Engineering Journal (Faculty of Engineering, Chulalongkorn University, Bangkok)
Not a member yet
1223 research outputs found
Sort by
Effect of Water Level Fluctuation on Riverbank Stability at the Estuary Area of Muaro Kualo Segment, Muara Bangkahulu River in Bengkulu, Indonesia
Get PDFThe paper presents an investigation of riverbank stability at the estuary area of Muaro Kualo Segment, Muara Bangkahulu River in Bengkulu, Indonesia. This area had experienced slope failures along the riverbank during the Bengkulu flood in 2019. This study is initiated by conducting a geotechnical survey to observe site condition. During the survey, slope geometry measurement and soil sampling are performed. The laboratory tests are performed to collect physical and engineering soils properties. The rainfall intensity during period of 2011-2020 is also collected to observe normal and critical river water level. The finite element method is employed to analyse the slope stability analysis under the normal and critical river water level conditions. The results showed that the slope failure is generally initiated at the slope toe. Because of the river water level, factor of safety of slope along the estuary is less than the minimum criteria for the stable slope. It indicates that slope failure is very possible to occur. Implementation of sheet pile is conducted to reduce the slope failure potential. The results showed that the use of sheet pile is relevant to improve slope stability in the study area
Sustainability of Concrete as A Civil Engineering Material
Get PDFWith increasing concern about the environment, energy consumption, climate change, and depletion of natural resources, the importance of sustainability has become mainstream among engineering and scientific communities. Concrete infrastructure is superbly durable and comes with a myriad of benefits. Yet, the production of concrete is energy intensive and represents a substantial portion of air pollution. Largely due to cement manufacturing, concrete represents 7% of greenhouse gas emissions globally and 1% in the United States. Focusing on sector-specific emissions in the United States., this paper outlines the environmental concerns of concrete production and discusses the forefront of research in reducing these effects including innovations in cement manufacturing, alternative clinker technologies, and carbon capture use and storage. Also discussed are various approaches and efforts in concrete recycling and incorporation of industrial wastes and supplementary cementitious materials into concrete. Finally, this study reviews the role of civil engineering design at various scales in the sustainability of concrete infrastructure
Geometry Optimization of PV/T-TEG Collector under Different Operating Conditions Using CFD Simulation and Taguchi Method
Get PDFPV panel connected within both fins and TEG that is well known as a PV/T-TEG system. The system increases the electrical efficiency affected by the thermal collector and contributes to additional electricity due to the temperature difference of the TEG sides. However, optimizing the thermal performance of the system involved the geometry parameters and operating conditions, it still requires many combinations of factors and levels. In the present study, Taguchi Method with five factors, three levels, and two responses is then implemented to reduce the number of combinations which are related to fin geometry, air mass flow rate and solar irradiation under different operating conditions. Air as a working fluid is applied with the inlet fluid temperature based on the tropical climate in Indonesia. The two responses are needed to be lower in temperature of the PV panel and higher in temperature difference of TEG sides respectively. Furthermore, Computational Fluid Dynamics (CFD) method is applied as an approach to generate the responses numerically. The results revealed that the combinations of the geometric parameters and operating conditions for achieving the optimal PV temperature are found to be the full fin arrangement, fin height of 75 mm, fin thickness of 3 mm, and air mass flow of 0.08 kg/s and heat absorbed of 400 W/m2. Thus, the combinations to obtain the optimal TEG temperature difference are staggered fin arrangement, fin height of 25 mm, fin thickness of 1 mm, the mass flow of 0.08 kg/s and heat absorbed of 800 W/m2. Additionally, the heat absorbed factor has the biggest impact on PV temperature change with the contribution of 47.57% of the total five factors. Meanwhile, fin arrangement is the factor that has the biggest impact on the temperature difference of TEG sides with a contribution of 33.31%
Site-Specific Analysis to Investigate Response and Liquefaction Potential during the Megathrust Earthquake at Banten Province Indonesia
Get PDFThe megathrust earthquake affiliated with several activities in the Java subduction zone is predicted to be the main trigger of the earthquake in Indonesia which is located in the world ring of fire. Therefore, this study aims to determine the seismic soil response and investigate the seismic liquefaction potential in the specific area in Banten Province. A computational simulation was performed to analyze soil response and earthquake data from Pacific Earthquake Engineering Research (PEER) database were adjusted based on the attenuation model. The results show that the site passes through amplification up to two times and the peak of spectral acceleration occurs at a low-medium period, namely 0.3 seconds. This indicated that the resonance effect can occur in buildings with up to 3 floors. Furthermore, the site dominated by sandy soil has the potential to undergo liquefaction, especially once peak ground acceleration reaches 0.1g. This investigation shows significant progressive results for understanding and practice related to the assessment of seismic site response and preliminary soil liquefaction study
Development of Drums for an Axial Flow Maize Shelling Unit
Get PDFShelling drums have an important effect on the performance of machinery used in maize harvesting. This study was aimed to develop axial flow drums for a maize shelling unit. They were 900 mm long and 300 mm in diameter. Comparative maize shelling experiments were carried out with peg-toothed (A), peg-rasp bar-toothed (B), peg-rectangular-toothed (C), and disc peg (D) drums with four levels of concave clearance (CC), 15, 20, 25, and 30 mm and three rotor speeds (RS), 6, 10, and 14 m/s. The results showed that the CC had a significant effect on the shelling efficiency (SE) and total losses (TL), while grain breakage (GB) was not significant. Furthermore, no interaction was found between the power requirements (P) and the specific energy consumption (SEC), the SE, and the GB. However, interaction between TL, P, and SEC was found with various drum types and the CC. The RS was found to have a significant effect on the SE, TL, GB, P, and SEC with different drum types. Moreover, the interaction between the drum types and the RS affected shelling at the α=0.05 level. Furthermore, it was found that the Type D drum had higher performance in shelling maize
Sappan Natural Dyed Biocomposites from Poly(Lactic Acid) and Aluminum Silicate Synthesized via Sol-Gel Method from Rice Husk Ash
Get PDFPrecipitated silica synthesized via the sol-gel method from rice husk ash was used as the solid support for Sappan dye, extracted from natural Sappan heartwood. The precipitated silica was transformed into aluminium silicate in order to fix the natural dye onto the solid support for better high-temperature resistance during polymer melt compounding. The novel synthesized natural dye pigments were mixed into poly(lactic acid) (PLA) via the melt compounding using a pigment loading of 5 wt% and injection molded into specimens. Three types of compatibilizers as tetraethyl orthosilicate (TEOS), g-glycidyloxypropyltrimethoxysilane (GPTMS) and g-aminopropyltriethoxysilane (APTES) have been studied on the effect on different color shade and the improvement of compatibility by better interfacial adhesion between PLA and the pigments. Based on FTIR spectra, natural dye adsorption onto aluminium silicate was illustrated. It was found that the Sappan (red color) dyed pigments treated with GPTMS had the highest tensile modulus, while those treated with APTES provided the brightest color of the biocomposites. Thermal resistant of the biocomposites were improved when compared with pure PLA due to presence of silica
Terrestrial Laser Scanners Datum Transformation: Insignificant Analysis of Scale Factor
Get PDFDue to the measurement mechanism employed by terrestrial laser scanners (TLSs), the pre-processing procedure has become crucial procedure to orient all acquired data into global or ground coordinate system. Rather than utilising all seven-transformation parameters, most of TLS practitioners have neglected the scale factor. Taking into account the uncertainties in deriving range data, neglecting the scale factor in datum transformation computation could jeopardise the quality of pre-processed results. To rigorously examine this argument, two experiments have been designed by considering the element of multi distances and multi sensors. Utilising phase (i.e. Faro Focus 3D) and pulse-based (i.e. Leica ScanStation C10) scanners, both experiments were carried out with computation of seven (7) transformation parameters and scale factors were extracted for the assessment. With the aid of statistical analysis, the computed scale factors were mathematically differentiate to the ideal value (i.e. 1.000 or no scale effect). Under 95% confidence level, the null hypotheses for both experiments have indicate an agreement that scale factor can be neglected in datum transformation process for both types of terrestrial laser scanners
Strength and Equivalent Modulus of Cement Stabilized Lateritic with Partial Replacement by Fly Ash and Rice Husk Ash
Get PDFThe effect of industrial/agricultural waste materials including fly ash (FA) and rice husk ash (RHA) as Portland cement replacement on properties of stabilized lateritic soil as a road construction material is investigated. The compacted lateritic soil samples treated with Portland cement at 1%, 2% and 3% by weight of the dry soil and three different amounts (10%, 20% and 30%) of FA and RHA for replacing cement are prepared and the unconfined compression and cyclic loading tests are conducted on 28 days curing samples. The equivalent modulus (Eeq) defined as the average linear portion from the unloading/reloading cycles, is used to quantify the effects of stress level on the cyclic resistance of the treated lateritic. Based on the compressive strength results, both replacement materials have demonstrated potential applications in lateritic soil stabilization. Overall, the RHA shows a better efficiency than FA for replacement particularly at 2% cement content. Based on cyclic loading tests, the Eeq values increase as the stress level increases for all samples. The FA and RHA notably enhance the Eeq values of cement treated lateritic
Vehicle Axle Load Identification Using Extracted Bridge Influence Line via Updated Static Component Technique
Get PDFBridge weigh-in-motion or moving force identification systems have been developed to screen the heavy truck or monitor its gross weight and axle loads. Bridge surface roughness has been considered a very sensitive parameter to the identification error. This paper presents the algorithm to accurately identify static axle weights by modifying the identification process to include the measured bridge influence line containing the actual road profile. The existing iterative calculation called the updated static component (USC) technique is also utilized to improve the dynamic axle load accuracy. The extracted influence line is obtained from a low-speed test using a known axle weight truck. Therefore, the characteristics of the road roughness and the measurement noise are included in the bridge responses. The effectiveness of the proposed technique is investigated through the numerical simulation and the experiment using scaled models. The results reveal that the identified axle loads become more accurate than those identified using the USC and the conventional regularized least squares methods. The proposed technique effectively decreases the identification errors of moving axle loads on the rough surface with a high measurement noise level. Moreover, the regularization parameter can be easily assigned with a broader range to achieve accurate identification results
Biopolymer Test Kit for Colorimetric Detection of Chlorine in Water
Get PDFThe objective of the study was to fabricate the colorimetric sensor of biodegradable material for free chlorine determination. The colorimetric reagent of N,N-diethyl-p-phenylenediamine sulfate (DPD) was entrapped in the hybrid biopolymer film of agar (AG) and tapioca starch (TAS) and it was coated on the plastic micro-PCR tube. The pink product obtained from the reaction between DPD reagent and chlorine could indicate the presence of residual chlorine in the water. The condition for the sensor film synthesis was optimized by the digital image analytical technique with mobile phone application. The results were showed that Red-Green-Blue (RGB) intensity of reaction product was not changed, even through the DPD reagent was added over 0.2 g/mL. The addition of 16 g/L EDTA in the buffer solution could reduce the interference effect from some metals, especially Fe3+, contaminated in water sample. The water pH could be maintained for best analysis at the volume ratio between buffer and DPD solution of 0.5:1. The incubation of colorimetric film at 60 °C and 60 minutes provided the best sensor performance with fast analysis of 1 min reaction time. In conjunction with the digital image colorimetry (DIC), the developed test kit did not provided only the qualitative information, but the rapid quantitative analysis could be also fulfilled. A wide linear range of 0.3 to 15 mg/L chlorine concentration with good linearity (R2 > 0.99) was achieved by this coupled technique. The application of biopolymer film to various kind of real water samples showed the good performances, which were comparable with the standard spectrophotometry (no significantly different results at 95% confidence level). These could promote the use of biopolymer test kit as the environmentally-friendly analytical method for chlorine in water