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The paper deals with terrestrial locomotion systems. Worms and snakes are living paragons for the development of biological inspired crawling robots. We set up certain models of worm- and snake-like locomotion systems and present purely analytical investigations in this paper. We try to follow an analytical framework, i.e., analyzing kinematics at first. Later on, we switch to dynamics and control of these models, to get hints for a technical development. The systems are modeled as chains of mass points. The mass points are interconnected via massless links with time-varying link-length. In contrast to the literature, the snake systems exhibit passive joints, but active links and rotatable skids. The combination of shape variation (via active links) together with the ground contact (via ideal spikes guaranteeing a one-sided velocity restriction) results in a global movement of the systems — undulatory locomotion. In dynamics, these link functions should be adjusted via, e.g., a force actuator between each mass point. Because it is impossible to determine a-priori these force outputs generating a desired gait, we apply an adaptive controller which adjusts these force outputs on-line on its own and λ -tracks a certain gait to achieve a movement of the whole system. [ABSTRACT FROM AUTHOR]

This paper presents an optimal control strategy and a cost effectiveness analysis for the Zika virus disease. A mathematical model for the transmission of the Zika virus is considered with four preventive measures as control, namely: the use of treated bednets, the use of condoms, a medical treatment of infected persons, and the use of indoor residual spray (IRS). We obtain the reproduction number R 0 for the disease and carry out a stability analysis. We observe that the disease’s free equilibrium state is stable when R 0 < 1 but unstable when R 0 > 1 , which leads to a spread of the disease. We examine the implementation of various combinations of the possible control strategies in order to determine the most cost-effective one. Based on the computational results, we conclude that a strategy that consists of treated bednets, treatment of symptomatic infected humans and indoor residual spray is the most cost effective strategy. [ABSTRACT FROM AUTHOR]

Zika virus is a flavivirus transmitted to humans primarily through the bite of infected Aedes mosquitoes. In addition to vector-borne spread, however, the virus can also be transmitted through sexual contact. In this paper, we formulate and analyze a new system of ordinary differential equations which incorporates both vector and sexual transmission routes. Theoretical analysis of this model when there is no disease induced mortality shows that the disease-free equilibrium is locally and globally asymptotically stable whenever the associated reproduction number is less than unity and unstable otherwise. However, when we extend this same model to include Zika induced mortality, which have been documented in Latin America, we find that the model exhibits a backward bifurcation. Specifically, a stable disease-free equilibrium co-exists with a stable endemic equilibrium when the associated reproduction number is less than unity. To further explore model predictions, we use numerical simulations to assess the importance of sexual transmission to disease dynamics. This analysis shows that risky behavior involving multiple sexual partners, particularly among male populations, substantially increases the number of infected individuals in the population, contributing significantly to the disease burden in the community. [ABSTRACT FROM AUTHOR]

Abstract: In this paper we describe the moments of a stochastic model of the Additive Increase Multiplicative Decrease (AIMD) algorithm. AIMD is the algorithm that underpins the Transmission Control Protocol (TCP), which is used extensively in the internet. We prove that the Markov chain describing TCP has the remarkable property that all moments converge to their asymptotes at exactly the same rate. Further, we illustrate how a closed form solution can be obtained from the network properties, and this formula is explicitly calculated for the case of the third moment. [Copyright &y& Elsevier]

In the present paper, we develop a simple two species prey–predator model in which the predator is partially coupled with alternative prey. The aim is to study the consequences of providing additional food to the predator as well as the effects of harvesting efforts applied to both the species. It is observed that the provision of alternative food to predator is not always beneficial to the system. A complete picture of the long run dynamics of the system is discussed based on the effort pair as control parameters. Optimal augmentations of prey and predator biomass at final time have been investigated by optimal control theory. Also the short and large time effects of the application of optimal control have been discussed. Finally, some numerical illustrations are given to verify our analytical results with the help of different sets of parameters. [ABSTRACT FROM AUTHOR]