Rattanakosin Journal of Science and Technology

Exponential Stability of a Certain Neutral Differential Equation with Time - Varying Delays

Suphatchaya Anusornpradit — 2024-12-27

In this paper, the exponential stability conditions for neutral differential equations with time-varying delays are presented. By improving the integral inequality, Lyapunov–Krasovskii functional. And determine sufficient conditions and show a comparison of conditions.

Influence of CBR value in embankment materials on the improvement of recycled asphalt concrete pavement

Piyachat Chattonjai — 2024-12-27

Reclaimed Asphalt Pavement (RAP) is the by-product of removing old asphalt concrete pavements through milling or excavation and broadly improves the engineering properties by mixing RAP with crushed rock and cement or polymer called “pavement in-place recycling”. The cost of raw materials can be significantly decreased and the mixing process easier
if cement or polymer is neglected. A road structure typically consists of multiple layers which the California Bearing Ratio (CBR) of the soil in each layer is different. This research studies the influence of CBR value in soils to improve the engineering properties of RAP. A different type of soil especially for road embankment includes gradation and CBR mixed with RAP in several ratios by weight were compacted and the CBR values evaluated to determine the appropriate mixing proportion. Based on the test results, native soil is found to improve the strength of RAP by densification and the maximum CBR of mixed material increased due to larger amounts of CBR in the native soil. However, the maximum CBR of mixed material after the appropriate mix proportion point is constant and cannot exceed the native soil. While ARP increases the CBR, it also reduces the percent of swilling for soaked condition. The cost of raw materials
is reduced because RAP performs a rigid body filled soil mass up to increase volume. Finally, this research also presents a cost-benefit analysis in which the cost of different layers of road structure are compared.

Design of Temperature Maintaining Package for Cold Chain Logistics Management of Blood Products

Jirawan Niemsakul — 2024-12-27

Logistics management in the blood cold chain is extremely important to the quality of blood products and blood components that will be used to treat patients. The transportation and storage processes must be concerned throughout the blood cold chain. This research objective was to design and develop an innovative prototype system for maintaining the temperature of packaging boxes in the transportation process. The electronic system was developed to control and maintain the temperature inside the box within the specified temperature range under the current situation environment, long enough for transport periods, and without cooling materials. The heat transfer theory was performed and test in experiment process.

The result was an innovative prototype electronic system that controls and maintains the temperature inside the packaging box in the transportation process. The average temperature inside the box can be controlled at 9-11 degrees Celsius under an outside temperature of 25-28 degrees Celsius. The temperature can be maintained and controlled continuously with direct current electricity at 12V with duration testing of 120 hours without cooling materials.

Development of an Unloading system from the Conveyor of Automated Packaging Machine for Coconut Pudding

sermpong Niemsakul — 2024-12-27

The coconut pudding product is characterized by a soft texture easily susceptible to damage. A key issue in the packaging process of the case study company is that pudding cups frequently fall from the conveyor belt. This is because the machinery used for packaging was originally designed for filling drinking cups and was later adapted for pudding packaging. The water filling machine lacks a mechanism to lift the cups from the conveyor, as the water cups can be tipped off the end of the conveyor without incurring damage. However, this approach is unsuitable for pudding cups, which require manual worker removal. Occasionally, workers fail to remove the cups in time, causing them to fall to the floor and damage the pudding. This results in a daily product damage rate of 5%, or approximately 350 cups per day. The pudding breakages also cause production to discontinue and require an average of 30 minutes to clean the machinery. This research aims to develop an automatic system for lifting pudding cups from the conveyor using pneumatic technology, without damaging the soft pudding texture. The goal is to enhance production efficiency and reduce waste costs associated with the packaging process. The system is designed to move the pudding cups vertically and horizontally at an appropriate speed to prevent damage. The research findings indicate that the developed system successfully lifts the pudding cups continuously without generating waste. Testing with 5-ounce and 6-ounce pudding cups across 1,000 continuous lifts was demonstrated to reveal the system's efficiency. The maximum horizontal speed that does not damage the pudding is 416.67 millimeters per second, and the maximum vertical speed is 197.37 millimeters per second. This improvement increases production capacity by at least 100% and reduces waste costs by 100%

Improved Accuracy in Calculating Acceleration due to Earth’s Gravity using Taylor Series Expansion: A case study in Pendulum Oscillations

Kanokorn Khampui — 2024-12-27

This study examined the simple harmonic motion of a pendulum oscillating at five different string lengths (0.2, 0.4, 0.6, 0.8, and 1.0 meters) at four different angles (10°, 20°, 30°, and 50°). A photogate sensor was used to measure the period. A high-accuracy formula and a simple formula were then used to compute the gravitational acceleration. The results showed that the period relates to the length of the string and was comparable at oscillation angles of 10°, 20°, and 30°. However, raising the angle to 50° extended the time. It was also found that using a 0.2-meter-long thread caused the most error in gravitational acceleration estimations. Using either a simple or a high-accuracy formula to calculate gravitational acceleration results in minimal changes in error levels for angles smaller than 10°. However, when the angle was extended to 20°, 30°, and 50°, calculations utilizing a high-accuracy formula were shown to be far more precise and error-free than those using a simple formula.

Comparison of Bullet Hole between Standard Pickup Truck Tailgate and Modified Tailgate after Firing at Different Distances

Bongkot Krobbang — 2024-12-27

Tool mark examination on objects is one of the evidence collection methods in forensic science. Bullet tool mark information can be used for investigation and comparison study that link to the incident. The objective of this research is to study the pattern and differences resulting from the collision between the tailgate of a pickup truck and a bullet. The experimental research was performed by gun shooting using to the metal sheet produced as the tailgate of the pickup truck as simulated shooting events at different ranges with Glock CZ automatic pistol and 9 mm bullets, Lead Round Nose (LRN) and Jacket Hollow Point (JHP) types. Tool marks observed at the shooting distances of 3, 5, and 7 meters from standard pickup truck tailgate from the manufacturer were compared to the modified tailgate. From the results, it was found that the shape and structure of the entrance and exit holes were different under the shooting angle at 90 degrees. The entrance hole of the projectile is circular with smooth edges. In the other hand, the exit hole of the bullet is circular in shape with irregular edges and some of the surface was shown to be swollen and torn. From the statistical analysis, it was found that shooting distance did not affect the width and length of both entrance and exit holes. However, the type of bullet was found to affect the size of entrance and exit holes. Overall, observed tool marks from the shooting were significantly different. This is useful for the measurement of incident tool marks and can be applied as a database to support the gunshot tool mark analysis on surfaces in forensic examination.

Bayesian Approach for Point Estimation under Different loss functions

Nittaya Phuwong — 2024-12-27

The aim of this research is to investigate the point estimation of the Poisson parameter using a Bayesian approach with an exponential distribution as the prior. The research involves employing Bayesian inference's loss function to derive point estimates under different loss functions, namely precautionary, entropy, and general entropy. The proposed methods are then compared with the maximum likelihood method, with the mean square error (MSE) serving as the performance evaluation criterion.

The findings reveal that the maximum likelihood estimator achieves the lowest MSE values when the true parameter falls within the range of 0.5 to 1. On the other hand, the Bayesian approach under the precautionary loss function yields the smallest MSE values when the true parameter ranges from 3 to 5.

Biogas Energy Potential using Linear Regression Analysis

Nunthaporn Yingratanasuk — 2024-12-27

A mathematical model of the relationship between biogas energy potential obtained from animal waste in Thailand by simple linear regression analysis was generated from data classified by province in 2020. The study found that the biogas energy potential was related to animal waste with a correlation coefficient of 0.9966 and could predict biogas energy potential at 99% (p < 0.001) with a standard error in the forecast equal to ±0.36: the forecast equation for the relation between biogas energy potential (y) and animal waste (Xi) was y = 0.0535 + 0.00002xi. The model was verified by comparing its predictions for 2021. The obtained model will be useful in future planning policies for the use of biogas renewable energy.