Search

Background: As advancements in surgical instruments and techniques continue to evolve, minimally invasive surgery has become increasingly preferred as a means of reducing patient pain and recovery time. However, one major challenge in performing minimally invasive surgery for early gastrointestinal cancer is accurately identifying the location of the lesion. This is particularly difficult when the lesion is confined to the lumen of the intestine and cannot be visually confirmed from the outside during surgery. In such cases, surgeons must rely on CT or endoscopic imaging to locate the lesion. However, if the lesion is difficult to identify with these images or if the surgeon has less experience, it can be challenging to determine its precise location. This can result in an excessive resection margin, deviating from the goal of minimally invasive surgery. To address this challenge, researchers have been studying the development of a marker for identifying the lesion using a radio-frequency identification (RFID) system. One proposed method for clinical application of this detection system is to attach an RFID tag to an endoscopic hemostatic clip and fix it to the intended position, providing a stable marker for the inner wall of the organ. This approach has the potential to improve the accuracy and effectiveness of minimally invasive surgery for early gastrointestinal cancer. Methods: In the development of a marker for identifying gastrointestinal lesions using a radio-frequency identification (RFID) system, the shape of the clip and suitable materials for attaching the RFID tag were determined through finite element method (FEM) analysis. A prototype of the clip was then fabricated and ex-vivo experiments were conducted using porcine intestine to evaluate the stability of the clip in relation to its position. To further evaluate the performance of the RFID-integrated clip in vivo, the clip was placed in the gastric wall of the stomach of anesthetized porcine using an endoscopic instrument. The clip was then detected using a RFID detector designed for laparoscopic approach. And later, the accuracy of detection was confirmed by incising the lesion. Results: The design and fabrication of a clip with varying thicknesses using STS316 and STS304 stainless steel were accomplished using the results of finite element method analysis. The stability of the clip was evaluated through ex-vivo experiments, showing it to be a viable option. In-vivo experiments were performed on anesthetized porcine, in which the RFID-integrated clip was placed in the gastric wall and detected using a custom-made RFID detector. The resection margin, measured at about 30 mm from the detector position, was accomplished with low error. These findings indicate the feasibility and efficacy of using an RFID-integrated clip as a marker in minimally invasive surgery for the identification of gastrointestinal lesions. Conclusions: The study evaluated the feasibility of using stainless steel clips for lesion detection in endoscopic surgery using computer-aided engineering analysis and ex-vivo experimentation. Results showed that STS304 was suitable for use while STS316L was not. The ex-vivo experiments revealed that the clip holding force and tissue retention length varied depending on the location of attachment. In-vivo experiments confirmed the accuracy and usefulness of the RFID lesion detection system. However, challenges remain for its use in clinical field, such as ensuring the stability of the clip and the safe attachment of the RFID tag, which requires further research for commercialization. [ABSTRACT FROM AUTHOR]

A feasibility study on the mass production of a small wind turbine blade using an injection molding process was conducted. The blade was divided into three sections suitable for injection molding, and the mold was designed and analyzed using Moldflow CAE S/W. The optimal feedstock material was selected through comparison and analysis of three candidate materials. A mold was manufactured to test the injection molding process and evaluate related parameters. The resulting blade was assembled with other components, and a generator was installed to assess its durability, safety, and performance under various conditions. The results indicated the feasibility of producing a blade for a small wind turbine through injection molding, which predicted higher productivity and lower costs compared to traditional manufacturing methods that rely heavily on manual labor. [ABSTRACT FROM AUTHOR]

Electroslag remelting (ESR) is used widely throughout the specialty metals industry. The process generally consists of a regularly shaped electrode, wherein a small amount is immersed in liquid slag at a temperature higher than the melting temperature of the electrode. Melting droplets from the electrode fall through the lower density slag into a liquid pool constrained by a crucible and solidify into an ingot. High quality ingots require that electrode melt rate and immersion depth be controlled at all times during the process. This can be difficult when process conditions are such that the temperature distribution in the electrode is not at steady state. This condition is encountered during the beginning and closing stages of the ESR process and also during some process disturbances such as when the melt zone passes through a transverse electrode crack. To address these transient melting situations, a new method of the ESR estimation and control has been developed that incorporates an accurate, reduced order melting model to continually estimate the temperature distribution in the electrode. The ESR process is highly nonlinear, noisy, and has coupled dynamics. An extended Kalman filter and an unscented Kalman filter were chosen as possible estimators and compared in the controller design. During the highly transient periods in melting, the unscented Kalman filter showed superior performance for estimating and controlling the system. [DOI: 10.1115/1.4000660] Keywords: electroslag remelting, Kalman filter, model-based control, unscented Kalman filter

This paper proposes a novel method for register partially overlapped three-dimensional (3D) point sets when a complete 3D scanned model is constructed from partially scanned 3D point sets. 3D point sets are the most primitive and fundamental surface representations. 3D acquisition devices such as laser scanners and range image finders are popular sources for acquiring point clouds. With the availability of low cost and highly efficient 3D laser scanners, the popularity of such devices is increasing rapidly in various fields. Generally, a standard scanner can obtain only a partial data to build a complete 3D model of the object. These partially scanned 3D patches need to be aligned together in the same coordinate system to construct a complete 3D model, and this process is widely known as registration. A coarse-to-fine alignment technique is proposed to register two partially overlapped point sets. First, the overlapping regions using a novel sampling strategy are identified and the overlapping regions of two point sets are aligned together. Second, fine registration is carried out, in which an auxiliary pair and surface normal constraints are used to find reliable corresponding points in order to achieve higher accuracy. [ABSTRACT FROM AUTHOR]