Papers by Keyword: Charge

Abstract: Direct compounding of long fiber thermoplastic (LFT-D) materials in compression molding are two complex processes in series linked by the plastificate. Continuous compounding and sequential compression create a time-dependent property progression along the extrusion direction of the plastificate. Under variation of secondary parameters, extruder die temperature, and die height of the LFT-D line, samples of plastificates, flow fronts and plates are manufactured and characterized. The plastificate density progression along the extrusion direction is primarily influenced by the temperature of the die. Lofting of the plastificate is higher at high temperatures while the density difference along the extrusion direction is lower. This density difference is known to influence fiber orientations and mechanical properties. The flow front of the material filling the mold is skewed because of the density difference. We show that the skewness is mainly influenced by the die height and is lower at high die heights. The fiber content distribution in the plate is discussed and found to be influenced by the length of the plastificate which is in turn determined by the secondary parameters. These secondary parameters of the LFT-D line can play a role in process optimization once the primary parameters are selected. This work provides clues and observations of principles for such optimizations.

Abstract: The enhancement of thermal stratification in solar storage tanks is a crucial aspect of advancing solar energy technology. This study presents an experimental investigation conducted on a vertical cylindrical hot solar water storage tank operating in a dynamic mode, involving simultaneous charging and discharging. The experiment aims to assess the impact of varying inlet water flow rates (4, 6, 8, 10 L/min) on thermal stratification within the tank and explores strategies to mitigate heat losses to the environment and minimize mixing effects caused by the inlet fluid flow. The experimental setup incorporates insulation and an inlet port diffuser section to optimize the distribution of inlet water during the charging and discharging states. The results reveal that the utilization of an inlet port diffuser significantly improves thermal stratification by reducing heat losses and minimizing mixing effects, as evidenced by improved Richardson numbers. Additionally, this study contributes to the development of a compact solar domestic hot water (SDHW) solution.

Abstract: A rational way to process silver-containing concentrates of the Dukat Mining & Processing Plant has been proposed and justified based on a series of physical and chemical studies and large-scale laboratory and factory tests, which comprises arranging a combined enrichment and metallurgical scheme primarily aimed at obtaining two silver-containing products best meeting the pyro-and hydrometallurgical processing requirements by column flotation. Obtaining a rough silver-gold alloy comprises two basic process operations: redox roasting of concentrate and electric smelting of the roasted product to an internal collector using soda ash as a flux. It has been experimentally established that the concentrate roasting in the oxidizing mode does not allow sufficiently stable extracting noble metals into a compact dore bead by crucible fusion. Adding a reducing agent to the roasting charge has allowed stabilizing the process. Electric smelting is characterized by mechanical loss of silver with a secondary matte phase and in the form of metal beads ranging in size from 5 to 300 μm, which have failed to pass into the bottom phase in the time allotted. The developed technology is universal and allows processing ores with various material compositions.

Abstract: Geckos can run swiftly on various surfaces, is not only related to the micro-nanostructure of their setae, but also related to the charged keratin in biological tissues of epidermis. Many gecko-inspired structural materials have been developed in order to obtain desired adhesion property. Much research has been done to improve their adhesion by changing chemical composition and optimizing micro-nanostructure, but little research has been done on the effect of surface charge. Therefore, this study aims to investigate the effect of surface charge on the adhesion of gecko-inspired materials, and to explore a new way to improve their adhesion performance. In this work, the dry adhesive materials made of polyvinylsiloxane (PVS) with mushroom-shaped pillars were polarized under high voltage. The results showed that polarized samples with the mushroom-shaped pillars facing the positive electrode have more negative charge, and the adhesion was improved a lot with increasing charge.

Abstract: A method was developed for synthesis of a single phase lithium tantalate charge doped by rare earth elements (TR) from highly pure solutions containing tantalum. The method is based on obtaining and thermal treatment of citrate precursor containing Li, Ta and TR. Charge samples were obtained due to suggested technological scheme; the dopant had given concentration and was chemically uniformly distributed. The charge can be applied both in single crystal growing technology and at obtaining of functional ceramics based on LiTaO₃:TR.

Abstract: The paper presents experimental data on nickel oxidation during electrolysis under rectangular alternating current in alkaline solutions, when the cathode pulse (I_к ) is greater than the anode pulse ( I_а ). During the process, intense nickel destruction occurs forming bivalent oxide powder. Under prolonged electrolysis, this powder deposits at the bottom of the electrolyzer in the form of a sponge. The results obtained can be used to produce active mass in the porous nickel oxide electrode of a chemical current source.

Abstract: The paper shows that in the conditions of a deficit of high-quality metal charge in steels melting production, the effective use of waste from abrasive grinding in the composition of the metal charge is a promising method for reducing the cost of steel. The most rational solution for the disposal of metallurgical wastes may be the agglomeration of fine-grained and fine-dispersed materials using briquetting technology widely used in many countries around the world to produce multi-purpose briquettes.

Abstract: The general method to remove contaminated particles in the non-pattern cleaning such as pre-photo cleaning, post-deposition cleaning, and post-CMP cleaning is to physically remove particles using spray nozzle. However, high-speed fluids for increasing particle removal efficiency cause static electricity due to friction between liquid and nozzle surfaces, resulting in unexpected charge defects. In this study, we propose a method to reduce static electricity by changing the material of nozzle and grounding by visualizing static electricity according to electric voltage.

Abstract: The radiation hardness of two dielectrics, SiO₂ and Al₂O₃, deposited on low doped, n-type 4H-SiC epitaxial layers has been investigated by exposing MOS structures involving these materials to MeV proton irradiation. The samples are examined by capacitance voltage (CV) measurements and, from the flat band voltage shift, it is concluded that positive charge is induced in the exposed structures detectable for fluence above 1×10¹¹ cm^-2. The positive charge increases with proton fluence, but the SiO₂/4H-SiC structures are slightly more sensitive, showing that Al₂O₃ can provide a more radiation hard passivation, or gate dielectric for 4H-SiC devices.

Abstract: Investigations of microarc calcium phosphate (CaP) boehmite-containing biocoatings on the pure titanium (Ti) alloy were presented. There were discovered relationships of coating properties (morphology, elemental and phase composition, zeta-potential, wettability) on the boehmite deposition parameters. A variation of the modification parameters of boehmite nanoparticles deposition allowed producing hydrophilic boehmite-containing CaP coatings with the roughness of 2.2-3.1 μm and nanoscale morphology. The influence of boehmite nanoparticles on the surface zeta-potential of the coating was found.