Engineering Journal (Faculty of Engineering, Chulalongkorn University, Bangkok)
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Enhancing Infrastructure Safety: A UAV-Based Approach for Crack Detection
Get PDFThe imperative task of identifying and promptly detecting cracks in concrete bridges is crucial for preserving their structural health and ensuring the safety of users. Traditional bridge inspection methods heavily rely on human eyes and additional tools, demanding extensive training for inspectors and resulting in time-consuming processes. The increasing demand for Unmanned Aerial Vehicles (UAVs) has provided a transformative solution to access hard-to-reach areas efficiently. This research explores the integration of deep learning algorithms, including CNN, RCNN, Fast RCNN, Faster RCNN, and YOLO, to enhance the accuracy and efficiency of UAV-based crack detection systems. Experimental results affirm the effectiveness of these algorithms in addressing challenges such as lighting variations and small crack detection. The study aims to contribute to structural health monitoring, improving maintenance practices, and enhancing safety
Stability of Control Systems with Multiple Sector-Bounded Nonlinearities for Inputs Having Bounded Magnitude and Bounded Slope
Get PDFThis paper considers the input-output stability of a control system that is composed of a linear time-invariant multivariable system interconnecting with multiple decoupled time-invariant memoryless nonlinearities. The objectives of the paper are twofold. First and foremost, we prove (under certain assumptions) that if the multivariable Popov criterion is satisfied, then the system outputs and the nonlinearity inputs are bounded for any exogeneous input having bounded magnitude and bounded slope, and for all the nonlinearities lying in given sector bounds. As a consequence of using the convolution algebra, the obtained result is valid for rational and nonrational transfer functions. Second, for the case in which the transfer functions associated with the Popov criterion are rational functions, we develop a useful inequality for stabilizing the system by numerical methods. This is achieved by means of the positive real lemma and known results on linear matrix inequalities. To illustrate the usefulness of the inequality, a numerical example is provided
Input-Shaped Model Reference Control Using Sliding Mode Design for Sway Suppression of An Industrial Overhead Crane
Get PDFInput-shaped model reference control using sliding mode design is a proven method for controlling systems with parameter variations and disturbance. However, this method has never been reported for an industrial overhead crane, which is operated under nonlinear elements such as acceleration and deceleration limits caused by inverters for driving a crane in speed control mode. The successful implementation of this method will allow the crane to be operated in “hybrid mode”, which results in the fastest response from the feedforward control technique, unity magnitude zero vibration (UMZV) and tracking performance from the feedback control. This paper shows the implementation and experimental result of the input-shaped model reference control using sliding mode design for sway suppression of an industrial overhead crane. The control scheme was implemented on an industrial grade 1-ton overhead crane using a PLC and inverters. The experiments compared the control results of the UMZV and the presented control scheme on the industrial overhead crane in the cases that the system parameters are known and uncertain. When the parameters are uncertain, the presented method, with the feedback elements, provided the advantage of reducing residual vibration, while keeping the benefits of the UMZV performance
Liquid-Phase Exfoliation of Graphite Using the Serum from Skim Natural Rubber Latex
Get PDFThe green exfoliation of graphite by using the serum from skim natural rubber latex together with ultrasonication was investigated. The rubber particles were coagulated with 0.7% w/v cationic polyacrylamides solution and the remaining serum containing ammonia was used as an exfoliating medium. The suspension with 25 mg graphite/ml serum was sonicated for 2 h at 29-53°C in an ultrasonic bath at 40 kHz and was left standing for 2 h at room temperature. The top part was centrifuged at 2000 rpm for 30 min and then the top section of this was centrifuged at 10500 rpm for 30 min to collect the solid. This process was repeated 2-3 times using the bottom part of the sedimentation. The yield of exfoliated graphite sample from each exfoliation process ranged from 0.20-0.35% and showed quality of multilayer graphene based on Raman spectroscopy results, which was comparable to the commercial graphene. The samples were also checked with scanning electron microscope and underwent some experiments, including sedimentation and methylene blue adsorption. It was found that the high-quality exfoliated sample showed better dispersion in water, resulting in 99% turbidity after 20-min sedimentation and yielded higher adsorption capacity than that of the commercial graphene
Development of a Data-Driven Soft Sensor for Multivariate Chemical Processes Using Concordance Correlation Coefficient Subsets Integrated with Parallel Inverse-Free Extreme Learning Machine
Get PDFNonlinearity, complexity, and technological limitations are causes of troublesome measurements in multivariate chemical processes. In order to deal with these problems, a soft sensor based on concordance correlation coefficient subsets integrated with parallel inverse-free extreme learning machine (CCCS-PIFELM) is proposed for multivariate chemical processes. In comparison to the forward propagation architecture of neural network with a single hidden layer, i.e., a traditional extreme learning machine (ELM), the CCCS-PIFELM approach has two notable points. Firstly, there are two subsets obtained through the concordance correlation coefficient (CCC) values between input and output variables. Hence, impacts of input variables on output variables can be assessed. Secondly, an inverse-free algorithm is used to reduce the computational load. In the evaluation of the prediction performance, the Tennessee Eastman (TE) benchmark process is employed as a case study to develop the CCCS-PIFELM approach for predicting product compositions. According to the simulation results, the proposed CCCS-PIFELM approach can obtain higher prediction accuracy compared to traditional approaches
Reverse Logistics Network Design with a 3-Phase Interactive Intuitionistic Fuzzy Goal Programming Approach: A Case Study of Covid-19 in Pathum Thani, Thailand
Get PDFDuring outbreaks, a vast quantity of Infected Medical Waste (IMW) can be substantially generated in a short period, which poses a massive risk to medical personnel and surrounding communities. This study proposes an Intuitionistic Fuzzy Multi-Objective Multi-Period Mixed-Integer Linear Programming (IFMOMILP) model for effective IMW management in outbreaks under uncertainty, considering financial and risk factors subject to a priority from Decision Makers (DMs). The primary emphasis is on determining the optimal locations and capacity levels for temporary facilities, including temporary storage and treatment centers, as well as the optimal transportation routes. A 3-phase interactive Intuitionistic Fuzzy Goal Programming (i-IFGP) approach is developed to solve this IFMOMILP model. First, the Jiménez approach is applied to handle the uncertainties. Then, the problem is solved by Intuitionistic Fuzzy Goal Programming (IFGP). An actual case study of the COVID-19 outbreak in Pathum Thani province in Thailand was carried out to demonstrate the effectiveness of the proposed approach. The proposed approach yields solutions with varying feasibility degrees and scaling factors, providing alternatives for DMs. Then, the score function is utilized to imply DMs’ satisfaction with the outcomes, which is a concrete measure since it can reflect the intention of the DMs
Methodology and Guidelines for Designing Flexible BMS in Automotive Applications
Get PDFThe fragile characteristics of Li-ion batteries lead to the need of battery management system (BMS) to carefully supervise them during the operation. Since there are so many variations in battery configurations, the BMS usually must undergo many iterations of the development cycle, which take a long time to optimize and finalize the design. Previously, many works adopted the idea of modularized BMS to address these issues, but they still have some skeptical issues such as measurement approaches or difficulties in reconfiguration. This paper presents a guideline on the crucial aspects of flexible BMS designs for automotive applications, which aims to reduce time and effort for developing a new BMS for automotive battery pack. The guideline covers some crucial aspects pertaining the automotive BMS hardware implementation, SOC estimation algorithm and its computational performance based on Extended Kalman Filter (EKF) and Luenberger Observer (LO) with 3 levels of Electrochemical model (ECM). All of the tests were carried out in a small-scale microcontroller. It was found that 2-RC ECM gives the best trade-off between SOC estimation accuracy and computational time. While the 3-RC ECM provides 9.5% and 31% higher accuracy than the 2-RC and 1-RC ECM, respectively, but taking 88% and 240% higher computational time than the latter two cases. The optimal speed of the observer poles of LO algorithm are suggested to be in the range of 2-5 times faster than the system poles, which makes the convergence speed to be comparable to the EKF algorithm but is still able to keep the SOC estimation error in the range of 3-5%. These results can be used to make a trade-off between estimation accuracy and computational time, to select the optimal SOC estimation algorithm for onboard BMSs
Laser-Induced Graphitization of Thermosetting Polymer Substrate and its Application—A Review
Get PDFLaser-induced graphene (LIG) production and application is currently receiving tremendous attention of the research community, perhaps because of its facile, clean, and sustainable nature. Thus, any critical review about the subject matter cannot be over-emphasized. Herein, the stage-wise procedure of producing the LIG that involves preparation of polymer substrate, specification of laser machine parameters/condition, laser-induced irradiation on the prepared substrate, and characterization/confirmation of the LIG have been explained, and most importantly the various applications of the LIG in the areas of energy and power, electromagnetic interference (EMI) shielding, environmental, and sensor development have also been reviewed. It is worthy of nothing that polyimide film is predominantly employed by the different independent researches as substrate in the LIG production and applications, and fascinating findings were found. Furthermore, future perspective of LIG production and applications have been suggested. Overall, information summarized herein will no doubt provide basis for research and development in the area of LIG production and application
Evaluation of The Road Vulnerability Network During the Evacuation Process (A Case Study in A Coastal Area of Bengkulu City, Indonesia)
Get PDFThis study aims to determine the road network's performance for the Pantai Panjang and Bencoolen Mall areas in Bengkulu City, Indonesia, if a tsunami disaster occurs. The traffic on roads and questionnaire survey on respondents who occasionally come to the study areas is performed. The numerical analysis is conducted using four-step modelling based on various road condition scenarios to evaluate the road network performance. Scenario 1 considers existing conditions during tsunami evacuation; Scenario 2 considers increasing road capacity and adding two new road sections using traffic flow simulation during tsunami evacuation; Scenario 3 considers the addition of one new road section using traffic flow simulation during tsunami evacuation. For Scenarios 4, 5 and 6, the previous scenarios are evaluated by considering the increase in vehicle numbers in the next five years. Scenarios 1 and 4 show that there is an increase in the degree of saturation up to 0.68. It shows that the level of road service decreases. The road modification scenarios (Scenarios 2 and 3) show improved service levels. The modelling results with scenarios using traffic flow data under the improvement of road service for the next five years (Scenarios 5 and 6) show that the level of road service is better than the existing model. The road modifications scenario also effectively reduces the vulnerability index. The local government could also consider the results to improve the tsunami disaster mitigation in the study area
New Sustainable Approach for Multi-Objective Production and Distribution Planning in Supply Chain
Get PDFThe paper aims to introduce a sustainable approach for aggregate production and distribution planning in a supply chain (APDP-SC) that considers multiple objectives and fuzzy parameters. The proposed approach addresses sustainability concerns, including maximizing total profit and total sales of the entire supply chain, balancing profit satisfaction between supply chain members, minimizing CO2 emissions from raw materials, production processes, and transportation of goods in the supply chain, and maximizing goodwill score from corporate social responsibility (CSR) activities. To determine the compromised solution, this paper develops a fuzzy multiple objectives mixed integer linear programming (FMOLP) model and a de-fuzzified model. The results of a simplified real case demonstrate that the proposed approach and model effectively determine the compromised solution and outperform comparison models that lack important features. Notably, this manuscript is the first to integrate the decision on conducting CSR activities with the APDP-SC decisions