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Increasing the Efficiency of Underground Block Leaching of Metal
No full textThe purpose of this study is to increase the efficiency of underground block metal leaching by increasing the metal content in the pregnant solution using the cavitation effect. To achieve this goal, it is proposed to process (cavitate) the leaching solution on the injector. The following research methods were used in this study: analysis of the current state of scientific and technical problems and research, laboratory work to establish the effect of the treated (cavitated) solution on the metal content in the pregnant solution, collection and processing of statistical data from laboratory work, analysis of research results, and preparation of conclusions. According to the results of laboratory research, leaching with a treated solution on an injector leads to an increase in the content of a useful component in the pregnant solution. The maximum increase in the metal content in the pregnant solution was achieved by processing the leaching solution for 5 min. The effectiveness of the solution over time after treatment was maintained for a long time (up to one month). Changes in the solution pressure did not affect the effectiveness of the treated leaching solution. The scientific novelty of this work consists of determining the dependence of the content of the useful component in the pregnant solution on the time of processing the leaching solution on the injector and the leaching time, which determines the optimal time for processing the solution on the injector to obtain the maximum metal content in the pregnant solution. The dependence of the content of the useful component in the solution on the pressure during leaching with untreated and treated solutions on the injector was obtained. Doi: 10.28991/CEJ-2024-010-10-014 Full Text: PD
Impact of Vertical Vibration on Group Piles During Earthquake Loading: Experimental Findings
No full textThis study presents novel research on the impact of vertical vibration on the dynamic response of pile groups embedded in stratified soil under seismic loading conditions. An experimental setup was employed wherein the piled machine foundation was subjected to vertical vibrations at three operating frequencies (10, 20, and 30 Hz) and subsequently exposed to four levels of seismic acceleration (0.1 g, 0.34 g, 0.77 g, and 0.82 g). Piles with a length-to-diameter ratio of 25 were embedded in a stratified soil profile, with an upper loose layer (30% relative density) and a lower dense layer (80% relative density) acting as end-bearing. Measurements and analyses of horizontal and vertical accelerations, and amplification factors were conducted using the Fast Fourier Transform (FFT), spectral acceleration (Sa), and variation of acceleration with depth. The results demonstrated a significant reduction in horizontal acceleration, with a peak ground acceleration (PGA) reduction of up to 64% in average, particularly at higher frequencies such as 30 Hz. The mitigation efficiency at 30Hz improved with increasing PGA, showing reductions of 42, 68, 75, and 63% for seismic accelerations of 0.1 g, 0.34 g, 0.77 g, and 0.82 g, respectively. The analysis further revealed harmonic resonance and higher mode effects at lower frequencies, with nonlinear soil behavior affecting the resonance and amplification patterns. Additionally, the results demonstrate that the far-field accelerations exceeded the near-field accelerations within the pile group, particularly in the surface layer. The results indicated that the initial vibration amplitudes exceeded the safe operating limits outlined in ACI 351.3R-18 under seismic loading, particularly at higher seismic acceleration levels and lower frequencies. Additional modified charts were presented to account for these conditions. The results presented promising evidence for using vertical vibrations as an earthquake-mitigation strategy. However, avoiding operating at frequencies less than 10 Hz is recommended because of the potential resonance and interaction with horizontal accelerations during earthquakes. Doi: 10.28991/CEJ-SP2024-010-010 Full Text: PD
An Advanced Adaptive Mesh for Beam-Column Finite Elements on Transient Dynamic Analysis
No full textThis research examines the influence of truncation error reduction on the nonlinear dynamic analysis of complex framed structures. A modified -adaptive method, incorporating inertial and damping forces in addition to the common restitutive forces, is introduced to refine the mesh and enhance accuracy. To address convergence challenges arising from increased complexity, Ritz modal shapes are utilized to reconstruct the mass matrix, excluding detrimental modes. The proposed formulation is validated through rigorous computational models and experimental data. Six building case studies, varying in complexity, were analyzed using the modified -adaptive method. The results revealed substantial variations in frequency and displacement responses, ranging from 6% to 50% and 0.8% to 63%, respectively. These disparities underscore the significant influence of nonlinear behavior on structures with high-order shape functions. The proposed formulation is theoretically more accurate. Therefore, the findings emphasize the necessity of employing mesh refinement techniques to obtain accurate nonlinear dynamic analysis results, particularly for complex structures with pronounced nonlinear characteristics. This study contains the background of a software called MainModelingStr. Doi: 10.28991/CEJ-2024-010-12-01 Full Text: PD
Measuring Belt and Road Initiative Perceptions: A Comparative Analysis of Thai Border and Non-Border Regions
No full textThis study aims to analyze and compare perceptions of the Belt and Road Initiative (BRI) between border and non-border regions in Thailand, addressing a gap in understanding how geographic proximity influences BRI project views. Using a sample of 3,200 respondents, this study employed confirmatory factor analysis and measurement invariance techniques to examine perceptions across eight key constructs related to BRI impacts. The findings reveal significant structural differences in BRI perceptions between border and non-border regions. Non-border regions generally showed more consistently positive perceptions across all constructs, while border regions demonstrated more varied and nuanced views. Notable differences were observed in perceptions of economic benefits, logistics improvements, and social impacts. This study contributes to the field by providing a comprehensive comparative analysis of BRI perceptions across different geographical contexts within a single country, employing advanced statistical methods to ensure valid comparisons. The results suggest the need for tailored approaches to BRI implementation and communication in different regions, implementing inclusive policy-making processes, and establishing robust monitoring and evaluation systems to address the varied perceptions and potential impacts of BRI projects in Thailand. Doi: 10.28991/CEJ-2024-010-12-010 Full Text: PD
Investigating Mechanical Properties of Metakaolin-Based Geopolymer Concrete Optimized with Wastepaper Ash and Plastic Granules
No full textThis study develops an environmentally friendly geopolymer concrete (GPC) using wastepaper ash (WPA) and high-density polyethylene (HDPE) granules, addressing environmental challenges such as wastepaper and HDPE disposal and CO2emissions from cement production. WPA was produced by incinerating wastepaper at 550 °C for one hour and used as a partial replacement for MK in ratios of 10%, 20%, 30%, 40%, 50%, and 100%, while HDPE granules replaced river sand in ratios from 1% to 5%. The results showed that the use of 30% WPA resulted in a compressive strength (CS) of 35.38 MPa, which was significantly higher than the control sample's CS of 31.62 MPa. The use of 30% WPA increased slump due to lower water demand. The combination of 3% HDPE and 30% WPA further enhanced the mechanical properties, resulting in a CS of 36.54 MPa, representing a 15.5% increase over the control. However, the addition of 3% HDPE and 30% WPA reduced the slump, attributed to the increased friction from the HDPE granules. Advanced analyses, including SEM, EDX, and XRD, confirmed a refined pore structure and increased geopolymerization in the treated GPC. It is novel to optimize WPA and HDPE as waste products in the production of MK-based GPC. Doi: 10.28991/CEJ-SP2024-010-011 Full Text: PD
Application of GIS Models in Determining the Suitable Site for a Solid Waste to Energy Plant in an Urban Area
No full textThis paper deals with the establishment of a solid waste-to-energy plant that significantly reduces the volume of solid waste and produces electricity at the same time. Thirteen criteria have been identified to locate the station based on environmental, economic, and social factors to avoid its negative impacts. These criteria were addressed by combining a Multi Criterion Decision Making (MCDM) method based on the GIS software. This study aims to establish a MCDM system based on the classical AHP and validated by the fuzzy AHP method. The findings revealed that using the classical AHP and fuzzy AHP methods, there was no significant difference in decision-making between the two methods. The importance of the criteria under study has been identified based on the judgments of experts; a questionnaire was designed and conducted electronically, which was collected with the help of a weighted overlay GIS model. This technique combines multiple reclassified data in ArcGIS 10.8 software to overlay criteria layers with different weights to create a composite map of suitability categories across the study area. The outcomes revealed that 96.76% of the study area is unsuitable for establishing the station, 1.36% is moderately suitable, and 0.04% is only very suitable for station site selection. Doi: 10.28991/CEJ-2024-010-01-011 Full Text: PD
Rice Self-Sufficiency and Optimization of Irrigation by Using System Dynamic
No full textThis research intends to optimize the results of irrigation canals with the conversion of function to fisheries without reducing rice self-sufficiency regionally. However, irrigation is an infrastructure asset that needs to be used optimally. It is due to the water; water sources and irrigation infrastructure can provide more benefits to rice fields, which are to function as fisheries in the study location (West Sumatra Province). The aim of this research is to propose the optimal combinations of irrigated land planted with rice and those in the form of fisheries. The methodology uses System Dynamics due to the official BPS data. There are many tools that are used in this system dynamics approach, such as causal diagrams, archetype systems, diagrams of stock and flow, and the behavior of over-time graphs. The DSS generator for simulating the program in this study uses Stella, which is a new paradigm in the water resources system approach. The result shows that the potential increase in income that could be obtained by converting the rice fields to tilapia fisheries is about 126 million Rupiah per year per hectare. West Sumatra Province, as a national rice granary, has many districts that are more self-sufficient in rice, so it can be considered to utilize irrigation to become the irrigation for fisheries. The potential of rice fields that can be converted into fisheries while maintaining self-sufficiency in rice at the district/city level of West Sumatra Province is more than 61 thousand hectares, and it generates an increase in income of about 7.7 trillion per year. Doi: 10.28991/CEJ-2024-010-02-010 Full Text: PD
Monitoring Physiological State of Drivers Using In-Vehicle Sensing of Non-Invasive Signal
No full textEighty percent of traffic accidents are caused by human error, called hypo vigilance, stemming from drowsiness, stress, or distraction while driving. This poses a significant threat to road safety. An electrocardiogram (ECG) is often used to monitor drivers' health. Thus, enhancing vehicles with Internet of Things (IoT) sensors and local analytical databases becomes crucial for real-time detection and transmission of relevant health data to avoid things that compromise road traffic safety. This study introduces a cost-effective in-vehicle ECG sensing prototype using an AD8232 sensor integrated with an Arduino Uno and an AD8232 Wi-Fi module placed on the steering wheel to monitor the driver's heart signal while driving. Short-term heart rate variability (HRV) features were computed through Python from the acquired ECG data, and supervised machine learning techniques such as AdaBoost, Random Forest, Naí¯ve Bayes, and Support Vector Machine (SVM) classified the features into normal and abnormal classes. Naive Bayes exhibited the highest accuracy (90.91%) and F1 score (85.71%), surpassing Random Forest's lower accuracy (63.64%) and F1 score (50.00%). These findings indicate the prototype's potential as a valuable tool for ensuring safe and efficient driving, proposing integration into standard vehicle safety systems for enhanced road traffic safety. Doi: 10.28991/CEJ-2024-010-04-014 Full Text: PD
Eco-friendly 3D Printing Mortar with Low Cement Content: Investigation on Printability and Mechanical Properties
No full textThe conventional approach to achieving optimal printability and buildability in 3D printing mortar relies heavily on cement, which is both costly and environmentally detrimental due to substantial carbon emissions from its production. This study aims to mitigate these issues by investigating the viability of slag as a partial substitute for cement, with the goal of developing an eco-friendly alternative. The newly formulated mortar, featuring a 30% reduction in cement content (from 830 to 581 kg/m3) and the inclusion of 0.10% micro-fibers, exhibits properties comparable to conventional 3D printing mortar. The research is structured into two parts: Part 1 focuses on determining the optimal fiber content, while Part 2 delves into the investigation of fiber-reinforced mortar with reduced cement content for 3D printing. Criteria were established to ensure mortar flow at 115%, initial printable time below 60 minutes, and 7-day compressive strength exceeding 28 MPa. Part 1 results indicate that a fiber content of 0.1% by volume meets the specified requirements. In Part 2, it was observed that increasing the slag replacement percentage extended the initial printable time and time gap. However, even at a 30% replacement rate, the initial printable time remained within the acceptable range, partially attributed to the presence of fibers in the mix. Additionally, higher slag content led to increased flow and reduced filament height in the mixes. Notably, all formulations surpassed the 7-day compressive strength threshold. These findings underscore the potential of slag as a sustainable alternative to cement in 3D printing fiber-reinforced mortar, offering promising prospects for environmentally friendly construction practices. Doi: 10.28991/CEJ-2024-010-03-010 Full Text: PD
Ensemble Learning Models for Prediction of Punching Shear Strength in RC Slab-Column Connections
No full textIn reinforced concrete (RC) structures, accurate prediction of the punching shear strength (PSS) of slab-column connections is imperative for ensuring safety. The existing equations in the literature show variability in defining parameters influencing PSS. They neglect potential variable interactions and rely on a limited dataset. This study aims to develop an accurate and reliable model to predict the PSS of slab-column connections. An extensive dataset, including 616 experimental results, was collected from earlier studies. Six robust ensemble machine learning techniques”random forest, gradient boosting, extreme gradient boosting, adaptive boosting, gradient boosting with categorical feature support, and light gradient boosting machines”are employed to predict the PSS. The findings indicate that gradient boosting stands out as the most accurate method compared to other prediction models and existing equations in the literature, achieving a coefficient of determination of 0.986. Moreover, this study utilizes techniques to explain machine learning predictions. A feature importance analysis is conducted, wherein it is observed that the reinforcement ratio and compressive strength of concrete demonstrate the highest influence on the PSS output. SHapley Additive exPlanation is conducted to represent the influence of variables on PSS. A graphical user interface for PSS prediction was developed for users' convenience. Doi: 10.28991/CEJ-SP2024-010-01 Full Text: PD