Conference Publications
Permanent URI for this collection
Browse
Recent Submissions
1 - 5 of 80
-
PublicationEffects of physical and mechanical properties of soft soil on subgrades performances in Lubuk Bayas village, Serdang Bedagai Regency(IOP Publishing, 2023)Generally, the existence of soft soil in Indonesia will be a problem in the construction of highway construction. One factor that influences and needs to be known in road construction is the characteristics of the subgrade where the pavement construction will be placed on it. Poor soil characteristics can cause bumpy road surfaces, cracks, or other road damage. Therefore, before carrying out a soil improvement, it is necessary to know its characteristics through the physical and mechanical properties of the subgrade. This research was conducted in Lubuk Bayas Village, Serdang Bedagai Regency, North Sumatra Province. Tests of physical properties in this study include sieve analysis, water content, specific gravity, plasticity limit test, and liquid limit test. The soil shear strength test and California Bearing Ratio (CBR) test were carried out to test the mechanical properties using a Dynamic Cone Penetrometer (DCP). From the results of testing the physical properties of the soil, it was found that Samples 1, 2, and 3 were fine-grained soils with the percentage of soil passing the No.200 sieve greater than 50%. The USCS classification system shows that samples 1 and 2 of the soil are in the Lean Clay (CL) group, while sample 3 is in the Fat Clay (CH) group. Samples 1, 2, and 3 include soils with high plasticity because the PI value is >17. The results of testing the mechanical properties of the soil Sample 1 obtained the value of c = 0.1299 kg/cm2 and Ø = 13.2°, in Sample 2 obtained the value of c = 0.1075 kg/cm2 and the value of Ø = 11.2° and in Sample 3 obtained the value of c = 0.1275 kg/cm2 and the value of Ø = 11.9°. DCP testing on samples 1, 2 and 3 obtained CBR values of 5.35%, 4.73% and 3.15%. From the CBR results, it can be seen that the soil in this location has a low soil bearing capacity, so if it is to be used as a subgrade layer, it will be necessary to repair the soil first so that structural damage does not occur in the future. Soil improvement can be made by stabilizing the soil using natural materials to maintain environmental sustainability. Natural materials that can be used include sand with certain gradations, stone ash, palm shell ash, and various other natural materials
-
PublicationRemoval of Chromium (VI) in aqueous solution by charcoal adsorbent derived PET plastic waste(IOP Publishing, 2023)This study was conducted to assess the potential of charcoal and activated charcoal derived Polyethylene Terephthalate (PET) as adsorbent through the experiment of chromium hexavalent [Cr (VI)] removal from aqueous solution. The study aims to investigate the optimum adsorption conditions for Cr (VI) removal in aqueous solution under diverse adsorption operating conditions, namely pH, contact time, agitation speed, adsorbent dosage, and initial concentration. The diameter of the charcoal produced was 600 μm. The results showed that 80 % and 90 % of Cr (VI) removal were achieved by using charcoal and activated charcoal, respectively, at pH 5, 150 rpm, 60 min of contact time, 0.5 g of adsorbent dosage, and 0.1 mg/L of Cr (VI) initial concentration. The removal of Cr (VI) was mainly affected by adsorption operating conditions and the physicochemical properties of adsorbents. Langmuir and Freundlich adsorption isotherms were applied to model the adsorption behaviour and determine the adsorption capacity of both PET charcoal adsorbents. The adsorption isotherm plot was well fitted with the Langmuir model.
-
PublicationA review on enhancement of oil palm solid waste through torrefaction(Springer, 2023-09)Biomass is one of the renewable energy sources and is easily obtained in Malaysia. Due to the substantial amount of biomass waste generated by agricultural activities, Malaysia actually has great potential for biomass power generation. The oil palm industry is the largest contributor to biomass waste in Malaysia, particularly oil palm solid waste. The raw oil palm solid waste produced low-quality products during thermochemical conversion. Thus, the torrefaction process is one of the approaches to improve the characteristics of raw oil palm solid waste. Therefore, the objectives of this study are to review the production and characteristics of solid biofuel from oil palm solid waste via the torrefaction process. Torrefaction is a thermal conversion method of biomass in the low-temperature range of 200–300 °C. Different reaction conditions such as temperature and reaction time lead to several characteristics of biofuel products. The solid fuel of pretreated oil palm solid waste has enhanced overall quality and its characteristics after torrefaction.
-
PublicationComparative analysis of machine learning techniques for SO₂ prediction modelling(IOP Publishing, 2023)Sulphur dioxide (SO₂) is produced both naturally and by human activity. The primary natural resource is derived from volcanoes. The burning of fossil fuels is the primary anthropogenic source (especially coal and diesel). Therefore, a reliable and accurate predicting method is essential for an early warning system for SO₂ atmospheric concentration. There are still limited studies in Malaysia that use machine learning methods to predict SO₂ concentrations. With the aid of machine learning, this study seeks to develop and predict future SO₂ concentrations for the next day using the maximum daily data from Klang, Selangor. RapidMiner Studio is the data mining tool used for this research work. Based on the results, it showed that the SVM model was the best guide to be used compared with the other five models (GLM, DL, DT, GBT, and RF). The performance indicators showed that the SVM model was adequate for the next day's prediction (R2 = 0.77, SE = 8.26, REL = 18.69%, AE = 1.46, and RMSE = 2.82). The developed model in this research can be used by Malaysian authorities as a public health protection measure to give Malaysians an early warning about the problem of air pollution. The goal of predictive modelling is to make a reasonable prediction of the variable of interest, and frequently, to determine how much the independent variable contributed to the dependent variable. The results also showed that the previous SO₂ concentrations were one of the most influential parameters used to predict the future SO₂ concentrations.
-
PublicationPredicting Particulate Matter (PM₁₀) during High Particulate Event (HPE) using Quantile Regression in Klang Valley, Malaysia(IOP Publishing, 2023)Particulate matter (PM₁₀) is the key indicator of air quality index (API) during high particulate event (HPE). The presence of PM₁₀ is believed to have an adverse effect on human health and environment. Therefore, the prediction of future PM₁₀ concentration is very important because it can aid the local authorities to implement precautionary actions to limit the impact of air pollution. This study aims to compare the performances of two predictive models, which include Multiple Linear Regression (MLR) and Quantile Regression (QR) in predicting the next-day PM10 concentration during HPE. The hourly dataset of PM₁₀ concentration with other trace gases and weather parameters at Kelang and Petaling Jaya from the year of historic haze event in Malaysia (1997, 2005, 2013 and 2015) were obtained from Department of Environment (DOE) Malaysia. Three performance measures namely Mean Absolute Error (MAE), Normalised Absolute Error (NAE) and Root Mean Squared Error (RMSE) were calculated to evaluate the performances of the predictive models. From the results, QR model at quantile 0.3 and 0.6 was chosen as the best predictive tools for predicting the next day PM₁₀ concentration during haze event in Kelang and Petaling Jaya, respectively. showed better performance for the prediction of next-day PM₁₀ concentration in Kelang. These results indicate that QR can be used as one of predictive tool to forecast air pollution concentration especially during unusual condition of air quality.