Engineering Journal (Faculty of Engineering, Chulalongkorn University, Bangkok)
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Load Feasible Region Determination by Using Adaptive Particle Swarm Optimization
Get PDFThe proposed of a method for determination a space of feasible boundary points, by using adaptive particle swarm optimization in order to solve the boundary region which represented by particle swarm points. This paper present method supports the calculation for a large-scale power system. In case of contingency will illustrate the point on the plane x-axis and y-axis dimensional power flow space. In addition, This method not only demonstrates the optimal particle swarm through the boundary tracing method of the feasible region but also present the boundary points are obtained by optimization. Moreover, receding loss function and operational constraints simultaneously are considering. The formulation points of feasible region can also determine the boundary points which is the contingencies are taken into account and the stability of load demand that system allows to execute in the normal requirements. These feasible points defined the limit of control actions and the robustness of operating points. Finally, the test systems shown the impact of system parameters on the load shedding, generator voltage control, and load level
A Study of Flowrate Calculation Using ESPRIT Technique for Ultrasonic Velocity Profiles
Get PDFAn ultrasonic Velocity Profile (UVP) has been continuously improved for flowrate measurements. Since the UVP can visualize a flow profile along a cross section of pipelines, it provides a significant advantage over other conventional methods such as differential pressure, turbine, and vortex. Previously, the UVP was realized by means of autocorrelation, fast Fourier transform, and wavelet as the signal-processing method. An Estimation of Signal Parameters via Rotational Invariance Technique (ESPRIT) has been widely used in a field of communication engineering for a high-resolution signal processing. This is the first of utilizing the ESPRIT technique in fluid mechanics for a flowrate computation. To guarantee the proposed idea, the results were compared with a standard electromagnetic flowmeter. Lab experiments were required to demonstrate the accuracy of flowrate measurements
A Co-optimization Model of Natural Gas Supply and Electric Power Systems
Get PDFIn Thailand, natural gas has been the primary source of fuel for power generation for the past few decades due to availability of indigenous resources. With continuous load growth and near depletion of domestic natural gas supply, renewable energy will play an increasing role in power industry in a close future. To achieve that, energy storage would become the key enabler. Therefore, this paper proposes a co-optimization steady-state model of a -coupled system of gas supply network and electric power system with integration of an energy storage device namely power-to-gas. The IEEE-14 bus power system coupled with the 20-node and 24 pipeline natural gas system is used to verify effectiveness of the proposed method through computer simulation. The results show the capability in maintaining the system variables within the statutory security limits and reducing power losses. Moreover, the proposed method has another feature that can optimally curtail loads of the two systems when experiencing stressful conditions
Effect of Monoethanolamine on Corrosion of A283 Carbon Steel in Propionic Acid Solution
Get PDFThis research studied the effect of monoethanolamine or MEA on corrosion of A283 carbon steels both in water and 5 vol.% propionic acid solution at boiling point temperature of solution. MEA concentrations ranging from 30 to 90 wt.% in water was used. The 5 vol.% propionic acid containing around 45 and 75 wt.% MEA additions (100:1 and 100:5) by volume in the test solution was studied. The carbon steel coupons were tested in a liquid phase, liquid and vapor phase and vapor phase. The weight losses of coupons were evaluated to calculate corrosion rate. A scanning electron microscope and X-ray diffraction were used to characterize the corrosion surface of coupons. The results showed that the corrosion rate order was in the liquid phase > in the liquid and vapor phase > in the vapor phase. MEA decreased the corrosion rate of A283 carbon steel both in water and 5 vol.% propionic acid solution containing around 45 and 75 wt.% MEA additions (100:1 and 100:5) by volume. MEA can be considered as corrosion inhibitor of carbon steel both in water and propionic acid solution. The formed layers of FeO(OH), Fe2O3 and Fe3O4 on the surface were detected to prevent a corrosion attack. The formed layer of Fe3C was also found and discussed. The more severe corrosion was in ferrite
Computer Simulation Study for Functional Group Effect on Methane Adsorption in Porous Silica Glass
Get PDFIn this paper, adsorption of methane on porous silica glass was investigated to see whether functional groups can affect the adsorption behavior. Adsorption isotherms for pores having widths between 7 and 40Å at 283 and 298 K were investigated using a Monte Carlo simulation (MC) method. The model of porous silica glass proposed in this study was assumed to be a finite-length slit pore which consisted of two parallel walls. The tetrahedral structure of SiO4 was used as atomic structure for the wall surface. Hydroxyl was assumed as the surface functional group which allocated either at pore mouth or random with concentration of 5 and 10%. It was found that the concentration of functional group has less significant effect on the adsorption of methane. The adsorption isotherm decreased a bit with an increase of functional group concentration. Effects of functional group position on adsorption isotherm were also investigated, the adsorption isotherm obtained for the random topology was greater than that for the pore mouth topology, due to the pore blocking effects. At the same pore width, the adsorption isotherm at 283K was greater than that at 293K, and this was due to that the adsorption of methane on porous silica glass was a physical adsorption. The initial adsorption of methane shifted to the higher pressure by increasing pore width, and the maximum adsorption capacity decreased with an increase of pore size, because of the pore packing effect
Barrier and Sacrificial Protection Mechanisms of Zinc Rich Primers
Get PDFA specific type of Zinc-Rich Paint was scratched and exposed in salt fog chamber for various exposure times up to 1,000 hours. The corrosion products that developed within the scratched region were studied by optical microscopy, scanning electron microscopy, and Electrochemical Impedance Spectroscopy (EIS). Bode plots were used to obtain the total resistance of the coating by salt spray exposure time. The results suggest that the mechanism of protection of zinc rich paints may not be simply as only sacrificial action followed by only barrier action, but rather an iteration of these two mechanisms exist. Although at very short times, prior to deposition of zinc corrosion products in the scratch, sacrificial action is the only mechanism of protection, once the corrosion products start to form there is a conjunction of the two protection actions with one dominating from time to time. This dual protection mechanism continues until all the available free zinc within the throwing power distance of the scratch has been consumed, at which point only barrier protection remains in action
Novel Approach to Respiratory Rate Measurement Using Resonance Tube with Contradictory Thresholding Technique
Get PDFIn this paper, we propose a novel approach to respiratory rate measurement using resonance tube to enhance the performance of microphone inserted and fixed at the end of the tube to catch breath sound signal from the mouth and/or nose. The signal is amplified and passed into envelope detector circuit after which it is compared with a suitable reference voltage in comparator circuit to generate a pulse train of square wave synchronized with the respiratory cycle. A simple algorithm is developed in a small microcontroller to detect rising edges of each consecutive square wave to calculate respiratory rate together with analysis of breathing status. In order to evade noises which will cause errors and artifacts in the measuring system, the reference voltage is creatively designed to intelligently adapt itself to be low during expiration period and high during inspiration and pause period using the concept of resolving contradiction in the theory of inventive problem solving (TRIZ). This makes the developed device simple and low-cost with no need for complicated filtering system. It can detect breath sound as far as 250 cm from the nose and can perform accurately as tested against End Tidal CO2 Capnography device. The result shows that the developed device can estimate precisely from as low as 0 BrPM to as high as 98 BrPM and it can detect shallow breathing as low as 10 mV of breath sound
Perceived Service Quality and Commuter Segmentation of Informal Public Transport Service in Bangkok, Thailand
Get PDFOne informal public transport service in Bangkok is Silor (SR), given the meaning in Thai as four-wheeler. SR facilitates urban mobility both in terms of major travel mode and feeder to bus and mass transit lines in the city. This research aims to explore user subgroups characterized by attitudes through an Exploratory Factor Analysis followed by commuter segmentation through Cluster Analysis based on the obtained latent variables in order to propose future implications for SR service improvement in Bangkok. Interviews are conducted through questionnaire survey to collect users’ socioeconomic and trip profiles and attitudes towards SR service. The result reveals dimensions of service quality, which explain user perception and priorities regarding the service. Four segments of SR users are identified by four attitudinal factors, including reliability, invehicle environment, comfort and convenience, and environmental impact. Personal profiles, trip characteristics, and attitudes of each segment are analyzed and compared. Research findings would contribute to new knowledge on quality factors and area of SR service improvement as well as provide better understanding on diverse perception among SR user segments. Policy implications that best suit for each user segments are discussed
Flooding in Oda River Basin during Torrential Rainfall Event in July 2018
Get PDFExtreme rainfall events cause severe flooding and/or landslides almost every summer in Japan. It seems that the frequency of such events and induced human/economic losses has increased in recent years. A torrential rainfall event in early July 2018 caused severe flooding in many river basins over Hiroshima and Okayama Prefectures of western Japan and resulted a number of fatalities and serious damage to property. One of them is the Oda river basin (about 498 km2), which was severely affected by the flood during the event. Different types of observation systems were used to measure or estimate rainfall for this event. Comparison of radar and satellite-based rainfall shows a good agreement with the rain gauge observations of the entire period. Basin-mean total rainfall from Japan Meteorological Agency’s analyzed radar rainfall (RADJ), Water and Disaster Management Bureau’s radar rainfall (RADW), Automated Meteorological Data Acquisition System (AMeDAS), and satellite-based rainfall data (GSMaP) were about 314, 322, 357 and 304 mm during July 5–7 2018. In this study, we applied Rainfall–Runoff–Inundation (RRI) to acquire a detailed understanding of flood processes in the Oda river basin. All the available rainfall data including different spatial resolution of hydrographic features were considered as the main input data in the model separately. Gridded flow and map of the possible maximum flood depth across the basins were generated and validated. Simulated results based on high resolution topographic data are more closely aligned with observed data. It is also found that the maximum flood inundation areas estimated by the RRI model using radar rainfall data appeared somewhat closer with the extent of flood-affected areas from the model with data of the Japanese Geospatial Information Authority (GSI) over the Mabi city. It is believed that modelled results can be used an important reference in the disaster mitigation and that they may be useful for further studies
Development of Data Acquisition Technique for Inspection of Pipes in Vessel using Gamma Scanning Coupled with Computed Tomography
Get PDFThis study proposes the data acquisition technique for on-line inspection of the pipe installed inside closed vessels through a laboratory model. The technique was based on transmission of gamma radiation that projected onto the radiation detectors. Laboratory model composed of four vertical pipes with different size installed inside the top opened tank. The proposed acquisition technique allowed the scanning with a few number of detectors to complete the projection as stated in Computed Tomography algorithm. Projected data were computed and reconstructed using filtered back projection algorithm and displayed in two dimension image. The simulation using Monte Carlo for N-Particle computer code (MCNP) was presented in this paper based on theoretical algorithm to be regarded as a reference result. The comparison between experimental results and simulation result showed a good agreement to each other. This technique could be extended to inspect integrity structure of pipe in vessels in petroleum and petrochemical in field work