Safety Factor Research Articles

A comparative slope stability analyses of heavily jointed open-pit slopes using 3D limit equilibrium and finite element methods: a case study from Bingöl, Türkiye

ABSTRACT This study investigates the slope stability of Bingöl open-pit iron mine slopes using 3D limit equilibrium and finite element methods. The pit benches are 3 m wide and 6 m high, with an overall slope angle of 38°. The geological composition comprises slightly to moderately weathered and heavily jointed phyllite, micaschist, and gneiss. Shear strength parameters were determined through back analyses of already failed sections using the Hoek-Brown failure criterion and Geological Strength Index (GSI). Factor of safety values for static and dynamic conditions were calculated using 3D limit equilibrium and 2D finite element analyses. Results show good agreement between the two methods, with benches in the northern section exhibiting a significant decrease in safety factor under dynamic conditions, indicating near-limit equilibrium slopes.

Finite Element Analysis and Weight Optimization of Knuckle joint for different Materials by using CAE Tools

The current study involved the analysis of a knuckle joint using finite elements. A mechanical joint with two intersecting cylindrical rods whose axes are in the same plane is called a knuckle joint. Knuckle joint should be designed and manufactured in such a way that it can sustain more load without failure. The objective of the present study is to study knuckle joints made of different materials like aluminum, stainless steel, structural steel, magnesium, and gray cast iron using CAE tools. The CAD model of knuckle joint is made in CATIA V5 R20. The finite element analysis of this CAD model using ANSYS 15 has been carried out to investigate maximum stress and deformation. The CAE results compared with the analytical results using conventional approach. The CAE results have been found close to the analytical results, thus validating the model. The knuckle joint of aluminum is found to have highest factor of safety (1.641) at 50 KN load and is the most the most suitable material for knuckle joint. Weight of vehicle plays an important role in overall performance and fuel efficiency of vehicle. Knuckle joint is a part of vehicle. Hence weight optimization of knuckle joint made of aluminum has been performed using ANSYS 15 and it is observed that weight of knuckle joint made of aluminum can be reduced by 5.08% for 50 KN loading condition. Key Words: Knuckle joint, Finite element analysis, Mechanical joint, Load-bearing capacity, Material selection, CAE tools, Deformation analysis etc.

MINE SLOPE DESIGN SIMULATIONS USING SLIDE 6.0 SOFTWARE OF POST-MINING SLOPE STABILITY

Post-mining slopes are susceptible to landslides due to factors such as slope geometry, rock structure, physical and mechanical properties of rocks, and groundwater content. Monitoring of these slopes is essential to prevent broader environmental issues. This research aims to determine the stability of former mining slopes using soil samples from the Mataraman District, Banjar Regency. The technical analysis method focuses on the physical and mechanical properties of soil, supplemented with mine slope design simulations using Slide 6,0 software to ascertain the safety factors from various slope angles. Safety factor analysis considers the smallest cohesion and bulk density values to represent the material strength of the slope. Findings indicate that the post-mining slopes would remain stable and safe provided no additional destabilizing factors are introduced. The slopes maintain a safety factor greater than 2, implying stability even with a steepness up to 70°. Keywords: mining slope stability, safety factor

Safety of immune checkpoint inhibitors in patients aged over 80 years: a retrospective cohort study

BackgroundImmuno-oncology (IO) drugs are essential for treating various cancer types; however, safety concerns persist in older patients. Although the incidence of immune-related adverse events (irAEs) is similar among age groups, higher rates of hospitalization or discontinuation of IO therapy have been reported in older patients. Limited research exists on IO drug safety and risk factors in older adults. Our investigation aimed to assess the incidence of irAEs and identify the potential risk factors associated with their development.MethodsThis retrospective analysis reviewed the clinical data extracted from the medical records of patients aged > 80 years who underwent IO treatment at our institution. Univariate and multivariate analyses were performed to assess the incidence of irAEs.ResultsOur study included 181 patients (median age: 82 years, range: 80–94), mostly men (73%), with a performance status of 0–1 in 87% of the cases; 64% received IO monotherapy. irAEs occurred in 35% of patients, contributing to IO therapy discontinuation in 19%. Our analysis highlighted increased body mass index, eosinophil counts, and albumin levels in patients with irAEs. Eosinophil count emerged as a significant risk factor for any grade irAEs, particularly Grade 3 or higher, with a cutoff of 118 (/μL). The group with eosinophil counts > 118 had a higher frequency of irAEs, and Grade 3 or higher events than the group with counts ≤ 118.ConclusionIO therapy is a safe treatment option for patients > 80 years old. Furthermore, patients with elevated eosinophil counts at treatment initiation should be cautiously managed.

Development of pulsed plasma operation scenario and required conditions in JA DEMO

Abstract We have developed the pulsed plasma operation scenarios for JA DEMO, a design concept of the steady-state tokamak demonstration reactor, to clarify controls of the current profile and power required for the operation. We compare the scenarios when injecting electron cyclotron waves only and both neutral beam and electron cyclotron waves for external heating and current drive. We demonstrate current profile control that maintains the minimum value of the safety factor above one and avoids creating the local minima in the safety factor profile and power control by argon seeding that maintains the fusion power constant at the desired value and reduces the heat load on the divertor, performing long-time integrated modelling simulations. We clarify the conditions of the heating and current drive system and impurity injection system required for such control. The dependence of power control on argon anomalous transport coefficients is investigated. We have the prospect of maintaining the fusion power of 1 GW for more than two hours, i.e., obtaining the required plasma performance determined using a systems code.

Efficient reliability assessment of slope stability with insightful sensitivity analysis concerning the safety factor

The limit state functions (LSFs) of slope stability are nonlinear, implicit, or derived from numerical simulations, and additional surrogate models are usually used for its reliability problems. Alternatively, an efficient numerical procedure using a variant of the HLRF-BFGS algorithm is proposed to address this issue without additional surrogate models. This proposed procedure simultaneously conducts reliability assessment and sensitivity analysis concerning the safety factor by suggested calculations of partial derivatives using the finite difference method (FDM). Two highly nonlinear numerical examples are presented to validate its convergence and to investigate the step length of the FDM. Results show that the proposed procedure can get considerable accuracy while the HLRF algorithm cannot converge, and its required iterations are about 30% and 81% less than those of the limited step-size iteration algorithm. In addition, a step length not greater than 0.1 is suggested after investigations. Application to a classical two-layered slope is illustrated. Reliability results show that the proposed procedure can get the same accuracy as those of surrogate models after only 5 iterative steps. Sensitivity results show that the cohesion of the upper soil is the only sensitivity factor, and the most possible potential slide surface lies in the upper soil.

Finite Element Analysis and weight Optimization of Knuckle joint for different materials by using CAE Tools

The current study involved the analysis of a knuckle joint using finite elements. A mechanical joint with two intersecting cylindrical rods whose axes are in the same plane is called a knuckle joint. Knuckle joint should be designed and manufactured in such a way that it can sustain more load without failure. The objective of the present study is to study knuckle joints made of different materials like aluminum, stainless steel, structural steel, magnesium, and gray cast iron using CAE tools. The CAD model of knuckle joint is made in CATIA V5 R20. The finite element analysis of this CAD model using ANSYS 15 has been carried out to investigate maximum stress and deformation. The CAE results compared with the analytical results using conventional approach. The CAE results have been found close to the analytical results, thus validating the model. The knuckle joint of aluminum is found to have highest factor of safety (1.641) at 50 KN load and is the most the most suitable material for knuckle joint. Weight of vehicle plays an important role in overall performance and fuel efficiency of vehicle. Knuckle joint is a part of vehicle. Hence weight optimization of knuckle joint made of aluminum has been performed using ANSYS 15 and it is observed that weight of knuckle joint made of aluminum can be reduced by 5.08% for 50 KN loading condition. Key Words: Knuckle joint, Finite element analysis, Mechanical joint, Load-bearing capacity, Material selection, CAE tools, Deformation analysis etc.

A numerical investigation into the equivalent parameters of a compressible soil treated by stone columns

A series of triaxial test simulations are adopted to estimate the equivalent strength parameters for compressible soil samples reinforced with stone columns. The simulations utilize the finite difference code, Fast Lagrangian Analysis of Continua in three dimensions FLAC3D. An elasto-plastic model is applied to utilize a Mohr-Coulomb yield criterion. The equivalent strength parameters are estimated using newly proposed formulas for geo-composite materials. The researchers compare the obtained results to the analytical formulas proposed in the literature. Additionally, the equivalent parameters are used in equivalent area models. This study investigates the effect of the replacement area ratio. This study offers two applications. Firstly, it evaluates the safety factor of embankments constructed on compressible soil improved with stone columns. Secondly, it estimates the bearing capacity of strip footings on compressible soil treated with stone columns. In all applications, both individual column and equivalent area models are considered. The proposed equations for the equivalent elastic parameters (E, ν) and the mechanical properties, equivalent cohesion, and internal frictional angle (c and φ) give results that agree with the solutions reported in the existing literature.

A Methodology for Susceptibility Assessment of Wave-Induced Seabed Liquefaction in Silt-Dominated Nearshore Environments

Wave-induced seabed liquefaction significantly jeopardizes the stability of marine structures and the safety of human life. Susceptibility assessment is key to enabling spatial predictions and establishing a solid foundation for effective risk analysis and management. However, the current research encounters various challenges, involving an incomplete evaluation system, poor applicability of methods, and insufficient databases. These issues collectively hinder the accuracy of susceptibility assessments, undermining their utility in engineering projects. To address these challenges, a susceptibility assessment method with the safety factor was developed as the key assessment parameter, allowing for a comprehensive susceptibility assessment across the silt-dominated nearshore environment using Empirical Bayesian Kriging (EBK). The safety factor is determined by combining the cyclic stress ratio (CSR) and the cyclic resistance ratio (CRR), which characterize wave loadings and sediment properties in the study area, respectively. This method was applied in the Chengdao region of the Yellow River Estuary, China, a typical silt-dominated nearshore environment where wave-induced liquefaction events have been reported as being responsible for multiple oil platform and pipeline accidents. By collecting the regional wave and seabed sediment data from cores spanning from 1998 to 2017, the safety factors were calculated, and a zonal map depicting the susceptibility assessment of wave-induced seabed liquefaction was created. This study can serve as a valuable reference for the construction and maintenance of marine engineering in liquefaction-prone areas.

Core electron temperature turbulence and transport during sawtooth oscillations in the DIII-D tokamak

Sawteeth are one of the concerning instabilities in ITER and future burning plasma experiments. Sawtooth dynamics and its interaction with broadband plasma turbulence has been a challenge for predictive simulations of core transport in future fusion devices. This study provides new observations of core turbulence behavior during sawtooth oscillations in DIII-D hydrogen L-mode neutral beam injection heated plasmas in an inner wall limited configuration. A strong correlation of electron temperature and density turbulence levels with the sawtooth oscillation phase has been observed at locations inside the T e inversion radius and/or safety factor q = 1 magnetic surface. The T e turbulence amplitude in the core during the sawtooth ramp exhibits a critical T e gradient behavior inside but not near the T e inversion radius/q = 1 magnetic surface. The most unstable mode calculated from the trapped gyro-landau fluid turbulence simulations reveal a change from low-k ion-type to low-k electron-type modes from pre- to post- sawtooth crash time periods.

Experimental and numerical study of the failure mechanism and stability of tunnel linings under different cavity conditions

In highway tunnels, the presence of a cavity behind the lining can affect the contact between the lining and surrounding rock, leading to the concentration of pressure from the surrounding rock and acceleration of cracking in the tunnel structure. Thus, such cavities pose significant safety hazards. However, due to the complexity of the interaction between the cavity behind the lining and the surrounding rock, it is challenging to clarify the mechanism of damage caused by the cavity. In this study, we developed a mechanical model for testing the linings of highway tunnels and conducted numerical simulations of the bearing capacity of the lining in the presence of cavities. The results showed that the presence of a cavity behind the arch crown significantly affected the overall lining structure along with the stress state and deformation of the lining, leading to cracking at the arch crown of the lining. In contrast, the effects of single voids at the arch shoulder and arch waist were relatively small. When the cavity is located on one side of the lining, the effect of the deviation angle of the cavity center on the overall safety factor of the lining becomes more significant, with a maximum decrease of 62% in the safety factor. This study provides an essential reference for detecting and evaluating tunnels during operation when voids are present behind the lining.

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

Abstract The CLT code is used to quantitatively study the impact of toroidal mode coupling on the explosive dynamics of m/n = 3/1 double tearing mode. This work focuses on the explosive reconnection processes in which 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 qmin (the minimum value of safety factor), or a low resistivity. The relationships between the higher m and n modes development, explosive reconnection rate and the position exchange of 3/1 islands are summarized for the first time. The separation plays a more important role than qmin on enhancing the development of higher m and n modes. At a relatively large separation, the well 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.

Performance and mechanism of organic solid-phase sediment composite plugging agent

The surface pipeline sediments of the Yingmai and Hade oil fields mainly contain substances such as asphalt and paraffin. The formation of sediment can increase the backpressure during pipeline transportation, and in severe cases, it can also lead to pipeline blockage. In order to solve this on-site situation, indoor experiments were conducted in the early stage, and an efficient organic unblocking system LXW was optimized and formulated. Based on this system, this article selects the wire mesh filtration method to evaluate the unblocking performance of LXW and on-site unblocking agents in the study and comparison of three evaluation methods. At the same time, based on the analysis of the chemical composition, microstructure, and melting point of organic sediments, from the perspectives of safety, environmental protection, and economic factors, further compares the performance and universality of the three unblocking systems, optimizes the process parameters of the LXW unblocking system, explores its stability and impact on the demulsification and dehydration of crude oil emulsions, and evaluates its safety performance. The LXW unblocking system has a more efficient unblocking effect and better universality, which can solve the problem of multiple block blockages on site. In addition, compared with existing unblocking agents, it has better economic benefits and is in line with the characteristics of low cost on site. On this basis, the dissolution and dispersion mechanism of the blockage system on sediment was studied through laser scattering system and fluorescence microscope, and its microscopic mechanism was further verified. At the same time, the oil-water interfacial tension under the action of the unblocking system was studied, and it was found that adding the agent can significantly reduce the equilibrium interfacial tension, which is of great significance for increasing production and injection.

Uncertainty Quantification of Engineering Parameters for a Nuclear Reactor Loaded with Dispersed Fuel Particles

Owing to their high intrinsic safety, dispersed fuel particles are an important fuel pattern for fourth-generation nuclear reactors. Due to the unique cladding layers and the random dispersion characteristics, dispersed fuel particles significantly differ from pressurized water reactors regarding operation-induced uncertainty. This study quantitatively analyzed overall uncertainty while considering a random distribution of dispersed fuel particles, material thickness, and fuel enrichment. The results demonstrated that, for all packing fractions, the uncertainty induced by the random dispersion of dispersed fuel particles was below 0.03%. For every packing fraction, the differences between the results obtained by the regular and the random distribution models increased, and then decreased, until reaching its maximum (1.297%) at 15%. Keff decreased as the radius of the UO2 kernel increased; Keff increased as the thickness of the cladding layer increased; the uncertainty of Keff was 1.003% when a random distribution of particles, material thickness, and fuel enrichment were taken into consideration; the uncertainty of the power distribution of reactor core assemblies was maximized (1.495%) at the edge of the reactor core. Quantitative analysis of uncertainty provides references for the optimization of design and safety margin analysis for reactors.

Heat capacity of liquid octamethyltrisiloxane (MDM) and hexamethyldisiloxane (MM): Measurement and molecular dynamics study

Accurate heat capacity data and models of fluids are necessary to reduce the design margins of engineering equipment. Also, heat capacities are indispensable in the development of high-accuracy equation of state. In this work, liquid heat capacities of Octamethyltrisiloxane (MDM, C8H24O2Si3) and Hexamethyldisiloxane (MM, C6H18OSi2) were obtained with a modified steady-flow calorimeter. Experiments were performed over the temperature range of 313 to 453 K and pressures up to 10 MPa. The expanded relative uncertainty in measurement of heat capacity is less than 0.015. Then, the present experimental heat capacity data were correlated with an empirical model, yielding an average absolute deviation (AAD) of 0.26 % for MDM and 0.38 % for MM. In addition, non-equilibrium molecular dynamics was used to investigate the heat capacity of MDM and MM. The simulation results show not only a reasonable heat capacity’s dependence on temperature but also a high accuracy.

Understanding the mechanism of safety attitude mitigates the turnover intention novice nurses via the person-centred method: A theory-driven, deductive cross-sectional study.

Examine profiles of safety attitudes among novices and explore whether profiles moderate the occupational identity-turnover pathway. Novice nurses face unique challenges in adopting positive safety attitudes, which influence outcomes like turnover. However, past research found only average levels of safety attitudes among novices, ignoring possible heterogeneity. Exploring whether meaningful subgroups exist based on safety perspectives and factors shaping them can provide insights to improve safety attitudes and retention. This study was designed as a cross-sectional investigation. Data were collected through the distribution of questionnaires. Descriptive statistics were first conducted, followed by latent profile analysis. We then carried out univariate analysis and ordinal multinomial regression to explore the factors shaping the different profiles. Finally, we examine the moderating effect of nurses' safety attitudes with different latent profiles on the relationship between professional identification and turnover intention. A total of 816 novice nurses were included. Three profiles were identified: high, moderate and low safety attitudes - higher attitudes were associated with lower turnover intention. Interest in nursing, health status, identity and turnover predicted profile membership. Moderate profile had a stronger buffering effect on the identity-turnover link versus high profile. Multiple safety attitude profiles exist among novice nurses. Certain factors like interest in nursing and occupational identity are associated with more positive safety profiles. Targeting these factors could potentially improve safety attitudes and reduce turnover among novice nurses. The moderating effects suggest that tailored interventions matching specific subgroups may maximize impact. Assessing subgroup attitudes enables tailored training for novices' specific needs, nurturing continuous improvement. Supporting early career development and role identity may strengthen retention intentions.

Picosecond alexandrite laser treatment of nevus of Ota in children.

The picosecond alexandrite laser has been safely and effectively used to treat the nevus of Ota in adults. However, limited data are available for children. To investigate the efficacy, safety, and correlative influencing factors of a 755nm picosecond alexandrite laser in the treatment of nevus of Ota in children. We retrospectively analyzed Chinese children with nevus of Ota who received a 755nm picosecond alexandrite laser treatment in a tertiary dermatological hospital. A total of 305 pediatric patients received an average of two treatments achieving an average of 79% pigment clearance. After the first treatment, 22 patients achieved complete clearance (95%-100%), and 72 patients achieved excellent response (75%-94%), with an average initial efficacy of 63% lesion clearance. Treatment at an early age achieved better initial efficacy (0- to 12-month group >1- to 6-year group, 6- to 12-year group). And 0- to 12-month group achieved better final efficacy. More treatment sessions also increased the final efficacy. Both initial efficacy and final efficacy were better when treating a darker lesion. The incidence of complications was 12.1%, with 10.8% being post-inflammatory hyperpigmentation and 1.3% being hypopigmentation. The rate of recurrence was 6.6%. Retrospective study. A 755nm picosecond alexandrite laser is safe and effective in treating nevus of Ota in children. Younger to initiate treatment, darker lesions, and more treatments are positively associated with better pigmentation clearance.

Assessing locations susceptible to shallow landslide initiation during prolonged intense rainfall in the Lares, Utuado, and Naranjito municipalities of Puerto Rico

Abstract. Hurricane Maria induced about 70 000 landslides throughout Puerto Rico, USA, including thousands each in three municipalities situated in Puerto Rico's rugged Cordillera Central range. By combining a nonlinear soil-depth model, presumed wettest-case pore pressures, and quasi-three-dimensional (3D) slope-stability analysis, we developed a landslide susceptibility map that has very good performance and continuous susceptibility zones having smooth, buffered boundaries. Our landslide susceptibility map enables assessment of potential ground-failure locations and their use as landslide sources in a companion assessment of inundation and debris-flow runout. The quasi-3D factor of safety, F3, showed strong inverse correlation to landslide density (high density at low F3). Area under the curve (AUC) of true positive rate (TPR) versus false positive rate (FPR) indicated success of F3 in identifying head-scarp points (AUC = 0.84) and source-area polygons (0.85 ≤ AUC ≤ 0.88). The susceptibility zones enclose specific percentages of observed landslides. Thus, zone boundaries use successive F3 levels for increasing TPR of landslide head-scarp points, with zones bounded by F3 at TPR = 0.75, very high; F3 at TPR = 0.90, high; and the remainder moderate to low. The very high susceptibility zone, with 118 landslides km−2, covered 23 % of the three municipalities. The high zone (51 landslides km−2) covered another 10 %.

A Simplified Method for Determining Fire Resistance of RC Columns Using Fire-Resistance-Column-Curves Approach

AbstractEurocode-2 (EC2) empirical equation for fire resistance of RC columns is very sensitive to the value of column capacity at normal temperature conditions $$N_{Rd}$$ N Rd . Techniques to determine $$N_{Rd}$$ N Rd accurately for eccentric slender columns are difficult and computationally demanding; thus, adopting simplifications leads to unsatisfactory results in many column cases. Another shortcoming of EC2 equation is that it does not include an explicit term regarding the effect of load eccentricity on fire resistance. In this paper, a simplified method, as an attempt to overcome EC2 method defects, is developed to determine the fire resistance of RC columns using fire-resistance-column-curves. A rational numerical model is used to analyze various series of RC columns with different geometric, material, and loading properties at elevated temperatures. The results of the numerical study are utilized to construct different fire-resistance-column-curves from which simplified design equations are developed to predict the fire resistance of fixed- and pinned-end RC columns. The validity of the method is established with the aid of experimental data and it was found that in most cases, there is good agreement between assessed and test columns. It was also found that the proposed equations provide sufficiently safe predictions when appropriate material safety factors are adopted. The applicability of the proposed method to fire resistance design of RC columns is illustrated through numerical examples.

Optimal energy storage system selection for future cost-effective green hydrogen production: Integrating techno-economic, risk-based decision making, and cost projections

This study conducts technical, economic, and safety analysis of a green hydrogen production system consisting of a 1000 kWp photovoltaic cell, 3 options of energy storage namely lead carbon (PbC), lithium-ion (Li-ion), and repurposed lithium-ion (2nd Life Li-ion) battery, and an electrolyzer. Firstly, the system is optimized to maximum hydrogen production by adjusting equipment capacity and capacity factors, informed by a 1-h resolution solar energy generation profile. This optimization yields insights into the system's yearly operational dynamics. Techno-economic analysis was conducted to estimate the levelized cost of hydrogen (LCOH) from 2020 to 2050, additionally, uncertainty analysis using Monte-Carlo simulation to estimate the range of uncertainty in LCOH projection from 2020 to 2050 was performed. Furthermore, a quantitative risk analysis, utilizing the process route index metric, evaluates the risk of battery explosions. Finally, this study employs multi-criteria decision-making to choose the best energy storage technology to produce green hydrogen from economic and safety factors. The result indicates that in 2020, the PbC battery emerged as the most cost-effective option. However, over time, both lithium batteries became the cheapest option with almost similar trends. In terms of explosion hazard, the analysis shows that the PbC battery is a safer option for stationary energy storage. When both aspects are considered, the preferred battery option is almost certainly PbC over the years, but in extreme cases where the decision-maker places significant emphasis on economic factors both Li-ion options may become preferable.