Experimentally validated structural vibration frequencies’ prediction from frictional temperature signatures using numerical simulation : a case of laced cantilever beam-like structures

This article pertains to the prediction of structural vibration frequencies from frictional temperature evolution through numerical simulation. To achieve this, a finite element analysis was carried on AISI 304 steel cantilever beam-like structures coupled with a lacing wire using the commercial software ABAQUS/CAE. The coupled temperature–displacement transient analysis simulated the frictional thermal generation. Furthermore, an experimental analysis was carried out with infrared cameras capturing the interfacial thermal images while the beams were subjected to forced excitation, thus validating the finite element analysis results. The analysed vibration frequencies using a MATLAB fast Fourier transform algorithm confirmed the validity of its prediction from the frictional temperature time domain waveform. This finding has a great significance to the mechanical and aerospace engineering communities for the effective structural health monitoring of dynamic structures online using infrared thermography, thus reducing the downtime and maintenance cost, leading to increased efficiency.Eskom Power Plant Engineering Institute (Republic of South Africa), University of Pretoria and Tshwane University of Technology.https://journals.sagepub.com/home/adehb2017Mechanical and Aeronautical Engineerin

Vibration characteristics measurement of beam-like structures using infrared thermography

Infrared thermography (IRT) has matured and is now widely accepted as a condition monitoring tool where temperature is measured in a non-contact way. Since the late 1970s, it has been extensively used in vibrothermography (Sonic IR) non-destructive technique for the evaluation of surface cracks through the observation of thermal imaging of the vibration-induced crack heat generation. However, it has not received research attention on prediction of structural vibration behaviour, hence; the concept to date is not understood. Therefore, this paper explores its ability to fill the existing knowledge gap. To achieve this, two cantilever beam-like structures couple with a friction rod subjected to a forced excitations while infrared cameras capturing the thermal images on the friction interfaces. The analysed frictional temperature evolution using the Matlab Fast Fourier Transform (FFT) algorithm and the use of the heat conduction equation in conjunction with a finite difference approach successfully identifies the structural vibration characteristics; with maximum error of 0.28% and 20.71% for frequencies and displacements, respectively. These findings are particularly useful in overcoming many limitations inherent in some of the current vibration measuring techniques applied in structural integrity management such as strain gauge failures due to fatigue.The authors greatly appreciate the support of Tshwane University of Technology, University of Pretoria and Eskom Power Plant Institute (South Africa) in funding this research.http:// www.elsevier.com/locate/infrared2017-11-30hb2017Mechanical and Aeronautical Engineerin

Seesaw mechanism, baryon asymmetry and neutrinoless double beta decay

A simplified but very instructive analysis of the seesaw mechanism is here performed. Assuming a nearly diagonal Dirac neutrino mass matrix, we study the forms of the Majorana mass matrix of right-handed neutrinos, which reproduce the effective mass matrix of left-handed neutrinos. As a further step, the important effect of a non diagonal Dirac neutrino mass matrix is explored. The corresponding implications for the baryogenesis via leptogenesis and for the neutrinoless double beta decay are reviewed. We propose two distinct models where the baryon asymmetry is enhanced.Comment: 21 pages, RevTex. Revise

Medicare Bundled Payment Policy on Anemia Care, Major Adverse Cardiovascular Events, and Mortality among Adults Undergoing Hemodialysis

Background and objectives In 2011, the Centers forMedicare & Medicaid Services implemented bundling of all services for patients receiving dialysis, including erythropoietin-stimulating agents use, and the Food and Drug Administration recommended conservative erythropoietin-stimulating agent dosing. Design, setting, participants, & measurements This retrospective cohort study investigated anemia care and clinical outcomes before and after the Centers for Medicare & Medicaid Services bundled payment and the revised Food and Drug Administration–recommended erythropoietin-stimulating agent labeling for Medicareinsured adults receiving hemodialysis using data from the United States Renal Data System from January 1, 2006 to December 31, 2016. Clinical outcomes included major adverse cardiovascular event (stroke, acute myocardial infarction, and all-cause mortality), cardiovascular mortality, and heart failure. Measurements were compared between prepolicy (2006–2010) and postpolicy (2012–2016) implementation using interrupted time series and Cox proportional hazards regression models. Results Of 481,564 patients, erythropoietin-stimulating agent use immediately decreased by 84.8 per 1000 persons (P11 g/dl decreased from 68% in January 2006 to 28% in December 2016, whereas those with hemoglobin >9 g/dl increased from 5% to 9%. Overall major adverse cardiovascular event (adjusted hazard ratio, 0.95; 95% confidence interval, 0.94 to 0.96), stroke (adjusted hazard ratio, 0.83; 95% confidence interval, 0.80 to 0.86), all-cause mortality (adjusted hazard ratio, 0.87; 95% confidence interval, 0.86 to 0.89), cardiovascular mortality (adjusted hazard ratio, 0.81; 95% confidence interval, 0.79 to 0.83), and heart failure (adjusted hazard ratio, 0.86; 95% confidence interval, 0.84 to 0.88) risks were lower. Acute myocardial infarction risk (adjusted hazard ratio, 1.04; 95% confidence interval, 1.01 to 1.06) was higher after policies changed. Conclusions The Medicare reimbursement policy and Food and Drug Administration–recommended erythropoietin-stimulating agent dosing changes were associated with lower erythropoietin-stimulating agent use and lower hemoglobin levels. These changes in anemia care were associated with lower risks of major adverse cardiovascular event, stroke, mortality, and heart failure but higher risk of acute myocardial infarction among adults receiving hemodialysis

An Extreme Solar Event of 20 January 2005: Properties of the Flare and the Origin of Energetic Particles

The extreme solar and SEP event of 20 January 2005 is analyzed from two perspectives. Firstly, we study features of the main phase of the flare, when the strongest emissions from microwaves up to 200 MeV gamma-rays were observed. Secondly, we relate our results to a long-standing controversy on the origin of SEPs arriving at Earth, i.e., acceleration in flares, or shocks ahead of CMEs. All emissions from microwaves up to 2.22 MeV line gamma-rays during the main flare phase originated within a compact structure located just above sunspot umbrae. A huge radio burst with a frequency maximum at 30 GHz was observed, indicating the presence of a large number of energetic electrons in strong magnetic fields. Thus, protons and electrons responsible for flare emissions during its main phase were accelerated within the magnetic field of the active region. The leading, impulsive parts of the GLE, and highest-energy gamma-rays identified with pi^0-decay emission, are similar and correspond in time. The origin of the pi^0-decay gamma-rays is argued to be the same as that of lower energy emissions. We estimate the sky-plane speed of the CME to be 2000-2600 km/s, i.e., high, but of the same order as preceding non-GLE-related CMEs from the same active region. Hence, the flare itself rather than the CME appears to determine the extreme nature of this event. We conclude that the acceleration, at least, to sub-relativistic energies, of electrons and protons, responsible for both the flare emissions and the leading spike of SEP/GLE by 07 UT, are likely to have occurred simultaneously within the flare region. We do not rule out a probable contribution from particles accelerated in the CME-driven shock for the leading GLE spike, which seemed to dominate later on.Comment: 34 pages, 14 Postscript figures. Solar Physics, accepted. A typo corrected. The original publication is available at http://www.springerlink.co