Current Issue : July-September Volume : 2023 Issue Number : 3 Articles : 5 Articles
This paper proposes a novel electrolytic-free quasi-Z-Source uk LED driver for automotive applications. Compared to the traditional uk converter, the first merit of the novel converter is higher gain, which makes it apt to switch between multiple applications. Secondly, the proposed converter combines the inherent characteristics of LED load to operate in a wide range in Continuous Conduction Mode (CCM), so the inductors can assist in energy storage, and only small capacitance is required. Thirdly, inductors can be integrated and use only one core, and capacitors are electrolytic-free, which will benefit integration and long life. All merits are important to automotive application. Detailed analysis and design steps are presented. Then, with the help of the simulation software Saber, several key parts of the converter are simulated. Finally, a prototype controlled by the micro control unit stm32f103c8t6 is built, and the feasibility is verified by the experiment results....
This scientific article examines the issue of changes in the density and speed of the airflow in the pipeline pneumatic conveying equipment used in ginneries, analyzes the causes of changes in the density and speed of air....
Cermet coatings are post-treated by a new surface microcrystallization technology, namely high-temperature-assisted ultrasonic deep rolling (HT + UDR). The process parameters of ultrasonic deep rolling significantly affect the microstructure and tribological properties of the Ni-WC coatings. In this paper, the samples were treated with different preloading depths (0.20 mm, 0.25 mm, and 0.30 mm), and the microstructure and properties of the coatings were characterized by SEM, EDS, X-ray stress analysis, and micro-Vickers hardness testing. An MMW-1A-type friction and wear tester was used for the dry friction and wear test at room temperature, respectively. Compared with the untreated sample, plastic rheology occurred on the surface of the coatings after HT + UDR, showing a phenomenon of “cutting peaks and filling valleys”. In the treated coatings, visible cracks were eliminated, and the inside of the coating was denser. The surface hard phase was increased as a “skeleton” and embedded with the soft phase, which played a role in strong and tough bonding. After HT + UDR + 0.25 mm treatment, the surface roughness increased by 68%, the microhardness of the surface layer reached a maximum of 726.3 HV0.1, and the residual tensile stress changed from 165.5 MPa to −337.9 MPa, which inhibited the germination and propagation of cracks. HT + UDR improved the wear resistance of the coating in many aspects. The coating after the 0.25mmpreloading depth treatment possessed the smallest friction coefficient and the lowest wear amount, which is 0.04 and 4.5 mg, respectively. The wear form was abrasive wear, and the comprehensive tribological performance is the best....
Residual carbon on the inner surface of copper tubes is known to be a cause of pitting corrosion. We showed previously that the rapid filling test was useful to evaluate the pitting corrosion resistance of copper tubes. Immersion tests using the rapid evaluation test solution showed that corrosion occurs on the entire surface of copper tubes with low residual carbon amounts, while those with high residual carbon amounts show pitting corrosion. Therefore, it is necessary to improve the corrosion resistance of copper tubes with high residual carbon amount, which are expected to undergo pitting corrosion. As pitting corrosion occurs when anodes are locally concentrated on part of the metal surface, it has been suggested that anodes be dispersed over the entire surface by the processing of the metal surface. Metal processing methods have various purposes, including changing the shape and properties of metals, and in this case, leading to desirable surface properties (such as expansion and drawing processes). Here, we focused on the expansion process and its effects on corrosion resistance of copper tubes. The results showed that hydraulic expansion has a significant effect on the inner copper surface by improving corrosion resistance as the anode area increases....
Al–Cu–Li (2xxx series) powders for additive manufacturing processes are often produced by gas atomization, a rapid solidification process. The microstructural evolution of gas-atomized powder particles during solidification was investigated by phase-field simulations using the software tool MICRESS. The following topics were investigated: (1) the microsegregation of copper and lithium in the particle, and the impact of lithium addition on the formation of secondary phases in Al-2.63Cu and Al-2.63Cu-1.56Li systems, (2) the effect of magnesium on the nucleation and final mass fraction of T1 (Al2CuLi) growing from the melt, and (3) the effect of increased magnesium content on the T1 and S (AlCu2Mg) phase fractions. It is observed that the addition of lithium into the Al–Cu system leads to a decrease in the solid solubility of copper in the primary matrix; consequently, more copper atoms segregate in the interdendritic regions resulting in a greater mass fraction of secondary precipitates. Our result agrees with findings on the beneficial impact of magnesium on the nucleation and precipitation kinetics of T1 precipitates in the conventional casting process with further thermomechanical heat treatments. Moreover, it is observed that the increase in magnesium from 0.28 wt.% to 0.35 wt.% does not significantly affect the nucleation and the amount of the T1 phase, whereas a decrease in T1 phase fraction and a delay of T1 formation are encountered when magnesium content is further raised to 0.49 wt.%....
Loading....