12 research outputs found
Bearing failure prediction using Wigner-Ville distribution, modified Poincare mapping and fast Fourier transform
No full textThis study outlines the experimental investigation methods of condition monitoring to predict bearing failures using the experimental vibration signatures. The purpose of condition monitoring is to maximize the machine availability and utility of the machine components. Bearings being one of the most common component in any rotating machinery, it is vital to study the health of the bearing and can predict bearing failure, its location and severity. This prevents machine downtime, monetary loss and unfortunate accidents. A test rig was fabricated to get the vibration signatures of bearings. Prediction of bearing failure relies on the presence of the bearing characteristic frequencies – inner race frequency, outer race frequency, ball pass frequency and fundamental train frequency – and its harmonics in the vibration signal acquired. These frequencies are present in the vibration signature due to the interaction of surfaces of different bearing components that have defects in them. Both time and frequency domain numerical signature analysis were performed on the vibration signatures acquired. Simple frequency domain method like Fast Fourier Transform (FFT), chaotic vibration method like modified Poincare mapping and time-frequency domain Wigner-Ville distribution (WVD) were used in detecting bearing failure. Using the FFT analysis method, it is hard to predict the failures, hence better signal processing methods like modified Poincare mapping and WVD are used. Also, it is observed that the chaotic vibration signatures found in the lower-order mechanical systems like bearings. With the chaotic analysis methods like, Poincare Mapping and Wigner-Ville Distribution, the location and the severity of the bearing failure can be predicted
Development of an Experimental Model for a Magnetorheological Damper Using Artificial Neural Networks (Levenberg-Marquardt Algorithm)
No full textModeling of a magneto-rheological (MR) damper using genetic programming
No full textThis paper is based on the experimental study for design and control of vibrations in automotive vehicles. The objective of this paper is to develop a model for the highly nonlinear Magneto-Rheological (MR) damper to maximize passenger comfort in an automotive vehicle. The behavior of the MR damper is studied under different loading conditions and current values in the system. The input and output parameters of the system are used as a training data to develop a suitable model using Genetic Algorithm. To generate the training data, a test rig similar to a quarter car model was fabricated to load the MR damper with a mechanical shaker to excite it externally. With the help of the test rig the input and output parameter data points are acquired by measuring the acceleration and force of the system at different points with the help of an impedance head and accelerometers. The model is validated by measuring the error for the testing and validation data points. The output of the model is the optimum current that is supplied to the MR Damper, using a controller, to increase the passenger comfort by minimizing the amplitude of vibrations transmitted to the passenger. Besides using this model for cars, bikes and other automotive vehicles it can also be modified by re-training the algorithm and used for civil structures to make them earthquake resistant.Published versio
Interfacial charge transfer in g-C3N4/FeVO4/AgBr nanocomposite for efficient photodegradation of tetracycline antibiotic and Victoria blue dye
No full textThe study presents the fabrication and superior photoactivity of a ternary g-C3N4/FeVO4/AgBr heterojunction nanocomposite, synthesized via a chemical precipitation method for effective degradation of tetracycline (TC) and Victoria Blue (VB) dye under light illumination. The morphology and the crystal size of the synthesized nanocomposite were characterized by using FESEM and XRD and the calculated grain size (100.39 nm) is larger than the crystal size (48.14 nm) indicating strong interparticle bonding. The heterojunction design leverages dual S-scheme interfacial charge transfer, reducing electron-hole recombination as confirmed by optoelectronic and electrochemical techniques. The composite demonstrated superior performance, achieving 82.15% degradation of TC and 97.25% degradation of VB. The study highlights density functional theory (DFT) simulations and MottSchottky (MS) analysis, providing insight into the electronic structure, distribution of charge, and band alignments of the g-C3N4/FeVO4/AgBr nanocomposite. Electron spin resonance and radical scavenging experiments revealed holes and superoxide radicals as the primary species driving the degradation process. Furthermore, LCMS analysis provided insights into the degradation pathways, confirming the conversion of TC and VB into nontoxic byproducts. The photocatalytic stability was confirmed through five consecutive cycles with minimal disruption in both performance and morphology, demonstrating its potential for wastewater treatment applications. Consequently, this study illustrates how the collaborative interplay of dual S-scheme charge migration and silver plasmonic effects enhances the efficiency of the g-C3N4/FeVO4/AgBr nanocomposite, offering a novel and highly effective solution for the degradation of complex pollutants in environmental remediation.King Saud University, Riyadh, Saudi Arabia [RSP2025R6]The author (T. A.) thanks the Researchers Supporting Project number (RSP2025R6) , King Saud University, Riyadh, Saudi Arabia
Fabrication of a dual Z-scheme Ag3PO4/g-C3N4/Bi2MoO6 ternary nanocomposite for effective degradation of methylene blue dye
No full textMethylene blue is a recognized carcinogen with detrimental effects on both people and marine life. Henceforth, in this study, the photocatalytic activity of Ag3PO4/g-C3N4/Bi2MoO6 (AP/GCN/BMO) photocatalyst was investigated for the degradation of MB dye from an aqueous system. g-C3N4, BMO and AP photocatalysts bare photocatalysts were synthesized via thermal polycondensation, hydrothermal and co-precipitation methods, respectively. Similarly, binary (GCN/BMO) and ternary heterojunctions (AP/GCN/BMO) was constructed through in-situ hydrothermal and co-precipitation methods, respectively. Morphological and structural analysis validated close interaction amongst Ag3PO4, g-C3N4, and Bi2MoO6 photocatalysts. Furthermore, density functional theory simulations were employed to explore the structural and electronic properties of the bare (Ag3PO4, g-C3N4, and Bi2MoO6) photocatalysts. The photocatalytic degradation experiments revealed that AP/GCN/BMO exhibited highest adsorption and photocatalytic degradation efficacy of methylene blue (MB) dye pollutant as compared to other photocatalysts. The achieved MB dye degradation efficiency of dual Z-scheme AP/GCN/BMO ternary photocatalyst was approx. ~94% within 60 min under visible light exposure which was much greater than pristine and binary photocatalysts. This higher efficiency was accredited to dual Z-scheme type of charge transfer route which boosted photocarriers charge separation and transferal rate. Furthermore, through scavenging experiment, the confirmed reactive species in this type of charge transfer route were •O2? and •OH radicals that efficiently degraded MB dye pollutant. Additionally, the ternary photocatalyst demonstrated good stability and recyclability for up to five successive catalytic cycles with 81% degradation efficiency. The current work extends our understanding of photocatalytic degradation by providing novel strategies for pollutant degradation that successfully degrade contaminants. Also, it promotes the development of more efficient, environmentally friendly waste treatment methods that uses solar/light energy. Graphical Abstract: (Figure presented.) © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2024
The Impact of Antiretroviral Therapy on Mortality in HIV Positive People during Tuberculosis Treatment: A Systematic Review and Meta-Analysis
No full textObjective: To quantify the impact of antiretroviral therapy (ART) on mortality in HIV-positive people during tuberculosis (TB) treatment. Design: We conducted a systematic literature review and meta-analysis. Studies published from 1996 through February 15, 2013, were identified by searching electronic resources (Pubmed and Embase) and conference books, manual searches of references, and expert consultation. Pooled estimates for the outcome of interest were acquired using random effects meta-analysis. Subjects The study population included individuals receiving ART before or during TB treatment. Main Outcome Measures: Main outcome measures were: (i) TB-case fatality ratio (CFR), defined as the proportion of individuals dying during TB treatment and, if mortality in HIV-positive people not on ART was also reported, (ii) the relative risk of death during TB treatment by ART status. Results: Twenty-one studies were included in the systematic review. Random effects pooled meta-analysis estimated the CFR between 8% and 14% (pooled estimate 11%). Among HIV-positive TB cases, those receiving ART had a reduction in mortality during TB treatment of between 44% and 71% (RR = 0.42, 95%CI: 0.29–0.56). Conclusion: Starting ART before or during TB therapy reduces the risk of death during TB treatment by around three-fifths in clinical settings. National programmes should continue to expand coverage of ART for HIV positive in order to control the dual epidemic.Version of Recor
Salvia przewalskii Maxim.
No full text<i>Salvia przewalskii</i> Maxim. <p> Yonekura (2008) described <i>Salvia transhimalaica</i> Yonek. for specimens from Mustang that had previoUsly been identified as <i>S. hians</i>. His Latin diagnosis can be translated as:</p> <p> Species similar to <i>Salvia castanea</i> and <i>S. przewalskii</i> but differing from the former by the straight not sigmoid corolla tube and triangular-hastate leaf with hastate-cordate base, and from the latter in purple-blue corolla and leaves densely tomentose above and densely strigose-tomentose below. It is distinguished from <i>Salvia hians</i> by the purple, not white, lower lip.</p> <p> The Mustang specimens are clearly distinguished from <i>Salvia castanea</i> and <i>S. hians</i> by the characters discussed by Yonekura, but the distinction between them and <i>S. przewalskii</i> is not at all clear. <i>Salvia przewalskii</i> is widespread in China and is found from 2100 to 4000 m in Gansu, Hubei, Sichuan, Xizang and Yunnan. <i>Salvia przewalskii</i> also has pUrplish flowers, and its leaves are tomentose below, but it is a rather variable species and the <i>Flora of China</i> account includes four varieties that are distinguished by differences in their indumentum and flower coloUr (Li & Hedge, 1994). The specimens from Mustang, and others from Manang and Dolpa, show no clear differences from material of <i>Salvia przewalskii</i> at either CSH or E, and there is a complete overlap in floral measUrements. <i>Salvia transhimalaica</i> is therefore considered within the circumscription of <i>S. przewalskii</i> and so is treated here as a synonym.</p> Salvia przewalskii Maxim., Bull. Acad. Imp. Sci. Saint-Pétersbourg 27: 526 (1881). <p> <i>Salvia transhimalaica</i> Yonek., Fl. Mustang: 265, pl. 4 (2008), <b>syn. nov.</b></p> <p> The Nepalese collections are all from trans-Himalayan areas to the north of the main ranges of the Himalayas, growing at elevations between 2810 and 4090 m, where the climate is similar to that of the regions of the Tibetan Plateau where <i>Salvia przewalskii</i> is found. It should be noted that the lower elevational limit of 1100 m reported in the <i>Flora of China</i> is probably incorrect. DUring extensive fieldwork in the region, the second aUthor has rarely seen this species below 2500 m, and the account in <i>Florae Republicae Popularis Sinicae</i> gives a range of 2100 to 4050 m (Wu & Li, 1977).</p> <p> The following specimens, previoUsly identified as <i>Salvia hians</i>, and also as <i>S. castanea</i>, <i>S. lanata</i> Roxb. (= <i>S. mukerjeei</i> Bennet & Raizada), <i>S. nubicola</i> Wall. ex Sweet and <i>S. transhimalaica</i>, are redetermined as <i>S. przewalskii</i>.</p> <p> <i>Specimens examined</i>. NEPAL. <b>Dolpa</b>: Phoksumdo Tal, 3800 m, 5 ix 2014, <i>BRD</i> A274 (E, KATH, TI); Lulo Khola, 13500 ft, 18 ix 1952, <i>O. V. Polunin</i> et al. 3463 (BM, E); Lulo Khola, 13500 ft, 18 ix 1952, <i>O. V. Polunin</i> et al. 3493 (BM, E). <b>Manang</b>: Marsiandi, 12000 ft, 23 vii 1950, <i>D. G. Lowndes</i> 1224 (BM, E); Manang, 12000 ft, 29 vii 1983, <i>R. J. D. McBeath</i> et al. 1546 (E); Lower Pisang, 3000 m, 15 viii 1994, <i>M. Mikage</i> et al. 9485435 (E, KATH); Manang, 3100 m, 24 ix 1969, <i>T. Wraber</i> 396 (BM). <b>Mustang</b>: Samar, 3700–3880 m, 11 vii 2000, <i>Y. Iokawa</i> et al. 20020092 (E); Kagbeni-Muktinath, 2810–3650 m, 11 ix 1999, <i>S. Ishizawa</i> et al. 99911017 (E); Bhona, 3860 m, 16 viii 2002, <i>F. Miyamoto</i> et al. 20220141 (E); Alubari Kharka, 3730 m, 31 vii 2001, <i>S. Noshiro</i> et al. 20104047 (E); Muktinath, 12000 ft, 26 vi 1966, <i>T.B. Shrestha</i> 5460 (BM); Thinigaon, 11500 ft, 24 v 1954, <i>J.D. A. Stainton</i> et al. 1370 (BM, E); Tukuche, 11000 ft, 18 vii 1954, <i>J.D. A. Stainton</i> et al. 1878 (BM, E); Dzong, 12000 ft, 27 vii 1954, <i>J.D. A. Stainton</i> et al. 2023 (BM, E); Ghemi, 12000 ft, 14 viii 1954, <i>J.D. A. Stainton</i> et al. 7229 (BM, E); Muktinath, 13500 ft, 1 ix 1954, <i>J.D. A. Stainton</i> et al. 8055 (BM, E).</p>Published as part of <i>Pendry, Colin A & Wei, Yukun K, 2021, FLORA OF NEPAL NOTULAE I: TAXONOMIC NOTES ON NEPALESE SALVIA, pp. 1-8 in Edinburgh Journal of Botany 78 (331)</i> on pages 6-7, DOI: 10.24823/EJB.2021.331, <a href="http://zenodo.org/record/10590914">http://zenodo.org/record/10590914</a>
Modeling the contribution of lamina 5 neuronal and network dynamics to low frequency EEG phenomena
No full textThe Electroencephalogram (EEG) is an important clinical and research tool in neurophysiology. With the advent of recording techniques, new evidence is emerging on the neuronal populations and wiring in the neocortex. A main challenge is to relate the EEG generation mechanisms to the underlying circuitry of the neocortex. In this paper, we look at the principal intrinsic properties of neocortical cells in layer 5 and their network behavior in simplified simulation models to explain the emergence of several important EEG phenomena such as the alpha rhythms, slow-wave sleep oscillations, and a form of cortical seizure. The models also predict the ability of layer 5 cells to produce a resonance-like neuronal recruitment known as the augmenting response. 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Long-term outcomes of abatacept in individuals at risk of developing rheumatoid arthritis (ALTO): a randomised, double-blind, placebo-controlled trial
No full text\ua9 2026 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license.Background Clinical trials aimed at preventing rheumatoid arthritis in individuals at risk have had variable results. The long-term outcomes of disease interception, however, are not known. We aimed to examine the long-term effect of therapeutic intervention, with emphasis on efficacy and safety. Methods The Arthritis Prevention In the Preclinical Phase of Rheumatoid arthritis with Abatacept (APIPPRA) phase 2b, randomised controlled trial recruited 213 anti-citrullinated protein antibody (ACPA) positive individuals with arthralgia in 28 hospital-based early arthritis clinics in the UK and three in the Netherlands, randomly assigning participants to 52 weekly subcutaneous injections of 125 mg abatacept (n=110) or placebo (n=103), with another 52 weeks of follow-up. The APIPPRA Long-Term Outcome (ALTO) study extended follow-up for between 4 and 8 years and study participants and clinical assessors remained masked to treatment group. The primary outcome was the time from randomisation to development of clinical synovitis in at least three joints, rheumatoid arthritis according to American College of Rheumatology–European Alliance of Associations for Rheumatology 2010 criteria, or first treatment with disease modifying anti-rheumatic drugs, whichever was met first. The primary outcome was also stratified by autoantibody profiles defined at the time of randomisation. People with lived experience of rheumatoid arthritis had input into the APIPPRA study design. The study was registered at ISRCTN (ISRCTN-12680338), and is completed. Findings Between April 26, 2021, and Jan 31, 2023, 143 APIPPRA study participants enrolled in ALTO: 71 in the abatacept group and 72 in the placebo group (mean age 48\ub72 years [SD 11\ub72], 112 [78%] females, 31 [22%] males, 116 [81%] White). Median follow-up time from randomisation was 55 months (IQR 23–74). Primary events increased by 54 to 119. The initial between-group difference in restricted mean arthritis-free survival time observed at 2 years in APIPPRA remained significant at 4 years (4\ub79 months 95% CI 0\ub71–9\ub76; p=0\ub7044), although the magnitude of this difference diminished over time. Assessments of disease activity and patient reported outcomes revealed no significant differences between groups beyond the treatment period. However, although participants with a broad autoantibody profile at baseline were at highest risk of progressing, this subgroup responded better to abatacept. There were 18 serious adverse events in the abatacept group and 13 in the placebo group; none deemed related to study drug. Interpretation In this at-risk population, 1-year treatment with abatacept delayed progression to rheumatoid arthritis for up to 4 years. Those at highest risk of progression have a broad autoantibody profile but are more responsive to abatacept treatment. Funding Bristol Myers Squibb
