Safety Factor Research Articles

A two-step dynamic FEM-FELA approach for seismic slope stability assessment

AbstractThe determination of the factor of safety (FoS) of slopes during seismic excitation can be complex if the relevant effects of pore water pressure accumulation, nonlinear material response and variable shear strength are duly accounted for. A rational two-step approach to tackle this task based on a hydro-mechanically coupled dynamic simulation and finite element limit analyses is henceforth introduced. To ensure accurate transfer of the hydro-mechanical soil state, a mapping concept is presented, accounting for spatial distributions of stresses, excess pore water pressures, inertial forces and shear strength. The proposed approach is compared to limit equilibrium method (LEM) for the case of a large-scale water-saturated open cast mine slope subjected to seismic loading. In comparison with LEM, the new approach to assess seismic slope stability proves to be simpler in its implementation and straightforward, which could be an important asset for practitioners.

Internet of things assisted deep learning enabled driver drowsiness monitoring and alert system using CNN-LSTM framework

Abstract Driver fatigue has been generally viewed as a critical road safety factor and has been cited for contributing to a good percentage of traffic accidents. Developing systems to monitor and alert drowsy drivers is essential in reducing incidents. This research proposes a robust framework for driver drowsiness detection using a CNN-LSTM architecture developed by fusing facial landmark analysis with multiple aspect ratios. It uses, as key metrics in detecting drowsiness, the Eye Aspect Ratio (EAR), Pupil Circularity (PUC), the Mouth Aspect Ratio (MAR), and the Mouth over Eye Aspect Ratio (MOE). CNN-LSTM had been trained on YawDD, NITYMD, FL3D, and custom datasets. Data augmentation techniques such as flipping, scaling, shearing, rotation, brightness and contrast adjustment are used to generalize under different illumination conditions and driver postures. The system is implemented on NVIDIA’s 128-core Jetson Nano GPU platform and does real-time processing of video frames captured by a CSI camera. It detects eye closure and yawning as symptoms of driver fatigue and immediately raises an alert through vibrations in the seatbelt and pre-recorded voice messages. The Internet connectivity allows remote monitoring via mobile applications, making it safer by ensuring that alerts reach the driver and passengers. This CNN-LSTM model has been carefully tested for various scenarios, including day and night conditions, proving its effectiveness. The proposed framework indicated excellent performance concerning accuracy (98%), precision (95%), recall (93%), F1 score (94%), and AUC (99%), thereby revealing its efficiency in practical scenarios. By incorporating EAR, MAR, PUC, and MOE for the early detection of drowsiness in this CNN-LSTM architecture, the system will be able to alert the driver ahead of time so that necessary precautions can be taken to avoid an accident. The proposed approach enhances the driver's safety and is a scalable solution that adapts to different environments and populations.

Thermal-hydraulic and safety analysis of alternative ceramic fuels in next generation of VVER-1000 reactor

Abstract The main aim of this study is the thermohydraulic and safety analysis of alternative UN and UC ceramic fuels in the next generation of VVER-1000/V446 reactor core. One of the advantages of these alternative fuels is their higher thermal conductivity and density relative to the UO2 conventional fuels. Thermohydraulic analysis has been performed under full power conditions. Also, the safety evaluation of alternative ceramic fuels has been researched by the Rod Ejection Accident (REA) scenario. RELAP5 Mod3.2 code is used for thermo-hydraulic analysis in both steady state and transient state in VVER-1000/V446 reactor. In addition, calculations of the fuel center temperature in mean and hot channels for steady state, the temperature of the hottest rod in the fuel assembly, the radial distribution of fuel temperature for both channels, and the maximum clad temperature during the reactivity injection have been performed. The results showed that in the steady state with full power, the fuel centreline temperature in UO2 is about twice the corresponding values for UN and UC alternative fuels which is very attractive from a safety point of view. In general, due to the large difference between the hot spot point and the melting point in alternative fuels, the thermal power and safety factors can be significantly increased in the next generation of VVER-1000/V446 reactors.

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.

Investigation into the Suitability of AA 6061 and Ti6Al4V as Substitutes for SS 316L Use in the Paraplegic Swivel Mechanism

SS 316L, a low-carbon 316 Stainless Steel, has been used to manufacture swivel mechanisms for paraplegic patients, but its weight is relatively high compared to a few materials in its range of properties. Aluminum alloy 6061 and Titanium alloy (Ti6Al4V) offer lightweight and incredible strength-to-weight ratio, hence their use for medical, aerospace, and automotive applications. This study, therefore, seeks a replacement for SS 316L. A 3D model of a swivel mechanism was developed to compare the performance of the swivel mechanism made with SS 316L, AA 6061, and Ti6Al4V. The kinematic analysis of the mechanism based on a range of weights: 1kN, 1.1 kN, 1.2 kN, 1.3 kN, 1.4 kN, and 1.5 kN was carried out to generate the inputs for the simulation. The 3D model was made with SolidWorks, and the results of the kinematic analysis were used to define the simulation parameters for the mechanism. Two scenarios generated depicted the full collapse of the mechanism and the full extension. The results showed that AA 6061 and Ti6Al4V outperformed SS 316L with higher yield strength and factor of safety. Therefore, swivel plates made with AA 6061 and Ti6Al4V have higher yield strength than those made with SS 316L, adding to the advantage that they have a higher strength-to-weight ratio. From this analysis and known knowledge of the cost of these materials, the optimal replacement considering cost with yield strength is AA 6061. However, Ti6Al4V is a better alternative for the strength-to-weight ratio for SS 316L.

Numerical study of runaway current impact on sawtooth oscillations in tokamaks

Abstract This study investigates the influence of runaway current in runaway plasmas on the dynamics of sawtooth oscillations and resultant loss of runaway electrons (RE) using the 3D magnetohydrodynamic (MHD) code M3D-C$^{1}$ (Jardin {\it et al} 2012 {\it J. Comput. Sci. Discovery} {\bf 6} 014002). Using an HL-2A-like equilibrium, we confirm that in the linear phase, the impact of REs on resistive internal kink instabilities is consistent with previous research.
In the nonlinear phase, as the runaway current fully replaces the plasmas current, we observe a significant suppression of sawtooth oscillations, with the first sawtooth cycle occurring earlier compared to the case without runaway current. Following the first sawtooth collapse, plasma current density, runaway current density, and safety factor ($q$) flatten within the $q=1$ surface, albeit displaying fine structures. Subsequently, the growing high torodial ($n$) and poloidal ($m$) mode number modes disrupt the magnetic surfaces, leading to the loss of REs outside the $q=1$ surface, while minimally affecting the majority of REs well-confined within it. Thus, in the current model, the physical processes associated with the presence of sawtooth oscillations do not effectively dissipate runaway current, as REs are assumed to be collisionless. In addition, the final profile of runaway current density exhibits increased steepening near the $q=1$ surface in contrast to the initial profile, displaying a distinctive corrugated inhomogeneity influenced by the growing fluctuation of the $n=0$ component. Finally, detailed convergence tests are conducted to validate the numerical simulations.

Improvements to the bonding condition of ultra-thin concrete overlays for airport rigid pavements

ABSTRACT Ultra-thin concrete overlay (UTO) is an effective solution for repairing functional deficiencies in airport rigid pavements, with interface bonding properties critical to pavement performance and longevity. This study systematically investigates methods to enhance UTO interface bond strength under heavy dynamic loads. Aircraft dynamic simulations were performed to analyze stress states during landing, taxiing, and turning, identifying the required ultimate bond strength to prevent interface failure. Laboratory tests measured the shear and pull-out strengths of new and old concrete interfaces. A styrene–butadiene rubber (SBR) modified cement quartz mortar adhesive was developed with optimal curing conditions, and the effects of grooving intervals on bonding strength were assessed. Results demonstrated that the interface treatment increased the safety factor for tensile failure from 0.69 to 1.25 and for shear resistance from 0.61 to 1.12 under dynamic loads. This research provides a scientific basis for enhancing UTO applications in the functional rehabilitation of airport rigid pavements, offering a practical solution to improve safety and durability in high-stress environments.

Analysis of the Liquefaction Potential at the Base of the San Marcos Dam (Cayambe, Ecuador)—A Validation in the Use of the Horizontal-to-Vertical Spectral Ratio

Ground liquefaction potential analysis is a fundamental characterization in areas with continuous seismic activity, such as Ecuador. Geotechnical liquefaction studies are usually approached from dynamic penetration tests, which pose problems both in their correct execution and in their evaluation. Our research involves analyzing dynamic penetration tests and microtremor geophysical surveys (horizontal-to-vertical spectral ratio technique, HVSR) for analyzing the liquefaction potential at the base of the San Marcos dam, a reservoir located in Cayambe canton (Ecuador). Based on the investigations performed at the time of construction of the dam (drilling and geophysical refraction profiles) and the application of 20 microtremor observation stations via the HVSR technique, an analysis of the safety factor of liquefaction (SFliq) was conducted using the 2001 Youd and Idriss formulation and the values of the standard penetration test (SPT) applied in granular materials (sands). In addition, the vulnerability index (Kg) proposed by Nakamura in 1989 was analyzed through the HVSR records related to the ground shear strain (GSS). The results obtained in the HVSR analysis indicate the presence of a zone of about 100 m length in the central part of the foot of the dam, whose GSS values identified a condition of susceptibility to liquefaction. In the same area, the SPT essays analysis in the P-8A drill hole also shows a potential susceptibility to liquefaction in earthquake conditions greater than a moment magnitude (Mw) of 4.5. That seismic event could occur in the area, for example, with a new activity condition of the nearby Cayambe volcano or even from an earthquake from the vicinity of the fractured zone.

Non-disruptive error field measurement in DIII-D low safety factor plasmas and projection to ITER

Abstract Previous experiments in DIII-D (Paz-Soldan et al 2022 Nucl. Fusion 62 126007) introduced a method to identify intrinsic error fields (EFs) in tokamaks with minimal disruption risk by promptly healing driven magnetic islands during the conventional ‘compass scan’. This paper presents recent experimental and numerical advancements in extending this approach to low q 95 plasmas, and projects its applicability to ITER. Non-disruptive EF measurement is achieved at q 95 = 4.5 and 3.9 without any initial EF correction (EFC) by reducing the time between the occurrence of the locked mode (LM) and control action to 10 ms and increasing the density 50%–100%. However, 50% correction of the intrinsic EF is required to achieve island healing at q 95 = 3.2 with 10 ms delay for the control action. Nonlinear two-fluid modeling with the TM1 code reproduces the DIII-D experimental observations, indicating that promptly turning off the 3D coil current reduces both magnetic island width and electromagnetic force, while raising the density increases plasma viscosity, facilitating magnetic island healing. The simulations show that for scenarios with q 95 = 3.2, lowering the control action time to 5 ms will lead to island healing without EFC. TM1 simulations are extended to future ITER scenarios with 5 MA and 7.5 MA plasma currents, predicting the dependence of required density rise on action time and EF amplitude. These simulations indicate that, benefiting from the much longer resistive time, island healing can be successfully achieved in ITER when taking control action 100–500 ms after a LM occurrence.

Effect of ion temperature anisotropy on ITG mode in reversed field pinch plasmas

Abstract The Ion Temperature Gradient (ITG) mode instability in the Reversed-Field-Pinch (RFP) plasmas with anisotropies in ion temperature and its gradient, is studied for the first time using the gyrokinetic integral eigen-mode equation. Detailed numerical results indicate that ITG instability is reduced by ion temperature anisotropy, specifically when the temperature is higher in the direction perpendicular to the magnetic field or sufficiently high in the direction parallel to the magnetic field, with Landau damping playing a significant role. Moreover, the driving force of the ion temperature gradient in the parallel direction for the ITG mode is stronger than that in the perpendicular direction, particularly when the parallel ion temperature is higher. In addition, the study provides detailed insights into the synergistic effects of ion temperature anisotropy with magnetic shear, poloidal wave number, safety factor, and density gradient on ITG mode. It also elucidates the threshold of the ion temperature gradient necessary for mode excitation.

Antibacterial mechanism analysis of resveratrol against Salmonella typhimurium via metabolomics.

Salmonella, a common pathogenic bacterium in food, can have a severe impact on food safety and consumer health. At present, Salmonella infection is controlled primarily by the use of antibiotics, which creates unsafe factors for food safety. Thus, finding a natural antibacterial agent is highly practical. In this study, resveratrol was screened from 17 kinds of polyphenols, and its inhibitory mechanism and effects on metabolites of Salmonella typhimurium were investigated to occur through cell wall and membrane damage and metabolomics analysis. The results revealed that the minimum inhibitory concentration of resveratrol against S. typhimurium was 250μg/mL. After treatment with resveratrol, the lag period of the strain was prolonged, and the cell wall and membrane structure were destroyed. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) further confirmed that resveratrol induced damage to the cell walls and cell membrane. The metabolic profile of S. typhimurium following resveratrol treatment was analysed by gas chromatography‒mass spectrometry. In the metabolome evaluation, we screened 23 differentially abundant metabolites, including 11 upregulated and 12 downregulated metabolites. Eight metabolic pathways of S. typhimurium, including pathways important for amino acid metabolism and the tricarboxylic acid (TCA) cycle, exhibited significant changes after resveratrol treatment. The verification results of the citric acid content, cis-aconitase activity, and ATP content further revealed that the tricarboxylic acid cycle and other related metabolic pathways of S. typhimurium were affected. These results could provide a theoretical possibility for the use of resveratrol as a plant-derived bacteriostatic for food safety problems caused by S. typhimurium. KEY POINTS: • The mechanism of bacteriostasis was studied via metabolomics • Resveratrol causes the death of Salmonella by disrupting the cell wall and membrane.

Evaluation of joystick built-in emergency stop function for mobile elevating work platform safety and human factors and ergonomics in accident prevention

Evaluation of joystick built-in emergency stop function for mobile elevating work platform safety and human factors and ergonomics in accident prevention

Development of 3D-printed braces protocol for juvenile idiopathic scoliosis: From the torso measurement and mechanical properties to preliminary experience on fitting

Background: There has been no standard for a rapid prototyping process in manufacturing of the 3D-printed brace with respect to its design, biomechanical properties, procedures, and brace adjustment and fitting. Objective: Objective of this study was to develop the 3D-printed brace protocol for juvenile idiopathic scoliosis. Methods: With the help of the Torso Measurement Frame, the child stands still and is positioned with 1 of 2 manipulation techniques by the physician. Although the patient is in the corrected position, a hand-held scanner registers the three-dimentional (3D) torso, and then the brace is designed using computer aided design (CAD) model. Finite element analysis is used to determine the minimum required thickness of the brace. Acrylonitrile Butadiene Styrene (ABS) material (thermoplastic polymers) and DuraForm PA plastic (Nylon) material were printed by 2 different systems, respectively, and were tested using standard tensile test procedures. Results: The minimum thickness of the brace should be 2 mm to maintain a standard structural factor of safety twice that of the material failure strength. The strain in elongation was less for the ABS compared to the 3D-printed Nylon (6% vs. 14%), and the tensile strength was reduced more for ABS as compared to Nylon (42% vs. 14%). The ABS brace could not withstand changes in tension and cracked when drilled into, heat flared, or donned tightly. However, the Nylon brace improved strength and eliminated the vulnerable aspects. Conclusions: The Nylon material for the 3D-printed brace improved ease of adjustments in trimming, drilling, and heat modifications for better fit and function.

A Conceptual Design of Deployable Antenna Mechanisms

Over the last decade, large-scale antennas have been developed to enhance precise blue force tracking and improve situational awareness. In general, such large-scale antennas, ranging from 1 to up to 10 m, need a specific mechanism that can reconfigure their shapes and morphologies, resulting in stowing and deploying upon the given environment. In parallel, it must be noted that such deployable mechanisms should accommodate a large aperture diameter while ensuring they are lightweight, robust, and structurally rigid to avoid undesired deformations due to the deployment. With these in mind, this work presents a large frustum-shaped deployable antenna mechanism with a large aperture diameter of 7.5 m. The deployable mechanism is composed of hierarchical bayes the radial direction at 30° intervals. Twelve bayes in total identify the overall morphology of the deployable antenna, which features a dodecagon. Specifically, the bay is composed of three linkage structures: a six-bar linkage mechanism, a V-folding mechanism, and a single pantograph mechanism. As a result of static and dynamic simulations, it is identified that the mechanism achieves an area-to-mass ratio of 5.003 m2/kg and a safety factor of 323.8 upon deployment. Conclusively, this work demonstrates a strong potential of the deployable antenna mechanism, providing high rigidity and large aperture diameter while ensuring high stability in space environments.

First application of the island divertor configuration in the J-TEXT tokamak

Abstract For the first time, an island divertor configuration was successfully implemented in the J-TEXT tokamak to improve heat exhaust and impurity control. The magnetic island is generated by applying external resonant magnetic perturbation fields, and the intersection between the edge island and the divertor target is then controlled by adjusting the edge safety factor qa, thereby achieving the island divertor configuration. The overall confinement is maintained in spite of the loss of the edge volume. The island divertor configuration significantly reduces peak heat-load on the divertor target by approximately 50% and improves impurity screening. Additionally, it effectively modulates radiation around the magnetic island's X-point, potentially enhancing the stability and control of radiative divertor operations. These findings highlight the island divertor configuration as a promising strategy for advancing heat exhaust and impurity control in tokamak operations.

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.

Effect of Geometric Parameters of High-Speed Helical Gears on Friction Flash Temperature and Scuffing Load Capacity in Electric Vehicles

High-speed reducers in electric vehicles, characterized by high rotation speeds, heavy loads, large helix angles, and high contact ratios, are prone to tooth surface scuffing due to high sliding speeds. This scuffing is caused by adhesion wear from excessive instantaneous friction flash temperatures. The prevailing approach to gear scuffing analysis relies on the standard formula method, which is a relatively rudimentary technique. This method lacks the precision required to accurately assess the intricate distribution of tooth surface flash temperature (TSFT), limiting its efficacy in targeted tooth optimization. This study introduces an enhanced semi-analytical method to calculate TSFT and analyzes its variation under different conditions: increased tooth number and reduced module, altered pressure angle, and varied helix angle. The aim is to understand how these geometric parameters affect TSFT and the scuffing load capacity of high-speed reducer gears. This study calculates load distribution and TSFT under peak operating conditions and shows that increasing the tooth number, pressure angle, and helix angle can reduce maximum TSFT by more than 30%, improving scuffing safety and load capacity. However, these improvements must consider the gear’s allowable bending safety factor and bearing service life. The research concludes that optimizing these geometric parameters can significantly enhance the scuffing load capacity of gearsets.

The critical role of c and φ in ensuring stability: A study on rockfill dams

Abstract Slope stability analysis is an important part of rockfill dam design, and the uncertainty of rock and soil physical and mechanical parameters has a significant impact on slope stability. In this article, based on physical and mechanical parameters c and φ, simplified Bishop’s method and mean clustering method are adopted to study the influence of parameter cohesion c and internal friction Angle φ on slope safety factor k of composite geomembrane rockfill dam, and the key and non-critical areas of the dam are preliminarily differentiated according to the different influences of the changes in different sections of the dam body on slope safety factor c and φ. The research results show that whether c and φ change ±5 and ±10% simultaneously with single parameter or double parameter, it shows that cohesion force c has little influence on slope stability, while internal friction Angle φ is the most sensitive factor in slope stability calculation, and its numerical accuracy has a great influence on the calculation result of safety factor. In addition, the influence of c and φ in key areas on the stability of the dam body is more significant. Therefore, in the construction of a composite geofilm rockfill dam, a relatively accurate φ value is required when selecting parameters, especially in key areas. This study not only has a certain guiding significance for the property requirements of the selected soil, engineering safety, and engineering optimization design, but also puts forward some new methods and ideas for optimizing the design scheme and improving the safety of the dam.

Enhancing Oxygen-Dissolving Capacity of Rotary Drum Food Waste Composting: Tumbling Process Optimization and Experimental Validation with Discrete and Finite Element Methods

An optimized tumbling process can significantly improve the oxygen dissolving capacity of composting and fertilizer quality: by increasing the fluffiness of the lower layer of the pile, localized anaerobic fermentation can be avoided, thereby enhancing compost quality. This paper presents a method for improving the oxygen dissolving capacity of rotary drum food waste composting through a combination of simulation optimization and experimental validation. First, the discrete element method was used to optimize the key parameters of the tumbling process. The response surface method was then employed to analyze the composting test results and determine the optimal conditions. To ensure the reliability of the equipment under this method, failure risk analysis was conducted using the finite element method. The simulation optimization results showed that with a rotary drum reactor speed of 3.5 r/min, a horizontal angle of inclination of 2.5°, a mixing blade angle of inclination of 43°, and a blade pitch of 580 mm, the fluffiness of the lower layer of the pile increased by 8.515%, achieving the best tumbling and indirectly enhancing oxygen dissolving capacity. The maximum deformation of the load-bearing components was only 0.0548 mm, and the minimum safety factor was 4.408 (≥1 is considered safe). A 14-day composting experiment was conducted to validate the optimized parameters. The results showed that the maximum temperature of the compost pile reached 68.34 °C (lasting 7 days), with the pH, moisture content, C/N ratio, humus substances, humic acid, and fulvic acid contents of the fertilizer all meeting or exceeding the levels recommended by Chinese national standards. These findings indicate that the optimized tumbling device effectively improved the stability and dissolved oxygen efficiency of food waste composting, providing valuable practical insights and a research foundation for enhancing oxygen efficiency in the composting of other organic wastes.

Matching Analysis of Technical Parameters and Safety Standards for Nuclear Replacement of Coal-Fired Units

In the context of the growing share of renewable energy and the impending decommission of a large number of coal-fired units, nuclear energy is the only green energy that can replace coal power for a stable, clean, efficient, and large-scale power supply. This article compares the differences between coal power and nuclear power in terms of thermal system, thermal cycle, turbine parameters, and safety. It discusses the possibility of replacing the boiler of a coal power plant with nuclear power, that is, replacing the boiler of a coal power plant with a nuclear reactor for generation/heating/cogeneration. For coal-fired units with similar capacity that do not use a reheat cycle (at or below high pressure) and nuclear power units (such as a high-temperature gas-cooled reactor), as well as coal-fired units with a reheat cycle (ultra-high pressure and above) and nuclear power units (such as pressurized water reactors), there are great differences in steam parameters. In terms of steam turbines, the size of nuclear power units is relatively larger, requiring additional dehumidification measures. In addition, the safety factors and management methods considered in the site selection, construction, and operation of nuclear power plants are more stringent and complex, and comprehensive analysis and evaluation are needed in aspects such as waste treatment and accident emergency response. Except for the relevant provisions of the American Society of Mechanical Engineers code for pressure vessels, nuclear power units are not compatible with coal-fired units in terms of safety standards. Therefore, considering comprehensively, it is believed that the scheme of nuclear power replacing coal-fired units for power generation/heating/cogeneration program is not feasible at present.