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Sensitivity analysis on the microscale combustion calorimeter for polyurethane foam using a full factorial design methodology

A sensitivity analysis on test outcomes from the microscale combustion calorimeter was performed using flexible polyurethane foam as the sample material. Three input factors were investigated: sample preparation, heating rate and pyrolysis chamber atmosphere. The experiments were setup according to the principles of design of experiments and a full factorial design was implemented. In total, 39 ex

Issues in child and adolescent inpatient assessment and evaluation after discharge : Protocol for app development and a randomized controlled trial

Background: New methods are needed for collecting data of in- and outpatients and for improving outpatient compliance after discharge. Mobile technologies, such as smartphone apps, have shown promising results, (eg, helping unwell people by offering support and resources). Screening for the condition, including comorbidities, is a vital part of psychiatric care. Comorbid conditions, especially in

ERS technical standard on bronchial challenge testing : pathophysiology and methodology of indirect airway challenge testing

Recently, this international task force reported the general considerations for bronchial challenge testing and the performance of the methacholine challenge test, a "direct" airway challenge test. Here, the task force provides an updated description of the pathophysiology and the methods to conduct indirect challenge tests. Because indirect challenge tests trigger airway narrowing through the act

Prevalence of amyloid-β pathology in distinct variants of primary progressive aphasia

OBJECTIVE: To estimate the prevalence of amyloid positivity, defined by positron emission tomography (PET)/cerebrospinal fluid (CSF) biomarkers and/or neuropathological examination, in primary progressive aphasia (PPA) variants. METHODS: We conducted a meta-analysis with individual participant data from 1,251 patients diagnosed with PPA (including logopenic [lvPPA, n = 443], nonfluent [nfvPPA, n =

Massive MIMO with a Generalized Channel Model: Fundamental Aspects

Massive multiple-input multiple-output (MIMO) is becoming a mature technology, and has been approved for standardization in the 5G ecosystem. Although there is a large body of papers on the theoretical analysis of massive MIMO, the majority of relevant work assumes the simplified, yet overly idealistic, Kronecker-type model for spatial correlation. Motivated by the deficiencies of the Kronecker mo

Aggressive RF Circuit Reduction Techniques in Millimeter Wave Cellular Systems

In this paper, we introduce a novel hybrid multiuser multiple-input multiple-output (MU-MIMO) architecture, with an emphasis on aggressive millimeter-wave (mmWave) hardware reduction methods, omitting the beam selection stage. We propose a simplification in a 28 GHz Rotman lens, where the number of beam-ports are reduced relative to the array ports resulting in the removal of a bank of RF switches

Massive MIMO for Ray-Based Channels

Favorable propagation (FP) and channel hardening are desired properties in massive multiple-input and multiple-output (MIMO) systems, where nearly optimal performance is achieved with linear processing techniques, such as maximal-ratio combining. To date, these properties have primarily been analyzed for statistical channel models, or ray-based models with very specific angular parameters and dist

Multi-User Processing for Ray-Based Channels

The performance of linear multi-user multiple-input multiple-output (MU-MIMO) systems has been extensively studied for classical statistical channel models. In contrast, there is little analysis for ray-based models, which are physically motivated, feature prominently in standards and have been experimentally validated. Thus, we present a novel analysis framework for zero forcing (ZF) and maximal

Performance of a 28 GHz Two-Stage Rotman Lens Beamformer for Millimeter Wave Cellular Systems

Phase shifter-based hybrid beamforming has received a lot of attention at millimeter-wave frequencies for cellular communications. Nevertheless, the implementation complexity of such beamformers is rather high due to the complexities involved in designing and fabricating the required radio-frequency (RF) circuits. In contrast, lens-based RF beamformers significantly reduce the implementation compl

Analytical Framework of Hybrid Beamforming in Multi-Cell Millimeter-Wave Systems

Multi-cell wireless systems usually encounter both intra-cell and inter-cell interference, which can be mitigated via coordinated multipoint (CoMP) transmission. Previous works on multi-cell analysis in the microwave band generally consider fully digital beamforming, requiring a complete radio-frequency chain behind each antenna. This is practically infeasible for millimeter-wave (mmWave) systems

On the Impact of Spillover Losses in 28 GHz Rotman Lens Arrays for 5G Applications

This work demonstrates the sensitivity of lens antenna arrays operating at millimeter-wave (mmWave) frequencies. Considering a Rotman lens array in receive mode, our investigation focuses on its most imperative defect: aberration of electromagnetic (EM) energy. Aberration leads to spillover of electric fields to neighboring ports, reducing the lens' ability to focus the EM energy to a desired port

Does Massive MIMO Fail in Ricean Channels?

Massive multiple-input multiple-output (MIMO) is now making its way to the standardization exercise of future 5G networks. Yet, there are still fundamental questions pertaining to the robustness of massive MIMO against physically detrimental propagation conditions. On these grounds, we identify scenarios under which massive MIMO can potentially fail in Ricean channels, and characterize them physic

Impact of RF Processing and Switching Errors in Lens-Based Massive MIMO Systems

Lens–based massive multiple–input multiple–output (MIMO) systems have considerable potential to reduce signal processing cost at millimeter–wave frequencies. As a result, they are able to lower the effective channel dimension via beam selection, realized with a network of radio–frequency (RF) switches. However, lens arrays suffer from the inherent quantization of the beamspace, as well as errors d

Developing Platform Economies : A European Policy Landscape

What is a digital platform economy and what are its key policy implications? This report on Developing Platform Economies collects four chapters from researchers in the fields of economy, media and law to define, scrutinize and draw empirically based policy-recommendations for a European context, particularly in comparison to the US.What is a digital platform economy and what are its key policy implications? This report on Developing Platform Economies collects four chapters from researchers in the fields of economy, media and law to define, scrutinize and draw empirically based policy-recommendations for a European context, particularly in comparison to the US.

Search for charged Higgs bosons decaying into top and bottom quarks at √s=13 TeV with the ATLAS detector

A search for charged Higgs bosons heavier than the top quark and decaying via H± → tb is presented. The data analysed corresponds to 36.1 fb−1 of pp collisions at s=13 TeV and was recorded with the ATLAS detector at the LHC in 2015 and 2016. The production of a charged Higgs boson in association with a top quark and a bottom quark, pp → tbH±, is explored in the mass range from mH± = 200 to 2000 Ge