Engineering Journal (Faculty of Engineering, Chulalongkorn University, Bangkok)
Not a member yet
1223 research outputs found
Sort by
Evaluation of The Effect of Abscissa Part on Seismic Response of Historical Masonry Church
Get PDFChurch buildings, which are the worship buildings of the Christian faith, were built in different plan typologies in different regions. There are many church structures built in Anatolia during the Ottoman Period. During the population exchange period in 1924, Muslims settled in the settlement areas instead of the non-Muslim community in Anatolia. In this period, church buildings were converted into mosque structures due to the change in the religious belief of the people. These structures, which are used by cultures belonging to and which are components of urban identity, have gained a place in the memory of the citizens. For this reason, it is necessary to ensure sustainability by protecting it. Churches have been destroyed either completely or locally due to earthquakes that have occurred over time. In this study, it is aimed to examine the earthquake behavior of the structure used as the Maden Mosque in Amasya. The effects and causes of this structural element on the dynamic behavior of the church, whose apse was destroyed, were investigated and reinforcement suggestions were presented accordingly. The 3D finite element model of the church has been developed, and structural responses were investigated under linear and nonlinear dynamic loads. As a result of the analyses, it has been determined that the most critical parts of the structure are the nave and wall at the west facade
Current Condition of the Japanese Construction Market, Contract Management, and Construction Management Education in Three ASEAN Universities
Get PDFThis paper reports on a basic study on the current condition of the Japanese construction market, the third largest market in the world, and contract management in Japan. It also deals with the current condition of construction management education, which is the basis for contract management in Japan and three ASEAN countries namely, Indonesia, Singapore, and Thailand. The Japanese construction market is introduced in terms of its scale and overseas expansion of leading Japanese construction companies. The characteristics of the Japanese construction market and a survey on Japanese construction management education are introduced. The curriculums of construction management education in three ASEAN universities are surveyed. Finally, by comparing the three ASEAN universities and Japan horizontally and internationally, the current condition of construction management education in civil engineering is obtained. The outcome deepens understanding of access to each construction market and can be the first step toward construction business collaboration between Japanese and some ASEAN countries
Enhancement of Photoluminescence Collection from Diamond-Based Quantum Emitter with Diamond Photonic Nanopillar
Get PDFThis work aimed to examine the effects of photonic diamond nanopillar toward enhancing the collection efficiency of photoluminescence signal from quantum emitters in diamond. In this work, the finite element methods were used as a platform to characterize the emission pattern and the collection efficiency. The collection efficiency value was then characterize based on various variables, including pillar diameters, dipole orientation, emission wavelength, and emitter placement inside the photonic structure. From the simulations, the collection efficiency from an optimized nanopillar structure can be improved up to three times the bulk value, particularly in pillar diameters ranging from 70-100nm. Furthermore, the multivariable dependency studies provide valuable insight into the design and engineering tolerance of future practical quantum-based devices
Weiner Model Drop Test Identification of a Light Amphibious Airplane
Get PDFThe new approach of the Weiner model for identifying drop test dynamics of a light amphibious airplane is presented in this paper. Unlike the traditional identification method of the Hammerstein model using LS-SVM with Gaussian radial basis serving as the kernel function, the small-signal excitation input is used to estimate the linear block of the Weiner model. Then, the static nonlinearity function of the model is identified through LS-SVM. The RMSE of the proposed Weiner model is 0.48805 and 0.38246 for the strut and wheel of the landing gear. The proposed Weiner model has better identification performance than the Hammerstein model and the traditional governing equation of the landing gear. The drop experiment of the light amphibious airplane is carried out not only to prove standard airworthiness compliance but also to verify the identifiability, accuracy, and performance of system identification
Lateral Loading Test of Reinforced Concrete Bored Pile in Stiff Clay and Near Slope
Get PDFStaff residence of University of Phayao has been constructed near slope. The inhabitants in the residence are concerned about the lateral strength of the pile foundation during earthquake. This paper involves the evaluation of reinforced concrete bored piles of the residence under lateral loading. In field experiment, two full-scale bored piles were built near the slope of 1:1.5 adjacent to the residence. Two lateral load patterns that push the piles in and out were applied at the pile head. The maximum value of the lateral force was 65 kN representing the base shear force due to earthquake in Thailand. The test results show that the lateral displacements of the pile do not exceed 3 mm and stress in the longitudinal reinforcement is below the yield point. It is implied that the bored piles of staff residence can resist the lateral load imposed on the structure during an earthquake. For the analysis, the pile is modeled using frame elements and the surrounding soil is assigned by horizontal springs. The stiffness of springs is validated by comparing to the test results of the previous researches and this study. It is found that using the proper soil spring stiffness and flexural rigidity values in the structural pile analysis can capture elastic responses including the lateral displacement, bending moment and depth of inflection point
Effect of Filler Metals on Creep Properties of 2.25Cr-1Mo Steel Weld Joints Prepared by GTAW Process
Get PDFThis research aims at comparing creep properties at elevated temperatures obtained on welding 2.25Cr-1Mo steel using gas tungsten arc welding (GTAW) with ER90S-G and ERNiCrMo-3 filler metals. The high temperature accelerated creep rupture test of 2.25Cr-1Mo welded samples was investigated over 139 to 315 MPa stress range at temperatures of 550 °C, 600 °C, and 650 °C. The samples were preheated at 250 °C for 0.5 hours and post-weld heat-treated at 690 °C for 1 hour. The results showed that the accelerated creep rupture lives of lower applied stress specimens were much longer than those of higher applied stress, when both welded materials were tested under same temperature conditions. The service lifetime of the welded materials can be predicted using the extrapolation of the Larson-Miller parameter. Creep surface fractures were investigated using SEM fractography that indicated the weldment fracture modes consisted of dimple ruptures and micro-voids coalescence in the fibrous matrix of the intercritical region of HAZ. Similar high-temperature creeps service lives were found in both welded materials
Effect of SiO2 Addition in Pack Aluminizing Mixture on Phase Evolution of Si-Modified Intermetallic Layers on IN800HT Alloys
Get PDFEffect of SiO2 addition on aluminides formation in a single-step high-activity pack aluminization on Incoloy 800HT is studied. SiO2 powder was added into pack aluminizing mixture at different theoretical ratios of the reduced Si and the remained Al, i.e. Si/(Si+Al), in range of 0-37.5 at.%. Aluminization was carried out at 1,000°C for 4 h. Microstructures, chemical compositions and phase evolution of the coatings were examined using scanning electron microscope (SEM), energy dispersive spectroscope (EDS) and X-ray diffractometer (XRD). For the undoped condition, the coatings showed three layers: (i) an outer layer as a mixture of various Al-rich intermetallics, (ii) a hyperstoichiometric β-(Fe,Ni)Al middle layer and (iii) an interdiffusion zone; it implies the formation is governed by Al inward diffusion. Although aluminides of the Si-doped specimens still showed three-layers structure, low Al content intermetallic prevailed in the outer layer while a thickness significantly decreased with higher SiO2 content. Silicon was found either as the dissolved Si in aluminide coatings and Si segregation at the interdiffusion layer or as separated domains in β-(Fe,Ni)Al layer with restricted concentration. The results emphasize a possibility of Al-Si co-deposited single-step aluminization using SiO2 as silicon source along with a reduction in the thermodynamic diffusing Al activity
In-Building Capacity Enhancement using Small Cells in Mobile Networks: An Overview
Get PDFIn this paper, we give an overview of the state-of-the-art research studies to present the potential of small cells to address the high capacity demands of in-building users in mobile networks. In doing so, we discuss relevant theoretical backgrounds and carry out performance evaluations of key enabling technologies along with three major directions toward improving the network capacity, including spectrum accessibility, Spectral Efficiency (SE) improvement, and network densification. For the spectrum accessibility, numerous types of Small Cell Base Station (SBS) architectures of a Mobile Network Operator (MNO) are evaluated. For the SE improvement, cognitive radio techniques are evaluated for the Dynamic Spectrum Sharing (DSS) among multiple MNOs in a country. For the network densification, the spectrum reuse is evaluated at both intra-and inter-building levels for a given Co-Channel Interference (CCI) constraint. It is shown that multi-band multi-transceiver enabled small cells operating in the high-frequency millimeter-wave licensed or unlicensed spectrum to realize DSS techniques by exploiting SBS architectures for the spectrum accessibility, a hybrid interweave-underlay spectrum access in Cognitive Radio Networks for the spectral efficiency improvement, and both vertical and horizontal spectrum reuse in small cells deployed densely within buildings for the network densification can address high capacity demand in indoor mobile networks
Advanced Production Separator for Crude Oil Production in Thailand
Get PDFThe propose is a new design and development of an advanced separator for oil production in Thailand on a prototype scale to order avoid deposition of sand contaminated include oil production. The novel separator was designed by installing a series of impellers along the horizontal bottom of the separator. The system was successfully implemented on the laboratory scale. A computational fluid dynamics (CFDs) model is employed to investigate the 3D hydrodynamics and flow behavior inside the separator tank modified with impellers. The CFD simulation was operated for 300 min. It could fundamentally demonstrate the flow phenomena of the crude fluids that the sand flowing out from the separator through the water outlet part depends on the accumulation of sand packing bed near the open channel of the outlet and including the effect of impeller rotation. It also shows the wave pattern of the sand outlet and the movement of the impeller did not disturb the efficiency of oil-water phase separation. In the laboratory experiments, the optimum conditions for sand separation in the water outlet part were investigated in terms of impeller sizes, the rotational speed of impellers, and the effect of duration times. The impeller sizes were compared between 3 inches and 5 inches in diameter. The results show that 5 inch-impeller is the optimum size for preventing the sand packing in this system. It was found that 200 rpm gave the most powerful speed of rotation to remove sand to the open channel. From all over the results of the CFD simulation and lab experiment, it could be concluded that the separator system with a strong rotation of impellers leads to effectively prevent sand sedimentation in the separator
Prediction of Catalyst Bed Density and Simulation of Glycerol Steam Reformer for Hydrogen Production
Get PDFThe work focuses on mimicking the loading of the catalyst pellets into a reactor in a realistic manner and proposing a simple method to predict catalyst bed density using Blender 3D Software, a free and open-source 3D creation suite. The catalyst freely falling into a container was animated. The void fraction of loose and close-packing catalyst bed was compared. The effects of different catalyst shapes (sphere and cylinder) and sizes (2–5 mm) on the catalyst bed density in different reactor sizes (18-50 mm) were investigated. It could well predict the values with the error ranging from 0.36 to 6.59%. The obtained information from Blender was employed in a computational fluid dynamics (CFD) model for simulating hydrogen production in a glycerol steam reformer packed with Co-Ni/Al2O3 catalyst