Hybrid User Pairing for Spectral and Energy Efficiencies in Multiuser MISO-NOMA Networks with SWIPT

In this paper, we propose a novel hybrid user pairing (HUP) scheme in multiuser multiple-input single-output nonorthogonal multiple access networks with simultaneous wireless information and power transfer. In this system, two information users with distinct channel conditions are optimally paired while energy users perform energy harvesting (EH) under non-linearity of the EH circuits. We consider the problem of jointly optimizing user pairing and power allocation to maximize the overall spectral efficiency (SE) and energy efficiency (EE) subject to userspecific quality-of-service and harvested power requirements. A new paradigm for the EE-EH trade-off is then proposed to achieve a good balance of network power consumption. Such design problems are formulated as the maximization of nonconcave functions subject to the class of mixed-integer non-convex constraints, which are very challenging to solve optimally. To address these challenges, we first relax binary pairing variables to be continuous and transform the design problems into equivalent non-convex ones, but with more tractable forms. We then develop low-complexity iterative algorithms to improve the objectives and converge to a local optimum by means of the inner approximation framework. Simulation results show the convergence of proposed algorithms and the SE and EE improvements of the proposed HUP scheme over state-of-the-art designs. In addition, the effects of key parameters such as the number of antennas and dynamic power at the BS, target data rates, and energy threshold, on the system performance are evaluated to show the effectiveness of the proposed schemes in balancing resource utilization

Crack growth modelling: enriched continuum vs. discrete models

Failure in quasi-brittle materials usually appears in the form of narrow bands called fracture process zones, where all inelastic deformation takes place, while the surrounding bulk material outside those areas typically unloads elastically. This localised nature of failure is the main source of size effects in these materials, since the width of the fracture process zone is a material property that does not scale with the size of the material volume. An adequate description of localised failure and associated size effects requires both size and behaviour of the fracture process zone and neighbouring material to be properly taken into account. In this study, we present two alternative approaches for modelling localised failure and simulating fracture propagation using finite element methods. In the first approach, an embedded crack appears at a constitutive level by enriching the kinematics of constitutive models, while in the second one this is done at the finite element level using cohesive interface elements. The advantages and shortcomings of both are presented through one numerical example on the failure of fibre-reinforced composite materials

Chemerin receptor blockade improves vascular function in diabetic obese mice via redox-sensitive- and Akt-dependent pathways

Chemerin and its G protein-coupled receptor [chemerin receptor 23 (ChemR23)] have been associated with endothelial dysfunction, inflammation, and insulin resistance. However, the role of chemerin on insulin signaling in the vasculature is still unknown. We aimed to determine whether chemerin reduces vascular insulin signaling and whether there is interplay between chemerin/ChemR23, insulin resistance, and vascular complications associated with type 2 diabetes (T2D). Molecular and vascular mechanisms were probed in mesenteric arteries and cultured vascular smooth muscle cells (VSMCs) from C57BL/6J, nondiabetic lean db/m, and diabetic obese db/db mice as well as in human microvascular endothelial cells (HMECs). Chemerin decreased insulin-induced vasodilatation in C57BL/6J mice, an effect prevented by CCX832 (ChemR23 antagonist) treatment. In VSMCs, chemerin, via oxidative stress- and ChemR23-dependent mechanisms, decreased insulin-induced Akt phosphorylation, glucose transporter 4 translocation to the membrane, and glucose uptake. In HMECs, chemerin decreased insulin-activated nitric oxide signaling. AMP-activated protein kinase phosphorylation was reduced by chemerin in both HMECs and VSMCs. CCX832 treatment of db/db mice decreased body weight, insulin, and glucose levels as well as vascular oxidative stress. CCX832 also partially restored vascular insulin responses in db/db and high-fat diet-fed mice. Our novel in vivo findings highlight chemerin/ChemR23 as a promising therapeutic target to limit insulin resistance and vascular complications associated with obesity-related diabetes

Dendrons consisting of two phosphonate functions and three oligo(ethylene glycol) (OEG) chains grafted on a central henoxyethylcarbamoylphenoxy group were synthesized and investigated as Langmuir monolayers at the surface of water. The OEG chain in the para position was graftedwith a t-Bu end-group, a hydrocarbon chain, or a partially fluorinated chain. These dendrons are models of structurally related OEG dendrons that were found to significantly improve the stability of aqueous dispersions of iron oxide nanoparticles when grafted on their surface. Compressionisotherms showed that all OEG dendrons formed liquid-expanded Langmuir monolayers at large molecular areas. Further compression led to a transition ascribed to the solubilization of the OEG chains in the aqueous phase. Brewster angle microscopy (BAM) provided evidence that the dendrons fitted with hydrocarbon chains formed liquid-expanded monolayers throughout compression, whilst those fitted with fluorinated end-groups formed crystalline-like domains, even at large molecular areas. Dimyristoylphosphatidylcholine and dendron molecules were partially miscible in monolayers.The deviations to idealitywere larger for the dendrons fitted with a fluorocarbon end-group chain than for those fitted with a hydrocarbon chain. Brewster angle microscopy and atomic force microscopy supported the view that the dendrons were ejected from the phospholipid monolayer during the OEG conformational transition and formed crystalline domains on the surface of the monolayer.

International audienc

Asymptotic solution of the high order partial differential equation

In the present paper, the authors have constructed an asymptotic solution of the high order equation with partial derivatives by means of the asymptotic method for the high order systems. The improved first approximation of the solution of the given boundary value problem is determine

Short-Packet Communications in Multi-Hop WPINs: Performance Analysis and Deep Learning Design

In this paper, we study short-packet communications (SPCs) in multi-hop wireless-powered Internet-of-Things networks (WPINs), where IoT devices transmit short packets to multiple destination nodes by harvesting energy from multiple power beacons. To improve system block error rate (BLER) and throughput, we propose a best relay-best user (bR-bU) selection scheme with an accumulated energy harvesting mechanism. Closed-form expressions for the BLER and throughput of the proposed scheme over Rayleigh fading channels are derived and the respective asymptotic analysis is also carried out. To support real-time settings, we design a deep neural network (DNN) framework to predict the system throughput under different channel settings. Numerical results demonstrate that the proposed bR-bU selection scheme outperforms several baseline ones in terms of the BLER and throughput, showing to be an efficient strategy for multi-hop SPCs. The resulting DNN can estimate accurately the throughput with low execution time. The effects of message size on reliability and latency are also evaluated and discussed

Population density, water supply, and the risk of dengue fever in Vietnam: cohort study and spatial analysis.

BACKGROUND: Aedes aegypti, the major vector of dengue viruses, often breeds in water storage containers used by households without tap water supply, and occurs in high numbers even in dense urban areas. We analysed the interaction between human population density and lack of tap water as a cause of dengue fever outbreaks with the aim of identifying geographic areas at highest risk. METHODS AND FINDINGS: We conducted an individual-level cohort study in a population of 75,000 geo-referenced households in Vietnam over the course of two epidemics, on the basis of dengue hospital admissions (n = 3,013). We applied space-time scan statistics and mathematical models to confirm the findings. We identified a surprisingly narrow range of critical human population densities between around 3,000 to 7,000 people/km² prone to dengue outbreaks. In the study area, this population density was typical of villages and some peri-urban areas. Scan statistics showed that areas with a high population density or adequate water supply did not experience severe outbreaks. The risk of dengue was higher in rural than in urban areas, largely explained by lack of piped water supply, and in human population densities more often falling within the critical range. Mathematical modeling suggests that simple assumptions regarding area-level vector/host ratios may explain the occurrence of outbreaks. CONCLUSIONS: Rural areas may contribute at least as much to the dissemination of dengue fever as cities. Improving water supply and vector control in areas with a human population density critical for dengue transmission could increase the efficiency of control efforts. Please see later in the article for the Editors' Summary

Requirements for Implementing Mappings Adaptation Systems

International audienceOntologies, or more generally speaking, Knowledge Organization Systems (KOS) have been developed to support the correct interpretation of shared data in collaborative applications. The quantity and the heterogeneity of domain knowledge often require several KOS to describe their content. In order to assure unambiguous interpretation, overlapped concepts of different, but domain-related KOS are semantically connected via mappings. However, in various domains, KOS periodically evolve creating the necessity of reviewing the validity of associated mappings. The size of KOS remains a barrier for a manual review of mappings, and rather requires the support of (semi-) automatic solutions. This article describes our experiences in understanding how KOS evolution affects mappings. We present our lessons learned from various empirical experiments, and we derive primary elements and requirements for improving the automation of mapping maintenance

The seesaw mechanism at TeV scale in the 3-3-1 model with right-handed neutrinos

We implement the seesaw mechanism in the 3-3-1 model with right-handed neutrinos. This is accomplished by the introduction of a scalar sextet into the model and the spontaneous violation of the lepton number. We identify the Majoron as a singlet under $SU_L(2)\otimes U_Y(1)$ symmetry, which makes it safe under the current bounds imposed by electroweak data. The main result of this work is that the seesaw mechanism works already at TeV scale with the outcome that the right-handed neutrino masses lie in the electroweak scale, in the range from MeV to tens of GeV. This window provides a great opportunity to test their appearance at current detectors, though when we contrast our results with some previous analysis concerning detection sensitivity at LHC, we conclude that further work is needed in order to validate this search.Comment: about 13 pages, no figure

Seatbelt use and risk of major injuries sustained by vehicle occupants during motor-vehicle crashes: A systematic review and meta-analysis of cohort studies

BackgroundIn 2004, a World Health Report on road safety called for enforcement of measures such as seatbelt use, effective at minimizing morbidity and mortality caused by road traffic accidents. However, injuries caused by seatbelt use have also been described. Over a decade after publication of the World Health Report on road safety, this study sought to investigate the relationship between seatbelt use and major injuries in belted compared to unbelted passengers.MethodsCohort studies published in English language from 2005 to 2018 were retrieved from seven databases. Critical appraisal of studies was carried out using the Scottish Intercollegiate Guidelines Network (SIGN) checklist. Pooled risk of major injuries was assessed using the random effects meta-analytic model. Heterogeneity was quantified using I-squared and Tau-squared statistics. Funnel plots and Egger's test were used to investigate publication bias. This review is registered in PROSPERO (CRD42015020309).ResultsEleven studies, all carried out in developed countries were included. Overall, the risk of any major injury was significantly lower in belted passengers compared to unbelted passengers (RR 0.47; 95%CI, 0.29 to 0.80; I-2=99.7; P=0.000). When analysed by crash types, belt use significantly reduced the risk of any injury (RR 0.35; 95%CI, 0.24 to 0.52). Seatbelt use reduces the risk of facial injuries (RR=0.56, 95% CI=0.37 to 0.84), abdominal injuries (RR=0.87; 95% CI=0.78 to 0.98) and, spinal injuries (RR=0.56, 95% CI=0.37 to 0.84). However, we found no statistically significant difference in risk of head injuries (RR=0.49; 95% CI=0.22 to 1.08), neck injuries (RR=0.69: 95%CI 0.07 to 6.44), thoracic injuries (RR 0.96, 95%CI, 0.74 to 1.24), upper limb injuries (RR=1.05, 95%CI 0.83 to 1.34) and lower limb injuries (RR=0.77, 95%CI 0.58 to 1.04) between belted and non-belted passengers.ConclusionIn sum, the risk of most major road traffic injuries is lower in seatbelt users. Findings were inconclusive regarding seatbelt use and susceptibility to thoracic, head and neck injuries during road traffic accidents. Awareness should be raised about the dangers of inadequate seatbelt use. Future research should aim to assess the effects of seatbelt use on major injuries by crash type