Taiwan Association of Engineering and Technology Innovation: E-Journals
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Optimal Relay Coordination for DG-Based Power System Using Standard and User-Defined Relay Characteristics
Get PDFThe operating time of directional overcurrent relays (DOCRs) can be reduced with user-defined relay characteristics considering plug setting (PS), time multiplier setting (TMS), and relay characteristic coefficients (λ and γ). This study presents a comparative analysis of relay coordination with standard and user-defined relay characteristics. The proposed relay coordination scheme is formulated as a non-linear constraint optimization problem. The grey wolf optimization (GWO) algorithm is used to determine the optimal relay settings and total operating time of DOCRs. The performance of the proposed scheme is tested on the standard 8-bus, 9-bus, and 15-bus systems. The results show that the total operating time of DOCRs with user-defined relay characteristics is better than that with standard relay characteristics. The results of the GWO algorithm are compared with the performance of optimization techniques used in literature to solve the relay coordination problem
Porous Maize Stalk Cellulose Fiber-Reinforced Geopolymer Composites for Heat Insulation at the Bottom Side of a Local Electric Stove
Get PDFThe objective of this work is to develop porous maize stalk cellulose fiber-reinforced geopolymer composites for heat insulation on the bottom side of an electric stove using the solid impregnation method. Heat loss measurement is conducted using an infrared thermometer. Moreover, the temperature effect on the composites is investigated. The maize stalk cellulose fibers are very essential to anticipate the cracking phenomenon generated by high temperatures. The degradation of the fibers causes the formation of small cavities in the matrix, and thus leads to high temperatures. The experimental result shows that it takes 22 minutes to boil water using the proposed electric stove, whereas it takes 29 minutes using the existing local electric stove. By using the proposed electric stove to boil water, 113,793,148.104 KWh of energy per year at the national level can be saved
Developing and Implementing an AI-Based Leak Detection System in a Long-Distance Gas Pipeline
Get PDFThis research proposes an artificial intelligence (AI) detection model using convolutional neural networks (CNN) to automatically detect gas leaks in a long-distance pipeline. The change of gap pressure is collected when leakage occurs in the pipeline, and thereby the feature of gas leakage is extracted for building the CNN model. The gas leak patterns in the long-distance pipeline are analyzed. A pipeline detection model based on AI technology for automatically monitoring the leaks is proposed by extracting the feature of gas leakage. This model is tested by collecting gas pressure data from an existing natural gas pipeline system starting from Mailiao to Taoyuan in Taiwan. The testing result shows that the reduced model of leak detection can be used to detect the leaks from the upstream and downstream pipelines, and the AI-based pipeline leak detection system can obtain a satisfactory result
Fault Identification, Classification, and Location on Transmission Lines Using Combined Machine Learning Methods
Get PDFThis study develops a hybrid method to identify, classify, and locate electrical faults on transmission lines based on Machine Learning (ML) methods. Firstly, Wavelet Transform (WT) technique is applied to extract features from the current or voltage signals. The extracted signals are decomposed into eleven coefficients. These coefficients are calculated to the energy level, and the data of teen fault types are converted to the RGB image. Secondly, GoogLeNet model is applied to classify the fault, and Convolutional Neural Network (CNN) method is proposed to locate the fault. The proposed method is tested on the four-bus power system with the 220 kV transmission line via time-domain simulation using Matlab software. The conditions of the fault resistance random values and the pre-fault load changes are considered. The simulation results show that the proposed method has high accuracy and fast processing time, and is a useful tool for analyzing the system stability in the field of electricity
Evaluation on Mechanical Deterioration of the Asphalt Mixtures Containing Waste Materials When Exposed to Corrosion Solutions
Get PDFThis research investigates the effect of corrosion solutions on the mechanical properties of asphalt concrete mixtures. A control asphalt mixture (CM) and five polymer-modified (PM) or filler-modified (FM) mixtures containing waste materials are prepared, namely PM high-density polyethylene plastic (PM-PL), PM crumb rubber (PM-CR), FM Para wood ash (FM-PA), FM palm empty fruit bunch ash (FM-EA), and FM rice husk ash (FM-RA). The experiment is conducted by immersing the mixture specimens in four types of water solutions (i.e., distilled water, alkaline solution, sulfate solution, and acid solution), followed by the splitting tests. Finally, the corrosion resistance factor (fc) is computed to assess the corrosive effect of the corrosion solutions. The results show that the degree of reduction in tensile strength mainly depends on the type of corrosion solutions, type of mixtures, and immersion time. FM-EA provides better resistance under the alkaline and acid solutions, while PM-PL exhibits the greatest fc under the sulfate solution. Among all the mixtures, PM-PL shows the greatest ability in withstanding the corrosion solutions
Effectiveness of Pozzolanic Leaf Ashes and Plastics on Geotechnical Characteristics
Get PDFThis study aims to investigate the geotechnical characteristics of three soils by adding waste plastics and a mixture of leaf ashes. The soil stabilizers used in the study are the plastics strips from waste plastic file folders and a mixture of ashes from five naturally occurring pozzolanic leaves in Sri Lanka. The plastics used in this study have a width of 5 mm and aspect ratios of 1, 2, 3, and 4 in the weight percentages 0.5, 1, 2, 4, and 8. The mixture of leaf ashes used is in the weight percentages 2, 4, 6, 8, and 10. The investigated geotechnical characteristics of the soils include the improvement of maximum dry density (MDD), optimum moisture content (OMC), soaked California bearing ratio (CBR), shear strength parameters, plastic index (PI), and Atterberg limits. The results suggest that the optimum improvement in soaked CBR and MDD can be achieved by adding 2% plastics and 6% leaf ash mixture into the soils. Shear strength parameters and PI can also be improved
A Novel Engine Start Mechanism for an Electrified Powertrain
Get PDFThis study aims to evaluate a novel starting mechanism (planetary starter) to crank the engine of a hybrid electric vehicle for a flying start maneuver. The study describes the P2 architecture and the planetary starter mechanism. The disturbance during engine crank and driveline engagement is a vital drive quality metric for a P2 vehicle. A linear quadratic Gaussian (LQG) controller is developed to reject the disturbance. The main results of the vehicle acceleration (disturbance) with and without the controller are compared. The results indicate that the planetary starter can crank the engine, and the closed-loop controller can effectively reject the active disturbances during the engine crank event
Numerical Study of Vortex Flow in a Classifier with Coaxial Tubes
Get PDFCentrifugal air classifiers are one of the most used separation devices in particle technology. The study aims to obtain a detailed description of the bulk material classification mechanism in the developed centrifugal classifier. The classifier design and the mechanism of the stable vortex structure formation in the inter-tube space of the device are described. Velocities within and between the vortices are studied to identify regions with inverse flows, which serve as transport channels for particles. The computational fluid dynamics modeling results indicate three channels with negative or near-zero axial velocities: between the vortices, near the outer wall of the internal tube, and the inner wall of the external tube. The selectivity of the device decreases when transport channels are disrupted due to flow mixing, which is caused by the height shifting of the vortex centers
Effect of Gear Materials on the Surface Contact Strength of Spur Gears
Get PDFIn gear applications, the initiation of cracks at or near the contact surfaces of gear mates occurs mostly due to the surface contact mode of gear failure. This study aims to investigate the influence of gear materials on the contact strength of spur gears. In this study, four different gear materials are selected and the contact stress on spur gear mates is analyzed. Hertz’s contact stress equation and ANSYS 16 are used for the theoretical analysis and finite element (FE) method, respectively. The results of Hertz’s equation are compared with the results of ANSYS 16. The results show that the contact stress on spur gear mates varies when different gear materials are used in both methods. This indicates that the surface contact strength of spur gears is greatly influenced by the type of gear materials
Wave Transmission and Energy Dissipation in a Box Culvert-Type Slotted Breakwater
Get PDFThis research is conducted to examine the transmission wave and energy dissipation of a box culvert-type slotted breakwater, which is designed as a breakwater structure with a watertight wall at the top and a box culvert type hole at the bottom. The process involves physical modeling of this structure in the laboratory. The hole and wave parameters are varied to determine the breakwater performance. The results show that the transmission coefficient (KT) value is reduced as the relative hole height (hL/d) value is decreasing and the relative hole length (B/L) and wave steepness (H/L) values are increasing. The energy dissipation coefficient (KD) value increases with an increment in hL/d, H/L, and B/L but starts to decrease after reaching the maximum, which is the optimum H × B/L2 value. This optimum value is found to be 0.0034(hL/d)2.618 depending on the (hL/d) value, while the maximum KD value is recorded to be 0.70