Stable Point Research Articles

STABILITY ANALYSIS OF THE SIQR MODEL OF DIPHTHERIA DISEASE SPREAD AND MIGRATION IMPACT

Diphtheria is an acute disease that affects the upper respiratory tract caused by Corynebacterium diphtheriae, which can also affect the skin, eyes, and other organs. This article analyzes the stability of the SIQR model of diphtheria disease spread in Mandau District by considering the migration factor. The SIQR model is a development of the SIR model by incorporating the quarantine process as an alternative to reduce morbidity. The purpose of this study is to see the effect of migration on the spread of diphtheria disease in Mandau District through mathematical model simulation. We calculated the disease-free and endemic equilibrium points and the basic reproduction number ( ) of the model. Model parameters were obtained using data from BPS Bengkalis Regency and UPTD Puskesmas Mandau. The calculation resulted in one disease-free equilibrium point and one endemic equilibrium point. If < 1, then the disease-free equilibrium point is asymptotically stable, and if > 1, then the endemic equilibrium point is also asymptotically stable. Based on the results of the data analysis, the value of. This value is less than 1, so the equilibrium point obtained is a disease-free and asymptotically stable equilibrium point. This means that the population will be free from diphtheria and the level of migration affects the presence of diphtheria disease in Mandau District.

A research framework for seismic slip distribution inversion considering atmospheric effects and deformation field downsampling

ABSTRACT Traditional Interferometric Synthetic Aperture Radar (InSAR) methods have difficulties in capturing deformation information of small and medium-sized earthquakes due to small surface deformation and atmospheric interference. This study proposes a research framework for seismic slip distribution inversion considering atmospheric effects and deformation field downsampling. The research framework begins by generating multiple interferometric pairs, using the coherence thresholding method to select stable points as reference during phase unwrapping. This step includes averaging the unwrapped pairs post-phase superposition to mitigate atmospheric turbulence effects in the interferograms and effectively extract the faint coseismic deformation field. Additionally, the framework employs a saliency-based quadtree downsampling algorithm to differentiate between major and minor deformation zones, thereby streamlining the data associated with the deformation field. The Bayesian method is then used to determine the geometric parameters of the earthquake fault, with the steepest descent method (SDM) applied to invert the fault slip distribution. The methodology was tested using the March 20, 2020, Ms5.9 earthquake in Dingri County, Tibet, China as a case study. Results demonstrate that this approach reduces atmospheric influences in the deformation field and enhances the accuracy of fault slip inversion, showing high consistency with existing studies and validating the reliability of the proposed method.

Sustainable alternative to manage the organic fraction of household solid waste: optimized composting in organomineral production

More than 50% of household solid waste is organic; thus, composting has emerged as alternative to extend landfills’ useful life and to reduce costs and minimize environmental impacts resulting from organic-fraction landfilling. The aims of the present study are to develop a domestic compost bin, optimize the main composting-process parameters set for household organic solid waste, generating an organomineral composite as final product from synthetic fertilizer application and featuring this matured biofertilizer. Rotatable central composite design was the method of choice to define the experimental matrix for variable optimization purpose. The following parameters were monitored throughout the experiments: moisture content, temperature, pH and C:N ratio. The mathematical model returned values close to 99% for optimum stabilization point and approximately 98% experimental data. This finding points out the efficiency of the generated optimization model. Temperature was not a compromising factor to achieve a proper composting process progress. According to the C:N ratio recorded throughout the experiments, the equipment mineralized the waste without reaching high temperatures, with small amounts of organic mass. The optimal conditions to maximize the stability of organic-mineral materials were reached when the process was carried out within 18 days, after 15-time compost revolving and the addition of 6.5% synthetic fertilizer (NPK). The equipment developed under the optimized composting parameters emerged as promising alternative to treat the organic fraction of urban solid waste, besides contributing to sustainable and environmental development, as well as to economic and social gains.

Stability of f(Q, B) Gravity via Dynamical System Approach: A Comprehensive Bayesian Statistical Analysis

Abstract In this work, we explore the cosmological stability of f(Q, B) gravity using a dynamical system approach, where Q denotes the nonmetricity scalar and B represents the boundary term. We determine the model parameters of f(Q, B) through Bayesian statistical analysis, employing Markov Chain Monte Carlo techniques. This analysis incorporates numerical solutions and observational data from cosmic chronometers, the extended Pantheon+ data set, and baryonic acoustic oscillation measurements. Our findings reveal a stable critical point within the dynamical system of the model, corresponding to the de Sitter phase, which is consistent with current observations of the Universe dominated by dark energy and undergoing late-time accelerated expansion. Additionally, we utilize center manifold theory to examine the stability of this critical point, providing deeper insights into the behavior of the model. The cosmological implications of f(Q, B) gravity indicate a smooth transition in the deceleration parameters from deceleration to the acceleration phase, underscoring the potential of the model to describe the evolution of the Universe. Our results suggests that the f(Q, B) model presents a viable alternative to the standard ΛCDM model, effectively capturing the observed acceleration of the Universe and offering a robust framework for explaining the dynamics of cosmic expansion.

Spatial and temporal distribution of arsenic concentration in rural drinking water and health risk assessment in Northern China from 2013 to 2022: a case study of Inner Mongolia Autonomous Region

BackgroundBy monitoring arsenic levels in rural drinking water in Inner Mongolia Autonomous Region from 2013 to 2022 and evaluating their health risks, this study provides a basis for further developing strategies to promote public health.MethodsOne stable centralized water supply point was randomly selected in each township of Inner Mongolia Autonomous Region. One finished water sample and 1–3 tap water samples were collected at each supply point. Water samples were collected once during the dry season (May) and once during the rainy season (August-September). Mann-Whitney U test was used to compare arsenic concentrations in drinking water from different types of water sources, and Kruskal-Wallis test was used to compare arsenic concentrations in drinking water across different years. Environmental health risk assessment was conducted using the health risk assessment model recommended by the US Environmental Protection Agency (USEPA).ResultsOverall, arsenic concentrations in rural drinking water were higher in the central-western part of Inner Mongolia Autonomous Region compared to the eastern part. From 2013 to 2022, there was a notable decreasing trend in arsenic concentrations in rural drinking water, with over 98% of water samples meeting arsenic standards by 2022. During 2013–2019, arsenic concentrations in drinking water sourced from groundwater were consistently higher than those from surface water sources (P < 0.05). Hazard quotient (HQ) values for the entire population were below 1, and lifetime cancer risk (LCR) values exceeded 1 × 10− 6. Sensitivity analysis indicated that drinking water arsenic concentration contributed the most to health risks for the population.ConclusionDuring 2013–2022, through concerted efforts by the government and the people, excessive arsenic levels in rural drinking water have been significantly reduced, resulting in decreased health risks for the population. However, some carcinogenic risks still exist.Therefore, the next critical step in improving water quality in the region involves further optimizing methods such as coagulation, adsorption, or ion exchange to remove arsenic from drinking water.

Structural reliability analysis of a stable equilibrium point based on the dynamic integrity of its safe basin

Structural reliability analysis of a stable equilibrium point based on the dynamic integrity of its safe basin

The dynamic ambivalence of adolescence in Emmanuel Dongala’s Johnny chien méchant (2002) and Tierno Monénembo’s L’Aîné des orphelins (2000)

In Johnny chien méchant (2002) by Emmanuel Dongala and L’Aîné des orphelins (2000) by Tierno Monénembo, the figure of the adolescent narrator-protagonist serves to depict personal and social crisis in (post-)conflict environments in Central Africa. This article explores how the authors portray the dynamic ambivalence of adolescence in interaction with a world in flux, both through the subjective accounts of their narrator-protagonists and through narrative form. Dongala uses the device of twin narratives – ostensibly of victim and perpetrator – to depict contrasting paths through violent conflict, and to show the turmoil of each adolescent protagonist from within and without. Monénembo’s teenage narrator gives a disjointed account, moving back and forth between recollections of innocent, stable, pre-pubescent childhood and brash, volatile adolescence, separated by the extreme rupture of the 1994 genocide against the Tutsi in Rwanda. The agency of the adolescent is manifest in a dynamic interaction of self-formation, resistance, and engagement with the world – an interaction intensified by the context of conflict and the ambiguous power of the peer group, violence, and the sexed body. The unreliable first-person narrative voice serves both to shape and to undermine adolescent identity and to deny the reader a stable point of view. In their unsettling and ambivalent conclusions, both novels challenge the linear conception of the child in formation progressing towards ‘fully formed’ adulthood. Rather, adolescence emerges as symbol and embodiment of creative/destructive flux, holding out the fragile possibility of renewal.

Visual Inertial SLAM Based on Spatiotemporal Consistency Optimization in Diverse Environments

ABSTRACTCurrently, the majority of robots equipped with visual‐based simultaneous mapping and localization (SLAM) systems exhibit good performance in static environments. However, practical scenarios often present dynamic objects, rendering the environment less than entirely “static.” Diverse dynamic objects within the environment pose substantial challenges to the precision of visual SLAM system. To address this challenge, we propose a real‐time visual inertial SLAM system that extensively leverages objects within the environment. First, we reject regions corresponding to dynamic objects. Following this, geometric constraints are applied within the stationary object regions to elaborate the mask of static areas, thereby facilitating the extraction of more stable feature points. Second, static landmarks are constructed based on the static regions. A spatiotemporal factor graph is then created by combining the temporal information from the Inertial Measurement Unit (IMU) with the semantic information from the static landmarks. Finally, we perform a diverse set of validation experiments on the proposed system, encompassing challenging scenarios from publicly available benchmarks and the real world. Within these experimental scenarios, we compare with state‐of‐the‐art approaches. More specifically, our system achieved a more than 40% accuracy improvement over baseline method in these data sets. The results demonstrate that our proposed method exhibits outstanding robustness and accuracy not only in complex dynamic environments but also in static environments.

Replicator dynamics generalized for evolutionary matrix games under time constraints.

One of the central results of evolutionary matrix games is that a state corresponding to an evolutionarily stable strategy (ESS) is an asymptotically stable equilibrium point of the standard replicator dynamics. This relationship is crucial because it simplifies the analysis of dynamic phenomena through static inequalities. Recently, as an extension of classical evolutionary matrix games, matrix games under time constraints have been introduced (Garay et al. in J Theor Biol 415:1-12, 2017; Křivan and Cressman in J Theor Biol 416:199-207, 2017). In this model, after an interaction, players do not only receive a payoff but must also wait a certain time depending on their strategy before engaging in another interaction. This waiting period can significantly impact evolutionary outcomes. We found that while the aforementioned classical relationship holds for two-dimensional strategies in this model (Varga et al. in J Math Biol 80:743-774, 2020), it generally does not apply for three-dimensional strategies (Varga and Garay in Dyn Games Appl, 2024). To resolve this problem, we propose a generalization of the replicator dynamics that considers only individuals in active state, i.e., those not waiting, can interact and gain resources. We prove that using this generalized dynamics, the classical relationship holds true for matrix games under time constraints in any dimension: a state corresponding to an ESS is asymptotically stable. We believe this generalized replicator dynamics is more naturally aligned with the game theoretical model under time constraints than the classical form. It is important to note that this generalization reduces to the original replicator dynamics for classical matrix games.

Evolution of the universe prior to inflation in loop quantum cosmology

Abstract We study the dynamics of pre-inflation with the generic potentials, namely, $V(\phi) \propto \phi^{4}$ and $V(\phi) \propto (1+\phi)^{2}$ in the context of loop quantum cosmology where initial singularity is resolved by a non-singular quantum bounce. Initially, the background evolution is either dominated by kinetic energy or potential energy at the quantum bounce. In case of kinetic energy dominated evolution at the bounce, we find three generic phases such as bouncing, transition and the slow-roll inflation whereas first two regimes are vanished in case of potential energy dominated evolution though the slow-roll inflation can still be achieved. Therefore, we find the physically viable initial conditions of the inflaton field which have the number of $e$-folds at least 60 to be compatible with observations. Additionally, we discuss the phase space diagram for the models under consideration where all the trajectories of the inflaton field start from the bounce and move towards the stable attractor points.

Continuous Fragmentation of Comet 157P/Tritton

We observed the split comet 157P/Tritton in 2022 October–November and 2024 January with the Nordic Optical Telescope. Our observations show that the splitting continued during the entire observing campaign. Fragmentation was associated with outbursts, consistent with the action of outgassing torques that spun up the nucleus and its fragments to the point of rotational instability. The outburst-fragmentation events can lead to a runaway process where the increasing spin rate, driven by outgassing torques, results in repeated mass loss until the sublimating body completely disintegrates.

Single inertial neuron with forced bipolar pulse: chaotic dynamics, circuit implementation, and color image encryption

Abstract The bipolar pulse current can effectively mimic the external time-varying stimulus of neurons, and its effect of neuronal dynamics has rarely been reported. To this end, this paper reports the effects of bipolar pulses on a two-dimensional single inertial neuron model, showcasing the chaotic dynamics of hidden attractors and coexisting symmetric attractors, which is of significant importance for understanding the complex behaviors of neuron dynamics under time-varying external stimuli and its application. Firstly, the mathematical model of the single intertial neuron model with forced bipolar pulse is presented, and then the equilibrium states behaving as unstable saddle point (USP), stable node-focus (SNF), and stable node point (SNP) are analyzed. Additionally, by using multiple dynamical methods including bifurcation plots, basins of attraction, and phase plots, complex dynamics of interesting bifurcation behaviors and coexisting attractors are revealed, which are induced by the forced bipolar pulse current as well as initial values, both. In addition, such effets are well valideted via a simple multiplerless electronic neuron circuit. The implementation circuit of presented model is constructed on the analog level and executed using PSIM circuit platform. The measurement results verified the double-scroll chaotic attractors and the coexisting period/chaos behaviors. Finally, the chaotic sequences of the model are applied to color image encryption for the benefit of requirements on modern security field. The encryption effectiveness is demonstrated through various evaluation indexes, including histogram analysis, information entropy, correlation coefficient, plaintext sensitivity, and resistance to noise attacks.

Dynamic damage law and failure modes of layered coal-rock mass under impact loading

Abstract Up to now, most of the structural dynamic analysis is based on the Lagrange system, while the Hamilton system is composed of the phase space composed of the generalized displacement and stress, showing a wonderful symmetry, which opens up a new way for the theoretical research and calculation of dynamics. The physical model of the layered combined coal-rock is constructed by dividing the ‘outburst center’ coal in front of the heading face into the combined layered structure. Based on Hamilton mechanics, the Hamilton canonical equation under symplectic geometry structure is established, combined with Hamilton variational principle and symplectic time subdomain method, the multi-layer symplectic element control equation of coal-rock is established, and the dynamic displacement and stress transfer characteristics at any time can be solved by iterative calculation. The action modes of axial torsional stress, radial principal stress and shear stress of layered coal- rock under impact loading are determined, and the weak layer and interlayer stress transfer dynamic response behavior of layered coal- rock under complex stress conditions are determined. The conclusions are as follows: ①Under static loading, the layered shear stress circle provides the initial condition of damage failure, impact loading acts as an exciting force to trigger the torsion effect, forming the ‘ X ’ -shaped shear line in the radial and axial directions of the interlayer interface, and the boundary produces the ‘ V ’ -shaped dynamic spalling surface. ②The short axis is damaged before the long axis, and the central node is the starting point of instability. The main cracks are formed along the long and short axis respectively, and finally the ‘ O-+ ’ failure mode is formed, which verifies the prominent axial and radial spallation phenomenon. This method avoids the non-conservation of system energy caused by energy dissipation, and will become an effective method to study the dynamic mechanical properties and damage evolution path of coal-rock. It has guiding and reference significance for the theoretical research and prevention technology of coal and rock dynamic disasters.

Two-dimensionally stable self-organisation arises in simple schooling swimmers through hydrodynamic interactions

We present new constrained and free-swimming experiments and simulations in the inertial regime, with Reynolds number $\mbox{Re} = O(10^4)$ , of a pair of two-dimensional and three-dimensional pitching hydrofoils interacting in a minimal school. The hydrofoils have an out-of-phase synchronisation, and they are varied through in-line, staggered and side-by-side formations within the two-dimensional interaction plane. It is discovered that there is a two-dimensionally stable equilibrium point for a side-by-side formation. This formation is super-stable, meaning that hydrodynamic forces will passively maintain this formation even under external perturbations, and the school as a whole has no net forces acting on it that cause it to drift to one side or the other. Previously discovered one-dimensionally stable equilibria driven by wake vortex interactions are shown to be, in fact, two-dimensionally unstable, at least for an out-of-phase synchronisation. Additionally, it is discovered that a trailing-edge vortex mechanism provides the restorative force to stabilise a side-by-side formation. The stable equilibrium is further verified by experiments and simulations for freely swimming foils where dynamic recoil motions are present. When constrained, swimmers in compact side-by-side formations experience collective efficiency and thrust increases up to 40 % and 100 %, respectively, whereas slightly staggered formations output an even higher efficiency improvement of 84 %, with an 87 % increase in thrust. Freely swimming foils in a stable side-by-side formation show efficiency and speed enhancements of up to 9 % and 15 %, respectively. These newfound schooling performance and stability characteristics suggest that fluid-mediated equilibria may play a role in the control strategies of schooling fish and fish-inspired robots.

Multistability and Robustness of Competitive Neural Networks With Time-Varying Delays.

This article is devoted to analyzing the multistability and robustness of competitive neural networks (NNs) with time-varying delays. Based on the geometrical structure of activation functions, some sufficient conditions are proposed to ascertain the coexistence of ∏i=1n(2Ri+1) equilibrium points, ∏i=1n(Ri+1) of them are locally exponentially stable, where n represents a dimension of system and Ri is the parameter related to activation functions. The derived stability results not only involve exponential stability but also include power stability and logarithmical stability. In addition, the robustness of ∏i=1n(Ri+1) stable equilibrium points is discussed in the presence of perturbations. Compared with previous papers, the conclusions proposed in this article are easy to verify and enrich the existing stability theories of competitive NNs. Finally, numerical examples are provided to support theoretical results.

Characterization and feeding value of mixed broccoli by-product silage for finishing lambs in confinement

The use of agricultural by-products in animal nutrition is increasingly being considered to address livestock feed shortages, reduce feed costs, and diminish environmental pollution. While some studies have investigated broccoli by-products as livestock feed, few have focused on the nutrition of finishing lambs. This study aims to evaluate the characteristics of broccoli by-product silage (BBS) and the effect of the complete replacement of forage with BBS in the diet of male Mehraban finishing lambs on growth performance, nutrient intake, digestibility, and meat characteristics. Sixteen Mehraban ram lambs (270.7 ± 1.4 days old; body weight of 28.3 ± 1.5kg) were individually housed for 60 days and adapted to feed and housing for 14 days. The experimental diets included the control diet (diet without BBS) and the BBS diet (diet containing 330g/kg DM BBS). The broccoli by-product before ensiling was mixed with wheat straw and ground barley grain in a ratio of 80:15:5 on a fresh weight basis. The pH, aerobic stability and Fleig point of BBS were 4.9, 71h and 75.9, respectively. The values for dry matter intake and live weight at slaughter (LWS) were lower in lambs fed the BBS diet than in those fed the control diet (P < 0.001 and P = 0.03, respectively). Average daily gain and feed conversion ratio did not differ between lambs fed the experimental diets. The feed cost per kg and cost per kg of LWS in the BBS diet were 19.5% and 25.7% lower than in the control diet, respectively. Digestibility of nutrients (DM, OM, CP, EE, and NDF) did not differ between treatments. Most carcass traits and cuts did not differ between treatments (P > 0.05) but the longissimus lumborum m. (LL) muscle area (cm2), skin, brisket, and tail fat (as a percentage of LWS) were lower in lambs fed BBS than in those fed the control diet (P < 0.01). The internal organs (a percentage of LWS) of lambs fed the experimental diets were not affected by the treatments except for the heart (P = 0.005), which was higher in lambs fed the control diet. For meat color stability, no significant differences were observed in the values of lightness (L⁎), redness (a⁎), yellowness (b⁎), chroma, red color (R), green color (G), and blue color (B) between the two treatments, however, the hue angle (h⁎) was greater in lambs fed BBS than in those fed the control diet (P = 0.002). In conclusion, BBS can be fed to finishing lambs; however, further dose-response studies may be needed to determine the optimal levels and mixtures of BBS for inclusion in lamb diets.

Efficient contact-based registration for minimally invasive anterior hip arthroplasty

This paper introduces an efficient contact-based registration method for minimally invasive anterior hip arthroplasty. Unlike existing methods that involve radiation exposure, implanted screws, or tedious point collection, our method requires only one contact within the acetabulum and two contacts on the landmarks. Inspired by the probe’s ball tip, we define a unique position, named stable point, to decouple translation from the overall transformation. The stable point in patient space is easily acquired by our tool, simplifying translation estimation to compute the stable point in image space. We present a fast computation method based on dichotomic search. After aligning the stable points, we introduce two bone landmarks for rotation estimation in a center-aware manner. Additionally, a deltille grid position-sensing (DGPS) marker is used to improve instrument tracking robustness. Experiments were conducted to evaluate the performance of our methods, demonstrating an average accuracy of 0.16±0.03mm for instrument tracking and 1.41±0.16mm for registration. Moreover, the entire process takes less than 1 minute. Results suggest that our method has significant potential for clinical application.

The application of improved SURF optical flow algorithm in seismic support safety monitoring system

Frequent earthquakes pose a major threat to the safety of building structures. As a critical component of earthquake-resistant systems, dynamic health monitoring of seismic isolation bearings is essential. However, existing monitoring methods are limited by high cost and poor environmental adaptability, and it is difficult to meet real-time requirements under complex conditions. Therefore, this study combines the stable acceleration feature point matching with the optical flow algorithm, and uses the proportional purification method and the bidirectional purification method to effectively match and purify the feature points. By optimizing the feature point matching and dynamic tracking accuracy, a seismic bearing safety monitoring system based on the improved feature optical flow algorithm is designed. The experimental results show that the improved model achieves a feature recognition rate of >90 %, and the number of feature tracking losses is <70. At the same time, the displacement time history curve of the seismic isolation bearing and the laser displacement sensor has the highest degree of fit, the error of the horizontal displacement peak is 2.13 %, and the absolute error is <0 .3mm. Compared with traditional methods, this system achieves high-precision real-time monitoring at a low cost, providing reliable technical support for the health management of seismic isolation bearings, and also opens up a new direction in the field of structural health monitoring.

Iterative neural networks for improving memory capacity

In recent years, the problem of the multistability of neural networks has been studied extensively. From the research results obtained, the number of stable equilibrium points depends only on a power form of the network dimension. However, in practical applications, the number of stable equilibrium points needed is often not expressed in power form. Therefore, can we determine an appropriate activation function so that the neural network has exactly the required number of stable equilibrium points? This paper provides a new way to study this problem by means of an iteration method. The necessary activation function is constructed by an appropriate iteration method, and the neural network model is established. Based on the mathematical theories of matrix analysis and functional analysis and on the inequality method, the number and distribution of the network equilibrium points are determined by dividing the state space reasonably, and some multistability criteria that are related to the number of iterations and are independent of the network dimension are established.

Comparison of technological and physical properties of matcha powders of different geographical origins.

The sorption characteristics and glass transition temperature are important attributes that determine the shelf life of foods, particularly in powder form, whereas color is a key factor influencing consumer acceptance. As the popularity of matcha green tea powder is increasing, this study investigated whether the country of origin of examples of matcha products available on the Polish market influenced the sorption properties, glass transition temperature, and color. All matcha powders exhibited sigmoidal water adsorption isotherms at 25 °C. The monolayer moisture content corresponding to the point of maximum stability ranged from 0.045 to 0.053 g water per g of sample. The glass transition temperature of anhydrous matcha powders varied between 106.3 and 139.0 °C. Based on the sorption and glass transition results, the matcha from Brazil should be the most stable during storage. The same sample showed the highest water solubility index values at temperatures above 80 °C and the lowest bulk density. The color parameters (L*, a*, b*, C*, and h) depended on the matcha powder variant. The results indicate that the optimal storage conditions for tea powders do not depend directly on the country of origin. Further research should therefore focus on analyzing the impact of climate or fertilization. © 2024 Society of Chemical Industry.