จำนวน Repository ( 82 )

การประเมินความเสี่ยงภัยแล้งในประเทศไทยโดยใช้ตัวแบบฮิดเด็นมาร์คอฟ
การประเมินความเสี่ยงภัยแล้งในประเทศไทยโดยใช้ตัวแบบฮิดเด็นมาร์คอฟ

The objectives of this research are to propose a proper model for risk assessment for drought in Thailand. A hidden Markov model is adopted. The results indicate that the amount of rainfall depends on the hidden states drought or non-drought state. If the state changes from drought to non-drought the amount of rain will increase. The probability of changing from drought state to non-drought state is higher than from drought state to drought state. The probability of drought occurrence in February is highest followed by in November March December January July April June October September August and May respectively. When the temperature increases the probability of drought occurrence will increase.

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Compensation of low frequency oscillation on power system using flexible ac transmission systems devices
Compensation of low frequency oscillation on power system using flexible ac transmission systems devices

This paper presents a study of low-frequency oscillations in compensated electric power systems with Flexible AC Transmission System of the power system frequency using PSAT Tool box To assist in the analysis of the stability of the system When the power transients in power systems is simulated By using standard IEEE 14 bus system as a case study. The Equipment that used to control the swing frequency of the is a flexible electrical power control devices or FACTS are two kinds of serial and parallel. The analysis showed that two models are compared with the time (Time Domain) and see the effect of the Eigen (Eigen Value) of the simulation results show work to see that controls are electrical flexible compensation. of low frequency oscillations in power systems in acceptable coordinates

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A development of management system for examination bank and test on internet
A development of management system for examination bank and test on internet

The objectives of this study are to develop a management system for examination bank and an online examination. Working procedures were performed by analysis a traditional working system and problems study of user requirements design of a new working system and a development of the new system. PHP and JAVA programming language operating with MySQL for developments and a database management were used. The new system consists of 6 systems by operating as web application. Users are 3 groups that are teachers students and administrator. In the items analysis stem a reliability value was calculated using KR-20 and KR-21 of Kuder-Richardson. The level of difficulty and discriminating power were identified using choice analysis with 27 percentages of upper and lower technique. The new system was tested with 3 groups of teachers students and administrator. The evaluation was performed using questionnaires. The results of the evaluation shown the contentment is in good level. Accuracy of the system was measured by comparison between a traditional item analysis and the new system. The comparison results were not different. However the accuracy of item analysis results depends on knowledge of the students who are in testing.

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Effect of glass cullet on compressive strength and abrasion resistance of terrazzo floor tile
Effect of glass cullet on compressive strength and abrasion resistance of terrazzo floor tile

This research was aimed to study the compressive strength and the abrasion resistance of Terrazzo floor which used glass cullet as aggregate. The mix proportion of Terrazzo was 1 : 2.5 (white cement : chipped stone) by weight. The weight percentages of replacement of chipped stone by glass cullet were 0 10 25 50 75 and 100% by weight of aggregate. The compressive strength and abrasion resistance of Terrazzo specimens were measured at 7 14 and 28 days. The results indicated that the compressive strength of mixtures with glass cullet of 0 10 25 50 75 and 100% were 581.11 540.81 534.83 480.94 435.42 and 343.71 kg/cm2 respectively. It showed that the compressive strength decreased with the increase of glass cullet content. The abrasion test of Terrazzo specimens showed that at low glass cullet content (10-50%) the abrasion resistance increased with the increase of glass cullet content. The mixtures with glass cullet of 75 and 100% have abrasion resistance nearly the same as the mixture without glass cullet

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Dispersion of copper oxide in water by pH value and ultrasonic method
Dispersion of copper oxide in water by pH value and ultrasonic method

The objective of this research is to study the dispersion of copper oxide particles in water using as a coolant in heat exchangers. Copper oxide particles were prepared by precipitate method. The parameters affected to dispersion of copper oxide were pH of solution and ultrasonic time. The results showed that an average crystalline size of copper oxide was in nano scale (< 22 nm). At pH value of 13 copper oxide was well dispersion in the water. Appropriate ultrasonic time of dispersion is dependent on particle sizes of copper oxide. The small particle sizes of copper oxide led to decreasing of ultrasonic time. On the other hand an increasing in particles sizes required longer ultrasonic time. Stability of suspension of CuO in the water decreased with an increasing of time. Moreover it was found that CuO particles were well dispersed in the water at pH value of 13 and ultrasonic time of 15 minutes

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