Stability Analysis 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.

Mapping for stable bilateral teleoperation of manipulators considering time delays

Teleoperation of manipulators has allowed extending the human skills to several areas, where the commands generated by a human operator on the leader robot are followed by a remote robot. For this purpose, position-position tracking requires a mapping given the mismatch between robot workspaces. This paper compares a pair of functions for mapping the haptic device commands to handle a remote robot, considering non-identical workspaces and a classic P+d control scheme. As part of the theoretical analysis, a Lyapunov-Krasovskii-based stability analysis is developed in steps, allowing us for determining the boundedness of velocities and coordination errors. Subsequently, the performance of the teleoperation system is compared using two mapping functions. To achieve a fair comparison of results, a test protocol is developed, where different levels of haptic device damping, time delays, and workspace scales are used to evaluate the time to complete the task and the average coordination errors. Based on the results, the mapping function influences the calculation of force feedback, stability of the system, and performance metrics. During a pick-and-place task, a reduction in coordination error is observed when the linear function is chosen, while the time to complete the task is lower when a non-linear function is considered.

Stability Analysis via Impedance Modelling of a Real-World Wind Generation System with AC Collector and LCC-Based HVDC Transmission Grid

Stability Analysis via Impedance Modelling of a Real-World Wind Generation System with AC Collector and LCC-Based HVDC Transmission Grid

The impact of Si substitution on Ge sites in full heusler compound Ru2VGe: stability analysis

The impact of Si substitution on Ge sites in full heusler compound Ru2VGe: stability analysis

Small Signal Modelling and Stability Analysis of a Grid Connected Inverted Based Microgrid

Small Signal Modelling and Stability Analysis of a Grid Connected Inverted Based Microgrid

The Addition of Avocado Seed Flour in Reduced Fat Mayonnaise as Stabilizer

Aims: This study aims to determine the quality of mayonnaise by adding avocado seed flour as a stabilizer based on pH, viscosity, stability emulsion, emulsion droplets, acidity, and color analysis (L a* b*). Study Design: This study are an laboratory experimental with a completely randomizeddesign. Place and Duration of Study: This study are located in Laboratory of Animal Product Technology, Faculty of Animal Science, Universitas of Brawijaya. Methodology: This research method used was laboratory experimental with a completely randomized design with 4 treatments and 4 replications. Results: Avocado seed flour is added to the mayonnaise formulation at 0%, 1%, 2% and 3% sensory evaluation of the total ingredients used. The variables measured are pH, viscosity, stability emulsion, emulsion droplets , acidity, color analysis (L a* b*). The results showed that the treatment had a very significant effect (P<0.01) on pH, viscosity, stability emulsion, emulsion droplets, acidity and color analysis (L a* b*). It can be concluded that the best treatment in this study was mayonnaise woth the addition of 1% avocado seed flour. Conclusion: This study concluded that the addition of avocado seed flour at 3% can produce mayonnaise with the characteristics of pH, viscosity, emulsion stability, acidity, emulsion droplets, and color analysis.

Modeling the Unsteady Wake of an Impulsively Started Circular Cylinder Using Refined Potential Flow Theory

Abstract Cylindrical structures find usage in many engineering applications including tethered oil drums and engine canisters slung beneath helicopters in flight. The motion of air around such circular cylindrical structures and the helicopter presents interesting phenomena including flow separation, wakes and turbulence. The physics of these are enshrined in the continuity equation and the Navier-Stokes equations. Therefore, their studies are not only important in mathematics and physics, but they are also required for efficient helicopter operations. In practice, reduced-order models of these operations that take in aerodynamics models of the tethered loads are utilized for stability analysis, flight certification and pilot training because of the prohibitive cost of experimentation and computational analyses of these configurations. However, there is a dearth of realistic analytical models of finite cylinder flows because of the Navier-Stokes problem. Classical potential flow theory provides an avenue to develop such models, but the extant gaps in its predictions significantly preclude its usage for engineering applications. Attempting to bridge these gaps, this article introduces refined potential flow theory in which the governing equations and boundary conditions are satisfied. Viscous effects, fluctuations of the mean flow and three-dimensional effects are also incorporated. For characterization, refined potential flow theory is employed on an incompressible flow over an impulsively started circular cylinder for Reynolds numbers and non-dimensional times in the range 30 < Re < 10^4 and 0.2 ≤ T≤ 77, 047 respectively. There is an excellent prediction of 0.209 for the Strouhal number at Re = 3, 900. At this transitional Reynolds number, the harmonics of the Strouhal frequency are also captured, and the characteristic irregular fluctuations at sub-Strouhal frequencies are discernible in the velocity spectra. As the flow becomes more turbulent, these become more pronounced at Re = 9, 500 when the predicted Strouhal number is within 10% of experimental result. In the fully developed stage, spectra analyses of the wake velocity components at some downstream locations also display Kolmogorov’s Five-Thirds law of homogeneous isotropic turbulence. The present model can thus aid the development of reduced-order models of helicopter operations that feature tethered cylindrical loads.

Effective potential and vacuum stability in the Litim-Sannino model

We revisit the scalar potential in the Litim-Sannino model. We compute for the first time the full quantum corrections to the classical potential and show that they significantly ameliorate the stability analysis at the UV fixed point. The quantum effective potential is computed at two-loop order and the numerical precision is further improved using resummations and parameter optimisations. As a result, we find a consistent widening of the UV conformal window across various approximations.

An evolutionary game and system dynamics approach for the production and consumption of carbon-labeled products-based on a media monitoring perspective

Carbon label is acknowledged as an effective way to combat the problem of global warming. As a powerful way to encourage individuals to adjust their consumption patterns and to promote the development of green consumption, carbon-labeled products are widely developed in China. To reveal the production and consumption process of carbon-labeled products, the present study constructs a tripartite game model consisting of the government, carbon-labeled products manufacturers and consumers based on a media monitoring perspective. The evolutionary stability strategy (ESS) is firstly determined by solving the replication dynamic equations and stability analysis of the equilibrium point, followed by the strategy analysis and sensitivity analysis through numerical simulation. The results show that media supervision can effectively complement and constrain government supervision. In addition, it can promote enterprises to standardize production and enhance consumers' trust and willingness to buy carbon-labeled products. The introduction of media supervision can well realize the ideal equilibrium of "effective government supervision, enterprise compliance and consumer support for purchase".

Nonlinear stability analysis of double‐diffusive convection in Kelvin–Voigt fluid with chemical reaction

Nonlinear stability analysis of double‐diffusive convection in Kelvin–Voigt fluid with chemical reaction

Turbulence and mixing from neighbouring stratified shear layers

Studies of Kelvin–Helmholtz (KH) instability have typically modelled the initial mean flow as an isolated stratified shear layer. However, geophysical flows frequently exhibit multiple layers. As a step towards understanding these flows, we examine the case of two adjacent stratified shear layers using both linear stability analysis and direct numerical simulations. With sufficiently large layer separation, the characteristics of instability and mixing converge towards the familiar KH turbulence, and similarly when the separation is near zero and the layers add to make a single layer, albeit with a reduced Richardson number. Here, our focus is on intermediate separations, which produce new and complex phenomena. As the separation distance $D$ increases from zero to a critical value $D_c$ , approximately half the thickness of the shear layer, the growth rate and wavenumber both decrease monotonically. The minimum Richardson number is relatively low, potentially inducing pairing, and shear-aligned convective instability (SCI) is the primary mechanism for transition. Consequently, mixing is relatively strong and efficient. When $D\sim D_c$ , billow length is increased but growth is slowed. Despite the modest growth rate, mixing is strong and efficient, engendered primarily by secondary shear instability manifested on the braids, and by SCI occurring on the eyelids. Shear-aligned vortices are driven in part by buoyancy production; however, shear production and vortex stretching are equally important mechanisms. When $D>D_c$ , neighbouring billow interactions suppress the growth of both KH instability and SCI. Strength and efficiency of mixing decrease abruptly as $D_c$ is exceeded. As turbulence decays, layers of marginal instability may arise.

Interaction between soliton and periodic solutions and the stability analysis to the Gilson–Pickering equation by bilinear method and $$\exp (-\theta (\alpha ))$$-function approach arising plasma physics

Interaction between soliton and periodic solutions and the stability analysis to the Gilson–Pickering equation by bilinear method and $$\exp (-\theta (\alpha ))$$-function approach arising plasma physics

Continuous-time Lyapunov stability analysis and systematic parametrization of robust adaptive sliding mode controller for systems with matched and unmatched dynamics

Continuous-time Lyapunov stability analysis and systematic parametrization of robust adaptive sliding mode controller for systems with matched and unmatched dynamics

Dark solitons and their bound states in a nonlinear fiber with second- and fourth-order dispersion

We study the excitations of dark solitons in a nonlinear optical fiber with the second- and fourth-order dispersion, and find the emergence of striped dark solitons (SDSs) and some multi-dark-soliton bound states. The SDSs can exhibit time-domain oscillating structures on a plane wave, and they have two types: the ones with or without the total phase step, while the multi-dark-soliton bound states exhibit different numbers of amplitude humps. By the modified linear stability analysis, we regard the SDSs as the results of the competition between periodicity and localization, and analytically give their existence condition, oscillation frequency, and propagation stability, which show good agreements with numerical results. We also provide a possible interpretation of the formation of the existing striped bright solitons (SBSs), and find that SBS will become the pure-quartic soliton when its periodicity and localization carry equal weight. Our results provide the theoretical support for the experimental observation of striped solitons in nonlinear fibers, and our method can also guide the discovery of striped solitons in other physical systems.

An elastoplastic semi-analytical solution for enhanced geothermal wellbore stability considering temperature-sensitive failure criterion

Temperature alters the rocks’ mechanical behavior and influences the stability and operation of enhanced geothermal wells. The stability of the well is a concern during construction, just after the construction, at the time of production, and injection. Most available analytical and semi-analytical solutions for wellbore stability do not account for rock's temperature-dependent yield behavior. In the present study, we proposed an elastoplastic constitutive model based on the temperature-sensitive yield criterion and a semi-analytical solution for wellbore stability. The applicability of the constitutive model is demonstrated by comparing the experimental results of Comiso limestone with the model output. The model elastic perfectly plastic assumption reasonability captures the stress-strain behavior at elevated temperatures. Temperature-sensitive yield criterion effectively predicts the yield point of Comiso limestone, even the substantial decay in yield stress after the temperature of 400 οC. The semi-analytical solution of wellbore stability analysis is validated using FE (Finite element) analysis. An implementation of the semi-analytical solution is showcased for a vertical wellbore, considering changes in in-situ stresses and temperature. A parametric analysis establishes that external factors, like vertical stress increase, do not consistently decrease the size of the plastic zone. Instead, a specific threshold of vertical stress exists at which the plastic zone radius reaches its minimum value. In the presented case, the least radius of the plastic zone is observed for in-situ vertical stress of 80 MPa. Furthermore, the parametric study examines the impact of horizontal stress, support pressure, temperature, and dilation parameter, which followed the generally reported trends.

Genetic diversity and stability analysis of the improved cultivars of guava and their related species

Guava (Psidium guajava L.) is an important fruit crop in the tropical and sub-tropical world. The morphological, biochemical, and molecular (using 56 microsatellite markers) characterization was carried out on 18 guava genotypes and related species (P. guineense) during 2018–2022. The present study exhibited a wider range of variability: fruit weight (61.5–68.4 g); fruit diameter (4.20–7.91 cm); total soluble solids (8.50–13.40 °Brix); titrable acidity (0.20–0.64%); reducing sugar (2.55–7.00 mg glucose /g); ascorbic acid (76.4–196.3 mg/100 g); total phenol (125.9–305.4 mg GAE/100 g pulp); and total flavonoid content (172.30–948.5 mg QE/100 g pulp). The antioxidant activities (FRAP and DPPH) showed a favorable relationship with ascorbic acid, total phenol, total flavonoid, and total flavonol content. Red-fleshed genotypes were found superior for all the quality parameters over white-fleshed genotypes. The molecular analysis generated 213 alleles from 56 markers, with 2–9 alleles per locus (mean = 3.80). Apart from the genetic diversity, the improved cultivars were also distinguished by a set of markers: RCGH-4 (mPGCIR-184 and mPGCIR-194); RCGH-1 (mPGCIR-108 and mPGCIR-243); RCG-11 (mPGCIR-206 and mPGCIR-325); and RCGH-7 (mPGCIR-16 and mPGCIR-19). The cluster analysis indicated that P. guineense was the most diverse of the cultivated species, and all the red flesh genotypes were close to each other. Furthermore, RCG-11 had a lower seed content (58.89 per 100 g pulp), while RCGH-1 and RCGH-4 were stable for fruit weight and seed number, which can be promoted for commercial production and future crop improvement programs.

Modelling the co-infection of malaria and zika virus disease

In this work, a new model for the co-infection of malaria and zika virus disease incorporating vaccination, treatment and vector control using sterile-insect technology (SIT) is formulated. The importance of this study is to highlight the possibility of the co-infection of humans with malaria and zika virus disease in any environment where both diseases co-circulate. Also, to suggest a new and comprehensive method for controlling the individual diseases and their co-infection. Through stability analysis, we showed that the disease-free equilibrium, (DFE) point of the co-infection model is locally asymptotically stable when the basic reproduction numbers, Rmz is less than one, and unstable otherwise. But, the DFE failed to be globally stable when Rmz < 1 which is an indication of existence of backward bifurcation in the model. This shows that bringing down the reproduction number, Rmz to less than one is not enough to eradicate the co-infection of the two diseases. Furthermore, it is shown that the two diseases have positive impact on the spread of each other, which could be attributed to misdiagnoses of one disease as the other. We also showed that effective treatment of infectious humans, increasing the rate of vaccination and employing sterile-insect technique to control the vectors significantly helped to control the individual diseases as well as the co-infection. From the results obtained in the study, it can be concluded that effective control of malaria and zika virus disease requires measures that will control their spread in both human and mosquito populations.

Effects of Geological and Geotechnical Characteristics on Cut-Slope Stability of Residual Formations in the Hilly Terrain of Sri Lanka A Case Study from Central Expressway (Section 3)

Residual formations consist of residual soils and parent rocks of different levels of weathering due to physical, chemical and biological processes. Existence of residual soils on the hilly slope surface and weathering of parent rocks of the residual formations can cause slope instability problems. Cutting on the hilly slopes during development projects have aggravated the problems. Sri Lankan residual soil formations are formed by weathering of the metamorphic rock and have inherited significant abrupt variations in engineering characteristics. Basic characteristics of these residual formations such as unsaturated shear strength (geotechnical) and variation of geological features (geological) are essential parameters in slope stability analyses. Therefore, a study for effects of geological and geotechnical characteristics on cut slope stability of residual formation was done by selecting major cutting sections on hilly terrain in Central Expressway Project (CEP 03) trace where degree of weathering of the parent rock units, their petrography, physical, mechanical properties and various structural features as well as series of index properties, engineering properties and strength tests on residual soils were performed.This paper highlights the need for detailed experimental studies and presents preliminary studies that have been conducted to establish the geological and geotechnical characteristics of unsaturated Sri Lankan residual formation. The results indicate that the variation in geotechnical as well as geological characteristics of the residual formation are related to cut slope stability in hilly terrain.

The Impact of Replacing Synchronous Generators with Renewable-Energy Technologies on the Transient Stability of the Mangystau Power System: An Introduction to Flexible Automatic Dosage of Exposures

Since the creation of the first parallel electrical power systems around the world, the rotor angle stability of synchronously operating generators has been one of the most crucial and challenging problems. In modern electricity networks, including in Kazakhstan, where renewable energy technologies are rapidly emerging, the issue of stability takes on even greater importance due to the technical shortcomings of inverter-based generation. In this framework, an analysis of rotor angle transient stability was carried out when replacing existing synchronous generators with doubly fed induction generators under a certain pre-emergency mode. A critical proportion of active power generation by DFIG units was identified at which transient stability can still be maintained due to the sufficient stored kinetic energy of the synchronous machines remaining in operation. In addition, two simple solutions were investigated to improve transient stability, such as an increased time of the automatic reclosure operation and the use of special load-shedding automation. Finally, this paper proposes a novel type of flexible smart-grid automation that is capable of monitoring the main operating parameters and issuing control actions depending on inertia, the availability of wind resources, and the load of the system as a whole. For this analysis, a real power system from the Mangystau region in Kazakhstan was considered, and the PowerWorld software 23 was used.

Genotype by environment interaction and stability analysis of three agronomic traits in Kersting's groundnut (Macrotyloma geocarpum) using factor analytic modeling and environmental covariates

AbstractUnderstanding genotype by environment interaction (GEI) represents a challenge in Kersting's groundnut [Macrotyloma geocarpum (Harms) Maréchal and Baudet] breeding for selecting high‐performing and stable lines across environments. Here, we investigated GEI and stability in Kersting's groundnut using factor analytic (FA) based linear mixed models and environmental covariates. A total of 375 accessions were evaluated across 3 years (2017, 2018, and 2019) and two locations (Sékou and Savè) in Benin, generating five environments (E1, E2, E3, E4, and E5). The traits measured included days to 50% flowering (DFF), grain yield (YLD), and 100‐seed weight (HSW). The study generated multi‐environment values for grain yield and its components in Kersting's groundnut. The genetic correlations between pairs of environments ranged from −0.71 to 0.99. The genetic correlations between YLD and HSW indicated positive and moderate to high correlations in all environments. The FA analysis revealed that FA2 structure accounted for 93.9% of the genetic variability in DFF with factor 1 accounting for more than 90% of the environments variations. Two factors explained 87% of the genetic variance in grain yield, and 70% of the environments variability were clustered by factor 1. For HSW, two factors explained 85% of the genetic variance of the environments, and factor 1 accounted for 72.7%. Combining environmental covariates to FA models revealed that precipitation, temperature, and growth cycle duration were highly correlated to the environmental loadings of factor 1. Relative humidity and solar radiation showed moderate to high correlations with factor 2 loadings. Those covariates explained the high GEI among environments clustered by a given factor. Precipitations and temperatures affected the variations in grain yield. Finally, based on latent regression analysis, the accessions AF202, AF221, AF223, AF225, and AF256 were identified as accessions combining best performance for grain yield, early flowering, and 100‐seed weight, showing adaptability across environments and stability to some environments.