National University of Formosa

Abstract Machining of SKD11 tool steel challenging task due to high hardness and strength of material, which are responsible for accelerated cutting tool wear, high cutting temperature, and poor surface finish. The traditional cooling system is not able to control the heat generation process at higher speeds in an effective manner. Also, the previous research work related to Ultrasonic-Assisted milling has focused on restricted scope. This study work is concentrated on the development of an improved cutting strategy which enhances the life of the cutting tool and the quality of the surface. This work approach combines Ultrasonic-Assisted milling with through-tool internal cooling method. The ultrasonic vibration generates a high-frequency, low-amplitude motion which reduces the friction and improves chip removal. However, the internal cooling performs coolant injection directly into the cutting zone for better heat dissipation. Comparative experimental tests between Z-axis, XY-axis, and XYZ-axis ultrasonic mode assisted milling under different cooling conditions proved that the best results were obtained by Z-axis ultrasonic assistance and internal cooling: surface roughness was decreased by 20–31%, and the temperature by 15–28%, as compared to conventional milling. Various machine learning (ML) models, such as Decision Tree, Random Forest, and AdaBoost, are used to predict cutting tool wear. Among these, AdaBoost provides the highest accuracy and precision values i.e., 0.94 and 0.964286 respectively, which is more improved by a simple ensemble vote. This integrated process and predictive model offer a practical solution to improve the machinability of SKD11 and enable smarter, more sustainable manufacturing.

Wireless charging systems have become increasingly popular, but they still suffer from standby power consumption even after batteries are fully charged. Recently, CPT wireless power transmission technology has been adopted. However, it can cause voltage spikes to damage the components when the battery is moved after complete charging. To address these issues, a low-cost circuit is proposed to eliminate standby power consumption. A microcontroller unit is used to control the switch of the power source. When the battery is fully charged, the switch will be turned off. Therefore, zero standby power consumption can be achieved by cutting off the power source from both the main circuit and the standby power reduction circuit. Experimental results show that the proposed circuit effectively eliminates standby power consumption while maintaining charging efficiency. This circuit can be easily implemented in wireless charging systems and can help improve energy efficiency and reduce power consumption.

Abstract Stabilizing high structural stiffness and spatial motion accuracy is a paramount challenge in industrial multi-axis robotic systems, particularly under dynamic loading and large workspace operation. This work presents a unified multi-domain approach to assess and optimize the mechanical performance of a six-axis robotic arm by combining finite element analysis (FEA), experimental modal analysis (EMA), spatial deformation mapping, and 6D laser interferometry. Modal simulations identify the first three natural frequencies as 108.9 Hz, 113.6 Hz, and 259.1 Hz, with experimental validation confirming modal peaks at 109.0 Hz, 114.0 Hz, and 259.0 Hz, respectively error < 1% , indicating high fidelity in frequency prediction. Spatial deformation varied between 15.3 µm to 25.7 µm, and frequency–deformation correlation analysis mapped optimized ≥ 105 Hz, ≤ 20 µm and risk-prone regions throughout the workspace. Real-time six-degree-of-freedom validation using a 6D laser interferometer indicated Y-axis positioning accuracy of 14.0 µm and peak X-axis deviation of 113.0 µm at extreme lower zones −350 mm. The integrated framework provides a robust foundation for stiffness-aware task allocation, workspace partitioning, and structural optimization. The results offer practical insights into the deployment of high-precision robotic platforms in aerospace, micro-assembly, and biomedical automation.

Abstract This study presents the vibration characteristics of a spur gear system in different damage conditions through a combined experimental and numerical methodology. A single 32-teeth spur gear is examined both in normal conditions and with combined levels of tooth cuts and crack depths. Vibrational signals recorded by accelerometers, are analyzed using Fast Fourier Transform (FFT) techniques and examined for trends that reflect damage. Besides, the influences of rotational speed (RPM) on gear vibrations are examined at varying levels. The definite integral concept of mathematics is utilized for the quantification of damage severity. The research accentuates the importance of RPM in vibration properties with reference to its application in fault diagnosis. It points out the viability of vibration analysis for detecting gear faults and evaluates the correspondence between damage severity and vibration energy distribution.

This study focuses on developing a composite material using graphene oxide (GO) as a dielectric film. First, GO was mixed with DI water and dried to form a film. Then, a titanium (Ti) film was deposited on the film surface through electron beam evaporation. The composite comprising graphene oxide with the Ti metal film was then dispersed in water, to which cellulose nanofiber (CNF)—noted for its high mechanical strength, stability, and lightweight attributes—was added. The mixture was then re-layered with cellulose nanofibers by agitating it in water, and subsequently dried to form a composite film. The electrical properties of the material were studied using an LCR meter. The results show that pure GO has a dielectric constant of about 1600 at 1 kHz and a dielectric loss of about 25. After adding Ti, the Ti composite film maintained a dielectric constant above 1000 at 1 kHz while significantly reducing the dielectric loss to 1.5. Additionally, the resistivity of pure GO at 1 kHz is approximately 1200 Ω·m, whereas the Ti composite film with Ti and cellulose nanofibers shows a resistivity as high as 50 k Ω·m at 1 kHz. The relationship between dielectric strength and resistivity indicates that the Ti composite film can withstand higher voltages compared to pure GO, demonstrating a significant increase in dielectric strength. Compared to graphene oxide, the Ti composite film combines high dielectric constant, low dielectric loss, and increased dielectric strength.

ABSTRACT: This study evaluated the adequacy of using digestibility values obtained by the in situ (ISOMD) method for predicting the average daily gain (ADG, g day-1) of free-ranging cattle through the Pampa Corte model. The evaluation was based on a data set compiled from two independent trials conducted with growing beef cattle grazing native grasslands of southern Brazil. Values of digestibility obtained through the N fecal method (FNOMD) were used as comparative reference in the present study. The predictions of ADG were performed at both individual (n= 41) and group (i.e. diet treatment within trials, n= 10) levels. Parameters generated from regression analyses between observed versus estimated values of ADG (i.e. determination coefficient (R2), root mean square error (RMSE), root mean square error of prediction (RMSEP), concordance correlation coefficient (CCC) and mean bias) were used to evaluate the predictive adequacy. The observed values of ADG were linearly related to those predicted by the Pampa Corte at both individual (R2= 0.52; RMSE= 148.9, CCC = 0.72, P < 0.05) and group levels (R2= 0.67; RMSE= 108.8, CCC = 0.81, P < 0.05), without effect of the method used to estimate herbage digestibility. However, compared to the FNOMD, the ISOMD resulted in higher mean bias of predictions (i.e. - 4.3 vs 61.6 g day-1). The ADG of free-ranging cattle grazing native grasslands of Southern Brazil can be adequately predicted by the Pampa Corte model using herbage digestibility values obtained through the ISOMD method. However, constraints associated with herbage sampling in heterogenous swards should be considered.

Introdução - A flacidez cutânea é uma condição comum que afeta a elasticidade e firmeza da pele, especialmente em indivíduos que passaram por perda de peso significativa ou envelhecimento. Com o avanço das técnicas fisioterapêuticas, diversas abordagens têm sido desenvolvidas para combater essa condição. Objetivo - deste estudo foi analisar a eficácia das principais técnicas fisioterapêuticas no tratamento da flacidez cutânea, destacando os métodos mais utilizados e os resultados observados. Metodologia - adotada foi uma revisão de literatura, utilizando bases de dados como PubMed, Scielo e Google Acadêmico. Foram selecionados artigos publicados entre 2005 e 2024 que abordavam intervenções fisioterapêuticas na redução da flacidez cutânea. Resultados e Discussão - indicaram que as técnicas mais eficazes incluem a radiofrequência, eletroestimulação e o uso de massagens terapêuticas específicas. Conclusão – conclui que, embora diferentes técnicas apresentem resultados promissores, a combinação de tratamentos pode potencializar a melhora da elasticidade da pele, sendo necessário personalizar as abordagens de acordo com as necessidades individuais de cada paciente.