http://yetl.yabesh.ir/yetl1/handle/yetl/19046 2026-04-23T02:59:38Z http://yetl.yabesh.ir/yetl1/handle/yetl/4310984 Integrating Decision Trees and Clustering for Efficient Optimization of Bioink Rheology and 3D Bioprinted Construct Microenvironments Limon, Shah M.; Sarah, Rokeya; Habib, Ahasan Among various 3D bioprinting methods, extrusion-based bioprinting stands out for its ability to maintain high cell viability and create intricate scaffold structures. However, working with synthetic polymers or natural shear-thinning hydrogels requires precise control of rheological properties, such as viscosity, to ensure scaffold stability while supporting living cells. Traditionally, researchers address these challenges through extensive experimentation, separately optimizing material properties and bioprinting performance. This process, though effective, is often slow and resource-heavy. To streamline this workflow, computational approaches like machine learning are proving invaluable. In this study, a decision tree model was developed to predict the viscosity of bioinks across various compositions with high accuracy, significantly reducing the trial-and-error phase of experimentation. Once viscosity is optimized, k-means clustering is applied to analyze and group scaffolds based on their mechanical and biological properties. This clustering technique identifies the optimal characteristics for scaffolds, balancing structural fidelity and cell viability. The integration of these computational tools allows researchers to optimize bioink formulations and printing parameters more efficiently. By reducing experimental workload and improving precision, this approach not only accelerates the bioprinting process but also ensures that the resulting scaffolds meet the required mechanical integrity and provide a conducive environment for cell growth. This study represents a significant step forward in tissue engineering, offering a robust, data-driven pathway to enhance both the efficiency and quality of 3D bioprinted constructs. 2025-01-01T00:00:00Z http://yetl.yabesh.ir/yetl1/handle/yetl/4310980 Feed Rate Improvement for Face Hobbing on a Six-Axis CNC Bevel Gear-Cutting Machine Shih, Yi-Pei; Lee, Yi-Hui; Chen, Kuan-Hung; Fong, Zhang-Hua; Wei, Bo-Lin; Wang, Yu-Chieh; Yu-Hsien, Wei Face hobbing is one of the two primary mass-producing methods for bevel gears. It is renowned for its high-quality contact and high production efficiency. This cutting method is widely used in the automotive industry. In contrast to face milling, face hobbing employs a more complex cutter system and cutting motions. These two methods used to be performed on different dedicated machines decades ago. Now, they are both integrated into modern six-axis computer numerical control (CNC) bevel gear-cutting machines. Modern CNC machines provide high precision and rigidity, enabling easier adjustments to cutting speeds through numerical codes (NC) programming, thereby improving cutting efficiency. While machine-recommended cutting feed rates are generally feasible, they may not be optimal. Engineers often need to manually adjust cutting speeds by monitoring cutting torque during the process. Additionally, the material removal rate (MRR) is vital in determining cutting torque. Although automatic optimization of feed rates based on the MRR is technically feasible, accurately determining the MRR for face hobbing has proven challenging. This article introduces a new ring-dexel-based cutting simulation method for face hobbing. The proposed approach calculates the MRR by simulating the removal volume and the planned feed rate. Experimental results reveal a nearly linear relationship between MRR and cutting torque, enabling accurate predictions of torque based on MRR. As a result, the feed rate was optimized, reducing the pinion machining time for the roughing process from 76 s to 43.5 s, while the ring gear machining time was reduced to just 1 min. 2025-01-01T00:00:00Z http://yetl.yabesh.ir/yetl1/handle/yetl/4310974 Acoustic Streaming-Assisted Underwater Laser Micromachining Process Charee, Wisan; Qi, Huan; Zhu, Hao; Saetang, Viboon A critical problem in the underwater laser micromachining process is the optical disturbance caused by gas bubbles in water, where the laser beam quality and cut quality are significantly deteriorated. This paper introduces an acoustic streaming-assisted underwater laser ablation technique, where an ultrasonic transducer is positioned parallel to the workpiece surface. This configuration generates a cross-streaming water flow that effectively removes laser-induced debris and bubbles during the ablation in water. A pure titanium sheet was drilled by a nanosecond pulse laser subjected to acoustic streaming in a water chamber. A glass window for confining water and separating it from ambient air was recommended to minimize the optical disturbance caused by water waves. By using the proposed laser micro-drilling technique, a clean through-hole, small hole taper angle of as low as 6.8 deg, and minimal heat-affected zone (HAZ) were achievable compared to laser micro-drilling in air and in water without the assistance of acoustic streaming. The effects of laser power and drilling duration on hole dimensions and HAZ indicated that the hole entrance diameter increased from 270 µm at 10 W to 410 µm at 30 W, while the HAZ width expanded up to 128 µm only. Statistical analysis using ANOVA showed that laser power had a significant effect on the hole entrance and HAZ, whereas drilling duration had a minor impact. The proposed technique can thereby be an effective method for high-precision microscale machining with reduced thermal damage. 2025-01-01T00:00:00Z http://yetl.yabesh.ir/yetl1/handle/yetl/4310905 Cavitation Intensity Mechanism in the Hydrodynamic Cavitation Abrasive Finishing Li, Dengting; Zhang, Tianyu; Wu, Ming; Wang, Wujun; Ding, Hongqin; Lin, Fangye; Zhu, Yi The hydrodynamic cavitation abrasive finishing (HCAF) technology, as an innovative, clean, and efficient polishing method, has been proven effective for processing the internal surfaces of additive manufacturing flow channels. However, in-depth mechanistic studies on the key factors affecting the cavitation intensity in the HCAF processing remain limited, even though they play a crucial role in optimizing polishing performance and enhancing process stability. This study aims to apply the HCAF process to the flow channels fabricated by the laser powder bed fusion (LPBF). By adjusting the abrasive inlet pressure and throat diameter, the optimal process parameter combination was obtained, resulting in a 90% reduction in surface roughness near the inlet. fluent simulations and high-speed imaging were conducted to further validate its effect on the cavitation intensity. Furthermore, the channel diameter was found to have a significant impact on the polishing performance. Additionally, predictions of cavitation intensity were used to guide the application of the HCAF polishing for channels of different diameters. The results indicate that although the abrasive inlet pressure has a minor effect on the incipient cavitation number, it significantly alters the pressure distribution in the mixed-flow chamber, thereby influencing cavitation dynamics. The high-pressure region accelerates cavitation bubble contraction and collapse, significantly reducing bubble lifespan and weakening both the intensity and persistence of the cavitation effect. This instability makes sustained cavitation enhancement in the HCAF difficult, affecting material removal efficiency and jet stability. Therefore, the abrasive inlet pressure plays a crucial role in controlling cavitation behavior and enhancing machining performance. 2025-01-01T00:00:00Z