Rate analysis of ZF receiver for uplink cell-free massive MIMO systems with D2D communications

This paper proposes a transmission structure of zero forcing (ZF) receiver for uplink cell-free massive multiple-input multiple-output (MIMO) systems with device-to-device (D2D) communications, followed by a rate analysis. We assumed that D2D users (DUEs) can utilize orthogonal radio resources to improve the efficiency of the scarce utilization or repurpose the time–frequency-spectrum resources currently used by the cell-free users (CFUEs). Assuming that the imperfect channel state information (CSI) is realizable, after that, the use-and-forget bounding technique is then used to respectively obtain the closed-form expressions of the CFUEs and DUEs, which provide the lower bounds on the ergodic approximate realizable rate of both communication links. First, we calculate the minimum-mean-square error (MMSE) estimation for all channels. Then, the derived results of the achievable uplink sum rate provide us with a tool that enables us to explain how some important parameters, such as the number of access points (APs)/CFUEs, each AP/CFUE/antenna, and the density of DUEs, affect system performance, highlighting the significance of cooperation between cell-free massive MIMO and D2D communication.     

A note on generalized nonlinear diagonal dominance

In this paper, an open problem, proposed by A. Frommer, about nonlinear generalized diagonal dominance, is solved on some weak restriction, a counterexample is presented if such a restriction is omitted, and some new properties of nonlinear generalized diagonally dominant functions are investigated.     

Simulations of flows and water depth in a dendritic river system

This paper presents the development of a channel hydrodynamic model for simulating the behaviour of flows and water depths in a river network that may consist of any number of joined and branched rivers/streams, including both tidal and non-tidal rivers. The model employs a numerical method—an integrated compartment method (ICM). The method greatly facilitates the set-up of algebraic equations for the discrete field approximating the corresponding continuous field. Most of the possible boundary conditions that may be anticipated in real-world problems are considered. These include junctions, prescribed flow, prescribed water depth (or cross-sectional area), and rating curve boundaries. The use of ICM makes the implementation of these four types of boundary conditions relatively easy. The model is applied to two case studies: first to a single river and then to a network of five river branches in a watershed. Results indicate that the model can simulate the behaviour of the hydrodynamic variables that are required to compute chemical transport in a river-stream network.     

Uncovering Organizational Hierarchies

This paper adapts a procedure, canonical analysis of asymmetry,originally defined by Gower (1977) to the analysis of hierarchicalproperties in organizational structures. Its application is demonstratedusing two available data sets, Freeman and Freeman's (1980) data on computercommunication and Krackhardt's (1987) data on advice-giving and getting inan organization.     

Collective firing regularity of a scale-free Hodgkin–Huxley neuronal network in response to a subthreshold signal

We consider a scale-free network of stochastic HH neurons driven by a subthreshold periodic stimulus and investigate how the collective spiking regularity or the collective temporal coherence changes with the stimulus frequency, the intrinsic noise (or the cell size), the network average degree and the coupling strength. We show that the best temporal coherence is obtained for a certain level of the intrinsic noise when the frequencies of the external stimulus and the subthreshold oscillations of the network elements match. We also find that the collective regularity exhibits a resonance-like behavior depending on both the coupling strength and the network average degree at the optimal values of the stimulus frequency and the cell size, indicating that the best temporal coherence also requires an optimal coupling strength and an optimal average degree of the connectivity.     

Synthesis and Structure of a Novel Polyoxomolybdate Lanthanide Complex: [Er2(H2O)14Cr(OH)6Mo6O18][Cr(OH)6Mo6O18]?·?14H2O

Abstract  A novel polyoxometalate compound consisting of Anderson-type anions and trivalent lanthanide cations, [Er₂(H₂O)₁₄Cr(OH)₆Mo₆O₁₈][Cr(OH)₆Mo₆O₁₈]·14H₂O (1), has been synthesized in aqueous solution and characterized by single crystal X-ray diffraction, elemental analyses, IR spectrum and TG analyses. Single crystal X-ray diffraction reveals that compound 1 crystallizes in the triclinic space group P-1 with a = 11.046 (5) ?, b = 11.653 (5) ?, c = 13.935 (5) ?, α = 75.006 (5)°, β = 84.497(5)°, γ = 89.515(5)°. The bulk ions of compound 1 in the cell unit exhibit orthorhombic C-centered packing mode, the eight [Cr(2)(OH)₆Mo₆O₁₈]³⁻ anions occupy the eight corners and the two [Er₂(H₂O)₁₄Cr(OH)₆Mo₆O₁₈]³⁺ cations occupy the centres of two opposite faces, whereas anions and cations are linked together via hydrogen bonding interactions tightly forming a three-dimensional supramolecular architecture, which contains one-dimensional channels occupied by free water molecules. Index Abstract  The bulk ions of compound 1 in the cell unit exhibit orthorhombic C-centered packing mode, the eight [Cr(2)(OH)₆Mo₆O₁₈]³⁻ anions occupy the eight corners and the two [Er₂(H₂O)₁₄Cr(OH)₆Mo₆O₁₈]³⁺ cations occupy the centres of two opposite faces, whereas anions and cations are linked together via hydrogen bonding interactions tightly forming a three-dimensional supramolecular architecture, which contains one-dimensional channels occupied by free water molecules. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Laterality index in functional MRI: methodological issues

In functional magnetic resonance imaging (fMRI), hemispheric dominance is generally indicated by a measure called the laterality index (LI). The assessment of a meaningful LI measure depends on several methodological factors that should be taken into account when interpreting LI values or comparing between subjects. Principally, these include the nature of the quantification of left and right hemispheres contributions, localisation of volumes of interest within each hemisphere, dependency on statistical threshold, thresholding LI values, choice of activation and baseline conditions and reproducibility of LI values. This review discusses such methodological factors and the different approaches that have been suggested to deal with them. Although these factors are common to a range of fMRI domains, they are discussed here in the context of fMRI of the language system.     

Résolution des équations de dispersion–diffusion en présence de forts gradientsResolution of advection–diffusion equation in presence of sharp gradient

In order to resolve the convection terms in the simulation of coastal flows, we propose a numerical method based on the Total Variation Diminishing scheme completed with the Artificial Compression Method to reduce the artificial diffusion and to sharpen the tracer profile in strong gradient regions. This method was applied successfully at discontinuous regions, but out of these regions a limitation of its application is necessary. An application is made to estimate the width of the fresh water band in the Eastern English Channel. To cite this article: C. Sart et al., C. R. Mecanique 330 (2002) 159–165.     

UMFSK水声通信技术研究

在MFSK基础上,本文提出了UMFSK信道编码方法。采用窄带调频和跳频调制技术,故在一定程度上抑制了由多途效应引起的码内/码间干扰;提出了基于UMFSK的实时信道标校技术,可对信道进行稳键均衡,抗信道多途引起的码内干扰。进行了湖试,取得了试验数据并进行了数据分析。分析表明：UMFSK可抑制码元相消干涉引起的码内干扰,其效果随码元调频带宽的增大而变好;信道标校技术可对信道进行稳键均衡,并由于结构简单,可做到实时实现。基于UMFSK的误码率为10^-3（通信带宽2kHz,速率100-150bps)。