The aim of this research was to develop and apply a statistical model that can be used to forecast long-term daily maximum particulate matter with a diameter of less than 2.5 microns (PM2.5) concentrations. In order to predict the daily maximum PM2.5 concentrations in the northeastern region of Thailand, the extreme value theory was analyzed, and an appropriate distribution model was identified by employing the Generalized Pareto distribution (GPD). The data of daily maximum PM2.5 concentrations during the years 2021–2023 obtained from six stations was used. These stations are located in Khon Kaen, Loei, Nakhon Ratchasima, Nong Khai, Nakhon Phanom, and Ubon Ratchathani provinces. The results of this study reveal that the GPD is appropriate based on the results of Kolmogorov-Smirnov Statistics Test. Estimating the return levels during the following return periods: 2 years, 5 years, 10 years, 25 years, 50 years, and 100 years showed that the area in the upper northeastern region, particularly Loei and Nakhon Phanom, has daily maximum PM2.5 concentrations above 500 micrograms per cubic meter. These results can also be used as information to support decision-making when conducting response planning in high-risk areas, which can be helpful for efficient resource planning and prevention actions. Doi: 10.28991/ESJ-2024-08-05-024 Full Text: PDF

This study deals with two approaches—viz. via Box-Jenkins and artificial neuron network to forecast the unemployment rate in Thailand. The Box-Jenkins approach proves more efficient to estimate the unemployment rate in Thailand, with less MAPE compared to the second model. The forecast values are consistent with the actual values and tend to decrease.

In this paper, we study the estimators of the population total in adaptive cluster sampling by using the information of the auxiliary variable. The numerical examples showed that the ratio estimator in adaptive cluster sampling without replacement of networks is more efficient than the ratio estimators in adaptive cluster sampling without replacement of units.

This research aims to develop a model for forecasting daily maximum rainfall caused by tropical cyclones over Northeastern Thailand during August and September 2022 and 2023. In the past, the ARIMA or ARIMAX method to forecast rainfall was used in research. It is a short-term rainfall prediction. In this research, the Grey Theory was applied as it is an approach that manages limited and discrete data for long-term forecasting. The Grey Theory has never been used to forecast rainfall that is affected by tropical cyclones in Northeastern Thailand. The Grey model GM(1,1) was analyzed with the highest daily cumulative rainfall data during the August and September tropical cyclones of the years 2018–2021, from the weather stations in Northeastern Thailand in 17 provinces. The results showed that in August 2022 and 2023, only Nong Bua Lamphu province had a highest daily rainfall forecast of over 100 mm, while the other provinces had values of less than 70 mm. For September 2022 and 2023, there were five provinces with the highest daily rainfall forecast of over 100 mm. The average of mean absolute percentage error (MAPE) of the maximum rainfall forecast model in August and September is approximately 20 percent; therefore, the model can be applied in real scenarios. Doi: 10.28991/CEJ-2022-08-08-02 Full Text: PDF

The objective of this research was to develop a mathematical and statistical model for long-term prediction. The Extreme Value Theory (EVT) was applied to analyze the appropriate distribution model by using the peak-over-threshold approach with Generalized Pareto Distribution (GPD) to predict daily extreme precipitation and extreme temperatures in eight provinces located in the upper northeastern region of Thailand. Generally, each province has only 1–2 meteorological stations, so spatial analysis cannot be performed comprehensively. Therefore, the reanalysis data were obtained from the NOAA Physical Sciences Laboratory. The precipitation data were used for spatial analysis at the level of 25 square kilometers, which comprises 71 grid points, whereas the temperature data were used for spatial analysis at the level of 50 square kilometers, which includes 19 grid points. According to the analysis results, GPD was appropriate for the goodness of fit test with Kolmogorov-Smirnov Statistics (KS Test) according to the estimation for the return level in the annual return periods of 2 years, 5 years, 10 years, 25 years, 50 years, and 100 years, indicating the areas with daily extreme precipitation and extreme temperatures. The analysis results would be useful for supplementing decision-making in planning to cope with risk areas as well as in effective planning for resources and prevention. Doi: 10.28991/CEJ-2023-09-07-014 Full Text: PDF

Background: Polysaccharides from the medicinal mushroom Phellinus rimosus (Berk.) Pilát (PR) are the major functional bioactive ingredients. However, there has been a marked natural decrease in the number of PR fruit bodies, leading to their increased cost. Moreover, the natural growth and development of mature PR fruit bodies takes several decades. Objective: The objective of this study was to produce a polysaccharide extract from cultured PR mycelia (PEPRM) by using ultrasonic-assisted extraction with response surface methodology (RSM), and determine its physicochemical composition and antioxidant potential. Methods: Polysaccharide and monosaccharide composition analyses were carried out by Fouriertransform infrared spectroscopy (FT-IR) and High-performance liquid chromatography (HPLC). Total contents of polysaccharides, beta-glucans, phenolic compounds, and flavonoids were investigated utilizing the phenol-sulfuric acid method, enzymatic-based commercial test kit, Folin-Ciocalteu method, and aluminium chloride colorimetric method, respectively. Antioxidant activity was determined by using 2,2-diphenyl-1-picrylhydrazyl-hydrate (DPPH) radical scavenging assay and 2,2- azino-bis (3-ethylbenzothiazol-6-sulfonic acid) (ABTS) radical cation decolorization assay. Results: Optimal conditions for the production of PEPRM included a ratio of 51.29 mL water to 1 g PR mycelia and an extraction time of 46.23 minutes, resulting in a total polysaccharide content of 577.5 mg/g of PEPRM. FT-IR spectra of PEPRM showed two broad bands at 3272.08 cm-1 and 2924.8 cm-1 in the carbohydrate region and the peaks at 1078.44, 1019.05, and 853.0 cm-1 indicated the presence of the pyranose ring skeleton, glycosidic linkage, and glucans. PEPRM had molar ratios of glucose: mannose: rhamnose: fucose, i.e., 21.86: 1.00: 2.08: 3.40, respectively. PEPRM had total contents of beta-glucans, phenolic compounds, and flavonoids as percentages of dry weight, i.e., 21.22, 2.51, and 5.71, respectively. PEPRM showed better inhibitory activity against ABTS radicals than DPPH radicals. result: Optimal conditions for the production of PEPRM were a ratio of 51.29 ml water to 1 g PR mycelia and extraction time of 46.23 min, yielding a total polysaccharide content of 577.5 mg/g of PEPRM. FT-IR spectra of PEPRM showed two broad bands at 3272.08 cm-1 and 2924.8 cm-1 in the carbohydrate region and the peaks at 1078.44, 1019.05, and 853.0 cm-1 indicated the presence of the pyranose ring skeleton, glycosidic linkage, and glucans. PEPRM had molar ratios of glucose: mannose: rhamnose: fucose, i.e., 21.86: 1.00: 2.08: 3.40, respectively. PEPRM had total contents of beta-glucan, phenolic compounds, and flavonoids as percentages of dry weight, i.e., 21.22, 2.51, and 5.71, respectively. PEPRM showed better inhibitory activity against ABTS radicals than DPPH radicals. Conclusion: This is the first finding to reveal that ultrasonic-assisted extraction with RSM was an environmentally friendly alternative to produce antioxidant polysaccharides from cultured PR mycelia. conclusion: This is the first finding to reveal that ultrasonic-assisted extraction with RSM was an environmentally friendly alternative to produce antioxidant polysaccharides from cultured PR mycelia.