Engineering Journal (Faculty of Engineering, Chulalongkorn University, Bangkok)
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1223 research outputs found
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Twitter-based Disaster Situation Analysis of the 2023 Turkey-Syria Earthquake
No full textEarthquakes are among the most severe natural disasters, and most earthquakes occur without warning or time for preparation. One of the main ways to mitigate the impact of earthquakes is to understand the phases of the disaster according to the disaster management cycle. The 2023 Turkey–Syria earthquake resulted in many casualties and damaged many buildings. In this study, we analyzed each phase of the disaster management phase using data acquired from the Twitter social media platform. Here, tweets related to the 2023 Turkey–Syria earthquake were collected from February 1st to March 10th, 2023. The acquired text data were then tokenized to group them into the keywords related to each disaster management cycle phase. We expect that the findings of this research will help disaster-related organizations understand the situation and manage disasters according to each phase of the disaster risk management cycle
Synchronizing Vehicle Platoons: A Distributed Model Reference Control Approach with Input Saturation
Full text linkDeveloping distributed control for vehicle platoon applications presents significant challenges due to input saturation and the changing velocity of the leader vehicle, which can lead to instability. This study introduces a distributed model reference control strategy designed to synchronize vehicle platoons under an undirected topology while considering input saturation. The approach combines a virtual cooperative tracking error reference model with the actual control dynamics. The virtual model swiftly relays changes in the leader's movement to all platoon members, while the actual controller employs low-gain cooperative feedback control to manage input saturation. Furthermore, the control scheme accounts for potential external disturbances that could impact the stability of the system. Stability analysis indicates that the proposed scheme can achieve synchronization with a bounded residual tracking error in vehicle platooning. The effectiveness of the approach is validated through numerical simulations of a vehicle platoon with eleven vehicles connected in a bidirectional leader topology, providing robust evidence of the control scheme’s practical reliability and effectiveness in real-world scenarios
Derivation of Shear Wave Velocity Profiles from Explosion-Induced Seismic Waves
No full textThis study introduces a simplified analytical method to extract shear wave velocity profiles from seismic waves evoked by explosives, providing a time-efficient solution to the conventional Multichannel Analysis of Surface Waves (MASW) method. Controlled ammonium nitrate emulsion explosions were used at five research sites throughout Thailand with different geological conditions to capture ground motion data through a 16-geophone array during field investigations. This direct analysis evaluates surface wave arrival times in real-time while implementing elastic theory-derived empirical factors for analysis. The proposed method delivers results that match MASW-derived profiles yet require fewer complex procedures and shows Vs30 variations from 4.43 to 38.33%. The simplified method delivered the most accurate results in areas displaying gradual soil property transitions and showed reduced precision when dealing with abrupt soil type or mechanical property shifts. The new method transforms petroleum exploration seismic data into geotechnical applications by delivering dependable shear wave velocity profiles with lower complexity and using fewer resources. It is specifically valuable for limited-budget engineering projects or difficult-to-access locations
Decision-Making Platform for Design Optimization by Integrating Linear Programming and House of Quality
No full textThis study presents an integrated approach combining the House of Quality (HoQ) and Linear Programming (LP) to optimize the design and manufacturing of consumer beverage packaging, ensuring alignment between customer expectations and engineering capabilities. The methodology focuses on translating user needs into functional characteristics, while minimizing production costs and material waste to support sustainability efforts. Linear Programming (LP) is utilized to systematically evaluate various design alternatives, helping designers strike an optimal balance between performance, usability, and cost-efficiency. Additionally, Finite Element Analysis (FEA) is applied to simulate mechanical behaviors, addressing structural concerns like handling convenience and base stability. Special attention is given to design elements, the ergonomically contoured body and cap, with an emphasis on single-handed operation and force distribution. The final design incorporates a sleek, minimalist aesthetic, enhancing both user interaction and manufacturing feasibility. This integrated framework not only enhances development efficiency but also aligns with changing market trends, especially among younger consumers who value functional aesthetics and responsible design. By bridging customer insights with engineering analysis, this study offers a strategic pathway for creating innovative and sustainable packaging solutions
Application of Geophysical Methods for mapping the buried archaeological heritage from the 13th Century in Aceh Sultanate of Lamuri, Indonesia
No full textKuta Lubok is one of the archaeological heritage sites of the Lamuri Sultanate in Aceh, dating back to the 13th century. The site has experienced significant damage over time, primarily due to the Indian Ocean tsunami and natural erosion, which has led to the partial destruction and burial of structural remains. To support preservation and reconstruction efforts, a non-destructive geophysical approach was deemed necessary to locate and map the buried features of this historical site. Geophysical methods, including magnetic, VLF-EM, and EM induction techniques, were applied to investigate the subsurface conditions and identify the distribution of archaeological remains. A total of 22 survey profiles, each ranging from 60 to 80 meters in length, were conducted across the fort and adjacent areas of archaeological interest. Fraser’s analysis of VLF-EM data revealed the distribution of archaeological traces, with high tilt values on the west side indicating the location of the Kuta Lubok fort. Measurements between 80 and 400 meters suggest the presence of a road leading to the fort. VLF-EM data also show that archaeological remains are buried at depths between 0 and 5 meters, a range consistent with the Euler Decomposition results obtained from magnetic data collected along the same profiles. In the form of apparent conductivity, EM induction data identified the fort’s distribution, albeit with lower resolution. Magnetic susceptibility data from EM induction confirmed similar findings. The excavation results in the fort area have found several archaeological objects such as pottery, stoneware, ceramics, charcoal, and bones, indicating that the Kuta Lubok building was once a community settlement area. This research demonstrates the value of integrating multiple geophysical methods to enhance archaeological investigations and preservation planning in coastal heritage sites. Overall, the combined geophysical and archaeological analysis suggests that the Kuta Lubok fort extends approximately 400 meters eastward, parallel to the coastline, from the remaining visible structure
Implementation of Compressed Sensing Technique for Vibration Measurement with a MEMS Accelerometer
Full text linkThis research demonstrates the feasibility of utilizing the compressed sensing technique with a low-cost measurement system consisting of a micro-electromechanical systems (MEMS) accelerometer and a microcontroller for vibration measurement. The vibration signals were sampled non-uniformly and processed using the compressed sensing technique. This approach enables the use of a maximum sampling frequency at approximately half the Nyquist rate, while reducing the amount of data by a factor of three to four compared to conventional sampling methods. The study comprised two main parts: simulation and experimental validation. The simulation phase examined the conceptual potential of compressed sensing, while the experimental phase confirmed its practical implementation. Vibration signals from single-piston and two-piston air compressors were measured using the low-cost system. The compressed sensing results were compared with signals simultaneously measured by a conventional system. The results confirmed that compressed sensing effectively reconstructed signals from low-sampling-rate data, closely matching those obtained from conventional measurements. Overall, compressed sensing proved particularly effective for signals with large amplitudes and prominent peaks in the frequency domain. In such cases, the percentage of matched peaks exceeded 80%, while the percentages of unrecovered and false peaks were less than 20%
Modeling of a Threshold-Based Scaling and Fractional Admission Controlling Problem for NSSI Blocks to Ensure QoS and Optimize Resource Utilization in 5G Network Slicing
Full text linkIn the 5G core network, network functions can be flexibly scaled out/in network slices proactively. The autoscaling process increases effectiveness by scaling out network function instances and minimizes expenses by scaling NSSI (Network Slice Subnet Instance) blocks. 5G network functions have to deploy or terminate multiple NFIs (Network Function Instances) simultaneously; it significantly affects the system’s cost efficiency and ensures QoS (Quality of Service). In the paper, we will propose a Markov chain-based analytical model for the Threshold-based Scaling and Fractional Admission Controlling problem of NSSI blocks (called TSFAC-NB) within a 5G network slice. The model will incorporate two thresholds related to the scaling-out/scaling-in of NSSI blocks. We will also propose a FAC (Fractional Admission Controlling) mechanism in the model with two thresholds added to control NSSI blocks by the probability to optimize resource utilization. A threshold-based scaling and fractional admission controlling (TSFAC) algorithm is developed and implemented in Kubernetes-based Open5GS to evaluate the performance of TSFAC-NB experimentally. The simulation results show a similarity between the analytical and experimental results, in which the analytical model helps to determine the admission thresholds for the best performance of TSFAC-NB
Maximizing EVA in a Cocoa Supply Chain Network Design with a Hybrid Optimization Approach: A Case Study in Vietnam
No full textGiven the intricacy of the cocoa supply chain and the abundance of relevant data, effectively managing factor variations proves to be a challenge, making traditional mathematical optimization methods insufficient for practical applications. This study formulates a three-phase optimization approach combining Mixed-Integer Linear Programming (MILP) and Simulation-Based Optimization (SBO), where MILP determines strategic decisions (i.e., supplier selection and establishment of distribution centers), and the simulation derives tactical plans (i.e., inventory levels) under demand uncertainty. The proposed approach combines the strengths of both methods and helps compensate for their weaknesses. Moreover, this study demonstrates the necessity of maximizing Economic Value Added (EVA) by prioritizing the capital charge from an investment when designing the network instead of the operating profit maximization, which considers the short-term gains. Employing a case study on the food industry in Southern Vietnam, the effectiveness of this approach and its ability to derive valuable managerial insights can be demonstrated. The proposed three-phase approach can enhance a significant methodological deficiency by introducing a hybrid approach that effectively encapsulates the structural and dynamic intricacies inherent in supply chain systems, while simultaneously optimizing for EVA, the financial performance metric that has been overlooked in many existing supply chain modeling approaches
Stochastic Creep Analysis of Hastelloy XR based on MPC-Omega Method and the Extended Kalman Filter
No full textA stochastic creep model was developed by incorporating the extended Kalman filter with the MPC-Omega method. The process noise covariance matrix for the filtering algorithm was derived by applying a traditional approach of uncertainty analysis to the empirical relationship of the Omega model’s parameters with stress and temperature. The model was validated with constant stress creep data of Hastelloy XR in an air environment and at various temperatures by predicting the statistical distributions for strain at a given time and the remaining useful life using a Monte Carlo simulation. The mean of the predictions was within a factor of two of the experimental data in almost all cases. In addition, the predicted 95% confidence intervals could cover virtually all of the experimental data
A Review of Practical Algorithms for Fault Diagnosis at DC side of Photovoltaic Systems and Future Research Trends
No full textPhotovoltaic systems have been under development for many years. However, their energy production is low compared to other systems. From 2016 to 2022, the research goal was to develop a fault diagnosis that evolves from inverter functional analysis to comprehensive monitoring systems. Currently, it is a major challenge to propose a commercially viable product. This review article focuses on fault diagnosis algorithms on the PV DC side for real-world applications. We analyzed 100 studies published between 2017 and 2024, considering nine factors PV array size on the DC side, data collection method, number of data sets, the fault itself, fault location, diagnosis accuracy, diagnosis time, input data for the algorithm and the diagnosis algorithm used. We summarize the strengths and weaknesses of each study in terms of practical implementation and highlight new technological trends. In addition, we discuss how new technologies for PV fault diagnosis on the DC side are tested and evaluated. Our contribution is intended to guide research in the field of PV fault diagnostics and help ensure that it can be used commercially in the future