Due to the modern urban system's high demand for stable electricity supply, underground cable power transmission has been increasingly adopted as a replacement for overhead power transmission. However, underground cable transmission still faces several operational challenges, such as significantly higher investment costs compared to overhead transmission, prolonged repair times in the event of system failures, limited fault analysis capabilities, and restricted capacity for additional load handling. This research project is designed to study the issues associated with the 22 kV XLPE underground cable system by utilizing the polarization and depolarization current analysis technique, a modern insulation diagnostic method.
เนื่องจากระบบเมืองสมัยใหม่ มีความต้องการใช้พลังงานไฟฟ้าที่มีเสถียรภาพสูงมากกว่าในอดีต ทำให้มีการนำระบบการส่งจ่ายพลังงานไฟฟ้าด้วยสายเคเบิลใต้ดินมาใช้งานกันอย่างแพร่หลายแทนที่การส่งพลังงานไฟฟ้าด้วยสายส่งเหนือหัว อย่างไรก็ตามการส่งจ่ายพลังงานไฟฟ้าด้วยสายเคเบิลใต้ดินยังมีปัญหาในการใช้งานอยู่หลายประการเช่น การลงทุนที่สูงกว่าการส่งจ่ายพลังงานไฟฟ้าเหนือหัวอยู่หลายเท่า การใช้เวลาแก้ไขเป็นระยะเวลานานเมื่อเกิดความล้มเหลวของระบบส่งจ่าย ความสามารถในการวิเคราะห์ปัญหาที่จำกัด ความสามารถในการรับภาระเพิ่มเติมเป็นต้น โครงการวิจัยนี้ออกแบบมาเพื่อศึกษาปัญหาของสายเคเบิลใต้ดินระบบ 22 kV XLPE โดยอาศัยเทคนิค การวิเคราะห์กระแสโพลาไรซ์และกระแสดีโพลาไรซ์ซึ่งเป็นเทคนิคการวิเคราะห์ฉนวนสมัยใหม่
คณะเทคโนโลยีการเกษตร
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คณะอุตสาหกรรมอาหาร
Bio-calcium powders were extracted from Asian sea bass bone by heat-treated alkaline with fat removal and bleaching supplementary method. Cereal bars (CBs) were fortified with produced bio-calcium at 3 levels: (1) increased calcium (IS-Ca; calcium ≥10% Thai RDI), (2) good source of calcium (GS-Ca; calcium ≥15% Thai RDI), and (3) high calcium (H-Ca; calcium ≥30% Thai RDI) which were consistent with the notification of the Ministry of Public Health, Thailand: No. 445; Nutrition claim issued in B.E. 2023. Moisture content, water activity, color, calcium content and FTIR analysis of bio-calcium powders were measured. Dimension, color, water activity, pH and texture of fortified CBs were determined. Produced bio-calcium could be classified as a dried food with light yellow-white color. Calcium contents in bio-calcium powder was 23.4% (w/w). Dimension, weight and color except b* and ΔE* values of fortified CBs were not different (P > 0.05) from those of the control. Fortifying of bio-calcium resulted in harder texture CBs. An increase of fortified bio-calcium amounts decreased carbohydrate and fat but increased of protein, ash and calcium in the fortified CBs. Shelf life of CBs was to be shorten by fortification of bio-calcium powder because of the increment of moisture, water activity and pH. Yield of bio-calcium production was 40.30%. Production cost of bio-calcium was approximately 7,416 Bth/kg while cost of fortified CBs increased almost 2-3 times compared to the control. Calcium contents in IS-Ca (921.12 mg/100g), GS-Ca (1,287.10 mg/100g) and H-Ca (2,639.70 mg/100g) cereal bars could be claimed as increased calcium, good source of calcium and high calcium, respectively. In conclusion, production of cereal bar fortified with Asian sea bass bone bio-calcium powder as a fortified food was possible. However, checking the remained hazardous reagents in bio-calcium powder must be carried out before using in food products and analysis of calcium bioavailability, sensory acceptance and shelf life of the developed products should be determined in further studies.
คณะเทคโนโลยีการเกษตร
The extreme weathers according to PM 2.5 is a global problem with out any borders. This pollutant can directly attack human health. The objective of the study was aimed to develop medicinal plant essential oil emulsions in order to use to decrease PM 2.5 based on chemical characterization of water-soluble anions and cations. A mount of 31 medicinal plant essential oil emulsions were prepared and then initially careened and tested for their efficiency in reducing PM 2.5 under test chamber by spraying method. It was found that spraying for 1 hr with kaffir lime essential oil emulsion at 0.025% concentration could reduce PM 2.5 obtained from engine exhaust pipe effectively when PM 2.5 of 24.7 µg/m3 was detected within 6 hrs, followed by kaffir lime essential oil emulsion at 0.05% and Eucalyptus essential oil emulsion at 0.05% and 0.025% concentration resulting in 27.3, 30.0 and 95.3 µg/m3, respectively. Whereas, water (blank) and control group (water and carboxymethylcellulose, CMC 0.2%) showed high revels of PM 2.5 with 126.4 and 157.3 µg/m3, respectively. This kaffir lime essential oil emulsion at 0.025% concentration showed 3-6 time decline of PM 2.5 upward 2 hrs compared with control group. Field experiment was performed at 3 Bangkok parks, namely, Suantaweewanarom, Suanbankharepirom and Suanthonbureerom. There were many factors affecting the decline of PM 2.5 caused by this essential oil emulsion, particularly, the windy as well as temperature and humidity. PM 2.5 level tended to be decreased after the beginning of spraying. In general, PM 2.5 levels appeared at those 3 parks were decreased rapidly within 1 hr as by average of 21.8 (7.7-27.3) µg/m3, Whereas, decline of only 6.4 (5.0-8.0) µg/m3 was observed in control (water). Incase of calm wind, (10-20 km/hr) this plant essential oil emulsion could even reduce PM 2.5 at 37.0-44.0 µg/m3 and reached to 13.5-16.5 µg/m3 within 3 hrs. As high level of PM 2.5 as 98.0-101.0 µg/m3 , it could reduce PM 2.5 to be an average of 23.0-26.5 µg/m3 within 3 hrs, Whereas, the use of water performed low capacity of PM 2.5 reduction found with only 31.0-40.0 µg/m3. However, windy condition (15-35 km/hr), the efficacy of this essential oil emulsion seem to be lower but tended to work better than using water alone