Papers by Keyword: Temperature

Abstract: In this paper a comparative study regarding the temperature in milling process for some types of aluminum alloys and an austenitic stainless steel is presented. In order to measure the temperature two methods are used, non-contact method, using an infrared thermometer and a contact method with six thermocouples installed along the workpiece. From the point of view of cutting parameters, for the both methods, different rotational speed and depth of cut were used, while feed speed was kept constant.

Abstract: The main purpose of this paper is to analyze the values of the temperature after turning of pure titanium and its alloy, Ti6Al4V, as function of different cutting parameters (rotational speed, feed and depth of cut). Based on an infrared thermometer measurements for dry turning, with un-coated carbide insert, graphically dependencies of temperature as function of the cutting parameters are presented for the both materials.

Abstract: Silicon carbide (SiC) Schottky barrier diodes (SBDs) have become critical components in power electronics due to their excellent high-voltage, high-temperature tolerance, and fast switching capability. However, increasing device area to improve current-carrying capability increases the total number of defects, which leads to an increase in reverse leakage current and reduces wafer yield. To improve current distribution uniformity within SiC module packaging, reduce system size and weight, and enhance the current-carrying capacity and high-temperature stability of a single SBD, this paper develops 750V/100A and 1200V/100A SiC SBDs on 6-inch wafers. For the 750V/100A device, the corresponding forward voltage (V_F) at forward current (I_F) of 100 A is 1.68 V. For the 1200V/100A device, the corresponding V_F is 1.75V. Calculation based on the current voltage characteristics shows that the ideal factors of 750V/100A and 1200V/100A devices are 1.01 and 1.04, respectively, which are very close to 1. It demonstrates excellent Schottky contact and a high-quality interface. The devices exhibit high-temperature stability, meeting the demands of high-temperature applications.

Abstract: Massive structures are exposed to the risk of high temperatures due to cement hydration. With the requirement for sustainable development, the clinker content of conventionally manufactured cements is being reduced, resulting in the development of blended cements, which are gradually being introduced into production. Therefore, the development of temperatures in massive concrete structures containing modern blended cement is the subject of an experimental program. Its results are evaluated not only in terms of the properties of the resulting concrete, but also in terms of the possibility of concrete production and the technology of mixing. Finally, recommendations are given for the design of concrete mixtures for massive structures. Furthermore, the article deals with the comparison of the measured values with the thermal analysis of the structures.

Abstract: Excessive heat generation during bone drilling is a leading cause of thermal osteonecrosis—a serious risk in medical departments. Despite extensive drill design research, the influence of margin geometry remains underexplored. This study presents finite element modeling and statistical optimization to evaluate and optimize drill margin geometry—specifically margin width (Mw) and height (Mh)—to reduce bone temperature rise during surgery. A thermo-mechanical finite element model was developed in DEFORM-3D to simulate cortical bone drilling using drill bits with varied margin dimensions. The models were validated experimentally using bovine cortical bone, with an average temperature prediction errors of 2.4–8.0%. The maximum bone temperature (T_max) was selected as the objective function. A central composite design (CCD) was applied to generate experimental runs, followed by response surface methodology (RSM) and desirability-based optimization. The second-order effect of Mw contributed 47.2% to T_max. The optimal Mh (0.05 mm) and Mw (0.22 mm)—with a desirability value of 0.985—could reduce T_max below the osteonecrosis level with only a 44.8 °C temperature rise. This study demonstrates a novel computational approach for optimizing surgical drill margins—a previously underutilized parameter. The findings may support future developments in drill bit customization and robotic surgery systems to minimize thermal injury to bone cells.

Abstract: The paper deals with an experimental determination of the temperature dependence of the contact angle of wetting of the tungsten substrate by liquid tin using the sessile drop method. Unlike the traditional method of heating of one drop of melt on a solid substrate, here a new similar drop of liquid tin was supplied through the capillary as the temperature increased. It was found that the values of the contact angle decreased with the growing temperature, but these values increased again at higher temperatures. Our findings indicate that, as applied to the tin–tungsten system, the curve of temperature dependence of the contact angle shows the sections of an anomalous increase in values of the contact angle as the temperature rises. We observed this effect earlier in the tin–steel system, and it was given a theoretical explanation from the standpoint of the quantum-mechanical model of Wentzel–Kramers–Brillouin quasiclassical representations.

Abstract: Lithium-ion batteries are the preferred choice for electric vehicles (EVs) due to their high energy density, low self-discharge, thermal stability, and long cycle life. Morphology of materials is essential in assessing the effectiveness of lithium-ion battery cathodes. One effective way to evaluate cathode quality is by examining its precursor (NMC-811) morphology using SEM. Samples were taken every 20 minutes over 2 hours, revealing that longer reaction times improve the homogeneity and semi-spherical shape of the NMC-811 precursor, with increased particle density and a reduced average diameter. NMC-811 was synthesized by a calcination process at temperatures of 450°C, 600°C, and 700°C, and sintering temperatures of 800°C and 900°C. SEM analysis revealed that higher calcination temperatures resulted in a more homogeneous particle structure, with variations in holding time having minimal impact on particle shape.

Abstract: Microbially induced calcite precipitation (MICP) is a promising alternative method for improving the geotechnical properties of granular soils. The effectiveness of the MICP technique depends on several variables, including relative density and temperature. The objective of this study was to determine the effect of different initial relative densities and ambient temperature ranges on the effectiveness of MICP. After 300 and 600 hours of MICP treatment, with injection cycles occurring every 12 hours, the specimens with a relative density of 34.5% were found to be effectively cemented. In contrast, specimens with a relative density of 59.8% were found to be less cemented. A greater percentage of specimens (52.4%) were cemented at warmer ambient temperatures (20-28°C), compared to only 15.7% at cooler temperatures (16-24°C). These results suggest that the looser soil matrix and warmer temperatures facilitated CaCO₃ precipitation and resulted in greater cementation.

Abstract: Mycelium-based composite (MBC), as a new engineering biocomposite, is receiving numerous interests due to its environmental sustainability. The study aimed to address the challenge of optimizing the physical properties of MBC for a more efficient production process. The study investigated the impact of hot or cold pressing, different pressing temperatures (120 °C, 160 °C, and 200 °C), pressing pressures (low, medium and high) and sequences (before and after drying process) on the physical properties of MBC such as density, shrinkage, moisture content and hardness. Mycelium millets were mixed with kenaf, carbon carbonate, wheat bran and wheat flour. The pressing methods and sequences significantly affected the properties of the MBC. Cold pressing had no effect on reducing shrinkage and moisture content of MBC but improved density. Hot pressing increased hardness at higher temperature and pressure, with strong mycelium-substrate bonding and less porosity observed in SEM image. The post processing sequence involving drying followed by hot pressing at 200°C exhibited higher density, hardness, less shrinkage and controllable moisture content of MBC for better dimensional stability and quality control purpose. It was crucial to optimize MBC pressing techniques for specific applications and ensure that it satisfied the demanding standards of companies looking for sustainable alternatives and cost-effective production.

Abstract: Fossil fuels continue to dominate energy use, despite growing environmental concerns, underscoring the need for renewable energy solutions. Photovoltaic cells convert sunlight but lose efficiency from heat, requiring cooling methods such as photovoltaic thermal systems. Tthis study evaluated a PVT system with three serpentine tubes under varied conditions using computational fluid dynamics simulations. Testing involved water coolant flow rates of 0.001, 0.005, and 0.009 kg/s, radiation intensities of 200, 400, and 600 W/m², and tube diameters of 15 mm and 17 mm. Increasing the mass flow rate significantly reduced temperature and improved thermal efficiency, while electrical efficiency remained stable as the PV panel temperature mainly influenced it. The optimal cooling performance was achieved with a 0.009 kg/s mass flow rate and a 15 mm tube diameter at 600 W/m² radiation intensity. These findings suggest water-based cooling may increase PV system performance and reliability, especially in high solar locations.