The capture of a target spacecraft by a chaser is an on-orbit docking operation that requires an accurate, reliable, and robust object recognition algorithm. Vision-based guided spacecraft relative motion during close-proximity maneuvers has been consecutively applied using dynamic modeling as a spacecraft on-orbit service system. This research constructs a vision-based pose estimation model that performs image processing via a deep convolutional neural network. The pose estimation model was constructed by repurposing a modified pretrained GoogLeNet model with the available Unreal Engine 4 rendered dataset of the Soyuz spacecraft. In the implementation, the convolutional neural network learns from the data samples to create correlations between the images and the spacecraft’s six degrees-of-freedom parameters. The experiment has compared an exponential-based loss function and a weighted Euclidean-based loss function. Using the weighted Euclidean-based loss function, the implemented pose estimation model achieved moderately high performance with a position accuracy of 92.53 percent and an error of 1.2 m. The in-attitude prediction accuracy can reach 87.93 percent, and the errors in the three Euler angles do not exceed 7.6 degrees. This research can contribute to spacecraft detection and tracking problems. Although the finished vision-based model is specific to the environment of synthetic dataset, the model could be trained further to address actual docking operations in the future.
In one, docking is defined as “when one incoming spacecraft rendezvous with another spacecraft and flies a controlled collision trajectory in such a manner to align and mesh the interface mechanisms”, and defined docking as an on-orbital service to connect two free-flying man-made space objects. The service should be supported by an accurate, reliable, and robust positioning and orientation (pose) estimation system. Therefore, pose estimation is an essential process in an on-orbit spacecraft docking operation. The position estimation can be obtained by the most well-known cooperative measurement, a Global Positioning System (GPS), while the spacecraft attitude can be measured by an installed Inertial Measurement Unit (IMU). However, these methods are not applicable to non-cooperative targets. Many studies and missions have been performed by focusing on mutually cooperative satellites. However, the demand for non-cooperative satellites may increase in the future. Therefore, determining the attitude of non-cooperative spacecrafts is a challenging technological research problem that can improve spacecraft docking operations. One traditional method, which is based on spacecraft control principles, is to estimate the position and attitude of a spacecraft using the equations of motion, which are a function of time. However, the prediction using a spacecraft equation of motion needs support from the sensor fusion to achieve the highest accuracy of the state estimation algorithm. For non-cooperative spacecraft, a vision-based pose estimator is currently developing for space application with a faster and more powerful computational resource.
คณะเทคโนโลยีการเกษตร
Dwarf whipray (Brevitrygon heterura) is a common species found in a local market in the Gulf of Thailand. However, like many other species of stingrays, it is threatened by overfishing and habitat destruction. Therefore, an accurate species identification is crucial because conservation efforts may vary depending on the species. This study aims to understand morphological variation of B. heterura in the Gulf of Thailand by morphometric study and genetic analysis. During October 2022 and February 2023, we obtained 49 samples from research vessels fish landing ports and local fish markets. We observed two distinct groups based on 43 morphological variables/ratios. B. heterura samples from Chanthaburi, Rayong, Chonburi, Samut Sakhon, Nakhon Si Thammarat and Songkla provinces, called “group A," typically have longer snout length than those from Prachuap Khiri Khan provinces, called “group B" according to external morphological characters for species identification. Three morphological variables/ratios were significantly different between groups A and B. Main characters to explain intraspecific variations between group A and group B are further discussed. DNA barcoding based on a fragment of the cytochrome c oxidase subunit I (COI) gene were obtain from eight samples of group A and eight samples from group B. Pairwise percent sequence divergence (p-distance) for COI between group A and group B were 0.0-2.5. This study contributes to the understanding of variations of morphology and genetics of B. heterura in the Gulf of Thailand.
คณะวิทยาศาสตร์
Agricultural products and by-products are important raw materials in various industries including cosmetics and pharmaceuticals. Agro-based fibers have the composition, properties and structure that make them suitable for uses as composite-cosmetic industry. Upon microwave digestion, cellulose have been successfully synthesized into nanocrystalline cellulose (NCC) with lengths from 50-1000 nm, widths between 5-70 nm. Nanocrystalline cellulose was grafted with cosmetic active ingredients such as glycerin), sodium hyaluronate), glycolic acid, and nicotinamide. The beauty active ingredients attached nanocelluloses can penetrate through the skin to enhance beauty and youth.
คณะเทคโนโลยีการเกษตร
This research gives a comprehensive overview of the use of antibiotics in livestock production, highlighting both the benefits and the risks associated with their use. The benefits, such as improving immunity, digestion, and reducing infections, are contrasted with the growing concern over antibiotic residues and the development of drug resistance. The shift towards alternatives like probiotics is explored as a sustainable solution, with a specific focus on lactic acid bacteria (LAB) found in the digestive systems of livestock. Thailand’s regulations, which control antibiotic use in animal feed, are also discussed, setting the stage for the study on LAB as a potential replacement for imported probiotics. 1. Use of Antibiotics in Livestock: Antibiotics have been used to promote growth, improve digestion, and prevent infections in livestock. However, the improper use of antibiotics can lead to residues in animal products and the development of drug-resistant bacteria. 2. Global Trends in Antibiotic Use: Many countries, like the European Union and Japan, have banned antibiotics as growth promoters, while others, like China and the U.S., are planning similar bans. 3. Thailand's Approach: Thailand has implemented a regulation since September 2020 to control the use of antibiotics in animal feed, requiring control at both feed mills and farms that mix their own feed. 4. Probiotics as an Alternative: Probiotics, particularly lactic acid bacteria (LAB), are being studied as an alternative to antibiotics. LAB are naturally found in the digestive tracts of livestock and are considered beneficial for maintaining gut health and replacing the need for antibiotics. The study examines the potential of LAB from Thai livestock (broilers, pigs, and cattle) as a sustainable alternative to imported probiotics, aiming to overcome issues like low survival rates of foreign probiotics in practice.