Search results for "Blocking"
showing 10 items of 164 documents
Performance of power control in inter-cell interference coordination for frequency reuse
2010
To mitigate inter-cell interference in 3G evolution systems, a novel inter-cell interference coordination scheme called soft fractional frequency reuse is proposed in this article, which enables to improve the data rate in cell-edge. On this basis, an inter-cell power control is presented for the inter-cell interference coordination, and the inter-cell balanced signal to interference plus noise ratio (SINR) among users is established for power allocation, which enables mitigation of inter-cell interference. Especially, the power control is based on a novel exponential kernel equation at higher convergence speed than the traditional arithmetic kernel equations. Numerical results show that th…
UDP flows in Cognitive Radios with Channel Aggregation and Fragmentation: A Test-bed Based Evaluation
2018
Channel aggregation (CA) and channel fragmentation (CF) have been studied extensively in cognitive radios (CRs) for many years. However, a test-bed evaluation for such techniques at flow level is still open. In this study, employing National Instruments devices, a test-bed is set up to evaluate the performance of UDP flows for CRs with CA and CF, considering the aspects of blocking, preemption, and throughput in probability. The measurements clearly show that there are performance improvements in applying CA and CF in CRs for UDP flows.
Dynamic Flow-Adaptive Spectrum Leasing with Channel Aggregation in Cognitive Radio Networks.
2020
Cognitive radio networks (CRNs), which allow secondary users (SUs) to dynamically access a network without affecting the primary users (PUs), have been widely regarded as an effective approach to mitigate the shortage of spectrum resources and the inefficiency of spectrum utilization. However, the SUs suffer from frequent spectrum handoffs and transmission limitations. In this paper, considering the quality of service (QoS) requirements of PUs and SUs, we propose a novel dynamic flow-adaptive spectrum leasing with channel aggregation. Specifically, we design an adaptive leasing algorithm, which adaptively adjusts the portion of leased channels based on the number of ongoing and buffered PU …
Spin transport in multilayer systems with fully epitaxial NiO thin films
2018
We report the generation and transport of thermal spin currents in fully epitaxial $\ensuremath{\gamma}\text{\ensuremath{-}}\mathrm{F}{\mathrm{e}}_{2}{\mathrm{O}}_{3}/\mathrm{NiO}(001)/\mathrm{Pt}$ and $\mathrm{F}{\mathrm{e}}_{3}{\mathrm{O}}_{4}/\mathrm{NiO}(001)/\mathrm{Pt}$ trilayers. A thermal gradient, perpendicular to the plane of the sample, generates a magnonic spin current in the ferrimagnetic maghemite $(\ensuremath{\gamma}\text{\ensuremath{-}}\mathrm{F}{\mathrm{e}}_{2}{\mathrm{O}}_{3})$ and magnetite $(\mathrm{F}{\mathrm{e}}_{3}{\mathrm{O}}_{4})$ thin films by means of the spin Seebeck effect. The spin current propagates across the epitaxial, antiferromagnetic insulating NiO layer…
Full angular dependence of the spin Hall and ordinary magnetoresistance in epitaxial antiferromagnetic NiO(001)/Pt thin films
2018
We report the observation of the three-dimensional angular dependence of the spin Hall magnetoresistance (SMR) in a bilayer of the epitaxial antiferromagnetic insulator NiO(001) and the heavy metal Pt, without any ferromagnetic element. The detected angular-dependent longitudinal and transverse magnetoresistances are measured by rotating the sample in magnetic fields up to 11 T, along three orthogonal planes (xy-, yz- and xz-rotation planes, where the z-axis is orthogonal to the sample plane). The total magnetoresistance has contributions arising from both the SMR and ordinary magnetoresistance. The onset of the SMR signal occurs between 1 and 3 T and no saturation is visible up to 11 T. Th…
Design of experiment approach applied to reducing and oxidizing tolerance of anode supported solid oxide fuel cell. Part I: Microstructure optimizati…
2011
The main drawback of Ni/YSZ anode supports for solid oxide fuel cell application is their low tolerance to reducing and oxidizing (RedOx) atmosphere changes, owing to the Ni/NiO volume variation. This work describes a structured approach based on design of experiments for optimizing the microstructure for RedOx stability enhancement. A full factorial hypercube design and the response surface methodology are applied with the variables and their variation range defined as: (1) NiO proportion (40-60 wt% of the ceramic powders), (2) pore-former proportion (0-30 wt% corresponding to 0-64 vol.%), (3) NiO particle size (0.5-8 mu m) and (4) 8YSZ particle size (0.6-9 mu m).
Structural modelling and mechanical tests supporting the design of the ATHENA X-IFU thermal filters and WFI optical blocking filter
2018
Copyright 2018 Society of Photo-Optical Instrumentation Engineers (SPIE). One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited. ATHENA is a Large high energy astrophysics space mission selected by ESA in the Cosmic Vision 2015-2025 Science Program. It will be equipped with two interchangeable focal plane detectors: the X-Ray Integral Field Unit (X-IFU) and the Wide Field Imager (WFI). Both detectors require x-ray transparent filters to fully exploit their sensitivity. In order to maximize the X-ray tra…
Baseline design of the thermal blocking filters for the X-IFU detector on board ATHENA
2014
ATHENA is an advanced X-ray observatory designed by a large European consortium to address the science theme "Hot and Energetic Universe" recently selected by ESA for L2 – the second Large-class mission within the Cosmic Vision science program (launch scheduled in 2028). One of the key instruments of the mission is the X-ray Integral Field Unit (X-IFU), an array of Transition Edge Sensor (TES) micro-calorimeters with high energy resolution (2.5 eV @ 6 keV) in the energy range 0.2÷12 keV, operating at the focal plane of a large effective area high angular resolution (5" HEW) grazing incidence X-ray telescope. The X-IFU operates at temperatures below 100 mK and thus requires a sophisticated c…
Influence of diamagnetic impurity on mid‐IR absorption in antiferromagnetic insulator NiO
2005
-1 was studied in polycrystalline Ni c Mg 1-c O solid solutions with c=0.99, 0.98, 0.97, 0.95, 0.90, 0.80, 0.70 and 0.60. The composition and temperature dependences of the absorption suggest that the band has magnetic origin re- lated to simultaneous excitation of two-magnons at the Brillouin-zone boundary and one phonon. -1 in polycrystalline NicMg1-cO solid solutions. Polycrystalline solid solutions NicMg1-cO (c=0.99, 0.98, 0.97, 0.95, 0.90, 0.80, 0.70 and 0.60) were prepared using ceramic technology from the appropriate amounts of aqueous solutions of Mg(NO3)2·6H2O and Ni(NO3)2·6H2O salts, which were mixed and slowly evaporated. The remaining dry 'flakes' were heated up to 500-600 oC to…
<title>Origin of visible photoluminescence in NiO and Ni<formula><inf><roman>c</roman></inf></formula>Mg<…
2003
A study of the visible photoluminescence in single-crystal NiO and NicMg1-cO (c = 0.99, 0.98 and 0.95) solid solutions is presented for the first time. Two wide luminescence bands, peaked at approximately 12000 cm-1 and approximately 18500 cm-1, were observed. The dependence of their intensity and position on the excitation energy, temperature, and composition were investigated. We attribute the origin of two photoluminescence bands to the impurity- or defect perturbed Ni2+ excitons.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.