One of the fundamental factors contributing to the spatiotemporal inaccuracy in climate modeling is the mapping of solution field data between different discretizations and numerical grids used in ...the coupled component models. The typical climate computational workflow involves evaluation and serialization of the remapping weights during the preprocessing step, which is then consumed by the coupled driver infrastructure during simulation to compute field projections. Tools like Earth System Modeling Framework (ESMF) (Hill et al., 2004) and TempestRemap (Ullrich et al., 2013) offer capability to generate conservative remapping weights, while the Model Coupling Toolkit (MCT) (Larson et al., 2001) that is utilized in many production climate models exposes functionality to make use of the operators to solve the coupled problem. However, such multistep processes present several hurdles in terms of the scientific workflow and impede research productivity. In order to overcome these limitations, we present a fully integrated infrastructure based on the Mesh Oriented datABase (MOAB) (Tautges et al., 2004; Mahadevan et al., 2015) library, which allows for a complete description of the numerical grids and solution data used in each submodel. Through a scalable advancing-front intersection algorithm, the supermesh of the source and target grids are computed, which is then used to assemble the high-order, conservative, and monotonicity-preserving remapping weights between discretization specifications. The Fortran-compatible interfaces in MOAB are utilized to directly link the submodels in the Energy Exascale Earth System Model (E3SM) to enable online remapping strategies in order to simplify the coupled workflow process. We demonstrate the superior computational efficiency of the remapping algorithms in comparison with other state-of-the-science tools and present strong scaling results on large-scale machines for computing remapping weights between the spectral element atmosphere and finite volume discretizations on the polygonal ocean grids.
► Surrogate modeling for non-planar fatigue crack growth under multi-axial loading. ► Non-parametric crack shape representation for crack growth with complex shapes. ► Prediction of crack front ...evolution for multiaxial variable amplitude load histories. ► Illustration of accurate prediction of crack growth in a cylindrical component.
This paper presents the development of a surrogate modeling technique for efficient non-planar fatigue crack growth analysis in mechanical components under multi-axial loading. Non-planar crack fronts are freely deformable space curves and require a high-dimensional representation. The large number of Cartesian co-ordinate variables involved in crack front representation makes it prohibitively expensive to train surrogate models for crack growth. Therefore, in our previous work, the crack shape was approximated using a planar parametrized representation. However, the parametrized representation limits the choice of crack shapes that can be considered. This paper presents the development of a non-parametric crack shape representation that allows for construction of a surrogate model for non-planar crack growth with complex crack shapes. The surrogate model is trained using a few runs of high-fidelity 3D simulations and predicts the evolution of a non-planar crack front under a given multi-axial, variable amplitude load history. We first parametrize the crack fronts as 3D spline curves with a fixed number of nodes. Instead of modeling the crack growth in this high dimensional data space, we project the data to a lower dimensional space using Principal Component Analysis (PCA) and then model the crack growth in this lower dimensional space. Finally, the predicted crack fronts are recovered using PCA back to the original data space. The proposed crack representation, growth modeling and recovery are illustrated using training points gathered from high-fidelity 3-D finite element simulations of non-planar crack growth in a cylindrical component similar to a rotorcraft mast, and the ability of the surrogate model to accurately predict the evolution of the crack growth over entire load histories is demonstrated.
The precipitation strengthening behavior of 304HCu austenitic stainless steel during isothermal aging at 650 °C is studied under 10 and 20 pct prior cold-worked conditions. The age hardening behavior ...under these cold-working conditions have been studied using hardness and electrical conductivity measurements. The analysis of electrical conductivity and hardness variation, during isothermal aging at 650 °C using the Johnson–Mehl–Avrami equation, indicates an increase in precipitation kinetics in the matrix, influenced by the dislocations formed during cold working. Further, XRD profiles of different cold-worked samples obtained from the INDUS-2 synchrotron are able to indicate the formation of very fine precipitates during thermal aging and these findings are corroborated with conductivity and hardness changes. The observed change in precipitation kinetics due to deformation is analyzed to evaluate an equivalent change in activation energy which is attributed to an equivalent of increase in aging temperature.
Myotonic dystrophy type 1(DM1) is the prototype for diseases caused by RNA toxicity. RNAs from the mutant allele contain an expanded (CUG)n tract within the 3' untranslated region of the dystrophia ...myotonica protein kinase (DMPK) gene. The toxic RNAs affect the function of RNA binding proteins leading to sequestration of muscleblind-like (MBNL) proteins and increased levels of CELF1 (CUGBP, Elav-like family member 1). The mechanism for increased CELF1 is not very clear. One favored proposition is hyper-phosphorylation of CELF1 by Protein Kinase C alpha (PKCα) leading to increased CELF1 stability. However, most of the evidence supporting a role for PKC-α relies on pharmacological inhibition of PKC. To further investigate the role of PKCs in the pathogenesis of RNA toxicity, we generated transgenic mice with RNA toxicity that lacked both the PKCα and PKCβ isoforms. We find that these mice show similar disease progression as mice wildtype for the PKC isoforms. Additionally, the expression of CELF1 is also not affected by deficiency of PKCα and PKCβ in these RNA toxicity mice. These data suggest that disease phenotypes of these RNA toxicity mice are independent of PKCα and PKCβ.
In fast breeder reactors, the quality of fuel pin end plug welds is very important because the presence of any weld defect can cause fission products to be released into the coolant circuit. Among ...the various defects that can form during welding, a root defect at the end plug weld joint
is the most prominent type observed in fuel pins. A conventional X-ray film radiographic procedure for end plug welds of fuel pins inserted in a stainless steel (SS) shape correction block with a thickness of 7 mm will limit the minimum detectable wall thickness difference to 1.1% of the specimen
thickness due to film gradient and film granularity factors. In the present work, with a standard X-ray digital radiographic data acquisition procedure and optimised radiographic exposure conditions (kV, mAs, etc), the normalised signal-to-noise ratio (SNRn) achieved is 140, which
limits the detectable wall thickness difference to 2.8% of the specimen thickness. Hence, a modified digital X-ray radiographic inspection procedure is proposed to assess the quality of end plug welded fuel pins using a suitable X-ray detector calibration technique. The structural noise and
pixel intensity variations between the flat-panel pixel elements are minimised using this modified procedure, which results in an order of magnitude increase in the SNRn of the radiographic images. Following implementation of this procedure with end plug welds, the X-ray images
show that the achievable wall thickness difference is enhanced to 0.9% of the specimen thickness and microdefects are clearly observed in the welds.
The prospect of graft loss is a problem faced by all transplant recipients, and retransplantation is often an option when loss occurs. To assess current trends in retransplantation, we analyzed data ...for retransplant candidates and recipients over the last 10 years, as well as current outcomes. During 2005, retransplant candidates represented 13.5%, 7.9%, 4.1% and 5.5% of all newly registered kidney, liver, heart and lung candidates, respectively. At the end of 2005, candidates for retransplantation accounted for 15.3% of kidney transplant candidates, and lower proportions of liver (5.1%), heart (5.3%) and lung (3.3%) candidates. Retransplants represented 12.4% of kidney, 9.0% of liver, 4.7% of heart and 5.3% of lung transplants performed in 2005. The absolute number of retransplants has grown most notably in kidney transplantation, increasing 40% over the last 10 years; the relative growth of retransplantation was most marked in heart and lung transplantation, increasing 66% and 217%, respectively. The growth of liver retransplantation was only 11%. Unadjusted graft survival remains significantly lower after retransplantation in the most recent cohorts analyzed. Even with careful case mix adjustments, the risk of graft failure following retransplantation is significantly higher than that observed for primary transplants.
To evaluate the predictive value of Computed Tomography Angiography (CTA) measurements of the RVOT for transcatheter valve sizing.
Transcatheter pulmonary valve replacement (TPVR) provides an ...alternative to surgery in patients with right ventricular outflow tract (RVOT) dysfunction. We studied 18 patients who underwent catheterization for potential TPVR to determine whether CT imaging can be used to accurately predict implant size.
Cases were grouped by RVOT characteristics: native or transannular patch (n = 8), conduit (n = 5) or bioprosthetic valve (n = 5). TPVR was undertaken in 14/18 cases, after balloon-sizing was used to confirm suitability and select implant size. Retrospective CT measurements of the RVOT (circumference-derived (Dcirc) and area-derived (Darea) diameters) were obtained at the level of the annulus, bioprosthesis or conduit. Using manufacturer sizing guidance, a valve size was generated and a predicted valve category assigned: (1) <18 mm, (2) 18–20 mm, (3) 22–23 mm, (4) 26–29 mm and (5) >29 mm. Predicted and implanted valves were compared for inter-rater agreement using Cohen’s kappa coefficient.
The median age of patients was 37 years old (IQR: 30–49); 55% were male. Diagnoses included: Tetralogy of Fallot (12/18), d-Transposition repair (3/18), congenital pulmonary stenosis (2/18) and carcinoid heart disease (1/18). Measurements of Darea (κ = 0.697, p < 0.01) and Dcirc (κ = 0.540, p < 0.01) were good predictors of implanted valve size. When patients with RVOT conduits were excluded, the predictive accuracy improved for Darea (κ = 0.882, p < 0.01) and Dcirc (κ = 0.882, p < 0.01).
CT measurement of the RVOT, using Darea or Dcirc, can predict prosthetic valve sizing in TPVR. These measurements are less predictive in patients with conduits, compared to those with a native RVOT or pulmonic bioprosthesis.
We studied 18 patients who underwent catheterization for TPVR to determine whether CT imaging could be used to accurately predict implant size. Retrospective RVOT measurements were used to generate a predicted valve size, which was compared with implanted valve size for inter-rater agreement. Measurements of Darea (κ = 0.697, p < 0.01) and Dcirc (κ = 0.540, p < 0.01) were good predictors of implanted valve size. When cases with RVOT conduits were excluded, the predictive accuracy improved for Darea (κ = 0.882, p < 0.01) and Dcirc (κ = 0.882, p < 0.01). CT measurement of the RVOT can accurately predict prosthetic valve sizing in TPVR. These measurements are less predictive in patients with conduits.
Literature indicates that altered plantar loading in people with diabetes could trigger changes in plantar soft tissue biomechanics which, in turn, could affect the risk for ulceration. To stimulate ...more research in this area, this study uses in vivo testing to investigate the link between plantar loading and tissue hardness.
Tissue hardness and plantar pressure distribution were measured for six plantar areas in 39 people with diabetes and peripheral neuropathy.
Spearman correlation analysis revealed that increased pressure time integral at the 1st metatarsal-head region (r = -0.354, n = 39, P = 0.027) or at the heel (r = -0.378, n = 39, P = 0.018) was associated with reduced hardness in the same regions. After accounting for confounding parameters, generalised estimating equations analysis also showed that 10% increase in pressure time integral at the heel was associated with ≈ 1 unit reduction in hardness in the same region.
For the first time, this study reveals that people with diabetes and neuropathy who tend to load their feet more heavily also tend to have plantar soft tissues with lower hardness. The observed difference in tissue hardness is likely to affect the tissue’s vulnerability to overload injury. More research will be needed to explore the implications of the observed association for the risk of ulceration.
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