Vol. 6, No. 3 (2022): Regular Issue

Dynamic evaporation and condensation processes contribute to successful operating regimes in oscillating heat pipes (OHPs), but they can also be responsible for evolution to a stagnant state where all liquid slugs are in the cold zone of the OHP system. In fact, accumulation of liquid slugs in the cold zone is considered to be the main cause for the slow startup of OHP systems. We formulate a model for the dynamics of liquid slugs and vapor plugs, which takes into account the effects of evaporation and vapor compressibility, and use it to examine mechanisms that drive the system from stagnation to oscillation. For example, modeled states where all menisci are located in the boundary between the hot and cold zones are equilibria in the presence of an imposed temperature gradient. Linear stability analysis at such equilibrium states corresponding to the stagnant case, i.e., all liquid slugs in the cold zone, is used to show that stagnant states bifurcate to self-excited oscillations when the system is subjected to sufficiently high temperature gradients. Our results extend those for an earlier model for one slug in a pipe closed at one end to a multi-slug model with pipe geometry characteristic of operational OHPs.

This paper considers a fractional order two species model incorporating pest and its predator population. It is assumed that the pest population is infected by a disease. Due to this infection, pest population is classified into two sub populations such as susceptible pest and infected pest population. For the biological control of pest species, the predator of pest population is introduced. Here, it is assumed that predator consumes susceptible as well as infected pests. The uniqueness, non-negativity and boundedness of the solutions of the fractional order system have been studied. Locally asymptotic stability of the equilibrium points has been investigated. Also, global stability of the interior equilibrium point has been analyzed. The existence condition of Hopf bifurcation in the proposed model has been studied. It is found that the stability of the model increases as the value of fractional order derivative $\alpha$ gradually decreases.

In this paper, the complete bifurcation trees of period-1 motions to chaos are predicted through discrete implicit maps for a periodically excited spring pendulum. Such discrete maps are used to construct mapping structures that describe any periodic motions in the system. Analytical bifurcation trees are obtained through the nonlinear algebraic equations of such implicit maps. The corresponding stability and bifurcations are achieved through eigenvalue analysis. For a better understanding of the motion complexity, the corresponding frequency-amplitude characteristics are presented through harmonic responses. Finally, simulation results of periodic motions are illustrated in compare to the analytical predictions.

Continuous and discrete time systems possessing strange non-chaotic attractors are under investigation. It is demonstrated that unpredictable trajectories exist in the dynamics. A recent numerical technique, the sequential test, is utilized to show the presence of unpredictability.

In order to simulate and study the firing activities of a biological neural model, different technologies have been developed in the field of neural morphology. In this paper, a Hindmarsh-Rose(HR) neuron model is analyzed numerically by a middle point integration method to unfold the complex bifurcation structures. The corresponding analog circuit is designed to reproduce the firing phenomenons according to the HR neuron model. The implementation of the circuit indicates that the circuit model reproduces several neuronal behaviors similar to the numerical model. These results can be used both to design a circuit implementation of the HR neuron model mimicking the diversity of neural response and as guidelines to achieve higher speed and lower hardware cost in large-scale implementation of the biological neural networks.