. The two kinds of composite solutions have the best wetting effect at 35-40 °C. In addition, the influence of surfactants on the chemical structure of coal under different temperature conditions was analyzed, and the variation rule between the chemical structure and the wetting property of coal was explored. The research results have important practical guiding significance for reducing dust generation in a coal mine.

Removal of Remazol Brilliant Blue R Dye from Water Using Eggshell Mixed Matrix Membrane through Filtration and Adsorption

Water pollution causes flora and fauna to be destroyed and this process might be irreversible as well as lead to other bad consequences, especially towards human beings. Due to the inefficiencies of the dyeing process, it is estimated that up to 200,000 tonnes of dyes are released into wastewater annually by the textile industry. This research aimed to fabricate the mixed matrix membranes made up of eggshells that were combined with silica (SiO2) for dye removal of Remazol Brilliant Blue R (RBBR). Poly ether sulfone (PES) and N-methyl-pyro-lidone (NMP) will be added in the formulation as a binder and solvent, respectively. The results from the characterisation and filtration process of the ceramic membrane with different ratios of eggshells and silica for removing Remazol Brilliant Blue R (RBBR) dye were compared. The ATR-FTIR showed a strong existence of carbonate minerals and silica proving its functional group and properties of having good capacity in filtration. The water contact angle measurement of the 4:1 ratio of eggshell: silica gave a low contact angle value which is 2.16o while the contact angle for a 1:1 ratio membrane is 1.99o, thus, the synthesis of the membrane was successful. From the filtration process, it was discovered that the 4:1 ratio of eggshell: silica was able to remove the 50 ppm blue dye with a removal efficiency of 81.39% compared to the 1:1 ratio with a removal efficiency of 76.17%. The adsorption capacity or the amount of dye adsorbed onto hollow fibre membrane and flat sheet membrane were found to be 1.423mg/g with an adsorption percentage of 71.15% and 1.616mg/g with an adsorption percentage of 80.80% respectively. To sum up, eggshells are a practical way to remove RBBR dye from a solution and a potential raw material for membrane manufacturing.

Trajectory Planning With A* Algorithm and Tracking With Multiple Controllers

ABSTRACTThis article consists of mathematical modelling of differential drive mobile robot (DDMR), path planning and tracking application via multiple controller usage. Robot kinematic and dynamic models were constructed and simulated in virtual 2D map environment. A* algorithm was applied to the 2D map problem to acquire optimal pathfinding, efficiency and flexibility in trajectory planning stage. After the reference trajectory is obtained by algorithm, the robot needs to be guided using control strategy that manages the speed control of electric motors. At the first part of the control problem, kinematic based backstepping control (KBBC) were used to increase the efficiency of the control system. After that Sliding Mode Control (SMC) and Proportional‐Integral‐Derivative (PID) control strategies were applied to reduce tracking errors between reference and actual coordinate values and heading angle value. To test the robustness and efficiency of control combinations, two different simulation systems were designed using Matlab‐Simulink Software. First system was designed for the non‐disturbance condition, while the second system included disturbance torque and an additional mass applied condition. Test results showcasing the performance of the controllers are presented in the concluding section, through trajectory tracking and error comparison graphs.