จำนวน Repository ( 2131 )

การประยุกต์ใช้หม้อแปลงฟลายแบคสำเร็จรูปสำหรับแหล่งจ่ายไฟฟ้าแรงดันสูงความถี่สูง
การประยุกต์ใช้หม้อแปลงฟลายแบคสำเร็จรูปสำหรับแหล่งจ่ายไฟฟ้าแรงดันสูงความถี่สูง

In this article the construction of a high-frequency high-voltage commercial flyback transformer to supply an input voltage for a tesla transformer is proposed. The purpose of a demonstration is a breakdown through the air gap of electrode. To confirm the proposed method the design of control of a flyback converter by using a commercial flyback transformer is rated with a 10 to 15 kV output voltage to supply a tesla transformer at a rated 30 kV and 120 kHz. The experimental results of an output breakdown design of the electrode and the setting for a 1 cm space are constructed. The electrodes consisted of the following: sphere–sphere electrode plane–plane electrode sphere–plane electrode and rod–plane electrode. It was found that there was a breakdown at the output electrode in all cases. Accordingly there was a breakdown with a 2 cm sphere diameter with reference to the IEC 60052-2002 standard; after that it was compared with the standard table and the atmospheric and temperature at the laboratory were adjusted resulting to a high voltage equal to 31.5 kV.

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การวิเคราะห์ปริมาณสารสำคัญและฤทธิ์ต้านอนุมูลอิสระของสารสกัดใบกะเปียดเครือ
การวิเคราะห์ปริมาณสารสำคัญและฤทธิ์ต้านอนุมูลอิสระของสารสกัดใบกะเปียดเครือ

Premna trichostoma Miq. (Lamiaceae) mainly distribute in Asia including Thailand. Folk healers use this plant to treat fever as a juice splash and bathe. The aims of this study are to evaluate the quantity of active constituents and antioxidant activity of P. trichostoma leaf extract. Total phenolic compounds were determined using Folin-Ciocalteu method. Total flavonoid contents were determined by Aluminum chloride method. The amount of apigenin and kaempferol contents were analyzed by high performance liquid chromatography (HPLC). In addition the antioxidant activity was evaluated by DPPH and ABTS assay. The results showed that total phenolic contents total flavonoid contents and the amount of apigenin and kaempferol of P. trichostoma leaf extract was 46.45±15.30 mg GAE/g extract 25.48±2.02 mg CE/g extract 11.16±0.04 and 4.54±0.08 µg/g extract respectively. The IC50 values from the DPPH and ABTS assay was 117.50±1.22 and 36.14±1.53 µg/ml respectively. This study shows the antioxidant properties and active constituents of P. trichostoma leaf extract which indicates the potentials for further development of this plant

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การควบคุมคุณภาพและลดการสูญเสียในกระบวนการประกอบชิ้นส่วนบังโคลนหน้าแก้มข้างรถยนต์ด้วยวิธีโพคา-โยเกะ
การควบคุมคุณภาพและลดการสูญเสียในกระบวนการประกอบชิ้นส่วนบังโคลนหน้าแก้มข้างรถยนต์ด้วยวิธีโพคา-โยเกะ

This study aimed to use Poka-Yoke techniques to help prevent errors and reduce loss in Front Side Fender Model assembly process. The researchers used four tools in the 7QC tools which were Check Sheet Cause-and-Effect Diagram and Graphs to search for causes and ways to solve problems and Cause and Effect Matrix and ECRS Techniques. The study revealed that the main cause of the problems was that the incorrect assembled side fenders were submitted to another department. This mistake had bad effects on time and workforce spent for correcting work including more expenses. The mistakes occurred because there was no tool for detecting errors in the work piece. Therefore the researchers use Poka-Yoke techniques in order to decrease errors by designing a control system for target detection while it was moving through the process. After collecting data the study showed that before the improvement during January to August 2019 the number of problems caused by the process were 0.093. However the number of problems after the improvement during September to December 2019 reduced to 0. It was obvious that this improvement reduced the loss from the front side fender assembly process up to 100.

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Real-time travel time prediction algorithm using spatiotemporal speed interval patterns matching
Real-time travel time prediction algorithm using spatiotemporal speed interval patterns matching

Accurate efficient and robust travel time prediction is crucial to the development of advanced traveler information systems for providing route guidance information. To achieve this goal this paper proposed a travel time prediction through the matching of the current speed interval pattern to that in a historical database. Speed intervals instead of speeds are considered in this study to simplify the structure of matching patterns for improving matching efficiency. In this study speed interval patterns are defined by sets of link speed intervals that are either spatially or temporarily correlated with the link considered. With the speed interval patterns the algorithm is developed for searching the historical pattern(s) that is/are the closest match with the current one. Then link speeds from these matched patterns are combined for travel time prediction. By using the GPS probe taxi data which the collected speeds are aggregated in every 5 minutes the proposed travel time prediction system is implemented in Bangkok. With the speed data from probe taxi this paper has chosen four links/paths with different geometric and flow characteristics for testing the performance of the proposed travel time prediction system. From these tests it is found that the optimal speed interval pattern should include: 1) speeds of the studied link within three preceding time intervals and; 2) speeds of links in the first connection level of the studied link. Also while the computational time is capable of real-time application the proposed prediction algorithm is more accurate under uninterrupted flow conditions.

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สมบัติการดูดซับน้ำมันทอดอาหารของนอนวูฟเวนจากเส้นใยเซลลูโลสฟางข้าว
สมบัติการดูดซับน้ำมันทอดอาหารของนอนวูฟเวนจากเส้นใยเซลลูโลสฟางข้าว

The objectives of this research were to study cellulose fiber extraction from rice straw with sodium hydroxide in various conditions (with 5 1 0 and 1 0 % of sodium hydroxide at room temperature 60ºC and 90 ºC for 0.5 1 2 and 3 hours) and to study rice straw nonwovens preparation by the wet-laid process. Oil wicking ability oil absorption ability air permeability morphology and physical properties of prepared nonwovens were investigated. It was found that the optimal condition for cellulose fiber extraction from rice straw was 5% of sodium hydroxide at 90 ºC for 2 hours. At this condition the cellulose fiber yield of 2 2% and the fiber length of 1 . 9 6 cm were obtained. The oil wicking ability and oil absorption ability of rice straw nonwovens increased when weight per unit area increased. Therefore oil absorbed into gaps between fibers of the nonwovens by capillary effect. Moreover the nonwovens could wick and absorb virgin palm oil better than fried palm oil because virgin palm oil has a lower viscosity than fried palm oil. The viscosity increased from derived lipid and other substances which dissolve and disperse increasing after frying food. The results indicated that the rice straw nonwovens had oil absorption ability.

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