Developing a Fuzzy-Stochastic Multi Objectives Inventory Model

In this paper we developed an inventory model in mixed imprecise and uncertain environment. Presented model is developed form of (r,Q) and is a multi-items model with two objectives as minimizing costs (holding & shortage) and risk level under constraints including available budgetary, the least service level, storage spaces & allowable quantities of shortage. Demand distribution functions are assumed to be exponential and extra demands are supposed in two situations as lost sales and backlogging. At first we develop crisp model then fuzzy stochastic model with fuzzy budgetary, allowable quantities of shortage and shortage spaces (i.e. stochastic with normal distribution function) parameter. All of fuzzy numbers are triangular type. In methodology of solution we change model to a crisp multi-­objective by using difuzzification of fuzzy constraints and fuzzy chance-constrained programming methods, and then solve it by fuzzy logic method. Finally an illustrated example is taken and solved using LINGO package

Bio-moleculear thermal oscillator and constant heat current source

The demand for materials and devices that are capable of controlling heat flux has attracted many interests due to desire to attain new sources of energy and on-chip cooling. Excellent properties of DNA make it as an interesting nanomaterial in future technologies. In this paper, we aim to investigate the thermal flow through two sequence combinations of DNA, e.g, (AT)4 (CG)4 (AT)4 (CG)4 and (CG)8 (AT)8. Two interesting phenomena have been observed respectively. In the first configuration, an oscillatory thermal flux is observed. In this way, an oscillating heat flux from a stationary spatial thermal gradient is provided by varying the gate temperature. In the second configuration, the system behaves as a constant heat current source. The physical mechanism behind each phenomenon is identified. In the first case, it was shown that the transition between thermal positive conductance and negative differential conductance implies oscillatory heat current. In the latter, the discordance between the phonon bands of the two coupled sequences results in constant thermal flow despite of increasing in temperature gradient

Ballistic induced pumping of hypersonic heat current in DNA nano wire

Heat shuttling properties of DNA nano-wire driven by an external force against the spontaneous heat current direction in non-zero temperature bias (non averaged) have been studied. We examined the valid region of driving amplitude and frequency to have pumping state in terms of temperature bias and the system size. It was shown that DNA could act as a high efficiency thermal pump in the hypersonic region. Amplitude-dependent resonance frequencies of DNA indicating intrinsic base pair internal vibrations have been detected. Nonlinearity implies that by increasing the driven amplitude new vibration modes are detected. To verify the results, an analytical parallel investigation based on multifractal concept has been done. By using the geometric properties of the strange attractor of the system, the threshold value to transition to the pumping state for given external amplitude has been identified. It was shown that the system undergoes a phase transition in sliding point to the pumping state. Fractal dimension demonstrates that the ballistic transport is responsible for energy pumping in the system. In the forbidden band gap, DNA could transmit the energy by exceeding the threshold amplitude. Despite of success in energy pumping, in this framework, DNA could not act as a real cooler