Search

In this work, we set up a new discrete predator–prey competitive model with time-varying delays and feedback controls. By virtue of the difference inequality knowledge, a sufficient condition which guarantees the permanence of the established discrete predator–prey competitive model with time-varying delays and feedback controls is derived. Under some appropriate parameter conditions, we have proved that the periodic solution of the system without delay exists and globally attractive. To verify the correctness of the derived theoretical fruits, we give two examples and execute computer simulations. Our obtained results are novel and complement previous known results. [ABSTRACT FROM AUTHOR]

Introduction: Pregnanediol-3-glucuronide (PdG), as the main metabolite of progesterone in urine, plays a significant role in the prediction of ovulation, threatened abortion, and menstrual cycle maintenance.Methods: To achieve a rapid and sensitive assay, we have designed a competitive model-based time-resolved fluorescence microsphere-lateral flow immunochromatography (TRFM-LFIA) strip.Results: The optimized TRFM-LFIA strip exhibited a wonderful response to PdG over the range of 30–2,000 ng/mL, the corresponding limit of detection (LOD) was calculated as low as 8.39 ng/mL. More importantly, the TRFM-LFIA strip was innovatively used for the quantitative detection of PdG in urine sample, and excellent recovery results were also obtained, ranging from 97.39% to 112.64%.Discussion: The TRFMLFIA strip possessed robust sensitivity and selectivity in the determination of PdG, indicating the great potential of being powerful tools in the biomedical and diagnosis region.

In this work, we set up a new discrete predator–prey competitive model with time-varying delays and feedback controls. By virtue of the difference inequality knowledge, a sufficient condition which guarantees the permanence of the established discrete predator–prey competitive model with time-varying delays and feedback controls is derived. Under some appropriate parameter conditions, we have proved that the periodic solution of the system without delay exists and globally attractive. To verify the correctness of the derived theoretical fruits, we give two examples and execute computer simulations. Our obtained results are novel and complement previous known results.

In this paper, we propose a simplified bidimensional Wolbachia infestation model in a population of Aedes aegypti mosquitoes, preserving the main features associated with the biology of this species that can be found in higher-dimensional models. Namely, our model represents the maternal transmission of the Wolbachia symbiont, expresses the reproductive phenotype of cytoplasmic incompatibility, accounts for different fecundities and mortalities of infected and wild insects, and exhibits the bistable nature leading to the so-called principle of competitive exclusion. Using tools borrowed from monotone dynamical system theory, in the proposed model, we prove the existence of an invariant threshold manifold that allows us to provide practical recommendations for performing single and periodic releases of Wolbachia-carrying mosquitoes, seeking the eventual elimination of wild insects that are capable of transmitting infections to humans. We illustrate these findings with numerical simulations using parameter values corresponding to the wMelPop strain of Wolbachia that is considered the best virus blocker but induces fitness loss in its carriers. In these tests, we considered multiple scenarios contrasting a periodic release strategy against a strategy with a single inundative release, comparing their effectiveness. Our study is presented as an expository and mathematically accessible tool to study the use of Wolbachia-based biocontrol versus more complex models.

This study assesses the consistency of the structural components of a model for developing a competitive health and well-being destination as viewed by health and well-being tourism entrepreneurs in an emerging Thai market. The sample consisted of 216 health and well-being tourism entrepreneurs recruited by purposive sampling. A questionnaire formatted using a five-point Likert scale was used. The questionnaire’s Index of Item-Objective Congruence (IOC) varied from 0.60 to 1.00, and its reliability ranged from 0.711 to 0.938. Statistical analysis, frequencies, percentages, means, standard deviations, exploratory factor analysis and confirmatory factor analysis were utilised. The findings revealed the following seven model components: 1) health and well-being tourism resources and attractions, 2) infrastructure and facilities, 3) service design and development, 4) policy, planning and destination management, 5) knowledge management and learning organisation, 6) destination management and 7) innovative capacity. Governors, entrepreneurs, destination managers and stakeholders can use the discovered variables to evaluate a competitive health and well-being destination’s expected performance, strengths, weaknesses and development opportunities. Further, this research should enable continuing support through the critical variable factors.

Filippov systems have found applications in various fields. This paper mainly studies five Lotka–Volterra models of Filippov type, including a competitive system with linear interaction between two species, a competitive system with Holling type II or type III functional response and a symbiosis system with Holling type II or type III functional response. We investigate the stability of all equilibria and the boundary equilibrium bifurcations of these systems, either a persistence bifurcation or a nonsmooth fold bifurcation. We present the numerical simulation results for each case. Consequently, based on both theory and simulation, we analyze the ecological aspects under the intervention of harvesting at different prescribed thresholds. [ABSTRACT FROM AUTHOR]

Abstract The aim of this paper is to investigate the optimal harvesting strategies of a stochastic competitive Lotka–Volterra model with S-type distributed time delays and Lévy jumps by using ergodic method. Firstly, the sufficient conditions for extinction and stable in the time average of each species are established under some suitable assumptions. Secondly, under a technical assumption, the stability in distribution of this model is proved. Then the sufficient and necessary criteria for the existence of optimal harvesting policy are established under the condition that all species are persistent. Moreover, the explicit expression of the optimal harvesting effort and the maximum of sustainable yield are given.

This paper presents an investigation on the dynamics of a delayed diffusive competition model with saturation effect. We first perform the stability analysis of the positive equilibrium and the existence of Hopf bifurcations. It is shown that the positive equilibrium is asymptotically stable under some conditions, and that there exists a critical value of delay, when the delay increases across it, the positive equilibrium loses its stability and a spatially homogeneous or inhomogeneous periodic solution emerges from the positive equilibrium. Then, we derive the formulas for the determination of the direction of Hopf bifurcation and the properties of the bifurcating periodic solutions. Finally, some numerical simulations are performed to illustrate the obtained results.

This article concerns a two-species competitive model with diffusive terms in a periodically evolving domain and study the impact of the spatial periodic evolution on the dynamics of the model. The Lagrangian transformation approach is adopted to convert the model from a changing domain to a fixed domain with the assumption that the evolution of habitat is uniform and isotropic. The ecological reproduction indexes of the linearized model are given as thresholds to reveal the dynamic behavior of the competitive model. Our theoretical results show that a lager evolving rate benefits the persistence of competitive populations for both sides in the long run. Numerical experiments illustrate that two competitive species, one of which survive and the other vanish in a fixed domain, both survive in a domain with a large evolving rate, and both vanish in a domain with a small evolving rate.

Overf the last few years, by utilizing Mawhin’s continuation theorem of coincidence degree theory and Lyapunov functional, many scholars have been concerned with the global asymptotical stability of positive periodic solutions for the non-linear ecosystems. In the real world, almost periodicity is usually more realistic and more general than periodicity, but there are scarcely any papers concerning the issue of the global asymptotical stability of positive almost periodic solutions of non-linear ecosystems. In this paper we consider a kind of delayed two-species competitive model with stage structure. By means of Mawhin’s continuation theorem of coincidence degree theory, some sufficient conditions are obtained for the existence of at least one positive almost periodic solutions for the above model with nonnegative coefficients. Furthermore, the global asymptotical stability of positive almost periodic solution of the model is also studied. The work of this paper extends and improves some results in recent years. An example and simulations are employed to illustrate the main results of this paper.

The aim of this paper is to investigate the optimal harvesting strategies of a stochastic competitive Lotka–Volterra model with S-type distributed time delays and Lévy jumps by using ergodic method. Firstly, the sufficient conditions for extinction and stable in the time average of each species are established under some suitable assumptions. Secondly, under a technical assumption, the stability in distribution of this model is proved. Then the sufficient and necessary criteria for the existence of optimal harvesting policy are established under the condition that all species are persistent. Moreover, the explicit expression of the optimal harvesting effort and the maximum of sustainable yield are given. [ABSTRACT FROM AUTHOR]

Energy hub concept has been emerged as a suitable tool to analyze multi-carrier energy systems. Deregulation and increasing competition in the energy industry have provided a suitable platform for developing the multi-agent energy systems. Planning of energy hubs considering the competition between the hubs has not been sufficiently addressed, yet. A model has been proposed in this study for planning of a multi-hub energy system considering the competition between the hubs. The hubs are interconnected via an electric transmission system. A linear model has been developed to determine the optimal planning/operation strategy for energy hubs in a multi-period planning horizon to meet the heat and electricity demand for the defined load zone. The problem has been formulated and solved using Karush-Kuhn-Tucker (KKT) conditions. The proposed model has been applied to 3-Hub and 5-Hub energy systems. The effect of renewable generation and storage system has also been evaluatedIt has also been observed that inclusion of renewable generation or storage technologies can reduce the conventional electricity generation capacity by 63 percent in HUB2. [ABSTRACT FROM AUTHOR]

Abstract. We consider a geographical region with spatially separated customers, whose demand is currently served by some pre-existing facilities owned by different firms. An entering firm wants to compete for this market locating some new facilities. Trying to guarantee a future satisfactory captured demand for each new facility, the firm imposes a constraint over its possible locations (a finite set of candidates): a new facility will be opened only if a minimal market share is captured in the short-term. To check that, it is necessary to know the exact captured demand by each new facility. It is supposed that customers follow the partially binary choice rule to satisfy its demand. If there are several new facilities with maximal attraction for a customer, we consider that the proportion of demand captured by the entering firm will be equally distributed among such facilities (equity-based rule). This ties breaking rule involves that we will deal with a nonlinear constrained discrete competitive facility location problem. Moreover, minimal attraction conditions for customers and distances approximated by intervals have been incorporated to deal with a more realistic model. To solve this nonlinear model, we first linearize the model, which allows to solve small size problems because of its complexity, and then, for bigger size problems, a heuristic algorithm is proposed, which could also be used to solve other constrained problems. [ABSTRACT FROM AUTHOR]

This paper deals with a stochastic two-species competitive model. Some very verifiable criteria on the global stability of the positive equilibrium of the deterministic system are established. An example with its computer simulations is given to illustrate our main theoretical findings.

The simulation of population dynamics and social processes is of great interest in nonlinear systems. Recently, many scholars have paid attention to the possible applications of population dynamics models, such as the competitive Lotka–Volterra equation, in economic, demographic and social sciences. It was found that these models can describe some complex behavioral phenomena such as marital behavior, the stable marriage problem and other demographic processes, possessing chaotic dynamics under certain conditions. However, the introduction of external factors directly into the continuous system can influence its dynamic properties and requires a reformulation of the whole model. Nowadays most of the simulations are performed on digital computers. Thus, it is possible to use special numerical techniques and discrete effects to introduce additional features to the digital models of continuous systems. In this paper we propose a discrete model with controllable phase-space volume based on the competitive Lotka–Volterra equations. This model is obtained through the application of semi-implicit numerical methods with controllable symmetry to the continuous competitive Lotka–Volterra model. The proposed model provides almost linear control of the phase-space volume and, consequently, the quantitative characteristics of simulated behavior, by shifting the symmetry of the underlying finite-difference scheme. We explicitly show the possibility of introducing almost arbitrary law to control the phase-space volume and entropy of the system. The proposed approach is verified through bifurcation, time domain and phase-space volume analysis. Several possible applications of the developed model to the social and demographic problems’ simulation are discussed. The developed discrete model can be broadly used in modern behavioral, demographic and social studies.

Introduction: Pregnanediol-3-glucuronide (PdG), as the main metabolite of progesterone in urine, plays a significant role in the prediction of ovulation, threatened abortion, and menstrual cycle maintenance. Methods: To achieve a rapid and sensitive assay, we have designed a competitive model-based time-resolved fluorescence microsphere-lateral flow immunochromatography (TRFM-LFIA) strip. Results: The optimized TRFM-LFIA strip exhibited a wonderful response to PdG over the range of 30-2,000 ng/mL, the corresponding limit of detection (LOD) was calculated as low as 8.39 ng/mL. More importantly, the TRFM-LFIA strip was innovatively used for the quantitative detection of PdG in urine sample, and excellent recovery results were also obtained, ranging from 97.39% to 112.64%. Discussion: The TRFMLFIA strip possessed robust sensitivity and selectivity in the determination of PdG, indicating the great potential of being powerful tools in the biomedical and diagnosis region., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Lin, Li, Ye, Zheng, Wang, Liu, Wang, Wu, Dong and Zan.)

Under current competitive liner shipping market, it is crucial to explore the optimal shipping strategy for the subsistence and development of liner companies. In order to establish a liner shipping competitive model, we choose service quality, which can be measured by a range of unstructured data of relative items (such as delivery service, security, processing speed, user-friendliness) with big data analytics, as a key factor in the utility function and analyze the impact of service quality on the pricing strategy for container liner shipping context. By using the analytic hierarchy process, fuzzy comprehensive evaluation and time series forecasting method, the concrete data from South America container liner shipping market is analyzed via empirical study. The finding has demonstrated the model could yield management value for liner companies, and could provide theoretical guidance to formulate the optimal liner shipping strategy. [ABSTRACT FROM AUTHOR]

Modern regional management needs special regional policy aimed at making the competitive potential of the region as a factor of its sustainable development. In this regard, the main task of this study is to base the nature, structure and destination of competitive potential for regional management, as well as the development of its grade methodology. It is proposed to consider the competitive potential of the region as a set of available resources, tools, and sources of various properties, which belong to the territory and which help to attract attention of aimed customers (investors, entrepreneurs, residents, tourists, etc.) at it, increase of the demand for some of its elements, which can be used in competition, making unique resources and capabilities into competitive advantages. Along with the traditional elements of the competitive potential of the region some elements were offered to include in its structure. Those elements show modern organizational and economic relations of the regional productive forces. The assessing technique of the competitive potential level of the region was developed. One of its most important areas of practical use the results are the organization of the formation potential monitoring for local, regional, and national governance.

Lévy noise, accounting for sudden catastrophic shocks, exists widely in the natural world. However, the effect of Lévy noise on the survival of a population is not well understood. In this paper, we develop and investigate a stochastic competitive model of two species with Lévy noise in an impulsive polluted environment. The threshold between weak persistence in the mean and extinction is established for each species. Sufficient conditions for strong persistence in the mean, stability in the mean and stochastic permanence are obtained. These results show that Lévy noise can change the persistence and extinction of each species significantly. Numerical simulations is carried out to illustrate the theoretical results. [ABSTRACT FROM AUTHOR]

This paper is concerned with a stochastic competitive model with Markov switching. Sufficient conditions for stochastic permanence, extinction, global attractivity and stability in distribution are established. Some numerical figures are introduced to validate the theoretical results. [ABSTRACT FROM AUTHOR]

This paper adds to the growing remanufacturing literature by investigating a collaborative model in which the manufacturer serves as the remanufacturer's distributor while selling its own product. The paper extends the collaborative model that we have studied previously by characterizing it as a channel power structure under which the manufacturer plays the leader role in the collaboration. Furthermore, the paper compares this collaborative model with a competitive model in which the manufacturer competes with the remanufacturer in the market on pricing, sales volume and profit and finds that even if the manufacturer chooses to collaborate with the remanufacturer, it does not give up its market position; the manufacturer keeps the price of its product unchanged as the remanufactured product becomes increasingly acceptable to the consumer, and its product's sales volume remains unchanged in both models. Finally, this paper observes that the collaborative model benefits the manufacturer more than the competitive model, whereas the competitive model benefits the remanufacturer more than the collaborative model. Obviously, if collaboration benefits both of the manufacturer and remanufacturer, they will choose to collaborate, and the manufacturer will transfer part of its profit to the remanufacturer, but if competition brings them more profit, they will choose to compete in the market, and the remanufacturer will transfer part of its profit to the manufacturer. [ABSTRACT FROM AUTHOR]

In this paper, we propose a simplified bidimensional Wolbachia infestation model in a population of Aedes aegypti mosquitoes, preserving the main features associated with the biology of this species that can be found in higher-dimensional models. Namely, our model represents the maternal transmission of the Wolbachia symbiont, expresses the reproductive phenotype of cytoplasmic incompatibility, accounts for different fecundities and mortalities of infected and wild insects, and exhibits the bistable nature leading to the so-called principle of competitive exclusion . Using tools borrowed from monotone dynamical system theory, in the proposed model, we prove the existence of an invariant threshold manifold that allows us to provide practical recommendations for performing single and periodic releases of Wolbachia -carrying mosquitoes, seeking the eventual elimination of wild insects that are capable of transmitting infections to humans. We illustrate these findings with numerical simulations using parameter values corresponding to the wMelPop strain of Wolbachia that is considered the best virus blocker but induces fitness loss in its carriers. In these tests, we considered multiple scenarios contrasting a periodic release strategy against a strategy with a single inundative release, comparing their effectiveness. Our study is presented as an expository and mathematically accessible tool to study the use of Wolbachia-based biocontrol versus more complex models.

Abstract: This note is concerned with a stochastic competitive system with time delays. Under a simple assumption, almost sufficient and necessary conditions for stability in time average and extinction of each population are established. Some numerical simulations are introduced to illustrate the main results. [Copyright &y& Elsevier]

Instead of the currently prevailing competitive model, a more collaborative strategy is needed to address the concerns related to the sustainability of today’s business. This article aims to explore collaborative approaches where enterprises seek to build long-term, mutually beneficial relationships with all stakeholders and want to produce sustainable values for their whole business ecosystem. Cases here analyzed demonstrate that alternative ways of doing business are possible. These enterprises share more democratic ownership structures, more balanced and broader governance systems, and a more comprehensive view of organizational goals and performance – which goes beyond the narrow concept of financial bottom line and into a stronger and systematic care of the needs and requirements of the different stakeholder groups. Thanks to this evidence and different theoretical and empirical contributions, we suggest that the strength and sustainability of enterprises come from their ability to fit into the environmental, social, and cultural context in which they operate. By creating values for all stakeholders, enterprises can involve them and gain deep support based on their commitment. This may lead to superior performance from a multiple-bottom-line perspective. [ABSTRACT FROM AUTHOR]

Abstract: The characteristic of “rich gets richer” is much more conspicuous on the Internet, which is the important cause of “power-law” characteristic of the “winner-takes-all” markets. A competitive model of e-commerce web sites is presented in order to explore the effects of competition and the characteristic of “rich gets richer” on Internet economy, and also to investigate how the “winner-takes-all” phenomenon comes forth. Then these ordinary differential equations are qualitatively analyzed and numerically simulated to study the dynamics of competition. The effects of parameters on the dynamic behavior in the model are also discussed. [Copyright &y& Elsevier]

A comparison of the neoclassical and the social economics paradigms, showing that the explicit inclusion of values enhances the explanatory value of social economics. This is illustrated by using literary examples to explain the difficulty the competitive model has in providing analyses and solutions for modem problems of product safety, natural resource overexploitation, urban congestion, and stakeholder rights. [ABSTRACT FROM AUTHOR]

The simulation of population dynamics and social processes is of great interest in nonlinear systems. Recently, many scholars have paid attention to the possible applications of population dynamics models, such as the competitive Lotka–Volterra equation, in economic, demographic and social sciences. It was found that these models can describe some complex behavioral phenomena such as marital behavior, the stable marriage problem and other demographic processes, possessing chaotic dynamics under certain conditions. However, the introduction of external factors directly into the continuous system can influence its dynamic properties and requires a reformulation of the whole model. Nowadays most of the simulations are performed on digital computers. Thus, it is possible to use special numerical techniques and discrete effects to introduce additional features to the digital models of continuous systems. In this paper we propose a discrete model with controllable phase-space volume based on the competitive Lotka–Volterra equations. This model is obtained through the application of semi-implicit numerical methods with controllable symmetry to the continuous competitive Lotka–Volterra model. The proposed model provides almost linear control of the phase-space volume and, consequently, the quantitative characteristics of simulated behavior, by shifting the symmetry of the underlying finite-difference scheme. We explicitly show the possibility of introducing almost arbitrary law to control the phase-space volume and entropy of the system. The proposed approach is verified through bifurcation, time domain and phase-space volume analysis. Several possible applications of the developed model to the social and demographic problems' simulation are discussed. The developed discrete model can be broadly used in modern behavioral, demographic and social studies. [ABSTRACT FROM AUTHOR]

This paper presents an investigation on the dynamics of a delayed diffusive competition model with saturation effect. We first perform the stability analysis of the positive equilibrium and the existence of Hopf bifurcations. It is shown that the positive equilibrium is asymptotically stable under some conditions, and that there exists a critical value of delay, when the delay increases across it, the positive equilibrium loses its stability and a spatially homogeneous or inhomogeneous periodic solution emerges from the positive equilibrium. Then, we derive the formulas for the determination of the direction of Hopf bifurcation and the properties of the bifurcating periodic solutions. Finally, some numerical simulations are performed to illustrate the obtained results.