2031 research outputs found
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Development of Machine Learning for Debris Flow Event Prediction in a Volcanic Area
No full textThe integration of machine learning (ML) into debris flow prediction in volcanic areas, exemplified by the Gendol River watershed of Mount Merapi, offers transformative potential for hazard mitigation. This study aimed to develop real-time, computationally efficient ML models capable of integrating multi-source data, rainfall intensity of 25 mm/hour linked to 300 cm Debris Flow heights, antecedent precipitation, and geomorphological variables to predict debris flows with actionable lead times. Key objectives included optimizing prediction accuracy, minimizing the false positive rate to 18.2% for "Debris Flow" events, and enhancing model interpretability for deployment in data-scarce volcanic regions. Results demonstrated that ensemble methods and deep learning architecture outperformed traditional models, with Efficient Logistic Regression and Linear SVM achieving an accuracy of 82.35%, and Cosine KNN attaining a prediction speed of 272 observations per second. Critical predictors included temporal rainfall patterns (contributing more than 50% to flow initiation) and ash deposit thickness (with a 70% influence on decision-making). However, challenges persisted: imbalanced datasets of nine training instances for "Debris Flow" events led to misclassification rates of 100% for hybrid events like "Rainfall and Debris Flow," while models like Naive Bayes exhibited instability (accuracy dropping to 50%). Research gaps highlighted data scarcity for high-magnitude events, limited geographic transferability, and the absence of standardized evaluation metrics. Technical limitations included reliance on low-resolution remote sensing data, high computational costs for ensemble models requiring 10 operational cost units, and the opacity of neural networks, which hindered stakeholder trust. Despite these constraints, ML models achieved 85% accuracy in non-event recognition and 76.47% precision in Bagged Trees, offering scalable frameworks for early warning systems. The study highlights the importance of enriched datasets, adaptive algorithms, and interdisciplinary collaboration in transforming volcanic risk management from a reactive approach, ultimately safeguarding vulnerable communities through data-driven, life-saving predictions
Compressive Strength and Acid Resistance of Fly Ash Based One-Part Geopolymer
No full textThis research studied the properties of one-part geopolymer mortar using a binder from high calcium fly ash. Sodium metasilicate (SM) and sodium hydroxide (SH) were used as solid alkali activators at ratios of 1:1 and 1:2. This study focused on the effect of the dosage and the solid ratio of the alkali activator from SM and SH for the potential to produce a one-part geopolymer. The compressive strength and corrosion resistance of mortar due to sulfuric acid and hydrochloric acid were investigated. The results showed that using a high amount of sodium metasilicate and sodium hydroxide could enhance the development of compressive strength. The fly ash-based one-part geopolymer using sodium metasilicate and sodium hydroxide (SM: NH) at a ratio of 1:1 at 18% achieved the highest compressive strength of 13.3 MPa at 60 days. For the acid attack, it was found that the fly ash-based one-part geopolymer mortar using SM: NH at a ratio of 1:1 had a lower weight change than a ratio of 1:2 after immersion in sulfuric acid. Meanwhile, the fly ash-based one-part geopolymer mortar with SM: NH at a ratio of 1:2 showed higher resistance to hydrochloric acid than at a ratio of 1:1
Effect of Dike Width on Pore Pressure and Water Content Evolution During Overtopping Conditions
No full textThe failure of dike embankments due to overtopping flow plays a crucial role in understanding the mechanisms behind dike erosion, which is essential for effective disaster mitigation. The "SLIDE" program was used to analyze the transient response of pore water pressure (PWP) and volumetric water content (VWC) within a homogeneous coarse sand bed. The authors have previously examined the use of seepage-control elements in 3D simulations of embankment breach failures due to overtopping, conducted in laboratory flumes at the University of Science of Malaysia. In this study, pore water pressure (PWP) and volumetric water content (VWC) were measured at various points beneath the crest and along both the upstream and downstream slopes for three different dike crest widths: 7 cm, 12 cm, and 18 cm. This paper also presents a factor of safety (FOS) analysis across the unsaturated–saturated zones within the dike embankment during the events of overtopping moments until full saturation of the downstream slope. The results indicate that increases in both PWP and VWC occurred across all test groups along the slopes. Narrower crest widths led to higher pore water pressure at the onset of overtopping, while wider crest widths resulted in increased pore pressure toward the end of the erosion process. A reduction in the factor of safety was observed along the crest and downstream slope. However, in dikes with wider crest widths, the length of the embankment decreased due to prolonged flow discharge through the downstream toe and remnants of the upstream slope. The transient flow and slope stability results provide new insights into the coupled hydromechanical behavior of dike soil during overtopping events
Evaluation of Fresh Properties of Cement Pastes: Part II-Modelling via Central Composite Design
No full textThis study investigates how variations in constituent materials affect the fresh properties of cement-based pastes using a statistically driven experimental approach. A Central Composite Design (CCD) was implemented to examine the influence of three key input parameters: water-to-cement ratio (w/c), superplasticizer-to-powder ratio (Sp/p), and water-to-powder ratio (w/p). Fifteen mix compositions were produced and tested using the mini-slump test and Marsh funnel flow time, both immediately after mixing and after 60 minutes. Response Surface Methodology (RSM) was applied to develop predictive models for each property. The results showed that the water-to-powder ratio was the most influential factor on workability, followed by the superplasticizer-to-powder ratio. The statistical models successfully captured main, interaction, and quadratic effects, enabling accurate prediction of flow and time measurements. These models were further used to optimize mix compositions according to targeted fresh-state performance. Compared with conventional one-variable-at-a-time approaches, the CCD method substantially reduces the number of tests required while providing deeper analytical insights. The proposed methodology improves the understanding of complex interactions among mix parameters and supports the efficient design of cement-based materials for performance-critical applications
An Exploration of PPP Infrastructure Projects’ Risks in Supporting Sustainable Development and SDGs
No full textIraq has initiated “Iraq Vision 2030” as a participation in the global efforts to attain sustainable development and the United Nations’ Sustainable Development Goals (SGDs). The private sector engagement in infrastructure development was adopted as a national goal. However, no serious accomplishment has been made. Accordingly, this research was conducted to explore risk factors affecting sustainable development in public-private partnership (PPP) infrastructure projects. 116 risk factors were identified through literature review; for proper assessment, monitoring, controlling, and management, they were classified into two groups. The first group includes risk factors that may appear at a specific stage of the PPP project lifecycle. The second group includes risk factors that may appear at any time along the PPP project lifecycle. A field study has been implemented in two stages; the first stage is an open questionnaire and face-to-face interview with PPP experts to finalize and approve proposed risk lists. The second stage is a closed questionnaire; the mean value was used to rank and identify respondents’ agreement on rating the level of importance of these risk factors supported by nonparametric tests. Findings indicated that the critical-level risks form nearly two-thirds of the overall and first-group risks and more than two-thirds of the second-group risks. Financial and fiscal sustainability concerns form a serious challenge, as they came in at the top of the critical-level risk factors. Overall findings indicate the importance of legislating a PPP law that serves the achievement of “Iraq Vision 2030” national goals and the UN’s SDGs and provides a comprehensive framework that protects citizens’ rights, ensures their well-being, and supports sustainable development
Adaptive Hydrodynamic Modeling for Sustainable Irrigation Management in Tidal Swamp Regions
No full textThe Lalan River functions as the primary water source and plays an important role in supporting irrigation systems and water management in tidal swamp areas. However, water management in this region still faces challenges such as salinity intrusion and unstable water distribution, while conventional approaches applied have not fully considered the hydraulic characteristics and hydrodynamic conditions of the waters. This study aims to analyze the hydrodynamic characteristics of the Lalan River as the main water system in the tidal swamp irrigation area of D.I.R. Karang Agung Hilir, Banyuasin Regency, South Sumatra Province, Indonesia, in order to design an effective water management strategy for agricultural irrigation. The research methods include bathymetry, tidal, current, and salinity measurements. Hydrodynamic modeling was applied to analyze aquatic phenomena, including flow dynamics and salinity distribution patterns in tidal swamp areas. The hydrodynamic model was calibrated and validated using field data with a Root Mean Square Error (RMSE) value of 0.170 m to ensure the reliability of the simulation. The analysis results show that the application of a one-way flow system can significantly reduce salinity, from around 2–5 ppt in the old system to around 1–2 ppt during high tide and below 0.5 ppt during low tide, or a reduction of up to ±60%. This reduction allows river water to be used more effectively for agricultural irrigation. The novelty of this research lies in the adaptive hydrodynamic approach based on seasonal hydrological conditions as a foundation for designing sustainable water management systems in tidal swamp areas according to the hydrotopography of the region
Comparative Life Cycle Assessment of Carbon Fiber and Nano-Silica Modified Asphalt Mixtures
No full textIn recent years, several studies have focused on enhancing the performance of asphalt mixtures using various additives; however, the environmental implications of these modifications have received limited attention. Accordingly, this study aims to evaluate the environmental impacts of asphalt mixtures incorporating carbon fiber (CF) and nano silica (NS) using the Life Cycle Assessment (LCA) methodology. In the current study, four mixtures were modelled and analyzed using SimaPro software: conventional asphalt mix (CAM), carbon fiber asphalt mix (CFAM), nano silica asphalt mix (NSAM), and carbon fiber–nano silica asphalt mix (CFNSAM). The assessment included the production cycle from raw material extraction to wearing surface installation, integrating laboratory performance data with the Ecoinvent v3.6 inventory. Results indicated that CAM exhibited the lowest environmental burden, whereas CFNSAM showed the highest impact resulting from the considerable energy inputs associated with carbon fiber fabrication. NSAM offered a balanced outcome, with moderate environmental impacts and satisfactory mechanical performance, positioning it as a more sustainable alternative. Overall, nano silica modification demonstrates promising potential for eco-efficient pavement applications
A Novel Exact Solution of Longshore Current and Its Application on Permeable Groin
Full text linkOne major environmental problem exacerbated by longshore currents is beach erosion. Groins are a common defense tactic built perpendicular to the shore. However, conventional impermeable groins promote downstream erosion and disrupt sediment movement. Permeable groins provide a more environmentally friendly option, allowing some sediment to flow through. This study examines the effects of permeable groins on longshore currents. Permeable groins are not included in currently used longshore current equations. This study fills this gap by creating a new longshore current velocity equation considering permeable groins. The longshore current equation with the groin was developed based on the momentum equation in the longshore direction without the influence of lateral mixing and the assumption that base friction will rise due to the groin. Therefore, it was determined that the base shear stress after the groin was equal to the base shear stress plus the drag caused by the groin. The result shows that the longshore current equation through the groin is a function of the breaking wave parameter and the resistance parameter owing to the groin. Longshore current velocities with and without permeable groins of different densities were measured in wave basins. We collected information on groin characteristics, current velocities, and breaking wave heights. This investigation validates the shortcomings of the current equations. Doi: 10.28991/CEJ-2025-011-02-07 Full Text: PD
Experimental Investigation of Single and Intermittent Light Non-Aqueous Phase Liquid Spills Under Dynamic Groundwater
Full text linkThe groundwater contamination from petroleum by-products represented in Light Non-Aqueous Liquid (LNAPL) under groundwater table fluctuations has become a serious environmental problem. For this reason, developing a rapid response strategy incorporating experimental characterization of LNAPL distribution trajectories is crucial for assessing the threats of LNAPL contaminants in the subsurface environment. In this study, the influence of various LNAPL spills in a porous medium under dynamic groundwater conditions was investigated using the Simplified Image Analysis Method (SIAM). Single and intermittent LNAPL (diesel) spills of total volume (400 and 800 ml) were examined in a river sand "Žtwo-dimensional tank (70 cm í— 70 cm í— 3.5 cm) under the effect of groundwater table fluctuation. The results indicated that the contaminant was distributed above h=28 cm in the 400 ml LNAPL spill. However, it migrated below h=28 cm, and its saturation reached 36% when the LNAPL volume raised to 800 ml. The LNAPL saturation in the case of four LNAPL intermittent spills was more evenly distributed through the tank depth than in the cases of a single spill of 800 ml and two intermittent spills of 400 ml. Furthermore, LNAPL migrated to a larger depth in the system (h=18.5 cm) only in the case of four LNAPL intermittent spills and under groundwater table fluctuation, which poses a significant threat to the groundwater. This study highlights the importance of the effect of various LNAPL spills under dynamic groundwater conditions, which can offer valuable guidance for developing remediation schemes. Doi: 10.28991/CEJ-2025-011-01-017 Full Text: PD
Seismic Assessment of First and Second Secant Stiffness for the Masonry Infilled RC Frame
Full text linkThe seismic resilience of composite concrete frame structures composed with masonry infill walls, is a critical research area due to its impact on structural performance during earthquakes. Most studies on reinforced concrete (RC) frames focus on key seismic response parameters like lateral strength and overall hysteretic behavior under cyclic loading, often analyzing the first and second secant stiffness throughout the seismic loading process. The present study examines the first and second secant stiffness as the structural performance during earthquake. A series of experimental tests are performed on half scaled RC frames filled with autoclaved aerated concrete (AAC) block masonry with external dimensions of 1.5 m x 1.5 m. These frames are subjected to displacements ranging from 2 mm to 6 mm and frequencies between 1 Hz and 7 Hz for simulating earthquake loading conditions. The experimental program aimed to evaluate the resistance of structure to earthquake loading by using dual mode of testing viz. displacement and frequency-controlled loading protocol. During test the RC frame responded elasto-plastically due to minor cracking at block joints and localized yielding at the interface between the frame and the infill at lower frequencies and displacements. Conversely the degradation of both first and second secant stiffness values became more pronounced at higher frequencies. The first secant stiffness decreased by 73.4%, while the second secant stiffness showed increase of 24.6% at a displacement of 4 mm and a frequency of 4 Hz with respect to the previous loading cycle which indicated the complex stress redistribution and temporary stabilization. Doi: 10.28991/CEJ-2025-011-02-05 Full Text: PD