จำนวน Repository ( 52 )

การวิเคราะห์อิทธิพลที่มีผลต่อผลผลิตพืชไร่ทางเศรษฐกิจที่สำคัญในพื้นที่เพาะปลูกเขตภาคกลางของประเทศไทยด้วยตัวแบบทางคณิตศาสตร์อย่างมีประสิทธิภาพ
การวิเคราะห์อิทธิพลที่มีผลต่อผลผลิตพืชไร่ทางเศรษฐกิจที่สำคัญในพื้นที่เพาะปลูกเขตภาคกลางของประเทศไทยด้วยตัวแบบทางคณิตศาสตร์อย่างมีประสิทธิภาพ

The objectives of this research are to propose an approate and efficient model for analyzing rice corn and sugar yields data. A linear mixed model (LMM) with spatial correlation following the conditional autoregressive model (CAR) was adopted. The results show that for rice yields if the amount of rainfall in a harvest season increases 1 mm the yields will decease by 25.74 tons. if the temperature in the harvest season increases 1 Celsius the yields will decease by 212.60 tons and according to the trend the yield will increase by 15.80 tons each year. For sugar cane yields if the amount of rainfall in the harvest season increases 1 mm the yields will decease by 51.35 tons. if the temperature in the harvest season increase 1 Celsius the yields will incease by 121.30 tons and according to the trend the yield will increase by 29.93.80 tons each year. For corn yield if the amount of rainfall in the havest season increases 1 mm the yields will incease by 73.45 tons. if the temperature in he havest season increases 1 celsius the yields will decease by 40.44 tons and according to the trend the yield will increase by 1.74 tons each year.

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การเตรียมและการวิเคราะห์แก้วและแก้วเซรามิกชีวภาพจากระบบแคลเซียมโซเดียมฟอสเฟต
การเตรียมและการวิเคราะห์แก้วและแก้วเซรามิกชีวภาพจากระบบแคลเซียมโซเดียมฟอสเฟต

The aim of this work was to study the magnetic properties of magnetic glassceramics with composition system CaO-Na2O-P2O5-BaO-Fe2O3. The magnetic glass– ceramics were prepared by conventional melting at 1300oC for 2 h of the coprecipitation derived starting products and heat treated at different temperatures. The structure and microstructure of the samples were characterized by X-ray diffraction energy dispersive X-ray analysis (EDXA) and scanning electron microscopy. The magnetic measurement showed that the samples which contained barium ferrite exhibited magnetic behavior which is similar to soft magnetic materials. Finally the samples were soaked in simulated body fluid (SBF) for 14 days. The apatite was found to form on the surface layer of glass-ceramics and it increases with the barium ferrite content was increased.

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ปัญหาและอุปสรรคในการปฏิบัติงานด้านการเบิกจ่ายเงินของ กรมราชองครัก
ปัญหาและอุปสรรคในการปฏิบัติงานด้านการเบิกจ่ายเงินของ กรมราชองครัก

This study was aimed to investigate problems and obstacles of 30 Royal Aide De Camp Department officers’ disbursement. The questionnaire was administered as the instrument for collecting data which were analyzed by the frequency distribution percentage distribution standard deviation t-test and One – Way ANOVA. In case of 0.05 statistical differences was found Least Significant Different method was applied to verify each pair. The results of the study revealed that most officers were males ranging between 31 to 40 years old and held bachelor’s degrees. They were responsible for the disbursement as administrative clerks with at least 15 years work experience. In terms of their opinions towards the disbursement they demonstrated in the average level. When examining each item the disbursement was still lack of notifying its processes such as paying reporting verifying informing since these are complicated orders. In addition payments were done through cash and checks; therefore executives or officers involving need to provide trainings or excursions in order to speed up the disbursement processes to obtain good understanding and problem solving skills to increase work efficiency and other necessary work experiences from other related work places.

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การประยุกต์ใช้ฟิล์มแข็งเคลือบผิวเพื่อยืดอายุพันช์เอียงในกระบวนการตัดขอบ
การประยุกต์ใช้ฟิล์มแข็งเคลือบผิวเพื่อยืดอายุพันช์เอียงในกระบวนการตัดขอบ

The objective of this research is to increase the tool life of trimming process by surface coating technology. The procedure of this research consists of two sections. In the first section the friction coefficient was investigated with the ball on disk technique by using a tribometer. Steel ball was produced from cold work tool steel grade SKD11 (JIS) hardened to 60±2 HRC. Two types of surface coating namely AlCrN and TiAlN were conducted by PVD technique. Disk material used in this experiment was made by stainless steel JIS; SUS 304 of 2 mm thickness. For the second section the wear tests of trimming die were performed by using flat punch and inclined punch 45 degrees without surface coating as well as the inclined punch 45 degrees coated with AlCrN and TiAlN (PVD). Workpiece material used for the wear test was stainless steel JIS; SUS 304 of 2 mm thickness. Additionally the finite element analysis was carried out for explanation the deformation of the workpiece during trimming operation. Although the friction coefficient of the surface coating was higher than non-coating it could be extended the tool life ostensibly. As the result of FEM the inclined punch 45 degrees could be generated the long sheared surface more than the flat punch. This is due to the internal stress of workpiece that did not connect from the punch to the die so the crack propagation would be delayed. The inclined punch 45 degrees coated TiAlN has a highly durable which can be used up to 5000 strokes.

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Flexural performance of corroded reinforced concrete beams repaired with CFRP sheets
Flexural performance of corroded reinforced concrete beams repaired with CFRP sheets

Corrosion of steel reinforcements in concrete is one of the main causes of early deterioration and reduction of service loads of reinforced concrete (RC) structures. This paper reports the results of an experimental program that was carried out to evaluate the effect of reinforcement corrosion on the flexural performance of RC beams and to investigate the efficiency of externally bonded carbon fiber reinforced polymer (CFRP) sheets to repair the corrosion-damaged RC beams. Seven RC beams with the same cross section and reinforcement details were prepared including the control beam (B0). First tension reinforcements of six RC beams were corroded by using an accelerated impress-current process to obtain corrosion levels of 15% 30% and 50% of weight loss according to Faraday’s law. Then three beams were repaired using CFRP sheets attached to the bottom surface leaving the other three unrepaired. All beams were subjected to the four-point bending load test. The experimental results show that the corrosion specimens demonstrated a significant deterioration on the structural performance and the integrity by decreasing in their ultimate load capacity stiffness and ductility. The deterioration by corrosion of tension reinforcements can be successfully overcome using CFRP sheets as the repair material. The technique can restore the beam strength to its original design strength except specimen B50F2 having severe steel-corrosion damage of 50%. A conservative value of the ultimate bending capacity of the beams with low corrosions (15%-30%) can be predicted by using RC conventional models as suggested in ACI 318. However the opposite trend is obtained for the high corrosion beam (50%). Appling ACI 440.2R provision to predict the ultimate flexural capacity of corroded beams repaired with CFRP sheets shows rather fair values for low corrosions (15%-30%) but significantly overestimates the strength of the high corrosion beam (50%).

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