One-sided Channel Research Articles

Solidification of Cascaded PCM Storages Embedded Within a Channel Under Various Forced Air Flow Strategies

In recent years, latent heat storage systems have been received considerable attention as they can provide high thermal storage capacity and optimize energy consumption. Cascaded phase change materials (PCMs) are a significant strategy to manage the gap between energy supply and demand, especially in renewable thermal energy applications. This work is devoted to investigate the unsteady freezing process of cascaded latent heat thermal energy storage systems inside a channel under different forced airflow strategies for winter conditions. Cold air flows through cascaded PCMs in five various ways and starts changing their initial liquid status to the final solid phase. Results discuss the heat transfer and phase transition features of each strategy in four various Reynolds numbers. Two-dimensional finite volume method is utilized to solve the governing equations of incompressible fluid flow in which conduction and convection mechanisms within PCM chambers are taken into account. According to numerical results, U-type and counter flow schemes lead to quick solidification in all Reynolds numbers, while in one-side channel strategy, the system takes a longer time to be completely solidified in all Reynolds numbers except Re = 300 in which parallel flow and middle inlets methods cause later freezing. The aspect ratio of PCM cavities and outlet temperature of the flowing air are also studied for various cases. Results demonstrated that the lower aspect ratio of the counter flow strategy could solidify the PCM faster and could remove the higher value of heat from cavities (higher outlet temperature).

Novel Outer Bounds and Capacity Results for the Interference Channel With Conferencing Receivers

In this paper, capacity bounds for the two-user interference channels with cooperative receivers via conferencing links of finite capacities are investigated. Capacity results known for these communication scenarios are limited to a very few special cases of the one-sided channels. One of the challenges in obtaining capacity limits of such cooperative networks is how to establish efficient capacity outer bounds for them. In this paper, by applying new techniques, novel capacity outer bounds are established for the interference channels with conferencing receivers. Using the outer bounds, several new capacity results are proved for interesting channels with unidirectional cooperation in strong and mixed interference regimes. A conferencing link (between receivers) may be utilized to provide a receiver with “information about its desired signal” or “information about its interfering signal”. It is demonstrated that both strategies can be helpful to achieve capacity. Finally, for the case of Gaussian interference channel with conferencing receivers, it is argued that our outer bound is strictly tighter than the previous one derived by Wang and Tse.

Classically high-dimensional correlation: simulation of high-dimensional entanglement.

Classical correlation, akin to the entanglement of quantum states, has been proven to bear a great promise in classical and quantum systems, such as enhancing measurement precision and characterizing quantum channels. Despite numerous successful applications of such correlation, it is strictly limited to two orthogonal bases and fails to further extend its dimensionality in practice. Here, we report a classically high-dimensional correlation, which is mathematically equivalent to its quantum counterparts and can be used to simulate the violations of the high-dimensional Bell inequalities. Moreover, we also show theoretically that quantum channels with high-dimensional quantum states can be characterized robustly using our scheme when a one-sided channel is perturbed by a turbulent atmosphere. This means that our results not only provide new physical insights into the notion of classical correlation, but also show potential applications in high-dimensional quantum information processing.

Modeling hydrodynamics and heat exchange in response to liquid metal buoyant flow in a rectangular channel in a coplanar magnetic field

The hydrodynamics and heat exchange in response to liquid metal (LM) buoyant flow in a rectangular channel with approximately 3/1 aspect ratio in a coplanar magnetic field (MF) on the assumption of one-sided channel heating have been studied. The flow configuration is approximated to the heat exchange channel of the cooling system of a TOKAMAK fusion reactor LM blanket. Experiments were performed on the mercury magneto-hydrodynamic (MHD) test stand as part of MPEI – JIHT of RAS facility. Under the conditions of buoyant flow, the measurable effect of thermal gravitational convection (TGC) interacting with the external MF in some environments was detected, it causes occurrence and development of layered flow variabilities. Averaged velocity, channel wall temperature profiles are shown. The MF causes suppression of turbulent transfer resulting in an increase in heated wall temperature. A numerical model of target values under experimental conditions is proposed. In the process of numerical simulation, the differential equation system: the continuity equation, the motion equation for three velocity components and the energy equation, was solved. To compute turbulence, the Reihardt model adapted for the rectangular channel was used. Computational data agree satisfactorily with experimental data.

Most robust and fragile two-qubit entangled states under deploarizing channels

For a two-qubit system under local depolarizing channels, the most robust and most fragile states are derived for a given concurrence or negativity. For the one-sided channel, the pure states are proved to be the most robust ones, with the aid of the evolution equation for entanglement given by Konrad \emph{et al.} [Nat. Phys. 4, 99 (2008)]. Based on a generalization of the evolution equation for entanglement, we classify the ansatz states in our investigation by the amount of robustness, and consequently derive the most fragile states. For the two-sided channel, the pure states are the most robust for a fixed concurrence. Under the uniform channel, the most fragile states have the minimal negativity when the concurrence is given in the region $[1/2,1]$. For a given negativity, the most robust states are the ones with the maximal concurrence, and the most fragile ones are the pure states with minimum of concurrence. When the entanglement approaches zero, the most fragile states under general nonuniform channels tend to the ones in the uniform channel. Influences on robustness by entanglement, degree of mixture, and asymmetry between the two qubits are discussed through numerical calculations. It turns out that the concurrence and negativity are major factors for the robustness. When they are fixed, the impact of the mixedness becomes obvious. In the nonuniform channels, the most fragile states are closely correlated with the asymmetry, while the most robust ones with the degree of mixture.

High-Rate Distributed Space-Time-Frequency Coding for Wireless Cooperative Networks

In this paper, we propose high-rate distributed space-time-frequency codes (DSTFCs) to exploit maximum achievable diversity gains over frequency-selective fading channels. The proposed designs achieve full-rate for any number of cooperative nodes, and allow channel variations over multiple OFDM blocks within one DSTFC codeword. We analyze diversity gains of DSTFCs through both conditional and average pairwise error probability (PEP), and we proposes better design criteria based on one-side channel conditional PEP. We show that the difference between the frequency-selective channel orders of source-to-relay and relay-to-destination links may provide extra diversity advantages, thus additional performance gains. Through Monte-Carlo simulations, we demonstrate that proposed high-rate DSTFCs provide notable diversity advantages over existing designs.