Rattanakosin Journal of Science and Technology

Differential Operator and Laplace Transform for Linear Differential Equations

2023-06-13T14:53:07+07:00

The solutions of differential equations, there are many different ways to find values. In this research, Laplace transform for time and space differential operators are used to find solutions to equations. which works very well and more quickly.

Temperature effects on a mixture of recycled asphalt concrete pavement and lateral soil

2023-07-14T15:24:54+07:00

Reclaimed Asphalt Pavement (RAP), widely used by mixing with other material for road structure material or Asphalt Hot – Mix Recycling, is the reuse of old asphalt concretes that was removed by milling machines. RAP contains two elements of asphalt and aggregates that can’t be used directly for road structure work without mixing or adding with another material due to it have no ability to densify by conventional compaction technique. This research focusses on how to use RAP as a backfill material without the pavement on the top of surface which the compacted material directly receives the solar heat. The results show that the appropriate mix proportion of laterite soil and RAP improves the engineering properties of RAP in both room and ambient temperature of 60 degrees. This research also presents the method to fine the appropriate mix proportion of both material in term of engineering properties and construction cost.

Nonlinear Static Analysis of Egg-Shaped Toroidal Shells under Internal Pressure

2023-08-21T13:40:42+07:00

This paper presents a nonlinear static analysis of egg-shaped toroidal shells under internal pressure. Strain- and curvature-displacement relations are considered in the energy functional of the egg-shaped toroidal shell system in terms of the metric tensor and curvature components, and are written in terms of the appropriate form for nonlinear analysis. Lagrange multiplier’s method is introduced in the present formulation to enforce the discontinuity effect. The numerical results in terms of the meridian and normal to the meridian displacements can be obtained by nonlinear finite element method. The toroidal shell displacements from the present formulation are found to be in close agreement with the finite element commercial software results. Finally, the effects of the internal pressure, cross-sectional radii ratio, and bend-to-cross-sectional radii ratio on the numerical results in terms of toroidal shell displacements are demonstrated in this paper.

The attitudes analysis of Students towards the Activities of Students Clubs, Faculty of Science, Energy and Environment, King Mongkut’s University of Technology North Bangkok (Rayong Campus)

2023-08-28T14:15:54+07:00

The study of attitudes of students towards the activities of student clubs of the Faculty of Science, Energy and Environment, King Mongkut's University of Technology North Bangkok (Rayong Campus). This study focused on the requirements of the students and their attitudes towards the activity patterns of student clubs at the Faculty of Science, Energy and Environment, King Mongkut's University of Technology North Bangkok (Rayong Campus). Additionally, a comparison of the requirements of students and attitudes towards the activity patterns of student clubs by classifying gender and year level. The population of the group sample was 300 students, and the tool for collecting survey data for this study was a questionnaire entitled Student’s Attitudes Towards the Activities of the Students' Clubs. The data analysis statistics included mean, standard deviation, T-test, One-way ANOVA, and content analysis. In accordance with the results, students' attitudes towards the student club's activities were, with a score of 4.329, overall, of high quality. Activities that encourage environmental protection received the highest ratings, scoring 4.403. Comparing the attitudes of students towards the activities of the student clubs, it was found that male and female students had different attitudes towards the activities of the student clubs. Overall, it is not significantly different.

Design of Brake Pad Lining Tool for Heavy Truck Using Quality Function Deployment

2023-10-02T09:28:49+07:00

The purpose of this study was to apply quality function deployment (QFD) in the design of a large truck brake lining assisting device. The research began by gathering the needs of customers who were service workers of a sample company using questionnaires and interviews. The data revealed the importance of each customer need and the level of customer satisfaction on the existing method, which were subsequently fed into the four-phase QFD. The results of analysis would guide the design of prototype which was supposed to meet the needs of customer groups in terms of ease of operation, part strength, maintenance procedures, compressive strength, speed of operation, and emergency protection capabilities.

Mechanical Properties of Lightweight Concrete Mixed with Palm Ash Reinforced with Palm Bunch Fibers by Steam Curing Method.

2023-05-11T14:23:28+07:00

This research aims to study of mechanical properties of lightweight concrete. Cement is replaced with palm ash. Percentage 5, 10, 15 and 20. Replace sand with palm fiber. The percentage 0, 2, 4, 6, and 8 percent, respectively. Concrete curing 2 solutions is normal watering and steam curing at ages 3, 7, 14, 21, and 28 days. The study indicated that cement is replaced with palm ash percentage 5 and 10. This results in the highest compressive strength. The method of normal curing and steam curing. Replacement of sand with palm fiber At 2% and 4%. This results in the highest compressive strength. Pulling capacity depends on the increase of palm fiber that replaces sand in increasing ratio. The 8 percent sand replacement ratio results in the highest tensile strength. Comparison of compressive strength development from both curing. Steam curing resulted in an increase in compressive strength of 12 percent. Testing of aerated concrete according to TIS 1505-2541. All ratios are classified in 4 quality classes 0.70 and AAC-WHF. All ratios are classified in 4 quality classes 0.70 and AAC-WHF. Attribute is the material of green building and lightweight concrete type a structure.

Developing a composite Molding of a prototype electric vehicle wheel in competition using an autoclave system

2023-07-26T14:04:14+07:00

This research is about developing a process for forming composite parts using an autoclave system. In this research, a prototype electric vehicle wheel was designed and formed using synthetic materials. Polyester resin (Polyester Resin), Polyurethane foam (PU Foam) and reinforced with carbon fiber fabric (Carbon Fiber) for the prototype energy-saving electric vehicle competition with the autoclave system. Using theories about air pressure, heat, and material strength. To make the carbon fiber wheel pieces come out according to the specified shape of the wheel and the wheel balance center to meet competition standards. In this research, three electric vehicle wheels were created by setting the pressure value for baking the workpiece when the first wheel was pressurized at +2 bar (15 psi), and the second wheel was pressurized at +1 bar (30 psi). and the third wheel is not pressurized. The research results were analyzed and divided into two topics: efficiency analysis and economic analysis. The research results can be summarized as follows. The performance of unpressurized carbon fiber wheels is that they explode when compressed with air at 65 psi, while pressurized wheels can be compressed at 75 psi. The economic analysis found that the process of forming composite parts with the autoclave system has a payback period of 2 months and ten days.

Soil Shrinkage and Swell Behavior due to Change in Soil Moisture

2023-06-15T09:40:36+07:00

This research is to study the behavior of changes in soil moisture which relate to landslides in hillside slopes. The purpose of this study is to study the behavior of soil shrinkage and expansion due to changes in soil moisture. The soil sample used was large to reduce the influence of lateral forces. In the test, the reduction and increase humidity and checking the changing humidity and water absorption force Dehumidification methods are carried out in two methods, one is oven drying and another is leave it at room temperature.

The results of the study showed that when the moisture in the soil decreased, soil shrinks rapidly until to 20% moisture content, after that the shrinkage rate slows down. During this process, cracks appear on the sample. When adding moisture, the soil was swell and cracks disappear. When considering the water suction force in the soil, it was found that the suction force is related to the moisture content in the soil. At high moisture content, the soil suction is less than at lower moisture content. However, because measuring the sample volume change did not measure crack size, the void ratio calculations were higher.

In addition, the formation of cracks may reduce the soil suction as cracked soils tend to contract more easily as they are not bound by the surrounding soil mass