Study of the Choice of Excitation Frequency for Sub Surface Defect Detection in Electrically Thick Conducting Specimen Using Eddy Current Testing

Understanding the scope and limitations of non-destructive testing procedure is essential for selecting the appropriate test parameters for material inspection. This paper presents the scope of material (\( \delta_{s} \)) and probe dependent (\( \delta_{t} \)) penetration depths for determining the optimal test frequency (\( f_{opt} ) \) for detection of sub surface defects in electrically thick conducting specimens. Numerical modelling is carried out for a pancake coil above an electrically thick aluminium plate, \( t/\delta_{t} \)?>?1, to study the influence of the EC probe and defect location (\( t_{df} \)) on the test frequency for near and deep sub surface defects. The study concludes that the optimal test frequency, \( f_{opt} \) for detection of deep sub surface defects (\( t_{df} /t \approx 1 \)) is determined by the probe dependent skin depth, \( \delta_{t} \), and the plate thickness is related to \( f_{opt} \) by, \( t \propto 1/\sqrt {f_{opt} } \). The numerical observations were experimentally validated for machined sub surface notches on a 10 mm thick (\( t \)) aluminium plate.     

Formation of As–As Interlayer Bonding in the cT Phase of EuFe<Subscript>2</Subscript>As<Subscript>2</Subscript> and CeFeAsO Under Pressure from First Principle

The electronic band structure and structural phase stability of EuFe₂As₂ and CeFeAsO compounds were studied using the full-potential linearized augmented plane wave (FP-LAPW) method implemented using WIEN2k. To calculate the structural stability and phase transition of these compounds, the total energies have been computed as a function of reduced volumes and fitted with the Birch–Murnaghan equation. The calculated lattice parameters are found to be in agreement with the available experimental data. The present results show that EuFe₂As₂ and CeFeAsO compounds undergo structural phase transition from body-centered tetragonal (BCT) into collapsed tetragonal (cT) and tetragonal (T) into cT phase under pressure. The calculated phase transition pressures are in agreement with recent experimental data. The calculated valence charge density of collapsed tetragonal phase reveals that As–As interactions found to be stronger under pressure.     

Causes and consequences of inflammation on anemia management in hemodialysis patients

Inflammation is common among hemodialysis patients, and evidence is accumulating to suggest that inflammation is a major contributor to morbidity and mortality. Several factors have been suggested as potential causes of inflammation, including infections and the atherosclerosis process, as well as etiologies directly related to kidney disease such as reduced renal function and dialysis. Among several inflammatory biomarkers investigated, serum C-reactive protein (CRP) is the most widely used. In hemodialysis patients, raised CRP levels have been shown to be predictive of cardiovascular events, hospitalization, and all-cause and cardiovascular mortality. Elevated CRP levels may correlate with comorbidities and intercurrent events, all of which may impact the response to erythropoiesis-stimulating agents (ESAs) and lead to higher ESA doses. Most dialysis facilities do not routinely measure CRP, despite recommendations by the National Kidney Foundation's Kidney Disease Outcomes Quality Initiative. Regular measurement of CRP levels may help providers to understand change in ESA dosing and identify patients at risk for cardiovascular events. This review explores the inter-relationships between inflammation, CRP levels, and anemia management in patients receiving hemodialysis.     

Acoustic Emission Study on Effect of Stress Triaxiality on Damage Micromechanisms in Near Alpha Titanium Alloy

Acoustic Emission (AE) studies have been performed on smooth and notched specimens of a near alpha titanium alloy under monotonic loading condition to study the effect of stress triaxiality on damage micromechanisms. The damage in the notched specimen was found to be of cleavage type as against the ductile type of damage in smooth specimen. This difference was distinguished in the AE energy evolution with notched specimen producing higher energy rate with lower total energy than that of smooth specimen.     

Catalytic activity of polymer-bound Ru(III)-EDTA complex

Chloromethylated styrene-divinylbenzene copolymer was chemically modified with ethylenediaminetetraacetic acid ligand. Catalytically active polymer containing Ru(III) moieties were synthesized from this polymeric ligand. They were characterized using FTIR, UV-vis, SEM, ESR and TGA. Other physico-chemical properties such as bulk density, surface area, moisture content and swelling behaviour in different solvents were also studied. The polymer bound complex was used to study hydrogenation of 1-hexene ton-hexane under mild conditions. Influence of [1-hexene], [catalyst], temperature and nature of the solvent on the rate of the reaction was investigated. A rate expression is proposed based on the observed initial rate data. Recycling efficiency of the catalyst has also been studied.     

Combined buoyancy and viscous effects in liquid–liquid flows in a vertical pipe

This paper presents experimental and numerical results of interfacial dynamics of liquid–liquid flows when an immiscible core liquid is introduced into a continuous liquid flow. The fully developed flow model predicts multiple solutions of the jet diameter over a range of dimensionless numbers: flow rate ratio, viscosity ratio, Bond and Capillary numbers. Experiments have been carried out using Polyethylene Glycol (PEG) and Canola oil to investigate the realizability of the three possible solutions predicted by the fully developed flow model. The measured values of inner fluid radii agree very well with the lower branch of the three branched solution while deviating from the top branch beyond a critical flow ratio value. This deviation is attributed to the fact that the flow develops a non-axisymmetric solution at this critical point. Computational fluid dynamics simulations have also been performed to examine the developing core annular flow and to compare the analytical solution results of liquid jet radius. The results predicted by numerical simulations agree very well with both the lower and upper branches of solution predicted by the analytical theory.     

An example of almost universally observable vector fields on P(R)

Using methods of dynamical systems, we construct examples of smooth, almost universally observable vector fields on the projective 1-space. These vector fields are non-linear, non-autonomous and their time dependence is almost periodic.     

Support vector regression based modeling of pier scour using field data

This paper investigates the potential of support vector machines based regression approach to model the local scour around bridge piers using field data. A dataset of consisting of 232 pier scour measurements taken from BSDMS were used for this analysis. Results obtained by using radial basis function and polynomial kernel based Support vector regression were compared with four empirical relation as well as with a backpropagation neural network and generalized regression neural network. A total of 154 data were used for training different algorithms whereas remaining 78 data were used to test the created model. A coefficient of determination value of 0.897 (root mean square error=0.356) was achieved by radial basis kernel based support vector regression in comparison to 0.880 and 0.835 (root mean square error=0.388 and 0.438) by backpropagation neural and generalized regression neural network. Comparisons of results with four predictive equations suggest an improved performance by support vector regression. Results with dimensionless data using all three algorithms suggest a better performance by dimensional data with this dataset. Sensitivity analysis suggests the importance of depth of flow and pier width in predicting the scour depth when using support vector regression based modeling approach.     

Dynamic proteome in enigmatic preeclampsia: an account of molecular mechanisms and biomarker discovery

The coevolution of genomics and proteomics has led to advancements in the field of diagnosis and molecular mechanisms of disease. Proteomics is now stepping into the field of obstetrics, where early diagnosis of pregnancy complication such as preeclampsia (PE) is imperative. PE is a multifactorial disease characterized by hypertension with proteinuria, which is a leading cause of maternal and neonatal morbidity and mortality occurring in 5-7% of pregnancies worldwide. This review discusses the probable molecular mechanisms that lead to PE and summarizes the proteomics research carried out in understanding the pathogenicity of PE, and for identifying the candidate biomarker for diagnosis of the disease.     

Meso-scale studies in fracture of concrete: A numerical simulation

The fracture behaviour of concrete is complex due to highly heterogeneous nature of the material. The heterogeneity of concrete manifests itself at various scales. At mesoscale, the presence of aggregates influences the strength of concrete by developing a zone of weakness in the form of aggregate–matrix interface. These lead to an increased distributed micro-cracking and enhances the energy absorption capacity of the material. The energy absorption capacity of structure is dependent not only on material properties but also on structural geometry and loading conditions. The present work attempts to identify the material and structural parameters that influence the overall behaviour, by using discrete numerical modelling of the material at mesoscale. Lattice modelling, a technique to model the heterogeneity using lattice elements is used to study the fracture behaviour of the material. Effect of aggregate volume fraction, specimen thickness and depth on the global behaviour is studied.