Value Of Safety Factor Research Articles

Prediction of fishbone linear instability in tokamaks with machine learning methods

Abstract A machine learning based surrogate model for fishbone linear instability in tokamaks is constructed. Hybrid simulations with the kinetic-magnetohydrodynamic (MHD) code M3D-K is used to generate the database of fishbone linear instability, through scanning the four key parameters which are thought to determine the fishbone physics. The four key parameters include (1) central total beta of both thermal plasma and fast ions, (2) the fast ion pressure fraction, (3) central value of safety factor q and (4) the radius of q = 1 surface. Four machine learning methods including linear regression, support vector machines (SVM) with linear kernel, SVM with nonlinear kernel and multi-layer perceptron are used to predict the fishbone instability, growth rate and real frequency, mode structure respectively. Among the four methods, SVM with nonlinear kernel performs very well to predict the linear instability with accuracy ≈ 95 % , growth rate and real frequency with R 2 ≈ 98 % , mode structure with R 2 ≈ 98 % .

Parametric Study of Rainfall-Induced Instability in Fine-Grained Sandy Soil

This study investigates the stability of fine-grained sandy soil slopes under varying rainfall intensities, durations, and geotechnical properties using a parametric analysis within GeoStudio. A total of 4416 unique parameter combinations were analyzed, incorporating variations in unit weight, cohesion, friction angle, slope inclination, slope height, rainfall intensity, and duration. Results reveal that rainfall intensity is the most influential variable on the factor of safety (FS), with higher intensities (e.g., 360 mm/h) on steeper slopes (e.g., 45°) leading to critical FS values below 1, indicating an imminent risk of failure. Under moderate conditions (e.g., 9 mm/h rainfall on slopes of 26.6°), the FS remains above 2. This dataset provides a valuable foundation for training machine learning models to predict slope stability under diverse environmental conditions, contributing to the development of early warning systems for rainfall-induced landslides.

Application of Capillary Barrier Systems for Slope Stabilization Under Extreme Rainfall: A Case Study of National Highway 10, India

Global warming has led to an increase in extreme rainfall events, which often result in landslides, posing significant threats to infrastructure and human life. This study evaluated the effectiveness of the Capillary Barrier System (CBS) in enhancing slope stability along a vulnerable section of India’s National Highway 10 (NH10) during maximum daily rainfall. The GEOtop model was employed to conduct water balance simulations and obtain the pore–water pressure (PWP), which was then used to calculate the Factor of Safety (FoS). Results showed that CBS effectively delayed the rise in PWP, leading to lower peak values and smaller areas of very high and high risk levels. Spatial distribution mapping further confirmed that CBS minimized very high risk zones. At three historical landslide points, CBS slopes generally maintained FoS values above 1, demonstrating enhanced stability and improved resilience to extreme rainfall. These findings highlight the potential of CBS as a viable strategy for slope reinforcement in regions susceptible to heavy rainfall.

Numerical study of turbulent eddy self-interaction in tokamaks with low magnetic shear. Part I: Linear simulations

Abstract This study examines the impact of low and zero magnetic shear, along with rational values of safety factor, on linear mode behavior in tokamak plasmas. We focus on how magnetic field line topology and parallel domain length influence linear mode structures and growth rates as magnetic shear decreases. Our results
show that as magnetic shear is reduced to low values, linear modes can transition between different branches, significantly affecting their characteristics. At zero magnetic shear, accurate modeling requires precisely capturing magnetic topology, as small deviations near rational surfaces can greatly impact growth rates. These findings are extended to nonlinear simulations in a companion paper (Volčokas, 2024), revealing that long turbulent eddies and magnetic field line topology play a crucial role in turbulence self-interaction and plasma transport.

Numerical Investigation of the Slope Stability in the Waste Dumps of Romanian Lignite Open-Pit Mines Using the Shear Strength Reduction Method

Open-pit mining generates significant amounts of waste material, leading to the formation of large waste dumps that pose environmental risks such as land degradation and potential slope failures. The paper presents a stability analysis of waste dump slopes in open-pit mining, focusing on the Motru coalfield in Romania. To assess the stability of these dumps, the study employs the Shear Strength Reduction Method (SSRM) implemented in the COMSOL Multiphysics version 6 software, considering both associative and non-associative plasticity models. (1) Various slope angles were analyzed, and the Factor of Safety (FoS) was calculated, showing that the FoS decreases as the slope angle increases. (2) The study also demonstrates that the use of non-associative plasticity leads to lower FoS values compared to associative plasticity. (3) The results are visualized through 2D and 3D models, highlighting failure surfaces and displacement patterns, which offer insight into the rock mass behavior prior to failure. (4) The research also emphasizes the effectiveness of numerical modeling in geotechnical assessments of stability. (5) The results suggest that a non-associative flow rule should be adopted for slope stability analysis. (7) Quantitative results are obtained, with small variations compared to those obtained by LEM. (6) Dilatation angle, soil moduli, or domain changes cause differences of just a few percent and are not critical for the use of the SSRM in engineering.

Investigation of landslide triggers on Mount Oku, Cameroon, using Newmark displacement and cluster analysis

BackgroundThe landslide inventory of the western flank of Mount Oku, Cameroon, includes spreads or complex landslides, indicating sudden soil weakening, possibly due to seismic activity or heavy rainfall causing groundwater rise. These landslides were likely triggered between 2009 and 2018 based on the dates of the aerial imagery. Identifying triggers for past landslides remains a major unresolved issue in landslide science. However, understanding these triggers is crucial for accurately assessing future landslide hazards.MethodologyIn this paper, we investigate the possibility of earthquakes to precondition landslide development or reactivation during climatic events. By assuming a magnitude 5.2 earthquake, an epicenter of 10 km from this area, and different wetness conditions, the factor of safety (FS) and Newmark displacement (ND) models were calculated for shallow and deep-seated landslides with sliding depths of 3 and 7.5 m. Afterward, the relationship between FS, assumed ND, and observed landslides was analyzed in a cluster analysis, to derive patterns of climatically and seismically triggered landslides.ResultsThe comparison of FS maps and FS values of the observed landslides revealed that especially for landslides at 7.5 m depth, most sites that are stable during dry conditions become instable under saturated conditions, indicating a climatic trigger. At 3 m depth, however, some landslide sites that are still marginally stable under saturated conditions, display relatively high ND values for the investigated hypothetical earthquake, indicating a possible seismic influence. In the cluster analysis, we clustered the observed landslides according to their distances to rivers and topographic ridges and obtained three clusters. Landslides from cluster 3 with 31% of the landslides display medium to high ND for the assumed earthquake, and were found near ridges and farther away from rivers, suggesting seismic triggering. Cluster 2, with 12% of landslides closer to rivers, suggested climatic origins. Thus, while climate is a critical landslide contributing factor, seismic events may also contribute, either by predisposing to landslides or by reactivating them alongside climatic factors. These results enable the establishment of more precise and effective landslide mitigating measures considering mostly rainfall but also earthquakes as possible triggers.

Coal Mine Slope Stability Analysis Using the Rock Mass Rating (RMR), Slope Mass Rating (SMR) Method, and Morgenstren-Price Limit Equilibrium for the Low Wall Pit Area Y PT. Bina Sarana Sukses, Lahat Regency, South Sumatra

Open pit mining has a complex connection to excavation and stockpiling operations, which can potentially induce slope instability. The analysis of slope stability is crucial to prevent slope failure, which has the potential to result in major losses. The study on slope stability was performed at the low wall pit Y area of PT. Bina Sarana Sukses site MAS in Lahat Regency. This research aimed to analyze the rock mass classifications, determine the safety factor values, and provide recommendations for mitigating landslide occurrences. The techniques employed in this study include the RMR and SMR methods for assessing the susceptibility of landslides, collectively with the Morgenstern-price limit equilibrium approach for estimating the stability of the slope. Based on the analysis of the rock mass rating (RMR) and slope mass rating (SMR), Block B2 exhibits a 20% likelihood of experiencing landslides, specifically due to block joint characteristics. On the other hand, Blocks B4 and B5 show a 40% potential for landslides, primarily associated with flat or wedge-type block joints. The force produced by friction under saturated conditions is comparatively lower than that observed under dry conditions. During the final design phase in 2022, it was observed that Blocks B4 and B5 exhibit critical and dangerous safety factors when saturated. Hence, the proposal has been suggested to enhance slope stability. Further, it is recommended to monitor the geotechnical piles periodically. We hope this research results as a valuable resource for evaluating and assessing slope stability, including artificial and natural slopes.

Application of limit equilibrium and shear strength reduction techniques for stability assessment of slope cuts- A case study of Khalid-Dijo dam project, Southern Ethiopia

Dam failure can occur due to foundation instability, downstream and upstream slopes instabilities. This study assesses the stability of upstream and downstream slope cuts at Khalid-Dijo irrigation dam project, which is located in Southern Ethiopia, 3km south of Werabe town. Limit equilibrium and finite element shear strength reduction methods are adopted. Validation of results and comparisons between those methods are carried out. The analysis considers anticipated site conditions, including static dry, static saturated, dynamic dry and dynamic saturated conditions. Slope material properties are measured from insitu, laboratory tests and used as input parameters for the analysis to obtain factor of safety and critical strength reduction factors. The properties considered in the analysis include unit weight, cohesion, angle of internal friction, poison’s ratio, dilation angle and Young’s modulus. The analysis indicates that the factor of safety values for limit equilibrium methods and the critical strength reduction factor for finite element method are very similar across the three slope cuts under all anticipated conditions. The lowest factor of safety and critical strength reduction factor is 1.56 and 2.07 respectively. Generally, the proposed dam project is safe against upstream and downstream slope failures. These studies suggest that maintained the average safety factor values of both methods during the design stage are crucial to avoid unnecessary risk.

Slope Stability Analysis Throughout Road Around Bukit Barisan Selatan National Park (BBSNP) using Fellenius Method

Bukit Barisan Selatan National Park (BBSNP) is a nature conservation area in Indonesia. The slope stability of the interprovincial roads in BBSNP needs to be assessed for slope stability. This study assesses slope stability using the Fellenius method for the factor of safety calculation. The data utilized consists of geological and structure regional conditions, soil descriptions, soil physical and mechanical properties, water content, liquid limit, plastic limit, plasticity index, specific gravity, soil strength, slope dimensions, and slope weight. The sampling process is conducted un-disturb, followed by laboratory testing. The laboratory tests conducted include soil elasticity and plasticity, soil cohesion, and internal friction angle. The critical slopes at LT-L01 and LT-L23 are compromised due to the low cohesion values, making both slopes susceptible to landslides. The stable slope at LT-R04, LT-L15, LT-L19, and LT-R30 exhibit variability properties across the slopes. The lithology for slope LT-R04 consists of inorganic clay with high plasticity, slopes LT-L15 and LT-R30 have same lithology of silty clay with medium plasticity, while slope LT-L19 has lithology of silty clay with low plasticity. The safety factor values indicate stability due to moderate - high cohesion, contributing to slope stability. Material compaction is required to enhance cohesion values on the slopes. Additionally, need to mitigate water saturation conditions in the slope materials.

Safety Factor Analysis on the Stability of the Retaining Wall Structure in Cimahi City, Indonesia

Retaining wall is a construction built to hold the ground on the slopes. Retaining wall can be said to be safe if its safety factors have been taken into account.In this study will be calculated the security factor based on SNI 8640:2017 on the location to be built retaining wall located in the area of Cimahi City, West Java using the help of software with two-dimensional finite element method.Based on the soil type map, the majority of the Cimahi City area consist of Tuffaceous Clay and Sandy Clay soils, which are alluvial fan deposits of volcanic origin, with soil thickness ranging from 1 m to 5 m. Retaining wall structures using cyclopean concrete appear to be slimmer compared to those using stone masonry. The use of dolken wood piles as additional reinforcement in locations using cyclopean concrete can strengthen the structure on the sliding plane, thus preventing overturning. Based on the modeling, the use of this structure resulted in a safety factor value greater than 1.5, with a displacement of 20 cm.

Spirodiclofen toxicity in Tetranychus urticae and safety to natural enemies Proprioseiopsis asetus and Amblyseius swirskii

Proprioseiopsis asetus and Amblyseius swirskii are excellent natural enemies of plant-feeding mites and small pests. In order to clarify the safety of the acaricide spirodiclofen to the predatory mites P. asetus and A. swirskii, here, we investigated the toxicity of the acaricide on the pest mite T. urticae (nymphs and adult females) and on both species of predatory mites, P. asetus and A. swiskii (eggs, nymphs, and female adults) by using the spray, slide-dip, and leaf residual toxicity methods, compared the selective toxicity and assessed the safety to these natural enemies. The results demonstrated that the corrected mortality in P. asetus and A. swirskii female adults was <5% at recommended spirodiclofen concentrations in the spray method. In the leaf residual toxicity method, P. asetus and A. swirskii egg-hatching rates did not differ significantly from the pure water control group. In the slide-dip method, spirodiclofen lethal concentration 50 (LC50) in P. asetus and A. swirskii female adults was noted to be 9,494.875 and 3,064.187 mg·L−1, respectively. In the spray method, spirodiclofen LC50 in P. asetus and A. swirskii nymphs was found to be 4,292.664 and 1,081.609 mg·L−1, respectively, and that in T. urticae female adults and nymphs was 55.189 and 40.862 mg·L−1, respectively. Spiroclofen selective toxicity ratios (STRs) in P. asetus female adults–T. urticae and P. asetus nymphs–T. urticae were 172.013 and 105.053, respectively, indicating that spiroclofen has a high positive selectivity toward the pest T. urticae and its natural enemy P. asetus. In contrast, spiroclofen STRs in A. swirskiis female adults–T. urticae and A. swirskiis nymphs–T. urticae were 55.522 and 26.470, respectively, indicating spiroclofen has a moderate positive selectivity toward the pest T. urticae and its natural enemy A. swirskii. In the safety evaluation, the spirodiclofen safety factor for P. asetus female adults and nymphs was 158.248–237.37 and 71.544–107.317, respectively, whereas that for A. swirskii female adults and nymphs was 50.070–76.605 and 18.027–27.040 respectively. All spirodiclofen safety factor values were much higher than 5, indicating that spirodiclofen is highly safe for P. asetus and A. swirskii; in particular, spirodiclofen is safer for P. asetus than for A. swirskii.

Effect of toroidal mode coupling on explosive dynamics of m/n = 3/1 double tearing mode

The CLT code was used to quantitatively study the impact of toroidal mode coupling on the explosive dynamics of the m/n = 3/1 double tearing mode. The focus of this study was on explosive reconnection processes, in which the energy bursts and the main mode no longer dominates when the separation between two rational surfaces is relatively large in the medium range. The development of higher m and n modes is facilitated by a relatively large separation between two rational surfaces, a small q min (the minimum value of the safety factor), or low resistivity. The relationships between the higher m and n mode development, explosive reconnection rate, and position exchange of 3/1 islands are summarized for the first time. Separation plays a more important role than q min in enhancing the development of higher m and n modes. At a relatively large separation, the good development of higher m and n modes greatly reduces the reconnection rate and suppresses the development of the main mode, resulting in the main mode not being able to develop sufficiently large to generate the position changes of 3/1 islands.

Optimal mine pitwall profiles in jointed anisotropic rock masses

ABSTRACT A new methodology based on the limit analysis upper bound method for the topological optimisation of slopes is presented, to determine geotechnically optimal slope profiles in anisotropic jointed rock masses. The methodology accounts for the effects of discontinuities such as joints, bedding planes, and tension cracks. We applied this methodology to the context of open pit mines, with the goal of achieving geotechnically optimal pitwall profiles. The optimal profiles maximise the Overall Slope Angle (OSA) while maintaining a prescribed Factor of Safety (FoS) and satisfying the geometric constraints imposed by benches and ramps. The method, implemented in the software OptimalSlope, utilises direction-dependent cohesion and internal friction angle parameters to replicate the effect of joints on slope stability. Key inputs include joint orientation, non-persistence, and probability of occurrence. We tested the methodology on a Mexican open pit mine to be excavated into Cretaceous siltstone featuring eight different joint sets and a primary bedding plane. Optimal pitwall profiles were determined for various combinations of bedding dip angles (0°, 15°, 30°, 45°, 60°, 75°, 90°) and mine pitwall orientations (hanging wall, footwall, side walls), considering the three-dimensional kinematics of the joints through anisotropic functions of cohesion and friction angle. Results indicate that the optimal pitwall profiles generally exhibit higher OSA compared to planar profiles with the same FoS, except in one bedding dip direction. Additionally, stability analyses performed using Rocscience Slide2 independently verified the FoS values of the optimal profiles.

An Analysis of the Slope Stability of Young Rock Cliffs in Sibang, Bali Using GEO5

This study presents a comprehensive analysis of slope stability for young rock cliffs in the Sibang region of Bali, employing advanced geotechnical software GEO5. The investigation is crucial due to the dynamic geological conditions and rapid changes in land use in the area, posing potential risks to infrastructure and environmental stability. The research focuses on young rock cliffs, characterized by recent geological formations, which are inherently susceptible to slope instability. This slope stability analysis is carried out using the GEO5 auxiliary program which will produce a Safety Factor value which is used as the basis for building a construction which interprets whether the slope is safe or not. The safety factor value used as the minimum value is 1.5, so the slope must have a SF value ≥ SF min = 1.5. This analysis was carried out on 4 cross sections with 2 method which name is Morgenstern-Price and Bishop Method because the analysis carried out was complex in terms of force and moment. The Safety Factor of cross section on BH-03 to BH-01 is not safe because the value is 1,16 and 1,15 which is < 1,5 (the minimum safety factor). Therefore, the slope must modelled with terraced slopes and also retaining wall reinforcement for each modelled terrace height.

Technical Feasibility of a Two-Cylinder Entablature Steam Engine with a Parallel Motion Crosshead: An Analysis from Mechanical Engineering

In this research, we present the results of analyzing the technical feasibility of an old invention by Henry Muncaster from the perspective of mechanical engineering, specifically focusing on the resistance of materials. The invention is a two-cylinder steam engine with a parallel motion crosshead, for which plans were published in the Model Engineer magazine in 1957. This complex device, composed of 76 elements and lacking descriptive information, has been the subject of a recent article that illustrated its design through the engineering drawing discipline and a 3D CAD model. To provide reliable information and conduct a comprehensive study of its technical feasibility, an extensive linear static analysis was performed. This analysis considered two critical positions of the piston inside the cylinder: upper dead center and lower dead center. We determined the optimal range of working pressures necessary to achieve a safety factor within the optimal design range of two to four. The results include von Mises stresses, displacements, and safety factor distributions, confirming that the optimal working pressure range for steam intake is between 1.885 and 3.550 MPa. This ensures that the safety factor values remain between 2.01 and 3.78.

ELGO electric motorcycle: Design and analysis of trail-type electric motorcycle frame using finite element analysis

The frame is an important part of the motorcycle as it carries the load of the passenger. Therefore, it is necessary to design a frame that can withstand the load and is lightweight. A lighter motorcycle will reduce the power required to ride it. This research aims to redesign the frame of a trail-type ELGO electric motorbike by considering a reduction in frame weight. The research was carried out using finite element analysis. The data from the analysis were checked based on the maximum stress not exceeding the yield strength of the DIN 1.0030 material and the safety factor greater than 1. The results showed that the newly designed frame has a lighter weight, with a maximum stress less than the yield strength of the DIN 1.0030 material and a safety factor value greater than 1. The simulation results also indicate the potential for further research by showing the maximum and minimum stress areas on the frame.

Analisis Penggunaan Tanaman Vetiver terhadap Stabilitas Lereng pada Bendungan Way Sekampung

Problems that occur in the western part of As Way Sekampung have the potential for landslides to occur. Efforts used to handle slope strengthening by planting vetiver plants. The research method used to analyze slopes uses the limit equilibrium method on slip surface sections using the Morgenstren-Price method with the help of Geostudio 2023.1.0 software. SLOPE/W to get the safety factor under normal conditions and under seismic load conditions. By using a seismic load with a return period of 500 years (PE 10% in 50 years) with a Peak Ground Acceleration (PGA) value for the Way Sekampung Dam inundation area of 0,265 g. In vetiver plants, the root depth is simulated according to the top soil depth of 0,0 – 0,1 m. Soil planted with vetiver plants experienced an increase in the value of cohesion (c) by 74,42% and a decrease in the value of the angle of internal friction (φ˚) by 49,40%. The conclusion obtained was that slope stability in normal existing conditions was 4,525 and in normal vetiver plant strengthening conditions the safety factor increased to 4,529. Then, in the existing seismic conditions, the safety factor is 2,624 and in strengthening vetiver plants with seismic loads, the safety factor value increases to 2,626. It can be concluded that vetiver plants are able to strengthen slope conditions.

Correction: The optimal values of Greenwald density limit and plasma safety factor in inductive and non-inductive operation modes

Correction: The optimal values of Greenwald density limit and plasma safety factor in inductive and non-inductive operation modes

Design and Analysis of Finger Prosthetics Using Finite Element Methods

According to the Central Statistics Agency (BPS), the total number of physically disabled people in Indonesia until 2020 reached 22.5 million people. However, only around 18% use assistive devices. 3D printing technology in the world of health can be used to print prosthetic materials. However, many previous functional prosthetic designs were still fabricated conventionally and did not pay attention to prosthetic standards and quality. One computational testing method that can be used to test prosthetic strength is the finite element method. The aim of this research is to produce a functional finger prosthetic design that has tested its strength through computational simulations using the finite element method to minimize prosthetic production costs so that the resulting prosthetics are more affordable.The tools needed in this research are a ruler for finger measurements and a computer or laptop with Fusion 360 software.Based on the analysis results, it shows that this model is able to withstand loads of up to 100 N with deformation, stress and safety factor values produced respectively of 0.016 mm, 27,605 MPa and 7.49.

Seroja Tropical Cyclon Destruction Case Study: Permanent Slope Protection Evaluation at Downstream of Rotiklot Dam Nomenclature Building, East Nusa Tenggara, Indonesia

Abstract Rotiklot Dam was one of some infrastructures which was affected by the Seroja Tropical Cyclone in East Nusa Tenggara Indonesia in April 2021. There are several landslides at the downstream of the dam that can threaten the safety of the dam, especially at the downstream of the nomenclature building. The right design of permanent slope protection must be determined in a limited time. Geotechnical investigations such as boring, resistivity survey, standard penetration test, and water pressure test were conducted in a short time. Back analysis method was carried out to find extreme soil parameters conditions. The slope protection must meet the national standard minimum safety factor or greater than 1.5. Safety factors of slope protections are evaluated by a finite element method to get the safety factor and maximum total displacements. Every stage of slope protection can give the optimal safety factor values which are required or greater than 1.5, however backfill material will give more load and decrease the safety factor value.