74 research outputs found

    Laboratory Testing and Analysis of Joints for Rigid Pavements

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    The primary objective of this study was to analyze the concrete pavement system under nonlinear temperature distribution and vehicle wheel loading. The jointed concrete pavement system consists of concrete slabs with transverse and longitudinal joints, dowel bars (across transverse joints), tie bars (across longitudinal joints), subbase and subgrade soil. Under the loading conditions the pavement structural system may fail by cracking of the concrete slab, loss-of-support of slab due to temperature induced curling, closing and opening of joints, and failure of load transfer devices such as dowel bars, etc. In order to understand the cause of these failures or to achieve an economical design, the state of stress in the pavement system should be determined. It is very difficult to predict the stresses accurately in the pavement system with discontinuities and complex support conditions using conventional classical methods. Therefore, this project uses the ANSYS finite element software. A literature review was performed to identify and evolve an accurate finite element model. It was found from this review that there were difficulties in incorporating the dowel-concrete interface, loss-of-support, contact conditions at the joints, nonlinear temperature distribution, etc. Since there has been no systematic comparison between the experiment and theoretical analysis in the past, the present study conducted the following laboratory testing to determine the respective stiffness quantities: (I) Doweled concrete blocks under bending and shear load, (2) Concrete blocks with tie bars under bending and shear load, (3) Concrete blocks with aggregate interlock joints under shear load, and (4) Concrete blocks with sealed joints under shear load The stiffness values derived from these testing procedures is to be used in the evolution of a finite element model for the concrete pavement system. In addition to this, it is recommended that field measurement of temperature distribution through the thickness of the slab be performed. Finally, a full-scale field testing using FWD is also recommended. The test results obtained from this full-scale testing could be used to assess the validity of the finite element model

    Binary Metal Oxides Thin Films Prepared from Pulsed Laser Deposition

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    The semiconductor industry flourished from a simple Si-based metal oxide semiconductor field effect transistor to an era of MOSFET-based smart materials. In recent decades, researchers have been replacing all the materials required for the MOSFET device. They replaced the substrate with durable materials, lightweight materials, translucent materials and so on. They have came up with the possibility of replacing dielectric silicon dioxide material with high-grade dielectric materials. Even then the channel shift in the MOSFET was the new trend in MOSFET science. From the bulk to the atomic level, transistors have been curiously researched across the globe for the use of electronic devices. This research was also inspired by the different semiconductor materials relevant to the replacement of the dielectric channel/gate. Study focuses on diverse materials such as zinc oxides (ZnO), electrochromic oxides such as molybdenum oxides (including MoO3 and MoO2) and other binary oxides using ZnO and MoO3. The primary objective of this research is to study pulsed laser deposited thin films such as ZnO, MoO3, binary oxides such as binary ZnO /MoO3, ZnO /TiO2 and ZnO/V2O5 and to analyse their IV properties for FET applications. To achieve the goal, the following working elements have been set: investigation of pulsed laser deposited thin film of metal oxides and thin film of binary metal oxide nanostructures with effects of laser repetition and deposition temperatures

    In-orbit Performance of UVIT on ASTROSAT

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    We present the in-orbit performance and the first results from the ultra-violet Imaging telescope (UVIT) on ASTROSAT. UVIT consists of two identical 38cm coaligned telescopes, one for the FUV channel (130-180nm) and the other for the NUV (200-300nm) and VIS (320-550nm) channels, with a field of view of 28 arcminarcmin. The FUV and the NUV detectors are operated in the high gain photon counting mode whereas the VIS detector is operated in the low gain integration mode. The FUV and NUV channels have filters and gratings, whereas the VIS channel has filters. The ASTROSAT was launched on 28th September 2015. The performance verification of UVIT was carried out after the opening of the UVIT doors on 30th November 2015, till the end of March 2016 within the allotted time of 50 days for calibration. All the on-board systems were found to be working satisfactorily. During the PV phase, the UVIT observed several calibration sources to characterise the instrument and a few objects to demonstrate the capability of the UVIT. The resolution of the UVIT was found to be about 1.4 - 1.7 arcsecarcsec in the FUV and NUV. The sensitivity in various filters were calibrated using standard stars (white dwarfs), to estimate the zero-point magnitudes as well as the flux conversion factor. The gratings were also calibrated to estimate their resolution as well as effective area. The sensitivity of the filters were found to be reduced up to 15\% with respect to the ground calibrations. The sensitivity variation is monitored on a monthly basis. UVIT is all set to roll out science results with its imaging capability with good resolution and large field of view, capability to sample the UV spectral region using different filters and capability to perform variability studies in the UV.Comment: 10 pages, To appear in SPIE conference proceedings, SPIE conference paper, 201

    Federated learning enables big data for rare cancer boundary detection.

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    Although machine learning (ML) has shown promise across disciplines, out-of-sample generalizability is concerning. This is currently addressed by sharing multi-site data, but such centralization is challenging/infeasible to scale due to various limitations. Federated ML (FL) provides an alternative paradigm for accurate and generalizable ML, by only sharing numerical model updates. Here we present the largest FL study to-date, involving data from 71 sites across 6 continents, to generate an automatic tumor boundary detector for the rare disease of glioblastoma, reporting the largest such dataset in the literature (n = 6, 314). We demonstrate a 33% delineation improvement for the surgically targetable tumor, and 23% for the complete tumor extent, over a publicly trained model. We anticipate our study to: 1) enable more healthcare studies informed by large diverse data, ensuring meaningful results for rare diseases and underrepresented populations, 2) facilitate further analyses for glioblastoma by releasing our consensus model, and 3) demonstrate the FL effectiveness at such scale and task-complexity as a paradigm shift for multi-site collaborations, alleviating the need for data-sharing

    Author Correction: Federated learning enables big data for rare cancer boundary detection.

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    10.1038/s41467-023-36188-7NATURE COMMUNICATIONS14

    A Multicenter, Randomized, Placebo‐Controlled Trial of Atorvastatin for the Primary Prevention of Cardiovascular Events in Patients With Rheumatoid Arthritis

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    Objective: Rheumatoid arthritis (RA) is associated with increased cardiovascular event (CVE) risk. The impact of statins in RA is not established. We assessed whether atorvastatin is superior to placebo for the primary prevention of CVEs in RA patients. Methods: A randomized, double‐blind, placebo‐controlled trial was designed to detect a 32% CVE risk reduction based on an estimated 1.6% per annum event rate with 80% power at P 50 years or with a disease duration of >10 years who did not have clinical atherosclerosis, diabetes, or myopathy received atorvastatin 40 mg daily or matching placebo. The primary end point was a composite of cardiovascular death, myocardial infarction, stroke, transient ischemic attack, or any arterial revascularization. Secondary and tertiary end points included plasma lipids and safety. Results: A total of 3,002 patients (mean age 61 years; 74% female) were followed up for a median of 2.51 years (interquartile range [IQR] 1.90, 3.49 years) (7,827 patient‐years). The study was terminated early due to a lower than expected event rate (0.70% per annum). Of the 1,504 patients receiving atorvastatin, 24 (1.6%) experienced a primary end point, compared with 36 (2.4%) of the 1,498 receiving placebo (hazard ratio [HR] 0.66 [95% confidence interval (95% CI) 0.39, 1.11]; P = 0.115 and adjusted HR 0.60 [95% CI 0.32, 1.15]; P = 0.127). At trial end, patients receiving atorvastatin had a mean ± SD low‐density lipoprotein (LDL) cholesterol level 0.77 ± 0.04 mmoles/liter lower than those receiving placebo (P < 0.0001). C‐reactive protein level was also significantly lower in the atorvastatin group than the placebo group (median 2.59 mg/liter [IQR 0.94, 6.08] versus 3.60 mg/liter [IQR 1.47, 7.49]; P < 0.0001). CVE risk reduction per mmole/liter reduction in LDL cholesterol was 42% (95% CI −14%, 70%). The rates of adverse events in the atorvastatin group (n = 298 [19.8%]) and placebo group (n = 292 [19.5%]) were similar. Conclusion: Atorvastatin 40 mg daily is safe and results in a significantly greater reduction of LDL cholesterol level than placebo in patients with RA. The 34% CVE risk reduction is consistent with the Cholesterol Treatment Trialists’ Collaboration meta‐analysis of statin effects in other populations
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