Inelastic Displacement Ratios for Evaluation of Degrading Peak – Oriented SDOF Systems

Estimation of the inelastic displacement demand (IDD) is an important part of the performance-based design. Coefficient method is one of the methods for the estimation of IDD and in this method, IDD is determined by multiplying elastic displacement demand with inelastic displacement ratio (CR ). Previous researches showed that structures deteriorate and also exhibit dynamic instability under severe earthquakes and these behaviors should be considered in the estimation of CR to estimate a reliable IDD. In this study, CR of the non-degrading bilinear hysteretic model and the degrading peak-oriented hysteretic model with collapse potential were determined and effects of degradation on IDD were investigated. Nonlinear time history analysis of SDOF systems were performed using considered hysteretic models. Furthermore a new equation is proposed for the mean CR of degrading SDOF systems. Also, effect of local site conditions and post-yield stiffness on the mean CR of degrading SDOF systems were investigated

Objective sputum colour assessment and clinical outcomes in bronchiectasis: data from the European Bronchiectasis Registry (EMBARC)

Background A validated 4-point sputum colour chart can be used to objectively evaluate the levels of airway inflammation in bronchiectasis patients. In the European Bronchiectasis Registry (EMBARC), we tested whether sputum colour would be associated with disease severity and clinical outcomes. Methods We used a prospective, observational registry of adults with bronchiectasis conducted in 31 countries. Patients who did not produce spontaneous sputum were excluded from the analysis. The Murray sputum colour chart was used at baseline and at follow-up visits. Key outcomes were frequency of exacerbations, hospitalisations for severe exacerbations and mortality during up to 5-year follow-up. Results 13 484 patients were included in the analysis. More purulent sputum was associated with lower forced expiratory volume in 1 s (FEV 1), worse quality of life, greater bacterial infection and a higher bronchiectasis severity index. Sputum colour was strongly associated with the risk of future exacerbations during follow-up. Compared to patients with mucoid sputum (reference group), patients with mucopurulent sputum experienced significantly more exacerbations (incident rate ratio (IRR) 1.29, 95% CI 1.22–1.38; p&lt;0.0001), while the rates were even higher for patients with purulent (IRR 1.55, 95% CI 1.44–1.67; p&lt;0.0001) and severely purulent sputum (IRR 1.91, 95% CI 1.52–2.39; p&lt;0.0001). Hospitalisations for severe exacerbations were also associated with increasing sputum colour with rate ratios, compared to patients with mucoid sputum, of 1.41 (95% CI 1.29–1.56; p&lt;0.0001), 1.98 (95% CI 1.77–2.21; p&lt;0.0001) and 3.05 (95% CI 2.25–4.14; p&lt;0.0001) for mucopurulent, purulent and severely purulent sputum, respectively. Mortality was significantly increased with increasing sputum purulence, hazard ratio 1.12 (95% CI 1.01–1.24; p=0.027), for each increment in sputum purulence. Conclusion Sputum colour is a simple marker of disease severity and future risk of exacerbations, severe exacerbations and mortality in patients with bronchiectasis.</p

Geographic variation in the aetiology, epidemiology and microbiology of bronchiectasis

Bronchiectasis is a disease associated with chronic progressive and irreversible dilatation of the bronchi and is characterised by chronic infection and associated inflammation. The prevalence of bronchiectasis is age-related and there is some geographical variation in incidence, prevalence and clinical features. Most bronchiectasis is reported to be idiopathic however post-infectious aetiologies dominate across Asia especially secondary to tuberculosis. Most focus to date has been on the study of airway bacteria, both as colonisers and causes of exacerbations. Modern molecular technologies including next generation sequencing (NGS) have become invaluable tools to identify microorganisms directly from sputum and which are difficult to culture using traditional agar based methods. These have provided important insight into our understanding of emerging pathogens in the airways of people with bronchiectasis and the geographical differences that occur. The contribution of the lung microbiome, its ethnic variation, and subsequent roles in disease progression and response to therapy across geographic regions warrant further investigation. This review summarises the known geographical differences in the aetiology, epidemiology and microbiology of bronchiectasis. Further, we highlight the opportunities offered by emerging molecular technologies such as -omics to further dissect out important ethnic differences in the prognosis and management of bronchiectasis.NMRC (Natl Medical Research Council, S’pore)MOH (Min. of Health, S’pore)Published versio

Dimming self-oscillating ballast by variable inductor

A simple new dimming technique for self-oscillating electronic ballasts based on a variable inductance is introduced. The variable inductor is controlled by DC current. The goal is to keep the resonant condition during dimming without utilising any IC or complex control circuits. Dimming is successfully accomplished and theoretical and experimental results are presented on self-oscillated cur-rent fed push pull electronic ballast.C1 Univ Pamukkale, Dept Elect Engn, Kinikli, Denizli, Turkey.Univ Pamukkale, Dept Tech Educ, Kinikli, Denizli, Turkey

CURRENT FED SELF OSCILLATING ELECTRONIC BALLAST DESIGN WITH PUSH PULL

Electronic ballasts are commonly used due to several advantages; among electronic ballasts, self oscillating electronic ballasts are not only simple and cheap but also have high efficiency because of zero voltage switching technique. Current and voltage fed topologies are commonly used in electronic ballasts. When both topologies are compared, current fed has better start up transient response. In this study, current fed push pull inverter circuit is designed for three 36W T8 fluorescent lamps. In the design, push pull transformer is wounded on a partition bobbin. Although it has the advantages of easy and reliable production for industrial automation and lowering the cost of the circuit, the coupling between the coils is considerably weak. Because of this, the weak coupling is taken into account in the design. The design has agreement with experimental and simulation results

technique

Dimming can be accomplished commonly by switching frequency and pulse density modulation techniques and a variable inductor. In this study, a variable power density modulation (VPDM) control technique is proposed for dimming applications. A fluorescent lamp is operated in several states to meet the desired lamp power in a modulation period. The proposed technique has the same advantages of magnetic dimming topologies have. In addition, a unique and flexible control technique can be achieved. A prototype dimmable electronic ballast is built and experiments related to it have been conducted. As a result, a 36WT8 fluorescent lamp can be driven for a desired lamp power from several alternatives without modulating the switching frequency

Conventional and soft-computing based MPPT methods comparisons in direct and indirect modes for single stage PV systems

Improving power efficiency for a Photovoltaic (PV) system becomes important issue for researchers. To achieve maximum power extraction from PV panels, different kinds of Maximum Power Point Tracking (MPPT) methods have been investigating in the literature. In all techniques, direct and indirect mode approaches can be implemented. Based on the physical application of the PV system under different condition, the efficiency and convergence speed become important. In this paper, a grid connected simple single stage PV system by using different MPPT methods in direct and indirect modes has been analysed to find out the best mode and technique for a specific PV system application. Three of the most preferred MPPT algorithms: the perturb & observe (P&O), incremental conductance (Inc. Cond.) and fuzzy logic control (FLC) have been performed in MATLAB Simulink and compared their performance in direct and indirect modes in terms of convergence speed and tracking accuracy by the proposed single stage PV system. The results show that direct mode MPPTs have better tracking accuracy but less convergence speed than indirect MPPTs. Therefore, indirect mode MPPTs present better performance for the rapid atmospheric changing applications. Additionally, FLC based MPPT exhibits almost best tracking performance for direct and indirect modes. © 2018 Kauno Technologijos Universitetas. All rights reserved

A comprehensive overview of maximum power extraction methods for PV systems

WOS: 000407185900009The power generated by photovoltaic (PV) system depends on environment irradiance and temperature parameters. Hence, PV panels have nonlinear characteristics. In uniform condition, there is only one maxima point called maximum power point (MPP) where the PV system operates in maximum efficiency. However, in non-uniform condition such as partial shading effects, the PV system presents multiple maxima points on the correspondence P-V curve due to bypass diodes which makes more difficult to estimate global MPP. That is why it makes maximum power point tracking (MPPT) more important for PV systems to operate in maximum efficiency. In the literature, various types of MPPT technique and alternative solutions are used to detect true global MPP point among the other local MPPs. In addition, different PV array topologies, architectures and configurations are proposed to remove local maxima on the P-V curve. In this paper, most popular and used MPPT techniques, PV array configurations, system architectures and circuit topologies are discussed. In this context, this paper provides an overview of the operating principles discusses advantages and disadvantages and makes a general comparison between different solutions of each method