Transmission Game in MIMO Interference Channels With Radio-Frequency Energy Harvesting

For multi-user transmissions over MIMO interference channels, each user designs the transmit covariance matrix to maximize its information rate. When passive radio-frequency (RF) energy harvesters are present in the network, the transmissions are constrained by both the transmit power limits and the energy harvesting requirements. A passive RF energy harvester collects the radiated energy from nearby wireless information transmitters instead of using a dedicated wireless power source. It needs multiple transmitters to concentrate their RF radiation on it because typical electric field strengths are weak. In this paper, strategic games are proposed for the multi-user transmissions. First, in a non-cooperative game, each transmitter has a best-response strategy for the transmit covariance matrix that follows a multi-level water-filling solution. A pure-strategy Nash equilibrium exists. Secondly, in a cooperative game, there is no need to estimate the proportion of the harvested energy from each transmitter. Rather, the transmitters bargain over the unit-reward of the energy contribution. An approximation of the information rate is used in constructing the individual utility such that the problem of network utility maximization can be decomposed and the bargaining process can be implemented distributively. The bargaining solution gives a point of rates that is superior to the Nash equilibria and close to the Pareto front. Simulation results verify the algorithms that provide good communication performance while satisfying the RF energy-harvesting requirements.Comment: 13 pages, 13 figures. Submitted to IEEE Transactions on Green Communications and Networkin

A discussion of deuteron transverse charge densities

The deuteron transverse charge density $\rho_C(b)$ is the two-dimensional Fourier transform of its charge form factor in the impact space. We show that different parameterizations of the charge form factors provide different $\rho_C(b)$, in particular at the central value of impact parameter ($b=0$), although all the parameterizations can well reproduce the form factors in the region of small $Q^2$. In addition, we also check the explicit contributions from the different coordinate intervals of the deuteron wave function to its root-mean-square radius.Comment: 6 pages, 5 tables, 3 figure

Effect of Pauli principle on the deformed QRPA calculations and its consequence in the β\beta-decay calculations of deformed even-even nuclei

In this work, we take into consideration of Pauli Exclusion Principle(PEP) in the quasi-particle random phase approximation (QRPA) calculations for the deformed systems by replacing the traditional Quasi-Boson Approximation(QBA) with the renormalized one. With this new formalism, the parametrization of QRPA calculations has been changed and the collapse of QRPA solutions could be avoid for realistic $g_{pp}$ values. We further find that the necessity of renormalization parameter of particle-particle residual interaction $g_{pp}$ in QRPA calculations is due to the exclusion of PEP. So with the inclusion of PEP, we could easily extend the deformed QRPA calculations to the less explored region where lack of experimental data prevent effective parametrization of $g_{pp}$ for QRPA methods. With this theoretical improvement, we give predictions of weak decay rates for even-even isotopes in the rare earth region and the results are then compared with existing calculations.Comment: 8 Pages, 4 Figures, Accepted by PR

Bardeen-Cooper-Schrieffer formalism of superconductivity in carbon nanotubes

We develop the Bardeen-Cooper-Schrieffer (BCS) formalism for the superconductivity of carbon nanotubes. It is found that the superconducting transition temperature Tc of single-wall carbon nanotubes decreases exponentially with the increase of the tube diameter because the density of states near the Fermi energy is inversely proportional to the tube diameter. For the multi-wall carbon nanotubes, the Cooper paring hopping between layers enhances the superconducting correlation and increases the superconducting transition temperature, which is consistent with the experimental observation.Comment: 11 page

Deuteron electromagnetic form factors in transverse plane with a phenomenological Lagrangian approach

A phenomenological Lagrangian approach is employed to study the electromagnetic properties of deuteron. The deuteron is regarded as a loosely bound state of a proton and a neutron. The deuteron electromagnetic form factors are expressed in light-front representation in the transverse plane. The transverse charge density of the deuteron is discussed.Comment: 13 pages, 9 figures, submitted to Chinese Physics

Clarifying Trust in Social Internet of Things

A social approach can be exploited for the Internet of Things (IoT) to manage a large number of connected objects. These objects operate as autonomous agents to request and provide information and services to users. Establishing trustworthy relationships among the objects greatly improves the effectiveness of node interaction in the social IoT and helps nodes overcome perceptions of uncertainty and risk. However, there are limitations in the existing trust models. In this paper, a comprehensive model of trust is proposed that is tailored to the social IoT. The model includes ingredients such as trustor, trustee, goal, trustworthiness evaluation, decision, action, result, and context. Building on this trust model, we clarify the concept of trust in the social IoT in five aspects such as (1) mutuality of trustor and trustee, (2) inferential transfer of trust, (3) transitivity of trust, (4) trustworthiness update, and (5) trustworthiness affected by dynamic environment. With network connectivities that are from real-world social networks, a series of simulations are conducted to evaluate the performance of the social IoT operated with the proposed trust model. An experimental IoT network is used to further validate the proposed trust model.Comment: 14 pages, 16 figures. Submitted to IEEE Transactions on Knowledge and Data Engineerin

Energy Efficiency in Multiuser Transmission Over Parallel Frequency Channels

Energy efficiency is an important design criterion for wireless communications. When parallel frequency channels are used for multiuser transmission, the channel bandwidths and user power are adjusted to maximize the sum information rate with the bandwidth budget, the transmit power budget, and the user-specific rate requirements. The maximum sum rate is used in measuring the energy efficiency. With fixed or flexible bandwidths of the frequency channels, practical methods are developed to find the total transmit power with the unique optimal resource (bandwidth and power) allocation for maximum energy efficiency. This resource allocation ensures that, while each user's minimum rate requirement is satisfied, all the excess resource of the spectrum and transmit power is dedicated to the one user with the best channel quality. Simulation results validate the optimal solutions of total transmit power and resource allocation that support the energy-efficient multiuser transmission.Comment: 10 pages, 9 figure

Secure Location-Aided Routing Protocols With Wi-Fi Direct For Vehicular Ad Hoc Networks

Secure routing protocols are proposed for the vehicular ad hoc networks. The protocols integrate the security authentication process with the Location-Aided Routing (LAR) protocol to support Wi-Fi Direct communications between the vehicles. The methods are robust against various security threats. The security authentication process adopts a modified Diffie-Hellman key agreement protocol. The Diffie-Hellman protocol is used with a short authentication string (SAS)-based key agreement over Wi-Fi Direct out-of-band communication channels. It protects the communication from any man-in-the-middle security threats. In particular, the security process is integrated into two LAR routing schemes, i.e., the request-zone LAR scheme and the distance-based LAR scheme. We conduct extensive simulations with different network parameters such as the vehicular node density, the number of the malicious nodes, and the speed of the nodes. Simulation results show that the proposed routing protocols provide superior performance in secure data delivery and average total packet delay. Also, the secure distance-based LAR protocol outperforms the secure request-zone LAR protocol.Comment: 10 pages, 14 figure

Quantum Szilard engines with arbitrary spin

The quantum Szilard engine (QSZE) is a conceptual quantum engine for understanding the fundamental physics of quantum thermodynamics and information physics. We generalize the QSZE to an arbitrary spin case, i.e., a spin QSZE (SQSZE), and we systematically study the basic physical properties of both fermion and boson SQSZEs in a low-temperature approximation. We give the analytic formulation of the total work. For the fermion SQSZE, the work might be absorbed from the environment, and the change rate of the work with temperature exhibits periodicity and even-odd oscillation, which is a generalization of a spinless QSZE. It is interesting that the average absorbed work oscillates regularly and periodically in a large-number limit, which implies that the average absorbed work in a fermion SQSZE is neither an intensive quantity nor an extensive quantity. The phase diagrams of both fermion and boson SQSZEs give the SQSZE doing positive or negative work in the parameter space of the temperature and the particle number of the system, but they have different behaviors because the spin degrees of the fermion and the boson play different roles in their configuration states and corresponding statistical properties. The critical temperature of phase transition depends sensitively on the particle number. By using Landauer's erasure principle, we give the erasure work in a thermodynamic cycle, and we define an efficiency (we refer to it as information-work efficiency) to measure the engine's ability of utilizing information to extract work. We also give the conditions under which the maximum extracted work and highest information-work efficiencies for fermion and boson SQSZEs can be achieved.Comment: 24 pages, 11 figure

Multiscale analysis for convection dominated transport equations

In this paper, we perform a systematic multiscale analysis for convection dominated transport equations with a weak diffusion and a highly oscillatory velocity field. The paper primarily focuses on upscaling linear transport equations. But we also discuss briefly how to upscale two-phase miscible flows, in which case the concentration equation is coupled to the pressure equation in a nonlinear fashion. For the problem we consider here, the local Peclet number is of O(ε^(-m+1)) with m is an element of [2, infinity] being any integer, where ε characterizes the small scale in the heterogeneous media. Due to the presence of the nonlocal memory effect, upscaling a convection dominated transport equation is known to be very difficult. One of the key ideas in deriving a well-posed homogenized equation for the convection dominated transport equation is to introduce a projection operator which projects the fluctuation onto a suitable subspace. This projection operator corresponds to averaging along the streamlines of the flow. In the case of linear convection dominated transport equations, we prove the well-posedness of the homogenized equations and establish rigorous error estimates for our multiscale expansion