Engineering Journal (Faculty of Engineering, Chulalongkorn University, Bangkok)
Not a member yet
1223 research outputs found
Sort by
Closed-form Expressions of Generalized Conforming Triangular Finite Element for Thermal Bending Analysis of Thin Plate
Get PDFThe generalized conforming triangular finite element for thermal bending analysis of thin plate caused by the temperature difference along the plate thickness is developed. The finite element formulation with detailed finite element matrices is derived based on the modified potential energy principle and the generalized compatibility conditions. The closed-form expressions of the stiffness matrix and the thermal loading which can be applied directly to the computer program are also derived and presented. The performance of the generalized conforming triangular element is evaluated by several examples of which the exact solutions are known. The results demonstrate that the generalized conforming triangular element performs very well for thermal bending analysis of thin plate
Developing an Automated System for Checking the Strut Arrangement in Deep Excavation
Get PDFAt the early stage of the project, the clash problem in the strut arrangement was reviewed by using two-dimensional construction drawings. This practice was time-consuming and error-prone. Moreover, some 3D construction software could detect clashes between the structural strut and permanent building structures. But they were still limited in this arrangement including (1) decision of strut arrangement relying on human judgment; (2) unable to distinguish between unreal clash and real clash in the strut arrangement based on work practice, and (3) unable to present overview of all clash detections from each strut at one time. To solve these problems, this paper integrated rule-based approach with Building Information Modelling (BIM) to develop an automated system for detecting and solving clashes of the structural strut. The methodology primarily developed three main modules of an automated system by using rule-based approach. Then, these modules applied with BIM software, visual programming and spreadsheet for generating, checking and solving the clashes. To proof the efficiency, a case study of office basement construction was applied to test the system. As a result, this system could improve the strut arrangement work by reducing the human judgement. Moreover, the system has shortened the time of the strut arrangement by only specifying on the real clash problems. Last, this system also could provide better visualization of clashes
Enhanced Photocatalytic Activity of C-doped TiO2 under Visible Light Irradiation: A Comparison of Corn Starch, Honey, and Polyethylene Glycol as a Carbon Sources
Get PDFTitanium dioxide (TiO2) represents an effective photocatalyst for removal of polluted water; however, it has a limitation of active under small part of ultraviolet light region from sun spectrum. Herein, reported the carbon doping TiO2 (C-doped TiO2) by using various carbon sources such as corn starch, honey, and polyethylene glycol, for improving the electronic and photocatalytic properties of TiO2. The responsed visible light photocatalysis was synthesized via the ultrasonic–assisted sol–gel method and characterized by X-ray diffraction (XRD), fourier transform infrared (FT–IR) and X-ray photoelectron (XPS) spectroscopy, field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), and UV−vis spectroscopy. The results showed that the photocatalytic C-doped anatase TiO2 nanoparticles have the narrowest band gap down to 2.71 eV with increase the carbon doping up to 2.0% by weight from corn starch as external carbon source. XPS result reveals carbon substitution of titanium positions in the anatase TiO2 structure and also to precipitate at the surface of TiO2. As compared photodegradation efficiency under ultraviolet light, observed 87 %MB maximum photoremoval in neutral aqueous solution within 1 hour reaction time under visible light irradiation. While doping with other carbon sources, C-doped anatase TiO2 showed low photocatalytic activity. Hence, great strategy of wastewater treatment application in large scale pilot plant, selected low cost of corn starch acted as an external carbon source for promoted an excellent visible light nano-anatase TiO2 photocatalytic immobilization on the modified glass supporter throughout adhesive waterproof glue
Accessibility-Based Approach: Shaping Travel Needs in Pandemic Situation for Planners’ Perspectives
Get PDFThe outbreak of acute respiratory syndrome coronavirus 2 (SARS-Cov-2) causing coronavirus disease (COVID-19) has affected travel behaviors and lifestyles in a matter of days and weeks. In transport planning process, the concept of accessibility is usually interpreted as an acronym of mobility. For decades, researchers have been advocating to interlink the mobility-based approach with accessibility-based approach. Despite considerable research work has been done for the development of accessibility measures, yet its effective use in transport planning is not very pervasive. In this research study, stress is emphasized to reflect on why significant progress for adopting accessibility-based approach has been difficult to accomplish especially in planning practices. Some of the promising efforts made so far have been highlighted. This study provides insights on the power of accessibility-based approach in urban settings and discussed why planners should adopt this approach to reshape safe travel behaviors in uncertain pandemic situations like COVID-19
Development of Novel Wind Turbines Hybridized between Permanent Magnet Disks and Additional Motor/Generator for Extending Operating Range and Enhancing Conversion Efficiency
Get PDFWe implement and evaluate a novel wind turbine setup, which consists of a conventional wind turbine and a pair of coupled disks. The disks are coupled by permanent magnets (PMs) and the distance between the coupling disk pair can be varied. The force between disks has been simulated as a function of disk distance and magnetic field strength. The strongest repulsive force is produced when the PM disks are in-line but when the PM disks are interdigitated, the coupled force is changed to attractive force and the coupling is maximized. Our testing experiment shows that when the wind speed is too low, the coupled disks can transfer angular speed to the turbine in order to maintain the turbine movement. With these added parts, we can avoid the rotational barrier from static friction when the wind speed is increased again. Without the coupled disks, the turbine will completely stop when the wind speed is too low. The static turbine needs stronger wind to start the movement again. Extension of the utilization of the turbine to the high-wind-speed situation has also been proposed. This work enhances the usage of wind turbine for producing renewable energy in low-wind-speed regions
State of The Art: Ozone Plasma Technology for Water Purification
Get PDFThe need of clean water will continue to increase along with the increase of population. However, not all regions in Indonesia have potential for raw water sources that meet standards of clean/drinking water, so an alternative water treatment needs to be developed. Peat water treatment using ozone plasma technology is one of technological breakthroughs that can treat peat water into clean water effectively and economically. Based on the results of treating peat water using ozone plasma technology, it is proven that the technology able to treat peat water very effectively compared to the conventional refining technology. Peat water used for this study is taken from Sintang, West Kalimantan. Tested Parameters of water quality will be compared with the Regulation of Minister of Health No. 416 Year of 1990. Four parameters in raw water are carried out to be tested after treating with variations in length of contact time of 10, 12, and 15 minutes. Water quality parameters to be tested are turbidity, color, coliform, and permanganate with final quality of treating for each parameter are 5,8 NTU, 1,1 Pt-Co, below 2 MPN/100 mL, and 11,8 mg/L. There is significant decrease in a value of four parameters, which three parameters meeting the maximum limit. Permanganate as parameter that exceed the maximum limit have high probability of meeting this limit if the contact time is extended. However, ozone plasma technology also has general considerations, regarding the performance of plasma-based water purification which is the plasma-liquid interface. This paper gives an overview of the state-of-the-art in ozone plasma technology for water purification, which the technology used is plasma-based
Construction Safety Management System at Project Level using System Dynamic Model (SDM)
Get PDFConstruction industry is one of the sectors that contributed to a high number of accidents. Three elements (i.e., cost, time, and quality) that measure the successful of construction project have been the main key driver, but safety and health is deemed as taboo. Hence caused several setbacks especially on the daily workers facing hazards that could happen due to negligence towards safety aspect. So, identifying the root causes of accidents is vital to prevent it from happening. Therefore, this research was conducted to improve construction safety management system at project level by using System Dynamic Model (SDM) to achieve three objectives which are: (1) to identify the common factors that cause safety accidents on the construction sites, (2) to determine the theme for the factors identified, and (3) to investigate the interactions between the themes using SDM. For this research, semi structures interview and questionnaire survey to 54 respondents from 15 construction sites around Daerah Petaling were conducted. This research revealed 18 factors of accidents and classified them into four (4) themes which used to create a System Dynamic Model that identify four key factors for each theme. On top of that, the findings proved that there are relationship and interactions between the factors. It is expected that the findings from this research may contribute to identify the most effective corrective actions that can be exploited to decrease the number of construction accidents in Malaysia
Effect of Silver Sulfadiazine and Metallic Ions on Properties of Thai Silk Fibroin/Gelatin Films for Anti-Bacterial Applications
Get PDFThis study aimed to develop Thai silk fibroin/gelatin (SF/GA) films incorporating various concentrations of silver sulfadiazine (SSD) and to investigate the effects of SSD and metallic ions (Ag(I) and Cu(II)) on chemical conformation of the SF/GA films. We found that the incorporation of SSD in the films changed the conformation of silk fibroin protein by increasing β-sheet content. The same phenomena was also observed with the other 2 metallic ions, Ag(I) and Cu(II), incorporated in the SF/GA films. This effect of metallic ions on the SF conformation transition in the SF/GA films may be similar to the phenomenon occurred during natural spinning process of the Bombyx mori silkworm. The SF/GA films incorporating SSD had therefore more stability, less water-insoluble fraction and extended degradation rate than the SF/GA films without SSD due to the higher content of stable β-sheet conformation. When cultured with L929 mouse fibroblast cells according to ISO 10993 part 5 standard, the SF/GA films incorporating SSD at all concentrations showed no cytotoxicity. The SSD released from the films also showed obvious anti-bacterial activity against Staphylococcus aureus (Gram positive) and Escherichia coli (Gram negative) bacteria. We suggested that the SF/GA films incorporating SSD may be useful for some medical applications in which anti-bacterial effect was required
Seismic Analysis of RC Frames with Brick Infill Panel Strengthened by Steel Cage and Expanded Metal
Get PDFThe seismic analysis of reinforced concrete infilled frame strengthened by using steel cage and expanded metal was investigated. The strengthening technique of steel cage consisted of steel angle, batten and expanded metal sheet was employed. The brick infill panel was strengthened with ferrocement and expanded metal. The flexible base foundation was considered by modelling the pile foundation with the lateral and the vertical spring stiffness. Eight types of frames: four existing frames and four retrofit frames were analyzed by nonlinear static analysis and nonlinear time history analysis with 20 ground motion records. It was found that the initial stiffness and the strength of the retrofit frames were significantly higher than those of the existing frames. The observed seismic damage of the retrofit frames was decreased to the specified limit. The initial stiffness of the frames with flexible foundation was lower than that of the fixed base resulting to the larger displacement and the higher seismic damage of the structures.
Determination of Material Parameters of PDMS Material Models by MATLAB
Get PDFGenerally, material constants and their corresponding stability regions of hyperelastic constitutive models can be obtained by well-known commercial software. Nonetheless, reproduction of engineering stress-strain curves from these software do not accurately represent of the uniaxial testing data of a Polydimethylsiloxane material (PDMS). This research aimed to develop PP algorithm, which are MATLAB codes, used to determinate hyperelastic material constants and their stability regions from uniaxial testing data of PDMS material. Hyperelastic constitutive models composed of Neo-Hookean; 3, 5, and 9 parameters Mooney-Rivlin; 2nd and 3rd order Yeoh; and 1st, 2nd and 3rd order Ogden. Moreover, the accuracies of our results were evaluated by the residual sum of squares (RSS) between testing data and hyperelastic models and compared with ones of ANSYS. In Neo-Hookean and Ogden models, the PP algorithm effectively determined material constants from the uniaxial testing data in which their RSS were lower than ones from ANSYS while the strain limit ranges were comparable. However, in Mooney-Rivlin and Yeoh models, the PP algorithm obtained lower RSS but had narrower strain limit ranges than ones from ANSYS. Finally, the Ogden 3rd order model is the accurate constitutive model for PDMS since it obtained not only low RSS but also no strain range limit